SC 13D

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D
(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE
13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(a)

ULTRA CLEAN HOLDINGS, INC.

(Name of Issuer)

COMMON STOCK, $0.01 PAR VALUE

(Title of Class of Securities)

90385V 10 7

(CUSIP Number)

Jack Sexton
Ultra Clean Holdings, Inc.
150 Independence Drive
Menlo Park, CA 94025

(Name, Address and Telephone Number of Person Authorized
to Receive Notices and Communications)

June 29, 2006

(Date of Event which Requires Filing of this Statement)

     If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e), 13d-1(f) or 13d-1(g), check the following box. o

     Note. Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See Rule 13d-7 for other parties to whom copies are to be sent.

      The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose Section 18 of the Securities Exchange Act of 1934 or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act.

CUSIP No. 90385v 10 7 13D Page 2 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Francisco Partners GP, LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware, U.S.A.
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 4,167,400
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 4,167,400
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON IC

¹ Includes 2,471,907 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

CUSIP No. 90385v 10 7 13D Page 3 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Francisco Partners, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware, U.S.A.
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 4,167,400
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 4,167,400
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON IC

¹ Includes 2,471,907 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

CUSIP No. 90385v 10 7 13D Page 4 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) FP-Ultra Clean, L.L.C.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION State of Delaware, U.S.A.
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 4,167,400
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 4,167,400
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON IC

¹ Includes 2,471,907 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

CUSIP No. 90385v 10 7 13D Page 5 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 1,793,860
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 1,793,860
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES x
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON OO

¹ Includes 4,845,447 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

CUSIP No. 90385v 10 7 13D Page 6 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2004 Irrevocable Trust Under Agreement dated June 4, 2004
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 40,168
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 40,168
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES x
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON OO

¹ Includes 6,599,139 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

CUSIP No. 90385v 10 7 13D Page 7 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) David Hongyu Wu and Winnie Wei Zhen Wu, as trustees of the Chen Minors Irrevocable Trust
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 24,719
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 24,719
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES x
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON OO

¹ Includes 6,614,588 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

CUSIP No. 90385v 10 7 13D Page 8 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Joe Chen and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 474,116
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 474,116
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES x
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON OO

¹ Includes 6,165,191 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

CUSIP No. 90385v 10 7 13D Page 9 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Victor Mezhvinsky
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 40,168
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 40,168
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES x
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON IN

¹ Includes 6,599,139 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

CUSIP No. 90385v 10 7 13D Page 10 of 16 Pages

1	NAME OF REPORTING PERSONS I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY) Frank Moreman
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (a) x  (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e) o
6	CITIZENSHIP OR PLACE OF ORGANIZATION United States
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH		7	SOLE VOTING POWER 98,876
		8	SHARED VOTING POWER 6,639,3071
		9	SOLE DISPOSITIVE POWER 98,876
		10	SHARED DISPOSITIVE POWER 6,639,3071
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 6,639,3071
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES x
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 31.9%1
14	TYPE OF REPORTING PERSON IN

¹ Includes 6,540,431 shares of Common Stock of the other Reporting Persons who are part of the group filing this Schedule 13D.

     This Schedule 13D is being filed on behalf of Francisco Partners GP LLC, Francisco Partners, L.P. and FP-Ultra Clean, L.L.C. (together with Francisco Partners GP, LLC and Francisco Partners, L.P., “FP”); Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988 (the “Mezhvinsky Living Trust”); Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2004 Irrevocable Trust Under Agreement dated June 4, 2004 (the “Joshua Trust”); David Hongyu Wu and Winnie Wei Zhen Wu, as trustees of the Chen Minors Irrevocable Trust (the “Chen Minors Trust”); Joe Chen and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002 (the “Chen Revocable Trust”); Victor Mezhvinsky; and Frank Moreman (together with FP, the Mezhvinsky Living Trust, the Joshua Trust, the Chen Minors Trust, the Chen Revocable Trust and Victor Mezhvinsky, the “Reporting Persons”) with respect to the shares of common stock, par value $.001 of Ultra Clean Holdings, Inc. (the “Common Stock”). The Reporting Persons are jointly filing this Schedule 13D because they are deemed to constitute a “group” within the meaning of Section 13(d) of the Securities and Exchange Act of 1934, as amended (the “Exchange Act”), solely by reason of having executed the Stockholders’ Agreement described below. All information in this Schedule 13D concerning any Reporting Person is being supplied solely by such Reporting Person, and only such Reporting Person shall be deemed responsible for the accuracy of such information. Statements made herein concerning the Reporting Persons are made severally by the Reporting Persons and not jointly, and no Reporting Person shall be responsible for the accuracy of information contained herein which has been supplied by or relates to another Reporting Person.

   Item 1. Security and Issuer.

     This statement on Schedule 13D relates to the shares of Common Stock of Ultra Clean Holdings, Inc., a Delaware corporation (the “Issuer”). The principal executive offices of the Issuer are located at 150 Independence Drive, Menlo Park, California 94025.

   Item 2. Identity and Background.

     (a) This statement is being filed by the Reporting Persons.

     (b) The principal addresses of the Reporting Persons are:

Francisco Partners GP, LLC, a Delaware limited liability company (“FPGP”)
Francisco Partners L.P., a Delaware limited partnership (“FPLP”)
FP-Ultra Clean, L.L.C., a Delaware limited liability company (“FP-Ultra Clean”)
2882 Sand Hill Road, Suite 280
Menlo Park, CA 94025

FPGP is the managing member of FP-Ultra Clean and the general partner of FPLP. FP-Ultra Clean is the record and beneficial owner of the shares of Common Stock in respect of which this Schedule 13D is being filed. Pursuant to Rule 13d-3 of the Securities Exchange Act of 1934, as amended, each of FPGP and FPLP may be deemed the beneficial owner of the shares of Common Stock in respect of which this Schedule 13D is being filed.

The Mezhvinsky Living Trust
10 Hampton Court
Hillsborough, CA 94010

The Joshua Trust
300 Third Street, #502
San Francisco, CA 94107

The Chen Minors Trust
260 Loyola Drive
Millbrae, CA 94030

The Chen Revocable Trust
260 Loyola Drive
Millbrae, CA 94030

11

Victor Mezhvinsky
300 Third Street, #502
San Francisco, CA 94107

Frank Moreman
1276 11th Avenue
San Francisco, CA 94122

     (c) During the last five years, none of the Reporting Persons has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors).

     (d) During the last five years, none of the Reporting Persons has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject, to federal or state securities laws or finding any violation with respect to such laws.

     (e) Each of the Reporting Persons is a United States citizen.

   Item 3. Source and Amount of Funds or Other Consideration.

     FP-Ultra Clean purchased, prior to the 2004 initial public offering of the Common Stock, all shares of Common Stock that it currently holds. FP previously reported its acquisition of shares of Common Stock on Schedule 13G filed with the Securities and Exchange Commission on October 13, 2004. Each of the other Reporting Persons acquired the shares of Common Stock that they currently hold as partial consideration for the acquisition by Issuer, pursuant to the Agreement and Plan of Merger and Reorganization dated as of June 29, 2006 (the “Merger Agreement”) among Sieger Engineering, Inc., Leonid Mezhvinsky, Bob Acquisition Inc., Pete Acquisition LLC, the Mezhvinsky Living Trust, the Chen Revocable Trust, Victor Mezhvinsky, the Joshua Trust, the Chen Minors Trust, Frank Moreman and Leonid Mezhvinsky as Sellers’ Agent, of all the outstanding shares of Sieger Engineering, Inc. (the “Merger”).

   Item 4. Purpose of Transaction.

     As described more fully in Item 6, in conjunction with the Merger, the Issuer, FP-Ultra Clean, the Mezhvinsky Living Trust, the Chen Revocable Trust, Victor Mezhvinsky, the Joshua Trust, the Chen Minors Trust and Frank Moreman have entered into the Shareholders’ Agreement whereby each holder of shares of Common Stock has agreed to vote such shares in favor of certain nominees to the Issuer’s Board of Directors (“the Board”).

     Each Reporting Person may, from time to time and subject to the Stockholders’ Agreement and the Lockup Agreement described below, increase, reduce or dispose of his or her investment in the Issuer, depending on general economic conditions, economic conditions in the markets in which the Issuer operates, the market price securities of the Issuer, the availability of funds, borrowing costs, other opportunities available to such Reporting Person and other considerations.

     Pursuant to the Stockholders’ Agreement, the Issuer will recommend to the Board that Leonid Mezhvinsky be nominated as a member of the Board when another independent director is appointed to the Board.

     Except as set forth in this Item 4, none of the Reporting Persons has any present plans or proposals which relate to or would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D.

   Item 5. Interest in Securities of the Issuer.

     (a) As a result of the Stockholders’ Agreement, the Reporting Persons may be deemed the beneficial owners of 6,639,307 shares, constituting approximately 31.9% of the issued and outstanding shares, of Common Stock of the Issuer, based on the number of shares of Common Stock outstanding as of July 11, 2006.

     FP-Ultra Clean is the record and beneficial owner of 4,167,400 shares (the “FP Shares”), constituting approximately 20.0% of the issued and outstanding shares of Common Stock. FPGP is the managing member of

12

FP-Ultra Clean LLC and the general partner of FPLP. In its capacity as the holder of the majority of membership interests in FP-Ultra Clean, FPLP may also be deemed the beneficial owner of the FP Shares. In its capacity as the managing member of FP-Ultra Clean and the general partner of FPLP, FPGP may also be deemed the beneficial owner of the FP Shares.

     The Mezhvinsky Living Trust is the beneficial owner of 1,793,869 shares, constituting approximately 8.6% of the issued and outstanding shares of Common Stock.

     The Joshua Trust is the beneficial owner of 40,168 shares, constituting approximately 0.2% of the issued and outstanding shares of Common Stock.

     The Chen Minors Trust is the beneficial owner of 24,719 shares, constituting approximately 0.1% of the issued and outstanding shares of Common Stock of the Issuer.

     The Chen Revocable Trust is the beneficial owner of 474,116 shares, constituting approximately 2.3% of the issued and outstanding shares of Common Stock of the Issuer.

     Victor Mezhvinsky is the beneficial owner of 40,168 shares, constituting approximately 0.2% of the issued and outstanding shares of Common Stock of the Issuer.

     Frank Moreman is the beneficial owner of 98,876 shares, constituting approximately 0.5% of the issued and outstanding shares of Common Stock of the Issuer.

     (b) As a result of the Stockholders’ Agreement, the Reporting Persons may be deemed to have shared voting and dispositive power with respect to 6,639,307 shares.

     FP may be deemed to have sole voting and dispositive power with respect to 4,167,400 shares and shared voting and dispositive power with respect to the remaining 2,471,907 shares held by the other Reporting Persons.

     The Mezhvinsky Living Trust may be deemed to have sole voting and dispositive power with respect to 1,793,869 shares and shared voting and dispositive power with respect to the remaining 4,845,447 shares held by the other Reporting Persons.

     The Joshua Trust may be deemed to have sole voting and dispositive power with respect to 40,168 shares and shared voting and dispositive power with respect to the remaining 6,599,139 shares held by the other Reporting Persons.

     The Chen Minors Trust may be deemed to have sole voting and dispositive power with respect to 24,719 shares and shared voting and dispositive power with respect to the remaining 6,614,588 shares held by the other Reporting Persons.

     The Chen Revocable Trust may be deemed to have sole voting and dispositive power with respect to 474,116 shares and shared voting and dispositive power with respect to the remaining 6,165,191 shares held by the other Reporting Persons.

     Victor Mezhvinsky may be deemed to have sole voting and dispositive power with respect to 40,168 shares and shared voting and dispositive power with respect to the remaining 6,599,139 shares held by the other Reporting Persons.

     Frank Moreman may be deemed to have sole voting and dispositive power with respect to 98,876 shares and shared voting and dispositive power with respect to the remaining 6,540,431 shares held by the other Reporting Persons.

     (c) Other than the Merger, there have been no transactions with respect to the Common Stock effected during the past 60 days by any of the Reporting Persons.

     (e) Not applicable.

13

   Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.

     Pursuant to the Merger Agreement, each of the Mezhvinsky Living Trust, the Chen Revocable Trust, Victor Mezhvinsky, the Joshua Trust, the Chen Minors Trust and Frank Moreman (collectively, the “Sieger Shareholders”) received shares of Common Stock as consideration for the Merger. On the same day (i) the Issuer, FP-Ultra Clean and the Sieger Shareholders entered into the Stockholders’ Agreement, (ii) the Issuer, FP-Ultra Clean and the Sieger Shareholders entered into an Amended and Restated Registration Rights Agreement (the “Registration Rights Agreement”) and (iii) the Issuer, Leonid Mezhvinsky and the Sieger Shareholders entered into a Lockup Agreement (the “Lockup Agreement”).

     The Stockholders’ Agreement provides that one director nominee to the Board will be Leonid Mezhvinsky (immediately following the appointment of an additional independent director to the Board) so long as (A) he is employed by the Issuer, (B) the Sieger Shareholders collectively hold more than 247,191 shares of Common Stock and (C) FP-Ultra Clean holds more than 416,740 shares of Common Stock. Pursuant to the Stockholders’ Agreement FP-Ultra Clean retains its right to nominate a number of directors that decreases in relation to the proportion of outstanding shares of the Issuer’s common stock held by FP-Ultra Clean and to nominate, together with the Chief Executive Officer of the Issuer, up to four additional directors. These nomination rights are subject to the powers and duties of the Issuer’s Nominating and Corporate Governance Committee and applicable rules of the Nasdaq Stock Market. The Stockholders’ Agreement also includes drag-along rights for FP-Ultra Clean and co-sale rights for the Sieger Shareholders. In addition, as long as FP-Ultra Clean holds any shares of the Issuer’s common stock, it will retain certain rights to receive financial information and reports regarding the Issuer’s business. The Sieger Shareholders also have the right to receive certain Issuer filings made with the Securities and Exchange Commission.

     The Lockup Agreement provides that the Sieger Shareholders may not sell or otherwise transfer their shares of Common Stock prior to December 26, 2006. The Lock-Up Agreement further provides that from December 26, 2006 to June 29, 2008, Leonid Mezhvinsky, Victor Mezhvinsky and their related trusts (the “Mezhvinsky Stockholders”) may not sell or otherwise transfer their shares of Common Stock unless they comply with the volume limitations under Rule 144 of the Securities Act of 1933, as amended, and do not sell or otherwise transfer more than 25% of the number of shares of Common Stock received by the Sieger Shareholders in the Merger in any consecutive 90-day period. Notwithstanding the foregoing, in the event that Leonid Mezhvinsky ceases to be an employee or director of the Issuer (if so elected), the Mezhvinsky Stockholders may sell or otherwise transfer up to 25% of the number of shares of Common Stock received by the Sieger Shareholders in the Merger in any consecutive 90-day period beginning on the later of December 26, 2006 and the date Mr. Mezhvinsky ceases to be an employee or director of the Issuer.

     The Registration Rights Agreement provides that, at the request of FP-Ultra Clean, or, under certain circumstances, the Sieger Shareholders, the Issuer can be required to effect registration statements registering the securities held by FP-Ultra Clean and the Sieger Shareholders. In addition, if the Issuer proposes to register any Issuer securities, other than a registration on form S-8 or S-4 or successor forms of these forms, whether or not such registration is for the Issuer’s own account, FP-Ultra Clean and the Sieger Shareholders may participate in such registration. The Issuer and any stockholders selling securities under a registration statement will be required to enter into customary indemnification and contribution arrangements with respect to each registration statement.

     References to and descriptions of the Stockholders’ Agreement as set forth in this Schedule 13D are qualified in their entirety by reference to the copy of the Stockholders’ Agreement included as Exhibit 1.

     References to and descriptions of the Lockup Agreement as set forth in this Schedule 13D are qualified in their entirety by reference to the copy of the Lockup Agreement included as Exhibit 2.

     References to and descriptions of the Registration Rights Agreement as set forth in this Schedule 13D are qualified in their entirety by reference to the copy of the Registration Rights Agreement included as Exhibit 3.

     Except for the Merger Agreement and the transactions contemplated thereby, including the Stockholders’ Agreement, the Registration Rights Agreement and the Lockup Agreement, there are no contracts, arrangements, understanding or relationships among any of the Reporting Persons or between such persons and any persons with

14

respect to any securities of the Issuer, including but not limited to transfer or voting of any of the securities, finder’s fees, joint ventures, loan or option arrangement, puts or calls, guarantees of profits, division of profits or loss, or the giving or withholding of proxies.

   Item 7. Material to be Filed as Exhibits.

     Exhibit 1: Amended and Restated Stockholders’ Agreement dated as of June 29, 2006 among the Issuer, FP-Ultra Clean, L.L.C., Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988, Joe and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002, Victor Mezhvinsky, Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2002 Irrevocable Trust under Agreement dated June 4, 2004, David Hongyu Wu and Winnie Wei Zhen Wu as trustees of the Chen Minors Irrevocable Trust and Frank Moreman.

     Exhibit 2: Lockup Agreement among the Issuer, Leonid Mezhvinsky, Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988, Joe and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002, Victor Mezhvinsky, Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2002 Irrevocable Trust under Agreement dated June 4, 2004, David Hongyu Wu and Winnie Wei Zhen Wu as trustees of the Chen Minors Irrevocable Trust and Frank Moreman.

     Exhibit 3: Amended and Restated Registration Rights Agreement among the Issuer, FP-Ultra Clean, L.L.C., Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988, Joe and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002, Victor Mezhvinsky, Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2002 Irrevocable Trust under Agreement dated June 4, 2004, David Hongyu Wu and Winnie Wei Zhen Wu as trustees of the Chen Minors Irrevocable Trust and Frank Moreman.

15

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

Francisco Partners GP, LLC

/s/ Benjamin Ball

Signature

Benjamin Ball, Managing Director

(Name/Title)

16

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

Francisco Partners, L.P.
By: Francisco Partners GP, LLC
        Its General Partner

/s/ Benjamin Ball

Signature

Benjamin Ball, Managing Director

(Name/Title)

17

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

FP- ULTRA CLEAN, L.L.C.
By: Francisco Partners GP, LLC
        Its Managing Member

/s/ Benjamin Ball

Signature

Benjamin Ball, Managing Director

(Name/Title)

18

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

LEONID AND INNA MEZHVINSKY
AS TRUSTEES OF THE REVOCABLE
TRUST AGREEMENT OF LEONID
MEZHVINSKY & INNA MEZHVINSKY,
DATED APRIL 26, 1988

/s/ Leonid Mezhvinsky

Signature

Leonid Mezhvinsky, Trustee

(Name/Title)

July 14, 2007

Date

LEONID AND INNA MEZHVINSKY
AS TRUSTEES OF THE REVOCABLE
TRUST AGREEMENT OF LEONID
MEZHVINSKY & INNA MEZHVINSKY,
DATED APRIL 26, 1988

/s/ Inna Mezhvinsky

Signature

Inna Mezhvinsky, Trustee

(Name/Title)

19

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

VICTOR MEZHVINSKY AS TRUSTEE
OF THE JOSHUA MEZHVINSKY 2004
IRREVOCABLE TRUST UNDER
AGREEMENT DATED JUNE 4, 2004

/s/ Victor Mezhvinsky

Signature

Victor Mezhvinsky, Trustee

(Name/Title)

20

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

DAVID HONGYU WU AND WINNIE
WEI ZHEN WU, AS TRUSTEES
OF THE CHEN MINORS
IRREVOCABLE TRUST

/s/ David Hongyu Wu

Signature

David Hongyu Wu, Trustee

(Name/Title)

July 14, 2007

Date

DAVID HONGYU WU AND WINNIE
WEI ZHEN WU, AS TRUSTEES
OF THE CHEN MINORS
IRREVOCABLE TRUST

/s/ Winnie Wei Zhen Wu

Signature

Winnie Wei Zhen Wu, Trustee

(Name/Title)

21

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

JOE CHEN AND JENNY CHEN
AS TRUSTII OF THE JOE CHEN
AND JENNY CHEN REVOCABLE
TRUST DATED 2002

/s/ Joe Chen

Signature

Joe Chen, Trustee

(Name/Title)

July 14, 2007

Date

JOE CHEN AND JENNY CHEN
AS TRUSTII OF THE JOE CHEN
AND JENNY CHEN REVOCABLE
TRUST DATED 2002

/s/ Jenny Chen

Signature

Jenny Chen, Trustee

(Name/Title)

22

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

/s/ Victor Mezhvinsky

Signature

Victor Mezhvinsky

(Name/Title)

23

SIGNATURE

     After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

July 14, 2007

Date

/s/ Frank Moveman

Signature

Frank Moveman

(Name/Title)

24

EX-99.1

Exhibit 1

AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT

dated as of

June 29, 2006

among

ULTRA CLEAN HOLDINGS, INC.,

FP-ULTRA CLEAN, L.L.C.,

     LEONID AND INNA MEZHVINSKY AS TRUSTEES OF THE
REVOCABLE TRUST AGREEMENT OF LEONID MEZHVINSKY AND
INNA MEZHVINSKY DATED APRIL 26, 1988,

JOE AND JENNY CHEN AS TRUSTEES OF THE JOE CHEN AND
JENNY CHEN REVOCABLE TRUST DATED 2002,

VICTOR MEZHVINSKY,

     VICTOR MEZHVINSKY AS TRUSTEE OF THE JOSHUA
MEZHVINSKY 2002 IRREVOCABLE TRUST UNDER AGREEMENT
DATED JUNE 4, 2004,

DAVID HONGYU WU AND WINNIE WEI ZHEN WU AS TRUSTEES OF
THE CHEN MINORS IRREVOCABLE TRUST,

and

FRANK MOREMAN

TABLE OF CONTENTS

PAGE

	ARTICLE 1 DEFINITIONS
Section 1.01.	Definitions	2
	ARTICLE 2 CORPORATE GOVERNANCE

Section 2.01.	Composition of the Board	5
Section 2.02.	Removal	7
Section 2.03.	Vacancies	7
Section 2.04.	Action by the Board	7
Section 2.05.	Conflicting Charter or Bylaw Provisions	8
Section 2.06.	Subsidiary Governance	8
	ARTICLE 3 RESTRICTIONS ON TRANSFER

Section 3.01.	General	9
Section 3.02.	Legends	9
Section 3.03.	Co-Sale Rights	9
Section 3.04.	Drag-Along Rights	10
	ARTICLE 4 CERTAIN COVENANTS AND AGREEMENTS

Section 4.01.	Information	11
Section 4.02.	Reports	12
Section 4.03.	Appointment of Stockholder Representative	12
	ARTICLE 5 MISCELLANEOUS

Section 5.01.	Entire Agreement	13
Section 5.02.	Binding Effect; Benefit	13
Section 5.03.	Assignability	13
Section 5.04.	Waiver; Amendment; Termination	13
Section 5.05.	Notices	14
Section 5.06.	Fees and Expenses	15
Section 5.07.	Headings	15
Section 5.08.	Counterparts	15
Section 5.09.	Applicable Law	15
Section 5.10.	Waiver of Jury Trial	15

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Section 5.11.	Specific Enforcement	16
Section 5.12.	Consent to Jurisdiction	16
Section 5.13.	Severability	16
Section 5.14.	Recapitalization	16
Section 5.15.	No Inconsistent Agreements	17

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AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT

     AGREEMENT dated as of June 29, 2006 (the “Agreement”) among Ultra Clean Holdings, Inc., a Delaware corporation (the “Company”), FP-Ultra Clean, L.L.C., a Delaware limited liability company (“FP”) and Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988 (the “Mehzvinsky Living Trust”), Joe and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002, Victor Mezhvinsky, Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2002 Irrevocable Trust under Agreement dated June 4, 2004 (the “Joshua Trust”), David Hongyu Wu and Winnie Wei Zhen Wu as trustees of the Chen Minors Irrevocable Trust and Frank Moreman (collectively, the “Sieger Stockholders”),and such additional persons as may sign joinder agreements to this Agreement.

W I T N E S S E T H :

     WHEREAS, FP is currently the owner of more than 20% of the Common Stock of the Company;

     WHEREAS, the Company has entered into an Agreement and Plan of Merger and Reorganization dated as of June 29, 2006 among Sieger Engineering, Inc., Leonid Mezhvinsky, the Company, Bob Acquisition Inc., Pete Acquisition LLC, the Sieger Stockholders and Leonid Mezhvinsky as Sellers’ Agent (the “Merger Agreement”) pursuant to which the Sieger Stockholders will receive shares of Common Stock of the Company;

     WHEREAS, the Company, FP and the Sieger Stockholders are entering into an Amended and Restated Registration Rights Agreement dated as of the date hereof (the “Amended and Restated Registration Right Agreement”) and the Company, Leonid Mehzvinsky and the Sieger Stockholders are entering into a Lockup Agreement dated as of the date hereof (the “Lockup Agreement”);

     WHEREAS, the parties hereto desire to enter into this Agreement to govern certain of their rights, duties and obligations;

     WHEREAS, the parties intend this Agreement to amend, supersede and restate in its entirety the Stockholders’ Agreement dated as of March 24, 2004 among the Company, FP and certain other persons named therein (the “Original Stockholders’ Agreement”);

     NOW, THEREFORE, in consideration of the covenants and agreements contained herein, the parties hereto agree that the Original Stockholders’ Agreement shall be amended and restated as follows:

ARTICLE 1
DEFINITIONS

     Section 1.01. Definitions. (a) The following terms, as used herein, have the following meanings:

     “Affiliate” means, with respect to any Person, any other Person directly or indirectly controlling, controlled by or under common control with such Person, provided that no securityholder of the Company shall be deemed an Affiliate of any other securityholder solely by reason of any investment in the Company. For the purpose of this definition, the term “control” (including with correlative meanings, the terms “controlling,” “controlled by” and “under common control with”), as used with respect to any Person, shall mean the possession, directly or indirectly, of the power to direct or cause the direction of the management and policies of such Person, whether through the ownership of voting securities, by contract or otherwise.

     “Aggregate Ownership” means, with respect to any Stockholder or group of Stockholders, and with respect to any class of Company Securities, the total amount of such class of Company Securities “beneficially owned” (as such term is defined in Rule 13d-3 of the Exchange Act) (without duplication) by such Stockholder or group of Stockholders as of the date of such calculation, calculated on a Fully Diluted basis.

     “Aggregate Ownership Percentage” means, with respect to any Stockholder (or group of Stockholders), and with respect to any class of Company Securities, the percentage equal to such Stockholder’s (or group of Stockholders’) Aggregate Ownership of such class of Company Securities divided by all outstanding Common Shares, calculated on a Fully Diluted basis.

     “Board” means the board of directors of the Company.

     “Business Day” means any day except a Saturday, Sunday or other day on which commercial banks in San Francisco or New York City are authorized by law to close.

     “Bylaws” means the bylaws of the Company, as amended from time to time.

     “Charter” means the certificate of incorporation of the Company, as the same may be amended from time to time.

     “Code” means the Internal Revenue Code of 1986, as amended from time to time.

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     “Common Stock” means the Common Stock, par value $0.001 per share, of the Company. “Common Shares” means shares of Common Stock.

     “Company Securities” means (i) the Common Stock, (ii) securities convertible into or exchangeable for Common Stock and (iii) options, warrants or other rights to acquire Common Stock or any other equity or equity-linked security issued by the Company.

     “Drag-Along Proportion” means the number of Common Shares that represents the percentage of all Common Shares held by FP to be sold pursuant to Section 3.04.

     “Drag-Along Shares” means the number of Common Shares of any Sieger Stockholder that represents the percentage of all Common Shares held by such Sieger Stockholder equal to the Drag-Along Proportion.

     “Exchange Act” means the Securities Exchange Act of 1934, as amended.

     “Five Percent Stockholder” means a Stockholder whose Aggregate Ownership Percentage is 5% or more.

     “Foreign Subsidiary” means, with respect to the Company, any entity organized under the laws of a jurisdiction other than a State of the United States of America of which securities or other ownership interests having ordinary voting power to elect a majority of the board of directors or other persons performing similar functions are at the time directly or indirectly owned by the Company.

     “Fully Diluted” means, with respect to any class of Company Securities, all outstanding shares and all shares issuable in respect of securities convertible into or exchangeable for such shares, all stock appreciation rights, options, warrants and other rights to purchase or subscribe for such Company Securities or securities convertible into or exchangeable for such Company Securities; provided that if any of the foregoing stock appreciation rights, options, warrants or other rights to purchase or subscribe for such Company Securities are subject to vesting, the Company Securities subject to vesting shall be included in the definition of “Fully Diluted” only upon and to the extent of such vesting.

     “Insignificant Subsidiary” means a subsidiary of the Company that does not meet any of the conditions contained in the definition of “significant subsidiary” as defined in Rule 1-02(w) of Regulation S-X promulgated by the SEC.

     “Investment” means, with respect to any Person, (i) any direct or indirect purchase or other acquisition by such Person of any notes, obligations,

3

instruments, stock, securities or ownership interest (including any partnership, limited liability and joint venture interest) of any other Person and (ii) any capital contribution by such Person to any other Person.

     “Mehzvinsky Party” means each of Leonid and Inna Mezhvinsky as trustees of the Mezhvinsky Living Trust, Victor Mezhvinsky, and Victor Mezhvinsky as trustee of the Joshua Trust.

     “Permitted Transferee” means (i) with respect to FP, any Person so designated by FP in its sole discretion, (ii) with respect to a Mehvinsky Party, any other Mezhvinsky Party, and (iii) with respect to any Sieger Stockholder, as applicable, such Sieger Stockholder’s Affiliates, spouse, ex-spouse, domestic partner, lineal descendant or antecedent, brother or sister, the adopted child or adopted grandchild, or the spouse or domestic partner of any child, adopted child, grandchild or adopted grandchild of such Sieger Stockholder, or a trust or trusts for the benefit of such Sieger Stockholder or those members of such Sieger Stockholder’s family specified in this clause (iii).

     “Person” means an individual, corporation, limited liability company, partnership, association, trust or other entity or organization, including a government or political subdivision or an agency or instrumentality thereof.

     “Pro Rata Share” means with respect to any Stockholder, the quotient obtained by dividing (i) the number of Common Shares held by such Stockholder by (ii) the aggregate number of all Common Shares held by the Stockholders.

     “SEC” means the Securities and Exchange Commission.

     “Securities Act” means the Securities Act of 1933, as amended.

     “Stockholder” means at any time, any Person (other than the Company) who shall then be a party to or bound by this Agreement, so long as such Person shall “beneficially own” (as such term is defined in Rule 13d-3 of the Exchange Act) any Company Securities.

     “Subsidiary” means, with respect to any Person, any entity of which securities or other ownership interests having ordinary voting power to elect a majority of the board of directors or other persons performing similar functions are at the time directly or indirectly owned by such Person.

     “Third Party” means a prospective purchaser(s) (other than a Permitted Transferee or other Affiliate of such Stockholder) of Company Securities in an arm’s-length transaction from a Stockholder.

     “Transfer” means, with respect to any Company Security, (i) when used as a verb, to sell, assign, dispose of, exchange, pledge, encumber, hypothecate or

4

otherwise transfer such security or any participation or interest therein, whether directly or indirectly, or agree or commit to do any of the foregoing and (ii) when used as a noun, a direct or indirect sale, assignment, disposition, exchange, pledge, encumbrance, hypothecation or other transfer of such security or any participation or interest therein or any agreement or commitment to do any of the foregoing.

     (b)The term “FP,” to the extent FP shall have transferred any of its Company Securities, shall mean FP and such transferee or transferees, taken together.

     (c)Each of the following terms is defined in the Section set forth opposite such term:

Term	Section
Additional Directors	2.01
Agreement	Preamble
Cause	2.02
Company	Preamble
Drag-Along Notice	Section 3.04(a)
FP	Preamble
FP Directors	Section 2.01(a)
FP Stockholder Representative	4.03
Replacement Nominee	2.03(a)
Sale Notice	Section 3.03(a)
Stockholder	5.03

ARTICLE 2
CORPORATE GOVERNANCE

     Section 2.01. Composition of the Board. (a) The Board shall consist of up to nine directors, nominated as follows: (i) up to three directors will be nominated by FP (the “FP Directors”); (ii) one director nominee will be the Chief Executive Officer of the Company for so long as he or she is employed by the Company; (iii) one director nominee will be Leonid Mezhvinsky (immediately following the appointment of an additional independent director to the Board) so long as (A) he is employed by the Company, (B) the Sieger Stockholders collectively hold more than 247,191 shares of Common Stock (C) FP holds more than 416,740 shares of Common Stock; and (iv) up to four directors will be nominated by the Chief Executive Officer and FP together, provided that each such director nominated pursuant to this clause (iv) shall (x) not be an “Affiliate” or an “Associate” (as such terms are used within the meaning of Rule 12b-2 under the Exchange Act) of FP and (y) be an “independent director,” as such term is

5

defined by the rules of the securities exchange or quotation system on which the Common Stock is traded. If the number of directors that comprise the entire Board is increased in accordance with Section 2.04 hereof, the number of directors added to the Board (the “Additional Directors”) must be a multiple of two, and FP shall continue to be entitled to nominate the FP Directors as provided in this Section 2.01.

     (b)Each Stockholder entitled to vote for the election of directors to the Board agrees that it will vote its Common Shares or execute a proxy or written consent, as the case may be, and take all other necessary action (including causing the Company to call a special meeting of stockholders) in order to ensure that the composition of the Board is as set forth in this Section 2.01. Notwithstanding anything to the contrary in this Agreement, the Sieger Stockholders shall be obligated to give effect to the rights to nominate directors set forth in Section 2.01(a)(i) only so long as the Sieger Stockholders hold more than 247,910 shares of Common Stock.

     (c)The right of FP to nominate the FP Directors pursuant to this Article 2 shall:

     (i)so long as FP’s Aggregate Ownership Percentage is less than 25%, be limited to the right to nominate one-fourth of the members of the Board, rounded up to the nearest whole number of members of the Board if such fraction is not a whole number;

     (ii)at such time as FP’s Aggregate Ownership Percentage is less than 20%, be reduced to the right to nominate one-fifth of the members of the Board, rounded up to the nearest whole number of members of the Board if such fraction is not a whole number;

     (iii)at such time as FP’s Aggregate Ownership Percentage is less than 10%, be reduced to the right to nominate one-tenth of the members of the Board, rounded up to the nearest whole number of members of the Board if such fraction is not a whole number; and

     (iv)terminate at such time as FP’s Aggregate Ownership Percentage is less than 5%.

     The obligations imposed on the Stockholders to give effect to the rights to nominate directors set forth in this Section 2.01 shall terminate as to any Person when such Person’s right to nominate a director is terminated.

     (d)The Company agrees to take all other reasonable actions (including calling a special meeting of the Board and/or stockholders) to effect the composition of the Board as set forth in this Section 2.01.

6

     Section 2.02. Removal. Each Stockholder agrees that if at any time it is then entitled to vote for the removal of directors from the Board, it will not vote any of its Common Shares in favor of the removal of any director who shall have been nominated in accordance with Section 2.01 hereof, unless such removal shall be for Cause or the Person or Persons entitled to nominate such director shall have consented to such removal in writing; provided that if the Person or Persons entitled to nominate any director pursuant to Section 2.01 hereof shall request in writing the removal, with or without Cause, of such director, such Stockholder shall vote its Common Shares in favor of such removal. Removal for “Cause” shall mean removal of a director because of such director’s (a) willful and continued failure substantially to perform his or her statutory or fiduciary duties to the Company in his or her established position, (b) participation in a fraud, act of dishonesty or other misconduct that is injurious, monetarily or otherwise, to the Company or any of its Subsidiaries, (c) having been charged with or pleading guilty to a felony or a crime involving fraud or dishonesty, (d) violation of any state or federal law that has an adverse effect on the Company or (e) abuse of illegal drugs or other controlled substances or habitual intoxication.

     Section 2.03. Vacancies. If, as a result of death, disability, retirement, resignation, removal (with or without Cause) or otherwise, there shall exist or occur any vacancy on the Board:

     (a)the Person or Persons entitled under Section 2.01 hereof to nominate such director whose death, disability, retirement, resignation or removal resulted in such vacancy may, subject to the provisions of Section 2.01 hereof, nominate another individual (the “Replacement Nominee”) to fill such vacancy and serve as a director on the Board; and

     (b)subject to Section 2.01 hereof, each Stockholder then entitled to vote for the election of the Replacement Nominee as a director of the Company agrees that it will vote its Common Shares, or execute a proxy or written consent, as the case may be, in order to ensure that the Replacement Nominee be elected to the Board.

     Section 2.04. Action by the Board. (a) A quorum of the Board shall consist of a majority of the total number of directors.

     (b)All actions of the Board shall require (i) the affirmative vote of at least a majority of the directors present at a duly convened meeting of the Board at which a quorum is present or (ii) the unanimous written consent of the Board; provided that if there is a vacancy on the Board and an individual has been nominated to fill such vacancy, the first order of business shall be to fill such vacancy.

7

     (c)The Board may create executive, compensation, audit, nominating and corporate governance and such other committees as it may determine. FP’s entitlement to representation on any committee created by the Board shall:

     (i)so long as FP’s Aggregate Ownership Percentage is less than 25%, be limited to an entitlement to designate one-fourth of the members of each such committee, rounded up to the nearest whole number of members if such fraction is not a whole number;

     (ii)at such time as FP’s Aggregate Ownership Percentage is less than 20%, be reduced to an entitlement to designate one-fifth of the members of each such committee, rounded up to the nearest whole number of members if such fraction is not a whole number;

     (iii)at such time as FP’s Aggregate Ownership Percentage is less than 10%, be reduced to an entitlement to designate one-tenth of the members of each such committee, rounded up to the nearest whole number of members if such fraction is not a whole number; and

     (iv)terminate at such time as FP’s Aggregate Ownership Percentage is less than 5%.

     Section 2.05. Conflicting Charter or Bylaw Provisions. Each Stockholder shall vote its Common Shares or execute proxies or written consents, as the case may be, and shall take all other actions necessary to ensure that the Company’s Charter and Bylaws (i) facilitate, and do not at any time conflict with, any provision of this Agreement and (ii) permit each Stockholder to receive the benefits to which each such Stockholder is entitled under this Agreement.

     Section 2.06. Subsidiary Governance. The Company and each Stockholder agree that (i) the board of directors or other persons performing similar functions of each Subsidiary of the Company (other than any Foreign Subsidiary and any Insignificant Subsidiary) shall be comprised of the individuals who are serving as directors on the Board in accordance with Section 2.01 hereof and (ii) the board of directors or other persons performing similar functions of any Subsidiary of the Company shall be subject to all the provisions of this Article 2. Each Stockholder agrees to vote its Common Shares and to cause its representatives on the Board, subject to their fiduciary duties, to vote and take other appropriate action to effectuate the agreements in this Section 2.06 in respect of any Subsidiary of the Company.

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ARTICLE 3
RESTRICTIONS ON TRANSFER

     Section 3.01. General. (a) Each Stockholder understands and agrees that the Company Securities acquired as of the date of this Agreement have not been registered under the Securities Act and are restricted securities under such Act and the rules and regulations promulgated thereunder. Each Stockholder agrees that it will not Transfer any Company Securities (or solicit any offers in respect of any Transfer of any Company Securities), except in compliance with the Securities Act, any applicable foreign or state securities or “blue sky” laws, and the terms and conditions of this Agreement.

     (b)Any attempt to Transfer any Company Securities not in compliance with this Agreement shall be null and void and the Company shall not, and shall cause any transfer agent not to, give any effect in the Company’s stock records to such attempted Transfer.

     Section 3.02. Legends. (a) In addition to any other legend that may be required, each certificate for Company Securities that is issued to any Stockholder shall bear a legend in substantially the following form:

     “THIS SECURITY HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR ANY FOREIGN OR STATE SECURITIES LAWS AND MAY NOT BE OFFERED OR SOLD EXCEPT IN COMPLIANCE THEREWITH. THIS SECURITY IS ALSO SUBJECT TO ADDITIONAL RESTRICTIONS ON TRANSFER AS SET FORTH IN THE AMENDED AND RESTATED STOCKHOLDERS’ AGREEMENT DATED AS OF JUNE 29, 2006, COPIES OF WHICH MAY BE OBTAINED UPON REQUEST FROM ULTRA CLEAN HOLDINGS, INC. OR ANY SUCCESSOR THERETO.”

     (b)If any Company Securities shall cease to be Registrable Securities (as defined in the Registration Rights Agreement) under clause (i) or clause (ii) of the definition thereof, the Company, upon the written request of the holder thereof, shall issue to such holder a new certificate evidencing such shares without the first sentence of the legend required by Section 3.02(a) hereof endorsed thereon. If any Company Securities cease to be subject to any and all restrictions on Transfer set forth in this Agreement, the Company, upon the written request of the holder thereof, shall issue to such holder a new certificate evidencing such Company Securities without the second sentence of the legend required by Section 3.02(a) hereof endorsed thereon.

     Section 3.03. Co-Sale Rights. (a)In the event (i) FP receives a bona fide offer from any person to purchase any of FP’s Company Securities and (ii) FP determines to sell any of its Company Securities, FP shall first give the Sieger

9

Stockholders notice of its intention to sell such shares, describing the number of shares proposed to be sold, the identity of the proposed purchaser, and the price and terms upon which FP proposes to make such sale (the “Sale Notice”).

     (b)Within 10 days after delivery of the Sale Notice, a Sieger Stockholder may elect to sell up to such Sieger Stockholder’s Pro Rata Share of the shares to be purchased by the purchaser described in the Sale Notice by giving written notice thereof to FP and tendering to the Secretary of the Company a certificate representing the shares to be sold, properly endorsed for transfer, with written instructions to transfer the shares to the purchaser described in the Sale Notice upon receipt of payment for such shares from such purchaser for the benefit of such Sieger Stockholder. FP shall thereupon notify the purchaser of the co-sale arrangements hereunder, and instruct the purchaser to deliver payment for the shares to be purchased by such purchaser to the Secretary of the Company, who shall transmit such payment to such Sieger Stockholders in payment for the shares sold by each.

     (c)To the extent any of the Sieger Stockholders decline to exercise the co-sale right as allowed by this Section 3.03, FP may, within 30 days after the date on which the Sieger Stockholders’ co-sale rights lapsed, sell some or all of FP’s Company Securities which were the subject of the Sale Notice at the price and on the terms specified in the Sale Notice. After the expiration of said 30 day period, FP shall not sell any of its Company Securities without first complying with the provisions of this Section 3.03.

     (d)This Section 3.03 shall not apply to any offer or sale of FP’s Company Securities pursuant to the exercise by FP of its rights under the Amended and Restated Registration Rights Agreement or pursuant to a sale under Rule 144 under the Securities Act.

     Section 3.04. Drag-Along Rights. (a)In the event FP determines to sell any of its Company Securities at a price equal to or greater than $9.00 per share, FP shall notify the Sieger Stockholders of its intention to transfer such shares, describing the number of shares held by FP to be transferred, the identity of the proposed transferee, the price and terms upon which FP proposes to make such transfer and the number of Drag-Along Shares to be purchased from each Sieger Stockholder by the transferee (the “Drag-Along Notice”).

     (b)Within 10 days after delivery of the Drag-Along Notice, each Sieger Stockholder shall tender to the Secretary of the Company a certificate representing the number of Drag-Along Shares to be sold by such Sieger Stockholder, properly endorsed for transfer, with written instructions to transfer the shares to the transferee described in the Drag-Along Notice upon receipt of payment for such shares from such transferee for the benefit of such Sieger Stockholder. FP shall thereupon instruct the transferee to deliver payment for the

10

shares to be purchased by such transferee to the Secretary of the Company, who shall transmit such payment to such Sieger Stockholders in payment for the shares sold by each.

     (c)This Section 3.04 shall not apply to any offer or sale of FP’s Company Securities pursuant to the exercise by FP of its rights under the Amended and Restated Registration Rights Agreement or pursuant to a sale under Rule 144 under the Securities Act.

ARTICLE 4
CERTAIN COVENANTS AND AGREEMENTS

     Section 4.01. Information. The Company agrees to furnish FP, for so long as FP owns any Company Securities:

     (a)as soon as practicable and in any event no later than 20 days after the end of each fiscal month, a management report for such month covering the items set forth in Exhibit B hereto;

     (b)as soon as practicable and, in any event, within 45 days after the end of each of the first three fiscal quarters, the unaudited consolidated balance sheet of the Company and its Subsidiaries as at the end of such quarter and the related unaudited statement of operations and cash flow for such quarter and for the portion of the fiscal year then ended, in each case prepared in accordance with GAAP;

     (c)as soon as practicable and, in any event, within 90 days after the end of each fiscal year, (i) the audited consolidated balance sheet of the Company and its Subsidiaries as at the end of such fiscal year and the related audited statement of operations and cash flow for such fiscal year, and for the portion of the fiscal year then ended, in each case prepared in accordance with GAAP and certified by Deloitte & Touche or another firm of independent public accountants of nationally recognized standing, together with a comparison of the figures in such financial statements with the figures for the previous fiscal year and the figures in the Company’s annual operating budget, (ii) any management letters or other correspondence from such accountants and (iii) the Company’s annual operating budget for the coming fiscal year,

     (d)promptly following the preparation thereof, a copy of any revisions to the annual operating budget delivered pursuant to clause (c) above,

     (e)promptly upon their becoming available, copies of (i) all financial statements, reports, notices and proxy statements sent or made generally available by the Company to any of its security holders, (ii) all regular and periodic reports

11

and all registration statements and prospectuses filed by the Company with any securities exchange or with the SEC and (iii) all press releases and other statements made generally available by the Company to the public,

     (f)as soon as practicable and, in any event, within five Business Days after any officer of the Company obtains knowledge thereof, notice (with a description in reasonable detail, and stating the action that the Company is taking or proposes to take with respect thereto) of (i) the commencement of any material litigation, investigation or other proceeding to which the Company or any of its Subsidiaries is a party before any court or arbitrator or any governmental body, agency or official or (ii) the existence of any material default or breach under this Agreement or any other material contract or agreement to which the Company or any of its Subsidiaries is a party, and

     (g)as promptly as reasonably practicable, such other information with respect to the Company or any of its Subsidiaries as may reasonably be requested by FP.

     The Company’s obligation to provide information pursuant to Section 4.01(a) and (b) shall be deemed satisfied upon the timely filing of such information with the SEC.

     Section 4.02. Reports. The Company will furnish the Stockholders with the quarterly and annual financial reports that the Company is required to file with the SEC pursuant to Section 13 or Section 15(d) of the Exchange Act or, in the event the Company is not required to file such reports, quarterly and annual reports containing the same information as would otherwise be required in such reports. The Company’s obligation to provide information pursuant to this Section 4.02 shall be deemed satisfied upon the timely filing of such information with the SEC.

     Section 4.03. Appointment of Stockholder Representative. FP and its Permitted Transferees, if any, irrevocably appoint the FP Stockholder Representative its agent and true and lawful attorney-in-fact, with full power of substitution, to take the actions, receive notices and exercise the powers delegated to the FP Stockholder Representative under this Agreement in the name of each such Stockholder, together with such actions and powers as are reasonably incidental thereto. Notwithstanding the foregoing, the FP Stockholder Representative shall not take any action or exercise any power to the extent that the holders of the majority of the Fully Diluted Common Shares held by FP and its Permitted Transferees shall have voted to prevent the Stockholder Representative from taking such action or exercising such power. “FP Stockholder Representative” means FP, as agent for FP and its Permitted Transferees. The entity appointed as the FP Stockholder Representative may be replaced at any time and from time to time by the vote of a majority of the Fully

12

Diluted Common Shares held by FP and its Permitted Transferees. FP shall notify the Company of such appointment as promptly as practicable after such appointment.

ARTICLE 5
MISCELLANEOUS

     Section 5.01. Entire Agreement. This Agreement, the Registration Rights Agreement, the Lockup Agreement, the Charter and the Bylaws constitute the entire agreement among the parties hereto and supersede all prior and contemporaneous agreements and understandings, both oral and written, among the parties hereto with respect to the subject matter hereof and thereof.

     Section 5.02. Binding Effect; Benefit. This Agreement shall inure to the benefit of and be binding upon the parties hereto and their respective heirs, successors, legal representatives and permitted assigns. Nothing in this Agreement, expressed or implied, is intended to confer on any Person other than the parties hereto, and their respective heirs, successors, legal representatives and permitted assigns, any rights, remedies, obligations or liabilities under or by reason of this Agreement.

     Section 5.03. Assignability. Neither this Agreement nor any right, remedy, obligation or liability arising hereunder or by reason hereof shall be assignable by any party hereto pursuant to any Transfer of Company Securities or otherwise, except that any Permitted Transferee acquiring Company Securities and any Person acquiring Company Securities who is required by the terms of this Agreement or any employment agreement or stock purchase, option, stock option or other compensation plan of the Company or any Subsidiary to become a party hereto shall (unless already bound hereby) execute and deliver to the Company an agreement to be bound by this Agreement in the form of Exhibit A hereto and shall thenceforth be a “Stockholder”, provided that any such Transfer pursuant to this Section 5.03 shall be subject to the terms of the Lockup Agreement. Any Stockholder who ceases to own beneficially any Company Securities shall cease to be bound by the terms hereof (other than Sections 5.09, 5.10, 5.11 and 5.12) .

     Section 5.04. Waiver; Amendment; Termination. (a) No provision of this Agreement may be waived except by an instrument in writing executed by the party against whom the waiver is to be effective. No provision of this Agreement may be amended or otherwise modified except by an instrument in writing executed by the Company with approval of the Board and Stockholders (including FP) holding at least 50% of the outstanding Common Shares held by the parties hereto at the time of such proposed amendment or modification.

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     (b)Any amendment or modification of any provision of this Agreement that would adversely affect FP may be effected only with the consent of FP.

     Section 5.05. Notices. All notices, requests and other communications to any party shall be in writing (including facsimile transmissions) and shall be given,

     if to the Company to:

Ultra Clean Holdings, Inc.
150 Independence Drive
Menlo Park, CA 94025
Attention: Chief Executive Officer
Fax: (650) 326-0929

     with copies to FP and Davis Polk & Wardwell at the addresses listed below.

     if to the Sieger Stockholders, to:

Sieger Engineering
130 Beacon Street
South San Francisco, CA 94080
Attention: Leonid Mezhvinsky
Fax: (650) 583-5823

     with a copy to:

Wilson Sonsini Goodrich & Rosati
Professional Corporation
One Market, Spear Tower, Suite 3300
San Francisco, CA 94105
Attention: Robert T. Ishii
Fax: (415) 947-2099

     if to FP, to:

FP-Ultra Clean, LLC
c/o Francisco Partners, L.P.
2882 Sand Hill Road, Suite 280
Menlo Park, CA 94025
Attention: Dipanjan Deb
Fax: (650) 233-2999

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     with a copy to:

Davis Polk & Wardwell
1600 El Camino Real
Menlo Park, CA 94025
Attention: Alan F. Denenberg, Esq.
Fax: (650) 752-2111

     All notices, requests and other communications shall be deemed received on the date of receipt by the recipient thereof if received prior to 5:00 p.m. in the place of receipt and such day is a Business Day in the place of receipt. Otherwise, any such notice, request or communication shall be deemed not to have been received until the next succeeding Business Day in the place of receipt. Any notice, request or other written communication sent by facsimile transmission shall be confirmed by certified mail, return receipt requested, posted within one Business Day, or by personal delivery, whether courier or otherwise, made within two Business Days after the date of such facsimile transmissions.

     Any Person who becomes a Stockholder shall provide its address and fax number to the Company, which shall promptly provide such information to each other Stockholder.

     Section 5.06. Fees and Expenses. The Company shall pay all out-of-pocket costs and expenses of FP, including the fees and expenses of counsel, incurred in connection with the preparation of this Agreement, or any amendment or waiver hereof, and the transactions contemplated hereby and all matters related hereto.

     Section 5.07. Headings. The headings contained in this Agreement are for convenience only and shall not affect the meaning or interpretation of this Agreement.

     Section 5.08. Counterparts. This Agreement may be executed in any number of counterparts, each of which shall be deemed to be an original and all of which together shall be deemed to be one and the same instrument.

     Section 5.09. Applicable Law. This Agreement shall be governed by, and construed in accordance with, the laws of the State of California, without regard to the conflicts of laws rules of such state.

     Section 5.10. Waiver of Jury Trial. EACH OF THE PARTIES HERETO HEREBY IRREVOCABLY WAIVES ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR RELATED TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY.

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     Section 5.11. Specific Enforcement. Each party hereto acknowledges that the remedies at law of the other parties for a breach or threatened breach of this Agreement would be inadequate and, in recognition of this fact, any party to this Agreement, without posting any bond, and in addition to all other remedies that may be available, shall be entitled to obtain equitable relief in the form of specific performance, a temporary restraining order, a temporary or permanent injunction or any other equitable remedy that may then be available.

     Section 5.12. Consent to Jurisdiction. The parties hereby agree that any suit, action or proceeding seeking to enforce any provision of, or based on any matter arising out of or in connection with, this Agreement or the transactions contemplated hereby shall be brought in the United States District Court for the District of Delaware or any Delaware State court sitting in Delaware, so long as one of such courts shall have subject matter jurisdiction over such suit, action or proceeding, and that any cause of action arising out of this Agreement shall be deemed to have arisen from a transaction of business in the State of Delaware, and each of the parties hereby irrevocably consents to the nonexclusive jurisdiction of such courts (and of the appropriate appellate courts therefrom) in any such suit, action or proceeding and irrevocably waives, to the fullest extent permitted by law, any objection that it may now or hereafter have to the laying of the venue of any such suit, action or proceeding in any such court or that any such suit, action or proceeding which is brought in any such court has been brought in an inconvenient form. Process in any such suit, action or proceeding may be served on any party anywhere in the world, whether within or without the jurisdiction of any such court. Without limiting the foregoing, each party agrees that service of process on such party asprovidedin Section 5.05 shall be deemed effective service of process on such party.

     Section 5.13. Severability. If one or more provisions of this Agreement are held to be unenforceable to any extent under applicable law or would result in a breach or violation of the rules or listing requirements of the securities exchange or quotation system on which the Common Shares are traded, such provision shall be interpreted as if it were written so as to be enforceable or in compliance with the rules or listing requirements, as applicable, to the maximum possible extent so as to effectuate the parties’ intent to the maximum possible extent, and the balance of the Agreement shall be interpreted as if such provision were so excluded or interpreted and shall be enforceable in accordance with its terms to the maximum extent permitted by law. Notwithstanding anything to the contrary contained herein, the Nominating and Corporate Governance Committee of the Board shall have the powers and duties set forth in its charter and all nominations made pursuant hereto shall be subject thereto.

     Section 5.14. Recapitalization. If any capital stock or other securities are issued in respect of, in exchange for, or in substitution of, any Company Securities by reason of any reorganization, recapitalization, reclassification,

16

merger, consolidation, spin-off, partial or complete liquidation, stock dividend, split-up, sale of assets, distribution to stockholders or combination of the Company Securities or any other change in capital structure of the Company, appropriate adjustments shall be made with respect to the relevant provisions of this Agreement so as fairly and equitably to preserve, as far as practicable, the original rights and obligations of the parties hereto under this Agreement.

     Section 5.15. No Inconsistent Agreements. The Company will not hereafter enter into any agreement with respect to its securities that is inconsistent with, or grants rights superior to the rights granted to the Stockholders pursuant to, this Agreement. The Company represents and warrants to each Stockholder that it has not previously entered into any agreement with respect to any of its securities granting any registration rights to any Person other than the Amended and Restated Registration Rights Agreement.

17

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed by their respective authorized officers as of the day and year first above written.

ULTRA CLEAN HOLDINGS, INC.
By:
	Name:
	Title:

FP-ULTRA CLEAN, LLC
	By:	FRANCISCO PARTNERS, L.P.,
		Managing Member

By:
	Name:
	Title:

LEONID AND INNA MEZHVINSKY AS TRUSTEES OF THE REVOCABLE TRUST AGREEMENT OF LEONID MEZHVINSKY AND INNA MEZHVINSKY DATED APRIL 26, 1988
By:
	Name:
	Title:

JOE AND JENNY CHEN AS TRUSTEES OF THE JOE CHEN AND JENNY CHEN REVOCABLE TRUST DATED 2002
By:
	Name:
	Title:

VICTOR MEZHVINSKY
By:
	Name:
	Title:

VICTOR MEZHVINSKY AS TRUSTEE OF THE JOSHUA MEZHVINSKY 2002 IRREVOCABLE TRUST UNDER AGREEMENT DATED JUNE 4, 2004
By:
	Name:
	Title:

DAVID HONGYU WU AND WINNIE WEI ZHEN WU AS TRUSTEES OF THE CHEN MINORS IRREVOCABLE TRUST
By:
	Name:
	Title:

FRANK MOREMAN
By:
	Name:
	Title:

EXHIBIT A

JOINDER TO STOCKHOLDERS’ AGREEMENT

     This Joinder Agreement (this “Joinder Agreement”) is made as of the date written below by the undersigned (the “Joining Party”) in accordance with the Stockholders’ Agreement dated as of June 29, 2006 (the “Stockholders’ Agreement”) among Ultra Clean Holdings, Inc., FP-Ultra Clean, L.L.C., Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988, Joe and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002, Victor Mezhvinsky, Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2002 Irrevocable Trust under Agreement dated June 4, 2004, David Hongyu Wu and Winnie Wei Zhen Wu as trustees of the Chen Minors Irrevocable Trust, Frank Moreman and certain other persons as the same may be amended from time to time. Capitalized terms used, but not defined, herein shall have the meaning ascribed to such terms in the Stockholders’ Agreement.

     The Joining Party hereby acknowledges, agrees and confirms that, by its execution of this Joinder Agreement, the Joining Party shall be deemed to be a party to the Stockholders’ Agreement as of the date hereof and shall have all of the rights and obligations of a “Stockholder” thereunder as if it had executed the Stockholders’ Agreement. The Joining Party hereby ratifies, as of the date hereof, and agrees to be bound by, all of the terms, provisions and conditions contained in the Stockholders’ Agreement.

     The Joining Party’s Aggregate Ownership is__________ Common Shares as of the date written below.

     IN WITNESS WHEREOF, the undersigned has executed this Joinder Agreement as of the date written below.

Date:___________ ___, 20___

[NAME OF JOINING PARTY]
By:
	Name:
	Title:
	Address for Notices:

EXHIBIT B

MATTERS TO BE INCLUDED IN THE COMPANY’S
MONTHLY MANAGEMENT REPORT

1.	The unaudited consolidated balance sheet of the Company and itsSubsidiaries as at the end of such month and the related unaudited statement of operations and cash flow for such month, and for the portion of the fiscal year then ended, in each case prepared in accordance with GAAP, setting forth in comparative form the figures for the corresponding month and portion of the previous fiscal year, and the figures for the corresponding month and portion of the then current fiscal year as in the Company’s annual operating budget.
2.	Projected monthly income statements prepared on the same basis as those specified in Item 1, including revenue forecasts by customer and expense budget by major expense category, for periods extending through a minimum of one year from the date of the report.
3.	A summary of realized and projected sales bookings for the most recent month and for periods extending through a minimum of one year from the date of the report, including probability-weighted “pipeline” projections of new bookings to the extent that the Company compiles such data for internal purposes.

EX-99.2

Exhibit 2

AMENDED AND RESTATED

REGISTRATION RIGHTS AGREEMENT

dated as of

June 29, 2006

among

ULTRA CLEAN HOLDINGS, INC.,

FP-ULTRA CLEAN L.L.C.,

     LEONID AND INNA MEZHVINSKY AS TRUSTEES OF THE
REVOCABLE TRUST AGREEMENT OF LEONID MEZHVINSKY AND
INNA MEZHVINSKY DATED APRIL 26, 1988,

JOE AND JENNY CHEN AS TRUSTEES OF THE JOE CHEN AND
JENNY CHEN REVOCABLE TRUST DATED 2002,

VICTOR MEZHVINSKY,

     VICTOR MEZHVINSKY AS TRUSTEE OF THE JOSHUA
MEZHVINSKY 2004 IRREVOCABLE TRUST UNDER AGREEMENT
DATED JUNE 4, 2004,

DAVID HONGYU WU AND WINNIE WEI ZHEN WU AS TRUSTEES OF
THE CHEN MINORS IRREVOCABLE TRUST,

AND

FRANK MOREMAN

TABLE OF CONTENTS

		PAGE
ARTICLE 1
DEFINITIONS
Section 1.01	Definitions	2
ARTICLE 2
REGISTRATION RIGHTS
Section 2.01	Demand Registration	5
Section 2.02	Piggyback Registration	7
Section 2.03	Registration Procedures	9
Section 2.04	Indemnification by the Company	12
Section 2.05	Indemnification by Participating Stockholders	13
Section 2.06	Conduct of Indemnification Proceedings	14
Section 2.07	Contribution	15
Section 2.08	Participation in Public Offering	16
Section 2.09	Other Indemnification	16
Section 2.10	Cooperation by the Company	16
Section 2.11	No Transfer of Registration Rights	17
ARTICLE 3
CERTAIN COVENANTS AND AGREEMENTS
Section 3.01	Reports	17
Section 3.02	Limitations on Subsequent Registration Rights	18
Section 3.03	Conflicting Agreements	18
ARTICLE 4
MISCELLANEOUS
Section 4.01	Lockup Agreement	19
Section 4.02	Binding Effect; Assignability; Benefit	19
Section 4.03	Notices	19
Section 4.04	Waiver; Amendment; Termination	21
Section 4.05	Fees and Expenses	21
Section 4.06	Governing Law	21
Section 4.07	Jurisdiction	21
Section 4.08	WAIVER OF JURY TRIAL	21
Section 4.09	Specific Enforcement	22
Section 4.10	Counterparts; Effectiveness	22

i

Section 4.11	Entire Agreement	22
Section 4.12	Captions	22
Section 4.13	Severability	22
Exhibit A: Joinder Agreement

ii

     AMENDED AND RESTATED REGISTRATION RIGHTS AGREEMENT

     Amended and Restated Registration Rights Agreement (this “Agreement”) dated as of June 29, 2006 among Ultra Clean Holdings, Inc., a Delaware corporation (the “Company”), FP-Ultra Clean L.L.C. (“FP”), Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988 (the “Mezhvinsky Living Trust”), Joe and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002 (the “Chen Living Trust”), Victor Mezhvinsky, Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2004 Irrevocable Trust under Agreement dated June 4, 2004 (the “Joshua Trust”), David Hongyu Wu and Winnie Wei Zhen Wu as trustees of the Chen Minors Irrevocable Trust (the “Chen Minors Trust”) and Frank Moreman.

W I T N E S S E T H :

     WHEREAS, pursuant to the Agreement and Plan of Merger and Reorganization dated as of June 29, 2006 among Sieger Engineering, Inc., Leonid Mezhvinsky, Ultra Clean Holdings, Inc., Bob Acquisition Inc., Pete Acquisition LLC, the Mezhvinsky Living Trust, the Chen Living Trust, Victor Mezhvinsky, the Joshua Trust, 2004, the Chen Minors Trust and Frank Moreman (collectively the “Sieger Stockholders”) and Leonid Mezhvinsky as Sellers’ Agent (the “Merger Agreement”), the Sieger Stockholders have acquired securities of the Company;

     WHEREAS, the Company, FP and the Sieger Stockholders are entering into an Amended and Restated Stockholders’ Agreement dated as of the date hereof and the Company, Leonid Mehzvinsky and the Sieger Stockholders are entering into a Lockup Agreement dated as of the date hereof (the “Lockup Agreement”);

     WHEREAS, the parties hereto desire to enter into this Agreement to govern certain of their rights, duties and obligations after consummation of the transactions contemplated by the Merger Agreement;

     WHEREAS, the parties hereto intend this Agreement to amend, supersede and restate in its entirety the Registration Rights Agreement dated as of December 2, 2002 among Ultra Clean Holdings, Inc., and FP-Ultra Clean L.L.C. (the “Original Registration Rights Agreement”);

     NOW, THEREFORE, in consideration of the covenants and agreements contained herein, the parties hereto agree that the Original Registration Rights Agreement shall be superseded and amended and restated in its entirety as follows:

ARTICLE 1 DEFINITIONS

     Section 1.01. Definitions. (a) The following terms, as used herein, have the following meanings:

     “Affiliate” means, with respect to any Person, any other Person directly or indirectly controlling, controlled by or under common control with such Person, provided that no securityholder of the Company shall be deemed an Affiliate of any other securityholder solely by reason of any investment in the Company. For the purpose of this definition, the term “control” (including, with correlative meanings, the terms “controlling”, “controlled by” and “under common control with”), as used with respect to any Person, shall mean the possession, directly or indirectly, of the power to direct or cause the direction of the management and policies of such Person, whether through the ownership of voting securities, by contract or otherwise.

     “Business Day” means any day except a Saturday, Sunday or other day on which commercial banks in San Francisco, California are authorized by law to close.

     “Common Stock” means the common stock, par value $0.001 per share, of the Company and any stock into which such Common Stock may thereafter be converted or changed.

     “Company Securities” means (i) the Common Stock, (ii) securities convertible into or exchangeable for Common Stock, (iii) any other equity or equity-linked security issued by the Company and (iv) options, warrants or other rights to acquire Common Stock or any other equity or equity-linked security issued by the Company.

     “Exchange Act” means the Securities Exchange Act of 1934, as amended.

     “First Public Offering” means March 24, 2004.

     “Mezhvinsky” means, collectively, the Mezhvinsky Living Trust, Victor Mezhvinsky and the Joshua Trust.

     “NASD” means the National Association of Securities Dealers, Inc.

     “Person” means an individual, corporation, limited liability company, partnership, association, trust or other entity or organization, including a government or political subdivision or an agency or instrumentality thereof.

     “Public Offering” means an underwritten public offering of Registrable Securities of the Company pursuant to an effective registration statement under the Securities Act.

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     “Registrable Securities” means, at any time, any Shares and any securities issued or issuable in respect of such Shares by way of conversion, exchange, stock dividend, split or combination, recapitalization, merger, consolidation, other reorganization or otherwise until (i) a registration statement covering such Shares has been declared effective by the SEC and such Shares have been disposed of pursuant to such effective registration statement, (ii) such Shares are sold under circumstances in which all of the applicable conditions of Rule 144 (or any similar provisions then in force) under the Securities Act are met or such securities may be sold pursuant to Rule 144(k) or (iii) such Shares are otherwise Transferred, the Company has delivered a new certificate or other evidence of ownership for such Shares not bearing the legend required pursuant to this Agreement and such Shares may be resold without subsequent registration under the Securities Act.

     “Registration Expenses” means any and all expenses incident to the performance of or compliance with any registration or marketing of securities, including all (i) registration and filing fees, and all other fees and expenses payable in connection with the listing of securities on any securities exchange or automated interdealer quotation system, (ii) fees and expenses of compliance with any securities or “blue sky” laws (including reasonable fees and disbursements of counsel in connection with “blue sky” qualifications of the securities registered), (iii) expenses in connection with the preparation, printing, mailing and delivery of any registration statements, prospectuses and other documents in connection therewith and any amendments or supplements thereto, (iv) security engraving and printing expenses, (v) internal expenses of the Company (including, without limitation, all salaries and expenses of its officers and employees performing legal or accounting duties), (vi) reasonable fees and disbursements of counsel for the Company and customary fees and expenses for independent certified public accountants retained by the Company (including the expenses relating to any comfort letters or costs associated with the delivery by independent certified public accountants of any comfort letters requested pursuant to Section 2.03(h)), (vii) reasonable fees and expenses of any special experts retained by the Company in connection with such registration, (viii) reasonable fees, out-of-pocket costs and expenses of the Stockholders, including one counsel for all of the Stockholders participating in the offering selected by the Stockholders holding the majority of the Registrable Securities to be sold for the account of all Stockholders in the offering, (ix) fees and expenses in connection with any review by the NASD of the underwriting arrangements or other terms of the offering, and all fees and expenses of any “qualified independent underwriter,” including the fees and expenses of any counsel thereto, (x) fees and disbursements of underwriters customarily paid by issuers or sellers of securities, but excluding any underwriting fees, discounts and commissions attributable to the sale of Registrable Securities, (xi) costs of printing and producing any agreements among underwriters, underwriting agreements, any “blue sky” or legal investment memoranda and any selling agreements and other documents in connection with the offering, sale or delivery of the Registrable Securities, (xii) transfer agents’

3

     and registrars’ fees and expenses and the fees and expenses of any other agent or trustee appointed in connection with such offering, (xiii) expenses relating to any analyst or investor presentations or any “road shows” undertaken in connection with the registration, marketing or selling of the Registrable Securities, (xiv) fees and expenses payable in connection with any ratings of the Registrable Securities, including expenses relating to any presentations to rating agencies and (xv) all out-of pocket costs and expenses incurred by the Company or its appropriate officers in connection with their compliance with Section 2.03(m).

     “Requesting Stockholder” means a Stockholder requesting a Demand Registration pursuant to Section 2.01 hereof.

     “Rule 144” means Rule 144 (or any successor provisions) under the Securities Act.

     “SEC” means the Securities and Exchange Commission.

     “Securities Act” means the Securities Act of 1933, as amended.

     “Shares” means shares of Common Stock.

     “Stockholder” means at any time, any Person (other than the Company) who shall then be a party to or bound by this Agreement, so long as such Person shall “beneficially own” (as such term is defined in Rule 13d-3 of the Exchange Act) any Company Securities.

     “Subsidiary” means, with respect to any Person, any entity of which securities or other ownership interests having ordinary voting power to elect a majority of the board of directors or other persons performing similar functions are at the time directly or indirectly owned by such Person.

     “Transfer” means, with respect to any Company Securities, (i) when used as a verb, to sell, assign, dispose of, exchange, pledge, encumber, hypothecate or otherwise transfer such Company Securities or any participation or interest therein, whether directly or indirectly, or agree or commit to do any of the foregoing and (ii) when used as a noun, a direct or indirect sale, assignment, disposition, exchange, pledge, encumbrance, hypothecation, or other transfer of such Company Securities or any participation or interest therein or any agreement or commitment to do any of the foregoing.

     (b)Each of the following terms is defined in the Section set forth opposite such term:

Term	Section
Company	Preamble
Damages	2.04
Demand Registration	2.01(c)

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Term	Section
Indemnified Party	2.06
Indemnifying Party	2.06
Inspectors	2.03(g)
Lockup Period	2.03
Maximum Offering Size	2.01(g)
Piggyback Registration	2.02(a)
Records	2.03(g)
Registering Stockholders	2.01(c)(ii)
Requesting Stockholder	2.01(a)

ARTICLE 2
REGISTRATION RIGHTS

     Section 2.01. Demand Registration. (a) If at any time the Company shall receive a request from FP; or

     (b)if at any time (but only once and provided the right in subsection (c) below has not previously been exercised) during the period beginning on June 29, 2008 and ending on December 29, 2009, the Company shall receive a request from Leonid Mezhvinsky as agent for the Sieger Stockholders; or

     (c) if at any time following the later of (i) December 29, 2006 and (ii) the day Leonid Mezhvinsky becomes a Non-Employee (as defined herein) (but only once, and provided the right in subsection (b) above has not been exercised, and provided further that Leonid Mezhvinsky has ceased to be (A) an employee or (B) a director, provided that he has not ceased to be a director either because he was not elected by the Company's stockholders after having been nominated to stand for election or because he declined to stand for election (in either A or B, a “Non-Employee”), of the Company) at any time during the period beginning on the date hereof and ending on June 28, 2008, the Company shall receive a request from Leonid Mezhvinsky as agent for the Sieger Stockholders that the Company effect the registration under the Securities Act of all or any portion of such Requesting Stockholder’s Registrable Securities (provided however, that any sales made pursuant to a request under Section 2.01(c) may only be effected up to the maximum number of shares that may be sold pursuant to Section 3 of the Lockup Agreement), and specifying the intended method of disposition thereof, then the Company shall promptly give notice of such requested registration (each such request shall be referred to herein as a “Demand Registration”) at least 15 Business Days prior to the anticipated filing date of the registration statement relating to such Demand Registration to the other Stockholders and thereupon shall use all reasonable efforts to effect, as expeditiously as possible, the registration under the Securities Act of:

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     (i)all Registrable Securities for which the Requesting Stockholder has requested registration under this Section 2.01, and

     (ii)subject to the restrictions set forth in Sections 2.01(g) and 2.02, all other Registrable Securities of the same class as those requested to be registered by the Requesting Stockholder that any other Stockholders with rights to request registration under Section 2.02 (all such Stockholders, together with the Requesting Stockholder, the “Registering Stockholders”) have requested the Company to register by request received by the Company within 15 Business Days after such Stockholders receive the Company’s notice of the Demand Registration,

all to the extent necessary to permit the disposition (in accordance with the intended methods thereof as aforesaid) of the Registrable Securities so to be registered, provided that the Company shall not be obligated to effect a Demand Registration unless the aggregate gross proceeds expected to be received from the sale of the Registrable Securities requested to be included in such Demand Registration equals or exceeds $5,000,000, and provided, further, that the Company shall not be required to effect a Demand Registration pursuant to subsection (b) hereof pursuant to Rule 415 (or its successor provision) and provided, further, that a registration pursuant to subsection (c) shall be, if so requested, pursuant to Rule 415 (or its successor provision) under the Securities Act. In no event shall the Company be required to effect more than one Demand Registration hereunder within any ninety day period.

     (d)Promptly after the expiration of the 15-Business Day period referred to in Section 2.01(c)(ii), the Company will notify all Registering Stockholders of the identities of the other Registering Stockholders and the number of shares of Registrable Securities requested to be included therein. At any time prior to the effective date of the registration statement relating to such registration, the Requesting Stockholders may revoke such request, without liability to any of the other Registering Stockholders, by providing a notice to the Company revoking such request.

     (e)The Company shall be liable for and pay all Registration Expenses in connection with any Demand Registration, regardless of whether such Registration is effected.

     (f)A Demand Registration shall not be deemed to have occurred:

     (i)unless the registration statement relating thereto (A) has become effective under the Securities Act and (B) has remained effective for a period of at least 180 days (or such shorter period in which all Registrable Securities of the Registering Stockholders included in such registration have actually been sold thereunder), provided that such registration statement shall not be considered a Demand Registration if, after such registration statement becomes effective, (1) such registration

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statement is interfered with by any stop order, injunction or other order or requirement of the SEC or other governmental agency or court and (2) less than 75% of the Registrable Securities included in such registration statement have been sold thereunder; or

     (ii)if the Maximum Offering Size is reduced in accordance with Section 2.01(g) such that less than 66 ² / ₃ % of the Registrable Securities of the Requesting Stockholders sought to be included in such registration are included.

     (g)If a Demand Registration involves an underwritten Public Offering and the managing underwriter advises the Company and the Requesting Stockholders that, in its view, the number of shares of Registrable Securities requested to be included in such registration (including any securities that the Company proposes to be included that are not Registrable Securities) exceeds the largest number of shares that can be sold without having an adverse effect on such offering, including the price at which such shares can be sold (the “Maximum Offering Size”), the Company shall include in such registration, in the priority listed below, up to the Maximum Offering Size:

     (i)First, all Registrable Securities requested to be registered by the Requesting Stockholder;

     (ii)second, all other Registrable Securities requested to be included in such registration by any Registering Stockholder (allocated, if necessary for the offering not to exceed the Maximum Offering Size, pro rata among such other Stockholders on the basis of the relative number of Registrable Securities so requested to be included in such registration by each such Stockholder); and

     (iii)third, any securities proposed to be registered by the Company.

     (h)Upon notice to each Requesting Stockholder, the Company may postpone effecting a registration pursuant to this Section 2.01 on one occasion during any period of twelve consecutive months for a reasonable time specified in the notice but not exceeding 60 days (which period may not be extended or renewed), if (i) an investment banking firm of recognized national standing shall advise the Company and the Requesting Stockholders in writing that effecting the registration would materially and adversely affect an offering of securities of such Company the preparation of which had then been commenced or (ii) the Company is in possession of material non-public information the disclosure of which during the period specified in such notice the Company reasonably believes would not be in the reasonable interests of the Company.

     Section 2.02. Piggyback Registration. (a) If at any time the Company proposes to register any Company Securities under the Securities Act (other than

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a registration on Form S-8 or S-4, or any successor forms, relating to Common Stock issuable upon exercise of employee stock options or in connection with any employee benefit or similar plan of the Company or in connection with a direct or indirect acquisition by the Company of another Person), whether or not for sale for its own account, the Company shall each such time give notice at least 30 Business Days prior to the anticipated filing date of the registration statement relating to such registration to each Stockholder, which notice shall set forth such Stockholder’s rights under this Section 2.02 and shall offer such Stockholder the opportunity to include in such registration statement the number of Registrable Securities of the same class or series as those proposed to be registered as each such Stockholder may request (a “Piggyback Registration”), subject to the provisions of Section 2.02(b) . Upon the request of any such Stockholder made within 15 Business Days after the receipt of notice from the Company (which request shall specify the number of Registrable Securities intended to be registered by such Stockholder), the Company shall use its reasonable efforts to effect the registration under the Securities Act of all Registrable Securities that the Company has been so requested to register by all such Stockholders, to the extent requisite to permit the disposition of the Registrable Securities to be so registered, provided that (i) if such registration involves an underwritten Public Offering, all such Stockholders requesting to be included in the Company’s registration must sell their Registrable Securities to the underwriters selected as provided herein on the same terms and conditions as apply to the Company or the Requesting Stockholders, as applicable, and (ii) if, at any time after giving notice of its intention to register any Company Securities pursuant to this Section 2.02(a) and prior to the effective date of the registration statement filed in connection with such registration, the Company shall determine for any reason not to register such securities, the Company shall give notice to all such Stockholders and, thereupon, shall be relieved of its obligation to register any Registrable Securities in connection with such registration. No registration effected under this Section 2.02 shall relieve the Company of its obligations to effect a Demand Registration to the extent required by Section 2.01. The Company shall pay all Registration Expenses in connection with each Piggyback Registration.

     (b)If a Piggyback Registration involves an underwritten Public Offering (other than any Demand Registration, in which case the provisions with respect to priority of inclusion in such offering set forth in Section 2.01(g) shall apply) and the managing underwriter advises the Company that, in its view, the number of Shares that the Company and such Stockholders intend to include in such registration exceeds the Maximum Offering Size, the Company shall include in such registration, in the following priority, up to the Maximum Offering Size:

     (i)first, so much of the Company Securities proposed to be registered for the account of the Company as would not cause the offering to exceed the Maximum Offering Size; and

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     (ii)second, all Registrable Securities requested to be included in such registration by any other Stockholders pursuant to Section 2.02 (allocated, if necessary for the offering not to exceed the Maximum Offering Size, pro rata among such Stockholders on the basis of the relative number of shares of Registrable Securities so requested to be included in such registration by each).

     Section 2.03. Registration Procedures. Whenever Stockholders request that any Registrable Securities be registered pursuant to Section 2.01 or 2.02, subject to the provisions of such Sections, the Company shall use its reasonable efforts to effect the registration and the sale of such Registrable Securities in accordance with the intended method of disposition thereof as quickly as practicable, and, in connection with any such request:

     (a)The Company shall as expeditiously as possible prepare and file with the SEC a registration statement on any form for which the Company then qualifies or that counsel for the Company shall deem appropriate and which form shall be available for the sale of the Registrable Securities to be registered thereunder in accordance with the intended method of distribution thereof, and use its reasonable efforts to cause such filed registration statement to become and remain effective for a period of not less than 180 days, or in the case of a shelf registration statement, one year (or such shorter period in which all of the Registrable Securities of the Registering Stockholders included in such registration statement shall have actually been sold thereunder).

     (b)Prior to filing a registration statement or prospectus or any amendment or supplement thereto, the Company shall, if requested, furnish to each participating Stockholder and each underwriter, if any, of the Registrable Securities covered by such registration statement copies of such registration statement as proposed to be filed, and thereafter the Company shall furnish to such Stockholder and underwriter, if any, such number of copies of such registration statement, each amendment and supplement thereto (in each case including all exhibits thereto and documents incorporated by reference therein), the prospectus included in such registration statement (including each preliminary prospectus and any summary prospectus) and any other prospectus filed under Rule 424 or Rule 430A under the Securities Act and such other documents as such Stockholder or underwriter may reasonably request in order to facilitate the disposition of the Registrable Securities owned by such Stockholder. Each participating Stockholder shall have the right to request that the Company modify any information contained in such registration statement, amendment and supplement thereto pertaining to such Stockholder and the Company shall use its reasonable efforts to comply with such request, provided, however, that the Company shall not have any obligation to so modify any information if the Company reasonably expects that so doing would cause the prospectus to contain an untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading.

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     (c)After the filing of the registration statement, the Company shall (i) cause the related prospectus to be supplemented by any required prospectus supplement, and, as so supplemented, to be filed pursuant to Rule 424 under the Securities Act, (ii) comply with the provisions of the Securities Act with respect to the disposition of all Registrable Securities covered by such registration statement during the applicable period in accordance with the intended methods of disposition by the Registering Stockholders thereof set forth in such registration statement or supplement to such prospectus and (iii) promptly notify each Registering Stockholder holding Registrable Securities covered by such registration statement of any stop order issued or threatened by the SEC or any state securities commission and take all reasonable actions required to prevent the entry of such stop order or to remove it if entered.

     (d)The Company shall use its reasonable efforts to (i) register or qualify the Registrable Securities covered by such registration statement under such other securities or “blue sky” laws of such jurisdictions in the United States as any Registering Stockholder holding such Registrable Securities reasonably (in light of such Stockholder’s intended plan of distribution) requests and (ii) cause such Registrable Securities to be registered with or approved by such other governmental agencies or authorities as may be necessary by virtue of the business and operations of the Company and do any and all other acts and things that may be reasonably necessary or advisable to enable such Stockholder to consummate the disposition of the Registrable Securities owned by such Stockholder, provided that the Company shall not be required to (A) qualify generally to do business in any jurisdiction where it would not otherwise be required to qualify but for this Section 2.03(d), (B) subject itself to taxation in any such jurisdiction or (C) consent to general service of process in any such jurisdiction.

     (e)The Company shall immediately notify each Registering Stockholder holding such Registrable Securities covered by such registration statement, at any time when a prospectus relating thereto is required to be delivered under the Securities Act, of the occurrence of an event requiring the preparation of a supplement or amendment to such prospectus so that, as thereafter delivered to the purchasers of such Registrable Securities, such prospectus will not contain an untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein not misleading and promptly prepare and make available to each such Stockholder and file with the SEC any such supplement or amendment.

     (f)(i) FP shall have the right, in its sole discretion, to select an underwriter or underwriters in connection with any Public Offering resulting from the exercise by FP of a Demand Registration, which underwriter or underwriters may include any Affiliate of FP and (ii) the Company shall select an underwriter or underwriters in connection with any other Public Offering, which underwriter or underwriters shall be reasonably acceptable to the Requesting Stockholder. In

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connection with any Public Offering, the Company shall enter into customary agreements (including an underwriting agreement in customary form) and take such all other actions as are required in order to expedite or facilitate the disposition of such Registrable Securities in any such Public Offering, including the engagement of a “qualified independent underwriter” in connection with the qualification of the underwriting arrangements with the NASD.

     (g)Upon execution of confidentiality agreements in form and substance reasonably satisfactory to the Company, the Company shall make available for inspection by any Registering Stockholder and any underwriter participating in any disposition pursuant to a registration statement being filed by the Company pursuant to this Section 2.03 and any attorney, accountant or other professional retained by any such Stockholder or underwriter (collectively, the “Inspectors”), all financial and other records, pertinent corporate documents and properties of the Company (collectively, the “Records”) as shall be reasonably necessary or desirable to enable them to exercise their due diligence responsibility, and cause the Company’s officers, directors and employees to supply all information reasonably requested by any Inspectors in connection with such registration statement. Records that the Company determines, in good faith, to be confidential and that it notifies the Inspectors are confidential shall not be disclosed by the Inspectors unless (i) the disclosure of such Records is necessary to avoid or correct a misstatement or omission in such registration statement or (ii) the release of such Records is ordered pursuant to a subpoena or other order from a court of competent jurisdiction. Each Registering Stockholder agrees that information obtained by it as a result of such inspections shall be deemed confidential and shall not be used by it or its Affiliates as the basis for any market transactions in the Company Securities unless and until such information is made generally available to the public. Each Registering Stockholder further agrees that, upon learning that disclosure of such Records is sought in a court of competent jurisdiction, it shall give notice to the Company and allow the Company, at its expense, to undertake appropriate action to prevent disclosure of the Records deemed confidential.

     (h)The Company shall furnish to each Registering Stockholder and to each such underwriter, if any, a signed counterpart, addressed to such Stockholder or underwriter, of (i) an opinion or opinions of counsel to the Company and (ii) a comfort letter or comfort letters from the Company’s independent public accountants, each in customary form and covering such matters of the kind customarily covered by opinions or comfort letters, as the case may be, as a majority of such Stockholders or the managing underwriter therefor reasonably requests.

     (i)The Company shall otherwise use its reasonable efforts to comply with all applicable rules and regulations of the SEC, and make available to its security holders, as soon as reasonably practicable, an earnings statement or such other document covering a period of 12 months, beginning within three months

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after the effective date of the registration statement, which earnings statement shall satisfy the provisions of Section 11(a) of the Securities Act and Rule 158 thereunder.

     (j)The Company may require each such Registering Stockholder promptly to furnish in writing to the Company such information regarding the distribution of the Registrable Securities as the Company may from time to time reasonably request and such other information as may be legally required in connection with such registration.

     (k)Each such Registering Stockholder agrees that, upon receipt of any notice from the Company of the happening of any event of the kind described in Section 2.03(e), such Stockholder shall forthwith discontinue disposition of Registrable Securities pursuant to the registration statement covering such Registrable Securities until such Stockholder’s receipt of the copies of the supplemented or amended prospectus contemplated by Section 2.03(e), and, if so directed by the Company, such Stockholder shall deliver to the Company all copies, other than any permanent file copies then in such Stockholder’s possession, of the most recent prospectus covering such Registrable Securities at the time of receipt of such notice. If the Company shall give such notice, the Company shall extend the period during which such registration statement shall be maintained effective (including the period referred to in Section 2.03(a)) by the number of days during the period from and including the date of the giving of notice pursuant to Section 2.03(e) to the date when the Company shall make available to such Stockholder a prospectus supplemented or amended to conform with the requirements of Section 2.03(e).

     (l)The Company shall use its reasonable efforts to list all Registrable Securities covered by such registration statement on any securities exchange or quotation system on which any of the Registrable Securities are then listed or traded.

     (m)The Company shall have appropriate officers of the Company (i) prepare and make presentations at any “road shows” and before analysts and rating agencies, as the case may be, (ii) take other actions to obtain ratings for any Registrable Securities and (iii) otherwise use their reasonable efforts to cooperate as reasonably requested by the underwriters in the offering, marketing or selling of the Registrable Securities.

     Section 2.04. Indemnification by the Company. The Company agrees to indemnify and hold harmless each Registering Stockholder holding Registrable Securities covered by a registration statement, its officers, directors, employees, partners and agents, and each Person, if any, who controls such Stockholder within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act from and against any and all losses, claims, damages, liabilities and expenses (including reasonable expenses of investigation and reasonable

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attorneys’ fees and expenses) (“Damages”) caused by or relating to any untrue statement or alleged untrue statement of a material fact contained in any registration statement or prospectus relating to the Registrable Securities (as amended or supplemented if the Company shall have furnished any amendments or supplements thereto) or any preliminary prospectus, or caused by or relating to any omission or alleged omission to state therein a material fact required to be stated therein or necessary to make the statements therein not misleading, except insofar as such Damages are caused by or related to any such untrue statement or omission or alleged untrue statement or omission so made based upon information furnished in writing to the Company by such Stockholder or on such Stockholder’s behalf expressly for use therein, provided that, with respect to any untrue statement or omission or alleged untrue statement or omission made in any preliminary prospectus, or in any prospectus, as the case may be, the indemnity agreement contained in this paragraph shall not apply to the extent that any Damages result from the fact that a current copy of the prospectus (or such amended or supplemented prospectus, as the case may be) was not sent or given to the Person asserting any such Damages at or prior to the written confirmation of the sale of the Registrable Securities concerned to such Person if it is determined that the Company has provided such prospectus to such Stockholder and it was the responsibility of such Stockholder to provide such Person with a current copy of the prospectus (or such amended or supplemented prospectus, as the case may be) and such current copy of the prospectus (or such amended or supplemented prospectus, as the case may be) would have cured the defect giving rise to such Damages. The Company also agrees to indemnify any underwriters of the Registrable Securities, their officers and directors and each Person who controls such underwriters within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act on substantially the same basis as that of the indemnification of the Stockholders provided in this Section 2.04.

     Section 2.05. Indemnification by Participating Stockholders. Each Registering Stockholder holding Registrable Securities included in any registration statement agrees, severally but not jointly, to indemnify and hold harmless the Company, its officers, directors and agents and each Person, if any, who controls the Company within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act to the same extent as the foregoing indemnity from the Company to such Stockholder, but only (i) with respect to information furnished in writing by such Stockholder or on such Stockholder’s behalf expressly for use in any registration statement or prospectus relating to the Registrable Securities, or any amendment or supplement thereto, or any preliminary prospectus or (ii) to the extent that any Damages result from the fact that a current copy of the prospectus (or such amended or supplemented prospectus, as the case may be) was not sent or given to the Person asserting any such Damages at or prior to the written confirmation of the sale of the Registrable Securities concerned to such Person if it is determined that it was the responsibility of such Stockholder to provide such Person with a current copy of the prospectus (or such amended or supplemented prospectus, as the case may be)

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and such current copy of the prospectus (or such amended or supplemented prospectus, as the case may be) would have cured the defect giving rise to such loss, claim, damage, liability or expense. Each such Stockholder also agrees to indemnify and hold harmless underwriters of the Registrable Securities, their officers and directors and each Person who controls such underwriters within the meaning of either Section 15 of the Securities Act or Section 20 of the Exchange Act on substantially the same basis as that of the indemnification of the Company provided in this Section 2.05. As a condition to including Registrable Securities in any registration statement filed in accordance with Article 2, the Company may require that it shall have received an undertaking reasonably satisfactory to it from any underwriter to indemnify and hold it harmless to the extent customarily provided by underwriters with respect to similar securities. No Registering Stockholder shall be liable under this Section 2.05 for any Damages in excess of the net proceeds realized by such Stockholder in the sale of Registrable Securities of such Stockholder to which such Damages relate.

     Section 2.06. Conduct of Indemnification Proceedings. If any proceeding (including any governmental investigation) shall be instituted involving any Person in respect of which indemnity may be sought pursuant to this Article 2, such Person (an “Indemnified Party”) shall promptly notify the Person against whom such indemnity may be sought (the “Indemnifying Party”) in writing and the Indemnifying Party shall assume the defense thereof, including the employment of counsel reasonably satisfactory to such Indemnified Party, and shall assume the payment of all fees and expenses, provided that the failure of any Indemnified Party so to notify the Indemnifying Party shall not relieve the Indemnifying Party of its obligations hereunder except to the extent that the Indemnifying Party is materially prejudiced by such failure to notify. In any such proceeding, any Indemnified Party shall have the right to retain its own counsel, but the fees and expenses of such counsel shall be at the expense of such Indemnified Party unless (i) the Indemnifying Party and the Indemnified Party shall have mutually agreed to the retention of such counsel or (ii) in the reasonable judgment of such Indemnified Party representation of both parties by the same counsel would be inappropriate due to actual or potential differing interests between them. It is understood that, in connection with any proceeding or related proceedings in the same jurisdiction, the Indemnifying Party shall not be liable for the reasonable fees and expenses of more than one separate firm of attorneys (in addition to any local counsel) at any time for all such Indemnified Parties, and that all such fees and expenses shall be reimbursed as they are incurred. In the case of any such separate firm for the Indemnified Parties, such firm shall be designated in writing by the Indemnified Parties. The Indemnifying Party shall not be liable for any settlement of any proceeding effected without its written consent, but if settled with such consent, or if there be a final judgment for the plaintiff, the Indemnifying Party shall indemnify and hold harmless such Indemnified Parties from and against any loss or liability (to the extent stated above) by reason of such settlement or judgment. Without the prior written consent of the Indemnified Party, no Indemnifying Party shall effect any

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settlement of any pending or threatened proceeding in respect of which any Indemnified Party is or could have been a party and indemnity could have been sought hereunder by such Indemnified Party, unless such settlement includes an unconditional release of such Indemnified Party from all liability arising out of such proceeding.

     Section 2.07. Contribution. If the indemnification provided for in this Article 2 is unavailable to the Indemnified Parties in respect of any Damages, then each such Indemnifying Party, in lieu of indemnifying such Indemnified Party, shall contribute to the amount paid or payable by such Indemnified Party as a result of such Damages (i) as between the Company and the Registering Stockholders holding Registrable Securities covered by a registration statement on the one hand and the underwriters on the other, in such proportion as is appropriate to reflect the relative benefits received by the Company and such Stockholders on the one hand and the underwriters on the other, from the offering of the Registrable Securities, or if such allocation is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits but also the relative fault of the Company and such Stockholders on the one hand and of such underwriters on the other in connection with the statements or omissions that resulted in such Damages, as well as any other relevant equitable considerations and (ii) as between the Company on the one hand and each such Stockholder on the other, in such proportion as is appropriate to reflect the relative fault of the Company and of each such Stockholder in connection with such statements or omissions, as well as any other relevant equitable considerations. The relative benefits received by the Company and such Stockholders on the one hand and such underwriters on the other shall be deemed to be in the same proportion as the total proceeds from the offering (net of underwriting discounts and commissions but before deducting expenses) received by the Company and such Stockholders bear to the total underwriting discounts and commissions received by such underwriters, in each case as set forth in the table on the cover page of the prospectus. The relative fault of the Company and such Stockholders on the one hand and of such underwriters on the other shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by the Company and such Stockholders or by such underwriters. The relative fault of the Company on the one hand and of each such Stockholder on the other shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates to information supplied by such party, and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission.

     The Company and the Registering Stockholders agree that it would not be just and equitable if contribution pursuant to this Section 2.07 were determined by pro rata allocation (even if the underwriters were treated as one entity for such

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purpose) or by any other method of allocation that does not take account of the equitable considerations referred to in the immediately preceding paragraph. The amount paid or payable by an Indemnified Party as a result of the Damages referred to in the immediately preceding paragraph shall be deemed to include, subject to the limitations set forth above, any legal or other expenses reasonably incurred by such Indemnified Party in connection with investigating or defending any such action or claim. Notwithstanding the provisions of this Section 2.07, no underwriter shall be required to contribute any amount in excess of the amount by which the total price at which the Registrable Securities underwritten by it and distributed to the public were offered to the public exceeds the amount of any Damages that such underwriter has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission, and no Registering Stockholder shall be required to contribute any amount in excess of the amount by which the total price at which the Registrable Securities of such Stockholder were offered to the public (less underwriters’ discounts and commissions) exceeds the amount of any Damages that such Stockholder has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No Person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities Act) shall be entitled to contribution from any Person who was not guilty of such fraudulent misrepresentation. Each Registering Stockholder’s obligation to contribute pursuant to this Section 2.07 is several in the proportion that the proceeds of the offering received by such Stockholder bears to the total proceeds of the offering received by all such Registering Stockholders and not joint.

     Section 2.08. Participation in Public Offering. No Person may participate in any Public Offering hereunder unless such Person (a) agrees to sell such Person’s securities on the basis provided in any underwriting arrangements approved by the Persons entitled hereunder to approve such arrangements and (b) completes and executes all questionnaires, powers of attorney, indemnities, underwriting agreements and other documents reasonably required under the terms of such underwriting arrangements and the provisions of this Agreement in respect of registration rights.

     Section 2.09. Other Indemnification. Indemnification similar to that specified herein (with appropriate modifications) shall be given by the Company and each Registering Stockholder participating therein with respect to any required registration or other qualification of securities under any federal or state law or regulation or governmental authority other than the Securities Act.

     Section 2.10. Cooperation by the Company. If any Stockholder shall transfer any Registrable Securities pursuant to Rule 144, the Company shall cooperate, to the extent commercially reasonable, with such Stockholder and shall provide to such Stockholder such information as such Stockholder shall reasonably request.

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     Section 2.11. No Transfer of Registration Rights. None of the rights of Stockholders under this Article 2 shall be assignable by any Stockholder to any Person acquiring Securities in any Public Offering or pursuant to Rule 144.

ARTICLE 3
CERTAIN COVENANTS AND AGREEMENTS

     Section 3.01. Reports. The Company agrees to furnish FP, for so long as FP owns any Company Securities:

     (a)as soon as practicable and, in any event within 20 days after the end of each month, the unaudited consolidated balance sheet of the Company and its Subsidiaries as at the end of such month and the related unaudited statement of operations and cash flow for such month, and for the portion of the fiscal year then ended, in each case prepared in accordance with GAAP, setting forth in comparative form the figures for the corresponding month and portion of the previous fiscal year, and the figures for the corresponding month and portion of the then current fiscal year as in the Company’s annual operating budget,

     (b)as soon as practicable and, in any event, within 45 days after the end of each of the first three fiscal quarters, the unaudited consolidated balance sheet of the Company and its Subsidiaries as at the end of such quarter and the related unaudited statement of operations and cash flow for such quarter and for the portion of the fiscal year then ended, in each case prepared in accordance with GAAP,

     (c)as soon as practicable and, in any event, within 90 days after the end of each fiscal year, (i) the audited consolidated balance sheet of the Company and its Subsidiaries as at the end of such fiscal year and the related audited statement of operations and cash flow for such fiscal year, and for the portion of the fiscal year then ended, in each case prepared in accordance with GAAP and certified by Deloitte & Touche or another firm of independent public accountants of nationally recognized standing, together with a comparison of the figures in such financial statements with the figures for the previous fiscal year and the figures in the Company’s annual operating budget, (ii) any management letters or other correspondence from such accountants and (iii) the Company’s annual operating budget for the coming fiscal year,

     (d)promptly following the preparation thereof, a copy of any revisions to the annual operating budget delivered pursuant to clause (c) above,

     (e)promptly upon their becoming available, copies of (i) all financial statements, reports, notices and proxy statements sent or made generally available by the Company to any of its security holders, (ii) all regular and periodic reports and all registration statements and prospectuses filed by the Company with any

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securities exchange or with the SEC and (iii) all press releases and other statements made generally available by the Company to the public,

     (f)as soon as practicable and, in any event, within five Business Days after any officer of the Company obtains knowledge thereof, notice (with a description in reasonable detail, and stating the action that the Company is taking or proposes to take with respect thereto) of (i) the commencement of any material litigation, investigation or other proceeding to which the Company or any of its Subsidiaries is a party before any court or arbitrator or any governmental body, agency or official or (ii) the existence of any material default or breach under this Agreement or any other material contract or agreement to which the Company or any of its Subsidiaries is a party, and

     (g)as promptly as reasonably practicable, such other information with respect to the Company or any of its Subsidiaries as may reasonably be requested by FP.

     Section 3.02. Limitations on Subsequent Registration Rights. The Company agrees that it shall not enter into any agreement with any holder or prospective holder of any securities of the Company (a) that would allow such holder or prospective holder to include such securities in any Demand Registration or Piggyback Registration unless, under the terms of such agreement, such holder or prospective holder may include such securities in any such registration only to the extent that their inclusion would not reduce the amount of the Registrable Securities of the Stockholders included therein or (b) on terms otherwise more favorable than this Agreement. The Company also represents and warrants to each Stockholder that it has not previously entered into any agreement with respect to any of its securities granting any registration rights to any Person other than the Original Registration Rights Agreement.

     Section 3.03. Conflicting Agreements. The Company represents and agrees that it shall not (a) grant any proxy or enter into or agree to be bound by any voting trust or agreement with respect to the Company Securities, except as expressly contemplated by this Agreement, (b) enter into any agreement or arrangement of any kind with any Person with respect to its Company Securities inconsistent with the provisions of this Agreement or for the purpose or with the effect of denying or reducing the rights of any other Stockholder under this Agreement, including agreements or arrangements with respect to the Transfer or voting of its Company Securities or (c) act, for any reason, as a member of a group or in concert with any other Person in connection with the Transfer or voting of its Company Securities in any manner that is inconsistent with the provisions of this Agreement.

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ARTICLE 4
MISCELLANEOUS

     Section 4.01. Lockup Agreement. Any rights granted to Mezhvinsky hereunder are granted and made expressly subject to the Lockup Agreement and the Company shall not be required to take any action which contravenes the terms of such Lockup Agreement.

     Section 4.02. Binding Effect; Assignability; Benefit. (a) This Agreement shall inure to the benefit of and be binding upon the parties hereto and their respective heirs, successors, legal representatives and permitted assigns.

     (b)Neither this Agreement nor any right, remedy, obligation or liability arising hereunder or by reason hereof shall be assignable by any party hereto pursuant to any Transfer of Company Securities or otherwise, except that, (i) at the sole written election of FP, Persons to whom FP has Transferred Company Securities may (unless already bound hereby) execute and deliver to the Company an agreement to be bound by this Agreement in the form of Exhibit A hereto and shall thenceforth be a “Stockholder” for purposes of, and have the rights of a Stockholder under, this Agreement and (ii) following the Transfer of Company Securities by a Sieger Stockholder to a transferee that is such Stockholder’s Affiliate, spouse, ex-spouse, domestic partner, lineal descendant or antecedent, brother or sister, the adopted child or adopted grandchild, or the spouse or domestic partner of any child, grandchild or adopted grandchild of such Stockholder, trust for the benefit of such Stockholder or those members of such Stockholder’s family specified in this subsection (b), such Transferee may (unless already bound hereby) execute and deliver to the Company an agreement to be bound by this Agreement in the form of Exhibit A hereto and shall thenceforth be a “Sieger Stockholder” for purposes of, and have the rights of a “Sieger Stockholder” under, this Agreement, provided that any such Transfer pursuant to this subparagraph (ii) must be in accordance with the Lockup Agreement.

     (c)Nothing in this Agreement, expressed or implied, is intended to confer on any Person other than the parties hereto, and their respective heirs, successors, legal representatives and permitted assigns, any rights, remedies, obligations or liabilities under or by reason of this Agreement.

     Section 4.03. Notices. All notices, requests and other communications to any party shall be in writing and shall be delivered in person, mailed by certified or registered mail, return receipt requested, or sent by facsimile transmission,

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if to the Company to:

       Ultra Clean Holdings, Inc.

       150 Independence Drive

       Menlo Park, CA 94025

       Attention: Chief Financial Officer

       Fax: 650-326-0929

if to FP, to:

       FP – Ultra Clean, L.L.C.

       2882 Sand Hill Road, Suite 280

       Menlo Park, CA 94025

       Attention: Dipanjan Deb

       Fax: 650-233-2999

       with a copy to:

       Davis Polk & Wardwell

       1600 El Camino Real

       Menlo Park, CA 94025

       Attention: Alan Denenberg

       Fax: (650) 752-2111

if to Mezhvinsky or the Sieger Stockholders, to:

       Sieger Engineering, Inc.

       130 Beacon Street

       South San Francisco, CA 94080

       Attention: Leonid Mezhvinsky

       Facsimile No.: (650) 583-5823

       with a copy to:

       Wilson Sonsini Goodrich & Rosati

       Professional Corporation

       One Market, Spear Tower, Suite 3300

       San Francisco, CA 94105

       Attention: Robert T. Ishii

       Facsimile No.: (415) 947-2099

     All notices, requests and other communications shall be deemed received on the date of receipt by the recipient thereof if received prior to 5:00 p.m. in the place of receipt and such day is a Business Day in the place of receipt. Otherwise, any such notice, request or communication shall be deemed not to have been received until the next succeeding Business Day in the place of receipt. Any notice, request or other written communication sent by facsimile transmission

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shall be confirmed by certified or registered mail, return receipt requested, posted within one Business Day, or by personal delivery, whether courier or otherwise, made within two Business Days after the date of such facsimile transmissions.

     Any Person that becomes a Stockholder shall provide its address and fax number to the Company.

     Section 4.04. Waiver; Amendment; Termination. No provision of this Agreement may be waived except by an instrument in writing executed by the party against whom the waiver is to be effective. No provision of this Agreement may be amended or otherwise modified except by an instrument in writing executed by all parties hereto.

     Section 4.05. Fees and Expenses. The Company shall pay all out-of-pocket costs and expenses of FP, including the reasonable fees and expenses of counsel, incurred in connection with the preparation of this Agreement, or any amendment or waiver hereof, and the transactions contemplated hereby and all matters related hereto.

     Section 4.06. Governing Law. This Agreement shall be governed by, and construed in accordance with, the laws of the State of California, without regard to the conflicts of laws rules of such state.

     Section 4.07. Jurisdiction. The parties hereby agree that any suit, action or proceeding seeking to enforce any provision of, or based on any matter arising out of or in connection with, this Agreement or the transactions contemplated hereby shall be brought in the United States District Court for the Northern District of California or any California State court sitting in San Jose, California, so long as one of such courts shall have subject matter jurisdiction over such suit, action or proceeding, and that any case of action arising out of this Agreement shall be deemed to have arisen from a transaction of business in the State of California, and each of the parties hereby irrevocably consents to the jurisdiction of such courts (and of the appropriate appellate courts therefrom) in any such suit, action or proceeding and irrevocably waives, to the fullest extent permitted by law, any objection that it may now or hereafter have to the laying of the venue of any such suit, action or proceeding in any such court or that any such suit, action or proceeding which is brought in any such court has been brought in an inconvenient form. Process in any such suit, action or proceeding may be served on any party anywhere in the world, whether within or without the jurisdiction of any such court. Without limiting the foregoing, each party agrees that service of process on such party as provided in Section 4.03 shall be deemed effective service of process on such party.

     Section 4.08. WAIVER OF JURY TRIAL. EACH OF THE PARTIES HERETO HEREBY IRREVOCABLY WAIVES ANY AND ALL RIGHT TO TRIAL BY JURY IN ANY LEGAL PROCEEDING ARISING OUT OF OR

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RELATED TO THIS AGREEMENT OR THE TRANSACTIONS CONTEMPLATED HEREBY.

     Section 4.09. Specific Enforcement. Each party hereto acknowledges that the remedies at law of the other parties for a breach or threatened breach of this Agreement would be inadequate and, in recognition of this fact, any party to this Agreement, without posting any bond, and in addition to all other remedies that may be available, shall be entitled to obtain equitable relief in the form of specific performance, a temporary restraining order, a temporary or permanent injunction or any other equitable remedy that may then be available.

     Section 4.10. Counterparts; Effectiveness. This Agreement may be executed in any number of counterparts, each of which shall be deemed to be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument. This Agreement shall become effective when each party hereto shall have received counterparts hereof signed by all of the other parties hereto.

     Section 4.11. Entire Agreement. This Agreement constitutes the entire agreement among the parties hereto and supersede all prior and contemporaneous agreements and understandings, both oral and written, among the parties hereto with respect to the subject matter hereof and thereof, other than the Lockup Agreement.

     Section 4.12. Captions. The captions herein are included for convenience of reference only and shall be ignored in the construction or interpretation hereof.

     Section 4.13. Severability. If any term, provision, covenant or restriction of this Agreement is held by a court of competent jurisdiction or other authority to be invalid, void or unenforceable, the remainder of the terms, provisions, covenants and restrictions of this Agreement shall remain in full force and effect and shall in no way be affected, impaired or invalidated so long as the economic or legal substance of the transactions contemplated hereby is not affected in any manner materially adverse to any party. Upon such a determination, the parties shall negotiate in good faith to modify this Agreement so as to effect the original intent of the parties as closely as possible in an acceptable manner so that the transactions contemplated hereby be consummated as originally contemplated to the fullest extent possible.

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     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be duly executed by their respective authorized officers as of the day and year first above written.

ULTRA CLEAN HOLDINGS, INC.
By:	/s/ Clarence L. Granger
	Name:	Clarence L. Granger
	Title:	President, Chief Executive Officer and Chief Operating Officer
FP-ULTRA CLEAN, LLC
By: FRANCISCO PARTNERS, L.P.,
By: Managing Member
By:	/s/ Dipanjan Deb
	Name:	Dipanjan Deb
	Title:	Managing member, Francisco Partners GP, LLC, its Managing Member
LEONID AND INNA MEZHVINSKY AS
TRUSTEES OF THE REVOCABLE TRUST
AGREEMENT OF LEONID
MEZHVINSKY AND INNA
MEZHVINSKY DATED 28-APR-88
By:	/s/ Leonid Mezhvinsky
	Name:	Leonid Mezhvinsky
	Title:	Trustee
JOE AND JENNY CHEN AS TRUSTEES OF THE
JOE CHEN AND JENNY CHEN
REVOCABLE TRUST DATED 2002
By:	/s/ Joe Chen
	Name:	Joe Chen
	Title:	Trustee

VICTOR MEZHVINSKY
By:	/s/ Victor Mezhvinsky
	Name:	Victor Mezhvinsky
	Title:	Trustee
VICTOR MEZHVINSKY AS TRUSTEE OF
THE JOSHUA MEZHVINSKY 2004
IRREVOCABLE TRUST UNDER
AGREEMENT DATED JUNE 4, 2004
By:	/s/ Victor Mezhvinsky
	Name:	Victor Mezhvinsky
	Title:	Trustee
THE CHEN MINORS IRREVOCABLE TRUST
By:	/s/ David Honguy Wu
	Name:	David Honguy Wu
	Title:	Trustee
By:	/s/ Winnie Wei Zhen Wu
	Name:	Winnie Wei Zhen Wu
	Title:	Trustee
FRANK MOREMAN
By:	/s/ Frank Moreman

EXHIBIT A

JOINDER TO REGISTRATION RIGHTS AGREEMENT

     This Joinder Agreement (this “Joinder Agreement”) is made as of the date written below by the undersigned (the “Joining Party”) in accordance with the Amended and Restated Registration Rights Agreement dated as of June 29, 2006 (the “Amended and Restated Registration Rights Agreement”) among Ultra Clean Holdings, Inc., FP – Ultra Clean, L.L.C. (“FP”), Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988, Joe and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002, Victor Mezhvinsky, Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2004 Irrevocable Trust under Agreement dated June 4, 2004, David Hongyu Wu and Winnie Wei Zhen Wu as trustees of the Chen Minors Irrevocable Trust and Frank Moreman, as the same may be amended from time to time. Capitalized terms used, but not defined, herein shall have the meaning ascribed to such terms in the Amended and Restated Registration Rights Agreement.

     The Joining Party hereby acknowledges, agrees and confirms that, by its execution of this Joinder Agreement and with the written consent of FP, the Joining Party shall be deemed to be a party to the Amended and Restated Registration Rights Agreement as of the date hereof and shall have all of the rights and obligations of a “Stockholder” thereunder as if it had executed the Amended and Restated Registration Rights Agreement. The Joining Party hereby ratifies, as of the date hereof, and agrees to be bound by, all of the terms, provisions and conditions contained in the Amended and Restated Registration Rights Agreement.

     IN WITNESS WHEREOF, the undersigned has executed this Joinder Agreement as of the date written below. This Joinder Agreement shall not be effective unless and until FP has indicated its written consent hereof.

Date: __________ __, ____

[NAME OF JOINING PARTY]
By:
	Name:
	Title:
Address for Notices:

FP hereby consents to the joinder of
the Joining Party to the Registration
Rights Agreement.

FP – Ultra Clean, L.L.C.
	By:
		Name:
		Title:

EX-99.3

Exhibit 3

LOCK-UP AGREEMENT

June 29, 2006

Ultra Clean Holdings, Inc.
150 Independence Drive
Menlo Park, California 94025
Attention: Clarence L. Granger,
President and Chief Executive Officer

Ladies and Gentlemen:

     Pursuant to the terms of the Agreement and Plan of Merger and Reorganization dated as of June 29, 2006 (the “Merger Agreement”) among Sieger Engineering, Inc. (the “Company”), Leonid Mezhvinsky (“Mezhvinsky”), Ultra Clean Holdings, Inc. (“Parent”), Bob Acquisition Inc., Pete Acquisition LLC, Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988 (the “Mezhvinsky Trust”), Joe and Jenny Chen as trustees of the Joe Chen and Jenny Chen Revocable Trust dated 2002, Victor Mezhvinsky, Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2004 Irrevocable Trust under Agreement dated June 4, 2004 (the “Joshua Trust”), David Hongyu Wu and Winnie Wei Zhen Wu as trustees of the Chen Minors Irrevocable Trust, Frank Moreman, and Leonid Mezhvinsky, as Sellers’ Agent, the undersigned will receive cash and shares of Common Stock, par value $0.001 per share, of Parent (the “Shares”), in exchange for shares of common stock of the Company, a majority of which is owned by the undersigned. In order to induce Parent to enter into the Merger Agreement and in connection with this letter agreement (this “Agreement”), Parent and the undersigned are also entering into the Amended and Restated Registration Rights Agreement and the Amended and Restated Stockholders’ Agreement dated as of the date hereof. Each of Mezhvinsky, the Mezhvinsky Trust, Victor Mezhvinsky and the Joshua Trust shall hereinafter be referred to as a “Mezhvinsky Stockholder,” and collectively as the “Mezhvinsky Stockholders.” Each of Parent and the other parties hereto hereby agrees as follows:

     1. Until December 26, 2006 (the “Initial Release Date”), each of the parties hereto (other than Parent) agrees not to sell, offer to sell, contract to sell, sell any option or contract for the sale or purchase of, lend, enter into any swap or other arrangement that transfers to another any of the economic consequences of ownership of, or otherwise dispose of (collectively, “Transfer”) any Shares.

     2. From the Initial Release Date until June 29, 2008 (the “Second Release Date”), each Mezhvinsky Stockholder agrees not to Transfer any Shares unless (i) each such Transfer during that period complies with the volume limitations of Rule 144 (“Rule 144”) under the Securities Act of 1933, as amended (the “Securities Act”) and (ii) Transfers made during any consecutive 90-day period do not exceed 25% of the Shares.

     3. Notwithstanding anything herein to the contrary, in the event Mezhvinsky ceases to be (i) an employee or (ii) a director (provided that he has not ceased to be a director either because he was not elected by the Company's stockholders after having been nominated to stand for election or because he declined to stand for election) of Parent, the Mezhvinsky Stockholders may Transfer up to 25% of the Shares in any 90-day period beginning on the later of (i) the Initial Release Date and (ii) the date Mezhvinsky ceases to be an employee or a director of Parent.

     4. Beginning on the Second Release Date and thereafter the Stockholders shall not be subject to any contractual limitation hereunder on their ability to Transfer any Shares.

     5. Notwithstanding the foregoing, Mezhvinsky acknowledges and agrees that at all times that he remains an “affiliate” (as defined in Rule 405 under the Securities Act) of Parent by virtue of his position on the Board of Directors of Parent or otherwise, he shall be subject to Parent’s insider trading and Section 16 compliance policies.

     6. The undersigned acknowledge that Parent may impose stock transfer restrictions on the Shares (including placing legends on the Shares indicating that such Shares are subject to this Agreement) to enforce the provisions of this Agreement or to the extent that restrictions exist under the Securities Act. The undersigned further acknowledge that the restrictions imposed by this Agreement are in addition to any other restrictions imposed on the Transfer of the Shares pursuant to any other agreement in effect between Parent and the undersigned or pursuant to applicable law; provided that, if any Shares cease to be subject to any restrictions on Transfer under the Securities Act or this Agreement, upon the written request of a Stockholder and the submission of evidence reasonably satisfactory to Parent of that fact, Parent shall issue to the Stockholder a new certificate or certificates evidencing those Shares without any legend or stock transfer restriction that may have been placed thereon with respect thereto.

     7. For purposes of this Agreement, the Shares shall be deemed to include all of the Shares received by Leonid and Inna Mezhvinsky as trustees of the Revocable Trust Agreement of Leonid Mezhvinsky and Inna Mezhvinsky dated April 26, 1988, Victor Mezhvinsky and Victor Mezhvinsky as trustee of the Joshua Mezhvinsky 2004 Irrevocable Trust under Agreement dated June 4, 2004 (the “Receiving Parties”) pursuant to the Merger Agreement and all of the Shares received and Transferred by the Receiving Parties shall be aggregated for purposes of determining the number of Shares that may be Transferred during any particular period.

     8. Notwithstanding anything contained herein to the contrary, any party hereto may, at any time, Transfer any number of Shares to such party’s “affiliates” (as defined in Rule 405 under the Securities Act), spouse, ex-spouse, domestic partner, lineal descendant or antecedent, brother or sister, the adopted child or adopted

2

grandchild, or the spouse or domestic partner of any child, adopted child, grandchild or adopted grandchild of such party, or a trust or trusts for the benefit of such party or those members of such party’s family specified in this Section 8; provided that any such transferee shall be subject to the terms of this Agreement.

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     If the above reflects our agreement with you, please sign in the place indicated below.

LEONID MEZHVINSKY
	/s/ Leonid Mezhvinsky
LEONID AND INNA MEZHVINSKY AS TRUSTEES OF THE REVOCABLE TRUST AGREEMENT OF LEONID MEZHVINSKY AND INNA MEZHVINSKY DATED APRIL 26, 1988
By:	/s/ Leonid Mezhvinsky
	Name:	Leonid Mezhvinsky
	Title:	Trustee
VICTOR MEZHVINSKY
By:	/s/ Victor Mezhvinsky
VICTOR MEZHVINSKY AS TRUSTEE OF THE JOSHUA MEZHVINSKY 2004 IRREVOCABLE TRUST UNDER AGREEMENT DATED JUNE 4, 2004
By:	/s/ Victor Mezhvinsky
	Name:	Victor Mezhvinsky
	Title:	Trustee

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JOE AND JENNY CHEN AS TRUSTEES OF THE JOE AND JENNY CHEN REVOCABLE TRUST DATED 2002
By:	Joe Chen
	Name:	Joe Chen
	Title:	Trustee
THE CHEN MINOR IRREVOCABLE TRUST
By:	/s/ David Hongyu Wu
	Name:	David Hongyu Wu
	Title:	Trustee
By:	/s/ Winnie Wei Zhen Wu
	Name:	Winnie Wei Zhen Wu
	Title:	Trustee
FRANK MOREMAN
	/s/ Frank Moreman

ACCEPTED AND AGREED TO:
ULTRA CLEAN HOLDINGS, INC.
By:	/s/ Clarence L. Granger
	Name:	Clarence L. Granger
	Title:	President, Chief Executive Officer and Chief Operating Officer

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