SEGMENT INFORMATION Sales by country (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 28, 2019	Jun. 29, 2019	Mar. 30, 2019	Dec. 29, 2018	Sep. 29, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 30, 2017	Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)	$ 139,827	$ 127,109	$ 115,908	$ 157,208	$ 184,824	$ 268,834	$ 221,772	$ 213,691	$ 540,052	$ 889,121	$ 809,041
China [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									252,179	408,567	323,803
Taiwan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									63,440	126,676	100,738
Malaysia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									41,568	65,354	72,329
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									36,393	68,774	57,728
Singapore [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									25,680	19,648	7,119
KOREA, REPUBLIC OF
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									15,236	38,551	73,410
GERMANY
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									13,594	19,018	18,754
HONG KONG
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									12,096	14,194	14,314
Philippines [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									12,057	26,372	25,165
VIETNAM
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									10,978	20,864	29,330
All Other Segments [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Net (Deprecated 2018-01-31)									$ 56,831	$ 81,103	$ 86,351