Intangible assets consist of the following, in thousands:


		September 30,
	Amortization Period	2023			2022
Backlog	1 year	$	2,100		$	—
Customer relationships	6-10 years		4,409			1,609
Developed technology	5 years		6,700			—
Noncompetition agreements	5 years		200			—
Trade names	3-15 years		2,679			879
			16,088			2,488
Accumulated amortization			(4,785	)		(1,730	)
Less asset impairments:
Backlog			(425	)		—
Customer relationships			(119	)		—
Developed technology			(4,645	)		—
Intangible assets, net		$	6,114		$	758

Intangible assets are amortized over a weighted-average amortization period of 6.6 years. Our customer relationship and trade name intangible assets are amortized over weighted-average amortization periods of 2.4 and 1.9 years, respectively.

During each fiscal year, we periodically assessed whether any indicators of impairment existed related to our intangible assets. As of each interim period end during each fiscal year, we concluded that a triggering event had not occurred that would more likely than not reduce the fair value of intangible assets below their carrying value. We identified a triggering event at the end of September 2023, primarily related to the prolonged downturn and general economic conditions in the semiconductor market, in addition to delays in the adoption of next-gen polishing tools, which reduced our cash flow projections. This triggering event indicated we should test the related long-lived assets for impairment in our Material and Substrate segment. We tested each identified asset group within our Material and Substrate segment by first performing a recoverability test, comparing projected undiscounted cash flows from the use and eventual disposition of each asset group to its carrying value. This test indicted that the undiscounted cash flows were not sufficient to recover the carrying value of certain asset groups. We then compared the carrying value of the individual long-lived assets within those asset groups against their fair value in order to determine if impairment existed. Determining the fair value of those asset groups involves the use of significant estimates and assumptions, including projections of revenues and expenses and related cash flows based on assumed long-term growth rates and demand trends, and estimated discount rates based on the asset group's weighted average return on assets, as derived from various methods. The fair value of the intangible assets were estimated using various valuation methodologies, including the multi-period excess earnings method, the relief from royalty method and the distributor method. These fair value measurements fall under Level 3 of the fair value hierarchy. As a result, we recorded a total impairment charge for intangible assets in our Materials and Substrate segment of $5.2 million during the year ended September 30, 2023. This impairment charge relates to developed technology and backlog at Entrepix and customer relationships at Intersurface Dynamics.

Amortization expense related to intangible assets was $3.1 million, $0.1 million and $0.2 million in 2023, 2022 and 2021, respectively. Future amortization expense for the remaining unamortized balance as of September 30, 2023 is estimated as follows, in thousands:


Years Ending September 30,	Amortization Expense
2024	$	929
2025		828
2026		828
2027		828
2028		613
Thereafter		2,088
Total	$	6,114