By Kent Whitfield, Director of Reliability, MiaSolé; Tanya Dhir, Senior Reliability Engineer, MiaSolé; Kedar Hardikar, Senior Scientist, MiaSolé
This paper describes a methodology used to establish reliability of a CIGS thin-film photovoltaic module component based on identification of a failure mode through product thermal-cycling. The initial observation of the failure is described as part of a larger reliability program that progresses from failure mode and effect analysis through a test-tofailure program that has an objective of understanding the ultimate consequence of specific applied stresses on product performance. Once the specific failure mode was discovered, four means of characterizing the mode were applied and are discussed: tensile testing and material analysis, computer modelling, coupon rapid thermal cycling, and mechanical fatigue testing. This work identified the relevant root cause for failure and facilitated a materials change, which itself was subjected to an accelerated testing program to quantify the improvement and determine success of the design. The means of verifying success included meeting an endurance thermal-cycle limit for a collection of samples and subjecting corrected designs to a mechanical fatigue test, where the correlation between thermal cycle and mechanical fatigue were compared using Weibull analysis.
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