Test-time compression for qualification testing of electronic packages: a case study

This paper illustrates a methodology for using physics-of-failure models to extract acceleration transform information from limited test data under accelerated stresses. Test time compression is achieved by appropriately accelerating the stress levels in order to obtain accurate information on reliability. The critical variables are identified and their influence on the stress magnitude is quantified using physics-of-failure models. The total amount of testing time is minimized by tailoring the critical variables in each sample such that multiple stress levels can be achieved in the samples under a single loading. This type of parametric-accelerated test eliminates the need for repeating the test at multiple load levels. Such techniques are essential for cost effective and timely qualification testing of highly reliable modules under accelerated stresses. All sources of error due to experimental variables and assumptions or simplifications in the analytical model are closely examined and discussed. Future work will employ a more detailed physics-of-failure model to quantify the experimental results. These test results also validate physics-of-failure models for acceleration transforms which relate test data to field reliability. Analytical predictive models for acceleration transforms will obviously result in significant savings of cost and time during qualification.