Strain-Range-Based Solder Life Predictions Under Temperature Cycling With Varying Amplitude and Mean

To investigate modeling approaches for predicting solder interconnect fatigue life under field thermal conditions, a complex temperature cycle composed of three temperature dwell points was modeled and physically tested. Modeling the solder interconnect life expectancy under these complex conditions is accomplished by segmenting the complex temperature cycle into multiple simple temperature cycles, predicting the life expectancy of the solder interconnect under the simple temperature cycles using the Engelmaier model, and applying Miner´s rule to superpose the damage of the segmented cycles and predict solder interconnect fatigue life under the complex temperature cycle. Several modeling strategies based on different segmenting schemes are presented, and the one with the best comparison with the physical test results is identified. A case study is presented for ceramic leadless chip carriers assembled with Sn62Pb36Ag2, Sn96.5Ag3Cu0.5, and SN100C solders. The Engelmaier model constants to model the simple temperature cycles are also provided as a basis for modeling the complex cycle.