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|CLCC Life Prediction under Complex Temperature Cycling Test|
|Keywords: Power Cycling, Modeling, Life prediction|
|The lifetime of electronic products are limited by a set of competing failure mechanisms brought on by their use and surrounding environment. Solder interconnect failure is a known life limiting failure mechanism that is driven by repeated temperature excursions. Thermal fatigue reliability of solder is conventionally assessed by simple temperature cycling tests, which apply a constant temperature range, fixed dwell times and ramp rates during the test. From these tests, fatigue models have been developed to predict life expectancy of solder joints. However, under on and off cycles, non-constant work loads, and changes in surrounding environment, electronic devices are not subjected to simple temperature cycling during their life. To address complex cycles, linear superposition approach has been applied. But here, the method of partitioning complex temperature cycles is not clearly documented. To examine this issue, a complex temperature cycle test is conducted. The interconnect life expectancy was estimated using the Engelmaier model. Various approaches for partitioning the temperature cycle were examined. Damage per cycle was defined as the one over the predicted cycles to failure for the specified partitioned temperature cycle. Damage for the segmented temperature cycles were then linearly superimposed and to predict the life under the complex temperature cycle. One partitioning method was found to provide the best simulation results. Solders evaluated include Sn62Pb36Ag2, Sn96.5Ag3Cu0.5 and SN100C.|
|Fei Chai, Graduate Student
University of Maryland - CALCE