Abstract:

Life time of electronic products is often limited by competing failure mechanisms brought on by the product’s use and its surrounding environment. Solder interconnect failure is a known life limiting failure mechanism that is induced 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 and model constants have been developed to predict life expectancy of solder joints. However, simple temperature cycling tests do not necessarily provide a good representation of field use. In the field, electronic devices can experience more complex temperature cycle due to user controlled on and off cycles, non-constant workloads, and changes in surrounding environment. Under these conditions, electronic equipment does not experience constant dwell and ramp. Instead, varying temperature excursions often occur. To address concerns related to complex temperature cycles, an experiment was conducted and several modeling strategies were examined. The most effective modeling approach using the Engelmaier model was not the most effective modeling approach when using a partitioned strain energy model.

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