Abstract
The decrease in fatigue life of solder joints under the high-temperature environment is a critical issue in semiconductor packages for automotive applications. To evaluate the deterioration of solder joints under high temperature, we studied the analytical method considering the decrease in yield-stress due to the grain coarsening of solder. We found that the decrease in yield stress largely depends on the exposed temperature and the holding time by using the Sn3Ag0.5Cu solder specimen. The decreasing ratio of yield stress was determined by the degradation factor and the accumulative holding time. The predicted fatigue life of solder joints using FEM considering the decrease in yield stress agreed well with the results of thermal cycle test.
