Comparison of Thermal-Fatigue Lives of Conventional and Hybrid Solder Joints: Experiment and FE Analysis

This paper presents experimental and numerical results of thermal-fatigue lives of conventional and hybrid solder joints of memory module. Thermal fatigue test is performed for three loading cases having different the maximum temperature and temperature range, from which crack initiation cycles and crack propagation rates are measured. It shows that measured crack initiation cycles are similar and much smaller than failure cycles for all cases. Measured crack propagation rates, however, vary significantly depending on the conditions. Measured crack propagation rates for the hybrid solder joints are more than twice, compared to that of conventional solder joints. For analysis, elastic-visco-plastic FE analysis using the Anand unified visco-plastic model combining plasticity and creep is performed, from which the volume-average value of inelastic dissipation energy density per cycle is calculated at the crack initiation location. To quantify thermal-fatigue lives of conventional and hybrid solder joints, four parameters in the energy-based Darveaux model are determined for conventional and hybrid solder joints from present experimental and FE analysis results.