Sensitivity of Solder Joint Fatigue to Sources of Variation in Advanced Vehicular Power Electronics Cooling

This paper demonstrates a methodology for taking variation into account in the thermal and fatigue analyses of the die attach for an inverter of an electric traction drive vehicle. This method can be used to understand how variation and mission profile affect parameters of interest in a design. Three parameters are varied to represent manufacturing, material, and loading variation: solder joint voiding, aluminum nitride substrate thermal conductivity, and heat generation at the integrated gate bipolar transistor, or IGBT. The influence of these parameters on temperature and solder fatigue life is presented. The heat generation loading variation shows the largest influence on the results for the assumptions used in this problem setup.