Reliability Evaluation on Deterioration of Power Device Using Coupled Electrical-Thermal-Mechanical Analysis

Abstract

This paper presents a simulation method to evaluate the thermal fatigue life of a power module. A coupled electrical-thermal analysis was performed to obtain the nonuniform temperature distribution of electric current. Then, a thermomechanical analysis was carried out based on the temperature distribution from the electrical-thermal analysis. Since crack propagation can change the route of heat transfer, a crack path simulation technique was used to investigate the fracture behavior of the power module. The crack initiates in the solder joint below the Al bonding wire of the insulated gate bipolar transistor module and propagates by increasing the diameter. The effect of the bonding type on power cycling fatigue life is also discussed. The fracture process was found to depend on the type of bonding. Lead frame bonding was found to be more effective than wire bonding.