Finite element modelling of thermal fatigue effects in IGBT modules

The aim of this paper is to demonstrate the use of finite element techniques for modelling of thermal fatigue effects in solder layers of insulated gate bipolar transistor (IGBT) modules during traction cycles. The three-dimensional models presented allow predictions of how the solder fatigue affects the thermal performance of the device under static loading conditions. In this paper, the analysis of an 800 A-1800 V IGBT module is performed. The parameters assessed are the thermal resistance, maximum junction temperature and heat flux distribution through different layers in the module construction. The critical crack length at which the thermal resistance and subsequently the chip temperature increase significantly is also determined through two-dimensional simulation. Calibration of the models is achieved by comparing simulation results with manufacturer's data, theoretical calculations and experimental measurements.