Local Interconnection Degradation of a Double-Sided Cooling SiC MOSFET Module Under Power Cycling

Due to the excellent performance of the silicon carbide (SiC) chip, it will increasingly be used in electric vehicle power conversion systems. Among different packaging options, the double-side cooling (DSC) package is considered a superior choice for packing SiC chips due to its exceptional cooling capacity and low parasitic inductance of DSC modules. As DSC modules have multiple interconnections, each interconnection is under different stresses during the power cycling test (PCT). Hence, the degradation of overall thermal resistance and local thermal resistance needs to be evaluated separately during the PCT. In this study, a double-sided cooling SiC MOSFET module was fabricated, and its excellent electrical performance was characterized at a high temperature of 175 °C. The SiC MOSFET body diode forward voltage of the DSC module was only increased by less than 1.5%, although the local area-accounted thermal resistance and overall thermal resistance increased by 26.03% and 20.51%, respectively. The increase rate of the local thermal resistance is greater than that of the overall thermal resistance due to the different thermo-mechanical strains in each interconnection. Therefore, for the DSC SiC MOSFET modules, it is critical to pay more attention to the local thermal resistance degradation than the overall one.