Comparative Study of Thermal Performance of a SiC MOSFET Power Module Integrated with Vapor Chamber for Traction Inverter Applications

Abstract

Silicon carbide metal-oxide-semiconductor field-effect transistors (SiC MOSFETs) has the potential to replace silicon-based insulated gated bipolar transistors (IGBT) in medium voltage range for the superiority of wide bandgap (WBG) devices. However, SiC MOSFET has a much smaller die size than Si IGBT, making it has a high thermal resistance and small heat capacitance. In real applications, the shrinkage in die size will lead to higher junction temperature and more significant junction temperature swing, reducing the lifetime and the reliability of the SiC power module. This paper proposes a new packaging design based on vapor chamber (VC) and compares its thermal performance with a conventional DBC module. Utilizing similar working principles as the heat pipes, VCs have advantages including high thermal conductivity, low weight and low cost. In this paper, the VCs are customized and integrated into the SiC power module with a new fabrication process. The FEM simulations along with the experiment demonstrated significant improvements on both steady-state and transient thermal performance compared with conventional direct bonded copper (DBC) substrate. The maximum junction temperature decreased by more than 31.7°C and the junction temperature swing deopped by 46% By comparing the thermal performance between the conventional module and VC integrated module, this paper reveals the effectiveness of integrating phase-change cooling components into SiC power modules.