Directly Integrated Vapor Chamber as an Efficient Heat Spreader for High Heat Flux Density SiC MOSFET Dies in Power Modules

Wide-bandgap (WBG) semiconductors devices such as silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) can handle much higher voltage and current in a relatively small die size than their Si counterpart. However, the shrinkage in die size poses new challenges to the thermal management systems for SiC MOSFET power modules. As a two-phase cooling component, vapor chamber (VC), has extremely high thermal conductivity with benefits including light weight, low cost and uniform temperature distribution, making it promising in SiC power module packaging. This paper proposes a new packaging design in which SiC bare dies are directly integrated on the top of vapor chambers. In this design, the vapor chamber not only is a heat spreader, but also conducts the drain current of SiC MOSFETs. The VCs in this study are optimized to improve the thermal performance and reduce the thermal stress in the die solder layer. SiC power module prototypes directly integrated with VCs are built using a new fabrication process. The modules integrated with VCs can operate under 200 W of power dissipation per die (632 W/cm2) without exceeding the maximum rated junction temperature. This paper reveals the potential of directly integrating phase change cooling components inside power modules, providing a new solution to improve the thermal performance and reliability of SiC power modules without adding complexity and energy consumptions to external cooling systems.