A Double-Sided Cooled Split-Phase SiC Power Module with Fuzz Button Interposer

Power modules are the core components of the powertrain of hybrid and battery electric vehicle (EV) and has a significant impact on system performance and reliability. Conventional single-sided cooled (SSC) wire-bonded power modules have limitation to utilize the benefits offered by new generations of silicon carbide (SiC) devices due to higher parasitic inductance and heat dissipation issues. Planar, low-profile, and double-sided cooled (DSC) power modules are emerging in inverters of EV powertrain to address the limitations of conventional SSC modules. However, there is a reliability concern introduced by the rigid interconnection between the device chips and two substrates of the DSC power module. In this article, the design and development of a DSC, 1200-V/150-A SiC half-bridge split-phase power module have been presented, where flexible compressible pins called 'fuzz buttons' are used in a low-profile printed circuit board (PCB) to realize die top-side connection. Our simulation result shows a 45% reduction of thermomechanical stress at the interposer-dies interface with a total power loss of 1300 W (200-W/SiC MOSFET and 125-W/SiC Schottky diode). The feature of double-sided cooling helps to reduce the maximum junction temperature of the dies by 26%, compared to single-sided cooling. Moreover, the vertical commutation loop and utilization of copper layer in PCB-based fuzz button retainer board help to achieve a power loop inductance as low as 1.51 nH.