A Solution to Press-Pack Packaging of SiC MOSFETS

This paper proposes a packaging method for SiC MOSFETs that provides a feasible solution of implementing press-pack packaging on SiC MOSFETs to extend the application of SiC devices into the high power range. The challenges in realizing press-pack packaging of SiC MOSFETs are addressed, and the solutions are proposed that fit the specific requirements of SiC MOSFET. To achieve pressure contact on SiC MOSFETs, miniature and flexible press pins called “fuzz buttons” are used in a low-profile interposer to realize die top side connection. Since the press-pack does not provide internal insulation between the active device and the heatsink, the heatsink is included in the power loop. To avoid large parasitic loop inductance being introduced by the heatsinks, a microchannel heatsink is developed which has a low thickness while remaining adequate heat dissipation efficiency. The structure and assembly process flow of the press-pack SiC MOSFET are provided. A half-bridge stack prototype with two press-packs and three heatsinks is developed. The thermal and electrical performances of the press-pack and the half-bridge stack are evaluated by simulations and tests to validate the feasibility of the proposed packaging approach.