Design and Optimization of a Novel Monolithic Spring for High-frequency Press-pack SiC FET Modules

This work is an integral element of the effort to develop high-frequency press-pack (HFPP) SiC FET modules for emergent grid-oriented power converters. The primary packaging challenge for high-frequency, small-area SiC FET dies resides in the press-contact design. As opposed to the conventional inefficient disc spring for press-pack IGBTs, this work proposes a novel monolithic spring (MS) for HFPP SiC modules by cutting airgap slits from a beryllium–copper block. This paper focuses on the design and optimization approach for MS development. The perforations are made perpendicular to the MS’s deflection direction in order to achieve the desired displacement, linear spring constant, minimal stray inductance, and high-frequency body resistance. Modeling, FEA simulation, and experimental validation are presented.