A 3.3-kV Press-Pack SiC Power Module With Diamond/Cu Source Blocks: Design, Fabrication, and Experimental Validation

This paper presents a 3.3-kV press-pack silicon carbide (SiC) power module that integrates Diamond/copper (Diamond/Cu) blocks with fuzz-button gate interconnects to reduce thermal resistance and mitigate thermomechanical stress. The low-CTE, high-thermal-conductivity Diamond/Cu source blocks reduce junction-to-fluid thermal resistance and mitigate die-block interfacial thermomechanical stress. Meanwhile, the fuzz-button gate routing places the gate path away from the high voltage drain region, easing insulation constraints at 3.3-kV ratings. Shear-lag and laminate models are used to relate block CTE and thermal conductivity to die-surface shear and normal stresses, providing guidance for source-block material selection. Thermomechanical simulations compare the press-pack module with molybdenum (Mo) and Diamond/Cu source blocks and predict a 22% reduction in the thermomechanical stress at the source interface when Mo is replaced by Diamond/Cu. Finally, a prototype was fabricated and tested: the measured junction-to fluid thermal resistance is 0.52 K/W, and double-pulse tests at a 1.8-kV dc-link voltage and 60-A current exhibit 9% switching overvoltage, demonstrating the feasibility of the proposed architecture under medium-voltage (MV) operating conditions.