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Power Modules / High Density Design

T29.2 - Transfer-Molded Power Module for Low Common-Mode Capacitance and Enhanced Thermo-Mechanical Reliability

Thursday, March 26, 2026
8:40 AM - 9:00 AM CT
Location: 217A
This paper presents a transfer-molded power module designed to enhance both electrical performance and thermo-mechanical reliability. The direct-bonded copper substrate incorporates a bottom copper etching structure and is filled with a low-permittivity epoxy. The etching layout is designed to effectively reduce common-mode capacitance while ensuring complete epoxy filling during transfer molding. A tunnel-shaped etching configuration is introduced to suppress void formation during encapsulation without compromising manufacturability. The proposed module allows more compliant thermal expansion between the epoxy and the substrate, thereby reducing stress at interfaces. Finite element based thermo-mechanical simulations and thermal cycling tests validate the improved structural robustness of the proposed module. In addition, the design flexibility afforded by the transfer-mold module configuration enables optimized bottom copper etching, resulting in a further 17 % reduction in common-mode capacitance compared with conventional design.