Power Semiconductor Module With Low-Permittivity Material to Reduce Common-Mode Electromagnetic Interference

The layout of a low-permittivity material is designed in a power semiconductor module to reduce parasitic common-mode (CM) capacitance and hence attenuate the CM current. Without sacrificing the thermal performance between the semiconductor devices and heat sink, a portion of the bottom copper of a direct-bond-copper substrate is replaced by air to decrease capacitance. The proposed power module is verified in a 1-kW 100-kHz buck converter. The CM current is decreased by 8 dB in the frequency domain without any additional components or filters.