Abstract
Wide bandgap semiconductors such as SiC and GaN have superb properties in breakdown strength, temperature resistance, and efficiency. Due to the widespread use of wide bandgap devices, the power density is required to be as high as possible and the key approach is to increase the working voltage and decrease the packaging size. The packaging insulation of high-voltage power modules such as SiC MOSFET should withstand high multi-physics stress and guarantee reliability. The electric field distribution is highly related to the electrical conductivity of packaging insulation since the electric stress in the packaging insulation is either constant DC voltage or unipolar square wave voltage due to the intrinsic body diode of SiC MOSFET. However, the non-linear conductivity and its coupling relationship with the electric field and temperature have not been investigated before. In this paper, a multi-physics analysis of electric field and temperature in high-voltage SiC MOSFET power modules is proposed. The non-linear electrical conductivity of packaging insulation materials (encapsulation and substrate ceramic) is measured and analyzed to derive an expression. Then a half-bridge SiC MOSFET is modeled in multi-physics software and the non-linear conductivity is considered to simulate the transient distribution of electric field and temperature in the packaging, especially at the key triple point positions. To use the multi-physics in the packaging insulation, an optimization procedure is proposed for future high-voltage power module design and fabrication.
Published Version
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