117 / 2022-03-13 19:59:20

Resistivity of Silicone Gel/Ceramic Substrate Interface in Power Modules

interface resistivity,Silicone Gel,Ceramic Substrate,Power Modules

 The high electric field stress at the triple points (silicone gel, ceramic substrate, and copper) posts a big challenge to development for high-voltage power modules. However, the resistivity of silicone gel/ceramic substrate interface, which is vital to electric field at triple points, is neglected. Therefore, this paper established an interface resistivity calculation model for interface resistance measured by four-electrode method. It was found that the silicone gel/ceramic interface resistance is different to surface resistance of bulk phase. Through the 430 nm gold layer, the interface resistivity was calculated approximately, which is lower than that of bulk phase for 4-5 order of magnitude. This is because that the molecule chains in interface region are easier to move and with higher relaxation frequency compared to bulk phase. The decrease in interface resistivity will increase the electric stress in silicone gel and ceramic bulk phase at triple points, which should be arouse great attention in the design for high-voltage power modules.