Geometrical Design of Ceramic Substrate for High Voltage Power Modules

High blocking voltage of wide bandgap (WBG) devices will improve the power density and power capacity in power electronic systems. However, such high voltage level of WBG devices can result in partial discharges (PDs) in power modules and threat the reliability of modules. Sources of PDs lie in the triple points between ceramic, silicone gel and metallization in power modules. The triple points combine electric field enhancement and insulation material defects (interface of ceramic and silicone gel). This paper focuses on the triple points and designs a new geometry of ceramic substrate. The new geometry is studied by finite element simulation in COMSOL Multiphysics. In the new designed ceramic substrate, the triple point is moved from the edge of metallization to a location where the electric field stress is lower. Moreover, in the new geometry, increasing the height ratio of silicone gel under the protruding metallization can relieve the high electric field stress at the edge of metallization.