Silicon carbide (SiC) devices exhibit several advantages such as high withstand voltage, high temperature operation, and low losses compared to conventional Si devices. However, in order to take full advantage of SiC devices, it is necessary to improve the characteristics of the power module package. In particular, the electrical insulation properties of the package depend on the insulating substrates. In this study, we focused on the difference in the electric field strength distribution when the front and back copper foils are moved horizontally relative to the aluminum nitride substrate.
We performed a dielectric breakdown voltage test and an electric field analysis corresponding to the test. It was clarified that the dielectric breakdown voltage has a correlation with the electric field strength of the triple junctions, and the dielectric breakdown points coincide with the triple junctions of the copper foil, ceramic and encapsulant.