I. Introduction
Wide-bandgap (WBG) medium-voltage (MV) power devices are being developed for grid applications [1–7]. A major challenge for using these devices is their packaging, of which insulation is the most concerning [4], [8]. Insulation of a typical MV power package relies on the ceramic of direct-bond-copper (DBC) substrate and silicone gel encapsulating the device and substrate. The different types of materials in a package form interfaces separating two dissimilar materials and triple points where three different materials come together [8], [9]. Triple points (TPs) are the most problematic for insulation because at which the electric field (E- field) strength often is many times higher than the nominal strength. Partial discharges (PDs) often are initiated at TPs to cause insulation failure.