Electrically isolated semiconductor power device

Abstract

An improved power semiconductor device and manufacturing method are described wherein the external, thermally conducting, heat transfer face of the device is electrically insulated by a glassy dielectric which is intimately bonded directly to the conductive heat spreader supporting the semiconductor die. By forming the exposed corners of the heat spreader to be substantially smooth curved surfaces having a predetermined minimum radius of curvature greater than the thickness of the glassy dielectric, formation of a ridge of glass at the corners and edges of the heat spreader is avoided. For ease of assembly the piece parts are initially substantially flat and parallel. A molding compound of controlled shrinkage is used to avoid distorting the substantially flat smooth insulated heat transfer face which remains exposed in the encapsulated device.