Patent ID: 8415801

Claim:
A semiconductor device comprising: a circuit board formed by integrally bonding a first metal plate and a second metal plate to both surfaces of an insulating substrate respectively, at least one semiconductor element bonded to an external surface of the first metal plate through a first solder, and a radiating base plate bonded to an external surface of the second metal plate through a second solder, wherein the first solder and the second solder are constituted by solder materials of the same type, wherein an average coefficient of thermal expansion of the circuit board is set to satisfy a plurality of endurance cycles in accordance with endurance characteristics of the first and second solders, and wherein a sum of thicknesses of the first metal plate and the second metal plate and a thickness of the insulating substrate are set based on a relationship between the average coefficient of thermal expansion and a ratio of the sum of thicknesses of the first metal plate and the second metal plate to the thickness of the insulating substrate.