A cooling device includes a heat sink having a top plate, a bottom plate spaced from the top plate and fins between the top and bottom plates, a first metal member laminated to the side of the top plate that is opposite from the fins, and a first insulator laminated to the first metal member. The top plate, the bottom plate and the first metal member are each made of a clad metal that is composed of a base metal and a brazing metal, so that the fins are brazed to the top and bottom plates, the first metal member is brazed to the top plate, and the first insulator is brazed to the first metal member.