Semiconductor device and inverter unit

Semiconductor chips (2, 3) are mounted on a heat sink (1). The frame (4) is bonded to the upper surfaces of the semiconductor chips (2, 3). A recess (10) is provided on the upper surface of a molding resin (9) that encapsulates the heat sink (1), the semiconductor chips (2, 3), and the frame (4). A heat dissipation plate (12) is attached to the outside of the recess (10) with a heat conduction material (11) having a higher thermal conductivity than the molded resin (9) interposed therebetween. The heat dissipation plate (12) is insulated from the semiconductor chips (2, 3) and the frame (4) by the molding resin (9). The heat dissipation plate (12) is a flat plate in which the upper surface and the lower surface facing each other are flat. 在散热器(1)之上安装有半导体芯片(2、3)。框架(4)与半导体芯片(2、3)的上表面接合。在将散热器(1)、半导体芯片(2、3)及框架(4)封装的模塑树脂(9)的上表面设置有凹部(10)。在凹部(10)隔着导热率比模塑树脂(9)高的导热材料(11)而外置安装有散热板(12)。散热板(12)通过模塑树脂(9)与半导体芯片(2、3)及框架(4)绝缘。散热板(12)为彼此相对的上表面和下表面分别平坦的平板。