As shown in FIG. 10, the coated portion 42 covers at least a part of the lower surface 40 of the graphite sheet 4 that is not in contact with the heat conductive portion 5. The coated portion 42 covers the shielded surface 40b. Since the coated portion 42 is provided to cover the circuit-board-side surface of the graphite sheet 4, it is possible to prevent small pieces of the graphite sheet 4 from falling onto the circuit board.

The coated portion 42 is provided so that the inner periphery portion 42a is located inside the outer periphery portion 51 of the heat conductive portion 5. An inner periphery portion 42a side part of the coated portion 42 is interposed at a position between the graphite sheet 4 and the heat conductive portion 5. The coated portion 42 is provided so that an outer periphery portion 42b covers the outer periphery portion 41 of the graphite sheet 4.

The coated portion 42 is a thin layer formed of a material such as a thin metal or resin. The coated portion 42 may be made of polyethylene, polyvinyl, or rubber. The coated portion 42 may be configured by attaching a sheet-like body to the lower surface 40 of the graphite sheet 4. The coated portion 42 may be formed by applying/painting the above-mentioned material and solidifying it. Since the coated portion 42 is in the form of a thin sheet, it can be made thinner as a component, which contributes to suppressing the manufacturing cost.