To reduce the temperature rise of electronic parts while the manufacturing cost of the electronic parts is reduced by constituting part of a casing of a metallic cover section, and attaching the electronic parts to the cover section in such a way that the heat generated from the electronic parts can be radiated.
Electronic parts 5 are soldered to a printed circuit board 2 and the board 2 is fixed to terminal fixing sections 3. To the bottom plate 7a of a cover section 7 formed by bending a metallic sheet, switch elements 8 are fixed respectively through adhesive sheets and copper sheets 9. In addition, another printed circuit board 6 is fixed to the cover section 7 by engaging the board 6 with the side plates 7b of the section 7. The copper sheets 9 are closely adhered and fixed to the cover section 7 while the sheets 9 are insulated from the section 7, so that the heat generated from the switch elements 8 may be spread and transferred extremely efficiently to the cover section 7. Therefore, the manufacturing time of a module power unit 1 can be shortened, because no heat transfer resin packing work is required. In addition, the heat generated from the switch elements 8 is not stored in the power unit 1, but can be radiated quickly to the air.
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