Abstract: An electronic unit includes an electrolytic capacitor, a covering resin layer, and electronic components. The electrolytic capacitor is on an upper surface of an insulating substrate. The covering resin layer covers the upper surface of the insulating substrate and the electronic components. Part of the covering resin layer serves as an electrolytic capacitor covering portion. The electrolytic capacitor covering portion includes an outer peripheral covering portion that covers an outer peripheral surface of the electrolytic capacitor and a top covering portion that covers a top portion of the electrolytic capacitor. A thin wall groove is formed in the top covering portion. The outer peripheral covering portion extends upward beyond the top covering portion by a height h. The top covering portion easily breaks at the thin wall groove so that an explosion-proof valve easily operates. A region corresponding to the height h creates an operating space of the explosion-proof valve.

Abstract: A digital amplifier integrated circuit (“IC”), which is a heat-generating electronic component, is mounted on an upper surface of an insulating substrate. The digital amplifier IC is disposed inside a recess of a heat sink. The heat sink includes a peripheral wall having an end face placed on the upper surface of the insulating substrate. A hot-melt resin layer, molded by hot-melt molding, covers the upper surface of the insulating substrate. The hot-melt resin layer is in contact with a side face of the peripheral wall and retains the heat sink on the insulating substrate. The recess of the heat sink has no hot-melt resin therein.

Abstract: A digital amplifier integrated circuit (“IC”), which is a heat-generating electronic component, is mounted on an upper surface of an insulating substrate. The digital amplifier IC is disposed inside a recess of a heat sink. The heat sink includes a peripheral wall having an end face placed on the upper surface of the insulating substrate. A hot-melt resin layer, molded by hot-melt molding, covers the upper surface of the insulating substrate. The hot-melt resin layer is in contact with a side face of the peripheral wall and retains the heat sink on the insulating substrate. The recess of the heat sink has no hot-melt resin therein.

Abstract: An electronic unit includes an electrolytic capacitor, a covering resin layer, and electronic components. The electrolytic capacitor is on an upper surface of an insulating substrate. The covering resin layer covers the upper surface of the insulating substrate and the electronic components. Part of the covering resin layer serves as an electrolytic capacitor covering portion. The electrolytic capacitor covering portion includes an outer peripheral covering portion that covers an outer peripheral surface of the electrolytic capacitor and a top covering portion that covers a top portion of the electrolytic capacitor. A thin wall groove is formed in the top covering portion. The outer peripheral covering portion extends upward beyond the top covering portion by a height h. The top covering portion easily breaks at the thin wall groove so that an explosion-proof valve easily operates. A region corresponding to the height h creates an operating space of the explosion-proof valve.