Patent ID: 8040708

Claim:
A semiconductor device including a DC-DC converter, comprising: (a) a high-side semiconductor chip in which a high-side MOSFET of the DC-DC converter is formed and which has a gate electrode pad, a source electrode pad, and a drain electrode of the high-side MOSFET; (b) a low-side semiconductor chip in which a low-side MOSFET of the DC-DC converter is formed and which has a gate electrode pad, a source electrode pad, and a drain electrode of the low-side MOSFET; (c) a driver semiconductor chip in which a driver circuit of the high-side MOSFET and the low-side MOSFET is formed; (d) a high-side chip mounting part over which the high-side semiconductor chip is mounted; (e) a low-side chip mounting part over which the low-side semiconductor chip is mounted; (f) a driver chip mounting part over which the driver semiconductor chip is mounted; (g) a high-side metal plate that electrically connects the source electrode pad of the high-side MOSFET provided on the high-side semiconductor chip and the low-side chip mounting part; and (h) a sealing body that covers a part of the high-side chip mounting part, apart of the low-side chip mounting part, a part of the driver chip mounting part, the high-side semiconductor chip, the low-side semiconductor chip, the driver semiconductor chip, and the high-side metal plate, wherein, on the top surface of the low-side chip mounting part, a low-side chip connecting plated layer formed in a region where the low-side semiconductor chip is mounted and a metal plate connecting plated layer formed in a region where the high-side metal plate is joined are provided, and wherein the low-side chip connecting plated layer and the metal plate connecting plated layer are separated.