| 摘要 |
PURPOSE: To improve the cooling property of a device by providing a heat transfer layer with a high heat transfer rate between one wire and the other wire of a multilayer wiring substrate. CONSTITUTION: A semiconductor pellet 5 is mounted on the pellet-mounting surface of a multilayer wiring substrate 1 and a first heat transfer layer 1D is provided on the reverse side opposing the pellet-mounting surface of the multilayer wiring substrate 1. Then, the first heat transfer layer 1D is connected between one wiring 1B of the multilayer wiring substrate and the other wiring 1C and a second heat transfer layer 4 with a high heat transfer rate as compared with the insulation layer 2 of the multilayer wiring substrate 1 is provided. As a result, heat generated by the operation of the circuit system of the semiconductor pellet 5 is transferred to a second heat transfer layer 4 via one insulation layer 2 of the multilayer wiring substrate 1 screened by the second heat transfer layer 4 and further is transferred to the first heat transfer layer 1D. Namely, the thermal resistance of the multilayer wiring substrate 1 can be reduced by the amount equivalent to the other insulation layer 2 of the multilayer wiring substrate 1. |
