SEMICONDUCTOR DEVICE

A semiconductor device includes a printed board, an electronic component, and a thermal diffuser. The electronic component and the thermal diffuser are bonded onto one main surface of the printed board. The electronic component and the thermal diffuser are electrically and thermally bonded to each other by a bonding material. The printed board includes an insulating layer and a plurality of radiation vias penetrating from the main surface to the other main surface of the printed board. At least a part of the plurality of radiation vias overlaps the electronic component, and at least another part of the plurality of radiation vias overlaps the thermal diffuser. At least a part of the plurality of radiation vias is disposed so as to overlap a heat radiator at a transmission viewpoint from the main surface of the printed board.