Header for semiconductor device, and semiconductor device

Abstract

A header for a semiconductor device, includes a main body section having an upper surface, and a cavity formed in the upper surface, a heat dissipation section provided on the upper surface of the main body section, and a wiring board provided inside the cavity. The wiring board includes a substrate having a first principal surface, and a second principal surface provided on an opposite side from the first principal surface, a first conductor pattern provided on the first principal surface, and having a mounting section on which a semiconductor element is mounted, and a second conductor pattern provided on the second principal surface, and bonded to an inner wall surface of the cavity and the heat dissipation section. A portion of the first conductor pattern extends beyond the heat dissipation section when viewed in a thickness direction of the wiring board.