PURPOSE: To eliminate a fear of drop of a heat sink plate by providing an exposed recess extending into a second base material and the plate, exposing adhesive in the recess on the same surface, and completely forming a metal plated layer with the exposed recess when the rear side of the second material is covered with a metal plated layer.

CONSTITUTION: A first base material 1A provided with a conductor circuit 94, a second base material 1B, a heat sink plate 2 held and secured through an adhesive 3 between both, and a recess 13 for placing an electronic component to be spot faced with the top of the plate 2 through the adhesive 3 to the material 1A at the material 1A side are provided. The rear side of the plate 2 is partly exposed from a stepped hole 11B formed at the material 1B. An exposed recess 4 exposed on the same surface as the adhesive 3 and extending into the material 1B and the plate is formed by spot facing. The rear sides of the plate 2, the recess 4 and the material 1B are covered with continuously metal plated layer 75. A metal plated layer 76 is formed on the inner surface of the recess 13, and a conductor circuit 94 is formed on the material 1A.