Abstract: A wiring board of the present invention readily controls a power source voltage and unwanted irradiation noises developed across a power source layer and a ground layer over a broad range of frequencies with a simple arrangement. The wiring board has an on-board surface on the surface of a dielectric substrate, on which a semiconductor device or the like is mounted, and a power source layer and a ground layer, which are made of a conductor material principally composed of at least one kind of element selected from Cu, W, and Mo, are provided on the back surface of the dielectric substrate or within the same. The periphery of at least one of low resistance areas of the power source layer and ground layer, respectively is provided with a corresponding high resistance area having a higher sheet resistance than that of the respective low resistance areas.

Abstract: A wiring board of the present invention readily controls a power source voltage and unwanted irradiation noises developed across a power source layer and a ground layer over a broad range of frequencies with a simple arrangement. The wiring board has an on-board surface on the surface of a dielectric substrate, on which a semiconductor device or the like is mounted, and a power source layer and a ground layer, which are made of a conductor material principally composed of at least one kind of element selected from Cu, W, and Mo, are provided on the back surface of the dielectric substrate or within the same. The periphery of at least one of low resistance areas of the power source layer and ground layer, respectively is provided with a corresponding high resistance area having a higher sheet resistance than that of the respective low resistance areas.