US Patent 8446013 Wiring substrate and method for manufacturing the wiring substrate

A wiring substrate includes a substrate body including a first substrate surface and a second substrate surface, a trench being open toward the first substrate surface, the trench having an inner bottom surface and an inner side surface, a through-hole having a first end communicating with the inner bottom surface of the trench and a second end being open toward the second substrate surface, a first conductive layer having a first surface toward the trench and being filled inside at least a portion of the through-hole from the second end, a second conductive layer covering the first surface and at least a part of the inner bottom surface of the trench, and a third conductive layer covering the second conductive layer and being filled inside the trench.