Abstract: A wiring substrate includes a core substrate, a build-up part formed on a surface of the substrate and including insulating layers and conductor layers, and a covering insulating layer formed on the build-up part such that the covering layer is covering the outermost surface of the build-up part. The build-up part is formed such that the insulating layers include a first insulating layer forming the outermost one of the insulating layers, that the conductor layers include a first conductor layer formed on the first insulating layer and including a first conductor pad, and that an elongation rate of the first insulating layer is greater than an elongation rate of each insulating layer other than the first insulating layer in the build-up part, and the covering layer is formed such that the covering layer has an opening entirely exposing an upper surface and a side surface of the first conductor pad.

Abstract: A wiring substrate includes a core substrate, a build-up part formed on a surface of the substrate and including insulating layers and conductor layers, and a covering insulating layer formed on the build-up part such that the covering layer is covering the outermost surface of the build-up part. The build-up part is formed such that the insulating layers include a first insulating layer forming the outermost one of the insulating layers, that the conductor layers include a first conductor layer formed on the first insulating layer and including a first conductor pad, and that a tensile strength of the first insulating layer is higher than a tensile strength of each insulating layer other than the first insulating layer in the first build-up part, and the covering layer is formed such that the covering layer has opening entirely exposing an upper surface and a side surface of the first conductor pad.