Abstract: A printed wiring board includes a core substrate, a first build-up layer, and a second build-up layer. Each build-up layer includes a first insulating layer including reinforcing material, a second resin insulating layer not containing reinforcing material, a first via conductor through the first insulating layer, and a second via conductor through the second insulating layer such that the top diameter of the first via conductor is substantially equal to the top diameter of the second via conductor and that the bottom diameter of the first via conductor is smaller than the bottom diameter of the second via conductor. The conductor layer on the first insulating layer includes a metal foil, a seed layer and an electrolytic plating film. The conductor layer on the second insulating-layer includes a seed layer and an electrolytic plating film and has thickness substantially equal to thickness of the conductor layer on the first insulating-layer.

Abstract: A printed wiring board includes a core substrate, a first build-up layer, and a second build-up layer. Each build-up layer includes a first insulating layer including reinforcing material, a second resin insulating layer not containing reinforcing material, a first via conductor through the first insulating layer, and a second via conductor through the second insulating layer such that the top diameter of the first via conductor is substantially equal to the top diameter of the second via conductor and that the bottom diameter of the first via conductor is smaller than the bottom diameter of the second via conductor. The conductor layer on the first insulating layer includes a metal foil, a seed layer and an electrolytic plating film. The conductor layer on the second insulating-layer includes a seed layer and an electrolytic plating film and has thickness substantially equal to thickness of the conductor layer on the first insulating-layer.

Abstract: A wiring board with a built-in electronic component includes a core substrate, an electronic component in the substrate, a first upper-layer structure on first surface of the substrate, a second upper-layer structure on second surface of the substrate, and via conductors in the substrate and first upper-layer structure such that the via conductors are connected to an electrode of the component. The substrate has an accommodating layer, a first connection layer on first surface of the accommodating layer, and a second connection layer on second surface of the accommodating layer, the accommodating layer includes inner wiring and insulation layers and has cavity accommodating the component, the first connection layer includes inner wiring and insulation layers, and the second connection layer includes inner wiring and insulation layers such that the second connection layer includes greater number of inner wiring and insulation layers than the first connection layer.

Abstract: A method for manufacturing a wiring board with a built-in electronic component includes positioning an electronic component in a cavity of a substrate, forming intermediate structures each including an intermediate insulation layer and an intermediate wiring-pattern layer on upper and lower surfaces of the substrate, respectively, such that a component-accommodating substrate is formed, attaching a support sheet to a first surface of the component-accommodating substrate, forming a connection layer including insulation layers and wiring-pattern layers on a second surface of the component-accommodating substrate on the opposite side with respect to the first surface of the component-accommodating substrate, removing the support sheet from the component-accommodating substrate such that an intermediate laminate structure having the connection layer laminated on the second surface of the component-accommodating substrate is formed, and forming upper-layer structures each including an insulation layer and a wirin

Abstract: A wiring board with a built-in electronic component includes a core substrate, an electronic component in the substrate, a first upper-layer structure on first surface of the substrate, a second upper-layer structure on second surface of the substrate, and via conductors in the substrate and first upper-layer structure such that the via conductors are connected to an electrode of the component. The substrate has an accommodating layer, a first connection layer on first surface of the accommodating layer, and a second connection layer on second surface of the accommodating layer, the accommodating layer includes inner wiring and insulation layers and has cavity accommodating the component, the first connection layer includes inner wiring and insulation layers, and the second connection layer includes inner wiring and insulation layers such that the second connection layer includes greater number of inner wiring and insulation layers than the first connection layer.