Printed wiring board

A printed wiring board, comprising:

• a core insulation layer comprising a resin and having a via conductor comprising a plating material filling a hole formed through the core insulation layer;
• a first laminated structure formed on a first surface of the core insulation layer and comprising a first conductive layer, an interlayer insulation layer and a second conductive layer;
• and
• a second laminated structure formed on a second surface of the core insulation layer on an opposite side of the first surface of the core insulation layer and comprising a first conductive layer, an interlayer insulation layer and a second conductive layer,
• wherein the first conductive layer of the first laminated structure is formed on the first surface of the core insulation layer and comprises a copper foil laminated on the first surface of the core insulation layer and a plated film formed on the copper foil, the interlayer insulation layer of the first laminated structure is formed on the first conductive layer of the first laminated structure, comprises a resin and has a via conductor comprising a plating material filling a hole formed through the interlayer insulation layer of the first laminated structure, the second conductive layer of the first laminated structure is formed on the interlayer insulation layer of the first laminated structure and comprises a copper foil laminated on the interlayer insulation layer of the first laminated structure and a plated film formed on the copper foil of the second conductive layer of the first laminated structure, the first conductive layer of the second laminated structure is formed on the second surface of the core insulation layer and comprises a copper foil laminated on the second surface of the core insulation layer and a plated film formed on the copper foil of the first conductive layer of the second laminated structure, the interlayer insulation layer of the second laminated structure is formed on the first conductive layer of the second laminated structure, comprises a resin and has a via conductor comprising a plating material filling a hole formed through the interlayer insulation layer of the second laminated structure, the second conductive layer of the second structure is formed on the interlayer insulation layer of the second laminated structure and comprises a copper foil laminated on the interlayer insulation layer of the second laminated structure and a plated film formed on the copper foil of the second conductive layer of the second laminated structure, each of the first conductive layers of the first and second laminated structures includes a conductive circuit, each of the second conductive layers of the first and second laminated structures has a conductive circuit connected to the conductive circuit in a respective one of the first conductive layers of the first and second laminated structures through the via conductor in a respective one of the interlayer insulation layers of the first and second laminated structures, each of the core insulation layer and the interlayer insulation layers has a dielectric constant of 4.0 or lower at a signal frequency of 1 GHz and a thermal expansion coefficient of 85 ppm/° C. or lower at or below Tg, and the copper foil of the first conductive layer in each of the first and second laminated structures has a thickness which is set greater than a thickness of the copper foil of the second conductive layer in each of the first and second laminated structures.