Patent ID: 8151456

Claim:
A method of producing a core substrate, comprising: forming a pilot hole in a base member, the base member including a core section composed of carbon fiber-reinforced plastic, copper foils being bonded on both surfaces of the core section with prepregs; coating an inner face of the pilot hole with a plated layer by electroless-plating; electrolytic-plating the base member subsequent to the electroless-plating of the inner face of the pilot hole; filling the pilot hole, whose inner face has been coated with the plated layer, with an insulating material composed of resin; forming resist patterns, which coat planar areas of the pilot hole and edges of the pilot hole with a prescribed width, on both surfaces of the base member by laminating photoresist thereon and exposing and developing the photoresist; forming copper foil patterns along the edges of the pilot hole and exposing the prepregs in both surfaces of the core section by etching the copper foils with using the resist patterns as masks; removing the resist patterns; integrating cable layers with the base member by successively placing a first additional prepreg, a cable sheet, in which cable patterns are formed on both surfaces of an insulating sheet, a second additional prepreg, and an additional copper foil, on each of the surfaces of the base member, and pressurizing and heating the cable layers to thermally cure the first additional prepregs and the second additional prepregs; coaxially forming a through-hole, whose diameter is smaller than that of the pilot hole and that penetrates the cable layers and the base member, with the pilot hole so as to expose the insulating material as an inner face; forming a plated through-hole on the inner face of the through-hole by electroless copper plating and electrolytic copper plating; filling the through-hole with resin; and etching the additional copper foils so as to form additional cable patterns on the both surfaces of the base member.