| 摘要 |
PROBLEM TO BE SOLVED: To provide a wiring board which has high-density fine wiring having a width and interval of 20 μm or less even in a wiring conductor for a core.SOLUTION: A wiring conductor 4 for a core is formed by the steps of: bonding a first conductor layer 13 in a through hole 7 bored in an insulating plate 1 for the core having copper foils 11 laminated on both surfaces thereof through a primer resin layer P which can be roughened, and also charging a hole-filling resin 8; polishing and flattening both ends of the hole-filling resin 8 so that the layer of the copper foil 11 remains on the surface of the insulating plate 1; and removing the layers of the copper foils 11 on top and reverse surfaces of the insulating plate 1 by etching, roughening surface of the primer resin layer P, and then plating a second wiring conductor 14 onto the primer resin layer P and the hole-filling resin 8 by a semi-additive method. |
