Patent ID: 8563872

Claim:
A wiring board comprising an insulating resin layer, a plurality of wirings laid via the insulating resin layer, and at least one via-hole conductor provided in a through-hole and configured to pierce the insulating resin layer for electrically connecting the wirings, wherein the via-hole conductor includes metal and resin portions, and the resin portion forms a matrix in which the metal portion is embedded, the metal portion including at least copper, tin, and Bi, and have a weight ratio (Cu/Sn) of Cu to Sn in the metal portions in the range from 1.59 to 21.43, the metal portion comprises three metal regions, including copper regions made of copper (Cu) particles, first metal regions, and second metal regions, the copper particles are in contact with one another via plane contact portions, thereby electrically connecting the wirings, the first metal regions are mainly composed of tin (Sn), a tin-copper alloy, and/or a tin-copper intermetallic compound, with at least part thereof covering around and extending over the plane contact portions of the copper particles, the second metal regions are mainly composed of bismuth (Bi), and the at least one via-hole conductor is sandwiched between a pair of the plurality of wirings, each of the pair of wirings at least partially covers either a top end or a bottom end of the through-hole.