| abstract |
A multilayer wiring board includes an insulating resin layer, wirings laid on their respective opposite surfaces of the insulating resin layer, and a via-hole conductor for electrically connecting the wirings. The via-hole conductor includes metal and resin portions. The metal portion includes first metal regions including a joined unit made of copper particles for connecting the wirings, second metal regions mainly composed of, for example, tin, a tin-copper alloy, or a tin-copper intermetallic compound, and third metal regions mainly composed of bismuth and in contact with the second metal regions. The copper particles forming the joined unit are in plane contact with one another to form plane contact portions, and the second metal regions at least partially are in contact with the first metal regions. |