Patent ID: 8759691

Claim:
A wiring board, comprising: a first resin insulation layer; a first conductive pattern formed on the first resin insulation layer; a second resin insulation layer formed on the first conductive pattern and having an opening portion exposing at least a portion of the first conductive pattern; a second conductive pattern formed on the second resin insulation layer; and a via conductor formed in the opening portion of the second resin insulation layer and electrically connecting the first conductive pattern and the second conductive pattern, wherein the via conductor has a side surface extending between the first conductive pattern and the second conductive pattern and a bent portion where an inclination of the side surface of the via conductor changes in a depth direction of the via conductor, the via conductor tapers from the bent portion toward the first conductive pattern and includes a tapered portion decreasing in size from the bent portion toward the first conductive pattern and a non-tapered portion such that the bent portion forms a boundary between the tapered portion and a non-tapered portion, the second resin insulation layer is formed with a plurality of layers having different elastic coefficients, and the bent portion of the via conductor is formed in a layer having the lowest elastic coefficient among the plurality of layers forming the second resin insulation layer.