Multilayered Wiring Board and Method of Manufacturing the Same

A method of manufacturing a multilayered wiring board having a stack structure multilayered by alternately stacking a plurality of conductor layers and a plurality of resin insulation layers including a same resin insulation material as a main component, a plurality of first main surface side connecting terminals being arranged in a first main surface side of the stack structure, a plurality of second main surface side connecting terminals being arranged in a second main surface side of the stack structure, the plurality of conductor layers being formed in the plurality of resin insulation layers and connected to each other through via conductors tapered such that diameters thereof are widened toward the first main surface side or the second main surface side, the method comprising:

• a process of forming a metal conductor portion corresponding to the first main surface side connecting terminal or the second main surface side connecting terminal on a base material;
• a build-up process of forming, after the process of forming the metal conductor portion, a stack structure multilayered by alternately stacking the plurality of conductor layers and the plurality of resin insulation layers;
• a process of forming, after the build-up process, connecting terminals including a plurality of the first main surface side connecting terminals and a plurality of the second main surface side connecting terminals within a plurality of openings in an outermost resin insulation layer by removing the base material while a part of the metal conductor portion remains;
• and
• a process of forming, after the process of forming connecting terminals, a solder resist on the outermost resin insulation layer, a part of the solder resist extending into the plurality of the openings and making contact with an outer circumference portion of outer surfaces of the connecting terminals.