Method of fabricating printed wiring board

A method of fabricating a printed wiring board, comprising:

• a step of preparing a core wiring board composed of a first conductor circuit pattern that is formed on at least one surface of an insulation layer;
• a step of forming an insulation resin layer on at least one surface side of the core wiring board to cover the first conductor circuit pattern;
• a step of forming a first resist layer on a predetermined region of a surface of the insulation resin layer;
• a step of forming a first metal layer with a plating method on a region of the surface of the insulation resin layer except the region where the first resist layer is formed;
• a step of forming a via hole by laser machining using the first metal layer as a mask to remove at least a predetermined region of the insulation resin layer and to expose part of a conductor layer formed on one side of the insulation resin layer that faces the core wiring board;
• a step of forming a second resist layer on a region of a surface of the first metal layer except the region around the via hole;
• a step of forming a second metal layer with a plating method on a region of the surface of the first metal layer except the region where the second resist layer is formed and on an inner surface of the via hole;
• a step of removing the second resist layer;
• a step of forming a third resist layer on a predetermined region of the surface of the first metal layer and on a surface of the second metal layer;
• and
• a step of forming a second conductor circuit pattern by etching the first metal layer using the third resist layer as a mask.