Method for producing a printed wiring board

A method of manufacturing a printed wiring board comprising:

• forming a seed layer comprising metal over a lower resin insulation layer;
• forming a plating resist on the seed layer such that a first portion of the seed layer is covered by the plating resist and a second portion of the seed layer is not covered by the plating resist;
• subjecting the seed layer and the plating resist to an electrolytic plating process so as to form an electrolytic plated film on the second portion of the seed layer;
• removing the plating resist from the first portion of the seed layer;
• removing the first portion of the seed layer to form a conductor circuit comprising the seed layer and the electrolytic plated film over the lower resin insulation layer, wherein said conductor circuit is formed to have a flat surface;
• forming a metal layer on an entire surface of the conductor circuit, the metal layer comprising Sn in order to improve adhesion of the metal layer to a resin material;
• and
• forming an upper resin insulation layer over the conductor circuit and the metal layer comprising Sn such that the upper resin insulating layer has improved adhesion to the conductor circuit.