Patent ID: 7356917

Claim:
A method for manufacturing a multi-layer printed circuit board, the method comprising the steps of: preparing a strip-shaped conductive pattern film by forming a strip-shaped conductive pattern made of metallic film on a resin film made of thermoplastic resin; preparing a pair of grounding conductive pattern films each of grounding conductive pattern film formed by a wide grounding conductive pattern made of metallic film on a resin film made of thermoplastic resin; preparing a spacer film including a resin film made of thermoplastic resin without any conductive pattern disposed on a part of the surface of the resin film of the spacer film, the part corresponding to the grounding conductive pattern; preparing at least one surface conductive film by forming a surface conductive pattern made of metallic film on a resin film made of a thermoplastic resin; laminating the strip-shaped conductive pattern film, the spacer film and the grounding conductive pattern films in such a manner that: the pair of grounding conductive pattern films is arranged so that one grounding conductive pattern of one of the pair of grounding conductive pattern films faces the other grounding conductive pattern of the other one of the pair of grounding conductive films, the spacer film is laminated on the surface of the strip-shaped conductive pattern of the strip-shaped conductive pattern film, the laminates of the strip-shaped conductive pattern film and the spacer film are inserted between the pair of the grounding conductive pattern films so that the grounding conductive pattern films are disposed on both sides of the strip-shaped conductive pattern film through the resin films of the strip-shaped conductive pattern film and the spacer film, and the laminates of the strip-shaped conductive pattern film, the spacer film, and the grounding conductive pattern films are laminated to the surface conductive film where the surface conductive pattern faces outwardly; bonding each resin film together by heating and pressurizing the laminates of the surface conductive film, the strip-shaped conductive pattern film, the spacer film and the grounding conductive pattern films, wherein each grounding conductive pattern and strip-shaped conductive pattern provide a high-frequency conductive pattern for providing a high frequency circuit, and wherein each of the grounding conductive patterns and strip-shaped conductive pattern has a surface roughness, which is smaller than a surface roughness of the surface conductive pattern on a resin film side, disposed on an outer surface of the multi-layer printed circuit board.