Patent ID: 8869391

Claim:
A method of producing a wired circuit board, comprising the steps of: preparing a metal supporting layer, forming an insulating layer on the metal supporting layer so as to form an opening, forming a conductive thin film on the insulating layer and on the metal supporting layer that is exposed from the opening of the insulating layer, heating the conductive thin film prior to formation of a plating resist for forming a conductive pattern and a metal connecting portion, forming the plating resist on an upper surface of the conductive thin film in a pattern reverse to that of the conductive pattern and the metal connecting portion to be formed, forming the conductive pattern on the conductive thin film that is formed on the insulating layer, and forming the metal connecting portion to be continuous to the conductive pattern on the conductive thin film that is formed on the metal supporting layer that is exposed from the opening of the insulating layer, wherein in the step of heating the conductive thin film, the conductive thin film itself is heated at 180 to 350° C. for 1 to 3 hours, thereby to improve an adhesion between the metal thin film and the metal supporting layer and prevent a peeling of the metal connecting portion from the metal supporting layer.