Patent ID: 8273234

Claim:
A method of manufacturing a printed circuit board, the printed circuit board comprising a copper clad laminate 31 including an insulated substrate 31 a and a piece of copper foil 31 b applied on one side of the insulated substrate 31 a , comprising the steps in order of: (a) adhering a dry film 32 including a photosensitizing agent on the copper foil 31 b , and then exposing and developing the dry film 32 , thereby forming a dry film opening 33 for forming a dot circuit; (b) forming a copper plating layer 34 by performing electroless or electrolytic plating, and then stripping the dry film 32 a other than the copper plating layer 34 , thereby forming a dot circuit 34 a , which is a first metal layer; (c) further adhering a dry film 35 including a photosensitizing agent on the dot circuit 34 a , and exposing and developing the dry film 35 , and etching the copper foil 31 b , thereby forming an external circuit 31 c having a larger width than the dot circuit 34 a ; and (d) removing the dry film 35 and forming a second metal layer 37 by performing electroless or electrolytic plating in order to improve conductivity of the dot circuit 34 a and external circuit 31 c.