Method for manufacturing printed wiring board and printed wiring board

Abstract

A method for manufacturing a printed wiring board includes forming a metal film on a surface of an insulative board, a plating resist on the metal film, and a plated-metal film on the metal film exposed from the plating resist, covering a portion of the plated-metal film with an etching resist, etching to reduce thickness of the plated-metal film exposed from the etching resist, removing the etching and plating resists, and forming a wiring having a pad for wire-bonding an electrode of an electronic component and a conductive circuit thinner than the pad by removing the metal film exposed after the plating resist is removed, a solder-resist layer on the surface of the board and wiring, an opening in the layer exposing the pad and a portion of the circuit contiguous to the pad, and a metal coating on the pad and portion of the circuit exposed through the opening.

1 . A method for manufacturing a printed wiring board, comprising:
 preparing an insulative board;   forming a metal film on a surface of the insulative board;   forming a plating resist on the metal film;   forming a plated-metal film on the metal film exposed from the plating resist;   covering a portion of the plated-metal film with an etching resist;   etching to reduce a thickness of the plated-metal film exposed from the etching resist;   removing the etching resist;   removing the plating resist;   forming a wiring having a pad configured to be wire-bonded with an electrode of an electronic component and a conductive circuit which is thinner than the pad by removing the metal film exposed after the plating resist is removed;   forming a solder-resist layer on the surface of the insulative board and the wiring;   forming an opening in the solder-resist layer exposing the pad and a portion of the conductive circuit contiguous to the pad; and   forming a metal coating on the pad and the portion of the conductive circuit which are exposed through the opening.   
     
     
         2 . The method for manufacturing a printed wiring board according to  claim 1 , wherein the pad is formed of the metal film and the plated-metal film on the metal film. 
     
     
         3 . The method for manufacturing a printed wiring board according to  claim 2 , wherein the plated-metal film that forms the pad is a portion of the plated-metal film exposed by removing the etching resist. 
     
     
         4 . The method for manufacturing a printed wiring board according to  claim 2 , wherein the conductive circuit is formed of the metal film and the plated-metal film on the metal film, and a thickness of a portion of the plated-metal film that forms the conductive circuit is less than a thickness of a portion of the plated-metal film that forms the pad. 
     
     
         5 . The method for manufacturing a printed wiring board according to  claim 1 , wherein the conductive circuit is formed of a portion of the metal film. 
     
     
         6 . The method for manufacturing a printed wiring board according to  claim 4 , wherein the portion of the plated-metal film that forms the conductive circuit is made thinner by reducing the thickness of the portion of the plated-metal film that forms the conductive circuit. 
     
     
         7 . The method for manufacturing a printed wiring board according to  claim 1 , wherein the pad has a thickness which is 2-10 μm greater than a thickness of the conductive circuit. 
     
     
         8 . The method for manufacturing a printed wiring board according to  claim 1 , wherein the pad has width which is substantially the same as a width of the conductive circuit. 
     
     
         9 . The method for manufacturing a printed wiring board according to  claim 1 , wherein the metal coating comprises at least one metal selected from the group consisting of Au, Ni, Pd, Pt, Pb, Ag, Sn and Zn. 
     
     
         10 . A method for manufacturing a printed wiring board, comprising:
 preparing an insulative board;   forming a metal film on a surface of the insulative board;   covering a portion of the metal film with a first plating resist;   forming a first plated-metal film on the metal film exposed from the first plating resist;   covering a portion of the first plated-metal film with a second plating resist;   forming a second plated-metal film on the first plated-metal film exposed from the second plating resist;   removing the first and second plating resists;   forming a wiring having a pad configured to be wire-bonded with an electrode of an electronic component and a conductive circuit which is thinner than the pad by removing the metal film exposed from the first and second plated-metal films;   forming a solder-resist layer on the surface of the insulative board and the wiring;   forming an opening in the solder-resist layer exposing the pad and the portion of the conductive circuit contiguous to the pad; and   forming a metal coating on the pad.   
     
     
         11 . The method for manufacturing a printed wiring board according to  claim 10 , wherein the pad has a thickness which is 2-10 μm greater than a thickness of the conductive circuit. 
     
     
         12 . The method for manufacturing a printed wiring board according to  claim 10 , wherein the pad has a width which is substantially the same as a width of the conductive circuit. 
     
     
         13 . The method for manufacturing a printed wiring board according to  claim 10 , wherein the metal coating formed on the pad and the portion of the conductive circuit which are exposed through the opening of the solder-resist layer. 
     
     
         14 . The method for manufacturing a printed wiring board according to  claim 10 , wherein the metal coating comprises at least one metal selected from he group consisting of Au, Ni, Pd, Pt, Pb, Ag, Sn and Zn.