Method for making plastic packages

Abstract

The method for making plastic packages of the present invention includes: forming an electroless Cu plating film on a resin substrate after removing a Cu foil; disposing a first plating resist pattern thereupon, passing electricity through the electroless Cu plating film, and disposing an electrolytic Cu plating film where the pattern is absent; disposing a second plating resist pattern to form a circuit pattern, and disposing a Ni and Au plating film; removing the plating resist pattern and etching away the Ni and Au plating film and the electroless Cu plating film not covered by the electrolytic Cu plating film; and disposing a solder resist film with openings to expose an external terminal connection pad and a semiconductor element connection pad. This method provides superior bonding properties with a solder resist, reduces undercutting during etching, allows use of high-density circuits, provides high reliability, and improves yield.

What is claimed is:  
     
         1 . A method for making a plastic package comprising a resin substrate to which a Cu foil is bonded on at least one side and, on said at least one side of said resin substrate, there is disposed a circuit pattern, an external terminal connection pad, and a semiconductor element connection pad, the method comprising: 
 etching away said Cu foil formed on a side of said resin substrate and then forming an electroless Cu plating film on said side of said resin substrate on which said Cu foil was formed;    forming a first plating resist pattern on a surface of said electroless Cu plating film; passing electricity through said electroless Cu plating film to form an electrolytic Cu plating film on a surface of said electroless Cu plating film not covered by said first plating resist pattern;    forming a second plating resist pattern on a surface of said electrolytic Cu plating film to serve as said circuit pattern; passing electricity through said electroless Cu plating film; electrolytic plating, on a surface of said electrolytic Cu plating film not covered by said second plating resist pattern, said external terminal connection pad and said semiconductor element connection pad upon which an Ni and Au plating film is disposed;    removing said first and said second resist patterns; etching away said electroless Cu plating film not covered by said Ni and Au plating film or said electrolytic Cu plating film; and    forming a solder resist film covering said circuit pattern while exposing said external terminal connection pad and said semiconductor element connection pad.    
     
     
         2 . A method of making a plastic package as described in  claim 1  wherein said solder resist film is formed on a surface of said circuit pattern and said solder resist film extends over a periphery of said external terminal connection pad.  
     
     
         3 . A method of making a plastic package as described in  claim 1  wherein said solder resist film is formed on a surface of said circuit pattern and said solder resist film extends over the periphery of said external terminal connection pad and said semiconductor element connection pad.