Patent ID: 6930044

Claim:
A method for fabricating a packaging substrate, comprising: providing a carrier plate having thereon at least one thin copper base layer; forming a first patterned photoresist layer on said thin copper base layer, said first patterned photoresist layer has a recessed trench area defining a copper circuit pattern; electroplating copper in said recessed trench area to form said copper circuit pattern including a to-be-Au-plating area that has a larger surface area as the terminal of said copper circuit pattern; stripping said first patterned photoresist layer; forming a second patterned photoresist layer exposing said to-be-Au-plating area of said copper circuit pattern; using said second patterned photoresist layer as an etching hard mask, etching away said thin copper base layer exposed by said second patterned photoresist layer and said to-be-Au-plating area; forming a third patterned photoresist layer on said second patterned photoresist layer to mend a recess under said second patterned photoresist layer; using said third patterned photoresist layer as an electroplating mask, electroplating a metal layer onto said copper circuit pattern in said to-be-Au-plating area; stripping said second and third patterned photoresist layers; and etching away remaining said thin copper base layer being exposed after stripping said second and third patterned photoresist layers.