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Method for Improving Adhesion of Copper on Advanced Solder Mask for Printed Circuit Boards

IP.com Disclosure Number: IPCOM000118034D
Original Publication Date: 1996-Aug-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Bauer, F: AUTHOR [+4]

Abstract

Disclosed is an improved process sequence to achieve a better adhesion of copper on printed circuit assemblies. At present, the adhesion of copper on photoimageable dielectric films e.g., Advanced Solder Mask (ASM) during the fabrication of printed circuit boards is achieved by mechanical roughening and a subsequent chemical etching process.

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Method for Improving Adhesion of Copper on Advanced Solder Mask for
Printed Circuit Boards

      Disclosed is an improved process sequence to achieve a better
adhesion of copper on printed circuit assemblies.  At present, the
adhesion of copper on photoimageable dielectric films e.g., Advanced
Solder Mask (ASM) during the fabrication of printed circuit boards is
achieved by mechanical roughening and a subsequent chemical etching
process.

The adhesion thus achieved can be improved by the following process
sequence:
  o  Applying the ASM material on the substrate, e.g., an inner
      layer.  The ASM material is laminated onto the substrate
      by means of a vacuum laminator
  o  Removing the mylar foil and drying the ASM material by
      means of a short bake
  o  Exposing the ASM layer
  o  Applying a copper foil onto the ASM layer by means of a
      commercial resist laminator.  Thereby, the rough copper
      treatment layer is imprinted in the soft ASM material
  o  Baking after exposure
  o  Removing the copper foil in the yellow room either by
     -  pulling off the foil, or
     -  etching the foil

Now the desired roughening of the ASM layer is achieved
  o  Developing the ASM layer
  o  Baking the ASM layer
  o  Chemically cleaning the holes and copper-plating the ASM layer

The described process sequence shows several advantages:
  o  Simple and quick process
  o  Process can be performed on availab...