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Electroless Deposition of NiP or CoP on a Copper Foil Functioning as an Adhesive Layer for Subsequent Polyimide Coating

IP.com Disclosure Number: IPCOM000114591D
Original Publication Date: 1995-Jan-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Boecker, J: AUTHOR [+2]

Abstract

This article decribes the electroless deposition of NiP or CoP on a copper foil. The phosphide layer serves as an adhesive layer for the subsequent polyimide coating.

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This is the abbreviated version, containing approximately 87% of the total text.

Electroless Deposition of NiP or CoP on a Copper Foil Functioning
as an Adhesive Layer for Subsequent Polyimide Coating

      This article decribes the electroless deposition of NiP or CoP
on a copper foil.  The phosphide layer serves as an adhesive layer
for the subsequent polyimide coating.

      The base material for flexible circuit boards or multi-layer
thin film structures consists of a dielectric (polyimide) which is
laminated or coated with a copper foil on one or two sides.  To
achieve good chemical adhesion between the copper and the polyimide
the foil is electrolessly coated with a thin layer of NiP or CoP on
the side facing the insulator.

      This cover layer is subjected to a chemical or electrolytical
secondary treatment, whereby a homogeneous surface is achieved which
causes a uniform adhesion, also resisting thermal stress.

      The copper foil is covered on one side with a thin (< 0.5 &mu
m) electroless NiP or CoP layer.  After a subsequent rinsing process
it is put into the secondary treatment bath, where a reproducible
surface oxidation takes place.  After rinsing and drying the foil can
be coated with the polyimide.

      Chemical oxidation is initiated by dipping into a solution
containing sodium borate or by electrolytical (anodic) treatment in
such a solution.

      Since the copper forms a homogeneous layer, smaller dimensions
are possible when etching the conductive paths because of thinner
copper layers and the f...