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Enhanced Conditioning of a Substrate for Electroless Metal Deposition

IP.com Disclosure Number: IPCOM000120995D
Original Publication Date: 1991-Jul-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 79K

Publishing Venue

IBM

Related People

Egitto, FD: AUTHOR [+5]

Abstract

Disclosed is deposition of electroless copper onto insulators commonly employing a "conditioner" step to increase the pick-up of "seeder" particles (e.g., colloidal Pd/Sn) by the surface. An aqueous solution of Reten*, a polyacrylamide, is an example of a conditioner utilized in the copper plating of epoxy/fiberglass composites. However, in the case of composite circuit boards incorporating fluoropolymer layers to achieve lower dielectric constants, the Reten based process does not provide good copper coverage in high aspect ratio through-holes.

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Enhanced Conditioning of a Substrate for Electroless Metal Deposition

      Disclosed is deposition of electroless copper onto
insulators commonly employing a "conditioner" step to increase the
pick-up of "seeder" particles (e.g., colloidal Pd/Sn) by the surface.
An aqueous solution of Reten*, a polyacrylamide, is an example of a
conditioner utilized in the copper plating of epoxy/fiberglass
composites.  However, in the case of composite circuit boards
incorporating fluoropolymer layers to achieve lower dielectric
constants, the Reten based process does not provide good copper
coverage in high aspect ratio through-holes.  The present invention
describes the use of an improved conditioner system which, when used
in combination with a helium plasma process to improve the
wettability of the Teflon** layers, dramatically improves the
coverage of additive copper plating in high aspect (15:1) ratio
through-holes.  The improved conditioner is a solution of
polyvinylpyridine (PVP, Fig. 1A) in a non-aqueous solvent such as
n-methylpyrrolidone.  PVP is an excellent film former with the
advantage of low water solubility so that it is not removed in
subsequent aqueous processes.  The pyridine groups in PVP become
protonated in typical acidic seeder solutions (Fig. 1B), thus
enabling PVP to electrostatically bind negatively charged seeder
particles resulting in enhanced seeder coverage.  PVP is also an
effective conditioner for plating other materials, such as
polyimides, wher...