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Seed Process for Low Dielectric Materials

IP.com Disclosure Number: IPCOM000119439D
Original Publication Date: 1991-Jan-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 1 page(s) / 49K

Publishing Venue

IBM

Related People

Park, J: AUTHOR [+4]

Abstract

One of the first steps involved in the metallization of printed circuit boards (PCB) is often the deposition of electroless copper. While the subsequent circuitization processes may vary, the electroless copper deposition is common to most and generally consists of the application of a seed layer (usually a noble metal catalyst) followed by immersion in an electroless copper bath. Most seed/electroless processes have been designed for applications with FR4 epoxy substrates.

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Seed Process for Low Dielectric Materials

      One of the first steps involved in the metallization of printed
circuit boards (PCB) is often the deposition of electroless copper.
While the subsequent circuitization processes may vary, the
electroless copper deposition is common to most and generally
consists of the application of a seed layer (usually a noble metal
catalyst) followed by immersion in an electroless copper bath.  Most
seed/electroless processes have been designed for applications with
FR4 epoxy substrates.

      The necessity of utilizing dielectric materials other than FR4
is often dictated by increased PCB performance requirements.
Fluoropolymers, such as PTFE or PFA and filled composites of these
materials, are now utilized as PCB materials due to their low
dielectric constants and desirable thermal expansion properties.
Metallization of these materials is difficult, generally producing
numerous voids and poorly adherent metal, attributable to poor
wetting of the polymer surface.

      Described herein is a seeding method which enables electroless
copper metallization of many perfluoronated substrates under ambient
process conditions, i.e., does not require rigorous oxygen exclusion.
A fluoropolymer substrate is immersed in a non-aqueous solvent (e.g.,
NMP, DMF, DMSO) containing a noble metal salt or complex (e.g.,
palladium acetylacetonate or palladium (II) chloride).  The metal
complex or salt is absorbed onto or absorbed into the dielec...