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Selective Seeding for Metallization of Photosensitive Polyimide Structures

IP.com Disclosure Number: IPCOM000121932D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

O'Toole, TR: AUTHOR [+2]

Abstract

Disclosed is a process that allows a selective base-only activation of multilayer polyimide structures for electroless metallization.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 75% of the total text.

Selective Seeding for Metallization of Photosensitive Polyimide Structures

      Disclosed is a process that allows a selective base-only
activation of multilayer polyimide structures for electroless
metallization.

      One method by which a polyimide (PI) surface can be activated
for electroless metallization is by the redox seeding process [1]. It
takes advantage of the ability of the imide sites to take up
electrons, i.e., undergo electron transfer, in a reversible manner.
Following reduction, the PI is immersed in a solution containing a
palladium salt where electrons are transferred resulting in
deposition of the catalytic pd(0) particles.  The redox seeding
process is particularly advantageous for selective seeding of
multilayer polyimide structures [2].  Since different PIs have
different redox properties, one can choose and image a polyimide top
layer (typically, a photosensitive polyimide, PSPI) which is more
difficult to reduce than the base layer. With proper choice of
reducing agent, therefore, the base of the imaged features can be
selectively activated for electroless metallization.  However,
certain packaging structures may require that only one type of PSPI
material be used.

      For builds based on one type of PI, selective seeding is still
possible using PSPIs which are based on poly(amic acid) salts or
esters.  In this case, redox seeding is done immediately after
imaging of the top PSPI layer and BEFORE curing.  Only the CURED
bottom...