Pd+2/poly(acrylic acid) thin films as catalysts for electroless copper deposition: Mechanism of catalyst formation

The mechanism involved in the initiation of electroless copper deposition onto dielectric substrates using Pd+2/ poly(acrylic acid) thin films is described. Dielectric substrates are catalyzed by dip-coating in aqueous poly(acrylic acid) to deposit a 50–300 nm thick film of the polymer on the surface; the coated substrate is then immersed in aqueous PdS04. It is shown that uptake of palladium in the poly(acrylic acid) film occurs by H+/Pd+2 ion exchange. The active catalyst is identified by x-ray photoelectron spectroscopy as zerovalent palladium, formed when the Pd+2-exchanged polymer film is immersed in an electroless copper deposition bath. © 1990, The Electrochemical Society, Inc. All rights reserved.