Electroless plating of copper on poly(tetrafluoroethylene) films modified by surface graft copolymerization and quaternization

Abstract

Argon plasma-pretreated poly(tetrafluoroethylene) (PTFE) films were subjected to UV-induced surface graft copolymerization with a tertiary amine monomer, N,N′-(dimethylamino)ethyl methacrylate (DMAEMA). The DMAEMA graft-copolymerized PTFE (DMAEMA-g-PTFE) surface was further reacted with 3-bromopropylamine hydrobromide (3-BPAH) to introduce the NH2 and the quaternary amine groups on the DMAEMA-g-PTFE film(the Q-DMAEMA-g-PTFE film). Both types of the PTFE surfaces could be activated by direct immersion in PdCl2 solution, in the absence of prior sensitization by SnCl2 (the Sn-free activation process). Electroless plating of copper could be carried out effectively on the Pd-activated DMAEMA-g-PTFE and Q-DMAEMA-g-PTFE surfaces. A much shorter induction time for the electroless plating of copper was found for the Q-DMAEMA-g-PTFE surface than for the DMAEMA-g-PTFE surface. The surface composition and the degree of quaternization of the surface-modified PTFE films were determined by X-ray photoelectron spectroscopy. The T-peel adhesion strength of the electrolessly deposited copper on the Q-DMAEMA-g-PTFE surface was improved to about 8 N/cm, in comparison to only about 4 N/cm for the DMAEMA-g-PTFE surface or about 0.6 N/cm for the PTFE surface with Ar plasma treatment alone. © 2001 The Electrochemical Society. All rights reserved.