Adhesion improvement of polytetrafluoroethylene/metal interface by graft copolymerization

Abstract

Copper-poly(tetrafluoroethylene) (PTFE) and gold-PTFE laminates were prepared by surface graft copolymerization of glycidyl methacrylate (GMA) on argon plasma-pretreated PTFE films at an elevated temperature with simultaneous lamination to copper foils or gold substrates. The plasma pretreatment introduces peroxides, which are thermally degraded into radicals to initiate the graft copolymerization of GMA on the PTFE surface. Before lamination, the gold surface was pretreated with alkanethiols to form self-assembled monolayers and then subjected to an Ar plasma treatment. The modified surfaces and interfaces were characterized by x-ray photoelectron spectroscopy and the adhesion strength was assessed by the T-peel test method. By this technique, the Cu-PTFE or Au-PTFE laminates exhibit significantly improved adhesion strengths and the joints are delaminated by cohesive failure inside the bulk of the PTFE film.