Surface modification of poly(tetrafluoroethylene) films by plasma polymerization of glycidyl methacrylate for adhesion enhancement with evaporated copper

Abstract

Surface modification of poly(tetrafluoroethylene) (PTFE) film by H2 plasma treatment, and by plasma polymerization and deposition of glycidyl methacrylate (GMA) in the absence and presence of H2 plasma pre-activation of the PTFE substrates, was carried out to enhance the adhesion of the polymer with evaporated copper. The H2 plasma treatment resulted in effective defluorination and hydrogenation of the PTFE surface, and enhanced the adhesion of evaporate Cu to the PTFE surface (the Cu/PTFE assembly) to various extents. For plasma polymerization carried out at a low RF power, a high epoxide concentration was preserved in the plasma-polymerized GMA (pp-GMA) layer on the PTFE surface (the pp-GMA-PTFE surface). However, high adhesion strength for the Cu/pp-GMA-PTFE assembly was obtained only in the presence of H2 plasma pre-activation of the PTFE substrates prior to the plasma polymerization and deposition of GMA. In the absence of H2 plasma pre-activation, the deposited pp-GMA layer on the PTFE surface could be readily removed by acetone extraction. The adhesion enhancement of the Cu/pp-GMA-PTFE assembly in the presence of H2 plasma pre-activation of the PTFE substrate was attributed to the covalent bonding of the pp-GMA layer with the PTFE surface, the preservation of the epoxide functional groups in the pp-GMA layer, and the strong interaction of evaporated Cu atoms with the epoxide and carboxyl groups of the GMA chains. © 2001 Elsevier Science Ltd.