Thermal and electroless deposition of copper on poly(tetrafluoroet hylene-co-hexafluoropropylene) films modified by surface graft copolymerization

Abstract

Surface modification of Ar plasma-pretreated poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) film via UV-induced graft copolymerization, under atmospheric conditions, with 4-vinylpyridine (4VP), 2-vinylpyridine (2VP) and 1-vinylimidazole (VIDz) was carried out to improve the adhesion with the thermally evaporated and the electrolessly deposited copper. The surface composition and structure of the graft-copolymerized FEP films were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM), respectively. The electroless plating of copper on the graft-copolymerized FEP film could be carried out in the absence of sensitization by SnCl2 (the Sn-free activation process). The adhesion strength of the thermally evaporated and the electrolessly deposited copper on the FEP surfaces was affected by the type of monomers used for graft copolymerization and the surface graft concentration. The T-peel adhesion strengths of the electrolessly deposited copper on the 4VP, 2VP and VIDz graft-copolymerized FEP films with 90-s of Ar plasma pretreatment were about 9.8 N/cm, 7.3 N/cm and 4.9 N/cm, respectively. The T-peel adhesion strengths of the thermal evaporated copper on the corresponding FEP surfaces were generally lower, possibly due to the reduced spatial interactions between the evaporated metal and the graft chains.