Surface graft copolymerization of poly(tetrafluoroethylene) film with simultaneous lamination to copper foil

A simple, one-step process of surface thermal graft copolymerization of arg on plasma-pretreated poly(tetrafluoroethylene) (PTFE) films with simultaneo us lamination of copper foils, or with similarly plasma-pretreated PTFE fil ms, was demonstrated. The simultaneous thermal grafting and lamination proc ess was carried out at 120 degrees C under atmospheric conditions. The mono mers used for the graft copolymerization were 1-vinyl imidazole (VIDz), 4-v inyl pyridine (4VP), and 2-vinyl pyridine (2VP). The adhesion strengths are reported as lap sheer adhesion strengths and T-peel adhesion strengths. Th e adhesion strength between the polymer and the metal was further enhanced by the presence of a crosslinking agent in the monomer. Adhesion strengths exceeding 7 N/cm were achieved for the Cu foil/PTFE laminates. X-ray photoe lectron spectroscopic (XPS) studies of the delaminated Cu foil/PTFE assembl y revealed that the joint failed by cohesive failure inside the PTFE film. The strong adhesion between PTFE and Cu arises from the charge-transfer int eraction between the nitrogen moiety of the grafted polymer and the Cu atom , as well as from the fact that the graft chains are covalently tethered on the PTFE film surface as a result of the graft copolymerization process.