Surface graft copolymerization of poly(tetrafluoroethylene) films with N-containing vinyl monomers for the electroless plating of copper

Abstract

Argon plasma-pretreated poly(tetrafluoroethylene) (PTFE) films were subjected to UV-induced surface graft copolymerization, under atmospheric conditions, with several N-containing vinyl monomers, including 4-vinylpyridine (4VP), 2-vinylpyridine (2VP), 1-vinylimidazole (VIDz), 1-vinylpyridinone (VPD), and acrylamide (AAm). Electroless plating of copper could be carried out effectively on the 4VP or 2VP graft-copolymerized PTFE surface after PdCl2 activation and in the absence of SnCl2 sensitization. The surface compositions of the modified PTFE films were studied by X-ray photoelectron spectroscopy (XPS). The catalytic processes for the electroless plating of copper in the presence and absence of sensitization by SnCl2 were compared. The adhesion strength of the electrolessly deposited copper on the graft-modified PTFE surface was affected by the type of the monomers used for graft copolymerization, the graft concentration, and the activation time of the PTFE surface in PdCl2 solution. The T-peel adhesion strength between the electrolessly deposited copper and the graft-modified PTFE film was further improved in the absence of the SnCl2 sensitization step and could reach as high as 7 N/cm. However, the electroless deposition of copper could not be carried out on the pristine or Ar plasma-treated PTFE surface in the absence of SnCl2 sensitization.