Electroless plating of copper on poly(tetrafluoroethylene) films modified by NH3 plasma and surface graft copolymerization with aniline

Electroless plating of copper on poly(tetrafluoroethylene) (PTFE) films modified by NH3 plasma treatment and surface graft copolymerization with aniline had been carried out. For the electroless plating of copper, the polyaniline (PANI)-grafted PTFE (PANI-g-PTFE) surface, with the PANI in its fully reduced leucoemeraldine form, was activated directly in the Pd(NO3)(2) acid solution in the absence of prior sensitization by SnCl2. The compositions and chemical states of the PTFE surfaces during each stage of the surface modification, surface activation, and electroless deposition processes were studied by x-ray photoelectron spectroscopy (XPS). The adhesion strength of the electroless deposited copper on the PANI-g-PTFE surface exhibited a strong dependence on the graft concentration of PANI. A T-peel adhesion strength of about 5 N/cm was achieved for the electrolessly deposited Cu on the PANI-g-PTFE surface (the Cu/PANI-g-PTFE assembly). The high adhesion strength of the Cu/PANI-g-PTFE assembly was attributed to the synergistic effects of strong interactions between the grafted aniline polymer and the metal (including Pd) atoms, the spatial distribution of the PANI chains in the metal matrix, and the fact that the polyaniline chains were covalently tethered on the PTFE surface. XPS results also revealed that the Cu/PANI-g-PTFE assemblies delaminated by cohesive failure inside the PTFE film. (C) 2001 American Vacuum Society.