Amidoximation of the acrylonitrile polymer grafted on poly(Tetrafluoroethylene-co-hexafluoropropylene) films and its relevance to the electroless plating of copper

Abstract

Argon plasma-pretreated poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) films were subjected to UV-induced surface graft copolymerization with acrylonitrile (AN). The AN graft-copolymerized FEP (AN-g-FEP) surface was further reacted with hydroxylamine to introduce amidoxime groups on the surface (the amidoximated AN-g-FEP surface). Electroless plating of copper could be carried out effectively on the AN-g-FEP and amidoximated AN-g-FEP surfaces after sensitization in SnCl2 solution and activation in PdCl2 solution. The plasma pretreatment time of the FEP substrate and the UV graft copolymerization time affected the graft concentration of the AN polymer on the FEP surface. The surface compositions and the degree of amidoximation (DA) of the surface-modified FEP films were determined by X-ray photoelectron spectroscopy (XPS). The amidoximated FEP surface formed a complex with palladium ions and exhibited a strong ability to extract copper ions from the plating solution. The interaction of the AN-g-FEP and its amidoximated surfaces with evaporated copper atoms was investigated in situ by XPS. The T-peel adhesion strength of the electrolessly deposited copper with the amidoximated AN-g-FEP surface was enhanced to about 12 N/cm, from about 5 N/cm with the AN-g-FEP surface. The adhesion failure of the electrolessly deposited copper with the amidoximated AN-g-FEP film occurred cohesively inside the FEP substrate.