A study of the interaction between thermally deposited aluminum films and fluoropolymer substrates

Aluminum was thermally deposited onto fluoropolymer substrates. The effects of interfacial reaction of aluminum with several fluoropolymeric substrates were investigated. These included PFA (poly[tetrafluoroethylene-co-perfluoro(alkoxy vinyl ether)]), FEP (poly(tetrafluoroethylene-co-hexa-fluoropropylene), and hydroxylated FEP (m-FEP). The hydroxyl modification was prepared by a previously developed radio frequency glow discharge (RFGD) method. X-ray photoelectron spectroscopy (XPS) studies of thin (—30 A) A1 deposited samples showed the formation of new fluorine-containing species, due to fluorine diffusion into the A1 overlayers. Auger and XPS depth profiles of samples with thick (—200 A) A1 overlayers also suggested the diffusion of fluorine and the formation of A1 fluorides at the interface. The RFGD modification process prior to the A1 deposition was performed to investigate potential adhesion of A1 to the substrates. This is envisioned as a reaction between A1 and RFGD introduced oxygen. The resulting Al/oxide interface limits the diffusion of fluorine.