ABSTRACT
Methods for enhancing the adhesion of both evaporated Cu and Cu foil to PTFE films are reported. Surface modification of argon plasma-pretreated poly(tetrafluoroethylene) (PTFE) film via UV-induced graft polymerization with glycidyl methacrylate (GMA) was first carried out. The so-prepared GMA-g-PTFE surface readily underwent reactive adsorption of an aminosilane coupling agent, γ-aminopropyltriethoxysilane (SCA1), in ethanol to give rise to the SCA1-GMA-g-PTFE surface. The SCA1-GMA-g-PTFE film exhibited T-peel adhesion strength in excess of 12 N/cm with evaporated copper. For enhanced adhesion of Cu foil to PTFE films, the copper foil was first pretreated with a silane coupling agent, such as (3-mercaptopropyl)trimethoxysilane (SCA2) or N1-P-itrimethoxysilyOpropylldiethylenetriamine (SCA3), followed by a brief period of Ar plasma treatment (5 s) before being subjected to UV-induced graft polymerization with GMA to give rise to the GMA-g-SCA-Cu surface. For thermal graft polymerization-induced lamination of the surface-modified copper foil to the Ar plasma-pretreated PTFE film or to the GMA-g-PTFE film, T-peel adhesion strength close to 10 N/cm was achieved in the presence of GMA and hexaethylenediamine (HEDA), or in the presence of an epoxy resin adhesive and GMA monomer. In all cases, the chemical compositions of the surface-modified PTFE films and copper foils, as well as the delaminated PTFE and copper surfaces from the corresponding assemblies, were characterized by X-ray photoelectron spectroscopy (XPS).
