Interfacial study of polyimide/copper system using silane-modified polyvinylimidazoles as adhesion promoters

Polyvinylimidazoles(PVIs) modified with vinyltrimethoxysilane (VTS) in different mole ratios were applied as adhesion promoters for polyimide (PI)/copper interface. The effects of the composition of VTS-modified PVI copolymers on lap shear strengths between PI and copper were investigated at different bonding temperatures. Fourier transform infrared spectroscopy was applied to examine the thermo-oxidative degradation of PI and oxidation of copper. In addition, scanning electron microscope and contact angle measurement analysis were performed to investigate the compatibility of VTS-modified PVIs with PI. An improvement in interfacial adhesion strength was obtained using the adhesion promoters. Especially at higher bonding temperatures, a significant increment in lap shear strength was seen when the mole ratio (VI:VTS) was 3:7, due to the high thermal stability of the silane unit. However, at lower bonding temperatures, lap shear strength does not increase as above, owing to the poor compatibility between the VTS-modified PVI with PI.