Adhesion of vapour phase deposited ultra-thin polyimide films on polycrystalline silver

Abstract

The vapour phase deposition of 4,4'-oxydianiline (ODA) and pyromellitic dianhydride (PMDA) on a polycrystalline silver substrate was studied using X-ray photoelectron spectroscopy. Adsorption of the pure components on the clean substrate at room temperature results in partial fragmentation of the adsorbate molecules. Bonding to the silver is believed to occur via the oxygens in the ODA and PMDA fragments. Room temperature codeposition of PMDA and ODA in a thin (∼ 36 Å) layer, followed by heating, led to polymerization and the formation of an ultra-thin (∼11 Å) and thermally stable (T < 450 ° C) polyimide film. Adhesion of this polymer involves bonding to the fragments of PMDA and ODA initially chemisorbed on the surface. These experiments demonstrate that sufficiently thin polymerized films can be prepared and applied to fundamental studies of adhesion