INVESTIGATION OF POLYIMIDESILOXANES FOR USE AS ADHESIVES BY ELECTRON-SPECTROSCOPY FOR CHEMICAL-ANALYSIS

Angle-dependent electron spectroscopy for chemical analysis (ESCA) was used to examine the air facing surface (20-100 Angstrom thick) compos ition of polyimidesiloxanes with different processing variations, and of varying polydimethylsiloxane (PDMS) content and block length (numbe r of PDMS repeat unit varies from 1 to 9). Polyimide was clearly detec ted (due to the nitrogen content) in the 20-100 Angstrom surface regio ns. This shows that a small amount of PDMS and short PDMS segment leng ths in polyimidesiloxanes give a surface region with both PDMS and pol yimide present. The surface composition, particularly that in the ca. 100 Angstrom region, was correlated to the peel strength of polyimides iloxane melt pressed to a metal substrate. Our results suggest that bo th PDMS and polyimide are essential components to rendering a needed p eel strength. PDMS, having a good diffusive ability, readily reaches t he substrate upon being pressed, achieving intimate contact, while imi de groups interact with the substrate, presumably through chemical bon ding; these two factors act synergistically to result in a high peel s trength. In addition, the interaction mechanism and the failure mechan ism involved in bonding polyimidesiloxane and metal substrate were als o elucidated based on the ESCA results.