Polyimide surface chemistry

Abstract

Poly(promelliticdianhydride-oxydianiline) (PMDA-ODA) and poly(bisphenyldianhydride-para-phenyldiamine) (BPDA-PDA) polyimide film surfaces are initially modified with KOH aqueous solution. These modified surfaces are further treated with aqueous HCl solution. Modified surfaces are identified with X-ray photoelectron spectroscopy (XPS), external reflectance infrared (ER IR) spectroscopy, scanning electron spectroscopy, gravimetric analysis, contact angle and thickness measurements. The depth of modification, which is measured by a technique using ellipsometry and ER IR, is controlled by the reaction temperature and the reaction time. Surface topography and film thickness can be maintained under the optimized reaction conditions. Polyamic acid surfaces are further modified by the reaction with various chemical reagents such as isocyanates and silanes. Polyimide-polyimide adhesion, studied by spin-coating polyimide precursor onto surface-modified polyimide and subsequent curing, gives 85-125 g/mm peel strengths under the optimum conditions.