Synthesis and positive-imaging photosensitivity of soluble polyimides having pendant carboxyl groups

Polyimides having pendant; carboxyl groups were prepared by a direct one-po t polycondensation of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride ( 6FDA) with 3,5-diaminobenzoic acid (DABz) and bis[4-(3-aminophenoxy)phenyl] sulfone (m-BAPS) in the presence of a gamma -valerolactone/pyridine catalys t system using N-methyl-2-pyrrolidone (NMP)/toluene mixture asa solvent at 180 degreesC. The obtained polyimides were soluble in dipolar aprotic solve nts such as dimethylformamide, dimethyl sulfoxide, and NMP as well as in te trahydrofuran and aqueous basic solution. The solubility of the polyimides was dependent on the diamine composition. Photosensitve polyimide (PSPI) sy stems composed of the polyimides and diazonaphthoquinone compound as a phot osensitive material gave positive-tone behavior by UV irradiation, followed by development with aqueous tetramethylammonium hydroxide (TMAH) solution. The scanning electron microscopic photograph of the resulting image showed 10-mum line/space resolution with about 15 mum of film thickness. The PSPI s baked at 350 degreesC for a short time had excellent thermal resistance c omparable to the original polyimides. (C) 2001 John Wiley & Sons, Inc.