Characterization of Positive-type Photosensitive Polyimide Films Formed by Electrodeposition Coating

Abstract

Soluble polyimides having pendant carboxyl groups were prepared by one-pot 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 γ-valerolactone/pyridine catalyst system using N-methyl-2-pyrrolidone (NMP)/toluene mixture as a solvent, and used for the electrodeposition coating. Positive-type photosensitive polyimide compositions for electrodeposition coating consisted of the pendant carboxyl-containing polyimide, NMP and cyclohexanone as solvents, N-methylmorpholine as a neutralizing agent, deionized water and diazonaphthoquinone(DNQ) compound(PC-5®) as a photosensitive material. The electrodeposition coating under a fixed voltage provided photosensitive polyimide films with high levels of appearance and smoothness on a copper foil. These photosensitive polyimide films formed by electrodeposition coating gave positive-tone behavior by UV irradiation and following development in an aqueous tetramethylammonium hydroxide(TMAH) or ethanolamine-containing solution. The scanning electron microscopic photographs of the resulting images showed fine and sharp line/space patterns.