A novel positive‐type photosensitive polyimide having excellent transparency based on soluble block copolyimide with hydroxyl group and diazonaphthoquintone

Abstract

AbstractA novel positive‐type photosensitive polyimide having excellent transparency based on soluble block copolyimide (Bco‐PI) with hydroxyl group and diazonaphthoquinone (DNQ) as a photoreactive compound was developed. The base Bco‐PI A was prepared by a direct one‐pot polycondensation of cyclohexanetetracarboxylic dianhydride (H‐PMDA), 2,2‐bis(3‐amino‐4‐hydroxyphenylhexafluoropropane) (Bis‐AP‐AF), and bis(4‐(3‐aminophenoxy)phenyl)sulfone (m‐BAPS) in the presence of a γ‐valerolactone and pyridine catalyst system by using dipolar aprotic solvent such as N‐methyl‐2‐pyrrolidone (NMP).The wholly aromatic polyimides have strong absorptions in the visible regions, because of their change–transfer complex formation. On the other hand, alicyclic dianhydride, H‐PMDA, contributed to the resulting Bco‐PI film with colorlessness and transparency, which are the important factors for a photosensitive polyimide. Photosensitive Bco‐PI, containing 20 wt % 1,2‐naphthoqiunonediazide‐5‐sulfonic acid p‐cresol ester (PC5), showed a sensitivity of 250 mJ/cm2 and a contrast of 2.56 when it was exposed to UV light, followed by development with 5% tetramethylammonium hydroxide (TMAH) aqueous solution at room temperature. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1619–1624, 2005