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

A 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 (in-BAPS) in the presence of a gamma-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/cm(2) 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. (c) 2005 Wiley Periodicals, Inc.