Low-Temperature-Curable and Positive-Type Photosensitive Polyimide with High Mechanical Strength, High Resolution and Good Pot-Life Based on Chain Extendable Poly(Amic Acid), Thermal Degradable Crosslinker, Chain Extender, Thermal Base Generator and Photoacid Generator

Abstract

A positive-type photosensitive polyimide (PSPI) based on a chain extendable poly(amic acid) (PAA), a thermally degradable cross-linker 1,3,5-tris[(2-vinyloxy)ethoxy]benzene (TVEB), a photoacid generator (PAG) (5-propylsulfonyloxyimino-5H-thiophene-2-ylidene)-(2-methylphenyl)acetonitrile, a chain extender diphenyl isophthalate (DPI) and a thermal base generator (TBG) t-butyl 2,6-dimethylpiperidine-carboxylate has been developed. The PAA prepared from 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-oxydianiline was end-capped with di-tert-butyl dicarbonate, and undergoes a chain extending reaction during a curing stage to constitute a linear structure. This advancing PSPI exhibited high resolution of 3 μm, good mechanical properties, low residue content of cross-linker, low imidization temperature (250 o C) catalyzed by TBG, preventing corrosion of Cu circuits due to neutralization of photogenerated acids with bases from TBG and the extended pot-life by using the chain extender with high hydrolytic stability, inducing a wide-ranging applicability.