To obtain a polyamic acid composition capable of stably giving polyimide film by a thermocuring system, by making the composition include a polyamic acid, a tertiary amine, and a poor solvent which hardly dissolve the polyamic acid.
This composition comprises (A) a polyamic acid obtainable by polymerization an aromatic tetracarboxylic acid dianhydride and an aromatic diamine in an organic polar solvent, (B) pref. 2-10 wt.% of a tertiary amine (pref. with a pKa of ≤5.3, e.g. pyridine), and (C) pref. 2-10 wt.% of a poor solvent which cannot dissolve the component A at ≥5 wt.% (pref. an aprotic solvent). Dehydrocyclization (imidation) of this composition by thermocuring process affords polyimide films with good peelability and excellent mountability such as ACF(anisotropic electroconductive film) pressure weldability.
NOJIRI HITOSHI
ITO TAKU
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