| 摘要 |
PROBLEM TO BE SOLVED: To provide copolyimide films which equally meet a high modulus, a low coefficient of thermal expansion, a low coefficient of hygroscopic expansion and a low water absorption and excel in alkali etching resistance when applied to flexible printed circuits provided with a metallic wiring in its surface or tape automated bonding tape(TAB tape) metallic wiring board substrate materials. SOLUTION: Copolyimide films are prepared from a random and/or block four-component copolyamic acid composed of 10-90 mol% 3,3',4,4'- benzophenonetetracarboxylic dianhydride and 10-90 mol% pyromellitic dianhydride on the basis of the dianhydrides, and 10-90 mol% phenylenediamine and 10-90 mol% bisaminophenoxyphenylpropane on the basis of the diamines.
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