Patent ID: 8546511

Claim:
A polyamideimide resin for flexible printed circuit boards, which is obtained by the polymerization reaction of an acid component comprising at least a dianhydride and an aromatic dicarboxylic acid with a diisocyanate compound or diamine compound in an approximately equimolar amount with respect to the total molar amount of the acid component, wherein the molar amount of the dianhydride is 0.2 to 0.4 taking the total molar amount of the acid component as 1, and wherein the dianhydride is at least one dianhydride selected from the group consisting of the anhydride of diphenylsulfonetetracarboxylic acid, benzophenonetetracarboxylic acid, pyromellitic acid, napthalenetetracarboxylic acid, diphenyltetracarboxylic acid, bis(dicarboxyphenyl)propane, bis(dicarboxyphenyl)sulfone and bis(dicarboxyphenyl)ether, and the acid component further contains an aliphatic dicarboxylic acid, and wherein the aliphatic dicarboxylic acid is at least one aliphatic dicarboxylic acid selected from the group consisting of adipic acid, sebacic acid, maleic acid, fumaric acid, decanedioic acid, dodecanedioic acid, and dimer acid.