Flexible base materials, their preparation and their use for printed circuits

Claim 1

A flexible, printed circuit with excellent adhesion of the printed circuit tracks, which is obtained by coating one side of a metal foil without any interlayer with a polymer consisting of a polyamide/polyimide block copolymer with recurring structural elements of the formula I [(A)--(E)] (I) in which n is a integer from 1 to 500, A is a polyamide block with a basic structural unit of the formula II or III ##STR13## and E is a polyimide block with a basic structural unit of the formula IV or V ##STR14## or consists of a polyamide/polyimide copolymer which is obtained by reacting a polyamide acid of the formula IVa or Va ##STR15## with a dicarboxylic acid dichloride of the formula XI ##STR16## and a diamine of the formula XII H.sub.2 N--R.sub.2 --NH.sub.2 (XII) and subsequently cyclising the polyamide/polyamide acid copolymer thus obtained, in which formulae a and b independently of one another are integers from 2 to 100, R 2 and R 4 independently of one another are a monocyclic aromatic radical which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups each having 1-4 C atoms, an unfused bicyclic aromatic radical which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups each having 1-4 C atoms and in which the aromatic nuclei are linked together via --O--, --CH 2 --or --SO 2 --, or a heterocyclic radical, alkylene having 2-12 C atoms or a dicyclohexylmethane radical, R 1 is an aromatic or heterocyclic radical or alkylene having 2 to 8 C atoms, the carbonyl groups being bonded to different carbon atoms, and R 3 is a 5-membered or 6-membered cycloalkyl radical, a benzene ring or an unfused bicyclic aromatic radical in which the aromatic nuclei are linked together via the bridge member --O--, --CO-- or --CONH-- and the carbonyl groups are bonded to different ring C atoms which are adjacent in pairs, heating the coated metal foil in the temperature range from 50° to 300° C. till a track-free coating is obtained, exposing the opposite side of the coated metal foil, which side is provided with a photolacquer, through a photo mask, and developing the exposed metal foil.