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, polyamide-imide or polyimide, obtained by heating a polyamide, polyamide-amidoacid or polyimide-acid having 1 to 100 mol % of structural units of the formula I ##STR5## and of 0 to 99 mol % of structural units of the formula II ##STR6## in which the NH groups in formula I are, independently of one another, bonded to the o-, m- or p-position of the benzene nucleus and the individual symbols or radicals m, n, R and R 1 , independently of one another, are defined as follows: m and n are each 1 or 2, R is a carbocyclic-aromatic or heterocyclic-aromatic radical, in which the carboxamide groups and carboxyl groups are bonded to different carbon atoms and the carboxyl groups, if R is a cyclic radical and at least one of m and n is 2, are each in the ortho-position to a carboxamide group, and R 1 is a carbocyclic-aromatic or heterocyclic-aromatic radical, heating the coated metal foil in the temperature range from 50° to 350° 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.