Flexible base material for prodn. of electrical circuits etc. - by coating copper foil with filled polyamide-acid or polyimide base-coat, with similar unfilled top-coat, and stoving combination

摘要

Process for coating Cu foil to produce a flexible base material (I) comprises (1) applying and drying a primer layer contg. (A) 5-35 ( 10-25 ) wt.% polyamido carboxylic acid(s) (II) or polyimide(s) which are soluble in organic solvents, (B) 1-75 (5-30) wt.% w.r.t. A) filler(s), (C) organic solvent(s) and (D) opt. other additives, etc., (2) applying and drying a topcoat contg. the same components except the fillers, and stoving the two coats together. (I) is claimed as such. Pref. base and top-coats have dry film thickness 4-90 and 2-70 microns respectively; filler has mean particle size 0.5-35 (1-10) microns. USE/ADVANTAGE - (I) is useful for prodn. of electrical circuits and components (claimed). Provides a cost-effective process for the prodn. of a flexible base material with good thermal-and good dimensional-stability and good polyimide-Cu adhesion.