Abstract: A method of preparing a copper-polyimide substrate comprising applying an electroless copper plating to the surface of a polyimide resin and, if required, further applying an electrolytic copper plating successively thereto, wherein heat treatment is applied to the substrate after the electroless copper-plating treatment within a temperature range from 120.degree. to 420.degree. C. The metal plating layer has an excellent adhesion capable of withstanding thermal shocks. The substrate can be used for producing electronic parts having high reliability with stable operationability.

Abstract: Disclosed is a method of preparing a copper-polyimide substrate comprising applying an electroless copper plating to the surface of a polyimide resin, wherein the surface of a polyimide resin is first etched so as to form a hydrophilic denatured layer on the surface of the said polyimide resin and, after a catalyst is imparted to the substrate, the substrate is copper-plated and thereafter heat-treated at a temperature of 120.degree. C. or higher thereby to modify the hydrophilic denatured layer to a heat-resistant copper-diffusion preventing layer.