PURPOSE: To see that the circuit, which is formed at a region requiring high dimension accuracy, almost holds design dimensions and maintains high accuracy by dividing the metallic foil face of an elastic insulator in the shape of metallic- foil-plated film into a high dimension accuracy area and other areas, and forming circuits in other areas at the first step, and forming a circuit at the high dimension accuracy area at the second step.

CONSTITUTION: The face of a metallic foil 2 is divided into a region 6 requiring high dimension accuracy and other areas 7, and the area 6 is covered with an etching resist being formed on the whole face. In the other areas 7, an etching resist is formed in specified shape, and next etching processing is done so as to form circuit conductor patterns 4. Next, a cover coat film 8 is superposed on the circuit conductor pattern 4, and those are heated for 2 to 3 hours at 100-180°C and 10-40kg/cm2, and are force-bonded, whereby the entire plastic insulating film 1 shrinks thermally. A circuit is formed in the region 6 requiring high dimension accuracy, and etching processing is done so as to form a circuit conductor pattern 4'.