PURPOSE: To eliminate the warpage of the title substrate and to make possible the surface mounting of a component by a method wherein the film surface of a flexible film with a circuit formed on one surface thereof is superposed on a metallic plate or the film surface of a flexible film with a circuit formed on the other one surface thereof using a dielectric as an intermediate layer and both films are integrally formed.
CONSTITUTION: A resin of a flexible film 1 is a polyester, a polyethylene, a polypropylene and the like. As one capable of forming a circuit on one surface of the film 1, a flexible wiring board and the like on the market are exemplified. As the materials for a circuit conductor and a metal layer, gold, silver, copper, aluminium and nickel, which are small in electric resistance, are suitable and copper is desirable for the circuit conductor from the viewpoint of cost and solderability. As a dielectric 4 and a metallic plate 5 are laminated and molded using the film 1 with a circuit formed previously on one surface thereof, the mismatching of a local stress is never generated and the problem of a warpage is not caused. Moreover, as the film is integrally formed with the dielectric 4 after a circuit is formed on one surface of the film, the circuit can be formed without deteriorating the characteristics of the film even in case a dielectric, which is low in heat resistance and chemical resistance, is used.
YOKOTA MITSUO
KAMIYA MASAMI
Next Patent: SOLDERING PRETREATMENT OF CERAMIC SUBSTRATE