PRINTED CIRCUIT BOARD OF SILICON STEEL BASE PLATE

PURPOSE:To prevent the progress of rust from a sagged surface caused by punching work to the inside of a wiring board, by constituting the board metal of silicon steel plate coated with a rust proof metal layer. CONSTITUTION:The surface of a silicon steel plate 1 is coated with a rust proof metal layer 2, which can be formed of oxidation resistant metal, e.g., aluminum, zinc, nickel, and chromium. The rust proof metal layer 2 is formed by electroplating, electroless plating, vapor-deposition, etc. After the silicon steel plate 1 is coated with the rust proof metal 2, resin, resin-impregnated glass cloth, etc., are arranged as a bonded insulating layer 3, and further a metal foil 4 is arranged, which are laminated and unified in a body. Then a circuit is formed, and punching work for digging holes, and the like are performed. Although the silicon steel plate 1 exfoliates from the bonded insulating layer 3, the end-surface of a sagged part 6 of the silicon steel plate 1 after exfoliation is coated with the rust-proof metal layer 2.