| 摘要 |
PROBLEM TO BE SOLVED: To reduce the costs of electroforming parts by forming non-plating patterns of an electrically insulative original plate blank and providing the blank with a thickly coated plating film for forming a conductor surface for the purpose of deposition of an electroforming plating film. SOLUTION: A photoresist 62 is applied on the surface of the original plate blank 61, such as a glass plate, following which the photoresist is exposed by using an exposure mask for diaphragm parts and is developed to form the resist patterns 63. The original plate blank 61 portion of the opening surface 64 of the resist patterns 63 are etched, by which etched parts 65 corresponding to the plating patterns are formed. The resist patterns 63 are removed and a conducting layer 66 is deposited on the surface of the original plate blank 61 by sputtering of Cr, Ni, etc. The plating of Cu, etc., is then applied thereon to form the thickly coated plating film 67 on the front surface of the original plate blank 61. The surface of the thickly coated plating film 67 is finished by polishing to the plane flush with the original plate blank 61 and the thickly coated plating film 67. As a result, an electroforming original plate 71 consisting of a conductive surface 70 for forming the first layer of the diaphragm and non-plating patterns is obtained.
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