| 摘要 |
PURPOSE:To smoothen the back surface of an inner lead without chemical polishing and to increase the strength of the inner lead by bonding a copper foil on an insulating substrate, then electrolytically plating copper to increase the thickness of a copper layer of a device hole unit and then forming the overhanging inner lead. CONSTITUTION:A copper plating film 6 is formed by electrolytic plating on a copper foil 5 which is bonded onto an insulating substrate 3, and is formed by etching method. The copper is increased in thickness by the electrolytic plating in this manner, thereby smoothening the back surface of the overhanging inner lead 1'. Thus, chemical polishing can be omitted, and since the thickness of the inner lead 1' is increased larger than a circuit pattern 2' which is continued to the lead, thereby increasing the strength. |
