PURPOSE: To keep smoothness of a surface by preventing a plating metal from being transferred and attached to a surface of a bonding tool which comes into contact with an inner lead and by preventing the surface from being contaminated or damaged.

CONSTITUTION: An inner lead 3 is provided with a metal plating layer 4 such as Au, Sn only to a lower side thereof, and plating is not applied to an upper side thereof. The inner lead 3 thus processed is pressed to an end of a bump 2 with a fixed pressure by a heated bonding tool 5. Here, a plating metal of a surface of the inner lead 3 and a bump metal which forms the bump 2 melt under a high temperature and a high pressure at an interface of the inner lead 3 and the bump 2, become integral in a state such as formation of an eutectic, and the inner lead 3 is connected to the bump 2. Thereby, a surface of the bonding tool at a side with comes into contact with the inner lead is not contaminated by a plating metal; smoothness can be maintained for a long time.