| 摘要 |
PURPOSE:To form a ball having a constant size all the time and to obtain excellent bonding, by controlling the amount of projection of a piece of wire from a capillary at a constant value, and fusing the entire part of the protruded wire. CONSTITUTION:In a ball forming process, a piece of gold wire 13 is protruded from the lower end of a capillary 15 by a specified length lambda in the wire cutting process in the previous cycle. Said length lambda is a length, which corresponds to a volume of a ball 16 having a spherical diameter phi just specified when the wire 13 is fused. At first, an electric torch 17 is moved to a position, which is separated from the lower end of the capillary 15 by an interval (d). Then a voltage is immediately applied across the wire 13 and the electric torch 17. Discharging occurs and the wire 13 is fused. Thus the ball 16 is formed. At this time, the amount of energy enough to fuse the entire part of the protruded length is applied. |
