| 摘要 |
PURPOSE:To replace gold with other metal such as copper while insuring weldability and neck strength of a ball by a method wherein an alternating voltage which gives larger energy when a metal wire is positive than when the wire is negative is applied between the metal wire and a discharge electrode. CONSTITUTION:An alternating voltage is applied between a metal wire 1 and a discharge electrode 2. If the value V1 of the voltage applied when the metal wire 1 is positive is larger than the value V2 of the voltage applied when the metal wire 1 is negative, an arc 3 is formed between the tip of the metal wire 1 and the discharge electrode 2 and concentrated heat is given to the tip of the wire 1. On the other hand, when the wire is negative, the arc 3 is formed extending to the top part of the metal wire 1 and the heat is given to the wire through the surface skin of the wire surface. With this process, the heat supply phenomenon is repeated so that the tip of the wire 1 is turned into a ball 28 the main part of which has perfect melting hysteresis and little unmelted part is left at the neck part 28a. |
