| 摘要 |
PURPOSE:To assure the bonding property of a ball and the neck strength by a method wherein a metallic wire as minus and a discharge electrode as plus are impressed with high voltage in inert gas atmosphere, setting up the discharge current at that time to be low-level current in the former time and high-level current in the latter time. CONSTITUTION:A metallic wire 1 as minus and a discharge electrode 2 as plus are impressed with high voltage in inert gas atmosphere to start arcing 3, setting up the discharge current to be low level current 11. Resultantly, the arcing 3 reaches the upper part of wire 1 for surface cleaning only not to melt the wire at all. When the set up time t1 elapsed and the oxide film on the surface of wire 1 is removed to start arcing 3 between the end of wire 1 and the discharge electrode 2, the discharge current is set up to be high-level current 12. At this time, the end part 6 of wire 1 is concentratedly heated so that a melted part 28 keeping spherical form may be formed into a ball 28 most of which is completely melted when the set up time t2 elapsed leaving a bit of unmelted part on the neck part 28a. |
