| 摘要 |
PROBLEM TO BE SOLVED: To perform constant diameter ball forming for wire bonding. SOLUTION: A spark discharge between a torch rod 5 and an end of a cut wire 6d, which protrudes from a capillary 6b, is achieved for forming a ball 6c. Since as a spark discharge gap changes due to cutting variations of the wire 6d, the spark discharge voltage fluctuates and thus it is difficult to form a ball constant. To solve this problem, a spark voltage is converted into an optimum voltage by a converter 9 for spark discharge voltage/ball forming effective voltage. A Joule generating rate (wattage value 1001) required to form a ball with a constant diameter is obtained by multiplying the ball-forming effective voltage by a discharge detect current. The spark discharge is made to end by a time determined by integrating the value 1001 for reaching a required total energy calculated by inputting a wire diameter and a ball diameter, with a comparator 12 and therefore, ensuring the production of a forming ball with a constant diameter. |
