| 摘要 |
PURPOSE:To provide a ball forming method wherein a ball of high sphericity can be formed when a metal wire easy of oxidation like Pb-Sn is used, neck cut at the time of bump formation is reduced by preventing the heat at the time of ball formation from travelling in the length direction of a wire, and a low loop can be realized at the time of bonding. CONSTITUTION:A nearly semi-spherical recess W7 is formed at a tip leading-out port W6 of a wire insertion path W5 of a capillary W4. The tip of a metal wire (a) protruding from the recess W7 is heated in a reaction gas atmosphere, and melted in the recess W7 to formed a ball a2. The upper side semi-circular part of the ball a2 in the molten state is made to abut against the inner surface of the recess W7, and surface tension is applied to the lower side semi-spherical part as the result of abutting. Thereby an excellent ball in a true spherical type can be formed. The heat at the time of ball formation is absorbed by the capillary W4 before the heat travels in the longitudinal direction of the wire (a), so that the coarse region a3 of structure can be shortened. |
