John A Kurtz, Donald E Cousens: Bonding wire ball forming method and apparatus. Fairchild Camera & Instrument, Kenneth Olsen, Michael J Pollock, Theodore Scott Park, June 28, 1983: US04390771 (33 worldwide citation)

Method and apparatus for forming a ball at the end of bonding wire or lead wire in a capillary wire holding and bonding tool is described suitable for ball bonding of copper and aluminum lead wire to integrated circuit chips. A ball is formed by substantially enclosing the end of the bonding wire in ...