Patent ID: 6337453
Filing Date: 2002-01-08
Classification: B23K,H01L

Abstract:
An apparatus for forming by means of an electric arc discharge a fusion ball on the end of a wire protruding from the bore of an ultrasonic bonding tool tip in preparation for using the wire to make a ball bond to a conductive pad of a workpiece, said apparatus including means for attenuating electromagnetic interference (EMI) emitted during said electric arc discharge and comprising:a. a spark chamber comprising an enclosure including at least a first, lower electrically conductive, electrostatic shield plate effective in attenuating electromagnetic interference (EMI) waves produced by an electrical arc above said shield plate and incident upon a workpiece located in a plane below said spark chamber, said spark chamber having above a lower surface thereof a high voltage electrode connected by an electrical conductor to a source of high voltage energy, b. means for causing relative advancing movement between said wire end protruding from said bonding tool and said electrode to thereby position said wire end close to said electrode and above said shield for forming a fusion ball, and relative receding movement to permit unimpeded motion of said tool towards a workpiece, and c. means for energizing said conductor of high voltage energy to thereby cause an electrical spark to form an arc discharge between said electrode and said wire end of sufficient energy to melt said wire end and form a fusion ball therein.