Abstract: A method and apparatus for forming a ball on a wire by spark discharge and for bonding the wire to a microcircuit is disclosed. The apparatus includes an electrode, a wire holder supporting a wire and forming a spark discharge gap between the tip of the wire and the electrode, first and second D.C. supply circuits, and an arrangement for bringing the wire ball into contact with a microcircuit and bonding the ball to the microcircuit. The first supply circuit provides a higher voltage and lower current than the second supply circuit and includes a capacitor of smaller value and charging, discharging resistors of higher value than corresponding capacitors and resistors in the second circuit. A control circuit initially connects the higher voltage across the wire and electrode to initiate an arc discharge and thereafter connects the lower voltage source across the gap form the ball.

Abstract: In arc butt welding the arc is moved between the faces of the parts to be joined by a magnetic field. In order to insure the arc travels over the whole of the faces to be welded the parts are moved generally parallel to the faces so that the overlapping area of the faces changes during the arc heating.