Abstract: Laser soldering in a tape automated bonding procedure is carried out on outer ends of a number of high density leads (72) printed on a film (78) of mylar and having inner ends connected to a circuit chip (70). The outer ends of the leads are soldered, without the use of flux, by application of heat and ultrasonic energy in a timed program while pressing an end (52) of the lead to be soldered against the substrate pad to which it is to be soldered. An elongated ultrasonically vibratable capillary (16) is employed to press the wire down against its pad (54) and to receive and guide an optical fiber (44) through which a beam of laser energy is fed coaxially through the capillary (16) to heat the wire end (52).

Abstract: A ball is formed at the tip of a wire by an arc. The arc is initiated and maintained across an air gap between the wire tip and an electrode by applying timed RF and DC voltages between them.