US 4,925,083 AGranted

Ball bonding method and apparatus for performing the method

AssigneeEmhart Deutschland GmbH

InventorsFarhad Farassat, Walter Birgel

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Abstract

A ball bonding method and apparatus is disclosed including gold wire bonding. The steps include positioning and lowering a bond capillary (10) with a bond wire (11) including a flame-scarfed bond wire ball (12) downwardly onto a first bonding pad (17). The bond wire ball (12) is welded by heating and applying a bonding pressure or ultrasonic, or both. The bond capillary (10) is raised and moved to form a loop (21), followed by the step of welding the bond wire (11) to a second bonding pad (16) using heating and applying pressure, ultrasonic or both. The bond capillary (10) is raised to a tail-length position (29) and the bond wire (11) is broken by a vertical pulling force created by closing a clamp (13) onto the wire and raising the clamp (13) engaging the bond wire (11). The end of the free bond wire is flame-scarfed to form a bond wire ball (12). For the flame-scarfing, the distance travelled by the wire clamp (13) until the bond wire (11) breaks is measured and the flame-scarfing lance (18) is accurately adjusted, or the free wire end after breakage is accurately adjusted.

Claims5

Dependent claims

A ball bonding method including the working steps of:

(a) positioning and lowering a bond capillary including a flame-scarfed bond wire ball from an upwardly retracted starting position onto a first bonding pad;
(b) welding the bond wire ball by heating and applying a defined bonding pressure and/or ultrasonic assistance;
(c) upward-retracting of the bond capillary;
(d) forming a loop in the bond wire;
(e) welding the bond wire in spaced relation to the bond wire ball to a second bonding pad by heating and applying a defined bonding pressure and/or ultrasonic assistance;
(f) upward-retracting of the bond capillary to a predetermined tail-length position, clamping and pulling on said bond wire to break the bond wire;
and subsequent upward-retracting of the bond capillary to said starting position;
and
(g) flame-scarfing the free bond wire end to form a fresh bond wire ball;
and
the improvement comprising the steps of
(h) applying a voltage between said second bonding pad and said clamp exerting said pulling force on the bond wire as soon as the clamp is in the wire clamping position;
(i) measuring the distance travelled by the clamp until breakage of the bond wire in accordance with interruption of the electrical connection between the second bonding pad and the clamp, and;
(j) locating a flame-scarfing device spaced from the free bond wire end in accordance with distance travelled by the clamp and thereby spacing the flame-scarfing device a predetermined distance from the free bond wire end.

11 more elements

Dependencies are inferred from the claim text.