Diagnostic wire bond pull tester

A wire bond pull tester for automatic wire bonders of the type which includes a Z-drive motor for positioning a bonding tool during continuous bonding operations, comprising:

• a bonding head for positioning a bonding tool,
• a Z-axis encoder coupled to said bonding head for monitoring the Z-axis position of said bonding tool,
• a fine wire threaded through said bonding tool for making first and second bonds between a semiconductor device and a carrier,
• wire clamping means for clamping said fine wire after making a second bond on said carrier,
• continuity circuit means coupled to said fine wire through said wire clamping means,
• control means for applying increasing increments of pull force through said wire clamping means and for sensing the amount of elongation of said fine wire between said wire clamping means and said second bond, and
• means for determining the Z-axis position of said bonding tool when said continuity circuit means indicates a break has occurred in said fine wire above said second bond.

A method of performing pull test on a fine wire during a bonding operation by an automatic wire bonder, comprising the steps of:

• bonding a fine wire to a target on a device with a bonding tool,
• raising the bonding tool to a predetermined distance above the bond on the bonding target while paying out fine wire,
• clamping the fine wire with wire clamps fixed relative to the bonding tool,
• connecting a continuity circuit between said wire clamps and said bonding target,
• applying predetermined increments of pull force to said wire clamps,
• reading said increments of pull force applied to said fine wire in said bonding tool as a result of an increase in total pull force, and
• continuing to pull said fine wire through said wire clamps by increasing the total pull force in predetermined increments of pull force until said fine wire breaks or a predetermined pull force is reached.