Wire bond integrity test system
AssigneeTexas Instruments Incorporated
InventorsAllan I. Dacanay, Raymond M. Partosa, Enrique R. Ferrer
Life of this patent
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Abstract
An improved bond integrity test system is provided by eliminating the spring loaded wire spool cover which contributes to particulate matter, and by addition of a second contact diverter in the wire path. These improvements have been shown to decrease false lifted ball bond reports by 68%, and therefore to improve productivity and accuracy of the test system. Such changes are readily adapted to current bonders, as well as to new designs.
Claims11
1- An improved system for automated ball bond integrity testing including:
- a wire spool assembly having no contact with a cover or other member,
- an electrically isolated gold wire wound on said spool,
- two or more contact diverters located in the wire path,
- current monitoring device connected to the device under assembly and said wire, and
- a DC voltage source applied to said wire.
2- A system as in claim 1 wherein said diverters comprise stainless steel cylinders having a conductive coating.
3- A system as in claim 1 wherein said diverters protrude from the bonder surface, and are positioned apart about 2 to 2.5 times the combined radii of the diverters.
4- A system as in claim 1 wherein the second diverter is about 30 to 35% smaller in diameter than the first.
5- A system as in claim 1 wherein each of the diverters provide an area for gold wire contact.
6- A system as in claim 1 wherein the double diverter replaces a single diverter on existing equipment, and the wire spool cover is removed.
7- An improved method for automated in process ball bond integrity testing including the following steps:
- applying a DC voltage source to an isolated gold wire fed from a spool assembly wherein said assembly includes no cover,
- feeding said wire across the top of a first contact diverter, and across the bottom side of a second contact diverter,
- directing the wire through an insulating wire clamp assembly and capillary,
- forming a ball,
- bringing the ball into contact with a semiconductor device positioned on a grounded work station, applying current and force to form a bond, and
- monitoring the signature of the current flow.
8- A method as in claim 6 wherein abnormal current flow is reported as a lifted ball.
9- A method as in claim 6 wherein particulate contamination from the wire spool assembly is minimal.
10- A method as in claim 6 wherein the DC current is applied through a current resistor.
11- A method as in claim 6 wherein said double diverters provide two locations for contact to the wire.