Wire Pull

Wire Pull Test:

Wire pull test is a test for wire bond strength and quality at the first bond. It consists of applying an upward force under the wire to be test, and effectively pulling the wire away from the die. Wire pull tester is required in performing the test, which consists of two parts:
1) A pull hook which is used for applying the upward pulling force on the wire
2) An instrument for measuring the force at which the wire or bond fails. The force is recorded in gram-force.

The procedure consists of applying the pull hook under a wire at the first bond and it’s positioned at the highest point along the loop of the wire, and pulling the wire away from the die through the vertical pull force perpendicular to the die surface. Besides the bond strength, I had to record the bond failure mode as well. The failure mode refers to one of the following:
1) Ball bond lifting
2) Break at neck
3) Break at stitch or heel break
4) Center wire break
5) Pad lifting

wire pull tool's position

ball lift

pad lift