Pull testing procedure

F ff ѲѲ 2f sin Ѳ = F If sin Ѳ = 30° then f = F If the angle of the 1 st and 2 nd bonds is 30° then the force we measure equals the tension in the wire.

Distance between 1 st and 2 nd bond = 1,500um Loop height = 500um Other parameters ignored for now; they may stay constant This gives roughly a 30°loop

BJ820 loop measured by hand produces an angle of 36° 36°30° Ѳ h d BJ820 bond head parameters produce an angle of 33.7°

35.9°30° Ѳ h d Correction factor for angle calculated from the bond head parameters. Ѳ = 33.7° Sin Ѳ = f × 0.55 = F F = F / 1.10 e.g. If F=12.0 g, f = 12/1.10 = 10.9 g Correction factor for measured angle of wire under pull test. Ѳ = 36° Sin Ѳ = f × 0.59 = F f = F / 1.18 e.g. If F=12.0 g, f = 12/1.18 = 10.2 g 36°30° The force F which the tester measures is 10%-18% larger than the tension f at which the wire breaks. (Note the difference between the angles, measured and calculated).

Work in progress to create a Standard Pull Test Loop using bond head parameters (Has anyone else defined a loop yet?) Either understand the difference better or do a methodical study of all bond head parameters to generate a 30° pull angle

A pull test result from the Birmingham BJ820 Parameters used: Stop after deformation: 33% (1.3 standard) Ultrasonic: 24% Bondforce: 24cN Duration: 50ms (Actual time ~ 8ms) Ramp: 0ms

20 tests total g mean 0.76 g Standard Deviation 10.5 g minimum load 13.0 g maximum load Test result code 1: 12 Test result code 3: 3 Test result code 4: 5 If the minimum pull strength is 10.5 g then how important is the Standard Deviation? Strong heels produce a higher Standard Deviation

Comparison between the different BJ820s in the community; something like this? This is a study for different surfaces, but it could be done for different wire bonders. We may learn something!