...this is page 5; click here to go to page 4.
Vector pull is a variety on wire pull, where the hook does not move up at a 90° angle relative to the sample, but at a programmable angle. On a bond tester, this is achieved by simultaneously moving the X- and/or Y-axes with the Z-axis. This enables different loading conditions between the first and second bonds that can help to promote the failure mode of interest.
Alternatively, one can clamp the sample in a work holder which is inclined. See an example of this under SMD gull wing leads testing.
The best way to test the bond of an SMD gull wing lead is to cut the body from the leads and then test each lead with a tweezer pull sensor. This way, the bond is tested with no effects from the body and the other leads.
The downside of this approach is the preparation time involved. If you pull test without cutting the body off and use a hook there are 3 problems, namely:
Because the hook is closer to the package than the pad, a lot of the test load goes into the package rather than the bond of interest. However, a weak lead to pad bond will still give a lower result and failure mode analysis of the tested bond will show poor soldering.
A strong wire hook is required. XYZTEC can support you with extra strong hooks that will withstand relatively high forces.
To minimize the effect the body has supporting the bond it may be better to use a vector pull, using a special hook and a shear sensor. This also allows the hook to be made stronger but it might still be weaker than the lead, depending on the clearance under the lead for the hook. With a vector pull, a higher test load is applied to the bond pad than with the regular wire pull.
Another method is to incline the sample. Using this approach, one can still use a regular pull sensor in combination with a strong wire hook. This has the following limitations, though: