If the geometry of the sample and the wire length are known the resultant angles and forces on the bonds during wire pull can be determined. If the wire length L is unknown, it can be calculated from the loop height.
The general equation is as follows:
If there is no height difference between the first and second bond and the pulltest is performed mid span, the equation can be simplified to:
If you want to pull with a specific angle θ at the first bond, calculate the test position along the wire according to the following formula.
You can use the same equation to calculate d1 for the second bond by making h2 negative. Φ then becomes θ and d1 is measured from the second bond.
The angle at the second bond Φ is derived from this expression.
If you want to pull with equal angles (θ=Φ), the following formulas apply.
The forces t, p and s then are as follows.