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How to: Cold Bump Pull (CBP)

How to: Shear

How to: Tweezer Pull

How to: Wire Pull

Sample measurement tests

Force calculations

Wire length L

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.

Wire-pull-calculate-length

The general equation is as follows:

Wire-length-general-equation

 

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:

Wire-length-mid-span-equation

Position d1 from first bond angle θ

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.

Wire-pull-position-along-wire-at-specific-angle

Position d1 from second bond angle θ

Wire-pull-distance-from-second-bond

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.

Wire-pull-position-along-wire-at-specific-angle (1)

Angle at second bond Φ

The angle at the second bond Φ is derived from this expression.

Equation-angle-second-bond-wire-pull

Pull at equal angles

If you want to pull with equal angles (θ=Φ), the following formulas apply.

Wire-pull-force-schematic

 

wire-pull-equal-angles

wire-pull-equal-angles-distance-from-first-bond

The forces t, p and s then are as follows.

wire-pull-force-t2

wire-pull-force-s

wire-pull-force-p2

wire-pull-force-p1

wire-pull-force-t1

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