A New Technique for Testing Copper Stud Bumps

We describe a technique to evaluate stud bump pull strength where the bumps are made from

copper. The method uses a DAGE 4000 bond tester equipped with a CBP100 load cell and

customized jaws. Results show that the bond strength can be assessed reliably and reproducibly.

Data will be presented showing the bond strength of particular examples and the types of failure

mode. Evaluation of these bumps is an essential part of the quality assurance for the flip chip

products in which they are used. Previously these stud bumps were made from gold and its

softness precluded the use of pull. Only shear testing could be used. Pull would be the preferred

technique as a simple tensile load is applied to the bond. The extra resilience of copper permits

the use of pull jaws to grip the material and exert a load. It is possible that this technique might

be extended to first ball bonds where copper is substituted for gold.