Laser Cuts Increase the Reliability of Heavy-Wire Bonds and Enables On-line Process Control with Thermography

Abstract:
Observations on the reliability of heavy wire bonds show a significant decrease of active thermal cycling lifetime with increasing wire diameter. The innovation outlined in this paper is, to shape the wire bond in the bonding region in such a way, that the thermo-mechanical load on the interface region between wire and semiconductor metallization is being reduced significantly. The efficiency of the approach is proven by finite element simulations and experiments. Moreover, the experiments indicate that the method can be used as a ’non-destructive‘ in-situ measurement technique, that enables to directly derive the crack growth from thermography measurements of the notches. The notches work like a magnifier for the thermography camera and eliminate the preconditioning e.g. with black coloring.