Bonding mechanism in ultrasonic gold ball bonds on copper substrate

I. Lum, J. P. Jung, Y. Zhou

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


The effects of process parameters on bond formation in thermosonic gold ball bonding on a copper substrate at ambient temperatures have been investigated with scanning electron microscopy (SEM). A model was developed based on classical microslip theory to explain the general phenomena observed in the evolution of bond footprints left on the substrate. The specific effects of ultrasonic energy and complex stress distributions arising from tool geometry must be taken into consideration and were incorporated into the model. It was shown that relative motion existed at the bonding interface as microslip at lower powers, transitioning into gross sliding at higher powers. With increased normal bonding forces, the transition point into gross sliding occurred at higher ultrasonic bonding powers.

Original languageEnglish
Pages (from-to)1279-1286
Number of pages8
JournalMetallurgical and Materials Transactions A: Physical Metallurgy and Materials Science
Issue number5
StatePublished - May 2005


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