Damage evolution in Al wire bonds subjected to a junction temperature fluctuation of 30 K

Agyakwa, Pearl and Yang, Li and Arjmand, Elahjeh and Evans, Paul and Corfield, Martin and Johnson, Christopher Mark (2016) Damage evolution in Al wire bonds subjected to a junction temperature fluctuation of 30 K. Journal of Electronic Materials . pp. 1-14. ISSN 1543-186X

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Ultrasonically bonded heavy Al wires subjected to a small junction temperature fluctuation under power cycling from 40°C to 70°C were investigated using a non-destructive three-dimensional (3-D) x-ray tomography evaluation approach. The occurrence of irreversible deformation of the microstructure and wear-out under such conditions were demonstrated. The observed microstructures consist of interfacial and inter-granular cracks concentrated in zones of stress intensity, i.e., near heels and emanating from interface precracks. Interfacial voids were also observed within the bond interior. Degradation rates of ‘first’ and ‘stitch’ bonds are compared and contrasted. A correlative microscopy study combining perspectives from optical microscopy with the x-ray tomography results clarifies the damage observed. An estimation of lifetime is made from the results and discussed in the light of existing predictions.

Item Type: Article
Keywords: Aluminum, wire bonds, power cycling, reliability, x-ray tomography, high cycle thermal fatigue
Schools/Departments: University of Nottingham UK Campus > Faculty of Engineering > Department of Electrical and Electronic Engineering
Identification Number: https://doi.org/10.1007/s11664-016-4519-0
Depositing User: Burns, Rebecca
Date Deposited: 17 May 2016 14:18
Last Modified: 15 Sep 2016 20:37
URI: http://eprints.nottingham.ac.uk/id/eprint/33365

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