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Laser cuts increase the reliability of heavy-wire bonds and enables on-line process control with thermography

 
: Middendorf, A.; Grams, A.; Lang, K.-D.; Schmitz, S.; Wittler, O.

MESAGO PCIM GmbH, Stuttgart:
PCIM Europe 2015. CD-ROM : International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management, Nuremberg, 19 – 21 May 2015; Proceedings
Berlin: VDE Verlag, 2015
ISBN: 978-3-8007-3924-0
pp.1327-1334
International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management <2015, Nuremberg>
English
Conference Paper
Fraunhofer IZM ()

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 'nondestructive' 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.

: http://publica.fraunhofer.de/documents/N-383122.html