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Bahi, M. A., Fremont, H., Landesman, J.-P., Gentil, A. & Lecuyer, P. (2009) A new methodology for the identification of ball bond degradation during high-temperature aging tests on devices in standard plastic packages. Microelectron. Reliab. 49 1273–1277.
Added by: Richard Baschera (2016-03-10 21:41:23) Last edited by: Richard Baschera (2016-05-24 10:03:29) |
| Type de référence: Article DOI: 10.1016/j.microrel.2009.07.009 Numéro d'identification (ISBN etc.): 0026-2714 Clé BibTeX: Bahi2009 Voir tous les détails bibliographiques  |
Catégories: PCM Mots-clés: qualification Créateurs: Bahi, Fremont, Gentil, Landesman, Lecuyer Collection: Microelectron. Reliab. |
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| Résumé |
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We describe a new methodology for the "in situ" identification of wire-bond degradation at early stages during high-temperature aging tests on devices with standard plastic packages. This methodology is based on the measurement of the changes in wire bond resistance, which is deduced from the I(V) characteristics of the ESD protection diodes on each contact pad of the circuit. In a first stage, the measurement procedure is described, with emphasis on the initial temperature calibration. This procedure allows for an "in situ" measurement sequence, where the packages stay in the aging chamber, at elevated temperature, during the electrical tests on the pad connections performed at different aging durations. By following accurately the package temperature, using a thermocouple, it is possible to correct for slight changes and thus get a reliable I-V measurement for each interconnection. In the second stage, the aging test results are described, showing the evolution of each individual interconnection. We were able to identify the onset of wire-bond degradation through the progressive increase of their resistance. To allow for better determination of the degradation process, once an increase in wire bond resistance was detected, complete I(V) curves were recorded at the pin(s) of interest. For each pin of a TQFP64 package, the tests were performed at least twice a day, with increased density when initial failure is detected (one complete measurement every 3 h). This strategy allowed for the detection of different behaviors on the wire bonds: good ball bonds (i.e. ball bonds with no change in their resistance), ball bond with intermittent opens (these ball bonds are in the process of degradation, and thermo-mechanical stresses induced in the resin by very small temperature changes are sufficient to open or close the circuits) and completely destroyed ball bonds, for which the resistance stays in an "high" level. This approach to wire-bond degradation in plastic packages is very powerful in terms of the number of interconnections which can be followed "in real time" and especially has the advantage, over other classical approaches, that the devices under test stay operational, contrary to what occurs with other types of destructive testing. These electrical test results are compared with metallographic investigations performed after a series of mechanical tests on the ball bonds (wire pull/ball shear tests) on a set of identical devices which undergone exactly the same High Temperature Storage (HTS) aging for 2000 h at 165 degrees C. (C) 2009 Elsevier Ltd. All rights reserved.
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