Title: FEM simulation of the size and constraining effect in lead free solder joints
Authors: Lederer, Martin
Khatibi, Golta
Weiss, Brigitte
Citation: Applied and Computational Mechanics. 2012, vol. 6, no. 1, p. 17-24.
Issue Date: 2012
Publisher: University of West Bohemia
Document type: článek
URI: http://www.kme.zcu.cz/acm/index.php/acm/article/view/169/156
ISSN: 1802-680X (Print)
2336-1182 (Online)
Keywords: von Misesovo kritérium;tvárný lom;pájené spoje
Keywords in different language: von Mises criterion;ductile fracture;solder joints
Abstract: Due to the ongoing miniaturization in microelectronics, the influence of dimensional constraining effects on the strength of solder joints becomes increasingly important. Detailed investigations show a strong dependence of tensile strength and ductility on solder geometry. This paper focuses on FEM simulations of the thickness effect of Sn-3.5Ag solder gaps under tensile load. Solder joints and copper base material are simulated with an elasto-plastic material model in the framework of von Mises plasticity. Within the solder material a pronounced triaxiality of stress is observed. In consequence, the von Mises stress inside the solder material is considerably smaller than the longitudinal stress along the tensile axis. This leads to increased tensile strength of thin solder joints. However, the increase of strength also depends on the yield stress of the copper base material. The FEM simulations were compared with experimental results of tensile tests and satisfactory coincidence was found. The remaining deviation between experiment and simulation is explained by pressure dependency of the flow stress. In conclusion, a new pressure dependent plasticity model is suggested.
Rights: © 2012 University of West Bohemia. All rights reserved.
Appears in Collections:Volume 6, number 1 (2012)
Volume 6, number 1 (2012)

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