International Journal for Multiscale Computational Engineering

ISSN for PRINT: 1543-1649

For Online Access

Best Paper Award Selection - Editorial Board Site

2007, Volume5

Issue 2 Guest Editor P. Trovalusci

100 pages

DOI: 10.1615/IntJMultCompEng.v5.i2

Issue price - $138.00

Marc Geers
Eindhoven University of Technology

R. L. J. M. Ubachs
Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513,5600MB Eindhoven, The Netherlands

M. Erinc
Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513,5600MB Eindhoven, The Netherlands

M. A. Matin
Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513,5600MB Eindhoven, The Netherlands

P. J. G. Schreurs
Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513,5600MB Eindhoven, The Netherlands

W. P. Vellinga
Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513,5600MB Eindhoven, The Netherlands

The past years have triggered considerable scientific efforts toward the predictive analysis of the reliability of solder connections in micro-electronics. Evidently, the replacement of the classical Sn-Pb solder alloy by a lead-free alternative constitutes the main motivation for this. This paper concentrates on the theoretical, computational, and experimental multiscale analysis of the microstructure evolution and degradation of the reference material, Sn-Pb, and the most promising alternative, a Sn-Ag-Cu (SAC) alloy. The microstructure evolution of Sn-Pb is analyzed on the basis of a representative volume element of the underlying microstructure. At this level, a phase field model is used to incorporate the thermally driven diffusion, thereby accounting for a nonlocal interfacial free energy. Starting from this phase field description of the microstructure, the intrinsic viscoplastic response and the damage developing in the phases and interfaces are analyzed. The correlation with experimentally found results is highlighted, whereby the microstructural dependence is the key issue. The lead-free SAC alloy is investigated at the material level by considering the mechanical and thermal anisotropy of the Sn-rich grains. It is shown that experimental results indicate severe grain boundary damage on thermal cycling. Using detailed microstructural information obtained through orientation imaging microscopy, the elaborated microstructural model reflects patterns of localized plastic strains and damage that show remarkable correlation with the experimentally found patterns. At the mesoscale, the numerical-experimental analysis concentrates at the internal and external interfaces in the material. A cohesive zone methodology is followed here, which represents the homogenized response of the underlying complex interfacial intermetallic microstructure. The motivation, qualification and quantification of the cohesive zone parameters are briefly addressed. The paper concludes by emphasizing the importance of collecting and exploiting different computational and experimental techniques in a multiscale setting, for which the case studied here constitutes a relevant example.

DOI: 10.1615/IntJMultCompEng.v5.i2.30 Download article, 93-103 pages

Article price - $35.00

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