In this paper, a microstructure-dependent creep model is developed that accounts for the hierarchal microstructure at multiple length scales. The model considers three distinguishable phases in the solder alloy at two different length scales: at the larger scale Sn dendrites of micrometer size are embedded in a homogeneous eutectic region; at a much smaller length scale the eutectic region consists of submicron size particles embedded in a homogeneous Sn matrix. The model predictions agree well with creep test data of lanthanum doped SnAg solders.
Issue Section:
Research Papers
1.
Dutta
, I.
, 2003 “A Constitutive Model for Creep of Lead-Free Solders Undergoing Strain-Enhanced Microstructural Coarsening: A First Report
,” J. Electron. Mater.
0361-5235, 32
, pp. 201
–207
.2.
Pei
, M.
, and Qu
, J.
, 2007 “Effect of Rare Earth Elements on Lead-Free Solder Microstructure Evolution
,” ECTC
, pp. 198
–204
.3.
Pei
, M.
, 2007, “Effects of Lanthanum Doping on the Microstructure and Mechanical Behavior of a SnAg Alloy
,” Ph.D. thesis, Georgia Institute of Technology, Atlanta, GA.4.
Qu
, J.
, and Cherkaoui
, M.
, 2006, Fundamentals of Micromechanics of Solids
, Wiley
, Hoboken, NJ
.6.
Gao
, F.
, and Takemoto
, T.
, 2006, “Mechanical Properties Evolution of Sn-3.5Ag Based Lead-Free Solders by Nanoindentation
,” Mater. Lett.
0167-577X, 60
, pp. 2315
–2318
.7.
Gao
, F.
, and Takemoto
, T.
, 2006, “The Evolution of Plastic Deformation of Sn3.5Ag-Based Lead-Free Solders
,” ECTC
, pp. 269
–274
.8.
Karakaya
, I.
, and Thompson
, W.
, 1987, Bull. Alloy Phase Diagrams
0197-0216, 8
, pp. 340
–347
.9.
Chen
, Z.
, Shi
, Y.
, Xia
, Z.
, and Yan
, Y.
, 2002, “Study on the Microstructure of a Novel Lead-Free Solder Alloy SnAgCu-RE and Its Soldered Joints
,” J. Electron. Mater.
0361-5235, 31
, pp. 1122
–1128
.Copyright © 2008
by American Society of Mechanical Engineers
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