Critical evaluation of creep behavior of Sn-Ag-Cu solder alloys over wide range of temperatures

Kanjilal, Anwesha and Jangid, Vikas and Kumar, Praveen (2017) Critical evaluation of creep behavior of Sn-Ag-Cu solder alloys over wide range of temperatures. In: MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING, 703 . pp. 144-153.

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Abstract

A critical survey of the current literature on creep behavior of Pb-free Sn based Sn-Ag-Cu (SAC) alloys show that there is considerable discrepancy in the creep parameters, such as activation energy, Q(c) and stress exponent, n. Accordingly, this study addresses the underlying reasons for such variability in the existing data by studying the creep behavior in compression of two most commonly used SAC alloys, namely Sn-1 wt.%Ag-0.5 wt.%Cu and Sn3 wt.% Ag-0.5 wt.% Cu, over wide range of temperatures, from 60 to 200 degrees C, and stresses from 7 to 14 MPa. Analysis of microstructure of SAC alloys reveals that both temperature and stress have pronounced effects on coarsening of precipitates during creep. The steady state strain rate increases with both temperature and stress as well as with decrease in Ag content of the alloys. Irrespective of the composition, SAC alloys show a transition in the creep behavior around 150 degrees C, with Cie and n changing from 55 kl/mol and 7, respectively, at low temperatures to 100 kJ/mol and 5, respectively, at higher temperatures. Such a simultaneous change in both Q(c) and n suggests that creep mechanism in SAC alloys is dislocation climb controlled by the core diffusion at low temperatures and the lattice diffusion at high temperatures.

Item Type:	Journal Article
Publication:	MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING
Additional Information:	Copy right for this article belongs to the ELSEVIER SCIENCE SA, PO BOX 564, 1001 LAUSANNE, SWITZERLAND
Department/Centre:	Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	30 Oct 2017 03:39
Last Modified:	30 Oct 2017 03:39
URI:	http://eprints.iisc.ac.in/id/eprint/58118

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