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Performance of SAC305 and SAC305-0.4La lead free electronic solders at high temperature

Muhammad Aamir (School of Engineering, Edith Cowan University, Joondalup, Australia)
Majid Tolouei-Rad (School of Engineering, Edith Cowan University, Joondalup, Australia)
Israr Ud Din (Research Center for Modelling and Simulation, National University of Sciences and Technology, Islamabad, Pakistan)
Khaled Giasin (School of Engineering, Cardiff University, Cardiff, UK)
Ana Vafadar (School of Engineering, Edith Cowan University, Joondalup, Australia)

Soldering & Surface Mount Technology

ISSN: 0954-0911

Article publication date: 25 June 2019

Issue publication date: 21 August 2019

Abstract

Purpose

Tin-Silver-Copper is widely accepted as the best alternative to replace Tin-Lead solders in microelectronics packaging due to their acceptable properties. However, to overcome some of the shortcomings related to its microstructure and in turn, its mechanical properties at high temperature, the addition of different elements into Tin-Silver-Copper is important for investigations. The purpose of this paper is to analyse the effect of lanthanum doping on the microstructure, microhardness and tensile properties of Tin-Silver-Copper as a function of thermal aging time for 60, 120 and 180 h at a high temperature of 150°C and at high strain rates of 25, 35 and 45/s.

Design/methodology/approach

The microstructure of un-doped and Lanthanum-doped Tin-Silver-Copper after different thermal aging time is examined using scanning electron microscopy followed by digital image analyses using ImageJ. Brinell hardness is used to find out the microhardness properties. The tensile tests are performed using the universal testing machine. All the investigations are done after the above selected thermal aging time at high temperature. The tensile tests of the thermally aged specimens are further investigated at high strain rates of 25, 35 and 45/s.

Findings

According to the microstructural examination, Tin-Silver-Copper with 0.4 Wt.% Lanthanum is found to be more sensitive at high temperature as the aging time increases which resulted in coarse microstructure due to the non-uniform distribution of intermetallic compounds. Similarly, lower values of microhardness, yield strength and ultimate tensile strength come in favours of 0.4 Wt.% Lanthanum added Tin-Silver-Copper. Furthermore, when the thermally aged tensile specimen is tested at high strains, two trends in tensile curves of both the solder alloys are noted. The trends showed that yield strength and ultimate tensile strength increase as the strain rate increase and decrease when there is an increase in thermal aging.

Originality/value

The addition of higher supplement (0.4 Wt.%) of Lanthanum into Tin-Silver-Copper showed a lower hardness value, yield strength, ultimate tensile strength, ductility, toughness and fatigue in comparison to un-doped Tin-Silver-Copper at high temperature and at high strain rates. Finally, simplified material property models with minimum error are developed which will help when the actual test data are not available.

Keywords

Acknowledgements

Conflicts of interest: The authors declare that they have no conflict of interest.

Citation

Aamir, M., Tolouei-Rad, M., Din, I.U., Giasin, K. and Vafadar, A. (2019), "Performance of SAC305 and SAC305-0.4La lead free electronic solders at high temperature", Soldering & Surface Mount Technology, Vol. 31 No. 4, pp. 250-260. https://doi.org/10.1108/SSMT-01-2019-0001

Publisher

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Emerald Publishing Limited

Copyright © 2019, Emerald Publishing Limited