Characterization of Eutectic Sn-Cu Solder Alloy Properties Improved by Additions of Ni, Co and In

Pitinan Piyavatin; Gobboon Lothongkum; Boonrat Lohwongwatana

doi:10.3139/120.110342

Article

Characterization of Eutectic Sn-Cu Solder Alloy Properties Improved by Additions of Ni, Co and In

Pitinan Piyavatin , Gobboon Lothongkum and Boonrat Lohwongwatana

Published/Copyright: May 26, 2013

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From the journal Materials Testing Volume 54 Issue 6

Abstract

Recently, the cost factor of raw materials has emerged continuous improvement of tin-copper solder alloys. This work aims to improve the microstructural and mechanical properties of the eutectic tin-copper solder alloys by addition of nickel, cobalt and indium. The temperature profile of reflow soldering in surface-mount assembly was simulated to produce realistic joint microstructures. Key properties for electronic soldering were characterized, i.e. melting behaviour, solidification beha-viour, wettability, electrical resistivity, microstructures and mechanical properties. The results showed that addition of Ni, Co and In can effectively improve the mechanical properties of Sn-0.7Cu solder alloy i.e. microhardness and shear strength by providing preferred interfacial morphology and formation of intermetallic compound precipitates. The new solder alloys also showed reduced liquidus and solidus temperatures whereas no significant degradation of other key properties were seen.

Kurzfassung

In der letzten Zeit führt der Kostenfaktor der Rohmaterialien zur kontinuierlichen Verbesserung der Zinn-Kupfer-Lötlegierungen. Die diesem Beitrag zugrundeliegende Arbeit zielt darauf ab, die mikrostrukturellen und mechanischen Eigenschaften einer eutektischen Zinn-Kupfer-Lötlegierung durch Zugabe von Ni, Co und In zu verbessern. Das Temperaturprofil des Reflow-Lötprozesses einer SMD-Montage wurde simuliert, um realistische Mikrostrukturen der Lötung zu erhalten. Es wurden die Schlüsseleigenschaften des elektronischen Lötens charakterisiert, diese sind das Erschmelzungsverhalten, das Erstarrungsverhalten, die Benutzbarkeit, der elektrische Widerstand, die Mikrostruktureigenschaften sowie die mechanischen Eigenschaften. Die Ergebnisse zeigen, dass die Zugabe von Ni, Co und In die mechanischen Eigenschaften der Sn-0,7Cu-Legierung effektiv verbessern kann, das heißt im Einzelnen, dass die Mikrohärte sowie die Scherzugfestigkeit durch die Bereitstellung einer vorzüglichen Grenzflächenmorphologie und durch die Ausscheidung von intermetallischen Verbindungen ansteigt. Die neuen Lötlegierungen wiesen außerdem reduzierte Liquidus- und Solidustemperaturen auf, wobei keine signifikanten Verschlechterungen der anderen Schlüsseleigenschaften auftraten.

Pitinan Piyavatin was born in 1985. He is graduate student at Chulalongkorn University studying master degree in Metallurgical Engineering. He received bachelor degree from Chulalongkorn University, Thailand, also in Metallurgical Engineering in 2008. His research scope is related to development and characterizations of novel solder alloys.

Assoc. Prof. Dr.-Ing. Gobboon Lothongkum was born in 1960. He is metallurgical engineering professor at the Faculty of Engineering, Chulalongkorn University, Thailand. He is also affiliated with the Innovative Metals Research Unit, Chulalongkorn University. He received Dr.-Ing Degree from University of the Federal Armed Force Hamburg, Germany in 1994. He received also the International Welding Engineer Certificate of The International Welding Institute in 2006. His areas of expertise include corrosion of metals and alloys, welding and metal joining, high temperature materials and stainless steels.

Boonrat Lohwongwatana, Ph.D., is metallurgical engineering professor at the Faculty of Engineering, Chulalongkorn University, Thailand. He is also affiliated with the Innovative Metals Research Unit, Chulalongkorn University. He is also affiliated with the Innovative Metals Research Unit, Chulalongkorn University. Born in 1977, he received the Royal Thai government scholarship to study Materials Science and Metallurgy from 1995–2007. He received bachelor degree in Materials Science and Engineering from Northwestern University, Evanston, IL, USA, and received master and PhD degrees from California Institute of Technology in 2002 and 2007, respectively. His areas of expertise include bulk metallic glass, alloy developments, jewelry and precious metals, solder and low melting alloys, and biomaterials.

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Published Online: 2013-05-26

Published in Print: 2012-06-01

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https://doi.org/10.3139/120.110342