Creep Characteristic of Sn1.0Ag0.7Cu Lead-Free Solders with Element Addition

• Published in: Applied mechanics and materials Vol. 853; no. Innovation in Testing and Evaluation of Structural Integrity; pp. 192 - 196
• Main Authors: Itoh, Takamoto, Ogawa, Fumio, Yamashita, Mitsuo, Nagao, Hiroki, Sakane, Masao, Hokazono, Hiroaki
• Format: Journal Article
• Language: English
• Published: Zurich Trans Tech Publications Ltd 01.09.2016
• Subjects: Bismuth; Coarsening; Creep (materials); Intermetallics; Lead free; Microstructure; Rupture; Solders; Lead-Free Solder; Creep; Microstructure; Life Prediction
• ISBN: 9783038357926; 3038357928
• ISSN: 1660-9336; 1662-7482; 1662-7482
• DOI: 10.4028/www.scientific.net/AMM.853.192

In this study, creep properties of lead-free solders based on Sn1.0Ag0.7Cu were investigated. In the solders, germanium, nickel and bismuth were added to improve their mechanical properties. The effect of element addition on their microstructure and creep properties were studied. Creep properties were improved with the element addition. Creep rupture lifetime was the longest for SnAgCuBiNiGe, and that of SnAgCuBi was the second longest. It was made clear that a minimum creep strain rate is useful for lifetime prediction of the solders. An observation of microstructure was performed and coarsening of intermetallics after creep test was identified, resulting in creep rupture. It was found that the addition of bismuth hinders the coarsening of intermetallics and is effective to improve the creep properties of the solders.