Abstract
Tensile and low cycle fatigue properties of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge (mass%) lead-free solder were investigated using miniature size specimens and obtained data were compared to those of Sn-3.0Ag-0.5Cu (mass%). The microstructure of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge consists of dendritic β-Sn phases and ternary eutectic phases surrounding them which are composed of β-Sn, (Cu,Ni)6Sn5 and Ag3Sn. Tensile strength and 0.1% proof stress of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge are superior to those of Sn-3.0Ag-0.5Cu at 25°C and 150°C. However, elongation of it is inferior to that of Sn-3.0Ag-0.5Cu at both temperatures. Fatigue lives of both alloys obey the Manson-Coffin equation and are analogous at 25°C. Although fatigue lives of both alloys decrease at 150°C, the fatigue life of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge is inferior to that of Sn-3.0Ag-0.5Cu. At 150°C, the crack mainly progresses at grain boundaries of recrystallized grains. Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge has several grain boundaies which can be the origin of the crack so that fatigue lives degrade at 150°C.
Publisher
Trans Tech Publications, Ltd.
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science
Reference8 articles.
1. M. Nagano, N. Hidaka, M. Shimoda, H. Watanabe, Effect of germanium content on oxidation prevention of Sn-Ag-Cu lead-free solder, Proc. of New Frontiers of Process Science and Engineering in Advanced Materials, Part 2, (2004) 256-261.
2. H. Watanabe, The lead-free solder of addition micro-elements in industrial products, Journal of Japan Institute of Electronics Packaging 8 (2005) 183-187.
3. I. Shohji, S. Tsunoda, H. Watanabe, T. Asai, M. Nagano, Reliability of solder joint with Sn-Ag-Cu-Ni-Ge lead-free alloy under heat exposure conditions, Materials Transactions 46 (2005) 2737-2744.
4. Y. Kariya, T. Asai, T. Suga, M. Otsuka, Mechanical properties of lead free solder alloys evaluated by miniature size specimen, TMS Letter 1 (2004) 169-170.
5. I. Shohji, T. Osawa, T. Matsuki, Y. Kariya, K. Yasuda, T. Takemoto, Effect of specimen size and aging on tensile properties of Sn-Ag-Cu lead-free solders, Materials Transactions 49 (2008) 1175-1179.