Improved creep resistance and thermal behavior of Ni-doped Sn-3.0Ag-0.5Cu lead-free solder

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• 作者：A.A. El-Daly ; A.M. El-Taher ; T.R. Dalloul
• 关键词：Lead-free solder alloys ; Microstructure ; Mechanical properties ; Thermal properties
• 刊名：Journal of Alloys and Compounds
• 出版年：25 February, 2014
• 年：2014
• 卷：587
• 期：Complete
• 页码：32-39
• 全文大小：4224 K

文摘

To develop lead-free solders for advance electrical components, a series of Sn-3.0Ag-0.5Cu (SAC 305) solders containing small amounts of Ni have been investigated. Results showed that the addition of Ni not only decreased the amount of undercooling by about 7.9-8.5 掳C, but also reduced the solidus temperature of SAC(305) solder from 219.9 to 216.2 掳C. Microstructure analysis revealed that Ni could replace the Cu atoms in the Cu₆Sn₅ phase and generates a new 畏-(Cu, Ni)₆Sn₅ IMC phase containing large amount of Ni after 0.5%Ni addition. The high solubility of Ni in Cu₆Sn₅ increased the substitutional defects and generated inter-atomic stress around Ni atoms, which in turn impeded the dislocation movements in different crystal directions, resulting in an increase in the creep resistance and total fracture time of 0.5%Ni-doped SAC(305) solder. In addition, the formation of fine fiber-like Ag₃Sn and finer dot-shaped precipitates at the surface of 尾-Sn matrix could provide more obstacles for dislocation pile up in the adjacent grains and enhanced the creep resistance. However, when the concentration of Ni exceeded 0.5 wt%, the benefits of creep behavior and fracture time were reduced due to the formation of small amount of abrasive Ag₃Sn and coarsening of (Cu, Ni)₆Sn₅ IMCs in the eutectic colony.