Influence of Zn addition on the microstructure, melt properties and creep behavior of low Ag-content Sn–Ag–Cu lead-free solders

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 608; pp. 130 - 138
• Main Authors: El-Daly, A.A., Hammad, A.E., Al-Ganainy, G.S., Ragab, M.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.07.2014; Elsevier
• Subjects: Alloying additive; Applied sciences; Brazing. Soldering; Creep; Creep (materials); Creep properties; Creep strength; Cross-disciplinary physics: materials science; rheology; Deformation, plasticity, and creep; Differential scanning calorimetry; Elasticity. Plasticity; Exact sciences and technology; Joining, thermal cutting: metallurgical aspects; Lead-free solder; Materials science; Mathematical models; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructure; Physics; Solders; Thermal properties; Treatment of materials and its effects on microstructure and properties; Zinc; Thermal properties; Creep properties; Lead-free solder; Microstructure; Differential scanning calorimetry; Temperature dependence; Molten state; Creep; Intermetallic compound; Fiber; Tensile property; Creep strength; Precipitate; Steady state; Tension test; Structure composition relationship; Zinc addition; Lifetime; Soldered joint; Lead free solder; Stress effects; Supercooling; Dislocation pile up
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2014.04.070

The effects of Zn addition on the microstructure, thermal behavior and tensile creep properties of Sn–1.0Ag–0.3Cu (SAC103) alloy were systematically investigated. Differential scanning calorimetry (DSC) reveals that the reductions of undercooling and pasty range are more significant for Zn-containing solders, although the solidus temperature remains the same or slightly changed. The creep life time of plain SAC103 alloy was remarkably enhanced two times with the addition of 3wt% Zn. Moreover, significant improvement in creep resistance of 145% and 360% is realized with the addition of 2wt% and 3wt% Zn into SAC(103) solder, respectively. The improvement of creep behavior is due to the microstructural change of Zn-containing solders, since the formation of new (Cu,Ag)5Zn8 intermetallic compound (IMC) phase and fine fiber-like Ag3Sn precipitates at the surface of β-Sn matrix could provide more obstacles for dislocation pile-up, which enhanced the stress exponent values and improved the creep resistance and creep life time. These results show that the Garofalo model is suitable for describing the steady-state creep behavior of SAC(103) solders over the tested stress and temperature ranges.