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The present paper investigates the microstructural and mechanical properties of Sn-1.0Ag-0.5Cu (SAC105) solder alloy with 0.06 wt% Ni and 0.5 wt% Sb additions. The study revealed that the microstructure properties and elastic moduli of such solder alloy improved. Results indicated that Ni element diffused from the molten solder matrix into the IMC particles to form the Ni 3 Sn 4 IMC phase during solidification. Thus, Ni improved the solder microstructure and increased the drop lifetime of the electronic assembly. Meanwhile, by adding Sb element, no new IMCs formed due to the high solubility of Sb in Sn, but provide solid solution strengthening. In terms of tensile behavior, the SAC105–0.5Sb exhibited the highest strength and largest ductility. As well, all examined alloys exhibited higher mechanical properties with increasing strain rate and/or decreasing testing temperature. Moreover, notable improvements of 31.25% and 101.1% in elongation were obtained with addition of Ni and Sb elements, respectively. Consequently, ductility was enhanced by Ni or Sb additions. Furthermore, the average activation energy (Q) for SAC105, SAC105-0.06Ni, and SAC105-0.5Sb solders were 49, 57 and 63.5 kJ/mol, respectively, which is close to that of pipe-diffusion mechanism in Sn-based solder matrix. [ABSTRACT FROM AUTHOR]

Highlights: [•] Small amounts of Ni and Sb have been added into hypoeutectic Sn–6.5Zn solder. [•] Sb addition refined the microstructure and Ni enhanced the formation of (Ni, Zn)3Sn4. [•] Ni and Sb can slightly reduce the undercooling and pasty range. [•] The Sn–6.5Zn–0.5Sb alloy has the highest UTS and appropriate ductility. [•] Correlations between the microstructure and mechanical parameters were analyzed. [Copyright &y& Elsevier]

Highlights: [•] Same amount of Ni and Sb have been added into Sn–6.5Zn solder. [•] Correlations between the microstructure and creep parameters were analyzed. [•] Ni and Sb are slightly reduced the undercooling and pasty range. [•] Sb and Ni provide about 270% and 182% higher creep resistance than Sn–6.5Zn solder. [ABSTRACT FROM AUTHOR]

Highlights: [•] This work investigates the effect of (0.05–0.1wt.%) Ni additions on the SAC (0507) solder. [•] Enhanced strength of SAC (0507)–0.05Ni was due to microstructural refinement and uniform distribution of the IMCs. [•] Improved ductility and worsen mechanical properties of SAC (0507)–0.1Ni alloy were due to the presence of large β-Sn grains. [•] Both YS and UTS increased with and decreasing temperature and decreasing strain rate. [ABSTRACT FROM AUTHOR]

Abstract: Nowadays, a major concern of Sn–Cu based solder alloys is focused on continuously improving the comprehensive properties of solder joints formed between the solders and substrates. In this study, the influence of Ag and/or In doping on the microstructures and tensile properties of eutectic Sn–0.7Cu lead free solder alloy have been investigated. Also, the effects of temperature and strain rate on the mechanical performance of Sn–0.7Cu, Sn–0.7Cu–2Ag, Sn–0.7Cu–2In and Sn–0.7Cu–2Ag–2In solders were investigated. The tensile tests showed that while the ultimate tensile strength (UTS) and yield stress (YS) increased with increasing strain rate, they decreased with increasing temperature, showing strong strain rate and temperature dependence. The results also revealed that with the addition of Ag and In into Sn–0.7Cu, significant improvement in YS (∼255%) and UTS (∼215%) is realized when compared with the other commercially available Sn–0.7wt. % Cu solder alloys. Furthermore, the Sn–0.7Cu–2Ag–2In solder material developed here also exhibits higher ductility and well-behaved mechanical performance than that of eutectic Sn–0.7Cu commercial solder. Microstructural analysis revealed that the origin of change in mechanical properties is attributed to smaller β-Sn dendrite grain dimensions and formation of new inter-metallic compounds (IMCs) in the ternary and quaternary alloys. [Copyright &y& Elsevier]

Abstract: In this study, the effects of separate and dual additions of small amount of Cu, In and Ag on the microstructure and elastic properties as well as thermal behavior of the eutectic Sn–9Zn solder alloy were investigated. The elastic properties of the newly developed ternary and quaternary alloys have been investigated using sound wave velocity measurements at 4MHz and T =25°C. In particular, the hardness, the attenuation coefficient, the bulk and shear moduli, Young''s and Poisson''s ratio have been established for a range of alloy compositions. Results showed that alloying of Cu, In and Ag resulted in reducing fusion heat, solidus temperature and broadening the pasty range. Moreover, the presence of additional elements in Sn–Zn alloy system allows many complex intermetallic (IMC) phases to form. Both the hardness and reduced modulus increase as the Poisson''s ratio of the alloy decreases. The elastic properties can be correlated with the formation of the new IMC phases. By analyzing the quotient of shear modulus to bulk modulus, we can assume that the Sn–9Zn, Sn–9Zn–1.5Ag and Sn–9Zn–0.7Cu alloys are ductile solders whereas, the Sn–9Zn–1.5In and Sn–9Zn–1.5Ag–0.7Cu alloys are brittle in nature. [Copyright &y& Elsevier]

Abstract: In the present study, the effects of separate and dual addition of small amount of Ag and Cu on the microstructure and mechanical properties of the eutectic Sn–9Zn solder alloy were investigated. Results indicate that alloying of Ag and/or Cu resulted in refine the coarse needle-like Zn-rich phase and formation of intermetallic compounds (IMCs) with the eutectic solder. Single addition of Ag led to formation of AgZn, Ag5Zn8 and ɛ-AgZn3 IMCs, which results in significant increase in both ultimate tensile strength (UTS) and ductility, while, the flower shaped and rod shaped Cu6Sn5, γ-Cu5Zn8 and ɛ-CuZn5 IMCs produced by Cu alloying, results in small increase in UTS and ductility. The dual addition of Ag and Cu suppressed the appearance of Ag5Zn8 IMCs due to the competition for Zn between Cu and Ag, which results in slight decrease in UTS and ductility of Sn–9Zn–1.5Ag solder. Worthy of notice is that all alloys demonstrated an increase in both UTS and yield stress with increasing strain rate and/or decreasing testing temperature, indicating that the tensile behavior of the four alloys often exhibits a strain rate and temperature dependence. [Copyright &y& Elsevier]

The investigation of a prospective lead-free solder alloy provides the essential data for microelectronic applications and estimation of solder joint reliability. In this study, we used the rotary magnetic field (RMF) as a novel approach to improve the mechanical performance and microstructure of Sn-2.0Ag-0.5Cu-2.0Zn (SACZ) lead-free solder alloy. The results revealed that both microstructure evolution and tensile characteristics enhanced by applying RMF. Microstructure studies showed that applying RMF reduced the grain size of β-Sn and IMCs. These modifications improved the tensile strength of the solder alloy. RMF improved Ultimate tensile strength (UTS), Yield stress (YS), Young modulus (E), and Elongation (El.%) of SACZ at room temperature by ~110%, 112%, 119%, and 108%, respectively. Besides, stress exponent, n, over the entire temperature and activation energy, Q, parameters calculated using the Garofalo hyperbolic sine law. n values were 5.9–8.3for SACZ alloy and 6.8–9.6 for SACZ-B alloy. Q values were ~ 51.8 kJ/mol for SACZ alloy and 79.2 kJ/mol for SACZ-B alloy close to pipe diffusion-controlled creep of tin. According to results, RMF is a promising approach to develop the microstructure evolution and mechanical characteristics of alloys. We hoped that the results would be useful for microelectronic applications. • Microstructure and tensile behavior of SACZ with RMF improved. • β-Sn grain size and IMC particles were reduced by RMF. • SACZ with RMF showed the highest strength. [ABSTRACT FROM AUTHOR]

Abstract Studying and understanding the dendritic growth process is a challenging topic related to liquid-solid phase transition, as it helps to predict the final microstructure controlling the solder properties. In a specific case of the design of Sn-Bi and Sn-Bi-Cu alloys, the solidification microstructures and corresponding electrical and elastic properties were studied with and without permanent magnetic stirring (PMS), as their influence on the growth morphology of dendrites is not yet fully assessed to date. We use pulse echo overlap (PEO) method for measuring the polycrystalline bulk modulus K , Young's modulus E , shear modulus G , Poisson ratio υ and hardness H. The PMS-driven flow caused a disruption of the columnar β-Sn dendrites and columnar-to-equiaxed transition (CET). Such behavior is believed to evolve from dendrite fragmentation, arises through complex hyper-branched morphologies at the origin of Lorentz force and Seebeck effect that acting on the melt. Both the hardness and elastic modulus are increased as the Poisson's ratio decreased. Moreover, the Pugh ratio clarified the ductility behavior of the alloy samples, while Poisson's ratio and electrical resistivity display slight decrease in the ionic contribution with applying PMS and/or Cu content. These results open new ways to predict the final microstructure controlling the dendritic growth in metallic alloys. Graphical abstract Image 1 Highlights • The effect of applying PMS on the properties of Sn-20Bi-xCu alloys was studied. • PMS induced columnar-to-equiaxed transition of columnar β-Sn dendrites. • PMS improved the elastic properties of alloys superior than that of Cu addition. • All the elastic moduli are increased as the Poisson's ratio decreased with PMS. • Pugh ratio clarified the ductility behavior of alloy samples. [ABSTRACT FROM AUTHOR]

Abstract: Sn–Cu alloys have been considered as a candidate for high temperature lead-free microelectronic solders. In the present study, the change in microstructure, attenuation and elastic behavior associated with alloying of Ag and/or In into the eutectic Sn–Cu solder alloy system have been evaluated. The study involved measurements of longitudinal and shear wave velocities, attenuation, hardness, bulk and shear moduli, Young''s and Poisson''s ratio. The results of attenuation show that a clear attenuating effect in the ternary Sn–Cu–Ag and Sn–Cu–In alloys is realized, whereas the quaternary Sn–Cu–Ag–In solder displays an obscure attenuating effect. The obscure effect is mainly attributed to the competition for In between Sn and Ag, which results in weak interface formed between intermetallic compounds (IMCs) and β-Sn matrix. Likewise, Poisson''s ratio results indicate that its value decreases with increasing the elastic moduli and ultrasonic velocities of Ag and In-containing alloys. The analyzed enhanced ductility of Sn–0.7Cu and Sn–0.7Cu–2In alloys and brittleness of Sn–0.7Cu–2Ag and Sn–0.7Cu–2Ag–2In alloys were rationalized on the basis of Poisson''s ratio and the quotient of shear modulus to bulk modulus (Pugh''s ratio). Microstructural analysis revealed that the origin of change in the elastic properties of the ternary and quaternary alloys is ascribed to smaller β-Sn dendrite grain dimensions and formation of new IMCs in the ternary and quaternary alloys. [Copyright &y& Elsevier]