Elastic properties and thermal behavior of Sn–Zn based lead-free solder alloys

• Published in: Journal of alloys and compounds 2010-09, Vol.505 (2), p.793-800
• Main Authors: El-Daly, A.A., Hammad, A.E.
• Format: Article
• Language: English
• Subjects: Alloying; Alloys; Condensed matter: structure, mechanical and thermal properties; Elastic constants; Elastic properties; Elasticity, elastic constants; Exact sciences and technology; Lead-free solder; Mechanical and acoustical properties; Mechanical and acoustical properties of condensed matter; Mechanical properties of solids; Microstructure; Phases; Physical properties of thin films, nonelectronic; Physics; Poissons ratio; Silver; Sn–Zn alloy; Solders; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thermal properties; Thermal properties of condensed matter; Tin base alloys; Tribology and hardness; Ultrasonic velocity
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.06.142

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 4 MHz 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.