Tin/Lead/Antimony Alloy - Material Information

The tin-lead-antimony alloy (Sn60/Pb39/Sb1) is a soft solder widely employed in electrical, electronic, and protective coating applications. This ternary system combines the excellent wetting and conductivity of tin, the low melting point of lead, and the strengthening and oxidation-resisting effects of antimony. Its reliability, thermal stability, and adaptability make it a standard solder composition in high-performance electronic assemblies and precision metal joining.

Material Overview

The Sn–Pb–Sb alloy system typically contains approximately 60 wt% Sn, 39 wt% Pb, and 1 wt% Sb. The eutectic temperature occurs around 183–190 °C, providing a narrow melting range ideal for smooth, consistent solder flow. Antimony serves as a microalloying element that enhances mechanical strength and suppresses the formation of coarse lead-rich phases, thus improving creep resistance and thermal fatigue life (Nur Syahirah et al., 2023). The microstructure consists of β-Sn and Pb-rich phases distributed uniformly, with trace Sb contributing to solid-solution strengthening. Electrical resistivity values range from 12–14 μΩ·cm, while thermal conductivity is around 50 W·m⁻¹·K⁻¹ (Karastojković et al., 2025). Antimony also refines the grain structure, increasing hardness without significantly elevating the melting temperature. Compared to lead-free alternatives, Sn–Pb–Sb alloys offer superior joint reliability and lower intermetallic formation rates during thermal cycling.

Applications and Advantages

This alloy is a general-purpose solder used for electrical contacts, film capacitors, and protective coatings. Its mechanical ductility and consistent wetting behavior ensure strong metallurgical bonding to copper, brass, and nickel-plated substrates. Non-ferrous soft solder variants incorporating small Sb additions exhibit improved shear strength and reduced oxidation during soldering (Dirnfeld & Ramon, 1989). The composition’s stable oxide layer provides additional corrosion resistance, allowing use in demanding industrial and laboratory conditions. Furthermore, Sn–Pb–Sb solders maintain their conductivity and joint integrity over long-term service in thermal and vibrational environments where many lead-free alternatives exhibit microcracking or delamination.

Goodfellow Availability

Goodfellow supplies high-purity Tin/Lead/Antimony (Sn60/Pb39/Sb1) alloy for research, prototyping, and production applications. Custom compositions and wire or foil forms are available to suit specific joining and coating requirements. Explore solder alloys and related materials through the Goodfellow product finder.

References

• Nur Syahirah, M. Z., Mohd Salleh, M. A. A., Abdullah, M. A. B., & Ramli, M. I. I. (2023). A short review on the influence of antimony addition to the microstructure and thermal properties of lead-free solder alloy. Archives of Metallurgy and Materials, 68(4), 145463. https://doi.org/10.24425/amm.2023.145463
• Karastojkovi?, Z., Sre?kovi?, M., Peri?, R., Stevi?, M., Ratkovi? Kova?evi?, N., & Malovi?, M. (2025). Melting temperatures and electrical conductivity of lead-free soldering alloys for filler materials. Journal of Materials Research, 12(3), 1–10. https://doi.org/10.69994/12ic25049
• Dirnfeld, S., & Ramon, J. (1989). Non-ferrous soft soldering lead-tin-antimony alloy compositions. U.S. Patent 4,871,414.
• Cao, L. (2017). Tin antimony solder alloy. Chinese Patent CN106701245A.
• Laugt, A. M., Ducolombier, A., Wary, M., & Pesci, R. (2020). Lead-free solder alloy and use of such an alloy. European Patent EP3671098A1.