Electrical and thermal characterization of lead-free Sn-Zn-Cu solder alloys

Abstract

Sn-Zn-Cu alloys have emerged as promising candidates to replace conventional lead-containing solder systems due to their environmentally favorable characteristics. In this study, four different phases within the Sn-Zn-Cu alloy system were investigated in terms of their thermal and electrical properties. Temperature-dependent thermal conductivity was measured using the linear heat-flow method, and the corresponding conductivity coefficients were derived from the collected data. Differential Scanning Calorimetry (DSC) was employed to determine melting temperatures, enthalpies of fusion, and specific heat differences between the liquid and solid phases. Electrical conductivity values were obtained using the four-point probe technique. Compared to commonly used Pb-free solder systems reported in the literature, the investigated Sn–Zn–Cu alloys exhibit a favorable combination of lower melting temperatures, stable thermal behavior, and controlled electrical conductivity, which are critical for ensuring reliable heat dissipation and electrical performance in advanced electronic and energy-related soldering applications. These characteristics highlight the potential of Sn–Zn–Cu alloys as cost-effective and high-performance alternatives to conventional Pb-free solders.

Keywords

• Heat transfer
• Zinc compounds
• Thermal properties
• Electrical conductivity

References

1. [1] Suganuma K. Advances in lead-free electronics soldering. Curr Opin Solid State Mater Sci 2001; 5: 55-64.
2. [2] Rashidi R, Naffakh-Moosavy H. Metallurgical, physical, mechanical and oxidation behavior of lead-free chromium dissolved Sn-Cu-Bi solders. J Mater Res Technol 2021; 13: 1805-1825.
3. [3] Abtew M, Selvaduray G. Lead-free solders in microelectronics. Mater Sci Eng R Rep 2000; 27: 95-141.
4. [4] Xing SF, Qiu X. Thermal properties, electrochemical behavior, and microstructure of Zn-5Sn-2Cu-1.5Bi-xRE high-temperature solder. J Mater Eng Perform 2015; 24: 1679-1686.
5. [5] Li Y, Chen C, Yi R, Ouyang Y. Special brazing and soldering: A review. J Manuf Process 2020; 60: 608-635.
6. [6] Xing F, Qiu XM, Li YD. Effects of Sn element on microstructure and properties of Zn-Cu-Bi-Sn high-temperature solder. Trans Nonferrous Met Soc China 2015; 25: 879-884.
7. [7] Lee BJ, Hwang NM, Lee HM. Prediction of interface reaction products between Cu and various solder alloys by thermodynamic calculation. Acta Mater 1997; 45: 1867-1874.
8. [8] McCormack M, Jin S, Kammlott GW, Chen HS. New high-strength Pb-free solder alloys based on the Sn-Ag-Zn system. Appl Phys Lett 1993; 63: 15-17.

9. [9] Ghosh G, Loomans M, Fine ME. An investigation of phase equilibria of the Bi-Sb-Sn system. J Electron Mater 1994; 23: 619-624.
10. [10] McCormack M, Jin S. New lead-free solders. J Electron Mater 1994; 23: 635-640.
11. [11] McCormack M, Jin S, Chen HS, Machusak DA. New lead-free Sn-Zn-In solder alloys. J Electron Mater 1994; 23: 687-690.
12. [12] Kattner UR, Boettinger WJ. On the Sn-Bi-Ag ternary phase diagram. J Electron Mater 1994; 23: 603-610.
13. [13] Loomans ME, Vaynman S, Ghosh G, Fine ME. Investigation of multi-component lead-free solders. J Electron Mater 1994; 23: 741-746.
14. [14] Artaki I, Jackson AM, Vianco PT. Evaluation of lead-free solder joints in electronic assemblies. J Electron Mater 1994; 23: 757-764.
15. [15] Kang SK, Sarkhel AK. Lead (Pb)-free solders for electronic packaging. J Electron Mater 1994; 23: 701-707.
16. [16] McCormack M, Jin S. Improved mechanical properties in new Pb-free solder alloys. J Electron Mater 1994; 23: 715-720.
17. [17] Wood EP, Nimmo KL. In search of new lead-free electronic solders. J Electron Mater 1994; 23: 709-713.
18. [18] Urasoğlu MG, İlbaş M. Attaining sustainable energy transition or facing costs of delayed action: A case of Turkey. Int J Energy Stud 2020; 5: 133-144.
19. [19] Dele-Afolabi TT, Ansari MNM, Azmah Hanim MA, Oyekanmi AA, Ojo-Kupoluyi OJ, Atiqah A. Recent advances in Sn-based lead-free solder interconnects for microelectronics packaging: Materials and technologies. J Mater Res Technol 2013; 25: 4231-4263.
20. [20] Choi S, Lim S, Hanifah MMM, Matteini P, Wan Yusof WY, Hwang B. An introductory overview of various typical lead-free solders for TSV technology. Inorganics 2025; 13: 86.
21. [21] Sobolewski M, Wojewoda-Budka J, Sobczak N, Janusz-Skuza M, Bigos A, Terlicka S, Korneva A, Szlezynger M, Adamek Z, Wierzbicka-Miernik A. Green electronics soldering by application of third generation lead-free solder alloys: Studies on their wettability and interface microstructure formed with copper. J Mater Eng Perform 2025; 34: 28134-28144.
22. [22] Puttlitz KJ, Stalter KA. Handbook of lead-free solder technology for microelectronic assemblies. IMB Corporation, East Fishkill, New York, 2004.
23. [23] Yang W, Messler RW Jr, Felton LE. Microstructure evolution of eutectic Sn-Ag solder joints. J Electron Mater 1994; 23: 765-772.
24. [24] Chou CY, Chen SW. Phase equilibria of the Sn-Zn-Cu ternary system. Acta Mater 2006; 54: 2393-2400.
25. [25] Aksöz S, Ata Esener P, Öztürk E, Maraşlı N. Effects of Bi content on thermal, microstructure and mechanical properties of Sn-Bi-In-Zn solder alloy systems. J Mater Sci Mater Electron 2022; 33: 11-26.
26. [26] Gündüz M, Hunt JD. The measurement of solid-liquid surface energies in the Al-Cu, Al-Si and Pb-Sn systems. Acta Metall 1985; 33: 1651-1672.
27. [27] Maraşlı N, Hunt JD. Solid-liquid surface energies in the AlCuAl2, AlNiAl3 and AlTi systems. Acta Metall 1996; 44: 1085-1096.
28. [28] Rudnev V, Loveless D, Cook R, Black M. Handbook of induction heating. Markel Dekker Inc, New York, 2003.
29. [29] Meydaneri F, Saatçi B, Arı M. Thermo-electrical characterization of lead-cadmium (Pb-Cd) alloys. Int J Phys Sci 2012; 7: 6210-6221.
30. [30] Onaran K. Material science. Science Technique Publisher, İstanbul, 2009.
31. [31] Ata Esener P, Bayram Ü, Öztürk E, Aksöz S, Maraşlı N. Electrical and thermal conductivity and phonon contribution to the thermal conductivity in the Bi-In system. J Therm Sci Technol 2020; 40: 367-378.
32. [32] Valder LB. Resistivity measurements on germanium for transistors. Proc IRE 1954; 42: 420-427.
33. [33] Ocak Y, Akbulut S, Keşlioğlu K, Maraşlı N. Solid-liquid interfacial energy of aminomethylpropanediol. J Phys D Appl Phys 2008; 41: 065309.
34. [34] Ata Esener P, Altıntas Y, Bayram Ü, Öztürk E, Maraşlı N, Aksöz S. Effect of Sn contents on thermodynamic, microstructure and mechanical properties in the Zn90-Bi10 and Bi88-Zn12 based ternary alloys. J Mater Sci Mater Electron 2019; 30: 3678-3691.
35. [35] Akbulut S, Ocak Y, Keşlioğlu K, Maraşlı N. Thermal conductivities of solid and liquid phases for neopentylglycol, aminomethylpropanediol and their binary alloy. J Phys Chem Solids 2009; 70: 72-78.
36. [36] Karadağ SB, Öztürk E, Aksöz S, Maraşlı N. Thermophysical properties of NPG solid solution in the NPG-SCN organic system. Int J Mater Res 2018; 109: 219-224.
37. [37] Altıntas Y, Kaygısız Y, Öztürk E, Aksöz S, Keşlioğlu K, Maraşlı N. Measurements of electrical and thermal conductivity variations with temperature and phonon component of the thermal conductivity in Sn-Cd-Sb, Sn-In-Cu, Sn-Ag-Bi and Sn-Bi-Zn alloys. Int J Therm Sci 2016; 100: 1-9.
38. [38] Öztürk E, Aksöz S, Keşlioğlu K, Maraşlı N. Measurement of thermal conductivity variation with temperature for Sn-20 wt.% In based lead-free ternary solders. Thermochim Acta 2013; 554: 63-70.
39. [39] Touloukian YS, Powell RW, Ho CY, Klemens PG. Thermal conductivity metallic elements and alloys, vol 1. New York-Washington, 1970.
40. [40] Kittel C. Introduction to solid state physics, 6th ed. John Wiley and Sons, 1965.
41. [41] Gill P, Moghadam TT, Ranjbar B. Differential scanning calorimetry techniques: Applications in biology and nanoscience. J Biomol Tech 2010; 21: 167-193.
42. [42] Powers JM. Department of aerospace and mechanical engineering, University of Notre Dame, USA, 2010.
43. [43] Mhiaoui S, Sar F, Gasser JG. Electrical and thermal conductivities and thermopower of some lead-free solders (LFS) in the liquid and solid state. J Non-Cryst Solids 2007; 353: 3628-3632.
44. [44] Srivastana JP. Elements of solid-state physics. Prentice Hall of India, 2006.