Skip to main content

Microstructural Modification of Sn-0.7Cu Solder Alloys by Fe/Bi-Addition for Achieving High Mechanical Performance


In this work, we studied the Fe/Bi-bearing tin-copper (Sn-0.7Cu) solders for their microstructural and mechanical properties. The microstructure was studied using field emission scanning electron microscopy (FESEM) with a backscattered electron (BSE) detector, x-ray diffraction (XRD) analysis, and energy-dispersive x-ray spectroscopy (EDX). The microstructure study showed that Fe forms very few FeSn2 intermetallic compounds (IMCs) and does not significantly alter the microstructure of Sn-0.7Cu, whereas Bi controls the size of inter-dendritic regions containing Cu6Sn5 and Ag3Sn IMCs of the alloy, as well as significantly refines its primary β-Sn dendrites. Moreover, Bi atoms dissolve in β-Sn matrix, which in turn strengthen the solder by the Bi solid solution strengthening mechanism. Such microstructural modification leads to significant improvements in various mechanical properties of the alloy, including shear strength, impact toughness, and hardness values. Shear tests were performed with a 0.25 mm/min shear speed. The results showed that shear strength improves from 16.57 MPa to 38.36 MPa with the addition of Fe/Bi to Sn-0.7Cu, raising by about 130%. The energy absorbed during impact tests was measured for samples with the help of a Charpy impact testing machine with a 5.4 m/s impact speed. The results revealed that the addition of Fe/Bi to Sn-0.7Cu improves its impact absorbed energy by over 35%, increasing it from 7.5 J to 10.3 J. Vickers hardness tests were carried out for the test samples with a 245.2 mN applied load and 10 s dwell time. The results showed that the hardness number improves from 9.89 to 24.13 with Fe/Bi to Sn-0.7Cu, increasing by about 140%.

This is a preview of subscription content, access via your institution.


  1. 1.

    G. Zeng, S. Xue, L. Zhang, and L. Gao, J. Mater. Sci. Mater. Electron. 22, 565 (2011).

    Article  Google Scholar 

  2. 2.

    W.T. Chen, C.E. Ho, and C.R. Kao, J. Mater. Res. 17, 263 (2002).

    Article  Google Scholar 

  3. 3.

    C.M.L. Wu, D.Q. Yu, C.M.T. Law, and L. Wang, J. Electron. Mater. 31, 928 (2002).

    Article  Google Scholar 

  4. 4.

    L. Yang, Y. Zhang, J. Dai, Y. Jing, J. Ge, and N. Zhang, Mater. Des. 67, 209 (2015).

    Article  Google Scholar 

  5. 5.

    H. Xie, N. Chawla, and K. Mirpuri, J. Electron. Mater. 41, 3249 (2012).

    Article  Google Scholar 

  6. 6.

    B. Ali, Solder. Surf. Mt. Technol. 27, 69 (2015).

    Article  Google Scholar 

  7. 7.

    T. Laurila, J. Hurtig, V. Vuorinen, and J.K. Kivilahti, Microelectron. Reliab. 49, 242 (2009).

    Article  Google Scholar 

  8. 8.

    L. Yang, J. Mater. Sci. Mater. Electron. 24, 1405 (2012).

    Article  Google Scholar 

  9. 9.

    A.A. El-Daly and A.M. El-Taher, Mater. Des. 47, 607 (2013).

    Article  Google Scholar 

  10. 10.

    J. Koo, J. Chang, Y.W. Lee, S.J. Hong, K.-S. Kim, and H.M. Lee, J. Alloys Compd. 608, 126 (2014).

    Article  Google Scholar 

  11. 11.

    D.A.-A. Shnawah, S.B.M. Said, M.F.M. Sabri, I.A. Badruddin, and F.X. Che, Microelectron. Reliab. 52, 2701 (2012).

    Article  Google Scholar 

  12. 12.

    I.E. Anderson and J.L. Harringa, J. Electron. Mater. 33, 1485 (2004).

    Article  Google Scholar 

  13. 13.

    I.E. Anderson, B.A. Cook, J. Harringa, and R.L. Terpstra, J. Electron. Mater. 31, 1166 (2002).

    Article  Google Scholar 

  14. 14.

    I.D. Sousa, D.W. Henderson, L. Parry, S.K. Kang, and D.Y. Shih, in Proceedings of the 56th Electronic Components and Technology Conference (San Diego, CA: IEEE, 2006), pp. 8.

  15. 15.

    S. Choi, J.P. Lucas, K.N. Subramanian, and T.R. Bieler, J. Mater. Sci. Mater. Electron. 11, 497 (2000).

    Article  Google Scholar 

  16. 16.

    I.E. Anderson, Lead Free Electronic Solders, ed. K.V. Subramanian (Boston US: Springer, 2007), p. 55.

    Chapter  Google Scholar 

  17. 17.

    S.H. Kim and J. Yu, Scr. Mater. 69, 254 (2013).

    Article  Google Scholar 

  18. 18.

    D.A.-A. Shnawah, S.B.M. Said, M.F.M. Sabri, I.A. Badruddin, and F.X. Che, Mater. Sci. Eng. A 551, 160 (2012).

    Article  Google Scholar 

  19. 19.

    R. Pandher and R. Healey, in Proceedings of the 58th Electronic Components and Technology Conference (Lake Buena Vista, FL: IEEE, 2008), pp. 2018.

  20. 20.

    E. Hodúlová, M. Palcut, E. Lechovič, B. Šimeková, and K. Ulrich, J. Alloys Compd. 509, 7052 (2011).

    Article  Google Scholar 

  21. 21.

    R.S. Pandher, B.G. Lewis, R. Vangaveti, and B. Singh, in Proceedings of the 57th Electronic Components and Technology Conference (Sparks, NV: IEEE, 2007), pp. 669.

  22. 22.

    Y. Liu, F. Sun, H. Zhang, and Y. Wang, in Proceedings of the 6th International Forum on Strategic Technology (Harbin Heilongjiang: IEEE, 2011), pp. 72.

  23. 23.

    M. He and V.L. Acoff, J. Electron. Mater. 35, 2098 (2006).

    Article  Google Scholar 

  24. 24.

    M.H. Mahdavifard, M.F.M. Sabri, S.M. Said, D.A. Shnawah, I.A. Badruddin, and S. Rozali, J. Electron. Mater. 45, 3673 (2016).

    Article  Google Scholar 

  25. 25.

    M. He and V.L. Acoff, J. Electron. Mater. 37, 288 (2008).

    Article  Google Scholar 

  26. 26.

    B. Ali, M.F.M. Sabri, I. Jauhari, and N.L. Sukiman, Microelectron. Reliab. 63, 224 (2016).

    Article  Google Scholar 

  27. 27.

    H. Fallahi, M.S. Nurulakmal, A.F. Arezodar, and J. Abdullah, Mater. Sci. Eng. A 553, 22 (2012).

    Article  Google Scholar 

  28. 28.

    L. Yang, S. Fenglian, and Y. Miaosen, in Proceedings of the 14th International Conference on Electronic Packaging Technology (Haidian Dist Beijing: IEEE, 2013), pp. 750.

  29. 29.

    Y. Liu, F. Sun, and P. Zou, in Proceedings of the International Symposium on Advanced Packaging Materials (Xiamen: IEEE, 2011), pp. 186.

  30. 30.

    N. Zhang, Y. Shi, F. Guo, and F. Yang, J. Electron. Mater. 39, 2536 (2010).

    Article  Google Scholar 

  31. 31.

    P. Zhang, S.X. Li, and Z.F. Zhang, Mater. Sci. Eng. A 529, 62 (2011).

    Article  Google Scholar 

  32. 32.

    M. Kamal, E.S. Gouda, and L.K. Marei, Cryst. Res. Technol. 44, 1308 (2009).

    Article  Google Scholar 

Download references


The authors acknowledge the financial support granted by University of Malaya under PPP Grant Project No: PG184-2015B and under UMRG Grants Project Nos: RP014B/13AET and RP003B/13AET.

Conflict of interest

The authors declare to have no conflict of interest.

Author information



Corresponding author

Correspondence to Mohd Faizul Mohd Sabri.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Ali, B., Sabri, M.F.M., Said, S.M. et al. Microstructural Modification of Sn-0.7Cu Solder Alloys by Fe/Bi-Addition for Achieving High Mechanical Performance. Journal of Elec Materi 46, 4755–4764 (2017).

Download citation


  • Sn-0.7Cu
  • Fe/Bi additives
  • microstructure
  • shear strength
  • impact toughness
  • hardness