Size effect on interface reaction of Sn–xCu/Cu solder joints during multiple reflows

  • Ru Huang
  • Haoran MaEmail author
  • Shengyan Shang
  • Anil Kunwar
  • Yunpeng Wang
  • Haitao Ma


At present, electronic products are developing in the direction of miniaturization and integration, which leads to the downsizing of solder bump in the packaging process. Moreover, micro solder bumps often require undergoing multiple reflow processes due to the improvement of packaging technology, which has a great influence on interface reaction. Hence, it is necessary to study the effects of solder composition, bump size and reflow cycle on interfacial reaction between solder alloys and Cu substrates. In this experiment, Sn–xCu (x = 0, 0.7, 2.0 wt%) alloys with diameter of 200 µm, 500 µm, and 800 µm were soldered to Cu substrates at 250 °C for 1 min, and then reflowed 20 cycles totally. The size effect of micro solder joints on the growth of IMC after multiple reflows was analyzed. At the same time, the impact of Cu concentration inside the bulk solder on the interfacial reaction during multiple reflows was explored. This experiment finds that the diameter of IMC grains increases with the decrease of solder ball diameter after one reflow cycle, and a significant size effect occurs in Sn/Cu solder bump. As the number of reflow cycle increases, the size effect on interface reaction is more pronounced. The most direct kinetic factor of this phenomenon is that the average Cu concentration in the small-sized solder ball rises faster than the others. When the number of reflow cycle reach to nine times, the lateral growth rate of IMC grains begins to surpass the longitudinal growth rate, and the morphology of IMC grains becomes flat. This phenomenon is especially evident in the small-sized solder ball. Moreover, the addition of Cu element in solder promotes ripening reaction resulting in the lateral growth of IMC. Cu6Sn5 micro particles appearing at the Sn/Cu, Sn–0.7Cu/Cu interface hinder the grain boundary motion and inhibit the lateral annexation of IMC grains, thereby suppressing the lateral growth of IMC.



This work was supported by the National Natural Science Foundation of China (Grant Nos. 51871040 and 51571049) and “Research Fund for International Young Scientists” of National Natural Science Foundation of China (Grant No. 51750110504).


  1. 1.
    A.S.M.A. Haseeb, Y.M. Leong, M.M. Arafat, Intermetallics 54, 86–94 (2014)CrossRefGoogle Scholar
  2. 2.
    L. Liu, Z. Chen, C. Liu et al., Intermetallics 76, 10–17 (2016)CrossRefGoogle Scholar
  3. 3.
    C.W. Chen, T.C. Chiu, Y.T. Chiu et al., Intermetallics 85, 117–124 (2017)CrossRefGoogle Scholar
  4. 4.
    S.S. Ha, J.K. Jang, S.O. Ha et al., Microelectron. Eng. 87(3), 517–521 (2010)CrossRefGoogle Scholar
  5. 5.
    J.H. Lau, Microelectron. Ind. 28(2), 8–22 (2011)CrossRefGoogle Scholar
  6. 6.
    C.C. Chang, Y.W. Lin, Y.W. Wang et al., J. Alloys Compd. 492(1–2), 99–104 (2010)CrossRefGoogle Scholar
  7. 7.
    H.T. Ma, H.R. Ma, A. Kunwar et al., J. Mater. Sci.: Mater. Electron. 29(1), 602–613 (2018)Google Scholar
  8. 8.
    W.K. Choi, H.M. Lee, J. Electron. Mater. 29(10), 1207–1213 (2000)CrossRefGoogle Scholar
  9. 9.
    H. Ma, A. Kunwar, R. Huang et al., Intermetallics 90, 90–96 (2017)CrossRefGoogle Scholar
  10. 10.
    L. Gu, L. Qu, H. Ma et al., ICEPT, 1–4 (2011).
  11. 11.
    H.K. Kim, K.N. Tu, Phys. Rev. B 53(23), 16027 (1996)CrossRefGoogle Scholar
  12. 12.
    L. Qu, H.T. Ma, H.J. Zhao et al., Appl. Surf. Sci. 305(12), 133–138 (2014)CrossRefGoogle Scholar
  13. 13.
    S. Li, Y. Du, L. Qu et al., ICEPT, 937–939 (2014)Google Scholar
  14. 14.
    M.L. Huang, F. Yang, N. Zhao et al., Mater. Lett. 139, 42–45 (2015)CrossRefGoogle Scholar
  15. 15.
    L. Qu, N. Zhao, H.J. Zhao et al., Scripta Mater. 72–73(2), 43–46 (2014)CrossRefGoogle Scholar
  16. 16.
    H. Ma, A. Kunwar, Z. Liu et al., J. Mater. Sci.: Mater Electron. 29(6), 4383–4390 (2018)Google Scholar
  17. 17.
    Y. Zhu, F. Sun, Solder. Surf. Mt. Technol. 29(2), 85–91 (2017)CrossRefGoogle Scholar
  18. 18.
    C.M.L. Wu, M.L. Huang, J. Electron. Mater. 31(7), 828–828 (2002)CrossRefGoogle Scholar
  19. 19.
    X.P. Li, J.M. Xia, M.B. Zhou et al., J. Electron. Mater. 40(12), 2425 (2011)CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  1. 1.School of Materials Science and EngineeringDalian University of TechnologyDalianChina
  2. 2.School of MicroelectronicsDalian University of TechnologyDalianChina
  3. 3.Department of Materials EngineeringKU LeuvenHeverleeBelgium

Personalised recommendations