Impact of 5% NaCl Salt Spray Pretreatment on the Long-Term Reliability of Wafer-Level Packages with Sn-Pb and Sn-Ag-Cu Solder Interconnects

  • Bo Liu
  • Tae-Kyu Lee
  • Kuo-Chuan Liu


Understanding the sensitivity of Pb-free solder joint reliability to various environmental conditions, such as corrosive gases, low temperatures, and high-humidity environments, is a critical topic in the deployment of Pb-free products in various markets and applications. The work reported herein concerns the impact of a marine environment on Sn-Pb and Sn-Ag-Cu interconnects. Both Sn-Pb and Sn-Ag-Cu solder alloy wafer-level packages, with and without pretreatment by 5% NaCl salt spray, were thermally cycled to failure. The salt spray test did not reduce the characteristic lifetime of the Sn-Pb solder joints, but it did reduce the lifetime of the Sn-Ag-Cu solder joints by over 43%. Although both materials showed strong resistance to corrosion, the localized nature of the corroded area at critical locations in the solder joint caused significant degradation in the Sn-Ag-Cu solder joints. The mechanisms leading to these results as well as the extent, microstructural evolution, and dependency of the solder alloy degradation are discussed.


Pb-free solder salt spray corrosion chlorine thermal fatigue 


  1. 1.
    D. Frear, H. Morgan, and J.H. Lau, eds., The Mechanics of Solder Alloy Interconnects (New York: Van Nostrand Reinhold, 1994).Google Scholar
  2. 2.
    H.K. Kim and K.N. Tu, Phys. Rev. B 53, 16027 (1996).CrossRefGoogle Scholar
  3. 3.
    H.G. Song, J.W. Morris Jr., and F. Hua, JOM 56, 30 (2002).CrossRefGoogle Scholar
  4. 4.
    F. Song and R. Lee, Proceeding of the 56th Electronic Components and Technology Conference, San Diego, California, May (2006).Google Scholar
  5. 5.
    M. Abtew and G. Selvaduray, Mater. Sci. Eng. R 27, 95 (2000).CrossRefGoogle Scholar
  6. 6.
    A.J. Hale and H.S. Fosteh, J. Soc. Chem. Ind. 9, 2371 (1915).Google Scholar
  7. 7.
    A. Jermstad and A. Gaule, J. Inst. Met. 13, 1370 (1919).Google Scholar
  8. 8.
    B.Y. Wu, Y.C. Chan, and M.O. Alam, J. Mater. Res. 21, 62 (2006).CrossRefGoogle Scholar
  9. 9.
    J.Y. Jung, S.B. Lee, H.Y. Lee, Y.C. Joo, and Y.B. Park, J. Electron. Mater. 37, 1111 (2008).CrossRefGoogle Scholar
  10. 10.
    D. Li, P. Conway, and C. Liu, Corros. Sci. 50, 995 (2008).CrossRefGoogle Scholar
  11. 11.
    R.P. Frankenthal and D.J. Siconolfi, Corros. Sci. 21, 479 (1981).CrossRefGoogle Scholar
  12. 12.
    T. Farrell, Met. Sci. 10, 87 (1976).CrossRefGoogle Scholar
  13. 13.
    D.Q. Yu, W. Jillek, and E. Schmitt, Mater. Electron. 17, 219 (2006).CrossRefGoogle Scholar
  14. 14.
    ASTM B117-09, Standard Practice for Operating Salt Spray (Fog) Apparatus.Google Scholar
  15. 15.
    T.-K. Lee, H. Ma, K.-C. Liu, and J. Xue, J. Electron. Mater. 39, 2564 (2010).CrossRefGoogle Scholar
  16. 16.
    T.-K. Lee, K.-C. Liu, and T.R. Bieler, J. Electron. Mater. 38, 2685 (2009).CrossRefGoogle Scholar
  17. 17.
    M. Mori, K. Miura, T. Sasaki, and T. Ohtsuka, Corros. Sci. 44, 887 (2002).CrossRefGoogle Scholar
  18. 18.
    U.S. Mohanty and K. Lin, Corros. Sci. 50, 2437 (2008).CrossRefGoogle Scholar
  19. 19.
    T.-K. Lee, B. Liu, B. Zhou, T. R. Bieler, and K.-C. Liu, J. Electron. Mater. 40. doi: 10.1007/s11664-011-1654-5.

Copyright information

© TMS 2011

Authors and Affiliations

  1. 1.Component Quality and Technology GroupCisco Systems, Inc.San JoseUSA

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