Synergetic effect of strain rate and electroplated Cu film for shear strength of solder/Kovar joints

  • Xiaowu HuEmail author
  • Nifa Bao
  • Zhixian Min


The effects of strain rate and electroplated Cu on the shear fracture behaviors of Sn37Pb/electroplated Cu (EPC)/Kovar solder joints were investigated after reflowing at 250 °C for 5 min. The Kovar was electroplated with 4.1 µm thick layer of Ni and 1.9 µm thick layer of Au. The copper electroplating time were 2, 5, 10 and 20 min, respectively, resulting in a different deposited thicknesses of Cu film on the Kovar substrate. The shear tests of Sn37Pb/EPC/Kovar joints were performed with different strain rates ranging from 8.3 × 10−2 to 1.6 s−1 to study the shear fracture behavior. Experimental results showed that the shear strength and failure mode of solder joints were affected by the thickness of electroplated Cu film and the applied strain rate. The shear strength of solder joint demonstrated increment at first and then decrement as the applied strain rate increased. It was observed that the shear failure mode of solder joints is well known to have experienced a transition from ductile fracture with the low strain rates (8.33 × 10−2 s−1 and 3.33 × 10− 1 s−1) to a mixed fracture with the intermediate strain rate (6.67 × 10−1 s−1) and high strain rates (1 s−1, 1.33 s−1 and 1.67 s−1). Studies in the shear properties of solder joints with electroplated Cu layer indicated that the electroplated Cu on the Kovar substrate has a significant improvement in the shear strength of solder joints. With increasing in the deposited thickness, the shear strength of solder joints increased when the deposited thickness was no more than 3.3 µm. Subsequently, the shear strength started to drop as the deposited thickness further increased.



This work was supported by the National Natural Science Foundation of China (Grant Nos. 51465039 and 51765040), Natural Science Foundation of Jiangxi Province (Grant No. 20161BAB206122).


  1. 1.
    T.L. Yang, J.J. Yu, W.L. Shih, C.H. Hsueh, C.R. Kao, Effects of silver addition on Cu-Sn microjoints for chip-stacking applications. J. Alloys Compd. 605(12), 193–198 (2014)Google Scholar
  2. 2.
    Z.X. Zhu, C.C. Li, L.L. Liao, C.K. Liu, C.R. Kao, Au-Sn bonding material for the assembly of power integrated circuit module. J. Alloys Compd. 671, 340–345 (2016)Google Scholar
  3. 3.
    T.L. Yang, J.Y. Wu, C.C. Li, S. Yang, C.R. Kao, Low temperature bonding for high temperature applications by using SnBi solders. J. Alloys Compd. 647, 681–685 (2015)Google Scholar
  4. 4.
    L.J. Yu, H.W. Yen, J.Y. Wu, J.J. Yu, C.R. Kao, Micromechanical behavior of singlecrystalline Ni3Sn4 in micro joints for chip-stacking application. Mater. Sci. Eng.: A. 685, 123–130 (2017)Google Scholar
  5. 5.
    X. Hu, W. Chen, X. Yu, Y. Li, Y. Liu, Shear strengths and fracture behaviors of Cu/Sn37Pb/Cu soldered joints subjected to different displacement rates. J. Alloys Compd. 600, 13–20 (2014)Google Scholar
  6. 6.
    Y.J. Chen, C.K. Chung, C.R. Yang, C.R. Kao, Single-joint shear strength of micro Cu pillar solder bumps with different amounts of intermetallics. Microelectron. Reliab. 53(1), 47–52 (2013)Google Scholar
  7. 7.
    Y. Wan, S. Li, X. Hu, Y. Qiu, T. Xu, Y. Li, X. Jiang, Shear strength and fracture surface analysis of Sn58Bi/Cu solder joints under a wide range of strain rates. Microelectron. Reliab. 86, 27–37 (2018)Google Scholar
  8. 8.
    X. Hu, T. Xu, L.M. Keer, Y. Li, X. Jiang, Shear strength and fracture behavior of reflowed Sn3.0Ag0.5Cu/Cu solder joints under various strain rates. J. Alloys Compd. 690, 720–729 (2017)Google Scholar
  9. 9.
    N. Bai, X. Chen, Z. Fang, Effect of strain rate and temperature on the tensile properties of tin-based lead-free solder alloys. J. Electron. Mater. 37(7), 1012–1019 (2008)Google Scholar
  10. 10.
    T.F. Song, X.S. Jiang, Z.Y. Shao, D.F. Mo, D.G. Zhu, Interracial microstructure and mechanical properties of diffusion-bonded joints of titanium TC4 (Ti-6Al-4V) and Kovar (Fe-29Ni-17Co) alloys. J. Iron Steel Res. Int. 24(10), 1023–1031 (2017)Google Scholar
  11. 11.
    W. Zhu, J. Chen, C. Jiang, C. Hao, J. Zhang, Effects of Ti thickness on microstructure and mechanical properties of alumina-Kovar joints brazed with Ag-Pd/Ti filler. Ceram. Int. 40(4), 5699–5705 (2014)Google Scholar
  12. 12.
    J. Wei, B. Deng, X. Gao, J. Yan, X. Chen, Interface structure characterization of Fe36Ni alloy with ultrasonic soldering. J. Alloys Compd. 576, 386–392 (2013)Google Scholar
  13. 13.
    J.W. Yoon, S.B. Jung, Investigation of interfacial reaction between Au-Sn solder and Kovar for hermetic sealing application. Microelectron. Eng. 84(11), 2634–2639 (2007)Google Scholar
  14. 14.
    J.W. Yoon, H.S. Chun, S.B. Jung, Liquid-state and solid-state interfacial reactions of fluxless-bonded Au-20Sn/ENIG solder joint. J. Alloys Compd. 469(1), 108–115 (2009)Google Scholar
  15. 15.
    H.J. Lin, T.H. Chuang, Intermetallic reactions in reflowed and aged Sn-9Zn solder ball grid array packages with Au/Ni/Cu and Ag/Cu pads. J. Electron. Mater. 35(1), 154–164 (2006)Google Scholar
  16. 16.
    B.L. Young, J.G. Duh, G.Y. Jang, Compound formation for electroplated Ni and electroless Ni in the under-bump metallurgy with Sn-58Bi solder during aging. J. Electron. Mater. 32(12), 1463–1473 (2003)Google Scholar
  17. 17.
    H.T. Lee, S.Y. Hu, T.F. Hong, Y.F. Chen, The shear strength and fracture behavior of Sn-Ag-xSb solder joints with Au/Ni-P/Cu UBM. J. Electron. Mater. 37(6), 867–873 (2008)Google Scholar
  18. 18.
    Z. Huber, J. Wojewoda-Budka, L. Litynska-Dobrzynska, N. Sobczak, P. Zieba, Microstructure and chemistry of the SAC/ENIG interconnections. Mater. Chem. Phys. 139(1), 276–280 (2013)Google Scholar
  19. 19.
    J.W. Yoon, B.I. Noh, S.B. Jung, Interfacial reaction between Au-Sn solder and Au/Ni-metallized Kovar. J. Mater. Sci.: Mater. Electron. 22(1), 84–90 (2011)Google Scholar
  20. 20.
    E.P. Lopez, P.T. Vianco, J.A. Rejent, Solderability testing of 95.5Sn-3.9Ag-0.6Cu solder on oxygen-free high-conductivity copper and Au-Ni-Plated kovar. J. Electron. Mater. 32(4), 254–260 (2003)Google Scholar
  21. 21.
    Q. Li, Y.C. Chan, Z. Chen, Interfacial microstructure and hardness of nickel (Ni) nanoparticle-doped tin-silver-copper (Sn-Ag-Cu) solders on immersion silver (Ag)-plated copper (Cu) substrates. J. Mater. Sci.: Mater. Electron. 25(9), 1222–1227 (2014)Google Scholar
  22. 22.
    R.B. Cinque, J.W. Morris, The effect of gold-nickel metallization microstructure on fluxless soldering. J. Electron. Mater. 23(6), 533–539 (1994)Google Scholar
  23. 23.
    W.M. Chen, S.K. Kang, C.R. Kao, Effects of Ti addition to Sn-Ag and Sn-Cu solders. J. Alloys Compd. 520(4), 244–249 (2012)Google Scholar
  24. 24.
    T.A. Powers, T.J. Singler, J.A. Clum, Role of tin content in the wetting of cu and au by tin-bismuth solders. J. Electron. Mater. 23(8), 773–778 (1994)Google Scholar
  25. 25.
    T.K. Lee, S. Zhang, C.C. Wong, A.C. Tan, Dissolution and reaction between Au and molten eutectic PbSn solder. Mater. Sci. Eng.: A 427(1–2), 136–141 (2006)Google Scholar
  26. 26.
    A. Sharif, Y.C. Chan, R.A. Islam, Effect of volume in interfacial reaction between eutectic Sn-Pb solder and Cu metallization in microelectronic packaging. Mater. Sci. Eng.: B 106(2), 120–125 (2004)Google Scholar
  27. 27.
    S.K. Kang, W.K. Choi, M.J. Yim, D.Y. Shih, Studies of the mechanical and electrical properties of lead-free solder joints. J. Electron. Mater. 31(11), 1292–1303 (2002)Google Scholar
  28. 28.
    J.W.R. Teo, Microstructure and failure mode of Sn-37Pb soldered in laser diode packages. Intermetallics 16(2), 293–298 (2008)Google Scholar
  29. 29.
    B. Lee, H. Jeon, S.J. Jeon, K.W. Kwon, H.J. Lee, A Study on the breakdown mechanism of an electroless-plated Ni(P) diffusion barrier for Cu/Sn/Cu 3D interconnect bonding structures. J. Electron. Mater. 41(1), 109–114 (2012)Google Scholar
  30. 30.
    C.Y. Liu, S.J. Wang, Prevention of spalling by the self-formed reaction barrier layer on controlled collapse chip connections under bump metallization. J. Electron. Mater. 32(1), L1–L3 (2003)Google Scholar
  31. 31.
    K.J. Puttlitz, G.T. Galyon, Impact of the ROHS Directive on high-performance electronic systems. J. Mater. Sci. 18, 347–365 (2007)Google Scholar
  32. 32.
    D.H. Jung, A. Sharma, K.H. Kim, Y.C. Choo, J.P. Jung, Effect of current density and plating time on Cu electroplating in TSV and low alpha solder bumping. J. Mater. Eng. Perform. 24(3), 1107–1115 (2015)Google Scholar
  33. 33.
    M.J. Starink, R.C. Thomson, The effect of high temperature exposure n dendritic segregation in a conventionally cast Ni based superalloy. J. Mater. Sci. 26(23), 5603–5608 (2001)Google Scholar
  34. 34.
    B.S. Lee, Y.H. Ko, J.H. Bang, C.W. Lee, Interfacial reactions and mechanical strength of Sn-3.0Ag-0.5Cu/Ni/Cu and Au-20Sn/Ni/Cu solder joints for power electronics applications. Microelectron. Reliab. 71, 119–125 (2017)Google Scholar
  35. 35.
    B. Lee, H. Jeon, K.W. Kwon, H.J. Lee, Employment of a bi-layer of Ni(P)/Cu as a diffusion barrier in a Cu/Sn/Cu bonding structure for three-dimensional interconnects. Acta Mater. 61(18), 6736–6742 (2013)Google Scholar
  36. 36.
    S.J. Wang, C.Y. Liu, Retarding growth of Ni3P crystalline layer in Ni(P) substrate by reacting with Cu-bearing Sn(Cu) solders. Scr. Mater. 49(9), 813–818 (2003)Google Scholar
  37. 37.
    J.Y. Tsai, C.W. Chang, C.E. Ho, Y.L. Lin, C.R. Kao, Microstructure evolution of gold-tin eutectic solder on Cu and Ni substrates. J. Electron. Mater. 35(1), 65–71 (2006)Google Scholar
  38. 38.
    A. Kumar, M. He, Z. Chen, Barrier properties of thin Au/Ni–P under bump metallization for Sn–3.5Ag solder. Surf. Coat. Technol. 198(1), 283–286 (2005)Google Scholar
  39. 39.
    Y. Li, K. Luo, A.B. Lim, Z. Chen, Improving the mechanical performance of Sn57.6Bi0.4Ag solder joints on Au/Ni/Cu pads during aging and electromigration through the addition of tungsten (W) nanoparticle reinforcement. Mater. Sci. Eng.: A 669, 291–303 (2016)Google Scholar
  40. 40.
    S.F. Choudhury, L. Ladani, Local shear stress-strain response of Sn-3.5Ag/Cu solder joint with high fraction of intermetallic compounds: experimental analysis. J. Alloys Compd. 680, 665–676 (2016)Google Scholar
  41. 41.
    K.E. Yazzie, H.X. Xie, J.J. Williams, N. Chawla, On the relationship between solder-controlled and intermetallic compound (IMC)-controlled fracture in Sn-based solder joints. Scr. Mater. 66(8), 586–589 (2012)Google Scholar
  42. 42.
    I. Shohji, T. Yoshida, T. Takahashi, S. Hioki, Tensile properties of Sn-Ag based lead-free solders and strain rate sensitivity. Mater. Sci. Eng.: A 366(1), 50–55 (2004)Google Scholar
  43. 43.
    H. Fei, K. Yazzie, N. Chawla, H. Jiang, Modeling fracture of Sn-Rich (Pb-Free) solder joints under mechanical shock conditions. J. Electron. Mater. 41(8), 2089–2099 (2012)Google Scholar
  44. 44.
    K.E. Yazzie, H.E. Fei, H. Jiang, N. Chawla, Rate-dependent behavior of Sn alloy-Cu couples: effects of microstructure and composition on mechanical shock resistance. Acta Mater. 60(10), 4336–4348 (2012)Google Scholar
  45. 45.
    T. An, F. Qin, Effects of the intermetallic compound microstructure on the tensile behavior of Sn3.0Ag0.5Cu/Cu solder joint under various strain rates. Microelectron. Reliab. 54(5), 932–938 (2014)Google Scholar
  46. 46.
    W. Chen, S. Xue, H. Wang, J. Wang, Z. Han, Investigation on properties of Ga to Sn-9Zn lead-free solder. J. Mater. Sci.: Mater. Electron. 21(5), 496–502 (2010)Google Scholar
  47. 47.
    H.T. Lee, H.S. Lin, C.S. Lee, P.W. Chen, Reliability of Sn–Ag–Sb lead-free solder joints. Mater. Sci. Eng.: A 407(1), 36–44 (2005)Google Scholar
  48. 48.
    X. Hu, Y. Li, Y. Liu, Z. Min, Microstructure and shear strength of Sn37Pb/Cu solder joints subjected to isothermal aging. Microelectron. Reliab. 54(8), 1575–1582 (2014)Google Scholar
  49. 49.
    F. Lang, H. Tanaka, O. Munegata, T. Taguchi, T. Narita, The effect of strain rate and temperature on the tensile properties of Sn-3.5Ag solder. Mater. Charact. 54(3), 223–229 (2005)Google Scholar

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© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Key Lab for Robot & Welding Automation of Jiangxi Province, Mechanical & Electrical Engineering SchoolNanchang UniversityNanchangChina
  2. 2.China Electronics Technology Group CorporationHefeiChina

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