Skip to main content Accessibility help

Microstructural evolution and change in macroscopic physical properties of microscale flip chip Cu/Sn58Bi/Cu joints under the coupling effect of electric current stressing and elastic stress

  • Shui-Bao Liang (a1), Chang-Bo Ke (a1), Cheng Wei (a2), Jia-Qiang Huang (a1), Min-Bo Zhou (a1) and Xin-Ping Zhang (a1)...


Severe phase coarsening and separation in Sn–Bi alloys have brought increasing reliability concern in microelectronic packages. In this study, a phase field model is developed to simulate the microstructural evolution and evaluate the change in macroscopic physical properties of the flip chip Cu/Sn58Bi/Cu joint under the conditions of isothermal aging, as well as the coupled loads of elastic stress and electric current stressing. Results show that large-sized Bi-rich phase particles grow up at the expense of small-sized ones. Under the coupled loads, Bi atoms migrate along the electron flow direction, consequently Bi-rich phase segregates to form a Bi-rich phase layer at the anode. The current crowding ratio in the solder decreases rapidly first and then fluctuates slightly with time. Current density and von Mises stress exhibit inhomogeneous distribution, and both of them are higher in the Sn-rich phase than in the Bi-rich phase. Electric current transfers through the Sn-rich phase and detours the Bi-rich phase. As time proceeds, the resistance of the solder joint increases, and the average von Mises stress of the solder joint decreases. The Bi-rich phase coarsens much faster under the coupled loads than under the conditions of isothermal aging.


Corresponding author

a)Address all correspondence to this author. e-mail:


Hide All
1.Kang, S.K. and Sarkhel, A.K.: Lead (Pb)-free solders for electronic packaging. J. Electron. Mater. 23, 701707 (1994).
2.Wang, F., Huang, Y., and Du, C.: Mechanical properties of SnBi–SnAgCu composition mixed solder joints using bending test. Mater. Sci. Eng., A 668, 224233 (2016).
3.Huang, J.Q., Zhou, M.B., and Zhang, X.P.: Interfacial reactions and microstructural evolution of BGA structure Cu/Sn3.0Ag0.5Cu/Sn58Bi/Cu mixed assembly joints during isothermal aging. In Proceedings of 17th International Conference on Electronic Packaging Technology, K.Y. Bi, S. Liu, and S.J. Zhou, eds. (IEEE, Piscataway, New Jersey, 2016); pp. 968973.
4.Hua, F., Mei, Z., and Glazer, J.: Eutectic Sn–Bi as an alternative to Pb-free solders. In Proceedings of 48th Electronic Components and Technology Conference, J. Billigmeier, ed. (IEEE, Piscataway, New Jersey, 1998); pp. 227283.
5.Kotadia, H.R., Howes, P.D., and Mannan, S.H.: A review: On the development of low melting temperature Pb-free solders. Microelectron. Reliab. 54, 12531273 (2014).
6.Mokhtari, O. and Nishikawa, H.: Correlation between microstructure and mechanical properties of Sn–Bi–X solders. Mater. Sci. Eng., A 651, 831839 (2016).
7.Cheng, S., Huang, C.M., and Pecht, M.: A review of lead-free solders for electronics applications. Microelectron. Reliab. 75, 7795 (2017).
8.Tu, K.N.: Recent advances on electromigration in very-large-scale-integration of interconnects. J. Appl. Phys. 94, 54515473 (2003).
9.Yeh, E.C.C., Choi, W.J., Tu, K.N., Elenius, P., and Balkan, H.: Current-crowding-induced electromigration failure in flip chip solder joints. Appl. Phys. Lett. 80, 580582 (2002).
10.Liu, C.Y., Chih, C., Liao, C.N., and Tu, K.N.: Microstructure-electromigration correlation in a thin stripe of eutectic SnPb solder stressed between Cu electrodes. Appl. Phys. Lett. 75, 5860 (1999).
11.Gan, H. and Tu, K.N.: Polarity effect of electromigration on kinetics of intermetallic compound formation in Pb-free solder V-groove samples. J. Appl. Phys. 97, 063514 (2005).
12.Yang, Q.L. and Shang, J.K.: Interfacial segregation of Bi during current stressing of Sn–Bi/Cu solder interconnect. J. Electron. Mater. 34, 13631367 (2005).
13.Tsai, C.M., Lin, Y.L., Tsai, J.Y., Lai, Y.S., and Kao, C.R.: Local melting induced by electromigration in flip-chip solder joints. J. Electron. Mater. 35, 10051009 (2006).
14.Liu, P.L. and Shang, J.K.: Interfacial embrittlement by bismuth segregation in copper/tin–bismuth Pb-free solder interconnect. J. Mater. Res. 16, 16511659 (2001).
15.Chen, C.M., Chen, L.T., and Lin, Y.S.: Electromigration-induced Bi segregation in eutectic SnBi solder joint. J. Electron. Mater. 36, 168172 (2007).
16.Chen, C. and Huang, C.: Atomic migration in eutectic SnBi solder alloys due to current stressing. J. Mater. Res. 23, 10511056 (2008).
17.Xu, G., Guo, F., Wang, X., Xia, Z., Lei, Y., Shi, Y., and Li, X.: Retarding the electromigration effects to the eutectic SnBi solder joints by micro-sized Ni-particles reinforcement approach. J. Alloys Compd. 509, 878884 (2011).
18.Liu, P.L. and Shang, J.K.: Segregant-induced cavitation of Sn/Cu reactive interface. Scr. Mater. 53, 631634 (2005).
19.Shang, P.J., Liu, Z.Q., Li, D.X., and Shang, J.K.: Bi-induced voids at the Cu3Sn/Cu interface in eutectic SnBi/Cu solder joints. Scr. Mater. 58, 409412 (2008).
20.Liu, P.L. and Shang, J.K.: Fracture of SnBi/Ni(P) interfaces. J. Mater. Res. 20, 818826 (2005).
21.Gu, X. and Chan, Y.C.: Electromigration in line-type Cu/Sn–Bi/Cu solder joints. J. Electron. Mater. 37, 17211726 (2008).
22.Zou, H.F., Zhang, Q.K., and Zhang, Z.F.: Eliminating interfacial segregation and embrittlement of bismuth in SnBi/Cu joint by alloying Cu substrate. Scr. Mater. 61, 308311 (2009).
23.Zou, H.F., Zhang, Q.K., and Zhang, Z.F.: Interfacial microstructure and mechanical properties of SnBi/Cu joints by alloying Cu substrate. Mater. Sci. Eng., A 532, 167177 (2012).
24.Chen, L. and Chen, C.: Electromigration study in the eutectic SnBi solder joint on the Ni/Au metallization. J. Mater. Res. 21, 962969 (2006).
25.Chen, C.M., Huang, C.C., Liao, C.N., and Liou, K.M.: Effects of copper doping on microstructural evolution in eutectic SnBi solder stripes under annealing and current stressing. J. Electron. Mater. 36, 760765 (2007).
26.He, H., Xu, G., and Guo, F.: Electromigration-induced Bi-rich whisker growth in Cu/Sn–58Bi/Cu solder joints. J. Mater. Sci. 45, 334340 (2010).
27.Zuo, Y., Ma, L., Liu, S., Shu, Y., and Guo, F.: Evolution of microstructure across eutectic Sn–Bi solder joints under simultaneous thermal cycling and current stressing. J. Electron. Mater. 44, 597603 (2015).
28.Ma, L., Zuo, Y., Liu, S., Guo, F., and Wang, X.: The failure modelsof Sn-based solder joints under coupling effects of electromigration and thermal cycling. J. Appl. Phys. 113, 044904 (2013).
29.Ubachs, R.L.J.M., Schreurs, P.J.G., and Geers, M.G.D.: A nonlocal diffuse interface model for microstructure evolution of tin–lead solder. J. Mech. Phys. Solids 52, 17631792 (2004).
30.Anders, D., Hesch, C., and Weinberg, K.: Computational modeling of phase separation and coarsening in solder alloy. Int. J. Solids Struct. 49, 15571572 (2012).
31.Liang, S.B., Ke, C.B., Huang, J.Q., Zhou, M.B., and Zhang, X.P.: Phase field simulation of microstructural evolution and thermomigration-induced phase segregation in Cu/Sn58Bi/Cu interconnects under isothermal aging and temperaturegradient. Microelectron. Reliab. 92, 111 (2019).
32.Jin, S. and McCormack, M.: Dispersoid additions to a Pb-free solder for suppression of microstructural coarsening. J. Electron. Mater. 23, 735739 (1994).
33.Chen, C., Ho, C.E., Lin, A.H., Luo, G.L., and Kao, C.R.: Long-term aging study on the solid-state reaction between 58Bi42Sn solder and Ni substrate. J. Electron. Mater. 29, 12001206 (2000).
34.Miao, H.W. and Duh, J.G.: Microstructure evolution in Sn–Bi and Sn–Bi–Cu solder joints under thermal aging. Mater. Chem. Phys. 71, 255271 (2001).
35.Gu, Y. and Nakamura, T.: Interfacial delamination and fatigue life estimation of 3D solder bumps in flip-chip packages. Microelectron. Reliab. 44, 471483 (2004).
36.Mei, Z. and Morris, J.W.: Characterization of eutectic Sn–Bi solder joints. J. Electron. Mater. 21, 599607 (1992).
37.He, H., Zhao, H., Guo, F., and Xu, G.: Bi layer formation at the anode interface in Cu/Sn–58Bi/Cu solder joints with high current density. J. Mater. Sci. Technol. 28, 4652 (2012).
38.Xu, G., He, H., and Guo, F.: Temperature-dependent phase segregation in Cu/42Sn–58Bi/Cu reaction couples under high current density. J. Electron. Mater. 38, 273283 (2009).
39.Chou, C.K., Chen, C.A., Liang, S.W., and Chen, C.: Redistribution of Pb-rich phase during electromigration in eutectic SnPb solder stripes. J. Appl. Phys. 99, 054502 (2006).
40.Dreyer, W. and Müller, W.H.: Modeling diffusional coarsening in eutectic tin/lead solders: A quantitative approach. Int. J. Solids Struct. 38, 14331458 (2001).
41.Li, L. and Müller, W.H.: Computer modeling of the coarsening process in tin–lead solders. Comput. Mater. Sci. 21, 159184 (2001).
42.Sun, J., Xu, G.C., Guo, F., Xia, Z.D., Lei, Y.P., Shi, Y.W., Li, X.Y., and Wang, X.T.: Effects of electromigration on resistance changes in eutectic SnBi solder joints. J. Mater. Sci. 46, 35443549 (2011).
43.Zhang, Q.K., Zou, H.F., and Zhang, Z.F.: Influences of substrate alloying and reflow temperature on Bi segregation behaviors at Sn–Bi/Cu interface. J. Electron. Mater. 40, 23202328 (2011).
44.Choi, W.J., Yeh, E.C.C., and Tu, K.N.: Mean-time-to-failure study of flip chip solder joints on Cu/Ni(V)/Al thin-film under-bump-metallization. J. Appl. Phys. 94, 56655671 (2003).
45.Ouyang, F.Y., Tu, K.N., and Lai, Y.S.: Effect of electromigration induced joule heating and strain on microstructural recrystallization in eutectic SnPb flip chip solder joints. Mater. Chem. Phys. 136, 210218 (2012).
46.Gu, X. and Chan, Y.C.: Thermomigration and electromigration in Sn58Bi solder joints. J. Appl. Phys. 105, 093537 (2009).
47.Yue, W., Qin, H.B., Zhou, M.B., Ma, X., and Zhang, X.P.: Electromigration induced microstructure evolution and damage in asymmetric Cu/Sn–58Bi/Cu solder interconnect under current stressing. Trans. Nonferrous Met. Soc. China 24, 16191628 (2014).
48.Yamanaka, K., Tsukada, Y., and Suganuma, K.: Solder electromigration in Cu/In/Cu flip chip joint system. J. Alloys Compd. 437, 186190 (2007).
49.Jen, M.H.R., Liu, L.C., and Lai, Y.S.: Electromigration test on void formation and failure mechanism of FCBGA lead-free solder joints. IEEE Trans. Compon. Packag. Technol. 32, 7988 (2009).
50.Chang, Y.W., Cheng, Y., Xu, F., Helfen, L., Tian, T., Di Michiel, M., Chen, C., Tu, K.N., and Baumbach, T.: Study of electromigration-induced formation of discrete voids in flip-chip solder joints by in situ 3D laminography observation and finite-element modeling. Acta Mater. 117, 100110 (2016).
51.Guo, F., Xu, G.C., Sun, J., Xia, Z.D., Lei, Y.P., Shi, Y.W., and Li, X.Y.: Resistance changes in eutectic Sn–Bi solder joints during electromigration. J. Electron. Mater. 38, 27562761 (2009).
52.Ohtani, H. and Ishida, K.: A thermodynamic study of the phase equilibria in the Bi–Sn–Sb system. J. Electron. Mater. 23, 747755 (1994).
53.Park, M.S. and Arróyave, R.: Early stages of intermetallic compound formation and growth during lead-free soldering. Acta Mater. 58, 49004910 (2010).
54.Felton, L.E., Raeder, C.H., and Knorr, D.B.: The properties of tin-bismuth alloy solders. JOM 45, 2832 (1993).
55.Raeder, C.H., Felton, L.E., Tanzi, V.A., and Knorr, D.B.: The effect of aging on microstructure, room temperature deformation, and fracture of Sn–Bi/Cu solder joints. J. Electron. Mater. 23, 611617 (1994).
56.Mostofizadeh, M., Pippola, J., and Frisk, L.: Shear strength of eutectic Sn–Bi lead-free solders after corrosion testing and thermal aging. J. Electron. Mater. 43, 13351346 (2014).
57.Wang, F., Liu, L., Li, D., and Wu, M.: Electromigration behaviors in Sn–58Bi solder joints under different current densities and temperatures. J. Mater. Sci.: Mater. Electron. 29, 2115721169 (2018).
58.Ye, H., Basaran, C., and Hopkins, D.C.: Pb phase coarsening in eutectic Pb/Sn flip chip solder joints under electric current stressing. Int. J. Solids Struct. 41, 27432755 (2004).
59.Wu, B.Y., Alam, M.O., Chan, Y.C., and Zhong, H.W.: Joule heating enhanced phase coarsening in Sn37Pb and Sn3.5Ag0.5Cu solder joints during current stressing. J. Electron. Mater. 37, 469476 (2008).
60.Wu, B.Y., Zhong, H.W., Chan, Y.C., and Alam, M.O.: Degradation of Sn37Pb and Sn3.5Ag0.5Cu solder joints between Au/Ni (P)/Cu pads stressed with moderate current density. J. Mater. Sci.: Mater. Electron. 17, 943950 (2006).
61.Chen, L.Q.: Phase-field models for microstructure evolution. Annu. Rev. Mater. Res. 32, 113140 (2002).
62.Wang, W., Suo, Z., and Hao, T.H.: A simulation of electromigration-induced transgranular slits. J. Appl. Phys. 79, 23942403 (1996).
63.COMSOL Multiphysics Users’ Guide (COMSOL Inc., Stockholm, Sweden, 2015).
64.Siewert, T., Liu, S., Smith, D.R., and Madeni, J.C.: Database for Solder Properties with Emphasis on New Lead-Free Solders (National Institute of Standards and Technology and Colorado School of Mines, Colorado, 2002).


Related content

Powered by UNSILO

Microstructural evolution and change in macroscopic physical properties of microscale flip chip Cu/Sn58Bi/Cu joints under the coupling effect of electric current stressing and elastic stress

  • Shui-Bao Liang (a1), Chang-Bo Ke (a1), Cheng Wei (a2), Jia-Qiang Huang (a1), Min-Bo Zhou (a1) and Xin-Ping Zhang (a1)...


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.