Abstract
Future generations of electronics are expected to include flexible, bendable, and wearable devices. There have been very few studies, however, on the bonding technology and reliability of bonding joints between a chip and a flexible substrate. In this study, we investigated the properties and reliability of joints formed with Sn-58Bi solder microbumps between a Si chip and a flexible substrate. For fine-pitch bonding, we formed Cu pillar bumps and Sn-58Bi solder microbumps with diameter of 25 μm by electroplating. The Si chips were then bonded on a flexible substrate finished with electroless nickel immersion gold (ENIG) using flip-chip technology, processing at 170°C under a force of 1 N, 2 N, or 3 N for 15 s. Cross-sectional images of bump joints were analyzed using field-emission scanning electron microscopy. While the Cu6Sn5 intermetallic compound (IMC) was formed on the Cu-pillar-bump side, another IMC, Ni3Sn4, was formed on the ENIG–substrate side. In addition, we performed a shear test, thermal shock test, and bending test to evaluate the joints’ mechanical properties and reliability. The bending test was performed by a machine designed for joints on flexible substrates. Unit shear force of 2 N was the nominally highest value obtained from joints prepared under the three bonding conditions. After the thermal shock test, we observed cracks initiated at the Cu6Sn5/Sn-58Bi interface, which then propagated within the solder bumps or at the interface. In the case of the bending test, failure occurred at the Ni3Sn4/Sn-58Bi interface or within the solder bumps.
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K. Zeng and K.N. Tu, Mater. Sci. Eng. R 38, 55 (2002).
S.K. Kang and A.K. Sarkhel, J. Electron. Mater. 23, 701 (1994).
K. Lee, H.J. Kim, M.J. Lim, and K.W. Paik, IEEE Trans. Electron. Packag. Manuf. 32, 241 (2009).
J. Liu, Solder. Surf. Mount Technol. 13, 29 (2001).
L.K. Teh, E. Anto, C.C. Wong, S.G. Mhaisalkar, E.H. Wong, P.S. Teo, and Z. Chen, Thin Solid Films 462–463, 446 (2004).
J. Shen and Y.C. Chan, Microelectron. Reliab. 49, 223 (2009).
T.T. Bao, Y. Kim, J. Lee, and J.G. Lee, Mater. Trans. 51, 2145 (2010).
I.C. Chen and S. Wagner, Flexible Electronics: Materials and Applications, ed. W.S. Wong and A. Salleo (New York: Springer, 2009), p. 5.
E.A. Brandes, Smithelles Metals Reference Book, 6th ed. (London: Butterworth, 1983), p. 11.
J.W. Nah, K.W. Paik, T.K. Hwang, and W.H. Kim, IEEE Trans. Electron. Packag. Manuf. 26, 166 (2003).
S. Chen, L. Zhang, J. Liu, Y. Gao, and Q. Zhai, Mater. Trans. 51, 1720 (2010).
P.T. Vianco, A.C. Kilgo, and R. Grnat, J. Electron. Mater. 24, 1493 (1995).
J.W. Yoon, C.B. Lee, and S.B. Jung, Mater. Trans. 43, 1821 (2002).
P.G. Kim, J.W. Jang, T.Y. Lee, and K.N. Tu, J. Appl. Phys. 86, 6746 (1999).
P.W. Wong, M. Ying, A. Tengh, A. Mohtar, and Y.C. Chia, in Proceedings of 8th Electronic Packaging Technology Conference (Singapore, Singapore, December 6–8, 2006), p. 307.
R.R. Tummala, Fundamentals of Microsystems Packaging, 1st ed. (New York: McGraw-Hill, 2001), p. 188.
J.G. Lee, A. Telang, K.N. Subramanan, and T.R. Bieler, J. Electron. Mater. 31, 1152 (2002).
L. Xu, T. Reinikaninen, W. Ren, B.P. Wang, Z. Han, and D. Agonafer, Microelectron. Reliab. 44, 1977 (2004).
R. Ghaffarian and N.P. Kim, IEEE Trans. Compon. Packag. Technol. 23, 528 (2000).
X. Zhang, V. Kripesh, T. Chai, T.C. Tan, D. Pinjala, and M.K. Iyer, in Proceedings of 7th Electronic Packaging Technology Conference (Singapore, Singapore, December 7–9, 2005), p. 158.
A.J.G. Strandjord, S. Popelar, and C. Jauernig, Mircoelectron. Reliab. 42, 265 (2002).
M. Abtew and G. Selvadurary, Mater. Sci. Eng. 27, 95 (2000).
N. Jiang, J.A. Clum, R.R. Chromik, and E.J. Cotts, Scripta Mater. 37, 1851 (1997).
J.H.L. Pang, S.C.K. Wong, S.K. Neo, and K.E. Tan, in Proceedings of 2nd Electronics System-Integration Technology Conference (Greenwich, UK, September 1–4, 2008), p. 744.
H. Tnanka, L.F. Qun, O. Munekata, T. Taguchi, and T. Narita, Mater. Trans. 46, 1271 (2005).
W.D. Callister Jr, Materials Science and Engineering: an Introduction, 3rd ed. (New York: Wiley, 1994), p. 117.
I. Kim and S.B. Lee, in Proceedings of 2007 IEEE 57th Electronic Components and Technology Conference (Reno, NV, May 29–June 1, 2007), p. 95.
D. Goyal, T. Lane, P. Kinzie, C. Panichas, K.M. Chong, and O. Villalobos, in Proceedings of 2002 IEEE 52nd Electronic Components and Technology Conference (San Diego, CA, May 28–31, 2002), p. 732.
E.H. Wong, S.K.W. Seah, C.S. Selvanayagam, R. Rajoo, W.D.V. Driel, J.F.J.M. Caers, X.J. Zhao, N. Owens, M. Leoni, L.C. Tan, Y.-S. Lai, and C.-L. Yeh, J. Electron. Mater. 38, 884 (2009).
K. Harada, S. Baba, Q. Wu, H. Matsushima, T. Matsunaga, Y. Uegai, and M. Kimura, in Proceedings of 2003 IEEE 53rd Electronic Components and Technology Conference (New Orleans, LA, May 27–30, 2003), p. 1731.
G. Ghosh, J. Mater. Res. 19, 1439 (2004).
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Ko, YH., Kim, MS., Bang, J. et al. Properties and Reliability of Solder Microbump Joints Between Si Chips and a Flexible Substrate. J. Electron. Mater. 44, 2458–2466 (2015). https://doi.org/10.1007/s11664-015-3781-x
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DOI: https://doi.org/10.1007/s11664-015-3781-x