Abstract
The present work studies the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder on Cu. The study includes solder bumps 140–145 µm in diameter and 55–65 µm tall deposited on Cu-plated Si, and solder joints 60 µm in diameter and 25 µm in height that join Cu-plated ceramic and polymide substrates. The results show that the microstructure is strongly affected by the addition of Cu from the substrate during reflow, which produces a thick intermetallic layer along the interface. In the case of the joints, normal processing produces a coarse microstructure that includes only a few grains between thick intermetallic coatings. Aging at high temperature causes a further monotonic increase in Cu content, which alters the intermetallic structure at the interfaces and can lead to intermetallic bridging across the joint. Thermal fatigue tests suggest that cyclic deformation breaks up the intermetallic structure, increasing the rate of Cu addition to the joint, but refining the apparent grain size.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
J.W. Morris, Jr., J. Korean Phys. Soc. 35, 335 (1999).
K.N. Tu and R. Rosenberg, Jpn. J. Appl. Phys., Suppl. 2 Part 1, 633 (1974).
J.S. Hwang, Modern Solder Technology for Competitive Electronics Manufacturing (New York: McGraw-Hill Co., 1996), p. 418.
M.T. McCormack, H. Jiang, S.I. Beilin, B. Chou, and M. Peters, EEP-Vol.26-2, Adv. Electron. Pkg. 2, 1807 (1999).
G.S. Matijasevic, C.C. Lee, and C.Y. Wang, Thin Solid Films 223, 276 (1993).
E. Zakel and H. Reichl, Flip Chip Technologies, ed. J.H. Lau (New York: McGraw-Hill Co., 1996), p. 451.
S. Nakahara, R.J. McCoy, L. Buene, and J.M. Vandenberg, Thin Solid Films 84, 185 (1981).
M.R. Pinnel and J.E. Bennett, Metall. Trans. 3, 1989 (1972).
Z. Mei, A.J. Sunwoo, and J.W. Morris, Jr., Metall. Trans. A 23A, 857 (1992).
O.B. Karlsen, A. Kjekshus, and E. Rost, Acta Chem. Scan. 46, 147 (1992).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Song, H.G., Morris, J.W. & McCormack, M.T. The microstructure of ultrafine eutectic Au-Sn solder joints on Cu. J. Electron. Mater. 29, 1038–1046 (2000). https://doi.org/10.1007/s11664-000-0170-9
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/s11664-000-0170-9