Abstract
The mechanical behavior of electroplated Sn thin films was investigated using thermal-expansion induced strain. For stress above a threshold value, the stress relaxation observed during the thermal cycles is well-described by a power law creep mechanism with exponents similar to those of the bulk material. However, the stress relaxation showed significant thickness dependence so that the relaxation in thicker films is faster than thinner films. The surface oxide was also shown to have a considerable effect on retarding the relaxation by inhibiting diffusion to the surface. The relevance of the stress relaxation to whisker formation in Sn-based coatings is discussed.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
B. Vandervelde, M. Gonzalez, P. Limaye, P. Ratchev, and E. Beyne: Thermal cycling reliability of SnAgCu and SnPb solder joints: A comparison for several IC-packages. Microelectron. Reliab. 47, 259 (2007).
J. Liang, S. Downes, N. Dariavach, D. Shangguan, and S.M. Heinrich: Effects of load and thermal conditions on Pb-free solder joint reliability. J. Electron. Mater. 33, 1507 (2004).
M. Abtew and G. Selvaduray: Lead-free solders in microelectronics. Mater. Sci. Eng., R 27, 95 (2000).
K.N. Tu: Interdiffusion and reaction in bimetallic Cu-Sn thin films. Acta Metall. 21, 347 (1973).
K.N. Tu: Irreversible processes of spontaneous whisker growth in bimetallic Cu-Sn thin-film reactions. Phys. Rev. B 49, 2030 (1994).
B.Z. Lee and D.N. Lee: Spontaneous growth mechanism of tin whiskers. Acta Mater. 46, 3701 (1998).
D. Weiss, H. Gao, and E. Arzt: Constrained diffusional creep in UHV-produced copper thin films. Acta Mater. 49, 2395 (2001).
R-M. Keller, S.P. Baker, and E. Arzt: Stress-temperature behavior of unpassivated thin copper films. Acta Mater. 47, 415 (1999).
R-M. Keller, S.P. Baker, and E. Arzt: Quantitative analysis of strengthening mechanisms in thin Cu films: Effects of film thickness, grain size, and passivation. J. Mater. Res. 13, 1307 (1998).
M.D. Thouless, J. Gupta, and J.M.E. Harper: Stress development and relaxation in copper films during thermal cycling. J. Mater. Res. 8, 1845 (1993).
W.D. Nix: Mechanical properties of thin films. Metall. Trans. A 20, 2217 (1989).
P.A. Flinn, D.S. Gardner, and W.D. Nix: Measurement and interpretation of stress in aluminum-based metallization as a function of thermal history. IEEE Trans. Electron. Dev. 34, 689 (1987).
E. Chason and B.W. Sheldon: Monitoring stress in thin films during processing. Surf. Eng. 19, 287 (2003).
L.B. Freund and S. Suresh: Thin Film Materials (Cambridge University Press, Cambridge, UK, 2003), p. 90.
J.G. Lee, A. Telang, K.N. Subramanian, and T.R. Bieler: Modeling thermomechanical fatigue behavior of Sn-Ag solder joints. J. Electron. Mater. 31, 1152 (2002).
H.J. Frost and M.F. Ashby: Deformation-Mechanism Maps (Pergamon Press, Elmsford, NY, 1982), pp. 6–16.
Metals Handbook: Properties and Selection: Non-Ferrous Alloys and Special Purpose Materials, 10th ed., Vol. 2 (ASM, Metals Park, OH, 1990), pp. 517–526.
M.D. Mathew, H. Yang, S. Movva, and K.L. Murty: Creep deformation characteristics of tin and tin-based electronic solder alloys. Metall. Mater. Trans. A 36, 99 (2005).
X.Q. Shi, Z.P. Wang, Q.J. Yang, and H.L.J. Pang: Creep behavior and deformation mechanism map of Sn-Pb eutectic solder alloy. ASME J. Eng. Mater. Technol. 125, 81 (2003).
R.J. McCabe and M.E. Fine: Creep of tin, Sb-solution-strengthened tin, and SbSn-precipitate-strengthened tin. Metall. Mater. Trans. A 33, 1531 (2002).
J. Weertman and J.E. Breen: Creep of tin single crystals. J. Appl. Phys. 27, 1189 (1956).
T. Chen and I. Dutta: Effect of Ag and Cu concentrations on the creep behavior of Sn-based solers. J. Electron. Mater. 37, 347 (2008).
C. Park, X. Long, S. Haberman, S. Ma, I. Dutta, R. Mahajan, and S.G. Jadhav: A comparison of impression and compression creep behavior of polycrystalline Sn. J. Mater. Sci. 42, 5182 (2007).
Z. Guo, Y-H. Pao, and H. Conrad: Plastic deformation kinetics of 95.5Sn4Cu0.5Ag solder joints. J. Electron. Packag. 117, 100 (1995).
W.H. Bang, K.H. Oh, J.P. Jung, J.W. Morris, Jr., and F. Hua: The correlation between stress relaxation and steady-state creep of eutectic Sn-Pb. J. Electron. Mater. 34, 1287 (2005).
Y. Choi and S. Suresh: Size effects on the mechanical properties of thin polycrystalline metal films on substrates. Acta Mater. 50, 1881 (2002).
J.W. Shin and E. Chason: (submitted).
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Shin, J.W., Chason, E. Stress behavior of electroplated Sn films during thermal cycling. Journal of Materials Research 24, 1522–1528 (2009). https://doi.org/10.1557/jmr.2009.0172
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1557/jmr.2009.0172