Varying amounts of Zn (1, 3, 7 wt%) were added to Sn–3.5Ag solder on the electroless Ni(P)/immersion Au metallization, and solder joint microstructures after reflow and isothermal aging (500 h at 150 °C) were investigated using scanning electron microscopy, energy dispersive x-ray spectroscopy, transmission electron microscopy, and x-ray diffraction, which were subsequently correlated to the microhardness and drop test results. Zinc in the solder affected the solder joint intermetallic compounds profoundly, which improved the drop reliability significantly. The effect of Zn was to nucleate Ni5Zn21 and to suppress the formation of Ni3P, Ni3SnP, and Ni3Sn4, which were known to increase the propensity for brittle cracking. Drop test results showed an inverse correlation between the number of drops-to-failure (Nf) and the thickness of Ni3P layer. As the growth of the Ni3P layer was suppressed by Zn, drop reliability increased substantially.
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T.I. Eijim, D.B. Hollesen, A. Holliday, S.A. Gahr R.J. Coyle: Assembly and reliability of thermally enhanced high I/O BGA packages in Proc. 21st IEEE International Electronics Manufacturing Symposium, 25 (1997)
Z. Mei, M. Kauffmann, A. Eslambolchi P. Johnson: Brittle interfacial fracture of PBGA packages on electroless Ni/immersion Au in Proc. 48th Electronic Component and Technology Conference, 952 (1998)
N. Biunno: A root cause failure mechanism for solder joint integrity of electroless Ni/immersion gold surface finishes. Proc. IPC Printed Circuit Expo. 1999, s18 1999
D. Goyal, T. Lane, P. Kinzie, C. Panichas, K.M. Chong O. Villalobos: Failure mechanism of brittle solder joint fracture in the presence of electroless nickel/immersion gold surface finishe in Proc. 52nd Electronic Component and Tech Conference, 732 (2002)
J.Y. Song J. Yu: Residual stress measurements in electroless plated Ni–P films. Thin Solid Films 415, 167 2002
Y.C. Sohn, J. Yu, S.K. Kang, D.Y. Shih T.Y. Lee: Spalling of intermetallic compounds during the reaction between lead-free solders and electroless Ni–P metallization. J. Mater. Res. 19, 2428 2004
Y.C. Sohn J. Yu: Correlation between chemical reaction and brittle fracture found in electroless Ni(P)/immersion gold-solder interconnection. J. Mater. Res. 20, 1931 2005
H. Min, Z. Chen G. Qi: Solid state interfacial reaction of Sn–37Pb and Sn–3.5Ag solders with Ni–P under bump metallization. Acta Mater. 52, 2047 2004
C.M.L. Wu C.M.T. Law: Microstructure evolution and shear strength of eutectic Sn–9Zn and Sn–0.7Cu lead-free BGA solder balls. Proc. HDP 04, 47 2004
H. Mavoori, J. Chin, S. Vaynman, B. Moran, L. Keer M.E. Fine: Creep, stress relaxation, and plastic deformation in Sn–Ag and Sn–Zn eutectic solders. J. Electron. Mater. 41, 1269 1997
Y. Chonan, T. Komiyama, J. Onuki, R. Urao, T. Kimura T. Nagano: Influence of P content in electroless plated Ni–P alloy film on interfacial structures and strength between Sn–Zn solder and plated Au/Ni–P alloy film. Mater. Trans. 43, 1887 2002
K.L. Lin C.L. Shih: Wetting interaction between Sn–Zn–Ag solders and Cu. J. Electron. Mater. 32, 95 2003
D.Q. Yu, H.P. Xie L. Wang: Investigation of interfacial microstructure and wetting property of newly developed Sn–Zn–Cu solders with Cu substrate. J. Alloys Compd. 385, 119 2004
T. Takemoto, T. Funaki A. Matsunawa: Electrochemical investigation on the effect of silver addition on wettability of Sn–Zn system lead-free solder. Welding Res. Abroad 46, 20 2000
M. Date, T. Shoji, M. Fujiyoshi, K. Sato K.N. Tu: Ductile-to-brittle transition in Sn–Zn solder joints measured by impact test. Scripta Mater. 51, 641 2004
Y.K. Jee, Y.H. Ko J. Yu: Effect of Zn on the intermetallics formation and reliability of Sn–3.5Ag solder on a Cu pad. J. Mater. Res. 22 (2007, in press)
JESD22-B111 Board Level Drop Test Method of Components for Handheld Electronic Components (JEDEC Solid State Technology Association 2003
W.K. Choi: Interfacial phenomena and characterization of Sn-Ag-based solder alloy systems for electronic packaging. Ph.D. Thesis, Korea Advanced Institute of Science and Technology, Daejeon, Korea (2001)
B.D. Cullity: Elements of X-ray Diffraction Prentice Hall 2001
J. Yu, C.J. McMahon Jr.: The effect of composition and carbide precipitation on temper embrittlement of 2.25Cr–1Mo Steel, Part I. Effect of P and Sn. Metall. Trans. 11, 277 1980
J. Yu, Y.C. Sohn, J.Y. Kim, Y.K. Jee Y.H. Ko Impact reliabilities of lead-free solder joints with Ni(P), Cu and Ni metallizations. in Proc. International Conference on Electronics Packaging, 271 (2006)
J.W. Jang, P.G. Kim, K.N. Tu, D.R. Frear P. Thomson: Solder reaction-assisted crystallization of electroless Ni-P under bump metallization in low cost flip chip technology. J. Appl. Phys. 85, 8456 1999
Y.C. Chan, M.Y. Chiu T.H. Chuang: Intermetallic compounds formed during the soldering reactions of eutectic Sn–9Zn with Cu and Ni substrates. Z. Metallkde. 93, 95 2002
J.F. Knott: Fundamentals of Fracture Mechanics Butterworths London, UK 1973 147
This work was supported by the Center for Electronic Packaging Materials (ERC) of MOST/KOSEF (Grant No. R11-2000-085-08001-0).
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Jee, Y.K., Yu, J. & Ko, Y.H. Effects of Zn addition on the drop reliability of Sn–3.5Ag–xZn/Ni(P) solder joints. Journal of Materials Research 22, 2776–2784 (2007). https://doi.org/10.1557/JMR.2007.0346