Abstract
Sn–Zn based alloys are promising as Pb-free solders, and Cu is commonly used in electronic products. Solidification and interfacial reactions of Sn–8.8wt%Zn, Sn–8.8wt% Zn–0.05wt%Co, and Sn–8.8wt%Zn–0.5wt%Co solders on Cu substrates are investigated. Two different masses of solders are used. The degrees of undercooling increase with increasing Co additions in the Sn–8.8wt%Zn alloys. The reaction products evolve with reaction time, and the timing of different reaction stages is influenced by both the minor Co alloying and the mass of solders. In the initial reaction stage, two reaction phases, γ-Cu5Zn8 and ε-CuZn5, are observed in the Sn–8.8wt%Zn/Cu and Sn–8.8wt% Zn-0.05wt%Co/Cu couples, and only the γ-Cu5Zn8 phase is found when the Co addition is up to 0.5 wt%. The reaction layers are thinner with higher Co alloying. The addition of Co into the Sn–Zn alloys consumes Zn, and this depletion of Zn in the Sn–Zn solders is the primary reason for the changes of reaction products and the thinner reaction layers.
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References
J. Glazer: Metallurgy of low temperature Pb-free solders for electronic assembly Int. Mater. Rev. 40(21, 65 (1995).
M. Abtew and G. Selvaduary: Lead-free solders in microelectronics Mater. Sci. Eng., R 27, 95 (2000).
C.W. Huang and K.L. Lin: Interfacial reactions of lead-free Sn-Zn based solders on Cu and Cu plated electroless Ni-P/Au layer under aging at 150 °C J. Mater. Res. 19, 121 (3560).
S.W. Chen, C.H. Wang, S.K. Lin, and C.N. Chiu: Phase diagrams of Pb-free solders and their related materials systems J. Mater. Sci.- Mater. Electron. 18, 19 (2007).
K.S. Kim, S.H. Huh, and K. Suganuma: Effects of fourth alloying additive on microstructures and tensile properties of Sn-Ag-Cu alloy and joints with Cu Microelectron. Reliab. 43, 259 (2003).
J.M. Song, C.F. Huang, and H.Y. Chung: Microstructural characteristics and vibration fracture properties of Sn-Ag-Cu-TM (TM = Co, Ni, and Zn) alloys J. Electron. Mater. 35, 12 (2154).
H. Nishikawa, A. Komatsu, and T. Takemoto: Morphology and pull strength of Sn-Ag-(Co) solder joint with copper pad J. Electron. Mater. 36, 9 (1137).
I.E. Anderson: Development of Sn-Ag-Cu and Sn-Ag-Cu-X alloys for Pb-free electronic solder applications J. Mater. Sci.-Mater. Electron. 18, 55 (2007).
Y.W. Wang, Y.W. Lin, C.T. Wu, and C.R. Kao: Effects of minor Fe, Co, Ni additions on the reaction between SnAgCu solder and Cu J. Alloys Comvd. 478, 121 (2009).
D.H. Kim, M.G. Cho, S.K. Seo, and H.M. Lee: Effects of Co addition on bulk properties of Sn-35Ag solder and interfacial reactions with Ni-P UBM. J. Electron. Mater. 38(1) 39 (2009).
C.Y. Chou, S.W. Chen, and Y.S. Chang: Interfacial reactions in the Sn-9Zn-(xCu)/Cu and Sn-9Zn-(xCu)/Ni couples J. Mater. Res. 21, 7 (1849).
J.E. Lee, K.S. Kim, M. Inoue, J. Jiang, and K. Suganuma: Effects of Ag and Cu addition on microstructural properties and oxidation resistance of Sn-Zn eutectic alloy J. Alloys Comvd. 454, 310 (2008).
W.K. Liou, Y.W. Yen, and C.C. Jao: Interfacial reactions of Sn-9Zn-xCu (x = 1, 4, 7, 10) solders with Ni substrate J. Electron. Mater. 38, 11 (2222).
C.W. Wang and S.W. Chen: Sn-07wt%Cu/Ni interfacial reactions at 250 °C. Acta Mater. 54, 247 (2006).
C.E. Ho, Y.W. Lin, S.C. Yang, C.R. Kao, and D.S. Jiang: Effects of limited Cu supply on soldering reactions between SnAgCu and Ni J. Electron. Mater. 35, 5 (1017).
S.W. Chen, C.C. Lin, and C.M. Chen: Determination of the melting and solidification characteristics of solders by using DSC Metall. Mater. Trans. A 29, 1965 (1998).
W.J. Boettinger, U.R. Kattner, K-W. Moon, and J.H. Perepezko: DTA and Heat-Flux DSC Measurements of Alloy Melting and Freezing (NIST, Washington, DC, 2006)
Y.C. Huang, S.W. Chen, and K.S. Wu: Size and substrate effects upon undercooling of Pb-free solders J. Electron. Mater. 391 109, (2010).
Z. Moser, J. Dutkiewicz, W. Gasior, and J. Salawa: Binary Alloy Phase Diagram, 2nd ed, edited by T.B. Massalski (ASM International, Materials Park, OH, 1990), p. 3416.
H. Okamoto: Co-Sn (cobalt-tin) J. Phase Eauilib. Diffus. 273 308, (2006).
T.B. Massalski: Binary Alloy Phase Diagram, 2nd ed, edited by H. Okamoto, P.R. Subramanian, and L. Kacprzak (ASM International, Materials Park, OH, 1990), p. 1261.
I.E. Anderson, J. Walleser, and J.L. Harringa: Observations of nucleation catalysis effects during solidification of SnAgCuX solder joints JOM 597, 38 (2007).
R. Kinyanjui, L.P. Lehman, L. Zavalij, and E. Cotts: Effect of sample size on the solidification temperature and micro-structure of SnAgCu near eutectic alloys J. Mater. Res. 20(11 2914 (2005).
Y.C. Huang, S.W. Chen, C.Y. Chou, and W. Gierlotka: Liquidus projection and thermodynamic modeling of Sn-Zn-Cu ternary system J. Alloys Comnd. 477, 283 (2009).
S.C. Yang, C.E. Ho, C.W. Chang, and C.R. Kao: Strong Zn concentration effect on the soldering reactions between Sn-based solders and Cu J. Mater. Res. 21,10 pp2436, (2006).
A. Rahn: The Basics of Soldering (Wiley-Interscience Publications, New York, NY, 1993)
K. Suganuma, T. Murata, H. Noguchi, and Y. Toyoda: Heat resistance of Sn-9Zn solder/Cu interface with or without coating J. Mater. Res. 154 884, (2000).
M. Date, K.N. Tu, T. Shoji, M. Fujiyoshi, and K. Sato: Interfacial reactions and impact reliability of Sn-Zn solder joints on Cu or electroless Au/Ni(P) bond-pads J. Mater. Res. 19(10), 2887 (2004).
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Huang, Yc., Chen, Sw. Co alloying and size effects on solidification and interfacial reactions in the Sn−Zn−(Co)/Cu couples. Journal of Materials Research 25, 2430–2438 (2010). https://doi.org/10.1557/jmr.2010.0314
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DOI: https://doi.org/10.1557/jmr.2010.0314