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Undercooling and microhardness of Pb-free solders on various under bump metallurgies

Published online by Cambridge University Press:  31 January 2011

Moon Gi Cho ,
Sung K. Kang  and
Hyuck Mo Lee
Moon Gi Cho
Affiliation:
Department of Materials Science and Engineering, KAIST, Gusung-Dong 373-1, Yusung-Gu, Daejeon, Republic of Korea 305-701
Sung K. Kang
Affiliation:
IBM T.J. Watson Research Center, Yorktown Heights, New York 10598
Hyuck Mo Lee*
Affiliation:
Department of Materials Science and Engineering, KAIST, Gusung-Dong 373-1, Yusung-Gu, Daejeon, Republic of Korea 305-701
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

The undercooling behavior of pure Sn, Sn–0.7Cu, Sn–3.5Ag, and Sn–3.8Ag–0.7Cu solder alloys was observed in terms of various under bump metallurgies (UBMs). Four different UBMs (electroplated Cu, electroplated Ni, electroless Ni(P), and electroless Ni(P)/immersion Au) were used. The amount of the undercooling of Pb-free solder alloys was reduced when reacted with electroplated Cu UBM and Ni-based UBMs. The Ni-based UBMs were more effective than Cu UBM in reducing the undercooling of Pb-free solders. When Ni3Sn4 was formed during the interfacial reactions with Ni-based UBMs, the reduction of undercooling was significant, especially for pure Sn and Sn–3.5Ag. The effects of UBMs on the undercooing of Pb-free solder alloys are discussed by comparing intermetallic compounds formed during interfacial reactions with UBMs. In addition, the microstructural changes as well as the microhardness of four solders with or without UBMs are discussed, which could be related to their undercooling behaviors.

Keywords

SolderingMicrostructureHardness
Type
Articles
Information
Journal of Materials Research , Volume 23 , Issue 4 , April 2008 , pp. 1147 - 1154
Copyright
Copyright © Materials Research Society 2008

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References

REFERENCES

1Bath, J., Handwerker, C.Bradley, E.: Research update: Lead-free solder alternatives. Circuits Assem. 11, 31 2000Google Scholar
2Anderson, I.E., Foley, J.C., Cook, B.A., Harringa, J., Terpatra, R.K.Unal, O.: Alloying effects in near-eutectic Sn–Ag–Cu solder alloys for improved microstructural stability. J. Electron. Mater. 30, 1050 2001CrossRefGoogle Scholar
3Puttlitz, K.J.: Sn–Ag and Sn–Ag–X solders and properties in Handbook of Lead-Free Solder Technology for Microelectronic Assemblies edited by K.J. Puttlitz and K.A. Stalter Marcel Dekker New York 2004 239–280CrossRefGoogle Scholar
4Jeong, S.W., Kim, J.H.Lee, H.M.: Effect of cooling rate on growth of IMC and fracture mode of near-eutectic Sn–Ag–Cu/Cu pad: Before and after aging. J. Electron. Mater. 33, 1530 2004CrossRefGoogle Scholar
5Kang, S.K., Lauro, P., Shih, D-Y., Henderson, D.W.Puttlitz, K.J.: The microstructure, solidification, mechanical properties, and thermal fatigue behavior of lead (Pb)-free solders and solder joints used in microelectronic applications. IBM J. Res. Dev. 49, 606 2005CrossRefGoogle Scholar
6Vonnegut, B.: Variation with temperature of the nucleation rate of supercooled liquid tin and water drops. J. Colloid Sci. 3, 563 1948CrossRefGoogle ScholarPubMed
7Pound, G.M.Mer, V.K.L.A.: Kinetics of crystalline nucleus formation in supercooled liquid tin. J. Am. Chem. Soc. 74, 2323 1952CrossRefGoogle Scholar
8Kang, S.K., Choi, W.K., Shih, D-Y., Henderson, D.W., Gosselin, T., Sarkhel, A., Goldsmith, C.Puttlitz, K.J.: Formation of Ag3Sn plates in Sn–Ag–Cu alloys and optimization of their alloy composition in Proc. 53rd Electronic Components and Technology Conference IEEE Piscataway, NJ 2003 64–70Google Scholar
9Lehman, L.P., Kinyanjui, R.K., Zavalij, L., Zribi, A.Cotts, E.J.: Growth and selection of intermetallic species in Sn–Ag–Cu no-Pb solder systems based on pad metallurgies and thermal histories in Proc. 53rd Electronic Components and Technology Conference IEEE Piscataway, NJ 2003 1215–1221Google Scholar
10Kang, S.K., Shih, D-Y., Leonard, D., Henderson, D.W., Gosselin, T., Cho, S-I., Yu, J.Choi, W.K.: Controlling Ag3Sn plate formation in near-ternary-eutectic Sn–Ag–Cu solder by minor Zn alloying. JOM 56(6), 34 2004CrossRefGoogle Scholar
11Kinyanjui, R., Lehman, L.P., Zavalij, L.Cotts, E.: Effect of sample size on the solidification temperature and microstructure of SnAgCu near eutectic alloys. J. Mater. Res. 20, 2914 2005CrossRefGoogle Scholar
12Kang, S.K., Cho, M.G., Lauro, P.Shih, D-Y.: Critical factors affecting the undercooling of Pb-free, flip-chip solder solder bumps and in-situ observation of solidification process in Proc. 57th Electronic Components and Technology Conference IEEE Piscataway, NJ 2007 1597–1603Google Scholar
13Kang, S.K., Cho, M.G., Lauro, P.Shih, D-Y.: Study of the undercooling of Pb-free, flip-chip solder bumps and in situ observation of solidification process. J. Mater. Res. 22, 557 2007CrossRefGoogle Scholar
14Xiao, Q., Nguyen, L.Armstrong, W.D.: The anomalous microstructural, tensile, and aging response of thin-cast Sn3.9Ag0.6Cu lead-free solder. J. Electron. Mater. 34, 617 2005CrossRefGoogle Scholar
15Kim, K.S., Huh, S.H.Suganuma, K.: Effects of fourth alloying additive on microstructures and tensile properties of Sn–Ag–Cu alloy and joints with Cu. Microelectron. Reliab. 43, 259 2002CrossRefGoogle Scholar
16de Sousa, I., Henderson, D.W., Party, L., Kang, S.K.Shih, D-Y.: The influence of low level doping on the thermal evolution of SAC alloy solder joints with Cu pad structures in Proc. 56th Electronic Components and Technology Conference IEEE Piscataway, NJ 2006 1454–1461Google Scholar
17Chen, S-W.Huang, C-C.: The relationship between the peak shape of a DTA curve and the shape of a phase diagram. Chem. Eng. Sci. 50, 417 1995CrossRefGoogle Scholar
18Chen, S-W., Lin, C-C.Chen, C-M.: Determination of the melting and solidification characteristics of solders using differential scanning calorimetry. Metall. Mater. Trans. A 29, 1965 1998CrossRefGoogle Scholar
19Jeon, Y-D., Nieland, S., Ostmann, A., Reichl, H.Paik, K-W.: A study on interfacial reactions between electroless Ni–P under bump metallization and 95.5Sn–4.0Ag–0.5Cu alloy. J. Electron. Mater. 32, 548 2003CrossRefGoogle Scholar
20Cho, M.G., Paik, K.W., Lee, H.M., Booh, S.W.Kim, T.G.: Interfacial reaction between 42Sn–58Bi solder and electroless Ni–P/immersion Au under bump metallurgy during aging. J. Electron. Mater. 35, 35 2006CrossRefGoogle Scholar
21Ho, C.E., Yang, S.C.Kao, C.R.: Interfacial reaction issues for lead-free electronic solders. J. Mater. Sci. Mater. Electron. 18, 155 2007CrossRefGoogle Scholar
22Chen, S-W.Wang, C-H.: Interfacial reactions of Sn–Cu/Ni couples at 250 °C. J. Mater. Res. 21, 2270 2006CrossRefGoogle Scholar