Hostname: page-component-78c5997874-m6dg7 Total loading time: 0 Render date: 2024-11-04T20:11:58.221Z Has data issue: false hasContentIssue false

Effect of solder bump geometry on the microstructure of Sn–3.5 wt% Ag on electroless nickel immersion gold during solder dipping

Published online by Cambridge University Press:  01 March 2005

Zhiheng Huang
Affiliation:
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom
Paul P. Conway*
Affiliation:
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom
Changqing Liu
Affiliation:
Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom
Rachel C. Thomson
Affiliation:
Institute of Polymer Technology and Materials Engineering, Loughborough University Loughborough, Leicestershire LE11 3TU, United Kingdom
*
a)Address all correspondence to this author. e-mail address: [email protected]
Get access

Abstract

Continuous miniaturization of solder joints in high-density packaging makes it important to study how the joint size could affect the solder microstructure and thereby the subsequent in-service reliability. In this study, a printed circuit board with electroless nickel immersion gold (i.e., Au/Ni–P) over Cu bond pads of size approximately ∼80 μm and ∼1500 μm in diameter was dipped into a Sn–3.5Ag solder bath. The study shows that the smaller bumps, which cool more quickly, include much finer Ag3Sn particles. In addition, substantial differences in the thickness of the interfacial intermetallics and the microstructure for different dipping times are observed for different bump sizes. The results from a combined thermodynamic–kinetic model also suggest that the solder bump geometry can influence the dissolution kinetics of the pad metal into the molten solder and therefore the microstructure at the solder-pad interface and within the bulk solder.

Type
Articles
Copyright
Copyright © Materials Research Society 2005

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1.Kivilahti, J.K.: The chemical modeling of electronic materials and interconnections. JOM 54, 52 (2002).CrossRefGoogle Scholar
2.Morris, J.W.: The microstructure and properties of solder joints. J. Korean Phys. Soc. 35 S335 (1999).Google Scholar
3.Song, H.G., Morris, J.W. and McCormack, M.T.: The microstructure of ultrafine eutectic Au–Sn solder joints on Cu. J. Electron. Mater. 29, 1038 (2000).CrossRefGoogle Scholar
4.Schaefer, M., Fournelle, R.A. and Liang, J.: in Design and Reliability of Solder and Solder Interconnections, edited by Mahidhara, R.K., Frear, D.R., Sastry, S.M.L., Murtym, K.L., Liaw, P.K., Winterbottom, W. (TMS, Warrendale, PA, 1997), p. 247.Google Scholar
5.Chada, S., Laub, W., Fournelle, R.A. and Shangguan, D.: An improved numerical method for predicting intermetallic layer thickness developed during the formation of solder joints on Cu substrates. J. Electron. Mater. 28, 1194 (1999).CrossRefGoogle Scholar
6.Chada, S., Fournelle, R.A., Laub, W. and Shangguan, D.: Copper substrate dissolution in eutectic Sn–Ag solder and its effect on microstructure. J. Electron. Mater. 29, 1214 (2000).CrossRefGoogle Scholar
7.Ma, D., Wang, W.D. and Lahiri, S.K.: Scallop formation and dissolution of Cu–Sn intermetallic compound during solder reflow. J. Appl. Phys. 91, 3312 (2002).CrossRefGoogle Scholar
8.Choi, W.K., Kang, S.K. and Shih, D-Y.: A study of the effects of solder volume on the interfacial reactions in solder joints using the differential scanning calorimetry technique. J. Electron. Mater. 31, 1283 (2002).CrossRefGoogle Scholar
9.Sharif, A., Chan, Y.C. and Islam, R.A.: Effect of volume in interfacial reaction between eutectic Sn–Pb solder and Cu metallization in microelectronic packaging. Mater. Sci. Eng. B 106, 120 (2004).CrossRefGoogle Scholar
10.Huang, Z., Conway, P.P., Liu, C. and Thomson, R.C.: The effect of microstructure and geometrical features on reliability of ultrafine flip chip micro solder joints. J. Electron. Mater. 33, 1227 (2004).CrossRefGoogle Scholar
11.Salam, B., Ekere, N.N., and Rajkumar, D.: Study of the interface microstructure of Sn–Ag–Cu lead-free solders and the effect of solder volume on intermetallic layer formation, in Proc. Electronic Components & Technology Conference (Institute of Electrical and Electronics Engineers, Inc.) 51 471 2001.Google Scholar
12.Davies, R.H., Dinsdale, A.T., Chart, T.G., Barry, T.I. and Rand, M.H.: Application of MTDATA—to the modeling of multicomponent equilibria. High Temp. Sci. 26, 251 (1989).Google Scholar
13.Davies, R.H., Dinsdale, A.T., Gisby, J.A., Robinson, J.A.J. and Martin, S.M.: MTDATA-Thermodynamic and phase equilibrium software from the National Physical Laboratory. Calphad 26, 229 (2002).CrossRefGoogle Scholar
14.Ochoa, F., Williams, J.J. and Chawla, N.: Effects of cooling rate on the microstructure and tensile behavior of a Sn–3.5 wt%Ag solder. J. Electron. Mater. 32, 1114 (2003).CrossRefGoogle Scholar
15.Kang, S.K., Choi, W.K., Shih, D.Y., Henderson, D.W., Gosselin, T., Sarkhel, A., Goldsmith, C. and Puttlitz, K.J.: Ag3Sn plate formation in the solidification of near-ternary eutectic Sn–Ag–Cu. JOM 55, 61 (2003).CrossRefGoogle Scholar
16.Kang, S.K., Shih, D.Y., Leonard, D., Henderson, D.W., Gosselin, T., Cho, S.I., Yu, J. and Choi, W.K.: Controlling Ag3Sn plate formation in near-ternary-eutectic Sn Ag Cu solder by minor Zn alloying. JOM 56, 34 (2004).CrossRefGoogle Scholar
17.Henderson, D.W., Gosselin, T., Sarkhel, A., Kang, S.K., Choi, W.K., Shih, D.Y., Goldsmith, C. and Puttlitz, K.J.: Ag3Sn plate formation in the solidification of near ternary eutectic Sn–Ag–Cu alloys. J. Mater. Res. 17, 2755 (2002).CrossRefGoogle Scholar
18.Jang, J.W., Kim, P.G., Tu, K.N., Frear, D.R. and Thompson, P.: Solder reaction-assisted crystallization of electroless Ni–P under bump metallization in low cost flip chip technology. J. Appl. Phys. 85, 8456 (1999).CrossRefGoogle Scholar
19.Jang, J.W., Frear, D.R., Lee, T.Y. and Tu, K.N.: Morphology of interfacial reaction between lead-free solders and electroless Ni–P under bump metallization. J. Appl. Phys. 88, 6359 (2000).CrossRefGoogle Scholar
20.Kang, S.K., Shih, D.Y., Fogel, K., Lauro, P., Yim, M.J., Advocate, G.G., Griffin, M., Goldsmith, C., Henderson, D.W., Gosselin, T.A., King, D.E., Konrad, J.J., Sarkhel, A. and Puttlitz, K.J.: Interfacial reaction studies on lead (Pb)-free solder alloys. IEEE Trans. Electron. Pack. Manufac. 25, 155 (2002).CrossRefGoogle Scholar
21.Sohn, Y.C., Yu, J., Kang, S.K., Choi, W.K. and Shih, D.Y.: Study of the reaction mechanism between electroless Ni–P and Sn and its effect on the crystallization of Ni–P. J. Mater. Res. 18, 4 (2003).CrossRefGoogle Scholar
22.Sohn, Y.C., Yu, J., Kang, S.K., Shih, D.Y., and Lee, T.Y.: Study of spalling behaviour of intermetallic compounds during the reaction between electroless Ni–P metallization and lead-free solders, in Proc. Electronic Component & Technology Conference (Institute of Electrical and Electronics Engineers, Inc.) 54 75 2004.Google Scholar
23.Jeon, Y.D., Paik, K.W., Bok, K.S., Choi, W.S. and Cho, C.L.: Studies of electroless nickel under bump metallurgy-solder interfacial reactions and their effects on flip chip solder joint reliability. J. Electron. Mater. 31, 520 (2002).CrossRefGoogle Scholar
24.Jeon, J.D., Ostmann, A., Reichl, H., and Paik, K.W.: Comparison of interfacial reactions and reliabilities of Sn3.5Ag, Sn4.0Ag0.5Cu, and Sn0.7Cu solder bumps on electroless Ni–P UBMs. in Proc. Electronic Components & Technology Conference (Institute of Electrical and Electronics Engineers, Inc.) 53, 1203 2003.Google Scholar
25.Hung, K.C., Chan, Y.C., Tang, C.W. and Ong, H.C.: Correlation between Ni3Sn4 intermetallics and Ni3P due to solder reaction assisted crystallization of electroless Ni–P metallization in advanced packages. J. Mater. Res. 15, 2534 (2000).CrossRefGoogle Scholar
26.Alam, M.O., Chan, Y.C. and Tu, K.N.: Effect of reaction time and P content on mechanical strength of the interface formed between eutectic Sn–Ag solder and Au/electroless Ni(P)/Cu bond pad. J. Appl. Phys. 94, 4108 (2003).CrossRefGoogle Scholar
27.Matsuki, H., Ibuka, H. and Saka, H.: TEM observation of interfaces in a solder joint in a semiconductor device. Sci. Technol. Adv. Mater. 3, 261 (2002).CrossRefGoogle Scholar
28.Hiramori, T., Ito, M., Tanii, Y., Hirose, A. and Kobayashi, K.F.: Sn–Ag based solders bonded to Ni–P/Au plating: Effects of interfacial structure on joint strength. Mater. Trans. 44, 2375 (2003).CrossRefGoogle Scholar
29.He, M., Chen, Z. and Qi, G.: Solid state interfacial reaction of Sn–37Pb and Sn–3.5Ag solders with Ni–P under bump metallization. Acta Mater. 52, 2047 (2004).CrossRefGoogle Scholar
30.Liu, C.M., Ho, C.E., Chen, W.T. and Kao, C.R.: Reflow soldering and isothermal solid-state aging of Sn–Ag eutectic solder on Au/Ni surface finish. J. Electron. Mater. 30, 1152 (2001).CrossRefGoogle Scholar
31.Torazawa, N., Arai, S., Takase, Y., Sasaki, K. and Sakai, H.: Transmission electron microscopy of interfaces in joints between Pb-free solders and electroless Ni–P. Mater. Trans. 44, 1438 (2003).CrossRefGoogle Scholar
32.Komiyama, T., Chonan, Y., Onuki, J. and Ohta, T.: The influence of phosphorus concentration of electroless plated Ni–P film on interfacial structures in the joints between Sn–Ag solder and Ni–P alloy film. Mater. Trans. 43, 227 (2002).CrossRefGoogle Scholar
33.Hutt, D.A., Liu, C., Conway, P.P., Whalley, D.C. and Mannan, S.H.: Electroless nickel bumping of aluminium bondpads—Part II: Electroless nickel plating. IEEE T Compon Pack T. 25, 98 (2002).CrossRefGoogle Scholar
34.Li, L. and Yeung, B.: Wafer level and flip chip design through solder prediction models and validation. IEEE T Compon Pack T. 24, 650 (2001).CrossRefGoogle Scholar