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Flip Chip Metallurgies for Lead-Free Solders

Published online by Cambridge University Press:  10 February 2011

T. M. Korhonen ,
S. J. Hong ,
M. A. Korhonen  and
C.-Y. LI
T. M. Korhonen
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca NY 14853
S. J. Hong
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca NY 14853
M. A. Korhonen
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca NY 14853
C.-Y. LI
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca NY 14853
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Abstract

The most commonly used lead-free solders contain large amounts of tin, which makes them incompatible with the conventional Cu-based underbump metallization (UBM) schemes. The tin in the solder reacts with the copper layer of the UBM, depleting the UBM of copper and causing loss of adhesion and a weak interface. Use of new under bump metallization schemes with Ni or CuNi alloys as the solderable layer were investigated in this study. Instead of Cr, a Tibased adhesion layer was used to decrease the amount of stress in the CuNi layer. Flip chip solder joints were made in which three Sn-Bi-Ag based lead-free solders were reflowed to several UBM pads of different compositions. The resulting interfacial microstructures were examined by SEM/EDX analysis of cross-sectioned samples. The joints were also mechanically tested in fatigue and shear to assess the quality and reliability of the interface.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 515: Symposium J – Electronic Packaging Materials Science X , 1998 , 79
Copyright
Copyright © Materials Research Society 1998

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References

REFERENCES

1. Kim, H. K., Liou, H. K. and Tu, K. N., Appl. Phys. Lett. 66, p. 2337, 1995 Google Scholar
2. Kim, H.K. and Tu, K. N., Appl. Phys. Lett. 67, p. 2002, 1995 Google Scholar
3. Liu, T., Kim, D., Leung, D., Korhonen, M. A. and Li, C.-Y., Scripta Materialia 35, 1996 Google Scholar
4. Bader, S., Gust, W. and Hieber, H., Acta Metall. Mater. 43, p. 329, 1995 Google Scholar
5. Rai, R. S.. Kang, S. K. and Purushothaman, S., Proc. 45th Electronic omponents & Technology Conference (IEEE), p. 1197, 1995 Google Scholar
6. Harada, M., Satoh, R., Yamada, O., Proc. 47th Electronic Components & Technology Conference (IEEE), p. 866, 1997 Google Scholar
7. Korhonen, T. M., Hong, S. J., Su, P., Zhou, C., Korhonen, M. A., and Li, C.-Y., “Under Bump Metallization Development for High Sn Solders”, MRS Fall Meeting, Boston, Dec. 1–5, 1997 (to be published in MRS Symp. Proc. 505)Google Scholar
8. Hong, S. J., Korhonen, T. M., Korhonen, M. A., and Li, C.-Y., “Under Bump Metallization Development for Eutectic Pb-Sn Solders”, MRS Spring Meeting, San Francisco, Apr.13–17, 1998 (to be published in MRS Symp. Proc. 515)Google Scholar