Skip to main content
SpringerLink
Log in

Fluxless bonding of Si chips to aluminum boards using electroplated Sn solder

  • Published:
Journal of Materials Science: Materials in Electronics Aims and scope Submit manuscript

Abstract

The high thermal conductivity and light weight properties of aluminum (Al) make it a promising material in high power device packaging and automotive electronics. A primary challenge is its high coefficient of thermal expansion (CTE) of 23 ppm/°C. In this research, we investigated the possibility of surmounting this challenge by bonding large Si chips to Al substrates using fluxless tin (Sn) solder. The Si–Al pair probably has the largest CTE mismatch among all bonded structures in electronic packaging. In experiments, 0.1 μm Cr layer and 0.2 μm Cu layer were deposited on Al substrates, followed by an electroplated 25 μm copper (Cu) layer. The Sn solder layer was then electroplated over the Cu, followed immediately by thin (0.1 μm) silver (Ag) layer. The joint thickness was controlled either by bonding pressure or by incorporating Cu spacers. Microstructure and composition of the joints were studied with scanning electron microscopy and energy dispersive X-ray spectroscopy. Despite the large CTE mismatch, the bonded structures did not break. The minimum fracture force measured among six samples by shear test is higher than three times of what specified in MIL-STD-883H, method 2019.8. This preliminary result corroborates potential adaption of Al substrates and boards in electronic packaging where lightweight is essential.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9

Similar content being viewed by others

References

  1. S. Lee, Optimum design and selection of heat sinks. IEEE Trans. Compon. Packag. Manuf. Technol. Part A 18, 812–817 (1995)

    Article  Google Scholar 

  2. C. Zweben, Advances in LED packaging and thermal management materials. Proc. SPIE Int. Soc. Opt. Eng. 6910, 691018 (2008)

    Google Scholar 

  3. P.-M. Geffroy, J.-D. Mathias, J.-F. Silvain, J.-F. Silvain, Heat sink material selection in electronic devices by computational approach. Adv. Eng. Mater. 10, 400–405 (2008)

    Article  Google Scholar 

  4. M.A. Gaynes, H. Shaukatullah, in Evaluation of Thermally Conductive Adhesives for Bonding Heat Sinks to Electronic Packages. 1993 43rd IEEE Electronic Components & Technology Conference (1993), pp. 765–771

  5. S.K. Kang, S. Purushothaman, Development of conducting adhesive materials for microelectronic applications. J. Electron. Mater. 28, 1314–1318 (1999)

    Article  Google Scholar 

  6. O. Kueckmann, Light-Emiting Diodes: Research, Manufacturing, and Applications X, High Power Led Arrays—Special Requirements on Packaging Technology—Art. No. 613404 (2006)

  7. P.J. Wang, J.S. Kim, D. Kim, C.C. Lee, Fluxless bonding of silicon wafers to molybdenum substrates using electroplated tin-rich solder. J. Mater. Sci.: Mater. Electron. 20, 334–342 (2009)

    Google Scholar 

  8. W.P. Lin, D.E. Wesolowski, C.C. Lee, Barrier/bonding layers on bismuth telluride (Bi2Te3) for high temperature thermoelectric modules. J. Mater. Sci.: Mater. Electron. 22, 1313–1320 (2011)

    Google Scholar 

  9. S.J. Hsu, C.C. Lee, Fluxless tin bonding of silicon chips to iron substrates. J. Mater. Sci.: Mater. Electron. 24, 2890–2896 (2013)

    Google Scholar 

  10. K.L. Lin, S.Y. Chang, The morphologies and the chemical states of the multiple zincating deposits on Al pads of Si chips. Thin Solid Films 288, 36–40 (1996)

    Article  Google Scholar 

  11. K. Azumi, T. Yugiri, M. Seo, S. Fujimoto, Double zincate pretreatment of sputter-deposited Al films. J. Electrochem. Soc. 148, C433–C438 (2001)

    Article  Google Scholar 

  12. M.K.M. Arshad, I. Ahmad, A. Jalar, G. Omar, U. Hashim, The effects of multiple zincation process on aluminum bond pad surface for electroless nickel immersion gold deposition. J. Electron. Packag. 128, 246–250 (2006)

    Article  Google Scholar 

  13. K.J. Zeng, R. Stierman, T.C. Chiu, D. Edwards, K. Ano, K.N. Tu, Kirkendall void formation in eutectic SnPb solder joints on bare Cu and its effect on joint reliability. J. Appl. Phys. 97, 024508 (2005)

  14. J.O. Suh, K.N. Tu, N. Tamura, Preferred orientation relationship between Cu6Sn5 scallop-type grains and Cu substrate in reactions between molten Sn-based solders and Cu. J. Appl. Phys. 102, 063511 (2007)

    Article  Google Scholar 

  15. J.O. Suh, K.N. Tu, G.V. Lutsenko, A.M. Gusak, Size distribution and morphology of Cu6Sn5 scallops in wetting reaction between molten solder and copper. Acta Mater. 56, 1075–1083 (2008)

    Article  Google Scholar 

  16. Y.-W. Yen, W.-T. Chou, Y. Tseng, C. Lee, C.-L. Hsu, Investigation of dissolution behavior of metallic substrates and intermetallic compound in molten lead-free solders. J. Electron. Mater. 37, 73–83 (2008)

    Article  Google Scholar 

  17. P.M. Hall, Creep and stress relaxation in solder joints, in Solder Joint Reliability Theory and Applications, ed. by J.H. Lau (Van Nostrand, New York, 1991), pp. 307–330

    Google Scholar 

Download references

Author information

Authors and Affiliations

  1. Electrical Engineering and Computer Science, Materials and Manufacturing Technology, University of California, Irvine, CA, 92697-2660, USA

    Shou-Jen Hsu, Chu-Hsuan Sha & Chin C. Lee

Authors
  1. Shou-Jen Hsu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Chu-Hsuan Sha
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Chin C. Lee
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Shou-Jen Hsu.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Hsu, SJ., Sha, CH. & Lee, C.C. Fluxless bonding of Si chips to aluminum boards using electroplated Sn solder. J Mater Sci: Mater Electron 25, 3276–3284 (2014). https://doi.org/10.1007/s10854-014-2014-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s10854-014-2014-z

Keywords

Search

Navigation