Hostname: page-component-669899f699-8p65j Total loading time: 0 Render date: 2025-04-25T06:15:39.140Z Has data issue: false hasContentIssue false
  • English
  • Français

Stresses in Polyimide Films during Cure and Thermal Cycling

Published online by Cambridge University Press:  15 February 2011

David J. Monk ,
Yongxiang He  and
David S. Soane
David J. Monk
Affiliation:
Department of Chemical Engineering, 201 Gilman Hall, University of California, Berkeley, CA 94720, (510) 642–0958, FAX (510) 642–7798
Yongxiang He
Affiliation:
Department of Chemical Engineering, 201 Gilman Hall, University of California, Berkeley, CA 94720, (510) 642–0958, FAX (510) 642–7798
David S. Soane
Affiliation:
Department of Chemical Engineering, 201 Gilman Hall, University of California, Berkeley, CA 94720, (510) 642–0958, FAX (510) 642–7798
Get access

Abstract

Several electronics packaging schemes involve polymer/inorganic interfaces, including: dual-in-line packages, tape automated bonding and multilayer interconnects. Typically, the thermal expansion coefficients are disparate, so these interfaces often cause high stress. Therefore, a phenomenological model describing transient stresses in spin-coated polyimide films was developed. The model is based on linear viscoelastic theory, and it accounts for shrinkage caused by solvent evaporation and imidization, viscoelastic relaxation, and thermal expansion mismatch. Strains have been defined from three mechanisms: thermal expansion mismatch, chemical curing, and solvent evaporation. Stress is, then, calculated by using the Classical Maxwell Model with one element. The concept of free volume is used throughout the model to estimate viscosity, modulus, and other quantities related to calculating strains. Model predictions for stress as a function of temperature during film cure and thermal cycling are fit with experimental data obtained from a bending beam apparatus.

Stress has been estimated by using the thin film approximation of the Timoshenko bilayer stress equation. Experimental data agree well with wafer bowing stress measurements. Although the technique does not yet take into account changing polyimide thickness during curing, the results still show qualitative curing dynamics. This preliminary study revealed good agreement between predicted and observed effects of material properties on stresses developed during cure and thermal cycling. Specificially, an unexpected high in-cure stress was observed for a standard low CTE polyimide. High stresses during curing can be as detrimental to an electronics device as high stress during device operation, so this technique may be useful when screening polyimides and/or prescribing curing schedules. Future work will improve the predictive capability of the model.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 264: Symposium G – Electronic Packaging Materials Science VI , 1992 , 175
Copyright
Copyright © Materials Research Society 1992

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.)

Article purchase

Temporarily unavailable

References

1. Klopfenstein, A. G., Tummala, R. R., and Rymaszewski, E. J. Eds., Microelectronics Packaginag Handbook (Van Nostrand Reinhold, New York, 1989).Google Scholar
2. Soane, D. S. and Martynenko, Z., Polymers in Microelectronics: Fundamentals and Applications (Elsevier, New York, NY, 1989).Google Scholar
3. Edelstein, S., (private communication), 1991.Google Scholar
4. Biernath, R. W., Ph. D. Thesis, University of California, Berkeley, 1990.Google Scholar
5. Timoshenko, S., J. Opt. Soc. Am. 11, 233 (1925).CrossRefGoogle Scholar
6. Monk, D. J., He, Y., and Soane, D. S. in American Society of Mechanical Engineers Winter Annual Meeting, (ASME, Atlanta, GA, 1991), pp. 87.Google Scholar
7. Lipatov, Y., Adv. Polym. Sci. 26, 63 (1978).CrossRefGoogle Scholar
8. Bilimeyer, F. W. Jr., Textbook of Polymer Science (John Wiley & Sons, New York, 1984).Google Scholar
9. Ferry, J. D., Viscoelastic Properties of Polymers (John Wiley & Sons, New York, 1961).CrossRefGoogle Scholar
10. Chow, T. S., J. Rheol. 30, 729 (1986).CrossRefGoogle Scholar
11. Kreuz, J. A., Erdrey, A. L., Gay, F. P., and Sroog, C. E., J. Polym. Sci. A-1, 2607 (1966).CrossRefGoogle Scholar
12. Huguenin, F. G. A. E., and Klein, M. T., Ind. Eng. Chem. Prod. Res. Dev. 24, 166 (1985).CrossRefGoogle Scholar
13. Croll, S. G., J. Appl. Poly. Sci. 2 847 (1979).CrossRefGoogle Scholar
14. Biernath, R. W. and Soane, D. S., in Stress Development in Thin Films of Polymeric Interlayer Dielectric and Packaging Materials University of California, Berkeley, pp. 147.Google Scholar
15. Doolittle, A. K., J. Appl. Phy. 22, 1471 (1951).CrossRefGoogle Scholar
16. Biernath, R.W. and Soane, D. S., in Polymeric Materials for Electronics Packaging and Interconnection, edited by Lupinski, J. H. and Moore, R. S. (American Chemical Society, Los Angeles, CA, 1989), pp. 356.CrossRefGoogle Scholar
17. Nguyen, L. T., in New Characterization Techniques for Thin Polymer Films, edited by Tong, H.-M. and Nguyen, L. T. (John Wiley & Sons, Inc., New York, NY, 1990), pp. 57.Google Scholar
18. Tong, H.-M. and Saenger, K. L., in New Characterization Techniques for Thin Polymer Films, edited by Tong, H.-M. and Nguyen, L. T. (John Wiley & Sons, Inc., New York, NY, 1990), pp. 29.Google Scholar
19. Pottiger, M. T., (IPC Task Group Meeting, Denver, 1992).Google Scholar
20. Day, D. R., Ridley, D., Mario, J. and Senturia, S. D., in Polyimides: Synthesis. Characterization. and Applications, edited by Mittal, K. L. (Plenum Press, New York, NY, 1982), pp. 767.Google Scholar
21. Monk, D. J., unpublished notes (Rockwell International, 1986).Google Scholar
22. Lee, C., (private communication), 1991.Google Scholar
23. Hendricks, N. H., (private communication), 1991.Google Scholar
24. Amoco, , Ultrade1 3112 Coating (Amoco Chemical Company, Chicago, IL, 1991).Google Scholar