The development of a mathematical model of the soldering process of actual pastes as used in surface mount technology (SMT) lines is described in this paper. The coupled heat transfer processes between the solder paste and the flux including changes in solder paste properties are considered in the model. Specifically, the loss of solvents in the vehicle system, melting, solidification and further single phase cooling of the solder paste are contemplated in the model. Experiments were conducted with the objective of validating the predictions of the solder paste temperature profile and of the loss of weight due to flux extraction. Results are shown in this paper for typical eutectic paste 63%Sn-37%Pb and experimental data is in good agreement with the numerical predictions. Simulations using the lead-free solder paste systems 96.5%Sn-3.5%Ag and 42%Sn-58%Bi are also reported in this paper. The proposed model is suitable for incorporation into existing three dimensional heat transfer models of PCBs for simulations in ovens with similar characteristics as those used in actual manufacturing applications.

Hwang, J. S., 1996, Modern Solder Technology for Competitive Electronics Manufacturing. Sec. 7.1. pp. 209, Sec. 8.2.3. pp. 231, The McGraw-Hill Co., New York, NY.
Chen, S.-W., C.-C. Lin, and C. C. Chen, 1997, Determination of the melting and solidification characteristics of solders using differential scanning calorimetry. Metallurgical and Materials Transactions. Vol. 29A, pp. 1965–1972.
King, C., and T. S. Ong, 1993, Development of a no-clean solder paste. Circuit World. Vol. 19, No. 4. pp. 44–47.
Pe´rez, H., A. Marrero, and J. E. Gonzalez, 1999, Study of the thermal behavior of PCB’s during reflow in SMT lines. Proceedings of the 5th ASME/JSME Joint Thermal Engineering Conference, San Diego, California, March 15–19.
Manko, H. H., 1986, Soldering Handbook for Printed Circuits and Surface Mounting. The Van Nostrand Reinhold Company Inc., New York, NY. Pp. 182.
Martin, H., D. Brian, S. Whitaker, and H. H. Winter, 1977, Heat and mass transfer between impinging gas jets and solid surfaces. Advances in Heat Transfer, Vol. 13, pp. 1–60.
Pe´rez, H., 1998, “Study of the Thermal Behavior of a Printed Circuit Board During the Reflow Process Inside a Surface Mount Technology Oven,” M.Sc. Thesis, University of Puerto Rico-Mayaguez.
Eftychiou, M. A., T. L. Bergman, and G. Y. Masada, 1992, Thermal effects during infrared solder reflow-Part II. A model of the reflow process. Journal of Electronic Packaging, Vol. 114, pp. 48–54.
Incropera, F. P., and D. P. DeWitt, 1990, Fundamentals of Heat and Mass Transfer, Wiley and Sons, New York.
Sarvar, F., and P. P. Conway, 1998, Effective modeling of the reflow process: Use of a modeling tool for product and process design. IEEE Transactions on Components, Packaging and Manufacturing Technology, Vol. 21, pp. 126–133.
Waldvogel, J. M., and D. Poulikakos, 1997, Solidification phenomena on picoliter size solder droplet deposition on a composite substrate. International Journal of Heat Mass Transfer. Vol. 40, pp. 295–309.
Boltz, R. E., and G. L. Tuve, 1973, CRC Handbook of Tables for Applied Engineering Science, CRC Press, Inc., Boca Raton, Florida.
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