Loading...

Simulation of Coarsening in Tin/Lead Solders by Using Phase Field Method

Tavakoli, Mohammad Mahdi | 2011

632 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41777 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Davami, Parviz; Ashouri, Hossein
  7. Abstract:
  8. Soldering is one of the important methods in joining techniques which has wide applications in industries such as microelectronic. Today, the physical and mechanical properties of solder joints is very important because the dimensions of electronic devices are decreasing that cause to increasing of their current density. One of the important problems of high current density in solder joints is the microstructures of solders in microelectronic components, change over time that is weakened the properties of the solder alloy. This study presents a quantitative model , which is capable to simulation phase separation and coarsening phenomenon in Tin/Lead Solders. This model is based on continuum theory and extended diffusion equation of the phase field model that were evaluated using the most recently available data for the free energy of the tin/lead system, diffusional and mobility coefficients as well as surface tensions of both phases. The model presented allows us to study the influence as well as the interaction between classical diffusion of the Fickean type, surface energies according to Cahn and Hilliard on phase separation and coarsening. In this study, the mathematical model is analysed with fourier transform and exponential time stepping methods and the numerical model is solved by C programming code. An attempt is made to compare the temporal development of a eutectic Sn/Pb microstructure at different temperature levels as predicted by the model to actual experiments. The results of this investigation are showed the capability of simulation in prediction of microstructural evaluation. For quantifying the microstructure of simulation and experimental, equivalent diameter of phases and the total interface length per unit area (Γ) is taken as a quantifiable number to be compared. After quantifying both experimental micrographs and the numerical simulation, expotent of phase coarsening and the yet unknown mobility of soler alloy (M) is first extracted from the results. This is done by fitting the development of M for the simulation to that for the experiment using only the mobility. In continuing this study, for evaluating the effects of phase coarsening on the properties of solder alloy, we designed mechanical and physical tests, and the results showed that phase coarsening process has harmful effects on the properties of pb-sn solder alloy.
  9. Keywords:
  10. Simulation ; Lead-Tin Solder ; Coarsening ; Phase Field Model ; Phase Coarsening

 Digital Object List

 Bookmark

No TOC