A materials design tool for developing Pb-free soldering alloys in electronic package was developed based on comprehensive experimental data of phase equilibria and thermodynamic properties data accumulated with the CALPHAD (calculation of phase diagrams) method and contains 10 elements, namely, Ag, Au, Bi, Cu, In, Ni, Sb, Sn, Zn and Pb. It can handle the calculation of phase diagrams in all combinations of these elements and all composition ranges. In addition, based on this tool, the liquidus, solidus, phase fractions and constitutions, equilibrium and non-equilibrium solidification behavior, surface tension and viscosity of liquid, diffusion reactions and microstructural evolution, etc. can be predicted. Typical examples of the calculation and application of this tool are presented. The design tool is expected to be a powerful tool for the development of Pb-free solders, as well as for promoting the understanding of the interfacial phenomena between Cu substrate and Pb-free solders in electronic packaging technology.
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