Diffusion processes in lead based solders used in microelectronic industry

Abstract

We have compiled parameters for 203Pb and 119Sn radiotracer diffusion in Pb, Pb-Sn binary, Pb-Sn-Cu, and Pb-Sn-Au ternary alloys in the lattice and in the grain boundaries. These isotopes represent the major elements of the solders. At a temperature of 80 °C which is commonly observed during the use of solders in microelectronic applications, diffusion in both the lattice and grain boundaries have been found to be sizable so that effective diffusion coefficients need to used for estimation of reliability due to processes such as the cyclic creep, electromigration, thermomigration etc. Significant reduction in the effective diffusion coefficients have been observed upon additions of ternary solutes such as Cu and Au.