Effect of an electric field on microstructure coarsening in 60Sn40Pb solder joints

The influence of an electrostatic field E=15 and 25 kV cm−1 on the microstructure coarsening in 60Sn40Pb solder joints annealed at 150 °C was determined. Without a field the following were found: (a) the eutectic Pb and Sn phase size distributions (PSDs) fit the Bitti–DiNunzio model, (b) the phase size coarsening time exponent m=0.25 and (c) the intermetallic compound (IC) growth time exponent p=0.33. The field had only a slight effect on the PSDs and on the time exponents m or p; it, however, retarded significantly the rates of phase coarsening and of IC growth. The mechanism by which the field produced the retarding effects is not clear. A likely possibility is that it reduced the governing diffusion coefficient.