Heterogeneous nucleation of tin in tin-silver-copper solder joints.

摘要

Experiments were conducted to examine the undercooling, and solidification kinetics, of near-eutectic Sn-Ag-Cu (SAC) alloys. The isothermal solidification of Sn in commercial SAC solder joints and in individual SAC samples on Cu and Zn substrates was monitored using thermal analysis. Classical nucleation theory was used to calculate the isothermal nucleation rate in samples with various thermal histories, and these rates were compared with predictions of the classical theory and with previously published data. Results show trends that are consistent with theory and suggest that nucleation in commercial samples is catalyzed heterogeneously by multiple impurities. Measured nucleation rates were relatively insensitive to samples' thermal history.