Sn-rich phase coarsening during isothermal annealing for as-soldered Sn-Ag-Cu solder

The effect of Sn-rich coarsening in Sn-Ag-Cu solder joints produced by isothermal annealing was investigated. The isothermal annealing temperatures employed were from 30 to 150 A degrees C for 24 h up to 1,008 h of annealing time. An Infinite Focus Measurement system (IFMA (R)) and Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) were used for microscopic analysis and elemental analysis, respectively. As the annealing time and temperature increased, a eutectic component Cu, diffused into the Sn-rich phases, coarsening the Sn-rich phases, and the activation energy value for the coarsening was determined to be 41 kJ/mol.