Interface reaction between Ag-Pd conductor and Pd-Sn solder

The intermetallic compound layer between Pb-Sn solder and Ag-Pd conductor after aging at 150 °C has been studied. Elemental and phase distributions of this layer has been probed using SEM, EPMA and EDX. The investigation of the microstructure of the layer with EPMA liner analysis reveals segregation of Ag-rich and Pd-rich phases Quantitative EDX analysis results show that the Ag-rich phase contains Ag and Sn with the Ag/Sn ratio around 3/1, and the Pd-rich phase Pd and Sn with the Pd/Sn ratio around 1/4. These phases are confirmed to be the intermetallic compounds Ag
3
Sn and PdSn
4
, respectively.