Influence of Al2O3 Nanoparticles on the Morphology and Growth Kinetics of Cu-Sn Intermetallic Compounds in Sn-Ag-Zn/Cu Solder Joints

Intermetallic compounds (IMCs) growth can simultaneously bring about low-resistance electrical pathways and drastically reduce joint lifetime. Recently, incorporated trace nanoparticles into the free-Pb solder were found to promote the performance of the solder joints. Sn3Ag0.9Zn (SAZ) nano-composite solders were developed by doping 0.5 wt.% Al2O3 nanoparticles into the SAZ solder. The IMCs formation and growth behavior at the interfacial reactions between the SAZ-0.5Al2O3 nano-composite solder and the Cu substrate during soldering at temperatures ranging from 250 to 325 °C for 30 min were investigated. The results showed that after the addition of Al2O3 nanoparticles into the SAZ solder, the elongated-type IMCs layer changed into a prism-type IMCs layer, and Ag3Sn nanoparticles were absorbed on the grain surface of the interfacial Cu6Sn5 phase, effectively suppressing the growth of the IMCs layers. The activation energies (Q) for the IMCs layers (Cu6Sn5 + Cu3Sn) were determined to be 36.4 and 39.1 kJ/mol for the SAZ/Cu and SAZ-Al2O3/Cu solders, respectively.