Nanocomposite Solders: an Influence of un-coated and Au-coated Carbon Nanotubes on Morphology of Cu / Sn-3.0Ag-0.5Cu / Cu Solder Joints

This study is devoted to the effect of minor admixtures of carbon nanotubes and Au-coated carbon nanotubes on the microstructure of solder/copper joints. The paste of solder Sn3.0Ag0.5Cu (known as SAC305) reinforced with 0.001, 0.003 and 0.005 wt.% of nanosized additions has been prepared as solder material. A microstructure of the solidified solder/copper joints was investigated by SEM. It was revealed that admixtures of the carbon nanotubes slow down the increase of the intermetallic layer Cu
₆
Sn
₅
, formed at the interface solder/copper. This effect was found in all studied uncoated and Au-coated carbon nanoparticles and could be connected with adsorption of nanoinclusions on the surface of grains in course of solidification. A comparison analysis revealed that the most favorable effect was obtained by adding of carbon nanotubes coated with Au to the SAC305 solder paste.