Influence of current and combined thermo-current load on microstructure and resistance of solder joints

The aim of our work is to evaluate an influence of current and combined thermo-current load on microstructure and electrical resistance of solder joints. The solder joints formed on bare Cu printed circuit board pads were long-term loaded by large current and high temperature. The obtained results clearly show that the both load methods significantly affect microstructure and electrical resistance of the joints. The both loads lead to a formation of extensive voids in the solder joints due to the effect of electromigration thus causing evident increase of their resistance. The resistance increase is more significant for the joints loaded by the combined thermo-current load.