Electrochemical Migration of Sintered Nanosilver Under Chloride-Containing Thin Electrolyte Layer for Power Electronic Packaging

The electrochemical migration (ECM) of sintered nanosilver in thin electrolyte layers with various chloride concentrations was investigated by in situ and ex situ characterizations. There are two ECM products, i.e., the cloud-like layer and branched dendrites, in both electrolytes with 0 ppm and 10 ppm of NaCl. Only the dendrites, however, could be observed in 100, 200, and 300 ppm NaCl electrolyte layers. The cloud-like layer product is attributed to formation and reduction of Ag2O. However, the formation of Ag2O is inhibited by formation of AgCl in 100, 200, and 300 ppm NaCl electrolyte layers. No ECM products were present in 400 ppm NaCl electrolyte layer, but precipitates of silver compounds were because of formation of insoluble precipitates at anodes. A proposed mechanism has been discussed experimentally in order to understand the effect of Cl− on the electrochemical migration of sintered nanosilver.