Preparation of nano Cu@Ag core shell powder for electronic packaging

Nano Cu@Ag core-shell powders for electronic packaging were prepared by Liquid phase reduction method. The core-shell powders were characterized by XRD, SEM and TEM. The key problems in the experiment were presented some resolvable solution, and the coating process was optimized. The results showed that the dispersant PVP was added to make the dispersion effect better or the selection of stirring speed could not be too small, which could avoid the agglomeration of coating powder. In view of the incompleteness of powder coating, first of all, the amount of Ag should not be too small, if the amount of Ag was small, the coating was incomplete, then the mixing rate could not be too large, which the integrity of the coated powder would be destroyed. To solve the plethoric product impurities, firstly, PVP concentration could not be too high, otherwise, it would be residual. Secondly, the amount of reactive Ag could not be excessive, and it was as far as possible to ensure that all Ag coated on the surface of Cu powder. The process optimization results showed that the range of PVP concentration was between 5 g/L and 10 g/L, Cu/Ag molar ratio n _Cu :n _Ag =7:1, and the stirring speed of the solution was controlled at about 3000 r/min. The Cu@Ag core shell powder prepared had good dispersion and encapsulation effect.