Fabrication and Performance Test of Nano Cu@Ag Core-Shell Particles for Power Device Packaging

In this paper, a green and pollution-free method was developed to plate a silver layer on the surface of copper cores with diameter of
$17.4\pm 0.56$
nm through replacement reduction reaction. Finally, Cu@Ag core shell nanoparticles charactered by low proportion, dense and uniform Ag shell, as well as good antioxidant property were obtained by adjusting the ratios of copper and silver elements in the reactants. Results showed that the addition of dispersant PVP and excess reducer glucose during the synthesis of Cu@Ag nanoparticles can improve not only the quality of the plating layer, but also the antioxidant properties of the Cu@Ag core shells attributed to the residual of these organic substances with reducing properties, which allowed them to be placed in the air for 40 days without oxidizing at a high temperature of
$20 0^{\circ}\mathrm{C}$
, and even maintain good thermal stability at
$235. 4^{\circ}\mathrm{C}$
in the case of a Cu to
$\text{AgNO}_{3}$
ratio of 4: 1 in the reactional solution. This is quite significant for the reliability improvement of power department device packaging.