Preparation and sintering characteristics of nano-silver wrapped tin paste

Abstract Nanosilver paste, an interconnect solder is a common choice in the electronics packaging industry, however higher sintering temperatures and lower sintering strength limit its application. At present, core-shell nano-slurry has been studied and applied to chip interconnection. Based on the mechanism of heterogeneous flocculation, we have developed a new nano-silver wrapped tin paste (Sn@Ag paste), and according to the decomposition temperature of the organic dispersant in the slurry, A corresponding sintering process with a maximum temperature of 300 ° C was developed. The Sn@Ag core-shell structure makes Sn have good dispersibility and oxidation resistance, and the sintered product of the slurry is a mixture of a solid solution of Ag and an Ag 3 Sn phase. Among them, the hard and brittle phase Ag 3 Sn acts as a dispersion strengthening effect in the Ag matrix phase, and the solid solution of Ag acts as a replacement solid solution strengthening. With the increase of doping Sn content, the sintering strength is significantly improved. When the Sn content is 5%, the joint shear strength reaches the highest value of 50Mpa, which is higher than the pure nano silver paste by 10 Mpa. This new nano-silver wrapped tin paste technology has the characteristics of low temperature sintering and high temperature service, so it is expected to be widely used in semiconductor power devices.