CoSn3 Intermetallic Nanoparticles for Electronic Packaging

Abstract

At present, composite solder pastes are getting a lot of attention, especially composite Sn based solders reinforced by nanoparticles. Indeed, CoSn3 is a strong nucleating agent of Sn crystal, which has potential application value in the field of electronic packaging. However, there is no reliable synthetic path for CoSn3 nanoparticles at present. In this article, a chemical synthesis method for CoSn3 nanoparticles is developed. Here, CoCl2 and SnCl2 are reduced by NaHB4 in triethylene glycol (TEG), dispersed by ultrasonics, and heated to 350 °C in a tube furnace for growth. The CoSn3 nanoparticles with a diameter of about 150 nm are obtained by heating at 350 °C for 10 min. The CoSn3 nanoparticles undergo a step reaction in the process of synthesis and go through different stages of merging and annexation during their growth. The crystal growth behavior and the process of orientation change during the nucleation and growth of CoSn3 nanoparticles are studied, especially the two growth mechanisms, namely OU (orientation unified) and OA (orientation attached). By mixing CoSn3 nanoparticles with SAC305, we obtain a kind of strengthened composite soldering paste. There are obvious six-fold cyclic twins in the joints made by this soldering paste.

A Study of Electroplated Nanoporous Copper Using Aberration-Corrected Transmission Electron Microscopy

“…Figure 1 shows that the deposition potentials of Zn and Cu shift negatively with the addition of the complex (pyrophosphate), thus suggesting that the addition of the complex during deposition is beneficial because it allows the reduction potential of Cu 2+ to approach that of Zn 2+ ; thus, the co-deposition of Cu and Zn occurs. TEM observations of the cathode reveal that Zn 2+ and Cu 2+ are preferentially reduced near the cathode to particles with a diameter of approximately 10 nm; this nucleation occurs as soon as the ions come into contact with the cathode, and the nucleated Cu-Zn nanoparticles are captured by the plating layer by means of “orientation attachment” [ 17 , 18 ]. The size of the plating layer increases as the surrounding nanoparticles are consumed.…”

Effect of CoSn3 nanocrystals on Sn3Ag plating for electronic packaging

“…CoSn3 nanoparticles (Fig. 2) were prepared by thermal synthesis and the detailed preparation method we published in [15].…”