Study on Thermal Stability of Dendritic Silver-Coated Copper Powders Fabricated by Galvanic Displacement Reaction

Metals of Group IB due to their higher electrical and thermal conductivities have been thoroughly studied. Particularly, silver electronic slurry extensively used as electrode material in various resistance devices and electromagnetic interference(EMI) shielding materials. But Ag ions cause electro-migration phenomena in hot and humid conditions, which results in decreasing the conductivity and increasing the coating resistance in certain conditions. Copper relatively lower in cost and having good conductivity as silver, but the problem is copper oxidizes when exposed to air. To prevent oxidation of copper, silver coating on copper powder have been reported in many articles.

  In structural perspective, the dendritic structure has many superior properties, such as large surface area and good conductivity. Therefore, it is commendable to explore the mechanism of dendritic copper metallic materials formation.

  In this presentation, we are reporting a simple fabrication method for copper powder and silver coated copper powder with dendritic morphology at low temperature. To improve the dendritic structure, the galvanic displacement reaction and hydrogen evolution reactions have been applied together. The formation mechanism of Cu dendritic structures on the basis of effect of concentration, termination time, anion concentration, and additives have been prudently analyzed. In addition, we have also analyzed the thermal stability of silver-coated copper powders performance at different temperature.

Figure 1. SEM images of (a) dendritic copper powders and (b) cross section of silver-coated copper powders fabricated by galvanic displacement reaction.

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