In recent years, metals with high specific surface area are widely used in the electrical and the electronics industries. Among them, Cu is attention due to its excellent electrical and thermal conductivities, good resistance to corrosion, good mechanical workability and low cost compared to other noble metals(Au, Ag, Pt, etc.).
Recently, synthesis of varioust metallic nanostructures with high specific surface area has become a hot subject for its broad applications in catalysis, fuel cell, gas sensor, and surface-enhanced Raman fields. Specifically, dendritic materials, consisting of a main stem and numerous side branches, receive significant attention in catalysis and technological fields.
The electrodeposition technique is very suitable for the preparation of such structures because it is possible to control the number, distribution, and pore size in these structures by the choice of appropriate electrolysis parameters. So we study, the growth behavior of dendritic copper powder in copper electroplating baths with or without additives by the electrodeposition method. Effect of bath type (CuSO4, CuCl2, Cu2P2O7), applied potential, plating time and type(PEG,JGB) and concentration of additives were studied.
The finer shape of dendrite was observed at high deposition overpotential due to “effective overpotential”. Therefore, the most fine dendritic copper was observed in the case of CuSO4 : -0.45V, CuCl2 : -0.6V, Cu2P2O7 : -1.45V. The shape of copper dendrite is related to the plating time, too. In the case of lower plating time the insufficient dendritic structure is observed and when the plating time increase above a critical value, for coarsening dendritic copper or shape changes of cauliflower-like. The dendrite depositing for 10 min showed the finest shape.
The apparent density and BET specific surface area were also measured. The finer dendrite has the less apparent density and the larger specific surface area. The shape factor of dendrite from copper chloride solution has the lowest apparent density value of 0.989g/cm3 and the largest specific surface area value of 1.81m2/g.
The effect of additive in the electrodeposition bath on copper film plating was widely investigated. But dendritic copper plating is not the case. In this work, effects of additives such as PEG(polyethylene glycol) and JGB(Janus Green B) have been studied because they can increase the overpotential of copper reduction reaction and decrease the deposition rate. The apparent density and BET specific surface area were measured. Both of the additives were larger specific surface area as the increasing concentration. Dendrite from JGB 80ppm solution has the lowest density and the largest surface(2.119m2/g) area among two additives, PEG and JGB.