Interactive Effects of Additives and Electrolyte Flow Rate on the Microstructure of Electrodeposited Copper Foils

An electrodeposition (ED) formula and approach are proposed to manufacture smooth copper foils on both the matte and shiny sides in this work. The interactive effects of additives and flow rate on the surface morphology of copper are investigated. The scanning electron microscopic images show that 3-mercapto-1-propanesulfonate (MPS) renders the formation of a densely deposited structure of Cu with clear grain boundaries. Polyethylene glycol (PEG) favors the formation of spherical clusters and suppresses the hydrogen evolution at high current density, meanwhile janus green B (JGB) shows distinctive flow-dependent influence on the microstructure of Cu foils. The roughness measurement shows that as the convection rises, the average particle size becomes smaller and the surface roughness becomes coarser if JGB is not introduced in the plating bath. On the other hand, JGB can flatten the surface under high flow rates because stronger convection may weaken the inhomogeneous distribution of JGB caused by current distribution. Therefore, azole compounds with positive charges are good additives to achieve a smooth surface of Cu foils since the bath convection is extremely strong under the practical manufacturing environment of Cu foils.