Effect of gelatin and chloride ions on the mechanical properties and microstructural evolution of copper foil

This study investigated the crystal structure and mechanical properties of copper foil electroplated by adjusting gelatin and chloride ions from 0 to 100 ppm. There was increased formation of spherical crystals and surface roughness on the surface of the electroplated layer when the gelatin was added, and the direction of crystal growth was parallel to the (111) plane. The grain size of the copper foil electroplated in the electrolyte containing 30~60 ppm of gelatin was smaller than that of groups with no additive. As a result, hardness increased, but elongation decreased. In contrast, the elongation and the crystal size of copper foil formed in the electrolyte containing chlorine ions increased more than the group with no additive. The clearly observed tendency was that crystals of the group with no additive as well as the group with added chloride ions grew along the (220) plane. However, the use of the electrolyte with chlorine ions and gelatin additives was not enough to obtain a uniform surface and desirable mechanical properties in the electroplated layer. The addition of a leveler and brightener could be used to fabricate useful copper foil. The tensile strength was similar for the no additive group and mixed additive group. However, it was observed that the grain size of the mixed additive group elongated 34.1% more than the no additive group.