Abstract
On the surface of graphite suspended in acidic solution, graphite-oxygen species are formed by anodic oxidation or by bubbling of ozonous air. These graphite-oxygen species on the surface of graphite are stable in the suspension solution and have a noble redox suspension potential. Based on this special character of graphite, the graphite-suspension which has such high oxidation ability could be applied to the etching of copper. The etching takes place only at the contact part with graphite, and then a troublesome undercut in etching can be prevented by controlling a size of graphite particles. The etching velocity of copper increases with increasing the amount of graphite and with diminishing in size of graphite, since the etching velocity depended mainly on the total surface area of suspended graphite particles at the same suspension potential. Then, the flow rate of suspension solution was increased in order to increase the etching velocity, but the increasing degree of etching velocity was limited by the reduction rate of oxygen species on graphite. The reduction rate depends upon the kind of graphite, and the ability can be experimentally evaluated by the cyclic voltammetry. The dissolved copper by this etching method can be easily recovered at cathode simply by an electrolysis of the solution without graphite particles.
