The transition from microthrowing power to macrothrowing power in electrodeposition from a cyanide copper bath

Abstract

Cylindrical cathodes containing microgrooves of various widths and depths were electrodeposited with copper from a cyanide copper bath. The uniformity ratio, hr/hp (where hr is the thickness of deposit on the recess of a groove, and hp a similar parameter for the peak), was measured in a microscope with an eyepiece micrometer. The ratio was found to vary with groove width (at constant depth), with groove depth (at constant width), and also with current density and bath temperature. The results demonstrate a transition from poor "microthrow" to good "macrothrow" when the groove width is of the order of the thickness of the diffusion layer. Rotation of the cathode during electrodeposition leads to levelling on wide grooves (0·008-0·009 in.) (0·2032-0·2286 mm) probably due to greater turbulent transport inside the grooves.