AU(III) IN BORATE MEDIUM - ELECTROCHEMICAL-BEHAVIOR AND APPLICATION TO ELECTROPLATING

A well-defined steady-state current for the reduction of gold on a gla ssy carbon microdisk electrode is obtained from berate medium. Coulome tric experiments show that this current is due to the reduction of gol d(III) to gold(0). This current is proportional to the concentration o f gold(III) and suitable for analytical purposes. Gold(III) is more st able in berate electrolytes than in solutions of an indifferent electr olyte at the same ionic strength and pH. However, UV-vis spectrometry and pH-metric titrations suggest that berate does not form stoichiomet ric complexes with gold(III). This medium yields an excellent quality of deposit on test masks with feature size in the range of 5 to 250 mu m and highest aspect ratio 1:1.