Abstract
It was found that KCNS, SeO2 and As2O3 in the copper cyanide plating bath were the most suitable brighteners as observed from cleanness of reflection image.
The range of brilliance was studied to decide the best composition and working condition when SeO2 brightener was used. At the same time, the potassium copper cyanide bath was compared with the sodium copper cyanide bath. The result is as follows:
The range of brilliance is wide and the current density high with high copper concentration, low free alkali cyanide, high K+ concentration, and high temperature.
Furthermore, it is better to use potassium copper cyanide bath than sodium bath.
For the reason above, it is recommendable to use bright copper cyanide bath under the following condition:
Bath Composition
Cu 60-70g/l
free CN- 5-10g/l
KOH 20g/l
SeO2 1g/l
Working Condition
Temperature 70-75°C
Current density 2A/dm2
It is also revealed that, by stirring the bath, higher current density can be used for wider range of brightness.
