A Technique for Continuous Control of Cu+ Concentration in Copper Etching Baths
Original Publication Date: 1986-Mar-01
Included in the Prior Art Database: 2005-Mar-09
The Cu+ product of the etching of copper from boards and cards by cupric chloride is converted back to Cu2+ by a process of bubbling water-saturated air or oxygen into the etch bath. The bubbling rate of the water-saturated air or oxygen is controlled so that the Cu+ concentration can be kept low, and wide fluctuations in the etch rate and thus inefficient etching are completely avoided. This process eliminates the need for the purchas storing, and adding of oxidizing chemicals such as hydrogen peroxide H2O2 to the etch bath so as to convert Cu+ to Cu2+ . Bath dilution is also prevented, avoiding the need to dispose of etchant on a periodic basis.