Think & Tinker, Ltd.
P.O. Box 1606, Palmer Lake, CO 80133
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Chemical Analysis/Copper Concentration Analysis
Copper Concentration Analysis
If you have not done so, please read the DOs and DON'Ts section now.
Copper concentration (g/L) = 0.127 x NumCop
The presence of too much dissolved copper in the etching bath will lead to excessive etch times, accelerated peroxide consumption and a reduction of the edge quality of an etched circuit. This analysis will need to be performed after every 30 sq.ft. of copper clad is etched and should be done on a Friday or at any time that the etcher can be idle for one or two days. A marked increase in the consumption of hydrogen peroxide is a fairly reliable indicator that there is too much dissolved copper in the etchant. Careful attention to your logbook will alert you when the need for this test is becoming critical.
The acceptable range of NumCop is
A reading in excess of 450 drops indicates that the bath has become supersaturated with copper. To prevent accelerated H2O2 consumption and spontaneous precipitation of copper sulfate in the etching tank, the excess dissolved copper should be precipitated out of the bath.