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id m0uqLPz-0000NqC; Tue, 13 Aug 96 10:30 CDT |
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| From [log in to unmask] Tue Aug 13 10: |
40:00 1996 |
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<"1j416.0.Mu7.zz94o"@ipc> |
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We etch inner layers using Cupric Chloride Etchant. We control the
chemistry with ORP and Conductivity probes. The ORP adds Sodium
Chlorate and the Conductivity controls HCl adds.
We have experienced gas generation (chlorine or HCl fumes) when both
the ORP and Conductivity are in control. The gas/fume release occurs
when the copper gets as high as 33 - 35 ounces per gallon.
Standard procedure is to feed copper into the system when a chemical
out of balance situation results in gas generation. Clearly in this
case this would be the wrong thing to do.
Can anyone explain the chemical reaction behind a release of gas/fumes
when the copper is high?
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