Page 37 - PCMI Summer Journal 2021
P. 37
An Overview of the Operation of Ferric Chloride Regeneration Systems in Photochemical Etching Machines
Presented by: Kirk Lauver, the Marketing Specialist, Chemcut Corporation, US
7/27/21
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• Easy to control
• Sometimes done manually in low volume systems
• Automatic control is either an “On-Off” control or analog
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• The most difficult parameter to control,
• Most common control method is a proportional addition of hydrochloric acid when the regeneration is active. (usually time based).
• Control using pH instrumentation is possible. Electrode maintenance and calibration is critical.
• Control has also been done using a toroidal conductivity probe, but more factors can cause drift than pH. Conductivity works best in etchant that is used for one family of alloys. Not recommended for sodium chlorate regeneration.
• Regardless of the control method, titrations MUST be done to verify the free acid and calculate any manual “top up” additions.
(Dr. Allen’s Webinar, PCMI Journals Spring 1986, and Fall 1987 for methods)
Issue 137 August 2021 PCMI Journal 37
