Page 42 - PCMI Summer Journal 2021

An Overview of the Operation of Ferric Chloride Regeneration Systems in Photochemical Etching Machines Presented by: Kirk Lauver, the Marketing Specialist, Chemcut Corporation7, /U2S7/21
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• Popular in Europe and parts of Asia
• High initial cost
• Because of the constant circulation of solution between the regeneration cell and
the etching machine, it is often installed near the etcher. Remote installations have also been done. Floor space may be an issue: cells, transformers and tanks
• Systems are often designed to allow the cells to operate overnight to fully regenerate the etching solution for the next day’s operation
• ORP value determines when the cell is in the regeneration mode.
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• The chlorine source is hydrochloric acid
• Hydrochloric acid is added to the left side of the cell along with some sodium chloride to improve the cell’s performance
• Ferric chloride etching solution from the etcher follows through the right side of the cell
• Hydrogen gas is given off from the left side of the cell
• The chloride ions move through the special membrane towards the anode where ferrous chloride is converted back into ferric chloride
• Theoretical HCl required for 1 Kg of metal dissolved is 5.36 liters of 20° Be’ HCl (31.5% at 1.16 Sp.Gr.), plus etcher and cell ventilation losses
Special Chloride Ion Permeable Membrane
Issue 137 August 2021 PCMI Journal 42