Page 35 - PCMI Summer Journal 2021
P. 35
An Overview of the Operation of Ferric Chloride Regeneration Systems in Photochemical Etching Machines Presented by: Kirk Lauver, the Marketing Specialist, Chemcut Corpor7a/t2io7n/,2U1S
9
ORP Electrodes: Ag:AgCl And Platinum
• Two electrodes, one is platinum, and the other is a silver-silver chloride reference electrode
• Other than physical damage the platinum electrode has infinite life
• Migration of etching solution through the porous “bridge” will eventually cause the reference electrode to fail.
• Failure usually appears as a slow response or an unchanging redox value
8
Oxidation-Reduction Potential
• Keep a spare set of electrodes on hand
• Check the ORP in the etcher once a week using the spare electrodes or a handheld ORPmeter. ±10mv=OK
• Use an ORP setpoint in the stable range
Issue 137 August 2021 PCMI Journal 35
