Page 58 - PCMI Journal December 2021

Maintenance Tips For PCM Etching Equipment
Kirk Lauver, Marketing and Customer Lab Manager, Chemcut Corporation, US
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12/6/21
Maintenance Tips For PCM Etching Equipment
The Impact Of Chemistry On Maintenance Conclusions of Dr. Allen and Dr. Impey
• The chemical composition of scale comprises mainly oxides of silicon.
• Scale is a breakdown product or constituent of the insoluble byproducts of ferric chloride
etching of metals.
• These deposits may be part of the coloured deposits known as "smut" only seen on etched metal surfaces. However, spray etching at high pressures can wash such deposits into the etching machine sump where they might aggregate and solidify to form scale.
• Scale deposits appear to be a very real threat to high quality PCM due to the disruption of the etchant hydrodynamics.
• No real solution exists to solve the problem, but it is recommended industrial practice to try to remove them by dissolution in strong hydrochloric acid or a power water spray at regular intervals, preferably at least once a month.
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Maintenance Tips For PCM Etching Equipment The Impact Of Chemistry On Maintenance
Hard Scale
It’s usually worse in machine that use regeneration, because the etchant reaches the highest silicon level.
Varies based on the alloys processed.
Could possibly be reduced by adding fresh ferric on a regular basis.
• To do it correctly would require regular bath analysis.
• Maximum levels of silicon are not established
Issue 138 December 2021 PCMI Journal 58
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