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NOVEMBER 2022 I PCB007 MAGAZINE 47 References 1. "Process Guidelines for Cupric Chloride Etch- ing," Chemcut.net Christopher Bonsell is a chemical process engineer at Chemcut. To read past columns, click here. regulations and safety precautions add up to making it more expensive than the counter- part options. If you do get the opportunity to use Cl 2 for regeneration, you should note that feeding it into your etching system will be a different process than the previous options. To bring the Cl 2 into your etching solution you will need to pull it into your etcher by vacuum. is vac- uum will pull the Cl 2 from the storage tank and introduce it to the spent etchant via sparging or feeding into a recirculating loop (see Fig- ure 3). is feeding method is a safety measure to prevent major releases of Cl 2 in case there is a leak in one of the connections between the tank and the etcher. Summary Regenerating CuCl 2 can be relatively sim- ple, and it is mostly a matter of picking which option you want. Which option you choose will likely depend on your location. e best option to go for is chlorine gas regeneration because it is cost-effective, but depending on your location, there may be too many regula- tions and barriers to entry for that to be a fea- sible option. If Cl 2 is not a valid choice for you, then the other two options can come down to many different factors that can be unique to your process. With the information I have pro- vided, you should be able to make an informed decision about which one would suit your cupric etch process best. PCB007 Figure 3: A free-standing regeneration unit designed to pull chlorine gas in by vacuum and introduce the gas into the etchant.