Adam, You are likely to get as many answers to this question as there are people that have etched with cupric since the free acid parameters can be set from zero Normal to as high as 5 Normal in every day running etchers. Your regeneration system that you describe can work but simply pumping in room oxygen would not be fast enough to regenerate the working solution while average amounts of copper are being etched. The oxygen pumped would have to be under very high pressure and that poses a whole new set of problems. The answers to your questions are not trade secrets but I am curious...What is the end result of the project you are working on? Is this for scientific curiousity or for a practical project? You may contact me both on TechNet and offline to continue this discussion. Best regards, Phil Culpovich [log in to unmask] www.oxfordvue.com -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Adam Seychell Sent: Tuesday, April 08, 2003 8:52 PM To: [log in to unmask] Subject: [TN] cupric chloride parameters The CuCl2 +HCl is a new etchant I've been experimenting with in the lab. I am trying to develop a lab sized room temperature etching system that will be entirely regenerated with atmospheric oxygen and HCl/water additions. After many many hours of experimenting I have reached the conclusion that etching rate improves with increased dissolved copper(II), and around 160 ~ 180g/l showed to work nicely (specific gravity = 1.28). At 75g/l of copper the etch speed was 4 times slower. Surprisingly I also found the free HCl concentration has a relatively small effect on etch rate. It can etch happily without acid ! ... BUT, the copper(I) produced during etching is the grand etching killer. If copper(I) is allowed to get too high it forms a white film over the copper and can stop etching dead in its tracks. So, copper(I) is kept very low by bubbling air through the acidic solution, HCl present 0.1 to 0.5N. HCl + CuCl + O -> CuCl2 + H2O I have some questions on commercial CuCl2 etchers, such as operating parameters they use. What is the copper(II) concentration range, what is the specific gravity, and how much acid is in there ? What happens when copper gets too high, or when acid is too high ? Do my finding agree with those who have experience with CuCl2 etching ? I'm especially interested finding information on the characteristics of cupric chloride etching and how each component effects etch rate and performance. Is all of this trade secrets ? Adam Seychell. VIC, Australia. --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------