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Author: Subject: Etching a PCB using H2O2 and HCl - a few questions
Brightscales
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[*] posted on 1-10-2012 at 06:42
Etching a PCB using H2O2 and HCl - a few questions


Hi,
I've been told a good etchant for PCBs (copper, essentially) would be a solution of distilled water, 10% HCl and 2% H2O2. I wonder about the safety of handling this solution, as I've heard it may produce Chlorine gas. Either way, I will be conducting this experiment outside with proper eye protection, and some thick latex gloves. Also, my container is made out of plastic.

Moving on. I have a solution of 10% HCl prepared and also a solution of 3% H2O2 (very little of it, however) so I was also wondering about the ratios and how much of each should I use to create this solution (oh and, do I even need the water, or is it fine by itself since the HCl is already at 10%?)

Sorry about the "Chinese Wall of Text" there, but I'm slightly worried and would like to conduct this experiment ASAP.

Thanks.
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AJKOER
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[*] posted on 1-10-2012 at 07:10


There has been some discussion on this forum as to what exactly HCl/H2O2 is. The view is a cycling reaction acting as Chlorine water. I find per the reaction:

HCl + H2O2 --> HOCl + H2O

the the mixture acts like Hypochlorous acid, which is capable of dissolving Gold, and in even dilute solutions attacks Iron.

Avoid fumes (Cl2 and/or Cl2O), but all in all, not as dangerous, in my opinion, as strong H2SO4 or HF or HBr or H3PO4, and as it is effective in dilute solutions, much safer to work with.
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zed
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[*] posted on 3-10-2012 at 12:17


Seems to me that we used to do our board etching with a solution of Ferric Chloride.

Pretty easy to handle, very effective.
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CHRIS25
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[*] posted on 3-10-2012 at 13:08


Quote: Originally posted by zed  
Seems to me that we used to do our board etching with a solution of Ferric Chloride.

Pretty easy to handle, very effective.

ferric chloride has its problems, I would use copper chloride, just as good and a lot more efficient. I haver been doing a lot of etching in copper and use copper chloride, self-regenerating using an air pump so no need for expensive H2O2. Mixing HCL and copper is not dangerous at reasonably small quantities (under a couple of litres). Fumes are not an issue if etching is done in a ventilated area.

The H2O2 will become exhausted quite quickly, it depends upon how much copper you are putting into the solution.

If you need any specific help I can offer you a ton of information, I collected charts and information from discussions on this forum, they are all in PDF formats. If you have issues then I would be happy to send you the relevant PDF's.
[Edited on 3-10-2012 by CHRIS25]

[Edited on 3-10-2012 by CHRIS25]




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