Cupric Chloride etchant


Joined Jan 18, 2008
The obvious question is what do you mean by better? I have read that about half of commercial boards are done with cupric chloride. Adam Seychell has a very nice review of the method (

I have used both. Both are fast and neither is particularly aggressive toward the resist. I use the photoresist method and found that HCl-peroxide, in contrast, attacked the resist a little.

Ferric chloride seems to give slightly sharper etching, which I noticed when using 2 oz copper. Cupric chloride seems a little more critical from "just right etched" to "over etched." I currently use cupric chloride and regenerate it with an air pump as suggested by Seychell. The all plastic aerators sold for aquariums have worked well for me.

The only advantage to cupric chloride over ferric chloride is its ease of regeneration. If I planned to use a non-regenerated system, I would stay with ferric chloride.



Joined Jun 13, 2009
Cupric Chloride Dihydrate (dehydrate) is better than ferric chloride for etching. I do manufacture Cupric Chloride. It is used in P.C.B (Printed Circuit Board)


Joined Mar 24, 2008
I've got some hydrocloric acid (aka Muriatic Acid, used in swimming pools) and hydrogen peroxide I'm going to experiment with, though I've heard it has problems.

Fry's sells Amonium perclorate (I think). There are actually lots of choices out there. I've had good results with FeCl (Ferric Cloride). I always thought the biproduct of the etch was Cupric Cloride. Was I wrong?


Joined Apr 20, 2004
I always though the reaction went to CuCl, too.

The ammonium persulfate works. I got some once. There was some kind of stuff to put in the solution that acted as some kind of assistant to the etching. I noticed that the storage life was very short.

I keep using FeCl because it works well and stores for years.


Joined Mar 24, 2008
Amen to that, I've got some that is over 20 years old. You have to watch out for the fumes (it will distroy anything metal), but other than that...