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substitution for ferric chloride

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mik3ca

Member
I'm making my own PCB's via the photo-resist method. Developing the boards work fine but when it comes to etching, ferric chloride is bad. In fact, today I spilled some on clothing and its very difficult to remove. But with a project I'm doing I need something that can eat copper faster than ferric chloride and preferably that won't kill your hands when you touch it by accident. I also don't want it where it over-eats copper to the point where I lost some of my required traces.

Can anyone suggest anything and the location as to where I can get it?
 

schmitt trigger

Well-Known Member
Not only that, but the byproducts of ammonium persulphate etching are not as polluting to the environment.

The remains are copper sulphate which is an excellent pool algicide.
 

hyedenny

Active Member
Hydrogen peroxide and hydrochloric acid (aka muriatic acid, or swimming pool acid) work very well. Quick, even etching, easy to see the progress, and very inexpensive.
 

hyedenny

Active Member
By the way, try oxalic acid (sold as "wood bleach" in hardware stores) to remove your stains. You can even try squeezing some lemon juice (or citric acid -- "sour salt" in the Kosher section of grocery stores)) on it and letting it sit.
 

Pommie

Well-Known Member
Most Helpful Member
Now, there's an incorrect and irresponsible statement!
Why do people think this? CuSO4 is routinely added to swimming pools as an algicide and sold as root clearer for drains.

If you are really paranoid then adding sodium bicarb will precipitate copper carbonate which can be thrown in the trash.

Far more environmentally friendly than Ferric Chloride.

Mike.
 

hyedenny

Active Member
Why?? Because it's a fact!
Even though you enthusiastically acknowledge that Cu+ salts are used as algaecides, fungicides, and herbicides -- you immediately imply on the very same comment that they are "environmentally friendly!!"
The other fallacy in your comment is that "CuSO4... [is] Far more environmentally friendly than Ferric Chloride." NONSENSE!
1) Iron is the second most abundant element on the planet
2) Iron, as Fe3+ and Fe2+ is in just about every handful of dirt beneath your feet -- and is what allows your blood to carry oxygen.
3) Iron salts are most commonly sold as fertilizers, as opposed to copper salts, which are sold almost exclusively as poisons.
4) Throwing away precipitated copper salts in the garbage is barely any better (environmentally, or criminally) than throwing away dissolved copper salts. The copper ions still eventually end up in the same place.
5) Your apparent assumption that people would be dumping their unexhausted Ferric Chloride, rather than the solution which should be mostly dissolved copper salts is also very confusing to this argument. Why would anyone do that?
 

hyedenny

Active Member
Good grief -- Has everyone forgotten their basic high school inorganic chemistry and half-reactions lessons?
 

Pommie

Well-Known Member
Most Helpful Member
I asked WHY do you think it is an incorrect and irresponsible statement? You answer with "because it's a fact" and then go on to rant about copper sulphate!!

Ammonium perchlorate is far cleaner than Ferric Chloride IMHO - having used both I would not even keep Ferric Chloride in my vicinity.

Mike.
 

hyedenny

Active Member
Ammonium Perchlorate??? WTF?! At least you admit that you're speaking in terms of opinions (re: "IMHO"), so that's a start. I'm not, I'm speaking in terms of hard, physical, scientific FACTS!
You're confusing the corrosiveness of ferric chloride with the toxicity of copper. One has nothing to do with another.
The fact that you think my response to your comment was a "rant about copper sulfate" further demonstrates your ignorance of chemistry, either that or a reading comprehension problem.
WHY are you even arguing this when you clearly have no idea what you're talking about?! Your knowledge in electronics is very much superior to mine, I wish you'd respect my superior knowledge in chemistry and stop saying foolish and irresponsible things, which actually encourage illegal activity.
 

Pommie

Well-Known Member
Most Helpful Member
Ammonium Perchlorate??? WTF?!
Again, you just state nothingness!! What is wrong with Ammonium Perchlorate?

And, why the need for personal attacks?

Mike.
Edit, Persulphate of course. Perchlorate has a different use.
 
Last edited:

hyedenny

Active Member
Praising your abilities in electronics is not a personal attack. Saying that you're ignorant in this matter of copper vs toxicity is a fact becoming more evident every time you post.
I don't think ammonium perchlorate would make a very good copper etchant. Besides, it's hard to get because of it's use as an oxidizer and explosive.
I've given lots of information in these past posts, yet you can't get anything but "nothingness" out of them. That means I'm wasting my time. Go read a few chem textbooks, then we'll talk.
 

Beau Schwabe

Active Member
I'll throw a monkey wrench into this discussion .... About 25 or 30 years ago, I specifically asked OSHA (Occupational Safety and Health Administration) how to properly dispose Ferric Chloride. There answer was to just pour it down the sink. Times have changed and they may have a different answer now, but I would contact them and ask them how to properly dispose Ferric Chloride or any other chemical etchant of your choice.

Reference:
https://www.osha.gov/oshdir/ok.html
 

Pommie

Well-Known Member
Most Helpful Member
You may be surprised to learn that I do know the difference between perchlorate and persulphate. My point, and question, is that you have not given any reason why Ammonium Persulphate is not preferable over Ferric Chloride. You claim the high ground on chemistry but have to resort to questioning my reading ability! BTW, what illegal activity am I encouraging?

Mike.
 

hyedenny

Active Member
Ya, it does wonders for your brass fixtures and copper plumbing! But why would anyone throw perfectly good ferric chloride down the drain instead of using it for its intended purpose?!?!?
I wonder, more to the point, what OSHA would say about throwing copper chloride down the drain.
After all, your exhausted etchant is no longer ferric chloride, it's copper chloride! And as others have already admitted -- even to the point of contradicting themselves -- copper salts are good at killing things! (Last time I checked, that's translates to bad for the environment.)

For anyone interested in learning something -- a solution of ferric chloride is nothing but a solution of ferric ions and chloride ions (and obviously some H+, OH- ions). Rust is also made up of ferric ions (and oxide ions), and table salt also comprises chloride ions (and sodium ions). In that very basic way it is very similar to a solution of rust and table salt. In the end, it's relatively harmless to the environment.

When one usese ferric chloride to dissolve copper, the more chemically electronegative copper goes into solution as cupric, the ferric is reduced to ferrous and mostly precipitates out as hydroxide, and the chloride stays in solution (as hydrochloric acid, or more correctly H+ and Cl-).
I'll say it again -- It's not the ferric chloride I'm "ranting" about! It's the copper -- especially when in solution.
 

Pommie

Well-Known Member
Most Helpful Member
Ya, it does wonders for your brass fixtures and copper plumbing! But why would anyone throw perfectly good ferric chloride down the drain instead of using it for its intended purpose?!?!?
I wonder, more to the point, what OSHA would say about throwing copper chloride down the drain.
After all, your exhausted etchant is no longer ferric chloride, it's copper chloride! And as others have already admitted -- even to the point of contradicting themselves -- copper salts are good at killing things! (Last time I checked, that's translates to bad for the environment.)

For anyone interested in learning something -- a solution of ferric chloride is nothing but a solution of ferric ions and chloride ions (and obviously some H+, OH- ions). Rust is also made up of ferric ions (and oxide ions), and table salt also comprises chloride ions (and sodium ions). In that very basic way it is very similar to a solution of rust and table salt. In the end, it's relatively harmless to the environment.

When one usese ferric chloride to dissolve copper, the more chemically electronegative copper goes into solution as cupric, the ferric is reduced to ferrous and mostly precipitates out as hydroxide, and the chloride stays in solution (as hydrochloric acid, or more correctly H+ and Cl-).
I'll say it again -- It's not the ferric chloride I'm "ranting" about! It's the copper -- especially when in solution.
Again, strangely lacking the words Ammonium Persulphate. Why did you state "Now, there's an incorrect and irresponsible statement!"? We seem to agree that throwing copper ions down the drain is not a problem, so why this statement? Or, is that your point, throwing copper ions down the drain is not OK? You post lots of words but don't seem to state anything. Just lecture.

Mike.
 
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