DIY Etchant

[firethorn]

I've been reading up on alternative copper etchants or tutorials on DIYing them ever since my country banned the sale/import (doesn't matter which one) of Ferric Chloride.

One of the much cheaper and apparently simpler alternatives I discovered involves hydrochloric acid, hydrogen peroxide and copper which forms, from what I understand, a redox reaction.

What scares me though is that chlorine gas is given off. I live in a humid environment(chlorine gas + water = hydrochloric acid) and my paranoia of killing myself is making me really nervous about this. I nearly had a heart attack after putting some brine on electrolysis (because salt speeds up the reaction) only to discover shortly after through online reading that that yellow stuff in the water was actually chlorine.

So I would like to ask, is there anyway to neutralise the chlorine gas that is generated?

[Naz Nomad]

Air scrubbers and absorbtion tanks would work, but rather costly on a small scale ... can't you just buy some Ferric 'pellets' off eBay?

[David]

firethorn -

Do you have access to diluted hydrochloric acid solution (called "muriatic acid" in the US)?  Do you have access to hydrogen peroxide (H2O2) -- preferably 40%?  If so, you don't need ferric chloride.  Mix them 1 for 1.  You need less than the amount of liquid in a cup of coffee to etch the average sized board.  Little vapor is given off.  Just don't breathe what is given off - it's rather unpleasant.  Stop the reaction by diluting it with water.  Lots of it.

[MikeH]

I use this method and I just put the container next to a window with a fan, or sometimes under the exhaust hood of my stove when it's cold outside.  Or if it's nice I sit outside and have a %^&*tail while I'm waiting.

[firethorn]

Air scrubbers and absorbtion tanks would work, but rather costly on a small scale ... can't you just buy some Ferric 'pellets' off eBay?

I can't import them. And ppl from the states can't export em. And i think making my own is more troublesome as compared to cupric chloride.

Do you have access to diluted hydrochloric acid solution (called "muriatic acid" in the US)?  Do you have access to hydrogen peroxide (H2O2) -- preferably 40%?  If so, you don't need ferric chloride.  Mix them 1 for 1.  You need less than the amount of liquid in a cup of coffee to etch the average sized board.  Little vapor is given off.  Just don't breathe what is given off - it's rather unpleasant.  Stop the reaction by diluting it with water.  Lots of it.

That's what I wanted to do(although I thought it was 1 part muriatic and 2 parts peroxide) but that vapour is chlorine no? At least that's what I've been gathering. Perhaps it's some parts of the hydrochloric acid evaporating because I was looking up the chemical equation and this is what I got: Cu + 2 HCl + H2O2 -> CuCl2+ 2H2O. Can't see any chlorine there.

I use this method and I just put the container next to a window with a fan, or sometimes under the exhaust hood of my stove when it's cold outside.  Or if it's nice I sit outside and have a %^&*tail while I'm waiting.

I live in an apartment building 11 storeys high, surrounded by even more apartments, so I'm worried if I blow it out my window, mother nature would blow it right back in to someone else's home.

[GibsonGM]

Must be too strong a concentration...when I've done that, it gives off little gas.  Have you tried watering the stuff down a tad?

[andrew_k]

One of the much cheaper and apparently simpler alternatives I discovered involves hydrochloric acid, hydrogen peroxide and copper which forms, from what I understand, a redox reaction.

I used this combination when etching some boards with Darron. The fumes were INTENSE and it took literally hours to etch three boards. I was just the helper monkey, hopefully Darron will drop by and share what he's learned about ferric chloride substitutes.

[tehfunk]

Im taking chem and by the equation all you get is hydrogen gas that is given off when the copper chloride forms (no chlorine gas, then there would be no reaction just decomposition of HCl), but I did some reaction like this in class, and basically, yes, it is the hydrochloric acid that gives off fumes that are dangerous to sniff or put your face in... I believe they can burn your nasal passages etc. So, I guess it's not a product of the reaction, it's the reactant itself because HCl is just a potent acid in general.

BTW: I believe that if you stick a burning piece of wood, like a match, above the solution where you are etching it will make a pop or small explosion, from the fire igniting the hydrogen gas; in chem, we did that inside of a test tube, the hydrogen just has to be rather concentrated, so you could like block the gases from escaping at first then quickly put the burning wood there and *pop* 

[ralley]

I just etched my first couple of boards last weekend using the homebrew method (Hydrochloric acid and hydrogen peroxide).  I've only etched 3 boards so not sure if my mix has converted to the copper based chemical yet. 

I mixed up about 150ml of the chemicals, that was plenty to etch small stompbox PCBs.  The gas produced was minimal, nothing that I could see or smell (didn't stick my head over the container though!).  I etched outside in the sun (winter - southern hemisphere here) and it only took 2.5 minutes per board to etch. 

I would think etching on an apartment balcony would be no problem as long as you didn't use litres of etchant.

Rob.

[Naz Nomad]

Air scrubbers and absorbtion tanks would work, but rather costly on a small scale ... can't you just buy some Ferric 'pellets' off eBay?

I can't import them. And ppl from the states can't export em. And i think making my own is more troublesome as compared to cupric chloride.

OMG ... do they open all your mail and check its contents? ... wink wink

[ItZaLLgOOd]

http://www.diystompboxes.com/smfforum/index.php?topic=65039.0

Try this.  It worked for me the first time but I wasn't able to reuse it.

[Minion]

What I do when etching to avoid fumes from the Acid and H2O2 is etch my Boards in a sealed Zip lock freezer bag, this contains all fumes in the bag and are only released when your board is done and you remove the board from the Bag which you can do outside or in a ventalated area or what I do is simply hold my breath for a minute while I remove the PCB from the bag.....

Cheers

[earthtonesaudio]

It's crude, but you could do electrolysis with just a saturated salt water solution, a battery, and 2 different metals (circuit board is one of them).  Works best for removing tiny bits of copper, not large amounts.

[Michael Allen]

HCl is a strong acid that is completely ionized in solution. This means there are H+ and Cl- in a solution of any concentration. Now, Cl2 can be liberated from the solution and will, along with H2 gas. Not an extreme amount comes off, but with Cl2 you don't need an extreme amount to poison you. Shake your bottle of muriatic acid and watch the fumes come off, that's gas liberating without any other chemical reaction occurring. Regardless of what you're using it for you need to be careful when using this stuff, because just as it is Chlorine gas will be coming off.

You can however safely use it if you do it outdoors or in a very well ventilated environment. I usually just mix it up in a bucket and stir the bucket. No need to be super far away from it, just don't breathe over it. You'll know when you get a little whiff of chlorine. When you ventilate out your apartment window you shouldn't fear it blowing into someone else's. The diffusion of gas into the atmosphere will mean fairly little if any will blow into someone else's window and certainly not enough to be a worry.

All will be fine as long as you don't breathe it. If you spill a little just wipe it off and rinse your hand for 30 seconds. When I work with concentrated HCl or H2SO4 i'll put on gloves and wear goggles but for muriatic acid you just need common sense

[firethorn]

OMG ... do they open all your mail and check its contents? ... wink wink

No one was even willing to sell 'em. haha.

For the link to the reusable "cupric chloride", that's the one I was talking about.

But it's alright. I'll be trying the HCl(when I find out where I can my hands on it) and peroxide method albeit very very cautiously.

Thanks guys esp to Mike Allen for explaining the process in detail. =)

[firethorn]

I'm having trouble getting my hands on HCL(aq) where I am.

Any ideas? Sulfuric Acid also is a problem.

[Minion]

You should be able to find Muriotic acid at any hardware store...They use it for cleaning cement and Stone,also for etching metals and even for adjusting the PH of swimming pools...I know it is readilly available in North America.....

The only other common etchants are Ferric Chloride and Ammonium Persulfate but these are probably harder to find than muriotic acid and they are More expensive by at least a factor of 10.....


Cheers

[sfx1999]

I use this method and I just put the container next to a window with a fan, or sometimes under the exhaust hood of my stove when it's cold outside.  Or if it's nice I sit outside and have a %^&*tail while I'm waiting.

The stove's hood is not adequate for ventilation. Chlorine gas is heavier than air; it will not rise. Not to mention that many stove hoods vent the gas right back into the kitchen.