Etchants

[Poste]

Hi Guys/Girls

I would like to start etching my enclosures as well as making some pcb's

What is the best/most popular etchant, and can I make it/buy it in Australia?

Thanks in advance

[Keppy]

The most popular etchant is ferric chloride, which seems to be available pretty much worldwide. Another option is muriatic acid and hydrogen peroxide. I haven't seen anyone using that on enclosures, but I plan to try it next week. Another is sodium persulfate, but that one is slower and not recommended for enclosures.

Here are some links:

http://www.diystompboxes.com/smfforum/index.php?topic=80962.0
http://tonepad.com/photoessay.asp?photoEssayID=11
http://www.facebook.com/l.php?u=http%3A%2F%2Fwww.instructables.com%2Fid%2FStop-using-Ferric-Chloride-etchant!--A-better-etc%2F&h=3792c


Good luck!

[deadastronaut]

i use this stuff....ferric chloride...in little orange balls....mix it as strong as you like.

http://cgi.ebay.co.uk/FERRIC-CHLORIDE-ETCHING-CRYSTALS-/230523744530?pt=LH_DefaultDomain_3&hash=item35ac493112

[egasimus]

I'd say HCl+H2O2 (muriatic+peroxide). A bit easier to obtain than FeCl. Also, it's supposed to start off weak, then become stronger with every board that you etch in it, as opposed to FeCl. And looks prettier, too. I have FeCl stains of an unwholesome yellowish colour on some of my best jeans.

[deadastronaut]

http://hubpages.com/hub/What-is-Muriatic-Acid

the adverse effects bit looks a bit dodgy....

[FunkyGibbon]

I've used the homemade salt etchant from the following site:

http://www.monoprints.com/info/techniques/nik4.html

I achieved good results, although it's pretty slow (about 45 minutes for reasonable depth). An advantage over FeCl is the solution is clear so you can see what is going on.

I haven't quite settled on the appropriate ratios yet for the volume one uses for an enclosure. The link is for etching large aluminium plates. The last time I did this I used the following solution: 700mL water, 30mL dry copper sulphate (no, it's not a liquid, but I used the density from the data sheet to calculate the volume so I could measure it with a plastic measuring spoon, instead of having to buy electronic scales), 16mL dry table salt (ditto re. the mass/ volume thing), 1.3mL dry sodium bisulphate (ditto). This works out as about twice as much salt and acid (sodium bisulphate) per volume as shown on the linked page. I will probably up this again next time to try to speed things up.

The other great thing about this method is that the materials are very easy to source: the sodium bisulphate is "pH Down" (dry acid) from a pool shop, the copper sulphate is a soil additive available at any gardening shop (it's supposed to be good for roses), and I don't need to tell you where to get salt.

Good luck,

Christopher

[Crowella]

I use Ammonium Persulphate for PCB's which seems to be readily available and is easy to dispose (if you have a pool). I like the fact it's clear so you can see how the PCB is going. Not the greatest etchant if you want down right perfect lines but its done every PCB for me without fail.

Just a side note, I live in Australia and I've been hard pressed to find FeCl anywhere but online. Jaycar won't stock it unless it's excess stock from a long time ago and they don't have anything for etching aluminium. You can order it online at Altronics I believe but I haven't tried it yet so i can't say what it's like.

Might have to try the idea above me though with homemade etchant. It does sound interesting.  

[Keppy]

FWIW, I use the muriatic/peroxide etchant, but for me it got weaker over time rather than stronger. I can't seem to keep it oxygenated. I live in Colorado, so I wonder if the thinner air at this altitude is working against me.

[FunkyGibbon]

I've used the homemade salt etchant from the following site:

http://www.monoprints.com/info/techniques/nik4.html

I achieved good results, although it's pretty slow (about 45 minutes for reasonable depth). An advantage over FeCl is the solution is clear so you can see what is going on.

I haven't quite settled on the appropriate ratios yet for the volume one uses for an enclosure. The link is for etching large aluminium plates. The last time I did this I used the following solution: 700mL water, 30mL dry copper sulphate (no, it's not a liquid, but I used the density from the data sheet to calculate the volume so I could measure it with a plastic measuring spoon, instead of having to buy electronic scales), 16mL dry table salt (ditto re. the mass/ volume thing), 1.3mL dry sodium bisulphate (ditto). This works out as about twice as much salt and acid (sodium bisulphate) per volume as shown on the linked page. I will probably up this again next time to try to speed things up.

The other great thing about this method is that the materials are very easy to source: the sodium bisulphate is "pH Down" (dry acid) from a pool shop, the copper sulphate is a soil additive available at any gardening shop (it's supposed to be good for roses), and I don't need to tell you where to get salt.

Good luck,

Christopher

The salt mordant is just for aluminium enclosures. For pcbs I use ammonium persulphate.

C.

[CodeMonk]

The most popular etchant is ferric chloride, which seems to be available pretty much worldwide. Another option is muriatic acid and hydrogen peroxide. I haven't seen anyone using that on enclosures, but I plan to try it next week. Another is sodium persulfate, but that one is slower and not recommended for enclosures.

Here are some links:

http://www.diystompboxes.com/smfforum/index.php?topic=80962.0
http://tonepad.com/photoessay.asp?photoEssayID=11
http://www.facebook.com/l.php?u=http%3A%2F%2Fwww.instructables.com%2Fid%2FStop-using-Ferric-Chloride-etchant!--A-better-etc%2F&h=3792c


Good luck!

Maybe it was my ratio (3/2 Acid/Peroxide), but when I tried that, after a little while, it started boiling violently.
I was etching it in a plastic container that was nearing melting point before I stopped it.

[CynicalMan]

There's a blog that shows how to use hydrogen peroxide, vinegar, and salt. I can post the link tomorrow.

[Keppy]

Maybe it was my ratio (3/2 Acid/Peroxide), but when I tried that, after a little while, it started boiling violently.
I was etching it in a plastic container that was nearing melting point before I stopped it.

Yeah, that's triple the acid level recommended in the tutorial. Were you etching copper or aluminum?

[CodeMonk]

Maybe it was my ratio (3/2 Acid/Peroxide), but when I tried that, after a little while, it started boiling violently.
I was etching it in a plastic container that was nearing melting point before I stopped it.

Yeah, that's triple the acid level recommended in the tutorial. Were you etching copper or aluminum?

I use it for copper.
Thought what the hell, lets try an enclosure. Not good :
Although I guess on some level, it has mojo




Edit:
Better picture.

[egasimus]

http://hubpages.com/hub/What-is-Muriatic-Acid

the adverse effects bit looks a bit dodgy....

Yeah, well, both FeCl and HCl are quite nasty chemicals. Which is one of the reasons large PCB fabs, if I'm not mistaken, make their PCBs mechanically, by cutting instead of etching.

I also add salt to my HCl/H2O2 mix to speed up etching. Got it from that vinegar tutorial.

[.Mike]

I also add salt to my HCl/H2O2 mix to speed up etching. Got it from that vinegar tutorial.

Hrmm.

About how much do you add, and to what ratio of HCl to H202?

I've been using a 1:1 ratio on PCBs, and it works great. 5-10 minutes, start to finish. I just etched about 9 sq. in. of board the other day, and only used 4 tablespoons of liquid in total. I do have to get a fish pump setup to replenish the oxygen for my spent etchant-- I've got about 4 cups of it.

I use the same ratio for enclosures. I still haven't gotten the technique down, but I'm getting there I think.

My first two (identical) enclosure etches had a large area to etch. The first enclosure started very slow, and then quickly accelerated, causing a violent reaction. It generated a lot of heat, so I pulled it out of the acid and dumped it in some water. The etch was uneven and had dots that didn't etch, and areas that etched too much. The metal seemed to flake off.

For the second one, I used a toothbrush to apply the etchant, allowing better control. It started the same, though-- slow reaction, and then it picked up. It was controllable, but it took forever-- about an hour. The results were much better, with the etched areas nice and smooth. I etched it a bit too deep, though, and rounded off some of my letters.

For the third one, it was a small etch, but with some fine lines. Worked great, but still took about an hour with a toothbrush. The result was almost flawless. I again etched it too deep, but the benefit was that I didn't need to paint it. There was no violent reaction this time, likely because of the small area being etched.

And for the last one, the other day (pic coming soon), I also had great success with the toothbrush method. There was only one minor flaw that I couldn't sand out. It has both big and small areas, fine lines, and curves.



Mike

[egasimus]

Well, I just sprinkle some on top of the PCB while it's dipped, resulting in a bluish layer (CuCl perhaps) which then washes away. Seems to speed up the reaction, although it doesn't really make much of a difference since I have nothing to heat the bath with, and the HCl/H2O2 mix works slower if cold, just like HCl.

[CynicalMan]

There's a blog that shows how to use hydrogen peroxide, vinegar, and salt. I can post the link tomorrow.

http://www.stephenhobley.com/blog/2011/03/02/still-messing-with-forces-i-dont-understand-the-formula/

This only works for copper, not aluminum.

[PRR]

> I used the density from the data sheet to calculate the volume

The quoted density may be for a solid; in chunks or powder the apparent density will be less.

> 30mL dry copper sulphate (no, it's not a liquid, but I used the density from the data sheet to calculate the volume so I could measure it with a plastic measuring spoon, instead of having to buy electronic scales)

Electronic scales?? BUY??

DIY!!

Assume you wanted 30 grams (you actually want more because CuSO4 is heavy).

Set a pencil under the exact center of a ruler. Put five US 25-cent coins and one US 10-cent coin in a cup on one end. Add your dope in a cup on the other end. When the ruler balances, that is 5*5.670 + 2.268 or 30.6 Grams. Take a wee pinch off, 30 grams exact-enuff for home chemistry.

No US coins handy? Two Aussie 50-cent is pretty near 30g.

5¢ 2.83 g Echidna
10¢ 5.65 g Superb Lyrebird
20¢ 11.30 g Platypus
50¢ 15.55 g Plain Coat of arms

(Heavy money!)

Ah!! Forget coins. Put 30mL of water in one cup. Fill other cup to balance. If 30 mL of water is perfectly pure and a certain temperature, it is 30 grams. For your purposes a little murk or a warm day does not make any difference. (Don't use beer or pee... alcohol and salt-water are noticably off from plain water.)

[FunkyGibbon]

Hi Paul,

I only just noticed your post. It seems so obvious now you've said it!

Thanks for the tips.

Christopher

[sanction13]

You can get ferric chloride in Australia from Ultrakeet or Element14 (formally Farnell).

Haven't checked Ultrakeet for a while but they normally sell out pretty quick.

Personally, I have just switched to ferric from ammonium. Ultrakeet has a good comparison of the two on their site. Did my first enclosure on the weekend, and was stoked with the results.