…messing with forces I don’t understand.

by Stephen Hobley on March 1, 2011

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If you’re anything like me, you like to etch PCBs at home. Quite often you’ll get the urge, but find that you’ve just run out of Ferret Chloride*, or Bureaucratic Acid*

So what can you do?

I know little about chemistry, but that doesn’t stop me from trying to cook up a substitute etching solution from common household stuff.

And it was during one of these sessions that I seem to have cracked it.

Homemade Etching Solution Test

This picture shows 3 candidate solutions – #2 and #3 show very little reaction – but #1 is smokin’ – it etched through the copper clad in about 20 minutes.

Clear Winner in the DIY Etching solution

It’s made from 3 chemicals – and you can safely put each one in your mouth (although I wouldn’t recommend swallowing them).

I’ll post the formula tomorrow, but in the meantime – anyone like to guess what the 3 ingredients are? It’s highly likely you have them at home right now.

* Ferret Chloride or Bureaucratic Acid – These are not real chemicals – just so you know. :)

UPDATE : #3 finally etched the board after about 3 hours – #2 is supposed to work, but doesn’t :(

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{ 20 comments… read them below or add one }

Brad March 1, 2011 at 9:58 pm

(Artificial) Lemon Juice, Peroxide and Vinegar?

Stephen Hobley March 1, 2011 at 10:06 pm

Ooh close, but no cigar…

Jerk March 1, 2011 at 11:23 pm

Ammonia, Lye, Oven cleaner

Stephen Hobley March 1, 2011 at 11:30 pm

Mmmmmmm…. Lye

pkuhns March 1, 2011 at 11:58 pm

Matt says its nail polish remover and hydrogen peroxide. And he doesn’t know sh*te about chemistry!

jimmy March 2, 2011 at 10:47 am

Dishwashing detergent, bleach, and uhh……… put some windex?

kyle March 2, 2011 at 12:25 pm

jimmy that would kill you.

neuromonkey March 2, 2011 at 2:05 pm

Monkey urine, narwhal tears, and unicorn drippings?

Stephen Hobley March 2, 2011 at 2:13 pm

Have you seen the price of unicorn drippings?

Ethan March 2, 2011 at 4:19 pm

I’m gonna say:
1. Toilet bowl cleaner
2. Hydrogen Peroxide
3. Bleach

macegr March 2, 2011 at 7:00 pm

Okay. I know that salt and vinegar have a curious de-oxidizing effect on copper that is greater than the sum of their parts. Now, if you add hydrogen peroxide to that, you might kick-start a neat redox chain reaction that would start eating copper right up. Of course I last did anything with chemistry ten years ago so I could be wrong.

Stephen Hobley March 2, 2011 at 9:00 pm

Yes! But you have to apply the ingredients just right to get the salt to work its magic.

I just posted a video “how-to” – it’s a strange reaction…

kyle March 3, 2011 at 1:27 pm

Ethan that would kill you.

Garry March 3, 2011 at 5:46 pm

Just wondering, how did you get such a nice finish to your etch resist mask in the first place? What process are you using, whenever I’ve tried to DIY PCB’s at home this stage has always been a total letdown.

Nice job on the “safe” etch bath though, many a time where I’ve had an incident with Ferret Chloride, not to mention the accident I had with it when I was 10 years old spilling 2 litres of it on the living room carpet!

Stephen Hobley March 3, 2011 at 5:51 pm

You are looking at the result of many, many *many* failed attempts before I got the formula right – check back I’ll have to put together a blog post about it.

Shameless plug: I do reveal the full process as part of my “step-by-step project” downloads – they’re not free, but I think you’ll find they’re worth the money. Currently I’ve got two projects available :

http://www.stephenhobley.com/store/0111
http://www.stephenhobley.com/store/0211

kwong March 3, 2011 at 8:14 pm

I am wondering if the etching process could speed up somewhat if the solution is preheated. At least heating up the solution works for the traditional etching methods using FeCl3.

Stephen Hobley March 3, 2011 at 8:19 pm

Yeah – but I’ve found that using a microwave can be detrimental the Peroxide – causing all the oxygen to exit the solution before it’s done its work.

Using a bath of warm water might be better.

Greg March 4, 2011 at 8:02 am

How about Hydrogen Peroxide in a brown bottle, put in the freezer, then pouring off the much more concentrated Hydrogen Peroxide solution(now strong enough to bleach any fabric). Mixing that with vinegar and salt should do the trick

Agent24 September 20, 2011 at 11:47 pm

Interesting, although the gunk accumulating on the board doesn’t seem that great. Scraping at the board while it’s in the etchant seems a good way to remove the resist and ruin the board!

I think I’ll stick to my cupric chloride, it’s working very nicely.

D.plomat March 5, 2012 at 6:03 am

pkuhns: if the nail polish remover is acetone based, just add some acid if you want the mixture to blow your hands and face ^^

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