Stop using Ferric Chloride etchant! (A better etching solution.)

Step 1 Ingredients: The Starter Etchant

For the starter etchant itself, you only need two ingredients: hydrochloric acid and hydrogen peroxide.

(OK, actually three. But the third one's copper. See the chemistry section for an explanation.)

Hydrochloric (muriatic acid, "pool acid", etc.) is available at a hardware store. The acid I got is 31.45% (or 10M) and should run around $5 per gallon. Which is more than you'll ever, ever need.

The peroxide is normal 3% for mouthwash or cleaning cuts, and can be bought at a drug store for $2-3 for a big bottle.

You'll also need a non-metallic container that fits your PCB and two standardized measuring cups.

As long as you're in the hardware store, pick up some acetone if you don't already have some. It's useful for removing the etch resist. (That's for another instructable.)

Comments

[bertm]

I’m using this for Copper Etching because I’m a beginner, how much water do you need before adding the muriatic acid and would like to know if I’m understanding this correctly
2 parts peroxide
? WATER
1 Part Muruatic acid
Are the steps correct because I really do not want to make a bomb

[The Real Elliot]

You don't need to add water explicitly. If you're using 3% peroxide, the other 97% is water. Slowly pour the acid into the peroxide mix and you'll be fine. BTW, in case you're wondering, the reason for "adding acid to water" is that the combination produces a little bit of heat (is exothermic). If you pour the water into the acid, you end up producing that heat in a concentrated acid solution, and if you add the water solution too fast, you can end up with boiling strong acid. And that's no fun. If you pour the acid into the water, you're creating the heat in a very dilute acid solution. If you slip and add it too quickly, at worst you've just got a cup of boiling (mostly) peroxide. Still no fun, but better than boiling hydrochloric acid! Also you're adding 1x acid into 2x water. So whatever heat you create is spread out over twice the volume, so it's less likely to boil. So yeah. Too much information? Or just enough?

[Etcher Cat Person]

The etching solution is working well. I am concerned about the safety of it however, as it is lightly bubbling on its own. Is it okay to leave the solution tightly capped shut? I am using safety goggles and chemical resistant gloves. Is it okay to rinse the etched plate in the shop sink? Is there a neutralizer like Baking soda for accidental spills? Thanks

[Davad]

Small amounts of the solution is ok to dispose down the drain. So rinsing in the shop sink is fine. Just don't dump a gallon of the stuff down the toilet.

A base like sodium hydroxide in the right amount will neutralize the acid in the solution but there is no such thing as neutralizing cupric chloride. It is what it is.

If you could find some way of replacing the copper ion with a sodium ion then you would have table salt and that probably won't be a problem to dump down the sink. But cupric chloride will kill fish and other life forms in water.

[jumpfroggy]

Just enough.

[robwen]

If you are at all paranoid, you should probably NOT purchase the Acetone, Peroxide, and Hydrochloric Acid all at the same time, or you may be suspected of terrorist activities. Those three ingredients just happen to be exactly all you need to make a certain high power primary explosive made famous by the "Shoe Bomber". I recommend not searching for it on the Internet either, unless you want to risk tripping certain "alarm filters". Have a nice day. ;-)

[tacamaral]

And peroxide is one of the components for refining cocaine. I think acetone is used, too, along with the peroxide. Two governmental agencies! Yay! : )

[geeklord]

maybe your comment just tripped a certain "alarm filter"??? It's all a conspiracy man........ jk =D

[Gamer917]

i just tripped the "alarm filter" (I googled the shoo bomber)

[geeklord]

Is there a bald guy in a suit with dark glasses knocking at your door?

[Gamer917]

nah the guy never came

[Sagar Gondaliya]

holy *expletive*!!! ther's a couple comeing up my driveway!!! thnx for the advance warnig, i gotta leave. *core purge in 3 seconds*

[jamilm9]

would this work<br/><a rel="nofollow" href="http://www.homehardware.ca/Products/index/show/product/I7159077/name/ph_down_pool_4kg">http://www.homehardware.ca/Products/index/show/product/I7159077/name/ph_down_pool_4kg</a><br/>if not can anyone find muriatic acid on homehardware. Thanks <br/>

[jrblast]

That most likely will not work. Also, it doesn't say what exactly it is, so you don't want to be mixing it with random stuff. I suggest checking pool stores for Muriatic Acid. If you need to find a pool store, try typing something like "Pool stores near " in google maps. That's what I did and I found a few stores really close.

[jamilm9]

i got some it was in the paint section and was sold as concrete cleaner

[glen1990]

i added abit more proixide and it seem to clean it up and mkae it etch a dubel sided board in about 10 -15 mins....so its getting better.......prob is i can on ly get the bottels in 200ml bottels for about $4 ruffly each :S....anyways i shoudl be good hopeing now

[glen1990]

hears a pic of what it looks like :S now

[glen1990]

hey anyone know how i can fix my etchent.....i used hydrocloric acid and the hydrogen preoxide 3% and mixed it like you said it etched a board in about 2 mins like you said....but this is the 3rd day and im etched about 5 littel boards and its looking quite dark green like you can hardly see thow the tank to the other side....i have had a low amount of bubbels wile etching going thow the mixture.....anyideas and now its taking about 20mins up to an hour for a signel sided PCb to etch.....i need help...:S

[Davidnipp]

Yeah, that's true. It makes an explosive called "cetone peroxide (triacetone triperoxide, peroxyacetone, TATP, TCAP) is an organic peroxide and a primary high explosive. It takes the form of a white crystalline powder with a distinctive acrid smell." It is approximately 150% more powerful than TNT if made correctly. DON'T GET ANY IDEAS

[reastag]

what kind of acetone did you use

[thedownsmeister]

What molarity acetone did you use? Does it even matter?

[kimleslie]

Hi I was wondering if the starter etchant also works with zinc besides the copper? And how much water do you mix it with? And does it matter what order if you pour one into the other if it matters? Someone mentioned this is really dangerous is it? thanks, Kim

[The Real Elliot]

Man, two acid-to-water comments in one day! See below. And anyway, the heat of solution of hydrochloric is not all that high. You can probably do it the "wrong" way and just end up with a cup of really hot acid. (I don't recommend this unless you're being really careful about it.) With other acids, like sulphuric, you have to be much more careful. Google "heat of solution" for whatever your acids are, do some lightweight math, and you can figure out whether or not there's actually a risk of boiling over.