Electrolysis Etching PCB's Complete Tutorial

[Zben3129]

Hi all,

Recently I etched a few tube screamer boards with the electrolysis process, and while i could find many tutorials on electrolysis etching an enclosure and could piece them all together for PCB's, I could not find one specifically directed at PCB's. So here is my tutorial (pictures coming tomorrow, sorry left my camera away)

First off, I'd like to tell you a little bit about this process. I like this way more than the ferric chloride method, as with ferric chloride you are dealing with an acid that is tough to dispose of, stains permanently and is toxic. Also, incase you didn't know, you can't make ferric chloride by turning on a faucet and grabbing a salt shaker    So, therefore, working almost as well, sometimes even better, and at 0$ cost after the first time, I have started only using the electrolysis method.

Materials List

Water

Salt

Plastic container, plastic bag, just can't be metal

DC power source - The higher the current, the faster the process. Voltage plays a role aswell, the higher the better, but I have found amperage to be a bigger factor. The one I use is a 12v 2A DC source I took from a broken DVD player of mine. Should be noted that i have done this using 9v batteries the first time i tried this method, took forever and was not as clean, ate through 4 batteries, but worked. Very good chance you have something that fits the bill lying around, so also possibly free

Alligator clips , wires , whatever you have to put the + and - in the water having one attatch to the board and one floating free, my preference is alligator clips, just for ease (note that whatever you use as the negative electrode will be copper plated! (Got something conductive you need copper plated...)

OPTIONAL - Light bulb from a flashlight



Making The Etchant Solution

1. Pour hot water into whatever bucket/container you will be using, just enough to cover the pcb by a little bit

2. Completely saturate the water with salt. Meaning, dissolve a boatload of salt into the water. You want to do this to that point that it is no longer possible to dissolve any more salt



Riggin' It Up

1.WITH THE POWER SOURCE UNPLUGGED  place the negative electrode into the solution in the container

2.WITH THE POWER SOURCE UNPLUGGED  clip/attatch the poitive electrode to the board and submerge the board in its entirerity into the etchant solution.



Lets Do The Etching

1. Plug the power source into the wall (Don't forget this step, kinda important)

2. You should see bubbles rising from the negative electrode, aka not the one attatched to the board. If theres bubbles coming off the board, you're plating your board with the material of the negative electrode. If you get bubbles coming off board, Unplug, reverse polarity, and plug back in.

3. Leave the etch process running until you think it is completed. For me, I leave it in for 5-10 minutes. For a lower supply than mine, it will probably take longer, and vice versa. You be the judge. Also, the water will be come extremely dark due to all the copper, so to check the progress, UNPLUG THE POWER SUPPLY then reach in and grab the PCB and check it. The copper may make your hands slightly green, but this washes right off with water, no effort, no staining.



Disposal

Got a toilet? Yes. Flush it. No worries, its salt, water, and Copper. Thats it!!!!




Ok Hope you enjoyed. Also, next time i do this (Probably around monday or tuesday) I will take pictures as well as video, and put those up


Thanks for reading and good luck!

[stumper1]

Interesting   I have a 12vdc 30amp power supply.  I just may have to try this.

[Idiot]

How are the traces drawn?? & with what?? ink??

[Zben3129]

ok I am back and about to finish, and the traces are drawn by whatever etch resist you want, pnp, toner, sharpie, you decide. The board preparing is the same, this is just alternative etching



edit: Apparently I can't edit my first post    anyways, Aron, if you see this, can you put the rest of my tutorial in the first post please? Much appreciated


anyways....


3. Leave the etch process running until you think it is completed. For me, I leave it in for 5-10 minutes. For a lower supply than mine, it will probably take longer, and vice versa. You be the judge. Also, the water will be come extremely dark due to all the copper, so to check the progress, UNPLUG THE POWER SUPPLY then reach in and grab the PCB and check it. The copper may make your hands slightly green, but this washes right off with water, no effort, no staining.



Disposal

Got a toilet? Yes. Flush it. No worries, its salt, water, and Copper. Thats it!!!!




Ok Hope you enjoyed. Also, next time i do this (Probably around monday or tuesday) I will take pictures as well as video, and put those up


Thanks for reading and good luck!

[Zben3129]

30 amps!!!!! be careful with that, don't want to become unconcious etching a PCB   

[Zben3129]

also should be noted - You are working with electricity. BE CAREFUL!   Technically speaking if you put your finger in the water with the power on, nothing would happen, but even so, don't be stupid

[R.G.]

Disposal
Got a toilet? Yes. Flush it. No worries, its salt, water, and Copper. Thats it!!!!

At the risk of appearing to be a spoil-sport, it's the copper in the remains of ferric chloride that's toxic. Iron is not; looks bad, but is nontoxic to almost all lifeforms. Dissolved copper compounds are toxic to many. This really isn't any more - or less! - environmentally sensitive than flushing leftover FeCl etchings with the CuCl in it. It just doesn't look as nasty.

Copper water pipes are benign because they are passivated by many minerals forming an insoluble layer inside the pipe, copper not dissolving all that easily in water without other reagents, and humans not be all that sensitive to dissolved copper. It's bad juju for a lot of aquatic life, though. And copper pipes do get dissolved away in some water systems; rainwater collection systems, one of which I use for my drinking water, have been known to dissolve through copper tubes. I used PEX for that reason.

[sengo]

I'm going to have to try this. I'm tired of FeCL, because winter is getting on where I live and I either have to etch outside in the cold, or etch inside where I have to trust my clumsy self not to stain my bedroom a nice rust color.

At the risk of appearing to be a spoil-sport, it's the copper in the remains of ferric chloride that's toxic.

What would be the best way to dispose of the copper solution R.G.? Should I just take the liquid to the dump and have them dispose of it properly?

Nick

[Zben3129]

Thanks for all your input!

R.G. - I could be wrong, but i'm pretty sure that with ferric chloride what is occuring is a chemical reaction between the Fe^IIICl₃ (Ferric Chloride) and the Cu (Copper - but remember it has impurities, not pure copper) causing the breakdown of the copper plating on the board, resulting in copper compounds such as Cu^IICl₂ (Copper Chloride) which are potentially hazardous. However, in electrolysis, what is happening is the movement of electrons is stripping the copper off of the board, a physical reaction. Since there is no chemical reaction occuring in electrolysis (besides the breakdown of water into oxygen and hydrogen , unimportant) etching, the copper on the board is not changed at all, just removed. Therefore, the remains are safe to flush 

RXN (ferric chloride etching) (Highly simplified)  Cu + Fe^IIICl₃ ----->  Cu^IICl₂ + (Other stuff)


RXN (Electro-etching) (doesn't account for impurities in water, Incase you didn't know, tap water is not H₂O, it's dhmo plus other contaminates) 

            energy
H₂O ----------->  H₂ + O (O is ozone, two O molecules will combine to create oxygen, O₂)




R.G. correct me if I am wrong, but I am pretty sure about this 

[mdh]

No, it's definitely a chemical reaction going on in both cases, and both result in ionic copper in solution.  It's been several years since my last chemistry course, so I'm, er, rusty, but in this case the solution wouldn't be turning blue without the presence of ionic copper.

[Zben3129]

the electrolysis solution doesn't turn blue, atleast it didn't for me. Anyways, I belive they actually copper plate things this way. I did some research on this and all the sources I have found have said to flush the remaining solution down the drain, none have mentioned it being hazardous

And if the electrolysis does produce a chemical reaction with the copper, what would it be?


Also, I am not trying to back myself up here so much as learn as much as I can about this so I can give an accurate representation, so I'm sorry if I sound harsh 

[Papa_lazerous]

ok so you want to use electrolysis to etch..........

You etch your board and now you have copper in your salt bath that you cant safely flush,

how about we use a little lateral thinking and use electrolysis.  You have copper in solution right.. so then put something you want to plate at the cathode and the copper will be magically plated onto said cathode. and no longer in suspension in the salt bath.

Is that too simple an idea??  I still dont fancy the electrolysis idea, far too much hassle but each to there own

[Papa_lazerous]

the electrolysis solution doesn't turn blue

It would if you did enough etching.....You just got a very very tiny amount of copper there so far thats why its not visibly blue YET

[Zben3129]

no there will still be copper suspended in the solution, but it is copper, not a copper compound, as is formed in a chemical reaction. Again, I could be wrong about this!  

Also, lets say that you took a knife and scraped the copper off of the circuit board and then you had a pile of copper shavings. Would you flush these down the toilet?

[PerroGrande]

Several thoughts on the matter based on some preliminary research.  For me, it has been a LONG time since chemistry, so I had to refresh a bit:

From thenakedscientists.com:



When you pass an electric current through a solution, ions (charged particles) migrate towards the electrode of the opposite charge.

In a salt solution (NaCl) the dominant species of ions are sodium (Na+) and chloride (Cl-), because only a tiny amount of water (H2O) is ionised (to H+ and OH-) at pH 7, and that's why pure water is very difficult to electrolyse (and why teachers add acid to help the process).

So when you apply a current to the solution using copper electrodes, the chloride ions (Cl-), termed anions, will move towards the positive electrode (the anode), whilst the positively-charged sodium ions (the cations) will migrate towards the negative electrode (the cathode). The migrating ions carry charge through the solution and hence help to complete the circuit.

At the anode 2 chloride ions (Cl-) will each surrender an electron to the anode (which likes electrons because it is positively charged) to form a molecule of chlorine gas, which you see fizzing off :

2Cl-(aq) -> Cl2(g) + 2e-

At the same time, the copper (Cu) forming the electrode will also try to donate electrons :

Cu(s) -> 2e- + Cu2+(aq). When the copper (Cu) gives up 2 electrons it forms a copper ion (Cu2+) which then goes into solution, turning the electrolyte blue / green, as you have observed.

At the negative electode (cathode) hydrogen ions (H+) from water pick up electrons to form hydrogen :

2H+(aq) + 2e- -> H2(g)

...and the copper ions (Cu2+) which were mobilised from the anode also pick up electrons to form metallic copper which is deposited on the cathode :

Cu2+(aq) + 2e- -> Cu(s).

So the slight amount of sludge you end up with is copper chloride.  During the electrolysis process, you bubbled off hydrogen and chlorine gas.   Copper chloride is none too friendly, either.

It might be worth trying something:  after the process is complete and the board is etched, stick another electrode in there where the board used to be -- something that isn't copper and reverse the polarity.  You might be able to plate the electrode with the copper in solution (not sure -- been a long time).

[Zben3129]

Ahhhh I forgot about the valence electron stuff, that was the missing piece!!! Thanks for helping me understand where the copper chloride comes from. Also, it is a very very small amount of CuCl correct? Small enough concentration to flush down?

[alanlan]

Couldn't the copper in the solution be re-plated on an electrode and then thrown in the bin or is this a silly idea - I'm not a chemist

[birt]

you're not telling something. because the whole copper area on you board is acting as an anode, you HAVE to keep bridges between every trace to keep the electricity running until the end of the etching process. A trace that gets disconnected from the anode will not be etched properly. afterwards you have to cut these bridges away.


oh and i etched somthing with electrolysis. when the etchant was too dirty i just let it vaporize and threw the residue away with the garbage.

[slacker]

Yeah I was wondering the same thing, presuambly you have to modify the layout to temporarily link all the traces together somehow? You can't just use normal layouts can you?

I'd be interested in seeing some pictures of the finished boards.

[John Lyons]

+1 I did some copper etching experiments with salt water and had the same problem.
Once your electrode is etched and the contact point becomes isolated from the rest of the copper
your electrolisis process stops working. (bridged traces and pads).

John