PCB etching

>>8969349
you're going to want urine. Pee on the board, this will etch it correctly

>>8969349
why the fuck would you use electrolysis?
http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/

You can't etch pcbs this way, because the traces have to be, well, disconnected. Fuck, why are you even etching your own PCBs? It's cheap enough to just buy from china these days.

>>8969349
>ferric chloride
I thought most of the people use sodium persulfate nowadays
>>8969355
>why are you even etching your own PCBs?
Prototyping. You can etch a PCB in 20-30 minutes to check if everything is ok instead of waiting a month or two for a fab house to ship you a faulty PCB, because some traces are too close to each other and some magic happens.
Also, they're the preferred method for some hobby or one time projects.

>>8969355
>http://www.instructables.com
I saw that one a while ago, and the idea of having a bottle of fuming HCL in my house doesn't particularly please me. But more than that, you're still building up a solution of copper ions, which is what I'm trying to eliminate.

>the traces have to be, well, disconnected
You're etching away the background to the traces, not the traces themselves. Unless you've got traces going from one side to the other, or in a circle, you will only need one point of connection. If you're referring to when the electrolysis etches away the copper connecting the bit you want to etch and the voltage source, then you are correct.

>It's cheap enough to just buy from china these days.
Including shipping time and the resulting hassle any trial and error takes, I don't see it as worth doing.

Let me alter my initial question. If I was using ferric chloride or the acid+hydroxide method, how easy would it be to pull the copper out of solution without producing chlorine gas? Would using sulfuric acid be a reasonable alternative, and would I even need hydrogen peroxide for this?

>>8969365
>sodium persulfate
What does that reduce to, and is it reversible?

>>8969374
>having a bottle of fuming HCL in my house doesn't particularly please me

You never heard of a bottle cap or a garage nigga?

Also bump cause EE planning on going into nanofab but since I'm not in it yet can't help ya OP

>>8969349

bumping, this board needs more posts like this

File: Screen Shot 2017-06-12 at 1.35.36 PM.png (15KB, 982x60px) Image search: [Google]

15KB, 982x60px

>>8970443
I'm in a cage-farmed city apartment, got no room for a garage nor any fume extraction. I don't think the flats above mine would appreciate having chlorine gas coming out of their kitchen extraction hood. My wardrobe is my pantry, but that's partly because my flatmates steal my butter.

>>8970463
Glad I could help?

If I've got this right, with ferric chloride:
[math]2Fe^{3+}+3Cu\rightarrow2Fe+3Cu^{2+}[/math]

With the acid+HCl:
[math]H_2O_2+Cu\rightarrow H_2O+CuO[/math]
[math]CuO+2H_3O^+\rightarrow 3H_2O+Cu^{2+}[/math]
Along with some copper oxidation states being tossed about

For the persulfate:
[math]S_2O_8^{2-}+2H_3O^++Cu\rightarrow 2HSO_4^-+2H_2O+Cu^{2+}[/math]
Which looks like it needs to be acidified.

In any of these cases, could I just pass electricity through the solution to refresh it? In the case of the peroxide I don't think I'd be able to oxidise new peroxide out of thin air, but I might be able to fuck with the copper oxidation states. With the persulfate I could probably easily pull all the unwanted copper into solution and then pull it back out again like a rechargeable battery, refreshing the oxidant. That is assuming it would be easy to refresh the persulfate from the sulfate. This looks particularly appealing as there won't be any chloride ions in solution to fuck up my lungs. Anybody know if this will work?

Etch min. gaps btwn your traces, and use planes. You would use the such a minuscule amount of reagent for your process if you just thought it out better.

>>8971026
Do you also like to type with maximum efficiency?

>>8969349
Electrolysis won't work if your anode and cathode are at the same potential.

File: electrolytic refining of copper.gif (10KB, 286x228px) Image search: [Google]

10KB, 286x228px

>>8971036
Oh hey would you look at that

>>8971075
Read your own image. That's impure copper vs copper. The additives in the impure copper change the potential. So when you link pure copper to impure copper there's a potential difference.

OP's PCB is copper plated, so the copper in question will be of high purity. When you link this to a copper electrode you're joining pure copper to pure copper. There won't be a potential difference.

>>8971094
There doesn't need to be a potential. The only reason copper doesn't spontaneously hop from one copper electrode to the other is because of an activation energy barrier, plus the system being in equilibrium. But if you put a potential across it, copper ions will be reduced at the cathode, and copper metal will be oxidised at the anode. You can even drive an already favoured reaction like this, not that there's much point.

>>8970932
Shit, I'm stupid. It should read:
[math]S_2O_8^{2-}+Cu\rightarrow 2SO_4^{2-}+Cu^{2+}[/math]
Much better; now it doesn't require acidic conditions.

>>8971542
Looking at the other options, sodium persulfate looks to be the ideal oxidant. It's highly soluble in both original and reduced form, does not require any pH conditions, and is a very strong oxidiser too.

So on the list of
[math]
S_2O_8^{2-} +2e^-\rightarrow 2SO_4^{2-}, +2.01V\\
Cl_{2(g)}+2e^- \rightarrow 2Cl^-, +1.36V\\
O_2 +H^++4e^- \rightarrow 2H_2O, +1.229V\\
Cu^++e^- \rightarrow Cu_{(s)}, +0.52V\\
O_{2(g)}+2H_2O+4e^- \rightarrow 4OH^-, +0.401V\\
Cu^{2+}+2e^- \rightarrow Cu_{(s)}, +0.337V\\
Cu^{2+}+e^- \rightarrow Cu^+, +0.159V\\
2H^++2e^- \rightarrow H_{2(g)}, +0.0V
[/math]
Where does my oxidiser need to be to NOT generate oxygen gas or hydrogen gas when I'm refreshing it and pulling copper metal out of solution?