Homebrew_PCBs

Stumbled across this method while reading up on etching.  I’m still waiting on my ferric chloride, which you cannot buy around here.

Anyway, the procedure is ‘simply’ mix cleaning vinegar (higher acid concentration than regular vinegar) and peroxide at 1:1 and let her rip, adding table salt to speed up up or maintain the reaction.

Here’s a few pics of the process:

http://s1381.photobucket.com/user/unclefalter/media/Mobile%20Uploads/20160618_145928_zpsyjqawclk.jpg.html

Further along:

http://s1381.photobucket.com/user/unclefalter/media/Mobile%20Uploads/20160618_165549_zpsrgxs32nq.jpg.html

And almost done:

http://s1381.photobucket.com/user/unclefalter/media/Mobile%20Uploads/20160618_170642_zpso2duc8vd.jpg.html

In terms of how it worked.. not bad… kind of slow.  On my first PCB, I made a batch of ‘etchant’ from peroxide and regular vinegar and dumped it in.  I thought it had to keep bubbling to work, so I kept adding salt.. but I think I killed the reaction.  I then went out and bought the more powerful cleaning vinegar, took the board out (it had been sitting in that first bath for about 1.5hrs) drained the old solution, then put in a new batch, again 1:1 with the more powerful vinegar.  The board upon removal had little bits of green PCB showing but there was still tons of copper, in a finish that is sort of like what rusty pennies get when you put them in cola.  I put the board back in.. wow… that remaining copper really began to disappear fast.  I also put the whole thing in my laundry tub and put a few inches of hot water under while gently rocking it back and forth.  That’s how it got to the state shown in the third picture. 

I’m not sure why, but there were some stubborn parts where the original shiny copper was still holding out.  I poured a bit of salt onto those spots and it seemed to help get things moving.

Anyway, off to try to finish it.. if anyone out there has more tips on this method I’m all ears.  I like that it’s a lot less nasty than ferric, etc.

It definitely works.  I’m just not sure how.  The various sites say the salt just ‘speeds up’ the process.  But if you just leave the boards in peroxide and vinegar, nothing really happens.  The salt seems to be the key.  I just pour a bit over un-etched areas and it goes nuts.  However on my first board, I’m thinking either the table vinegar I was using was too weak, or too much salt.. eventually the process just stopped working.

Yeah.  I just have a hesitancy about muriatic, remembering some accidental burns years ago. J  I accidentaly splashed a bit of this vinegar stuff on my hand in a moment where I forgot to put on gloves and nothing happened.  That kind of thing with muriatic would be very bad.  It etches beautifully – just really slow.

Have you thought about using acetic acid ? isn’t that what vinegar actually is ?

I have glacial acetic here ,it is used for darkroom work. Stop bath is basically the same thing except it has indicator in it so you know when it goes bad I used to stick my fingers in it all the time when printing photo’s . it freezes at about 62 degrees I think ,so watch where you store it. The glacial you can water down to whatever strength you need ,stop bath you also water down. It comes in a small plastic bottle and you add a certain amount to like a half gallon of water . think the mix is only a couple ounces to half a gallon!

What I’ve got seems to work fairly well – I think the only area I’m suffering is not understanding the process, and the relationship between the vinegar and salt and the peroxide.  Today I put in a full 500ml bottle of peroxide and then dumped what was left of my cleaning vinegar in – I think it was close but not quite 1:1.. and that mixture went crazy on the board and did a perfect job.  However, the board I put in was half the size of the previous.. so maybe the amount of copper present has an impact also.  I put a bit of salt in and it just fizzed and fizzed away.

Without a doubt it works.. the goal here was a) to be safer and b) avoid relying on things that are difficult or impossible to by in my silly small town.

Another thing I found helps per Quinn’s site is the foam brush on the board while it’s in the bath.

Side note: I’m glad I didn’t go with those $400 custom made PCBs I was thinking about.. I dissolved a piece of their sample in my etchant and the green of the fiber was nowhere near what it looked like in pictures.  In fact, these cheapo Chinese boards were far closer.

Brad

I’ve seen ferric chloride solidify of try to during etching towards the end when it gets pretty well saturated with the copper. Ferric chloride to my understanding is used for sewage treatment to coagulate the solids.

Thanks guys.  I’ve now etched 5 boards and am pretty happy with the results:

http://s1381.photobucket.com/user/unclefalter/media/20160619_190537_zpsk5uo6tan.jpg.html

For me it’s just living in a small town, there are certain things you cannot get.  I can get hydrochloric, but yeah, I’m wary. 

I would be more concerned with the copper salts. They put copper in marine paint to prevent organisms from attaching to boats!