LCD with Circuit Boards

[gotgoldfever]

Hi,
I have over 2000 of these brand new still in esd wrappers. The curciut boards have gold on both sides. I was hoping that it was gold under the solder mask but as you can see no such luck. BTW a hot solution of draino takes the solder mask off quite nicely. So having said all this I have a few questions for the experts.
1 - Would there be any advantage/disadvantage to strip the solder mask off?
2 - I am planning on using the AP then AC process Steve has demonstrated (thanks Steve!!!). Is this the best route?
3 - I read somewhere on the forum that the LCD itself contains indium. Is there anyone on the board that would be interested in the LCD's? They are free as long as you pay for shipping (and some pics of your recovery results I have never seen raw indium before).
Thanks,
ggf

 

[gotgoldfever]

On the reverse side of these boards there are two ic's covered with some kind of resin or something. Under the resin everything is gold plated. Unfortunately nothing short of a chisel seems to touch the stuff. I am not too keen on removing over 4000 of these with a chisel. Any Ideas?

 

[lazersteve]

Hello,

I see no reason to remove the solder mask. It will come off with the AP bath anyway. You can separate it from the gold foils using HCl-Cl to dissolve the foils and filter off the residual mask material and other debris.

As Harold would say for the epoxy resin... Incinerate!

I have found that the resins and epoxies used in some of the cpus tends to breakdown into a brittle plastic material once it reaches a critical temperature. This makes it easier to deal with. It's also nice that you don't have to necessarily totally burn the epoxy to get past it, just heat it to the brittle point and it's easier to work. Of course, if you are set up to handle the fumes, total incineration would be optimal.

Steve

 

[JustinNH]

Sometimes bending the boards a bit will pop a corner of them off and they can be scraped off easily. That, or they may just come off in the process. I dont remember if it was just a HCL wash ro if it made it to the AP batch, but i know ive had some just come off in the acid when i couldnt get them off normally.

 

[gotgoldfever]

I know this is the wrong place to ask for help but it is in reguards to the same boards. I wanted to figure out what the yield might be for these boards so I am making a pilot run (as this is my first time I'm not sure how accurate my results will be but at least I might have some idea). I have taken 75 of these boards and processed them in AP (BTW I used the 35% HP and that stuff rocks!). So I have some AP solution that is so black it almost looks like old motor oil and I have my filtered foils (and some junk). I plan on running the foils through AC so here is my question: is it ok to combine my pregnant AC and AP solutions and then drop with smb or should I drop them individually? How important is ph when dropping? (it doesn't seem like Steve mentioned it in his video but I may have just missed it).
Thanks!
ggf

 

[lazersteve]

You should never combined your stripping solution with your refining solutions. If you do you will be adding back in the base metals you worked hard to remove. This will contaminate your gold all over again.

Since you used the high strength peroxide you most likely dissolved some gold in the AP. You can keep using the AP after rejuventing and the gold will drop as the copper levels build up. The dark solution is most likely in need of some more water and possible acid. This gold will be black powder and requires further refining before melting. Redissolve it in HCl-Cl.

Add a little water, if you see white clouds in the solution (copper I chloride), you need more HCl.

Steve

 

[gotgoldfever]

Awesome thanks Steve! So I have another question, I was reading that you can strip copper chloride from solution (as elemental copper crystals) using a cell with a graphite anode and cathode. Will this work with my stripping solution? Will it help rejuvinate the solution or will it have a negative affect on the soluiton?

 

[lazersteve]

I've tried electrolytic recovery of the spent AP once and all I produced was a lot of chlorine and a fine coating of copper on the graphite that quickly turned green (copper chloride). I never pursued it past that. Most likely the key factor will be dilution of the AP. If you get it right I'm interested in your process.

Whatever copper that doesn't get precipitated will still be useful as a stripping agent as long as it's in the +2 state. You can get it to this state via oxidation and pH control as per the copper chloride document on my website.

Steve

 

[Anonymous]

New guy to the forum but not exactly to reclaiming. Would grinding the boards allow the chemicals to dissolve the gold underneath the epoxy? It would allow the chemicals to come in contact in a lot of different places instead of just the edges.