# Recovering gold from PCBs and motherboards



## powermetalx (Sep 29, 2013)

Hi all,
So I've been collecting escrap, and some of the initial processing is very easy (mechanical separation etc.)

But many motherboards and PCBs clearly have a layer of gold underneath the top layer of epoxy. How can I get at this? I can post pics if needed. 

But basically it's just that the gold cannot be separated mechanically by any method I know. Is there a way o etting the epoxy off safely?

Many thanks!


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## FrugalRefiner (Sep 29, 2013)

In most cases, the traces just _look_ like gold. There are some exceptions, but rarely. To check, use a sharp blade to scrape off just enough of the coating to expose the metal. They're likely just copper. :| 

Dave


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## AndyWilliams (Sep 29, 2013)

powermetalx said:


> Hi all,
> So I've been collecting escrap, and some of the initial processing is very easy (mechanical separation etc.)
> 
> But many motherboards and PCBs clearly have a layer of gold underneath the top layer of epoxy. How can I get at this? I can post pics if needed.
> ...



Dave's right. Any question after you scrape the mask, use a drop of nitric.


Overall, a great explanation is here (I searched for "removing solder mask):

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=48&t=5896&p=180728&hilit=removing+green+mask#p180728


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## joem (Sep 29, 2013)

There is no "goold" in any boards


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## macfixer01 (Oct 1, 2013)

powermetalx said:


> Hi all,
> So I've been collecting escrap, and some of the initial processing is very easy (mechanical separation etc.)
> 
> But many motherboards and PCBs clearly have a layer of gold underneath the top layer of epoxy. How can I get at this? I can post pics if needed.
> ...




There are different colors of solder mask, the most common being green. Other colors are red, blue, and a gold-ish color commonly used on certain brands of motherboards which can make the copper traces under it look a lot like gold when viewed through it. As was mentioned already, scrape some of the solder mask away (without digging into the metal) and under a light you'll likely see only copper. There are some brands of boards such as HP, Agilent, and Tektronix that often have gold-plated traces, but most often it has no solder mask covering it. I have seen some boards that are exceptions though that had solder mask covering gold-plated traces, since it offers other benefits besides oxidation protection. Solder mask is actually designed to help prevent solder from bridging between adjacent pads during the flow soldering process. The solder mask is not an epoxy and is not that durable fortunately. The previous thread referenced by Andy will tell you how to remove the solder mask if you still need to, using a hot Lye solution.


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## powermetalx (Oct 12, 2013)

So it turns out that the metal IS in fact gold under the epoxy. Having established that, I'm still at a loss. Any advice on how to get the epoxy off?


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## g_axelsson (Oct 12, 2013)

powermetalx said:


> So it turns out that the metal IS in fact gold under the epoxy. Having established that, I'm still at a loss. Any advice on how to get the epoxy off?


Here you go...
https://www.google.se/search?q=site:goldrefiningforum.com+removing+solder+mask

Göran


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## patnor1011 (Oct 13, 2013)

powermetalx said:


> So it turns out that the metal IS in fact gold under the epoxy. Having established that, I'm still at a loss. Any advice on how to get the epoxy off?



Can you share with us how did you established that?

That is not correct statement.
Metal under epoxy is copper. *Sometimes* it is *flash* plated. 
Recovery of this flash plated gold will not cover expense you will have trying to do it.


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## macfixer01 (Oct 13, 2013)

powermetalx said:


> So it turns out that the metal IS in fact gold under the epoxy. Having established that, I'm still at a loss. Any advice on how to get the epoxy off?




I guess we'd have to take your word on that since you haven't provided any pictures. It's remotely possible the board is coated in epoxy or some other sort of what's known as a Conformal Coating, but usually that would be a relatively thick opaque coating and you may not even see the contours of traces through it. Most likely it's plain solder masking and removable with hot lye solution as described in the earlier threads already mentioned - which I'm guessing you never read? Epoxy potted or conformal coated boards are relatively pretty rare. It's usually used as a security measure on boards for data decryption or that hold other trade secrets the manufacturer doesn't want to allow you access to. I remember it mostly from old cable tv decoder boxes. In any case if you can scratch it and it easily flakes off, then it isn't epoxy, it's solder mask.


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## goldsilverpro (Oct 13, 2013)

I haven't seen good thick gold on the traces since Zerox boards from the early 70's. When gold is under the solder mask, it is typically worth 5 cents to 10 cents per square inch of plated area.


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## ahmadbayoumi (Nov 26, 2013)

Hello ALL,

Is this the same for cellphone broads ?

I mean does it worth to process cellphone PCBs for gold ?

Thanks is advance


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## steyr223 (Nov 26, 2013)

Hi everyone
Aa long as were on the subject there is something i always wondered about.

Since im colorblind i have to look to other ways to determine if its gold

I noticed at least on my material,when the mask covers the gold it flakes real easy with a blade in big pieces, when the mask covers copper it seems way thicker(many more passes with blade)just to get to the copper and its not flakes that come off,i'd relate it to scraping plastic more or less
Anyways why is this and does anybody also notice this

Thanks Steyr223. Rob


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## pgms4me (Nov 26, 2013)

Hello Rob: I have had several makes and types of boards with gold plated copper traces under the soldermask. I have not had any that ever flaked off as you describe. the boards I am reffering to are telecom boards,HP test equipment boaqrds and hi quality 90's server boards. Some is easier to scrape than others,but it all comes off with the lye method.


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## steyr223 (Nov 30, 2013)

Ok sorry 
I was actually referring to gold plated boards
I have only seen a few 
One was round i only received 1/2 the board(complete woud have been app 24" in diameter) it was from sound testing equipment 
Yeild was 1gram per side of my 1/2
(If the. Whole. Board then 4 grams)
The mask flaked very thin

Another were i dont know where or what but they were just green board
About the size of a memory stick(big ones) no traces or even a schematic 
But 30 of them in ap for 4 days and when hit with water the foil came off in
One piece. 
Yeild for about 30. Was 7 grams
These also flaked when scraped

But yes i never saw traces flake sorry
Thanks steyr223 rob


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