Gold on pcb

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Jbroadway

Member
Joined
Oct 11, 2016
Messages
22
Hi all I'm not sure if this is in right place but I have got some pcbs and they have gold traces and I am wondering how everyone goes about processing them
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I have quite a few of those myself, but I thought the gold-tone was copper rather than gold... Seeing as they serve no obvious function towards signalling, it wouldn't make sense to have gold there. And considering how skimpy they are with the gold elsewhere in the electronic parts, I would think that is not gold. I hope I'm wrong though... :wink:
 
The components under the black "blobs" are more likely to contain gold than the traces on that type of board. Soaking the boards in NaOH is one way to remove the green solder mask but I would recommend that you look up the dangers of working with that stuff before you do it and ensure that you follow the relevant safety precautions because it is extremely unforgiving if you get it in your eyes.

Edit: Yes there are certain types of board that gold plated traces under the solder mask, removing the mask completely will help you determine that. One thing of note- differing revisions of the same types of boards can vary a lot.
 
I would agree but knowing that This stuff is out of high end electronics it wouldn't surprise me, I have seen copper traces and they are nowhere near this shiny... as of yet I don't actually have any gold testing kits or chemicals to prove it and was wondering if anyone had this experience


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anachronism said:
The components under the black "blobs" are more likely to contain gold than the traces on that type of board. Soaking the boards in NaOH is one way to remove the green solder mask but I would recommend that you look up the dangers of working with that stuff before you do it and ensure that you follow the relevant safety precautions because it is extremely unforgiving if you get it in your eyes.

Thanks anachronism I would follow all safety precautions and I was wondering if I could get the green mask off thank you :)

Any idea on getting rid of the black blobs??

I pmed you the other day :)


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Ahh I hadn't checked my PMs- thanks I'll go take a look.

Those black blobs are processed in a very similar manner to the BGA and north bridge chips- there's a whole load of resource on the forum with regards to processing those if you look around.
 
:) it's just know what to search for thank you, should I remove them from the boards?


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anachronism said:
There you go. Oh look - gold :D :eek: :D

& its not just the gold plating under the blob (on the board) but for every trace on the board going to the blob there is a gold bonding wire "in" the blob which then connects to the IC chip in the blob

Kurt
 
Yeah, so, no-one is really saying this loudly and clearly, there is almost NO gold on that PCB, it is a gold 'flash' coating over the pads to prevent corrosion before the PCB is assembled. They are pretty much not worth processing.

The gold in you boards is located inside the black blobs in the form of bond wires.
 
Copper traces with gold flash on exposed surfaces. It's called ENIG, do a search. It is used for oxidation protection before soldering and is a lot thinner than gold fingers.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=34&t=21751#p225672

Göran
 
That really depends on how much of it you have. Any gold that will give you a visible result is a good learning tool. If you have only a few of these boards then the answer is probably no from a financial perspective but as a learning excercise- maybe.
 
I agree with anachronism, It depends...

What quantity, which process, what are your labor costs... and so on.

It isn't easy to get it either, most of the gold flash is dissolved in the solder and the unsoldered part you see is so thin it breaks down to microscopic flakes if you dissolve the trace under it.

For me it isn't worth processing it myself, but I toss it in the box for cards that I'm sending out once I have enough to get paid for the content and not a flat rate.

Power supplies and brown boards (old TV boards, radios...) goes into the cards I sell to the local scrap yard for a pittance.

Göran
 
Thanks for all of the input, I think for the learning process I will cut off anything that is exposed and use that and the cards can be boxed :)

Now for learning the processes


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For learning, you are far better to go on ebay and spend too much money for some RAM or trimmed fingers. It doesn't matter if you pay too much, because at least you will end up with enough gold that you can actually see it drop out of solution and melt it into a (small) button.

By processing a few of those LCD boards, you may not even have enough gold to see it drop out of solution and almost certainly not enough to make melting it worthwhile.

Same thing basically applies to those bond-wire-blobs. You want at least 100g or so of them before you are likely to end up with around 0.1g to 0.3g of gold.
 
kernels said:
For learning, you are far better to go on ebay and spend too much money for some RAM or trimmed fingers. It doesn't matter if you pay too much, because at least you will end up with enough gold that you can actually see it drop out of solution and melt it into a (small) button.

By processing a few of those LCD boards, you may not even have enough gold to see it drop out of solution and almost certainly not enough to make melting it worthwhile.

Same thing basically applies to those bond-wire-blobs. You want at least 100g or so of them before you are likely to end up with around 0.1g to 0.3g of gold.

Thanks kernels

I have just trimmed a box of ram for its fingers so have them (though I would like more) I was actually thinking of removing the blobs and trimming all exposed gold off the boards and chuck that into the finger mix would that be a bad idea??



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