Gold on pcb

[kernels]

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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No problem throwing any bits of PCB with visible gold into AP with the fingers, they are essentially the same thing, just with a thinner gold plating. Make sure you have an aquarium air pump bubbling air though your AP, you can also use an aquarium heater (set at about 30 deg C) if the temperature is cold in your part of the world, it will greatly speed up the process. Make sure only the glass part of the heater is sitting in the solution.

I usually try not to mix gold flash boards with cut fingers if the boards still have some solder on them. In theory it should not matter, but I like running 'clean' AP batches and 'dirty' AP batches.

 

[kernels]

These black "blobs" will run much more than BGA IC.

Yeah, good point, those black blobs could be around 1g+ per 100g since they have a better overall mass to gold ratio than a standard BGA. Good spotting there patnor1011

 

[Jbroadway]

Do I need to use any special air lines or will silicone tubing be ok??


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[kernels]

I've never had a problem with aquarium air line tube

 

[Jbroadway]

Can you mix ap with water to get the aquarium heater covered?


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[kernels]

Try to use as little AP solution as possible, makes filtering and clean-up much quicker. Lay the heater sideways if need be, only the bottom part with the heating coil needs to be in the liquid. I just bought the smallest heater available, only has about 2 inches in the liquid.

I would be inclined to add more HCl to increase my AP level, rather than dilute with water.

 

[Jbroadway]

Thanks that's really helpful advice, can I ask do you process plated pins the same way? Even ones that are magnetic? I read something somewhere about it but can't find it now...


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[kernels]

Thanks that's really helpful advice, can I ask do you process plated pins the same way? Even ones that are magnetic? I read something somewhere about it but can't find it now...


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In theory you can use AP to dissolve the base metals out of the non-magnetic (copper based) plated pins, there is a user on here (Tzoax) who has a thread where he does it, but really, you are dissolving away a massive amount of base metal for a small amount of gold.

If you have a large quantity of plated pins, you want to investigate a cyanide type leach (dangerous) or a reverse-electroplating Sulfuric Acid Cell (dangerous). Both of these solutions act on the gold, rather than the base metal.

 

[Jbroadway]

I think I'll stick to the slower less dangerous one for now learn that and get that working right


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[Elektrikis]

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

You are right.

https://www.youtube.com/watch?v=HIYbrFuxBgo

 

[clearsteam]

I think this is useful, a seminar from the industry, whilst most of the "golden" cards that we come across are enig --(2 to 4 micro inches thick) some will be electrolytic gold/hard gold (25 to 40 micro-inches thick) and possibly more on cards where gold has been used as etch resist (rare high end industrial applications often with metal substrate ) http://www.epectec.com/downloads/surface-finishes.pdf