# Question: Circuit Boards with AP Process



## takenbyvultures (Jul 26, 2012)

Hello, I have just started processing trimmed gold fingers using the AP method in a 5gal bucket with bubbler and everything is working well so far. I was wondering if I would be able to use the same process on the boards shown below, or does it need to be reverse electroplated. If I was to use the AP method would I need to remove any ceramic memory modules, plastic clips, etc, or just leave them on? Also it appears that the channels on these boards are gold plated, do you guys agree? Would these boards give good yield? I also purchased lazersteve's DVD, waiting for it to arrive, hopefully it helps with everything. Thanks a lot!


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## publius (Jul 26, 2012)

soak the subject boards in HCl to remove the tin and other components.
use lye to remove the solder mask.
THEN
process with AP

I am sure that others will be able to correct me if I have erred in the above information.

You may also want to review this thread: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=58&t=14768


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## martyn111 (Jul 26, 2012)

publius said:


> soak the subject boards in HCl to remove the tin and other components.
> use lye to remove the solder mask.
> THEN
> process with AP
> ...



The only thing I would add to your reply is to save any components that you remove, there are a lot of PM's contained within the chips and monolithic capacitors, and then read up on the forum how to process these materials.


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## takenbyvultures (Jul 28, 2012)

Thank you for your replies, they are very helpful. When I do the initial Soak in HCl, should I run the tubes in from the agitation pump like I do for AP process, or will it not effect it without the peroxide at that point? Also, do I add lye directly to the HCl after it has soaked for 24 hours, and approximately how much lye per gallon of HCl? Again, thank you very much for the insight.


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## jimdoc (Jul 28, 2012)

You don't use lye and acid together, that would be a big mistake. 
They are separate processes. 

http://boards.straightdope.com/sdmb/archive/index.php/t-110255.html

Jim


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## takenbyvultures (Jul 28, 2012)

Thanks for the info, I read on wiki that mixing caustic soda and HCl would only make saltwater, so it shouldn't be a big mistake, but still not ideal =) After soaking the boards in HCl should I removed them, then put them in a different container with lye dissolved in water? Thank you, I love this board, lots of great info, I read hoke's book and ordered steve's dvd, but it's so much information to retain.


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## jimdoc (Jul 28, 2012)

I don't mess with boards like that, I just sell them as is. It is far better to learn with gold fingers than whole boards. Even when you have the ability, boards are often not worth it for a lot of people. 
It depends on how involved you want to get. The others that do whole boards will be the ones to offer any help on that.

Jim


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## jimdoc (Jul 28, 2012)

Also all that gold you see on those boards, and any that "may" be under the solder mask is very thin, and looks better than it actually is.

Jim


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## Geo (Jul 28, 2012)

when dealing with the type of board in the picture, it take a large quantity to have a measurable return.only the area that gets touched repeatedly (keypad) has gold of any thickness. the rest is more than likely RF shielding. if you could peel it off in a sheet, you could see right through it.

but hey, gold is where you find it. if you had many pounds, it would be well worth doing.


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## takenbyvultures (Jul 28, 2012)

That makes sense, like I said I have about 150 pieces of each board, so a fairly large quantity. I'm still working on the AP process for trimmed gold fingers so I think I'll stick with that for now and not get ahead of myself. I'll probably set these boards aside or run 10 through and see what kind of yields I get, see if it pencils out. Oh another question, it doesn't require a whole new thread. I just broke down the pins from 10 sd cards and ran them through an AP mix and they seem to be breaking down nicely, has anyone here attempted this with SD cards? I have 15,000 of them, so I think it might be worth the trouble, any tips? Thank you.


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## takenbyvultures (Aug 1, 2012)

Thanks for all of the help everyone, I got my first gold button today, no luck with a propane torch, had to buy a MAP one but it did the trick! I'm soaking these boards in HCl right now, it's pulled lots of pieces and debris off and settled to the bottom, should I bother with the lye or go straight to AP process? Lye seems dangerous and not sure where to get it, besides the draino stuff, but I believe i read somewhere that it had aluminum flakes in it?


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## Geo (Aug 1, 2012)

it depends on whether there is gold plating under the solder mask. if its just copper underneath, dont worry about removing it. if theres gold under the solder mask (unlikely but not unheard of) it has to be removed or the AP will not remove the gold foil underneath it.


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## NobleMetalWorks (Aug 1, 2012)

You might want to think about stripping the components before putting the boards into HCL. Sometimes, some of the chips have polymers between the layers that can create gel like substances when introduced to acids. I generally try to remove components before I put the boards into HCL. This way I am able to use my HCl longer, and retain the components for processing later. 

I found a cast iron wok and attached a heating element and filled the wok with play sand. I simply lay the boards on the sand, the solder melts off and I'm able to pluck the components from the board without too much issue. Most of the solder comes off this way so I use less HCl, plus I am not putting unknown things into my HCl stripping tank.

The short version would go like this. Put the boards on your solder stripping sand/wok, introduce into an HCl tank to strip whatever other base metals might be on the board, wash and introduce into a solution of sodium hydroxide and water at a ration of 5 to 1 water to sodium hydroxide to create a lye solution that will strip the soldering mask, wash when finished and introduce into your AP tank, collect the foils and dissolve in HCl/Cl and process from there. 

I learned my lesson about weird polymers in solution. I had stripped a bunch of boards with plastic chips that had sandwich layers. The chips fell apart after the HCl attacked whatever binding polymer was between the plastic material. When I went to retrieve the boards, the HCl solution turned into a gel. When it came time to deal with the mess, I had to reduce the solution down by evaporation to solids, then roast the solids, dissolve them in acid again to make sure I didn't have any values locked up in the weird gel material. It took a full week just to dry the stuff out, I didn't want to put it directly on heat because I was afraid whatever the stuff was, it was going to cause issues with whatever I cooked it in, so I waited until it was dry.

This method seems to work really well for my purposes, but everyone is different so please don't take what I said as the only correct way of processing your boards. It's only a suggestion.

Scott


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## takenbyvultures (Aug 1, 2012)

Lots of great ideas, thank you. The HCl is very rich with various debris like you said, this makes me think it's not worth dropping them straight in since I wouldn't feel comfortable re-using the HCl. I'll have to try that wok trick, do you think it will get hot enough on a basic hot plate (300 Deg F)? I'm not sure if this is a stupid question, but is it possible to use stannous on the used HCl to determine what has dissolved in the solution from the boards?


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## butcher (Aug 1, 2012)

If just HCl was used no values would dissolve, straight HCl will not dissolve copper without an oxidizer like air, oxygen, or diluted hydrogen peroxide, if using an strong oxidizer like 30% hydrogen peroxide or nitric then the values can dissolve into solution, but if elemental base metals are un-dissolved the base metal will displace the values from solution, the base metal will dissolve into solution (oxidize losing electrons) and the values will cement onto remaining base metal or form insoluble metal powders, as the base metal is oxidized it gives electrons to the more valuable metal in solution so that the oxidized values become metal again (reduced gain of electrons).

So to answer your question the stannous chloride will not test for values that are not dissolved into solution (oxidized).

If you did not dissolve the values into solution you will not have any values to detect in solution with the stannous chloride test.

If you dissolved the values, but not totally dissolve all of the base metals were not totally dissolved you may not have values in solution, although you could by chance have some.

Also remember base metals in electronic components can be inside a component like layers of copper in between layers of fiberglass on multi-layer circuit boards, or under solder mask, or inside electronic packages like CPU's, if the acid reaches the metal and had gold in solution the gold could now be cemented inside these areas where you cannot see it anymore.

The stannous chloride test reduces values that are oxidized in solution the tin chloride gives electrons to the values, but also keeps them in solution as colorful colloids (colloids are metal particles that repel each other keeping each other in solution and not precipitating to the bottom of the vessel), the colorful reaction which help us determine if the metal we are looking for was in solution.

Very fine particles of gold like brown or black powdered elemental gold (like cemented gold) or very fine flakes of gold will normally settle to the bottom of a vessel, unless the solution is dirty with things like oils from your hands, dirty solutions from circuit boards oils heat sink grease, organic materials, or other nasty substances like tin from solder or a thick dirty copper chloride solution, these dirty solutions can hold fine elemental gold in solution, and the gold being a fine metal powder the stannous test will not detect it (the gold is already reduced, and stannous chloride cannot reduce it to the violet color).

Letting a solution settle the fine gold powder or flakes will normally settle, some floater can be sunk with a mist from a water spray bottle, and filtering solution may recover fine gold that is held in solution if there is any, but if tin (the gold could have formed colloids which will not settle) if the tin is involved then you may find even filtering almost impossible in this case the goop (if values involved) are best dehydrated, neutralized, rinsed, then dried, and incinerated, then the oxidized metal powder given a boil in HCl to help remove the tin.

Tin in nitric is impossible to filter, tin in HCl is not much better.

If you washed your material in HCl to dissolve the solder (tin will dissolve into solution), and, you did not use a strong oxidizer, then you did not dissolve gold, (some silver if involved in the solder along with lead will form insoluble white or gray chloride powders as the solder breaks down (these two metals can be separated with boiling hot water, lead chloride in hot water is somewhat soluble silver chloride is insoluble), the HCl alone without an oxidizer can help to remove some of the troubles discussed above concerning the tin in solution.


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## NobleMetalWorks (Aug 1, 2012)

I vote this to be a sticky

Nice post Butcher!



butcher said:


> If just HCl was used no values would dissolve, straight HCl will not dissolve copper without an oxidizer like air, oxygen, or diluted hydrogen peroxide, if using an strong oxidizer like 30% hydrogen peroxide or nitric then the values can dissolve into solution, but if elemental base metals are un-dissolved the base metal will displace the values from solution, the base metal will dissolve into solution (oxidize losing electrons) and the values will cement onto remaining base metal or form insoluble metal powders, as the base metal is oxidized it gives electrons to the more valuable metal in solution so that the oxidized values become metal again (reduced gain of electrons).
> 
> So to answer your question the stannous chloride will not test for values that are not dissolved into solution (oxidized).
> 
> ...


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## goldpete (Aug 10, 2012)

i soak my boards in nitric for 2 days , it works so well , the boards come out completely stripped , every single thing comes off them and i see gold flake everywhere


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## patnor1011 (Aug 10, 2012)

You will also see dissolved tin everywhere. It will be gel which makes filtering nearly impossible. This get will coat your flakes too. At this stage it will be difficult to get rid of that.


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## im1badpup1 (Dec 27, 2017)

Its an old thread i know but, to aid filtering tin in hcl, its a very fine powder what clogs the filterpaper wanting to hold onto the liquid its in?

What i do with similar problematic materials when filtering is use an inert material the powder gets trapped in without instantly blocking. Packing glass wool onto the filter paper, youll figure how densely, and filter small amounts before emptying the buchner filter, dont suck each batch dry concentrate them down and do it all in one at the end. Squeeze out the glass wool and reuse the wool. Using two filter papers believe it or not helps somewhat.
Apply the vacuum slowly each time. To fast and hard compacts the material too tightly blocking the paper.
(As an example of what i mean dairy milk filters are a layer of paper then cotton wool then paper to prevent filters clogging or slowing down in use)
Any material whats difficult to filter because it clogs check out using things like glass wool, sand, even salt layered on top of the filter paper depending on what youre filtering, just be sure its inert or easily separateable.
Ive used a soft brush before today gently moving the hard to filter material on the filterpaper as it vacuum filters. It does noticably help but you dont really want to be tied down doing this unless theres no other option.

That 'gel' been described i think a substance like that you could do some research and find something to add as a decoagulant.


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