# fingers and other plated boards



## markk (Nov 14, 2016)

Hi;
I was wanting to know just how much non gold/copper can be put in with fingers without causing problems to the process. I have boards that are plated both sides. Some parts I can simply break off and will be clean of solder but some parts will have just a bit of solder on one side. Can I still put this in with the fingers ?
Also if I have small components that are gold and whatever type metal , can i put them in with fingers ? Just a few small parts.

In the pics the small squares are only about 1/4 inch . that is front and back of the square. Just an example of what I am speaking of when I say a bit of solder on one side.

The large boards are lnb . the dark colored one is all gold it just looks like copper in pic and I scraped all parts off with blade. My question on these is how best to proceed. Can I put in HCl and eat away the solder and then AP / HClCl like fingers ? I thought I would not want to just toss in AP because all that solder would contaminate useful AP so perhaps just HCl first as I can save HCL for only this type process.


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## clearsteam (Nov 14, 2016)

I am interested in this, as I have a similar question.

The best solution I have heard so far is to depopulate the boards with nice cheap NaOH sodium hydroxide. I know many on the board pretreat/depopulate with hcl before Hcl/peroxide, but the waste is toxic and needs disposing of separately/safely and for a tightwad like me its ten times the cost.. the sodium hydroxide with tin hydroxide I believe is safe enough to be diluted and disposed down sewerage.

Is there anyone who can disabuse me of this idea? I plan to start depopuating prior to ap shortly.


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## butcher (Nov 14, 2016)

lead is very toxic. treat waste properly, do not dispose of any of this into the sewage. People down river drink what people upriver flushed.


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## clearsteam (Nov 15, 2016)

lead free boards and solder have been required since 2006 and all of the boards that I work with are Pb free, and seem to be marked as such going back to 2000. The SAC solder used is silver/tin /copper, so I think I should be safe. Tin will be dissolved and silver, copper precipitated, Tin hydroxide is apparently safe to enter our waste water system, as is unused Na0H. Waste water in the uk must go through processing and testing before it is allowed back into the fresh water system be it rivers , seas or pipework

I will be observant to ensure that any wastes with lead in are disposed of properly


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## markk (Nov 16, 2016)

clearstream, how do you dissolve solder with lye ? All I have used it for is to remove solder mask , which I have always referred to as " green paint" and never read about anyone using it for solder or parts. 
My main objective here is to get rid of base metal so I can process like fingers. 
I also need to know if I can put any non copper in this i.e. very small parts that are gold plated over tin or iron , or if even small amount would cause problems.

As a side note , the first time I tried to recover gold I used a whole bunch of old stuff, 486, 386, gold capped military stuff.... Lost almost all of it but about 1/2 gram due to Shor international instructions with their sub zero. Tossed it all in aqua and it made a sludge of green paint etc and Although I did get some back I lost most of that trying to melt it as it blew away, and the rest I find out later is locked in solution with the tin that unfortunately I tossed out . I do actually have a little of that left from '06 . I added water and tossed in a spoon. I have not figured out yet how to recover anything from this. Was just told to put stainless steel in.

I will start another thread on an interesting thing of gold flakes from fingers dissolved in lye water.


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## clearsteam (Nov 16, 2016)

Bear in mind that I am still learning, and not put this into practise yet. Lye dissolves aluminium, tin and lead (quite vigorously) which would take away the solder and leave precious metals in the solid residue along with all the chips that fall off.

I had it confirmed by a fellow refiner with experience who currently uses this method.

Im a tight-wad and a bit wary of fumes so it seems ideal for me. BE WARY, the reactions could be vigorous especially with aluminium. Im hoping to experiment with it next week to see if the process suits my purpose.

I have posted on here asking why nobody seems to use this much cheaper much less toxic method of depopulating the boards than HCL bath, and nobody has responded .


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## Shark (Nov 16, 2016)

Lye is a very dangerous chemical. Many people take it as being less dangerous because it is not labeled "acid". With a bit of reading you will find that many base chemicals have serious hazards, often more dangerous than the acids we use.

I would like to learn how the use of lye is less toxic in refining. Can you point us to a good text on it's use?

Another point is that of the waste clean up. If you use only one or two chemicals the waste treatment can be better streamlined to meet your specific needs. Bases often need treating separately from acid type chemical. 

There is much still to be learned. Keep studying you will get there.


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## rickbb (Nov 16, 2016)

I use simple heat to de-populate boards, then soak in cheap Hcl to remove the tin solder. Makes recovery of the gold easier and cleaner gold.


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## clearsteam (Nov 16, 2016)

Shark said:


> Lye is a very dangerous chemical. Many people take it as being less dangerous because it is not labeled "acid". With a bit of reading you will find that many base chemicals have serious hazards, often more dangerous than the acids we use.
> 
> I would like to learn how the use of lye is less toxic in refining. Can you point us to a good text on it's use?
> 
> ...



Thanks for your reply.

Assuming that you have the safety gear on- gloves/gauntlets, apron as you would for HCL, Na0H reacts giving off hydrogen- non toxic.

Left in the open it decomposes to washing soda.

Assuming your boards are lead free, the resulting aluminium hydroxide, tin hydroxide are non toxic and used by waterboards in purification plants, the solution can be relivened by electrolysis or addition of slaked lime.

Lye is 10% of the cost of hcl here. HCL dissolving tin creates highly toxic stannous chloride.

So yes, it does seem safer for the environment and wallet provided proper precautions are taken.

http://www.practicalmachinist.com/v...droxide-caustic-soda-lye-useful-stuff-158041/

Starting to feel that HCL is being used because its the way it has always been done.


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## goldsilverpro (Nov 16, 2016)

clearsteam said:


> Shark said:
> 
> 
> > Lye is a very dangerous chemical. Many people take it as being less dangerous because it is not labeled "acid". With a bit of reading you will find that many base chemicals have serious hazards, often more dangerous than the acids we use.
> ...


So, you've been doing this for exactly 3 weeks, today. I've been doing it for 50 years and I still don't like the dangers involved in working with sodium hydroxide. It's far, far safer working with HCl. I don't buy anything you just said. As far as I'm concerned, the 2 most dangerous chemicals we use are concentrated sulfuric acid and strong sodium hydroxide solutions. Both increase 10 fold in being dangerous when they are hot. Maybe, when you've been working with these chemicals, daily, for 4 or 5 years and after making 500 posts, you'll be qualified to make valid suggestions that will get no one hurt.


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## clearsteam (Nov 16, 2016)

acid/alkali , both need to be treated with respect, both can muck your life up. 

one is sold over the counter everywhere, the other is limited to chemical and building supplier, which is the most dangerous do you think?

I think you're maybe kicking yourself for having caused so much toxic waste with HCL and all the dollars going down the drain.

I have been on the forum for three weeks,been dismantling and recovering gold from IT for nearly six months without attempting processing (other than small experiments), researched papers and methods outside of this site, I like to get to source material and information, and a few months after the research began I found this great site where people share their practical experiences as they learn. This is a VERY VERY useful resource and methods are constantly developing, such as the AP process.I did study chemistry thirty years ago band and live a life by logic and tradition, some traditions have been lost, and some seem set in stone that perhaps shouldnt be as the nature of the ores you are working with change.

I may be wrong, but experiment is the only way to prove it


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## markk (Nov 16, 2016)

clearsteam said:


> Bear in mind that I am still learning, and not put this into practise yet. Lye dissolves aluminium, tin and lead (quite vigorously) which would take away the solder and leave precious metals in the solid residue along with all the chips that fall off.
> 
> I had it confirmed by a fellow refiner with experience who currently uses this method.
> 
> ...



Lye is strong stuff. I used it a lot over the years for other things. I soaked boards in very strong solution to remove solder mask without heating but never had it eat away at anything else. 
Solder mask removes at 20% with heat so perhaps a stronger maybe 50% and heat is needed to attack metals.
In another thread I posted today you can find what happened to a freinds gold flakes with strong lye. 

I will be cleaning some LNB boards soon and I will experiment with different moles of lye and heat to see what happens.


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## markk (Nov 16, 2016)

rickbb said:


> I use simple heat to de-populate boards, then soak in cheap Hcl to remove the tin solder. Makes recovery of the gold easier and cleaner gold.


That is what I am going for. I figured acid first to get rid of a lot of stuff then AP . Just was not sure about using AP first as I hear it is not great for base metals but then others say use it for pins . 
I will go with HCl hot then AP then clorox. Well maybe AP twice with a good wash as I read earlier it is needed for pure gold .

Wish I would have known all this in 06 . Big chunk of gold gone .


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## Shark (Nov 16, 2016)

I guess location may play a large part in it, but HCl can be bought off the shelf here in one of this countries largest retail chains, Wal-Mart. Lye is another story, quite often very hard, if not impossible to find on the shelf any more. I worked with lye on a large scale from the early 80's until around 2005. Believe me when I say it demands respect. The little bit of refining I have accomplished leads me to agree wholeheartedly with GSP, lye and sulfuric are two of the most dangerous chemicals we use. As for dollars down the drain, I am not to sure what you mean. My first two gallons of HCl was used to make up my AP somewhere around three years ago, and I am still using it. I use it less often these days, but I do still use it. With work and study you will find a lot of the chemicals can be used over when handled right.


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## clearsteam (Nov 16, 2016)

markk said:


> clearsteam said:
> 
> 
> > Bear in mind that I am still learning, and not put this into practise yet. Lye dissolves aluminium, tin and lead (quite vigorously) which would take away the solder and leave precious metals in the solid residue along with all the chips that fall off.
> ...



did you try depopulating boards with lye? I know it needs heat to speed up solder mask removal, but if left long enough the solder mask will dissolve anyway. the reaction with the solder should be more vigorous than the slow eating up of the mask. I do not want to heat any acid or base unless absolutely necessary (such as kovar pins). A vat of boiling acids/alkalis would require some serious serious safety precautions.

try mixing lye crystals with warm water to saturated solution, then add boards slowly , remove alu heatsinks , capacitors if possible to prevent too much fizzing. solder should be dissolved within a few days if not hours, residue in bottom of vessel should be mostly silver and a teensy proportion of the gold plate that had been dissolved in the solder.. (on top of the grit of mlccs and other tiny smds.)

I read your post abut lye dissolving gold.. you had not sinsed/removed the hcl, the na0H freed up the CL in the HCL to dissolve the gold, you have gold chloroaurate in solution, its still there, accidentally.


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## markk (Nov 16, 2016)

I must say as far as what I have used lye and acid for the lye is far more dangerous to play with. As far as refining goes I would not know which is less dangerous . To me dangerous is blowing up, burning me , deadly fumes... I have soaked in acid many times and the fumes dont bother me unless thick and all I know is lye getting on you is far worse. I am notorious for not wearing gloves. 10% lye does not bother me much but stronger does.


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## clearsteam (Nov 16, 2016)

If thats the way you play then its best leave any chemicals alone and stick to salt and vinegar :wink:


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## markk (Nov 16, 2016)

clearsteam said:


> If thats the way you play then its best leave any chemicals alone and stick to salt and vinegar :wink:


well im still alive after many years of chemicals . Might be a bit damaged. I would not suggest using my methods of safety.

Does that salt and vinegar actually work ?


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## Grelko (Nov 16, 2016)

markk said:


> clearsteam said:
> 
> 
> > If thats the way you play then its best leave any chemicals alone and stick to salt and vinegar :wink:
> ...



Yes, it does.

https://www.youtube.com/watch?v=ouYW_7-Njbs sreetips (kadriver) has some really good videos

Normally, I'd say stay away from Youtube videos for gold refining, but there are a few members here that make them.


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## markk (Nov 17, 2016)

clearstream; I have not used the lye for anything but loosing up solder mask. I started with 40 mole I think it was and then just dumped in a bunch more. Used it cold just sitting in a bowl . Took a couple days and then I brushed off most of the green with a tooth brush. Then rinsed and dipped in vinegar to neutralize. 
The boards were depopulated already. Never noticed it eating up any solder or doing any fizzing at all. 
I depopulate with a large pair of wire cutters a small pair and a special pair of pliers and then cut all SMD off with a utility knife. Anything I dont want to ruin I use a desolder station. Heat gun keeps blowing fuses around this house so I dont use it any more.

That gold in lye , I think he said he just filtered it from the AP and it had paint in it so he pured straight lye over it in the filter. I dont remember but I think he said he poured water over that but it may have been the rest of the AP he was filtering .


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## markk (Nov 17, 2016)

clearsteam said:


> If thats the way you play then its best leave any chemicals alone and stick to salt and vinegar :wink:


I worked in a aircraft parts plating company . We had a round vat that sat on the floor in the paint & parts stripping area. It was about 2 feet tall. If you tripped you would fall right in it. It had something really bad in it. Black nasty smelly stuff. I forget n ow but I think it was called black oxide .... All I know is if you got any on you it would eat a hole right on through if you did not stop it. The only way to stop it was to pour sulphuric on it and then hit the rinse water tank to get rid of that. Never got any on me but that is what they told me to do if I did.


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## goldsilverpro (Nov 17, 2016)

Clearstream,

As a moderator, one of my responsibilities is to help prevent injuries to our members. It's obvious that you don't know enough to advise anybody on this forum about anything. If you continue advising people about *anything* involved with refining or the use of any chemicals, I will ban you.


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## goldsilverpro (Nov 17, 2016)

markk said:


> clearsteam said:
> 
> 
> > If thats the way you play then its best leave any chemicals alone and stick to salt and vinegar :wink:
> ...


The main chemical in a black oxide solution is lye or sodium hydroxide.


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## markk (Nov 18, 2016)

goldsilverpro said:


> markk said:
> 
> 
> > clearsteam said:
> ...


Yep , I think this must have had something else in it also as I cant think of any reason one would need sulphuric to neutralize lye unless of course it was the only acid available in that area of the shop I suppose. 
I tried to keep my distance so I would not find out.


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## FrugalRefiner (Nov 18, 2016)

Since you've mentioned it again, I can't imagine putting sulfuric acid on my body intentionally. HCl or acetic maybe, but not sulfuric. Perhaps the information you were given was wrong. Perhaps there is something about the bath I don't understand, as I've never worked in a plating shop. 

My only point in making this post is to caution anyone who may read it in the future that sulfuric is one of the most destructive acids to human tissue, and that they should not intentionally use it to neutralize a sodium/potassium hydroxide bath.

If I'm wrong, I hope that GSP will let me know.

Dave


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## goldsilverpro (Nov 18, 2016)

The acid would obviously neutralize the sodium hydroxide. As I've mentioned several times, I used to keep a bucket of about 2% HCl to neutralize any cyanide I might get on my hands. After rinsing well with water. I dipped my hand into the weak HCl and then rinsed again with water. I would think one could do the same with sodium hydroxide and a very weak H2SO4 - say, 1% by volume. Of course, very weak HCl could also be used.

With either cyanide or sodium hydroxide, it is very easy to determine whether or not you have neutralized or removed them completely. If, when you rub your fingers together, it feels "slick", there is still some of the chemical remaining. When I used the HCl on cyanide, this "slickness" was immediately gone.


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## anachronism (Nov 18, 2016)

Also the "slickness" Chris refers to is the action of the alkaline solution on the skin i.e. Dissolving it. Think of how they used to make soap.


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## markk (Nov 19, 2016)

I use vinegar since I buy it by the gallon and i can pour it in the house without fuming me out of the house.


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## goldsilverpro (Nov 19, 2016)

markk said:


> I use vinegar since I buy it by the gallon and i can pour it in the house without fuming me out of the house.


Vinegar would work fine - I just don't care for the smell. 

Surely you're not refining in your house!


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## markk (Nov 19, 2016)

goldsilverpro said:


> markk said:
> 
> 
> > I use vinegar since I buy it by the gallon and i can pour it in the house without fuming me out of the house.
> ...


I like vinegar . I drink a good swallow now and then. No, not refining in the house . Just the lye for the solder mask. I am thinking of buying the little system shor has with the filter on it. But I think from looking that filter system is nothing more than a column of charcoal. Can make that myself . 
Dont have a place to refine at here besides in house or outside on porch.
Thinking I would make a hood in my utility room to vent everything out the roof during cold weather . But then I will have to be going back to work soon and I drive a truck so I might not do anything until summertime anyway maybe during a holiday. Not home when driving except on weekends for a few hours. I'm just sitting around now for a few months or six being lazy.


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## kernels (Nov 22, 2016)

One thing that is probably worth mentioning in this thread is that unless you are processing very special boards (out of old electronics test gear for example), that gold 'plating' that you see is almost non-existent. ENIG is roughly 4 microinches thick, as a comparison, a gold bond wire (which is pretty much invisible to the naked eye) is 500 microinches.

Gold plating on 'fingers' like RAM or PCI cards is much thicker (in the 50 to 300 microinch range) and is obviously worth recovering. 

It is really not worth the risk or hassle to recover ENIG gold as a home refiner. But, probably worth trying for yourself once, because no-one ever believes it when you just tell them the answer.


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## goldsilverpro (Nov 22, 2016)

kernels said:


> One thing that is probably worth mentioning in this thread is that unless you are processing very special boards (out of old electronics test gear for example), that gold 'plating' that you see is almost non-existent. ENIG is roughly 4 microinches thick, as a comparison, a gold bond wire (which is pretty much invisible to the naked eye) is 500 microinches.
> 
> Gold plating on 'fingers' like RAM or PCI cards is much thicker (in the 50 to 300 microinch range) and is obviously worth recovering.
> 
> It is really not worth the risk or hassle to recover ENIG gold as a home refiner. But, probably worth trying for yourself once, because no-one ever believes it when you just tell them the answer.


Actually, I think it's a little worse than that. If I remember right, gold bonding wire is either .001" diameter (1000 microinches) or .0007" (700 microinches). One troy ounce of the .001" wire is 2 miles long and a troy ounce of the .0007" wire is 4 miles long.

A plating website for the immersion gold (IG) part of ENIG, for general purposes, gave a thickness of between 3 to 5 microinches. For soldering applications, it can be as thin as 1.6 microinches. A 4 microinch gold coating is worth about $0.05 per square inch.

I have used a lot of real gold leaf (usually 23K) for signmaking purposes. It's about 3.5 microinches thick. When they are applying it on windows, you can see light through it.


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## kernels (Nov 23, 2016)

Absolutely, I made the mistake once of paying good money for 'gold plated' telecoms boards, the boards were about the size of an A3 sheet of paper and fully 'plated' on one side, almost couldn't see the gold drop from that solution! Money wasted, lesson learned.


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## goldsilverpro (Nov 23, 2016)

Immersion plating is essentially a cementation process and its thickness is self-limiting. Unlike the cementation we do as refiners, there are other chemicals in the IG solution that insure adhesion of the gold to the base metal. When the gold deposits, some of the base metal must dissolve. When the surface is 100% coated, the plating stops. This is because the solution can no longer penetrate to the base metal.

I've read that the maximum thickness of immersion gold (IG) is 10 microinches. In another place, they said 20 microinches, although, from my experiences, I would doubt that. When they call out a thickness of 1.6, 3, or 5 microinches, it makes me wonder how they are measuring that thin of a coating. Is it based on actual thickness or is it based on what the thickness would be if the mass of the gold per unit volume were 19.3 g/cc? Probably the former. By definition, IG is an extremely porous coating. Therefore, a measurement of 5 IG may only contain the same amount of gold as an electroplated gold layer of, say, half that thickness. In other words, there may only half (or, whatever) as much gold as you think there is, based on the specs.


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## markk (Nov 26, 2016)

Yes that plating on them LNB is very thin on some as it actually looks kind of silver , I guess the copper underneath is making it look that way. Them boards seem to have lost their gold plate in the very strong lye solution. 
I was going to use these LNB's and such just to add in to my fingers and other good gold but am thinking of just selling the boards on ebay along with all of my pins and perhaps the Ic's, flatpacks, memory... Not sure yet but looks like just as much money to be made by ebay as refining it. 
but I do like to experiment and do things like refining even if I do not make a profit so I might just refine it all with the exception of the thin LNB as it seems like that is more of a waste of chemicals unless perhpoas you had a whole lot of them.


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## FrugalRefiner (Nov 26, 2016)

markk said:


> Yes that plating on them LNB is very thin on some as it actually looks kind of silver , I guess the copper underneath is making it look that way.


Nickel. Gold is rarely plated directly onto copper in electronics because the gold will migrate into the copper over time. Usually, the copper is plated with nickel first, then gold. The gold has a much more difficult time migrating into the nickel. That's why very thin plating can look silver.

Dave


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## markk (Dec 6, 2016)

That would explain the silver look. I have taken up selling my boards that look thin on ebay for a couple bucks a pound after I depopulate and strip the solder mask. I figure someone can practice on them or just add them in with their other stuff to refine without having to do the crap work first. Heck I paid 2 bucks a pound for them.


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## saadat68 (Dec 29, 2016)

Hi 
why you say don't use sodium hydroxide when we use it in scrubbers ? :idea: 
You really fear me :
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?p=264388#p264388


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## Yggdrasil (Feb 7, 2017)

Hi!
I'm stepping into this thread since it is about boards and fingers.
I have finally been processing fingers and boards in AP for the first time and lo and behold I ended up with a couple of "mistakes" even if reading here for a long time :wink: 

I started with a mix of fingers and whole depopulated rams and small PCBs. 
Whole PCBs since a few seamed to have gold plating not only on the finger area, mainly ram sticks.
First error, forgot to weigh them  I'll weigh them after so no big deal.

Added 30 percent HCl and water 1:1 + appr a dinner spoon or so with 10 percent H2O2. 
After a week there was still no green color, so I added another spoon peroxide 
and the solution turned green within 10 minutes.
This is where I realized "mistake" number 2. 
I had not dissolved the solder first, maybe that is why it was slow to start? 
Or perhaps the temperature slowed the start down since it was below freezing outside?

Now a month or so later the solution was getting more transparent even if some of the foils was still sticking. Mostly it seems because of through hole plating. 
But there are also foils that seems embedded/locked by solder mask, which reveals "mistake" number 3. 
I should really remove solder mask before processing.

Now I have mostly filtered and separated the PCBs from the foils.
They have been put back into AP to clean out the rest, but they seem stubborn.

Which leads to a couple of questions:
1. The foils is surrounded by a black fine powder and some solder mask remnants.
What is this black powder? Is it solder or copper powder? 
It is going to have a second leach in pure HCl before beeing washed and cleaned according to forum recommendations.

2. If the PCBs are leached to end and kept wet, will substantial losses be expected if the remaining gold on 
PCBs are leached with AR or HCl/Cl?


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## patnor1011 (Feb 7, 2017)

1. It also can be gold. Many plated items are just flash plating which can break down as a brownish/blackish powder.
2. Not good idea. Firstly you are chasing pennies while spending dollars. That plating remaining on boards will be only few dollars worth while you will need quite a lot of solution to leach it out. Not to mention that you will not leach it out anyway unless you dissolve all other metal present what in case of pcb is not possible unless it is finely shreded. Pcb contains layers of copper, nickel and substrate which will suck up any dissolved values as soon as they dissolve. 

AP is not throw and forget type of leach. In order for it to work the best agitation is the key. Most of the folks achieve it by using aquarium air machine and introduce air in solution which helps to oxidize and keep leach in motion. Much better than having to agitate solution several times a day.


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## Yggdrasil (Feb 7, 2017)

Hi Patnor
Thanks for the answer.
I did not mention my agitation, of course I have agitation 
I'm using this nice little four port Sera aquarium pump.
I can keep 3 pots leaching and still have one spare for the stock pot 
I was hoping that it was possible to leach out all the copper.
Some of the Ram sticks have quite a few through-hole plating which hold remarkably well together.
I can not flush them off with quite powerful water jets from a squirt bottle.
My guesstimate is that on some of sticks the area can be as much as a few fingers.
Oh well, I'll give them a couple of weeks more and then see how clean I can get them.


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## ashir (Aug 12, 2019)

What about using h2so4 and fertilizer to get rid of solder and copper? 
And yes it's also need too much safety acts working with h2so4 and filtering it is a nightmare,but weak h2so4 and fertilizer urea can work to get the clean gold ?


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