# Depopulating circuitboards as best as I understand to be the best/proper way



## punkymunk (Jun 24, 2017)

If I have populated boards that have gold plating/flashing that I want to recover from the boards themselves... from what I understand thus far as the best/proper process would be...

After cherrypicking certain components of interest (MLCCs of a certain size & larger, IC chips, SMB Tantalum Caps, IDE-type pins, etc.)...


1. Hot sand bath to remove the remaining soldered on components (or maybe heat gun and tapping?)

2. Then hot HCL soak to remove any remaining solder (I'm assuming in a sealable beaker or other heat-safe glassware and to me "hot" is a relatively loose term... not sure if just heated or boiling in some manner)

3. Then Lye bath to remove solder mask (for the boards with gold under the mask)

4. Then HCL + airbubbler ..or.. AP method to remove the gold plating/flashing foils (of in which I still have some questions about this method even with just the simple gold fingers recovery)

5. Filter, rinse and collect said foils until later for some sort of refining process and save whatever other possible particulates to later figure out what might be in it.

6. And secure & save the HCL for future depopulating only use until it is spent


Am I right in the steps above? Or am I missing something or too many steps?

Also... could I not just skip the hot sand bath and let the hot HCL soak remove the various components since that "eats" the solder that holds them on? Granted I would snip off any aluminum capacitors first (my scrap yard allows me to add those caps to my sheet aluminum scrap) since HCL reacts violently with aluminum and remove as much plastics as possible.

Like others on here... I'm not exactly looking for profitabilty vs time and whatnot per se right now. More of a just wanting to learn here in the beginning and is a hobby of a sorts. Profit considerations can come later on once better perfection of methods and eventual better understanding of various chemicals used... and of course more experience. For the moment, HCL (muriatic acid I should say... not lab grade) is the only chemical I feel comfortable enough to start using. And outside use at that.


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## Topher_osAUrus (Jun 24, 2017)

Instead of breaking up the quotes, I will respond in line in red text.



punkymunk said:


> If I have populated boards that have gold plating/flashing that I want to recover from the boards themselves... from what I understand thus far as the best/proper process would be...
> "best" is all a matter of perspective, my friend.
> After cherrypicking certain components of interest (MLCCs of a certain size & larger, IC chips, SMB Tantalum Caps, IDE-type pins, etc.)...
> Why just the big ones?..I understand "bigger is better", but, if you do your hot sand bath, then sieve them out, or use a good neodymium magnet to pick up the nickel layer, that makes life a little bit easier. Maybe the other guys have a better suggestion than that, afterall, I gave up on doing my own escrap.
> ...


Do everything outside for now, until you have a good fume hood system. Muriatic seems mild, but, don't forget that it's Cl thats in there, and breathing that in can be pretty detrimental to your health. Just use PPE, and common sense and caution, you will be fine. There is a huge library of information now at your disposal, take your time and learn from the great guys who built this forum
Welcome, and enjoy your stay


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## snoman701 (Jun 24, 2017)

make sure you are testing your HCl from step 5 prior to disposal. With an oxidizer present, you run the risk of picking up gold.


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## snoman701 (Jun 24, 2017)

And honestly, don't try to process every bit of gold...learn the easy stuff, then get rid of the hard stuff. 

I've got boxes of boards, and no time to process anything right now....but I basically set a price point where I'll chase, anything that falls below that, it's not worth it.


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## eastky2 (Jun 24, 2017)

The first question is how old are your boards? Do you mean gold traces on the board or gold flashing as in a gold shielding or gold flash as in being there to help protect the copper traces.

Gold traces are found on old HP tektronics boards. Gold shielding is found on high frequency components and boards. Gold flash like on sticks of memory and cell phone boards.

What do you have?


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## punkymunk (Jun 24, 2017)

Topher_osAUrus said:


> Instead of breaking up the quotes, I will respond in line in red text.
> 
> 
> 
> ...



Thank you your time and info. I'll add your insights to my notes that I've been trying to take. I have read here and there about copper (II) chloride and copper (III) chloride in which I'm still trying to figure that all out and so forth. I've even begun reading Hoke and can already tell that I'll probably need to re-read it several times since, so far, it appears to be aimed at jewelers and dental work. As said before... the various chemical processes for me are still down the road. Although from what I've read thus far about AP and "poor man's AR... seems to me that PMAR would be better for smaller stuff like printer ink ribbons, mylar ribbon cable ends with gold plating and so on but that maybe AquaRegia would be best for the bigger stuff. I honestly don't know yet though. Still reading and trying to learn.

I guess I should've added that my main reason for this posting was for the first couple of points at the present time. I have accumulated quite a bit of boards that I want to de-populate and clean off any residual solder so I can add to my "Ready for AP" pile of stock for when I'm ready to attempt that process later on. Including fingerless RAM sticks. But I just thought adding the rest of those steps would be good to know if I understand that much already or not for later as the whole recovery (not refining) process.

As far as the pennies worth of possible reclaimable gold under any solder mask... since I'm just looking at the hobby aspect for now, to me low yield is still yield. But I do see why you said that from a time & profit standpoint.

Yes I read a lot about the dangers of hot lye and had good success with it thus far from removing solder masks from laptop keypad boards. But I have found plenty of populated boards, like sound cards and various phone boards, that has gold under the solder mask. Those are primarily what lead to this posting actually. Boards with just copper underneath with maybe specs around tiny holes, I just toss into my e-waste recyclable boards for my scrap yard. So in some regards I guess I do factor some yield not worth my effort lol.

In the cherry-picking... I just assumed that picking off some of the bigger desirable stuff would actually be easier beforehand vs afterwards (like removing the MLCCs before removing CPU pins from the fiberboard)with everything else mixed in since other stuff are magnetic as well like diodes, resistors, and so on. And please correct me if I'm wrong on this point but... I know some of those MLCC looking items are inductors and not capacitors and don't have any PM except for maybe the solder that holds them on and if mixed together, it would be much harder to differentiate them apart or if left mixed together could generate their own unnecessary setbacks when attempting to process MLCCs for their potential PMs.

I asked about just using HCL to depopulate because I've read & seen where some have and they make it seem super easy and was just wondering if the hot sand bath was an unnecessary step. But I also know they're more professional at doing this. By no means do I want to cut corners but I also don't want to end up doing more than necessary in process steps if possible. Think of a bottle of water to drink... some may open the bottle and drink away and some will open the bottle, pour into a container, then drink away. From my point of view the pouring into a container is an unnecessary step where the result is still the exact same with the added extra cleanup, or disposal, of a container afterwards.

I see my error on point 6. I meant that as in save the HCL from depopulating (if that route is taken) and solder removal separate from each other as well as separate from any AP usage for later use until spent. I already know about where to take my spent acid wastes for my area when the times comes to that.

Yes... outside I have learned (the hard way actually from 2 years ago with attempted heating of HCL on CPU pins... still in the beaker dried awaiting further down the road learning) is the best way until I can get another outbuilding in place and a fumehood. I will have to admit that trying to navigate this forum with my own questions before posting is a bit tedious with so many search results not pertaining to, or giving enough specific info, to get my answers and wind up with tons of info (and arguing & bickering & insults & excessive repeating of this n that that doesn't appear relevant to one's actual posting.), but I do try and have learned a little bit that way.

But in the meantime of learning... the e-waste is piling up and what's already been snipped and saved separately is gaining weight. One positive forward thinking point is, once ready to start, I'll have plenty to process and eventually refine


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## punkymunk (Jun 24, 2017)

snoman701 said:


> make sure you are testing your HCl from step 5 prior to disposal. With an oxidizer present, you run the risk of picking up gold.



Yes, I have read & heard that stannous testing should be done prior to disposing of acid waste. I'm certain I'll learn how to do that as well as time goes by. Still learning... but trying to learn in an orderly fashion while making some notes to later steps rather than bits n pieces of everything at once here n there constantly.


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## punkymunk (Jun 24, 2017)

snoman701 said:


> And honestly, don't try to process every bit of gold...learn the easy stuff, then get rid of the hard stuff.
> 
> I've got boxes of boards, and no time to process anything right now....but I basically set a price point where I'll chase, anything that falls below that, it's not worth it.



I'm not necessarily going for every insy spec I can see but I am going for what I can find that isn't too horridly difficult to get to. This is still just a hobby for me therefore low yield is still yield to me. I'm not looking at price-points or profitability just yet. The knowledge is more valuable to me at this point.


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## punkymunk (Jun 24, 2017)

eastky2 said:


> The first question is how old are your boards? Do you mean gold traces on the board or gold flashing as in a gold shielding or gold flash as in being there to help protect the copper traces.
> 
> Gold traces are found on old HP tektronics boards. Gold shielding is found on high frequency components and boards. Gold flash like on sticks of memory and cell phone boards.
> 
> What do you have?



I honestly can't say the age of the boards I have collected thus far. Some were from older electronics and some from newer. Basically... I scratch the solder masks of any board I get that I think may have gold underneath and if I see a yellowish shiny vs the more common pinkish copper... I want to try and recover unless the board is very small and super dense with populated components. But some boards have visible plating or flashing, with copper under the mask, but can't easily be cut out or has components soldered onto the gold so I'd like to depopulate and de-solder.


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## FrugalRefiner (Jun 24, 2017)

punkymunk said:


> I will have to admit that trying to navigate this forum with my own questions before posting is a bit tedious with so many search results not pertaining to, or giving enough specific info, to get my answers and wind up with tons of info (and arguing & bickering & insults & excessive repeating of this n that that doesn't appear relevant to one's actual posting.), but I do try and have learned a little bit that way.


Punkymunk, we all understand and feel your pain. I provided some advice in my Tips thread, but it only scratches the surface of finding what's here. We can all do with less arguing, bickering, and insults.

Dave


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## Topher_osAUrus (Jun 24, 2017)

punkymunk said:


> Thank you your time and info. I'll add your insights to my notes that I've been trying to take. I have read here and there about copper (II) chloride and copper (III) chloride in which I'm still trying to figure that all out and so forth. I've even begun reading Hoke and can already tell that I'll probably need to re-read it several times since, so far, it appears to be aimed at jewelers and dental work. As said before... the various chemical processes for me are still down the road. Although from what I've read thus far about AP and "poor man's AR... seems to me that PMAR would be better for smaller stuff like printer ink ribbons, mylar ribbon cable ends with gold plating and so on but that maybe AquaRegia would be best for the bigger stuff. I honestly don't know yet though. Still reading and trying to learn.
> Lazersteve has a great copper chloride leach document on his website, that explains the colors of solution and what is needed to successfully rejuvenate it. Poorman AR is essentially just an AR workaround for people that nitric is hard to comeby. For foils, and printer cartriges, and powders, HCl and bleach is commonly used. (Which is different from poor man ar)
> Hoke is indeed geared toward jewelry scrap, but thats not why it is preached as bible truth. Everyone praises her book, because she explains complex chemistry in simple terms. Any and every lay person can get the basic fundamentals under their belt, simply by her words. Not just chem majors, but regular Joe's like myself. ..and not to nit pick, but, I dont think there is any Cu(III) chlorides, just (I) and (II), not for certain though, as I know there is Copper (III) oxide. But, Im no chemist.. So I cannot say for certain. But I do know that the AP leach is based upon the copper (I), and (II) valences.
> I guess I should've added that my main reason for this posting was for the first couple of points at the present time. I have accumulated quite a bit of boards that I want to de-populate and clean off any residual solder so I can add to my "Ready for AP" pile of stock for when I'm ready to attempt that process later on. Including fingerless RAM sticks. But I just thought adding the rest of those steps would be good to know if I understand that much already or not for later as the whole recovery (not refining) process.
> ...


Thats good, everyone has to start somewhere,
It may not be a week, or a month, or even a year, but, your first shiny button will eventually come, and it will be a testament to your determination and fortitude. It is a very hard learning curve to get over, but with the forum and Hoke, anyone in this world can become a well versed refiner. It just takes a lot of reading...a LOT.. But, if you like to read, well, then it's not so bad at all!


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## gcdrummer02 (Jun 26, 2017)

Fun fact: Do not use an aluminum pan for your sand bath. I didn't know the stove could melt aluminum until that day.


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