# Depopulated board in oil



## Williamjf77 (Nov 3, 2019)

Well I did a little experiment today, I tried to depopulate a ram stick in hot baby oil. I can’t be the only one to ever think of that but I haven’t seen it posted anywhere before so I tried it.

I figured all I needed was something that boils higher than the melting point of solder. 

I’m sure there is a better oil, maybe olive or something but it’s reusable and the baby oil smells kinda good when hot. Just thinking outside the box as I’m finally getting ready to process @50 lbs of ram sticks and after the painstaking process of cutting off fingers I was looking for something cheap and effective.

I also tried dissolving bga chip in Ethylene glycol and a catalyst after reading a paper about it, I used sodium hydroxide but the paper was about TBD ? as a catalyst compared to other catalysts.

Anyway that didn’t work for me.

But the oil bath with a little agitation stripped chips but the solder will wick onto anywhere it can so if there are still fingers on the board the solder may flow there.

Just thought I’d post the info, commensurate flaming  :mrgreen:


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## Johnny5 (Nov 3, 2019)

Williamjf77 said:


> I used sodium hydroxide



Careful, that will strip the gold if the concentration is too high.


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## Shark (Nov 3, 2019)

Olive oil will start smoking around 350F. It will scorch around that or lightly higher giving a foul odor and taste. Have you considered a rotisserie type toaster over? I have always been curious if one of those would do that job. I have an oven here I just don't get much escrap these days to try it on.


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## Williamjf77 (Nov 3, 2019)

Actually I saw one of those rotisserie ovens at a local pawn shop, I might pick it up tomorrow.

I was just experimenting, I think canola oil smokes @ 230c, that would be cheap. 

I was envisioning a big turkey fryer pot with 50lbs of ram sticks on a charcoal fire.


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## Williamjf77 (Nov 3, 2019)

I was thinking if I could heat chips in a solvent that boiled high enough to pyrolize and depopulate in one shot that would be a win. If pyrolysis temp is @350c, and the oil boils [email protected] 350c and there would be no oxygen because of the oil.

But I gave up after the smoke got too much.

Just a theory but seems logical right?


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## Williamjf77 (Nov 3, 2019)

And any hydrocarbon off gas would dissolve in the hydrocarbon solvent.

I’m no chemist but I love the science.


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## Shark (Nov 3, 2019)

I saw a video once of a machine depopulating boards. It was nothing more than a big rotating basket with a heating element and controller in the top part. As it rotated and the heat became enough the parts would drop through the mesh of the basket and was caught in a tray under the basket. 

My rotisserie came from a yard sale for $10 and came with a toaster basket made of 1/2 and 1/2 inch mesh. I had thought about using it but I only have around a pound of memory left. I might check tomorrow and see how they fit.


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## g_axelsson (Nov 4, 2019)

Johnny5 said:


> Williamjf77 said:
> 
> 
> > I used sodium hydroxide
> ...


Not to my knowledge.

Göran


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## g_axelsson (Nov 4, 2019)

Williamjf77 said:


> I was thinking if I could heat chips in a solvent that boiled high enough to pyrolize and depopulate in one shot that would be a win. If pyrolysis temp is @350c, and the oil boils [email protected] 350c and there would be no oxygen because of the oil.
> 
> But I gave up after the smoke got too much.
> 
> Just a theory but seems logical right?



Pyrolize, breaking down and driving off any hydrocarbons to leave you with only carbon and inert substances... in a hydrocarbon solvent? Either you boil the solvent off or char it. Either way it's more effort than just pyrolyzing the chips. Only chips would have less thermal mass and less hydrocarbon gases to get rid off. I can't see any problem that an oil bath would solve here.

Göran


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## anachronism (Nov 4, 2019)

Does a 300 degree C hot oil bath seem somewhat dangerous to anyone else? It's fraught with hazards. 

For one, the reaction of many components to that level of temperature is best described as explosive.


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## Williamjf77 (Nov 4, 2019)

Anything that temp is surely dangerous.


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## Yggdrasil (Nov 4, 2019)

There has been shown liquid pyrolyzing systems in here before, but they have been based upon molten salts. Not quite that combustible, and depending on the salts used, they can maybe be tuned to certain specific gravities for flotation and so on. Maybe....

But as I see it, it will create a horrible mess of fibrous glass and components with carbonized trash in there as well. Then it will still need incineration after the initial pyrolysis, if your plan is to refine anything the sorting will be next to impossible.

Or maybe the glass can be used as part of the flux and the whole shabang melted to bars for electolysis or sale?
Anyways, the whole thing seems quite messy to me.

Edited for clarity


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## Johnny5 (Nov 4, 2019)

g_axelsson said:


> Johnny5 said:
> 
> 
> > Williamjf77 said:
> ...



I've stripped masking from several hundred boards (fully gold plated), and witnessed what "appears" to be gold dissolution, from a few dozen. This situation happened to every single board exposed to the concentrated solution, and the "appearance" of dissolution only happened to parts exposed to the solution. Any parts outside of the solution still appeared to have it's original gold playing under the masking. It's entirely possible that I'm wrong, however Jack Burns, Frank, and myself were all talking one night, and they too experienced the same phenomenon. Again, I may be wrong.

Johnny


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## Williamjf77 (Nov 4, 2019)

Mostly I just wanted to depopulate, with something cheap quick and reusable without directly using flames on the board, then I figured I’d leave it in longer to see but the smoke point of oil was just as bad as flames. So for depopulating it worked ok. Not something I’ll probably try again but who knows. Vacuum pump oil would work but that would defeat the cheap part. 

Lead free melts below 200c so I don’t think that temp is crazy to work with, I mean French fries fry hotter than that don’t they


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## Shark (Nov 4, 2019)

Does anyone know what type oil is used in an oil heater? The type that heats the oil in a closed system.
While I am not one to heat oil much, it may take more heat than some other types. 

With a small amount of memory the oil thing might work. If I was going to do a large batch the hot oil would spook me into looking else where. Especially if I would be doing batches that size more than once, I would look into something easily repeatable with a wider safety margin.


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## anachronism (Nov 4, 2019)

Here's the thing. 

It's one thing putting RAM in hot oil. Yes it COULD work I accept that. We put a process up on here where someone does it and before you know what's happening some eejit has put a PC board or similar in the same system and had the capacitors explode. Covering the workplace and probably himself in both red hot oil and shredded Aluminium.

There's another word for that shredded Aluminium. Shrapnel. I don't think anyone needs telling what shrapnel does. This is a really dumb idea lads.


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## Williamjf77 (Nov 4, 2019)

Good point on the electrolytic caps. 
See now there is information out there of why someone should not do that.


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## Williamjf77 (Nov 4, 2019)

On a side note does anybody know why my AP solution smells like dumpster juice? I only used it to strip pins and just put the fingers in it yesterday. Is there a certain metal that does that?


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## g_axelsson (Nov 4, 2019)

Johnny5 said:


> g_axelsson said:
> 
> 
> > Johnny5 said:
> ...


Led and tin will dissolve in lye, that can plate out on some of the conductors thanks to different metals gives different potentials like a battery or cementing back. That's why you see one finger turning white next to a golden one. The gold is still there, just covered by tin.

Göran


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## rickzeien (Nov 4, 2019)

Why not indirect heated sand bath. A large electric fry pan should work. 

May even be possible to recover the solder once the sand is saturated. 

I would try very course sand then sift out the contaminants once saturated. The solder and the small SMD devices should be there. 

Once the sand is super-saturated it could be smelted to clean up the balance. 

Have not tried it but I would think someone on the forum would have some experience. 

Also I would advise proper ventilation, gloves and a respirator when doing this. A shield face shield would be a good idea as well. 

Sent from my SM-G950U using Tapatalk


Edited for spelling


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## Shark (Nov 4, 2019)

I went and cleaned up my rotisserie oven and heated it up. The downside is it has no way to control the heat or turning speed. It will reach 500F inside pretty quick the stabilizes around that number and the thing has very little insulation, if any, in it. The basket would need some tweaking to stop the boards from sliding out the ends. Any idea what an optimal temperature would be if it was used for memory only?


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## Williamjf77 (Nov 4, 2019)

I think 450f should melt the solder, most lead free melts below that and leaded even lower


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## Shark (Nov 4, 2019)

rickzeien said:


> Why not indirect heated sand bath. A large electric fry pan should work.
> 
> May even be possible to recover the solder once the sand is saturated.
> 
> ...



Several years ago I used that method to strip small boards. Like anything we do, it takes some work to get it just right, but does work. Then as Jon mentioned, and I had forgot, those capacitors are best removed first if doing larger boards. I have dodged one or two of those capacitors and is one of the reasons I went back to doing manually. There is a lot about board stripping I just do not miss..


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## Williamjf77 (Nov 4, 2019)

I have read about sand bath but am trying to avoid manually handling stick by stick. I’m sure I’d be half done by now just doing a proven process instead of trying new thing. I like the trammel style depopulated like the rotisserie. I do have a lathe maybe I can rig up a temp solution.


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## butcher (Nov 4, 2019)

Oil? I would not even consider as an option to depopulate circuit boards.

I have used several methods to remove components from circuit boards.
Rotary tools to cut or an air chisel to shear.

Hot air gun will melt solder, and a bang of the edge of the board against the table to knock the components free.
Sand bath to desolder and knock on the table.
Using a desoldering and suction station.

I would like to try something that would be similar to a clothes dryer where you could control the hot airflow through the drum to melt solder, yet not harm the electronic components...


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## rickzeien (Nov 4, 2019)

I would like to try something that would be similar to a clothes dryer where you could control the hot airflow through the drum to melt solder, yet not harm the electronic components...[/quote]








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## rickzeien (Nov 4, 2019)

Tried to edit quote but my comment didn't come over. 

I really like this idea.

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## rickbb (Nov 4, 2019)

Depopulating boards on anything other than large industrial scale with expensive equipment is a pain. 

I've not found anything faster than just holding a single board at a time with pliers on a hot plate and scraping off the components with a wide blade putty knife.

If you get a rhythm going you can scrap off the bits without any smoke at all. But you will still need ventilation, stuff stinks and is not healthy to breathe. 

A hot oven with a rotating wire basket that would hold poundage of all kinds of boards sounds like a winner.


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## Shark (Nov 4, 2019)

At 5 minutes this was the results.







A very short video at the 10 minute mark. There was no smoke, and very little odor, and actually smelled like solder more than anything. I don't like the factory basket, and actually think a more rounded one or even a square shape would work better. The banging as the sticks dropped did knock off many components.

[youtube]https://youtu.be/9SZUX9IVvQ0[/youtube]


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## rickzeien (Nov 4, 2019)

Looks great Shark. Did it completely depopulate and remove the the solder?

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## Shark (Nov 4, 2019)

No, it left some on the boards and some on the chips. It looks like most of it remained with the boards, but only in a few spots. Both are cleaner than using a sand bath or a butane torch. The sliding action and the boards bumping together seem to remove some solder as there is solder balls in the bottom pan. I only ran these for 15 minutes and it took that long for glass type chips to start coming loose.The old chips with legs came loose first (at about 5 minutes), the newer square epoxy type and the mlcc's came off next at about 9 minutes. The oven I am using is a Sunbeam model RE12-12. The only heating element is high on the back side and I think that is plus. It keeps some heat away from the components after they fall off. If I can I want to try a longer run tomorrow, it is getting to dark now. I have an idea on how to get the chips to leave the oven I want to look at closer tomorrow as well.


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## snoman701 (Nov 4, 2019)

anachronism said:


> Does a 300 degree C hot oil bath seem somewhat dangerous to anyone else? It's fraught with hazards.
> 
> For one, the reaction of many components to that level of temperature is best described as explosive.


You mean since the auto ignition temp of mineral oil is right at the temp he heated it too? Yes. Just a tad dangerous. 




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## Shark (Nov 5, 2019)

This this took 3 hours to run in my small oven. It don't look like much but the chips are in a 1.5l dish. It did leave enough time in between changing out the boards to decant my stock pot into the iron bucket. Refill the stock pot and set up a new, quieter way to circulate the solution. I have no memory left to play with, and it will be a while before I expect to have very much again, but I do have other ideas to try with this thing yet.


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## Williamjf77 (Nov 5, 2019)

Shark said:


> This this took 3 hours to run in my small oven. It don't look like much but the chips are in a 1.5l dish. It did leave enough time in between changing out the boards to decant my stock pot into the iron bucket. Refill the stock pot and set up a new, quieter way to circulate the solution. I have no memory left to play with, and it will be a while before I expect to have very much again, but I do have other ideas to try with this thing yet.
> 
> 1105191407.jpg



How about the new way to circulate the stock pot? Care to elaborate.


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## Shark (Nov 5, 2019)

Give me a few days to see how it is working. As of now, it seems to be good.


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## Williamjf77 (Nov 5, 2019)

Nice, I like the rotisserie, especially the rectangular basket, the shape gives an impact to knock the chips off as it turns


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## Shark (Nov 5, 2019)

For me the oven is like a proof of concept. It should be easily scalable to suit ones needs. I like that idea of using a cloths dryer, if one has the material to make it worth while. Done right, the chips will drop and exit the area that is being heated. What I would like now is to figure out how to get the cleaned boards to leave the drum and deposit in another area separate from the chips.


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## butcher (Nov 5, 2019)

Not actually a clothes dryer.

https://www.google.com/search?sxsrf=ACYBGNSZA2joWFgAB8jcTRqoEFvYw_EDBg%3A1573011303358&source=hp&ei=Zz_CXbKHE5bD0PEPm8SDiAI&q=rotary+drum+roaster&oq=rotary+drum+roaster&gs_l=psy-ab.3..0i22i30l3.10734.23108..26103...0.0..0.175.2153.5j14....2..0....1..gws-wiz.......0j35i39j0i131.vR-PMy_M1mw&ved=0ahUKEwjy1tjf09TlAhWWITQIHRviACEQ4dUDCAg&uact=5



https://www.google.com/search?q=rotary+drum++ore+roasting&sxsrf=ACYBGNQCqNvwOo33DsMHXQPlDKLl4CwQBw:1573011423771&source=lnms&tbm=isch&sa=X&ved=0ahUKEwiIt5CZ1NTlAhW6FTQIHTsYDlkQ_AUIEigB&biw=1280&bih=881


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## kernels (Nov 6, 2019)

DIY version of the ram depopulator -> https://www.youtube.com/watch?v=wzWB66dLBok


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## anachronism (Nov 6, 2019)

What you are really looking for is a reflow oven. You can pick them up second hand extremely cheap. Then all the work is done for you. 

The search term is "reflow oven."


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## kurtak (Nov 6, 2019)

Most of this thread has been about depopulating RAM

IMO - there is only "one" way to do this --- put the RAM in a 5 gallon bucket (1/3 - 1/2 full) cover the RAM with HCl - give it about one hour for the HCl to react with the tin - pick the bucket up by the handle & twist/rotate the bucket back & forth - this gets fresh acid between RAM sticks that are touching each other - repeat bucket twisting/rotation about every 20 minute - 1/2 hour until it becomes evident chips & SMDs have come loose from board --- decant HCl & use same bucket twist rotate to do 3 or 4 water washes - separate boards from components (can be done with screening - or by hand)

Why HCl instead of some kind of heating :?: 

Because with heat you have not eliminated the solder (tin) --- so - before you can move on to the recovery of your gold you still have to (at some point) do a HCl leach to remove the tin - other wise the tin is going to follow through the rest of your recovery processes 

Therefore - IMO - get rid of the tin to start with &/or in THE FIRST PLACE 

Just did about 40 pounds of RAM this way (& have been doing it this way for years)

Trust me --- I have tried ALL other methods will NEVER do it any other way then the way I just discribed 

And it works on both the older types of RAM (older type chips) & on the newer BGA type RAM (chips)

Its the fastest - AND - it gets rid of the tin right out the gate

And - don't forget - the FINE black powder from dissolving the tin away contains "gold" (and antimony) as well - so let that fine black powder from you HCl decant & the water washes settle out for processing as well

Kurt


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## Williamjf77 (Nov 6, 2019)

The hcl is what I ended up doing. I don’t have to build anything and it’s practical.

Now I just have to figure out the pyrolysis and incineration.
I had bad experience the first time, I used my blacksmith forge, it’s rectangle with opening on both ends and a Venturi burner.

It started out good with my vessel sealed with some holes in the top, I put water in it threw it in the forge and the gases started burning but then it just blasted nasty smoke. I don’t know if it’s because the setup I have is tuned to burn neutral or slightly rich?

Or maybe not enough time for the gases to mix, either way next I think I’ll try rerouting the gas out of the crucible into the back of the forge.

Anyway it’s great how a dumb idea can generate good discussion


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## Shark (Nov 6, 2019)

I like the conversation side as well. Sometimes other ideas arise that have nothing to do with the original question. I have never done 40lb of memory. Most of mine has been in the 4 to 5 pound range, but I like to think "what if", trying to be somewhat prepared, just in case. The idea I had for the oven was based on a much larger but similar machine from a video from a Chinese manufacturer, where they were doing whole boards. In the back ground you could see the parts dropping out as well as hear the capacitors popping. I enjoy studying different types of machines, and have since I was a kid. 

I like the idea of the black dust having gold trapped in it. Every little bit counts. I have been doing my hydrochloric washes after recovering the chips. The thought was to use less chemicals. I may be loosing a tiny bit of gold right there. Next time I will try it Kurt's way and see how it works out as I know the acid will have plenty of use left afterwards.


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## Williamjf77 (Nov 6, 2019)

And then with the hcl method you have gallons of stannous test solution


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## Shark (Nov 6, 2019)

Here is a new batch of waste going into the stock pot. I hate the sound of those air pumps bubbling away so I used these, they are much quieter, but occasionally one gets finicky about the depth. I added the same solution from a larger bucket yesterday, today it was very dark and had a fair bit of material cemented out. 

It is hard to see, but I drilled a small hole in the bottom so the solution would run down the copper bars and out the bottom. It increase's circulation in the bucket as well as retains the solution in the confined area a bit longer. Most of all, it is very hard to hear from 8 or 10 feet away, has less splatter due to the cover and I can actually hear myself when I am talking to me. Even so I keep this smaller bucket inside a five gallon bucket to help reduce splatter as well. The drop on top is from a spray bottle is water.


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## kurtak (Nov 7, 2019)

Williamjf77

I am having a problem with my computer right now so can't copy/paste links (my touch screen is working but my touch pad/mouse is not working)

concerning pyrolysis/incineration --- go to "Build your own Equipment" - scroll down about 2/3 & look for thread title "Pyrolysis reactor" by kjavanb123 - it's a very good discussion on methods for pyrolysis/incineration as well as info on milling smelting etc.

Kurt


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## Williamjf77 (Nov 7, 2019)

Those are great threads. This is what I have


That’s the back and the front is wide open.
I’m thinking to use the forge as the after burner and making a chamber that attaches to the forge. I know the forge can melt steel so it’s hot enough for an after burner while the incinerator doesn’t need to be that hot. I’m just not sure if an after burner will work without a blower


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## g_axelsson (Nov 7, 2019)

Two important factors for an afterburner, oxygen excess and dwell time.

I think 4metals have discussed that a couple of years ago.

Göran


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## Williamjf77 (Nov 8, 2019)

Actually I just did a test and it worked pretty good as is, as long as I didn’t put too many in at once. I think the way the flame bounces off the floor and then pushes everything to the top kind of lets the gas dwell. Now I need a way to load and add air as needed. 

The flow of air from small hole in back to open in front with the force of the flame and air from the burner going perpendicular seems to mix the gases and burn pretty good. Takes about 2 minutes per load of about 50 grams of north bridge tops.

I was really hoping I could use this because I don’t blacksmith much anymore, too much work but satisfying on a bad day to smash hot metal.


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