Need help with CPU on boards.

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M

Makcc

Active member
Joined
Jun 11, 2020
Messages
40
Hello everyone.
Thank you for all the information that has been so generously and selflessly shared.
I am planning to process some CPUs and even though I am new to the forum, I am not new to gold recovery.
I have a quantity of CPUs that are soldered on circuit boards and the boards have been cut quite close to the CPU. This makes removal with a heat gun impossible.
Please suggest a method on how to deal with these CPUs ;that is how to separate them from the boards and solder or any other advice on how to proceed to recovery.
I am attaching pictures of samples of the said CPUs. Please disregard the background.
Thank you.
 
Yeah, that's not fun to do but it can be done. You can heat the board side with
a heat gun and the solder that holds the pins from the CPU on the board will
melt allowing you to pry the board away from the CPU. Just watch the solder holes
and you will see when they become "shiny" meaning the solder is probably molten.

I have done it dozens of times so I know that it can be done with a good heat gun. 8)
 
I have some but its quite difficult. The bent legs presents a problem after the solder melts.
Perhaps Incineration in a controlled environment if the quantity is significant.
 
Thanks.
Yes, the bent legs are troublesome but I will keep trying.
Any chance soaking in HCl might be effective?
Denim, I have about 40 of those boards and several others that I plan to depopulate.
see attached.
 
Concerning the "three" CPUs at the bottom of the first pic of the first post (the one where the CPUs were "cut" from the circuit board) - YES - I would just put them in HCL to dissolve the solder away which should allow you to separate the CPUs from the cut off CB (you need to get rid of the tin/solder anyway at some point - so do it now)

Concerning the "complete" CBs - there are several ways to deal with depopulating them - however I don't have time to go into all of that right now

Those are some VERY nice CBs & with 40 of them should be a "nice" payday

As Denim pointed out - they "may be" worth "more" as is - MUCH more if you can find a market for them "as is"

Kurt
 
Thank you.
Is it better to use diluted HCl or just plain muriatic acid?
I checked and there's about 32 lbs of the cut off CPUs. Most of them have non magnetic capacitors on the back of the piece of board.. Or what appears to be cap.
 
Try to get the mlcc (capacitors) off the cpus/boards before you put them in the Hcl and save them as I suspect all or most on those boards will be non magnetic. The Hcl you just use it full strength there is no need to dilute it.
 
Thank you.
I will lift the caps with the heat gun and let the CPUs soak in HCl..
Unrelated... I saw this on ebay.

https://www.ebay.com/itm/293606249778
 
Makcc said:
Thank you.
I will lift the caps with the heat gun
Click to expand...

You don't need to do that - just put them (the "cut off" CPUs/boards) in "full strength" HCl (do NOT heat) the HCl will dissolve the tin - getting rid of the tin - in the beginning of the process is the "first" thing you want to do - including getting rid of the tin that has the ceramic caps soldered to the board

In other words - if you use a heat gun to depopulate the ceramic caps from the board - you will still have to put them in HCl to get rid of the tin before processing them for the Pd/Ag - IF (big if) they are the non magnetic Pd/Ag type caps

Put the CPUs (with the cut off boards) in a 5 gallon bucket - cover them with HCl - let them soak for 20 minutes to a half hour - pick the bucket up by the handle - while holding the handle use a back & forth "twisting" action (be aggressive) so that fresh acid gets to all parts &/or in between the boards/CPUs --- this part of the process will take "about" 3 - 4 hours --- I usually just let it go for a day while doing other things & just go twist the bucket every once in a while - in other words I don't time it I just go do it every so often while doing other things

Next day I go & pour the acid off & then wash the acid out using the same twisting method - takes several washes to get all the acid out

When done with the washes most if not all the ceramic caps will have come off the boards from the twisting action durring the process & you can then separate the CPUs from the boards - may have to pry them apart due to bent pins but they will come apart without much problem

Because you got rid of the tin "first" in this process - you can now go for the gold without worry of a stannic tin problem when you move forward (or at least "much less" of a stannic tin problem)

Concerning depopulating the other boards you have three options - you can do an HCl soak - or use heat with ether a heat gun or by setting them on a hot plate - or knock them off with a chisel

Personally I "prefer" knocking them of with a chisel & a hammer --- the chisel I use is called a masonry de-scaling chisel like the one in the link

I will explain the up side & down side to each of these methods later & why I prefer the hammer/chisel method

Concerning expected yield from those boards - there is no why to tell because some of the boards are "loaded" with the ceramic chips - while some of the boards have fewer of the ceramic chips --- so the real question is how many ceramic chips you end up with "after" depopulating the boards

As a WILD guess --- at least 1 ozt - & "maybe" as high as 2 ozt

Link to pic of chisel I use :arrow: https://www.bing.com/images/search?view=detailV2&ccid=0%2bpEAQrl&id=1D7C5CD0052DCD642E2843F903BD953816F8B3FD&thid=OIP.0-pEAQrlvMG1R0JwL8fOGgHaFx&mediaurl=http%3a%2f%2f1.bp.blogspot.com%2f-JSlCyzLXqEk%2fVGefK1oV7-I%2fAAAAAAAAB88%2fOZn6CSP9TxY%2fs1600%2fJ.%252BTyzack%252B%2526%252BSon%252B4.5%252Binch%252BBolster%252BChisel.JPG&exph=1001&expw=1283&q=concrete+chisel+types&simid=608040860706146790&ck=0D1F170556351D345A9600DC3242EED2&selectedIndex=28

Kurt
 
Outstanding Kurtak.
Thanks for the added details.
Hmm.. 2 ozt... I can get new shoes.
 
really all you meed is to put them in an oven for a few minutes and the chips will come off real nice. Heat gun on a stand with some long hemos will work too.

The boards I had like that the PBC was glues to the/a metal. The heat gun was easier than removing the board.




Eric
 
Update :

35 lbs of mostly SUN CPUs soldered on board placed in bucket of muriatic acid until fully submerged.
One week.. swishing the bucket once daily.
Result:
Blackish goo found on side and bottom of bucket. CPUs still holding strong on the circuit boards.
Muriatic acid is distinctly purple (definitely nano gold).
Tops of CPUs have lost the gold plating.

I would not recommend this method to remove CPUs from circuit boards. So far it's ineffective and gold may be lost.
 
Makcc said:
Update :

35 lbs of mostly SUN CPUs soldered on board placed in bucket of muriatic acid until fully submerged.
One week.. swishing the bucket once daily.
Result:
Blackish goo found on side and bottom of bucket. CPUs still holding strong on the circuit boards.
Muriatic acid is distinctly purple (definitely nano gold).
Tops of CPUs have lost the gold plating.

I would not recommend this method to remove CPUs from circuit boards. So far it's ineffective and gold may be lost.
Click to expand...
LOL its like you made a bunch of Stannous then used it.

GSP compared nano gold to "smoke or gelatin" advocated to dissolve again (H2O2 or bleach would work) then to precipitate.I would try to heat the liquid to get rid of a lot of the water first it will stick to everything, but just wash you utensils in the solution it will clean the gold up.

Eric
 
Make, my suggestion to you is treat as a leaching process. This will maximize your yield and produce a cleaner product.
Heat is used but not a heat gun. In fact a low heat on stove top to simmer the acidic solution and bring to optimal temp for the acid to work.
I'd you are unfamiliar with the leaching process pm me and I'll walk you through it.
 
Putting the whole board in acid is foolish. As is putting a bunch of processors into HCl without pre-treating.

The proper method of treating this waste with hydrometallurgical methods is well defined on this board elsewhere. You break each ceramic processor, do a short soak in warm nitric to free the silicon dies, pins and caps. Decant, saving leach. Leach will have Ag/Pd. Just save it.

I personally prefer to remove large portions of ceramic and process them separately (first). The pins and caps are put in a second beaker.

Now add HCl and warm to 90 deg C. Add nitric in steps until no more reaction occurs. This won't take long. You may still have enough residual nitric from the first wash to get it done.

I then decant off the pregnant leach on to the beaker with lids and pins and small crumbs of alumina which I dissolve last.

I do this for a couple reasons. The longer you boil the ceramic in pregnant leach, the more gold you temporarily lose. The alumina will soak up a significant amount of gold. The second reason is I can do a quick hot wash of the alumina ceramic bodies, then just add the wash to my leach. Usually I end up having to add a little more HCl because dissolving the caps takes so much HCl.
 
To specify, CPU boards and computer scrap contains a low yield per piece being recycled. Something like 3-7 grams per Computer tower.(pending brand name and age of device) $$(some brand contain more (HP) and some less (e-machines)
Personally I don't waste time on that, to much of it needed to be profitable, unless you have a supplier of bulk material.
The process and method I had suggested was how I first learned. It is an effective way to separate and identify the precious metals in their raw form.
Personally , I extract from natural finds in rural locations , tons of fun. 8)
Now it has been a while since doing a recycle process, but I would have to agree with you on the separation of the components, I figure thaT common sense, if you don't separate your components then you could compromise your find, for semi precious metals like silver or copper, and let's be honest if you are looking to turn a profit then you would want the least amount of waste.
Aside from that the leaching process is a very effective method for extracting precious metals from electronic scrap. As well as natural finds.
Thank you for your response, and do view my other posts.
If you are interested in a natural find d excursion onbox me and I could give a couple suggestions.
 
Indigo Suelo said:
To specify, CPU boards and computer scrap contains a low yield per piece being recycled. Something like 3-7 grams per Computer tower.(pending brand name and age of device) $$(some brand contain more (HP) and some less (e-machines)
Personally I don't waste time on that, to much of it needed to be profitable, unless you have a supplier of bulk material.
The process and method I had suggested was how I first learned. It is an effective way to separate and identify the precious metals in their raw form.
Personally , I extract from natural finds in rural locations , tons of fun. 8)
Now it has been a while since doing a recycle process, but I would have to agree with you on the separation of the components, I figure thaT common sense, if you don't separate your components then you could compromise your find, for semi precious metals like silver or copper, and let's be honest if you are looking to turn a profit then you would want the least amount of waste.
Aside from that the leaching process is a very effective method for extracting precious metals from electronic scrap. As well as natural finds.
Thank you for your response, and do view my other posts.
If you are interested in a natural find d excursion onbox me and I could give a couple suggestions.
Click to expand...

3-7 grams of gold per computer tower? In your dreams. Maybe in bigger main frames from 1980 or specialized huge server machines only found in data centers, but ordinary tower machines, never.

Göran
 

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