# I processed some Pentium 4 CPUs



## ohminator

I processed 115 Pentium 4 Socket 478 CPUs by:
- removing heatspreaders
- dissolving the base metals with AP
- dissolving the gold containing sludge in HCl/Cl
- dropping gold with SMB

I got 0,7 g of gold powder and equals a gold content of 0.006g/CPU. Since these chips are considered low yield, I'm not sure if this is good or bad ?
Problem: I'm nearly sure that there is no more gold in solution though the stannous test is still positive !
It is difficult to identify the colour because of a green solution, which originates from copper or nickel impurities I think. 
Any hints?


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## Alentia

Congratulations! That is tough job to work on those.

The results most likely correct. I would expect less than that.

However on the reason of processing them, other than educational:

1. You derived $35 worth of gold
2. You have spent at least 2 hours removing heatsink
3. You have spent at least $5-10 worth of chemicals
4. You have spent at least 5-8 hours attending the process
5. Did you pay for them anything?


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## etack

Alentia said:


> However on the reason of processing them, other than educational:



I love this statement. I tell clients this all the time. Some things are more profitable to sell like fiber CPUs and pinless ceramics CPU (sun sparc and HP)

Eric


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## butcher

one thing I do when I get a dark stannous test and cannot tell what color it is , I will hold the Q tip over the fumes evolving from a solution of aqua regia I am de-Noxing, or over a solution when vaporizing of chlorine gas fumes from a solution of HCl/NaClO, the vapors lighten the dark color of the stannous test, sometimes changing a dark black looking color to violet if positive.

too much SMB can give a false brown color to the test.

Every little bit of gold you recover adds up, and that is gold in your pocket, That is 35 dollars worth of gold that was not thrown in the trash, some times it probably is more work than it is worth, but it is gold that you have now, to me it is like seeing a penny and walking across the street to get it, that penny may not be worth the trip, but it is sure is nice when all those penny's add up to dollars, and sometimes it is worth it to recover that penny saving it from being lost, keep up the work getting those little bits of gold, and watch your nugget get bigger.


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## glorycloud

The P4's seem to sell at $8.00 a pound and you pay the shipping
or you could try the ebay way and make the buyer pay shipping
and you pay the ebay/paypal fees.

You have learned a lot I am sure by working through this process
(hopefully outdoors or under a fume hood) and that has value but
perhaps selling them may make more sense than giving them an acid bath?

Anyway, good job and let us know what you work on next. 8)


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## Alentia

butcher said:


> Every little bit of gold you recover adds up, and that is gold in your pocket, That is 35 dollars worth of gold that was not thrown in the trash, some times it probably is more work than it is worth, but it is gold that you have now, to me it is like seeing a penny and walking across the street to get it, that penny may not be worth the trip, but it is sure is nice when all those penny's add up to dollars, and sometimes it is worth it to recover that penny saving it from being lost, keep up the work getting those little bits of gold, and watch your nugget get bigger.



Butcher, I totally agree with you...but we no longer have pennies in Canada on the streets, nor in the banks or stores for that matter.


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## butcher

:lol: Well thank goodness I walked across the street and picked up them penny's over my years, I have a few maple leafs from Canada, heck the copper in them is worth more than a penny nowadays, so maybe I have got my moneys worth.

The gold he got out of the scrap may have been a lot of trouble, it may have cost him some to get, but he learned a lot doing it, that is worth a lot, plus he has gold in his hands, to me it sounds like he done pretty darn good after all, I would bet just the accomplishment, and that gold put a smile on his face after he pulled it out of the melting dish, and held it in his hand, I would bet that felt much better, than the feeling would have gotten from selling a hand full of electronic scrap for a couple of penny's, so all in all I think he done a great job walking across the street to get those gold buttons.
Like the penny's that gold too will be worth more later.

Heck If all I was interested in was profit, I would have quit this hobby years ago.


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## ohminator

The processors came out of a big lot I bought on ebay with the following content:
- 120 CPUs (2,2 kg) Intel (Socket 478)
- 88 CPUs (0,9 kg) AMD (Socket 462)
- 44 CPUs (0,5 kg) Intel (Socket 370)
I paid ~90€ for them. 
Both the latter I can sell at the local scrap dealer for 75€.

In these lots there are always chips you can sell separately. Since I'm also collector I know something about the demand for particular chips. I also kept some on my own.
And yes, removing the heatsinks is somewhat time-consuming. I've done this while whatching a boring movie, so time was not really wasted. Wasted time can not be wasted once more


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## AUH-R

Hi Ohminator,

I, like you, am new to the hobby and these are the processors I'm practicing on. I have de-pinned using a heat gun 103x P4 mobile copper tops, 1x brown fibre, 82 P4s - Turions mix and 26x Celerons green fibre. I now have 221grams of pins and 25grams of monolithic capacitors (not sure if they are worth collecting). See pictures below. I expect different yields to you as the plating used for the mobile chips was 3 times thicker (0.76 micron Au) than the standard P4 chips (0.2 micrometers Au over 2.0 micrometer Ni). My estimate is 0.015 for the brown fibre and P4 mobiles and 0.005 for the Celerons. I will follow up and confirm in the next couple of weeks when I do my first acid procedure. I'm taking a different route to you I will boil my pins in HCL to recover the gold foils. 

My question after all that waffle sorry! How did you remove the copper tops I tried boiling 1 for 5 mins but it would not budge. 




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## g_axelsson

Don't know how other are removing their heatsinks, but I'm using a thin bladed knife and just cuts the glue around the edge and then the top is loose.
There are two types though, one with a cooling paste between the die and heat spreader and one with the heat spreader soldered to the die. The soldered one takes some force as you have to break the die to get it off. The solder is probably indium based and very soft.

Then I used HCl to remove the pins by dissolving the solder, when all the pins were off I then continued with HCl until all base metals were dissolved. The foils were added to other recovered gold so I have no yield figures.

Göran


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## ohminator

I doubt, that the capacitors are worth keeping. I tested a small batch of crushed ones for palladium, the stannous test was negative.

As mentioned by g_axelsson, the heatsinks are best removed using a thin blade. Some of them may be soldered and can be removed by heating up to ~160°C .
You are able to recover some indium and you get access to the gold-plating on the underside of the plate.


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## AUH-R

Thanks for the tip guys that worked a treat and was very fast each processor took 15 seconds at most using a stanley knife. I had some with gold coloured backs, is that gold plate?




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I know which ones have the gold back by type and tear and I can pm you that info. if it helps. I don't want to type it here so google can pick it up and create competition for myself when trying to get hold of these for almost free 

Regards,


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## ericrm

what are your leaching method used on those cpu?


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## AUH-R

Hi Ericrm, 

I am not sure if I will process the tops to separate the Au, Ni and Cu, I need to learn the most economic way of doing it.
The pins I'm going to boil in HCL to remove the lead and tin. 

Regards,


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## ericrm

AUH-R said:


> I know which ones have the gold back by type and tear and I can pm you that info. if it helps. I don't want to type it here so google can pick it up and create competition for myself when trying to get hold of these for almost free
> 
> Regards,


i will accept your offer, can you send me a pm with your serial number i will send you mine


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