Gold inside chips (black, flatpacks - not CPU)

[Geo]

I've always used the nitric bath first. This removes any silver before any other process. After this, any insoluble oxides should be taken care of with the following incineration and HCl bath. I'm not sure which way is better but I havent had any problems with insoluble salts. My problem is the finite dust that makes it through all the filterings. It has to settle until the liquid is clear every time the fine silt is disturbed. I truly am in need of a better filtering system.

 

[g_axelsson]

Incinerating - washing/magnet - HCl - neutralizing - incinerating - HNO3 (Ag, Pd) - AR (Au, PGM)

I was just confused if first HCl and then HNO3 or first HNO3 and then HCl. Does the HNO3 dissolve AgCl or will Ag cement back on the copper, so it will be dissolvable in HNO3? I was just afraid of leaving any silver back in the mud. But now I have started with HCl.

If you are concerned with creating silver chloride and losing it, I would suggest a modification.

incinerating - washing/magnet - HCL - wash with NaOH solution - wash with water - incinerating - HNO₃ (Ag, Pd) - AR (Au, PGM)

- I removed the neutralizing step between HCl and incineration, the incineration will evaporate off any acid residues.
- Added a NaOH wash step followed by water wash.

The NaOH will convert any AgCl into Ag₂O, then the incineration will decompose the Ag₂O into metallic silver and oxygen above 280 degrees C. No AgCl that can go up into smoke at the incineration step and all silver will be soluble in nitric after incineration.

Correct me if I'm wrong.

Göran

 

[solar_plasma]

Göran

wash with NaOH solution

Thanks! That's an ingenious advice! One problem solved.

You will probably have seen it, I have just done the opposite of what I was told and what I wanted, I ask HCl first or HNO₃ first...everyone says: HNO₃ first!....I say: Aaah, I see! First HCl.... :roll: :lol:
Well, well, ...but it sounds as if both will work. Next time I do as advised.

 

[resabed01]

I am new to this and still learning but I'm of the opinion of HCL first before HNO₃ just for the simple reason of getting rid of base metals first, especially tin which will cause you heartburn later. I know HCl can be painfully slow and HNO₃ works much faster which is why, I think, some people prefer to use it first.

 

[Geo]

Processing chips is a process in and of itself different from processing other scrap. By removing the magnetic material first, you are removing the solder. Any remaining tin would be negligible. You can remove all the base metal at once except any aluminum. The aluminum is the reason for the HCl bath.

 

[alvaschein]

Hi all

I took my time for a little "research" on gold content of black chips. First I sorted a pile of black chips into more or less similar type classes. So at the end I had 16 different classes. From each class I took a sample of about 50 g, depending on how much I effectively had, treated them to get to the gold bond wires and calculated the ratio of gold content.
I have to say that the washing process without losing too much bond wires was rather difficult and there still remained some dirt of cracked silicon chips. So, I guess the resulting yield might be the maximum possible yield with this kind of treatment.

Well, take a look at the results (see attached doc) and calculate for yourself which type of chips is worth hunting for. My personal favorites are the FCBGAs. They had surprisingly long bond wires.

Have fun

Roy

 

[Rodthrower18]

Has anyone used a blue bowl or other concentrator yet? Panning takes a certain amount of skill. How fine is the gold supposed to be? I ran a test batch of 200g of the black epoxy part of s/n bridge chips and the best I got was a few heavy ultra fine almost flour like "lines" of color. I've kept all of my "wash" water and keep repanning and every time I get more color back out from what's supposed to be my wash water lol. So any ideas or confirmation on the blue bowl would be great.

 

[Stowmaster]

I read this top. I've been collecting these chips only. Sorry for the poor photo quality. Part of the chips I have already burned.

 

[patnor1011]

This is what is the most valuable item on motherboard. There is more gold on this IC than on all of the pins combined.

 

[g_axelsson]

Stowmaster, that is plastic top BGAs, no ceramics.

Don't mix the tops with the small circuit boards. The gold bond wires are all inside the plastic part with the silicon die. It is easy to rip it off the board before incineration. After the incineration you would have some copper and the gold bond wires mixed in with the ash and silicon dies. Some of your BGA capsules had a copper plate as heat spreader, just pick them out while washing if you didn't remove them before incineration.
I would wash the ash away, remove the copper traces with a little bit of nitric and then go after the gold with AR or HCl/Cl.

The board part contains only trace amounts of gold... I've been told, haven't tested that myself yet but I don't see anything wrong with that statement. What is clear is that the board part contains all the tin and you don't want to mess with that, it would probably cost more in chemicals than you would get in extracted gold.

Göran

 

[Imran]

Pat thanks for posting so much invaluable informations.

Thought I should post. There are gold bonding wires in transistors too. It is not much but every little bit counts 8) After all there are a lot of transistors on motherboards. The ones on boards from power supplies don't have any gold just ones on the motherboards.

 

[patnor1011]

Yes, you are correct. I am collecting them and do have tad less than one kilogram. I will play with them to find out some numbers.

 

[IntelGold]

Hi, Would someone kindly let me know what sort of transistors you are refering to? Maybe a Picture.
Thanks.

 

[patnor1011]

Give me minute I will take quick picture of what I have laying on table, not every one of them do have gold bonding wires but even if only half do, that will add up.

 

[IntelGold]

I can't seem to find any gold or even aluminum bonding wires. I have taken apart 20 or so and nothing. Are the wires in the top plastic part or the bottom Metal bit?

Thanks for any help.

 

[Geo]

Bonding wires are about 1/10 the diameter of a human hair. You need a good jeweler's loupe to see them clearly. Normally, they are in the plastic body connecting from the legs to the silicon chip.

 

[Imran]

intel...of course you can't see any bonding wires like that.
Follow this instructions.

Use blowtorch to incinerate those chips. Half a minute under direct flame would do the job. After that they should be white outside and easy to pulverize. Do that so that the powder is as fine as possible. You also need to remove bottom copper part. Now you should have really fine black dust. Put it on a sheet of paper and if you have really good eyesight you should be able to see gold wires. If not use magnifying glass.

Second step is to concentrate powder. In order to do that you should pan it. Be very careful. After that you should be left with a gold concentrate. Then use HNO₃ to remove any possible base metals. In the next step use HNO₃/HCl or HCl/NaClO to dissolve gold. Precipitate it with Alkali metabisulfite or FeSO₄.

Voila you have pure gold powder ready to be melted :lol:

 

[Smack]

Give me minute I will take quick picture of what I have laying on table, not every one of them do have gold bonding wires but even if only half do, that will add up.

I bet the one on the left in the picture with the number 30127 has gold bonding wires.

 

[patnor1011]

I use heat gun to remove them. It is quick. Some things can be done while watching TV some can't but gold is gold so we must count a bit of sweat and blood as price of getting it. :lol:

Yes, Imran that is exactly how I do them. If you do handful at a time you will see bonding wires easier as they will accumulate in one spot.

 

[alvaschein]

I read this top. I've been collecting these chips only. Sorry for the poor photo quality. Part of the chips I have already burned.

I took a closer look to this type of chip. I removed the top body from its base and found a gold plated circuit on the base. So I decided to treat those bases with AP, and yes, I got the gold foil off. The next step will be to treat the top body the same way to remove the remaining gold which kept there while removing them from their bases.
Well, my advice: Do not just burn them. Take off the top body and treat both, body and base, with AP. After this you can burn the top body for recovering the bond wires.

Roy