# Silicon Wafers (gold, silver)



## hestati86 (Jun 2, 2017)

Do you know a way to recycle these? I have access to about 10 tons, 10g of silver per kg of wafers. I guess I could strip the gold, but what to do with silicon? I'd like to do it properly, not just strip and dump.

Maybe you know someone who would buy these? Coming from South East Asia.


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## MRN (Jun 16, 2017)

Are you willing to sell these Scraps, as is or / or after you recover the Au from the scraps.

Image if the Silicon Wafer is requested


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## kernels (Jun 17, 2017)

Silicon is pretty inert, I wouldn't think there is any problem with strip-and-dump as long as they are cleaned of chemicals before being dumped ?


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## anachronism (Jun 17, 2017)

kernels said:


> Silicon is pretty inert, I wouldn't think there is any problem with strip-and-dump as long as they are cleaned of chemicals before being dumped ?



Yep you've pretty much nailed it there. 

Jon


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## Manjelle (Jan 17, 2018)

Not familiar with silicon wafers. Where are these located and what do they look like


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## goldsilverpro (Jan 17, 2018)

Manjelle said:


> Not familiar with silicon wafers. Where are these located and what do they look like



https://en.wikipedia.org/wiki/Wafer_(electronics)

The silicon chip (die) circuit is duplicated many time of a single wafer. They are then cut into individual chips (dice). If the chips are to be mounted on gold plated bases inside the IC packages, to aid in brazing of the chip, the back of the entire wafer will be coated with gold. In an IC manufacturing facility, these silicon wafers sometimes end up as rejects. In an L.A. refinery where I used to work, we would often get gold coated ones by the drum loads from Silicon Valley companies.


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## Manjelle (Jan 17, 2018)

goldsilverpro said:


> Manjelle said:
> 
> 
> > Not familiar with silicon wafers. Where are these located and what do they look like
> ...


Ok don't see much along those lines. But the more you know and the harder you look, the more you see


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## Rougemillenial (Feb 22, 2018)

I’ve also heard there’s some PGMs as well in those dies.silicon as an element is quite interesting especially once you react it with chlorine to make silicon tetrachloride and convert back into even purer silicon than what you started with. I usually however for many reasons, just like to flux it out.


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## pokermandown (Mar 19, 2018)

Do you know the Au content per Kg? I have a bucket of them but I am working on known items before I go stumbling into a new set of challenges. Might be worth it if I could get 1% yield like Ag.


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## anachronism (Mar 19, 2018)

pokermandown said:


> Do you know the Au content per Kg? I have a bucket of them but I am working on known items before I go stumbling into a new set of challenges. Might be worth it if I could get 1% yield like Ag.



Have you any idea how many processors you would need in order to get a Kg of silicon wafers?


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## goldsilverpro (Mar 20, 2018)

From the internet, the thickest gold I found on silicon wafers was 1000 angstroms. That's about 0.1 microns or, at a $1310 spot, 5 cents per square inch. I did see references to 100 angstroms also. The gold is applied using thin film techniques, like evaporation.


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## g_axelsson (Mar 20, 2018)

pokermandown said:


> Do you know the Au content per Kg? I have a bucket of them but I am working on known items before I go stumbling into a new set of challenges. Might be worth it if I could get 1% yield like Ag.


Where did you get them from? Production rejects? From processing CPU:s? ...

Göran


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## pokermandown (Mar 25, 2018)

They are production rejects from a couple of local chip manufacturers. I got the majority of them in a bin with other items and I just set them aside and as I find more, I just put them together. There appear to be at least 12 different kinds of images, but I have not dug around much because there are a lot of sharp edges. I have no documentation but they are mostly on 125mm and 150mm wafers so I don't think they are recently made.


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## cosmetal (Mar 25, 2018)

goldsilverpro said:


> From the internet, the thickest gold I found on silicon wafers was 1000 angstroms. That's about 0.1 microns or, at a $1310 spot, 5 cents per square inch. I did see references to 100 angstroms also. The gold is applied using thin film techniques, like evaporation.



Chris,

Can you, please, provide more information on the "thin film techniques, like evaporation" you refer to? I assume that this is not the ENIG process, correct? Nor AuSn 80/20 solder or gold braze?

Thanks,
James


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## gcdrummer02 (Mar 25, 2018)

vapor deposition

I remember back in the day, when I did a lot with solar panels, solar companies would pay for scrap silicon and broken cells. It was not a significant amount, but if you already have them stacked, its a place to send it.


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