Gold inside chips (black, flatpacks - not CPU)

[patnor1011]

Picture of small pin from inside of IC with gold bonding wire still attached, not very clear I need better camera and another one of pins being removed with magnets - some of them with gold bonding wire still attached.

 

[skippy]

I have no data on this type and I do not consider them as good source of precious metals but I collect them and will do few experiments.

Pat, that is called a "flip chip". If I understand right, the only gold content is in the legs if its a plug in type. I don't know about any other PM inside. I incinerated 5 pounds of flip chip bases and never could recover any amount of gold from them.

I looked into this stuff a little bit now, and it seems that they have very little need for gold in these "flip chips". There's some plating that is used to make the contact between the silicon and the copper traces on the wafer's underlying board. The solder which connects them are called bumps, and the solder composition is a bit of a mystery. It can be several things; lead-tin, tin silver tin-gold (5%), and pure gold in some cases, but in any case looking underneath a silicon wafer just now whatever it is made of, it's not going to be much. Hopefully these rotten chips fall out of favour.

 

[patnor1011]

Time to ebay my pile then. To let somebody else to figure out what to do with them. :mrgreen:

 

[patnor1011]

I got mail from member asking me something so I replied but I think it will be good to post it here too as it may help some other members too.

Email:

Hi. I downloaded & read your incineration PDF. I was wondering how much coal you used to consume the 7kg you started with? I can get some coal, which I believe will burn hotter & last longer than charcoal, but I've never personally burned coal so I don't know how much to use.

My reply:

It is really hard to say. It probably depend on where you going to do it. Some people do have heating systems based on some stove or burner using coal, here I guess it will take shorter time and less fuel but it will need to be done in some closed steel container with few small holes to allow gas to escape.
I did it in regular size open fire place like people do have in living rooms. I am guessing right now but say it had space like cube 50 cm x 50 cm and is deep probably like 50 cm as-well.
In there I put probably about 1-2 kilograms of coal - well it can be seen on my pictures that will show you how much I used.
If you want to know total amount it depend on many things. I now do them only few pieces at a time. I mean that if there is few pieces on tray and in fire they burn properly and faster on the contrary of putting there full bowl or too much of them on tray like one on another. I now prefer single layer of them. That will make them to burn properly, they become white and very soft-crumbling that enable me to separate center Si piece and sieve out powder with wires and separate pins.
If you put them in fire in container where they are stacked one on another then those in middle will not burn properly and will require additional crushing.
I will estimate that I spent about one bag of coal which is 40 kilograms in here.

I will suggest that if you cut them off boards with knife then proceed to incinerating but if you just desoldered them and they do have legs still on them then if you have source of cheap HCl then soak them in warm HCl to dissolve as much of legs as possible. They do not contain any values, most if not all PM are locked in center of IC so dissolving legs will work for you to speed up later recovery from incinerated material. (less base metals with values to deal with).
Regards Pat.

 

[patnor1011]

My latest babies, they were born last week, labor was quite painful and involved a lot of washing and crushing and cursing... :mrgreen:
Source: 3800g of s/n bridges, 2000g of RAM chips.
Yield: 22,5g (4 buttons pictured are 5g each, I still have 2,5g of powder)

 

[rewalston]

Look beautiful Pat, so S/N bridge and RAM chips are the only real ones worth going after on the boards? None of the other flatpacks?

Rusty

 

[Geo]

Rusty, they are not worth the time. You can send them to me and I'll happily pay the shipping. :mrgreen: Seriously, all quads or flatpaks should have precious metals. Almost all will have gold bonding wires. When the weather finally breaks here, I intend on doing a start to finish video on flatpak chips.

 

[patnor1011]

I do save and process all of them with exception of eprom like IC. They are saved too but I do not have intention to process them, I may try to eBay them later on.
I did only RAM chips this time as I am trying to find out approximate yields of different types. I am so far convinced (all my test batches proved) that s/n bridge type run at least 5 g of Au from kilogram.
I am now close to have number for RAM IC (thin & thick).
The rest of IC I like to separate to thin and thick type and those two then to small and big size.

 

[patnor1011]

Here is what you can and should expect in pan from 100 grams of s/n bridge BGA chips. Longer wires accumulated to nice ball, small bits of wires all around pan.

 

[wadocgold]

What method was used to crush chips?

 

[patnor1011]

Incineration of chips and then I just crumbled them with fingers. You see, when they are incinerated properly they crumble to powder without much effort. Then I just washed most of ash with water. What remained were just bonding wires and some small pieces of plastic. I just used spoon to mash rest of burned plastic and wash away with water. At the end just gold remained in pan.

 

[samuel-a]

Here's the way i do it...

Though panning isn't my choice for small batches... I do feel that some sort of flotation separation should be done on a larger scale, say 5 lb. and upward.
I have plans on building a bit larger incineration unit which includes an after burner to keep toxic emissions to bare minimum.

 

[nmlfreitas]

Hi Sam congratulations on the video once again a good help.
I just have one doubt it might sound stupid. On the video, almost in the end, you say that you process the ash without the magnetic pins into AR.
Don't you have copper based material on that ash? Should we run it through 50:50 Nitric like Patnor does it? Or that is just for the metallic pins???
Or is it because Patnor is processing N/S bridges at the same time?

Sorry for my doubts I hope you can help me.

 

[Geo]

Most quads and dips have iron based legs. After incineration and milling, the magnetic material needs to be removed before processing.

 

[nmlfreitas]

Hi Geo
Thanks for the info. I knew about that I'm just trying to find out why Patnor on his Guide washes those wires with dilute nitric.
We only come across those wires with flatpacks right? With ICs we have only powder right?
And if the same process is applied for the baby powered. I guess when we have powder we can go strait to AR.

 

[Geo]

All the IC packages will have iron legs (except the north/south bridge chips). After removing the iron, nitric wash is to remove the few copper legs and the small amount of silver/palladium in the glass chips. Also, after the nitric bath, you may see some white material that would not dissolve in the nitric. This will most likely be bits of melted aluminum. Aluminum is used under the packages substrate as a heat spreader. After the nitric bath, incinerate the powder to remove the nitrates. Now place the powder into a HCl bath to remove the aluminum. After this wash, rinse with water and process with your choice of chemicals.

 

[patnor1011]

Yes, no pins inside s/n bridge but occasionally you may end up with copper too, when you split top and bottom part some copper leads might get stuck (and believe me they will) on top part so I wash concentrate from that in Nitric too.

Other IC will have some amount of copper based pins you will not be able to remove all with magnet so I wash concentrate in Nitric too.

AR is final step for me. I like to wash concentrate in nitric, that will get out any silver present and that will add up to our pm pile.

 

[nmlfreitas]

Patnor and Geo thanks a lot.
Now I'm sure how I will perform my experience.
I have about 800gr of IC and 100gr flatpacks. I guess I will treat them separatly and then join them on AR.
Do you think that EEproms should be mixed with ICs or EEproms don't have any PM on them?

 

[patnor1011]

I don't mix them. Plastic common ones don't have much in them.

 

[solar_plasma]

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.