HarryLee1506
Active member
i have 3 tons of material like the picture below taken from electronics company waste... anyone on the forum know what this is and the metal content in it, thanks u so much...
Are there any precious metals in this material?
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macfixer01
Well-known member
Those are silicon wafers that could’ve been used for setup and testing of the fab equipment, or maybe they failed functional testing, or maybe they just got damaged at some step in the processing? They’re thin slices off a large silicon boule that’s drawn and grows out of pure silicon melt. When they make IC’s they use a step and repeat machine to align and expose multiple copies of each photomask all over on the wafer, along with the chemical processes applied to the whole wafer surface at each step, to make a bunch of the dies all at one time. Once they’re completely formed and after automated machine testing of each die, then they’re all sliced apart. Only the good dies are moved ahead to each be installed into their packaging, the leads are connected to the die by bond wires, then final functional testing is done. The silicon has different doping agents applied such as phosphorus and arsenic during processing, also layers of oxide insulation, and vapor deposited aluminum to connect the different structures within the die. There really should not be any PMs on it though. They would be involved later on as part of the packaging.
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macfixer01
Well-known member
I should’ve mentioned... The processed wafers are often sold piecemeal by people on eBay for example as oddities, for art use, and collectibles. It would take a long time to get rid of tons of them that way though. Maybe you could package them in larger lots, or just sell them off in bulk to someone else who was willing to do all that work. I don’t know if scrap dealers will buy used silicon? I believe they buy Silicon Carbide tools or abrasive for example, but that’s different.
dannlee
Well-known member
There may be metal enriched pads prepared for the gold bonding wires to land on, they get hydrogen-torch welded to something other than pure glass...
- likely not enough to matter but likely it would be some nearly inert element to keep it safely locked up in the silicon die crystal matrix.
I found hard to acid bath them as they stack together, the only reason to crush them would be to make some grit that would keep most of them from covering each other up.
A before/after microscope photo showing pits & voids (or not) after AR would be cool : )
- likely not enough to matter but likely it would be some nearly inert element to keep it safely locked up in the silicon die crystal matrix.
I found hard to acid bath them as they stack together, the only reason to crush them would be to make some grit that would keep most of them from covering each other up.
A before/after microscope photo showing pits & voids (or not) after AR would be cool : )
Integrated circuits (ICs) are typically made up of various elements that are deposited or implanted onto a silicon wafer. Some of the most commonly used elements on IC wafers include:
These elements are combined and processed in various ways to create the complex circuitry that makes up an IC.
(Source: From my library)
- Silicon: Silicon is the primary material used in IC manufacturing. It is a semiconductor material that is used as the base for the IC and forms the "active" part of the device.
- Doping materials: Doping materials are added to the silicon to change its electrical properties. The two most common doping materials used in ICs are boron and phosphorus.
- Metal layers: Metal layers are used to create the interconnects between different parts of the IC. Copper and aluminum are the two most common metals used for interconnects.
- Dielectric materials: Dielectric materials are used to insulate the metal layers from each other and from the silicon substrate. Silicon dioxide (SiO2) and silicon nitride (Si3N4) are the two most common dielectric materials used in ICs.
- Photoresist: Photoresist is a light-sensitive material that is used to create the patterns on the IC. The photoresist is exposed to light in a specific pattern, and then the exposed areas are etched away to create the desired pattern.
- Oxidation materials: Oxidation materials are used to create a thin layer of oxide on the surface of the silicon wafer. This oxide layer is used as a mask during the etching process.
- Etching materials: Etching materials are used to selectively remove material from the IC during the manufacturing process. The two most common etching materials used in ICs are wet etchants and dry etchants.
- Implantation materials: Implantation materials are used to implant ions into the silicon wafer to change its electrical properties. Boron and phosphorus are the two most common implantation materials used in ICs.
These elements are combined and processed in various ways to create the complex circuitry that makes up an IC.
(Source: From my library)
The short answer to your question is Silicon(Silicium in Latin) die (for some electronic component) and no PM`s. The long version was already answered by #macfixer01 and #Marcel.
In addition to their answer, the scrap price of silicon (if you clean up and sell only the silicon without the support plastic) is around 2800 USD / metric ton (you`ll find more info in google). So if you find a scraspyard, you`ll probably make more money selling it, then buy gold from it instead of just throwing it away.
IMHO, if you find someone who would gladly buy from you, you should sell the whole package under the market price (so he would be eager to take it off your hands asap) and invest in gold coins or bars.
Alltogether the few tons of silicon (if you choose to hold on) is worthless.
Pete.
In addition to their answer, the scrap price of silicon (if you clean up and sell only the silicon without the support plastic) is around 2800 USD / metric ton (you`ll find more info in google). So if you find a scraspyard, you`ll probably make more money selling it, then buy gold from it instead of just throwing it away.
IMHO, if you find someone who would gladly buy from you, you should sell the whole package under the market price (so he would be eager to take it off your hands asap) and invest in gold coins or bars.
Alltogether the few tons of silicon (if you choose to hold on) is worthless.
Pete.
HarryLee1506
Active member
thank you very much... i have learned about these wafers, they are mostly made of silicon element. But what I want to know is whether the surface of these DIE ICs is plated or mounted by any precious metal
I live in Vietnam and this shipment is from a Thai electronics factory.
I live in Vietnam and this shipment is from a Thai electronics factory.
Unfortunately the PM`s are added when assembling the component to its final state. As wafels or dies these do not contain any precious metals.
Pete.
HarryLee1506
Active member
This batch consists of 2 types, one has a glue coating on the surface that makes the heat treatment and the use of chemicals like Ar ineffective. The second one is not glued on the surface, I put them in Ar and the result is about 3g Au/kg, but this is very little. Is there any chemical that can dissolve the glue on everyone??? It looks like it's some kind of anti-acid heat-resistant glue…
HarryLee1506
Active member
Tks u so much, the information I found said the same, but with this shipment it seems I got lucky, it seems to be covered with a layer of gold on the surface.
Hmm, it seems you have received some dies which came off the line right before incapsulation and bonding wire connection, which explains the gold content since the fixing of the die to the eventual cooling surface is made by brazing or soldering and for that you need a contact surface with a solderable metal which is a good heat conductor.
3g/kg of dies seems an awesome yield....it means 3kg/ton which = approx. 190000USD of value
Pete.
HarryLee1506
Active member
3 Gramm per Kilogramm would be a high-yield material. That makes 3 Kg per metric ton. South African ore contains around 4g per metric ton. Have you tested the purity of your refined material?
HarryLee1506
Active member
yes i made the finished product and it is exactly about 3g per 1kg of material... each sheet weighs about 10g so it takes about 100 panels to get 1kg. i'm having a problem with the 2nd material, there's some kind of glue or plastic on the surface that i can't get the gold out, i grind it up and soak it in cyanide for 1 month run it through activated carbon but only get 3g of gold, only a little gold around the material is dissolved, is there any chemical that can decompose them, someone please help me...
Glue will burn. Silicon hardly. That can be one option, but I do not know anything about diffusion of gold into the silicon matrix, so this can be an issue.
Type of glue will be helpful. Some are destroyed by hydroxide solutions, some will resist. Some can be dissolved in organic solvents, some couldn´t. And some are simply from interlinked polymers, so they cannot be removed by non-destructive ways.
Type of glue will be helpful. Some are destroyed by hydroxide solutions, some will resist. Some can be dissolved in organic solvents, some couldn´t. And some are simply from interlinked polymers, so they cannot be removed by non-destructive ways.
HarryLee1506
Active member
Thank you very much, your information is very helpful... AR, NaOH, heat all have no effect. If someone knew what kind of surface this was on it would be easier to handle.
#orvi has the point. I agree with him on this one.
In addition to his description. Try industrial solvents first, acrilyc solvent, acetone, alcohol, benzene, petroleum etc. and whatever solvent you can find and work your way up to acids until you figure it out what type of coating you do have. If you use solvent, for better effect you need a constant stirring or vibrating and exposure to large surface. (that is my experience)
Unfortunately if you have the gel type thermo polimere, you have bad luck, that gel cannot be removed with any type of solvent, it is thermo resistent up until 1000 degree C or maybe higher. That clear gel can only be removed mechanically. I hate that gel stuff, came across in high power transistors (eupec) it is very hard to get rid of. The picture is downloaded from google just as example of what i am talking about.
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HarryLee1506
Active member
awesome, this is exactly the info i was looking for, thank you very much. I will try and let everyone know the results.
Has the thermopolymer you talked about found a cure?
dannlee
Well-known member
There are silicone caulk removers that work by breaking the bond between dissimilar materials - otherwise the are no known solvents for silicone based products - that might be the key, loosen the grip so it can flake/peel off.. .
