Any Experts Regarding Scrapping Motherboards?

alloy_II

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On gold plated fingers just below the gold, nickel plating over the copper, the reason for this is to keep the gold from migrating into the copper.

From the motherboard, you can see where the gold has migrated into the copper.

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alloy_II

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Dec 24, 2021
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Copper from the motherboard leached in acid, filtered then cemented out with aluminum scraps.

In the electromotive series of metals any metal below aluminum will cement out and this accounts for the dark color of the cemented copper.

Once its dried out I'll weigh up the copper just to see how much was in the motherboard. Maybe I'll cast the copper into a small anode then part the copper electrically in the parting cell.

The only issue is that I do not own an analytical scale to weigh up such a small amount of gold.

copper leach.jpg

pats flash copper.JPG



Electromotive-series-of-metals.png
 

alloy_II

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Dec 24, 2021
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This, other elements traces of gold.

Abstract​


This work proposes a method for the recovery of tin and silver from wave soldering dross produced during the manufacture of printed circuit boards.

Samples of wave soldering dross were first subjected to carbothermic reduction to obtain an ingot containing the above metals plus other elements.

This ingot was then subjected to electrorefining at different densities of electrical current, electrolyte flow rate, and cathode-anode separation distance, to determine the optimum conditions for recovering pure tin.

Under such conditions, 82 wt% of the tin in the ingot was recovered at a purity of 99.94%. After subjecting ingots to continuous electrorefining under optimum conditions for 845 h, the slime collected at the anode was removed for the recovery of silver.

This slime was subjected to thin-layer leaching with concentrated nitric acid. The leachate produced was subjected to copper-cementation; the silver adhering to the copper rod was collected by washing.

This process recovered 92% of the silver in the wave soldering dross ingot at a purity of >99.6%. Some 99% of the copper entering the leachate from the copper rod during cementation was recovered by liquid-liquid extraction with 40% LIX84 (dissolved in EXXOL D100).

This method could provide a rapid, inexpensive means of recovering pure tin and silver from wave soldering dross.
 
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alloy_II

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Typical wave solder alloy Sn96.3 / Ag3.7, so for every hundred pounds of scrap solder recovered there would be theoretically 3.7 pounds of silver.

Roughly 54 troy ounces of silver per hundred pounds of scrap solder.

The hot solder used in the wave process acts as a solvent as if passes over any gold plated areas it leaches minute traces of gold. As the solder in the pot becomes overloaded the operator will exchange the solder out for fresh.

The most common sources of solder pot contamination will typically be material included in the assemblies that you are running across the wave. Copper can be a contaminate at certain levels and minute amounts strip off of each board that goes across the solder pot. The same goes for gold or silver if you are using it as a surface finish.
 
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alloy_II

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Something that caught my eye from the hot solder article, silver surface finish.

I highly recomend reading the full article, I found it very interesting.

Silver surface finish.

Immersion silver PCB is a printed circuit board which surface finish is coated by immersion silver, immersion silver is most used for aluminum wire bonding, metallic dome contacts, and EMI shielding. The thickness of immersion silver is 5 micro inches to 12 micro inches, and is can be store for at least 12 months.
 
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alloy_II

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The motherboard above 25.9 grams of copper, dirty silver chloride in the jar turned black - UV light.

Not sure what the brown layer is in the silver jar, but I believe silver is above gold in the electromotive series of metals, it's possible the silver precipitated the gold out of solution.

Top image is cemented copper from another source, used to give an idea of what clean copper looks like. The motherboard copper contains other elements.

This will be my last contribution to this thread, many thanks to the original poster for posting the question. It gave me inspiration to get off my ass.

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crashbandicoot

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The motherboard above 25.9 grams of copper, dirty silver chloride in the jar turned black - UV light.

Not sure what the brown layer is in the silver jar, but I believe silver is above gold in the electromotive series of metals, it's possible the silver precipitated the gold out of solution.

Top image is cemented copper from another source, used to give an idea of what clean copper looks like. The motherboard copper contains other elements.

This will be my last contribution to this thread, many thanks to the original poster for posting the question. It gave me inspiration to get off my ass.

View attachment 2021626
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Very good series of posts Alloy! Gotta digest all this.Thank you!
 

alloy_II

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While preparing some boards for the pyroliysis reactor came across this Cyrex MII.

Board preparation, removing battery and capacitors, graphics chip and cpu.

Unfortunately the installer did not use heat paste between the heat sink and the cpu, as the fan gathered dust it became unbalanced causing the scuff.

cyrex.jpg

 

ARC

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While preparing some boards for the pyroliysis reactor came across this Cyrex MII.

Board preparation, removing battery and capacitors, graphics chip and cpu.

Unfortunately the installer did not use heat paste between the heat sink and the cpu, as the fan gathered dust it became unbalanced causing the scuff.

View attachment 2025916

Out of curiosity ... what is / why is this chip ?... special why IOW's ?
 

alloy_II

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Out of curiosity ... what is / why is this chip ?... special why IOW's ?
It's a low end collector CPU $20.00, due to the scuffing its worthless.

Incompetent installer, is the point of interest.

Unfortunately the installer did not use heat paste between the heat sink and the cpu, as the fan gathered dust it became unbalanced causing the scuff.
 

ARC

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It's a low end collector CPU $20.00, due to the scuffing its worthless.

Incompetent installer, is the point of interest.

Unfortunately the installer did not use heat paste between the heat sink and the cpu, as the fan gathered dust it became unbalanced causing the scuff.
Darn it... i was hoping you were gonna say... "it has the most gold of all CPU's ever produced.

And to think i just tore apart 36 computers in a junk pile looking for one.

:P
 

alloy_II

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With my fixation with gold, I was tossing out the baby with the bath water.

it appears the real value in mother boards is these tiny surface mount capacitors with palladium and silver.

The dish was first tared before the powder was added.

p1.png


p2.jpg
 

ARC

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Please elaborate... i see several items that appear to "surface mounted".
 

crashbandicoot

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Please elaborate... i see several items that appear to "surface mounted".
I,ll jump in since alloy II hasn,t yet. The items he,s talking about are the tiny black and brown components with silver ends.resistors and MLCCs. They have a recoverable amount of silver and palladium,the yellow ones are tantalum capacitors,I keep them but don,t know what their value is,though supposedly they do have some. I havn,t researched them much.There,s also black and blue tantalum capacitors but I don,t see any in the pic. Many videos on Youtube about recovery of values from MLCCs and the little resistors.
 

alloy_II

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I had not processed any e-waste for the past five years, what I've learned from this most recent event.

The newer electronics have fewer chips and next to nothing for gold, if you can find a buyer, you'll make more by selling the mother boards.
 

crashbandicoot

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I had not processed any e-waste for the past five years, what I've learned from this most recent event.

The newer electronics have fewer chips and next to nothing for gold, if you can find a buyer, you'll make more by selling the mother boards.
True,gold is hard to come by on these newer boards,less of it too.You,ll do about as good by harvesting the copper and aluminum,easier to get and sell. There,s several places online that buy boards,I don,t recall the names offhand.Search E-waste buyers,motherboards and you,ll find them.
 

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