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have you tried running any more lots of those small bga chips from RAM chips? I ran a second run with even worse results than my first attempt... has anyone else tried running them?
My results of specific types of IC chips, flatpacks and BGA
- Thread starter Tzoax
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solar_plasma
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richard2013
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mls26cwru said:
Can you show samples of the BGA chips you process Thanks
Tzoax
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mls26cwru, one of the reasons that our results was so different maybe was he fact that i was not using only chips from RAM memories. There was many small BGA chips from laptop motherboards, graphic cards and other computer parts. Some of them was twice bigger (but they are still small BGA), maybe they have a better yield than RAM BGA chips. Take a look at a picture i posted for small BGA chips, there are a lot of chips that are not from RAM memories.
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I was using the BGA RAM chips from all kinds of RAM... as long as it had two rows of chips on both sides of the ram, i sheared off the chips and ran them. solder was removed before roasting, then the chips were ground, separated from the dies and fiber layer, the ash was sluiced, then the concentrates, dies, fiber layers were all leeched individually for Au recovery.
I'm thinking the inclusion of the small N/S bridge might be enough of a reason for the difference... I took a closer look at the picture and it does appear there are a decent amount of them... but why my second run was so much different, that is really what confuses me... the second batch I ran, the recovery was ~0.3g for 453g of chips (before solder removal).
Maybe by taking double row/double sided ram, maybe that meant I was only taking newer stuff that has lower PM content/Al bonding wires? That is a possibility I didn't think of before... what do you guys think?
I'm thinking the inclusion of the small N/S bridge might be enough of a reason for the difference... I took a closer look at the picture and it does appear there are a decent amount of them... but why my second run was so much different, that is really what confuses me... the second batch I ran, the recovery was ~0.3g for 453g of chips (before solder removal).
Maybe by taking double row/double sided ram, maybe that meant I was only taking newer stuff that has lower PM content/Al bonding wires? That is a possibility I didn't think of before... what do you guys think?
Tzoax
Well-known member
mls26cwru, there is no single one N/S bridge chip on that picture. All that chips are small BGA chips, not N/S BGA chips. I processed N/S bridges in a separate batch, take a look at that picture and you will notice the difference.
There are so many factors that is impossible to always have the same values. But you can know some approximate values and what you could expect from your material. The different result for 0.3g that you get on second test is not something that should be worried about, it's only about 10-15 percents less than your first test.
That simply means that next time you could expect result in that range - for example 2.7 - 3.1 grams of gold per kilogram of your material.
There are so many factors that is impossible to always have the same values. But you can know some approximate values and what you could expect from your material. The different result for 0.3g that you get on second test is not something that should be worried about, it's only about 10-15 percents less than your first test.
That simply means that next time you could expect result in that range - for example 2.7 - 3.1 grams of gold per kilogram of your material.
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my mistake, when you said you included other chips from laptops and misc. computer parts, i misread/misunderstood it... i thought you were talking about the really tiny N/S bga's and when i saw the green in the picture i assumed that's what they were. thank you for the clarification!
I think I will try third and final run of ram chips and see if my result is any better then this last time... it cant hurt and will give me something to do!
I think I will try third and final run of ram chips and see if my result is any better then this last time... it cant hurt and will give me something to do!
Tzoax
Well-known member
Trying to avoid a very small (undetectable) amount of gold, i collected some more of ceramic IC chips to make a test. I also added big one IC chips like in the picture. So this test will be for all sizes ceramic IC chips that only have gold braze (no gold plated legs, no gold bonding wires, and no gold plated caps). Also, there is no EPROM chips.
From earlier calculations i expect something around 0.4841 grams of gold per 1 kg of those chips.
Total weight of chips is 372.6g in 80 pieces. Avg weight of one piece is 4.6575g.
So from this batch i expect 0.3726 * 0.4841 = 0.18 grams of gold.
Most likely i will use poorman's AR (HCl and KNO3) to process this IC chips. I will post result when i finish.
From earlier calculations i expect something around 0.4841 grams of gold per 1 kg of those chips.
Total weight of chips is 372.6g in 80 pieces. Avg weight of one piece is 4.6575g.
So from this batch i expect 0.3726 * 0.4841 = 0.18 grams of gold.
Most likely i will use poorman's AR (HCl and KNO3) to process this IC chips. I will post result when i finish.
Tzoax
Well-known member
This is what i've done so far:
-The ceramic IC chips was settled inside of 600ml beaker.
-I used 200ml of %16 HCl with 20g KNO3 added in small portions over time, on a hotplate with temperature just below boiling. Over time vhen solution evaporated a few centimeteres i refilled evaporated volume of solution with a fresh HCl and added a little more KNO3 until solution becomes saturated (deep brown color, picture 3)
-I decanted the solution (there was no visible gold left on IC chips) and replaced with a new one, same as before (200ml of %16 HCl with 20g KNO3).
-The whole reaction is done in 4 hours. This is sample pictures from beginning to the end.
After solution was saturated a second time i decanted it and decided to stop processing it because of the next reason...
It is obvious (and i have read about it) that the glue (or what ever was used to join the two halves of the chip) was reacting with acid and it becomes white powder that is forming on the bottom of the beaker. And this process is very slow, after 4 hours there was still a lot of it attached on the chips. Considering that, and the fact that the gold is in solution i stopped the reaction because i was sure it is unnecessary (maybe i was wrong but i doubt that this substance can interfere the process between AR and reactive metals).
This is the picture of remaining white "glue" on the chips after reaction.
I neutralized the solution with urea, filtered it through double filter paper (it was very slow because of the white powder that is most likely mix of a "glue" and silver chloride. this is a picture of a filtered solution.
This is where i was left, soon i will precipitate the gold in solution with SMB.
One thing confuses me... The dies are still attached to the ceramics. It also looks like the braze is still there but it have silver like color instead of golden.
Is it possible that this was not gold braze at all? It is maybe (gold plated) Ag / Pd alloy or some other braze alloy that are not reacting with AR. I don't know.
-The ceramic IC chips was settled inside of 600ml beaker.
-I used 200ml of %16 HCl with 20g KNO3 added in small portions over time, on a hotplate with temperature just below boiling. Over time vhen solution evaporated a few centimeteres i refilled evaporated volume of solution with a fresh HCl and added a little more KNO3 until solution becomes saturated (deep brown color, picture 3)
-I decanted the solution (there was no visible gold left on IC chips) and replaced with a new one, same as before (200ml of %16 HCl with 20g KNO3).
-The whole reaction is done in 4 hours. This is sample pictures from beginning to the end.
After solution was saturated a second time i decanted it and decided to stop processing it because of the next reason...
It is obvious (and i have read about it) that the glue (or what ever was used to join the two halves of the chip) was reacting with acid and it becomes white powder that is forming on the bottom of the beaker. And this process is very slow, after 4 hours there was still a lot of it attached on the chips. Considering that, and the fact that the gold is in solution i stopped the reaction because i was sure it is unnecessary (maybe i was wrong but i doubt that this substance can interfere the process between AR and reactive metals).
This is the picture of remaining white "glue" on the chips after reaction.
I neutralized the solution with urea, filtered it through double filter paper (it was very slow because of the white powder that is most likely mix of a "glue" and silver chloride. this is a picture of a filtered solution.
This is where i was left, soon i will precipitate the gold in solution with SMB.
One thing confuses me... The dies are still attached to the ceramics. It also looks like the braze is still there but it have silver like color instead of golden.
Is it possible that this was not gold braze at all? It is maybe (gold plated) Ag / Pd alloy or some other braze alloy that are not reacting with AR. I don't know.
Barren Realms 007
In Remembrance
Tzoax do you see the silicone dies left on the chips after you have processed them? You are missing the gold under these dies and the chips need to be processed for a longer period of time.
Tzoax
Well-known member
Thank you very much, i was close to throw them away, you saved me some gold. So there is still possibility that this braze have gold. I was confused with a color, but if it is tin / gold alloy, the silver color could be from tin.Barren Realms 007 said:
I dropped gold with SMB and now i'm waiting it to settle, it looks like something about 0.2 - 0.4 g so far.
I will collect this powder and i will join it with the rest of gold powder that i process from the rest of the material thanks to you.
The remainder should be the 20 percent silicon from the braze... look at it as silicon inquarted with gold. What's left is the silicon skeleton, soft and easily broken just like inquarted gold.
Göran
Göran
Several times, I assayed those type cerdips (ceramic dual inline packages) in the photos back in about 1990. At today's prices, they would be worth about 16 cents each in gold. That's about .004g each.
Tzoax
Well-known member
This is a pictures of two chips with silicon dies still attached. If i am understand it correctly, the silver color ring around the silicon die (where the gold braze was) contains no more gold, it is a silicon remainder (skeleton) from it, and underneath a silicon die is still undissolved gold from the braze that AR still haven't reached.
I thought that braze is made of alloy of Au/Sn, but since there is a silica remainder the braze is most likely alloy of Au/Si.
I thought that braze is made of alloy of Au/Sn, but since there is a silica remainder the braze is most likely alloy of Au/Si.
Tzoax
Well-known member
I have washed the gold powder from above picture and here is the results:
Weight: 389.1g of IC chips
Number of IC chips: 82 pieces
Avg. weight per 1 piece: 4.74g
Gold content: 0.2g
Gold content per 1 kilogram of IC chips: 0.51g
Gold content per 1 IC chip: 0.002439024g
*This is only from above test, there is still some gold beneath the silicon dies, i will update results when i process them. So, for now this kind of IC chips have at least 0.5g of gold per kilogram and all of that gold comes only from the gold braze used to solder silicon dies to the ceramics.
The next test i am intending to do is with silicon dies from incinerated mixed plastic IC chips. They should have some of the braze on them. I never tried to process them, and i have a lot of them mixed with wires and heatsinks. If this test shows well i will separate the silicon dies from the rest of the material and process a lot of them.
This is a sample i will test: 68.4g. I have no idea of the yields, i hope i will get some detectable amount of gold.
Weight: 389.1g of IC chips
Number of IC chips: 82 pieces
Avg. weight per 1 piece: 4.74g
Gold content: 0.2g
Gold content per 1 kilogram of IC chips: 0.51g
Gold content per 1 IC chip: 0.002439024g
*This is only from above test, there is still some gold beneath the silicon dies, i will update results when i process them. So, for now this kind of IC chips have at least 0.5g of gold per kilogram and all of that gold comes only from the gold braze used to solder silicon dies to the ceramics.
The next test i am intending to do is with silicon dies from incinerated mixed plastic IC chips. They should have some of the braze on them. I never tried to process them, and i have a lot of them mixed with wires and heatsinks. If this test shows well i will separate the silicon dies from the rest of the material and process a lot of them.
This is a sample i will test: 68.4g. I have no idea of the yields, i hope i will get some detectable amount of gold.
I would think the majority of the gold in the cerdips is under the chips. According to my numbers, there would be .328g in the batch you did. Considering you said you didn't get it all, what you got sounds about right.
About 40 years ago, I processed a lot of those. The 2 ceramic halves contain about 5 percent glass frit in their makeup. They are "glued" together with additional glass put between them and then fired. I discovered that the halves would separate by heating them to about 800F and then quenching them in water. The glass in between shattered. I then tumbled them in a cement mixer, which broke the kovar away from the ceramic and I finally separated out the kovar with a magnet. At that point, the extreme tips of the kovar leads had gold plating on them, necessary to attach the Al bonding wires from the chips. The bottom ceramic halves had gold plating on the chip mounting pad and the chip mounting of Au/Si braze. I'm thinking I treated the ceramic with AR and didn't worry about the tiny bit of gold on the kovar.
About 40 years ago, I processed a lot of those. The 2 ceramic halves contain about 5 percent glass frit in their makeup. They are "glued" together with additional glass put between them and then fired. I discovered that the halves would separate by heating them to about 800F and then quenching them in water. The glass in between shattered. I then tumbled them in a cement mixer, which broke the kovar away from the ceramic and I finally separated out the kovar with a magnet. At that point, the extreme tips of the kovar leads had gold plating on them, necessary to attach the Al bonding wires from the chips. The bottom ceramic halves had gold plating on the chip mounting pad and the chip mounting of Au/Si braze. I'm thinking I treated the ceramic with AR and didn't worry about the tiny bit of gold on the kovar.
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Tzoax said:
I think you will be surprised from these... In my experience with BGA chips, these are always worth recovering gold from... a word of advice though, the brazing/wire is a Au/Ag alloy. Each bonding wire attaches to a lead on the silicon chip and under a microscope you can see the brazing and a 'stub' from where the bonding wire broke off. I don't have any numbers on this myself so I will be interested to see what you get!! Great thread!
I would look for palladium too among the dies. It seems like a palladium braze is often used to secure the die on the lead frame.
Göran
Göran
upcyclist
Well-known member
You mentioned your unknown white powder at the bottom of the beaker after processing, and I did notice this (emphasis mine):
I'm wondering if you have metastannic acid. Your earlier research mentioned and 80/20 braze of gold and tin. Now you're dissolving your tin in a mixture that contains nitric acid...
Tzoax said:
I'm wondering if you have metastannic acid. Your earlier research mentioned and 80/20 braze of gold and tin. Now you're dissolving your tin in a mixture that contains nitric acid...
Tzoax
Well-known member
Thank you all for great tips and advices!
GSP, it is a great way to prepare the ceramic chips and get rid of kovar legs and glass before processing with acids. I also have the EPROM chips (with no gold bonding wires) and no visible gold braze. I wonder if these contains some of the gold.
mls26cwru, i have a lot of various IC chips silicon dies that are mixed with BGA chips silicon dies. So i can't test them separately. I processed this 68.4g of them and now i am ready to drop the gold with SMB. I am very exited to see results. I will post some pictures.
Göran, thanks for the tip, i am saving the rest of solutions in a stockpot.
upcyclist, long time filtering is most probably not because of tin, because reaction between AR and tin generally produces tin IV chloride /stannic chloride (that is soluble in AR).
This is a pictures from processing IC chips silicon dies with poorman's AR - HCl and KNO3 and the look of the filtered solution..
GSP, it is a great way to prepare the ceramic chips and get rid of kovar legs and glass before processing with acids. I also have the EPROM chips (with no gold bonding wires) and no visible gold braze. I wonder if these contains some of the gold.
mls26cwru, i have a lot of various IC chips silicon dies that are mixed with BGA chips silicon dies. So i can't test them separately. I processed this 68.4g of them and now i am ready to drop the gold with SMB. I am very exited to see results. I will post some pictures.
Göran, thanks for the tip, i am saving the rest of solutions in a stockpot.
upcyclist, long time filtering is most probably not because of tin, because reaction between AR and tin generally produces tin IV chloride /stannic chloride (that is soluble in AR).
This is a pictures from processing IC chips silicon dies with poorman's AR - HCl and KNO3 and the look of the filtered solution..
