AP solution for removing ic chips legs
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Sulfuric will precipitate lead during the refining process. Of coarse removing as much as possible before helps and that is where the question of “to AP or not” comes in. I prefer to let the refine deal with it. I also remove most IC’s with a small torch except for memory, those I do in a rotisserie oven. There is also a machine that desolders parts that I would like to look into. Kind of like a hot lead bath just not sure how quick it would be.
I build a rotary tumbler with a hot air gun and de solder the memory chips and little MLCC which will be screened through a sieve. Because I am a beginner I start with things which are simple in principle and learn other things which might seem obvious to others. I try to find efficiency and cost reduction and do it in a very safe manner. I have a few things which are not very clear to me and I don't like to proceed with things like that because that is how you run into trouble. The first thing is which base metals I have to absolutely get rid of before AR (the ones that will not affect the precipitation) and the second is if I have a material which contains other values beside gold like Silver Palladium , how to separate them in the extraction.
I try to separate materials but chips I gather them altogether, so they might contain silver gold, platinum ?
I try to separate materials but chips I gather them altogether, so they might contain silver gold, platinum ?
I think there might be a bit of confusion here...
Chips are made with a lead frame, not the metal lead but as a way to lead the signals in to the chip. The silicon die is often placed on top of a central flat piece. Sometimes with glue, sometimes with silver braze, gold braze or palladium. In most cases it's not made of precious metals in modern devices. The signals going to the chip is then connected with bond wires (gold, aluminium or gold plated copper is common). Every connection on the outside has it's corresponding bond wire inside the capsule.
After the bond wires are attached the lead frame with the die and bond wires are put into a mould and silicon dioxide filled epoxy is injected. After curing the lead frame is cut and the pins are formed so it reach down to the circuit board.
As a last step the pins or legs are plated or covered in tin solder. In older days the solder contained a bit of the metal lead but at least the last 20+ years the solder is lead free. There might be up to 3% of silver mixed in with the tin.
So there isn't a lot of the metal lead in most IC:s, but most of it, if there is some, is on the outside of the body.
The white ash is basically just fine sand. After a complete incineration the body should be white straight through. This takes some time though, so most videos I've seen shows a lot of black carbon left.
I have a temperature controlled oven that I use to burn off the carbon. 400-600 degrees C (slightly glowing) and a bit of air for a couple of hours, depending on the size of the lot, burns off most of the carbon and can even oxidize the lead frame. Then it's an easy task to crush the chips.
Göran
Chips are made with a lead frame, not the metal lead but as a way to lead the signals in to the chip. The silicon die is often placed on top of a central flat piece. Sometimes with glue, sometimes with silver braze, gold braze or palladium. In most cases it's not made of precious metals in modern devices. The signals going to the chip is then connected with bond wires (gold, aluminium or gold plated copper is common). Every connection on the outside has it's corresponding bond wire inside the capsule.
After the bond wires are attached the lead frame with the die and bond wires are put into a mould and silicon dioxide filled epoxy is injected. After curing the lead frame is cut and the pins are formed so it reach down to the circuit board.
As a last step the pins or legs are plated or covered in tin solder. In older days the solder contained a bit of the metal lead but at least the last 20+ years the solder is lead free. There might be up to 3% of silver mixed in with the tin.
So there isn't a lot of the metal lead in most IC:s, but most of it, if there is some, is on the outside of the body.
The white ash is basically just fine sand. After a complete incineration the body should be white straight through. This takes some time though, so most videos I've seen shows a lot of black carbon left.
I have a temperature controlled oven that I use to burn off the carbon. 400-600 degrees C (slightly glowing) and a bit of air for a couple of hours, depending on the size of the lot, burns off most of the carbon and can even oxidize the lead frame. Then it's an easy task to crush the chips.
Göran
Thanks for clarifying this, so in this case if you have have a waste AP solution contaminated already with lead it could be useful to get rid of the Pb from the solder by givin it a bath?
Attachments
Add a few drops of Sulfuric, that will take care of it.
kurtak
Well-known member
Correct - when we talk about the "lead frame" in IC chips we are NOT talking about the metal lead (Pb)
for clarification ------------
https://en.wikipedia.org/wiki/Lead_frame
Lead (pronounced leed) frame - as in a path that leads somewhere - in this case the path the signal/current takes from the circuit board through the metal legs going into IC chip then to the silicon die (chip) inside the epoxy housing
Edit to add; - in other words - the leads are the wires/legs on the outside of the chip that connect to the circuit board- & then connect to the silicon die inside the chip with a gold bonding wire
The lead (pronounced leed) frames are made of copper or Kovar - not the metal lead (Pb)
Kovar leads are removed with a magnet after incineration & milling
copper leads are removed by sifting &/or nitric leaching after incineration & milling
Kurt
kurtak
Well-known member
The basic steps for processing IC chips
1) incineration to turn the epoxy housing to carbon/ash
2) milling to turn the carbon/ash to fine powder
3) magnet to remove Kovar leads
4) sifting through 80 mesh or 100 mesh screen to remove larger copper leads (some smaller copper leads will go though sifting screen - silicon dies & other large stuff including but not limited to carbon that did not fully mill to fine powder - so likely some re-milling
5) washing off most carbon/ash to get concentrates (panning, blue bowl, sluice box, concentrator table) not all carbon will wash off - so ----
6) re-incineration of concentrates to turn remaining carbon to ash
7) nitric leach to remove copper that made it through the above (or you can do nitric leach after step 5)
8) then you can ether AR leach the concentrate - or - smelt the concentrates
Outside of that - processing IC chips has been discussed extensively on this form --- so you can do your own research using key words - IC Chips - incineration - milling - ball milling - bonding wires - concentrator table - etc. & you will find a HUGE amount of info posted by me & others about processing IC chips
Part of the process - is doing your own research (that is how I learned)
In other words - (& I am sorry if this sounds rude - it's not meant to be) but there is no need for me to post another long & detailed post about how to process IC chips - because - there is already a HUGE amount of info here on the forum that has been discussed EXTENSIVELY
Kurt
1) incineration to turn the epoxy housing to carbon/ash
2) milling to turn the carbon/ash to fine powder
3) magnet to remove Kovar leads
4) sifting through 80 mesh or 100 mesh screen to remove larger copper leads (some smaller copper leads will go though sifting screen - silicon dies & other large stuff including but not limited to carbon that did not fully mill to fine powder - so likely some re-milling
5) washing off most carbon/ash to get concentrates (panning, blue bowl, sluice box, concentrator table) not all carbon will wash off - so ----
6) re-incineration of concentrates to turn remaining carbon to ash
7) nitric leach to remove copper that made it through the above (or you can do nitric leach after step 5)
8) then you can ether AR leach the concentrate - or - smelt the concentrates
Outside of that - processing IC chips has been discussed extensively on this form --- so you can do your own research using key words - IC Chips - incineration - milling - ball milling - bonding wires - concentrator table - etc. & you will find a HUGE amount of info posted by me & others about processing IC chips
Part of the process - is doing your own research (that is how I learned)
In other words - (& I am sorry if this sounds rude - it's not meant to be) but there is no need for me to post another long & detailed post about how to process IC chips - because - there is already a HUGE amount of info here on the forum that has been discussed EXTENSIVELY
Kurt
I was wondering if I have plastic and ceramic chips mixed, incinerating them would work?
I really don't understand how your post, relate to the post you reply to?
You reply to a post from Dave, with a question regarding a totally different topic.
It is a question about incineration, I was trying to ask him this question....
I don't mean for that be rude, but Kurt is right.
There is tons of useful information on the forum pertaining to most any subject we deal with. Because it is old information does not make it bad information. Some of the posts from the past are the most informative, educational and often just plain fun to read. If you find one, then still have questions, bring it up and ask there, in the old post. The next person looking for the information can then find it easier. Another thing this does is shows the rest of the forum just how hard your trying.
If you know they are mixed, it may be better to separate them. Separately your test results will be more accurate for you than ours will be at times. Skill and knowledge, as well as equipment and methods we use can or will come into play.
Otherwise, occasionally the ceramic may pop open, at times a bit violently. And they do not grind/crush very well.
There is tons of useful information on the forum pertaining to most any subject we deal with. Because it is old information does not make it bad information. Some of the posts from the past are the most informative, educational and often just plain fun to read. If you find one, then still have questions, bring it up and ask there, in the old post. The next person looking for the information can then find it easier. Another thing this does is shows the rest of the forum just how hard your trying.
If you know they are mixed, it may be better to separate them. Separately your test results will be more accurate for you than ours will be at times. Skill and knowledge, as well as equipment and methods we use can or will come into play.
Otherwise, occasionally the ceramic may pop open, at times a bit violently. And they do not grind/crush very well.
Well, ask the question then, without quoting to something completely unrelated, please.
And as Kurt and Shark said, there should not be much that has not been discussed on the forum.
Learn to use the search function and you will end up learning more and better.
kurtak
Well-known member
Per the bold print --- I don't mean to be rude - but - use some common sense here
Ask your self --- does ceramic burn ? --- Answer - NO
Does ceramic easily crush (mill) to a fine powder ? --- answer - NO
So - why would you mix them in with epoxy (plastic) chips that burn & then mill to a fine powder
Kurt
I was not sure of the exact composition of the so called "ceramic" is what people refer to ceramic, I heard even plastic is not actually quite plastic so due to the overwhelming number of variants I thought I could ask here.
I have not started yet because I have some chips which I have collected together in a bucket and was not sure if plastics will melt or create some other unforeseen problem. My plan was to incinerate all, finely grind them with my new 39000 rpm mill and then use the washing and decanting method I have seen in an older video of Jeff where all water decanted is recirculated. My worry was that plastics will melt but was thinking that at a high temperature it will burn off.
Before I do a test I usually try to think through the process, to the best of my abilities and if it sounds like it should work I do it. I did a test with the plastic connectors, the initial plan was that after grinding plastic will float but I could not grind all the plastic, it would actually melt in the mill at that speed so I got another type of slower mill for the connectors.
EDIT: the chips I collected are of all kinds toghether
Having ask before starting is a great way to learn at a lower cost. While it seems some of the comments are harsh they aren’t meant to be. Patnor, an older member, did a pretty good write up on how to process these years ago. It worked for me with a pound or two at a time. Kurt has been doing them longer and in larger volume than anyone else I have heard of, at least that is willing to help out. Find the posts from both and learn from them. Then think it all through again. I would concentrate on Kurt’s method, I think long term for volume it will be the way to go. Kurt is semi retired, or retired from refining so he is limited on time.
Who is Jeff, besides me and Geo?
Who is Jeff, besides me and Geo?
