# Piggy back chip, Pd?



## qst42know (Jul 31, 2008)

First I'm new to this forum as you may have guessed. These are the chips that sparked my interest in recovery of PMs. They came from an early IBM main frame, massive things that looked more like large chest freezers on wheels than computers. My earliest experiments with refining these involved a fire assay techniques learned from a 1909 college text. Three of these paired chips were crushed, lids and all and added to a quantity of metalic lead and roasted in a homemade portland cement cupel with a large propane torch. When my pinch of this pinch of that (borax, soda ash, and crushed glass, and other at hand minerals) when the flux was just right the steel lids and legs would bubble brightly, liquify pass to the slag and be absorbed by the cupel. When the cupel had become completly saturated from the sweating lead, the metal ball was cooled and added to another fresh cupel. It took 4 or 5 cupels to reduce the mass to a golden bead that would sweat no more. Most of the time I would end up with a droplet of about 1.5 grams.
As a collecting of any PMs rather than refining and having lost its entertainment value I set this process asside for several years, untill I found this site. I have tried small batches of header pins, fingers, and small pieces of karat gold and met with some sucess. This site has sparked my interest again. However this chip has got me stumped. One chip added whole in a test tube with 20cc of poormans AR and heated with more AR required for a total of 40cc of AR disolved all visable traces of metal, some likely remain in the ceramic (saved for crushing). The contents of the test tube were filtered into a 4oz jar diluted with the water to rinse the test tube and filter, a small amount of HCL was added to reduce the cloudiness. Some hot urea solution was added with no reaction. Stannous test was dark purple. Added SMB no fizzing and some black powder began to settle. Left over night the bottom of the jar was covered with a black powder, the solution remains transparent black like smoked glass. Stannous test first on a swab was brown and then on the base of a porcelain dish (not having a proper spot plate) a brown precipitate. 
Is this iron? Hoke states iron does not react to stannous? Is this Pd or something else? Where is the best place to aquire DMG?
And I suspect one or more of you has processed this chip and what methods did you use and what were your results?
https://photos.buckeye-express.com/albums.cfm/4285
Please let me know if the photos will not display.
Thanks


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## qst42know (Jul 31, 2008)

https://photos.buckeye-express.com/listalbums.cfm/111535


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## goldsilverpro (Jul 31, 2008)

I doubt if there is any Pd in there. I have processed many millions of parts that look identical to the top half and have never found Pd. I'm not saying it's impossible, however. 

1) The base metal is most usually kovar - 54Fe, 29Ni, and 17Co. It will test magnetic. That includes the legs, the lid, and the ring under the lid, if there is one. It doesn't look like there is one.
2) The gold plating is thick - about 40 - 60 micro". 
3) The lid is most likely held on with a 80/20, Au/Sn eutectic braze. 
4) The chip is probably attached with a Au/Si eutectic braze containing about 97% gold. 
5) The legs are attached to the leg pads with a Ag/Cu braze. 
6) The wires attaching the chip to the inside fingers are 9999 gold (if yellow) or Al (if white). 
7) The leg pads, die pad, lid ring pad, pads underneath the gold plated inside fingers, and the inside traces connecting the inside fingers to the legs are all moly-manganese. All these are applied as pastes to the ceramic and fired. 
8 ) The ceramic is alumina containing a 5% glass frit, in order to hold it together. 

From my experience, that's about the size of it. 

I don't know about the bottom half. It looks similar. Also, I can't tell what's inside the top half. I'm assuming it's the same as the single parts that I worked with. 

If the brazes are as described above, the top half would be worth several hundred dollars, per pound of parts, in gold. These are 16 leads. Those with more leads will be worth less per pound. Those with less leads will be worth more per pound.

It looks like the part was made in 1983.


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## qst42know (Jul 31, 2008)

The upper and lower chip appear identical though only the top chip is numbered a reliability redundency I suppose. The connecting wires are gold and the lid braze is a silver color. Everything else seems identical to what you described. The edge braze was the last to go so I suspect it was silver as you indicated it took the last 5cc of AR to finish it. I saved the solder from the boards as well as some of the leg to leg braze appeared washed away and likely has some values. Anyhow I have 490g of these chips to recover. Would this be the best approach or would some other process or series of processes be called for? Thanks GSP


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## goldsilverpro (Jul 31, 2008)

The color of the 80/20, Au/Sn eutectic is almost white. 

The key to success is getting everything into solution. The most difficult thing to dissolve is the Au/Si braze under the chip. This is important because it could be 20 - 30% of the value. If you can slide the chip around on the pad, it is complete. It helps to crush these up a bit. Especially the chip area. This increases the edge area of the chip so the acid can penetrate underneath it with more volume and speed things up. If it weren't for the braze under the chip, breaking up the part wouldn't be necessary.


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## qst42know (Sep 28, 2008)

I ran some tests on a couple of these chips in a test tube. Nitric acid eats both the solder that holds the lid on as well as the base metal of the lid yielding some nice gold foils from top and bottom. I will continue to add nitric until the lids are no longer magnetic. The gold foils will be treated with Ar. This solution now resembles Dijon mustard. I have been rinsing this mud with hot water. Add large quantity of hot water stir vigorously and allow to settle. The upper solution is a transparent rust color. I am still rinsing but can see that a heavy layer of insoluble white silt will remain. It is very fine but heavy settles quite quickly.

Would this be silicon from the solder? 

Do you think this would interfear with the AR treatment.


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## synthetiklone (Oct 5, 2008)

Hi,
FYI:sorry, edit, thought you were takling about another ibm mainframe chip, but will leave this as i useful anyway 
BTW, youve probably got gold there, it is dark prolly cause of dragdown other metals in solution. I rinse well, use nitric to dissolve others, and then rinse well, use hydrochloric.. then you get nice tan colour powder. Or you could re-refine.
Make stannous, and AuCl as a test solution, and chk to see if your stannous is working, that way you know u have precip all!..
all the best.. SK

I've recently processed some of these chips for gold, and noticed that on the larger ones,
with the ROWS of gold p pins on the bottom (not the 3081's with a single dense grid of over a thousand pins).
After dissolving in A, I noticed that there was lots of small square bits floating in the AR, and that also,
left on the top of the ceramic, the gold had dissolved, but the traces, and lands were a silvery colour, not dissolving in AR!
I'm presuming this to be platinum maybe, and is the reason I am now on the forum searching for a way to
reconstitute it into a single lump of metallium de platinum (palladium?? dunno)..

The MCMs (multi chip modules) that have this are the large ones, about 130mm square, and about 8mm thick ceramic.
This ceramic block is actually up to 60 layers of sintered layers, each having a mask of silver interconnecting
wiring, hardwiring the pins and the ball grid arrays together. The small 5mmsq chips are multi processors, and other varoius
RISC chips, quite cutting edge for the 80's. The basic IBM mainframe using these cost $130 million to buy!
I have quite a bit more info on these, which is why its kind of sad to reduce them to a lump of gold, ohh well, such is life.
They were manufactured in 1984, they have the copper spring piston heatsinksto the aluminium block,
(not the aluminium heat transfer piston ones) and also are filled with a silicon based gooey compound
which has to be removed before processing. They also have a yellow coloured mask on the ceramic surface where the chips are.
This has to also be removed, as it covers the silver traces.

I placed a chunk in hot AR, and the silver PGM? traces dissolved. A stannous test showed up bright blue, then faded awhile later.

I didnt really want to process these, as they are very collectable, but the first chipped one I did yeilded about 10 to 15 grams of gold,
and that was a plain 3081, not with the gold plated carrier frame! I decided (sadly) that a collector would never pay the equivalent of
up to half an ounce of gold for one, so have procesed them all now, with the added surprise of the possible PGM.

These are very rare, (IBM 3081's) but have heard they sell for up to US$400 on ebay, which is roughly about the gold content.. so far.

Well, thats my bit, hope helps anyone on the lookout for them.

SK


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## patgspot (Nov 12, 2008)

Great information SK. Thanks.


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