3golden legs transistors

does anyone knows the yeald of gold in those transistors with 3gold plated legs?is there pd and ag in these transistors besides the gold plated legs?

since no one could give me a reply,i did the experiment with cianide and from 3,90kilos i extracted 10,8grams of gold from the golden legs-----2,76grams of gold per kilo------now i am left with 3,9kilos of magnetic transistors---which i think there is no pms inside but i will try to confirm it by experiments---thanks all

Nearly four kilos and nearly eleven grams of gold.
Want to sell some? :lol:

Mark

Do you have a picture of these 3 golden legs transistors?

thks

Are you talking about these?
http://www.sodz.com/tech/Article/UploadFiles/200805/20080528170633639.jpg

Or, these?
http://www.allelectronics.com/make-a-store/item/2N2222A/NPN-TO-18-TRANSISTOR/-/1.html

gsp,i am talking of your first link -----not from alleletronics

Arthur,
Would you mind sharing your source for this material?

Chris,
Nothing gets past you. This is why I read every word you post on this forum.

Mark

Thanks, Mark,

When I consider the value of these type things, I only consider the package type which contains the chip. I have no interest in chip numbers or part numbers. Only the package. That's where the value is.

Is this case, the package is a TO-5 transistor header. I've seen them made of copper but, usually, they're made of Kovar, a magnetic alloy of 54Fe, 29Ni, and 17Co. They've been around for 50-60 years and, in general, over the years, they have become less valuable. There are often more than 3 leads. The very early ones were painted black. Scratch the paint off and the entire thing was gold plated. Today, these might be worth well over $100/pound, in gold.

Early on, they stopped plating the top hat (the lid), and they looked very much like the one in the photo. The most valuable of these used Au/Si solder to attach the chip. In the mid 70s, we dissolved many tons of these, in a tumbler, using about 30-40% nitric acid. Using today's prices, they would be worth at least $100/pound, assuming the die (chip) was attached using Au/Si solder. Some of the newer ones use silver solder or epoxy for die attach.

Arthur,

If the visible edge of the header pad, under the top hat, was gold plated, like in the photo, there is a lot of value still inside. If not, the value was primarily in the leads - although that doesn't make much sense to me.

most of the gold is under the silver cap and can run as high as 2 percent gold by weight.

gsp,the edge of the header was gold plated and now it is deplated--- the transistors after the gold deplation have a silvery aspect and it is highly magnetic---- deducing that the inside of the hat there might be gold(watlarry mentioned up to 2% by weight)-----how would i act to reach for the gold under those silver caps?----------

Mark ,tomorow i will receive another 20kilos of these transistors and i will ask my son from where he got it--my son is my buyer of precious metals scraps and he buys everything from silver contacts to platinum containing aircrafts sparkplugs---fantasy rhodium plated jewellery---he buys from industries,from scrapyards etc---these transistors he payed 3dollars per kilo(very cheap)----

Arthur,

I would probably use nitric acid to eat everything but the gold. Then use AR until the gold is dissolved and the chip is free to slide around on the pad - this way, you'll know that you're getting all of the Au/Si solder under the chip - the Au/Si solder is key to high value on this part. Instead of HNO3, Steve's HCl/H2O2 would probably dissolve the kovar, but it would be slower.

2% seems high - $274/pound - but there may be varieties that run that much. I'm thinking that the tons (literally) we ran were about $35/pound at a $180 gold market. That would be $182/pound today, or 1.3%. However, these were from one specific manufacturer. Whatever, you'll find out. Only the refiner knows the true value, when he puts the gold bar on the scales.

Arthur,
2.2 pounds X $182( GSP's #'s) - $3 = Goldmine. :lol:

Congratulations, and good luck, I hope he ( your son) can get many more.

Mark

i wrote 2hours ago an ouline of how i acted to obtain the gold from the inside of the transistor but it seems that the outline got lost in this thread---------i am going to try to recall what i wrote-----first i said that i followed gsp s sugestion and it worked very well---thanks gsp--i admire your experience and read all your threads with great pleasure ---you are a master----
i took 200grams of the deplated transistors and used nitric acid as you sugested---the gold foils , the chips(ceramics) and more gold foils mixed with a jelly stayed in solution and i filtered it out----then i incinerated this material and put it in ar-----the ar solution was treated as usual with smb and the gold was precipitated----the 200grams resulted in 1,52grams of gold or 0,76% by weight---i thought that the 10,8grams obtained from the 3,9kilos would be all, but the 200gram which i tested projected more 29,64grams of gold ---the total 40,4grams of gold in 3,9kilos of 3golden legs transistors----fantastic ---thanks again gsp for your experience

Excellent, Arthur. You're becoming a very good refiner. I very much like your approach and your detail. Also, you don't screw around - you go right after it, with intelligence.

That's $142/pound, which is in the range that I remember. It's always nice to hit a $6,000 lick with a bucket of stuff. The key, of course, was finding those with that gold ring. Some of the newer ones have no gold ring and are virtually worthless, except for, maybe, a little silver. Some of the worthless ones have an aluminum lid. The TO18s, the smaller ones in the second link I gave, will run even higher per pound if they have the gold ring. The TO18s were almost as common as the TO5s. Another key was the gold leads. In knowing how they plate these things, if the leads are gold, the pad will also usually be gold.

You can inspect the insides simply by squeezing the lid with a pair of dull diagonal cutters or pliers and then twisting it off. I use a 10X eye loupe - I always keep a loupe and a magnet handy in my pocket on my key chain. Au/Si solder will usually be seen bled out around the edges of the chip and will usually be a very faint yellow color.

I had forgotten about the insulating gel that is in some of these. I'm glad that you were able to incinerate it successfully.

As a general rule, in all types of packages, when the chip is attached to a gold plated surface (pad), it is attached using Au/Si solder. Since this solder is about 20 times thicker than the gold plating, that's where a lot of the value is. It is similar with the lid. If a gold plated lid is soldered to a gold plated pad or ring, they usually use a Au/Sn solder (braze). In this case, a Kovar lid is soldered to a gold plated pad, so I doubt if this solder on the lid contains gold.

The very pure gold plating on these is about twice, or more, as thick as that on circuit board fingers. To attach the chip, they had to use enough heat to melt the Au/Si solder. During the heating, if the gold were thinner, the heat would migrate some of the underlying metal up through the pores of the thin gold plating and the gold surface would discolor from the base metal oxides. Therefore, as a general rule, anytime a chip is soldered to a gold surface, the plating will be quite thick. Thick gold plate is less porous than thin gold. For the same reason, all metal portions of the header must be covered with gold, including the leads, since any base metal left unplated would discolor from the heat.

I mention these things because the more you learn about how and why different parts are made and assembled, the more success you will have in buying and refining. That has always been my approach. Just remember that there are always exceptions to all general rules in this business.

Chris

thanks again Chris for all the information and stimulus given to me----today i received another 22kilos of the same transistors from a lot of 96kilos of other strange materials that also contains pms----and will relate to you and to the forum how i am dealing with these refinings-----this materials comes from a circuit components industry that ended its activities a decade ago------Mark, this industry is from a city called Campinas which i think you lived there for a few years( i am not sure)----

Arthur,thanks for sharing your source.
I did not live in Campinas but my second wife did for a few years, until she left to attend college at Auburn.
Her dad was an engineer for Dupont there, until he was transferred to another plant at Waynesboro Va.

Mark

together with the golden legs transistors came not golden leg transistors---i put some (250grams ) of these in hno3 1:1 and then h2so4 to dissolve what i supossed to be (iron)(brown solution)---the h2so4 dissolved the brown solution and in this solution i have gold foils dancing---i was and am looking for ag or pd and found gold---i will go after pd and ag today-----i did these because a friend told me that the black plastic headed transistors have pd and soon i will have these black headed transistors----i am deducing that all or almost all type of transistors have pms in them---please give me some coments of this---thanks arthur

Photo of chip and pad underneath can.

i have several pounds of these from the 50s/60s. gotta revisit em.