# EPROMs and Plastic IC’s, what kind of PM?



## joheleh (Apr 26, 2022)

Hi, here are some EPROMs (gold and not window) and some plastic IC’s I have, 15kg in total, are there some PM? May there be silver in the legs of the IC’s? What should I expect? Silver, gold and maybe palladium? The EPROMs are from the 80’s


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## GoldTJ (May 30, 2022)

Sorta the same question 

Kinda new into this , But got my hand on alot of old 80s-90s UV Eprom. 

I've smash somes , to see beter inside 

I cant see any gold ... Am I blind ?


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## orvi (May 30, 2022)

Gold is only present in brazing under the silicon chip - if the brazing is some shade of golden  Bonding wires are usually aluminium. Brazing do not need to be a gold alloy - there are many many "silver" EPROMs which do not contain gold or any other PMs. AuSn20 alloy could also be used for brazing, and this alloy is fairly "white"  

Plastic chips can have gold plated legs underneath the plastic, aside of gold bonding wires. Smash some with hammer or snap it with pliers and observe. 4-side leg type chips tend to have more values than classical DIP package chips. But with old stuff, you need to test it.

Advantage is that ceramic EPROMs can be conveniently split (tapping with hamer on the side), leaving all worthless legs and top ceramic part with window. There is nearly no metal other than brazing alloy and solder on the bottom part of the chip, so you can strip the gold with very little acid, and creating practically no waste.


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## eaglekeeper (May 30, 2022)

I have found EPROM's to have a low yield for gold and never found any that tested positive for PGM's. I not saying there isn't any out there that contain PMG's, but I've never found any.

Check the part numbers on eBay.... see sold/completed section for a reference on what has sold in the past. Some of those might have a collector value far above gold value.


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## Ohiogoldfever (May 30, 2022)

A drop of HCL on the bonding wires will tell you what they are. If it’s aluminum it will react pretty quickly.


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## GoldTJ (May 30, 2022)

Really big thanks for the quick answers !


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## orvi (May 30, 2022)

eaglekeeper said:


> I have found EPROM's to have a low yield for gold and never found any that tested positive for PGM's. I not saying there isn't any out there that contain PMG's, but I've never found any.
> 
> Check the part numbers on eBay.... see sold/completed section for a reference on what has sold in the past. Some of those might have a collector value far above gold value.


That´s right. They are pretty heavy, with only very small area of gold braze. Also depends on a manufacturing date. Old stuff can be pretty rewarding, but it is rare today. Some old Eastern Germany made EPROMs had also gold plated legs. But that is more of a collector stuff, not for gold recovery.

Also never found any with PGMs, logically that makes great sense - why using metals with melting points above 1500°C for brazing ceramics...


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## gaurav_347 (Jun 3, 2022)

We have processed 100s of kgs of plastic ics . The average au content is 0.3 gms per kg . We are smelting these ics so we are not sure about the silver content as it keeps getting collected .


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