Help identifying ic

[madelyn]

I have a few of these ics and was wondering if anybody,could help identify it so that I can now if it would be worth selling?
They came from telecom boards.

 

[g_axelsson]

Advanced Micro Devices
Search: AM7905ADC
Subscriber Loop Interface Circuit - 4.096 MHz, 64-channel w/expanded mode
Nom. Supp (V)=5.0
Status=Discontinued
Package=DIP
Pins=24

Göran

 

[madelyn]

Thanks axelson, but i was wondering if someone new if they are worth refining for gold or pgm?
This is how the inside looks.

 

[g_axelsson]

Yellow inside, that's gold braze used to fasten the die to the capsule. Clearly worth refining. I run them with ceramic processors and other ceramic IC:s.

Look at the bond wires, yellow is gold, white is aluminum.

Göran

 

[madelyn]

Thanks for the tip, I was thinking of selling them , but since I have a lot of ceramics to refine I think I will throw them with the pile. I have about 5 kg of them.
Thanks

 

[g_axelsson]

The glass frit, the mass between the lid and the ceramic body is probably sensitive to nitric acid, it turns into a goo that looks almost like silver chloride. I usually clean off EPROM that is made in the same way in a weak nitric bath before going to AR. It simplifies the filtering later on.

If the bond wires are made of aluminum then the legs doesn't contain anything of value and can be removed before any acid bath.

Göran

 

[goldsilverpro]

Over 40 years ago, I came up with the following method. The parts I did were not identical to these, but I think they were made in essentially the same way - 2 ceramic halves containing about 5% glass frit, glued together with molten glass. Kovar legs.

Heat them thoroughly to about 900F. I'm not sure about that temp - it's been a long time. A temp-controlled electric box furnace works well for this. Quench in water. The glass holding the 2 ceramic halves together will shatter and the ceramic halves should easily separate.

After quenching, I let them dry and then tumbled them in a cement mixer, alone, with no media. They fell apart. Then, separate the metal with a magnet (I'm assuming it is kovar). The remaining ceramic is then leached with AR to dissolve the gold.

Any gold plating on the kovar can be stripped, if desired. Most of the value will be on the ceramic.

 

[johnny309]

I have a question :
Why not using the induction furnance (with adittion of copper as a colector)...to recover the precious metals?

Iron will oxidate and Ni will do part with Cu....and Co will do the same...electrolises the Cu....

Is done by Umicore this process....ISA melt submerged lance.

Not something new.

 

[machiavelli976]

The remaining ceramic is then leached with AR to dissolve the gold.

Is there undesired chance of losing gold inside the ceramics ? I've noticed the porosity of the alumina is not quite inexistent .