Old Z80 plastic CIs

[Geld Konig]

Hi guys.

I want to know how to get gold from old Z80 CIs. I broke some and see that "pads"from CIs are gold plated and the substrat where Chip is attached. all are gold plated. The CIs are plastic made, some are ceramic. The last is easy to broke and reach the silicon chip and pads.What are the best chemical and physical process to do? I think the best process is to broke all CIs and use NaCN. what Y think? thanks

 

[butcher]

CI's
I think you mean IC's integrated circuits.
there can be several different ways to process, exposing the metals to acids would be important, here I would crack them to bits at first (not dust) and do a leach for base metals,( or series of leaches), to get as much base metals seperated as possible, decanting pregnant solution, once the acids leaches got all the base metals they could. then would do leaches for the more nobel metals, when acid could reach no more value, then I would powder them and re-leach them, reason being fine powders can complicate filtering solutions and so on.
stannous chloride tests are important, to be able to find values in solutions.
my goal is normally to eliminate the base metals as much as possible before going for the more valueable metals, by using one of different processes preleaches such as HCl/Peroxide method. or nitric acid method, after base metals are pretty much eliminated.
then can use either HCl/Bleach. or aqua regia method to go after the more valuble metals,

I have never used cyanide and hear it can be used selectively to go after gold.

which method I chose can be determined by cost and availability of reagent chemicals, ease of use, and safety.

 

[goldsilverpro]

If the pad is gold plated, it is very possible that gold solder (gold/silicon) was used to attach the chip (IC). Also, if the lid is gold plated, gold/tin solder could have been used to attach it. I know of no cyanide formulation that will attack either of these alloys.