Hi. I want to ask a question here. But I can see this post is a little old.
Want to open this up again as this actually is the Q&A post for fiber CPU's and HCl leach.
I started a batch with fiber CPU pins today, and boiled it for 3 hours in HCl in a erlenmeyer flask. The solution turned green pretty fast, that is copper right?
I sat up a condensation setup with a cork and a tube, I watched it for an full hour and the evaporation rate did not seem to be very high, so I left it to do something else for about 2 hours, and then the acid got boiled off, it was all dry when I got out again
Good experience
It was a little as 350W I used on the hotplate, but this in fact seems like too much. The first lessons comes forward
But I just poured in some fresh HCl and let it stand COLD for 4 hours more. But nothing major happened. The foils have not been separated from the pin, but the solution has a deep green colour, so it seems like most of the pins were copper-based, because this copper has cemented onto just about all of the pins.. I read that this could happen in this very post if it was both kovar based pins, and copper based pins. Facinating.
So.. Should I add some more HCl and also a little H2O2 to this solution and just dissolve everything beside the gold, filter it and proceed with a HCl wash and then AR? Im also going to test it after filtering, with stannous obviously.
I can't think of a better way to clean this up, but that is why I ask if anyone else have some tips? Especially you Sam that is the author of this guide
Thanks