Green/black/brown fiber CPUs and aqua regia

[VanMarco]

Hello!
I've read on the forum and on the website of samuel-a that putting tin with aqua regia is not a great idea. I am asking why is that.
To proove about what would cause tin in solution, i've dropped 5 grams of tin soldering wire to aqua regia, all it did was dissolving the tin and form
a white precipitate. I don't see what this precipitate would cause of so terrible to avoid it at all costs. Processing green/black/brown fiber pins in aqua
regia would be tremendosly faster so.

Any thoughts?

 

[jimdoc]

Hello!
I've read on the forum and on the website of samuel-a that putting tin with aqua regia is not a great idea. I am asking why is that.
To proove about what would cause tin in solution, i've dropped 5 grams of tin soldering wire to aqua regia, all it did was dissolving the tin and form
a white precipitate. I don't see what this precipitate would cause of so terrible to avoid it at all costs. Processing green/black/brown fiber pins in aqua
regia would be tremendosly faster so.

Any thoughts?

You will find out eventually. There are reasons for all the tin warnings. If it was easier and faster with no consequences, then there would be no warnings about tin in your batches.
It has been discussed before if you use the search box for the technical reasons.

Here is a hint;
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=17650

Jim

 

[VanMarco]

Thanks. I've been reading alot of forum post I asked that as I've read in the forum that black fibers are made just like ceramic ones, so indeed tin will end up in aqua regia. That is why I asked

 

[g_axelsson]

Processing fiber processors in aqua regia is a bad idea because the way they are constructed. The gold and base metals will dissolve but not all as some are protected by the pcb (printed circuit board).
Some gold could start to cement onto the remaining base metals inside the pcb.

I made the mistake of putting a couple of fiber processors with some ceramic ones and processed them with the modified aqua regia process. In the end I got distracted by life... a year later I started to clean up all the jars I had standing outside but the yield were less than I expected. I then examined the leftovers, on the fiber processors there were some brown accretions and then it struck me... cementation. I checked it under the microscope and there it was, the gold had cemented onto the fiber processors.
I will incinerate the rest of the fiber processors as I suspect that there are some gold inside the board too.

There are more than one type of fiber processor. The ones with the die inside a cavity in the board and covered in epoxy got some gold bond wires between the pcb and the die. The ones with a flip chip, die mounted on top without any epoxy, doesn't contain any gold except for the pins.

Göran

 

[Alentia]

Hello!
I've read on the forum and on the website of samuel-a that putting tin with aqua regia is not a great idea. I am asking why is that.
To proove about what would cause tin in solution, i've dropped 5 grams of tin soldering wire to aqua regia, all it did was dissolving the tin and form
a white precipitate. I don't see what this precipitate would cause of so terrible to avoid it at all costs. Processing green/black/brown fiber pins in aqua
regia would be tremendosly faster so.

Any thoughts?

You saw what you saw because you had free HNO3 in your AR. When, there is free HCl and AuClx the effect will be different. I would not even process pins from green fiber. It is waste of time, effort and chemicals. Pins from brown fibers and Black fibers required different processing methods due to different compositions of pins.