Mess with Black fiber CPUs and AP [PICS]

[VanMarco]

Hi!
I guess I have made some mess, but i also guess it is something I could rescue.
After alot of reading on the forum and on the forum's book, I thought well that in order to loosen the pins of the black fiber CPUs, instead of using simple HCl and nothing else, why don't I use AP? And so I did. I've put enough HCl 36% to cover the cpus and when the initial bubbling stopped i've added around a tablespoon of H2O2 3/4%. Left there for three days, then I pulled them out and the pins were loose. A couple had this reddish colour on the pins, and I started to think bad. Then as the solution was still in very good shape I thought well to add other 10 black fiber cpus in it. What happened, well, maybe a mess, maybe it's just how it should've been. Copper CEMENTED on Tin, falling on the bottom of the jar. I thought well. no big deal. Today I pulled the CPUs out as I suspected they were ready yet... and found the horror! the pins are all reddish. I said earlier that I think it could be rescued because also the gold plated area on top was reddish, but the copper washed away. on the pins it's a bit tougher, but it comes off and beneath it appears the gold is still there. My question for you experts, is that sort of things normal, and Did I loose gold in the sense that also GOLD replaced copper? My take is that gold is far less reactive than TIN and it shouldn't have, but still I can't explain why the pins seems to be "copper plated". I have attached some pics. Hope you can help! thanks in advance!

Reddish pins on the CPU

AP solution

Precipitate

 

[Lino1406]

What is tablespoon 3/4% H2O2?
However, the gold, as negligent
as it is, is still there

 

[butcher]

The hydrogen peroxide was way too strong, you dissolved the gold, the gold would later plate out onto copper or cement as black fine powder, as the oxidizer depleted.

Any acid that made it inside the fiber CPU could also plate some gold inside the CPU, the CPU would have to be incinerated crushed or pulled fiber layers apart to retrieve the gold inside

Tin and lead solder will break down in HCl alone.
Copper will not be attacked by HCl alone as long as no oxygen or oxidizers involved.
Gold is not attacked in HCl, and needs strong oxidizer to dissolve the gold, HCl and 3% H2O2 has very little effect on gold but will attack copper.
gold can be dissolved in HCl with a strong oxidizer like 32% H2O2, the strong oxidizer oxidizing not only the gold but also the HCl to form chlorine gas in solution which helps to attack the gold.

At this point using keep using the copper chloride leach but only add the 3% H2O2 when needed, you should get gold powder after you dissolve all of the copper, how many pounds of these chips do you have? if only a few, you may not be able to find the gold, from too small of a batch.

 

[VanMarco]

thanks for your input, I've put some more in another jar with HCl alone and it's working like a charm. I'll be more careful, infact I just used 10 instead of the whole lot because I wasn't sure Thanks again!

 

[VanMarco]

Hy guys..
Weirdly enough, the same effect has happened even with HCl alone. Gold plated surfaces got copper plated. It really never occourred to you?

 

[VanMarco]

luckily they get clean with HNO3!

 

[butcher]

:?:

 

[gold4mike]

Normally you should run AP to completion. If the legs have fallen off, remove the CPU's and let the legs continue to dissolve until they're gone. Your gold will remain.

Process the remainder of the CPU the same way you would ceramic CPU's.