Rings on CPU pins

[Marcel]

I took some ceramic Pentium CPUs from Intel AND AMD.
Let them dissolve the attachted pins until they floated around, hollow.
Washed them with HCl and water.
Took them to HCl/Cl bath and the process started, then suddently stopped.
I took the solids out and noticed some white rings in the solution. They came from the pins and were attached to them were the pins enter the CPU housing, like a O-ring.
Tried to dissolve them with HCl - no success.
Took some and heated them with the torch. The gold melted, but not those O-rings.
Now they have a silver color.
Anyone knows, what these rings are made of?
Metal or non-metal? How can I get rid of them or seperate them from the goldfoils. They seem to have disturbed the HCl leach.
I even saw them disolving in HCl/Cl. they were running around releasing gas and fizzling.
Stannous test indicated: No gold in solution but also no other color

 

[Sucho]

Marcel

Those rings are made of silver chloride from silver solder used for attaching pins...

 

[glondor]

I grind them with a mortar and pestle then redo in A/R. Yield for au is good. Very much worth doing. AMD leaves more rings than intel.

 

[Marcel]

I grind them with a mortar and pestle then redo in A/R. Yield for au is good. Very much worth doing. AMD leaves more rings than intel.

So you dont seperate them from the gold before AR?

Thank you for the answers anyway.

 

[pgm]

interesting you learn something new everyday

 

[glondor]

Hey Marcel. They are usually left over in the fines after A/R if the A/R is a bit weak or not enough time/heat is used. Sometimes they are there and sometimes not. They are the base of the pins where the pin attaches to the ceramic base.

They are very small, 2 - 3 mm at most with a small hole in the middle where the pin was before dissolution. Usually grey white in color.

After the chopped up cpu's have dried I run them through an appropriate sized sifting device to recover all the fines. I grind with mortar and pestle and process as usual. The best effort is to dissolve on the first A/R evolution and avoid the Issue. But as stated, sometimes they are there and sometimes they are not.

AMD seems more prone to this issue, perhaps due to the fact they contain more iron.

 

[Marcel]

For those, who don´t know what they look like:
Here is a picture, the ring of silverchlorid is still attachted to the pin, which is a foil after a bath in AP.

Later these ring deattach.

 

[glondor]

After A/R they are much smaller.