Several Random E-Scrap Processing Questions for the More Experienced...

[AuggieDog]

First...How much Sn is too much when using AR to digest e-scrap? Another words, if I am digesting 150g of top hat transistors and there is solder residue on the majority of the legs, (that is a tiny amount) am I going to run into trouble with the formation of metastannic acid? Is there a rule of thumb? Or does it have to be NO Sn whatsoever...?

If I am processing large amounts of ceramic IC's with silicon dies mounted on gold solder (is this solder?), does this solder contain Sn...?

If I am processing large amounts of IC's with gold solder but aluminum bonding wires, are there any issues with the Al reacting with AR...?

Finally, if I was to pulverize ceramic IC's to near dust, will it react with HNO3, HCL, or AR...? Is there any risk of contamination or dissolution of the ceramic components?

Thank you!

 

[Yggdrasil]

First...How much Sn is too much when using AR to digest e-scrap? Another words, if I am digesting 150g of top hat transistors and there is solder residue on the majority of the legs, (that is a tiny amount) am I going to run into trouble with the formation of metastannic acid? Is there a rule of thumb? Or does it have to be NO Sn whatsoever...?

If I am processing large amounts of ceramic IC's with silicon dies mounted on gold solder (is this solder?), does this solder contain Sn...?

If I am processing large amounts of IC's with gold solder but aluminum bonding wires, are there any issues with the Al reacting with AR...?

Finally, if I was to pulverize ceramic IC's to near dust, will it react with HNO3, HCL, or AR...? Is there any risk of contamination or dissolution of the ceramic components?

Thank you!

I do not think there is a threshold for this it is just an increasing nuisance.
Removing as much Tin as practical with HCl is the best way for this I believe.

The ceramic ICs with Gold Solder, the Solder may be better described as brazing maybe?
So there may or may not be Tin in it. Test one.
Al is passified by Nitric and dissolved in HCl. so there should not be a big deal.
I can see no reason to pulverize the ceramic, noting in there.

 

[ólom]

Metastannic acid is not produced in AR, but if you only use nitric acid, metastannic acid is produced, which you can dissolve with sulfuric acid, that is, you can put it in suspension.

 

[GoIdman]

First...How much Sn is too much when using AR to digest e-scrap? Another words, if I am digesting 150g of top hat transistors and there is solder residue on the majority of the legs, (that is a tiny amount) am I going to run into trouble with the formation of metastannic acid? Is there a rule of thumb? Or does it have to be NO Sn whatsoever...?

If I am processing large amounts of ceramic IC's with silicon dies mounted on gold solder (is this solder?), does this solder contain Sn...?

If I am processing large amounts of IC's with gold solder but aluminum bonding wires, are there any issues with the Al reacting with AR...?

Finally, if I was to pulverize ceramic IC's to near dust, will it react with HNO3, HCL, or AR...? Is there any risk of contamination or dissolution of the ceramic components?

Thank you!

I would cut off the soldered legs and process those separately if you do not apply the HCl method to dissolve the tin.....but old gold cap transistors or IC were soldered with mostly lead solder combined with tin to be soft and flexible.....todays ROHS solders break like glass and make bad joints in time...

Pulverizing ceramic IC is mostly not feasable, there is nothing inside which is PM, you just waste your time with it...

Search the forum how to recover gold from ceramic IC`s...CPU`s

Pete