fiber CPU heat spreaders.

[danieldavies]

hello.i just want to say this forum has give me a lot of information but i couldn't find anything on gold plated heat spreaders. they are made of solid copper plated with nickel then gold with a blob of solder on the gold plating. does anyone know a good process to recover the gold plating. i was thinking a soak in hydrochloric acid to remove the solder then put them in sulfuric to remover the nickel and gold plating. what do you think members? thanks

 

[necromancer]

what type of cpu did that come off ??

 

[danieldavies]

intel xeon. i got hundreds.

 

[necromancer]

personally i dont think thats gold on the spredder

 

[danieldavies]

i put a drop of nitric acid on it and no reaction.

 

[Geo]

it is gold. its very little, but gold is gold. process in stripping cell when you run your next batch.

 

[danieldavies]

thanks geo. how many micro inches would you say the plating is?

 

[Geo]

unsure, but it is really thin. still enough to process though.

 

[chlaurite]

Just as a aside, have you confirmed that blob of "solder" as tin/lead and not something designed to become liquid at normal CPU temps? Those tend to contain all sorts of goodies, particularly silver, indium, and gallium.

Drop it in a pot of boiling water and see if it melts. If it does, it may have more dollar value in its metals than that pretty gold distraction. 8)

 

[g_axelsson]

The solder seems to be indium, haven't made an exact assay of how pure but it's really soft, easily marked with your nail.

The gold (based on a couple of heat spreaders) is decent thickness, it stayed as a cm-long flakes when I forgot to take out some heat spreader from the HCl bath I used to remove the indium. When I had some copper chloride is started to run faster and in no time turned my clear indium chloride into a dark green mess.
The rest of my heat spreaders is going to be part of my first run with the sulfuric cell. The indium chloride is now all contaminated with copper chloride and probably tin chloride too, anyone know how to recover the indium? Not for economic reasons, just for fun. 8)

Göran

 

[necromancer]

hmmmmm

will have to open some of those tomorrow 8)

 

[Geo]

ive put the whole lids in hot hcl trying to remove the solder. it was slow to dissolve. i had no idea what it was composed of. it seemed to be of such small value, i didnt worry about studying them. one thing i did notice is that the hot hcl will remove the tin before it completely removes the solder. it may be the small percentage that soaked up the gold plating when it first melted onto the top. there was a thread where i took some pictures of the tops i was using in my stock pot. each one has a hole, so i would tie a small nylon string on it and hang it off into the pail. they etched into some very pretty shapes. you could see the shapes of the copper crystals. but i digress, thank you Göran for the information.