Dealing with Indium in CPUs

[Uciocciu]

Hi guys,

As many of you know, there is some indium in many types of CPU.

Could someone tell me wether it is pure indium or not ?

If not, is it an alloy ?
and what would be the process to refine it ?

Thank you in advance and kind regards from my beautiful island of Corsica

U ciocciu

 

[Lino1406]

You may mean iridium?

 

[snoman701]

No, he means indium.

I’d expect that Iridium would be pretty rare in electronics.


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[Lino1406]

Notice Iridium windows are widely used now in fabrication of IC's

 

[anachronism]

I'm pretty sure that he means Indium. That's commonly used in things like processor lids.

 

[g_axelsson]

Notice Iridium windows are widely used now in fabrication of IC's

Lino, what is the source for that picture? GaAs is commonly used for infrared cameras and detectors so I suspect that the "Ir Window" actually means "IR Window".

I think that the indium used to solder the heat spreader to the back of the die on many modern CPU:s are quite pure before soldering. Afterwards it is contaminated by some gold at least.

Doing some digging I found this article... "The material optimization and reliability characterization of an indium-solder thermal interface material for CPU packaging" https://www.semanticscholar.org/paper/The-material-optimization-and-reliability-of-an-for-Deppisch-Fitzgerald/40fe11ccc30fcdac3d2c38cb65b42f112f040558
In it there is this diagram :

Which actually shows the gold plating on the lids to be as good as gold fingers. Some of the gold is diffused into the indium solder over time so it will end up as a sludge if you dissolve the indium in hydrochloric acid for example.

I usually use the heat spreaders as a copper source in my stock pot, that way the foils ends up with the rest of my gold in the end. :mrgreen:

Göran

 

[Lino1406]

From what I know, Ir oxide or silicide has indeed an IR range, so it may be a kind of a filter. Indium has of course another role I assume replacing Al. Try this thread (?)
https://www.sciencedirect.com/topics/engineering/surface-recombination-velocity