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Experiment with Galium(the metal) thermal compound (Read... interesting hehe)

F

Flat

Banned
As you may or may not know the lower the melting tempeture of a element the better heat conductivity, thats why Artic Silver is slighty better than alumminum grease, lower melting temp. So, in this vein of thought, I thought of GALIUM, which has practically the lowest melting temp of any metal (if I am all wrong, sorry History major not chemistry), so my grand idea is to make a thermal "pad" with galium, as it can be easly molded into shapes. I basically formed a small rectangle with the galium and "cut" a small slice of which I then placed upon the die. boot up, run FlightSim 2k max everything, and a wow! a 5 degree drop from artic silver. the worked for about 2 hours, then, tradegy strikes... my system dies, not like power dies or reboots, no the monitor sorta just fades away, and nothing i do will make the computer startup. at this point I notice... some silver-ish stuff right on the edge of my HSF, and that it is around a capacitator and thoose little silver square. My motherboard has been ruined :0 fortunatly the CPU was OK, so lesson dont use anything with a low or realativily low melting temp without some way to contain it.
Idle-31C Galium 35C Silver
Max-37C Galium 42C Silver
 
I may be wrong, but I think gallium is the only metal that is a liquid at room temperature. It will melt in your hand.

edit: melting temp: 29.8 degrees celcius

edit2: reminded about mercury a few posts below. gallium is the only metal that will actually phase change in your hand.
 
MP is 29.78 degrees C, boiling point... 2400C hehe. I think I could have gotten quite a bit better reluts if I had some way of keeping its together... I am probaly going to try a alloy of artic silver EPoxy and galium, or if you have any ideas Mike let me know. Another thing... the viscosity of melted galium is quite high, quite a bit more that say Karo syrup, therefor I should not be to hard to get this stuff to stay put...
 
I suppose if you wanted something permanent, you could try potting the area between the heatsink and the cpu. It would keep the gallium from flowing out. Another thing is that it will expand when it becomes a liquid, creating a better bond between the core and the hsf. You would want to seal in the area around the core so that it doesn't flow out. Maybe this would be where a shim could come in handy.
 
but how would I create such a precise detent? any ideas? and I assume you refering to a copper shim of some sort
 
I'm not sure. I think the potting idea is better than using a shim. I don't know what temps silicon sealant can handle though. What if you created a neoprene shim? Something that would compress and not absorb or allow fluid to flow through it. You create your neoprene shim slightly larger and thicker than the core, use a thin slice of gallium on the core, then put the hsf on top. Like I said, it will expand as it melts, so some of it will flow off the core and be sealed in by the neoprene shim. I guess experimentation will determine what size shim and how much gallium to use.
 
gallium doesn't have the lowest melting point, mercury is a metal but trying to cool your system with that could turn deadly very fast. I think a sealed liquid cooling setup could work though. It would have to be sealed, mercury vapor isn't good for your health. Hmm, i think mercury has a low boiling point too, i wonder if it would boil from the heat off your cpu...
 
You think mercury is bad? I belive its Phosphrous has a MP of 44C, would work well probaly but its extremly reactive, it burns when it comes in contact with water hehehe. theres also palladium which has a high conductivity rating... but it cost $3000 an ounce, as aposed to $606 for platinum 260 for gold and $5 for silver LoL
 
EUREKA! I could bond a copper or silver shim with artic silver epoxy to my hedgehog... that would be "metal" tight and certitnly keep the galium contained over the die!
 
Gallium arsenide is already used in some electronic components, and some computers (albeit not PCs) have used it extensively. In this regard, the Cray-3 springs to mind.

Edit: looking at all the posts once again, I should say something in case someone tries to put mercury in their system. Mercury is extremely conductive, much more tap water (or water from any source that hasn't been deionized). Also, it tends to "dissolve" metals like gold, which are present and important on the motherboard and in chips. So, not only will you get mercury poisioning, you will short out your motherboard and dissolve imporant stuff away as well.
 
Flat you have the HSF to shim seal figured out but you still need to seal the shim to the CPU , might i suggest RED RTV silicone , this stuff is designed with very high temps (automotive exhausts) in mind. also you might wanna make sure your shim (if you buy one) actually fills the gap between your HSF and CPU , cuz as we have seen recently http://www.extremeoverclocking.com/reviews/misc/Copper_Shims_1.html , this isnt always the case , although since you are using a "seal" on both sides of the shim ,this may not be a problem .great idea though , let us know how it works.
 
OK... I plan to seal the edge around to CPU and HSF with that RTV stuff, not acually all together so then I can just cut it apart with an exacto knife if needed.
Alpineranger: I am using elemental Galium
 
Just to clarify something: lower melting point does not equate to higher thermal conductivity. The best known thermal conductor is diamond.
 
If you could come up with some kind of gallium/silver paste, I think you would be sitting on top of a big money maker.
 
is galium eltrically conductive?? if so, more or less than silver? btw, i have the stuff at home and its very fun to play with, it just melts in your hands =)
 
Periodic Table

Lead has a lower thermal conductivity than gallium. Mercury is very low, but you'd probably die of mercury poisoning. 🙂 Titanium is about half that of gallium.
 
This is out of one of my PalmPilot's programs, 'Element', which I have found incredibly usefull...

Mercury
Melting point: 234.28K (-38.87C, -37.966F)
Boiling point: 630K (356.85C, 674.33F)
State (@ 298K): Liquid
Thermal conductivity: 0.0834 [W/(m*degK)]
Electric conductivity: 0.0104 [10^8/(Ohm*m)]
Specific heat: 0.139 [J/(g*degC)]

Gallium
Melting point: 302.9K (28.85C, 83.93F)
Boiling point: 2478K (2204.85C, 4000.73F)
State: Liquid
Thermal conductivity: 0.406
Electric conductivity: 0.0678
Specific heat: 0.37

Silver
Melting point: 1234K
Boiling point: 2436K
State: Solid
Thermal conductivity: 4.29
Electric conductivity: 0.63
Specific heat: 0.235

Copper
Melting point: 1357.6K
Boiling point: 2836K
State: Solid... duh
Thermal conductivity: 4.01
Electric conductivity: 0.596
Specific heat: 0.38

Aluminum
Melting point: 933.25K
Boiling point: 2740K
Thermal conductivity: 2.37
Electric conductivity: 0.377
Specific heat: 0.9

Any other values: Atomic radius, electron configuration, density... etc just ask.
I'm pretty interested in this topic.. a hermetrically sealed mercury system would be both insane for the user and the CPU's temperature
 
Yep galium melts at room temperature. You could probably make it into a paste just like arctic silver.
 
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