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Stimmy

Pure Gallium instead of liquid metal thermal compound

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Posted · Original PosterOP

Hi guys,

while surfing around on the web, I found out that pure gallium has a much higher thermal conductivity than the usual Galinstan liquid metal which contains gallium, indium, and tin.

Galinstan has a thermal conductivity of 16.5 W/mK, pure gallium has 40.6 W/mK. It's also quite easy to apply, since it has a melting point of 30 °C and wets the surfaces just like liquid metal. If chip and IHS/heatsink are slighty pre-warmed, it can be applied lust like liquid metal.

The only obvious disadvantage is that one has to warm the heatsink up to >30°C before one can remove it again.

Also, the gallium melts and solidifies regularly during everyday use. This may put thermal expansion stress on the chip, and as an unlikely worst-case scenario might even crack it.

I can also imagine that the liquid metal layer is so extremely thin that a higher thermal conductivity reduces the temps only by a neglible amount.

 

Does anyone have experience with gallium as a thermal compound, or know a reason while using it would be a bad idea?

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I would think that if it were a good idea, the chemical engineers that make up the thermal paste would have thought of it and said.. HEY.. :lightbulb: goes off... 


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10 minutes ago, Stimmy said:

Galinstan has a thermal conductivity of 16.5 W/mK, pure gallium has 40.6 W/mK. It's also quite easy to apply, since it has a melting point of 30 °C and wets the surfaces just like liquid metal. If chip and IHS/heatsink are slighty pre-warmed, it can be applied lust like liquid metal.

The only obvious disadvantage is that one has to warm the heatsink up to >30°C before one can remove it again.

Also, the gallium melts and solidifies regularly during everyday use. This may put thermal expansion stress on the chip, and as an unlikely worst-case scenario might even crack it.

Not familiar, but the reasons you mentioned above sounds like enough for it to be a bad idea.

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Posted · Original PosterOP

Thanks for the answers!

I've looked around a bit more, and found out that some liquid metal thermal compounds have a significantly higher thermal conductivity than Galinstan.

According to the manufacturer, "Coollaboratory Liquid Pro" has a thermal conductivity of 80 W/mK, which would be two times as much as pure gallium.

This thermal conductivity might even surpass that of the solder alloys for soldered CPUs (not really sure about this).

As stated in the MSDS, Coollaboratory Liquid Pro contains silver, which may explain the higher thermal conductivity.

 

So, using pure gallium would be quite pointless.

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7 hours ago, Stimmy said:

Hi guys,

while surfing around on the web, I found out that pure gallium has a much higher thermal conductivity than the usual Galinstan liquid metal which contains gallium, indium, and tin.

Galinstan has a thermal conductivity of 16.5 W/mK, pure gallium has 40.6 W/mK. It's also quite easy to apply, since it has a melting point of 30 °C and wets the surfaces just like liquid metal. If chip and IHS/heatsink are slighty pre-warmed, it can be applied lust like liquid metal.

The only obvious disadvantage is that one has to warm the heatsink up to >30°C before one can remove it again.

Also, the gallium melts and solidifies regularly during everyday use. This may put thermal expansion stress on the chip, and as an unlikely worst-case scenario might even crack it.

I can also imagine that the liquid metal layer is so extremely thin that a higher thermal conductivity reduces the temps only by a neglible amount.

 

Does anyone have experience with gallium as a thermal compound, or know a reason while using it would be a bad idea?

Hi, I am currently studying chemistry at university in italy so i know something (not all bare in mind :) )

Pure Gallium is very corrosive against other metals. It attacks other metal (like aluminum or steel) diffusing into them and making their structure very fragile. The die is made by a mixture of silicon and copper (if i am not wrong) and the IHS is made of metal. So if it doesn't attack the die, it is going to attack the IHS.

Pure gallium also tend to stain other surfaces making it difficult to clean up.

Pure gallium also changes a lot his physical properties and are very strongly dependent on his temperature. His thermal expansion will change a lot depending on the temperature. For example gallium tends to expand by 3% when changes phases (when heated) so i think it will press against the IHS and the die maybe causing some damage to the chip.

On the contrary gallium compounds have different features that allows them to be used as the "liquid metal" that we all know. Plus they add some sort of stabilizer to prevent the gallium compound from reacting with your component. The manifacturer i am sure tried many recipe for making the best thermal interface material that is safe for your other component and it is stable

 

This is what i think about it and probably isn't 100% correct but it is accurate enough (And sorry if my english is bad)

 

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On 9/17/2018 at 8:12 AM, Stimmy said:

Hi guys,

while surfing around on the web, I found out that pure gallium has a much higher thermal conductivity than the usual Galinstan liquid metal which contains gallium, indium, and tin.

Galinstan has a thermal conductivity of 16.5 W/mK, pure gallium has 40.6 W/mK. It's also quite easy to apply, since it has a melting point of 30 °C and wets the surfaces just like liquid metal. If chip and IHS/heatsink are slighty pre-warmed, it can be applied lust like liquid metal.

The only obvious disadvantage is that one has to warm the heatsink up to >30°C before one can remove it again.

Also, the gallium melts and solidifies regularly during everyday use. This may put thermal expansion stress on the chip, and as an unlikely worst-case scenario might even crack it.

I can also imagine that the liquid metal layer is so extremely thin that a higher thermal conductivity reduces the temps only by a neglible amount.

 

Does anyone have experience with gallium as a thermal compound, or know a reason while using it would be a bad idea?

I was just checking that out myself, and there's a lot of information available and a lot of testing going on. I need someone to translate some of the information for me... I understand the basics but this is PhD level science and physics... I found a lot of people, companies investing serious money into research to use gallium derivatives as a viable cooling solution.  

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On 9/17/2018 at 3:48 PM, 98ChemisT said:

Hi, I am currently studying chemistry at university in italy so i know something (not all bare in mind :) )

Pure Gallium is very corrosive against other metals. It attacks other metal (like aluminum or steel) diffusing into them and making their structure very fragile. The die is made by a mixture of silicon and copper (if i am not wrong) and the IHS is made of metal. So if it doesn't attack the die, it is going to attack the IHS.

Pure gallium also tend to stain other surfaces making it difficult to clean up.

Pure gallium also changes a lot his physical properties and are very strongly dependent on his temperature. His thermal expansion will change a lot depending on the temperature. For example gallium tends to expand by 3% when changes phases (when heated) so i think it will press against the IHS and the die maybe causing some damage to the chip.

On the contrary gallium compounds have different features that allows them to be used as the "liquid metal" that we all know. Plus they add some sort of stabilizer to prevent the gallium compound from reacting with your component. The manifacturer i am sure tried many recipe for making the best thermal interface material that is safe for your other component and it is stable

 

This is what i think about it and probably isn't 100% correct but it is accurate enough (And sorry if my english is bad)

 

 

2 hours ago, gerard1021 said:

I was just checking that out myself, and there's a lot of information available and a lot of testing going on. I need someone to translate some of the information for me... I understand the basics but this is PhD level science and physics... I found a lot of people, companies investing serious money into research to use gallium derivatives as a viable cooling solution.  

 

On 9/17/2018 at 7:41 AM, Stimmy said:

Thanks for the answers!

I've looked around a bit more, and found out that some liquid metal thermal compounds have a significantly higher thermal conductivity than Galinstan.

According to the manufacturer, "Coollaboratory Liquid Pro" has a thermal conductivity of 80 W/mK, which would be two times as much as pure gallium.

This thermal conductivity might even surpass that of the solder alloys for soldered CPUs (not really sure about this).

As stated in the MSDS, Coollaboratory Liquid Pro contains silver, which may explain the higher thermal conductivity.

 

So, using pure gallium would be quite pointless.

Gallium when mixed with the other metals prevents them from entering their normal 'solid' state at given temperatures and mixtures. there are different mixtures out there, some with gallium, and some without.

 

no matter how much stuff you mix in doesn't change the nature of the metal as mentioned by @98ChemisT its just making the best possible situation that can apply to a larger range of 'use'

also  the rating of 73w/mK and others makign outrageous claims, not sure how this can be so, i read a few 'studies on liquid metal tims' and  they are more along the lines of 15-20 W/mK  not sure how the companys come up with the other numbers (we should be running ambient or near to it if they can shed that much heat)

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On 9/17/2018 at 3:12 PM, Stimmy said:

Hi guys,

while surfing around on the web, I found out that pure gallium has a much higher thermal conductivity than the usual Galinstan liquid metal which contains gallium, indium, and tin.

Galinstan has a thermal conductivity of 16.5 W/mK, pure gallium has 40.6 W/mK. It's also quite easy to apply, since it has a melting point of 30 °C and wets the surfaces just like liquid metal. If chip and IHS/heatsink are slighty pre-warmed, it can be applied lust like liquid metal.

The only obvious disadvantage is that one has to warm the heatsink up to >30°C before one can remove it again.

Also, the gallium melts and solidifies regularly during everyday use. This may put thermal expansion stress on the chip, and as an unlikely worst-case scenario might even crack it.

I can also imagine that the liquid metal layer is so extremely thin that a higher thermal conductivity reduces the temps only by a neglible amount.

 

Does anyone have experience with gallium as a thermal compound, or know a reason while using it would be a bad idea?

Yes, I've tried it! It's not hard to do. Obviously the gallium needs to have been melted, but you will also need to heat the CPU first. Not hard, just boot to BIOS with no cooler fitted and it will get hot enough quite quickly. Remove the CPU before applying, of course - you don't want to be fishing around inside the case with a conductive molten metal.

The results were dissapointing ... exactly the same temps as a galinstan-based TIM. Not sure why. But as it's about 50 times cheaper, go for it. You also get to play with gallium, which is fun. I wouldn't worry about the freeze-thaw cycle hurting the chip. Gallium will actually remain liquid *way* below its melting/freezing point if it is under pressure, which of course it is when you fit a cooler. When I removed the cooler (at room temperature) mine was liquid and it stayed liquid for quite a while.

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On 9/17/2018 at 11:48 PM, 98ChemisT said:

Hi, I am currently studying chemistry at university in italy so i know something (not all bare in mind :) )

Pure Gallium is very corrosive against other metals. It attacks other metal (like aluminum or steel) diffusing into them and making their structure very fragile. The die is made by a mixture of silicon and copper (if i am not wrong) and the IHS is made of metal. So if it doesn't attack the die, it is going to attack the IHS.

Pure gallium also tend to stain other surfaces making it difficult to clean up.

Pure gallium also changes a lot his physical properties and are very strongly dependent on his temperature. His thermal expansion will change a lot depending on the temperature. For example gallium tends to expand by 3% when changes phases (when heated) so i think it will press against the IHS and the die maybe causing some damage to the chip.

On the contrary gallium compounds have different features that allows them to be used as the "liquid metal" that we all know. Plus they add some sort of stabilizer to prevent the gallium compound from reacting with your component. The manifacturer i am sure tried many recipe for making the best thermal interface material that is safe for your other component and it is stable

 

This is what i think about it and probably isn't 100% correct but it is accurate enough (And sorry if my english is bad)

 

Gallium is still corrosive when it is part of an alloy. Pure gallium isn't significantly more corrosive than the gallium alloys used in metal TIMs. It won't destroy your IHS though. Gallium alloys with the copper, but the Ga/Cu alloy layer never gets more than a few hundred atoms thick. And it doesn't react with silicon at all.

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On 9/17/2018 at 3:41 PM, Stimmy said:

Thanks for the answers!

I've looked around a bit more, and found out that some liquid metal thermal compounds have a significantly higher thermal conductivity than Galinstan.

According to the manufacturer, "Coollaboratory Liquid Pro" has a thermal conductivity of 80 W/mK, which would be two times as much as pure gallium.

This thermal conductivity might even surpass that of the solder alloys for soldered CPUs (not really sure about this).

As stated in the MSDS, Coollaboratory Liquid Pro contains silver, which may explain the higher thermal conductivity.

 

So, using pure gallium would be quite pointless.

The thermal conductivity claims of metal TIM manufacturers are absolute and utter lies. When you alloy two metals, the thermal conductivity is always much lower than the the thermal conductivity of either constituent. It is physically impossible for an alloy of indium and gallium to have a thermal conductivity even close to that of pure gallium, unless the proportion of indium is huge - in which case the alloy would not be a liquid anywhere near room temperature.

 

Addition of silver (or any other high thermal conductivity metal) can only reduce thermal conductivity further. For the addition of silver to increase thermal conductivity, it would need to make up about 50% of the alloy. Such an alloy would have a melting point of around 500 degrees Celsius (search for "Ag Ga phase diagram").

 

Manufacturers can get away with claiming whatever the hell they like about the physical properties of their products, because nobody has the time, energy, money or motivation to take them to court over it.

 

Eutectic gallium/indium (known as eGaIn) performs identically to Coollaboratory's and Thermal Grizzly's products (I've made it, and I've tested it extensively - it actually marginally outperforms both - presumably because it doesn't contain any tin). Its thermal conductivity is 24.9 W⋅m. K1. That's as good as it gets.

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