The ideal thermal transfer material?

[skool h8r]

Hi all,
it's just struck me, since silver is well known for it's good thermal transfer properties, and the base of a heatsink is hardly ever perfectly flat, why not use a few sheets of silver leaf between the CPU and heatsink. You could flatten it into the grain of the surface of the heatsink and then use a couple of other sheets to gently fill out the spaces. It sprung to mind when i was actually padding out my foil cube (i'll tell you about it some other time). When i rubbed it on the desk to try and get a mirror-like finish, i noticed it left a big grey mark, and some of the foil peeled off in extremely thin sheets, like silver leaf. Anyone think this would actually work?

[cadaveca]

it could, but the chance of trapping air between you layers is very great, and might hamper any benefit this might have over using a liquid with silver particles infused in it.

[Samuknow]

Originally Posted by cadaveca

it could, but the chance of trapping air between you layers is very great, and might hamper any benefit this might have over using a liquid with silver particles infused in it.

Same thing I was thinking. It is virtually impossible to get the surface completly flat with a non liquid or fluid like material. Without some highend equipment of course.

If your willing to give it a try and post some results that would be great.

try with AS or the like and then your silver leaf...

[BobRoss]

I think that another part of that problem is the fact that the die itself is not perfectly flat and it is against popular wisdom to lap it flat. But what about a silver heat sync?

[Aedan]

How about just manufacturing the die as part of the heatsink assembly, so that no interface material was needed?

[Samuknow]

Originally Posted by Áedán

How about just manufacturing the die as part of the heatsink assembly, so that no interface material was needed?

I like it.

Maybe a few with some water blocks made in also....

[BobRoss]

They could make little capillaries in between the transistors with carbon nanotubes.

[Samuknow]

Originally Posted by BobRoss

They could make little capillaries in between the transistors with carbon nanotubes.

I think that is being done...

There is a thread here somewhere....

[BobRoss]

I read that they were going to use the tubes for the electricity though not for cooling but that they expect them to run cooler.

[QSDT]

Don't know where I read it but about a year ago found a story about a guy who use silver leaf folded it over about 6 times I think and his temps dropped 6 to 8c. Was always going to try it but still on the to do list. Give it ago and he said that you need cotton gloves to touch the stuff.

[keithwalton]

Silver is very good in terms of thermal conductivity and i believe it used to be used in some form or other in P2/P3 heatsinks as a thermal pad. However silver is way to soft to be generally usefull as anything but a TIM

[Kaitain]

The best TIM is the thinnest one you can get with the highest combination - the engineers in here will be familiar with Fourier's Law: Q=kAdT/x where Q is the heat flux, k is the thermal conductivity, dT is the temperature difference and x is the thickness of the TIM.

Rearranging this to be dT = xQ/kA and assuming the following (to make the maths easier) - CPU output is 100W, thickness of TIM is 0.1mm, conductivity is 400 W/m2C and area is 1cm2

dT = 0.0001 * 100 / (400 * 0.0001) = 0.25C

Making a thinner, more conductive TIM can reduce the heat retained in your CPU by whole hundredths of a degree Celsius!!!

But seriously, the overall temperature your CPU ends up at is dependent on the greatest resistance to heat flow - and that is and always has been getting the heat out of the heatsink and into the air. Provided the TIM is applied properly and excludes air correctly, then altering its properties will have only a negligible difference in the temperature of your CPU. The ground-work of cleaning, lapping and using a fluid TIM all ensure that you've excluded air from the system more than anything else...