Thermal compound: vaseline/lube/lotion

[Valkerie]

For chemistry majors out there, would vaseline, lube, lotion, toothpaste, or any rubby substances work for a good thermal compound?
Has anyone tried it before...?

I'd like to know, thanks.

 

[racolvin]

I dunno about chemistry majors but...

vaseline = bad idea. Petroleum product put under pressure and then having heat applied? Bad idea IMHO
lotions, toothpaste,etc could all break down at those temperatures and actually provide insulating properties instead of conductive properties. I certainly dunno the chemistry but for the whole $5 a tube of AS5 would cost, I wouldn't be taking the chance of experimenting

 

[Capt Caveman]

No, b/c they would burn out their cpu. None of the products you listed are thermal compounds.

 

[kleinwl]

The whole point of a thermal compound is the thermal conductivity. Ie how easily "heat" (thermal energy) "flows" (is transfered) through the material. You add a thermal compound to the top of a cpu to fill in the microscopic voids in the metal to metal contact (cpu to heat exchanger). By doing this, you increase the surface are that the "heat" can "flow" across... thus increasing the thermal efficency (ie. the ability of your heat exchanger to cool the CPU). If you use a poor thermal compound (something that has a lower thermal conductivity) your heat exchanger will be less effective, increasing the temperature of our CPU. In this case, you would be better off with no compound at all.

 

[Operandi]

haha

 

[imported_whatever]

Originally posted by: Operandi
haha

huh, i remember seeing something like that where the non-thermal pastes worked decently

 

[Operandi]

Hmmm..... Vegemite?

 

[CycloWizard]

Originally posted by: kleinwl
The whole point of a thermal compound is the thermal conductivity. Ie how easily "heat" (thermal energy) "flows" (is transfered) through the material. You add a thermal compound to the top of a cpu to fill in the microscopic voids in the metal to metal contact (cpu to heat exchanger). By doing this, you increase the surface are that the "heat" can "flow" across... thus increasing the thermal efficency (ie. the ability of your heat exchanger to cool the CPU). If you use a poor thermal compound (something that has a lower thermal conductivity) your heat exchanger will be less effective, increasing the temperature of our CPU. In this case, you would be better off with no compound at all.

:thumbsup:

Very nice explanation.

 

[Zepper]

No, thermal compound is mainly to eleiminate dead air pockets between the device and the heatsink. Very little heat is transferred by conduction - almost all is transferred by radiation which dead air tends to block. None of the items listed will hold up under any heat at all. The cheap little tube of white HS grease from RadioSchlock (part no. 276-1372A) would do better than any of those.
. Although someone did do a test with toothpaste (might be dansdata.com) and it did hold up for a while - but toothpaste contains water and glycerine. Water will quickly evaporate from the heat leaving tiny dead-air pockets and glycerine will not hold up to the heat either and will drain to the low side leaving yet more air pockets.

.bh.

 

[CycloWizard]

Originally posted by: Zepper
No, thermal compound is mainly to eleiminate dead air pockets between the device and the heatsink. Very little heat is transferred by conduction - almost all is transferred by radiation which dead air tends to block. None of the items listed will hold up under any heat at all. The cheap little tube of white HS grease from RadioSchlock (part no. 276-1372A) would do better than any of those.
. Although someone did do a test with toothpaste (might be dansdata.com) and it did hold up for a while - but toothpaste contains water and glycerine. Water will quickly evaporate from the heat leaving tiny dead-air pockets and glycerine will not hold up to the heat either and will drain to the low side leaving yet more air pockets.

Actually, the reason for the need to eliminate air pockets is because air has a very low thermal conductivity. If one were to rely on radiation, one would need to leave a complete void between the two surfaces, or at least fill the gap with a material that is transparent to the wavelengths of radiation of interest. Conduction is the only mechanism for heat transfer from core to heat sink.

 

[ericlala]

Originally posted by: CycloWizard

Originally posted by: Zepper
No, thermal compound is mainly to eleiminate dead air pockets between the device and the heatsink. Very little heat is transferred by conduction - almost all is transferred by radiation which dead air tends to block. None of the items listed will hold up under any heat at all. The cheap little tube of white HS grease from RadioSchlock (part no. 276-1372A) would do better than any of those.
. Although someone did do a test with toothpaste (might be dansdata.com) and it did hold up for a while - but toothpaste contains water and glycerine. Water will quickly evaporate from the heat leaving tiny dead-air pockets and glycerine will not hold up to the heat either and will drain to the low side leaving yet more air pockets.

Actually, the reason for the need to eliminate air pockets is because air has a very low thermal conductivity. If one were to rely on radiation, one would need to leave a complete void between the two surfaces, or at least fill the gap with a material that is transparent to the wavelengths of radiation of interest. Conduction is the only mechanism for heat transfer from core to heat sink.

having air = convection

 

[CycloWizard]

Originally posted by: ericlala
having air = convection

Ummmmmmmmm... No? Convection is the mechanism of heat transfer driven by bulk motion. In this sense, small air pockets are enclosed, thus must rely on natural (free) convection. Due to the size of the pockets, the thermal gradients within are completely negligible, resulting in no noteworthy free convection.

Now, to remove the heat once it reaches the heat sink, you most definitely rely on convection. Forced (induced) convection is brought about by the fan forcing air past the heat transfer surface. The faster the air is moving, the more heat it can take away and the lower your temperature will be.

 

[0roo0roo]

http://www.dansdata.com/goop.htm

 

[SVT Cobra]

Originally posted by: whatever

Originally posted by: Operandi
haha

huh, i remember seeing something like that where the non-thermal pastes worked decently

LMFAO that is one of the best article's i have ever seen!

 

[drpootums]

Go to SVC.com (i think that's the site) and buy a $4 tube of AS Ceramic with free shipping and get it in 3 days...

Why save like $3 when you could ruin your equipment?

 

[coomar]

thermal conductivity of air is roughly 0.00026 W/cmK, our conductive metals rock in around 4. for copper and 2.37 for aluminum so we're looking at a difference of about 15000 time, I remember that artic silver is about 50-100 times less conductive than metals, that still a hell of lot better than air