Arctic Silver Alumina vs Silver

[Obi-dad]

The Arctic Silver Alumina thermal adhesive is less expensive than the silver version of their thermal adhesive, anyone know whether it has 'good enough' (yes I know it won't be 'as good') thermal conductivity for our diy LED reef lighting purposes?

Any other reason besides thermal conductivity to use the silver version instead?

[OUCaptain]

The Arctic Silver Alumina thermal adhesive is less expensive than the silver version of their thermal adhesive, anyone know whether it has 'good enough' (yes I know it won't be 'as good') thermal conductivity for our diy LED reef lighting purposes?

Any other reason besides thermal conductivity to use the silver version instead?

I'm sure it will be fine. Computer users use it to transfer heat from the cpu to the heat sink. Most reviews I've seen of popular thermal compounds end up with only a few degree's difference on the cpu. If your LED setup is only a few degrees away from failure, nothing short of active cooling will help.

[Obi-dad]

I will be using active cooling (fans). I just want to make sure that this isn't one those situations where saving dollars impacts led life.

The Premium Silver at newegg lists the thermal conductivity as 'Greater than 7.5W/mK'.

The Alumina version doesn't list the thermal conductivity (either on newegg or the Arctic Silver website).

Any of the engineers have know about the Alumina version's thermal conductivity? Or have used it for LEDs?

[BeanAnimal]

I'm sure it will be fine. Computer users use it to transfer heat from the cpu to the heat sink. Most reviews I've seen of popular thermal compounds end up with only a few degree's difference on the cpu. If your LED setup is only a few degrees away from failure, nothing short of active cooling will help.

That is somewhat misleading...

High output LEDs that are driven at ANY reasonable output depend 100% on proper thermal management. That is they are always "a few degrees" away from failure.

In any case, either compound will work fine. The thermal differences between the two compounds are not important. The AS is easier to work with and remove the paste form (not the epoxy) does get pretty stiff after applied (compared to the silver compound). I would stick with the AS even though it costs more.

[BeanAnimal]

I will be using active cooling (fans). I just want to make sure that this isn't one those situations where saving dollars impacts led life.

The Premium Silver at newegg lists the thermal conductivity as 'Greater than 7.5W/mK'.

The Alumina version doesn't list the thermal conductivity (either on newegg or the Arctic Silver website).

Any of the engineers have know about the Alumina version's thermal conductivity? Or have used it for LEDs?

Arctic Alumina > 4.0 W/mK

http://www.arcticsilver.com/arctic_alumina.htm

[Obi-dad]

Bean, you are speaking about the thermal compound versions, are they much different than the adhesive versions? I had seen the number for the alumina compound but didn't see any numbers for the alumina adhesive.

I am going to be using the adhesive instead of the thermal compound, because I will be using small heatsinks individually instead of a single massive heatsink. I don't need the ability to reposition the led on a heatsink, and the adhesive prevents the need need for drilling and screws - the heatsinks are only 80 cents each. I got this method from terahz, he showed us his build last week, very sweet. With the individual heatsinks you can reposition the led/heatsink assemblies easily.

If the compound thermal conductivity is the same as the adhesive, the thermal conductivities between the silver and alumina are quite different, the silver almost double. Do you think that makes a big difference for our application with fan cooled heatsinks?

I saw a non-scientific experiment on the web where a guy used different thermal compound brands, and also toothpaste and Vegemite - and his heat results were the same for everything, saying that more important than the compound is eliminating the air gap between the device and heatsink. I am just wondering if the silver version is really necessary.