artic alumina/silver 5 question for thermal transfer question

ok, i have just spent about 20 minutes searching through the forums as to which artic thermal compound to use between a heatsink and mag host for best thermal transfer, i believe that i have my question answered but i am still a little confused and just wanted to be sure before i place an order.

the closest thread i could find to answer my question was this one http://www.candlepowerforums.com/vb...-differences&p=1312511&viewfull=1#post1312511

Want to enhance thermal conductivity but don't care about electrical isolation? (as in enhancing thermal path of an o-sink in a MagD mod) Use the Artic Alumina thermal compound.

Click to expand...

honestly i think what is confusing me, is all the vendors on amazon - they seem to list their compounds like this "Artic Silver 5 Alumina Epoxy Grease Adhesive Non-Conductive" so it turns up in all the searches

just to confirm i have these three links for artic silver grease:


http://www.amazon.com/dp/B004Z9XG0I/?tag=cpf0b6-20

http://www.amazon.com/dp/B0002VFXFE/?tag=cpf0b6-20

http://www.amazon.com/dp/B001JYVFLY/?tag=cpf0b6-20

I think the first link is the correct one?

Thanks in advance for any help

There are two different types of product that they sell; paste and epoxy. The epoxy is a two part permanent adhesive that transfers heat, and the paste just transfers heat. Paste will transfer heat a little better than epoxy. Arctic Silver 5 also transfers heat better than Arctic Alumina, but it conducts a little bit of electricity. If that's not a concern, the Arctic Silver 5 paste will conduct the heat the best. However, the advantage over Arctic Alumina is marginal, and many prefer Arctic Alumina because it is cheaper.

Remember, the inside of the battery tube is anodized. This and also the heatsink you're using may also be anodized. I really wouldn't worry about it. Arctic silver 5 is mildly conductive if I remember correctly. This is because it has silver it it. If you're really worried about shorting something, then use a none silver based thermal paste/epoxy. They will work fine.

thanks :rock:

Technically, the second two links (for Arctic Silver 5 thermal compound) have superior thermal conductivity vs the first link (Arctic Alumina compound). See this post for example. You have a series resistance configuration: LED to heat sink, heat sink to Mag tube, Mag tube to ambient.

Thermal resistance is given by bond line thickness/(thermal conductivity * effective contact area).

The LED to heat sink interface is probably limited by effective contact area since the LED slug is typically very small (e.g., a Cree MC-E slug is about 14 mm^2). I'd use the most convenient material that has the highest thermal conductivity. If you can reflow solder the LED to the heat sink, that's the best. Otherwise, I'd probably use Arctic Silver 5 thermal compound (if you have some method to apply constant pressure to the LED to keep it in place) or Arctic Silver thermal adhesive (epoxy). For simplicity, I'd use Arctic Silver epoxy to glue down the LED to the heat sink and be done with it.

I haven't made any example calculations, but the contact area between the heat sink and Mag tube is extremely large compared to the area of an LED slug, so I would expect minimal gain using Arctic Sliver 5 compound vs Arctic Alumina compound. I'd probably just go with Arctic Alumina compound between the heat sink and Mag tube.