Thermally conductive, electrical insulating material? 1

[KevinH673]

I'm interested if there is a material I can use in a 1/2" thick piece I have, that will dissipate heat (it is up against a cold plate), yet will electrically insulate. Can anyone recommend anything?

Am I better off posting in the composite forum? I found a polymer composite with boron nitride coated carbon flakes, but this requires a mold. This piece must be tapped for bolts! I have attached a picture of the part, and where it is mounted, if this helps...

Thank you all.
-Kevin

 

[blueandwhiteg3]

I'd look at aluminum nitride, excellent for precisely your needs. It is far, far better than most of the coatings proposed - no risk of wearing off, amazingly thermally conductive, etc.

Here's one supplier, I have never dealt with them, but the data is presented very up-front and is a good example at least:

http://www.aluminumnitride.com/

Another good example:

http://www.ceradyne.com/uploads/Aluminum_Nitride_data_sheet_10-03_4.pdf

The thermal conductivity can be only maybe 10-15% lower than aluminum, yet it is a very good insulator, better than most glass and rubber in most cases. Up to 10^15 ohm-cm. You could even have pieces custom hot pressed, albeit at a cost.

Another great option is silicon carbide. It won't usually hit the same thermal conductivity as aluminum nitride, but it won't be bad (easily to 1/2 that of aluminum or more) and sometimes can match aluminum nitride depending on comparison points. It may be more widely available and/or less expensive. The key downside is that it is not as electrically insulating, so shop carefully.

Here's a nice example:

http://www.ceradyne.com/uploads/Silicon Carbide Data Sheet 10-03.pdf

You could also look at taking a thermally conductive metal and coating it with something. This has already been suggested, I am thinking more like a plating than a coating almost. Imagine if you took copper and plated it with aluminum nitride. This would be more complicated and might have other issues, but it would yield slightly better thermal conductivity.

If that is not sufficient for your needs, you could always move up to beryllium oxide (lighter, a bit more thermally conductive) although that is NASTY stuff to work with - insanely expensive, highly harmful if inhaled.