Thermally conductive, electrical insulating material?
Thermally conductive, electrical insulating material?
(OP)
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
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





RE: Thermally conductive, electrical insulating material?
RE: Thermally conductive, electrical insulating material?
RE: Thermally conductive, electrical insulating material?
You can do a websearch: machinable ceramic thermally conductive
resulting in:
http://www.precision-ceramics.co.uk/shapal.htm
supposedly drillable.
TTFN
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RE: Thermally conductive, electrical insulating material?
I believe it will be okay to machine the part from aluminum, and put some kind of coating on it. In this event, the mica sheets may be okay, assuming that a thing sheet of mica will be enough to electrically insulate the piece. I will keep searching though. Thanks again.
RE: Thermally conductive, electrical insulating material?
RE: Thermally conductive, electrical insulating material?
There are some ceramic type coating for Al but at present are very expensive and are limited in size.
http://www.whitfordww.com/design/electrical.html
http://www.enduracoatings.com/prod100_a.asp
Can you come back with your actual requirements as to temperature and dielectric strength
RE: Thermally conductive, electrical insulating material?
I asked the electrical engineer, as far as electrical properties, it is dealing with (estimating) 9 V, 1/2 A, 4~5 W. He did not know the temperature, but the aluminum part is not too hot to touch. Without it, the heat sink on the boards it's attached to get too hot to touch, though (sorry so vague).
Upon further thought, I'm not sure I can use pieces like the mica sheets on the ends, as there are bolts attached to the electrical boards on this piece, and other bolts that attach to the base. The bolts would carry current, unless there is some coating I could spray in the threads. Thoughts?
IRStuff - I have emailed that company you posted the link to and will look into getting a quote from there, thanks.
RE: Thermally conductive, electrical insulating material?
TTFN
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RE: Thermally conductive, electrical insulating material?
As you are leaning toward Mica and bolting it on I think you should look at alternatives to Mica such as the ceramic glasses like Pyroceram that will fill your needs. Here is just one of many suppliers of these materials. If you look at the Whitford site in my previous post you will find a coating "Xylan" that is one of the better dielectric coatings for fasteners available. You might be able to find machine screws off the shelve coated with Xylan.
http://www.fireviewglass.com/index.asp
Another thought is that it may be possible to anchor what ever type material is used by using posts with a ceramic adhesive or potting compound.
RE: Thermally conductive, electrical insulating material?
RE: Thermally conductive, electrical insulating material?
(Estimating) 9 V, 1/2 A, 4~5 W.
Thanks in advance (and for the help).
RE: Thermally conductive, electrical insulating material?
RE: Thermally conductive, electrical insulating material?
RE: Thermally conductive, electrical insulating material?
I would try this approach as starting point.
A little warning, Mica is not the easiest thing to get a neat hole in. Another thing give you self a little leeway in the design for expansion of the Al and be aware that Mica thermal expansion is very low.
For your Nylon Fasteners take a look at Micro Plastics as they have about anything you need in the Nylon line.
http
Just thought of another possible solution. Take a look at Glyptal Insulating Paint for you Al plate and fastener heads. This is one tough paint that been around for a long time as an electrical insulator and heat conductor.
I've used it in some pretty tough conditions, both temperature wise and chemical exposure. It will easily take the 135C temperature mention in the description.
http://www.caswellplating.com/aids/glyptal.html
RE: Thermally conductive, electrical insulating material?
RE: Thermally conductive, electrical insulating material?
It might take a little experimentation to get an even coat.
For maximum durability you may need to bake it. If you have any questions the Glyptal people have always been very helpful.
http
RE: Thermally conductive, electrical insulating material?
Regards,
Mike
RE: Thermally conductive, electrical insulating material?
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RE: Thermally conductive, electrical insulating material?
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RE: Thermally conductive, electrical insulating material?
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:
h
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:/
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.