Electrically non-conductive but thermally highly conductive material 3

[Jakelian]

I am looking for a material which is electrically non-conductive but thermally highly conductive.

Need the material in sheet form, like a gasket, any thickness between 1/4 inch and 1/2 inch would be perfect,

Doesnt have to be flexible, bendable etc, can be either soft or very solid,

Wont bear any physical pressure,

Operating temp: 180 F,

Needless to say, must be commercially available ))

Guys, thanks a lot in advance,

Jakelian

 

[IRstuff]

Do you really think you'll get away with not providing some numerical requirements? Otherwise, just alumina could construed as meeting your requirements.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529


Of course I can. I can do anything. I can do absolutely anything. I'm an expert!
There is a homework forum hosted by engineering.com:

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[itdepends]

Thermal grease?

https://en.wikipedia.org/wiki/Thermal_grease

As a chem eng/metallurgist the first part of any answer I give starts with "It Depends"

 

[gruntguru]

Link

je suis charlie

 

[Jakelian]

Thanks;

IRStuff:

Only requirements I can think of at this stage (and with my knowledge) are, max temperature; 180F, thickness; upto 1/2 inches. Values about electrical or thermal insulation? I dont feel like I have that info or the luxury to ask those at this moment. I mean, if I find something with 50 WmK, it is better than nothing. Or 40 WmK but cheaper, it will work better.. I just have to see the cost.. Then if affordable for the product, think of it as $s per W/mK, then test it on its place to see what difference it makes..

I am checking the alumina pads, I think 1550C temp is kind of overkill for my 180F application, and for 0.13 thermal conductivity, it may just not worth it, I am cheking...

Itdepends:

Thanks but thermal grease wont stay there for long , I need something that can hold itself better, for example, a soft blanket would stand there.. (I forgot to say that the application stands vertical, Itdepends, sorry, my bad).

Gruntguru:

That WORKS, (if it is affordable), I am on it! I am giving you a star for the best answer, thank you very much

Guys, I appriciate your attention))

 

[moltenmetal]

You did notice that the stuff is 1.8 W/m K, which is an order of magnitude lower than what you apparently wanted. But it's better than glass, which is only around 1 W/m K

Alumina ceramic is somewhere between 12 and 30 W/m K or so, and is pretty cheap.

Silicon carbide can be 50-100 W/m K, but is a lot more costly.

 

[Jakelian]

Moltenmetal,

Thank you for correcting me, yes, now I found alumina with 29W/mK, far superior to those pads (star).

Can you think of any US manufacturer who provides it in sheet form?

Oh pls dont bother, I am cheking with ThomasReg,

Thanks a lot)

 

[IRstuff]

That's an odd way to design a system. Nevertheless, just to be complete, you can look at Aluminum Nitride:

http://www.goodfellow.com/catalogue...0Qmmw5CWdf5w&n=qPnWjX0SQh5zSEBfPmhBHLwQyH1REg

which has nearly 1/2 the thermal conductivity pure aluminum, but is an insulator.

TTFN
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Need help writing a question or understanding a reply? forum1529


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There is a homework forum hosted by engineering.com:

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[btrueblood]

...or higher if you can get it in a single crystal. Similarly, boron nitride. And on the far end of the silly scale, diamond and graphene.

 

[zappedagain]

Do you really need it that thick?

http://www.digikey.com/product-search/en?vendor=0&keywords=tgon

Z

 

[Compositepro]

When dealing with heat conduction though a material it important to realize that all materials cause a resistance to heat flow. It is more effective to cut the thickness in half than to find a better "conductor" because it is, in fact, a "resistor"

 

[Jakelian]

IRStuff,

Thanks, I checked your link, empty page comes up. Then I went their home page and searched. I found several options, one of them is:

http://www.goodfellow.com/catalogue...d_urlNo=GFCat411&Catite=AK613100&CatSearNum=1

So,

25x25mm, with 10mm thickness, price: 235 Sterling?? (So, what is the size of the sheet? 25mm x ?)?

btrueblood, the product can not afford those,

zapped again, yes, I need it at least 1/4 inches...

For actual production, I will need the material for 500mm x 2000mm, in other words, 19.6" x 78.7". So, it must be really affordable. Any more ideas?

Thanks again,
J

 

[arbreen]

I worked with power electronics packaging in a past life, so here's my two cents. You can't just sandwich a ceramic block in there and expect to get good heat transfer at the interfaces because they're not compliant. I would use a copper sheet (or aluminum for cost) for the bulk of the material, and depending on which interfaces must be electrically insulating I would use a thermally conductive dielectric sheet at each interface. You need a sheet at each interface unless it's just a heat spreader, but if one interface doesn't need to be electrically isolating then that pad can be cheaper and have better heat transfer. You will need relatively close bolt spacing to get even pressure on the interfaces, and insulating screw bushings will be needed to maintain electrical isolation. This arrangement will have better thermal performance and lower cost than any single-material solution I'm aware of.

 

[Jakelian]

arbreen,

Thank you very much for your attention,

Good thinking, but, about aluminium and copper: Absolutely no metals around.. So, cant use them; they cause other problems..

Thanks anyway for the thought anyway.

ceramic block, yes, i am searching that one...)) thanks..

J

 

[Overrun]

arbreen Any thought as to heat grease or thin "heat conductive" adhesive at the interface?

 

[arbreen]

Overrun, we didn't use thermal grease, at least in part because they're messy and these assemblies were in optics. Based on experience installing computer heatsinks with silver grease it may be difficult to get a thin, even application of grease or adhesive with such a large surface. Heat conducting but electrically insulating grease won't form a reliable dielectric layer, it's just good because it won't short out connections that it oozes onto. However, you might call a manufacturer like Bergquist and ask their engineers. They should know all about pads, metal substrates, thermal greases and adhesives. Full disclosure, they were a major vendor to a previous employer and are a customer of the current employer.

 

[Ceramicguy]

Before you go crazy with expensive high thermal conductivity ceramics, take a careful look at your thermal "system". Often times failure to properly design and specify the faying thermal interfaces introduces enough thermal resistance to offset the improved conductivity of the thermal link. By the way, what are the dimensions you need besides thickness? They may impact availability and affordability. Contact me if you want to go the ceramic route. I have most of the materials discussed in stock.

-Bruce

Bruce

http://accuratus.com

 

[Jakelian]

Ceramicguy,

Thank you very much for your attention,

I solved the problem by using some polyester foil, it was easier than I thought,

Thanks a lot anyway for your attention,

regards,

Jakelian