Thermal Interface Material Challenge

[Baheej]

Gurus, I need a thermal interface material between an electrical/electronic device and an Aluminum heat sink. The surface of the device is not flat and mostly is non-uniformly concaved. The out-of-flatness is about 0.060" at the highest concaved point of the surface. The device surface is 15" x 7.5". The device is mounted via four mounting holes on its corners. The interface material needs to be soft enough to squeeze/flow/gush/…. out and fill in the gap(s) between the device and the heat sink. At the same time, I'll need to replace the device frequently and need to have a clean interface material that is not messy and easy to remove. The device replacement will be done in the field. Thermal grease is not an option. I also tried typical thermal pads, but none had enough flow in them for that much area. Any ideas?

 

[ivymike]

make a casting of the surface, and transfer the geometry to a specially-made heatsink that fits closely?

use metallic foil or similar to carry the heat to places where contact actually happens?

 

[Baheej]

Thanks ivymike. You have a good idea but I should have mentioned all the restrictions. I'll need to mount 90 of those devices to custom built heat sinks (each heat sink carries ten devices, five on each side). Also, the concavity on these devices changes from one to another (i.e.: there is no single profile to copy). So it is not a matter of one device on one heat sink.

 

[IRstuff]

Are you saying that the following can't do the job:

http://vendor.parker.com/Groups/Sea...f36927a6efc85256e89004ea33a/$FILE/570_580.pdf

or this:

http://vendor.parker.com/Groups/Sea...30b190bd94ce1785256c010045aef7/$FILE/t630.pdf

or this:

http://vendor.parker.com/Groups/Sea...8d8c7e99b0883e85256b5f004b411e/$FILE/G574.pdf

TTFN

 

[Baheej]

IRstuff,
I'm waiting for samples of the A570 from Comerics. Still I wanted to see if there are any solutions out there that I'm not aware off.
Regards,

 

[ScottyUK]

Bergquist are a direct competitor to Chomerics. Their 'Gap Pad' range might be worth a look.

http://www.bergquistcompany.com/tm_gap_pad_list.cfm

There are numerous thermally conductive epoxies and silicones out there if you don't need to be able to dismantle the assembly (or don't want you customers to do so!). I Googled [blue]thermally conductive epoxy[/blue] and got nearly half a million hits.


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I don't suffer from insanity. I enjoy it...

 

[Onno]

The thermal conductivity of indium is 82 watt/m*K and it's melting point 156 C. Available as thin foil and is rather soft. I do not know your maximum allowable temperature.

Or, think of a 2-step solution i.e 2 heat flow barriers.
#1 between electronic device and intermediate barrier. You could use paste here.
#2 between intermediate barrier and Al heat sink. this can be disconnected but you are not using paste. The intermediate barrier is optimized with regard to the elctrnic device and the Al heat sink.