heatsink goo

[mr.squatch]

I know nothing of these kinds of things, I'm sure it's got an easy answer to somebody who does. I need an adhesive type goo that'll stick an aluminum heatsink to a flat plastic box, that'll transfer heat thru the goo. Is there such a mystery material? Help muchly appreciated.


g

 

[IMSabbel]

Do i read that correctly?

The glue should be between heatsink and plastic? And the heat transfer is from the plastic to the heatsink, through the glue?

If yes, just take superglue. The termal resistence wont matter a bit compared to the plastic part (seeing that correct application results in a very thin layer).

Otherwise, there is thermal epoxy.

 

[LukeA]

Do i read that correctly?

The glue should be between heatsink and plastic? And the heat transfer is from the plastic to the heatsink, through the glue?

If yes, just take superglue. The termal resistence wont matter a bit compared to the plastic part (seeing that correct application results in a very thin layer).

Otherwise, there is thermal epoxy.

There's also the tube of silicone-based thermal goo that DX sells. It cures like caulk.

But when heatsinking to plastic, the thermal compound won't matter at all.

 

[Torque1st]

Plastic is an insulator, both thermally and electrically.

 

[gadget_lover]

What everyone is saying is that the heatsink is supposed to conduct heat to something with enough surface area to radiate the heat to the surrounding area. The plastic won't help at all, and the heat will build up in the metal of the heatsink until it's as hot as the LED. At that point it will not be cooling the LED at all.

Daniel

 

[markus_i]

...unless your 'piece of plastic' is a part of the body of the ROV(?) in your avatar and more or less completely immersed during operation.

But even in this case, keep the contact area as large as possible and the adhesive as thin as possible, otherwise use whatever works for sticking those two materials together. A thin layer of high strength epoxy (I use UHU Endfest, but that's more or less a matter of geographical preference) works quite well for a lot of plastics. The keyword is 'thin' - I use a single layer of a multi-layered tissue paper as distance holder/isolator.

Bye
Markus

 

[mr.squatch]

The application is a 12v ac/dc adapter (power supply), pretty much exactly the same as the one that powers a laptop. Same dimensions and everything. It powers up some batteries that run while being charged. It gets very very hot, so hot that I worry about taking it on the job. Too hot to handle if it's been on for an hour or so. I believe it's a very thin layer of plastic over a metal charger. It's very heavy so I'm pretty sure there's a lot of metal in there. I figured I could stick a couple heatsinks to each side and dissipate some of the heat and hopefully not catch something on fire. haha.

I was thinking something like this, one on each side:
http://www.surplusales.com/Heatsinks/HeatSink2.html

the one on the bottom row, right side.

Thanks for the advice

g

 

[gadget_lover]

That makes more sense. I was thinking that there was a flashlight involved.

If the plastic is hot, the heatsink will help to cool it, so that's not a bad idea. It won't be perfect, but sometimes dropping the temperature by a few degrees is all that's needed to extend the life of the power supply.

Daniel

 

[markus_i]

In this case, if you've got sufficient space, a fan might even be better than a (small) heat sink. It's quite amazing how much difference even a little bit of air movement can make. Top right on http://www.surplusales.com/Heatsinks/HeatSink4.html
might do it, the one on the right in the third row might be a bit expensive.

Bye
Markus