Thermal Adhesive -vs- Thermal Tape

[Kookapeli]

Would using thermal adhesive tape work just as well as the adhesive compound as they are both designed to do the same thing. The tape is also alot cheaper than that of the compound. I'm not planning on making that many lasers so don't rely want to fork out $10 on something that's just going to get wasted
when I can get a bit of tape for 2 or 3 $$$ and wont go off.

http://www.chilledpc.co.uk/shop/product_info.php?products_id=158

What do you guys think ?

 

[BShanahan14rulz]

I tried 3M's 9882 tape. Adhesive properties aren't great, but heat transfer is way better than silpads. Haven't compared it to adhesive or grease, but adhesive and grease will probably be better if it is actual thermal grease or adhesive.

 

[Bionic-Badger]

The tape or paste or whatever should only be there to fill in the microscopic gaps between the two surfaces, and should be as thin as possible. With that in mind you might as well just buy a small tube of Arctic Silver and use that. A tiny little blob (as in 1-3mm long from the tip) will be enough for most jobs, which means your tube will last you for a long time unless you're manufacturing tons of things, in which case I'd buy the larger tube. It's not that expensive for how much you'll use.

Paste also allows you to fill in gaps that tapes won't be able to fit into, like curves or even around the diodes themselves. You can also use it for your computer processor.

 

[Benm]

Tape is only good for contacts between two flat surfaces, notably a processor and its heatsink.

When building lasers, you often have to major thermal connections to overcome: between diode and aixiz, and between aixiz and heatsink. Both connections are round, and i would recommend using a thermal paste rather than tape.

You don't need to get a very expensive thermal paste though: its just for filling very small surface gaps, not for bridging large distances. The latter you could do with thermal epoxy, altough its heat conductivity is still marginal compared to any metal.

 

[Kookapeli]

It's just to attach the driver to a heatsink I would of thought it would be ok as the are both flat surfaces

 

[LarryDFW]

Kookapeli;

I make my own thermal epoxy.

Mix a name-brand good quality 2-part epoxy with aluminum oxide (polishing powder),

and use that to attach your heat sink.

LarryDFW

 

[Coherent Light]

Wouldn't it be conductive as well doing it that way?

 

[Kookapeli]

That's what I was thinking. Is your home made stuff thermally conductive as well ?

 

[LarryDFW]

Kookapeli;

Not conductive to the voltages we are working at.

Reasonably conductive thermally.

LarryDFW

 

[Coherent Light]

I might borrow your recipe then. Was worried about shorting driver components.

 

[Kookapeli]

It's a good idea if you're going to use a lot of it, but I' not going to be using a lot of the stuff in the near future, I was wondering if anyone has used the tape at all ???

 

[anselm]

I've been using some kind of thermal "tape" to put between the back of the lm317
and a piece of aluminium heatsink.
Both the tape and the aluminium come from a power transformer, there were 3
ICs similar to the lm317 in shape and size mounted onto the same heatsink.

This purplish stuff isolates electrically, transfers heat effectively but sticks only to
the heatsink, not to the IC. So a little screw presses the lm317, via that hole in it's "back",
onto the (threaded) heatsink, sandwiching the tape or pad inbetween.

Works fine for my purposes.

 

[LarryDFW]

I might borrow your recipe then. Was worried about shorting driver components.

I have plenty of the 600 mesh aluminum oxide,

if you have trouble finding it.

LarryDFW

 

[Coherent Light]

Thanks Larry. I'll let You know if I have trouble.

 

[Benm]

Getting electrical insulation with thermal contact is another matter entirely.

There are some good solutions on the market though: especially the silicone pads and plastic screw combintions can work very well if you need to use them. Thermal coupling will never be as good as a contact that allows electrical conduction too, but they can be of great help in some circuits.

More old fashioned are mica plates coupled with thermal grease on either side. They were widely used in audio amplifiers and such, but cannot compete with the more moder alternatives.

 

[Kenom]

powdered Ceramic mixed into your epoxy will make a electrically isolating epoxy.

This is just your basic white thermal grease for CPU's it's mixed with Ceramic powder.