Low cost thermal adhesive.. DIY Tutorial

Mohrenberg · May 7, 2012

you can also do a simple experiment to test ho effective it is.
get 3 flat pieces of aluminum, and glue two pieces on each side of a single piece.
glue 1 with the homemade glue, and the other with arctic silver. tape a thermometer to each prong, and then apply heat to the first piece.

whichever piece heats up more, it's transferring more heat through the glue and into the metal.
Here is a picture.
this would also be helpful for finding out what ratio of epoxy/powder works best

JLSE · May 8, 2012

^ That looks like it would help establish a preferred mix.. So far when ive
used this, I just add as much aluminum as possible without affecting the
grip and strength of the epoxy.

Its not all that hard to get a mix with plenty of AL that works well.

That setup would be great for testing different materials.. I read that
diamond dust has some good properties, but the structure of the dust
works against any benefit..

Mohrenberg · May 8, 2012

Yeah I can't take credit for it. I saw it done for this exact purpose, DIY thermal adhesive. The other person was using thermal paste and epoxy though

JLSE · May 8, 2012

^ Wonder how that worked out :thinking: Using paste and epoxy
seems to me would be counter productive, unless they dried the
paste with heat first. That extra moisture in the epoxy cant be good.

Benm · May 9, 2012

Just a word of caution for people that plan on working with this aluminium powder: Be extremely careful when handling it. Aluminium is combustible, and it finely powdered form like adveretised could result in serious dust explosions if you happen to get the powder up in the air.

JLSE · May 9, 2012

^^ I will keep this in mind next time I pour a foundation of thermal epoxy

The aluminum used and linked is the spherical 'atomized' type. Even if you mix this
with a strong oxidizer, it does nothing. While im sure anything is possible, the amount
used is approx 1gr per mix..

IIRC I mentioned in the first post not to use the 'ball mill flake' variety. That stuff
is very flammable.. I have never seen anything burn quite like it. A small pile radiates
a lot of heat and light. The atomized stuff is molten AL sprayed through a nozzle and cooled
with water..

I would though caution those who try not to breathe any of the dust...

Mohrenberg · May 9, 2012

JLSE said:
I would though caution those who try not to breathe any of the dust...

I snort lines of it. Keeps you cool in the summer.

Benm · May 9, 2012

The manufacturing process makes it inert to combustion indeed, but only up to a certain degree. Surely it does have an oxide layer protecting it much better than the milled pyrothechnic material, but that is no guarantee for safety.

This dust may not be that easy to ignite initially, but one you manage to spark a could of it, there is no way back, nor any difference with freshly ground aluminium of similar mesh size.

JLSE · May 9, 2012

Benm said:
The manufacturing process makes it inert to combustion indeed, but only up to a certain degree. Surely it does have an oxide layer protecting it much better than the milled pyrothechnic material, but that is no guarantee for safety.

This dust may not be that easy to ignite initially, but one you manage to spark a could of it, there is no way back, nor any difference with freshly ground aluminium of similar mesh size.

For the amounts being worked with, and a non pyro grade AL, I wouldn't be too worried..

AL flake on the other hand will ignite with a brief shot of a laser, with no oxidizer
added.

You can also hit the spherical AL with a torch and nothing happens. it glows under flame but will
not sustain any type of burn. When mixed with kclo3, the chlorate separates and balls up into
molten 'pearls', the AL remains with no ignition..

I would not be worried unless I spilled a 1lb bag of the stuff in a confined area, and still id be more
concerned with the onset of Alzheimer's.. :anyone:

*EDIT

Heres a video of pyro grade AL. I added no chemical oxidizer to this. You can
see how easily it reacts to a small amount of heat delivered by a 1.5W 445 laser.

Id make a video of the spherical AL, but it would be pretty boring. I will see if I can
get some to light with a H/V transformer..

daawood123 · May 9, 2012

woah, imagine that happened inside your laser build, and you thought it was the diode that made the host red hot.

jakeGT · May 12, 2012

Watch out for this seller on amazon. I ordered this "arctic silver" last week, and it came in today, and it is actually arctic alumina. I filed a claim saying I want my damn arctic SILVER or my money back.

Once again, be wary of this one.

http://www.amazon.com/gp/product/B001JYQ9WO/ref=oh_details_o00_s00_i00

cilegray · May 12, 2012

jakeGT said:
Watch out for this seller on amazon. I ordered this "arctic silver" last week, and it came in today, and it is actually arctic alumina. I filed a claim saying I want my damn arctic SILVER or my money back.

Once again, be wary of this one.

Amazon.com: Arctic Silver Adhesive (Premium Silver Thermal Epoxy) - 7.0 Gram (ASTA-7G): Computers & Accessories

I don't know what you're going to use it for, but I'm gonna go ahead and say Alumina is better for your application, anyways.

Non-capacitive, non-conductive, the Alumina is much safer around easily shortable electronics.

I know your point is you didn't get what you bought, but I believe it's for the better.

jakeGT · May 13, 2012

Hehe, I agree. But I have always used arctic silver, but am definitely gonna use the alumina. I've only bought thermal adhesive once when this guy on here bought two sets on amazon and received like 50.

JLSE · May 16, 2012

Ive always used arctic silver both thermal paste as well
as the quick set epoxy. I have yet to have any trouble with
bridging connections with this stuff, just keep it clear of
any open contacts.

It comes down to what you are using it for.. As DTR pointed out
either in this thread or another, using it for drivers may prove tricky
depending what the compound is coming in contact with.

Mounting diodes to modules and modules to heatsinks, its the best
way to go.. To this day I have never dry mounted a diode.

Benm · May 16, 2012

The problems come when you use a metal based compound to set a circuit to a heatsink. If its -just- the part that is intended to be connected to a heatsink (like the flange on a power transistor) its probably fine, but when you use it epoxy-style to pot in whole circuits you're in for trouble.

If you connect metal to metal using any kind of paste/compound you should asumme it will make an electrical connection. There are special pads (and mica discs) to make an electrically insulated connections, which are used with nylon bolts/nuts to secure them etc.

daawood123 · May 16, 2012

^ :O i just finished my build and before finishing i glued the ghostdrive into the heatsink hole where the diode is. bear in mind only the side with the black thing (regulator??) is glued on, and i used phobya 2 part thermal epoxy which i got from ebay. as far as i can tell, its working fine.

Low cost thermal adhesive.. DIY Tutorial

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