Homebrew thermal epoxy MacGyver(w/pics)

[Freq Band]

I have had no luck finding "thermal glue" for attatching heatsinks to IC chips that need it.
So I MacGyver'd my own.... (and no, I wasn't trapped in an abandonded mountain cabin with bad guys chasing me, in order to save a beautiful girl from a politically incorrect injustice).
The metal powder is from a craft store, or well stocked paint store.
It is powdered aluminum. I chose clear type epoxy because coloured type has pigment, and possibly other fillers : I wanted the ratio of epoxy-to-metal(powder) to be high....maximum stick/maximum metal.

I seem to come up with an eyeballed mix ratio of:

equal parts glue, and powder
(where glue includes part A & B together)

....this simply means a lump of glue is the same size as a lump of the powder.
I was curious to see if I could put "too much" metal in the glue, and have it pass 24v @1 amp....but I tried it, and it did not pass anything. Nor would it read as any resistance/continuity on my Fluke DMM.

IMPORTANT :!: YUCKY DUST HAZARD:
Always mix/handle this aluminum powder outside, or a non-windy place......it loves to get airborne and I doubt it's good for you. I mix it in my dirty garage with a dust mask, then run inside and use it :grin:

(If I am correct, the longer 'working time' the epoxy has, the less brittle it is, or will become, over time. Any thoughts?)
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EXAMPLES:


(this is where I'm glueing two AD811 single opamps, to make them fit as a dual 8pin type ....I didn't have the correct dual chip (AD812) :roll: ))

http://i5.photobucket.com/albums/y177/Midiot/dscn1884.jpg
http://i5.photobucket.com/albums/y177/Midiot/DSCN1886.jpg
http://i5.photobucket.com/albums/y177/Midiot/DSCN1891.jpg
http://i5.photobucket.com/albums/y177/Midiot/DSCN1890.jpg

(EDIT...oops these are pics of before I came up with the metal mixture, so just pretend the glue you see is aluminum coloured, not black :wink: )

=FB=

 

[Gus]

Look for Arcticsilver thermal adhesive or other brands like it. The places that PC overclockers buy parts should have it.

 

[yan_b]

nice idea,
did you try to check how good is the thermal conductivity of the glue in someway?

 

[mikka]

When I worked with resins, we used to make our own thermal goop for casting heated moulds in a very similar way.... just mix aluminum granules and epoxy... :thumb: Araldite was famous for having a low temperature tolerance.....softening around 70 deg Centigrade....and you want to make sure the "metal" powder is genuine metal, not some sexy looking craft powder.... :green:

 

[shabtek]

that clear epoxy does not seem best to me...ive had experiences where it turns rubbery and flexible with time...try "jb weld" it is the most durable epoxy I have ever used, and may have some metal content built in...on that point, J.H. mensions he uses a silicone filler in his opamps so as not to mechanically stress components that expand and contract with thermal cycles.

 

[asm]

i second what gus mentioned...


http://www.newegg.com/Product/Product.asp?Item=N82E16835100013

:?: