[sci.electronics] Conducting Adhesive

pjh@mccc.uucp (Pete Holsberg) (10/07/90)

What's a good conducting adhesive that I can use to stick a heat sink to the
top of a large IC?

Thanks,
Pete
-- 
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jgd@rsiatl.UUCP (John G. DeArmond) (10/08/90)

pjh@mccc.uucp (Pete Holsberg) writes:

>What's a good conducting adhesive that I can use to stick a heat sink to the
>top of a large IC?

I have a nice little kit here from Thermalloy, Inc called a "Thermalbond
4951".  The kit contains a jar of green epoxee goop and a smaller 
bottle of activator liquid.  It mixes at the ratio of 100 parts of
resin to 7.5 parts of hardner (got that? :-) and sets up in 24 hours
at ambient or 30 minutes at 130 degrees C.  It also recommends a post
cure of 4 days or 4 hours at 200 degrees F.  I cure it for about
an hour in an oven at about 250 degrees and it works well.  It sets
up to a bright green, very hard and very conductive mass.

I bought the stuff surplus at a hamfest for $3.00 a kit.  It has a shelf
life but the fact that mine is several years out of date does not 
seem to affect its performance.  The address on the box for Thermalloy is:

PO Box 340839
2021 West Valley View Lane
Dallas, TX 75234
214 243 4321
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whit@milton.u.washington.edu (John Whitmore) (10/09/90)

In article <1990Oct7.155829.3917@mccc.uucp> pjh@mccc.uucp (Pete Holsberg) writes:
>What's a good conducting adhesive that I can use to stick a heat sink to the
>top of a large IC?
>
	Assuming you mean heat-conducting, RTV silicone is a good adhesive
for this sort of thing.  The important thermal resistance is not likely
to be the adhesive (its path length, the thickness of the glue, is short),
but rather the package of the IC.  While 'loaded' adhesives have better
conductivity (we've used copper powder/epoxy mixes here, for our
cryostat work), the plain ol' gunk from the tube is entirely adequate.

		John Whitmore