Best heat sink compound?

[DaveC]

White "tooth" paste kind, or clear greasy "hair stuff" kind?

 

[Robert Baer]

White "tooth" paste kind, or clear greasy "hair stuff" kind?
--
DaveC
[email protected]
This is an invalid return address
Please reply in the news group

I think the white stuff is better.
Use a *thin* coat, and move the part around in small circles while
pressing together, to remove air pockets.

 

[Guy Macon]

White "tooth" paste kind, or clear greasy "hair stuff" kind?

Neither.

http://www.ksbrainstorms.com/index.php?pagename=Arctic_Silver_5_Review
http://www.xbox-connection.com/hostedsites/hotlinesrc//reviews/arcticsilver5.php
http://www.overklokking.no/annet/arctic_silver_5/eindex.html
http://overclockersclub.com/reviews/articsilvercermaiquereview.php
http://www.modsynergy.com/Review 109.htm

 

[Watson A.Name - Watt Sun, Dark Remover]

White "tooth" paste kind, or clear greasy "hair stuff" kind?

Most of the stuff I've seeen recenlty uses neither. They use a piece
of gray rubbery fabric, which looks like it's pre-cut, with holes etc.
in it. The T's/FETs/diodes are clamped to it with a springy clamp, so
that as they heat up, the parts can move somewhat. I like that idea,
because I've had to replace devices that failed because they were no
longer making good contact with the heatsink. Some of the worst
failures were the ones that used nylon screws. Once they get loose,
the device gets hot and melts the screw, and then it's all over very
quickly. That's probably why many equipment makers put loktite thread
sealant on the screws and nuts to prevent the loosening.

--
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[Guy Macon]

Make sure you use all the other over hyped crap so it doesn't get
lonely.

I would find it easier to believe that it was overhyped crap if
I wasn't typing this on a quad processor Compaq Proliant that
has the CPUs runnin 10 degrees C cooler since I replaced the
OEM heat sink compound.

 

[cpemma]

White "tooth" paste kind, or clear greasy "hair stuff" kind?

Unless you're on forced-air cooling there isn't a major difference, as the
junction-package and sink-air thermal resistances are so much more than the
package-HS figure. Better to make sure the mating surfaces are both flat,
especially round the mounting holes. I think the white goo creeps less so is
cleaner long-term than silicone grease, silver types are snake-oil in most
applications.

Heatsinks-On Semiconductor AN1040-D:
https://www.onsemi.com/pub/Collateral/AN1040-D.PDF worth a read

 

[Michael A. Terrell]

Neither.

http://www.ksbrainstorms.com/index.php?pagename=Arctic_Silver_5_Review
http://www.xbox-connection.com/hostedsites/hotlinesrc//reviews/arcticsilver5.php
http://www.overklokking.no/annet/arctic_silver_5/eindex.html
http://overclockersclub.com/reviews/articsilvercermaiquereview.php
http://www.modsynergy.com/Review 109.htm

--
Guy Macon, Electronics Engineer & Project Manager for hire.
Remember Doc Brown from the _Back to the Future_ movies? Do you
have an "impossible" engineering project that only someone like
Doc Brown can solve? My resume is at http://www.guymacon.com/

Make sure you use all the other over hyped crap so it doesn't get
lonely.
--
24 days!


Michael A. Terrell
Central Florida

 

[Miles Golding]

This question is timely for me. I'm about to build my own (first time) and
have bought an Intel P4 2.4 /heatsink pack. Having researched a fair bit
before starting the job, I discovered thermal paste. Is it really necessary?
I don't intend to overclock, so will the thin film already attached to the
base of the heatsink do the job adequately?
Miles

 

[Costas Vlachos]

This question is timely for me. I'm about to build my own (first time) and
have bought an Intel P4 2.4 /heatsink pack. Having researched a fair bit
before starting the job, I discovered thermal paste. Is it really
necessary?

I don't intend to overclock, so will the thin film already attached to the
base of the heatsink do the job adequately?
Miles

If there is a thin rubbery film already there on the heatsink surface, then
you don't need to add anything else, it will work fine. But if the heatsink
is bare (i.e., a plain metal surface), then it's absolutely necessary to use
some kind of thermal paste between heatsink and CPU. No matter how smooth
the surfaces are, there will always be small imperfections and particles
that will not allow a good thermal path between the two. That's the purpose
of the paste. But in your case it's not necessary as your heatsink already
has thermally conductive film on it.

cheers,
Costas
_________________________________________________
Costas Vlachos Email: [email protected]
SPAM-TRAPPED: Please remove "-X-" before replying

 

[Asimov]

"DaveC" bravely wrote to "All" (01 Dec 03 00:10:21)
--- on the heady topic of "Best heat sink compound?"

Try lard, then when you get that frying bacon smell you know it's too hot!

Da> From: DaveC <[email protected]>

Da> White "tooth" paste kind, or clear greasy "hair stuff" kind?

.... A couple of volts below threshold.

 

[Floyd Davidson]

I would find it easier to believe that it was overhyped crap if
I wasn't typing this on a quad processor Compaq Proliant that
has the CPUs runnin 10 degrees C cooler since I replaced the
OEM heat sink compound.

First, if you saw that much difference, then it is *obvious* that
the initial installation with OEM heat sink compound was flawed.
10C is *way* too much!

However, there *are* differences between the different heat sink
compounds. The question is, what is it worth to have 2 degrees
lower temperatures? If you have a one shot deal, and the price
is $10, why not??? That fact that for $6 you can do well enough
just isn't significant.

On the other hand, if you might do a dozen or more, it starts adding
up. Likewise if it ever comes to a question of delaying a project
until the "good stuff" can be obtained, that might not settle too
well either.

The most hilarious part of the whole thing though, is that the
difference between any of those silver based compounds that you
pay an arm and a leg for, is too small to be significant in most
cases compared to what you can find in virtually *any* automotive
shop.

NAPA Item# 765-2569
Copper Anti-Seize Lubriant

A 4 ounce bottle will last forwever unless you are in the business
of turning out multiple systems per day.

 

[Guy Macon]

First, if you saw that much difference, then it is *obvious* that
the initial installation with OEM heat sink compound was flawed.
10C is *way* too much!

Point well taken. The OEM heat sink compound was applied at a
Compaq factory in 1996, and I replaced it in 2003, so age is
almost certainly a factor.

 

[Tim Wescott]

Define "best".

Do you mean best thermal conductivity? Best price? Best assembled
equipment cost? Best reliability? Each "best" will get you a different
answer. As "cpemma" pointed out, unless your thermal goo is the limiting
factor in your thermal path you're better off going to something easier to
assemble than the highest thermal conductivity. On the other hand, if
you're designing a circuit with 100W transistors that have a 1/2 square inch
thermal contact area, you'd better use the best thermally conductive
material that you can find.

The last place I worked either used thermally conductive glue to attach the
heatsinks to chips or used the heat conductive elastomer (the brand name was
Sil-Pad, I think). This was done for ease of manufacture, to bring the
assembled equipment cost down. The only place where we used thermal goo was
to cool an electromechanical part who's case temperature couldn't exceed 85C
without internal damage.

 

[Tim Wescott]

[email protected] mentioned...

-- snip --

longer making good contact with the heatsink. Some of the worst
failures were the ones that used nylon screws. Once they get loose,
the device gets hot and melts the screw, and then it's all over very
quickly. That's probably why many equipment makers put loktite thread
sealant on the screws and nuts to prevent the loosening.

According to one of the mechanical designers at my old work, nylon screws
contract with cold and stretch. Then when it gets warm again they're loose
(and presumably about to melt). We designed systems for close to the
military temperature range, so we simply didn't use nylon screws -- usually
we used thermally conductive glue, or a stainless-steel screw with a nylon
shoulder washer if necessary.

 

[Jim Weir]

You will get many answers to this, and as usual, "best" is a function of several
variables.

However, if you are out in East Undershirt hicksville some day and just HAVE to
get the job done, go down to the drugstore and get a small tube of that white
stuff you rub on your nose in the summertime (zinc oxide). It isn't the BEST
thermal conductor you can find, but it will do a fine job in most instances.

BTW, the "thin rubber fiber" that some other folks are talking about are from a
company called Bergquist if I'm not mistaken. Expensive, but damned good
thermal conductivity.

Jim

 

[DaveC]

NAPA Item# 765-2569
Copper Anti-Seize Lubriant

and you recommend this as a head-sink compound for semiconductors?

 

[Michael Black]

Make sure you use all the other over hyped crap so it doesn't get
lonely.

Considering the question, and the large cross-posting, I kind of
expected a computer newsgroup to be included. And the threads over
there about heatskink compound can be somewhat amusing. They range
from "Do I really need heatsink compound" to debate over the brand name
of the compound.

It strikes me that it's right up there with the audio consumers
and gold plated cables and ten dollar capacitors.

Michael

 

[John Larkin]

White "tooth" paste kind, or clear greasy "hair stuff" kind?

The white thermal compound stuff is better. For serious heat sinking,

both surfaces must be flat; *very* flat. Most extruded heat
sinks aren't unless they are machined after extrusion.

don't use an insulator. If you must, use 0.5 mil
hard anodize on the heat sink.

*don't* use a silicone sil-pad or phase-change stuff.
They are both awful thermally.

Apply high, uniform mounting pressure. Belleville washers
and clamps are good.

Make sure the heatsink baseplate is thick enough to spread
the heat laterally; otherwise there will be a hot spot under
the device and all this effort is mostly wasted. Use a copper
heat spreader if needed.

If this is for a CPU, forget the whole thing.

John

 

[Floyd Davidson]

and you recommend this as a head-sink compound for semiconductors?

Depends. Low voltage and mechanically attached, yes.

I use for cpu's, such as the AMD Athlon series that runs so hot.

 

[John Larkin]

If there is a thin rubbery film already there on the heatsink surface, then
you don't need to add anything else, it will work fine. But if the heatsink
is bare (i.e., a plain metal surface), then it's absolutely necessary to use
some kind of thermal paste between heatsink and CPU. No matter how smooth
the surfaces are, there will always be small imperfections and particles
that will not allow a good thermal path between the two. That's the purpose
of the paste. But in your case it's not necessary as your heatsink already
has thermally conductive film on it.

cheers,
Costas
_

The 'thin' rubber films are typically 5-10 mils thick, which is huge
in this game. They are rotten thermal conductors, even if you believe
their published specs. They dominate thermal resistance except for the
wimpiest of heat sinks.

John


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