Questions about thermal grease?

[Don Kuenz]

Greetings,

This post is about thermal grease for processors. Many PC technicians
think highly of silver thermal grease. What do people here think about
it?

Does it make sense to use bulk thermal grease? Or is a single use
syringe the best way to go?

Thank you.

--

( \_/ )
(='-'=) Don Kuenz
(")_(")

[Ian Malcolm]

Don Kuenz <gar...@crcomp.net> wrote in news:m5i4q1$obk$1...@dont-email.me:

>
> Greetings,
>
> This post is about thermal grease for processors. Many PC technicians
> think highly of silver thermal grease. What do people here think about
> it?
>
> Does it make sense to use bulk thermal grease? Or is a single use
> syringe the best way to go?
>
> Thank you.
>

<http://www.dansdata.com/goop.htm>

Just about any reputable brand of thermal transfer grease sold in bulk
for general eectronics use will do fine if properly applied.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & >32K emails --> NUL

[N_Cook]

Whichever you use, the absolute minimum you can deliver, not dollops of
it by the handfull. Its only to fill any microscopic holes, any excess
,over that ,can only reduce thermal conduction if the excess is not
squeezed out, so why place it there initially.

[Jeff Liebermann]

On Mon, 1 Dec 2014 16:25:57 +0000 (UTC), Don Kuenz
<gar...@crcomp.net> wrote:

>This post is about thermal grease for processors. Many PC technicians
>think highly of silver thermal grease. What do people here think about
>it?

I currently use Arctic Silver because I inherited a box of the stuff
from a shop that went out of business. My guess is that I have more
than a lifetime supply because I use it VERY sparingly. The idea is
to just fill in the cracks and gouges in the heat sink, not plaster
the CPU or heatsink with a thick layer. More goop is NOT better. I'll
guess that one tube lasts me about 12 Pentium 4 size CPUs. I apply a
tiny blob of the stuff to the CPU, and smear it around with a plastic
spatula until the entire surface is coated and that there are no lumps
or blank areas.

I've also experimented with tooth paste, Vaseline, powdered aluminum
suspended in vegetable oil, and other concoctions. Everything works
with only subtle differences in CPU operating temperatures.

I also spent some time testing how a polished aluminum heat sink works
against a polished CPU. The results were better than with Arctic
Silver but had a problem. After a few months of operation, they would
overheat. What was happening was the heat sink was expanding and
contracting irregularly and would temporarily open a crack between the
CPU and heatsink. Dust would get into this crack an create a tiny air
gap, which was sufficient to ruin the cooling. With a heat sink that
is tightly clamped down, this will not happen, but with the very loose
cam clamps used by Dell in some of their early Optiplex motherboards,
it became a problem.

>Does it make sense to use bulk thermal grease? Or is a single use
>syringe the best way to go?

I have some while silicon grease in a tooth paste size tube. I think
it's at least 20 years old and is maybe 1/4th used. It really depends
on how many CPU's will need grease. Adjust your quantities
accordingly.

Incidentally, if you read the Arctic Silver instructions, they mumble
something about the conductivity improving after the machine has been
used for a while. That's true because the volatile oils, that make
the silver dust flow, need to evaporate. If you leave the stuff open
to the air, you'll end up with an unspreadable lump. Therefore, most
such compounds need to tubes or syringes of some sort.

Don't forget to clean off the old grease and goo with some solvent
before applying the new stuff.


--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

[Michael Black]

On Mon, 1 Dec 2014, Don Kuenz wrote:

>
> Greetings,
>
> This post is about thermal grease for processors. Many PC technicians
> think highly of silver thermal grease. What do people here think about
> it?
>

Do they? I don't know, but people who put together their own computers
aren't "computer builders" they often follow instructions and have no
deeper grasp. So once something falls into their view, they may become
insistent, whether or not there is any value to a given product. They
may not have even tried anything else, but since it works they soak in the
marketing around the product, and repeat it.

They may be quite insistent on things, yet if things don't go well, they
are lost. Something to cnsider.

Endless things are assembled with "everyday thermal grease" and no
problems arise. That's an important thing to consider.

> Does it make sense to use bulk thermal grease? Or is a
single use > syringe the best way to go?
>

I think the single use packets exist because for most people, the only
time they'll need it is when putting together a computer. it's convenient
and you can throw the package away later.

I can't imagine it's different from a larger tube. But for someone who
is only putting together a computer every few years, it may be cheaper to
get the smaller package, and then they don't have the tube around to just
sit there, or to figure out where they put it the next time they need it.

Michael

[larrymo...@my-deja.com]

On Monday, December 1, 2014 9:26:20 AM UTC-7, Don Kuenz wrote:

> Many PC technicians think highly of silver thermal grease.

Most PC technicians aren't nearly as skilled or knowledgeable
as electronics technicians.

The #1 maker/seller of silver grease, Arctic Silver, doesn't
seem to know very much about it, not even the maximum safe
voltage, but they did brag of it being used for IGBIs in
windmill electronics that ran at high voltage, despite
claiming that they didn't do any testing above 12 volts.

[isw]

In article <m5i4q1$obk$1...@dont-email.me>, Don Kuenz <gar...@crcomp.net>
wrote:

> Greetings,
>
> This post is about thermal grease for processors. Many PC technicians
> think highly of silver thermal grease. What do people here think about
> it?

You can find performance comparisons of various kinds of thermal
compounds online. I'd suggest a preference for tests *not* run by anyone
who has a horse in the race.

You'll probably find, as I did, that the product-to-product variations
are rather subtle.

Isaac

[N_Cook]

Similarly whenever you see test results for the related product silipads
you never see the companies' products cross-compared with mica slips.
Mica is non-patentable and dirt cheap with the technical advantage it
does not creep , so does loose functionality over time and heat-cycling.
What limited in-service testing I've done , mica does a better job in
heat transfer, let alone longevity advantage

[William Sommerwerck]

Mica also has the advantage of being non-conductive.

You would never want to use conductive thermal grease //by itself// when
attaching a device directly to a metal heat sink. At least, I don't think so.

[Don Kuenz]

Ian Malcolm <See.My.Sig...@totally.invalid> wrote:
> Don Kuenz <gar...@crcomp.net> wrote in news:m5i4q1$obk$1...@dont-email.me:
>
>>
>> Greetings,
>>
>> This post is about thermal grease for processors. Many PC technicians
>> think highly of silver thermal grease. What do people here think about
>> it?
>>
>> Does it make sense to use bulk thermal grease? Or is a single use
>> syringe the best way to go?
>>
>> Thank you.
>>
>
> <http://www.dansdata.com/goop.htm>
>
> Just about any reputable brand of thermal transfer grease sold in bulk
> for general eectronics use will do fine if properly applied.

I want to thank everybody for their answers to my question. It looks
like Dan put a lot of effort into creating the above web page, which
compares thermal compounds. My takeaway from both that page and this
discussion is that there is little measurable difference between
commercial grade compounds.

Dan mentions Cooler Master on his page. Cooler Master offers a 200G tub
of compound under the SKU of RG-ICFN-200G-B1. It seems to meet the needs
of my business. It apparently comes with a credit card applicator to use
instead of a syringe.

FWIW, all of the hundreds (thousands?) of motherboards and coolers that
I've worked on over the years (decades) always used grey compound. Not
one of them ever used zinc oxide.

There's the right way, the wrong way, and the Intel way of doing things.
Doing it the Intel way works for me. Intel coolers come with a square of
grey compound pre-applied. Intel warranty exchanges come with a syringe
of grey compound when applicable.

Delta once had me swap out a few Dell motherboards at the local airport.
The new motherboards each came with a syringe of grey compound. They
also came with a pad coated with a chemical to remove the old compound
in a single step process. Whatever was in that pad was corrosive enough
to immediately start burning my bare skin.

Such are the hazards of service work. I always keep lots of vinyl,
latex, nitrile gloves around these days. Never again will any chemical
touch my bare skin.

In lieu of hazardous-to-your-health pads I use ArctiClean in my
business. ArcticClean uses a two step process. In the first step a mild
corrosive is applied. It smells of oranges and is probably acetic acid.
In the second step a neutralizing agent is applied to stop the acidic
reaction.

[Jeff Liebermann]

On Tue, 2 Dec 2014 17:43:44 +0000 (UTC), Don Kuenz
<gar...@crcomp.net> wrote:

>FWIW, all of the hundreds (thousands?) of motherboards and coolers that
>I've worked on over the years (decades) always used grey compound. Not
>one of them ever used zinc oxide.

<http://www.buildcomputers.net/cpu-thermal-paste.html>
The gray goo is some kind of metal (aluminum or silver) to provide the
thermal conductivity. The white stuff is a ceramic (aluminum oxide or
zinc oxide). Note the thermal conductivities:
<http://en.wikipedia.org/wiki/List_of_thermal_conductivities>
W/m*K
Metallic Silver 406 - 430
Metallic Aluminum 205 - 250
Aluminum Oxide 26 - 40
Zinc Oxide 21
The huge differences don't translate into spectacular differences in
final CPU temperature. That's because the thin layer of thermal
compound is tiny part of the thermal circuit. You could use butter
instead, and it will still sorta work. The thermal resistances are in
the range of 0.01 to 0.10 C/W. It's like building a 120VAC resistance
wall heater and then asking how much will the temperature drop if I
insert a very small value resistor in series. It's barely noticeable.

80-way Thermal Interface Material Performance Test (14 pages)
<http://archive.benchmarkreviews.com/index.php?option=com_content&task=view&id=150&Itemid=62>

Gotta run, I'm late. Also think about packing density, heat sink
warping, ductility, galling, viscosity, and re-usability.

[Don Kuenz]

Thank you Jeff for making me rethink my choice. Upon reflection it now
seems that Tgrease 2500 ( http://tinyurl.com/puj96hs ) best fits my
needs. It's silicon free and white (zinc?) with a thermal conductivity
of 3.8 W/mK. It comes in commercial sizes from 10cc to 10kg.

Intel may special order its grey compound directly from 3M or Dow. It
wouldn't be the first Intel part that's not available through retail
channels.

There's a controversy surrounding Arctic Silver 5's thermal conductivity.
The company claims 8.7 W/mK but another lab measured it at
0.94 W/mK. So it seems that Tgrease works better than the storied Arctic
Silver 5.

[Jeff Liebermann]

On Wed, 3 Dec 2014 03:42:43 +0000 (UTC), Don Kuenz
<gar...@crcomp.net> wrote:

>> Gotta run, I'm late. Also think about packing density, heat sink
>> warping, ductility, galling, viscosity, and re-usability.

I blew the clutch on my car. Wiped most of the day arranging for a
clutch transplant. It's now 8:30PM and I'm in the office trying to
catch up with promised work.

>Thank you Jeff for making me rethink my choice. Upon reflection it now
>seems that Tgrease 2500 ( http://tinyurl.com/puj96hs ) best fits my
>needs. It's silicon free and white (zinc?) with a thermal conductivity
>of 3.8 W/mK. It comes in commercial sizes from 10cc to 10kg.

What I basically said was that it really doesn't matter. Like real
resistors, the thermal resistances between a heat source and the
ambient air add to yield the total thermal resistance between the CPU
die and the ambient air. If you want real numbers, I can supply them.
Suffice to say that the thermal resistance of the other components of
the puzzle are much larger than the thermal resistance of the thermal
grease. Off the top of my head, I think the typical P4 CPU is about
0.5C/W and the common heat sink (without the fan) about 2C/W. In
between is the thermal goo, with optimistically about 0.05 C/W. Since
they all add up together, the contribution of the 0.05 C/W is trivial.
I could cut it to maybe 0.005 C/W by using diamond dust, and the total
thermal resistance will have hardly changed.

So, why all the fuss about the thermal grease? Because if there are
any voids, air gaps, misalignment, warp, or gaps between the CPU and
the heat sink, the thermal resistance goes from 0.05 C/W to something
10 or 100 times as large. Then it becomes really significant.

>Intel may special order its grey compound directly from 3M or Dow. It
>wouldn't be the first Intel part that's not available through retail
>channels.

Magic sauce. My guess is that it's more important for it to be
environmentally correct, worker safe, and of course, cheap.

>There's a controversy surrounding Arctic Silver 5's thermal conductivity.
>The company claims 8.7 W/mK but another lab measured it at
>0.94 W/mK. So it seems that Tgrease works better than the storied Arctic
>Silver 5.

Dunno. It's tricky to measure. The solvent in the Arctic Silver goo
does evaporate with time, which will certainly chance the thermal
conductivity.

More insanity:
<http://www.overclock.net/t/1369042/poll-how-many-of-you-ever-used-toothpaste-as-thermal-paste>

[Jeff Liebermann]

On Tue, 2 Dec 2014 05:53:37 -0800, "William Sommerwerck"
<grizzle...@comcast.net> wrote:

>Mica also has the advantage of being non-conductive.

It's not very flat and needs thermal goo on BOTH sides of the
insulator.

>You would never want to use conductive thermal grease //by itself// when
>attaching a device directly to a metal heat sink. At least, I don't think so.

I don't see why not. I commonly mount TO220 devices directly to a
heat sink with only a little thermal goo in between. The thermal goo
isn't going to act as a gap filler, but does help deal with uneven and
rough surfaces.

[John-Del]

On Wednesday, December 3, 2014 12:00:21 AM UTC-5, Jeff Liebermann wrote:
.
>
> >You would never want to use conductive thermal grease //by itself// when
> >attaching a device directly to a metal heat sink. At least, I don't think so.
>
> I don't see why not. I commonly mount TO220 devices directly to a
> heat sink with only a little thermal goo in between. The thermal goo
> isn't going to act as a gap filler, but does help deal with uneven and
> rough surfaces.

Probably referring to metal cased semis where the metal case is electrically connected to the device and needs an electrical barrier (like mica and plastic washers) to isolate it electrically. Years ago it was more common to find metal backed T0-220s or T0-3s that needed mica or silicon rubber. Today most semis are encapsulated and only need thermal goo to mount.

[Michael Black]

On Tue, 2 Dec 2014, Jeff Liebermann wrote:

> On Tue, 2 Dec 2014 05:53:37 -0800, "William Sommerwerck"
> <grizzle...@comcast.net> wrote:
>
>> Mica also has the advantage of being non-conductive.
>
> It's not very flat and needs thermal goo on BOTH sides of the
> insulator.
>
>> You would never want to use conductive thermal grease //by itself// when
>> attaching a device directly to a metal heat sink. At least, I don't think so.
>
> I don't see why not. I commonly mount TO220 devices directly to a
> heat sink with only a little thermal goo in between. The thermal goo
> isn't going to act as a gap filler, but does help deal with uneven and
> rough surfaces.
>

You used the mica washer to isolate the device from ground. You needed
good heat connection to the heatsink, but didn't want electrical. The
mica washer was to insulate, the thermal compound was to make sure things
made good thermal contact.

Michael

[gregz]

I started fixing an amp somebody was trying to fix. Without insulators on
the output transistors, it was never going to work.

Greg

[gghe...@gmail.com]

This is fun,
http://www.dansdata.com/goop.htm

How about some vegemite? :^)

George H.