Maker Pro
Maker Pro

Thermal Grease/Adhesive (?)

A

Arfa Daily

Jan 1, 1970
0
Geoff Wood said:
One of my worst ever !

g.

Years ago ( Jesus, about 40 actually ... ) a buddy of mine in chemistry
class, got asked by the teacher, what the chemical symbol ' Sn ' was. Quick
as a flash, he said " Silicon, sir ! "

After a suitable pause, the teacher said " Aye, Smith, you really are a
silicon, aren't you ... ? "

His name wasn't actually Smith ...

Arfa |:-o
 
Shouldn't be an issue with the voltages one would expect to see in a
transistor amp. Cheap white compound will dry out over time and lose its
effectiveness, whereas something like arctic silver shouldn't. I wouldn't
necessarily recommend silver loaded compound mind, but I see no reason not
to use it for this kind of job. It's possible in this case that the
transistor is directly mounted anyway, ie without an insulating pad.

I have a Leach audio amplifier built in the 1970s, and a few years ago
its Radio Shack or GC silicone grease hadn't dried out. So I wouldn't
worry about this, and I don't see why Arctic Silver would be more
resistant to drying out (it may use ester instead of silicone grease).
 
D

Dave D

Jan 1, 1970
0
I have a Leach audio amplifier built in the 1970s, and a few years ago
its Radio Shack or GC silicone grease hadn't dried out. So I wouldn't
worry about this,

It depends on how hot the semicondictor runs. It's possible the
effectiveness of thermal compound can deteriorate as it changes state.
and I don't see why Arctic Silver would be more
resistant to drying out (it may use ester instead of silicone grease).

It is based on polysynthetic oils. The manufacturers apparently claim it
won't dry out, and my experience with it certainly backs their claims up- I
have never seen dried Arctic Silver.

In any case, I am not advising anyone to rush out and buy Arctic Silver for
electronic work. I merely meant that for the OP's purposes, any form of
thermal compound he could get his hands on would do the job. Plain old
white, silver, whatever. Many people build their own PCs these days, so I
thought perhaps he may have a tube of CPU compound lying around, or have a
nearby computer shop he could get it from.

Dave
 
G

GregS

Jan 1, 1970
0
I have a Leach audio amplifier built in the 1970s, and a few years ago
its Radio Shack or GC silicone grease hadn't dried out. So I wouldn't
worry about this, and I don't see why Arctic Silver would be more
resistant to drying out (it may use ester instead of silicone grease).

I have seen the white stuff dry out plenty of times. Its sure easy to
spot and feel. If you can't smear it then it must be removed.
If its still good, I would just even out the stuff and reapply components.

greg
 
R

Richard Crowley

Jan 1, 1970
0
"GregS" wrote ...
I have seen the white stuff dry out plenty of times. Its sure easy to
spot and feel. If you can't smear it then it must be removed.
If its still good, I would just even out the stuff and reapply
components.

I agree in theory. But in practice, thermal grease is so
cheap compared to what it prevents that it is foolish
economy IMHO.
 
A

Arny Krueger

Jan 1, 1970
0
Richard Crowley said:
"GregS" wrote ...

I agree in theory. But in practice, thermal grease is so
cheap compared to what it prevents that it is foolish
economy IMHO.

Agreed.

If there is some small particle in the thermal compound, it
would separate the component from the heatsink and could
dramatically decrease cooling.

The best plan is to carefully clean both surfaces and use
new, clean compound.
 
G

GregS

Jan 1, 1970
0
Agreed.

If there is some small particle in the thermal compound, it
would separate the component from the heatsink and could
dramatically decrease cooling.

The best plan is to carefully clean both surfaces and use
new, clean compound.

I was building amps from STK modules. I studied the mating surfaces.
Ideally metal to metal contact is best, even the anodized surfaces
should be milled down. So I was taking the STK module and
sanding it down flat. It really wasn't very flat. I had to start out
with a flat surface for the sandpaper! After much work, I got it
to the point I felt was OK. Even a flat etched surface is worse than a mirrored
flat surface. Very very little grease is needed if everything is smooth and flat.

greg
 
C

clifto

Jan 1, 1970
0
GregS said:
I have seen the white stuff dry out plenty of times. Its sure easy to
spot and feel. If you can't smear it then it must be removed.

I noticed the CPU temperature on my main computer going a bit high a few
months ago. I checked, and sure enough the heat sink grease had dried
out. Replaced it and all was well.
If its still good, I would just even out the stuff and reapply components.

Disagree. Where it's needed, it's critical; it's cheap enough that
replacing it in critical places is well worth while.
 
G

Geoff Wood

Jan 1, 1970
0
GregS said:
I was building amps from STK modules. I studied the mating surfaces.
Ideally metal to metal contact is best, even the anodized surfaces
should be milled down. So I was taking the STK module and
sanding it down flat. It really wasn't very flat. I had to start out
with a flat surface for the sandpaper! After much work, I got it
to the point I felt was OK. Even a flat etched surface is worse than a
mirrored
flat surface. Very very little grease is needed if everything is smooth
and flat.


They don't suffer from thermal problem when mounted conventionally, with a
dab of heatsink compound, so why bother ?!!!

All a bit OTT consuidering the STK modules don't sound that great in the
first place.

geoff
 
G

GregS

Jan 1, 1970
0
They don't suffer from thermal problem when mounted conventionally, with a
dab of heatsink compound, so why bother ?!!!

All a bit OTT consuidering the STK modules don't sound that great in the
first place.

geoff

Sounds good enough for the common man. Running the 200 watt modules,
now extinct, but rugged as hell. I ran at reduced voltage for 200 watts at 4 ohms.
I was actually driving nearer 3 ohms at one time.

greg
 
G

GregS

Jan 1, 1970
0
I noticed the CPU temperature on my main computer going a bit high a few
months ago. I checked, and sure enough the heat sink grease had dried
out. Replaced it and all was well.


Disagree. Where it's needed, it's critical; it's cheap enough that
replacing it in critical places is well worth while.

i suppose the fluid helps to also fill in gaps having to fit into the compound mix
of dry materials. Having dried out may not always be a problem. There should be very little actual
compound that sits between flat surfaces. Its almost totally trapped in. if the surfaces
are poor, and the strength of the compression is poor, I think it would dry
out quicker. Probably a good choice for gasket type pads.

greg
 
J

Jim Yanik

Jan 1, 1970
0
"GregS" wrote ...

I agree in theory. But in practice, thermal grease is so
cheap compared to what it prevents that it is foolish
economy IMHO.

What dries out (white stuff) is not the thermal conducting material.
It should be reapplied solely for best thermal contact.
And the thinnest,most even layer is most optimal.
 
R

Richard Crowley

Jan 1, 1970
0
If John McCain gets the 2008 Republican Presidential nomination,
my vote for President will be a write-in for Jiang Zemin.

Makes me feel good that Usenet is available even to the insane.
 
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