Alternative to heatsink compound for cheapskates... Vote!

[Turbo DV8]

So, I need a smudge of heat sink compound under my SSC star, but I don't feel like going to Fry's and buying a whole crapload of the stuff. I have in my garage two potential compounds which I would like to share with you and get your opinions on regarding suitability for use as a heat sink compound. You may vote which you would guess to be the better of the two, or give your reasons why you feel one or both should not be used.

First is Permatex anti-seize lubricant. It is a thin petroleum based grease with a high metal content of what appears to be aluminum powder, or some other such aluminum-colored metal powder.

The second candidate is Permatex ultra disc brake caliper lube. This is a silicone based lubricant with molybdenum added.

Which would be best for a hopeless cheap-*** to use for heat sink compound? What is the base for a dedicated heat sink compound? And please do not say, "Just go out and buy some real heat sink compound!" If I did that, I just wouldn't feel resourceful!

 

[WNG]

I have used Permatex anti-seize compound (aluminum based) as a cpu heatsink compound. And it works fine. I wanted to test whether it can be used as a substitute to silicone heatsink compound. I didn't see a rise in temps from the cpu thermistor.
It works fine in my experiment.

Go to Permatex's website for more specifications on their anti-seize compounds. Their copper based one can handle higher temps.

Only issue may be the organic lubricant carrier is low viscosity, may get runny in very high temps. Too bad it doesn't come with a silicone based lube instead.
Also being aluminum powder, may be conductive if improperly used.


Their disc brake lube is a silicone grease. Very viscous and tacky to resist oxidation by brake heat and wash out by water spray. But it may not have heat transfer characteristics of a compound due to lack of suspended heat transfering particles.

 

[Turbo DV8]

Their disc brake lube is a silicone grease. But it may not have heat transfer characteristics of a compound due to lack of suspended heat transfering particles.

Yes, the anti-seize you can see begin to separate slightly even in the bottle into it's oil and aluminum consitituents. It must be stirred up well before use. It does say "resists temperatures up to 1600 F" but I suppose this does not mean it can't get real runny in the process.

Now, the silicone disc brake lube says resists temperatures up to 550 F, but it is a much thicker consistency to begin with. I guess the question is, what are the thermal heat transfer characteristics of the molybdenum that is suspended in the silicone?

Well, I did a little search, and found that both silicone and molybdenum are used for their thermal conductivity in heatsinks, so I think I will go with the caliper lube. I also found this:

During the early construction of nuclear power plants, steam condensers relied upon copper base alloys – brass and copper nickel – for heat transfer capabilities. These alloys have high coefficients of thermal conductivity required in steam generation to power nuclear reactor turbines. But copper-alloyed tubes were being replaced too quickly – with an average life of eight years – because of sulphide pitting. Hardest hit were those reactors using polluted seawater to cool their reactors.

Over the past 30 years ago, nuclear utilities slowly began turning to the super austenitic stainless steels as one way to make their nuclear reactors last longer. The addition of molybdenum, initially starting with percentage of less than four percent, helped increase the thermal conductivity lacking in nickel, iron or steel. At nuclear stations which replaced the copper alloys with HPSS condenser tubes, 57 percent rated the thermal performance good and all but one rated it normal. Molybdenum had helped overcome the thermal hurdle.

 

[joecarrow]

They're talking about molybdenum in a steel alloy. I wouldn't worry about the content of what you're using, just use something that will stay put when it heats up, and won't break down over time.

Just remember- the principle purpose of thermal compound is to fill the gaps between the heat sink and the heat source. Whatever goop you put in there, even if it's $30/oz nano-whatever-silver, is going to act as an insulator compared to solid aluminum or copper. The best connection to your heat sink that you can make would have no grease at all, just two perfectly flat surfaces. I've personally made a heat sink that I bought for a PC for $6 work like a $50 heat sink just by lapping the surface to a mirror finish.

My advice- don't go to Fry's, go to Radio Shack. They have lithium grease for less than $2 per tube. I don't know what it's temperature limit is, or what your application is, but most LEDs shouldn't be operated much over 100 Celsius anyway.

 

[DrifT3R]

apparnatly toothpaste mixed with some sort of oil works well.

 

[LED Zeppelin]

If those are your only two choices, I'd go with the caliper lube. I have various tubes and bottles of Never Seize and it will separate over time, and part of it is clear and runny. It will definitely make a mess and run out.

If the caliper lube is the blue stuff I've used, it doesn't seem to get runny, it's very tacky and consistent.

I have some (0.23 oz. tube nearly full) Radio Shack sililcone based heatsink compound I can send you if you PM me your mailing address. I switched to Arctic from the Shoppe and don't use it anymore.

 

[EngrPaul]

Permatex anti-seize (for spark plugs) would be my choice.

Avoid silicone products, they can make the inside of your lens foggy.

 

[bfg9000]

As far as performance goes, pretty much anything will work well--even Vegemite or toothpaste.

The difference is for how long. Plain white thermal grease is generally zinc oxide in silicone carrier oil. It's not that it dries out, but repeated heat cycling will eventually cause the silicone oil to ooze from the interface and leave a dry powder that does not work as well. And that's a product specifically designed for such use...

 

[ErickThakrar]

Seriously, just go buy the right stuff. Not like you won't ever use it again and why gamble with the components for a few dollars worth?

 

[Psycan]

ANY decent grease will work. I have used automotive bearing grease and Vaseline. Don't even have to worry about it melting and running because you are putting the thinnest possible layer on. You want metal to metal contact of the peaks on your two surfaces and the grease just fills in the pits. The more liquid it is, the better it transfers heat.