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really proper way to apply thermal compound?
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coppercone2:
I still think the glue is a true solution but the other stuff is a colloid at best.
DaJMasta:
As for checking for air gaps, using regular thermal material will generally show you the outline of the bubble when you remove it to reset it, but I'm not sure how to know before you remove it aside from seeing a temperature that's too high and deciding there was probably a problem with the application.

Most of the reason commercial products or coolers with TIM pre applied come with the thick sheet of heatsink compound (which is often internally reinforced with a mesh) is that the thickness and width ensure a fairly even, full coverage installation.  I think virtually none of the time it's the ideal low thermal resistance connection, but it is consistently reliable at making a decent connection, so if the rest of the thermal design is done around that assumption, automated assembly or end-user assembly and all its variables can still get reliably good results.
Nerull:
These guys tested several application methods and found differences of a fraction of a degree on high-wattage CPU applications.



People obsess over methods of thermal compound application but real word differences seem minimal to non-existent.
thermistor-guy:

--- Quote from: Nerull on December 10, 2018, 04:09:05 am ---...
People obsess over methods of thermal compound application but real word differences seem minimal to non-existent.

--- End quote ---

I change the CPU/GPU paste on several computers every few years, either because of an upgrade or just regular preventative maintenance.

I use Arctic Silver, and the 2-part Arctic Clean. My steps are, using gloves throughout:

* clean the surfaces gently but thoroughly with cotton buds, and then lint-free laboratory wipes (Kimwipes or similar;
* let dry for at least 30 minutes;
* apply the paste to the CPU with a glossy business card (new in box, untouched); spread in X, Y, and X-Y directions so it's a thin even coat;
I don't use the edge, I bow the card in half and use the soft bend as the spreading surface;
* install the heatsink; this step usually squishes the paste a little but not much;
* run a thermal benchmark, to test the installation.

What I find, each maintentance cycle, is that the previous coating was quite even with no obvious voids, and the benchhmark gives reasonable temperatures
on the fully loaded system.

So yes, do it with care - don't scratch the surfaces, and do a proper clean - but don't obsess either.
TERRA Operative:
A good way to ensure even coverage and exclude air is to apply the thermal paste in an 'X' pattern then clamp the heatsink on.
This will make sure the thermal paste reaches the edges but won't capture air.

On the other hand, ESAB welders specify to apply a small amount of heatsink compound then dab it around with the flat end of a small foam paint roller until a thin even coating is achieved. They even supply the paint roller with the tube of thermal paste in the kit.
If that process is good for IGBT modules passing hundreds of amps, I'm sure it'll be ok for a CPU or vreg etc.

On the topic of lapping, apparently 1200 grit emery paper leaves grooves that are approximately the same size as the silver particulates in Arctic Silver 5 thermal paste. Anecdotally, this should mean the silver is able to more effectively fill the gaps and make a close thermal interface.
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