Quote Originally Posted by FUGGER View Post
Jon, have time to do a spring loaded test?

Contact pressure is important and may skew results a bit as thickness of the TIM may vary. .

Side note:
IT outlet in Taiwan has more TIM variation than we could ever name.
Spring load is a great point as continuous pressure helps the compound resolve down to it's bond line thickness or average particle size.

With screws alone you hit a point where it feels secure - the screws are set at a position that does not move and now when you apply heat the paste continues to flow leaving a light contact or gap and should be re-torqued like the head gasket on old cars to get the proper contact.

Here is one where the end user used a torque wrench to get a calibrated pressure. Great way to maximize temp performance

http://www.evga.com/forums/tm.aspx?m=681429

Also you can do a room temperature test to indicate whether a compound has reached it's Bond Line Thickness (BLT) as a general guide By taking an IHS Sized piece of metal between 2 pieces of glass, apply the compound with 4 binder clips @ approx 50 -60 psi and use a micrometer at timed intervals 1 min, 5 min, 10 min, 30 min, 1 hr, 2 hr. to mic the thickness and time to spread or resolve down to it optimal limit.

I found that 2hours @ cold or ambient room had most compounds at near the BLT in 2 -3 hours with maybe a minor improvement overnight with constant pressure @ 60 psi. If your are subzeroing compounds a pre cure would be in order otherwise the compound would possibly harden at a thicker BLT if it is cooled before it has a chance to spread.