So many recommendation ignore all specification numbers. Recommended are thermal compounds that put most of your money into advertising, hype, and other propaganda sources. Not in facts or into that thermal compound.

Relevant parameter measures thermal conductivity. Direct 'semiconductor to heatsink' interface is hundreds of W/K-m. What is that number for those highly promoted 'magic' thermal compounds? One is only 8.4 W/K-m.

That is more conductive than air (typically less than 1 W/K-m). So thermal compound is applied to only fill microscopic air gaps.

Heatsink is tapered and pressed hard on a semiconductor to squeeze thermal compound out (except in those microscopic gaps). Direct contact accounts for tens of degrees temperature reduction. Thermal compound is added to only reduce temperatures by a few (single digit) degrees more.

Really does not matter which thermal compound is used. Best is to buy same thermal compound that does not have hyped names (Kryonaut, Arctic Silver) so as to cost up to ten times more money. Only recommendation, that is not ignored, will cite relevant specification numbers (ie W/K-m).

Far more attention focuses on how well a heatsink is machined and mounted. So that direct contact to that semiconductor increases.

Another myth is drying. Thermal compound remains just as thermally conductive - wet or dry. It is originally wet so that a heatsink can sufficiently squeeze it out (except in those microscopic air gaps). So that compound does not obstruct what transfers most heat - direct contact. Once applied and properly squeezed out, then thermal compound remains just as thermally conductive even 20 years later.

More information discussed here.

This post has been edited by westom: Dec 23 2020, 04:04 AM