Thermally conductive potting compounds provide an efficient pathway for heat to travel uniformly away from a heat-generating source to a metal enclosure or to air.
What is electrical potting?
Potting is a process of filling a complete electronic assembly with a compound for resistance to shock and vibration, and for exclusion of moisture and corrosive.
How strong is thermal adhesive?
3M claims a thermal conductive epoxy with 0.72, but this is not much better than average plastic around 0.3 to 0.5. The important thing is that these are all 100 times more conductive than air, and they fill the gap eliminating the air.