At 12:25 PM 8/20/2013, neil n wrote:
>between these parts. Too much paste might, to some degree, insulate
>each part from the other.

No "might" about it.  The dirty little secret of heat-conducting
paste is that it's a pretty good insulator.  If you use more than the
absolute bare minimum it will be worse than using none at all.

What it's supposed to do is fill in the microscopic voids between the
high spots where the metal actually touches.  There's a lot more void
area than contact area even on extremely smooth metal.  The ideal
installation would have all the voids filled but still have the high
spots touching.  This is practically impossible, but it's what you're
shooting for.

That's also the reason for the high clamping pressures on computer
CPUs and such, to squeeze out excess paste as much as possible.

Likewise why you shouldn't re-use the stuff after it's had the goo
squeezed out of it.  Clean it all off and start over.

Yours,
David