Heatsink grease

[Andrew W. Macfadyen]

Anything you could apply would tend to lower the  overal heat transfer
coefficeient hence reduce the heat transfer. Black anodised finishes are
ok because they are not a paint but a dye  applied to the porrus oxide
surface layer of the alloy.

Apart from using a fan and or Peltier effect heat pump the only real way
is by using a bigger heat sink bonded on to the semi conductor using a
special bonding compound.

For good heat transfer any layer of bonding compound or grease between
the
heat sink and the semiconductor should be as thin as possible.

Apart from having a large surface area good heat sink design should be
of
a  thick crossection where it makes conact with the semiconducter, and
at
the base of the fins.

With fans it is more important to blow air over the whole of the heat
sink
than to move the air at high speed but leave a hot spo, this is a fault
seen in most  Pentium CPU heat sink fans which don't cool the hottest
part
of the CPU well.

Chris Conlon wrote:

> Apologies for the vaguely-efi content,
>
> There are several greases designed to increase heat flow between (say)
> a transistor and a heatsink; are there compounds to increase heat flow
> between a heat sink and air? I know you can paint it black, but I'm
> talking about convective heat flow, not radiative.
>
>    TIA,
>    Chris C.