"Serge Auckland" wrote in message
...
"Gareth Magennis" wrote in message
news
Am I right in my belief that putting heatsink compound on silicon pads
gives less thermal conductivity than pads alone?
Cheers,
Gareth.
My understanding is that thermal compound couples the bottom of the device
to the heatsink by filling-in the tiny interstices that would otherwise
exist between the slightly rough device and the slightly rough heatsink.
Consequently, heat is conducted better than it would be if the device were
clamped directly to the heatsink.
My understanding was that silicon pads already have the optimum contact with
both surfaces due to their squidginess. Putting 2 layers of thermal
compound with less than 100% thermal conductivity between them is only going
to make things worse.
I just seem to remember reading something about this somewhere, but that
does not of course make it true.
Gareth.