Re: Best heat sink compound?

On Tue, 2 Dec 2003 13:30:40 +0100, "Frithiof Andreas Jensen"
<[EMAIL PROTECTED]> wrote:

>
>"John Larkin" <[EMAIL PROTECTED]> wrote in
>message news:[EMAIL PROTECTED]
>
>
>> The white thermal compound stuff is better. For serious heat sinking,
>
>It sucks in production and it sucks during servicing - the Warth et. al.
>thermal pads handles much, much better (and if you cannot get the heat out
>with that, you are cutting it too close anyway).
>
>>   don't use an insulator. If you must, use 0.5 mil
>>   hard anodize on the heat sink.
>
>hehe - above 60 V you *must* use an insulator if the heat-sink is accessible
>to the user - 

The hard anodize *is* the insulator, with a thermal resistance a tiny
fraction of a sil-pad's. If the heatsink is properly grounded to the
chassis, it's safe even if an insulator - any insulator - fails.

>besides I would not trust the anodising at all: One tiny piece
>of burr under the device; Boom! This *will* happen in a production
>environment..
>

A burr will punch through a sil-pad as well. Don't have them.
Interestingly, the hard anodize process etches the aluminum nicely...
it's a soft-looking, very smooth and pretty finish, and hard as glass.
If you take your sharpest meter probes and push as hard as you can,
you'll just measure infinity ohms on a properly hard-anodized heat
sink.


>>   *don't* use a silicone sil-pad or phase-change stuff.
>>   They are both awful thermally.
>
>No, Not Really - especially if the device is fixed with a clip instead of
>that silly screw/washer combo.

Do the math. Numbers beat opinions every time.

John