Its a shame these devices do not have a thermal mounting point to enable the
metal case to cool it.
I think from experience matt black paint does insulate but can also get hot
in itself. To be of any use it needs to be part of the material and share
its thermal qualities.

Brian

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This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"T i m" wrote in message
...
Hi all,

I have some neat extruded ally cases for my std Raspberry Pi's and I
was about to put my new 3B+ in one and wondered, because it seems to
get the warmest of all the Pi's so far ... if the interior finish
(shiny / matt) / colour (white to matt black) would make any
difference to how efficiently the case would re-radiate the (Pi) heat?

eg, If we assume the case is sealed (it isn't but doesn't have much in
the way of airflow) then the heat coming off the Pi to the inside of
the case would be direct in the form of radiation ... and indirect by
the way of conduction from the warm air, that distributed /
transferred via convection to the inside of the case (and hence via
conduction to the outside etc).

So, the case has a slightly shot blasted / gold anodised finish
throughout and I was wondering if painting the inside matt black (acid
etch spray primer and matt black spray) would have any cooling
advantage at all or would it in fact actually make matters worse
because the paint would act like a thermal barrier?

I'm pretty sure the Pi would survive irrespective as I believe it has
the ability to clock-throttle when it overheats but equally if you can
help it run 'cool' it will run at full speed for (and possibly last a
bit) longer?

I did consider making up a heat-pipe (a 'U' shaped copper strip)
allowing me to conduct heat from the main chip to the case but that
requires a bit more 'engineering'. ;-)

I've ordered the one of the little 3 x heatsink kits that may add a
little thermal capacity (to the chips) and the ability to conduct the
heat away from the chips themselves more efficiently but that may only
slow the raise in temperature of the chips but could increase the
speed the inside of the case is heated, especially if it runs longer
before throttling?

Anyone confirm the practical science behind it all please?

Cheers, T i m