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Date:	Thu, 10 Sep 2015 22:16:48 +0000
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Subject:	Re: [geda-user] 5630 LED footprint
From:	"Evan Foss (evanfoss AT gmail DOT com) [via geda-user AT delorie DOT com]" <geda-user AT delorie DOT com>
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On Thu, Sep 10, 2015 at 10:07 PM, DJ Delorie <dj AT delorie DOT com> wrote:
>
>> > Usually thermal relief is added to ease hand soldering but it will
>> > also make it a very bad heat sink. I guess you have to chose
>> > between either hand soldering or heat sink.
>>
>> Nicklas : That would defeat the point of using holes (vias really) and
>> pads to heat sink the LED.
>
> I've done embedded pad soldering from the back with one large plated
> hole.  It took care to get enough heat in without toasting the chip.
> IIRC I filled the hole with first flux then solder paste, so it would
> be done as soon as enough heat was present.
>
>> What you want to do is have tons of vias and peel back the mask to
>> expose more copper to remove the most heat possible.
>
> It's debatable whether bare (shiny) copper or soldermask can dissipate
> heat better.  I've heard both ways, although I'm partial to the
> argument that a matte black mask would be the best emitter.

I would think there would be someone who has tested this. I use a fair
number of linear regulators and things that depend on PCB heatsinks. I
think the data sheet for the last one suggested removing the mask.

I see your point about black body emission.

-- 
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