There are accountable reasons why PC boards heat up. Usually it is
because the designer
did not take into consideration how much current various traces on the board
need to carry. There are formulas and calculations that the "pros" use
to design
high current carrying PC boards, especially in laying out power supply
boards.
With 2 oz copper, and proper design, one can make boards that can carry
a lot of current. I don't have a good feeling for what increasing the
thickness
of the substrate would do to make a properly designed PC board dissipate
more heat. Epoxy-glass is not a very good heat conductor.
Heat sinks and fans usually handle heating problems, along with
properly engineered circuit trace widths..
Epoxy systems generally "decompose" when exposed to high temperatures,
and applying heat is a quick and dirty way of breaking down an epoxy bond.
I suspect that there are some toxic fumes emitted when epoxy systems are
decomposed via the application on intense heat.
Roland F. Harriston
∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗∗
DJ Delorie wrote:
>
>
> "Stefan Trethan" <stefan_trethan@...
> <mailto:stefan_trethan%40gmx.at>> writes:
> > Why do you get that impression?
>
> >From all the stories of motor mounts that fail due to epoxy softening.
> And from my dad telling me to use a torch to remove epoxy plugs from
> car parts. And from HowItWorks showing heat-softened epoxy sheets
> used for vacuum forming.
>
> Yes, if a pcb gets that hot, something else is usually wrong. But if
> you're suing 2oz copper and 1/8 boards, I'm guessing you're probably
> concerned about heat anyway.
>
> My only point is, if you're concerned about heat, be careful about the
> adhesive you use.
>
>
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