Homebrew PCBs

Nah, doesn't fit.

If i heat with hot air from above the powdery stuff must be hotter than  
the board.

ST


On Mon, 21 Nov 2005 21:46:59 +0100, Alan King <alan@...> wrote:

>
>
>   Think of having your board right at the melt point, and taking a solid
>
> lead pencil and writing on the traces.  Pencil stays solid, but where
>
> you're touching the traces is melting.  Traces are above the melt temp,
>
> but you're only getting melt when you make it touch.  For sure it is
>
> melting some, just not a lot.  Remember it takes a lot more energy for
>
> the phase change, so right near the melt temp you'll melt the surface
>
> but not have near enough extra heat to melt the rest of the solder
>
> balls.  Might also be doing something with the flux at a higher temp, as
>
> someone else noted recently it stays on much longer just at the melt  
> temp..
>
>
>   Think of how you draw on your iron tip with solder, as the iron is
>
> just heating up, leaves a nice shiny path.  And won't melt the rest of
>
> the solder very fast yet, because it doesn't have enough extra heat.
>
>
>   Things well above the melt temp uaually oxidize much faster than
>
> things right at it, part of the reason a temp controlled soldering iron
>
> is a good thing too..
>
>
> Alan
>