More editable solder mask

[xultz]

Today it is possible only to increase/decrease the
clearance area between a pin in the soldermask
(selectin Show Soldremask on the Screen Tab), but
sometimes it is important to make some work on the
solder mask. Like, if I have a TO220 series regulator,
like 7805 mounted layered with the board, it is a good
idea to draw a great polygon below him to make heat
dissipation, but to do it the area below him must not
have soldermask, so the component get directly in
contact with these ground area. Today, I make it by
editing the postscript output in sketch, but I cant do
it with the gerber output.
The idea is to draw rectangules, polygons, and maybe
lines too, that makes a XOR with the soldermak.
To make it, it would be nice to make the soldermask
translucent, like with the option in the pcb rc file,
that makes the opposite side translucent.
It is important to have lines to edit the soldermask,
because sometimes it is needed to remove the soldermask
from above a line, so in the hot air process the line
receives some solder in it, and increases the current
capabilty.

[haceaton (haceaton)]

Yikes! Increasing current capacity with solder?! For the
TO220, simply include a SMD pad in the component definition
so that you get a copper area under the tab, then you will
be able to adjust the solder mask as well. If you really,
really need to draw the solder mask, consider drawing what
you want on an unused layer and making that your mask file.

[haceaton (haceaton)]

If you want to draw arbitrary lines on the solder mask
another thing you can do is to draw a track and convert it
to an element. That actually makes sense for increasing
current carrying ability with hot-air solder. It really
becomes an element then. Once the track is an element (with
a single SMD pad), you can play with
the soldermask relief.

[Colin D Bennett (colinb)]

It is possible to do some fancier solder mask openings by overlaying SMD pads with different settings. For instance, I have an LED footprint that has large copper pads for heat transfer, but a small opening in the solder mask to assist in clean soldering.

Overlaying SMD pads is a very versatile kludge that isn't perfect, but with a bit of effort you can do almost anything.