I noticed at some point that a keepout check box was added to the fill
properties.  I have long wanted to place a top or bottom only keepout in
between certain surface mount pads such that copper pours were prevented
from filling in between pads that had a layer specific keepout.

Unfortunately to make the keepout layer-specific the fill that will be
turned into a keepout must be on a single side layer, like Toplayer or
Topoverlay.  Unfortunately the fill must be associated with a conductive
layer to prevent polygons on that layer from over-running the
fill-made-keepout.  This now leaves a chunk of copper in between the pads in
place of the pour.  Better but not what is needed.

I thought of using very thin traces in the form of a rectangle with no net
to block the migration of the pour. Of course there would have to be a set
of rules written to keep the DRC happy.

Ideally we could make an all-sides keepout fill be layer specific by
selecting the desired layer in a "Constrain Keepout to a Specific Layer"
pull down but that does not exist yet.

Does anyone have any better ideas how to keep pours on a given layer from
passing through certain pads.  The solution should be able to be saved with
the footprint and should not involve using larger clearance rules.

The reason for this requirement is to keep the copper from between surface
mount pads when using circuit board routers to prototype SMT boards. Since
solder masking is typically not used with this type of prototype, copper
under components like caps and resistors can lead to shorts from paste
reflow.  The selective keepout would prevent the polygon from getting under
some of these small components.

Charlie Jenkins, Pioneer

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