gEDA-user: gPCB Polygon Best Practices

["Jeff VR" <jffvnrkl@xxxxxxxxx>]

I spent the past few month becoming familiar with PCB and after
finishing my schematic in gschem I'm ready to start the layout.
Hooray!  I've got a fairly good handle on the basics but there are few
areas that I need a little assistance/guidance.  The first is getting
polygons and lines to play nicely together.  My plan is to try and get
my design on a 2 layer board.  I've spent a lot of time arranging
components to make routing as painless as possible.  If I can get away
with 2 layers I want a GND plane on the bottom layer which will be
split up by traces that just couldn't fit on the components side of
the board.  So I did some practicing and drew a line for on the solder
side of the board.  Afterwards I drew a large rectangle(polygon) on
the solder side when I had GND_SLDR chosen .  I then figured out that
<key>j enforced the clearances around the line and nicely removed the
GND polygon from the trace.

Problems/Questions:
1. Even after the polygon was cleared from the trace the rat's nest
was claiming that the net associated with the trace on solder side was
shorting with GND???  I remove the trace and the error goes away...if
I leave the trace and remvoe the GND plane the error goes away.  How
do I figure out what is wrong when visually the GND polygon is
clearing the net?

2. Should I draw the GND plane at the beginning or should it be the last step?

3. I have unplated holes on one of my symbols that is enforcing a
clearance on the component side but not on the Solder side.  After I
drew polygon associated with GND_SLDER I get warnings about a polygon
to close to the holes.  Why is there not a clearance on the Solder
side of the board enforced for nonplated holes?  How do I get this
clearance around the holes to work?

4. Layer assignments.  I understand that PCB goes up to 8 layers.  In
the preferences there is  up to 8 groups and 8 different buttons two
of which are unassigned by default.  If I changed my design to a 4
layer design with the following configuration:

Bottom (Layer 4): Signal and components
Middle (Layer 3): GND
Middle (Layer 2): VCC: 3.3, 5, and 12
Top (Layer 1): Signal and components

How would I configure the groups and Y axis buttons in PCB layer
preferences to acheive the results above?  I saw in the info tab an
example but I don't think it's exactly what I'm after.

Any assitance is greatly appreciated.

Thanks
Jeff


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