Mail Archives: geda-user/2013/05/03/15:58:34
That is an interesting technique, Steve. I'll have to keep that in mind.
On my last board, I used one large rectangle for the copper pour and
then used the hole tool to cut out the corners. I actually started
with a large mounting hole, via, but didn't like the round pointy
bits along the edge of the board, so I used the hole tool to cut those
off.
On Fri, May 3, 2013 at 2:38 PM, Stephen R. Besch <sbesch AT buffalo DOT edu> wrote:
> On 05/03/2013 01:57 PM, Ed Simmons wrote:
>>
>> On 03/05/13 18:44, Dave McGuire wrote:
>>>
>>> On 05/03/2013 01:30 PM, Ed Simmons wrote:
>>>>>
>>>>> ...for the lack of a better term.
>>>>>
>>>>> I would like to have the corners of a board not plated with copper,
>>>>> such that the copper fill (which I normally do with one big polygon)
>>>>> for
>>>>> the ground plane is shaped like a big fat '+' character.
>>>>>
>>>>> Other than drawing a big fat '+' with polygons, does anyone have a
>>>>> nice clean way to accomplish what I'm after?
>>>>>
>>>> Could this be done with a footprint containing pads (eg mounting or
>>>> tooling holes in the corners) with clearance such that the copper stops
>>>> where you wish? You could set the square flag to get the shape you're
>>>> after.
>>>>
>>>> Hope that's useful...
>>>
>>> Oh, that's an interesting idea! I will explore that. Thank you!
>>>
>>> -Dave
>>>
>> I make a generic 1 pin symbol that refers to the footprint for a
>> particular housing. Make sure you give the pads unique numbers or PCB will
>> tell you to connect them together, this keeps things easy to manage in the
>> schematics and PCB.
>>
>> Ed
>>
>>
> I've tried all of the above techniques and they all work, but tend to be
> limited to special cases. Multiple/Complex polygons work most of the time,
> especially when the copper keep-out is at the board edge. However, in those
> cases where there is a copper keep-out in the middle of the board, polygons
> don't seem to work. I've recently used another technique which is ideal in
> some cases, does not require composing a new footprint for every shape of
> keep-out, and can be made completely general. I draw a free, closed trace
> around the desired keep-out area. Rectangles will not cross this trace so
> the area bounded by it will be copper free. This does leave a visible
> "window frame" around the keep-out though. Sometimes this trace can be used
> for connectivity as well. In any case, the Gap between the polygon and the
> keep-out trace can be eliminated by drawing another trace in the gap. This
> trace needs to partially overlap the Keep-Out trace. Then setting the join
> flag on this second trace lets the polygon flood over the second trace, but
> it still stops at the keep-out trace. One rather major limitation is that
> other traces cannot cross the boundary either, so its not as useful in
> crowded parts of the board unless you are willing to add a lot of
> vias/jumpers or break the keep-out trace into enough segments - then trace
> clearance will prevent copper fill getting past the trace. Another cool
> thing about this technique is that you can drop another rectangle inside the
> keep-out to make a separate, electrically independent copper pour. This is
> useful for heat-sinks or sub-circuit power distributions or ground isolation
> areas (e.g., separating analog circuitry from Digital circuitry).
>
> It is all a bit of a pain, but since PCB does not have an official Copper
> Keep-Out, you do what you have to do and the more techniques the merrier.
>
> Steve Besch
>
> --
> fictio cedit veritati
>
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