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"Virtual 4-layer" PCB in a double layer PCB ?

Posted by joaoabs 
"Virtual 4-layer" PCB in a double layer PCB ?
June 27, 2016 07:16AM
Hello,

I finished my first PCB this weekend. I was a simple, single-sided test design.
I designed it with eagle, created the gcode with the PCB-to-GCODE (great stuff, BTW), and used a small CNC machine with GRBL and bCNC software running on a raspberry PI. I can say that eventough I didn't tune much the parameters I'm quite happy with the result.

Then, when I was soldering the components I thought how great would be if the "default track" (don't know the exact term for it, but its the copper part that doesn't belong to any other track and its all over the PCcool smiley could be associated to ground (GND) signal, for instance. I guess this would make the design simpler.

Going beyond that, if we work in double layer PCB's, we could do a similar approach in the top layer, associating, for instance, 5V to the "Default track".

Since in the multi-layer PCB's, there is usualy one layer for GND and other for VCC, we could call this a "virtual 4 layer" design.

So, in one sentence, the idea here is to simplify (considerably, I expect) the design by associating the unused copper on each layer to the most used signals in a PCB: GND and VCC.

Would this be possible, or is it already implemented but I'm missing the parameters?

Cheers,
Joao
Re: "Virtual 4-layer" PCB in a double layer PCB ?
June 27, 2016 07:56AM
I "think" the term your looking for is "ground plane". You make an outline which will show up as a dotted line around the area you select. Then you make your connections to it and then do a "ratsnest" the the whole area will turn to blue and have the appropriate connections (well at least most of the time for me unless I mess up"spinning smiley sticking its tongue out
Re: "Virtual 4-layer" PCB in a double layer PCB ?
June 27, 2016 09:54AM
So you mean that there is nothing to do on the PCB-to-GCODE, this could be done entirely in the board application of eagle? What else can you share about it, such as:

Have you tried before?
Does it work well with PCB-to-GCODE?
Does it make the design simpler as expected?
Have you tried with a dual layer PCB?


Thanks for your inputs,
Joao
Re: "Virtual 4-layer" PCB in a double layer PCB ?
June 27, 2016 12:21PM
Yes, it is done in Eagle itself.


As for your questions,
Have you tried before?
[yes several times]
Does it work well with PCB-to-GCODE?
[yes, no problems ]
Does it make the design simpler as expected?
[Most definitely as I has eliminated the need for vias several time. You might have to play around with component/trace location a bit, but it does work very well]
Have you tried with a dual layer PCB?
[No all my stuff so far has been single layer, but I have successfully used two different ground pours on the same side of the board, I see no reason why it would not work on dual layer.]
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