Im currently working on a PCB design, where I will have 6 layers

The stackup will be:

  1. Top signals
  2. GND layer
  3. Signal 3
  4. Signal 4
  5. Powerlayer
  6. Bottom signal

Right now I have an full Ground plane on layer 2, but should i also use copper fill connected to GND on the other 5 layers to shorten the GND return path as much as possible?

The design is filled with digital sensors sampling at a 1MHz or 2. - Only impedance that is important is my wire to the wifi antenna, which of course will follow the rules to get 50 Ohm impedance.

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  • \$\begingroup\$ Did you use the search-function? There are at least several very similar questions. Some with respect to different layer stacks, some with focus on high speed etc. \$\endgroup\$ – Rev1.0 Nov 13 '17 at 13:11

I wouldn't.

If your ground plane does not have breaks in it the extra fill wont really get you anything other than adding the potential to add in ground loops and noisy mechanical edges you really do not want. Other wise I really do not see how it will "shorten" your return paths.

However, there is some merit to add fill if the components on your board are expected to run hot. Whether that fill should be connected to ground or not is up for debate. I would single point connect it to ground just so it can't build up a charge.

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If you don't see any reason to isolate different grounds (analog, digital, power-management ground) then by all means the grounds can be shortened.

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