Free space on signal layers

[Mihai]

Hi,

It is good or bad practice to fill up the signal layers with polygon planes tied to GND? I am referring on all signal type layers (inner, top, bottom).

Thanks,
Mihai

[robertferanec]

I do not do that and I have never had problems with the kind of boards I design (digital boards). I read, that these "planes" may sometimes make your PCB even worse - especially if the plane is noisy or if it has slivers which may behave as antennas. However, I have never done any direct comparison.

PS: In some designs these fillings may be required - the best is to check reference design or design guide. I see it a lot in RF stuff, but I do not do RF, so I can not really speak much about that area.