For a single or double layered PCB board, usually I will cover all the empty spaces in the layout with Ground.
This is the 1st time I am designing a 4 layer PCB layout.
Layer 1: top signal (high speed)
Layer 2: Ground plane
Layer 3: Power plane (5v, 3.3v, 1.8v)
Layer 4: bottom signal (normal speed)
Since now I already got a dedicated Ground plane (Layer 2), my question is:
After finished all the routing, for Layer 1 & 4, should I still cover all the emptied space with Ground as well?