For a 4 layers PCB, covering with ground polygon on Layer 1 and 4 necessary?
The 4 layers PCB layout I am designing is as following.
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, my question is:
After finished all the routing, for Layer 1 & 4, should I still cover all the emptied space with Ground as well?