Hi guys,
I'm doing a 8 layer PCB where I have a couple of differential pairs to route. My stackup is the following
L1 : TOP
L2 : GND
L3:SIG
L4:GND
L5:GND
L6:SIG
L7:GND
L8: BOT
I routed my diff pairs on the inner signal layers, however from time to time I get stucked and don't have any path to continue my routing
=> Would it be dammageable if I switch from my signal layer to go to one of my ground plane layer , continue my path on the ground plane and then come back to the signal layer when it's possible ? Let's say I switch a diff pair from L3 to L4 and then come back to L3.
=> Furthermore I have some low speed signals to pass. Once again is it dammageable for my diff pairs if I route my low speed signals on the ground planes ?
The result of doing this would be fragmented ground planes. However I plan on making sure the planes above / below every diff plane is continous.
Thanks a lot for your answers !

 

a) route them on top or bottom , then you avoid stubs on vias.
b) Why a 8 layer board, whats on layer 4 and 5 ?
c) if you do change layers, ensure you use a differential via, with a ground pair around it.
https://www.signalintegrityjournal.com/articles/1918-how-to-stop-your-differential-vias-from-leaking