I have a design which has 7 layers. The top layer has only short stubs.
There are two layers for traces but they are sensitive signals and there is a solid ground plane above and below these two layers. I have connected these two planes at one point near the incoming supply. I also have a single ground plane as layer 7 which is noisy.
How do I connect a number of ground signals from Layer 1 to Layer 7 WITHOUT connecting to the other two ground planes, which would inject noise onto these planes?
When I try using the normal vias, they connect all planes from 1 to 7 and also 2 and 5, I just need layers 1 and 7 connected but they need to connect at the supply (one via connecting layers 1, 2, 5 and 7).