Guten Tag Kai,

Long time no "see." I hope all is well with you and yours.



As a rule, I wouldn't put the ground plane on the component side. I would make it the power plane (Vxx) instead. Of course, you still need to be deliberate about where you route any sensitive traces.

Concerning the matter of shielding between signal layers, and assuming this is a 4-layer stack up we're discussing, isolation would be whatever can be achieved by the orthogonality of the layers (just like on any 2-layer stack up). Of course, one also has the option of making it a 3-layer stack up, or 5 or 6 or ....

In the end, as is usually the case in engineering, the best design for any given pwb is going to be the result of many compromises, or trade-offs if you prefer. But if other circumstances don't make it impossible, sandwiching your signal layer(s) can very possibly save you having to install a faraday cage around your board. And if someone is making a lot of your board, that can be a significant savings.

Joe