nelsonys
Member level 4
I would like to draw a conclusion.
For high density BGA package, it is hard to design a perfect return for each and every signals without crossing the split of the power planes. It is merely decided by the Tr of the signals and how high the frequency is it, then only we can decide for relevant PCB stackup, for example two GND layers stripline to cover the high speed or sensitive signal from EMI problems. By then, it will be a very tough design job.
I think it is just matter of what is the extent you would like to design your board to. How much do you concern about SI including your margin of design. It might be over-design at times, perhaps. We could only be able to validate our design through post-design simulation like 2D or 3D wave-solver.
For high density BGA package, it is hard to design a perfect return for each and every signals without crossing the split of the power planes. It is merely decided by the Tr of the signals and how high the frequency is it, then only we can decide for relevant PCB stackup, for example two GND layers stripline to cover the high speed or sensitive signal from EMI problems. By then, it will be a very tough design job.
I think it is just matter of what is the extent you would like to design your board to. How much do you concern about SI including your margin of design. It might be over-design at times, perhaps. We could only be able to validate our design through post-design simulation like 2D or 3D wave-solver.