I have a digital signal (MISO) via with that goes from top to bottom layers on a 4 layer board. I have a ground plane, and I want to place 2 ground vias next to this signal to provide a better return path for the signal.
I get the DRC Warning:
Via is not connected or connected on only one layer.
Via [GND] on F.Cu - B.Cu
I tried running a ground trace between the ground vias, but still the same warning.
I have attached a picture of the via properties and what the board looks like.
Also, I have incldued a screenshot from this video - PCB Stack-Up and Build-Up - Phil’s Lab #56 - https://www.youtube.com/watch?v=QAOEtfvCaMw&t=7s, timestamp 17:23 that illustrates what I am trying to do.
I know I can just ignore the warning, but I want to make sure I have set up the ground vias correctly.
Your Blue layer is apparently a GND layer, but the other green layer is not. These transfer via’s only work if they can connect GND zones on different layers together.
The green is 3.3V power plane. OK…the video has 2 ground planes, with a via connecting them. I only have one ground plane, so I cannot have a ground via. Is that correct?
If I leave the board as is, what will happen when it is manufactured?
If I leave the board as is, what will happen when it is manufactured?
You will get two vias which have a GND-connection on bottom, but no connection on any other layer. So in principle two useless vias.
Nevertheless most probably your connection will work correctly - your shown application note applies to very high frequency communication.
A MISO-signal sounds like a SPI-connection and should normally not be affected by missing decoupling vias.
you have already correctly seen the difference between your board-stackup and the pcb in the video: you have a pcb with Vcc and GND layer, the video shows a pcb with 2x GND layer (L2+L3). On that layer-stackup a GND-via can be useful (for edge cases and really fast signals).
