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The PCB I designed is 6-layer. I will create a chassis ground in the form of a frame surrounding the mounting holes and add a Y capacitor between and to the signal GND. And I will surround this chassis ground and adding stitching vias on the entire layer of the PCB.

The part that stuck in my head is that the circular connectors in the middle do not contact the PCB. Ethernet signals from circular connectors first go to an ethernet isolation transformer and then go to the other connector. For the Ethernet isolation transformer midpoint, I need to make a Bob Smith ground to the chassis. However, I cannot do this from the middle connectors.This type of connector is mechanically connected to the chassis from the body but has no connection with the pcb. If I bring the chassis ground around the edges of the PCB to the middle point where it is the ethernet transformer, should I add all the lower layers to the chassis ground? Or do you have another suggestion? Another aspect of the job is that the other signals will pass through the lower layers.

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  • \$\begingroup\$ So you're using metallic circular connectors not in a metallic enclosure? \$\endgroup\$
    – Tim Williams
    Aug 9 at 19:36
  • \$\begingroup\$ The enclosure is metal. The connector is also metal, but it is not directly connected to the pcb and is not soldered. If you examine Amphenol brand connectors, you can see a lot of connectors of this type."Wall Mount Receptacle" \$\endgroup\$
    – Electronx
    Aug 9 at 19:47
  • \$\begingroup\$ Oh... but then you already have a chassis? Why not use that? \$\endgroup\$
    – Tim Williams
    Aug 9 at 19:56
  • \$\begingroup\$ I guess I didn't explain well. The connector is connected to the pcb only through its pins. The body of the connector is independent from the pcb and pins .there is no tab where I can solder the body of the connector to the pcb. \$\endgroup\$
    – Electronx
    Aug 9 at 20:01
  • \$\begingroup\$ Right. So you only need connect PCB to GND (enclosure). Which can be done at each mounting hole, to main ground plane, no? I was confused because you said "create a chassis ground in the form of a frame surrounding the mounting holes" (which brings, to my mind, how some people suggest creating a ""chassis"" around the board periphery). Do you need isolation between circuit ground and chassis ground then, or can they be bonded? At the very least it sounds like capacitors in the corners should mostly do it. What about signals on the connector, are they all low-frequency or differential? \$\endgroup\$
    – Tim Williams
    Aug 9 at 20:10

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