Earth Ground vs Digital Ground on a Multiboard design

[harshal_pwr]

Hi,
I am working on a design that consists main board (Interface board) and a daughter board (CPU Board).
The daughter board will house the CPU, PMIC, and all communication PHYs. The interface board will have all the communication ports including RJ45, USB Type A, etc.

The communication ports are shielded and have a shield pin that needs to be connected to earth ground.

We are incorporating procedures that will enable us to place an EMI shield on CPU card. (in case we need)
1. Does this EMI shield need to be connected to Digital GND? or Earth Ground?
2. If this needs to be earth grounded, can I incorporate 2 net-ties that connect earth GND and Digital GND? (first net-tie on the daughter card and second on the interface board)

Thank you for your advice.

Best regards,
- Harshal

[robertferanec]

Every system is different, so there is no universal answer.

If I am not sure, what I need to do, I try to support all the kind of different scenarios. For example, I place number of footprints between the grounds. Then during EMCI/EMI/ESD test we may try different scenarios e.g. we do not fit anything, we fit 0R, we fit BEADS or Capacitors. Then, in the final product we will use the configuration with best results.

PS: If we need more grounds, usually we only have two: Enclosure GND (all shields of connectors are connected here) and Board GND (this is the ground where all the chips are connected)