Shared heatsink grounding

[BorisRap]

Good day.

I'm designing a power supply composed of 3 stages:
-a PFC with line filter
-an isolated LLC resonant converter
-a constant current/constant voltage DC/DC converter

All three stages are in series.
All switching mode stages are on the same board (it's a fairly large board) and the board is inside an aluminum case without any airflow. For this reason it must be a good thermal connection between all the heat-generating elements and the case.

So I've designed it in a way which all switching transistors and switching inductors are thermally coupled to the case. This noisy components are electrically insulated but they are really close to the metal.
That's why I'm worrying about switching noise coupling to the case, especially between switching components of two switching converter that are insulated.

Do you have any idea how should I connect the case?

Of course it must be connected to mains earth. And mains earth is coupled to the PFC ground via the inline filter Y capacitors.
Do you have any guidelines on how should I (or shouldn't) couple the two grounds and mains earth?

Thank you very much

[Benta]

I'd be more worried about killing someone touching the case.