This is how you mount controller to your RC model.
Mounting of controllers is possible using either the 4 mounting holes in the corner of the main PCB or by using M3 screws in the cooler (red arrows) from both sides (4 M3 screws are needed).
If you use the holes in the main PCB, use spacer plate from non-conducting material (polyamide, xxxx etc). Choose the M3 screw head such that it is not in contact with surrounding copper areas on the board (that is up to Ø 6 mm) or use an insulating pad.
If you use holes in the cooler, it does not matter which material is used as the coolers are insulated, they are not connected to any potential.
If the system in which the controller is mounted vibrates, fasten it using suitable silent blocks.