VIM3 Mount: Standoffs - plastic/metal?

Which Khadas SBC do you use?

VIM3 Basic

Which system do you use? Android, Ubuntu, OOWOW or others?

Ubuntu

Which version of system do you use? Khadas official images, self built images, or others?

20.04

Please describe your issue below:

I would like to mount the Khadas VIM3 using standoffs with the 4 mounting holes. May I please know if I am required to use metal standoff for the purpose of grounding or can plastic be used as well and grounding through the mounting holes is not required?

Thank you