Question Non conductor preventing short circuit

[rok_hribar]

Hello,

so I am interested what is put as a medium between two logic boards. So it doesnt come to short circuit.
I suppose a non conductor which doesnt transfer current, like wood or smth. I am more interested what is used in industry.

And also will these mediums in nuc be sufficient.(the grey ones)
https://nucblog.net/wp-content/uploads/2018/10/nuc8i3beh_components.jpg

Thank you for your reply

 

[ss202sl]

an air gap?