All, I am having difficulty mounting some of the small pcb pieces such as buck/boost converters (see attached figure), arduino nano, etc. My question is can I use thermal paste/grease to use as glue to mount them on the casing since they are supposed to be electrically non-conductive. Any potential issues? Thanks!

 

hi us201,
I use a hot melt glue gun for those awkward modules.[ or an old solder iron with a hot melt glue stick]
Just a spot of melt is enough, which with an old solder iron can easily be detached if required,

The thermal paste will dry out with time.
E

 

I have used hot melt glue on things that get warm and found that sometimes they go so warm that the glue became un-glue.

Another way to hold something to a heatsink that was designed to be easily held onto a heatsink is with a spring clamp like the one in the picture.

In the case of your power supply module, you should probably insulate the back (circuit side) of the board with a silicone sheet (expensive) or Kaptan tape (cheap).