[Repeater-Builder] Controller enclosure shielding

[kq7dx]

Hello to  Group!,
I had a question on shielding. 
The controller I have has a gap on the back of the enclosure where the DB-9 is. 
Since I have been told everything has to be double shielded on a repeater, so 
should I put some copper tape across the back to cover the gap into the 
enclosure. I am not sure where the machine is going yet and thought if it was 
in a high RF environment, the RF would get into the opening and do something to 
the controller.
Thanks for any replies.