Cubesat type application: Should I ground the PCB stack to the external chassis?

[logancane]

Pretty much as the question states. In this case, the application is a high altitude balloon, but we are connecting the PCB's like how they do in cubesats. That is to say the PCB's will be connected via PC/104 to an aluminum block/ground plane. My question is, should I electrically connect or isolate this ground plane from the external chassis that is exposed to the atmosphere? I am trying to minimize noise in the circuit.

Cheers everyone.
 

[MikeK]

Won't the chassis act like an antenna?

[David Hess]

Test instruments with metal chassis faces the same problem.  The chassis should never be floating with respect to the circuit because static charge could build up and especially so in your application.  If no ground plane is used, then a single point ground is usually the best option and if possible, should be at the signal ingress/egress.  With a ground plane, every standoff might be connected to the chassis.

In applications where a direct low impedance connection is not feasible, some provision should still be made to bleed off static charge like an inductor or resistor between the chassis and the single point ground.  Often in this case a bypass capacitor is also used to make an RF connection, or a breakover (?) capacitor which acts as a spark gap.

[nfmax]

Are lightning strikes a possibility? The voltage at different points of the external chassis will be different, because of the lightning current flowing through the structure. You need to talk to an expert though, not me.