You will not have to do through customs during your connection, but you may have to pass through immigration, depending on what your final destination is.
If your destination is within the Schengen zone (Switzerland recently joined the Schengen treaty), no immigration check is needed. If your destination is outside Schengen, you will have to go through passport control since you are exiting the Schengen zone at ZRH.
In general, one hour and 35 minutes is plenty of time for a connection in ZRH, especially if you use the transfer desks to check in airside.