Shipla, Can you provide a picture and a brief description of the kinds of circuits (Are the signals expected to be DC or AC, What kinds of signals are you concerned about and how close are they?)
In general a qquard ring is referring to a tap or set of tap connections on substrate or in Nwell that is isolating one region from another by absorbing charge. I think you are referring to a metal shield. Often just referred to as a shield. It will tend to act to absorb capacitive coupling between adjacent circuits but will have very limited effect on magnetic field as aluminium and copper are both not magnetic materials. What this means in practical terms is that shields can protect from Capacitive coupling from DC to Ghz but have no impact on preventing magnetic field coupling from far field EM waves