Water-repellant monolithic ceramic capacitor suppresses ion migration

Paul Boughton

Electronic devices are becoming ever more compact and densely packed with components, with this comes an increase in the possibility of malfunctions influencing circuit operation due to ion migration.

Ion migration may occur when voltage is applied to a capacitor where moisture is present between the electrodes. This may result in the anode metal becoming ionised and changing to a cathode. Then, when gaining electrons as a cathode, the metal may undergo the electrochemical phenomenon of deposition and growth that can eventually result in a short-circuit. This is particularly prone to occur when the capacitor is moistened by condensation.

To address this issue Murata has developed a water repellent monolithic ceramic capacitor. The monolithic capacitor is treated with a water-repellant treatment film so that moisture forms into scattered, rather than larger, droplets. These droplets are suppressed to a size that is not big enough to span the gap between the external electrodes and this prevents ion migration.

This capacitor has applications particularly in navigation systems, body control electronic control units (ECUs), air conditioner ECUs, meter ECUs and engine ECUs, etc.