Zinc Oxide-Bismuth Oxide Low Q Decoupling Capacitor

A description and analysis are presented of the fabrication and electrical properties of a non-ferroelectric material with a high apparent dielectric constant over a wide frequency range into the megacycle region. This material is zinc oxide with additions of bismuth oxide. Specific attention is focused on those properties which make the material uniquely suited for microminiature high-frequency low impedance decoupling capacitors. With proper processing, apparent dielectric constants on the order of 1500 at 5 Mc/s are reached. Using silk screening techniques, capacitors with values up to 100µF/in²have been obtained, but at the expense of a very low (10 -cm) dc resistivity. Usable devices with dc resistances of a few hundred to a few thousand ohms have capacitances in the I to 50 µF region. This device is also capable of strongly attenuating inductive noise signals and exhibits a constant total impedance of 2 to 3 ohms in the 10 to 100 mc/s range.