The Preparation and Properties of 4.7 uF 2220 Size 50 V Z5U Relaxor Multilayer Ceramic Capacitors

Abstract

A new dielectric for multilayer ceramic capacitors is currently undergoing factory qualification. This dielectric is based on a nonstoichiometric lead magnesium niobate relaxor material. Dielectric constants in excess of 15000 have been achieved for bodies which sinter close to 900°C with 100 percent Ag internal electrodes. The use of very high Ag content electrode systems means that there is a considerable cost reduction so that multilayer ceramic chip capacitors become cost competitive with solid tantalum chip capacitors. The preparation and properties of the dielectric material are described and life test data are presented showing that capacitors of the new dielectric are extremely stable for periods up to two years at ambient and upper rated temperature. A direct comparison is made between the electrical properties of 4.7 uF 50 V 2220 size Z5U multilayer chip capacitors manufactured from the new relaxor dielectric and the equivalent value tantalum chip capacitors.