Enhanced microwave-assisted sintering of X7R ceramic dielectrics for use in multilayer capacitors

A hybrid furnace, allowing the simultaneous application of microwave (2.45 GHz) and radiant energy, has been used to investigate the sintering of a commercial X7R powder commonly used in multilayer capacitors. Samples were processed at temperatures in the range 1060–1120 °C. Enhanced sintering has been observed in the form of accelerated densification when a microwave field is applied. At 1090 °C for example, 99.4% dense material was obtained by microwave-assisted heating but only 96.9% density was reached by conventional heating. The relative permittivity of the microwave sintered material was ∼2200, typically 10%, higher than for conventionally sintering. The Curie temperature was lower by 5 °C in the microwave heated samples.