Middle-permittivity LTCC dielectric compositions with adjustable temperature coefficient

Abstract

Middle-permittivity low-temperature co-fired ceramics (LTCC) dielectric compositions with adjustable temperature coefficient have been studied based on CaZrO3-CaTiO3. To lower the densification temperature from 1450 degreesC to less than 900 degreesC, a series of lithium-borosilicate glass system was designed and added to the CaZrO3-CaTiO3 system. As the tau(f) of glass frits and CaZrO3 are slightly negative (-5 to -200 ppm/degreesC) and that of CaTiO3 is significantly positive, zero tau(f) could be realized by mixing an appropriate amount of CaTiO3 (10-20 wt.%) with CaZrO3. Microstructures, physical properties, and microwave dielectric properties were measured as a function of the compositional ratio of CaZrO3-CaTiO3. Nearly zero tau(f), together with an acceptable microwave quality factor, was obtained at the composition Of CaZrO3/CaTiO3/frit=70:15:15 wt.%. (C) 2004 Elsevier B.V. All rights reserved.