Co-sintering of barium strontium titanate (BST) thick films inside a LTCC substrate with pressure-assisted sintering

Screen-printed ferroelectric BST thick films were co-fired inside a LTCC substrate by employing pressure-assisted sintering (PAS). Sintering pressure and time were varied and their effect on the microstructure and dielectric properties of the film was studied. Sintering conditions for the fabrication of buried BST thick films were experimentally defined and parallel plate capacitors were successfully fabricated inside a LTCC substrate. The relative permittivity (ɛr) of the films at 10 kHz varied from 188 to 220 depending on the sintering conditions, and the maximum tunability of the films was 44% (5.7 V/μm). The measured loss tangent (tan δ) at zero bias was 0.005.