Characterization of Li₂MoO₄/BaTiO₃ All-Ceramic Films on Organic Substrate Printed Capacitors at 45 MHz–10 GHz

Abstract

This article presents novel all-ceramic composite films used as a screen-printed capacitors on polymer surface and their characterization at 45-MHz to 10-GHz frequency range. All-ceramic composite paste is based on lithium molybdate (Li₂MoO₄), barium titanate (BaTiO₃), and water manufactured by the room temperature fabrication (RTF) method. For the determination of the permittivity and the loss tangent of the materials, ceramic thick films are printed on the top of an interdigital-shaped microwave capacitors using pastes with 0, 10, and 20 vol.&#x0025; of BaTiO₃ filler in Li₂MoO₄ followed by a drying process at 120 &#x00B0;C. The electrical properties of the capacitors, capacitance, and quality value are derived from measured <inline-formula> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula>-parameter results, whereas the electrical properties of the ceramic thick-film materials, real, and imaginary values of permittivity are derived from the measured results through computer simulations. The electrical properties of the ceramic material, such as moderate permittivity and moderately low-loss tangent, could be adjusted by changing the volume fraction of the BaTiO₃ filler to match the demands of different areas of applications. The obtained results are verified with five samples of each ceramic composition. The results show the capacitance values of 0.30 pF for an uncoated capacitor and 0.55, 0.67, and 0.95 pF with coatings of Li₂MoO₄ with 0, 10, and 20 vol.&#x0025; of BaTiO₃ composites, respectively, at 2.5-GHz frequency. The calculated relative permittivity (<inline-formula> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula>) values for the same materials are 3.70, 5.23, and 6.43, and loss tangent values are 0.035, 0.027, and 0.036 at 2.5 GHz. These novel all-ceramic capacitor composite materials are applicable for the RF components used in telecommunication applications in the frequency range of 45 MHz&#x2013;10 GHz, thus widening the technology roadmap in terms of material choices for different applications, especially high thermal resistant materials.