Microwave dielectric ceramics with low dielectric loss and high temperature stability for LTCC applications

Abstract

Preliminary tri-layer architecture ZnNb1.8V0.1O5.75-TiO2+CuO–ZnNb1.8V0.1O5.75 ceramics with high-temperature stability and low dielectric loss have been prepared. In the past, the stacked co-firing process could only be used at normal sintering temperatures. In this paper, the effect of the transition layer in ZnNb1.8V0.1O5.75-TiO2+CuO–ZnNb1.8V0.1O5.75 ceramics with tri-layer architecture sintered at low temperatures (950 °C) on the crystalline structure, microscopic structure, and integrated microwave dielectric performance of specimens has been investigated in depth for the first time. This low-temperature stacked-layer co-firing technique can effectively enable the chemical reaction between ZnNb1.8V0.1O5.75 and TiO2+CuO to take place in a rather narrow region (about 20 μm), i.e., the interface of the heterogeneous layers. In this interface, diffusion of Zn, Nb, V, Ti, and Cu can be observed. This heterogeneous interface can act as an in-situ “glue” that holds the layers together well. The effect of TiO2+CuO content on the microwave dielectric performances of laminated architectural specimens under low-temperature sintering was systematically investigated. Among the existing layer architectures, the stack of ZnNb1.8V0.1O5.75-TiO2+CuO–ZnNb1.8V0.1O5.75 with 0.03 wt% TiO2+CuO exhibits the most excellent microwave dielectric performances. τf can be efficiently tuned close to zero (−7.14 ppm/°C), and remarkably, a low dielectric loss (14,587 GHz) and a high value of εr (24.00) are also achieved. This low-temperature sintered tri-layered architecture is designed to help open new avenues for the development of high-performance microwave dielectrics based on existing material systems, providing effective strategies and methods for 5G applications and multilayer packaging technologies.