ith the explosive increase of global mobile data and the rapid development of global satellite positioning system (GPS)and other wireless communication positioning means,microwave dielectric ceramics,as vital dielectric materials,can bear a variety of high-frequency signals and microwave signals,and are developing towards high-frequency and signal high-frequency adjustability. Lightweight,high performance and low loss are higher requirements for microwave dielectric ceramic materials in the era of big data. Low temperature co-fired ceramic (LTCC)technology has become the mainstream of active / passive component packaging with excellent thermal and electrical properties as well as an advanced preparation process,which is widely used in electronic devices and circuit packaging. In practice applications,for microwave electronic substrates,low permittivity effectively avoids signal delays and ensures efficient transmission rates. Materials with high quality factors (Q×f≥5 000 GHz)can increase frequency selectivity and reliability. And the near-zero resonant frequency temperature coefficient (τf)can guarantee the stability of the device operating at different temperatures. The low sintering temperature (≤950 ℃) enables co-firing with metals with low melting points and high conductivity. Therefore,low dielectric LTCC ceramics have become a current research hotspot,greatly promoting the application of microwave dielectric materials. Microwave dielectric materials can be divided into ceramic systems (tellurite,vanadate,molybdate,tungstate,borate and phosphate,etc.), glass-ceramics (CaO-B2 O3 -SiO2,MgO-B2 O3 -SiO2,ZnO-B2 O3,MgO-Al2 O3 -SiO2,Li2 O-MgO-ZnO-B2 O3 -SiO2,CuO-B2 O3 -Li2 O,etc.),and glass+ceramic composite systems. The ceramic system is generally prepared in a stoichiometric ratio by a solid phase method. Glass-ceramics is a polycrystalline material with adjustable composition and excellent microwave dielectric properties,which has been widely used. The high-density glass-ceramic composite system is prepared by adding a ceramic filler into a low softening point glass matrix,and the selection of the ceramic filler material depends on the dielectric requirement of the microelectronic device and is mainly used for improving the dielectric,thermal and mechanical properties. The research and development of high-performance LTCC materials need the matching co-firing of low-temperature sintered dielectric material and inner electrode material,improving the microwave performance of the low-temperature sintered dielectric material and optimizing the thermal expansion coefficient and thermal conductivity of the low-temperature sintered dielectric material. In addition,it is also considered that the low-temperature sintered dielectric material has good mechanical strength and low production cost. This work summarizes the concept and classification of low temperature co-fired materials with low dielectric permittivity and focuses on the research status and performance characteristics of various types of LTCC ceramics,glass ceramics and glass+ceramic composite systems. In addition,the main problems faced in the preparation and application of low-temperature and low dielectric co-fired materials are analyzed,and the application prospect in future communication technology is discussed,which can provide a reference for the future development of low firing high-performance microwave dielectric materials. © 2023 Cailiao Daobaoshe/ Materials Review. All rights reserved.
