A kind of ultra-low dielectric constant microwave dielectric ceramic and preparation method thereof

Abstract

The invention discloses ultralow-dielectric-constant microwave dielectric ceramic Ca1.5V2O6F capable of being sintered at low temperature and a preparation method of the microwave dielectric ceramic. The preparation method comprises the following steps: (1) weighing and blending original powder including CaF2, CaCO3 and V2O5 with the purity being 99.9 percent by weight according to the composition of Ca1.5V2O6; (2) carrying out wet ball-milling on the raw materials in the step (1) for 12 hours, drying and then presintering for 6 hours at the atmosphere of 880 DEG C, wherein a ball-milling medium is distilled water; and (3) adding a binder to the powder prepared in the step (2) and granulating, then pressing for molding and finally sintering for 4 hours at the atmosphere of 930-950 DEG C, wherein the binder is a polyvinyl alcohol solution with the mass concentration being 5 percent and the addition of polyvinyl alcohol accounts for 3 percent of the total mass of the powder. The ceramic prepared by the preparation method has favorable sintering property at 930-950 DEG C, the dielectric constant reaching 8-8.6, the quality factor Qf up to 56900-58100GHz and low temperature coefficient of resonance frequency and has extremely great application value in the industry.

Description

technical field [0001] The invention relates to a dielectric ceramic material, in particular to a dielectric ceramic material for manufacturing microwave components such as ceramic resonators and filters used in microwave frequencies and a preparation method thereof. Background technique [0002] Microwave dielectric ceramics refer to ceramics that are used as dielectric materials in circuits in the microwave frequency band (mainly UHF and SHF bands) and perform one or more functions. They are widely used as resonators, filters, and dielectric substrates in modern communications. Components such as chips and dielectric waveguide circuits are the key basic materials of modern communication technology. They have been used in portable mobile phones, car phones, cordless phones, TV satellite receivers and military radars. They are used in modern communication tools. It is playing an increasingly important role in the process of miniaturization and integration. [0003] Dielectr...

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Problems solved by technology

[0009] In the process of exploring and developing new low-firing microwave dielectric ceramic materials, material systems such as Li-based compounds, Bi-based compounds, tungstate compounds and tellurate-based compounds with inherently low sintering temperatures have received extensive attention and research. However, due to the three performance indicators of microwave dielectric ceramics (ε r with Q f and τ ? ) is a mutually restrictive relationship (see literature: The restrictive relationship between the dielectric properties of microwave dielectric ceramic materials, Zhu Jianhua, Liang Fei, Wang Xiaohong, Lu Wenzhong, Electronic Components and Materials, Issue 3, March 2005), satisfying three There are very few single-phase microwave dielectric ceramics that require high performance and can be sintered at low temperature, mainly because their resonant frequency temperature coefficient is usually too large or the quality factor is too low to meet the practical application requirements.

At present, most of the research on microwave dielectric ceramics is a summary of experience obtained through a large number of experiments, but there is no complete theory to explain the relationship between microstructure and dielectric properties. Predict the microwave dielectric properties such as its resonant frequency temperature coefficient and quality factor, which largely limits the development of low temperature co-firing technology and microwave multilayer devices

Exploring and developing microwave dielectric ceramics that can be sintered at low temperature and have near-zero resonant frequency temperature coefficient (-10ppm / ℃≤τ?≤+10ppm / ℃) and high quality factor is the technology in this field A difficult problem that people have always wanted to solve but have never been able to succeed in

[0010] Our composition of Ca 1.5 Ta 2 o 6 F, Ca 1.5 V 2 o 6 F, Ca 1.5 Nb 2 o 6 F. Ba 1.5 Ta 2 o 6 F and Ba 1.5 V 2 o 6 A series of compounds of F were studied for microwave dielectric properties, in which it was found that Ca 1.5 V 2 o 6 F and Ba 1.5 V 2 o 6 The sintering temperature of F is lower than 960 °C, but only Ca 1.5 V 2 o 6 F has near-zero resonant frequency temperature coefficient and high quality factor, Ca 1.5 Ta 2 o 6 F and Ba 1.5 V 2 o 6 The resonant frequency temperature coefficient of F ceramics is too large (τ ? respectively +64ppm / ℃ and +72ppm / ℃), while Ca 1.5 Nb 2 o 6 F and Ba 1.5 Ta 2 o 6 The dielectric loss of F is too large to be used as a microwave dielectric ceramic

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