CN105622089A - Low-temperature-sintering low-dielectric-constant microwave dielectric ceramic Li2ZnTiO4 - Google Patents

Abstract

The invention discloses application of halite-structure composite oxides Li2ZnTiO4 as temperature-stable low-dielectric-constant microwave dielectric ceramic and a preparation method of the microwave dielectric ceramic. The preparation method comprises the following steps: (1) weighing and proportioning Li2CO3, ZnO and TiO2 original powders with the purity of higher than 99.9 wt% according to the composition of the Li2ZnTiO4; (2) carrying out wet ball milling mixing on the raw materials in the step (1) for 8 hours by using anhydrous ethanol as a ball milling medium, drying, and presintering in an 850-DEG C atmospheric atmosphere for 4 hours; and (3) adding an adhesive into the powder prepared in the step (2), granulating, compacting, and finally, sintering in a 900-960-DEG C atmospheric atmosphere for 4 hours, wherein the adhesive adopts a 5 wt% polyvinyl alcohol solution, and the addition amount of the polyvinyl alcohol is 3% of the total mass of the powder. The ceramic has favorable sintering property, the dielectric constant reaches 8.4-9.8, the quality factor Qf value is up to 24000-37000 GHz, the temperature coefficient of resonance frequency is small, and the ceramic has great application value in industry.

Description

A kind of low temperature sintering dielectric constant microwave dielectric ceramic Li2ZnTiO4

Technical field

The present invention relates to dielectric ceramic material, particularly relate to dielectric ceramic material and its preparation method of the microwave devices such as the ceramic substrate for the manufacture of microwave frequency use, resonator and wave filter.

Background technology

Microwave dielectric ceramic refers to and is applied in microwave frequency band (mainly UHF and SHF frequency range) circuit as dielectric material and completes the pottery of one or more functions, modern communication is widely used as the components and parts such as resonator, wave filter, dielectric substrate and medium guided wave loop, it it is the key foundation material of modern communication technology, in portable mobile phone, automobile telephone, cordless telephone, telestar susceptor and military radar etc., there is very important application, in the miniaturization, integrated process of modern communication instrument, just playing increasing effect.

In recent years, along with the high speed development of information technology, electronic circuit develops to high frequency, miniatureization and highly integrated direction day by day, this just electronics is met propose that size is little, the requirement of high frequency, high reliability and high integration. LTCC Technology (LowTemperatureCo-firedCeramics, LTCC) thick-film material is adopted, according to the structure designed in advance, by one-time sintering technology monolithic structures such as electrode materials, substrate, electron devices, it is that one can realize high integration and high performance Electronic Packaging technology. As ltcc substrate material, microwave dielectric ceramic should meet the requirement of following dielectric characteristics: (1) low-k�� _r To improve the transfer rate of signal; (2) high quality factorQValue or low dielectric loss tan��To reduce noise, general requirementQ��f>=3000GHz; (3) temperature factor of resonant frequency�� _? Little of as far as possible to ensure the thermostability that device has had, general requirement-10ppm/ DEG C�ܦ�_?��+10ppm/ DEG C. Meanwhile, in order to realize and the common burning of high conductivity metal electrode (Ag, Cu etc.), the sintering temperature of microwave dielectric ceramic should lower than 960 DEG C. In the recent period, some low fever's system materials have been carried out exploring widely and research by domestic and international researchist, mainly adopting devitrified glass or glass-ceramic composite system, because low melting glass has relatively high dielectric loss mutually, the existence of glassy phase substantially increases the dielectric loss of material. Therefore development is the current emphasis studied without the low fired microwave dielectric ceramic material of glassy phase.

Explore can in the process of low fired microwave dielectric ceramic materials with development of new, the material systems such as Li based compound, Bi based compound, tungstate architecture compound and tellurate architecture compound that intrinsic sintering temperature is low get the attention and research. Our mutual-through type is A_aB_bO_a+bLi basement rock salt structural compounds carried out Study on microwave dielectric property, it has been found that Li₂ZnTiO₄Sintering temperature lower than 960^oC, and have low-k (�� _r ~ 9.5) and high quality factorQ��fValue (37,000GHz), and its temperature coefficient of resonance frequency ��_?(-11.3ppm/ bigger than normal^oC).

Summary of the invention

It is an object of the invention to provide one can low-temperature sintering and there is good thermal stability and low-loss dielectric constant microwave dielectric ceramic material and its preparation method.

The chemical group of the microwave dielectric ceramic material of the present invention becomes Li₂ZnTiO₄��

Preparation method's step of this microwave dielectric ceramic material is:

(1) be 99.9%(weight percent by purity) more than Li₂CO₃, ZnO and TiO₂Starting powder press Li₂ZnTiO₄Composition weigh batching;

(2) step (1) raw material wet ball-milling being mixed 8 hours, ball-milling medium is dehydrated alcohol, after oven dry in 850 DEG C of air atmosphere pre-burning 4 hours;

(3) in the powder that step (2) is obtained, binding agent is added and after granulation, then compression moulding, finally sinters 4 hours in 900 ~ 960 DEG C of air atmosphere; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for the 3% of powder total mass.

The advantage of the present invention: Li₂ZnTiO₄Pottery sintering below 960 DEG C is good, and specific inductivity reaches 8.4��9.8, especially the temperature factor �� of resonant frequency_?Little, temperature stability is good; Quality factor q f value, up to 24,000-37,000GHz, extensively for the manufacture of the microwave devices such as various medium substrate, resonator and wave filter, can industrially have great using value.

Embodiment

Embodiment:

Table 1 shows 4 specific embodiments and the microwave dielectric property thereof of the different sintering temperatures forming the present invention. Its preparation method as mentioned above, it is necessary, carry out the evaluation of microwave dielectric property by cylindrical dielectric resonator method.

This pottery extensively for the manufacture of the microwave devices such as various medium substrate, resonator and wave filter, can meet the technology needs of the system such as mobile communication and satellite communications.

Table 1:

Claims (1)

1. the composite oxides as the application of temperature-stable dielectric constant microwave dielectric ceramic, it is characterised in that the chemical group of described composite oxides becomes: Li₂ZnTiO₄;

Preparation method's step of described composite oxides is:

(1) be 99.9%(weight percent by purity) more than Li₂CO₃, ZnO and TiO₂Starting powder press Li₂ZnTiO₄Composition weigh batching;

(2) step (1) raw material wet ball-milling being mixed 8 hours, ball-milling medium is dehydrated alcohol, after oven dry in 850 DEG C of air atmosphere pre-burning 4 hours;

(3) in the powder that step (2) is obtained, binding agent is added and after granulation, then compression moulding, finally sinters 4 hours in 900 ~ 960 DEG C of air atmosphere; Described binding agent adopts mass concentration to be the polyvinyl alcohol solution of 5%, and the addition of polyvinyl alcohol accounts for the 3% of powder total mass.