CN108975914B - ZnO-TiO2-Nb2O5Base LTCC material and preparation method thereof - Google Patents

Abstract

The invention belongs to the field of electronic ceramics and manufacture thereof, and relates to ZnO-TiO₂‑Nb₂O₅A base LTCC material and a preparation method thereof. The main crystal phase of the material provided by the invention is Zn_0.5Ti_0.5NbO₄Phase, secondary crystal phase Zn_0.15Nb_0.3Ti_0.55O₂Phase, and a secondary crystal phase ZnNb is also present during sintering at 850-875 DEG C₂O₆The sintering temperature is as low as 850 ℃, the dielectric constant is 40-48, and the loss is as low as 2.9 multiplied by 10^‑4Temperature coefficient of frequency τ_f+ 60-24 ppm/. degree.C. Compared with the prior art, the preparation method reduces the preparation of the auxiliary agent and the secondary batching after the pre-sintering, simplifies the preparation process, and finally prepares the ZnO-TiO₂‑Nb₂O₅The performance of the base system LTCC material is superior to that of the prior art.

Description

ZnO-TiO2-Nb2O5Base LTCC material and preparation method thereof

Technical Field

The invention belongs to the field of electronic ceramics and manufacture thereof, and relates to ZnO-TiO₂-Nb₂O₅A low temperature co-fired ceramic (LTCC) material and a preparation method thereof.

Background

Modern communication systems are increasingly demanding in microwave dielectric ceramic materials. Microwave dielectric ceramic materials are now widely used in dielectric resonators, microstrip antennas, filters, and the like. With the continuous high-speed development of the domestic communication industry in recent decades, the radio mobile communication equipment is frequently updated, and has the development characteristics of small size, stronger function and pursuit of low cost. The Low Temperature Co-fired Ceramic (LTCC) technology plays a key role in the production of multilayer Ceramic circuits, and the volume of various communication radio frequency devices can be effectively reduced due to the adoption of a laminated three-dimensional layout process design, so that the LTCC technology is widely applied to the fields of medical treatment, automobile manufacturing, communication equipment and the like.

The LTCC material is required to be co-fired with electrodes such as Ag and Cu used in the current production, so that the Ag electrode is prevented from melting due to overhigh temperature (the melting point of Ag is 961 ℃). Therefore, the LTCC material is required to have lower sintering temperature (less than or equal to 950 ℃) and good chemical compatibility with an electrode. Further, the microwave dielectric ceramics to be used are required to have different relative dielectric constants (. epsilon.) depending on the field of use_r) High quality factor (Qxf) and near-zero temperature coefficient of resonant frequency (τ)_f). Wherein it corresponds to a dielectric constant ε_rPhysical parameters commonly used to characterize dielectric or polarization properties of dielectric materials, whose values are equal to the ratio of the capacitance of a capacitor of the same size made with the predicted material as the medium and with the vacuum as the medium; the quality factor Qxf is used to represent a quality index of the ratio of the energy stored in an energy storage device (such as an inductance coil, a capacitor, etc.) and the resonant circuit to the energy lost per cycle; temperature coefficient of resonance frequency tau_fExpressed as the sensitivity of the resonance frequency to temperature changes.

At present, on ZnO-TiO₂-Nb₂O₅The research on the sintering temperature reduction of the base ceramics focuses on adding sintering aids, such as CuO and Li, to the pre-sintered material₂O-ZnO-B₂O₃、ZnO、BaO-CuO-B₂O₃And the like. According to the existing report, the temperature of the ceramic matrix can be reduced to 875-950 ℃, but the dielectric constant epsilon of the final ceramic is_rLower (30) and τ_fThe value is large (-59 ppm/. degree.C.).

Disclosure of Invention

Aiming at solving the problems or the defects, the ZnO-TiO₂-Nb₂O₅Base LTCC Material epsilon_rLower and τ_fThe invention provides a ZnO-TiO with larger value₂-Nb₂O₅The electronic ceramic material can be sintered and compacted at low temperature and simultaneously improve the microwave dielectric property.

The ZnO-TiO₂-Nb₂O₅Based LTCC material with Zn as main crystal phase_0.5Ti_0.5NbO₄Phase, secondary crystal phase Zn_0.15Nb_0.3Ti_0.55O₂Phase, and a secondary crystal phase ZnNb is also present during sintering at 850-875 DEG C₂O₆The sintering temperature is as low as 850 ℃, the dielectric constant is 40-48, and the loss is as low as 2.9 multiplied by 10^-4Temperature coefficient of frequency τ_f+60～-24ppm/℃。

The raw materials are as follows: ZnO, TiO₂、Nb₂O₅、Li₂CO₃、B₂O₃And SiO₂Mixing (0.15+0.35x) ZnO- (0.55-0.05x) TiO according to a chemical formula₂-(0.15+0.35x)Nb₂O₅-(0.3y+xy)Li₂CO₃-(0.5y+xy)B₂O₃ -(0.2y+xy)SiO₂(x is 0.4 to 0.6mol, and y is 0.01 to 0.04mol) by a solid phase method.

The preparation method comprises the following steps:

step 1, adding ZnO and TiO₂、Nb₂O₅、Li₂CO₃、B₂O₃And SiO₂The original powder is prepared into (0.15+0.35x) ZnO- (0.55-0.05x) TiO according to a chemical general formula₂-(0.15+0.35x)Nb₂O₅-(0.3y+xy)Li₂CO₃-(0.5y+xy)B₂O₃ -(0.2y+xy)SiO₂(x＝0.4-0.6mol,y＝0.01-0.04mol)；

Step 2, filling the ingredients obtained in the step 1 into a ball milling tank, taking zirconium balls and deionized water as grinding media, and mixing the following ingredients: zirconium ball: carrying out planetary ball milling for 5-7 hours at a deionized water mass ratio of 1: 5-7: 2-4, then drying at 80-100 ℃, sieving by using a 40-60 mesh screen, and finally presintering for 2-4 hours at 900-1000 ℃ in an atmosphere;

step 3, mixing the powder subjected to the pre-sintering in the step 2 into powder: zirconium ball: performing secondary ball milling on the deionized water in a mass ratio of 1: 5-7: 1-3 for 3-6 hours, taking out and drying, and adding an acrylic acid solution into the obtained powder for granulation;

and 4, pressing and forming the powder granulated in the step 3, removing the glue, raising the temperature to 850-950 ℃, and preserving the heat for 4-6 hours to obtain the low-temperature sintered microwave dielectric ceramic.

In conclusion, the invention uses ZnO and TiO as raw materials₂、Nb₂O₅、Li₂CO₃、B₂O₃And SiO₂The preparation method reduces the preparation of the auxiliary agent and the secondary batching after the pre-sintering (simplifies the preparation process) compared with the prior art, and finally the prepared ZnO-TiO is₂-Nb₂O₅The performance of the base system LTCC material is superior to that of the prior art.

Drawings

Fig. 1 shows the shrinkage curve when x is 0.43mol and y is 0.01 mol.

Fig. 2 is an XRD pattern of examples 1-4 where x is 0.43mol and y is 0.01 mol.

Fig. 3 is an SEM image of example 5 with x being 0.43mol and y being 0.01 mol.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

Step 1, adding ZnO and TiO₂、Nb₂O₅、Li₂CO₃、B₂O₃And SiO₂The original powder is prepared into (0.15+0.35x) ZnO- (0.55-0.05x) TiO according to a chemical general formula₂-(0.15+0.35x)Nb₂O₅-(0.3y+xy)Li₂CO₃-(0.5y+xy)B₂O₃–(0.2y+xy)SiO₂(x ═ 0.43mol, y ═ 0.01mol and x ═ 0.43mol, y ═ 0.02 mol);

step 2, filling the ingredients obtained in the step 1 into a ball milling tank, taking zirconium balls and deionized water as grinding media, and mixing the following ingredients: zirconium ball: carrying out planetary ball milling for 6 hours at the mass ratio of deionized water of 1:6:4, then drying at 100 ℃, sieving by using a 60-mesh sieve, and finally presintering for 3 hours at 950 ℃ in atmosphere;

and 3, putting the pre-sintered powder into a ball milling tank for secondary ball milling, and mixing the powder: zirconium ball: carrying out planetary ball milling for 4 hours according to the mass ratio of the deionized water to the deionized water of 1:6:3, taking out and drying, and adding an acrylic acid solution into the obtained powder for granulation;

and 4, putting the granulated powder into a phi 15 die, performing dry pressing under the pressure of 20MPa to form a cylindrical block body (the size of the cylindrical block body is 15mm multiplied by 10 mm), then performing heat preservation on the cylindrical block body for 2 hours at 450 ℃ to remove the binder, then raising the temperature to 850-975 ℃, performing heat preservation for 4 hours, and finally preparing the low-temperature sintered microwave dielectric ceramic.

Fig. 1 shows the shrinkage curve when x is 0.43mol and y is 0.01 mol. It can be seen that the temperature at which the sample begins to shrink is around 600 c, and the sample reaches a maximum shrinkage of around 17% when the temperature is increased to around 950 c.

FIG. 2 is the XRD diffraction patterns of examples 1-4, from which it can be seen that the main crystal phase of the ceramic is Zn_0.5Ti_0.5NbO₄Matched with JCPDS card number 48-0323, the secondary crystal phase is Zn_0.15Nb_0.3Ti_0.55O₂(JCPDS # 79-1186). In examples 1 and 2, a small amount of ZnNb is present₂O₆Phase, card number (JCPDS # 37-1371). In examples 3 to 4, ZnNb was observed as the sintering temperature was increased₂O₆The phases disappeared.

FIG. 3 is a SEM surface topography of example 5. It is seen from the figure that the sample surface is porous, and has crystal grains with different sizes and states, and the crystal grain size is smaller.

The compositions and microwave dielectric properties of the examples are shown in the table below

As can be seen from the above table data, the samples all achieved excellent performance between 850 ℃ and 975 ℃, and for examples 1 to 6, the dielectric constant of the samples increased and then decreased with increasing sintering temperature, and the best dielectric was 42.22 at 925 ℃ sintering (example 4), at which time the Q f value of the samples reached 18904 GHz. Taking into account τ_fThe sample achieved excellent performance at example 2, where the sintering temperature was 875 ℃. For examples 7-12, the dielectric constant of the samples increased with temperature from 41.73 to 47.53, and the Q x f value of the samples increased from 11413 to 13263 GHz. The overall optimum performance was also achieved at a sintering temperature of 875 ℃ (example 8).

In summary, the invention adjusts the raw materials of ZnO and TiO₂、Nb₂O₅、Li₂CO₃、B₂O₃And SiO₂The molar ratio of the components is high, and finally ZnO-TiO with excellent performance is obtained at low temperature₂-Nb₂O₅A microwave dielectric ceramic system.

Claims (2)

1. ZnO-TiO₂-Nb₂O₅The LTCC material is characterized in that:

the main crystal phase being Zn_0.5Ti_0.5NbO₄Phase, secondary crystal phase Zn_0.15Nb_0.3Ti_0.55O₂Phase, the sintering temperature is 875-950 ℃, and a paracrystalline phase ZnNb is also existed during sintering at 875 DEG C₂O₆Phase, dielectric constant 40 to 48, loss as low as 2.9X 10^-4Temperature coefficient of frequency τ_f -23.47～-15.78ppm/℃；

The raw materials are as follows: ZnO, TiO₂、Nb₂O₅、Li₂CO₃、B₂O₃And SiO₂Mixing (0.15+0.35x) ZnO- (0.55-0.05x) TiO according to a chemical formula₂-(0.15+0.35x)Nb₂O₅-(0.3y+xy)Li₂CO₃-(0.5y+xy)B₂O₃ -(0.2y+xy)SiO₂X =0.4-0.6, y =0.01-0.04, prepared by a solid phase method.

2. The ZnO-TiO of claim 1₂-Nb₂O₅The preparation method of the base LTCC material comprises the following specific steps:

step 1, adding ZnO and TiO₂、Nb₂O₅、Li₂CO₃、B₂O₃And SiO₂The original powder is prepared into (0.15+0.35x) ZnO- (0.55-0.05x) TiO according to a chemical general formula₂-(0.15+0.35x)Nb₂O₅-(0.3y+xy)Li₂CO₃-(0.5y+xy)B₂O₃ -(0.2y+xy)SiO₂ ，x=0.4-0.6, y=0.01-0.04；

Step 2, filling the ingredients obtained in the step 1 into a ball milling tank, taking zirconium balls and deionized water as grinding media, and mixing the following ingredients: zirconium ball: carrying out planetary ball milling for 5-7 hours at a deionized water mass ratio of 1: 5-7: 2-4, then drying at 80-100 ℃, sieving by using a 40-60 mesh screen, and finally presintering for 2-4 hours at 900-1000 ℃ in an atmosphere;

step 3, mixing the powder subjected to the pre-sintering in the step 2 into powder: zirconium ball: performing secondary ball milling on the deionized water in a mass ratio of 1: 5-7: 1-3 for 3-6 hours, taking out and drying, and adding an acrylic acid solution into the obtained powder for granulation;

and 4, pressing and molding the powder granulated in the step 3, removing the glue, raising the temperature to 875-950 ℃, and preserving the heat for 4-6 hours to obtain the low-temperature sintered microwave dielectric ceramic.

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