CN106986636B - A kind of low temperature sintering microwave ceramic material and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of electronic functional ceramics and components, relates to microwave devices and circuits, and specifically provides a low-temperature sintered microwave ceramic material and a preparation method thereof, which are used to overcome the disadvantage that the temperature coefficient of the existing low-temperature sintered microwave ceramics is not zero-adjusted; The chemical expression of the invented microwave ceramic material is: Ca _5+A Co _4+B V _{6+ C} O ₂₄ -XCaTiO ₃ , where A+B+C=‑0.05,‑0.05≤A≤0,‑0.05≤B≤ 0, ‑0.05≤C≤0, 2wt%<X≤10wt%; the microwave ceramic can be co-fired with metallic silver without chemical reaction with silver, and the temperature coefficient of resonant frequency can be achieved: ‑10ppm/℃～+10ppm /℃, that is, zero temperature coefficient; at the same time, the material has the characteristics of low sintering temperature, and does not need to add any sintering aid, which effectively prevents the deterioration of its dielectric properties caused by the sintering aid, and maintains a high density and Porcelain body strength, simple preparation process, environmental protection and energy saving, good repetition, low cost, easy to realize industrialized production.

Description

A kind of low temperature sintering microwave ceramic material and preparation method thereof

technical field

The invention belongs to the technical field of electronic functional ceramics and components, in particular to microwave devices and circuits, and relates to a low-temperature sintered microwave ceramic material and a preparation method thereof.

Background technique

The rapid development of microelectronic devices and integrated devices has put forward high requirements for the miniaturization and light weight of electronic equipment. A single active device integration has been unable to meet the generation application. Passive devices must be miniaturized. It has become a trend, but the traditional use of large Bulk metal resonators make the integration of microstrip circuits difficult. Microwave multi-chip module (MMCM) modules are widely used due to their technical characteristics of light weight, small size, low cost and high reliability. The effective way to realize this technology is to develop multi-layer components. Low Temperature Co-fired Ceramics (LTCC) technology has become a main way to realize the integration of current electronic components because of its advantages of high integration density and good high frequency characteristics. The multi-layer wiring structure adopted by LTCC technology is a three-dimensional assembly of passive device integration and passive device hybrid integration technology, which can realize the integration of passive components (resistors, capacitors, inductors, filters) and transmission lines, and can Mounting ICs plays an important role in realizing miniaturization, modularization of multiple functions, and improved signal reliability.

The interconnecting conductors used in LTCC technology generally have silver metal with excellent electrical conductivity, and its melting point is about 961 ° C, which requires that the ceramic materials used in LTCC technology must be sintered and dense below 950 ° C. In addition, applied in LTCC technology. Microwave ceramic materials should also have the following characteristics: (1) suitable dielectric constant to facilitate the miniaturization of the device; (2) high quality factor to reduce loss, generally requiring Q×f≥20000GHz; (3) near-zero Temperature coefficient (10～+10ppm/°C) to facilitate temperature stability. However, many high-temperature sintered microwave ceramics must be added with sintering aids (low melting point oxides such as B ₂ O ₃ , glass and V ₂ O ₅ ) in order to meet the temperature requirements of LTCC (the sintering densification temperature is lower than 950°C). For example in OhsatoH, Ohhashi T, Kato H, et al. Microwave Dielectric Properties and Structure of the Ba _6-3x Sm _8+2x Ti ₁₈ O ₅₄ Solid Solutions [J]. Japanese Journal of Applied Physics, 1995, 34(1): It was reported in 187-191 that Ba _6-3x Sm _8+2x Ti ₁₈ O ₅₄ reduced the sintering temperature from 1733K to 1473K by adding 0.5wt% B ₂ O ₃ , and also lowered the quality factor and dielectric constant, which is typical A case of sacrificing microwave dielectric properties for low temperature sintering. It can be seen that although the sintering aid can reduce the sintering effect, the addition of the sintering aid will deteriorate its microwave dielectric properties, and at the same time reduce the density and the strength of the porcelain body; the structure formed by the addition of the sintering aid is difficult to control. , the preparation process is relatively complicated, and usually the sintering aid must be prepared separately, such as through the glass melting process, which not only increases the complexity of the process, but also consumes a lot of energy and increases energy consumption. Therefore, the development of low-temperature sintered microwave ceramics has become a trend.

Vanadate system is a new type of LTCC microwave dielectric material, which not only has a low sintering temperature, but also has the advantages of high Q×f value, and has gradually attracted attention in recent years. For example, it is reported in Journal of the American Ceramic Society, 2013, 96(6): 1691-1693 "Novel Series of Low-Firing Microwave DielectricCeramics: Ca ₅ A ₄ (VO ₄ ) ₆ (A2+=Mg, Zn)", Ca ₅ Zn Microwave dielectric properties of ₄ (VO ₄ ) ₆ and Ca ₅ Mg ₄ (VO ₄ ) ₆ microwave ceramics sintered at 725℃ and 800℃: dielectric constants 11.7 and 9.2, quality factor Q×f=49400GHz and 53300GHz, temperature Coefficients -83ppm/℃ and -50ppm/℃; reported in Journal of Materials Science: Materials in Electronics 2016, 27(7): 7292-7296 "Microwave dielectric properties of low temperature sintering Ca ₅ Mn ₄ (VO ₄ ) ₆ ", Ca ₅ Microwave dielectric properties of Mn ₄ (VO ₄ ) ₆ : dielectric constant 11.7, quality factor Q×f=33800GHz, temperature coefficient -70ppm/°C. Although the above-mentioned vanadate system microwave ceramics can meet the temperature requirements of LTCC (the sintering and densification temperature is lower than 950 °C), they cannot meet the requirements of near-zero temperature coefficient, which seriously limits their application in microwave devices. Microwave ceramics for the various requirements of LTCC technology have become an urgent need.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a low-temperature sintered microwave ceramic material and a preparation method thereof, so as to overcome the disadvantage that the temperature coefficient of the existing low-temperature sintered microwave ceramic is not zero-adjusted; the chemical expression of the microwave ceramic material is: Ca _5+A Co _4+B V _{6+ C} O ₂₄ -XCaTiO ₃ , wherein A+B+C=-0.05, -0.05≤A≤0, -0.05≤B≤0, -0.05≤C≤0, 0<X≤15; The microwave ceramic can be co-fired with metallic silver without chemical reaction with silver, and can realize the temperature coefficient of resonant frequency: -10ppm/℃～+10ppm/℃, meanwhile, the preparation process is simple, the cost is low, the repetition is good, and the industrialization is easy. Production.

To achieve the above object, the technical scheme adopted in the present invention is:

A low-temperature sintering microwave ceramic material, characterized in that the chemical expression of the microwave ceramic material is: Ca _5+A Co _4+B V _6+C O ₂₄ -XCaTiO ₃ , wherein A+B+C=-0.05 , -0.05≤A≤0, -0.05≤B≤0, -0.05≤C≤0, 2wt%<X≤10wt% (especially 4wt%<X≤8wt%).

The main crystal phase of the microwave dielectric ceramic is Ca ₅ Co ₄ (VO ₄ ) ₆ , and the secondary crystal phase is CaTiO ₃ .

The preparation method of the above-mentioned low-temperature sintered microwave ceramic material comprises the following steps:

Step 1: Using CaCO ₃ , Co ₂ O ₃ , V ₂ O ₅ and CaTiO ₃ as raw materials, according to the molar ratio of CaCO ₃ : Co ₂ O ₃ : V ₂ O ₅ =5+A:4+B:6+C ingredients, mix evenly to obtain a mixture, wherein A+B+C=-0.05, -0.05≤A≤0, -0.05≤B≤0, -0.05≤C≤0, 2wt%<X≤10wt%;

Step 2: the mixture obtained in step 1 is ball-milled, dried and sieved successively to obtain dry powder; and pre-sintered at a temperature of 750-850° C. for 4-6 hours to obtain a pre-sintered material;

Step 3: pass the pre-sintered material obtained in step 2 through ball milling, drying and sieving in turn to obtain secondary ball abrasive;

Step 4: adding 5-10 wt% of the binder PVA to the secondary ball abrasive obtained in step 3 and mixing, granulating and molding to obtain a green body;

Step 5: sintering the green body obtained in step 4 at a temperature of 900-950° C. and an atmosphere of air for 1-7 hours to obtain the microwave ceramic material.

Further, in the steps 2 and 3, the ball milling time is 4-7 h, and the drying temperature is 80-100°C.

In the step 4, the granulation size is 100-250 mesh, and the granulation is formed under a pressure of 20 MPa.

The beneficial effects of the present invention are:

The invention provides a low-temperature sintered microwave ceramic material and a preparation method thereof. The microwave ceramic material can realize a resonant frequency temperature coefficient of -10ppm/℃～+10ppm/℃, that is, zero temperature coefficient; the material has the characteristics of low sintering temperature (sintering temperature <950℃), no need to add any sintering aids, which effectively prevents the deterioration of its dielectric properties caused by sintering aids, and maintains high density and porcelain body strength; The complex phase structure formed by the sintering agent is difficult to control, and the preparation process is complicated (the sintering agent must be prepared separately, such as through the glass melting process), etc. In conclusion, the present invention provides a zero temperature coefficient low-temperature sintering microwave medium, and at the same time, the The microwave ceramic material has the advantages of simple preparation process, environmental protection and energy saving, good repetition and low cost, and is easy to realize industrial production.

Description of drawings

1 is the XRD diffraction analysis diagram of the microwave ceramic material Ca _5+A Co _4+B V _6+C O ₂₄ -XCaTiO ₃ prepared in Example 1.

FIG. 2 is a SEM electron microscope image of the microwave ceramic material Ca _5+A Co _4+B V _6+C O ₂₄ -XCaTiO ₃ prepared in Example 1. FIG.

Detailed ways

Below in conjunction with specific embodiment, the present invention is further elaborated:

Example 1 to Example 5

The chemical expression of the microwave medium provided in the above embodiment is:

The specific implementation steps for preparing the microwave ceramics of these examples are as follows: Ca _5+A Co _4+B V _6+C O ₂₄ -XCaTiO ₃ , wherein A=B=0, C=-0.05, X=6wt%; the The specific preparation process of microwave ceramic materials is as follows:

Step 1: according to claim 1 according to the chemical formula of the material of the invention, the raw materials CaCO ₃ , Co ₂ O ₃ , V ₂ O ₅ and CaTiO ₃ are weighed and mixed to obtain a mixture;

Step 2: Ball milling the mixture obtained in Step 1 for 7 hours, drying at 100°C and passing through a 40-mesh sieve, and pre-sintering at 775° C. for 3 hours to obtain a pre-sintered material;

Step 3: the obtained pre-sintered material is subjected to secondary ball milling for 7 hours, and after the ball milling is completed, the ball abrasive is dried at 100° C. to obtain secondary ball abrasive;

Step 4: Add 5-10wt% binder PVA to the obtained secondary ball abrasive, and then granulate, and the granulation size is controlled at 100-250 mesh, and under the pressure of 20MPa molding to obtain a green body;

Step 5: The green body obtained in Step 4 is sintered at a temperature of 900-950° C. and an atmosphere of air for 1-7 hours to obtain the final microwave ceramic required.

Step 6: Testing: According to the Hakki-Coleman dielectric resonance method, the microwave dielectric properties of the samples were tested with a network analyzer.

The specific components, process parameters and microwave dielectric properties of Examples 1 to 5 are shown in the following table:

The above descriptions are only specific embodiments of the present invention, and any feature disclosed in this specification, unless otherwise stated, can be replaced by other equivalent or alternative features with similar purposes; all the disclosed features, or All steps in a method or process, except mutually exclusive features and/or steps, may be combined in any way.

Claims (4)

1. A low-temperature sintered microwave ceramic material, wherein the chemical expression of the microwave ceramic material is: Ca _{5+ A} Co _4+B V _6+C O ₂₄ -XCaTiO ₃ , wherein A+B+C= -0.05, -0.05≤A≤0, -0.05≤B≤0, -0.05≤C≤0, 2wt%<X≤10wt%; the main crystal phase of the microwave ceramic material is Ca ₅ Co ₄ (VO ₄ ) _6. The secondary crystal phase is CaTiO ₃ ; the resonant frequency temperature coefficient of the microwave ceramic material is: -10ppm/℃～+10ppm/℃. 2. by the preparation method of the described low temperature sintering microwave ceramic material of claim 1, comprises the following steps: Step 1: Using CaCO ₃ , Co ₂ O ₃ , V ₂ O ₅ and CaTiO ₃ as raw materials, according to the molar ratio of CaCO ₃ : Co ₂ O ₃ : V ₂ O ₅ =5+A:4+B:6+C ingredients, mix evenly to obtain a mixture, wherein A+B+C=-0.05, -0.05≤A≤0, -0.05≤B≤0, -0.05≤C≤0, 2wt%<X≤10wt%; Step 2: the mixture obtained in step 1 is ball-milled, dried and sieved successively to obtain dry powder; and pre-sintered at a temperature of 750-850° C. for 4-6 hours to obtain a pre-sintered material; Step 3: pass the pre-sintered material obtained in step 2 through ball milling, drying and sieving in turn to obtain secondary ball abrasive; Step 4: adding 5-10 wt% of the binder PVA to the secondary ball abrasive obtained in step 3 and mixing, granulating and molding to obtain a green body; Step 5: sintering the green body obtained in step 4 at a temperature of 900-950° C. and an atmosphere of air for 1-7 hours to obtain the microwave ceramic material. 3. The preparation method of the low-temperature sintered microwave ceramic material according to claim 2, wherein in the step 2 and the step 3, the ball milling time is 4-7h, and the drying temperature is 80-100°C. 4. The preparation method of the low-temperature sintered microwave ceramic material according to claim 2, characterized in that, in the step 4, the granulation size is 100-250 mesh, and it is formed under the pressure of 20MPa.

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