A high-performance microwave dielectric ceramic material suitable for ULTCC and its preparation method

Abstract

A high-performance microwave dielectric ceramic material suitable for ULTCC and its preparation method are disclosed. The ceramic material, by weight percentage, consists of 50-75% ceramic main phase material and 25-50% sintering aid LiF. The preparation method includes the following steps: first, preparing the main crystalline phase powder; then adding LiF powder as a sintering aid and mixing; adding anhydrous ethanol and zirconium balls and ball milling; successively drying and sieving; adding a binder; heating and stirring; sieving again; and finally pressing, debinding, and sintering to obtain the microwave dielectric ceramic material. The preparation process of this invention is reliable, has a high fault tolerance, and is suitable for industrial production. The ceramic material obtained through the traditional solid-state reaction method has a simple composition and can simultaneously possess a high quality factor and a near-zero resonant frequency temperature coefficient, thus solving the problem that molybdate microwave dielectric ceramic systems struggle to achieve both a high quality factor and good temperature stability.

Description

Technical Field

[0001] This invention belongs to the field of electronic information materials and components technology, specifically relating to a high-performance microwave dielectric ceramic material suitable for ULTCC and its preparation method. Background Technology

[0002] To meet the co-firing requirements of microwave dielectric ceramics and aluminum electrodes in ultra-low temperature co-fired ceramics (ULTCC) technology, current mainstream research focuses on developing ceramic systems with extremely low intrinsic sintering temperatures, or adding appropriate sintering aids to pure-phase materials to reduce the sintering temperature of composite systems. Among these, molybdate-based microwave dielectric ceramics have attracted widespread attention due to their inherently low sintering temperature and excellent microwave dielectric properties.

[0003] However, existing molybdate ceramics still have the following two drawbacks when applied to ULTCC technology: Firstly, there is an imbalance in intrinsic properties. While most pure-phase molybdate materials with intrinsic sintering temperatures meeting ULTCC requirements can achieve high quality factors (Q×f values), their resonant frequency temperature coefficient (…) is unbalanced. The values ​​of ) often exhibit large negative values, resulting in significant frequency drift and poor thermal stability of the device when the operating temperature changes, making it difficult to meet the needs of practical applications.

[0004] Secondly, modification is costly. To improve... To address the negative value problem, existing technologies typically employ ion substitution or composite phase design for control. However, while these modification methods adjust the temperature coefficient, they inevitably introduce lattice defects or heterogeneous phase interfaces, thereby significantly increasing the dielectric loss of the material and causing a sharp deterioration in the Q×f value.

[0005] Therefore, it is evident that existing technologies consistently struggle to achieve both "high Q×f value" and "near-zero" at ultra-low sintering temperatures. There is a clear performance trade-off between the two. This deficiency severely restricts the widespread application of molybdate microwave dielectric ceramics in the high-end ULTCC technology field. Summary of the Invention

[0006] The purpose of this invention is to provide a high-performance microwave dielectric ceramic material suitable for ULTCC and its preparation method. The preparation process of this method is reliable, has a high fault tolerance, and is suitable for industrial production. The ceramic material prepared by the traditional solid-state reaction method has a simple composition and can simultaneously have a high quality factor and a near-zero resonant frequency temperature coefficient, thus solving the problem that molybdate microwave dielectric ceramic systems are difficult to balance with both a high quality factor and good temperature stability.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is: a high-performance microwave dielectric ceramic material suitable for ULTCC, comprising 50-75% ceramic main phase material by weight. It consists of 25-50% sintering aid LiF.

[0008] Preferably, the high-performance microwave dielectric ceramic material suitable for ULTCC comprises, by weight percentage, 72-77% of... Composed of 25-28% LiF; or, by weight percentage, 67-72% Composed of 28-33% LiF; or, by weight percentage, 57-62% Composed of 38-43% LiF; or, by weight percentage, 50-52% It consists of 48-50% LiF.

[0009] Preferred high-performance microwave dielectric ceramic materials suitable for ULTCC, by weight percentage, consist of 75% Composed of 25% LiF; or by weight percentage, of 70% Composed of 30% LiF; or by weight percentage, of 60% Composed of 40% LiF; or by weight percentage, of 50% It consists of 50% LiF.

[0010] To achieve the above-mentioned objectives, this invention also provides a method for preparing the high-performance microwave dielectric ceramic material suitable for ULTCC, comprising the following steps: S1, according to chemical formula Weighing chemical raw materials according to the measurement ratio , The mixture is thoroughly mixed to obtain an initial powder; anhydrous ethanol and zirconium balls are added to the initial powder and then ball-milled to obtain a slurry; the slurry is then dried, sieved, and pre-calcined in air to obtain the main crystalline phase. Powder; S2. Mix the main crystalline phase obtained in step S1 according to the specified ratio. The powder was mixed with LiF powder as a sintering aid to obtain a mixed raw material. Anhydrous ethanol and zirconium balls were added to the mixed raw material and then ball milled to obtain a uniformly dispersed composite ceramic slurry. The composite ceramic slurry was dried to obtain composite ceramic powder, and then sieved. S3. Add paraffin wax as a binder to the composite ceramic powder after sieving in step S2, heat and stir until uniformly mixed, and then sieve again to obtain a granular molding powder with good flowability. S4. Place the granular molding powder obtained in step S3 into a mold and press it to obtain a dense ceramic green body. S5. After debinding the ceramic green body obtained in step S4, sinter it to obtain a high-performance microwave dielectric ceramic material suitable for ULTCC.

[0011] Preferably, in step S1, the mass ratio of the initial mixed powder, anhydrous ethanol, and zirconium balls is 1:1:1.5; the pre-firing temperature is 700℃, and the pre-firing time is 2-8h; in step S2, the mass ratio of the mixed raw materials, anhydrous ethanol, and zirconium balls is 1:1:1.5.

[0012] Preferably, in steps S1 and S2, ball milling is performed for 8-16 hours; drying temperature is 60-85℃; and the material is passed through a 40-80 mesh sieve; in step S3, the material is passed through a 40-80 mesh sieve.

[0013] Preferably, in steps S1 and S2, the ball milling is performed for 12 hours; the drying temperature is 78°C; in step S1, the material is passed through a 40-mesh sieve; and in steps S2 and S3, the material is passed through an 80-mesh sieve.

[0014] Preferably, in step S3, the mass of paraffin is 8 wt% of the sieved composite ceramic powder.

[0015] Preferably, in step S4, a powder tablet press is used to compress the tablets under a pressure of 2-4 MPa.

[0016] Preferably, in step S5, the sintering temperature is 555~605℃ and the sintering time is 4-6h.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides The ceramic samples (x=25, 30, 40, 50) are a series of low dielectric constant ULTCC microwave dielectric ceramic materials with a low sintering temperature range (ST=555 ℃ ~ 605 ℃) and a high quality factor (Q׃= 20012.9). The temperature coefficient of the resonant frequency is continuously adjustable. The dielectric constant is 6.66 ~ 15.09, with a pH of 27.62 ppm / °C. The dielectric properties are optimal when ST = 585°C and x = 40. , , This series of microwave dielectric ceramics has a simple composition and controllable phase structure, and simultaneously possesses a high quality factor and a near-zero resonant frequency temperature coefficient (-30~30 ppm / °C). The preparation process used is stable and mature; the process is pollution-free and suitable for industrial production. In particular, this series of ceramics has the characteristic of an ultra-low sintering temperature range, and its application prospects in the field of ultra-low temperature co-fired ceramics are broad. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the embodiments.

[0019] Example A method for preparing a high-performance microwave dielectric ceramic material suitable for ULTCC includes the following steps: S1, according to chemical formula Weighing chemical raw materials according to the measurement ratio (Analytical grade) (Analytical grade), mixed evenly to obtain an initial mixed powder; anhydrous ethanol and zirconium balls were added to the initial mixed powder and ball-milled for 12 hours to obtain a mixed slurry; the mass ratio of the initial mixed powder, anhydrous ethanol, and zirconium balls was 1:1:1.5; the mixed slurry was dried at 78°C, passed through a 40-mesh sieve, and then pre-calcined at 700°C for 6 hours in air atmosphere to obtain the main crystalline phase. Powder; S2. Mix the main crystalline phase obtained in step S1 according to the specified ratio. The powder was mixed with LiF (analytical grade) powder as a sintering aid to obtain a mixed raw material. Anhydrous ethanol and zirconium balls were added to the mixed raw material and ball milled for 12 hours to obtain a uniformly dispersed composite ceramic slurry. The mass ratio of the mixed raw material, anhydrous ethanol and zirconium balls was 1:1:1.5. The composite ceramic slurry was dried at 78°C to obtain composite ceramic powder, and then passed through an 80-mesh sieve. S3. Add 8wt% paraffin wax as a binder to the composite ceramic powder after sieving in step S2, heat it in a heating device (such as a container on a resistance furnace) and stir until uniformly mixed, and then pass it through an 80-mesh sieve again to obtain a granular molding powder with good flowability. S4. Place the granular molding powder obtained in step S3 into a mold, and use a powder press to press and shape it under a pressure of 3MPa to obtain a dense ceramic green body; the green body dimensions are: diameter d=10mm, thickness h=5mm; S5. After debinding the ceramic green body obtained in step S4, sinter it at 555~605℃ for 4 hours to obtain a high-performance microwave dielectric ceramic material suitable for ULTCC; the microwave dielectric ceramic material consists of 50~75% ceramic main phase material by weight percentage. It is composed of 25-50% sintering aid LiF. Finally, the microwave dielectric ceramic material prepared is tested for its microwave dielectric properties using a network analyzer.

[0020] The specific steps of Comparative Examples 1-4 and Specific Examples 1-24 are consistent with those in the above examples. The relevant process parameters and microwave dielectric properties of Comparative Examples 1-4 and Specific Examples 1-24 are detailed in Table 1.

[0021] Table 1. Relevant process parameters and microwave dielectric properties of Comparative Examples 1-4 and Examples 1-24 As can be seen from Table 1, the comparative examples 1-4 provided The ceramic samples (x=5, 10, 15, 20) are a series of materials with high resonant frequency temperature coefficients; while the present invention provides... The ceramic samples (x=25, 30, 40, 50) are a series of low dielectric constant ULTCC microwave dielectric ceramic materials with a low sintering temperature range (ST=555℃~605℃) and a high quality factor. The temperature coefficient of the resonant frequency is continuously adjustable. The dielectric constant is 6.66 ~ 15.09, with a pH of 27.62 ppm / °C. The dielectric properties are optimal when ST = 585°C and x = 40. , , The ceramic materials prepared by this invention using the traditional solid-state reaction method possess both a high quality factor and a near-zero resonant frequency temperature coefficient (-30~30ppm / °C). The preparation process used is stable and mature; the process is pollution-free and suitable for industrial production. In particular, this series of ceramics has the characteristic of an ultra-low sintering temperature range, and its application prospects in the field of ultra-low temperature co-fired ceramics are broad.

Claims

1. A high-performance microwave dielectric ceramic material suitable for ULTCC, characterized in that, By weight percentage, it consists of 50-75% ceramic main phase material. It consists of 25-50% sintering aid LiF.

2. The high-performance microwave dielectric ceramic material suitable for ULTCC according to claim 1, characterized in that, By weight percentage, it consists of 72-77%. It consists of 25-28% LiF; Or, by weight percentage, 67-72% Composed of 28-33% LiF; Or, by weight percentage, 57-62% It consists of 38-43% LiF; Or, by weight percentage, 50-52% It consists of 48-50% LiF.

3. The high-performance microwave dielectric ceramic material suitable for ULTCC according to claim 2, characterized in that, By weight percentage, it consists of 75% It consists of 25% LiF; Or, by weight percentage, 70% It consists of 30% LiF; Or, by weight percentage, 60% It consists of 40% LiF; Or, by weight percentage, 50% It consists of 50% LiF.

4. A method for preparing a high-performance microwave dielectric ceramic material suitable for ULTCC as described in any one of claims 1-3, characterized in that, Includes the following steps: S1, according to chemical formula Weighing chemical raw materials according to the measurement ratio , The mixture is thoroughly mixed to obtain an initial powder; anhydrous ethanol and zirconium balls are added to the initial powder and then ball-milled to obtain a slurry; the slurry is then dried, sieved, and pre-calcined in air to obtain the main crystalline phase. Powder; S2. Mix the main crystalline phase obtained in step S1 according to the specified ratio. The powder was mixed with LiF powder as a sintering aid to obtain a mixed raw material. Anhydrous ethanol and zirconium balls were added to the mixed raw material and then ball milled to obtain a uniformly dispersed composite ceramic slurry. The composite ceramic slurry was dried to obtain composite ceramic powder, and then sieved. S3. Add paraffin wax as a binder to the composite ceramic powder after sieving in step S2, heat and stir until uniformly mixed, and then sieve again to obtain a granular molding powder with good flowability. S4. Place the granular molding powder obtained in step S3 into a mold and press it to obtain a dense ceramic green body. S5. After debinding the ceramic green body obtained in step S4, sinter it to obtain a high-performance microwave dielectric ceramic material suitable for ULTCC.

5. The method for preparing a high-performance microwave dielectric ceramic material suitable for ULTCC according to claim 4, characterized in that, In step S1, the mass ratio of the initial mixed powder, anhydrous ethanol, and zirconium balls is 1:1:1.5; the pre-firing temperature is 700℃, and the pre-firing time is 2-8h; in step S2, the mass ratio of the mixed raw materials, anhydrous ethanol, and zirconium balls is 1:1:1.

5.

6. The method for preparing a high-performance microwave dielectric ceramic material suitable for ULTCC according to claim 4, characterized in that, In steps S1 and S2, ball milling is performed for 8-16 hours; drying temperature is 60-85℃; and the material is passed through a 40-80 mesh sieve. In step S3, the material is passed through a 40-80 mesh sieve.

7. The method for preparing a high-performance microwave dielectric ceramic material suitable for ULTCC according to claim 5, characterized in that, In steps S1 and S2, the ball milling is carried out for 12 hours; the drying temperature is 78℃; in step S1, the material is passed through a 40-mesh sieve; in steps S2 and S3, the material is passed through an 80-mesh sieve.

8. The method for preparing a high-performance microwave dielectric ceramic material suitable for ULTCC according to claim 4, characterized in that, In step S3, the mass of paraffin is 8 wt% of the sieved composite ceramic powder.

9. The method for preparing a high-performance microwave dielectric ceramic material suitable for ULTCC according to claim 4, characterized in that, In step S4, a powder tablet press is used to compress and form the tablets under a pressure of 2-4 MPa.

10. The method for preparing a high-performance microwave dielectric ceramic material suitable for ULTCC according to claim 4, characterized in that, In step S5, the sintering temperature is 555~605℃, and the sintering time is 4-6h.

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