Pyrophosphate microwave dielectric ceramic material for ltcc and preparation method thereof

Abstract

A pyrophosphate microwave dielectric ceramic material for LTCC and its preparation method are disclosed. The main crystalline phase of the ceramic material is (Ca,Sr,Zn,Cu)₂P₂O₇. The reactants of the ceramic material include two main materials: the first main material is a mixture of one or more of calcium oxyacid salts, strontium oxyacid salts, zinc oxide, and copper oxide; the second main material is pyrophosphate. The mass ratio of the first and second main materials is (45~60):(35~45). By reasonably controlling the ratio of the first / second main materials and the regulator, the main crystalline phase of the material can be adjusted, ensuring that a pyrophosphate microwave dielectric ceramic with the main crystalline phase of (Ca,Sr,Zn,Cu)₂P₂O₇ and a dielectric constant ε₀ is obtained. r Low (7.1~9.2), high quality factor Q×f (26800~86100GHz), high temperature coefficient of resonant frequency τ f With its near-zero adjustable dielectric constant (-71.4~18.6ppm / ℃), pyrophosphate microwave dielectric ceramics exhibit significant advantages in dielectric loss and sintering compatibility, enabling them to meet low ε... r High Q×f, near-zero τ f The technical requirements are better suited to the needs of high-frequency communication, LTCC (low-temperature co-fired ceramics) and other scenarios.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials, and more particularly to a pyrophosphate microwave dielectric ceramic material for LTCC and its preparation method. Background Technology

[0002] In high-frequency communication scenarios, signal delay has become the primary bottleneck restricting system performance. According to electromagnetic propagation theory, signal delay time is related to the dielectric constant of the medium (ε). r The square root of the resonant frequency (Q×f) is positively correlated with the frequency. Using low dielectric constant materials can directly increase the propagation speed of radio signals, effectively alleviating delay problems. Simultaneously, the high quality factor (Q×f) can significantly reduce energy loss and crosstalk risks in signal transmission, optimizing circuit frequency selection characteristics; a near-zero temperature coefficient of resonant frequency (τ) f This ensures that the material maintains stable performance in complex temperature environments, making it suitable for demanding applications such as aerospace.

[0003] Low-temperature co-fired ceramics (LTCC) technology, with its excellent miniaturization and integration capabilities, is widely recognized as a core implementation solution for next-generation communication system modules. To achieve material compatibility with the LTCC process, the primary task is to lower its sintering temperature to match that of the internal electrode material. Currently, there are four main approaches to achieving low-temperature sintering: ① using specialized sintering equipment, ② utilizing ultrafine raw material powders, ③ adding low-melting-point sintering aids, and ④ developing material systems with inherently low sintering temperatures. Approach ① requires specialized equipment and involves significant investment. Approach ② offers limited reduction in sintering temperature.

[0004] Approach ③, widely adopted in the industry, involves adding low-melting-point additives (including oxides and glasses) to the main crystalline phase of existing ceramic materials to lower the sintering temperature and achieve compatibility with LTCC processes. Examples include patents CN107382299A, CN109608050A, CN111170741A, CN112079631A, CN113004026A, CN113716870A, and CN114315334A. While this method lowers the sintering temperature, it leads to varying degrees of deterioration in the dielectric properties of the materials and significantly increases the difficulty of subsequent process adaptation.

[0005] In recent years, approach ④ has received considerable attention, and microwave materials such as tellurates, molybdates, tungstates, and phosphates have been developed, as evidenced by patents CN113004026A, CN115611628A, and CN120987647A. However, these materials still suffer from significant dielectric losses and exhibit poor sintering compatibility and low quality factors, making them unsuitable for applications such as high-frequency communication and LTCC (low-temperature co-fired ceramics). Therefore, the development of low-ε dielectric materials compatible with LTCC technology is crucial. r High Q×f, near-zero τ fNovel microwave dielectric ceramic materials are a key path to meet the requirements of 5G / 6G high-frequency communication technologies, and have important theoretical value and engineering application significance. Summary of the Invention

[0006] The purpose of this invention is to provide a pyrophosphate microwave dielectric ceramic material for LTCC and its preparation method, which can meet the requirements of low ε r High Q×f, near-zero τ f The technical requirements are compatible with LTCC technology.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a pyrophosphate microwave dielectric ceramic material for LTCC, wherein the main crystal phase of the ceramic material is (Ca,Sr,Zn,Cu)2P2O7, and the reactant raw materials of the ceramic material include two main materials. The first main material is a mixture of one or more of calcium oxyacid salts, strontium oxyacid salts, zinc oxide and copper oxide, and the second main material is pyrophosphate. The mass ratio of the first main material and the second main material is (45~60):(35~45).

[0008] Preferably, the first main material is a mixture of one or more of CaCO3, SrCO3, ZnO and CuO.

[0009] Preferably, the main crystalline phase of the second main material after calcination is P2O5.

[0010] Preferably, the ceramic material has a dielectric constant of 7.1 to 9.2 at 10 to 13 GHz, a quality factor Q×f of 26800 to 86100 GHz, and a temperature coefficient τ of resonant frequency. f The concentration ranges from -71.4 to 18.6 ppm / ℃.

[0011] Preferably, the porosity of the ceramic material is less than 5.0%.

[0012] The above-mentioned method for preparing pyrophosphate microwave dielectric ceramic materials for LTCC includes the following steps: Step 1: Weigh 45-60 parts of the first main material and 35-45 parts of the second main material according to the mass fraction, add them to the ball mill, use anhydrous ethanol as the grinding medium, and perform ball milling and mixing once for no less than 8 hours. Step 2: Add the slurry obtained after one ball milling to the drying oven for one drying. Step 3: Place the mixture obtained after the first drying into a muffle furnace at 700℃~850℃ for a first calcination. The heating rate is controlled at 5℃ / min~10℃ / min, and the holding time is not less than 3 hours. Step 4: Add the powder obtained after the first calcination and 0-10 parts of the regulator into a ball mill, and use deionized water as the grinding medium to perform a second ball milling for no less than 8 hours. Step 5: Add the mixed slurry obtained after the second ball milling to the drying oven for secondary drying; Step 6: The mixture obtained after secondary drying is sieved and granulated using a 60-100 mesh standard sieve, and then pressed into a cylindrical blank under a pressure of not less than 150 MPa. Next, it is subjected to cold isostatic pressing under a pressure of not less than 200 MPa to obtain a ceramic green body. Step 7: Sinter the ceramic blank at 850℃~950℃ for 2 hours to obtain the microwave dielectric ceramic material.

[0013] Preferably, before ball milling, the calcium oxyacid salt and strontium oxyacid salt in the first main material are dried in a 100°C drying oven, and the zinc oxide and copper oxide in the first main material are pre-calcined in a 900°C muffle furnace to remove moisture and impurities.

[0014] Preferably, the first drying is carried out in a 90℃ drying oven, and the second drying is carried out in a 120℃ drying oven, with a time of not less than 6 hours.

[0015] Preferably, the regulator is a mixture of one or more of TiO2, CuO, and H3BO3.

[0016] Preferably, in step seven, the temperature is first raised to 550°C to 650°C at a heating rate of 3°C / min to 5°C / min and held for 2 hours, and then the temperature is raised to a sintering temperature of 850°C to 950°C at a heating rate of 3°C / min to 8°C / min.

[0017] According to the above technical solution, the beneficial effects of the present invention are: This invention selects calcium oxyacid salts, strontium oxyacid salts, zinc oxide, and copper oxide as the first main material, and pyrophosphate as the second main material. It leverages the advantages of high entropy effect in stabilizing phase composition and synergistically adjusting microwave dielectric properties and sintering performance. The first main material provides multiple equivalent cations, and the second main material provides phosphate ions. A regulator is used to synergistically improve temperature stability. The resulting (Ca,Sr,Zn,Cu)₂P₂O₇ microwave dielectric ceramic material has a dielectric constant ε₀. r Low (7.1~9.2), high quality factor Q×f (26800~86100GHz), high temperature coefficient of resonant frequency τ f With its near-zero adjustable dielectric constant (-71.4~18.6ppm / ℃), pyrophosphate microwave dielectric ceramics exhibit significant advantages in dielectric loss and sintering compatibility, enabling them to meet low ε... r High Q×f, near-zero τ fThe technical requirements are better suited to the needs of high-frequency communication, LTCC (low-temperature co-fired ceramics) and other scenarios.

[0018] This invention maintains the ratio of the first / second main materials at 45~60:35~45. Under this ratio, the ceramic material can maintain a single-phase (Ca,Sr,Zn,Cu)₂P₂O₇. Experiments have verified that if the material ratio is lower or higher than this range, Sr₂P₂O₇ or Zn₂P₂O₇ impurities may be generated during crystal phase production, adversely affecting the microwave dielectric properties of the material. Therefore, this invention adjusts the main crystal phase of the material by rationally controlling the ratio of the first / second main materials and the modifier, ensuring that a pyrophosphate microwave dielectric ceramic with the main crystal phase of (Ca,Sr,Zn,Cu)₂P₂O₇ is obtained. Attached Figure Description

[0019] Figure 1 The phase composition of (Ca,Sr,Zn,Cu)2P2O7 powder and (Ca,Sr,Zn,Cu)2P2O7 ceramic material; Figure 2 The bulk density and relative density of (Ca,Sr,Zn,Cu)2P2O7 ceramic material; Figure 3 The relative permittivity of (Ca,Sr,Zn,Cu)2P2O7 ceramic material; Figure 4 The quality factor of (Ca,Sr,Zn,Cu)2P2O7 ceramic material; Figure 5 The resonant frequency temperature coefficient of (Ca,Sr,Zn,Cu)2P2O7 ceramic material. Detailed Implementation

[0020] This invention provides a pyrophosphate microwave dielectric ceramic material for LTCC. The main crystalline phase of the ceramic material is (Ca,Sr,Zn,Cu)2P2O7. The reactant raw materials of the ceramic material include two main materials, and the mass ratio of the first main material to the second main material is (45~60):(35~45).

[0021] The primary raw material is a mixture of one or more of calcium oxyacid salts, strontium oxyacid salts, zinc oxide, and copper oxide. Specifically, it can be a mixture of one or more of CaCO3, SrCO3, ZnO, and CuO, or other raw materials that are decomposed by heating to produce zinc oxide or copper oxide.

[0022] The second main ingredient is pyrophosphate, and the main crystalline phase after calcination is P2O5.

[0023] The following five examples illustrate the preparation method of the pyrophosphate microwave dielectric ceramic material for LTCC. The (Ca,Sr,Zn,Cu)₂P₂O₇ ceramic material prepared by this method has a dielectric constant of 7.1–9.2 at 10–13 GHz, a quality factor Q×f of 26800–86100 GHz, and a resonant frequency temperature coefficient τ. f The concentration ranges from -71.4 to 18.6 ppm / ℃, and the porosity is less than 5.0%.

[0024] This method leverages the advantages of high entropy effect in stabilizing phase composition, synergistically adjusting microwave dielectric properties and sintering performance. It utilizes the first main material to provide multiple equivalent cations, the second main material to provide phosphate, and a regulator to synergistically improve temperature stability (the regulator is a mixture of one or more of TiO2, CuO, and H3BO3).

[0025] Example 1: A method for preparing pyrophosphate microwave dielectric ceramic material for LTCC, comprising the following steps: Step 1: Weigh out 56 parts of the first main ingredient and 44 parts of the second main ingredient according to the mass fraction.

[0026] The calcium oxyacid salts and strontium oxyacid salts in the first main material are dried in a 100°C drying oven, and the zinc oxide and copper oxide in the first main material are pre-calcined in a 900°C muffle furnace to remove moisture and impurities.

[0027] Then, the first and second main materials are added together into a ball mill, and anhydrous ethanol is used as the grinding medium for one ball milling and mixing, which takes 8 hours.

[0028] Step 2: Add the mixture slurry obtained after one ball milling to a 90℃ drying oven for drying for 6 hours.

[0029] Step 3: Place the mixture obtained after the first drying into an 800℃ muffle furnace for calcination. The heating rate is controlled at 8℃ / min, and the holding time is 3 hours.

[0030] Step 4: Add the powder obtained after the first calcination and 0 parts of the regulator into a ball mill, and use deionized water as the grinding medium for a second ball milling for 8 hours.

[0031] Step 5: Add the mixed slurry obtained after the second ball milling to a 120℃ drying oven for a second drying time of 6 hours.

[0032] Step 6: The mixture obtained after secondary drying is sieved and granulated using a 60-100 mesh standard sieve, and then pressed into a cylindrical blank with a diameter of 12 mm under a pressure of 150 MPa. Next, it is subjected to cold isostatic pressing under a pressure of 200 MPa for 40 seconds to obtain a ceramic green body.

[0033] Step 7: Sinter the ceramic blank at 850°C for 2 hours to obtain the microwave dielectric ceramic material.

[0034] The sintering process is temperature controlled. First, the temperature is raised to 600℃ at a heating rate of 5℃ / min and held for 2 hours. Then, the temperature is raised to 850℃ at a heating rate of 8℃ / min.

[0035] Step 8: Polish the sintered (Ca,Sr,Zn,Cu)2P2O7 ceramic sample for subsequent testing.

[0036] Example 2: A method for preparing pyrophosphate microwave dielectric ceramic material for LTCC, comprising the following steps: Step 1: Weigh out 45 parts of the first main ingredient and 45 parts of the second main ingredient according to the weight proportions.

[0037] The calcium oxyacid salts and strontium oxyacid salts in the first main material are dried in a 100°C drying oven, and the zinc oxide and copper oxide in the first main material are pre-calcined in a 900°C muffle furnace to remove moisture and impurities.

[0038] Then, the first and second main materials are added together into a ball mill, and anhydrous ethanol is used as the grinding medium for one ball milling and mixing, which takes 8 hours.

[0039] Step 2: Add the mixture slurry obtained after one ball milling to a 90℃ drying oven for drying for 6 hours.

[0040] Step 3: Place the mixture obtained after the first drying into a muffle furnace at 700℃ for calcination. The heating rate is controlled at 5℃ / min, and the holding time is 3 hours.

[0041] Step 4: Add the powder obtained after the first calcination and 10 parts of the regulator into a ball mill, and use deionized water as the grinding medium for a second ball milling for 8 hours.

[0042] Step 5: Add the mixed slurry obtained after the second ball milling to a 120℃ drying oven for a second drying time of 6 hours.

[0043] Step 6: The mixture obtained after secondary drying is sieved and granulated using a 60-100 mesh standard sieve, and then pressed into a cylindrical blank with a diameter of 12 mm under a pressure of 150 MPa. Next, it is subjected to cold isostatic pressing under a pressure of 200 MPa for 40 seconds to obtain a ceramic green body.

[0044] Step 7: Sinter the ceramic blank at 950°C for 2 hours to obtain the microwave dielectric ceramic material.

[0045] The sintering process is temperature controlled. First, the temperature is raised to 650℃ at a heating rate of 3℃ / min and held for 2 hours. Then, the temperature is raised to 950℃ at a heating rate of 3℃ / min.

[0046] Step 8: Polish the sintered (Ca,Sr,Zn,Cu)2P2O7 ceramic sample for subsequent testing.

[0047] Example 3: A method for preparing pyrophosphate microwave dielectric ceramic material for LTCC, comprising the following steps: Step 1: Weigh out 60 parts of the first main ingredient and 38 parts of the second main ingredient according to the weight proportions.

[0048] The calcium oxyacid salts and strontium oxyacid salts in the first main material are dried in a 100°C drying oven, and the zinc oxide and copper oxide in the first main material are pre-calcined in a 900°C muffle furnace to remove moisture and impurities.

[0049] Then, the first and second main materials are added together into a ball mill, and anhydrous ethanol is used as the grinding medium for one ball milling and mixing, which takes 8 hours.

[0050] Step 2: Add the mixture slurry obtained after one ball milling to a 90℃ drying oven for drying for 6 hours.

[0051] Step 3: Place the mixture obtained after the first drying into a muffle furnace at 850℃ for calcination. The heating rate is controlled at 10℃ / min, and the holding time is 3 hours.

[0052] Step 4: Add the powder obtained after the first calcination and 2 parts of the regulator into a ball mill, and use deionized water as the grinding medium for a second ball milling for 8 hours.

[0053] Step 5: Add the mixed slurry obtained after the second ball milling to a 120℃ drying oven for a second drying time of 6 hours.

[0054] Step 6: The mixture obtained after secondary drying is sieved and granulated using a 60-100 mesh standard sieve, and then pressed into a cylindrical blank with a diameter of 12 mm under a pressure of 150 MPa. Next, it is subjected to cold isostatic pressing under a pressure of 200 MPa for 40 seconds to obtain a ceramic green body.

[0055] Step 7: Sinter the ceramic blank at 900℃ for 2 hours to obtain the microwave dielectric ceramic material.

[0056] The sintering process is temperature controlled. First, the temperature is raised to 550℃ at a heating rate of 4℃ / min and held for 2 hours. Then, the temperature is raised to 900℃ at a heating rate of 5℃ / min.

[0057] Step 8: Polish the sintered (Ca,Sr,Zn,Cu)2P2O7 ceramic sample for subsequent testing.

[0058] Example 4: A method for preparing pyrophosphate microwave dielectric ceramic material for LTCC, comprising the following steps: Step 1: Weigh out 59 parts of the first main ingredient and 37 parts of the second main ingredient according to the mass fraction.

[0059] The calcium oxyacid salts and strontium oxyacid salts in the first main material are dried in a 100°C drying oven, and the zinc oxide and copper oxide in the first main material are pre-calcined in a 900°C muffle furnace to remove moisture and impurities.

[0060] Then, the first and second main materials are added together into a ball mill, and anhydrous ethanol is used as the grinding medium for one ball milling and mixing, which takes 8 hours.

[0061] Step 2: Add the mixture slurry obtained after one ball milling to a 90℃ drying oven for drying for 6 hours.

[0062] Step 3: Place the mixture obtained after the first drying into a muffle furnace at 825℃ for calcination. The heating rate is controlled at 6℃ / min, and the holding time is 3 hours.

[0063] Step 4: Add the powder obtained after the first calcination and 4 parts of the regulator into a ball mill, and use deionized water as the grinding medium for a second ball milling for 8 hours.

[0064] Step 5: Add the mixed slurry obtained after the second ball milling to a 120℃ drying oven for a second drying time of 6 hours.

[0065] Step 6: The mixture obtained after secondary drying is sieved and granulated using a 60-100 mesh standard sieve, and then pressed into a cylindrical blank with a diameter of 12 mm under a pressure of 150 MPa. Next, it is subjected to cold isostatic pressing under a pressure of 200 MPa for 40 seconds to obtain a ceramic green body.

[0066] Step 7: Sinter the ceramic blank at 925℃ for 2 hours to obtain the microwave dielectric ceramic material.

[0067] The sintering process is temperature controlled. First, the temperature is raised to 650℃ at a heating rate of 3℃ / min and held for 2 hours. Then, the temperature is raised to 925℃ at a heating rate of 3℃ / min.

[0068] Step 8: Polish the sintered (Ca,Sr,Zn,Cu)2P2O7 ceramic sample for subsequent testing.

[0069] Example 5: A method for preparing pyrophosphate microwave dielectric ceramic material for LTCC, comprising the following steps: Step 1: Weigh out 59 parts of the first main ingredient and 35 parts of the second main ingredient according to the mass fraction.

[0070] The calcium oxyacid salts and strontium oxyacid salts in the first main material are dried in a 100°C drying oven, and the zinc oxide and copper oxide in the first main material are pre-calcined in a 900°C muffle furnace to remove moisture and impurities.

[0071] Then, the first and second main materials are added together into a ball mill, and anhydrous ethanol is used as the grinding medium for one ball milling and mixing, which takes 8 hours.

[0072] Step 2: Add the mixture slurry obtained after one ball milling to a 90℃ drying oven for drying for 6 hours.

[0073] Step 3: Place the mixture obtained after the first drying into an 800℃ muffle furnace for calcination. The heating rate is controlled at 5℃ / min, and the holding time is 3 hours.

[0074] Step 4: Add the powder obtained after the first calcination and 6 parts of the regulator into a ball mill, and use deionized water as the grinding medium for a second ball milling for 8 hours.

[0075] Step 5: Add the mixed slurry obtained after the second ball milling to a 120℃ drying oven for a second drying time of 6 hours.

[0076] Step 6: The mixture obtained after secondary drying is sieved and granulated using a 60-100 mesh standard sieve, and then pressed into a cylindrical blank with a diameter of 12 mm under a pressure of 150 MPa. Next, it is subjected to cold isostatic pressing under a pressure of 200 MPa for 40 seconds to obtain a ceramic green body.

[0077] Step 7: Sinter the ceramic blank at 950°C for 2 hours to obtain the microwave dielectric ceramic material.

[0078] Temperature control is implemented during the sintering process. First, the temperature is raised to 600℃ at a heating rate of 5℃ / min and held for 2 hours. Then, the temperature is raised to 950℃ at a heating rate of 8℃ / min.

[0079] Step 8: Polish the sintered (Ca,Sr,Zn,Cu)2P2O7 ceramic sample for subsequent testing.

[0080] The microwave dielectric ceramic materials prepared in Examples 1-5 were tested, and the test results are as follows: Figure 1-5 As shown, Figure 1The phase composition of (Ca,Sr,Zn,Cu)2P2O7 powder and (Ca,Sr,Zn,Cu)2P2O7 ceramic material is shown. It can be seen that the (Ca,Sr,Zn,Cu)2P2O7 powder calcined at 800℃ has a single-phase structure. After sintering at 825~900℃, the phase composition of the sample does not change and still maintains a single-phase structure.

[0081] The microwave dielectric properties of the samples obtained in each embodiment are shown in Table 1. It can be seen that the (Ca,Sr,Zn,Cu)2P2O7 ceramic prepared by this invention has excellent properties and is a promising microwave dielectric material.

[0082] Table 1. Microwave dielectric properties of the samples obtained in the examples Combining Table 1 and Figure 2-5 , Figure 2 The volume density and relative density of (Ca,Sr,Zn,Cu)2P2O7 ceramics prepared at different sintering temperatures are shown. It can be seen that the ceramic material has the highest density under the sintering condition of 850℃. Figure 3 , 4 5 represents (Ca) prepared under different sintering conditions. 0.5 Sr 0.5 Zn 0.5 Cu 0.5 The microwave dielectric properties of P2O7 ceramics, including relative permittivity, quality factor, and temperature coefficient of resonant frequency, show that as the sintering temperature increases, the permittivity and quality factor first increase and then decrease, while the temperature coefficient of resonant frequency first decreases and then gradually increases. The permittivity, quality factor, and temperature coefficient of resonant frequency of (Ca,Sr,Zn,Cu)2P2O7 ceramics prepared by sintering at 850℃ are 7.1, 47400GHz, and -71.4ppm / ℃, respectively.

[0083] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications or equivalent transformations made using the content of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing pyrophosphate microwave dielectric ceramic material for LTCC, characterized in that: The main crystalline phase of the ceramic material is (Ca). 0.5 Sr 0.5 Zn 0.5 Cu 0.5 P2O7, the reactant raw materials of ceramic materials include two main materials. The first main material is a mixture of CaCO3, SrCO3, ZnO and CuO. The second main material is pyrophosphate with P2O5 as the main crystalline phase after calcination. The mass ratio of the first main material to the second main material is (45~60):(35~45). Includes the following steps: Step 1: Weigh 45-60 parts of the first main material and 35-45 parts of the second main material according to the mass fraction, add them to the ball mill, use anhydrous ethanol as the grinding medium, and perform ball milling and mixing once for no less than 8 hours. Step 2: Add the slurry obtained after one ball milling to the drying oven for one drying. Step 3: Place the mixture obtained after the first drying into a muffle furnace at 700℃~850℃ for a first calcination. The heating rate is controlled at 5℃ / min~10℃ / min, and the holding time is not less than 3 hours. Step 4: Add the powder obtained after the first calcination and 0-10 parts of the regulator into a ball mill, and use deionized water as the grinding medium to perform a second ball milling for no less than 8 hours; the regulator is used to synergistically improve temperature stability and is a mixture of one or more of TiO2, CuO, and H3BO3. Step 5: Add the mixed slurry obtained after the second ball milling to the drying oven for secondary drying; Step 6: The mixture obtained after secondary drying is sieved and granulated using a 60-100 mesh standard sieve, and then pressed into a cylindrical blank under a pressure of not less than 150 MPa. Next, it is subjected to cold isostatic pressing under a pressure of not less than 200 MPa to obtain a ceramic green body. Step 7: Sinter the ceramic blank at 850℃~950℃ for 2 hours to obtain the microwave dielectric ceramic material.

2. The preparation method according to claim 1, characterized in that: Before ball milling, CaCO3 and SrCO3 in the first main material are dried in a 100°C drying oven, and ZnO and CuO in the first main material are pre-calcined in a 900°C muffle furnace to remove moisture and impurities.

3. The preparation method according to claim 1, characterized in that: The first drying process uses a 90℃ drying oven, and the second drying process uses a 120℃ drying oven, with a time of no less than 6 hours for each process.

4. The preparation method according to claim 1, characterized in that: Step 7: First, raise the temperature to 550℃~650℃ at a heating rate of 3℃ / min~5℃ / min and hold for 2 hours. Then, raise the temperature to a sintering temperature of 850℃~950℃ at a heating rate of 3℃ / min~8℃ / min.

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