Microwave dielectric ceramic material, preparation method thereof and microwave component

Abstract

The application discloses a microwave dielectric ceramic material and a preparation method and microwave component thereof, and relates to the technical field of microwave dielectric ceramic materials. The raw material of the ceramic material comprises a main crystal phase C2ZS-CS and a Zn-B-Si sintering aid, and the chemical formula of the main crystal phase C2ZS-CS is Ca2ZnSi2O7-CaSiO3. The main crystal phase and the sintering aid are 91-95 parts and 5-9 parts by weight, respectively. The low-temperature sintering microwave dielectric ceramic material with low dielectric constant, 0±15ppm / ℃ volume temperature coefficient and high-frequency low loss is obtained. The ceramic material preparation method is simple, energy-saving, and can use domestic raw materials in the preparation process. The ceramic material is lead-free, cadmium-free and other toxic and harmful substances, green and environment-friendly, and can realize industrialized batch production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic ceramic materials, in particular to a microwave dielectric ceramic material, a preparation method thereof and a microwave component. BACKGROUND

[0002] Microwave dielectric ceramic is a key material for modern mobile communication, satellite communication, cellular base station and military radar resonators, filters, dielectric ceramic substrates, dielectric ceramic capacitors and other microwave components. With the rapid development of the new generation of mobile communication, higher requirements are put forward for signal transmission speed and stability. Compared with traditional materials, high-stability low-dielectric low-loss microwave dielectric ceramic has the advantages of low dielectric loss, high use frequency and highly stable capacitance temperature coefficient, which can meet the development of microwave devices towards high frequency, high speed and high reliability. The capacitance temperature characteristic of 0±15ppm / ℃ is conducive to the high stability of the frequency temperature of the line.

[0003] Microwave dielectric ceramic has been developed since 1939, and various low, medium and high dielectric constant microwave dielectric ceramics have made great progress. The low dielectric constant microwave dielectric ceramic with a dielectric constant εr of about 12 is mainly Al2O3-TiO2 system and MgAl2O4-SrTiO3 system (patent No. CN 114163229 A). When the purity of the raw material required by Al2O3-TiO2 system is lower than 99.99%, it is difficult to prepare microwave dielectric ceramic with low loss at microwave frequency, and the product made of high-purity raw material is relatively high; and the sintering temperature is high, reaching more than 1300℃. The sintering temperature of MgAl2O4-SrTiO3 system is also high, reaching more than 1340℃, which consumes energy.

[0004] At present, the low-temperature sintering microwave dielectric ceramic with low dielectric constant is mainly Ca-B-Si system, but its dielectric constant is generally lower than 10, and the capacitance temperature coefficient is generally more than 30ppm / ℃, which is mainly used for LTCC products, but not suitable for manufacturing MLCC. And in the production of Ca-B-Si system dielectric ceramic, it is usually necessary to melt into glass first, and then water quenching and powder grinding, which is a complicated process and consumes energy. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a microwave dielectric ceramic material, a preparation method thereof, and a microwave component prepared by using the microwave dielectric ceramic material; the present application obtains a low-temperature sintering microwave dielectric ceramic material with low dielectric constant, 0±15ppm / ℃ capacitance temperature coefficient and high frequency low loss. The microwave component such as MLCC (multilayer ceramic capacitor) product prepared by using this dielectric ceramic material has low dielectric loss (dielectric loss-0.9×10 -4 ~0.3×10 -4), the temperature coefficient is stable at 0±15ppm / ℃, the reliability is high, the sintering temperature is low (1000℃-1030℃), the preparation process is simple, and the energy consumption is low. The Q×f value is 40107.8 GHz.

[0006] The first object of the present application is to provide a microwave dielectric ceramic material, the raw materials of which include a main crystal phase C2ZS-CS and a Zn-B-Si sintering aid, and the chemical formula of the main crystal phase C2ZS-CS is Ca2ZnSi2O7-CaSiO3.

[0007] The main crystal phase and the sintering aid are respectively 91-95 parts and 5-9 parts by weight.

[0008] In the embodiment of the present application, Ca2ZnSi2O7-CaSiO3 and the sintering aid Zn-B-Si are used in combination, and the Zn-B-Si sintering block is added to the main crystal phase C2ZS-CS sintering block, so that the ZnB2SiO6 crystal of the low-temperature phase can be synthesized at a lower temperature. During the sintering process, the Zn-B-Si sintering block forms a liquid phase first and fills the gaps between the Ca2ZnSi2O7-CaSiO3 crystal particles, so as to wrap the Ca2ZnSi2O7-CaSiO3 crystal particles and generate capillary pressure, which can promote the rearrangement of the particles to achieve more compact packing, and also can make the small particles dissolve in the liquid phase and condense on the surface of the large particles through liquid phase diffusion, so as to promote the uniform distribution of the crystal particles, accelerate the sintering speed, and realize the reduction of the sintering temperature. At the same time, due to the crystal structure of the Zn-B-Si sintering block itself, the Zn-B-Si sintering block is easy to be mutually dissolved with the main crystal phase particles to form a continuous solid solution, so as to reduce the material dielectric loss and be beneficial to the optimization of the dielectric properties. Moreover, the main crystal phase with the Ca2ZnSi2O7-CaSiO3 structure does not need high-temperature melting and water quenching and powder grinding treatment during the preparation of the dielectric ceramic material, so the process is simple and the energy consumption is low.

[0009] In the present application, barium carbonate or magnesium carbonate or strontium carbonate is used as an additive to adjust the temperature coefficient; metal oxides are used as additives to adjust the insulation performance of the material and improve the reliability of the product; and zinc oxide is used as a main crystal phase structure material, which mainly functions to form Ca2ZnSi2O7 crystals to obtain main crystal phase crystals with excellent dielectric properties. Through reasonable design of the ratio of each raw material in the main crystal phase and the ratio of each raw material in the sintering aid, the embodiment of the present application obtains a material with more excellent dielectric constant, capacity temperature coefficient, dielectric loss and sintering temperature.

[0010] In an optional embodiment, the preparation raw materials of the main crystal phase C2ZS-CS include calcium carbonate, silicon dioxide, zinc oxide, a dopant and metal oxides.

[0011] The dopant includes any one of barium carbonate, magnesium carbonate or strontium carbonate.

[0012] The metal oxide includes two or more of aluminum oxide, titanium dioxide, lanthanum oxide, niobium pentoxide, and bismuth oxide.

[0013] In the embodiment of the present application, when preparing the main crystal phase and pre-sintering the first mixture slurry, the cations in the dopant magnesium carbonate, barium carbonate or strontium carbonate or the cations in the metal oxide MO enter the main crystal lattice and replace Ca 2+ , Zn 2+ , Si 4+ , causing lattice distortion and reducing the synthesis temperature of the C2ZS-CS main crystal phase. In addition to the reduction of the sintering temperature, the addition of the dopant such as barium carbonate can adjust the temperature coefficient, so that the comprehensive dielectric properties of the C2ZS-CS microwave dielectric ceramic material are improved, and the performance is more stable. The material can be used to manufacture microwave components such as resonators, filters, dielectric ceramic substrates, antennas, and multilayer ceramic capacitors.

[0014] The metal oxide (including two or more of aluminum oxide, titanium dioxide, lanthanum oxide, niobium pentoxide, and bismuth oxide) is used as an additive to adjust the dielectric properties of the material, including the insulation properties. The titanium ions in the titanium dioxide enter the main crystal lattice to form a high-dielectric titanate, which can improve the dielectric constant of the main crystal phase. The aluminum oxide itself is a high-insulation material, and when it is solid-solved in the material system, the insulation strength of the material can be improved. In addition, because there is a large amount of silicon dioxide in the main crystal phase formula, the silicon dioxide will undergo a crystal type transformation at high temperatures, causing the internal structure of the ceramic body to relax and thus reducing the insulation properties. The introduction of aluminum oxide can form sillimanite (Al2O3.SiO2) with free silicon dioxide to prevent the crystal type transformation in the crystal and ensure the insulation of the material.

[0015] In an optional embodiment, the molar ratio of calcium carbonate, silicon dioxide, zinc oxide, dopant, and metal oxide in the raw material of the main crystal phase is (37-42):(38-45):(8-12):(4.9-8.4):(6.1-8.2).

[0016] In the embodiment of the present application, the proportion of zinc oxide in the raw material for preparing the main crystal phase is large, which is to form Ca2ZnSi2O7-CaSiO3 crystals to obtain a main crystal phase crystal with excellent dielectric properties.

[0017] In an optional embodiment, the purity of the zinc oxide is greater than 99%, which avoids the introduction of other impurities and ensures the dielectric properties of the material.

[0018] In an optional embodiment, the raw material of the sintering aid includes zinc oxide, boric acid, and silicon dioxide, and the molar ratio of zinc oxide, boric acid, and silicon dioxide is (26-33):(45-52):(17-21).

[0019] The second object of the present application is to provide a preparation method of the microwave dielectric ceramic material, comprising the following steps:

[0020] Preparation of the main crystal phase powder: according to the formula, calcium carbonate, silicon dioxide, zinc oxide, dopant, and metal oxide are mixed to obtain a first mixture, the obtained first mixture is ground and mixed with water to obtain a first mixture slurry, and the first mixture slurry is dried, sieved, and pre-fired to obtain C2ZS-CS fired blocks, which are crushed for use;

[0021] Preparation of Zn-B-Si sintering aid: according to the formula, zinc oxide, boric acid, and silicon dioxide are mixed to obtain a second mixture, the second mixture is ground and mixed with ethanol to obtain a second mixture slurry, and the second mixture slurry is dried and pre-synthesized to obtain Zn-B-Si fired blocks;

[0022] According to the formula, the C2ZS-CS powder and the Zn-B-Si fired blocks are ground and mixed with water, sieved to obtain a third mixture slurry, and the third mixture slurry is dried, sieved, pressed, and sintered to obtain the microwave dielectric ceramic material.

[0023] In the embodiment of the present application, the main crystal phase and the sintering aid are synthesized by a solid phase method, the Zn-B-Si fired blocks are added in the Ca2ZnSi2O7-CaSiO3 microwave dielectric ceramic material fired blocks, and then the C2ZS-CS microwave dielectric ceramic material is prepared by grinding and sintering. The preparation process is simple, does not need high-temperature melting and water quenching and powder grinding, saves energy, can use domestic raw materials in the preparation process, is free of toxic and harmful substances such as lead and cadmium, is green and environmentally friendly, and can realize industrialized mass production.

[0024] In an optional embodiment, when the first mixture is ground and mixed with water, zirconia balls are used as the grinding medium, the weight ratio of the mixture to the balls to water is 1:5-6:1.5-3, the grinding and mixing is performed for 5-8 hours, the first mixture slurry is dried at 140°C and sieved through a 40-mesh sieve, and the pre-firing is performed at 1120-1160°C for 3-5 hours to obtain the C2ZS-CS fired blocks. (The pre-firing temperature of 1120-1160°C can well synthesize the C2ZS-CS main crystal phase structure.

[0025] In an optional embodiment, when the second mixture is ground and mixed with ethanol, zirconia balls are used as the grinding medium, the weight ratio of the mixture to the balls to ethanol is 1:5-6:1.0-2, the grinding and mixing is performed for 5-8 hours, and the second mixture slurry is dried and pre-synthesized at 650-730°C for 3h to obtain the Zn-B-Si fired blocks. (The pre-synthesis temperature of 650-730°C is conducive to the synthesis of the low-temperature phase ZnB2SiO6 crystal.

[0026] The C2ZS-CS powder, Zn-B-Si briquettes and water are mixed by grinding with zirconia balls as grinding medium, the weight ratio of material:ball:water is 1:5-6:1.5-2.5, the grinding and mixing is carried out for 15-45 hours, the third mixture slurry is dried at 140℃ and sieved through 80 mesh screen, the obtained dry powder is added with 8-12% paraffin wax and then pressed into round green blanks, the green blanks are sintered at 1000-1030℃ for 2-3 hours to obtain the dielectric ceramic material.

[0027] A third object of the present application is to provide a microwave component, which is prepared by using the microwave dielectric ceramic material according to any one of the above or prepared by using the dielectric ceramic material prepared by using the preparation method according to any one of the above, and the microwave component includes any one of resonator, filter, dielectric ceramic substrate, antenna, multilayer ceramic capacitor.

[0028] A fourth object of the present application is to provide a multilayer ceramic capacitor, which is prepared by using the microwave dielectric ceramic material according to any one of the above or prepared by using the dielectric ceramic material prepared by using the preparation method according to any one of the above;

[0029] The preparation method is as follows:

[0030] The dielectric ceramic powder, ball milling medium and solvent are dispersed and ball milled, then the adhesive is added, and the ceramic slurry is prepared after ball milling;

[0031] The ceramic slurry is made into a film strip, the film strip is printed with internal electrode slurry and dried and shaped;

[0032] The film strip printed with internal electrode and the blank film strip are laminated according to the design of the shape size of the chip type and the number of internal electrode layers not less than 2, to prepare a green blank bar;

[0033] The green blank bar is pressurized by a warm isostatic press, the temperature is 50-100℃, the pressure is 5000-8000MPa, and the pressure maintaining time is 20-50min, the green blank bar is cut on a cutting machine to form a capacitor green body;

[0034] The temperature is raised to 450-600℃ at a temperature raising rate of 0.5-3℃ / min, the adhesive is discharged, then the temperature is raised to 1000-1030℃ at a temperature raising rate of 1-4℃ / min for sintering, and the temperature is lowered with the furnace after heat preservation for 3-4 hours.

[0035] The multilayer ceramic capacitor (MLCC product) obtained by the embodiment of the present application has low sintering temperature (1000-1030℃) and low energy consumption, and has excellent performance (dielectric loss is -0.9×10 -4 -0.3×10 -4 , temperature coefficient is stable at 0±15ppm / ℃) and high reliability.

[0036] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0037] (1) The microwave dielectric ceramic material provided by the embodiment of the present application adds Zn-B-Si sintering block which can assist sintering to the main crystal phase C2ZS-CS sintering block, the Zn-B-Si sintering block will undergo phase transition at a lower temperature, and with the increase of temperature, the Zn-B-Si sintering block will first generate viscous liquid phase and begin to wet and coat the powder particles. During the sintering process, the Zn-B-Si sintering block Zn 2+ At the same time, the two O 2- are connected, the glass structure network is continuous, and the sintering temperature is reduced; at the same time, Zn 2+ enters the main crystal lattice and replaces Ca 2+ , Ba 2+ and other A cations, causing lattice distortion, and Zn2+ can bring the Zn-B-Si glass system into the lattice, further causing temperature reduction. At this time, part of the Zn-B-Si glass system is brought into the main crystal lattice and fills between the main crystal particles, which can promote the uniform distribution of crystal grains, accelerate the sintering speed, and realize the reduction of sintering temperature; and the other part of the Zn-B-Si glass system is wrapped in the main crystal lattice, thereby further reducing the temperature.

[0038] The main crystal phase with Ca2ZnSi2O7-CaSiO3 structure does not need high-temperature melting and water quenching and powder grinding during the preparation of the dielectric ceramic material, the process is simple, and the energy consumption is low.

[0039] (2) The dielectric ceramic material obtained by the embodiment of the present application has low dielectric constant, the dielectric constant (1 MHz) is about 12, low dielectric loss (1 MHz) is (1.0-1.7) x 10 -4 , the capacity temperature coefficient is stable at 0±15 ppm / ℃, and the Qxf value is 40107.8 GHz.

[0040] (3) The preparation method of the dielectric ceramic material of the embodiment of the present application adds Zn-B-Si sintering block to the Ca2ZnSi2O7-CaSiO3 microwave dielectric ceramic material sintering block, and then grinds and sintering to obtain C2ZS-CS microwave dielectric ceramic material. The preparation method is simple, does not need high-temperature melting, saves energy, uses domestic raw materials in the preparation process, is lead-free and cadmium-free, green and environmentally friendly, and can realize industrialized batch production.

[0041] The energy consumption is low during the manufacturing process of the dielectric ceramic material: the main crystal phase pre-sintering temperature is low, 1120-1160℃; the temperature of the temperature-reducing agent Zn-B-Si is low, 650-730℃, the material sintering temperature is low, 1000℃-1030℃.

[0042] (4) The MLCC product obtained by the embodiment has low sintering temperature (1000-1030 DEG C), low energy consumption, excellent performance and high reliability:

[0043] Dielectric loss-0.9-0.3*10 -4 The communication device has very small energy loss and almost no energy loss, and high signal transmission quality.

[0044] The temperature coefficient is stable at 0±15ppm / ℃, the breakdown voltage reaches 4.1kv, which is much higher than the rated voltage 500v, the capacity is 100pF, and the electrode paste of 15%Pd85%Ag can be matched. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope, and other related drawings can also be obtained by those skilled in the art without creative labor. In the drawings:

[0046] Figure 1 The XRD diagram of C2ZS-CS obtained at different pre-sintering temperatures (1005 DEG C, 1015 DEG C, 1030 DEG C).

[0047] Figure 2 The electrode diagram of the 1111-500V-101 type capacitor product. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present application more clear and obvious, the present application will be further described in detail below in combination with embodiments, and the exemplary embodiments of the present application and their descriptions are only used to explain the present application, and not as a limitation on the present application.

[0049] The embodiment of the present application provides a microwave dielectric ceramic material, and raw materials include main crystal phase C2ZS-CS and Zn-B-Si sintering aid, the chemical formula of the main crystal phase C2ZS-CS is Ca2ZnSi2O7-CaSiO3.

[0050] The main crystal phase and the sintering aid are 91-95 parts and 5-9 parts by weight, respectively.

[0051] Further, the preparation raw materials of the main crystal phase C2ZS-CS include calcium carbonate, silicon dioxide, zinc oxide, dopant and metal oxide.

[0052] The dopant includes any one or several of magnesium carbonate, barium carbonate or strontium carbonate.

[0053] The metal oxide includes two or more of aluminum oxide, titanium dioxide, lanthanum oxide, niobium pentoxide, and bismuth oxide.

[0054] Further, the molar ratio of calcium carbonate, silicon dioxide, zinc oxide, dopant, and metal oxide in the raw material of the main crystal phase is (37-42):(38-45):(8-12):(4.9-8.4):(6.1-8.2).

[0055] Further, the purity of the zinc oxide is greater than 99%.

[0056] Further, the raw material of the sintering aid includes zinc oxide, boric acid, and silicon dioxide, and the molar ratio of zinc oxide, boric acid, and silicon dioxide is (26-33):(45-52):(17-21).

[0057] The embodiment of the present application also provides a preparation method of the microwave dielectric ceramic material, including the following steps:

[0058] Preparation of the main crystal phase powder: according to the formula, calcium carbonate, silicon dioxide, zinc oxide, dopant, and metal oxide are mixed to obtain a first mixture, the obtained first mixture is ground and mixed with water to obtain a first mixture slurry, and the first mixture slurry is dried, sieved, and pre-fired to obtain C2ZS-CS fired blocks, which are crushed for use;

[0059] Preparation of the Zn-B-Si sintering aid: according to the formula, zinc oxide, boric acid, and silicon dioxide are mixed to obtain a second mixture, the second mixture is ground and mixed with ethanol to obtain a second mixture slurry, and the second mixture slurry is dried and pre-synthesized to obtain Zn-B-Si fired blocks;

[0060] According to the formula, the C2ZS-CS powder and the Zn-B-Si fired blocks are ground and mixed with water, sieved to obtain a third mixture slurry, and the third mixture slurry is dried, sieved, pressed, and sintered to obtain the microwave dielectric ceramic material.

[0061] Specifically, the first mixture is ground and mixed with water using zirconium dioxide balls as the grinding medium, and the weight ratio of the material:ball:water is 1:5-6:1.5-3 for grinding and mixing for 5-8 hours, the first mixture slurry is dried at 140℃ and sieved through a 40-mesh sieve, and pre-firing is performed at 1120-1160℃ for 3-5 hours to obtain C2ZS-CS fired blocks. The C2ZS-CS obtained at different pre-firing temperatures (1005℃, 1015℃, and 1030℃) is subjected to XRD testing, and the results are shown in Table 1. Figure 1

[0062] ​Specifically, the second mixture is mixed with ethanol as grinding medium, and zirconium dioxide balls are used as the grinding medium, and the weight ratio of the mixture:ball:ethanol is 1:5-6:1.0-2, and the mixture is ground for 5-8 hours. After the second mixed slurry is dried, it is pre-synthesized at 650-730°C for 3 hours to obtain the Zn-B-Si block.

[0063] The C2ZS-CS powder, the Zn-B-Si block and water are mixed as grinding medium, and zirconium dioxide balls are used as the grinding medium, and the weight ratio of the mixture:ball:water is 1:5-6:1.5-2.5, and the mixture is ground for 15-45 hours. The third mixed slurry is dried at 140°C and sieved through an 80-mesh sieve. The obtained dry powder is added with 8-12% of paraffin, and then pressed into a round green body. The green body is sintered at 1000-1030°C for 2-3 hours to obtain the dielectric ceramic material.

[0064] The ceramic material has low dielectric constant, stable capacity temperature coefficient of 0±15ppm / ℃ and low high-frequency loss.

[0065] The following is described in detail through specific examples.

[0066] 1. Preparation example of main crystal phase C2ZS-CS block (defined as C1, C2, C3 and C4 respectively)

[0067] Example C1:

[0068] 37.23% of calcium carbonate, 8.1% of zinc oxide, 41.22% of silicon dioxide, 6.16% of barium carbonate, magnesium carbonate or strontium carbonate, and 7.29% of one or more MOs are proportioned according to the ratio. The purity of the zinc oxide is more than 99%, and the calcium carbonate and the silicon dioxide are analytically pure. The obtained mixture is ground with zirconium dioxide balls as the grinding medium and water as the solvent, and the weight ratio of the mixture:ball:water is 1:5-6:1.5-3. The mixture is ground for 5-8 hours to obtain a uniformly mixed mixture slurry. The slurry is dried at 140°C and sieved through a 40-mesh sieve. The C2ZS-CS block is obtained by pre-sintering at 1120-1160°C for 3-5 hours, and is crushed for use.

[0069] Example C2:

[0070] The mixture of 38.14% calcium carbonate, 8.67% zinc oxide, 40.19% silicon dioxide, 5.77% barium carbonate or magnesium carbonate or strontium carbonate, 7.23% MO(s) in molar percentage is proportioned, wherein the purity of zinc oxide is above 99%, and the purity of calcium carbonate and silicon dioxide is analytical, the obtained mixture is ground and mixed for 5-8 hours with zirconium dioxide ball as grinding medium and water as solvent, and the weight ratio of material: ball: water is 1:5-6: 1.5-3, to obtain a slurry of uniformly mixed mixture, which is dried at 140°C and passed through a 40-mesh sieve, and pre-sintered at 1120-1160°C for 3-5 hours to obtain C2ZS-CS sintered block, which is crushed for use.

[0071] Example C3:

[0072] The mixture of 39.23% calcium carbonate, 8.34% zinc oxide, 41.17% silicon dioxide, 5.66% barium carbonate or magnesium carbonate or strontium carbonate, 5.6% MO(s) in molar percentage is proportioned, wherein the purity of zinc oxide is above 99%, and the purity of calcium carbonate and silicon dioxide is analytical, the obtained mixture is ground and mixed for 5-8 hours with zirconium dioxide ball as grinding medium and water as solvent, and the weight ratio of material: ball: water is 1:5-6: 1.5-3, to obtain a slurry of uniformly mixed mixture, which is dried at 140°C and passed through a 40-mesh sieve, and pre-sintered at 1120-1160°C for 3-5 hours to obtain C2ZS-CS sintered block, which is crushed for use.

[0073] Example C4:

[0074] The mixture of 41.46% calcium carbonate, 8.06% zinc oxide, 38.79% silicon dioxide, 4.97% barium carbonate or magnesium carbonate or strontium carbonate, 6.72% MO(s) in molar percentage is proportioned, wherein the purity of zinc oxide is above 99%, and the purity of calcium carbonate and silicon dioxide is analytical, the obtained mixture is ground and mixed for 5-8 hours with zirconium dioxide ball as grinding medium and water as solvent, and the weight ratio of material: ball: water is 1:5-6: 1.5-3, to obtain a slurry of uniformly mixed mixture, which is dried at 140°C and passed through a 40-mesh sieve, and pre-sintered at 1120-1160°C for 3-5 hours to obtain C2ZS-CS sintered block, which is crushed for use.

[0075] The formula and sintering temperature of the main crystal phase C2ZS-CS sintered block of each preparation example are shown in Table 1, and the numerical values in the table are in molar percentage.

[0076] Table 1

[0077]

[0078] 2, Zn-B-Si sintered block preparation example (defined as G1, G2 respectively)

[0079] Example G1:

[0080] The mixture of 29.7% zinc oxide, 49.5% boric acid and 20.8% silicon dioxide in mole percentage, wherein the purity of zinc oxide is above 99%, and the boric acid and silicon dioxide are analytically pure, is mixed with zirconium dioxide balls as grinding medium and anhydrous ethanol as solvent, and the weight ratio of the mixture: balls: anhydrous ethanol is 1:5-6: 1.0-2. The mixture is ground and mixed for 5-8 hours, dried, and pre-synthesized at 680°C for 3 hours to obtain the Zn-B-Si block.

[0081] Example G2:

[0082] The mixture of 32.7% zinc oxide, 46.9% boric acid and 20.4% silicon dioxide in mole percentage, wherein the purity of zinc oxide is above 99%, and the boric acid and silicon dioxide are analytically pure, is mixed with zirconium dioxide balls as grinding medium and anhydrous ethanol as solvent, and the weight ratio of the mixture: balls: anhydrous ethanol is 1:5-6: 1.0-2. The mixture is ground and mixed for 5-8 hours, dried, and pre-synthesized at 650-730°C for 3 hours to obtain the Zn-B-Si block.

[0083] The formula and pre-synthesis temperature of the Zn-B-Si block of each preparation example are shown in Table 2, and the numerical values in the table are in mole percentage.

[0084] Table 2

[0085] Reference Zinc oxide Boric acid Silicon dioxide Pre-synthesis temperature (°C) G1 29.7 49.5 20.8 680 G2 32.7 46.9 20.4 710

[0086] An example of the preparation of a C2ZS-CS microwave dielectric ceramic material is as follows:

[0087] Example 1:

[0088] The mixture of 93.47 parts by weight of the main crystal phase C2ZS-CS block C1 and 6.53 parts by weight of the Zn-B-Si block G1 is mixed in a certain ratio, and the mixture is ground and mixed for 15-45 hours with zirconium dioxide balls as grinding medium and water as solvent, and the weight ratio of the mixture: balls: water is 1:5-6: 1.5-2.5. The mixture is dried at 140°C and sieved through an 80-mesh sieve to obtain a dry powder. The dry powder is mixed with 8-12% paraffin, and then pressed into a green body. The green body is sintered at 1030°C for 2-3 hours to obtain the dielectric ceramic material. This is denoted as 1#.

[0089] Example 2

[0090] The difference from Example 1 is that the mixture of 93.99 parts by weight of the main crystal phase C2ZS-CS block C1 and 6.01 parts by weight of the Zn-B-Si block G2 is mixed in a certain ratio. The sintering temperature is 1025°C. This is denoted as 2#.

[0091] Example 3

[0092] The difference from Example 1 is that the weight parts of 91.87 main crystal phase C2ZS-CS sintered block C2 and 8.13 Zn-B-Si sintered block G1 are proportioned. The sintering temperature is 1010℃. It is recorded as 3#.

[0093] Example 4

[0094] The difference from Example 1 is that the weight parts of 93.26 main crystal phase C2ZS-CS sintered block C2 and 6.74 Zn-B-Si sintered block G2 are proportioned. The sintering temperature is 1020℃. It is recorded as 4#.

[0095] Example 5

[0096] The difference from Example 1 is that the weight parts of 94.06 main crystal phase C2ZS-CS sintered block C3 and 5.94 Zn-B-Si sintered block G1 are proportioned. The sintering temperature is 1020℃. It is recorded as 5#.

[0097] Example 6

[0098] The difference from Example 1 is that the weight parts of 92.15 main crystal phase C2ZS-CS sintered block C3 and 7.85 Zn-B-Si sintered block G2 are proportioned. The sintering temperature is 1000℃. It is recorded as 6#.

[0099] Example 7

[0100] The difference from Example 1 is that the weight parts of 93.18 main crystal phase C2ZS-CS sintered block C4 and 6.82 Zn-B-Si sintered block G1 are proportioned. The sintering temperature is 1010℃. It is recorded as 7#.

[0101] Example 8

[0102] The difference from Example 1 is that the weight parts of 92.34 main crystal phase C2ZS-CS sintered block C4 and 7.66 Zn-B-Si sintered block G2 are proportioned. The sintering temperature is 1020℃. It is recorded as 8#.

[0103] Comparative Example 1

[0104] The mass percentage of the main crystal phase is 96.73%, and the mass percentage of the fluxing agent is 3.27%. It is recorded as Comp 1#.

[0105] Comparative Example 2

[0106] The mass percentage of the main crystal phase is 90.33%, and the mass percentage of the fluxing agent is 9.67%. It is recorded as Comp 2#.

[0107] Comparative Example 3:

[0108] The mass percentage of the main crystal phase is 93.26%, the mass percentage of the sintering aid is 6.74%, and the main crystal phase is obtained from 42.11% calcium carbonate, 7.41% zinc oxide, 38.79% silicon dioxide, 4.97% barium carbonate or magnesium carbonate or strontium carbonate, and 6.72% MO by mole percentage. Denoted as 3#.

[0109] Comparative Example 4:

[0110] The mass percentage of the main crystal phase is 93.26%, the mass percentage of the sintering aid is 6.74%, and the main crystal phase is obtained from 40.73% calcium carbonate, 10.42% zinc oxide, 41.86% silicon dioxide, and 6.99% barium carbonate or magnesium carbonate or strontium carbonate by mole percentage. No metal oxide is contained. Denoted as 4#.

[0111] Comparative Example 5:

[0112] The mass percentage of the main crystal phase is 93.26%, the mass percentage of the sintering aid is 6.74%, and the main crystal phase is obtained from 41.3% calcium carbonate, 9.83% zinc oxide, 40.19% silicon dioxide, and 8.68% MO by mole percentage, and no dopant is contained. Denoted as 5#.

[0113] Comparative Example 6:

[0114] The mass percentage of the main crystal phase is 93.26%, the mass percentage of the sintering aid is 6.74%. C2ZS-CS briquettes (C1) are obtained under the condition that the pre-sintering temperature is 1100℃.

[0115] Denoted as 6#.

[0116] Comparative Example 7:

[0117] The patent with the application number "202010631188.5" and the patent name "Low-temperature sintering microwave dielectric ceramic material and preparation method thereof". Denoted as 7#.

[0118] Test:

[0119] The dielectric constant (εr), dielectric loss factor (tgδ), and capacity temperature coefficient (αc) of the dielectric ceramic materials obtained in each embodiment are tested by Agilient8722ET network analyzer. The test results are shown in Table 3:

[0120] Table 3 Performance parameters of dielectric ceramic materials of each embodiment

[0121]

[0122]

[0123] From Table 3, it can be seen that the dielectric constant (1 MHz) of the medium ceramic material obtained by each embodiment is stabilized at about 12, the dielectric loss (1 MHz) is 1.0-1.7x10 -4 , the capacity temperature coefficient is stabilized at 0±15ppm / ℃, the temperature coefficient is CF (0±15ppm / ℃), and the temperature stability of the material is better; the sintering temperature is 1000-1030℃.

[0124] Comparing Comparative Examples 1 and 2 with Example 1, it can be seen that when the content of the main crystal phase is higher than 95% and the content of the cooling agent is lower than 5%, the sintering temperature of the product increases, and the temperature coefficient slightly increases; when the content of the main crystal phase is lower than 91% and the content of the cooling agent is higher than 9%, the sintering temperature of the product decreases, the dielectric constant decreases, and the dielectric loss and the temperature coefficient significantly increase.

[0125] Comparing Comparative Example 3 with Example 1, it can be seen that when the content of zinc oxide is lower than the content of the present application, the temperature coefficient slightly increases, the dielectric loss significantly increases, and the sintering temperature significantly increases (mainly the synthesis temperature of the main crystal phase increases to 1190℃).

[0126] Comparing Comparative Examples 4 and 5 with Example 1, it can be seen that in Comparative Example 4, when the main crystal phase C2ZS-CS is prepared without metal oxides, the sintering temperature of the product significantly increases, the dielectric constant significantly decreases, and the temperature coefficient significantly increases. In Comparative Example 5, when the main crystal phase C2ZS-CS is prepared without dopants, the sintering temperature of the product slightly increases, the dielectric constant slightly increases, and the dielectric loss and the temperature coefficient significantly increase.

[0127] Comparing Comparative Example 6 with Example 4, it can be seen that the synthesis temperature of the C1 main crystal phase is 1100℃, the sintering temperature, the dielectric constant, and the temperature coefficient all increase, and the dielectric performance deteriorates.

[0128] In Comparative Example 7, the dielectric loss of each embodiment is higher than that of Example 1, the lowest is 2.3x10 -4 (as a raw material for preparing LTCC, the loss is higher than 2.0x10 -4 , the maximum capacity temperature coefficient is 33ppm / ℃, and the minimum capacity temperature coefficient is -18ppm / ℃, the capacity temperature coefficient is unstable, and the temperature coefficient is CG (0±30ppm / ℃).

[0129] In Comparative Example 7, the main crystal phase is Ca x Ba 1-x (SiO3) y (Al2O4) 1-y , wherein 0.95≤x≤0.975, 0.965≤y≤0.983, the barium carbonate and the aluminum oxide are main crystal phase materials, and Ba 2+ enters the main crystal structure to form BaSiO3 or BaAl2O4, and Al3+ Enter the main crystal phase structure CaAl2O4 or BaAl2O4, zinc oxide as a modified additive, Zn 2+ Enter the main crystal lattice with Ca 2+ , Ba 2+ Substitution.

[0130] The main crystal phase of the embodiment of the application is Ca2ZnSi2O7-CaSiO3, barium carbonate or magnesium carbonate or strontium carbonate as an additive plays a role in adjusting the temperature coefficient; metal oxides such as aluminum oxide as an additive are used to adjust the insulation performance of the material and improve the reliability of the product; zinc oxide as a main crystal structure material mainly functions to form Ca2ZnSi2O7 crystals to obtain a main crystal phase crystal with dielectric properties. The embodiment of the application obtains a material with more excellent dielectric constant, capacity temperature coefficient, dielectric loss and sintering temperature by reasonably designing the ratio of each raw material in the main crystal phase and the ratio of each raw material of the sintering aid.

[0131] The dielectric ceramic material obtained by the embodiment 4 of the application is used for tape casting to make a multilayer ceramic capacitor (MLCC product), and the specific preparation method is as follows:

[0132] The dielectric ceramic powder is dispersed and ball milled with a ball milling medium and a solvent, and then a binder is added, and the ceramic slurry is prepared after ball milling;

[0133] The ceramic slurry is made into a film strip, and the film strip is printed with an internal electrode paste and dried and formed;

[0134] The film strip printed with the internal electrode and the blank film strip are stacked according to the design of the outer shape size as a chip type and the number of internal electrode layers not less than 2, to form a green body bar;

[0135] The green body bar is pressurized by a warm isostatic press, the temperature is 50-100℃, the pressure is 5000-8000MPa, and the pressure holding time is 20-50min, and the green body bar is cut on a cutting machine to form a capacitor green body;

[0136] The temperature is raised to 450-600℃ at a rate of 0.5-3℃ / min, the binder is discharged, and then the temperature is raised to 1000-1030℃ at a rate of 1-4℃ / min for sintering, and the temperature is lowered with the furnace after holding for 3-4 hours.

[0137] Finally, a 1111-500V-101 type capacitor product is obtained, and the electrode diagram is as follows Figure 2 As can be seen from the electrode diagram, the number of electrode layers is 13, and the electrode continuity is good with 15% Pd85% Ag electrode paste.

[0138] The performance of the obtained MLCC product is as follows:

[0139] MLCC product specification: specification size 1111, rated voltage 500V, capacity 100pF, matching 15% Pd85% Ag electrode paste.

[0140] After sintering at 1005℃, the test results are: capacity 95pF or so, dielectric loss -0.9x10 -4 ~0.3x10 -4 , breakdown voltage 4.1kv, capacity temperature coefficient 0±15ppm / ℃, Q value (100MHz) 1590, better than the same specification imported product level (100MHz Q value 1328, temperature coefficient CG characteristics, main crystal phase MgTiO3).

[0141] The following table 4 is the performance test record of 1111-500V-101 type capacitor product, ESR and Q value test results.

[0142] Table 4

[0143]

[0144] The dielectric ceramic material obtained by the embodiment 4 of the present application is used for batching and casting to make ceramic substrate with specification 38.1x38.1x0.17mm, and the Qxf value is 40107.8G.

[0145] The above detailed description is further detailed for the purpose, technical scheme and beneficial effects of the present application, and it should be understood that the above is only the specific embodiment of the present application, and is not used to limit the protection scope of the present application, any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A microwave dielectric ceramic material, characterized by, The raw materials include main crystal phase C2ZS-CS and Zn-B-Si flux, the chemical formula of the main crystal phase C2ZS-CS is Ca2ZnSi2O7-CaSiO3; The main crystal phase and the flux are 91-95 parts and 5-9 parts by weight respectively; The raw materials for preparing the main crystal phase C2ZS-CS include calcium carbonate, silicon dioxide, zinc oxide, dopant and metal oxide; The dopant includes any one of magnesium carbonate, barium carbonate or strontium carbonate; The metal oxide includes two or more of aluminum oxide, titanium dioxide, lanthanum oxide, niobium pentoxide and bismuth oxide; In the raw materials of the main crystal phase, the molar ratio of calcium carbonate, silicon dioxide, zinc oxide, dopant and metal oxide is (37-42):(38-45):(8-12):(4.9-8.4):(6.1-8.2), the slurry formed by mixing the raw materials is pre-fired at a temperature of 1120-1160°C for 3-5 hours to obtain C2ZS-CS blocks; The raw materials of the flux include zinc oxide, boric acid and silicon dioxide, and the molar ratio of zinc oxide, boric acid and silicon dioxide is (26-33):(45-52):(17-21), the raw materials are mixed and pre-synthesized at 650-730°C to obtain Zn-B-Si blocks.

2. The microwave dielectric ceramic material of claim 1, wherein, The purity of the zinc oxide is greater than 99%.

3. A method for preparing a microwave dielectric ceramic material according to any one of claims 1 to 2, characterized in that, The method comprises the following steps: Preparation of main crystal phase powder: according to the formula, calcium carbonate, silicon dioxide, zinc oxide, dopant and metal oxide are mixed to obtain a first mixture, the obtained first mixture is ground and mixed with water to obtain a first mixture slurry, which is dried, sieved and pre-fired to obtain C2ZS-CS blocks, which are crushed for use; Preparation of Zn-B-Si flux: according to the formula, zinc oxide, boric acid and silicon dioxide are mixed to obtain a second mixture, the second mixture is ground and mixed with ethanol to obtain a second mixture slurry, which is dried and pre-synthesized to obtain Zn-B-Si blocks; According to the formula, C2ZS-CS powder, Zn-B-Si blocks and water are ground and mixed, sieved to obtain a third mixture slurry, which is dried, sieved, pressed and sintered to obtain the microwave dielectric ceramic material.

4. The method of claim 3, wherein the microwave dielectric ceramic material is prepared by the steps of: preparing a first mixture by mixing a first powder and a second powder; preparing a second mixture by mixing a third powder and a fourth powder; and mixing the first mixture and the second mixture. When the first mixture is ground and mixed with water, zirconium dioxide balls are used as the grinding medium, and the material:ball:water weight ratio is 1:5-6:1.5-3, and the grinding and mixing time is 5-8 hours, the first mixture slurry is dried at 140°C and sieved through a 40-mesh sieve before pre-firing.

5. The method for preparing a microwave dielectric ceramic material according to claim 3, characterized in that, When the second mixture is ground and mixed with ethanol, zirconium dioxide balls are used as the grinding medium, and the material:ball:ethanol weight ratio is 1:5-6:1.0-2, and the grinding and mixing time is 5-8 hours, the second mixture slurry is dried and pre-synthesized at 650-730°C for 3 hours to obtain the Zn-B-Si blocks; The C2ZS-CS powder, Zn-B-Si briquettes and water are mixed by grinding with zirconia balls as grinding medium, the weight ratio of material:ball:water is 1:5-6:1.5-2.5, and the grinding and mixing is carried out for 15-45 hours, the third mixture slurry is dried at 140℃ and sieved through 80 mesh screen, the obtained dry powder is added with 8-12% paraffin, and then pressed into a round green body, and sintered at 1000-1030℃ for 2-3 hours to obtain the dielectric ceramic material.

6. A microwave component, characterized by The microwave dielectric ceramic material is prepared by using the microwave dielectric ceramic material according to any one of claims 1-2, or the microwave dielectric ceramic material prepared by using the preparation method according to any one of claims 3-5, and the microwave component includes any one of resonator, filter, dielectric ceramic substrate, antenna, and multilayer ceramic capacitor.

7. A multilayer ceramic capacitor characterized by The microwave dielectric ceramic material is prepared by using the microwave dielectric ceramic material according to any one of claims 1-2, or the microwave dielectric ceramic material prepared by using the preparation method according to any one of claims 3-5; The preparation method is as follows: The microwave dielectric ceramic powder, ball milling medium and solvent are dispersed and ball milled, then the binder is added, and the ceramic slurry is prepared after ball milling; The ceramic slurry is made into a film strip, the film strip is printed with inner electrode slurry and dried to form a shape; The film strip printed with inner electrode and the blank film strip are laminated according to the design of the shape size of the sheet type, and the number of layers of inner electrode is not less than 2, to prepare a green body bar; The green body bar is pressed by a warm isostatic press, the temperature is 50-100℃, the pressure is 5000-8000MPa, the pressure maintaining time is 20-50min, the green body bar is cut on a cutting machine to form a capacitor green body; The temperature is raised to 450-600℃ at a temperature rising rate of 0.5-3℃ / min, the binder is discharged, then the temperature is raised to 1000-1030℃ at a temperature rising rate of 1-4℃ / min for sintering, and the temperature is maintained for 3-4 hours, and then the temperature is lowered with the furnace.

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