CN115286397B - Ceramic substrate and preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of ceramic products, and in particular relates to a ceramic substrate and a preparation method thereof. In order to improve the preparation method of the sheet ceramic heat dissipation substrate material while obtaining high thermal conductivity and mechanical properties, the present invention optimizes the structure and material of the inner matrix and the outer matrix, and combines the hot pressing sintering process to the ceramic substrate Densification is carried out to make the inner matrix material and high thermal conductivity particles form a better combination, the outer matrix can effectively support the inner matrix, and form a better metallurgical interface bond with the inner matrix, so as to ensure that the prepared ceramic substrate has a higher thermal conductivity. Density, hardness, flexural strength, wear resistance, thermal conductivity, and further broaden the application range of the prepared ceramic substrate, so that it can be applied to many fields such as heat conduction and heat dissipation devices and wear-resistant materials. In addition, the preparation method of the present invention is simple, high in efficiency, low in cost, and can be industrialized.

Description

A kind of ceramic substrate and preparation method thereof

technical field

The invention belongs to the technical field of ceramic products, and in particular relates to a ceramic substrate and a preparation method thereof.

Background technique

In recent years, electronic devices such as electric vehicles, wind power generation and LED lighting have entered a stage of rapid development. Due to the current high operating current, high temperature and high frequency of electronic devices, the heat dissipation substrate materials in electronic devices can no longer meet the requirements. In order to ensure the stability and service life of devices and circuits, it is necessary to develop heat-dissipating substrate materials with high thermal conductivity.

Ceramic substrate materials such as aluminum nitride, silicon nitride, and alumina have properties such as high temperature resistance, wear resistance, oxidation resistance, low thermal expansion coefficient, good thermal conductivity, insulation, and electrical breakdown resistance, and are widely used in the field of integrated circuit electronic devices. widely used. However, the current thermal conductivity of aluminum nitride is only 120-200W/(m K), silicon nitride is only 60-100W/(m K), and aluminum oxide is only 10-45W/(m K). . In order to meet the needs of high power, high frequency and integration of electronic devices, it is necessary to further improve the thermal conductivity of ceramic substrate materials. At the same time, the preparation process of the sheet ceramic substrate material is complicated, and the common preparation method is to sinter the ceramic powder after tape casting. However, the casting process needs to add a large amount of organic solvents such as alcohols and ketones, such as polyvinyl butyral (PVB), polyvinyl alcohol (PVA) and other binders, dibutyl phthalate (DBP), etc. Plasticizers, dispersants such as silane coupling agents, these organic solvents can easily cause environmental pollution and endanger the health of operators in the process of casting and debinding. Therefore, it is necessary to improve the preparation method of sheet ceramic heat dissipation substrate materials while obtaining high thermal conductivity and mechanical properties.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned prior art, the present invention proposes a preparation method of a ceramic substrate, which can obtain high thermal conductivity and mechanical properties through processes such as hot-pressing sintering and densification, and can be applied to fields such as heat conduction and wear resistance.

In order to achieve the above object, the technical solution adopted in the present invention is:

The invention provides a method for preparing a ceramic substrate. In terms of raw materials, the ceramic substrate includes a main substrate material, an auxiliary substrate material and a high thermal conductivity particle material, and the main substrate material is selected from powdered aluminum nitride, aluminum oxide, At least one of silicon carbide and silicon nitride, the auxiliary substrate material is selected from Al ₂ O ₃ , SiO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , Y ₂ O ₃ , MgO, CaO, Li ₂ O, At least one of ZnO, the high thermal conductivity particle material is selected from at least one of diamond, cubic boron nitride, tungsten diboride, and graphite sheet; structurally, the ceramic substrate includes an outer matrix on both sides and The inner matrix, and a single layer of closely arranged high thermal conductivity particle material between the inner matrix, the outer matrix is made of the main substrate material and the auxiliary substrate material, the inner matrix is made of the auxiliary substrate material; the ceramic substrate The preparation method comprises the following steps:

S1. Preparation of the outer matrix: mix and ball-mill the powdery main substrate material and the auxiliary substrate material to form a slurry, and then prepare a sheet-shaped compact with a thickness of 0.05-2 mm by cold pressing;

S2, the preparation of the inner matrix, the auxiliary substrate material powder is ball-milled into a slurry, and then cold-pressed to prepare a sheet-shaped green compact with a thickness of 0.05-2mm;

S3. Arrange a single layer of highly thermally conductive granular material tightly on the surface of the inner matrix, cover another layer of inner matrix on the surface of the high thermally conductive granular material for fixation, and then cover two layers of outer matrix for fixing on both sides of the inner matrix , and then use rapid pressure sintering to densify the obtained composite layer, the sintering temperature is 900-1800°C, the holding time is 5-30min, the sintering pressure is 10-100MPa, and the sintering environment is vacuum, nitrogen or argon;

S4. Thinning and grinding the flaky ceramic substrate prepared by sintering to reduce the thickness of the outer matrix to 0.01-1 mm to obtain a ceramic substrate.

In the present invention, the structure and material of the inner matrix and the outer matrix are designed and optimized, and combined with the hot pressing sintering process to densify the ceramic substrate, wherein the inner matrix material can form a better combination with high thermal conductivity particles at a certain temperature, The outer matrix can effectively support the inner matrix during the sintering process, and form a good metallurgical interface bond with the inner matrix, so as to ensure that the substrate material has excellent compactness, mechanical properties and thermal conductivity. Finally, the ceramic substrate material with high strength, high wear resistance and high thermal conductivity can be obtained by thinning and grinding the ceramic substrate. The ceramic substrate prepared by the method of the present invention can be applied in many fields, for example, it can be used as a heat dissipation substrate in the field of high-power and highly integrated semiconductor devices, and it can also be used in wear-resistant materials and devices.

Preferably, the particle size of the main substrate material and the auxiliary substrate material is 1 nm-200 μm, and the particle size of the high thermal conductivity particle material is 100 μm-2000 μm.

Preferably, the single-layer closely arranged high thermal conductivity granular material in step S3 accounts for 20%-50% of the total volume of the composite layer, and after thinning and grinding in step S4, the high thermal conductivity granular material accounts for 40% of the total volume of the ceramic substrate. %-70%.

Preferably, the auxiliary substrate material includes 20wt% _Y2O3 , 10wt% MgO, 55wt% _SiO2 , 5wt% ZnO, 10wt% _Bi2O3 , or 10wt% MgO, _{45wt % SiO2} , 5wt% CaO, 10wt% B2O3, 30wt% _Al2O3 , or 30wt _{% B2O3} , _40wt % _Bi2O3 , 10wt _{% Li2O} , _{20wt % SiO2} .

Preferably, in step S1, the volume percentage of the main substrate material is 60%-100%.

Preferably, in steps S1 and S2, during ball milling, absolute ethanol is used as the ball milling solvent, and high-purity zirconia balls are used as grinding balls, and the mass ratio of the powder material to absolute ethanol and the grinding balls is 1:(1- 3): (1-10), the time of ball milling is 1-15h, and the speed is 150-350r/min.

Preferably, in steps S1 and S2, the pressure of cold pressing is 100-250 MPa, and the thickness of the compact is 0.05-2 mm.

Preferably, after the thinning and grinding step S4, the thickness of the outer matrix is reduced to 0-0.2mm.

Preferably, in step S4, grinding is performed with a 400-1000 mesh resin or metal bonded diamond grinding wheel, and a double-sided grinding machine is used for grinding with a 500nm-10 μm diamond grinding liquid.

Preferably, the high thermal conductivity particle material is selected from diamond or cubic boron nitride or tungsten diboride particles.

Preferably, the main substrate material is selected from aluminum nitride or aluminum oxide or silicon nitride powder.

The present invention also provides the ceramic substrate prepared by the above preparation method.

The present invention also provides the application of the above-mentioned ceramic substrate in the preparation of heat-conducting and heat-dissipating materials and/or wear-resistant materials.

Compared with prior art, the beneficial effect of the present invention is:

The invention discloses a preparation method of a ceramic substrate. By designing and optimizing the structure and material of the inner matrix and the outer matrix, and combining the hot pressing sintering process to densify the ceramic substrate, the inner matrix material and high thermal conductivity particles are formed. Better combination, the outer matrix can effectively support the inner matrix, and form a better metallurgical interface with the inner matrix, so as to ensure that the prepared ceramic substrate has higher density, hardness, flexural strength, wear resistance, thermal The conductivity further broadens the application range of the prepared ceramic substrate, so that it can be applied to many fields such as heat conduction and heat dissipation devices and wear-resistant materials. In addition, the preparation method of the present invention is simple, high in efficiency, low in cost, and can be industrialized.

Description of drawings

1 is a schematic diagram of the structure and preparation process of a ceramic substrate;

Figure 2 shows the structure of the aluminum nitride ceramic substrate and its thermal conductivity at different thicknesses of the outer substrate.

Detailed ways

Specific embodiments of the present invention will be further described below. It should be noted here that the descriptions of these embodiments are used to help understand the present invention, but are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not constitute a conflict with each other.

The experimental methods in the following examples, unless otherwise specified, are conventional methods, and the test materials used in the following examples, unless otherwise specified, can be purchased through conventional commercial channels.

Embodiment 1 A kind of preparation method of sheet ceramic substrate

In terms of raw materials, the raw materials of the sheet-shaped ceramic substrate include main substrate materials, auxiliary substrate materials and high thermal conductivity granular materials. The main substrate material uses aluminum nitride powder with a particle size of 10 μm, and the auxiliary substrate material includes 20wt% Y ₂ O ₃ , 10wt% MgO, 55wt% SiO ₂ , 5wt% ZnO, 10wt% Bi ₂ O ₃ , the The high thermal conductivity granular material uses 12/14 mesh diamond.

Structurally, the sheet-like ceramic substrate includes an outer matrix and an inner matrix on both sides, and high thermal conductivity particles located between the inner matrix. The high thermal conductivity particles are closely arranged in a single layer, that is, each high thermal conductivity particle Only in contact with the inner matrix in the plane, there is no up and down overlapping state, and the single layer of closely arranged high thermal conductivity particles accounts for 28% of the total volume of the ceramic substrate. In the outer matrix, the volume percentage of the main substrate material is 60%, and the volume percentage of the auxiliary substrate material is 40%. The inner matrix is made of auxiliary substrate material.

The preparation method of the sheet ceramic substrate material comprises the following steps:

(1) Preparation of the outer matrix: Weigh the powdered main substrate material and auxiliary substrate material, place them in a polytetrafluoroethylene ball mill jar, use absolute ethanol as the ball mill solvent, and use high-purity zirconia balls as the grinding balls. Powder: anhydrous ethanol: grinding ball = 1:1:4 weight ratio using a planetary ball mill to mix evenly, the ball milling time is 8 hours, and the rotation speed is 350r/min. Then put the mixed slurry into the flask of the rotator, and rotate it at a temperature of 65°C to remove alcohol; after the obtained powder is sieved, it is cold-pressed with a cemented carbide mold under a uniaxial pressure of 200Mpa. Prepare a sheet-shaped compact with a thickness of 0.5 mm.

(2) Preparation of inner matrix: Mix auxiliary substrate material powder (Y ₂ O ₃ , MgO, SiO ₂ , ZnO, Bi ₂ O ₃ ) with absolute ethanol, use high-purity zirconia balls as grinding balls, and then follow Powder: absolute ethanol: grinding ball = 1:1:4 weight ratio using a planetary ball mill to mix evenly, the ball milling time is 8h, the rotating speed is 350r/min, then put the mixed slurry into the flask of the rotator, Rotary evaporation at a temperature of 65°C to remove alcohol; the resulting powder was sieved and cold-pressed with a Rongmei FLS four-column hydraulic press under a uniaxial pressure of 200Mpa to prepare a sheet-shaped compact material with a thickness of 0.5mm.

石墨模具和快速直烧式热压烧结机(DSP507)，通过快速热压烧结的方式进行致密化，烧结的温度为1750℃，保温时间为10min，烧结的压力为40MPa，保护气氛为氩气。(3) As shown in Figure 1, the 12/14-mesh diamond monolayer is densely packed and distributed on the surface of the inner matrix without overlapping up and down, another layer of inner matrix is covered on the surface of the diamond layer for fixation, and then two outer layers The base body is respectively covered on both sides of the inner base body for fixing. Then, use

Graphite molds and rapid direct-fired hot-press sintering machines (DSP507) are densified by rapid hot-press sintering. The sintering temperature is 1750°C, the holding time is 10min, the sintering pressure is 40MPa, and the protective atmosphere is argon.

Scanning electron microscope observation shows that the aluminum nitride ceramic substrate prepared by this method has a good inlaid diamond matrix, no obvious pores and cracks, and a good combination of the outer matrix and the inner matrix is also achieved. Through the test of Archimedes drainage method, it is found that the density of 98% can be obtained, and the thermal diffusivity is obtained by using the laser thermal conductivity meter (LFA 447), and the thermal conductivity of the sintered ceramic substrate is calculated according to the density and specific heat capacity of 195W/(m · K), using a universal testing machine (AGS-X-50KND) to test with a three-point bending method to obtain a bending strength of 236MPa.

(4) As shown in Figure 2, there is a strict correlation between the thickness of the outer matrix layer and the thermal conductivity of the ceramic substrate, and the thermal conductivity of the ceramic substrate can be controlled by the thickness of the outer matrix layer. To this end, thinning and grinding the sheet ceramic substrate (aluminum nitride ceramic substrate) prepared by sintering: use 800 mesh resin bonded diamond grinding wheel, set the grinding wheel speed, depth of cut and feed rate to 20m/s respectively , 15μm and 7.5m/min, use a surface grinder to grind and cut the thin metal outer matrix to 0.1mm. And using a double-sided grinding machine (FD-6BL), the diamond water-based grinding fluid with a particle size of 5 μm (purchased from Zhongwei Grinding Technology Co., Ltd.) was used for grinding. After thinning and grinding, the thickness of the outer matrix was 0.1 mm. The surface roughness measured by an interferometer (Taylor-Hobson) was Ra 96nm. After thinning, the volume fraction of diamond in the ceramic substrate increases to 52%, and the thermal conductivity increases to 275 W/(m·K).

Embodiment 2 A preparation method of a sheet ceramic substrate

In terms of raw materials, the raw materials of the sheet-shaped ceramic substrate include main substrate materials, auxiliary substrate materials and high thermal conductivity granular materials. The main substrate material uses alumina powder with a particle size of 500nm, and the auxiliary substrate material includes 10wt% MgO, 45wt% SiO ₂ , 5wt% CaO, 10wt% B ₂ O ₃ , 30wt% Al ₂ O ₃ , so The high thermal conductivity granular material uses 100/120 mesh cubic boron nitride.

Structurally, the sheet-like ceramic substrate includes an outer matrix and an inner matrix on both sides, and high thermal conductivity particles located between the inner matrix. The high thermal conductivity particles are closely arranged in a single layer, that is, each high thermal conductivity particle Only in contact with the inner matrix in the plane, there is no up and down overlapping state, and the single layer of closely arranged high thermal conductivity particles accounts for 20% of the total volume of the ceramic substrate. In the outer matrix, the volume percentage of the main substrate material is 60%, and the volume percentage of the auxiliary substrate material is 40%. The inner matrix is made of auxiliary substrate material.

The preparation method of the sheet ceramic heat dissipation substrate material comprises the following steps:

(1) Preparation of the outer matrix: Weigh the powdered main substrate material and auxiliary substrate material, place them in a polytetrafluoroethylene ball mill jar, use absolute ethanol as the ball mill solvent, and use high-purity zirconia balls as the grinding balls. Powder: anhydrous ethanol: grinding ball = 1:2:3 weight ratio using a planetary ball mill to mix evenly, the ball milling time is 10h, and the rotation speed is 300r/min. Then put the mixed slurry into the flask of the rotator, and rotate it at a temperature of 60°C to remove alcohol; after the obtained powder is sieved, it is cold-pressed with a cemented carbide mold under a uniaxial pressure of 150Mpa. Prepare a sheet-shaped compact with a thickness of 0.2 mm.

(2) Preparation of inner matrix: Mix auxiliary substrate material powder (MgO, SiO ₂ , CaO, B ₂ O ₃ , Al ₂ O ₃ ) with absolute ethanol, use high-purity zirconia balls as grinding balls, and then follow Powder: anhydrous ethanol: grinding ball = 1:2:3 weight ratio using a planetary ball mill to mix evenly, the ball milling time is 10h, the rotating speed is 300r/min, then put the mixed slurry into the flask of the rotator, Rotary evaporation at a temperature of 60°C to remove alcohol; the resulting powder was sieved and cold-pressed with a Rongmei FLS four-column hydraulic press under a uniaxial pressure of 150Mpa to prepare a sheet-shaped compact material with a thickness of 0.2mm.

石墨模具和快速直烧式热压烧结机(DSP507)，通过快速热压烧结的方式进行致密化，烧结的温度为1550℃，保温时间为10min，烧结的压力为35MPa，保护气氛为氩气。(3) As shown in Figure 1, a single layer of cubic boron nitride particles of 100/120 mesh is densely arranged on the surface of the inner matrix without overlapping up and down, and another layer of inner matrix is covered on the surface of the diamond layer for fixation, and then Cover the two sides of the inner matrix with two layers of outer matrix respectively for fixing. Then, use

Graphite molds and rapid direct-fired hot-press sintering machines (DSP507) are densified by rapid hot-press sintering. The sintering temperature is 1550°C, the holding time is 10min, the sintering pressure is 35MPa, and the protective atmosphere is argon.

Scanning electron microscope observation shows that the alumina ceramic substrate prepared by this method has a good inlaid diamond matrix, no obvious pores and cracks, and a good combination of the outer matrix and the inner matrix is also achieved. It is found that a density of 96% can be obtained by the Archimedes drainage method test.

(4) Thinning and grinding the sheet-like ceramic substrate (alumina ceramic substrate) prepared by sintering: use a 400-mesh metal-bonded diamond grinding wheel, set the grinding wheel speed, depth of cut and feed rate to 10m/s, 10μm and 5m/min, use a surface grinder to grind and cut the thin metal outer matrix to 0.2mm. And use a double-sided grinding machine (FD-6BL) to grind with a diamond water-based grinding fluid with a particle size of 1 μm. After thinning and grinding, the thickness of the outer matrix is 0.2 mm, and the surface is obtained by using a white light interferometer (Taylor-Hobson). The roughness is Ra 86nm, the volume fraction of cubic boron nitride is 41%, the thermal diffusivity is obtained by using the laser thermal conductivity meter (LFA 447), and the thermal conductivity is calculated according to the density and specific heat capacity. The thermal conductivity is 51W/(m K), using The universal testing machine (AGS-X-50KND) obtained a bending strength of 201MPa by three-point bending method.

Embodiment 3 A preparation method of a sheet ceramic substrate

In terms of raw materials, the raw materials of the sheet-shaped ceramic substrate include main substrate materials, auxiliary substrate materials and high thermal conductivity granular materials. The main substrate material uses silicon nitride powder with a particle size _of 100 μm, the auxiliary substrate material includes 30wt% B2O3, _40wt % _Bi2O3 , 10wt% _Li2O , 20wt _{% SiO2} , the The high thermal conductivity particle material uses 50/60 mesh tungsten diboride particles.

Structurally, the sheet-like ceramic substrate includes an outer matrix and an inner matrix on both sides, and high thermal conductivity particles located between the inner matrix. The high thermal conductivity particles are closely arranged in a single layer, that is, each high thermal conductivity particle Only in contact with the inner matrix in the plane, there is no up and down overlapping state, and the single layer of closely arranged high thermal conductivity particles accounts for 23% of the total volume of the ceramic substrate. In the outer matrix, the volume percentage of the main substrate material is 80%, and the volume percentage of the auxiliary substrate material is 20%. The inner matrix is made of auxiliary substrate material.

The preparation method of the sheet ceramic substrate material comprises the following steps:

(1) Preparation of the outer matrix: Weigh the powdered main substrate material and auxiliary substrate material, place them in a polytetrafluoroethylene ball mill jar, use absolute ethanol as the ball mill solvent, and use high-purity zirconia balls as the grinding balls. Powder: anhydrous ethanol: grinding ball = 1:2:4 weight ratio using a planetary ball mill to mix evenly, the ball milling time is 15h, and the rotation speed is 300r/min. Then put the mixed slurry into the flask of the rotator, and rotatively evaporate at a temperature of 60°C to remove alcohol; after the obtained powder is sieved, it is cold-pressed under a uniaxial pressure of 200Mpa using a cemented carbide mold, Prepare a sheet-shaped compact with a thickness of 0.4 mm.

(2) Preparation of inner matrix: Mix auxiliary substrate material powder (B ₂ O ₃ , Bi ₂ O ₃ , Li ₂ O, SiO ₂ ) with absolute ethanol, use high-purity zirconia balls as grinding balls, and then follow Powder: absolute ethanol: weight ratio of grinding ball = 1:2:4, use planetary ball mill to mix evenly, the time of ball milling is 15h, the rotating speed is 300r/min, then put the mixed slurry into the flask of rotator, Rotary evaporation at a temperature of 70°C to remove alcohol; the resulting powder was sieved and cold-pressed with a Rongmei FLS four-column hydraulic press under a uniaxial pressure of 200Mpa to prepare a sheet-shaped compact material with a thickness of 0.2mm.

石墨模具和快速直烧式热压烧结机(DSP507)，通过快速热压烧结的方式进行致密化，烧结的温度为1800℃，保温时间为15min，烧结的压力为40MPa，保护气氛为氩气。(3) As shown in Figure 1, a single layer of 50/60 mesh tungsten diboride particles is densely packed and distributed on the surface of the inner matrix without overlapping up and down, and another layer of inner matrix is covered on the surface of the diamond layer for fixation, and then Cover the two sides of the inner matrix with two layers of outer matrix respectively for fixing. Then, use

Graphite molds and rapid direct-fired hot-press sintering machines (DSP507) are densified by rapid hot-press sintering. The sintering temperature is 1800°C, the holding time is 15min, the sintering pressure is 40MPa, and the protective atmosphere is argon.

Scanning electron microscope observation shows that the silicon nitride ceramic substrate prepared by this method has a good inlaid diamond matrix, no obvious pores and cracks, and a good combination of the outer matrix and the inner matrix is also achieved. It is found that 97% density can be obtained by the Archimedes drainage method test.

(4) Thinning and grinding the sheet-shaped ceramic substrate (silicon nitride ceramic substrate) prepared by sintering: use an 800-mesh resin bonded diamond grinding wheel, and set the grinding wheel speed, depth of cut and feed rate to 20m/s respectively , 15μm and 7.5m/min, use a surface grinder to grind and cut the thin metal outer matrix to 0.01mm, and use a double-sided grinder (FD-6BL) to grind with a diamond water-based grinding fluid with a particle size of 5μm. After thinning and grinding Finally, after the outer matrix is completely removed, the white light interferometer (Taylor-Hobson) is used to test the surface roughness (Ra) of 90nm, and the volume fraction of tungsten diboride is 40%. The ceramic substrate obtained by grinding and polishing is tested by friction and wear Test, through the ball-on-disk friction and wear test, using the CFT-I material surface performance comprehensive tester (Lanzhou Zhongke Kaihua Technology Development Co., Ltd.) to test the tribological properties of the sample, under the load of 5N, the silicon nitride ceramic substrate The wear rate is 3.82×10 ^-6 mm ³ /mN, while the wear rate of silicon nitride ceramics without high thermal conductivity particles is 5.62×10 ^-6 mm ³ /mN. The results show that the wear resistance of the ceramic substrate is significantly better than that of silicon nitride. The thermal diffusivity was obtained by using a laser thermal conductivity meter (LFA 447), and the thermal conductivity was calculated according to the density and specific heat capacity to be 121W/(m K). Using a universal testing machine (AGS-X-50KND) with a three-point bending method The bending strength obtained by the test is 456MPa.

The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions and modifications to these embodiments still fall within the protection scope of the present invention.

Claims (10)

1. A method for preparing a ceramic substrate, characterized in that, on raw materials, the ceramic substrate includes a main substrate material, an auxiliary substrate material and a high thermal conductivity particle material, and the main substrate material is selected from powdered aluminum nitride, oxide At least one of aluminum, silicon carbide and silicon nitride, the auxiliary substrate material is selected from Al ₂ O ₃ , SiO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , Y ₂ O ₃ , MgO, CaO, Li ₂ At least one of O and ZnO, the high thermal conductivity particle material is selected from at least one of diamond, cubic boron nitride, tungsten diboride, and graphite sheet; structurally, the ceramic substrate includes outer a matrix and an inner matrix, and a single layer of closely arranged high thermal conductivity particle material located between the inner matrix, the outer matrix is made of a main substrate material and an auxiliary substrate material, and the inner matrix is made of an auxiliary substrate material; the The preparation method of ceramic substrate comprises the following steps: S1. Preparation of the outer matrix: mix and ball-mill the powdery main substrate material and the auxiliary substrate material to form a slurry, and then prepare a sheet-shaped compact with a thickness of 0.05-2 mm by cold pressing; S2, the preparation of the inner matrix, the auxiliary substrate material powder is ball-milled into a slurry, and then cold-pressed to prepare a sheet-shaped green compact with a thickness of 0.05-2mm; S3. Arrange a single layer of highly thermally conductive granular material tightly on the surface of the inner matrix, cover another layer of inner matrix on the surface of the high thermally conductive granular material for fixation, and then cover two layers of outer matrix for fixing on both sides of the inner matrix , and then use rapid pressure sintering to densify the obtained composite layer, the sintering temperature is 900-1800°C, the holding time is 5-30min, the sintering pressure is 10-100MPa, and the sintering environment is vacuum, nitrogen or argon; S4. Thinning and grinding the sheet-shaped ceramic substrate prepared by sintering to reduce the thickness of the outer matrix to 0-1 mm to obtain a ceramic substrate. 2. The preparation method of a ceramic substrate according to claim 1, wherein the particle diameter of the main substrate material and the auxiliary substrate material is 1 nm-200 μm, and the particle diameter of the high thermal conductivity granular material is 100 μm -2000 μm. 3. The preparation method of a ceramic substrate according to claim 1, characterized in that the single-layer closely arranged high thermal conductivity granular material in step S3 accounts for 20%-50% of the total volume of the composite layer, and after step S4 After thinning and grinding, the high thermal conductivity granular material accounts for 40%-70% of the total volume of the ceramic substrate. 4. The preparation method of a ceramic substrate according to claim 1, wherein the auxiliary substrate material comprises 20wt% Y ₂ O ₃ , 10wt% MgO, 55wt% SiO ₂ , 5wt% ZnO, 10wt% Bi ₂ O ₃ , or 10wt% MgO, 45wt% SiO ₂ , 5wt% CaO, 10wt% B ₂ O ₃ , 30wt% Al ₂ O ₃ , or 30wt% B ₂ O ₃ , 40wt% Bi ₂ O ₃ , 10wt% Li ₂ O, 20 wt% SiO ₂ . 5 . The method for preparing a ceramic substrate according to claim 1 , wherein, in step S1 , the volume percentage of the main substrate material is 60%-100%. 6. The preparation method of a kind of ceramic substrate according to claim 1, characterized in that, in steps S1 and S2, during ball milling, absolute ethanol is used as the ball milling solvent, and high-purity zirconia balls are used as the grinding balls, and the powder The mass ratio of bulk material to absolute ethanol and grinding balls is 1:(1-3):(1-10), the time of ball milling is 1-15h, and the rotating speed is 150-350r/min. 7 . The method for preparing a ceramic substrate according to claim 1 , wherein, in steps S1 and S2 , the pressure of cold pressing is 100-250 MPa, and the thickness of the compact is 0.05-2 mm. 8. The preparation method of a ceramic substrate according to claim 1, characterized in that, in step S4, use 400-1000 mesh resin or metal bonded diamond grinding wheel for grinding, and use a double-sided grinding machine with a thickness of 500nm-10μm Diamond grinding fluid for grinding. 9. The ceramic substrate prepared by the preparation method according to any one of claims 1-8. 10. The application of the ceramic substrate according to claim 9 in the preparation of heat-conducting and heat-dissipating materials and/or wear-resistant materials.

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