Large-size, high-smoothness and high-strength aluminum oxide ceramic substrate and preparation method thereof

Abstract

The invention discloses a large-size, high-flatness and high-strength aluminum oxide ceramic substrate and a preparation method thereof, and relates to the technical field of ceramic materials.The preparation method of the large-size, high-flatness and high-strength aluminum oxide ceramic substrate comprises the steps that S1, aluminum oxide powder, a solvent, a dispersing agent and a sintering aid are added into a ball milling tank, and ball milling is conducted; adding zirconium balls into the ball milling tank, and carrying out primary ball milling to obtain primary slurry, wherein the weight ratio of the alumina powder to the solvent to the dispersing agent to the sintering aid to the zirconium balls is 200: 80: 6: 1: 600; s2, a binder and a plasticizer are added into the primary slurry for secondary ball milling, aluminum oxide tape casting slurry is obtained, and the weight ratio of the primary slurry to the binder to the plasticizer is 287: 20: 3. The preparation method of the aluminum oxide ceramic substrate has the beneficial effects that the large-size aluminum oxide ceramic substrate prepared by the preparation method of the aluminum oxide ceramic substrate is high in flatness and high in strength, and can effectively meet the requirements of various application scenes such as high-end electronic element carriers and precision measurement platforms.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic materials, and in particular to a large-size, high-flatness, high-strength alumina ceramic substrate and a preparation method thereof. Background Art

[0002] With the development of science and technology, the market has put forward higher requirements for ceramic substrates in the electronics industry and precision instrument fields. Traditional small-sized, low-strength ceramic substrates can no longer meet the needs of modern industry. Therefore, it is particularly important to develop an alumina ceramic substrate that combines large size, high flatness and high strength. Large-sized alumina ceramic substrates in the prior art often have difficulty in taking into account the characteristics of high flatness and high strength at the same time. Summary of the invention

[0003] The main purpose of the present invention is to provide a large-size, high-flatness, high-strength alumina ceramic substrate and a preparation method thereof, aiming to solve the problem of poor flatness and low strength of existing large-size alumina ceramic substrates after sintering.

[0004] In order to solve the above problems, the present invention proposes a method for preparing a large-size, high-flatness, and high-strength alumina ceramic substrate, comprising: S1, adding alumina powder, solvent, dispersant, and sintering aid into a ball mill, and then adding zirconium balls into the ball mill for one ball milling to obtain a primary slurry, wherein the weight ratio of alumina powder, solvent, dispersant, sintering aid, and zirconium balls is 200:80:6:1:600; S2, adding a binder and a plasticizer to the primary slurry for secondary ball milling to obtain an alumina tape casting slurry, wherein the weight ratio of the primary slurry, the binder, and the plasticizer is 287:20:3; S3, degassing the alumina tape casting slurry; S4, tape-casting the alumina tape-casting slurry after degassing on a tape-casting machine, and drying to obtain a tape-casting green body; S5, subjecting the tape-cast green body to isostatic pressing in a warm isostatic press; S6, placing the tape-cast green body after isostatic pressing in an air environment at 25° C. for 30 days; S7, cutting the tape-cast green body that has been left to stand still into blocks of a desired size, and then stacking the blocks, sprinkling spherical alumina powder between two adjacent layers of blocks, and placing a sintering plate or a metal plate on the top layer of blocks; S8, sequentially debinding, sintering, grinding and polishing the stacked green blocks to obtain an alumina ceramic substrate.

[0005] In one embodiment, the purity of the alumina powder is ≥ 99.9%; The solvent is one or more of ethanol, isopropanol, methyl ethyl ketone, trichloroethylene, benzene, toluene, and xylene; The dispersant is one or more of oleic acid, triethyl phosphate, and castor oil; The sintering aid is one or more of Y2O3, MgO, SiO2, ZrO2, and CaO; The binder is polyvinyl butyral; The plasticizer is one or more of dibutyl phthalate, polyethylene glycol, and dioctyl phthalate; The debinding temperature is 500-700°C, the debinding rate is 1°C / min, and the sintering temperature is 1550-1650°C.

[0006] In one embodiment, the mesh size of the spherical alumina in S7 is 300-500 meshes, the number of stacked layers of the green blocks is 6-10 layers, and the weight of the pressed support plate or metal plate is 100-200 g.

[0007] In one embodiment, in S7, the blocks are stacked and transported by a flatbed trolley, and spherical alumina powder is sprinkled between two adjacent layers of blocks by a powder sprinkling device.

[0008] In one embodiment, the powder spreading device comprises: A frame, on which a screw rod is vertically mounted, and the screw rod is screwed to the frame; The motor is connected to the frame in a vertical sliding manner and is connected to the screw drive; The loading plate is connected to the frame for vertical sliding and is connected to the screw for rotation. A horizontal push device and a hopper are arranged on the loading plate. The hopper is connected to the horizontal push device, and the hopper is pushed to move horizontally on the loading plate through the horizontal push device.

[0009] In one embodiment, the step S7, cutting the tape-cast green body after standing still into blocks of a desired size, then stacking the blocks, sprinkling spherical alumina powder between two adjacent layers of blocks, and pressing the topmost block with a sintering plate or a metal plate comprises: S71, cutting the tape-cast green body that has been left to stand still into blocks of required sizes; S72, placing a layer of briquettes on a flatbed trolley, pushing the flatbed trolley to move to just below the loading plate, and positioning the hopper just above the briquettes; S73, pouring spherical alumina powder into the hopper, and then controlling the horizontal push device to push the hopper to move horizontally to evenly spread the spherical alumina powder on the billet; S74, controlling the motor to rotate and drive the screw to rotate, and the screw rotation drives the motor and the carrier plate to slide upward on the frame, and then another layer of blocks is placed on the blocks on the flatbed trolley; S75, repeat S73 and S74, and finally press a support plate or a metal plate on the uppermost layer of the green blocks.

[0010] In one embodiment, the frame includes a bottom plate, a column, a cross bar, and a screw barrel, wherein the lower end of the column is fixedly connected to the bottom plate, the cross bar is fixedly connected to the upper end of the column, the screw barrel is vertical and fixedly connected to the cross bar, and the screw rod passes through the screw barrel and is screwed to the screw barrel; The frame also includes a slide rail, which is fixedly connected to the crossbar and the bottom plate, and the motor and the loading plate are vertically slidably connected to the slide rail.

[0011] In one embodiment, a sliding hole is provided on the carrier plate, a sliding rod is provided on the hopper, the sliding rod is slidably connected to the upper and lower surfaces of the carrier plate, the hopper passes through the sliding hole, and is horizontally slidably connected to the carrier plate through the sliding rod.

[0012] In one embodiment, the discharge port of the hopper is connected to a discharge pipe through a connecting hose, and a vibration motor and a counterweight are provided on the discharge pipe, and the vibration motor and the counterweight are symmetrically arranged on both sides of the discharge pipe; The discharge pipe is flat.

[0013] In addition, the present invention also proposes a large-size, high-flatness, high-strength alumina ceramic substrate, which is prepared by any of the aforementioned methods for preparing a large-size, high-flatness, high-strength alumina ceramic substrate.

[0014] Beneficial effects: The large-size alumina ceramic substrate prepared by the preparation method of the alumina ceramic substrate of the present application has high flatness and high strength, which can effectively meet the needs of various application scenarios such as high-end electronic component carriers and precision measurement platforms. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 is a front view of the powder spreading device of the present invention; Figure 2 1 is an internal structure diagram of the powder spreading device of the present invention, in which the flatbed trolley has been moved below the loading plate, and multiple layers of alumina ceramic substrates have been stacked on the flatbed trolley; Figure 3 is a top view of the powder spreading device of the present invention; Figure 4 It is a schematic structural diagram of the carrier plate of the present invention; Figure 5 yes Figure 2 Enlarged view of part A in .

[0017] The accompanying drawings are described as follows: 1. Base plate; 2. Column; 3. Cross bar; 4. Screw barrel; 5. Screw; 6. Coupling; 7. Motor; 8. Slide rail; 9. Loading plate; 10. Push device; 11. Slide hole; 12. Hopper; 13. Slide bar; 14. Alumina ceramic substrate; 15. Flatbed trolley; 16. Connecting hose; 17. Discharge pipe; 18. Vibration motor; 19. Counterweight. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0020] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] The present invention proposes a method for preparing a large-size, high-flatness, and high-strength alumina ceramic substrate. The large-size alumina ceramic substrate prepared by the method has high flatness and high strength, and can effectively meet the needs of various application scenarios such as high-end electronic component carriers and precision measurement platforms. In addition, the large-size alumina ceramic substrate has excellent chemical stability and corrosion resistance, and is an ideal basic material for high-performance electronic devices and precision instruments. The alumina purity of the large-size alumina ceramic substrate is greater than 99%, the size range exceeds 500mm×500mm, the overall thickness deviation is less than ±0.05mm, the flatness tolerance is less than 0.01mm, and the three-point bending strength is greater than 450MPa.

[0023] Specifically, in one embodiment of the invention, the method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate comprises: S1. Alumina powder, solvent, dispersant and sintering aid are added to a ball mill, and then zirconium balls are added to the ball mill for one ball milling to obtain a primary slurry, wherein the weight ratio of the alumina powder, solvent, dispersant, sintering aid and zirconium balls is 200:80:6:1:600. The addition of the sintering aid can improve the fluidity and filling property of the green body, improve the surface quality and dimensional accuracy of the finished alumina ceramic substrate, and improve the mechanical strength and fracture toughness of the alumina ceramic substrate, with the strength reaching more than 320 MPa, so that the alumina ceramic substrate can withstand greater mechanical loads and thermal cycle shocks; S2, adding a binder and a plasticizer to the primary slurry for secondary ball milling to obtain an alumina tape casting slurry, wherein the weight ratio of the primary slurry, the binder, and the plasticizer is 287:20:3; S3, degassing the alumina tape casting slurry; S4, tape-casting the alumina tape-casting slurry after degassing on a tape-casting machine, and drying to obtain a tape-casting green body; S5, subjecting the tape-cast green body to isostatic pressing in a warm isostatic press to improve the density of the alumina ceramic substrate, and to enhance the mechanical strength and fracture toughness of the alumina ceramic substrate, with the strength reaching above 320 MPa, so that the alumina ceramic substrate can withstand greater mechanical loads and thermal cycle shocks, and has the advantage of high strength; S6. The tape-cast green body after isostatic pressing is placed in an air environment at 25° C. for 30 days to fully release stress and fully homogenize the tape-cast green body, ensure uniform and stable volatilization of organic matter during debinding and sintering, make the shrinkage rate of the alumina ceramic substrate in all directions consistent, and ensure flatness; S7, cutting the tape-cast green body that has been left to stand still into green blocks of a desired size, and then stacking the green blocks, sprinkling spherical alumina powder between two adjacent layers of green blocks, and placing a setter plate or a metal plate on the green blocks on the top layer, the spherical alumina between the green block layers can fully ensure that the alumina ceramic substrate shrinks smoothly without cracking, and the constrained sintering of the setter plate or the metal plate can suppress the deformation and warping of the alumina ceramic substrate to ensure flatness; S8, sequentially debinding, sintering, grinding and polishing the stacked green blocks to obtain an alumina ceramic substrate.

[0024] Specifically, the purity of the alumina powder is ≥99.9%; The solvent is one or more of ethanol, isopropanol, methyl ethyl ketone, trichloroethylene, benzene, toluene, and xylene; The dispersant is one or more of oleic acid, triethyl phosphate, and castor oil; The sintering aid is one or more of Y2O3, MgO, SiO2, ZrO2, and CaO; The binder is polyvinyl butyral; The plasticizer is one or more of dibutyl phthalate, polyethylene glycol, and dioctyl phthalate; The debinding temperature is 500-700°C, the debinding rate is 1°C / min, and the sintering temperature is 1550-1650°C.

[0025] In this embodiment, the mesh number of the spherical alumina in S7 is 300~500 mesh, the number of stacked layers of green blocks is 6~10 layers, and the weight of the pressed supporting plate or metal plate is 100~200g. This design can ensure that the alumina ceramic substrate has consistent shrinkage rates in all directions and has the characteristics of high flatness without damaging the alumina ceramic substrate.

[0026] Further, in order to improve the preparation efficiency of the alumina ceramic substrate 14, the blocks can be stacked and transported by a flatbed trolley 15 in S7, and spherical alumina powder can be sprinkled between the upper and lower adjacent layers of blocks by a powder sprinkling device, such as Figure 1-Figure 5As shown, the powder spreading device includes: a frame, a motor 7, and a loading plate 9. A screw 5 is vertically installed on the frame, and the screw 5 is screwed to the frame; the motor 7 is vertically slidably connected to the frame and is transmission-connected to the screw 5. After the motor 7 is started, the screw 5 is driven to rotate, and then the motor 7 is driven to rise and fall; the loading plate 9 is vertically slidably connected to the frame and is rotationally connected to the screw 5. The rotation of the screw 5 drives the loading plate 9 and the motor 7 to rise and fall synchronously. The loading plate 9 is provided with a horizontal push device 10 and The hopper 12 is connected to the horizontal pushing device 10, and the horizontal pushing device 10 pushes the hopper 12 to move horizontally on the loading plate 9 to evenly spread the spherical alumina powder in the hopper 12 on the upper surface of the green block. This design saves the trouble of manually spreading the spherical alumina powder evenly on the upper surface of the green block, and compared with manual spreading, it can ensure uniform spreading, fast spreading speed, high efficiency, and good spreading effect, which effectively improves the preparation efficiency of the alumina ceramic substrate 14, reduces costs and increases efficiency, and improves production benefits.

[0027] In this embodiment, if Figure 1-Figure 5 As shown, the S7, cutting the tape-cast green body that has been left to stand still into blocks of a desired size, then stacking the blocks, sprinkling spherical alumina powder between the upper and lower adjacent blocks, and placing a sintering plate or a metal plate on the top block, comprises: S71, cutting the tape-cast green body that has been left to stand still into blocks of required sizes; S72, placing a layer of briquettes on the flatbed trolley 15, pushing the flatbed trolley 15 to move to just below the loading plate 9, and positioning the hopper 12 just above the briquettes; S73, pouring the spherical alumina powder into the hopper 12, and then controlling the horizontal push device 10 to push the hopper 12 to move horizontally so that the spherical alumina powder is evenly spread on the billet. The horizontal push device 10 can ensure that the hopper 12 moves horizontally at a uniform speed, so that the spherical alumina powder can be evenly spread on the billet; S74, after a layer of briquettes is spread, the motor 7 is controlled to rotate to drive the screw 5 to rotate, and the rotation of the screw 5 drives the motor 7 and the loading plate 9 to slide upward on the frame for a short distance, and then another layer of briquettes is placed on the briquettes on the flatbed trolley 15; S75, repeat S73 and S74, and finally press a support plate or a metal plate on the uppermost layer of the green blocks.

[0028] In this embodiment, if Figure 1-Figure 3As shown, the frame includes a base plate 1, a column 2, a cross bar 3, and a screw barrel 4. The lower end of the column 2 is fixedly connected to the base plate 1, the cross bar 3 is fixedly connected to the upper end of the column 2, the screw barrel 4 is vertical and fixedly connected to the cross bar 3, the screw rod 5 passes through the screw barrel 4 and is screwed to the screw barrel 4. The design of the screw barrel 4 helps the screw rod 5 to rotate smoothly; the frame also includes a slide rail 8, which is fixedly connected to the cross bar 3 and the base plate 1, and the motor 7 and the loading plate 9 are vertically slidably connected to the slide rail 8. The design of the slide rail 8 is conducive to the smooth lifting and lowering of the motor 7 and the loading plate 9.

[0029] In this embodiment, if Figure 3-Figure 4 As shown, a sliding hole 11 is provided on the carrier plate 9, and a sliding rod 13 is detachably fixedly provided on the hopper 12. The sliding rod 13 is slidably connected to the upper and lower surfaces of the carrier plate 9. The hopper 12 passes through the sliding hole 11 and is horizontally slidably connected to the carrier plate 9 through the sliding rod 13. The design of the sliding rod 13 is conducive to improving the movement stability of the carrier plate 9.

[0030] In this embodiment, if Figure 5 As shown, the discharge port of the hopper 12 is connected to a discharge pipe 17 through a connecting hose 16. The discharge pipe 17 is flat. In order to prevent the discharge flow of the hopper 12 from being too large, which may cause the thickness of the spherical alumina powder layer spread on the upper surface of the green block to be too large, resulting in waste of spherical alumina powder and affecting the sintering quality of the alumina ceramic substrate 14, a discharge pipe 17 is specially arranged at the discharge port of the hopper 12. The discharge pipe 17 has a small mouth. When the discharge pipe 17 shakes, the discharge pipe 17 discharges material. When the discharge pipe 17 does not shake, the discharge pipe 17 does not discharge material. This design can accurately control the hopper 12 to spread the spherical alumina powder on the upper surface of the green block, and avoid the spread of spherical alumina powder. The thickness of the powder layer is too large, and the opening and closing timing of the hopper 12 is accurately controlled to prevent the spherical alumina powder from falling outside the billet and causing waste. The discharge pipe 17 is provided with a vibration motor 18 and a counterweight 19. The vibration motor 18 is used to drive the discharge pipe 17 to vibrate so that the discharge pipe 17 can discharge the material. Therefore, the vibration of the discharge pipe 17 can be controlled by controlling the start and stop of the vibration motor 18. The design of the connecting hose 16 can prevent the vibration of the discharge pipe 17 from being transmitted to the hopper 12. The vibration motor 18 and the counterweight 19 are symmetrically arranged on both sides of the discharge pipe 17. With this design, the counterweight 19 can balance the center of gravity of the discharge pipe 17 to prevent the discharge pipe 17 from tilting and affecting the discharge.

[0031] The powder spreading equipment of this embodiment accurately controls the discharge of the discharge pipe 17 through the vibration motor 18, which avoids the waste of spherical alumina powder and the excessive thickness of the spherical alumina powder layer spread on the surface of the green block compared to the conventional valve, ensures that the thickness of the spherical alumina powder layer spread on the surface of the green block is uniform, and the hopper 12 can be filled with spherical alumina powder at one time, eliminating the trouble of frequently adding material to the hopper 12.

[0032] In addition, the present invention also proposes a large-size, high-flatness, high-strength alumina ceramic substrate, which is prepared by any of the aforementioned methods for preparing a large-size, high-flatness, high-strength alumina ceramic substrate.

[0033] The following is a detailed description of a method for preparing a large-size, high-flatness, and high-strength alumina ceramic substrate according to the present invention through a plurality of embodiments. Embodiment 1:

[0034] S1. Weigh 200 g of alumina powder, 0.4 g of MgO, 0.6 g of CaO, 50 g of ethanol, 30 g of toluene, and 6 g of triethyl phosphate and add them to a ball mill. Add 600 g of zirconium balls to the ball mill and perform a ball milling. S2, weighing 3g of dibutyl phthalate plasticizer and 20g of polyvinyl butyral binder, adding them to the primary slurry after the first ball milling, and performing secondary ball milling; S3, degassing the alumina tape casting slurry after the secondary ball milling, and molding and drying the treated slurry on a tape casting machine to obtain a tape casting green body; S4, subjecting the tape-cast green body to isostatic pressing in a warm isostatic press, and leaving it to stand at 25° C. for 30 days to fully release stress; S5, cutting the tape-cast green body into a square of 500 mm*500 mm, stacking the tape-cast green body, sprinkling 500 mesh spherical alumina powder between the upper and lower layers of the tape-cast green body, and pressing a 100 g setter on the top layer of the tape-cast green body; S6, debinding, sintering, grinding and polishing the stacked tape-cast green bodies to obtain an alumina ceramic substrate. Embodiment 2:

[0035] The difference between this embodiment and the first embodiment is that the weight of the setter plate is 150 g. Embodiment three:

[0036] The difference between this embodiment and the first embodiment is that the weight of the setter plate is 200 g.

[0037] Comparative Example 1: The difference between this embodiment and the first embodiment is that the spherical alumina powder is not sprinkled between the upper and lower layers of the tape-cast green bodies.

[0038] Comparative Example 2: The difference between this embodiment and the first embodiment is that the weight of the setter plate is 250 g.

[0039] The warpage of the alumina ceramic substrates prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 is shown in the following table.

[0040]

[0041] It can be seen from the above table that sprinkling spherical alumina powder between the upper and lower layers of the cast green body has a great influence on the warping and strength of the alumina ceramic substrate. In addition, it can be seen from the above table that the weight of the pressing support plate or metal plate should not be too large, otherwise the alumina ceramic substrate will be damaged.

[0042] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate, characterized in that: include: S1, adding alumina powder, solvent, dispersant, and sintering aid into a ball mill, and then adding zirconium balls into the ball mill for one ball milling to obtain a primary slurry, wherein the weight ratio of alumina powder, solvent, dispersant, sintering aid, and zirconium balls is 200:80:6:1:600; S2, adding a binder and a plasticizer to the primary slurry for secondary ball milling to obtain an alumina tape casting slurry, wherein the weight ratio of the primary slurry, the binder, and the plasticizer is 287:20:3; S3, degassing the alumina tape casting slurry; S4, tape-casting the alumina tape-casting slurry after degassing on a tape-casting machine, and drying to obtain a tape-casting green body; S5, subjecting the tape-cast green body to isostatic pressing in a warm isostatic press; S6, placing the tape-cast green body after isostatic pressing in an air environment at 25° C. for 30 days; S7, cutting the tape-cast green body that has been left to stand still into blocks of a desired size, and then stacking the blocks, sprinkling spherical alumina powder between two adjacent layers of blocks, and placing a sintering plate or a metal plate on the top layer of blocks; S8, sequentially debinding, sintering, grinding and polishing the stacked green blocks to obtain an alumina ceramic substrate.

2. The method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate according to claim 1, characterized in that: The purity of the alumina powder is ≥99.9%; The solvent is one or more of ethanol, isopropanol, methyl ethyl ketone, trichloroethylene, benzene, toluene, and xylene; The dispersant is one or more of oleic acid, triethyl phosphate, and castor oil; The sintering aid is one or more of Y2O3, MgO, SiO2, ZrO2, and CaO; The binder is polyvinyl butyral; The plasticizer is one or more of dibutyl phthalate, polyethylene glycol, and dioctyl phthalate; The debinding temperature is 500-700°C, the debinding rate is 1°C / min, and the sintering temperature is 1550-1650°C.

3. The method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate according to claim 1, characterized in that: The mesh number of spherical alumina in S7 is 300~500 mesh, the number of stacked layers of green blocks is 6~10 layers, and the weight of the pressed support plate or metal plate is 100~200g.

4. The method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate according to claim 1, characterized in that: In S7, the blocks are stacked and transported by a flatbed trolley, and spherical alumina powder is sprinkled between the upper and lower adjacent layers of blocks by a powder spreading device.

5. The method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate according to claim 4, characterized in that: The powder spreading equipment comprises: A frame, on which a screw rod is vertically mounted, and the screw rod is screwed to the frame; The motor is vertically slidably connected to the frame and is drivingly connected to the screw; The loading plate is connected to the frame for vertical sliding and is connected to the screw for rotation. A horizontal push device and a hopper are arranged on the loading plate. The hopper is connected to the horizontal push device, and the hopper is pushed to move horizontally on the loading plate through the horizontal push device.

6. The method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate according to claim 5, characterized in that: The step S7, cutting the tape-cast green body after standing still into blocks of required size, then stacking the blocks, sprinkling spherical alumina powder between two adjacent layers of blocks, and placing a sintering plate or a metal plate on the top layer of blocks, comprises: S71, cutting the tape-cast green body that has been left to stand still into blocks of required sizes; S72, placing a layer of briquettes on a flatbed trolley, pushing the flatbed trolley to move to just below the loading plate, and positioning the hopper just above the briquettes; S73, pouring spherical alumina powder into the hopper, and then controlling the horizontal push device to push the hopper to move horizontally to evenly spread the spherical alumina powder on the billet; S74, controlling the motor to rotate and drive the screw to rotate, and the screw rotation drives the motor and the carrier plate to slide upward on the frame, and then another layer of blocks is placed on the blocks on the flatbed trolley; S75, repeat S73 and S74, and finally press a support plate or a metal plate on the uppermost layer of the green blocks.

7. The method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate according to claim 5, characterized in that: The frame includes a bottom plate, a column, a cross bar, and a screw barrel. The lower end of the column is fixedly connected to the bottom plate, the cross bar is fixedly connected to the upper end of the column, the screw barrel is vertical and fixedly connected to the cross bar, and the screw rod passes through the screw barrel and is screwed to the screw barrel. The frame also includes a slide rail, which is fixedly connected to the crossbar and the bottom plate, and the motor and the loading plate are vertically slidably connected to the slide rail.

8. The method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate according to claim 5, characterized in that: The carrier plate is provided with a sliding hole, the hopper is provided with a sliding rod, the sliding rod is slidably connected to the upper and lower surfaces of the carrier plate, the hopper passes through the sliding hole, and is horizontally slidably connected to the carrier plate through the sliding rod.

9. The method for preparing a large-size, high-flatness, high-strength alumina ceramic substrate according to claim 5, characterized in that: The discharge port of the hopper is connected to a discharge pipe through a connecting hose, and a vibration motor and a counterweight are arranged on the discharge pipe, and the vibration motor and the counterweight are symmetrically arranged on both sides of the discharge pipe; The discharge pipe is flat; The material is discharged when the discharge pipe shakes, and the material is not discharged when the discharge pipe does not shake.

10. A large-size, high-flatness, high-strength alumina ceramic substrate, characterized in that: The large-size, high-flatness and high-strength alumina ceramic substrate is prepared by the preparation method of any one of claims 1 to 9.

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