Ceramic substrate, method for manufacturing the same, and use thereof

Abstract

The application discloses a ceramic substrate and a preparation method and application thereof, and relates to the technical field of ceramic substrate processing and treatment; the preparation method of the ceramic substrate comprises the following steps: ceramic powder with a particle size of 0.1-10 mu m is taken, mixed with water-based suspension liquid in which a binder and a plasticizer are suspended and dispersed, and prepared into a casting slurry, and then the casting slurry is cast into a green sheet; the green sheet is subjected to sulfurization pressing by using a 100-400 mesh grid, and a grid-textured green sheet with a surface printed with a grid pattern is obtained; and the grid-textured green sheet is subjected to normal-pressure sintering, and the ceramic substrate is obtained.The preparation method of the application is prepared by using ceramic powder with a wide particle size distribution, and is beneficial to improving the surface roughness; meanwhile, the grid-textured green sheet is obtained by grid sulfurization pressing, and the pressure maintaining time is optimized; after normal-pressure sintering, the surface roughness of the ceramic substrate can be effectively improved, the combination of copper and the ceramic substrate is more compact, and the peeling strength of the copper foil can be effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic substrate processing, and more particularly to a ceramic substrate and a preparation method and application thereof. Background Art

[0002] Ceramic substrates have the advantages of sufficiently high mechanical strength, low dielectric constant, low thermal expansion coefficient, high thermal conductivity, good chemical stability, etc., and have become an important basic material in the fields of electronic circuit structure technology and interconnection technology.

[0003] Ceramic substrates often need to be covered with copper on the surface, and corresponding patterns can be etched according to the circuit design or product structure. However, the material properties of ceramic substrates and copper foil are quite different. To ensure the close bonding of copper and ceramic, high requirements are placed on the surface roughness of the ceramic substrate. At present, the processing methods for improving the surface roughness of ceramic substrates mainly include sandblasting and grinding. Among them, for sandblasting, 30-150 mesh white corundum sand, corundum or silicon carbide sand are usually selected, and the surface of the ceramic sheet is sandblasted by a sandblasting machine to increase its roughness. For grinding, 30-150 mesh white corundum sand, corundum or silicon carbide sand are usually selected, and the surface of the ceramic sheet is ground by a grinder to increase its roughness. However, the operation of the above methods is relatively complicated and the production efficiency is low.

[0004] Prior art proposes a raw material preparation method and equipment for preventing delamination during soldering of silicon nitride integrated circuit boards. This method involves adding texture to the ceramic surface. During grinding of the mixed material, the ceramic surface is pretreated, etching 0.05-0.1mm textures on the ceramic surface. The textures are inclined at a 45-degree angle, with a spacing of 2-3mm between the textures. The textures are then aligned perpendicularly to the textures, forming a grid pattern. After sandblasting, the surface roughness reaches Ra 0.2-0.5. While this method physically textures the silicon nitride ceramic substrate, increasing the contact area, it still requires sandblasting to meet the roughness requirements. This method fails to ensure uniformity of the overall surface roughness of the ceramic, failing to achieve both improved surface roughness and uniformity. Summary of the Invention

[0005] The purpose of the present invention is to overcome the process defects and shortcomings of existing ceramic substrates that fail to achieve both high surface roughness and uniformity, and to provide a method for preparing a ceramic substrate.

[0006] Another object of the present invention is to provide a ceramic substrate obtained by the above preparation method.

[0007] Another object of the present invention is to provide an application of the above-mentioned ceramic substrate in the preparation of a circuit board.

[0008] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0009] The present invention provides a method for preparing a ceramic substrate, comprising the following steps:

[0010] S1, taking ceramic powder with a particle size of 0.1-10 μm, mixing it with an aqueous suspension containing a binder and a plasticizer, and preparing a casting slurry, and performing tape casting to obtain a green sheet;

[0011] S2, vulcanizing and pressing the green sheet using a 100-400 mesh grid, with a holding time of 10-60 seconds and a pressure of 5-40 MPa to obtain a textured green sheet with a texture printed on the surface;

[0012] S3, sintering the textured green sheet under normal pressure to obtain the ceramic substrate.

[0013] The ceramic substrate of the present invention is prepared using ceramic powder with a wide particle size distribution to improve surface roughness. An aqueous suspension is also added, where organic particles can adsorb smaller-sized ceramic powder, achieving uniform particle size and significantly improving dispersibility. The resulting green sheet exhibits both high surface roughness and uniformity. Furthermore, a mesh pattern is formed using a grid-like vulcanization press, and the dwell time is optimized. After atmospheric pressure sintering, the surface roughness of the ceramic substrate is effectively increased, resulting in a tighter bond between the copper and the ceramic substrate and improved peel strength of the copper foil. The clear and uniform pattern ensures accurate replication of the circuit design or product structure during etching, thereby guaranteeing circuit performance and stability.

[0014] Among them, the mesh should be 100-400 mesh, and the material can be selected from nylon mesh or steel mesh; the higher the mesh number, the smaller the roughness, and when the mesh number is too high, the mesh and the blank are easy to stick together, making processing difficult.

[0015] Preferably, the pressure is 10-30 MPa, under which the embossing effect is good and the roughness is high.

[0016] Preferably, the holding time is within the range of 10-60s. When the pressing time is short, the mesh is shallow and the roughness is low. When the pressing time is too long, the mesh may be distorted, deformed, and the texture may be uneven.

[0017] In some embodiments, in step S1, the ceramic powder material having a median particle size of 3-4 μm accounts for 60%-80% of the total weight of the ceramic powder material, the powder material having a median particle size of 0.1-2 μm accounts for 10%-20% of the total weight of the ceramic powder material, and the powder material having a median particle size of 5-10 μm accounts for 10%-20%. By using and optimizing the segmented particle sizes, the surface roughness of the product is effectively improved.

[0018] In some embodiments, in step S2, the temperature of the vulcanization pressing is 40-70° C. and the pressure is 10-30 MPa.

[0019] In some embodiments, in step S1, the casting slurry includes the following components in percentage by mass:

[0020]

[0021]

[0022] The ceramic powder comprises aluminum oxide powder with a mass fraction of not less than 95%.

[0023] In some embodiments, the ceramic powder comprises, by mass percentage, 95%-97% alumina powder, 1%-2% flow agent, and 2%-4% sintering aid, wherein the alumina powder is non-spherical or irregularly shaped.

[0024] Non-spherical or irregularly shaped powders with a wide particle size distribution can be stacked in a manner that fills each other during the molding process, which is conducive to forming a more compact stacking structure. During sintering, the particles are in close contact, providing more contact points, which is conducive to diffusion and sintering between particles. Non-spherical or irregularly shaped powders have high sintering activity, thereby reducing the sintering temperature, increasing the sintering speed and sintering density, and further improving the mechanical strength of the ceramic substrate. A wide particle size distribution can lead to poor fluidity of the powder, and the biggest disadvantage of non-spherical or irregularly shaped powders is also poor fluidity. The present invention improves the fluidity of the powder by adding a certain proportion of a flow agent to the powder. The flow agent is an inorganic oxide, including but not limited to spherical silica, alumina, zirconia, etc., to improve the fluidity of the powder, that is, to improve the fluidity of the casting slurry.

[0025] Preferably, the sintering aid is one or more of magnesium oxide, silicon oxide, calcium carbonate, lanthanum oxide, yttrium oxide or zinc oxide.

[0026] In some embodiments, the binder is selected from polyvinyl butyral (PVB) and / or polymethyl methacrylate (PMMA).

[0027] In some embodiments, the plasticizer is selected from one or a combination of two or more of dibutyl phthalate (DBP), dioctyl phthalate (DOP), epoxidized soybean oil, tricresyl phosphate, triphenyl phosphate, dioctyl sebacate or chlorinated paraffin.

[0028] In some embodiments, the solvent is selected from a benzene solvent, a ketone solvent or an alcohol solvent.

[0029] Preferably, the solvent is selected from butanone or a combination of isopropanol and ethanol.

[0030] In some embodiments, the casting slurry has a viscosity of 15,000-25,000 cp at 25°C.

[0031] In some embodiments, the casting slurry is prepared by mixing ceramic powder, dispersant and solvent and ball milling for 15-25 hours, then adding aqueous suspension and ball milling for a second time for 15-20 hours, and vacuum degassing to obtain the casting slurry.

[0032] In some embodiments, the aqueous suspension is prepared by dispersing PVB and DOP in an aqueous phase; the inventors have found that the use of ceramic powder with a wide particle size distribution can improve the roughness of the ceramic substrate, but ceramic powder with a smaller particle size is very prone to sedimentation in the tape casting slurry system, and due to the high viscosity of PVB and DOP, it is difficult for the ceramic powder to be mixed evenly therein, resulting in extremely poor roughness uniformity of the ceramic substrate. The present invention prepares an aqueous suspension of PVB and DOP first, and then uses the aqueous suspension of PVB and DOP to prepare the tape casting slurry. The form of the aqueous phase is conducive to mixing with the ceramic powder, and the suspended aqueous suspension of PVB and DOP is mixed with the ceramic fine powder, so that the ceramic fine powder adheres to the binder and plasticizer particles to form larger particles, which have a gravity equivalent to that of the ceramic powder with a larger particle size and can be simultaneously suspended and dispersed in the tape casting slurry, thereby improving the stability and uniformity of the slurry and improving the quality of the tape casting green body. If PVB and DOP are measured and added directly to the slurry, the stability and uniformity of the slurry will be improved, and the quality of the tape-cast green body will be improved.

[0033] Preferably, the preparation method of the casting slurry is: 10%-40wt% alumina powder, a sintering aid, a dispersant and a solvent are mixed and ball-milled for 5-10 hours, and then the remaining amount of alumina powder is added and ball-milled for 10-15 hours, and then a binder and a plasticizer aqueous dispersion are added and ball-milled for a second time for 15-20 hours, and vacuum degassing is performed to obtain the casting slurry.

[0034] Adding alumina powder in two stages can reduce agglomeration, achieve better dispersion, and optimize the morphology and size of powder particles, transforming sharp-edged particles into relatively smooth spherical or quasi-spherical shapes, improving molding performance. Furthermore, it can reduce energy consumption during the ball milling process and improve production efficiency.

[0035] In some embodiments, the aqueous suspension is prepared by adding a binder and a plasticizer to an organic solvent, stirring at 50-80°C until dissolved, adding a suspending dispersion, rapidly cooling to 0-15°C, extracting to remove the organic solvent, and separating to obtain the aqueous suspension.

[0036] Optionally, the suspension dispersion is an aqueous solution containing 0.01-1 wt% of a surfactant; preferably, the surfactant is a polyoxyethylene ether nonionic surfactant, and more preferably, the surfactant is nonylphenol polyoxyethylene ether (Nonal 912A), with a content of 0.5 wt%.

[0037] In some embodiments, in step S3, the sintering temperature of the pressureless sintering is 1600-1630° C., and the holding time is 4-6 hours.

[0038] The invention protects a ceramic substrate with high surface roughness, which is made by a preparation method of the ceramic substrate.

[0039] In some embodiments, the surface roughness of the ceramic substrate is 0.3-3 μm.

[0040] The present invention protects the application of a ceramic substrate with high surface roughness in the preparation of a circuit board.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The present invention provides a method for preparing a ceramic substrate. The method utilizes ceramic powder with a wide particle size distribution to improve surface roughness. Simultaneously, an aqueous suspension is added, wherein the organic particles in the suspension can adsorb ceramic powder with smaller particle sizes, achieving uniform particle size and significantly improving dispersibility. The resulting green sheet exhibits high surface roughness and uniformity. Furthermore, a mesh pattern is formed by grid vulcanization pressing, and the dwell time is optimized. After atmospheric pressure sintering, the surface roughness of the ceramic substrate is effectively improved, resulting in a tighter bond between the copper and the ceramic substrate, effectively enhancing the peel strength of the copper foil and facilitating large-scale production. Furthermore, the clear and uniform mesh pattern ensures that the circuit design or product structure is accurately replicated during the etching process, thereby guaranteeing circuit performance and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a surface topography of a ceramic substrate with high surface roughness in Example 5 of the present invention.

[0044] Figure 2 This is a surface morphology diagram of the ceramic substrate with high surface roughness in Comparative Example 2 of the present invention.

[0045] Figure 3 For the present invention Figure 1 The results of the surface roughness test of a high surface roughness ceramic substrate. DETAILED DESCRIPTION

[0046] The present invention will be further described below in conjunction with specific embodiments, but the examples do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the examples of the present invention are conventionally purchased raw materials and reagents.

[0047] Example 1

[0048] A method for preparing a ceramic substrate comprises the following steps:

[0049] S1, taking ceramic powder with a particle size of 0.1-10 μm, mixing it with an aqueous suspension in which a binder and a plasticizer are suspended and dispersed, and preparing a casting slurry, and performing tape casting to obtain a green sheet.

[0050] S2, after the green sheet is punched into sheets according to the required size by a sheet punching machine, the green sheet is vulcanized and pressed using a 200-mesh grid with a holding time of 10 seconds to obtain a textured green sheet with a texture printed on the surface;

[0051] S3, sending the textured green sheet into a tunnel kiln for normal pressure sintering at a sintering temperature of 1620° C., a holding time of 5 hours, and a pushing speed of 40 min / push, thereby obtaining the ceramic substrate.

[0052] Specifically, step S1 includes:

[0053] (1) Slurry raw materials

[0054] The casting slurry includes the following components in percentage by mass:

[0055]

[0056] The ceramic powder comprises 96% alumina powder and 4% sintering aid. The alumina powder is non-spherical or irregularly shaped. The sintering aid is selected from magnesium oxide, silicon oxide, calcium carbonate, lanthanum oxide, yttrium oxide, and zinc oxide.

[0057] Furthermore, the ceramic powder with a median diameter of 3-4 μm accounts for 70% of the total weight of the ceramic powder, the powder with a median diameter of 0.1-2 μm accounts for 20% of the total weight of the ceramic powder, and the powder with a median diameter of 5-10 μm accounts for 10% of the total weight of the ceramic powder.

[0058] The dispersant is selected from castor oil phosphate.

[0059] The binder is selected from polyvinyl butyral (PVB).

[0060] The plasticizer is selected from dioctyl phthalate (DOP).

[0061] The solvent is selected from butanone and ethanol in a mass ratio of 1:1.

[0062] (2) Casting slurry preparation

[0063] 1) Preparing an aqueous suspension of PVB and DOP: Add an organic solvent (toluene) to a reaction vessel, add PVB and DOP to the reaction vessel, and add the PVB and DOP to a total volume ratio of 50% of the organic solvent. Heat the mixture to 65°C and stir until dissolved to obtain an organic mixed solution. Then, add a suspending dispersion in an amount of 5 times the amount of the organic mixed solution. The suspending dispersion is an aqueous solution containing 0.5 wt% of a surfactant, nonylphenol polyoxyethylene ether (Nonal 912A).

[0064] The organic mixed solution is transferred to a receiving kettle by rapid cooling. The temperature within the receiving kettle is lower than the lowest boiling point of the organic solvents, in this embodiment, the temperature within the receiving kettle is 8°C. The receiving kettle is evacuated to create a negative pressure, and the organic mixed solution is sprayed into the receiving kettle using an ejector.

[0065] The organic solvent in the material is removed by using an extractant until the content of the organic solvent in the solution is less than 1 wt %, thereby obtaining an aqueous suspension of PVB particles and DOP particles; wherein the extraction temperature is 30° C.; and the extraction solvent is preferably chloroform.

[0066] 2) Ball milling and dispersion of raw materials: Alumina powder, magnesium oxide powder, silicon oxide powder, calcium carbonate powder, lanthanum oxide powder, yttrium oxide powder, zinc oxide powder, solvent (methyl ethyl ketone and ethanol), and dispersant (25% by weight of the total weight of the alumina powder) were added to a ball mill and pre-milled for 8 hours. The remaining amount of alumina powder was then added and ball-milled for 12 hours. The above-mentioned PVB and DOP aqueous dispersion was then added and ball-milled for a second time for 18 hours.

[0067] Due to the poor compatibility between water and organic additives and the problem that powders with a wide particle size distribution are very prone to sedimentation in the casting slurry, the aqueous suspension of PVB and DOP prepared in this embodiment can enable the fine ceramic powder to adhere to the PVB and DOP particles in the subsequent steps to form larger particles. The gravity is equivalent to that of the larger ceramic powder particles, and they can be suspended and dispersed in the slurry at the same time, greatly improving the uniformity of the dispersion.

[0068] (3) The material was discharged from the ball mill and vacuum degassed to obtain a casting slurry with a viscosity of 20,000 cp.

[0069] (4) The casting slurry is cast into a green body by casting.

[0070] Step S2 includes placing the green sheet on a vulcanizer, with nylon mesh of 200 mesh placed on both the upper and lower surfaces. The sheet is pressed to form textures on both the upper and lower surfaces. The vulcanizer is vulcanized for 10 seconds at a temperature of 50°C and a pressure of 15 MPa.

[0071] Furthermore, this embodiment adopts a lamination process, and the operation is: take 5 pieces of green sheets, place nylon mesh on the top and bottom and between the layers in sequence, and then move them to a flat workbench. After vulcanization and pressing, the texture on the top and bottom of the green sheets is more uniform and consistent.

[0072] Examples 2-5

[0073] The method for preparing a ceramic substrate in Examples 2-5 is different from that in Example 1 in that the holding times in Examples 2-5 are 20s, 30s, 40s, and 50s, respectively.

[0074] Examples 6-10

[0075] The method for preparing a ceramic substrate in this embodiment is different from that in Example 1 in that the median diameter of the ceramic powder is selected differently.

[0076] Example 6: The ceramic powder with a median diameter of 3-4 μm accounts for 60% of the total weight of the ceramic powder, the powder with a median diameter of 0.1-2 μm accounts for 20% of the total weight of the ceramic powder, and the powder with a median diameter of 5-10 μm accounts for 20% of the total weight of the ceramic powder;

[0077] Example 7: The ceramic powder with a median diameter of 3-4 μm accounts for 80% of the total weight of the ceramic powder, the powder with a median diameter of 0.1-2 μm accounts for 10% of the total weight of the ceramic powder, and the powder with a median diameter of 5-10 μm accounts for 10% of the total weight of the ceramic powder;

[0078] Example 8: The ceramic powder with a median diameter of 3-4 μm accounts for 70% of the total weight of the ceramic powder, the powder with a median diameter of 0.1-2 μm accounts for 15% of the total weight of the ceramic powder, and the powder with a median diameter of 5-10 μm accounts for 15% of the total weight of the ceramic powder.

[0079] Example 9: The ceramic powder with a median diameter of 3-4 μm accounts for 90% of the total weight of the ceramic powder, and the powder with a median diameter of 0.1-2 μm accounts for 10% of the total weight of the ceramic powder.

[0080] Example 10: The ceramic powder with a median diameter of 3-4 μm accounts for 50% of the total weight of the ceramic powder, the powder with a median diameter of 0.1-2 μm accounts for 35% of the total weight of the ceramic powder, and the powder with a median diameter of 5-10 μm accounts for 15% of the total weight of the ceramic powder.

[0081] Examples 11-14

[0082] The method for preparing a ceramic substrate of this embodiment is different from that of Embodiment 1 in that the pressures in the sulfurization pressing in step S2 are 5 MPa, 10 MPa, 20 MPa and 40 MPa respectively.

[0083] Examples 15-17

[0084] The method for preparing a ceramic substrate of this embodiment is different from that of embodiment 1 in that: in step S2, the mesh sizes of the grids are 100 mesh, 300 mesh, and 400 mesh.

[0085] Comparative Example 1-2

[0086] The method for preparing a ceramic substrate in this comparative example is different from that in Example 1 in that the holding times in this comparative example are 100 s and 200 s respectively.

[0087] Comparative Example 3

[0088] The method for preparing a ceramic substrate in this comparative example is different from that in Example 1 in that it includes the following steps:

[0089] S1, prepare ceramic powder with a particle size of 0.1-10 μm into a casting slurry, cast it through a casting machine, and dry it to obtain a green sheet.

[0090] S2, sending the green sheet into a tunnel kiln for normal pressure sintering at a sintering temperature of 1620° C., a holding time of 5 hours, and a pushing speed of 40 min / push, thereby obtaining the ceramic substrate.

[0091] Comparative Example 4

[0092] The method for preparing a ceramic substrate in this comparative example is different from that in Example 1 in that equal amounts of PVB and DOP are directly measured and added into the slurry.

[0093] Performance Testing

[0094] 1. Surface roughness test

[0095] 1.1. Influence of holding time on roughness

[0096] The surface roughness of the samples of Examples 1-5 and Comparative Examples 1-2 at different holding times was tested using a surface roughness meter to observe the effect of holding time on the roughness. The results are shown in Table 1.

[0097] Table 1

[0098]

[0099]

[0100] As can be seen from Table 1, within the holding time (10-60s) of the present invention, the roughness reaches 0.456-0.853 μm, and the roughness increases with the increase of the holding time; in Comparative Examples 1-2, the holding time is too long, the reticulation has obvious deformation, the texture is uneven, and even with a higher roughness, it cannot meet the use requirements.

[0101] like Figure 1 As shown in FIG, within the holding time range of the vulcanization pressing of the present invention, the surface texture of the obtained product is uniform and clear; Figure 2 As shown, the holding time (200s) of the product of Comparative Example 2 is too long, and the texture on the surface of the green sheet is mixed and blurred.

[0102] like Figure 3 As shown, after testing with a surface roughness meter, the roughness of the fine screen-printed ceramic sheet of Example 5 is 0.847 μm.

[0103] 1.2. Influence of powder particle size and particle size distribution on roughness

[0104] The surface roughness of the samples of Examples 6-8 and Comparative Example 3 was tested using a surface roughness meter to observe the effect of powder particle size (median diameter) on the roughness. The results are shown in Table 2.

[0105] Table 2

[0106]

[0107] As can be seen from Table 2, the present invention can improve the surface roughness of the product by using ceramic powder with a wider particle size distribution. Among them, the surface roughness of the ceramic powders of Examples 1, 6-8 is higher after the particle size distribution is optimized. When the particle size distribution of Examples 9 and 10 is more concentrated or more dispersed, the surface roughness is reduced.

[0108] 1.3. Effect of pressing force on roughness

[0109] The surface roughness of the samples of Examples 11-14 was tested using a surface roughness meter to observe the effect of powder particle size on the roughness. The results are shown in Table 3.

[0110] Table 3

[0111]

[0112] It can be seen from Table 3 that as the vulcanization pressing force increases, the roughness increases. However, when the pressing force is too large, it is easy to cause deformation of the texture.

[0113] 1.4. Effect of mesh size on roughness

[0114] The surface roughness of the samples of Examples 15-17 was tested using a surface roughness meter to observe the effect of the mesh size on the roughness. The results are shown in Table 4.

[0115] Table 4

[0116]

[0117] It can be seen from Table 4 that as the mesh number of the grid increases, the surface roughness decreases; and if the mesh number of the grid is too large or too small, it will cause the deformation of the texture.

[0118] 1.5. Effect of the addition method of binder and plasticizer on roughness

[0119] Compared with Example 1, in Comparative Example 4, equal amounts of PVB and DOP were directly measured and added to the slurry.

[0120] The results show that the surface roughness distribution of Comparative Example 4 treated at 15 MPa for 10 seconds is very uneven, with a minimum roughness of 0.124 μm and a maximum roughness of 4.256 μm, which cannot meet the use requirements.

[0121] 2. Peel strength test

[0122] The peel strength test of the ceramic substrate samples of Examples 1-5 and Comparative Example 2 was performed, and the results are shown in Table 5.

[0123] Experimental method: The present invention uses a 90° peel tester to test. A force parallel to the bonding surface is applied to the interface between the metal foil and the ceramic substrate to separate the two. The peel force per unit area when the metal foil and the ceramic substrate are separated is the peel strength.

[0124] Table 5

[0125]

[0126] As can be seen from Table 2, the high-surface-roughness ceramic substrate of the present invention has a greater peel strength, and the greater the roughness, the greater the peel strength, and the tighter the copper-ceramic bond. The ceramic substrate of Comparative Example 3, whose surface was not pressed to form a reticulated pattern, has a lower roughness and a lower average peel strength.

[0127] The above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications may be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a ceramic substrate, characterized in that: The following steps are involved: S1, taking ceramic powder with a particle size of 0.1-10 μm, mixing it with an aqueous suspension containing a binder and a plasticizer, and preparing a casting slurry, and performing tape casting to obtain a green sheet; The ceramic powder material has a median particle size of 3-4 μm accounting for 60%-80% of the total weight of the ceramic powder material, the powder material has a median particle size of 0.1-2 μm accounting for 10%-20% of the total weight of the ceramic powder material, and the powder material has a median particle size of 5-10 μm accounting for 10%-20% of the total weight of the ceramic powder material; The viscosity of the casting slurry at 25° C. is 15,000-25,000 cp; S2, vulcanizing and pressing the green sheet using a 100-400 mesh grid, with a holding time of 10-60 seconds and a pressure of 5-40 MPa to obtain a textured green sheet with a texture printed on the surface; S3, sintering the textured green sheet under normal pressure to obtain the ceramic substrate.

2. The method for preparing a ceramic substrate according to claim 1, wherein: In step S2, the temperature of the vulcanization pressing is 40-70°C.

3. The method for preparing a ceramic substrate according to claim 1, wherein: In step S1, the casting slurry includes the following components in percentage by mass: Ceramic powder 55-70%, Dispersant 1-2%, Binder 5-10%, Plasticizer 2-5%, Solvent 22-28%; The ceramic powder comprises aluminum oxide powder with a mass fraction of not less than 95%.

4. The method for preparing a ceramic substrate according to claim 3, wherein: The preparation method of the tape casting slurry is as follows: ceramic powder, dispersant and solvent are mixed and dispersed by ball milling for 15-25 hours, then aqueous suspension is added and ball milled for a second time for 15-20 hours, and vacuum degassing is performed to obtain the tape casting slurry.

5. The method for preparing a ceramic substrate according to claim 4, wherein: The aqueous suspension is prepared by adding a binder and a plasticizer to an organic solvent, stirring at 50-80° C. until dissolved, adding a suspension dispersion, cooling to 0-15° C., extracting and removing the organic solvent, and separating to obtain the aqueous suspension; the suspension dispersion is an aqueous solution containing 0.01-1 wt % of a surfactant.

6. A ceramic substrate, characterized in that: The ceramic substrate is made by the preparation method of any one of claims 1 to 5.

7. The ceramic substrate according to claim 6, wherein: The surface roughness of the ceramic substrate is 0.3-3 μm.

8. Use of the ceramic substrate according to claim 6 or 7 in the preparation of a circuit board.

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