Preparation method of aluminum oxide ceramic substrate

Abstract

The invention relates to the technical field of ceramic substrates, in particular to a preparation method of an aluminum oxide ceramic substrate, which comprises the following steps: step 1, mixing and refining aluminum oxide powder and a fluxing agent to obtain mixed powder, the aluminum oxide powder comprising first aluminum oxide powder and second aluminum oxide powder; 2, adding the mixed powder, a binder, a plasticizer, a sintering aid and a dispersing agent into a mixed solvent, uniformly mixing, carrying out ball milling treatment, and then sufficiently defoaming and aging to obtain slurry; 3, uniformly coating a PET film with the slurry, and then carrying out three-stage drying to obtain a blank belt; 4, the blank strip is subjected to rolling and die punching in sequence, and a blank sheet is obtained; and step 5, sintering the blank piece at 1500-1550 DEG C to obtain the ceramic substrate. Two kinds of aluminum oxide powder with different particle sizes are used, and the sintering aid Y2O3 is added, so that the mechanical property of the ceramic substrate with the aluminum oxide content of 98% is improved while the sintering temperature is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic substrates, and in particular to a method for preparing an alumina ceramic substrate. Background Art

[0002] A ceramic substrate is a thin sheet made of ceramic material. Common materials include aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), etc. Ceramic substrates usually have a flat surface and are used to connect and support microelectronic components. They are key materials in the manufacture of electronic components. Ceramic substrates have excellent mechanical, thermal and electrical properties and are widely used in consumer electronics, low-end industrial and home appliances, and automotive electronics. In recent years, with the rapid development of high-tech fields such as electronic information technology, new energy, and aerospace, various fields have put forward higher requirements on the performance of ceramic substrates. High-performance ceramic substrates have become one of the core materials supporting high-power devices, high-frequency communications, and high-temperature environment applications, and their status in modern industry is becoming increasingly important.

[0003] Alumina ceramic substrates, as the most mature and widely used material system among ceramic substrates, offer advantages over aluminum nitride and silicon nitride ceramic substrates, such as low raw material costs and high compatibility with metallization processes. Ceramic substrates with a 98% alumina content (98 ceramics) have low impurity ion concentrations and excellent high-temperature stability. However, high-purity alumina has a high melting point, typically requiring higher sintering temperatures to promote diffusion and bonding between particles, forming a dense structure. Higher sintering temperatures not only increase energy consumption but also lead to abnormal grain growth. Existing technologies generally use a MgO-SiO2-CaO additive system to lower the sintering temperature. However, this MgO-SiO2-CaO additive system tends to form a low-viscosity liquid phase, which reduces the mechanical properties of the ceramic substrate. Summary of the Invention

[0004] To address the technical problem of decreased mechanical properties of ceramic substrates with an alumina content of 98% at low sintering temperatures, the present invention provides a method for preparing an alumina ceramic substrate. The method uses alumina powders of two different particle sizes and adds a sintering aid, Y2O3, to reduce the sintering temperature while improving the mechanical properties of the ceramic substrate with an alumina content of 98%.

[0005] The technical solutions of the present invention are as follows: A method for preparing an alumina ceramic substrate comprises the following steps: Step 1: mixing and refining the alumina powder and the flux to obtain a mixed powder, wherein the alumina powder includes a first alumina powder and a second alumina powder, wherein the particle size of the first alumina powder is 1.8±0.2 μm, and the particle size of the second alumina powder is 0.8±0.2 μm; Step 2: adding the mixed powder, binder, plasticizer, sintering aid and dispersant to a mixed solvent of toluene and isopropyl alcohol, mixing them evenly and then ball milling them, and then fully degassing and aging them to obtain a slurry, wherein the sintering aid is Y2O3; Step 3: Evenly apply the slurry onto the PET film, and then perform three-stage drying to obtain a blank strip; Step 4: Roll and punch the blank strip in sequence to obtain a blank sheet; Step 5: The green sheet is sintered at 1500-1550°C to obtain a ceramic substrate with an alumina content of 98%.

[0006] Furthermore, in step one, the flux includes MgO, SiO2 and CaO, wherein the mass ratio of MgO, SiO2 and CaO is 0.4-1.6:1-3:0.1-0.7, preferably 0.9:1.6:0.5, and the ratio of the mass of the flux to the mass of the mixed powder is 1.5%.

[0007] Furthermore, in step 1, the alumina powder includes 50%-80% by mass of the first alumina powder and 20%-50% by mass of the second alumina powder.

[0008] Furthermore, in step 2, the binder is at least one of polyvinyl butyral, polyvinyl alcohol and paraffin; the plasticizer is at least one of dibutyl phthalate, dimethyl phthalate and diethyl phthalate; and the dispersant is at least one of glyceride, fatty acid ester, polyethyleneimine and polymethacrylic acid.

[0009] Furthermore, in step 2, the mass of the binder is 5%-9% of the mass of the mixed powder; the mass of the plasticizer is 2%-6% of the mass of the mixed powder; the mass of the sintering aid is 0.3% of the mass of the mixed powder; the mass of the dispersant is 0.5%-3% of the mass of the mixed powder; and the mass of the mixed solvent is 40%-60% of the mass of the mixed powder.

[0010] Furthermore, in step 2, the mass ratio of toluene to isopropanol in the mixed solvent is 3-6:9-13, preferably 5:10.5.

[0011] Furthermore, in step three, before the slurry is evenly coated on the PET film, the slurry is filtered using a cartridge filter.

[0012] Furthermore, in step three, the coating thickness of the slurry is 0.4-0.5 mm, and the temperatures of the three-stage drying are 30-60° C., 50-80° C., and 70-100° C. in chronological order.

[0013] Furthermore, in step 4, the blanks are sequentially powdered, dried, and waxed. The powdering can separate adjacent blanks in a stack of blanks to prevent them from sticking together.

[0014] Furthermore, the method further includes step six: sandblasting and re-drying the surface of the ceramic substrate, wherein the water pressure of the sandblasting is 0.1-1 MPa and the temperature of the re-drying is 120±3°C.

[0015] The beneficial effects of the present invention are: The present invention provides a method for preparing an alumina ceramic substrate. The method comprises the following steps: mixing and refining a first alumina powder with a particle size of 1.8±0.2 μm and a second alumina powder with a particle size of 0.8±0.2 μm with a flux; and filling the intergranular spaces between the first alumina powder with a particle size of 1.8±0.2 μm with the second alumina powder with a particle size of 0.8±0.2 μm, thereby achieving close stacking between coarse particles and fine particles and improving the flexural strength of the ceramic substrate. The mixed powder, a binder, a plasticizer, a sintering aid, and a dispersant are added to a mixed solvent of toluene and isopropyl alcohol, which is beneficial for uniform dispersion of the mixed powder and reduction of agglomerate size. Since toluene and isopropyl alcohol can form an azeotropic system, the mixed solvent evaporates more evenly during a drying process, which is beneficial for reducing microcracks and pinholes. By using a small amount of a sintering aid Y2O3, the mechanical properties of the ceramic substrate are further improved while reducing the sintering temperature. The slurry is evenly coated on a PET film and then dried in three stages, using a gradient temperature increase method to reduce residual internal stress of the green strip. DETAILED DESCRIPTION

[0016] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present invention.

[0017] Example 1 A method for preparing a ceramic substrate with an aluminum oxide content of 98%, comprising the following steps: Step 1: Place the alumina powder and flux in an ultrafine blender for mixing and refining to obtain a mixed powder. In the mixed powder, the mass percentage of alumina powder is 98.5%, and the mass percentage of flux is 1.5%. In terms of mass percentage, the alumina powder includes 70% of a first alumina powder and 30% of a second alumina powder. The particle size of the first alumina powder is 1.8±0.2μm, and the particle size of the second alumina powder is 0.8±0.2μm. The flux includes MgO, SiO2, and CaO, wherein the mass ratio of MgO, SiO2, and CaO is 0.9:1.6:0.5.

[0018] Step 2: Add the mixed powder, polyvinyl butyral (PVB), dibutyl phthalate (DBP), Y2O3, and glycerol to a mixed solvent of toluene and isopropyl alcohol, mix thoroughly, and transfer to a ball mill for milling. The mixture is then fully degassed and aged to obtain a slurry. The mass of PVB is 5% of the mass of the mixed powder; the mass of DBP is 5% of the mass of the mixed powder; the mass of Y2O3 is 0.3% of the mass of the mixed powder; the mass of glycerol is 1% of the mass of the mixed powder; and the mass of the mixed solvent is 50% of the mass of the mixed powder. The mass ratio of toluene to isopropyl alcohol in the mixed solvent is 5:10.5.

[0019] Step 3: Filter the slurry using a cartridge filter to remove small impurities. The filtered slurry is then directed into a hopper, where it is evenly coated onto the PET film. The slurry's thickness is controlled at 0.45mm during the casting process by precisely adjusting the scraper height. The casting speed is 0.5m / min. The slurry is then dried in three stages. The curing temperatures are, in chronological order, as follows: 30-60°C in the first zone, 50-80°C in the second zone, and 70-100°C in the third zone. During the drying process, the slurry gradually solidifies to form a green ribbon.

[0020] Step 4: The strips obtained in Step 3 are wound together as they pass through the rewinding device at the end of the tape casting machine, forming a roll. The roll is then unrolled and placed on the workbench of a stamping press. A die with a specialized blade structure installed on the press shears and creases the strips to produce sheets. The sheets are then powdered, dried, and waxed.

[0021] Step 5: Place the green sheet in a main firing furnace at 1515±10℃. Under high temperature, the green sheet undergoes a sintering process, and the particles gradually fuse to form a dense and hard ceramic substrate.

[0022] Step 6: Use a high-pressure sandblaster to sandblast and clean the surface of the ceramic substrate, followed by re-drying to obtain the ceramic substrate product. The water pressure for sandblasting is 0.1-1MPa, and the re-drying temperature is 120±3°C. A warpage test is used to test the flatness of the ceramic substrate product. If the ceramic substrate product passes through a marble plate with a certain gap on the warpage tester under its own weight, the surface flatness is qualified. Ceramic substrates that fail to meet the flatness requirements are stacked and heated and softened at 1430±5°C in a flattening furnace under their own weight to improve warpage. A coloring machine is used to apply red or blue ink to one side of a sample of a ceramic substrate product that meets the flatness requirements. If a surface defect or crack is present on the sample, the ink will appear linearly on the other side, forming a surface defect mark. Defects can be detected by observing water penetration on the surface of the ceramic substrate product.

[0023] Example 2 A method for preparing a ceramic substrate with an aluminum oxide content of 98%, comprising the following steps: Step 1: Place the alumina powder and flux in an ultrafine blender for mixing and refining to obtain a mixed powder. In the mixed powder, the mass percentage of alumina powder is 98.5%, and the mass percentage of flux is 1.5%. In terms of mass percentage, the alumina powder includes 80% of a first alumina powder and 20% of a second alumina powder. The particle size of the first alumina powder is 1.8±0.2μm, and the particle size of the second alumina powder is 0.8±0.2μm. The flux includes MgO, SiO2, and CaO, wherein the mass ratio of MgO, SiO2, and CaO is 0.9:1.6:0.5.

[0024] Step 2: Add the mixed powder, polyvinyl butyral (PVB), dibutyl phthalate (DBP), Y2O3, and glycerol to a mixed solvent of toluene and isopropyl alcohol, mix thoroughly, and transfer to a ball mill for milling. The mixture is then fully degassed and aged to obtain a slurry. The mass of PVB is 5% of the mass of the mixed powder; the mass of DBP is 5% of the mass of the mixed powder; the mass of Y2O3 is 0.3% of the mass of the mixed powder; the mass of glycerol is 1% of the mass of the mixed powder; and the mass of the mixed solvent is 50% of the mass of the mixed powder. The mass ratio of toluene to isopropyl alcohol in the mixed solvent is 5:10.5.

[0025] Step 3: Filter the slurry using a cartridge filter to remove small impurities. The filtered slurry is then directed into a hopper, where it is evenly coated onto the PET film. The slurry's thickness is controlled at 0.45mm during the casting process by precisely adjusting the scraper height. The casting speed is 0.5m / min. The slurry is then dried in three stages. The curing temperatures are, in chronological order, as follows: 30-60°C in the first zone, 50-80°C in the second zone, and 70-100°C in the third zone. During the drying process, the slurry gradually solidifies to form a green ribbon.

[0026] Step 4: The strips obtained in Step 3 are wound together as they pass through the rewinding device at the end of the tape casting machine, forming a roll. The roll is then unrolled and placed on the workbench of a stamping press. A die with a specialized blade structure installed on the press shears and creases the strips to produce sheets. The sheets are then powdered, dried, and waxed.

[0027] Step 5: Place the green sheet in a main firing furnace at 1515±10℃. Under high temperature, the green sheet undergoes a sintering process, and the particles gradually fuse to form a dense and hard ceramic substrate.

[0028] Step 6: Use a high-pressure sandblaster to sandblast and clean the surface of the ceramic substrate, followed by re-drying to obtain the ceramic substrate product. The water pressure for sandblasting is 0.1-1MPa, and the re-drying temperature is 120±3°C. A warpage test is used to test the flatness of the ceramic substrate product. If the ceramic substrate product passes through a marble plate with a certain gap on the warpage tester under its own weight, the surface flatness is qualified. Ceramic substrates that fail to meet the flatness requirements are stacked and heated and softened at 1430±5°C in a flattening furnace under their own weight to improve warpage. A coloring machine is used to apply red or blue ink to one side of a sample of a ceramic substrate product that meets the flatness requirements. If a surface defect or crack is present on the sample, the ink will appear linearly on the other side, forming a surface defect mark. Defects can be detected by observing water penetration on the surface of the ceramic substrate product.

[0029] Example 3 A method for preparing a ceramic substrate with an aluminum oxide content of 98%, comprising the following steps: Step 1: Place the alumina powder and flux in an ultrafine blender for mixing and refining to obtain a mixed powder. In the mixed powder, the mass percentage of alumina powder is 98.5%, and the mass percentage of flux is 1.5%. In terms of mass percentage, the alumina powder includes 75% of a first alumina powder and 25% of a second alumina powder. The particle size of the first alumina powder is 1.8±0.2μm, and the particle size of the second alumina powder is 0.8±0.2μm. The flux includes MgO, SiO2, and CaO, wherein the mass ratio of MgO, SiO2, and CaO is 0.9:1.6:0.5.

[0030] Step 2: Add the mixed powder, polyvinyl butyral (PVB), dibutyl phthalate (DBP), Y2O3, and glycerol to a mixed solvent of toluene and isopropyl alcohol, mix thoroughly, and transfer to a ball mill for milling. The mixture is then fully degassed and aged to obtain a slurry. The mass of PVB is 5% of the mass of the mixed powder; the mass of DBP is 5% of the mass of the mixed powder; the mass of Y2O3 is 0.3% of the mass of the mixed powder; the mass of glycerol is 1% of the mass of the mixed powder; and the mass of the mixed solvent is 50% of the mass of the mixed powder. The mass ratio of toluene to isopropyl alcohol in the mixed solvent is 5:10.5.

[0031] Step 3: Filter the slurry using a cartridge filter to remove small impurities. The filtered slurry is then directed into a hopper, where it is evenly coated onto the PET film. The slurry's thickness is controlled at 0.45mm during the casting process by precisely adjusting the scraper height. The casting speed is 0.5m / min. The slurry is then dried in three stages. The curing temperatures are, in chronological order, as follows: 30-60°C in the first zone, 50-80°C in the second zone, and 70-100°C in the third zone. During the drying process, the slurry gradually solidifies to form a green ribbon.

[0032] Step 4: The strips obtained in Step 3 are wound together as they pass through the rewinding device at the end of the tape casting machine, forming a roll. The roll is then unrolled and placed on the workbench of a stamping press. A die with a specialized blade structure installed on the press shears and creases the strips to produce sheets. The sheets are then powdered, dried, and waxed.

[0033] Step 5: Place the green sheet in a main firing furnace at 1515±10℃. Under high temperature, the green sheet undergoes a sintering process, and the particles gradually fuse to form a dense and hard ceramic substrate.

[0034] Step 6: Use a high-pressure sandblaster to sandblast and clean the surface of the ceramic substrate, followed by re-drying to obtain the ceramic substrate product. The water pressure for sandblasting is 0.1-1MPa, and the re-drying temperature is 120±3°C. A warpage test is used to test the flatness of the ceramic substrate product. If the ceramic substrate product passes through a marble plate with a certain gap on the warpage tester under its own weight, the surface flatness is qualified. Ceramic substrates that fail to meet the flatness requirements are stacked and heated and softened at 1430±5°C in a flattening furnace under their own weight to improve warpage. A coloring machine is used to apply red or blue ink to one side of a sample of a ceramic substrate product that meets the flatness requirements. If a surface defect or crack is present on the sample, the ink will appear linearly on the other side, forming a surface defect mark. Defects can be detected by observing water penetration on the surface of the ceramic substrate product.

[0035] Example 4 A method for preparing a ceramic substrate with an aluminum oxide content of 98%, comprising the following steps: Step 1: Place the alumina powder and flux in an ultrafine blender for mixing and refining to obtain a mixed powder. In the mixed powder, the mass percentage of alumina powder is 98.5%, and the mass percentage of flux is 1.5%. In terms of mass percentage, the alumina powder includes 65% of a first alumina powder and 35% of a second alumina powder. The particle size of the first alumina powder is 1.8±0.2μm, and the particle size of the second alumina powder is 0.8±0.2μm. The flux includes MgO, SiO2, and CaO, wherein the mass ratio of MgO, SiO2, and CaO is 0.9:1.6:0.5.

[0036] Step 2: Add the mixed powder, polyvinyl butyral (PVB), dibutyl phthalate (DBP), Y2O3, and glycerol to a mixed solvent of toluene and isopropyl alcohol, mix thoroughly, and transfer to a ball mill for milling. The mixture is then fully degassed and aged to obtain a slurry. The mass of PVB is 5% of the mass of the mixed powder; the mass of DBP is 5% of the mass of the mixed powder; the mass of Y2O3 is 0.3% of the mass of the mixed powder; the mass of glycerol is 1% of the mass of the mixed powder; and the mass of the mixed solvent is 50% of the mass of the mixed powder. The mass ratio of toluene to isopropyl alcohol in the mixed solvent is 5:10.5.

[0037] Step 3: Filter the slurry using a cartridge filter to remove small impurities. The filtered slurry is then directed into a hopper, where it is evenly coated onto the PET film. The slurry's thickness is controlled at 0.45mm during the casting process by precisely adjusting the scraper height. The casting speed is 0.5m / min. The slurry is then dried in three stages. The curing temperatures are, in chronological order, as follows: 30-60°C in the first zone, 50-80°C in the second zone, and 70-100°C in the third zone. During the drying process, the slurry gradually solidifies to form a green ribbon.

[0038] Step 4: The strips obtained in Step 3 are wound together as they pass through the rewinding device at the end of the tape casting machine, forming a roll. The roll is then unrolled and placed on the workbench of a stamping press. A die with a specialized blade structure installed on the press shears and creases the strips to produce sheets. The sheets are then powdered, dried, and waxed.

[0039] Step 5: Place the green sheet in a main firing furnace at 1515±10℃. Under high temperature, the green sheet undergoes a sintering process, and the particles gradually fuse to form a dense and hard ceramic substrate.

[0040] Step 6: Use a high-pressure sandblaster to sandblast and clean the surface of the ceramic substrate, followed by re-drying to obtain the ceramic substrate product. The water pressure for sandblasting is 0.1-1MPa, and the re-drying temperature is 120±3°C. A warpage test is used to test the flatness of the ceramic substrate product. If the ceramic substrate product passes through a marble plate with a certain gap on the warpage tester under its own weight, the surface flatness is qualified. Ceramic substrates that fail to meet the flatness requirements are stacked and heated and softened at 1430±5°C in a flattening furnace under their own weight to improve warpage. A coloring machine is used to apply red or blue ink to one side of a sample of a ceramic substrate product that meets the flatness requirements. If a surface defect or crack is present on the sample, the ink will appear linearly on the other side, forming a surface defect mark. Defects can be detected by observing water penetration on the surface of the ceramic substrate product.

[0041] Example 5 A method for preparing a ceramic substrate with an aluminum oxide content of 98%, comprising the following steps: Step 1: Place the alumina powder and flux in an ultrafine blender for mixing and refining to obtain a mixed powder. In the mixed powder, the mass percentage of alumina powder is 98.5%, and the mass percentage of flux is 1.5%. In terms of mass percentage, the alumina powder includes 60% of a first alumina powder and 40% of a second alumina powder. The particle size of the first alumina powder is 1.8±0.2μm, and the particle size of the second alumina powder is 0.8±0.2μm. The flux includes MgO, SiO2, and CaO, wherein the mass ratio of MgO, SiO2, and CaO is 0.9:1.6:0.5.

[0042] Step 2: Add the mixed powder, polyvinyl butyral (PVB), dibutyl phthalate (DBP), Y2O3, and glycerol to a mixed solvent of toluene and isopropyl alcohol, mix thoroughly, and transfer to a ball mill for milling. The mixture is then fully degassed and aged to obtain a slurry. The mass of PVB is 5% of the mass of the mixed powder; the mass of DBP is 5% of the mass of the mixed powder; the mass of Y2O3 is 0.3% of the mass of the mixed powder; the mass of glycerol is 1% of the mass of the mixed powder; and the mass of the mixed solvent is 50% of the mass of the mixed powder. The mass ratio of toluene to isopropyl alcohol in the mixed solvent is 5:10.5.

[0043] Step 3: Filter the slurry using a cartridge filter to remove small impurities. The filtered slurry is then directed into a hopper, where it is evenly coated onto the PET film. The slurry's thickness is controlled at 0.45mm during the casting process by precisely adjusting the scraper height. The casting speed is 0.5m / min. The slurry is then dried in three stages. The curing temperatures are, in chronological order, as follows: 30-60°C in the first zone, 50-80°C in the second zone, and 70-100°C in the third zone. During the drying process, the slurry gradually solidifies to form a green ribbon.

[0044] Step 4: The strips obtained in Step 3 are wound together as they pass through the rewinding device at the end of the tape casting machine, forming a roll. The roll is then unrolled and placed on the workbench of a stamping press. A die with a specialized blade structure installed on the press shears and creases the strips to produce sheets. The sheets are then powdered, dried, and waxed.

[0045] Step 5: Place the green sheet in a main firing furnace at 1515±10℃. Under high temperature, the green sheet undergoes a sintering process, and the particles gradually fuse to form a dense and hard ceramic substrate.

[0046] Step 6: Use a high-pressure sandblaster to sandblast and clean the surface of the ceramic substrate, followed by re-drying to obtain the ceramic substrate product. The water pressure for sandblasting is 0.1-1MPa, and the re-drying temperature is 120±3°C. A warpage test is used to test the flatness of the ceramic substrate product. If the ceramic substrate product passes through a marble plate with a certain gap on the warpage tester under its own weight, the surface flatness is qualified. Ceramic substrates that fail to meet the flatness requirements are stacked and heated and softened at 1430±5°C in a flattening furnace under their own weight to improve warpage. A coloring machine is used to apply red or blue ink to one side of a sample of a ceramic substrate product that meets the flatness requirements. If a surface defect or crack is present on the sample, the ink will appear linearly on the other side, forming a surface defect mark. Defects can be detected by observing water penetration on the surface of the ceramic substrate product.

[0047] Example 6 A method for preparing a ceramic substrate with an aluminum oxide content of 98%, comprising the following steps: Step 1: Place the alumina powder and flux in an ultrafine blender for mixing and refining to obtain a mixed powder. In the mixed powder, the mass percentage of alumina powder is 98.5%, and the mass percentage of flux is 1.5%. In terms of mass percentage, the alumina powder includes 55% of a first alumina powder and 45% of a second alumina powder. The particle size of the first alumina powder is 1.8±0.2μm, and the particle size of the second alumina powder is 0.8±0.2μm. The flux includes MgO, SiO2, and CaO, wherein the mass ratio of MgO, SiO2, and CaO is 0.9:1.6:0.5.

[0048] Step 2: Add the mixed powder, polyvinyl butyral (PVB), dibutyl phthalate (DBP), Y2O3, and glycerol to a mixed solvent of toluene and isopropyl alcohol, mix thoroughly, and transfer to a ball mill for milling. The mixture is then fully degassed and aged to obtain a slurry. The mass of PVB is 5% of the mass of the mixed powder; the mass of DBP is 5% of the mass of the mixed powder; the mass of Y2O3 is 0.3% of the mass of the mixed powder; the mass of glycerol is 1% of the mass of the mixed powder; and the mass of the mixed solvent is 50% of the mass of the mixed powder. The mass ratio of toluene to isopropyl alcohol in the mixed solvent is 5:10.5.

[0049] Step 3: Filter the slurry using a cartridge filter to remove small impurities. The filtered slurry is then directed into a hopper, where it is evenly coated onto the PET film. The slurry's thickness is controlled at 0.45mm during the casting process by precisely adjusting the scraper height. The casting speed is 0.5m / min. The slurry is then dried in three stages. The curing temperatures are, in chronological order, as follows: 30-60°C in the first zone, 50-80°C in the second zone, and 70-100°C in the third zone. During the drying process, the slurry gradually solidifies to form a green ribbon.

[0050] Step 4: The strips obtained in Step 3 are wound together as they pass through the rewinding device at the end of the tape casting machine, forming a roll. The roll is then unrolled and placed on the workbench of a stamping press. A die with a specialized blade structure installed on the press shears and creases the strips to produce sheets. The sheets are then powdered, dried, and waxed.

[0051] Step 5: Place the green sheet in a main firing furnace at 1515±10℃. Under high temperature, the green sheet undergoes a sintering process, and the particles gradually fuse to form a dense and hard ceramic substrate.

[0052] Step 6: Use a high-pressure sandblaster to sandblast and clean the surface of the ceramic substrate, followed by re-drying to obtain the ceramic substrate product. The water pressure for sandblasting is 0.1-1MPa, and the re-drying temperature is 120±3°C. A warpage test is used to test the flatness of the ceramic substrate product. If the ceramic substrate product passes through a marble plate with a certain gap on the warpage tester under its own weight, the surface flatness is qualified. Ceramic substrates that fail to meet the flatness requirements are stacked and heated and softened at 1430±5°C in a flattening furnace under their own weight to improve warpage. A coloring machine is used to apply red or blue ink to one side of a sample of a ceramic substrate product that meets the flatness requirements. If a surface defect or crack is present on the sample, the ink will appear linearly on the other side, forming a surface defect mark. Defects can be detected by observing water penetration on the surface of the ceramic substrate product.

[0053] Example 7 A method for preparing a ceramic substrate with an aluminum oxide content of 98%, comprising the following steps: Step 1: Place the alumina powder and flux in an ultrafine blender for mixing and refining to obtain a mixed powder. In the mixed powder, the mass percentage of alumina powder is 98.5%, and the mass percentage of flux is 1.5%. In terms of mass percentage, the alumina powder includes 50% of a first alumina powder and 50% of a second alumina powder. The particle size of the first alumina powder is 1.8±0.2μm, and the particle size of the second alumina powder is 0.8±0.2μm. The flux includes MgO, SiO2, and CaO, wherein the mass ratio of MgO, SiO2, and CaO is 0.9:1.6:0.5.

[0054] Step 2: Add the mixed powder, polyvinyl butyral (PVB), dibutyl phthalate (DBP), Y2O3, and glycerol to a mixed solvent of toluene and isopropyl alcohol, mix thoroughly, and transfer to a ball mill for milling. The mixture is then fully degassed and aged to obtain a slurry. The mass of PVB is 5% of the mass of the mixed powder; the mass of DBP is 5% of the mass of the mixed powder; the mass of Y2O3 is 0.3% of the mass of the mixed powder; the mass of glycerol is 1% of the mass of the mixed powder; and the mass of the mixed solvent is 50% of the mass of the mixed powder. The mass ratio of toluene to isopropyl alcohol in the mixed solvent is 5:10.5.

[0055] Step 3: Filter the slurry using a cartridge filter to remove small impurities. The filtered slurry is then directed into a hopper, where it is evenly coated onto the PET film. The slurry's thickness is controlled at 0.45mm during the casting process by precisely adjusting the scraper height. The casting speed is 0.5m / min. The slurry is then dried in three stages. The curing temperatures are, in chronological order, as follows: 30-60°C in the first zone, 50-80°C in the second zone, and 70-100°C in the third zone. During the drying process, the slurry gradually solidifies to form a green ribbon.

[0056] Step 4: The strips obtained in Step 3 are wound together as they pass through the rewinding device at the end of the tape casting machine, forming a roll. The roll is then unrolled and placed on the workbench of a stamping press. A die with a specialized blade structure installed on the press shears and creases the strips to produce sheets. The sheets are then powdered, dried, and waxed.

[0057] Step 5: Place the green sheet in a main firing furnace at 1515±10℃. Under high temperature, the green sheet undergoes a sintering process, and the particles gradually fuse to form a dense and hard ceramic substrate.

[0058] Step 6: Use a high-pressure sandblaster to sandblast and clean the surface of the ceramic substrate, followed by re-drying to obtain the ceramic substrate product. The water pressure for sandblasting is 0.1-1MPa, and the re-drying temperature is 120±3°C. A warpage test is used to test the flatness of the ceramic substrate product. If the ceramic substrate product passes through a marble plate with a certain gap on the warpage tester under its own weight, the surface flatness is qualified. Ceramic substrates that fail to meet the flatness requirements are stacked and heated and softened at 1430±5°C in a flattening furnace under their own weight to improve warpage. A coloring machine is used to apply red or blue ink to one side of a sample of a ceramic substrate product that meets the flatness requirements. If a surface defect or crack is present on the sample, the ink will appear linearly on the other side, forming a surface defect mark. Defects can be detected by observing water penetration on the surface of the ceramic substrate product.

[0059] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the mass of Y2O3 is 0.2% of the mass of the mixed powder.

[0060] Comparative Example 2 The only difference between Comparative Example 2 and Example 1 is that the mass of Y2O3 is 0.4% of the mass of the mixed powder.

[0061] Comparative Example 3 The only difference between Comparative Example 3 and Example 1 is that the mass of Y2O3 is 0.5% of the mass of the mixed powder.

[0062] Comparative Example 4 The only difference between Comparative Example 4 and Example 1 is that the mass of Y2O3 is 0% of the mass of the mixed powder.

[0063] Comparative Example 5 The only difference between Comparative Example 5 and Example 1 is that the aluminum oxide powder is the first aluminum oxide powder.

[0064] Comparative Example 6 The only difference between Comparative Example 6 and Example 1 is that the aluminum oxide powder is the second aluminum oxide powder.

[0065] The ceramic substrate products obtained in Examples 1 to 7 and Comparative Examples 1 to 6 were subjected to performance tests. The test methods for each performance test are as follows: a. Surface roughness test The surface roughness of the ceramic substrate product was tested using a stylus method. A diamond stylus was slid across the surface of the ceramic substrate product, and the vertical displacement of the stylus was recorded by a sensor to obtain surface profile information and obtain the Ra value of the surface roughness of the ceramic substrate product. At least three samples were selected for each embodiment and each comparative example, and three points were selected at different positions of the samples for testing, and the average value of the test results was taken.

[0066] b. Density test The density of ceramic substrate products was tested using the Archimedean displacement method: A densitometer was used to measure the mass of the ceramic substrate product in air (m1) and in water (m2), respectively. The values ​​were recorded on the instrument. The density ρ of the ceramic substrate product was calculated using the following formula. At least five samples were tested for each example and comparative example, and the average of the test results was used.

[0067]

[0068] Among them, ρ 水 Indicates the density of water.

[0069] c. Bending strength test The bending strength of the ceramic substrate product was tested using a universal testing machine. At least three samples were selected for each embodiment and each comparative example for testing, and the average value of the test results was taken. The size of the test sample was 30×20 mm, the test span was 25 mm, and the descent speed was 0.5 mm / min.

[0070] Some parameters and performance test results of the ceramic substrate products obtained in Examples 1 to 7 and Comparative Examples 1 to 4 are shown in Table 1.

[0071] Table 1 Some parameters and performance test results of ceramic substrate products

[0072] As shown in Table 1, although the flexural strength, density, and surface roughness of the ceramic substrate obtained in Comparative Example 4 are comparable to those obtained in Examples 1-7, due to the absence of Y2O3, the sintering temperature of the ceramic substrate obtained in Comparative Example 4 is as high as 1575-1595°C, which is much higher than that of the ceramic substrates obtained in Examples 1-7. Compared with the ceramic substrates obtained in Comparative Examples 1-3 and Comparative Examples 5-6, the ceramic substrates obtained in Examples 1-7, at the same sintering temperature, have a flexural strength of 468-564 MPa and a density of 3.8-3.9 g / cm3. 3 , the surface roughness Ra is 0.11-0.15μm, with high bending strength, moderate density and low surface roughness.

[0073] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and substance of the present invention, persons of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any changes or substitutions that can be readily conceived by persons skilled in the art within the technical scope disclosed in the present invention shall be within the scope of protection of the present invention.

Claims

1. A method for preparing an alumina ceramic substrate, characterized in that: The steps include: Step 1: mixing and refining the alumina powder and the flux to obtain a mixed powder, wherein the alumina powder includes a first alumina powder and a second alumina powder, wherein the particle size of the first alumina powder is 1.8±0.2 μm, and the particle size of the second alumina powder is 0.8±0.2 μm; Step 2: adding the mixed powder, binder, plasticizer, sintering aid and dispersant to a mixed solvent of toluene and isopropyl alcohol, mixing them evenly and then ball milling them, and then fully degassing and aging them to obtain a slurry, wherein the sintering aid is Y2O3; Step 3: Evenly apply the slurry onto the PET film, and then perform three-stage drying to obtain a blank strip; Step 4: Roll and punch the blank strip in sequence to obtain a blank sheet; Step 5: The green sheet is sintered at 1500-1550°C to obtain a ceramic substrate with an alumina content of 98%.

2. The method for preparing an alumina ceramic substrate according to claim 1, wherein: In step 1, the flux includes MgO, SiO2 and CaO, wherein the mass ratio of MgO, SiO2 and CaO is 0.4-1.6:1-3:0.1-0.

7.

3. The method for preparing an alumina ceramic substrate according to claim 1, wherein: In step 1, the aluminum oxide powder includes 50% to 80% by mass of a first aluminum oxide powder and 20% to 50% by mass of a second aluminum oxide powder.

4. The method for preparing an alumina ceramic substrate according to claim 1, wherein: In step 2, the binder is at least one of polyvinyl butyral, polyvinyl alcohol and paraffin; the plasticizer is at least one of dibutyl phthalate, dimethyl phthalate and diethyl phthalate; and the dispersant is at least one of glyceride, fatty acid ester, polyethyleneimine and polymethacrylic acid.

5. The method for preparing an alumina ceramic substrate according to claim 4, wherein: In step 2, the mass of the binder is 5%-9% of the mass of the mixed powder; the mass of the plasticizer is 2%-6% of the mass of the mixed powder; the mass of the sintering aid is 0.3% of the mass of the mixed powder; the mass of the dispersant is 0.5%-3% of the mass of the mixed powder; and the mass of the mixed solvent is 40%-60% of the mass of the mixed powder.

6. The method for preparing an alumina ceramic substrate according to claim 1, wherein: In step 2, the mass ratio of toluene to isopropanol in the mixed solvent is 3-6:9-13.

7. The method for preparing an alumina ceramic substrate according to claim 1, wherein: In step three, the slurry is filtered before being evenly coated on the PET film.

8. The method for preparing an alumina ceramic substrate according to claim 1, wherein: In step 3, the coating thickness of the slurry is 0.4-0.5 mm, and the temperatures of the three-stage drying are 30-60° C., 50-80° C., and 70-100° C. in chronological order.

9. The method for preparing an alumina ceramic substrate according to claim 1, wherein: In step 4, the blank is powdered, dried and waxed in sequence.

10. The method for preparing an alumina ceramic substrate according to claim 1, wherein: The method further includes step six: sandblasting and cleaning the surface of the ceramic substrate and drying it again.

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