A large-size ceramic substrate and its preparation method

Abstract

This invention relates to the field of ceramic substrate technology, specifically to a large-size ceramic substrate and its preparation method. The preparation method includes at least the following steps: (1) Powder ball milling: the solid phase component is ball-milled using a wet method. The grinding stones include 15mm large balls, 10mm medium balls, and 5mm small balls. The mass ratio of the large, medium, and small balls is 1:2:1. The amount of grinding stones used is 3 times the mass of the solid phase component. The ball milling time is 24 hours. (2) Slurry preparation. (3) Casting: the slurry is coated to obtain a blank strip. The blank strip is placed in a drying chamber for drying. The temperatures of the first, second, and third temperature zones of the drying chamber are 30℃, 70℃, and 105-110℃, respectively. (4) Die punching. (5) Sintering. This invention, by adjusting the grinding stone ratio of the powder and adjusting the drying temperature of the casting process, can avoid the generation of defects, reduce the surface roughness of the product, and improve the strength of the product.

Description

Technical Field

[0001] This invention relates to the field of ceramic substrate technology, and more specifically to a large-size ceramic substrate and its preparation method. Background Technology

[0002] In recent years, semiconductor devices have developed rapidly towards higher power, higher frequency, and greater integration. The heat generated during the operation of semiconductor devices is a key factor causing their failure, and the thermal conductivity of the insulating substrate is crucial to the overall heat dissipation of the semiconductor device. Compared to traditional resin substrate materials, ceramic materials possess superior thermal conductivity and mechanical properties, along with advantages such as high melting point, high hardness, high wear resistance, and oxidation resistance, making them the optimal material for substrates in high-end semiconductor devices, especially high-power semiconductor devices.

[0003] In practical applications, the surface roughness and strength of ceramic substrates are key factors affecting subsequent copper-clad and circuit etching processes, which places high demands on substrate performance. Ceramic substrates are widely used core components in semiconductor manufacturing, and their manufacturing cost directly impacts their application and market competitiveness. This necessitates low-cost and high-efficiency manufacturing methods. Currently, ceramic substrate production primarily focuses on small-scale products, resulting in a limited range of applications.

[0004] Directly producing large-size ceramic substrates is beneficial for improving production efficiency and reducing costs. However, existing process formulas for small-size products cannot be directly applied to the production of large-size ceramic substrates. Currently, the following problems exist in the production of large-size ceramic substrates: ① The larger the ceramic substrate size, the more difficult it is to guarantee the substrate strength; ② The larger the ceramic substrate size, the more difficult it is to control the surface roughness of the product. Summary of the Invention

[0005] To address the technical problem that the larger the size of the ceramic substrate, the more difficult it is to guarantee the strength of the substrate and the more difficult it is to control the surface roughness, this invention provides a large-size ceramic substrate and its preparation method. By adjusting the ball milling ratio of the powder and adjusting the drying temperature of the casting molding, defects can be avoided, the surface roughness of the product can be reduced, and the strength of the product can be improved.

[0006] In a first aspect, the present invention provides a method for preparing a large-size ceramic substrate, comprising at least the following steps:

[0007] (1) Powder ball milling: The solid phase component is ball milled by wet method. The grinding stones include 15mm large balls, 10mm medium balls and 5mm small balls. The mass ratio of large balls, medium balls and small balls is 1:2:1. The amount of grinding stones is 3 times the mass of the solid phase component. The ball milling time is 24h. The powder after ball milling is collected for the preparation of slurry.

[0008] (2) Slurry preparation;

[0009] (3) Casting: The blank strip is obtained by coating the slurry and placed in the drying chamber for drying. The drying chamber is divided into three temperature zones: zone 1, zone 2, and zone 3. The temperatures of zone 1, zone 2, and zone 3 are 30℃, 70℃, and 105-110℃, respectively. The airflow velocities of zone 1, zone 2, and zone 3 are 0, 0.5m / s, and 1.0m / s, respectively.

[0010] (4) Stamping die;

[0011] (5) Sintering.

[0012] Furthermore, the solid phase component includes alumina powder with a mass percentage of 95%-99% and a co-solvent with a mass percentage of 1%-5%, and the alumina powder has a particle size of 1.0-6.0 μm.

[0013] Furthermore, the co-solvents include silicon oxide, calcium oxide, and magnesium oxide in a mass ratio of 1-4:0.2-0.7:0.5-1.8.

[0014] Further, step (2) specifically involves dispersing the ball-milled powder evenly with binder, plasticizer, dispersant and solvent, and then aging and degassing to obtain a slurry.

[0015] Furthermore, the binder is selected from one or more of polyvinyl butyral (PVB), polyvinyl alcohol, paraffin, and stearic acid, and the mass of the binder is 6.5%-9.5% of the mass of the solid phase component.

[0016] Furthermore, the plasticizer is selected from one or more of dibutyl phthalate (DBP), dimethyl phthalate (DMP), diethyl phthalate (DEP), dioctyl phthalate (DOP), and butyl benzyl phthalate (BBP), and the mass of the plasticizer is 1%-4% of the mass of the solid phase component. The plasticizer can play a lubricating and binding role, improving the stability of the slurry.

[0017] Furthermore, the dispersant is selected from one or more of glycerol esters, fatty acid esters, polyethyleneimine, and polymethacrylic acid, and the mass of the dispersant is 0.8%-2.5% of the mass of the solid phase component. The dispersant can increase the dispersibility of the powder and the uniformity of the substrate.

[0018] Furthermore, the solvent is at least one of benzene-based solvents and alcohol-based solvents, specifically using a mixture of toluene and isopropanol as the solvent, with a mass ratio of toluene to isopropanol of 3.5-6.5:8.5-12.5, and the solvent mass is 45%-55% of the solid phase component mass.

[0019] Further, step (4) involves placing the blank strip under a press and stamping it using a die with a blade structure on the press. Then, the blank strip is prepared by applying powder, drying, and waxing.

[0020] Furthermore, to identify the product's orientation and front / back sides, an identification angle is provided at the lower right corner of the ceramic substrate, with a dimension C of the identification angle. 辨识角 =1.50-2.50mm, where C 辨识角 This indicates the length of the hypotenuse of an isosceles right triangle constructed at the lower right corner of the ceramic substrate. The longer side opposite the angle is designated L1, and the shorter side is designated W1. The longer side adjacent to the angle is designated L3, and the shorter side is designated W3. An identification arc is provided on side W3, with a radius R. 辨识 =0.50-1.00mm, identify the distance L between the central angle of the arc and the boundary of the ceramic substrate. 弦 =0.30-0.60mm.

[0021] Furthermore, to better prevent product damage due to stress concentration during manufacturing, and to protect operators, chamfers are provided at the upper left, lower left, and upper right corners of the ceramic substrate. The chamfer dimension C... 倒角 =0.20-0.60mm, where C 倒角 This indicates the length of the hypotenuse of the isosceles right triangles constructed at the top left, bottom left, and top right corners of the ceramic substrate.

[0022] Further, step (5) specifically involves placing the billet in a rotary sintering furnace and sintering it at 1500-1650℃.

[0023] Furthermore, it also includes the following steps:

[0024] (6) Warpage test: The sintered ceramic substrate is subjected to a warpage test. Under its own weight, it passes through a glass plate with a certain gap at a 45° angle. If it passes, the surface flatness is qualified.

[0025] (7) Leveling: Place the ceramic substrate that fails the warping test in a rotary leveling furnace and heat it at 1350-1450℃ to soften it. The warping of the ceramic substrate is improved by stacking and firing under its own weight.

[0026] (8) Inspection: When ink is applied to the surface of the ceramic substrate product, defect marks will be formed at the defective areas.

[0027] Secondly, the present invention provides a large-size ceramic substrate prepared by the above-mentioned preparation method, with a side length of 120-200 mm, a thickness of 0.30-1.00 mm, and a surface roughness between 0.2 and 0.4.

[0028] Furthermore, the flexural strength of large-size, high-strength ceramic substrates is ≥450MPa.

[0029] The beneficial effects of this invention are as follows:

[0030] This invention significantly increases the flexural strength of ceramic substrates by adjusting the ball milling ratio and milling time of the powder, and by adjusting the drying temperature of the cast film molding process. It also effectively improves the density of the product, reduces defects and surface roughness, and facilitates large-scale automated production, thereby reducing material and labor costs. Specifically, compared with existing technologies, this invention has the following advantages:

[0031] 1. This invention reduces the ball milling time of the powder by adjusting the ball milling stone ratio, thereby increasing the ball milling efficiency, increasing the flexural strength of the ceramic substrate, and improving the density of the product. Therefore, it is beneficial for large-scale automated production and reduces costs.

[0032] 2. This invention accelerates the drying process of cast casting and reduces defects and surface roughness of the product by adjusting the drying temperature of the cast casting process. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of the ceramic substrate in a specific embodiment of the present invention.

[0035] Figure 2 yes Figure 1 A magnified schematic diagram of the structure of the middle circle Q.

[0036] In the diagram, 1 is edge L1, 2 is edge W1, 3 is edge L3, 4 is edge W3, and O is the center of the arc. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0038] Example 1

[0039] A ceramic substrate with a length of 189.70-190.30 mm, a width of 141.70-142.30 mm, and a thickness of 0.43-0.50 mm is prepared according to the following method, with specific steps as follows:

[0040] (1) Powder ball milling: The solid phase component was ball milled by wet method. The proportion of alumina powder in the solid phase component was 96%, the particle size of alumina powder was 5±0.2μm, the proportion of co-solvent was 4%, and the co-solvent component was SiO-CaO-MgO with a mass ratio of 1.7:0.6:1.0. The amount of grinding stones added included 15mm large balls, 10mm medium balls and 5mm small balls with a mass ratio of 1:2:1. The amount of grinding stones used was 3 times the mass of the solid phase component, and the ball milling time was 24h.

[0041] (2) Slurry preparation: After the ball milled powder is dried in a spray tower, it is added to a disperser along with binder, plasticizer, dispersant and solvent. After aging and degassing, a slurry is obtained.

[0042] The binder is PVB, and the mass of the binder is 7% of the mass of the solid phase component.

[0043] The plasticizer is DBP, and the binder accounts for 3.5% of the mass of the solid phase component.

[0044] The dispersant is a glycerol ester, and its mass is 1% of the mass of the solid component.

[0045] The solvent was a mixture of toluene and isopentol in a mass ratio of 6:11.5, and the mass of the solvent was 48% of the mass of the solid phase component.

[0046] (3) Casting: The degassed slurry is coated onto the PET film through a hopper. The thickness of the green film is controlled by the height of the scraper. Then it is dried in a drying chamber to evaporate the solvent in the slurry and obtain the green film.

[0047] The drying chamber is divided into three temperature zones: a first temperature zone, a second temperature zone, and a third temperature zone. In the early stage of drying, a lower temperature needs to be maintained to prevent defects caused by different solvent evaporation rates between the upper and lower layers of the product. In the later stage, a higher temperature needs to be maintained to reduce drying time and improve production efficiency. The temperatures of the three temperature zones are 30℃, 70℃, and 110℃, and the airflow velocities are 0, 0.5m / s, and 1.0m / s, respectively.

[0048] (4) Stamping: The blank strip is placed under the press and stamped using the die with blade structure on the press. Then, the blank strip is prepared by steps such as powdering, drying, and waxing.

[0049] To identify the product's orientation and front / back sides, an identification angle is provided at the lower right corner of the ceramic substrate. The size of the identification angle is C. 辨识角 =1.50-2.50mm, where C 辨识角 This indicates the length of the hypotenuse of an isosceles right triangle drawn at the lower right corner of the ceramic substrate. The longer side opposite the angle is designated L1, and the shorter side is designated W1. The longer side adjacent to the angle is designated L3, and the shorter side is designated W3. An identification arc (e.g., ...) is provided on the W3 side. Figure 2 As shown), identify the radius R of the arc.辨识 =0.50-1.00mm, identify the distance L between the central angle of the arc and the boundary of the ceramic substrate. 弦 =0.30-0.60mm;

[0050] To better prevent damage to the product due to stress concentration during manufacturing, and to protect operators, chamfers are provided at the upper left, lower left, and upper right corners of the ceramic substrate. The chamfer dimension C... 倒角 =0.20-0.60mm, where C 倒角 This indicates the length of the hypotenuse of the isosceles right triangles constructed at the top left, bottom left, and top right corners of the ceramic substrate.

[0051] (5) Sintering: The blank is placed in a rotary sintering furnace and sintered at 1520℃. Through sintering, the particles migrate, densify, and re-agglomerate, causing the particles to stick together and generate a certain strength.

[0052] (6) Warpage test: The sintered ceramic substrate is subjected to a warpage test. Under its own weight, it passes through a glass plate with a certain gap at a 45° angle. If it passes, the surface flatness is qualified.

[0053] (7) Leveling: Place the ceramic substrate that fails the warping test in a rotary leveling furnace and heat it at 1380°C to soften it. By stacking and firing, the warping of the ceramic substrate is improved under its own weight.

[0054] (8) Inspection: Apply red or blue ink to the surface of the ceramic substrate product. Defect marks will be formed at the defective areas.

[0055] Comparative Example 1

[0056] The only difference between this example and Example 1 is that the mass ratio of large, medium and small grinding stones is 1:2:2, and the rest is the same as in Example 1.

[0057] Comparative Example 2

[0058] The only difference between this example and Example 1 is that the mass ratio of large, medium and small grinding stones is 1:2:3, and the rest is the same as in Example 1.

[0059] Comparative Example 3

[0060] The only difference between this example and Example 1 is that the mass ratio of large, medium and small grinding stones is 2:2:1, and the rest is the same as in Example 1.

[0061] Comparative Example 4

[0062] The only difference between this example and Example 1 is that the mass ratio of large, medium and small grinding stones is 3:2:1, and the rest is the same as in Example 1.

[0063] Comparative Example 5

[0064] The only difference between this example and Example 1 is that the mass ratio of large, medium and small grinding stones is 1:1:1, and the rest is the same as in Example 1.

[0065] The performance of the ceramic substrates of Example 1 and Comparative Examples 1-5 was tested, and the test methods are described below:

[0066] I. Bending strength

[0067] The bending strength of the ceramic substrate was tested using a universal testing machine. At least three samples were selected for each example / comparative example and the average value of the test results was taken. The size of the test sample was 30×20mm, the test span was 25mm, and the descent speed was 0.5mm / min.

[0068] II. Density

[0069] The density of the ceramic substrate was tested using the water displacement method. At least five samples were selected for each example / comparative example, and the average value of the test results was taken.

[0070] The results are shown in Table 1 below.

[0071] Table 1 Performance test results of Example 1 and Comparative Examples 1-5

[0072]

[0073] Example 2

[0074] The only difference between this example and Example 1 is that the temperatures of the first, second, and third temperature zones are 30°C, 70°C, and 105°C, respectively; the rest is the same as in Example 1.

[0075] Example 3

[0076] The only difference between this example and Example 1 is that the temperatures of the first, second, and third temperature zones are 30°C, 70°C, and 115°C, respectively; the rest is the same as in Example 1.

[0077] Comparative Example 6

[0078] The only difference between this example and Example 1 is that the temperatures of the first, second, and third temperature zones are 25°C, 70°C, and 105°C, respectively; the rest is the same as in Example 1.

[0079] Comparative Example 7

[0080] The only difference between this example and Example 1 is that the temperatures of the first, second, and third temperature zones are 25°C, 70°C, and 115°C, respectively; the rest is the same as in Example 1.

[0081] Comparative Example 8

[0082] The only difference between this example and Example 1 is that the temperatures of the first, second, and third temperature zones are 35°C, 70°C, and 105°C, respectively; the rest is the same as in Example 1.

[0083] Comparative Example 9

[0084] The only difference between this example and Example 1 is that the temperatures of the first, second, and third temperature zones are 35°C, 70°C, and 115°C, respectively; the rest is the same as in Example 1.

[0085] The performance of the ceramic substrates of Examples 1-3 and Comparative Examples 6-9 was tested, and the test methods are described below:

[0086] I. Surface Roughness

[0087] The surface roughness Ra of a ceramic substrate was tested using the stylus method. The test stylus was gently traced across the surface of the ceramic substrate. At least three samples were selected for each embodiment / comparative example, and three points were selected at different locations on the samples for testing. The average value of the test results was taken.

[0088] II. Bending Strength

[0089] The bending strength of the ceramic substrate was tested using a universal testing machine. At least three samples were selected for each example / comparative example and the average value of the test results was taken. The size of the test sample was 30×20mm, the test span was 25mm, and the descent speed was 0.5mm / min.

[0090] The results are shown in Table 2 below.

[0091] Table 2 Performance test results of Examples 1-3 and Comparative Examples 6-9

[0092]

[0093] As can be seen from the test results in Tables 1 and 2, the large-size ceramic substrate provided by this invention effectively improves strength and reduces surface roughness. The large-size ceramic substrate provided by this invention can be applied to the large-scale production of high-power semiconductor device substrates. This invention solves the problems of low strength and high roughness in current large-size ceramic substrates, which is beneficial for large-scale automated production and cost reduction.

[0094] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Various equivalent modifications or substitutions can be made to the embodiments of the present invention by those skilled in the art without departing from the spirit and essence of the invention, and such modifications or substitutions should all be within the scope of the present invention. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should also be covered within the protection scope of the present invention.

Claims

1. A method for preparing a large-size ceramic substrate, characterized in that, It should include at least the following steps: (1) Powder ball milling: The solid phase component is ball milled by wet method. The grinding stones include 15mm large balls, 10mm medium balls and 5mm small balls. The mass ratio of large balls, medium balls and small balls is 1:2:

1. The amount of grinding stones is 3 times the mass of the solid phase component. The ball milling time is 24h. The powder after ball milling is collected for the preparation of slurry. The solid phase component includes alumina powder with a mass percentage of 95%-99% and a co-solvent with a mass percentage of 1%-5%. The alumina powder has a particle size of 1.0-6.0 μm. The co-solvent includes silicon oxide, calcium oxide, and magnesium oxide in a mass ratio of 1-4:0.2-0.7:0.5-1.

8. (2) Slurry preparation; (3) Casting: The blank strip is obtained by coating the slurry and placed in the drying chamber for drying. The drying chamber is divided into three temperature zones: zone 1, zone 2, and zone 3. The temperatures of zone 1, zone 2, and zone 3 are 30℃, 70℃, and 105-110℃, respectively. The airflow velocities of zone 1, zone 2, and zone 3 are 0, 0.5m / s, and 1.0m / s, respectively. (4) Stamping die; (5) Sintering: Place the blanks in a rotary sintering furnace and sinter at 1500-1650℃; The large-size ceramic substrate has a side length of 120-200mm, a thickness of 0.30-1.00mm, a surface roughness between 0.2 and 0.4, and a bending strength ≥450MPa.

2. The preparation method according to claim 1, characterized in that, Step (2) specifically involves dispersing the ball-milled powder evenly with binder, plasticizer, dispersant and solvent, aging and degassing to obtain a slurry.

3. The preparation method according to claim 1, characterized in that, The binder is selected from one or more of polyvinyl butyral, polyvinyl alcohol, paraffin wax, and stearic acid, and the mass of the binder is 6.5%-9.5% of the mass of the solid phase component. The plasticizer is selected from one or more of dibutyl phthalate, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, and butyl benzyl phthalate, and the mass of the plasticizer is 1%-4% of the mass of the solid component; The dispersant is selected from one or more of glycerol esters, fatty acid esters, polyethyleneimine, and polymethacrylic acid, and the mass of the dispersant is 0.8%-2.5% of the mass of the solid component. The solvent is at least one of benzene-based solvents and alcohol-based solvents, and the mass of the solvent is 45%-55% of the mass of the solid phase component.

4. The preparation method according to claim 1, characterized in that, Step (4) involves placing the blank strip under a press and stamping it using a die with a blade structure on the press. Then, the blank strip is prepared by applying powder, drying, and waxing.

5. The preparation method according to claim 4, characterized in that, A recognition angle is provided at the lower right corner of the ceramic substrate, and the size of the recognition angle is C. 辨识角 =1.50-2.50mm, C 辨识角 This indicates the length of the hypotenuse of an isosceles right triangle constructed at the lower right corner of the ceramic substrate. The longer side opposite the angle is designated L1, and the shorter side is designated W1. The longer side adjacent to the angle is designated L3, and the shorter side is designated W3. An identification arc is provided on side W3, with a radius R. 辨识 =0.50-1.00mm, identify the distance L between the central angle of the arc and the boundary of the ceramic substrate. 弦 =0.30-0.60mm; Chamfers are provided at the upper left, lower left, and upper right corners of the ceramic substrate, with a chamfer dimension C. 倒角 =0.20-0.60mm, C 倒角 This indicates the length of the hypotenuse of the isosceles right triangles constructed at the top left, bottom left, and top right corners of the ceramic substrate.

Images