A large-size, high-strength ceramic substrate and its preparation method

Abstract

This invention relates to the field of ceramic substrate technology, specifically to a large-size, high-strength ceramic substrate and its preparation method. The preparation method involves casting a prepared slurry, molding it using a die, and then sintering it. The slurry raw materials include a solid component, a binder, a plasticizer, a dispersant, and a solvent. The solid component includes 96%-99% alumina powder by mass and 1%-4% a co-solvent by mass. The alumina powder has a particle size of 1.0-3.5 μm. The sintering temperature is 1500-1650℃. This invention, by reducing the alumina particle size and changing the sintering temperature, ensures the production efficiency of large-size ceramic substrates, thereby increasing the production efficiency of chip resistors by 27.3%-39.1%. Simultaneously, adjusting the alumina powder particle size also reduces the surface roughness of the product and improves the warpage yield.

Description

Technical Field

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

[0002] With the booming development of the microelectronics packaging technology industry, electronic packaging technology is moving towards miniaturization, high density, high power, and high reliability. Electronic packaging materials have gradually become a high-tech, high-economic-efficiency, and important industrial field. In recent years, the development of packaging materials has shown a rapid growth trend. Electronic materials are used to carry electronic components and their connecting circuits, and possess good electrical insulation properties.

[0003] Currently, substrates are commonly used electronic packaging materials. Substrate materials are mainly divided into metal substrates, polymer substrates, and ceramic substrates. Metal substrates, due to their low thermal conductivity insulation layer, have a low thermal conductivity, severely limiting their development in power electronic components. Ceramic substrates, as an emerging heat dissipation material, possess excellent insulation properties, as well as superior thermal conductivity, electrical properties, and mechanical strength at high temperatures. They are a commonly used electronic component material, widely applied in high-speed rail, new energy vehicles, photovoltaic power generation, and other fields, showing broad application prospects. However, the current efficiency of ceramic substrates clearly cannot meet market demand, resulting in limited product supply.

[0004] While large-format ceramic substrates can solve the problem of low production efficiency in current electronic packaging materials, the size of alumina grains during the production process can lead to a decrease in the number of grain boundaries and an increase in the size of defects such as bulk pores. Ultimately, this results in low ceramic matrix strength, high surface roughness, and severe warping issues in the product. Summary of the Invention

[0005] To address the technical problems of low ceramic matrix strength, high surface roughness, and severe warpage in the current production of large-size ceramic substrates, this invention provides a large-size, high-strength ceramic substrate and its preparation method. By reducing the alumina particle size and changing the sintering temperature, the production efficiency of large-size ceramic substrates is ensured, thereby increasing the production efficiency of chip resistors by 27.3%-39.1%. Simultaneously, adjusting the alumina powder particle size also reduces the surface roughness of the product, improving the warpage yield.

[0006] In a first aspect, the present invention provides a method for preparing a large-size, high-strength ceramic substrate, wherein a prepared slurry is cast, die-cast, and then sintered; wherein the slurry raw materials include a solid component, a binder, a plasticizer, a dispersant, and a solvent, the solid component includes alumina powder with a mass percentage of 96%-99% and a co-solvent with a mass percentage of 1%-4%, the alumina powder having a particle size of 1.0-3.5μm; and the sintering temperature is 1500-1650℃.

[0007] Furthermore, the co-solvents include MgO, SiO2 and CaO in a mass ratio of 0.4-1.6:1-3:0.1-0.7.

[0008] Furthermore, the binder is selected from one or more of polyvinyl butyral (PVB), polyvinyl alcohol, and paraffin, and the mass of the binder is 5%-9% of the mass of the solid phase component.

[0009] Furthermore, the plasticizer is selected from one or more of phthalate esters, fatty acid esters, phosphonate esters, and epoxy esters, specifically one or more of dibutyl phthalate (DBP), dimethyl phthalate (DMP), diethyl phthalate (DEP), dioctyl phthalate (DOP), and butyl benzyl phthalate (BBP), with the plasticizer mass being 2%-6% of the solid phase component mass.

[0010] Furthermore, the dispersant is selected from one or more of organic small molecule dispersants and organic high molecular weight dispersants, specifically using one or more of glycerol esters, fatty acid esters, polyethyleneimine, and polymethacrylic acid, with the mass of the dispersant being 0.5%-3% of the mass of the solid phase component.

[0011] Furthermore, the solvent is a mixture 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 3-6:9-13, and the solvent mass is 40%-60% of the solid phase component mass.

[0012] Secondly, the present invention provides a large-size, high-strength ceramic substrate prepared by the above-described preparation method.

[0013] Furthermore, the length of the large-size, high-strength ceramic substrate is 94.2-95.8 mm, the width is 65.2-66.8 mm, and the thickness is 0.15-0.25 mm.

[0014] Furthermore, the flexural strength of large-size, high-strength ceramic substrates is between 430-470 MPa.

[0015] Furthermore, the surface warpage of the large-size, high-strength ceramic substrate is between 0.37 and 0.41, and the surface roughness is between 0.1 and 0.3 μm.

[0016] The beneficial effects of this invention are as follows:

[0017] The raw materials of the ceramic substrate of the present invention include alumina powder, co-solvent, binder, plasticizer, dispersant and solvent. Alumina powder and co-solvent are the main components of the ceramic substrate. The strength and surface roughness of the ceramic substrate are controlled by controlling the particle size of alumina powder. The plasticizer can play a role in lubrication and bonding, and improve the stability of the slurry. The dispersant can increase the dispersibility of the powder and the uniformity of the substrate.

[0018] This invention can significantly increase the strength of ceramic substrates by adjusting the particle size of alumina and the sintering temperature, reduce cracking during surface metal printing, greatly improve production efficiency, and save material, labor and time costs. At the same time, the substrate has low surface roughness and high warpage yield. Detailed Implementation

[0019] 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.

[0020] Example 1

[0021] Large-size, high-strength ceramic substrates are prepared using the following method, with specific steps as follows:

[0022] (1) Slurry preparation: The solid components are added into the ball mill in a certain proportion. The proportion of alumina powder in the solid components is 96%, the particle size of alumina powder is 1.8±0.2μm, the proportion of co-solvent is 4%, and the composition of co-solvent is SiO2-MgO-CaO with a mass ratio of 1.6:0.9:0.5. Then, the binder PVB (accounting for 5% of the mass of the solid components), plasticizer DBP (accounting for 5% of the mass of the solid components), and dispersant glyceryl ester (accounting for 1% of the mass of the solid components) are dissolved in the solvent (a mixture of toluene and isopropanol with a mass ratio of 5:10.5, accounting for 50% of the mass of the solid components). The mixture is then added into the ball mill. After thorough ball milling, degassing and aging, the slurry required for casting is obtained.

[0023] (2) Casting: The slurry prepared in (1) is filtered and then evenly coated on the PET film through a hopper. The slurry is then spread on the film by a scraper. The height of the scraper is adjusted to control the thickness of the slurry. After heating and drying, the solvent in the slurry evaporates, and a green body with a certain thickness, density and surface uniformity is obtained.

[0024] (3) Stamping: The green blank obtained in (2) is placed under the stamping machine. The blank strip is stamped with the blade structure mold on the stamping machine. A recognition angle of C=1.00 is prepared on the lower left of the ceramic substrate, and chamfers of C=0.5 are prepared on the other three corners. Then, the blank required for sintering is prepared by steps such as powdering, drying, and waxing.

[0025] (4) Main firing of ceramic: The green body obtained in (3) is sintered at 1530℃ to obtain a highly versatile, large-size ceramic substrate. During the sintering process, migration densification and recrystallization will occur, causing the particles to stick together and generate a certain strength. The ceramic substrate is then sandblasted and dried by a high-pressure sandblasting machine.

[0026] (5) Warping test: The ceramic substrate is tilted at a 45° angle through a marble plate with a certain gap under its own weight. If it passes, it means that the surface flatness is qualified.

[0027] (6) Warpage correction: The ceramic substrate that fails the warpage test is heated and softened at 1400℃, and the warpage is improved by stacking and firing under its own gravity.

[0028] (7) Inspection: Apply red or blue ink to the sample surface and detect defects by observing the penetration of ink on the substrate surface. When there are defects or cracks on the product surface, the contact point between the ink and the substrate becomes a contact line, which will form surface defect traces.

[0029] Example 2

[0030] The only difference between this example and Example 1 is that the particle size of the alumina powder used is 2.5±0.2μm; otherwise, they are the same as in Example 1.

[0031] Example 3

[0032] The only difference between this example and Example 1 is that the particle size of the alumina powder used is 3±0.2μm; otherwise, they are the same as in Example 1.

[0033] Example 4

[0034] The only difference between this example and Example 1 is that the particle size of the alumina powder used is 3.5±0.2μm; otherwise, they are the same as in Example 1.

[0035] Example 5

[0036] The only difference between this example and Example 1 is that the sintering temperature used is 1510℃, and the rest is the same as in Example 1.

[0037] Example 6

[0038] The only difference between this example and Example 1 is that the sintering temperature used is 1520°C; otherwise, they are the same as in Example 1.

[0039] Example 7

[0040] The only difference between this example and Example 1 is that the sintering temperature used is 1540°C; otherwise, they are the same as in Example 1.

[0041] Example 8

[0042] The only difference between this example and Example 1 is that the sintering temperature used is 1550°C; otherwise, they are the same as in Example 1.

[0043] The dimensions of the ceramic substrates in Examples 1-8 were tested. The length of the ceramic substrates in each example was in the range of 94.2-95.8 mm, the width was in the range of 65.2-66.8 mm, the thickness was in the range of 0.15-0.25 mm, and the surface warpage was between 0.37 and 0.41.

[0044] Comparative Example 1

[0045] The only difference between this example and Example 1 is that the particle size of the alumina powder used is 4±0.2μm; otherwise, they are the same as in Example 1.

[0046] Comparative Example 2

[0047] The only difference between this example and Example 1 is that the particle size of the alumina powder used is 5±0.2μm; otherwise, they are the same as in Example 1.

[0048] Comparative Example 3

[0049] The only difference between this example and Example 1 is that the solvent used is isopropanol, which accounts for 50% of the mass of the solid phase component; the rest is the same as in Example 1.

[0050] The performance of the ceramic substrates of Examples 1-8 and Comparative Examples 1-3 was tested, and the test methods are described below:

[0051] I. Surface Roughness

[0052] 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.

[0053] II. Density

[0054] 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.

[0055] III. Bending Strength

[0056] 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.

[0057] Table 1. Performance test results of ceramic substrates

[0058]

[0059] As shown in Table 1, the preparation method of this invention can significantly increase the production efficiency of the substrate by reducing the particle size of alumina and optimizing the sintering temperature, saving production materials and reducing labor and time costs. Simultaneously, the substrate exhibits low surface roughness and a high warpage yield. Using a mixed solvent of toluene and isopropanol is beneficial for improving the dispersion of powder in the slurry, thereby increasing the strength and density of the product.

[0060] 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, high-strength ceramic substrate, characterized in that, The prepared slurry is cast, die-cast, and then sintered. The slurry raw materials include solid components, binders, plasticizers, dispersants, and solvents. The solid components include alumina powder with a mass percentage of 96%-99% and a flux with a mass percentage of 1%-4%. The alumina powder has a particle size of 1.0-3.5μm. The flux includes MgO, SiO2, and CaO in a mass ratio of 0.4-1.6:1-3:0.1-0.

7. The sintering temperature is 1500-1650℃. The solvent mass is 40%-60% of the solid phase component mass. A mixture of toluene and isopropanol is used as the solvent, with a mass ratio of toluene to isopropanol of 5:10.

5. The length of the large-size, high-strength ceramic substrate is 94.2-95.8 mm, the width is 65.2-66.8 mm, and the thickness is 0.15-0.25 mm. The bending strength of large-size, high-strength ceramic substrates is between 430-470 MPa, the surface warpage is between 0.37-0.41, and the surface roughness is between 0.1-0.3 μm.

2. The preparation method according to claim 1, characterized in that, The binder is selected from one or more of polyvinyl butyral, polyvinyl alcohol, and paraffin, and the mass of the binder is 5%-9% of the mass of the solid phase component.

3. The preparation method according to claim 1, characterized in that, The plasticizer is selected from one or more of phthalates, fatty acid esters, phosphonates, and epoxy esters, and the mass of the plasticizer is 2%-6% of the mass of the solid component.

4. The preparation method according to claim 1, characterized in that, The dispersant is selected from one or more of organic small molecule dispersants and organic polymer dispersants, and the mass of the dispersant is 0.5%-3% of the mass of the solid phase component.

5. A large-size, high-strength ceramic substrate prepared by the preparation method described in any one of claims 1-4.

Images