Alumina high-temperature co-fired multilayer ceramic substrate and preparation method thereof

Abstract

The invention relates to the technical field of ceramic substrates, and provides an aluminum oxide high-temperature co-fired multilayer ceramic substrate and a preparation method thereof. The aluminum oxide high-temperature co-fired multilayer ceramic substrate comprises the following raw materials in parts by weight: 80-90 parts of aluminum oxide, 3-6 parts of a reinforcing agent, 2-5 parts of a sintering aid, 85-95 parts of a solvent, 6-12 parts of a binder and 0.5-1.5 parts of a dispersing agent, the reinforcing agent comprises yttrium oxide coated silicon carbide and copper oxide. According to the technical scheme, the problem that the strength of the aluminum oxide high-temperature co-fired multilayer ceramic substrate is insufficient due to long-time high-temperature sintering of a low-viscosity liquid phase in related technologies is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic substrates, and specifically, to a high-temperature co-fired multi-layer alumina ceramic substrate and a preparation method thereof. Background Art

[0002] Due to characteristics such as good chemical stability, high-temperature co-fired multi-layer alumina ceramic substrates are widely used in fields such as high-power micro-assembly circuits. However, at present, high-temperature co-fired multi-layer alumina ceramic substrates still have the problem of insufficient bending strength. The reason is that during the preparation process of high-temperature co-fired multi-layer alumina ceramic substrates, additives are usually needed to promote the sintering process. When these sintering aids form a low-viscosity liquid phase during the high-temperature sintering stage, they can help alumina particles migrate and diffuse better to a certain extent in a short time, improve the sintering performance of the matrix, and increase the density. However, during the long-term high-temperature co-firing process, the low-viscosity liquid phase will cause problems such as excessive grain growth and increased pores, which limits the improvement of the bending strength of high-temperature co-fired multi-layer alumina ceramic substrates.

[0003] Therefore, it is necessary to solve the problem that the strength improvement of alumina ceramic substrates is restricted during long-term high-temperature sintering of the low-viscosity liquid phase, and obtain a high-strength high-temperature co-fired multi-layer alumina ceramic substrate. Summary of the Invention

[0004] The present invention provides a high-temperature co-fired multi-layer alumina ceramic substrate and a preparation method thereof, which solve the problem of insufficient strength of high-temperature co-fired multi-layer alumina ceramic substrates caused by long-term high-temperature sintering of a low-viscosity liquid phase in the related art.

[0005] The technical solution of the present invention is as follows: The present invention provides a high-temperature co-fired multi-layer alumina ceramic substrate, comprising the following raw materials in parts by weight: 80-90 parts of alumina, 3-6 parts of a reinforcing agent, 2-5 parts of a sintering aid, 85-95 parts of a solvent, 6-12 parts of a binder, and 0.5-1.5 parts of a dispersant; the reinforcing agent includes yttrium oxide-coated silicon carbide and copper oxide.

[0006] As a further technical solution, the solvent includes water.

[0007] As a further technical solution, the preparation method of the yttrium oxide-coated silicon carbide includes the following steps: Stir and mix silicon carbide and yttrium nitrate hexahydrate solution, dry, and perform heat treatment to obtain the yttrium oxide-coated silicon carbide.

[0008] As a further technical solution, the raw materials of the yttrium nitrate hexahydrate solution include yttrium nitrate hexahydrate and water; The mass ratio of the silicon carbide, yttrium nitrate hexahydrate, and water is 10:3:20-30.

[0009] As a further technical solution, the rotation speed during stirring and mixing is 800 - 900 rpm, and the time is 35 - 45 min.

[0010] As a further technical solution, the drying is vacuum drying, and the temperature of the vacuum drying is 75 - 90 °C; The temperature of the heat treatment is 650 - 680 °C, and the time is 5 - 6 h.

[0011] In the reinforcing agent of the alumina co-fired multi-layer ceramic substrate of the present invention, when preparing yttrium oxide-coated silicon carbide, as the drying process proceeds, the solvent gradually volatilizes, and the concentration of yttrium nitrate in the solution continuously increases. When it reaches the supersaturated state, yttrium nitrate crystallizes and precipitates on the surface of silicon carbide, forming a coating layer of yttrium nitrate on the surface of silicon carbide. During the heat treatment stage, yttrium nitrate on the surface of silicon carbide is converted into yttrium oxide, thus realizing the coating of silicon carbide with yttrium oxide.

[0012] As a further technical solution, the silicon carbide includes silicon carbide whiskers and silicon carbide particles.

[0013] As a further technical solution, the mass ratio of the silicon carbide whiskers to the silicon carbide particles is 1:5 - 7.

[0014] Based on yttrium oxide-coated silicon carbide and copper oxide as the reinforcing agent of the alumina co-fired multi-layer ceramic substrate in the present invention, when coating silicon carbide with yttrium oxide, the silicon carbide further adopts a mixture of silicon carbide particles and silicon carbide whiskers. The silicon carbide particles initiate crack deflection, and the silicon carbide whiskers achieve crack bridging and pull-out toughening. The two cooperate to greatly consume the crack propagation energy, prevent the rapid spread of cracks, and improve the fracture toughness of the alumina co-fired multi-layer ceramic substrate.

[0015] As a further technical solution, the length of the silicon carbide whiskers is 12 - 15 μm, and the diameter is 0.5 - 1 μm.

[0016] The length of the silicon carbide whiskers can be, for example, 12 μm, 13 μm, 14 μm, 15 μm, and the diameter of the silicon carbide whiskers can be, for example, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm.

[0017] As a further technical solution, the particle size of the silicon carbide particles is 50 - 100 nm.

[0018] The particle size of the silicon carbide particles can be, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm. Preferably, the particle size of the silicon carbide particles is 80 nm.

[0019] As a further technical solution, the mass ratio of yttrium oxide-coated silicon carbide to copper oxide is 8:2 to 5, for example, it can be 8:2, 8:3, 8:4, 8:5. Preferably, the mass ratio of yttrium oxide-coated silicon carbide to copper oxide is 8:3.

[0020] As a further technical solution, the sintering aid includes one or more of La2O3, B2O3, and CaO.

[0021] As a further technical solution, the dispersant includes one or both of potassium polyacrylate and sodium polyacrylate.

[0022] In the raw materials of the alumina co-fired multilayer ceramic substrate of the present invention, potassium polyacrylate and / or sodium polyacrylate are used as the dispersant of the alumina co-fired multilayer ceramic substrate, which improves the dispersion uniformity of each raw material, reduces the internal defects formed in the ceramic substrate due to raw material agglomeration, and ensures the mechanical properties of the alumina co-fired multilayer ceramic substrate.

[0023] As a further technical solution, the binder includes one or both of polyacrylamide and polyvinyl alcohol.

[0024] In the raw materials of the alumina co-fired multilayer ceramic substrate of the present invention, the binder is a water-soluble polymer, such as polyacrylamide, polyvinyl alcohol, etc., which has good water solubility, is convenient for mixing evenly with the inorganic raw materials of the ceramic substrate, and is more easily decomposed and volatilized during the sintering process, reducing the interference of residual impurities on the performance of the alumina co-fired multilayer ceramic substrate.

[0025] The present invention also provides a method for preparing the above-mentioned alumina co-fired multilayer ceramic substrate, which is used to prepare the above-mentioned alumina co-fired multilayer ceramic substrate, and includes the following steps: S1. Mix alumina, reinforcing agent, sintering aid, dispersant and solvent to obtain a premix; S2. Add a binder to the premix for mixing, tape casting, drying, to obtain a green ceramic sheet; S3. After punching the green ceramic sheet, perform surface printing, lamination, through-hole connection, cutting, sintering, and cooling to obtain the alumina co-fired multilayer ceramic substrate.

[0026] The working principle and beneficial effects of the present invention are: In the present invention, yttrium oxide-coated silicon carbide and copper oxide are added as reinforcing agents for the alumina ceramic substrate, significantly improving the flexural strength of the high-temperature co-fired multi-layer alumina ceramic substrate. Breaking through the limitations of the prior art in improving the strength of the high-temperature co-fired multi-layer alumina ceramic substrate due to the low-viscosity liquid phase, the present invention utilizes yttrium oxide-coated silicon carbide and copper oxide as synergistic reinforcing agents. Copper oxide forms a liquid phase during sintering, filling pores to improve the density of the ceramic, and introducing yttrium oxide-coated silicon carbide to make up for the defect that the low-viscosity liquid phase formed by copper oxide is not conducive to the strength improvement of the alumina ceramic substrate during long-term high-temperature sintering. At the same time, yttrium oxide-coated silicon carbide effectively improves the dispersion of silicon carbide in the alumina matrix, and yttrium oxide forms a yttrium aluminum garnet bridge between silicon carbide and alumina, promoting the internal skeleton of the ceramic to be more solid. Therefore, adding yttrium oxide-coated silicon carbide and copper oxide as reinforcing agents for the alumina ceramic substrate, the two work synergistically to improve the flexural strength of the high-temperature co-fired multi-layer alumina ceramic substrate. Detailed Embodiments

[0027] The following will describe the technical solutions in the embodiments of the present invention clearly and completely in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0028] In the following examples and comparative examples, the particle size of alumina is 30 μm, the particle size of copper oxide is 10 μm, the weight-average molecular weight of polyvinyl alcohol is 10,000, the particle size of La2O3 is 100 nm, and the particle size of CaO is 5 μm.

[0029] Example 1 A high-temperature co-fired multi-layer alumina ceramic substrate, comprising the following raw materials in parts by weight: 80 parts of alumina, 3 parts of reinforcing agent, 1 part of La2O3, 1 part of CaO, 85 parts of water, 6 parts of polyvinyl alcohol, 0.5 part of sodium polyacrylate; the reinforcing agent is yttrium oxide-coated silicon carbide and copper oxide with a mass ratio of 8:2; The preparation method of yttrium oxide-coated silicon carbide includes the following steps: Mix yttrium nitrate hexahydrate and water to obtain a yttrium nitrate hexahydrate solution. Stir and mix silicon carbide and the yttrium nitrate hexahydrate solution at a rotation speed of 800 rpm for 35 min, vacuum dry to remove moisture at 75 °C, and heat-treat in a muffle furnace at 650 °C for 6 h to obtain yttrium oxide-coated silicon carbide; wherein, the mass ratio of silicon carbide, yttrium nitrate hexahydrate and water is 10:3:20; the silicon carbide is silicon carbide particles (particle size 100 nm); The preparation method of the high-temperature co-fired multi-layer alumina ceramic substrate includes the following steps: S1. Mix alumina, a reinforcing agent, La2O3, CaO, sodium polyacrylate, and water to obtain a premix. S2. Add polyvinyl alcohol to the premix, mix, cast into a film, dry, and obtain a green ceramic sheet. S3. After drilling holes in the green ceramic sheet, perform surface printing, stack 30 layers, conduct electricity up and down, cut, sinter at 1600 °C for 4 h, and cool to obtain a high-temperature co-fired multi-layer alumina ceramic substrate.

[0030] Example 2 The high-temperature co-fired multi-layer alumina ceramic substrate comprises the following raw materials in parts by weight: 90 parts of alumina, 6 parts of a reinforcing agent, 5 parts of La2O3, 95 parts of water, 12 parts of polyvinyl alcohol, and 1.5 parts of sodium polyacrylate; the reinforcing agent is yttrium oxide-coated silicon carbide and copper oxide with a mass ratio of 8:5. The preparation method of yttrium oxide-coated silicon carbide comprises the following steps: Mix yttrium nitrate hexahydrate and water to obtain a yttrium nitrate hexahydrate solution. Stir and mix silicon carbide and the yttrium nitrate hexahydrate solution at a rotation speed of 900 rpm for 45 min, vacuum dry at 90 °C to remove moisture, place in a muffle furnace, and heat-treat at 680 °C for 5 h to obtain yttrium oxide-coated silicon carbide; wherein, the mass ratio of silicon carbide, yttrium nitrate hexahydrate, and water is 10:3:30; the silicon carbide is silicon carbide particles (particle size 50 nm). The preparation method of the high-temperature co-fired multi-layer alumina ceramic substrate comprises the following steps: S1. Mix alumina, a reinforcing agent, La2O3, sodium polyacrylate, and water to obtain a premix. S2. Add polyvinyl alcohol to the premix, mix, cast into a film, dry, and obtain a green ceramic sheet. S3. After drilling holes in the green ceramic sheet, perform surface printing, stack 30 layers, conduct electricity up and down, cut, sinter at 1600 °C for 4 h, and cool to obtain a high-temperature co-fired multi-layer alumina ceramic substrate.

[0031] Example 3 The high-temperature co-fired multi-layer alumina ceramic substrate comprises the following raw materials in parts by weight: 85 parts of alumina, 5 parts of a reinforcing agent, 3 parts of La2O3, 90 parts of water, 8 parts of polyvinyl alcohol, and 1 part of sodium polyacrylate; the reinforcing agent is yttrium oxide-coated silicon carbide and copper oxide with a mass ratio of 8:3. The preparation method of yttrium oxide-coated silicon carbide comprises the following steps: Yttrium nitrate hexahydrate and water were mixed to obtain a yttrium nitrate hexahydrate solution. Silicon carbide and the yttrium nitrate hexahydrate solution were stirred and mixed at a rotation speed of 900 rpm for 35 min, and then dried under vacuum at 80 °C to remove moisture. The obtained product was heat-treated in a muffle furnace at 650 °C for 6 h to obtain silicon carbide coated with yttrium oxide. Among them, the mass ratio of silicon carbide, yttrium nitrate hexahydrate and water was 10:3:25; the silicon carbide was silicon carbide particles (particle size 80 nm). A preparation method of a high-temperature co-fired multi-layer alumina ceramic substrate includes the following steps: S1. Alumina, a reinforcing agent, La2O3, sodium polyacrylate and water were mixed to obtain a premix; S2. Polyvinyl alcohol was added to the premix for mixing, and then tape-cast, dried to obtain a green ceramic sheet; S3. After the green ceramic sheet was punched, it was subjected to surface printing, laminated 30 layers, upper and lower conduction, cutting, sintered at 1600 °C for 4 h, and then cooled to obtain a high-temperature co-fired multi-layer alumina ceramic substrate.

[0032] Example 4 The difference between this example and Example 3 is only that the silicon carbide is silicon carbide whiskers (length 12 μm, diameter 0.5 μm).

[0033] Example 5 The difference between this example and Example 3 is only that the silicon carbide is a mixture of silicon carbide whiskers (length 12 μm, diameter 0.5 μm) and silicon carbide particles (particle size 80 nm) with a mass ratio of 1:5.

[0034] Example 6 The difference between this example and Example 3 is only that the silicon carbide is a mixture of silicon carbide whiskers (length 15 μm, diameter 1 μm) and silicon carbide particles (particle size 80 nm) with a mass ratio of 1:7.

[0035] Comparative Example 1 The difference between this comparative example and Example 3 is only that the reinforcing agent is copper oxide.

[0036] Comparative Example 2 The difference between this comparative example and Example 3 is only that the reinforcing agent is silicon carbide coated with yttrium oxide.

[0037] Comparative Example 3 The difference between this comparative example and Example 3 is only that the silicon carbide coated with yttrium oxide is replaced with silicon carbide.

[0038] Experimental Example 1 According to the test method specified in GB / T 6569-2006 "Test Method for Flexural Strength of Fine Ceramics", the flexural strength tests of the high-temperature co-fired multi-layer alumina ceramic substrates prepared in Examples 1-6 and Comparative Examples 1-3 were carried out respectively. The test method used three-point bending, and the results are shown in Table 1.

[0039] Table 1 Performance Test Results

[0040] Compared with Comparative Examples 1 to 3, the alumina co-fired multilayer ceramic substrates obtained in Examples 1 to 6 have higher flexural strength, indicating that the addition of yttrium oxide-coated silicon carbide and copper oxide to the alumina co-fired multilayer ceramic substrates significantly improves the flexural strength of the alumina co-fired multilayer ceramic substrates.

[0041] Experimental Example 2 According to the specimen requirements and measurement methods of GB / T 23806-2009 "Test Method for Fracture Toughness of Fine Ceramics - Single Edge Pre-Cracked Beam (SEPB) Method", the fracture toughness of the alumina multilayer ceramic substrates prepared in Examples 3 to 6 was tested respectively, and the test results are shown in Table 2.

[0042] Table 2 Performance Test Results

[0043] Compared with Examples 3 to 4, the alumina co-fired multilayer ceramic substrates obtained in Examples 5 to 6 have higher fracture toughness, indicating that when the silicon carbide in the yttrium oxide-coated silicon carbide is silicon carbide whiskers and silicon carbide particles, the alumina co-fired multilayer ceramic substrates have better fracture toughness.

[0044] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-temperature co-fired multi-layer ceramic substrate made of alumina, characterized in that, It comprises the following raw materials in parts by weight: 80 - 90 parts of alumina, 3 - 6 parts of reinforcing agent, 2 - 5 parts of sintering aid, 85 - 95 parts of solvent, 6 - 12 parts of binder, and 0.5 - 1.5 parts of dispersant; The reinforcing agent includes yttrium oxide - coated silicon carbide and copper oxide.

2. The high-temperature co-fired multi-layer ceramic substrate made of alumina according to claim 1, wherein, The preparation method of the yttrium oxide - coated silicon carbide includes the following steps: Mix silicon carbide and yttrium nitrate hexahydrate solution by stirring, dry, and perform heat treatment to obtain the yttrium oxide - coated silicon carbide.

3. The high-temperature co-fired multi-layer ceramic substrate made of alumina according to claim 2, characterized in that, The raw materials of the yttrium nitrate hexahydrate solution include yttrium nitrate hexahydrate and water; The mass ratio of the silicon carbide, yttrium nitrate hexahydrate, and water is 10:3:20 - 30.

4. The alumina high-temperature co-fired multi-layer ceramic substrate according to claim 2, wherein The rotation speed during the stirring and mixing is 800 - 900 rpm, and the time is 35 - 45 min; The drying is vacuum drying, and the temperature of the vacuum drying is 75 - 90 °C; The temperature of the heat treatment is 650 - 680 °C, and the time is 5 - 6 h.

5. The alumina high-temperature co-fired multi-layer ceramic substrate according to claim 2, wherein The silicon carbide includes silicon carbide whiskers and silicon carbide particles.

6. The high-temperature co-fired multi-layer ceramic substrate made of alumina according to claim 5, characterized in that, The mass ratio of the silicon carbide whiskers and the silicon carbide particles is 1:5 - 7.

7. The high-temperature co-fired multi-layer ceramic substrate made of alumina according to claim 5, characterized in that, The length of the silicon carbide whiskers is 12 - 15 μm, and the diameter is 0.5 - 1 μm; The particle size of the silicon carbide particles is 50 - 100 nm.

8. The high-temperature co-fired multi-layer ceramic substrate made of alumina according to claim 1, wherein The mass ratio of the yttrium oxide - coated silicon carbide and the copper oxide is 8:2 - 5.

9. The high-temperature co-fired multi-layer ceramic substrate made of alumina according to claim 1, characterized in that, The sintering aid includes one or more of La2O3, B2O3, and CaO; The dispersant includes one or both of potassium polyacrylate and sodium polyacrylate; The binder includes one or both of polyacrylamide and polyvinyl alcohol.

10. A preparation method of a high-temperature co-fired multi-layer ceramic substrate of alumina, which is used to prepare a high-temperature co-fired multi-layer ceramic substrate of alumina according to any one of claims 1 to 9, characterized in that, It includes the following steps: S1. Mix alumina, reinforcing agent, sintering aid, dispersant, and solvent to obtain a premix; S2. Add a binder to the premix for mixing, tape - casting, and drying to obtain a green ceramic sheet; S3. After drilling the green ceramic sheet, perform surface printing, lamination, through - hole connection, cutting, sintering, and cooling to obtain the alumina high - temperature co - fired multilayer ceramic substrate.

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