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

Abstract

The present invention relates to the field of ceramic substrate technology and proposes an alumina high-temperature co-fired multilayer ceramic substrate and its preparation method. The alumina high-temperature co-fired multilayer ceramic substrate comprises the following raw materials by weight: 80-90 parts alumina, 3-6 parts reinforcing agent, 2-5 parts sintering aid, 85-95 parts solvent, 6-12 parts binder, and 0.5-1.5 parts dispersant. The reinforcing agent includes yttrium oxide-coated silicon carbide and copper oxide. This technical solution solves the problem of insufficient strength of alumina high-temperature co-fired multilayer ceramic substrates caused by long-term high-temperature sintering in a low-viscosity liquid phase in related technologies.

Description

Technical Field

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

[0002] Alumina high-temperature co-fired multilayer ceramic substrates are widely used in fields such as high-power micro-assembly circuits due to their good chemical stability. However, the current problem of insufficient bending strength of alumina high-temperature co-fired multilayer ceramic substrates is that additives are usually required to promote the sintering process during the preparation of alumina high-temperature co-fired multilayer ceramic substrates. When these sintering additives 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 period of time, improve the sintering performance of the substrate, 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, limiting the improvement of the bending strength of alumina high-temperature co-fired multilayer ceramic substrates.

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

[0004] The present invention provides an alumina high-temperature co-fired multilayer ceramic substrate and a preparation method thereof, which solves the problem in the related art that the alumina high-temperature co-fired multilayer ceramic substrate has insufficient strength due to long-term high-temperature sintering of a low-viscosity liquid phase.

[0005] The technical solutions of the present invention are as follows:

[0006] The present invention proposes an alumina high-temperature co-fired multi-layer 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 comprises yttrium oxide-coated silicon carbide and copper oxide.

[0007] As a further technical solution, the solvent includes water.

[0008] As a further technical solution, the preparation method of yttrium oxide-coated silicon carbide comprises the following steps:

[0009] Silicon carbide and yttrium nitrate hexahydrate solution are stirred and mixed, dried, and heat-treated to obtain the yttrium oxide-coated silicon carbide.

[0010] As a further technical solution, the raw materials of the yttrium nitrate hexahydrate solution include yttrium nitrate hexahydrate and water;

[0011] The mass ratio of the silicon carbide, yttrium nitrate hexahydrate and water is 10:3:20-30.

[0012] As a further technical solution, the rotation speed during the stirring and mixing is 800-900 rpm, and the time is 35-45 minutes.

[0013] As a further technical solution, the drying is vacuum drying, and the temperature of the vacuum drying is 75-90°C;

[0014] The heat treatment temperature is 650-680° C. and the time is 5-6 hours.

[0015] In the reinforcing agent of the alumina high-temperature co-fired multi-layer ceramic substrate of the present invention, when yttrium oxide-coated silicon carbide is prepared, as the drying process proceeds, the solvent gradually evaporates, and the yttrium nitrate concentration in the solution continues to increase. When it reaches a supersaturated state, yttrium nitrate crystallizes and precipitates on the surface of the silicon carbide, forming a coating layer of yttrium nitrate on the surface of the silicon carbide. During the heat treatment stage, the yttrium nitrate on the surface of the silicon carbide is converted into yttrium oxide, thereby achieving the coating of the silicon carbide with yttrium oxide.

[0016] As a further technical solution, the silicon carbide includes silicon carbide whiskers and silicon carbide particles.

[0017] As a further technical solution, the mass ratio of the silicon carbide whiskers to the silicon carbide particles is 1:5-7.

[0018] The present invention is based on the use of yttrium oxide-coated silicon carbide and copper oxide as reinforcing agents for alumina high-temperature co-fired multi-layer ceramic substrates. When yttrium oxide is coated on silicon carbide, the silicon carbide further adopts a mixture of silicon carbide particles and silicon carbide whiskers. The silicon carbide particles are used to induce crack deflection, and the silicon carbide whiskers achieve crack bridging and pull-out toughening. The combination of the two greatly consumes crack propagation energy, prevents rapid crack propagation, and improves the fracture toughness of the alumina high-temperature co-fired multi-layer ceramic substrate.

[0019] As a further technical solution, the length of the silicon carbide whisker is 12-15 μm and the diameter is 0.5-1 μm.

[0020] The length of the silicon carbide whisker may be, for example, 12 μm, 13 μm, 14 μm, or 15 μm, and the diameter of the silicon carbide whisker may be, for example, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, or 1 μm.

[0021] As a further technical solution, the particle size of the silicon carbide particles is 50-100 nm.

[0022] The particle size of the silicon carbide particles can be, for example, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm. Preferably, the particle size of the silicon carbide particles is 80 nm.

[0023] As a further technical solution, the mass ratio of the yttrium oxide-coated silicon carbide to the copper oxide is 8:2~5, for example, it can be 8:2, 8:3, 8:4, 8:5. Preferably, the mass ratio of the yttrium oxide-coated silicon carbide to the copper oxide is 8:3.

[0024] As a further technical solution, the sintering aid includes one or more of La2O3, B2O3, and CaO.

[0025] As a further technical solution, the dispersant includes one or both of potassium polyacrylate and sodium polyacrylate.

[0026] Among the raw materials of the alumina high-temperature co-fired multi-layer ceramic substrate of the present invention, potassium polyacrylate and / or sodium polyacrylate are used as dispersants for the alumina high-temperature co-fired multi-layer ceramic substrate, thereby improving the dispersion uniformity of each raw material, reducing internal defects of the ceramic substrate caused by agglomeration of the raw materials, and ensuring the mechanical properties of the alumina high-temperature co-fired multi-layer ceramic substrate.

[0027] As a further technical solution, the binder includes one or both of polyacrylamide and polyvinyl alcohol.

[0028] Among the raw materials of the alumina high-temperature co-fired multi-layer 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 easy to mix evenly with the inorganic raw materials of the ceramic substrate, and is more easily decomposed and volatilized during the sintering process, thereby reducing the interference of residual impurities on the performance of the alumina high-temperature co-fired multi-layer ceramic substrate.

[0029] The present invention also provides a method for preparing the alumina high-temperature co-fired multi-layer ceramic substrate, which comprises the following steps:

[0030] S1. Mixing alumina, a reinforcing agent, a sintering aid, a dispersant, and a solvent to obtain a premix;

[0031] S2, adding a binder to the premix, mixing, tape casting, and drying to obtain a green porcelain sheet;

[0032] S3, after punching the green ceramic sheet, performing surface printing, lamination, upper and lower conductive bonding, cutting, sintering, and cooling to obtain the alumina high temperature co-fired multi-layer ceramic substrate.

[0033] The working principle and beneficial effects of the present invention are:

[0034] In the present invention, yttrium oxide-coated silicon carbide and copper oxide are added as reinforcing agents to the alumina ceramic substrate, significantly improving the flexural strength of the alumina high-temperature co-fired multilayer ceramic substrate. This overcomes the limitation of the prior art in improving the strength of alumina high-temperature co-fired multilayer ceramic substrates due to the low-viscosity liquid phase. The present invention utilizes yttrium oxide-coated silicon carbide and copper oxide as reinforcing agents in synergy. The copper oxide forms a liquid phase during sintering, filling the pores and improving the density of the ceramic. The introduction of yttrium oxide-coated silicon carbide compensates for the defect that the low-viscosity liquid phase formed by copper oxide is not conducive to improving the strength of the alumina ceramic substrate during long-term high-temperature sintering. At the same time, the yttrium oxide-coated silicon carbide effectively improves the dispersion of silicon carbide in the alumina matrix, and yttrium oxide forms yttrium aluminum garnet bridges between silicon carbide and alumina, making the internal skeleton of the ceramic more solid. Therefore, the addition of yttrium oxide-coated silicon carbide and copper oxide as reinforcing agents to the alumina ceramic substrate synergistically improves the flexural strength of the alumina high-temperature co-fired multilayer ceramic substrate. DETAILED DESCRIPTION

[0035] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] In the following examples and comparative examples, the particle size of aluminum oxide 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.

[0037] Example 1

[0038] An alumina high-temperature co-fired multilayer ceramic substrate comprises the following raw materials in parts by weight: 80 parts alumina, 3 parts reinforcing agent, 1 part La2O3, 1 part CaO, 85 parts water, 6 parts polyvinyl alcohol, and 0.5 part sodium polyacrylate; the reinforcing agent is yttrium oxide-coated silicon carbide and copper oxide in a mass ratio of 8:2;

[0039] The preparation method of yttrium oxide coated silicon carbide comprises the following steps:

[0040] Yttrium nitrate hexahydrate and water are mixed to obtain a yttrium nitrate hexahydrate solution, silicon carbide and the yttrium nitrate hexahydrate solution are stirred and mixed at a rotation speed of 800 rpm for 35 minutes, vacuum dried at 75°C to remove moisture, and heat treated in a muffle furnace at 650°C for 6 hours to obtain yttrium oxide-coated silicon carbide; wherein the mass ratio of silicon carbide, yttrium nitrate hexahydrate, and water is 10:3:20; and the silicon carbide is silicon carbide particles (particle size 100 nm);

[0041] A method for preparing a high-temperature co-fired alumina multilayer ceramic substrate comprises the following steps:

[0042] S1, mixing alumina, a reinforcing agent, La2O3, CaO, sodium polyacrylate and water to obtain a premix;

[0043] S2, adding polyvinyl alcohol to the premix, mixing, tape casting, and drying to obtain a green porcelain sheet;

[0044] S3. After punching the green ceramic sheet, surface printing, lamination of 30 layers, upper and lower conductive bonding, cutting, sintering at 1600°C for 4 hours, and cooling, an alumina high-temperature co-fired multilayer ceramic substrate is obtained.

[0045] Example 2

[0046] An alumina high-temperature co-fired multilayer ceramic substrate comprises the following raw materials in parts by weight: 90 parts alumina, 6 parts reinforcing agent, 5 parts La2O3, 95 parts water, 12 parts polyvinyl alcohol, and 1.5 parts sodium polyacrylate; the reinforcing agent is yttrium oxide-coated silicon carbide and copper oxide in a mass ratio of 8:5;

[0047] The preparation method of yttrium oxide coated silicon carbide comprises the following steps:

[0048] Yttrium nitrate hexahydrate and water are mixed to obtain a yttrium nitrate hexahydrate solution, silicon carbide and the yttrium nitrate hexahydrate solution are stirred and mixed at a rotation speed of 900 rpm for 45 minutes, vacuum dried at 90°C to remove moisture, and heat treated in a muffle furnace at 680°C for 5 hours to obtain yttrium oxide-coated silicon carbide; wherein the mass ratio of silicon carbide, yttrium nitrate hexahydrate, and water is 10:3:30; and the silicon carbide is silicon carbide particles (particle size 50 nm);

[0049] A method for preparing a high-temperature co-fired alumina multilayer ceramic substrate comprises the following steps:

[0050] S1, mixing alumina, a reinforcing agent, La2O3, sodium polyacrylate and water to obtain a premix;

[0051] S2, adding polyvinyl alcohol to the premix, mixing, tape casting, and drying to obtain a green porcelain sheet;

[0052] S3. After punching the green ceramic sheet, surface printing, lamination of 30 layers, upper and lower conductive bonding, cutting, sintering at 1600°C for 4 hours, and cooling, an alumina high-temperature co-fired multilayer ceramic substrate is obtained.

[0053] Example 3

[0054] An alumina high-temperature co-fired multilayer ceramic substrate comprises the following raw materials in parts by weight: 85 parts alumina, 5 parts reinforcing agent, 3 parts La2O3, 90 parts water, 8 parts polyvinyl alcohol, and 1 part sodium polyacrylate; the reinforcing agent is yttrium oxide-coated silicon carbide and copper oxide in a mass ratio of 8:3;

[0055] The preparation method of yttrium oxide coated silicon carbide comprises the following steps:

[0056] Yttrium nitrate hexahydrate and water are mixed to obtain a yttrium nitrate hexahydrate solution, silicon carbide and the yttrium nitrate hexahydrate solution are stirred and mixed at a rotation speed of 900 rpm for 35 minutes, vacuum dried at 80°C to remove moisture, and heat treated in a muffle furnace at 650°C for 6 hours to obtain yttrium oxide-coated silicon carbide; wherein the mass ratio of silicon carbide, yttrium nitrate hexahydrate, and water is 10:3:25; and the silicon carbide is silicon carbide particles (particle size 80 nm);

[0057] A method for preparing a high-temperature co-fired alumina multilayer ceramic substrate comprises the following steps:

[0058] S1, mixing alumina, a reinforcing agent, La2O3, sodium polyacrylate and water to obtain a premix;

[0059] S2, adding polyvinyl alcohol to the premix, mixing, tape casting, and drying to obtain a green porcelain sheet;

[0060] S3. After punching the green ceramic sheet, surface printing, lamination of 30 layers, upper and lower conductive bonding, cutting, sintering at 1600°C for 4 hours, and cooling, an alumina high-temperature co-fired multilayer ceramic substrate is obtained.

[0061] Example 4

[0062] The only difference between this embodiment and embodiment 3 is that the silicon carbide is a silicon carbide whisker (length 12 μm, diameter 0.5 μm).

[0063] Example 5

[0064] The only difference between this embodiment and embodiment 3 is that the silicon carbide is 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.

[0065] Example 6

[0066] The only difference between this embodiment and embodiment 3 is that the silicon carbide is silicon carbide whiskers (length 15 μm, diameter 1 μm) and silicon carbide particles (particle size 80 nm) with a mass ratio of 1:7.

[0067] Comparative Example 1

[0068] The only difference between this comparative example and Example 3 is that the reinforcing agent is copper oxide.

[0069] Comparative Example 2

[0070] The only difference between this comparative example and Example 3 is that the reinforcing agent is yttria-coated silicon carbide.

[0071] Comparative Example 3

[0072] The only difference between this comparative example and Example 3 is that the yttrium oxide-coated silicon carbide is replaced by silicon carbide.

[0073] Experimental Example 1

[0074] According to the test method specified in GB / T 6569-2006 "Test Method for Flexural Strength of Fine Ceramics", the alumina high-temperature co-fired multi-layer ceramic substrates prepared in Examples 1-6 and Comparative Examples 1-3 were tested for flexural strength using three-point bending. The results are shown in Table 1.

[0075] Table 1 Performance test results

[0076]

[0077] Compared with Comparative Examples 1 to 3, the bending strength of the alumina high-temperature co-fired multi-layer ceramic substrates obtained in Examples 1 to 6 is higher, indicating that the addition of yttrium oxide-coated silicon carbide and copper oxide to the alumina high-temperature co-fired multi-layer ceramic substrate significantly improves the bending strength of the alumina high-temperature co-fired multi-layer ceramic substrate.

[0078] Experimental Example 2

[0079] According to the specimen requirements and test methods of GB / T 23806-2009 "Fine Ceramics Fracture Toughness Test Method Single Edge Precracked Beam (SEPB) Method", the fracture toughness tests were performed on the alumina multilayer ceramic substrates prepared in Examples 3 to 6. The test results are shown in Table 2.

[0080] Table 2 Performance test results

[0081]

[0082] Compared with Examples 3 and 4, the alumina high-temperature co-fired multi-layer ceramic substrates obtained in Examples 5 and 6 have higher fracture toughness, indicating that when the yttrium oxide-coated silicon carbide is silicon carbide whiskers and silicon carbide particles, the alumina high-temperature co-fired multi-layer ceramic substrates have better fracture toughness.

[0083] The above are only 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 principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An alumina high temperature co-fired multilayer ceramic substrate, characterized in that: The raw materials include the following parts by weight: 80-90 parts of aluminum oxide, 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; The silicon carbide includes silicon carbide whiskers and silicon carbide particles.

2. The alumina high temperature co-fired multi-layer ceramic substrate according to claim 1, characterized in that: The preparation method of the yttrium oxide-coated silicon carbide comprises the following steps: Silicon carbide and yttrium nitrate hexahydrate solution are stirred and mixed, dried, and heat-treated to obtain the yttrium oxide-coated silicon carbide.

3. The alumina high temperature co-fired multi-layer ceramic substrate 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, characterized in that: The stirring and mixing is performed at a speed of 800-900 rpm for 35-45 min. The drying is vacuum drying, and the temperature of the vacuum drying is 75-90°C; The heat treatment temperature is 650-680° C. and the time is 5-6 hours.

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

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

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

8. The alumina high temperature co-fired multi-layer ceramic substrate 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.

9. A method for preparing an alumina high-temperature co-fired multi-layer ceramic substrate, for preparing the alumina high-temperature co-fired multi-layer ceramic substrate according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Mixing alumina, a reinforcing agent, a sintering aid, a dispersant, and a solvent to obtain a premix; S2, adding a binder to the premix, mixing, tape casting, and drying to obtain a green porcelain sheet; S3, after punching the green ceramic sheet, performing surface printing, lamination, upper and lower conductive bonding, cutting, sintering, and cooling to obtain the alumina high temperature co-fired multi-layer ceramic substrate.

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