A high-resistivity aluminum nitride ceramic substrate and preparation method thereof

Abstract

The present invention relates to the field of ceramic substrate technology and proposes a high-resistivity aluminum nitride ceramic substrate and its preparation method. The high-resistivity aluminum nitride ceramic substrate comprises the following raw materials by weight: 75-85 parts aluminum nitride powder, 4-8 parts sintering aid, 3-6 parts functional additive, 8-12 parts binder, 1-5 parts plasticizer, 1-3 parts dispersant, and 65-75 parts solvent. The functional additive comprises carbide, tungsten oxide, and yttria-stabilized zirconia in a mass ratio of 1-9:2:1. This technical solution overcomes the problem of insufficient strength of aluminum nitride ceramic substrates in related technologies.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic substrates, and in particular to a high-resistivity aluminum nitride ceramic substrate and a preparation method thereof. Background Art

[0002] Aluminum nitride ceramic substrates are widely used in automotive electronics, aerospace, and other fields. In this field, especially in the battery management systems of electric vehicles, aluminum nitride ceramic substrates provide reliable electrical isolation and heat dissipation, helping to improve battery efficiency and safety. In practical applications, aluminum nitride ceramic substrates are often subject to mechanical stress. For example, during the assembly of electronic equipment, substrates need to be cut, drilled, and mounted. In the aerospace field, equipment is subjected to complex mechanical stresses during flight due to factors such as vibration and air pressure fluctuations. Under the influence of frequent mechanical stress, existing aluminum nitride ceramic substrates lack strength, which seriously affects their reliability and stability in practical applications, increasing equipment failure rates and repair costs. This problem is particularly limiting the further application of aluminum nitride ceramic substrates in fields with extremely high reliability requirements, such as aerospace and medical equipment.

[0003] Therefore, it is necessary to produce a high-strength aluminum nitride ceramic substrate to meet higher requirements in practical applications. Summary of the Invention

[0004] The present invention provides a high-resistivity aluminum nitride ceramic substrate and a preparation method thereof, which solves the problem of insufficient strength of the aluminum nitride ceramic substrate in the related art.

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

[0006] The present invention provides a high-resistivity aluminum nitride ceramic substrate, comprising the following raw materials in parts by weight: 75-85 parts of aluminum nitride powder, 4-8 parts of a sintering aid, 3-6 parts of a functional additive, 8-12 parts of a binder, 1-5 parts of a plasticizer, 1-3 parts of a dispersant, and 65-75 parts of a solvent;

[0007] The functional additives include carbide, tungsten oxide, and yttria-stabilized zirconia in a mass ratio of 1 to 9:2:1.

[0008] As a further technical solution, the particle size of the aluminum nitride powder is 1-3 μm, for example, 1 μm, 2 μm, 3 μm, preferably 2 μm.

[0009] As a further technical solution, the particle size of the carbide is 300-500 nm, for example, 300 nm, 350 nm, 450 nm, 500 nm, 400 nm, preferably 300 nm, 500 nm.

[0010] As a further technical solution, the particle size of the yttria-stabilized zirconia is 30~80nm, the molar content of ZrO2 is 91.5%~94.7%, and the molar content of Y2O3 is 3%~5%. Preferably, the particle size of the yttria-stabilized zirconia is 30nm, the molar content of ZrO2 is 91.5%, and the molar content of Y2O3 is 5%.

[0011] As a further technical solution, the carbide includes one or more of titanium carbide, zirconium carbide, molybdenum carbide, and strontium carbide, preferably titanium carbide and strontium carbide.

[0012] As a further technical solution, the tungsten oxide is rare earth element-doped tungsten oxide.

[0013] In the present invention, tungsten oxide has a unique crystal structure and electrical properties. After rare earth element doping, the lattice structure changes, resulting in lattice distortion. When rare earth element-doped tungsten oxide is added to an aluminum nitride ceramic substrate, strong chemical bonds are formed between the rare earth element-doped tungsten oxide and the aluminum nitride particles, promoting inter-particle bonding and inhibiting abnormal growth of aluminum nitride grains, making the microstructure of the aluminum nitride ceramic more uniform and dense. At the same time, rare earth element-doped tungsten oxide acts as a second-phase particle, introducing a dispersion strengthening mechanism into the aluminum nitride matrix. Under the action of external forces, these dispersed particles hinder dislocation motion, consume external energy, effectively inhibit crack initiation and propagation, and further enhance the strength of the aluminum nitride ceramic substrate.

[0014] As a further technical solution, the preparation method of the rare earth element-doped tungsten oxide comprises the following steps:

[0015] A1. Mix tungstate and water to obtain a tungstate solution;

[0016] A2. Adding rare earth nitrate solution to the tungstate solution for primary mixing, adjusting the pH to 1-2, and then performing secondary mixing and post-processing to obtain rare earth element-doped tungsten oxide.

[0017] In the present invention, tungstate can be dissolved in water, and the tungstate is converted into a solution state, providing a homogeneous environment for subsequent mixing with a rare earth nitrate solution and a chemical reaction. After adding a rare earth nitrate solution to the tungstate solution, the pH is adjusted to 1-2. In this acidic environment, tungstate ions are more likely to interact with rare earth ions, thereby obtaining rare earth element-doped tungsten oxide with stable structure and performance.

[0018] As a further technical solution, in step A1, the mass volume ratio of the tungstate and water is 1 g:10~12 mL.

[0019] As a further technical solution, in step A2, the temperature of the second mixing is 120-130° C. and the time is 15-20 h;

[0020] The post-processing includes cooling, washing, drying and grinding.

[0021] In the present invention, a hydrothermal method is used, and the temperature of the second mixing is 120-130° C. and the time is 15-20 hours. At this temperature and time, the collision frequency between the rare earth ions and the tungstate is increased, the complexation reaction is promoted, and the reaction between the ions is accelerated, so that the formation of rare earth element-doped tungsten oxide is more complete.

[0022] As a further technical solution, in the rare earth nitrate solution, the mass volume ratio of rare earth nitrate to water is 1g:15~20mL;

[0023] The mass ratio of the tungstate to the rare earth nitrate is 12:1-3.

[0024] As a further technical solution, the tungstate includes one or both of sodium tungstate and ammonium tungstate;

[0025] The rare earth nitrate includes one or both of ytterbium nitrate and cerium nitrate.

[0026] As a further technical solution, when the rare earth nitrate is ytterbium nitrate and cerium nitrate, the mass ratio of the ytterbium nitrate to the cerium nitrate is 3:1-2.

[0027] In the present invention, when the rare earth elements ytterbium and cerium are co-doped with tungsten oxide, the different ionic radii and valence states of the two rare earth elements enhance the interfacial bonding between the tungsten oxide and aluminum nitride, making the resulting ceramic microstructure more uniform and dense, and improving the strength of the aluminum nitride ceramic substrate. Furthermore, with the development of electronic devices towards miniaturization and high power, aluminum nitride ceramic substrates still suffer from insufficient resistivity. Ytterbium-cerium co-doped tungsten oxide is uniformly dispersed in the aluminum nitride matrix, forming effective charge scattering centers, increasing the probability of electron scattering, and thus improving the resistivity of the aluminum nitride ceramic substrate.

[0028] As a further technical solution, the sintering aid includes one or more of lanthanum oxide, calcium fluoride, magnesium oxide, and calcium oxide.

[0029] As a further technical solution, the sintering aids are lanthanum oxide and calcium fluoride.

[0030] As a further technical solution, the sintering aid is lanthanum oxide and calcium fluoride in a mass ratio of 1:1.

[0031] The binder includes polyvinyl butyral;

[0032] The plasticizer includes one or both of dibutyl phthalate and diisooctyl phthalate;

[0033] The dispersant includes one or two of cetyltrimethylammonium bromide and polyethylene glycol;

[0034] The solvent includes one or more of ethanol, isopropanol, and n-butanol.

[0035] The present invention also provides a method for preparing a high-resistivity aluminum nitride ceramic substrate, which is used to prepare the high-resistivity aluminum nitride ceramic substrate, comprising the following steps:

[0036] S1, mixing the aluminum nitride powder, sintering aid, functional additive and solvent, adding the remaining raw materials of the high resistivity aluminum nitride ceramic substrate and continuing to mix to obtain a slurry;

[0037] S2, tape-casting the slurry and drying it to obtain a blank;

[0038] S3. Debinding and sintering the green material to obtain a high resistivity aluminum nitride ceramic substrate.

[0039] The working principle and beneficial effects of the present invention are:

[0040] In the present invention, the main raw material of the aluminum nitride ceramic substrate is aluminum nitride powder, which itself has high thermal conductivity. The sintering aid can improve the density of the aluminum nitride ceramic substrate and ensure the mechanical properties of the aluminum nitride ceramic substrate. The binder forms a bridge between the raw material particles, giving the aluminum nitride ceramic substrate shape stability during processing and ensuring that the green body does not break during molding and transportation. The plasticizer, dispersant and solvent in the raw material can improve the plasticity, processability and fluidity of the material. The added carbide, tungsten oxide and yttria-stabilized zirconia serve as functional additives and can form a dispersed reinforcement phase in the aluminum nitride ceramic matrix, so that it can still maintain a good physical form under complex usage environments, thereby significantly improving the strength of the aluminum nitride ceramic substrate. DETAILED DESCRIPTION

[0041] 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.

[0042] In the following examples and comparative examples, the particle size of the aluminum nitride powder is 2 μm;

[0043] The particle size of strontium carbide is 300 nm;

[0044] The particle size of titanium carbide is 500 nm;

[0045] The particle size of tungsten oxide (WO3) is 1 μm;

[0046] The particle size of yttria-stabilized zirconia is 30 nm, the molar content of ZrO2 is 91.5%, the molar content of Y2O3 is 5%, and the crystal phase is tetragonal;

[0047] The model of polyvinyl butyral is TB-20.

[0048] Example 1

[0049] A high-resistivity aluminum nitride ceramic substrate comprises the following raw materials in parts by weight: 75 parts of aluminum nitride powder, 4 parts of a sintering aid, 3 parts of a functional additive, 8 parts of polyvinyl butyral, 1 part of dibutyl phthalate, 1 part of hexadecyltrimethylammonium bromide, and 65 parts of ethanol;

[0050] The functional additives are titanium carbide, tungsten oxide, and yttria-stabilized zirconia in a mass ratio of 9:2:1; the sintering additives are lanthanum oxide and calcium fluoride in a mass ratio of 1:1;

[0051] A method for preparing a high-resistivity aluminum nitride ceramic substrate comprises the following steps:

[0052] S1. Mixing aluminum nitride powder, a sintering aid, a functional additive, and ethanol, adding the remaining raw materials of the high resistivity aluminum nitride ceramic substrate and continuing to mix to obtain a slurry;

[0053] S2, tape-casting the slurry and drying it to obtain a blank;

[0054] S3. Debinding and sintering the green material to obtain a high resistivity aluminum nitride ceramic substrate.

[0055] Example 2

[0056] A high-resistivity aluminum nitride ceramic substrate comprising the following raw materials in parts by weight: 85 parts of aluminum nitride powder, 8 parts of lanthanum oxide, 6 parts of a functional additive, 12 parts of polyvinyl butyral, 5 parts of dibutyl phthalate, 3 parts of hexadecyltrimethylammonium bromide, and 75 parts of ethanol;

[0057] The functional additives are strontium carbide, tungsten oxide, and yttria-stabilized zirconium oxide in a mass ratio of 1:2:1;

[0058] A method for preparing a high-resistivity aluminum nitride ceramic substrate comprises the following steps:

[0059] S1. Mixing aluminum nitride powder, lanthanum oxide, functional additives, and ethanol, adding the remaining raw materials of the high resistivity aluminum nitride ceramic substrate and continuing to mix to obtain a slurry;

[0060] S2, tape-casting the slurry and drying it to obtain a blank;

[0061] S3. Debinding and sintering the green material to obtain a high resistivity aluminum nitride ceramic substrate.

[0062] Example 3

[0063] A high-resistivity aluminum nitride ceramic substrate comprises the following raw materials in parts by weight: 80 parts of aluminum nitride powder, 6 parts of a sintering aid, 5 parts of a functional additive, 10 parts of polyvinyl butyral, 3 parts of dibutyl phthalate, 2 parts of hexadecyltrimethylammonium bromide, and 70 parts of ethanol;

[0064] The functional additives are strontium carbide, tungsten oxide, and yttria-stabilized zirconia in a mass ratio of 6:2:1; the sintering additives are lanthanum oxide and calcium fluoride in a mass ratio of 1:1;

[0065] A method for preparing a high-resistivity aluminum nitride ceramic substrate comprises the following steps:

[0066] S1. Mixing aluminum nitride powder, a sintering aid, a functional additive, and ethanol, adding the remaining raw materials of the high resistivity aluminum nitride ceramic substrate and continuing to mix to obtain a slurry;

[0067] S2, tape-casting the slurry and drying it to obtain a blank;

[0068] S3. Debinding and sintering the green material to obtain a high resistivity aluminum nitride ceramic substrate.

[0069] Example 4

[0070] The only difference between this embodiment and embodiment 3 is that tungsten oxide is replaced with rare earth element-doped tungsten oxide;

[0071] The preparation method of rare earth element doped tungsten oxide comprises the following steps:

[0072] A1. Mix sodium tungstate and water at a mass volume ratio of 1 g:10 mL to obtain a sodium tungstate solution;

[0073] A2. Add ytterbium nitrate solution (the mass volume ratio of ytterbium nitrate to water is 1g:15mL) to the sodium tungstate solution and mix. After adding nitric acid to adjust the pH to 1, mix at 120°C for 20 hours, cool to room temperature, wash the product with water, dry at 80°C for 4 hours, and grind to obtain rare earth element-doped tungsten oxide with an average particle size of 10μm, wherein the mass ratio of sodium tungstate to ytterbium nitrate is 12:1.

[0074] Example 5

[0075] The only difference between this embodiment and embodiment 3 is that tungsten oxide is replaced with rare earth element-doped tungsten oxide;

[0076] The preparation method of rare earth element doped tungsten oxide comprises the following steps:

[0077] A1. Mix sodium tungstate and water at a mass volume ratio of 1 g:12 mL to obtain a sodium tungstate solution;

[0078] A2. Add ytterbium nitrate solution (the mass volume ratio of ytterbium nitrate to water is 1g:20mL) to the sodium tungstate solution and mix. After adding nitric acid to adjust the pH to 2, mix at 130°C for 15 hours, cool to room temperature, wash the product with water, dry at 90°C for 3 hours, and grind to obtain rare earth element-doped tungsten oxide with an average particle size of 10μm, wherein the mass ratio of sodium tungstate to ytterbium nitrate is 12:3.

[0079] Example 6

[0080] The only difference between this embodiment and embodiment 5 is that ytterbium nitrate is substituted for cerium nitrate.

[0081] Example 7

[0082] The only difference between this embodiment and embodiment 5 is that ytterbium nitrate is replaced by a rare earth nitrate mixture, and the rare earth nitrate mixture includes ytterbium nitrate and cerium nitrate in a mass ratio of 3:1.

[0083] Example 8

[0084] The only difference between this embodiment and embodiment 5 is that ytterbium nitrate is replaced by a rare earth nitrate mixture, and the rare earth nitrate mixture includes ytterbium nitrate and cerium nitrate in a mass ratio of 3:2.

[0085] Comparative Example 1

[0086] The only difference between this comparative example and Example 3 is that the functional additives are strontium carbide and tungsten oxide in a mass ratio of 3:1.

[0087] Comparative Example 2

[0088] The only difference between this comparative example and Example 3 is that the functional additives are strontium carbide and yttria-stabilized zirconia in a mass ratio of 6:1.

[0089] Comparative Example 3

[0090] The only difference between this comparative example and Example 3 is that the functional additives are tungsten oxide and yttria-stabilized zirconia in a mass ratio of 2:1.

[0091] Experimental Example 1

[0092] According to the three-point bending test method in the standard GB / T 6569-2006 "Test method for bending strength of fine ceramics", the high resistivity aluminum nitride ceramic substrates prepared in Examples 1 to 8 and Comparative Examples 1 to 3 were tested for bending strength. The results are shown in Table 1 below.

[0093] Table 1 Performance test results

[0094]

[0095] Compared with Comparative Examples 1 to 3, the aluminum nitride ceramic substrates prepared in Examples 1 to 8 have higher bending strength, indicating that the functional additives of the aluminum nitride ceramic substrates are a compound of carbide, tungsten oxide, and yttria-stabilized zirconia, which improves the strength of the aluminum nitride ceramic substrates.

[0096] Experimental Example 2

[0097] According to the test method in GB 5594.5-1985 "Test Methods for Performance of Structural Ceramics for Electronic Components - Volume Resistivity Test Method", the volume resistivity of the high resistivity aluminum nitride ceramic substrates prepared in Examples 3 and 5 to 8 was tested. The results are shown in Table 2 below.

[0098] Table 2 Performance test results

[0099]

[0100] Compared with Examples 3 and 5-6, the volume resistivity of the aluminum nitride ceramic substrates prepared in Examples 7-8 is higher, indicating that when rare earth elements are doped with tungsten oxide in the aluminum nitride ceramic substrate, the rare earth elements ytterbium and cerium co-doped with tungsten oxide improve the resistivity of the aluminum nitride ceramic substrate.

[0101] 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. A high resistivity aluminum nitride ceramic substrate, characterized in that: The method comprises the following raw materials in parts by weight: 75-85 parts of aluminum nitride powder, 4-8 parts of sintering aid, 3-6 parts of functional additive, 8-12 parts of binder, 1-5 parts of plasticizer, 1-3 parts of dispersant, and 65-75 parts of solvent; The functional additives include carbide, tungsten oxide, and yttria-stabilized zirconia in a mass ratio of 1 to 9:2:

1.

2. The high resistivity aluminum nitride ceramic substrate according to claim 1, characterized in that: The carbide includes one or more of titanium carbide, zirconium carbide, molybdenum carbide, and strontium carbide.

3. The high resistivity aluminum nitride ceramic substrate according to claim 1, characterized in that: The tungsten oxide is rare earth element doped tungsten oxide.

4. The high resistivity aluminum nitride ceramic substrate according to claim 3, characterized in that: The preparation method of the rare earth element-doped tungsten oxide comprises the following steps: A1. Mix tungstate and water to obtain a tungstate solution; A2. Adding rare earth nitrate solution to the tungstate solution for primary mixing, adjusting the pH to 1-2, and then performing secondary mixing and post-processing to obtain rare earth element-doped tungsten oxide.

5. The high resistivity aluminum nitride ceramic substrate according to claim 4, characterized in that: In step A1, the mass volume ratio of the tungstate and water is 1 g:10-12 mL.

6. The high resistivity aluminum nitride ceramic substrate according to claim 4, characterized in that: In step A2, the temperature of the second mixing is 120-130° C. and the time is 15-20 h; The post-processing includes cooling, washing, drying and grinding.

7. The high resistivity aluminum nitride ceramic substrate according to claim 4, characterized in that: In the rare earth nitrate solution, the mass volume ratio of rare earth nitrate to water is 1g:15-20mL; The mass ratio of the tungstate to the rare earth nitrate is 12:1-3.

8. The high resistivity aluminum nitride ceramic substrate according to claim 7, characterized in that: The tungstate includes one or both of sodium tungstate and ammonium tungstate; The rare earth nitrate includes one or both of ytterbium nitrate and cerium nitrate.

9. The high resistivity aluminum nitride ceramic substrate according to claim 1, characterized in that: The sintering aid includes one or more of lanthanum oxide, calcium fluoride, magnesium oxide, and calcium oxide; The binder includes polyvinyl butyral; The plasticizer includes one or both of dibutyl phthalate and diisooctyl phthalate; The dispersant includes one or two of cetyltrimethylammonium bromide and polyethylene glycol; The solvent includes one or more of ethanol, isopropanol, and n-butanol.

10. A method for preparing a high-resistivity aluminum nitride ceramic substrate, for preparing a high-resistivity aluminum nitride ceramic substrate according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, mixing the aluminum nitride powder, sintering aid, functional additive and solvent, adding the remaining raw materials of the high resistivity aluminum nitride ceramic substrate and continuing to mix to obtain a slurry; S2, tape-casting the slurry and drying it to obtain a blank; S3. Debinding and sintering the green material to obtain a high resistivity aluminum nitride ceramic substrate.

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