Aluminum nitride ceramic substrate with low thermal expansion coefficient and preparation method thereof

Abstract

The present invention relates to the technical field of ceramic substrates, and proposes a low thermal expansion coefficient aluminum nitride ceramic substrate and a preparation method thereof. The low thermal expansion coefficient aluminum nitride ceramic substrate, the raw materials include the following components in parts by weight: 100 parts of aluminum nitride, 10-18 parts of titanium-containing compounds, 4-8 parts of copper oxide, 5-8 parts of binder, 2-4 parts of plasticizer, 6-8 parts of sintering aid, 1-3 parts of dispersant, 80 parts of solvent; the titanium-containing compound includes barium strontium titanate and titanium aluminum carbide in a weight ratio of 1.5-3:1. Through the above technical solution, the problem of high thermal expansion coefficient of aluminum nitride ceramic substrates in related technologies is solved.

Description

Technical Field

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

[0002] Ceramic substrate is an electronic circuit board substrate made of ceramic material, which has excellent electrical insulation performance and good thermal conductivity. It has a wide range of uses. In power electronic modules, ceramic substrates can provide stable mechanical support for chips, realize electrical connection between chips and external circuits, and ensure stable operation of chips within a suitable temperature range, thereby improving the reliability and service life of power electronic modules. Ceramic substrates have become the preferred substrate material for key electronic components due to their high strength and good comprehensive performance.

[0003] Aluminum nitride (AlN) ceramic substrates have the advantages of high thermal conductivity and good chemical stability, so they are favored in the field of high-power and high-density packaging. However, the existing aluminum nitride ceramic substrates still have certain defects in terms of thermal expansion coefficient. On the one hand, although its thermal expansion coefficient has a certain degree of matching with silicon chips, in some application scenarios with extremely stringent requirements on thermal stability, the slight difference between the thermal expansion coefficient of the aluminum nitride ceramic substrate and the chip material will cause large thermal stress between the substrate and the chip, which will seriously affect the performance and reliability of electronic devices. On the other hand, as electronic equipment continues to develop in the direction of miniaturization and integration, higher requirements are placed on the uniformity of the thermal expansion coefficient of ceramic substrates.

[0004] At present, the problem of high thermal expansion coefficient is dealt with by adjusting the material composition, such as adding some low expansion additives, such as yttrium oxide, lanthanum oxide, etc., but the effect of inhibiting the thermal expansion of aluminum nitride is limited, and stress concentration is easily generated at the interface with the ceramic substrate matrix, affecting the reliability of the substrate.

[0005] Therefore, developing an aluminum nitride ceramic substrate with a lower thermal expansion coefficient is of great significance for meeting the performance requirements of the aluminum nitride ceramic substrate. Summary of the invention

[0006] The invention provides an aluminum nitride ceramic substrate with a low thermal expansion coefficient and a preparation method thereof, which solves the problem of a high thermal expansion coefficient of the aluminum nitride ceramic substrate in the related art.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention provides a low thermal expansion coefficient aluminum nitride ceramic substrate, the raw materials of which include the following components in parts by weight:

[0009] 100 parts of aluminum nitride, 10-18 parts of titanium-containing compound, 4-8 parts of copper oxide, 5-8 parts of binder, 2-4 parts of plasticizer, 6-8 parts of sintering aid, 1-3 parts of dispersant, and 80 parts of solvent;

[0010] The titanium-containing compound includes barium strontium titanate and titanium aluminum carbide in a weight ratio of 1.5 to 3:1.

[0011] In the present invention, the lattice occupancy ratio of the barium element in the barium strontium titanate can be 0.3, 0.5, 0.7, 0.95, preferably 0.3, 0.5, 0.7, and more preferably 0.5, that is, the barium strontium titanate can be Ba 0.3 Sr 0.7 TiO 3 , Ba 0.5 Sr 0.5 TiO 3 , Ba 0.7 Sr 0.3 TiO 3 , Ba 0.95 Sr 0.05 TiO 3 , preferably Ba 0.3 Sr 0.7 TiO 3 , Ba 0.5 Sr 0.5 TiO 3 , Ba 0.7 Sr 0.3 TiO 3 , more preferably Ba 0.5 Sr 0.5 TiO 3 ;

[0012] When the lattice occupancy ratio of barium in barium strontium titanate is 0.5, that is, barium strontium titanate is Ba 0.5 Sr 0.5 TiO 3 The crystal structure of barium strontium titanate is relatively more stable, and its bonding with the matrix aluminum nitride is better. Working together with titanium aluminum carbide, it can further enhance the thermal expansion constraint on the matrix aluminum nitride, thereby further reducing the thermal expansion coefficient of the aluminum nitride ceramic substrate.

[0013] As a further technical solution, the titanium-containing compound is a composite titanium-containing compound, and the raw materials of the composite titanium-containing compound include a titanium-containing compound, aluminum powder and a carbon chain polymer.

[0014] As a further technical solution, the weight ratio of the aluminum powder and the carbon chain polymer to the titanium-containing compound is 2 to 7:30, for example, it can be 1:15, 1:10, 2:15, 3:20, 1:6, 5.5:30, 1:5, 7:30, preferably 1:15, 2:15, 1:6, 7:30, and more preferably 2:15, 1:6.

[0015] As a further technical solution, the weight ratio of the aluminum powder to the carbon chain polymer is 1:1.

[0016] In the present invention, aluminum powder and carbon chain polymer are used to carry out composite treatment on the titanium-containing compound, and the dosage ratio of the titanium-containing compound, aluminum powder and carbon chain polymer is reasonably regulated. In the process of preparing the aluminum nitride ceramic substrate, the titanium-containing compound can be better combined with aluminum nitride and other components through sintering treatment, so that the internal structure of the aluminum nitride ceramic substrate is more uniform and dense, and the aluminum nitride ceramic substrate is maintained with a low expansion coefficient, while the bending strength of the aluminum nitride ceramic substrate is also improved;

[0017] In the present invention, the carbon chain polymer is a polymer whose main chain consists of carbon atoms, for example, polymethyl methacrylate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyacrylonitrile, polyvinyl alcohol, preferably polymethyl methacrylate.

[0018] As a further technical solution, the preparation method of the composite titanium-containing compound comprises the following steps:

[0019] A1, dispersing the carbon chain polymer in acetone, adding a titanium-containing compound, mixing evenly, drying, and calcining to obtain a pre-composite titanium-containing compound;

[0020] A2. Add aluminum powder to the pre-composite titanium-containing compound and perform ball milling to obtain a composite titanium-containing compound.

[0021] As a further technical solution, in step A1, when the mixing is uniform, stirring is adopted, and the stirring speed is 500-600 rpm and the time is 20-30 min.

[0022] As a further technical solution, during the calcination, the calcination temperature is 400-500° C. and the time is 1-1.5 h in a nitrogen atmosphere;

[0023] In step A2, when adding aluminum powder, 40% to 60% of the weight of the aluminum powder is first added, and ball milled at 200 to 300 rpm for 35 to 40 minutes, and then the remaining weight of the aluminum powder is added, and ball milled at 400 to 500 rpm for 10 to 20 minutes.

[0024] In the present invention, in step A1, the carbon chain polymer and the titanium-containing compound are first mixed, and after removing the solvent, the carbon chain polymer and the titanium-containing compound composite system can be initially formed, and then calcined at 400-500° C. to enhance the subsequent bonding degree with aluminum powder, laying a foundation for the preparation of the composite titanium-containing compound;

[0025] In step A2, 40% to 60% of the weight of aluminum powder is first added and ball milled at a lower ball milling speed, so that the added aluminum powder can gradually combine with the pre-composite titanium-containing compound, and then the remaining aluminum powder is added and the ball milling speed is increased to further mix the later added aluminum powder with each component. At the same time, the higher speed helps to increase the mechanical force between the aluminum powder and the pre-composite titanium-containing compound, making them more closely combined, thereby better preparing the composite titanium-containing compound.

[0026] As a further technical solution, the solvent includes one or both of ethanol and isopropanol, preferably ethanol.

[0027] In the present invention, during the forming process of the aluminum nitride ceramic substrate, the binder can bind the components together, the ceramic particles are bonded together, the plasticity of the components is increased, the casting slurry is better stamped and formed, and the blank is better kept in shape. The binder can be one or two of polyvinyl butyral and hydroxy acrylic resin, preferably polyvinyl butyral.

[0028] In the present invention, the plasticizer can give the aluminum nitride ceramic substrate blank a certain flexibility, so that it is not easy to break under the action of external force. The plasticizer includes one or both of dibutyl phthalate and diethyl phthalate, preferably dibutyl phthalate.

[0029] In the present invention, the dispersant can reduce the interaction force between the components in the aluminum nitride ceramic substrate to a certain extent, and work together with the binder to make the viscosity and flowability of the casting slurry in a moderate state. Good flowability helps the casting slurry to spread evenly during the molding process, which is beneficial to improving the uniformity of the internal structure of the aluminum nitride ceramic substrate. The dispersant includes one or more of polyethylene glycol stearate, triethyl phosphate, and polyethylene glycol, preferably polyethylene glycol stearate.

[0030] In the present invention, the sintering aid can reduce the sintering temperature of the aluminum nitride ceramic substrate, so that it can achieve densification sintering at a relatively low temperature. The sintering aid can be one or more of calcium oxide, yttrium oxide, yttrium chloride, and calcium fluoride. Calcium oxide is CaO, yttrium oxide is Y 2 O 3 , yttrium chloride is YCl 3 , calcium fluoride is CaF 2 , preferably CaO, Y 2 O3 , CaO and Y 2 O 3 The weight ratio is 0.5~1.5:3, for example, it can be 0.5:3, 0.8:3, 1:3, 1.1:3, 1.3:3, 1.5:3, preferably 1:3.

[0031] The present invention also provides a method for preparing a low thermal expansion coefficient aluminum nitride ceramic substrate, which is used to prepare the low thermal expansion coefficient aluminum nitride ceramic substrate, comprising the following steps:

[0032] S1, mixing the components except the binder and the plasticizer uniformly, and ball milling to obtain a mixture;

[0033] S2, adding a binder and a plasticizer to the mixture and mixing evenly to obtain a casting slurry;

[0034] S3, subjecting the tape-casting slurry to tape-casting, drying, and stamping to obtain a blank;

[0035] S4, debinding and sintering the green sheet to obtain the low thermal expansion coefficient aluminum nitride ceramic substrate.

[0036] As a further technical solution, during the sintering, in a nitrogen atmosphere, the sintering temperature is 1670-1750° C. and the sintering time is 2-4 hours.

[0037] As a further technical solution, in step S1, during the ball milling, the ball milling speed is 300-400 rpm and the time is 30-40 min.

[0038] The working principle and beneficial effects of the present invention are:

[0039] 1. In the present invention, the raw materials of the aluminum nitride ceramic substrate include aluminum nitride, a titanium-containing compound, copper oxide, a binder, a plasticizer, a sintering aid, a dispersant, and a solvent. Aluminum nitride, as the main material of the ceramic substrate, provides a solid structural foundation for the ceramic substrate, and gives the ceramic substrate good thermal conductivity and basic mechanical strength. By combining with the various components, an aluminum nitride ceramic substrate with a low thermal expansion coefficient can be prepared.

[0040] 2. Titanium-containing compounds include barium strontium titanate and titanium aluminum carbide. By adding barium strontium titanate and titanium aluminum carbide to an aluminum nitride ceramic substrate and rationally adjusting the weight ratio of barium strontium titanate and titanium aluminum carbide to 1.5-3:1, the two can form certain constraints on the thermal expansion of the matrix aluminum nitride through interface bonding, thereby achieving effective regulation of the thermal expansion coefficient of the ceramic substrate, thereby improving the dimensional stability of the aluminum nitride ceramic substrate under different temperature environments, reducing the thermal expansion coefficient of the aluminum nitride ceramic substrate, and meeting the requirement of a low thermal expansion coefficient 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 described embodiments 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 creative work are within the scope of protection of the present invention.

[0042] In the following examples and comparative examples, the model of polyethylene glycol stearate is PEG-100; the model of polyvinyl butyral is TB-20; the model of polymethyl methacrylate is POQ66; the average particle size of titanium aluminum carbide is 30 μm; and the barium strontium titanate is Ba 0.3 Sr 0.7 TiO 3 , Ba 0.7 Sr 0.3 TiO 3 , Ba 0.5 Sr 0.5 TiO 3 , with an average particle size of 3 μm, and were purchased from Beijing Jinyuan New Materials Technology Co., Ltd.

[0043] Example 1

[0044] A method for preparing a low thermal expansion coefficient aluminum nitride ceramic substrate comprises the following steps:

[0045] S1, 100 parts of aluminum nitride, 6 parts of barium strontium titanate, 4 parts of titanium aluminum carbide, 4 parts of copper oxide, 1.5 parts of CaO, 4.5 parts of Y 2 O 3 , 1 part of polyethylene glycol stearate, and 80 parts of ethanol, mixed evenly, and ball-milled at 300 rpm for 40 minutes to obtain a mixture; wherein the lattice occupancy ratio of barium element in barium strontium titanate is 0.3, that is, barium strontium titanate is Ba 0.3 Sr 0.7 TiO 3 ;

[0046] S2, adding 5 parts of polyvinyl butyral and 2 parts of dibutyl phthalate to the mixture, mixing evenly to obtain a casting slurry;

[0047] S3, subjecting the tape-casting slurry to tape-casting, drying, and stamping to obtain a blank;

[0048] S4. After debinding the green sheet, sinter it in a nitrogen atmosphere at 1670° C. for 4 hours to obtain an aluminum nitride ceramic substrate with a low thermal expansion coefficient.

[0049] Example 2

[0050] A method for preparing a low thermal expansion coefficient aluminum nitride ceramic substrate comprises the following steps:

[0051] S1, 100 parts of aluminum nitride, 9.6 parts of barium strontium titanate, 6.4 parts of titanium aluminum carbide, 6 parts of copper oxide, 1.75 parts of CaO, 5.25 parts of Y 2 O 3 , 2 parts of polyethylene glycol stearate, and 80 parts of ethanol, mixed evenly, and ball-milled at 350 rpm for 35 minutes to obtain a mixture; wherein the lattice occupancy ratio of barium element in barium strontium titanate is 0.3, that is, barium strontium titanate is Ba 0.3 Sr 0.7 TiO 3 ;

[0052] S2, adding 6.5 parts of polyvinyl butyral and 2 parts of dibutyl phthalate to the mixture, mixing evenly to obtain a casting slurry;

[0053] S3, subjecting the tape-casting slurry to tape-casting, drying, and stamping to obtain a blank;

[0054] S4. After debinding the green sheet, sinter it in a nitrogen atmosphere at 1710° C. for 3 hours to obtain an aluminum nitride ceramic substrate with a low thermal expansion coefficient.

[0055] Example 3

[0056] A method for preparing a low thermal expansion coefficient aluminum nitride ceramic substrate comprises the following steps:

[0057] S1, 100 parts of aluminum nitride, 13.5 parts of barium strontium titanate, 4.5 parts of titanium aluminum carbide, 8 parts of copper oxide, 2 parts of CaO, 6 parts of Y 2 O 3 , 3 parts of polyethylene glycol stearate, and 80 parts of ethanol, mixed evenly, and ball-milled at 400 rpm for 30 minutes to obtain a mixture; wherein the lattice occupancy ratio of barium element in barium strontium titanate is 0.3, that is, barium strontium titanate is Ba 0.3 Sr 0.7 TiO 3 ;

[0058] S2, adding 8 parts of polyvinyl butyral and 4 parts of dibutyl phthalate to the mixture, mixing evenly to obtain a casting slurry;

[0059] S3, subjecting the tape-casting slurry to tape-casting, drying, and stamping to obtain a blank;

[0060] S4. After debinding the green sheet, sinter it in a nitrogen atmosphere at 1750° C. for 2 hours to obtain an aluminum nitride ceramic substrate with a low thermal expansion coefficient.

[0061] Example 4

[0062] The difference between this embodiment and embodiment 2 is that in this embodiment, 12 parts of barium strontium titanate and 4 parts of titanium carbide are added; the lattice occupancy ratio of barium in barium strontium titanate is 0.3, that is, barium strontium titanate is Ba 0.3 Sr 0.7 TiO 3 .

[0063] Example 5

[0064] The difference between this embodiment and embodiment 4 is that in this embodiment, the lattice occupancy ratio of barium in barium strontium titanate is 0.7, that is, barium strontium titanate is Ba 0.7 Sr 0.3 TiO 3 .

[0065] Example 6

[0066] The difference between this embodiment and embodiment 4 is that in this embodiment, the lattice occupancy ratio of barium in barium strontium titanate is 0.5, that is, barium strontium titanate is Ba 0.5 Sr 0.5 TiO 3 .

[0067] Example 7

[0068] The difference between this embodiment and embodiment 6 is that, in this embodiment, the titanium-containing compound is a composite titanium-containing compound, and the preparation method of the composite titanium-containing compound comprises the following steps:

[0069] A1. Disperse 1 part of polymethyl methacrylate in 35 parts of acetone, add 22.5 parts of barium strontium titanate and 7.5 parts of titanium aluminum carbide, stir at 500 rpm for 30 min, mix evenly, dry, and calcine at 400° C. in a nitrogen atmosphere for 1.5 h to obtain a pre-composite titanium-containing compound;

[0070] A2, first add 0.4 parts of aluminum powder to the above pre-composite titanium-containing compound, ball mill at 200 rpm for 40 min, then add 0.6 parts of aluminum powder, ball mill at 400 rpm for 20 min to obtain a composite titanium-containing compound;

[0071] A method for preparing a low thermal expansion coefficient aluminum nitride ceramic substrate comprises the following steps:

[0072] S1, 100 parts of aluminum nitride, 16 parts of composite titanium-containing compound, 6 parts of copper oxide, 1.75 parts of CaO, 5.25 parts of Y 2 O 3 , 2 parts of polyethylene glycol stearate, and 80 parts of ethanol, mixed evenly, and ball-milled at 350 rpm for 35 minutes to obtain a mixture; wherein the lattice occupancy ratio of barium element in barium strontium titanate is 0.5, that is, barium strontium titanate is Ba0.5 Sr 0.5 TiO 3 ;

[0073] S2, adding 6.5 parts of polyvinyl butyral and 2 parts of dibutyl phthalate to the mixture, mixing evenly to obtain a casting slurry;

[0074] S3, subjecting the tape-casting slurry to tape-casting, drying, and stamping to obtain a blank;

[0075] S4. After debinding the green sheet, sinter it in a nitrogen atmosphere at 1710° C. for 3 hours to obtain an aluminum nitride ceramic substrate with a low thermal expansion coefficient.

[0076] Example 8

[0077] The difference between this embodiment and embodiment 7 is that, in this embodiment, the preparation method of the composite titanium-containing compound comprises the following steps:

[0078] A1. Disperse 3.5 parts of polymethyl methacrylate in 35 parts of acetone, add 22.5 parts of barium strontium titanate and 7.5 parts of titanium aluminum carbide, stir at 500 rpm for 30 min, mix evenly, dry, and calcine at 400° C. in a nitrogen atmosphere for 1.5 h to obtain a pre-composite titanium-containing compound;

[0079] A2. First, 1.4 parts of aluminum powder were added to the above pre-composite titanium-containing compound, and the mixture was ball-milled at 200 rpm for 40 min. Then, 2.1 parts of aluminum powder were added, and the mixture was ball-milled at 400 rpm for 20 min to obtain a composite titanium-containing compound.

[0080] Example 9

[0081] The difference between this embodiment and embodiment 7 is that, in this embodiment, the preparation method of the composite titanium-containing compound comprises the following steps:

[0082] A1. Disperse 2 parts of polymethyl methacrylate in 35 parts of acetone, add 22.5 parts of barium strontium titanate and 7.5 parts of titanium aluminum carbide, stir at 500 rpm for 30 min, mix evenly, dry, and calcine at 400° C. in a nitrogen atmosphere for 1.5 h to obtain a pre-composite titanium-containing compound;

[0083] A2. First, 0.8 parts of aluminum powder were added to the above pre-composite titanium-containing compound, and the mixture was ball-milled at 200 rpm for 40 min. Then, 1.2 parts of aluminum powder were added, and the mixture was ball-milled at 400 rpm for 20 min to obtain a composite titanium-containing compound.

[0084] Example 10

[0085] The difference between this embodiment and embodiment 7 is that, in this embodiment, the preparation method of the composite titanium-containing compound comprises the following steps:

[0086] A1. Disperse 2.5 parts of polymethyl methacrylate in 35 parts of acetone, add 22.5 parts of barium strontium titanate and 7.5 parts of titanium aluminum carbide, stir at 500 rpm for 30 min, mix evenly, dry, and calcine at 400° C. in a nitrogen atmosphere for 1.5 h to obtain a pre-composite titanium-containing compound;

[0087] A2. First, 1 part of aluminum powder was added to the above pre-composite titanium-containing compound, and the mixture was ball-milled at 200 rpm for 40 min. Then, 1.5 parts of aluminum powder was added, and the mixture was ball-milled at 400 rpm for 20 min to obtain a composite titanium-containing compound.

[0088] Embodiment 11

[0089] The only difference between this embodiment and embodiment 10 is that in this embodiment, the preparation method of the composite titanium-containing compound comprises the following steps:

[0090] A1. Disperse 2.5 parts of polymethyl methacrylate in 35 parts of acetone, add 22.5 parts of barium strontium titanate and 7.5 parts of titanium aluminum carbide, stir at 600 rpm for 20 min, mix evenly, dry, and calcine at 500° C. in a nitrogen atmosphere for 1 h to obtain a pre-composite titanium-containing compound;

[0091] A2. First, 1 part of aluminum powder was added to the above pre-composite titanium-containing compound, and the mixture was ball-milled at 300 rpm for 35 min. Then, 1.5 parts of aluminum powder was added, and the mixture was ball-milled at 500 rpm for 10 min to obtain a composite titanium-containing compound.

[0092] Example 12

[0093] The only difference between this embodiment and embodiment 7 is that in this embodiment, the preparation method of the composite titanium-containing compound includes the following steps: dispersing 2 parts of polymethyl methacrylate in 35 parts of acetone, adding 22.5 parts of barium strontium titanate and 7.5 parts of titanium aluminum carbide, stirring at 500 rpm for 30 minutes, mixing evenly, drying, and calcining at 400°C in a nitrogen atmosphere for 1.5 hours to obtain a composite titanium-containing compound.

[0094] Embodiment 13

[0095] The only difference between this embodiment and embodiment 7 is that in this embodiment, the preparation method of the composite titanium-containing compound includes the following steps: 22.5 parts of barium strontium titanate, 7.5 parts of titanium aluminum carbide and 0.8 parts of aluminum powder are blended, ball-milled at 200 rpm for 40 minutes, and then 1.2 parts of aluminum powder are added, and ball-milled at 400 rpm for 20 minutes to obtain the composite titanium-containing compound.

[0096] Comparative Example 1

[0097] The difference between this comparative example and Example 1 is that in this comparative example, no barium strontium titanate is added, and 10 parts of titanium aluminum carbide are added.

[0098] Comparative Example 2

[0099] The difference between this comparative example and Example 1 is that in this comparative example, no titanium aluminum carbide is added, and 10 parts of barium strontium titanate are added.

[0100] Comparative Example 3

[0101] The only difference between this comparative example and Example 1 is that in this comparative example, neither barium strontium titanate nor titanium aluminum carbide is added.

[0102] Experimental Example 1

[0103] The thermal expansion coefficients of the aluminum nitride ceramic substrate samples prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were tested between 30° C. and 400° C. using a German NETZSCH linear dilatometer (model: DIL 402C). The test results are shown in Table 1.

[0104] Table 1 Test results of thermal expansion coefficient of aluminum nitride ceramic substrate

[0105]

[0106] Compared with Comparative Examples 1 to 3, the thermal expansion coefficients of the aluminum nitride ceramic substrates in Examples 1 to 6 are significantly reduced, indicating that when barium strontium titanate and titanium aluminum carbide are added to the aluminum nitride ceramic substrate, the two have a synergistic effect, reducing the thermal expansion coefficient of the aluminum nitride ceramic substrate, and reducing the thermal expansion coefficient of the aluminum nitride ceramic substrate to 2.5 ppm / °C.

[0107] Experimental Example 2

[0108] The aluminum nitride ceramic substrate samples prepared in Examples 6 to 13 were tested for bending strength according to the three-point bending test method of GB / T 6569-2006 “Test method for bending strength of fine ceramics”. The test results are shown in Table 2.

[0109] Table 2 Bending strength test results of aluminum nitride ceramic substrate

[0110]

[0111] Compared with Example 6 and Examples 12-13, the bending strength of the aluminum nitride ceramic substrates in Examples 7-11 reached above 538 MPa, indicating that the bending strength of the aluminum nitride ceramic substrates can be improved by composite treatment of the titanium-containing compound with aluminum powder and carbon chain polymer.

[0112] Experimental Example 3

[0113] The aluminum nitride ceramic substrates prepared in Examples 1 to 3 were tested for thermal conductivity according to the test method specified in GB / T 39862-2021 “Testing of thermal conductivity of high thermal conductivity ceramics”. The test results are shown in Table 3.

[0114] Table 3 Thermal conductivity test results of aluminum nitride ceramic substrate

[0115]

[0116] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A low thermal expansion coefficient aluminum nitride ceramic substrate, characterized in that: The raw materials include the following components in parts by weight: 100 parts of aluminum nitride, 10-18 parts of titanium-containing compound, 4-8 parts of copper oxide, 5-8 parts of binder, 2-4 parts of plasticizer, 6-8 parts of sintering aid, 1-3 parts of dispersant, and 80 parts of solvent; The titanium-containing compound includes barium strontium titanate and titanium aluminum carbide in a weight ratio of 1.5 to 3:

1.

2. The low thermal expansion coefficient aluminum nitride ceramic substrate according to claim 1, characterized in that: The lattice occupancy ratio of the barium element in the barium strontium titanate is 0.

5.

3. The low thermal expansion coefficient aluminum nitride ceramic substrate according to claim 1, characterized in that: The titanium-containing compound is a composite titanium-containing compound, and the raw materials of the composite titanium-containing compound include a titanium-containing compound, aluminum powder and a carbon chain polymer.

4. The low thermal expansion coefficient aluminum nitride ceramic substrate according to claim 3, characterized in that: The carbon chain polymer includes polymethyl methacrylate.

5. The low thermal expansion coefficient aluminum nitride ceramic substrate according to claim 3, characterized in that: The weight ratio of the aluminum powder and the carbon chain polymer to the titanium-containing compound is 2-7:

30.

6. The low thermal expansion coefficient aluminum nitride ceramic substrate according to claim 3, characterized in that: The preparation method of the composite titanium-containing compound comprises the following steps: A1, dispersing the carbon chain polymer in acetone, adding a titanium-containing compound, mixing evenly, drying, and calcining to obtain a pre-composite titanium-containing compound; A2. Add aluminum powder to the pre-composite titanium-containing compound and perform ball milling to obtain a composite titanium-containing compound.

7. The low thermal expansion coefficient aluminum nitride ceramic substrate according to claim 6, characterized in that: During the calcination, the calcination temperature is 400-500° C. and the time is 1-1.5 h in a nitrogen atmosphere; In step A2, when adding aluminum powder, 40% to 60% of the weight of the aluminum powder is first added, and ball milled at 200 to 300 rpm for 35 to 40 minutes, and then the remaining weight of the aluminum powder is added, and ball milled at 400 to 500 rpm for 10 to 20 minutes.

8. The low thermal expansion coefficient aluminum nitride ceramic substrate according to claim 1, characterized in that: The binder comprises one or two of polyvinyl butyral and hydroxy acrylic resin; and / or The plasticizer includes one or both of dibutyl phthalate and diethyl phthalate; and / or The dispersant includes one or more of polyethylene glycol stearate, triethyl phosphate, and polyethylene glycol; and / or The sintering aid includes one or more of CaO, Y2O3, YCl3, CaF2; and / or The solvent includes one or both of ethanol and isopropanol.

9. A method for preparing a low thermal expansion coefficient aluminum nitride ceramic substrate, used to prepare a low thermal expansion coefficient aluminum nitride ceramic substrate as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1, mixing the components except the binder and the plasticizer uniformly, and ball milling to obtain a mixture; S2, adding a binder and a plasticizer to the mixture and mixing evenly to obtain a casting slurry; S3, subjecting the tape-casting slurry to tape-casting, drying, and stamping to obtain a blank; S4, debinding and sintering the green sheet to obtain the low thermal expansion coefficient aluminum nitride ceramic substrate.

10. The method for preparing a low thermal expansion coefficient aluminum nitride ceramic substrate according to claim 9, characterized in that: During the sintering, in a nitrogen atmosphere, the sintering temperature is 1670-1750° C. and the sintering time is 2-4 hours.

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