A high-temperature co-fired multi-layer ceramic substrate and its preparation method

Abstract

The present invention relates to the technical field of ceramic substrates, and provides a high-temperature co-fired multi-layer ceramic substrate and a preparation method thereof. For the high-temperature co-fired multi-layer ceramic substrate, the raw materials include the following components in parts by weight: 100 parts of alumina, 4-12 parts of tungsten boride, 6-18 parts of borate compound, 3-6 parts of sintering aid, 2-4 parts of dispersant, 5-10 parts of binder, and 50-60 parts of solvent; the borate compound includes metaborate and polyborate with a weight ratio of 1-9:1. Through the above technical solution, the problem of poor flexural strength of multi-layer ceramic substrates in the related art 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 ceramic substrate and a preparation method thereof. Background Art

[0002] The multi-layer ceramic substrate is also known as a ceramic package. While serving as a signal transmission and heat dissipation medium, it can also protect the encapsulated device from various physical and chemical hazards. Due to its excellent thermal conductivity, high rigidity and other characteristics, it can be widely used in energy, medical, communication and other aspects.

[0003] The manufacturing of multi-layer ceramic substrates often adopts high-temperature co-fired and low-temperature co-fired ceramic technologies due to the differences in the materials used and the sintering temperature. Both of these preparation methods allow each layer in the ceramic substrate to be independently fabricated, tested and replaced, but the high-temperature co-fired ceramic technology is more mature. High-temperature co-fired multi-layer ceramic substrates mostly use alumina, aluminum nitride, beryllium oxide, etc. as ceramic materials, and tungsten, molybdenum, etc. as conductor materials, and a multi-layer ceramic substrate is prepared at a sintering temperature above 1400°C.

[0004] However, due to the high sintering temperature of high-temperature co-fired multi-layer ceramic substrates, the material selection is severely restricted. In a high-temperature environment, mainly some materials with higher melting points are used. In addition to alumina and aluminum nitride, there are also some other high-temperature resistant materials. Although these materials have higher melting points, they have higher costs, and there are problems with poor compatibility of materials under high-temperature sintering, which will affect the flexural strength of the ceramic substrate and reduce its yield and reliability.

[0005] Therefore, researching and developing a multi-layer ceramic substrate that can improve the flexural strength of the multi-layer ceramic substrate through a high-temperature co-firing process is of great significance for expanding the application of multi-layer ceramic substrates. Summary of the Invention

[0006] The present invention provides a high-temperature co-fired multi-layer ceramic substrate and a preparation method thereof, which solves the problem of poor flexural strength of multi-layer ceramic substrates in related technologies.

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

[0008] The present invention provides a high-temperature co-fired multi-layer ceramic substrate, and the raw materials include the following components in parts by weight:

[0009] 100 parts of alumina, 4 - 12 parts of tungsten diboride, 6 - 18 parts of borate compound, 3 - 6 parts of sintering aid, 2 - 4 parts of dispersant, 5 - 10 parts of binder, 50 - 60 parts of solvent;

[0010] The borate compound includes metaborate and polyborate in a weight ratio of 1 - 9:1.

[0011] As a further technical solution, the weight ratio of the metaborate to the polyborate is 3 to 7:1.

[0012] As a further technical solution, the metaborate includes one or more of sodium metaborate, calcium metaborate, and potassium metaborate;

[0013] The polyborate includes one of sodium tetraborate and potassium pentaborate.

[0014] As a further technical solution, the raw materials further include the following components in parts by weight: 2 to 8 parts of crystalline silica.

[0015] In the present invention, crystalline silica is introduced into the multilayer ceramic substrate. The crystalline silica can assist the borate compound to adjust the pore structure of the ceramic substrate. And when the ceramic substrate is subjected to an external force, under the action of the crystalline silica and other components, it can hinder the dislocation movement inside the ceramic substrate, so that when the ceramic substrate is subjected to friction, no wear marks are easily generated on the surface, thereby improving the wear resistance of the ceramic substrate.

[0016] As a further technical solution, the crystalline silica is titanium composite crystalline silica.

[0017] As a further technical solution, the raw materials of the titanium composite crystalline silica include crystalline silica and a titanium source in a weight ratio of 16:1 to 5;

[0018] The titanium source includes one of titanium acetylacetonate and titanium citrate, and preferably titanium acetylacetonate.

[0019] In the present invention, using titanium acetylacetonate or titanium citrate as the titanium source to perform a composite treatment on the crystalline silica and controlling the weight ratio of the crystalline silica to the titanium source to be 16:1 to 5 can further improve the wear resistance of the ceramic substrate. The possible reason is speculated as follows: In the early stage, during the preparation of the casting slurry, using titanium acetylacetonate or titanium citrate as the titanium source to perform a composite treatment on the crystalline silica can further improve the uniformity of the crystalline silica in the casting slurry, so that the formed green ceramic sheet has a uniform and stable internal structure; in the later stage, through sintering treatment, a dense film structure can be formed on the surface of the crystalline silica, thereby further improving the wear resistance of the ceramic substrate.

[0020] As a further technical solution, the preparation method of the titanium composite crystalline silica includes the following steps:

[0021] A1. Add the crystalline silica into an alkaline solution, disperse it evenly, concentrate, and dry to obtain the pretreated crystalline silica;

[0022] A2. Dissolve the titanium source in isopropanol, add the pretreated crystalline silica, disperse, concentrate, dry, and calcine to obtain titanium composite crystalline silica.

[0023] As a further technical solution, the weight ratio of the crystalline silica to the titanium source is 16:2 - 3.

[0024] When the weight ratio of the crystalline silica to the titanium source is 16:2 - 3, the wear resistance of the ceramic substrate is better, and the wear rate of the ceramic substrate can be reduced to 2.76×10 -6 ~2.82×10 -6 mm 3 / mN. When the weight ratio of the crystalline silica to the titanium source is outside the range of 16:2 - 3, the wear resistance of the ceramic substrate is inferior to that when the weight ratio of the crystalline silica to the titanium source is 16:2 - 3.

[0025] As a further technical solution, in step A1, the alkaline solution is one of sodium hydroxide solution, sodium carbonate solution, and sodium bicarbonate solution, and the mass fraction of the alkaline solution is 1% - 3%.

[0026] As a further technical solution, in step A1, the weight ratio of the crystalline silica to the alkaline solution is 1:1 - 1.06.

[0027] As a further technical solution, in step A1, the dispersion time is 10 - 18 min.

[0028] As a further technical solution, in step A2, the calcination temperature is 500 - 600 °C and the time is 1 - 2 h.

[0029] In the present invention, the sintering aid can be any one or more conventional sintering aids in the art. For example, it can be one or more of Y2O3, Li2O, Cr2O3, and La2O3. Preferably, it is Y2O3, Cr2O3, and La2O3 with a weight ratio of 2:1:1. In the late stage of sintering, abnormal grain growth is likely to occur in the ceramic material, affecting the densification of the internal structure of the ceramic substrate. By adding the sintering aid, while making the grains grow more uniformly, the sintering temperature range of each component in the ceramic substrate can be appropriately expanded, making it easier for the ceramic substrate to be formed.

[0030] In the present invention, the dispersant can be any one or more conventional dispersants in the art. For example, it can be one or two of tributyl phosphate and glyceryl trioleate. Preferably, it is glyceryl trioleate. By adding the dispersant, the casting slurry can be dispersed evenly, reducing the agglomeration and sedimentation of ceramic powder and improving the stability of the green ceramic sheet.

[0031] In the present invention, the binder can be any one or more conventional binders in the art. For example, it can be one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, and polyvinyl butyral, and preferably hydroxypropyl methyl cellulose. After adding the binder to the casting slurry, during the casting process, it can be dispersed among the components. When the solvent volatilizes, its solidification and bonding effects can play a bridging role on the ceramic powder material. Under the action of the binder and each component, the flexural strength of the ceramic substrate is improved.

[0032] In the present invention, the solvent can be any one or more conventional solvents in the art. For example, it can be water and an organic solvent with a weight ratio of 3 - 4:1, and the organic solvent can be one or more of ethanol, n-butanol, and acetone, and preferably ethanol.

[0033] The present invention also provides a method for preparing the above-mentioned high-temperature co-fired multi-layer ceramic substrate, which is used to prepare the above-mentioned high-temperature co-fired multi-layer ceramic substrate, and includes the following steps:

[0034] S1. Mix the remaining raw materials except the solvent, dispersant, and binder, add the solvent and dispersant, perform the first ball milling, add the binder, and perform the second ball milling to obtain a casting slurry;

[0035] S2. Debubble, cast and form, and dry the casting slurry to obtain a green tape;

[0036] S3. Punch, fill the holes, print, stack, laminate, sinter, and cool the green tape to obtain a high-temperature co-fired multi-layer ceramic substrate.

[0037] As a further technical solution, in step S1, during the first ball milling, the speed is 300 - 400 rpm and the time is 1.5 - 2.5 h; during the second ball milling, the speed is 400 - 500 rpm and the time is 1 - 2 h.

[0038] As a further technical solution, in step S3, the punching pressure is 0.5 - 0.7 MPa.

[0039] As a further technical solution, in step S3, the printing material is tungsten paste, and the printing thickness of the tungsten paste is 15 - 20 μm.

[0040] As a further technical solution, in step S3, during the stacking, the number of layers is 35 - 40.

[0041] As a further technical solution, in step S3, during the sintering, the temperature is 1420 - 1550 °C, the time is 30 - 50 min, and the sintering atmosphere is air.

[0042] The working principle and beneficial effects of the present invention are as follows:

[0043] 1. In the present invention, alumina is the main material of the multi-layer ceramic substrate, endowing the multi-layer ceramic substrate with basic strength and stability. Through the combined action of tungsten boride, borate compounds, sintering aids, dispersants, binders and solvents, a multi-layer ceramic substrate with good density is formed during subsequent processing, having excellent flexural strength. Among them, tungsten boride itself has high hardness. When added to the multi-layer ceramic substrate, it can reduce surface damage during the assembly and use of the multi-layer ceramic substrate. At the same time, acting together with alumina, the multi-layer ceramic substrate can have good heat dissipation ability.

[0044] 2. In the present invention, the borate compounds include metaborates and polyborates. By introducing two different borate compounds into the multi-layer ceramic substrate and adjusting the weight ratio of metaborate to polyborate to 1-9:1, during the sintering process, the internal stress generated due to solvent volatilization can be reduced, the densification degree of the internal structure of the ceramic substrate can be improved, thereby improving the flexural strength of the multi-layer ceramic substrate and enhancing the structural stability of the entire ceramic material. Specific Embodiments

[0045] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described 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 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.

[0046] In the following examples and comparative examples, the average particle size of alumina is 10 μm; the average particle size of tungsten boride is 5 μm; the effective component content of sodium metaborate is 99.0%; sodium tetraborate is anhydrous sodium tetraborate, and the effective component content is 99.5%; the viscosity of hydroxypropyl methylcellulose is 150,000 mPa·s; crystalline silica, specifically quartz sand, has an average particle size of 25 μm; amorphous silica, specifically diatomaceous earth, has an average particle size of 25 μm.

[0047] Example 1

[0048] A high-temperature co-fired multi-layer ceramic substrate, the raw materials include the following components in parts by weight:

[0049] 100 parts of alumina, 4 parts of tungsten boride, 6 parts of borate compounds, 1.5 parts of Y2O3, 0.75 parts of Cr2O3, 0.75 parts of La2O3, 2 parts of glyceryl trioleate, 5 parts of hydroxypropyl methylcellulose, 37.5 parts of water, 12.5 parts of ethanol;

[0050] The borate compound includes 3 parts of sodium metaborate and 3 parts of sodium tetraborate;

[0051] A method for preparing a high-temperature co-fired multi-layer ceramic substrate includes the following steps:

[0052] S1. After mixing alumina, tungsten boride, borate compound, Y2O3, Cr2O3, and La2O3, add water, ethanol, and glyceryl trioleate, ball-mill at 300 rpm for 2.5 h, add hydroxypropyl methylcellulose, and ball-mill at 400 rpm for 2 h to obtain a casting slurry;

[0053] S2. Subject the casting slurry to degassing, casting forming, and drying to obtain a green ceramic tape;

[0054] S3. Punch holes in the green ceramic tape under 0.5 MPa, fill the holes, print a tungsten paste material with a thickness of 15 μm, stack 35 layers of green ceramic tapes, laminate them, sinter in an air atmosphere at 1420 °C for 50 min, and then cool to obtain a multi-layer ceramic substrate.

[0055] Example 2

[0056] A high-temperature co-fired multi-layer ceramic substrate, the raw materials of which include the following components in parts by weight:

[0057] 100 parts of alumina, 8 parts of tungsten boride, 16 parts of borate compound, 2.5 parts of Y2O3, 1.25 parts of Cr2O3, 1.25 parts of La2O3, 3 parts of glyceryl trioleate, 8 parts of hydroxypropyl methylcellulose, 42 parts of water, 14 parts of ethanol;

[0058] The borate compound includes 10 parts of sodium metaborate and 6 parts of sodium tetraborate;

[0059] A method for preparing a high-temperature co-fired multi-layer ceramic substrate includes the following steps:

[0060] S1. After mixing alumina, tungsten boride, borate compound, Y2O3, Cr2O3, and La2O3, add water, ethanol, and glyceryl trioleate, ball-mill at 350 rpm for 2 h, add hydroxypropyl methylcellulose, and ball-mill at 450 rpm for 1.5 h to obtain a casting slurry;

[0061] S2. Subject the casting slurry to degassing, casting forming, and drying to obtain a green ceramic tape;

[0062] S3. Punch holes in the green ceramic tape under 0.7 MPa, fill the holes, print a tungsten paste material with a thickness of 20 μm, stack 40 layers of green ceramic tapes, laminate them, sinter in an air atmosphere at 1500 °C for 40 min, and then cool to obtain a multi-layer ceramic substrate.

[0063] Example 3

[0064] A high-temperature co-fired multi-layer ceramic substrate, the raw materials comprising the following components in parts by weight:

[0065] 100 parts of alumina, 12 parts of tungsten boride, 18 parts of borate compound, 3 parts of Y2O3, 1.5 parts of Cr2O3, 1.5 parts of La2O3, 4 parts of glyceryl trioleate, 10 parts of hydroxypropyl methylcellulose, 48 parts of water, 12 parts of ethanol;

[0066] The borate compound comprises 16.2 parts of calcium metaborate and 1.8 parts of potassium pentaborate;

[0067] A method for preparing a high-temperature co-fired multi-layer ceramic substrate, comprising the following steps:

[0068] S1. After mixing alumina, tungsten boride, borate compound, Y2O3, Cr2O3 and La2O3, add water, ethanol and glyceryl trioleate, ball mill at 400 rpm for 1.5 h, add hydroxypropyl methylcellulose, and ball mill at 500 rpm for 1 h to obtain a casting slurry;

[0069] S2. Subject the casting slurry to defoaming, casting and drying to obtain a green ceramic tape;

[0070] S3. Punch and fill holes in the green ceramic tape at 0.7 MPa, print a tungsten paste material with a thickness of 20 μm, stack 40 layers of green ceramic tapes, laminate, sinter at 1550 °C in an air atmosphere for 30 min, and then cool to obtain a multi-layer ceramic substrate.

[0071] Example 4

[0072] The difference between this example and Example 2 is only that, in this example, the borate compound comprises 14.3 parts of sodium metaborate and 1.7 parts of sodium tetraborate.

[0073] Example 5

[0074] The difference between this example and Example 2 is only that, in this example, the borate compound comprises 12 parts of sodium metaborate and 4 parts of sodium tetraborate.

[0075] Example 6

[0076] The difference between this example and Example 2 is only that, in this example, the borate compound comprises 14 parts of sodium metaborate and 2 parts of sodium tetraborate.

[0077] Example 7

[0078] A high-temperature co-fired multi-layer ceramic substrate, the raw materials comprising the following components in parts by weight:

[0079] 100 parts of alumina, 8 parts of tungsten boride, 16 parts of borate compound, 2 parts of crystalline silica, 2.5 parts of Y2O3, 1.25 parts of Cr2O3, 1.25 parts of La2O3, 3 parts of glyceryl trioleate, 8 parts of hydroxypropyl methylcellulose, 42 parts of water, 14 parts of ethanol;

[0080] The borate compound includes 14 parts of sodium metaborate and 2 parts of sodium tetraborate;

[0081] A preparation method of a high-temperature co-fired multi-layer ceramic substrate includes the following steps:

[0082] S1. After mixing alumina, tungsten boride, borate compound, crystalline silica, Y2O3, Cr2O3 and La2O3, add water, ethanol and glyceryl trioleate, ball mill at 350 rpm for 2 h, add hydroxypropyl methylcellulose, and ball mill at 450 rpm for 1.5 h to obtain a casting slurry;

[0083] S2. Bubble-remove, cast and dry the casting slurry to obtain a green ceramic tape;

[0084] S3. Punch holes in the green ceramic tape at 0.7 MPa, fill the holes, print a tungsten paste material with a thickness of 20 μm, stack 40 layers of green ceramic tapes, laminate, sinter at 1500 °C in an air atmosphere for 40 min, and then cool to obtain a multi-layer ceramic substrate.

[0085] Example 8

[0086] The difference between this example and Example 7 is only that in this example, 2 parts of crystalline silica are replaced by 8 parts of crystalline silica.

[0087] Example 9

[0088] A high-temperature co-fired multi-layer ceramic substrate, the raw materials include the following components in parts by weight:

[0089] 100 parts of alumina, 8 parts of tungsten boride, 16 parts of borate compound, 8 parts of titanium composite crystalline silica, 2.5 parts of Y2O3, 1.25 parts of Cr2O3, 1.25 parts of La2O3, 3 parts of glyceryl trioleate, 8 parts of hydroxypropyl methylcellulose, 42 parts of water, 14 parts of ethanol;

[0090] The borate compound includes 14 parts of sodium metaborate and 2 parts of sodium tetraborate;

[0091] The preparation method of titanium composite crystalline silica includes the following steps:

[0092] A1. Add 16 parts of crystalline silica to 16.8 parts of a 2% sodium hydroxide solution by mass, disperse for 15 min, concentrate, and dry to obtain pretreated crystalline silica;

[0093] A2. Dissolve 1 part of titanium acetylacetonate in 20 parts of isopropanol, add the pretreated crystalline silica described above, disperse evenly, concentrate, dry, and calcine at 550 °C for 1.5 h to obtain titanium composite crystalline silica;

[0094] A preparation method of a high-temperature co-fired multi-layer ceramic substrate, comprising the following steps:

[0095] S1. Mix alumina, tungsten boride, borate compounds, titanium composite crystalline silica, Y2O3, Cr2O3, and La2O3, add water, ethanol, and glyceryl trioleate, ball mill at 350 rpm for 2 h, add hydroxypropyl methyl cellulose, and ball mill at 450 rpm for 1.5 h to obtain a casting slurry;

[0096] S2. Subject the casting slurry to defoaming, casting forming, and drying to obtain a green ceramic tape;

[0097] S3. Punch holes in the green ceramic tape under 0.7 MPa, fill the holes, print a tungsten paste material with a thickness of 20 μm, stack 40 layers of the green ceramic tape, laminate, sinter in an air atmosphere at 1500 °C for 40 min, and then cool to obtain a multi-layer ceramic substrate.

[0098] Example 10

[0099] The difference between this example and Example 9 is only that, in the process of preparing titanium composite crystalline silica in this example, 5 parts of titanium acetylacetonate are added.

[0100] Example 11

[0101] The difference between this example and Example 9 is only that, in the process of preparing titanium composite crystalline silica in this example, 2 parts of titanium acetylacetonate are added.

[0102] Example 12

[0103] The difference between this example and Example 9 is only that, in the process of preparing titanium composite crystalline silica in this example, 3 parts of titanium acetylacetonate are added.

[0104] Example 13

[0105] The difference between this example and Example 8 is only that, in this example, the crystalline silica is replaced with an equal amount of amorphous silica.

[0106] Comparative Example 1

[0107] The difference between this comparative example and Example 2 is only that, in this comparative example, sodium tetraborate is replaced with an equal amount of sodium metaborate.

[0108] Comparative Example 2

[0109] The difference between this comparative example and Example 2 is only that in this comparative example, sodium metaborate is replaced with an equal amount of sodium tetraborate.

[0110] Comparative Example 3

[0111] The difference between this comparative example and Example 2 is only that in this comparative example, no borate compound is added.

[0112] Experimental Example 1

[0113] The multi-layer ceramic substrates prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were tested for the flexural strength of the specimens according to the test method specified in GB / T 6569-2006 "Test Method for Flexural Strength of Fine Ceramics". Among them, the three-point bending test method was used, and the test results are shown in Table 1:

[0114] Table 1 Flexural Strength Test Results of Examples 1 to 6 and Comparative Examples 1 to 3

[0115]

[0116] It can be concluded from Table 1 that compared with Comparative Examples 1 to 3, the flexural strength of the multi-layer ceramic substrates prepared in Examples 1 to 6 is improved, indicating that the addition of metaborate and polyborate can improve the flexural strength of the multi-layer ceramic substrates.

[0117] Experimental Example 2

[0118] The multi-layer ceramic substrates prepared in Examples 6 to 13 were tested for the wear rate of the ceramic substrate specimens using a CFT-I type comprehensive tester for material surface properties. Among them, the test load was 5 N, and the test results are shown in Table 2:

[0119] Table 2 Wear Rate Test Results of Examples 6 to 13

[0120]

[0121] It can be seen from Table 2 that compared with Example 6 and Example 13, the wear rate of the multi-layer ceramic substrates prepared in Examples 7 to 12 is reduced, indicating that the introduction of crystalline silica into the multi-layer ceramic substrates can improve the wear resistance of the multi-layer ceramic substrates. Compared with Example 8, the wear rate of the multi-layer ceramic substrates prepared in Examples 9 to 12 is reduced, indicating that by compounding the titanium source and multi-layer silica and through the subsequent sintering process, the wear resistance of the multi-layer ceramic substrates can be improved.

[0122] Experimental Example 3

[0123] The multi-layer ceramic substrates prepared in Examples 1 to 3 were subjected to the following performance tests:

[0124] ① Thermal conductivity: The thermal conductivity of the specimen was measured in accordance with GB / T 32064-2015 "Test Method for Thermal Conductivity and Thermal Diffusivity of Building Materials by Transient Plane Heat Source Method".

[0125] ② Dielectric loss: The dielectric loss of the specimen was measured using a broadband dielectric impedance analyzer E4990A, where the test frequency was 10 9 Hz.

[0126] The test results are shown in Table 3:

[0127] Table 3 Test Results of Thermal Conductivity and Dielectric Loss of Examples 1 to 3

[0128]

[0129] 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 principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-temperature co-fired multi-layer ceramic substrate, characterized in that The raw materials include the following components in parts by weight: 100 parts of alumina, 4 - 12 parts of tungsten boride, 6 - 18 parts of borate compound, 3 - 6 parts of sintering aid, 2 - 4 parts of dispersant, 5 - 10 parts of binder, 50 - 60 parts of solvent; The borate compound includes metaborate and polyborate with a weight ratio of 1 - 9:1; The raw materials further include the following components in parts by weight: 2 - 8 parts of crystalline silica.

2. The high-temperature co-fired multi-layer ceramic substrate according to claim 1, wherein The weight ratio of the metaborate to the polyborate is 3 - 7:

1.

3. A high-temperature co-fired multi-layer ceramic substrate according to claim 1, characterized in that, The metaborate includes one or more of sodium metaborate, calcium metaborate, potassium metaborate; The polyborate includes one of sodium tetraborate and potassium pentaborate.

4. A high-temperature co-fired multi-layer ceramic substrate according to claim 1, characterized in that, The crystalline silica is titanium - composite crystalline silica.

5. A high-temperature co-fired multi-layer ceramic substrate according to claim 4, characterized in that The raw materials of the titanium - composite crystalline silica include crystalline silica and a titanium source with a weight ratio of 16:1 - 5; The titanium source includes one of titanium acetylacetonate and titanium citrate.

6. The high-temperature co-fired multi-layer ceramic substrate according to claim 5, wherein, The preparation method of the titanium - composite crystalline silica includes the following steps: A1. Add the crystalline silica into an alkaline solution, disperse evenly, concentrate, and dry to obtain the pretreated crystalline silica; A2. Dissolve the titanium source in isopropanol, add the pretreated crystalline silica, disperse, concentrate, dry, and calcine to obtain the titanium - composite crystalline silica.

7. A high-temperature co-fired multi-layer ceramic substrate according to claim 5, characterized in that, The weight ratio of the crystalline silica to the titanium source is 16:2 - 3.

8. A high-temperature co-fired multi-layer ceramic substrate according to claim 1, characterized in that, The sintering aid includes one or more of Y2O3, Li2O, Cr2O3, La2O3; The dispersant includes one or two of tributyl phosphate and glyceryl trioleate; The binder includes one or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose, and polyvinyl butyral; The solvent is water and an organic solvent, and the organic solvent includes one or more of ethanol, n - butanol, and acetone.

9. A method for preparing a high-temperature co-fired multi-layer ceramic substrate, which is used to prepare the high-temperature co-fired multi-layer ceramic substrate according to any one of claims 1 to 8, characterized in that, It includes the following steps: S1. Mix the remaining raw materials except the solvent, dispersant, and binder, add the solvent and dispersant, conduct the first ball - milling, add the binder, and conduct the second ball - milling to obtain a casting slurry; S2. Debubble, cast - form, and dry the casting slurry to obtain a green ceramic tape; S3. Punch, fill holes, print, stack, laminate, sinter, and cool the green ceramic tape to obtain a high - temperature co - fired multilayer ceramic substrate.

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