An efficient heat dissipation multi-layer ceramic substrate and its preparation method

Abstract

The present invention relates to the technical field of ceramic substrates, and provides a high-efficiency heat-dissipating multi-layer ceramic substrate and a preparation method thereof. For the multi-layer ceramic substrate, the raw materials include the following components in parts by weight: 110 parts of alumina, 8-16 parts of vanadium pentoxide, 1-3 parts of dispersant, 2-4 parts of sintering aid, 8-12 parts of binder, 0.5-2 parts of plasticizer, and 70 parts of water; the alumina includes alumina I and alumina II with a weight ratio of 4-9:1; the specific surface area of alumina I is 47-76m 2 / g, and the specific surface area of alumina II is 6.8-8m 2 / g. Through the above technical solution, the problem of poor fracture toughness 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 highly heat-dissipating multi-layer ceramic substrate and a preparation method thereof. Background Art

[0002] A multi-layer ceramic substrate is a three-dimensional ceramic substrate processed from multiple ceramic thin sheets through processes such as printing, lamination, and sintering, and internally integrates functional structures such as through holes. Its core functions are to serve as an electrical connection carrier, a mechanical support platform, and a physical protection layer for electronic components, and at the same time undertake the role of signal transmission and heat dissipation. With its unique advantages, this substrate has been widely used in fields such as optical communication, medical equipment, lighting systems, and energy management.

[0003] Traditional multi-layer ceramic substrates are usually prepared mainly from alumina ceramic materials. Due to their relatively high flatness, the contact thermal resistance between the substrate and the load or radiator can be reduced to a certain extent. At the same time, they are highly regarded due to their good heat dissipation ability, chemical stability, oxidation resistance, and low production cost. However, among the many performance indicators of multi-layer ceramic substrates, fracture toughness is one of the core indicators for measuring their reliability. It reflects the ability of the multi-layer ceramic substrate to resist fracture when subjected to external forces, and is closely related to the stability and service life of the multi-layer ceramic substrate in actual applications. The fracture toughness of alumina multi-layer ceramic substrates is relatively low, and when subjected to external forces such as impact, vibration, or thermal stress, they are prone to brittle fracture, generating cracks or even breaking, which limits their application in some application scenarios with dynamic loads or vulnerable to external impacts. Currently, by improving the microstructure of alumina multi-layer ceramic substrates, the fracture toughness of alumina ceramic substrates can be increased to a certain extent. For example, more advanced sintering techniques or the addition of a second phase can be used to achieve the purpose of improving the microstructure. In the addition of the second phase, fiber materials are usually introduced to transform the intergranular fracture mode of traditional alumina powder, thereby improving the fracture toughness of alumina multi-layer ceramic substrates. However, during the sintering process, the fiber materials are easily sintered into one body with the ceramic matrix, resulting in limited improvement in the fracture toughness of alumina multi-layer ceramic substrates.

[0004] In view of this, it is of great significance to develop a multi-layer ceramic substrate that can significantly improve its fracture toughness for expanding its applications. Summary of the Invention

[0005] The present invention provides a highly heat-dissipating multi-layer ceramic substrate and a preparation method thereof, which solve the problem of poor fracture toughness of multi-layer ceramic substrates in related technologies.

[0006] The technical solution of the present invention is as follows:

[0007] The present invention provides a highly heat-dissipating multi-layer ceramic substrate, and the raw materials include the following components in parts by weight:

[0008] 110 parts of alumina, 8 - 16 parts of vanadium pentoxide, 1 - 3 parts of dispersant, 2 - 4 parts of sintering aid, 8 - 12 parts of binder, 0.5 - 2 parts of plasticizer, 70 parts of water;

[0009] The alumina includes alumina I and alumina II with a weight ratio of 4 - 9:1;

[0010] The specific surface area of the alumina I is 47 - 76m 2 / g, and the specific surface area of the alumina II is 6.8 - 8m 2 / g.

[0011] As a further technical solution, the average particle sizes of the alumina I and the alumina II are independently 15 - 50μm.

[0012] As a further technical solution, the weight ratio of the alumina to the vanadium pentoxide is 11:1 - 1.4.

[0013] In the present invention, during the sintering process, vanadium pentoxide can, to a certain extent, fill the pores in the grain boundaries, enhancing the bonding force between grains. And during the sintering process, the grain growth of alumina is often relatively fast. The addition of vanadium pentoxide can appropriately regulate the grain growth rate of alumina, reducing the influence of uneven internal structure of the ceramic substrate caused by large differences in the grain growth size of alumina, thereby further improving the fracture toughness of the multilayer ceramic substrate. When the weight ratio of alumina to vanadium pentoxide is 11:1 - 1.4, the fracture toughness of the multilayer ceramic substrate can be increased to 12.7 - 13.0 , and when the weight ratio of alumina to vanadium pentoxide is outside the range of 11:1 - 1.4, the effect of improving the fracture toughness of the multilayer ceramic substrate becomes worse. It can be seen that for alumina, too much or too little content of vanadium pentoxide will limit the improvement of the fracture toughness of the multilayer ceramic substrate.

[0014] As a further technical solution, the alumina is pretreated alumina, and the raw materials of the pretreated alumina include alumina and polysaccharide with a weight ratio of 25:1 - 5.

[0015] As a further technical solution, the preparation method of the pretreated alumina includes the following steps:

[0016] A1. After adding the polysaccharide to water, perform the first stirring, then add the alumina and perform the second stirring, and then dry to obtain a premix;

[0017] A2. After ball - milling the premix, perform sintering treatment to obtain the pretreated alumina.

[0018] As a further technical solution, the weight ratio of the alumina to the polysaccharide is 25:2 to 3.

[0019] As a further technical solution, the polysaccharide includes one or more of chitosan, dextran, and starch, and preferably chitosan and starch.

[0020] As a further technical solution, the weight ratio of the chitosan to the starch is 4:1.

[0021] As a further technical solution, in step A1, the speeds of the first stirring and the second stirring are each independently 500 to 700 rpm, and the time is 1 to 3 h.

[0022] As a further technical solution, in step A2, the speed of the ball milling is 600 to 800 rpm, and the time is 2 to 3 h.

[0023] As a further technical solution, in step A2, the sintering is divided into first sintering and second sintering;

[0024] During the first sintering, the sintering atmosphere is air, the temperature is 550 to 650 °C, and the time is 2 to 4 h;

[0025] During the second sintering, the sintering atmosphere is nitrogen, the temperature is 1450 to 1550 °C, and the time is 0.5 to 1.5 h;

[0026] The gas flow rate of the nitrogen is 15 to 20 L / min.

[0027] In the present invention, first, the alumina is treated with the polysaccharide, and the content ratio of the polysaccharide and the alumina is reasonably regulated, so that the alumina is combined together during the pretreatment process. Through the subsequent sintering treatment, while assisting in regulating the microstructure of the alumina, it is beneficial to the binding effect between different crystal form alumina particles, making the binding between the crystal grains closer, and improving the bending strength of the multi-layer ceramic substrate.

[0028] In the present invention, the sintering is divided into first sintering and second sintering. The first sintering is carried out in an air atmosphere with a relatively low temperature of 550 to 650 °C. This process mainly plays the role of pretreatment of the alumina by the polysaccharide, enabling the alumina particles to start preliminary crystal growth and laying a foundation for the subsequent high-temperature sintering; the second sintering is carried out in a nitrogen atmosphere with a relatively high temperature of 1450 to 1550 °C. This process mainly further improves the stability of the alumina crystal structure, can further sinter and densify, and alumina with high strength and good stability can be obtained, thereby further improving the bending strength of the multi-layer ceramic substrate.

[0029] As a further technical solution, the sintering aid is Y 2 O3 , YF 3 , B 2 O 3 one or more of;

[0030] The binder is one or two of polyvinyl butyral and hydroxypropyl methylcellulose;

[0031] The plasticizer is one or more of polyethylene glycol, dioctyl phthalate, and polyvinyl alcohol;

[0032] The dispersant is one or more of stearic acid, polyacrylic acid, and polymethacrylic acid.

[0033] As a further technical solution, when the sintering aid is Y 2 O 3 and B 2 O 3 When, the Y 2 O 3 and B 2 O 3 The weight ratio of is 3:1.

[0034] When the sintering aid is Y with a weight ratio of 3:1 2 O 3 and B 2 O 3 it can effectively reduce the sintering temperature of alumina, make the microstructure of the ceramic more uniform, thereby reducing the defect of cracks in the ceramic material in an environment of rapid temperature change, and further improving the fracture toughness and mechanical properties of the multilayer ceramic substrate under the action of vanadium pentoxide and other additives.

[0035] In the process of preparing the multilayer ceramic substrate, alumina itself is difficult to form, and the addition of the binder can directly endow the alumina ceramic material with a certain viscosity, thereby ensuring the integrity and stability of the final multilayer ceramic substrate; the addition of the plasticizer can increase the compatibility between the alumina powder and the binder, promote the binder to better play the binding role, reduce surface defects, and thus improve the comprehensive performance of the multilayer ceramic substrate; the addition of the dispersant, such as stearic acid, polyacrylic acid, and polymethacrylic acid, can adsorb on the surface of the alumina particles, making the alumina particles evenly dispersed in the slurry, and making the particle distribution inside the ceramic substrate more uniform.

[0036] The present invention also provides a method for preparing the above-mentioned high-efficiency heat-dissipating multilayer ceramic substrate, comprising the following steps:

[0037] S1. After mixing the remaining components except the binder once, add the binder and mix them a second time to obtain a slurry;

[0038] S2. Defoam, tape-cast, and dry the slurry to obtain a green ceramic sheet.

[0039] S3. After subjecting the green ceramic sheet to punching, hole filling, surface printing, laminating, pressing, and thermal cutting, co-fire and cool it to obtain the high-efficiency heat dissipation multi-layer ceramic substrate.

[0040] As a further technical solution, in step S1, during the first mixing, the ball milling speed is 300 - 400 rpm and the time is 2 - 3 h; during the second mixing, the ball milling speed is 500 - 700 rpm and the time is 1.5 - 2.5 h.

[0041] As a further technical solution, in step S3, during punching, the punching pressure is 0.4 - 0.6 MPa.

[0042] As a further technical solution, in step S3, during punching, circular micro-holes with a diameter of 0.1 - 0.2 mm can be formed.

[0043] As a further technical solution, in step S3, the raw material for surface printing is tungsten paste, and the thickness formed by the tungsten paste is 10 - 18 μm.

[0044] As a further technical solution, in step S3, the number of layers for laminating is 45 - 55 layers, the temperature for laminating is 40 - 60 °C, and the pressure for laminating is 5 - 9 MPa.

[0045] As a further technical solution, in step S3, during pressing, the pressure is 15 - 20 MPa.

[0046] As a further technical solution, in step S3, during co-firing, the temperature is 950 - 1050 °C and the time is 20 - 40 min.

[0047] The working principle and beneficial effects of the present invention are as follows:

[0048] In the present invention, the multi-layer ceramic substrate uses alumina as the base material, combines vanadium pentoxide, dispersant, sintering aid, binder, and plasticizer to prepare a dense and stable multi-layer ceramic substrate with good fracture toughness; among them, the alumina includes alumina I and alumina II with different specific surface areas. The specific surface area of alumina I is 47 - 76 g / cm 3 , and the specific surface area of alumina II is 6.8 - 8 g / cm 3, during the sintering process, the two types of alumina restrict each other, enabling the growth rate of alumina grains to be moderate and making the internal structure of the ceramic substrate uniformly dense. And when the multi-layer ceramic substrate is subjected to external forces, due to the uniform distribution of the particle gaps formed by alumina I and alumina II, the possibility of stress concentration can be reduced, thereby decreasing the likelihood of crack propagation, improving the fracture toughness of the multi-layer ceramic substrate. Moreover, by optimizing the content ratio of alumina I and alumina II, when the weight ratio of alumina I to alumina II is 4 - 9:1, the effect of improving the fracture toughness of the multi-layer ceramic substrate is optimal. Additionally, the addition of vanadium pentoxide can also improve the fracture toughness of the multi-layer ceramic substrate to a certain extent. Specific Embodiments

[0049] The following will describe in clear and complete detail the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0050] In the following examples and comparative examples, the average particle size of alumina I and alumina II is 25 μm; the average particle size of vanadium pentoxide is 38 μm; the viscosity of hydroxypropyl methylcellulose is 100,000 mPa·s; the model of polyethylene glycol is PEG - 1000; for chitosan, the degree of deacetylation is 90%, and the weight - average molecular weight is 20,000; the starch is corn starch, and the effective ingredient content is 98%.

[0051] Example 1

[0052] A highly efficient heat - dissipating multi - layer ceramic substrate, the raw materials include the following components in parts by weight:

[0053] 110 parts of alumina, 8 parts of vanadium pentoxide, 1 part of stearic acid, 1.5 parts of Y 2 O 3 、0.5 part of B 2 O 3 、8 parts of hydroxypropyl methylcellulose, 0.5 part of polyethylene glycol, 70 parts of water;

[0054] The alumina includes alumina I and alumina II with a weight ratio of 4:1;

[0055] The specific surface area of alumina I is 47 m 2 / g, and the specific surface area of alumina II is 6.8 m 2 / g;

[0056] The preparation method of the highly efficient heat - dissipating multi - layer ceramic substrate includes the following steps:

[0057] S1. Mix the remaining components except hydroxypropyl methylcellulose at a ball milling speed of 300 rpm for 3 h, then add hydroxypropyl methylcellulose and mix at a ball milling speed of 500 rpm for 2.5 h to obtain a slurry.

[0058] S2. Debubble, cast and dry the slurry to obtain a green ceramic sheet.

[0059] S3. Punch the green ceramic sheet at a punching pressure of 0.4 MPa to form circular micro-holes with a diameter of 0.1 mm, then fill the holes. After printing tungsten slurry with a thickness of 15 μm on the surface, stack 45 layers of green ceramic sheets at 40 °C and 5 MPa, press at 15 MPa, perform cutting treatment, co-fire at 950 °C for 40 min, and then cool to obtain a high-efficiency heat dissipation multi-layer ceramic substrate.

[0060] Example 2

[0061] A high-efficiency heat dissipation multi-layer ceramic substrate, the raw materials of which include the following components in parts by weight:

[0062] 110 parts of alumina, 16 parts of vanadium pentoxide, 2 parts of stearic acid, 2.25 parts of Y 2 O 3 、0.75 parts of B 2 O 3 、10 parts of hydroxypropyl methylcellulose, 1.5 parts of polyethylene glycol, 70 parts of water;

[0063] The alumina includes alumina I and alumina II with a weight ratio of 6:1;

[0064] The specific surface area of alumina I is 47 m 2 / g, and the specific surface area of alumina II is 6.8 m 2 / g;

[0065] The preparation method of the high-efficiency heat dissipation multi-layer ceramic substrate includes the following steps:

[0066] S1. Mix the remaining components except hydroxypropyl methylcellulose at a ball milling speed of 350 rpm for 2.5 h, then add hydroxypropyl methylcellulose and mix at a ball milling speed of 600 rpm for 2 h to obtain a slurry.

[0067] S2. Debubble, cast and dry the slurry to obtain a green ceramic sheet.

[0068] S3. Punch the green ceramic sheet under a punching pressure of 0.5 MPa to form circular micro-holes with a diameter of 0.14 mm, then fill the holes. After printing tungsten paste with a thickness of 15 μm on the surface, stack 50 layers of green ceramic sheets at 50 °C and 7 MPa, press them at 18 MPa, perform cutting treatment, co-fire them at 990 °C for 30 min, and then cool to obtain a high-efficiency heat dissipation multi-layer ceramic substrate.

[0069] Example 3

[0070] A high-efficiency heat dissipation multi-layer ceramic substrate, the raw materials of which include the following components in parts by weight:

[0071] 110 parts of alumina, 16 parts of vanadium pentoxide, 3 parts of stearic acid, 3 parts of Y 2 O 3 、1 part of B 2 O 3 、12 parts of hydroxypropyl methylcellulose, 2 parts of polyethylene glycol, 70 parts of water;

[0072] The alumina includes alumina I and alumina II with a weight ratio of 9:1;

[0073] The specific surface area of alumina I is 76 m 2 / g, and the specific surface area of alumina II is 8 m 2 / g;

[0074] A preparation method of a high-efficiency heat dissipation multi-layer ceramic substrate, which includes the following steps:

[0075] S1. Mix the remaining components except hydroxypropyl methylcellulose at a ball milling speed of 400 rpm for 2 h, then add hydroxypropyl methylcellulose and mix at a ball milling speed of 700 rpm for 1.5 h to obtain a slurry;

[0076] S2. Bubble-remove, doctor blade and dry the slurry to obtain a green ceramic sheet;

[0077] S3. Punch the green ceramic sheet under a punching pressure of 0.6 MPa to form circular micro-holes with a diameter of 0.2 mm, then fill the holes. After printing tungsten paste with a thickness of 15 μm on the surface, stack 55 layers of green ceramic sheets at 60 °C and 9 MPa, press them at 20 MPa, perform cutting treatment, co-fire them at 1050 °C for 20 min, and then cool to obtain a high-efficiency heat dissipation multi-layer ceramic substrate.

[0078] Example 4

[0079] The difference between this example and Example 1 is only that in this example, the alumina includes alumina I and alumina II with a weight ratio of 9:1.

[0080] Example 5

[0081] The difference between this example and Example 1 is only that in this example, the addition amount of vanadium pentoxide is 16 parts.

[0082] Example 6

[0083] The difference between this example and Example 1 is only that in this example, the addition amount of vanadium pentoxide is 10 parts.

[0084] Example 7

[0085] The difference between this example and Example 1 is only that in this example, the addition amount of vanadium pentoxide is 14 parts.

[0086] Example 8

[0087] The difference between this example and Example 7 is only that in this example, the alumina is pretreated alumina, and the preparation method of the pretreated alumina includes the following steps:

[0088] A1. Add 4.4 parts of polysaccharide (where the weight ratio of chitosan to starch is 4:1) to 100 parts of water, stir at 500 rpm for 3 h, then add 110 parts of alumina (where the weight ratio of alumina I to alumina II is 4:1), stir at 500 rpm for 3 h, and then dry to obtain a premix;

[0089] A2. Ball mill the premix at 600 rpm for 3 h, then sinter it at 550 °C in an air atmosphere for 4 h, and then sinter it at 1450 °C in a nitrogen atmosphere with a gas flow rate of 15 L / min for 1.5 h to obtain the pretreated alumina.

[0090] Example 9

[0091] The difference between this example and Example 8 is only that in the preparation process of the pretreated alumina in this example, the addition amount of polysaccharide is 22 parts, where the weight ratio of chitosan to starch is 4:1.

[0092] Example 10

[0093] The difference between this example and Example 8 is only that in the preparation process of the pretreated alumina in this example, the addition amount of polysaccharide is 8.8 parts, where the weight ratio of chitosan to starch is 4:1.

[0094] Example 11

[0095] The difference between this example and Example 8 is only that in the preparation process of the pretreated alumina in this example, the addition amount of polysaccharide is 13.2 parts, where the weight ratio of chitosan to starch is 4:1.

[0096] Example 12

[0097] The difference between this embodiment and Embodiment 11 is only that, in this embodiment, the preparation method of the pretreated alumina comprises the following steps:

[0098] A1. Add 13.2 parts of polysaccharide (wherein the weight ratio of chitosan to starch is 4:1) to 100 parts of water, stir at 700 rpm for 1 h, then add 110 parts of alumina (wherein the weight ratio of Alumina I to Alumina II is 4:1), stir at 700 rpm for 1 h, and then dry to obtain a premix;

[0099] A2. Ball-mill the premix at 800 rpm for 2 h, then sinter at 650 °C in an air atmosphere for 2 h, and then sinter at 1550 °C in a nitrogen atmosphere with a gas flow rate of 20 L / min for 0.5 h to obtain the pretreated alumina.

[0100] Comparative Example 1

[0101] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the weight ratio of Alumina I to Alumina II is 1:1.

[0102] Comparative Example 2

[0103] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the weight ratio of Alumina I to Alumina II is 10:1.

[0104] Comparative Example 3

[0105] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, Alumina I is replaced with an equal amount of Alumina II.

[0106] Comparative Example 4

[0107] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, Alumina II is replaced with an equal amount of Alumina I.

[0108] Comparative Example 5

[0109] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the specific surface area of Alumina I is 39 m 2 / g, and the specific surface area of Alumina II is 5 m 2 / g.

[0110] Comparative Example 6

[0111] The difference between this comparative example and Embodiment 1 is only that, in this comparative example, the specific surface area of Alumina I is 100 m 2 / g, and the specific surface area of Alumina II is 11 m 2 / g.

[0112] Comparative Example 7

[0113] The difference between this comparative example and Example 1 is only that in this comparative example, vanadium pentoxide is replaced with an equal amount of zirconium oxide.

[0114] Comparative Example 8

[0115] The difference between this comparative example and Example 1 is only that in this comparative example, vanadium pentoxide is not added.

[0116] Test Example 1

[0117] The multi-layer ceramic substrates prepared in Examples 1 to 7 and Comparative Examples 1 to 8 were tested for fracture toughness according to the method in GB / T 23806-2009 "Test Method for Fracture Toughness of Fine Ceramics - Single Edge Pre-Cracked Beam (SEPB) Method". The test results are shown in Table 1:

[0118] Table 1 Fracture toughness test results of Examples 1 to 7 and Comparative Examples 1 to 8

[0119]

[0120] As can be seen from Table 1, compared with Comparative Examples 1 to 4, the fracture toughness of the multi-layer ceramic substrates prepared in Examples 1 to 6 was significantly improved, indicating that alumina includes Alumina I and Alumina II. The specific surface area of Alumina I is 47 - 76 m 2 / g, and the specific surface area of Alumina II is 6.8 - 8 m 2 / g. By using two different aluminas in combination and adjusting the weight ratio of Alumina I to Alumina II to 4 - 9:1, the fracture toughness of the multi-layer ceramic substrate can be improved. In addition, compared with Comparative Examples 7 to 8, the fracture toughness of the multi-layer ceramic substrates obtained in Example 1 and Examples 5 to 7 was improved, indicating that when vanadium pentoxide and alumina coexist, the fracture toughness of the multi-layer ceramic substrate can also be improved.

[0121] Test Example 2

[0122] The multi-layer ceramic substrates prepared in Examples 7 to 12 were tested for the flexural strength of the test 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 2:

[0123] Table 2 Flexural strength test results of Examples 7 to 12

[0124]

[0125] As can be seen from Table 2, the flexural strength of the multi-layer ceramic substrates prepared in Examples 8 to 12 was higher than that of the multi-layer ceramic substrates prepared in Example 7, indicating that after pretreatment of alumina with polysaccharide, the flexural strength of the multi-layer ceramic substrate can be improved.

[0126] Test Example 3

[0127] The thermal conductivity of the multi-layer ceramic substrates prepared in Examples 1 to 3 was measured according to GB / T 32064-2015 "Transient Plane Heat Source Method for Testing Thermal Conductivity and Thermal Diffusivity of Building Materials". The test results are shown in Table 3:

[0128] Table 3 Test Results of Thermal Conductivity of Examples 1 to 3

[0129]

[0130] The thermal conductivity of the multi-layer ceramic substrates prepared in Examples 1 to 3 was in the range of 34.7 to 38.1 W / (m·k), showing good heat dissipation effect.

[0131] 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-efficiency heat dissipation multilayer ceramic substrate, characterized in that: The raw materials include the following components in parts by weight: 110 parts of aluminum oxide, 8-16 parts of vanadium pentoxide, 1-3 parts of dispersant, 2-4 parts of sintering aid, 8-12 parts of binder, 0.5-2 parts of plasticizer, 70 parts of water; The aluminum oxide includes aluminum oxide I and aluminum oxide II in a weight ratio of 4 to 9:1; The specific surface area of ​​the aluminum oxide I is 47 to 76 m 2 / g, the specific surface area of ​​the aluminum oxide II is 6.8~8m 2 / g; The alumina is pretreated alumina, and the raw materials of the pretreated alumina include alumina and polysaccharide in a weight ratio of 25:2-3.

2. The high-efficiency heat dissipation multilayer ceramic substrate according to claim 1, characterized in that: The weight ratio of the aluminum oxide to the vanadium pentoxide is 11:1-1.

4.

3. The high-efficiency heat dissipation multilayer ceramic substrate according to claim 1, characterized in that: The method for preparing the pretreated aluminum oxide comprises the following steps: A1. After adding polysaccharide to water, stir for the first time, add alumina, stir for the second time, and dry to obtain a premix; A2. After ball milling the premixture, sintering is performed to obtain pretreated alumina.

4. The high-efficiency heat dissipation multilayer ceramic substrate according to claim 1, characterized in that: The polysaccharide includes one or more of chitosan, dextran and starch.

5. The high-efficiency heat dissipation multilayer ceramic substrate according to claim 3, characterized in that: In step A2, the sintering is divided into a first sintering and a second sintering; During the first sintering, the sintering atmosphere is air, the temperature is 550-650°C, and the time is 2-4 hours; During the second sintering, the sintering atmosphere is nitrogen, the temperature is 1450-1550°C, and the time is 0.5-1.5h; The nitrogen gas flow rate is 15-20 L / min.

6. The high-efficiency heat dissipation multilayer ceramic substrate according to claim 1, characterized in that: The sintering aid is one or more of Y2O3, YF3, and B2O3; The binder is one or two of polyvinyl butyral and hydroxypropyl methylcellulose; The plasticizer is one or more of polyethylene glycol, dioctyl phthalate, and polypropylene alcohol; The dispersant is one or more of stearic acid, polyacrylic acid and polymethacrylic acid.

7. The method for preparing a high-efficiency heat dissipation multilayer ceramic substrate according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. After mixing the remaining components except the binder, the binder is added and mixed for a second time to obtain a slurry; S2, subjecting the slurry to degassing, tape casting and drying to obtain a green porcelain sheet; S3, subjecting the raw ceramic sheets to punching, hole filling, surface printing, lamination, pressing, and thermal cutting processes, and then to co-firing and cooling to obtain the high-efficiency heat dissipation multilayer ceramic substrate.

8. The method for preparing a high-efficiency heat dissipation multilayer ceramic substrate according to claim 7, characterized in that: In step S1, during the first mixing, the ball milling speed is 300-400 rpm, and the time is 2-3 h; during the second mixing, the ball milling speed is 500-700 rpm, and the time is 1.5-2.5 h.

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