A multi-layer ceramic substrate and a preparation method thereof

Abstract

The present invention relates to the technical field of ceramic materials, and provides a multi-layer ceramic substrate and a preparation method thereof. The multi-layer ceramic substrate comprises raw materials in the following parts by weight: 100 parts of alumina, 2-3 parts of toughening agent, 3-6 parts of sintering aid, 2-3 parts of dispersant, 4-8 parts of binder, 0.5-1 part of auxiliary agent, 4-6 parts of polyvinyl alcohol, and 30-35 parts of solvent; the auxiliary agent is composed of calcium carboxymethyl cellulose and calcium 2,5-dihydroxybenzenesulfonate with a weight ratio of 1:1-3. Through the above technical solution, the problem of poor bending strength of the ceramic substrate in the related art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and specifically, to a multi-layer ceramic substrate and a preparation method thereof. Background Art

[0002] In the era of the rapid development of modern electronic information technology, electronic devices are making great strides towards miniaturization, light weight, high performance, and multi-functional integration. This development trend poses more stringent requirements on the ceramic substrate, which is a core basic component of electronic devices.

[0003] Among many electronic devices, such as smartphones, a large number of complex circuit functions need to be integrated inside, including high-performance processors, advanced radio frequency modules, large-capacity storage units, etc.; in addition, electronic devices in the aerospace field face extreme working environments and have extremely high requirements for the stability, reliability, and heat dissipation performance of the devices. These application scenarios urgently require the ceramic substrate to have higher integration, more excellent electrical performance, good heat dissipation ability, and reliable mechanical performance.

[0004] Traditional single-layer ceramic substrates gradually expose many limitations when dealing with these demands. For example, the number of electronic components that a single-layer ceramic substrate can carry is limited, making it difficult to meet the wiring requirements of complex circuit designs and unable to achieve a highly integrated circuit layout. In terms of signal transmission, in the case of high-frequency and high-speed signal transmission in a single-layer structure, problems such as signal distortion, delay, and excessive loss are likely to occur, seriously affecting the performance improvement of electronic devices. To solve these problems, multi-layer ceramic substrates have emerged.

[0005] However, in the preparation process of multi-layer ceramic substrates, the dispersibility of alumina in the ceramic slurry cannot be well controlled. Therefore, as the number of layers of the multi-layer ceramic substrate increases, this non-uniformity will gradually accumulate, and the problem of poor alumina dispersibility will become more prominent, restricting the further improvement of the bending strength of the multi-layer ceramic substrate. Therefore, it is necessary to improve the dispersibility of alumina in the ceramic slurry to improve the bending strength of the ceramic substrate. Summary of the Invention

[0006] The present invention provides a multi-layer ceramic substrate and a preparation method thereof, which solve the problem of poor bending strength of the ceramic substrate in the related art.

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

[0008] The present invention provides a multi-layer ceramic substrate, which comprises raw materials with the following parts by weight: 100 parts of alumina, 2 - 3 parts of toughening agent, 3 - 6 parts of sintering aid, 2 - 3 parts of dispersant, 4 - 8 parts of binder, 0.5 - 1 part of additive, 4 - 6 parts of polyvinyl alcohol, and 30 - 35 parts of solvent; the additive is composed of calcium carboxymethyl cellulose and calcium 2,5-dihydroxybenzenesulfonate.

[0009] As a further technical solution, the mass ratio of the calcium carboxymethylcellulose to the calcium 2,5-dihydroxybenzenesulfonate is 1:1 to 3.

[0010] As a further technical solution, the mass ratio of the calcium carboxymethylcellulose to the calcium 2,5-dihydroxybenzenesulfonate is 1:2.

[0011] As a further technical solution, the solvent is water.

[0012] As a further technical solution, the sintering aid includes calcium oxide, beryllium oxide and strontium oxide.

[0013] In the present invention, the sintering aid can not only form a eutectic or solid solution with low melting point with other components in the ceramic substrate, but also promote the density of sintering, and can also make oxygen ions migrate more easily, thereby reducing the pores and defects inside the ceramic and improving the bending strength of the ceramic substrate.

[0014] As a further technical solution, the preparation method of the sintering aid is: adding calcium oxide, beryllium oxide and strontium oxide into water, adding aliphatic polyoxyethylene ether, and after mixing and drying, the sintering aid is obtained.

[0015] As a further technical solution, the temperature of the mixing is 30°C and the time of the mixing is 1 h.

[0016] As a further technical solution, the mass ratio of the calcium oxide, the beryllium oxide and the strontium oxide is 1:2:1.

[0017] As a further technical solution, the addition amount of the aliphatic polyoxyethylene ether is 3% of the sum of the masses of the calcium oxide, the beryllium oxide and the strontium oxide.

[0018] As a further technical solution, the ratio of the mass of the solvent to the sum of the masses of the calcium oxide, the beryllium oxide and the strontium oxide is 20:1.

[0019] As a further technical solution, the HLB of the aliphatic polyoxyethylene ether is 6 to 13, and can be 6 to 7, 9 to 10, 12 to 13, and preferably 9 to 10.

[0020] In the present invention, adding aliphatic polyoxyethylene ether during the preparation of the sintering aid can reduce the surface tension of the solvent, avoid the agglomeration of calcium oxide, beryllium oxide and strontium oxide, and enable the components of the sintering aid to be evenly distributed, so that they can play a more sufficient and uniform role in subsequent sintering, thereby improving the bending strength of the ceramic substrate. Aliphatic polyoxyethylene ethers with different HLB values have different hydrophilic-lipophilic properties. The inventor found that the HLB value of aliphatic polyoxyethylene ether affects the bending strength of the ceramic substrate. When the HLB value is 9-10, it can interact better with calcium oxide, beryllium oxide and strontium oxide, prevent the agglomeration of the three sintering aids, and has a certain steric hindrance stabilization effect. However, when the HLB value of aliphatic polyoxyethylene ether is not in the range of 9-10, the bending strength of the ceramic substrate decreases.

[0021] As a further technical solution, the toughening agent includes cerium oxide, alumina fiber, and yttrium oxide.

[0022] As a further technical solution, the mass ratio of cerium oxide, alumina fiber, and yttrium oxide is 1:4:1.

[0023] As a further technical solution, the addition amount of the organic amine substance is 4% of the sum of the masses of alumina fiber, cerium oxide, and yttrium oxide.

[0024] As a further technical solution, the preparation method of the toughening agent is: adding cerium oxide, alumina fiber, and yttrium oxide into ethanol, and then adding an organic amine substance and mixing and drying to obtain the toughening agent.

[0025] As a further technical solution, the temperature of the mixing is 30°C and the mixing time is 1 h.

[0026] As a further technical solution, the ratio of the mass of the solvent to the sum of the masses of cerium oxide, alumina fiber, and yttrium oxide is 20:1.

[0027] Alumina fiber can play a role in bridging cracks in the ceramic matrix and improve the fracture toughness of the ceramic matrix; when subjected to external forces, cerium oxide can inhibit the growth of grains during sintering, making the grain size of the ceramic matrix finer and more uniform, thereby improving the fracture toughness of the ceramic substrate. Moreover, when the ceramic substrate is subjected to external forces, cerium oxide will undergo volume expansion, hinder the propagation of cracks, and improve the fracture toughness of the ceramic matrix; yttrium oxide can be dissolved into the lattice of the ceramic matrix, increase dislocation movement, and improve the fracture toughness of the ceramic substrate. Through the combination of cerium oxide, alumina fiber, and yttrium oxide, the fracture toughness of the ceramic substrate can be better improved; the addition of organic amine substances can improve the dispersibility of cerium oxide, alumina fiber, and yttrium oxide, and the uniformly distributed toughening agent can better improve the fracture toughness of the ceramic substrate.

[0028] As a further technical solution, the organic amine substances include one or more of ethylenediamine, diethylenetriamine, and triethylenetetramine.

[0029] As a further technical solution, the organic amine substance is diethylenetriamine.

[0030] The inventor found in the process of preparing the toughening agent that selecting diethylenetriamine can further improve the fracture toughness of the ceramic substrate.

[0031] As a further technical solution, the binder includes one or more of polyvinyl alcohol, polyvinyl butyral, and polyacrylate.

[0032] As a further technical solution, the dispersant includes one or more of acrylate, polyvinylpyrrolidone, and triethyl phosphate.

[0033] The present invention also provides a method for preparing a multi-layer ceramic substrate, comprising the following steps:

[0034] S1. Weigh alumina, plasticizer, sintering aid, dispersant, additive, polyvinyl alcohol, and solvent, and stir to obtain a mixture;

[0035] S2. Add a binder to the mixture and stir to obtain a slurry. The slurry is formed by doctor blading to obtain a green ceramic sheet;

[0036] S3. After punching the green ceramic sheet, perform surface printing, lamination, through-hole conduction, cutting, and sintering, and cool to obtain a multi-layer ceramic substrate.

[0037] As a further technical solution, in S3, the sintering is carried out at a heating rate of 5-10 °C, heated to 1400-1450 °C, and held for 8-10 h.

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

[0039] In the present invention, on the basis of adding a dispersant, adding a specific proportion of calcium carboxymethylcellulose and calcium 2,5-dihydroxybenzenesulfonate to the multi-layer ceramic substrate can better improve the dispersibility of alumina in the preparation process, improve the density of the material during the forming process, and reduce internal defects; the addition of polyvinyl alcohol can also be used as a plasticizer to improve the mechanical properties of the multi-layer ceramic substrate, which helps to improve the bending strength of the multi-layer ceramic substrate. Specific embodiments

[0040] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. 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 creative efforts fall within the scope of protection of the present invention.

[0041] In the following examples and comparative examples:

[0042] Fatty alcohol polyoxyethylene ether - 3, HLB 6 - 7; fatty alcohol polyoxyethylene ether - 4, HLB 9 - 10; fatty alcohol polyoxyethylene ether - 7, HLB 12 - 13; alumina, average particle size 50 nm; calcium oxide, average particle size 44 μm; beryllium oxide, average particle size 1 μm; strontium oxide, average particle size 1 μm; alumina fiber, model 95, manufacturer Shandong Dongheng Guoxian New Materials Co., Ltd.; calcium carboxymethyl cellulose: model 01, manufacturer Shandong Gukang Bio - engineering Co., Ltd.

[0043] Example 1

[0044] A preparation method of a multi - layer ceramic substrate includes the following steps:

[0045] S1. Weigh 100 parts of alumina, 3 parts of sintering aid, 0.5 part of additive, 2 parts of acrylate, 4 parts of polyvinyl alcohol 200, 2 parts of toughening agent, and 30 parts of water, and stir to obtain a mixture; wherein the sintering aid is obtained by uniformly mixing calcium oxide, beryllium oxide, and strontium oxide with a mass ratio of 1:2:1; the toughening agent is obtained by uniformly mixing cerium oxide, alumina fiber, and yttrium oxide with a mass ratio of 1:4:1; the additive is composed of calcium carboxymethyl cellulose and calcium 2,5 - dihydroxybenzenesulfonate with a mass ratio of 1:1;

[0046] S2. Add 4 parts of polyvinyl alcohol 2488 to the mixture, stir to obtain a slurry, and the slurry is formed by doctor - blading to obtain a green ceramic sheet;

[0047] S3. After punching the green ceramic sheet, perform surface printing, lamination, through - hole connection, cutting, and then heat it to 1400 °C at a heating rate of 5 °C, hold for 10 h, and cool to obtain a multi - layer ceramic substrate (40 layers).

[0048] Example 2

[0049] S1. Weigh 100 parts of alumina, 6 parts of sintering aid, 1 part of additive, 3 parts of acrylate, 6 parts of polyvinyl alcohol 200, 3 parts of toughening agent, and 35 parts of water, and stir to obtain a mixture. The sintering aid is obtained by uniformly mixing calcium oxide, beryllium oxide, and strontium oxide with a mass ratio of 1:2:1. The toughening agent is obtained by uniformly mixing cerium oxide, alumina fiber, and yttrium oxide with a mass ratio of 1:4:1. The additive is composed of calcium carboxymethyl cellulose and calcium 2,5-dihydroxybenzenesulfonate with a mass ratio of 1:1.

[0050] S2. Add 8 parts of polyvinyl alcohol 2488 to the mixture, stir to obtain a slurry, and the slurry is formed by casting to obtain a green ceramic sheet.

[0051] S3. After drilling holes in the green ceramic sheet, it is subjected to surface printing, lamination, through-hole connection, cutting, and heated at a heating rate of 10 °C to 1450 °C, held for 8 h, and cooled to obtain a multi-layer ceramic substrate (40 layers).

[0052] Example 3

[0053] Compared with Example 1, the only difference is that the additive is composed of calcium carboxymethyl cellulose and calcium 2,5-dihydroxybenzenesulfonate with a mass ratio of 1:2.

[0054] Example 4

[0055] Compared with Example 1, the only difference is that the additive is composed of calcium carboxymethyl cellulose and calcium 2,5-dihydroxybenzenesulfonate with a mass ratio of 1:3.

[0056] Example 5

[0057] Compared with Example 3, the only difference is the preparation method of the sintering aid. The preparation method of the sintering aid in this example is as follows: Add calcium oxide, beryllium oxide, and strontium oxide with a mass ratio of 1:2:1 to water, add aliphatic polyoxyethylene ether-3, mix at 30 °C for 1 h, and then dry to obtain the sintering aid. The addition amount of aliphatic polyoxyethylene ether is 3% of the total mass of calcium oxide, beryllium oxide, and strontium oxide; the mass ratio of water to the total mass of calcium oxide, beryllium oxide, and strontium oxide is 20:1.

[0058] Example 6

[0059] Compared with Example 5, the only difference is that aliphatic polyoxyethylene ether-3 is replaced with an equal amount of aliphatic polyoxyethylene ether-4.

[0060] Example 7

[0061] Compared with Example 5, the only difference is that aliphatic polyoxyethylene ether-3 is replaced with an equal amount of aliphatic polyoxyethylene ether-7.

[0062] Example 8

[0063] Compared with Example 6, the only difference is that the preparation method of the toughening agent is different. The preparation method of the toughening agent in this example is as follows: Cerium oxide, alumina fiber, and yttrium oxide with a mass ratio of 1:4:1 are added to ethanol, ethylenediamine is added, and after mixing at 30 °C for 1 h, it is dried to obtain the toughening agent; the addition amount of ethylenediamine is 4% of the sum of the masses of alumina fiber, cerium oxide, and yttrium oxide; the mass ratio of ethanol to the sum of the masses of cerium oxide, alumina fiber, and yttrium oxide is 20:1.

[0064] Example 9

[0065] Compared with Example 8, the only difference is that ethylenediamine is replaced with an equal amount of diethylenetriamine.

[0066] Example 10

[0067] Compared with Example 8, the only difference is that ethylenediamine is replaced with an equal amount of triethylenetetramine.

[0068] Comparative Example 1

[0069] Compared with Example 1, no additive is added.

[0070] Comparative Example 2

[0071] Compared with Example 1, calcium 2,5-dihydroxybenzenesulfonate is replaced with an equal amount of calcium carboxymethylcellulose.

[0072] Comparative Example 3

[0073] Compared with Example 1, calcium carboxymethylcellulose is replaced with an equal amount of calcium 2,5-dihydroxybenzenesulfonate.

[0074] Experimental Example 1

[0075] According to the specimen requirements in GB / T 6569-2006 "Test Method for Flexural Strength of Fine Ceramics" (the specimen preparation method is: heating the green ceramic sheet at a heating rate of 5 °C to 1400 °C, holding for 10 h, and cooling to obtain), and the measurement method, the flexural strength of the single-layer ceramic substrates in Examples 1 to 7 and Comparative Examples 1 to 3 was measured. The test method was three-point bending, and the measurement results are shown in Table 1.

[0076] Table 1

[0077]

[0078] The flexural strengths in Examples 1 to 7 of the present invention are all higher than those in Comparative Examples 1 to 3, and the flexural strength in Example 6 is as high as 518 MPa, which can better meet the requirements in the actual use process.

[0079] Experimental Example 2

[0080] According to the specimen requirements and measurement methods of GB / T 23806-2009 "Test Method for Fracture Toughness of Fine Ceramics - Single Edge Pre-Cracked Beam (SEPB) Method", the fracture toughness of the specimens in Examples 6, 8 to 10 (the specimen preparation method is the same as that in Experimental Example 1) was measured, and the measurement results are shown in Table 2.

[0081] Table 2

[0082]

[0083] As can be seen from Table 2, the fracture toughness in Examples 8 to 10 is better than that in Example 6, indicating that adding organic amine substances can improve the fracture toughness of the ceramic substrate.

[0084] Experimental Example 3

[0085] According to the measurement method of the dielectric constant in GB / T 5594.4-2015 "Test Methods for Properties of Structural Ceramic Materials for Electronic Components - Part 4: Methods for Measuring Dielectric Constant and Dissipation Factor", the dielectric constant of the specimen (the specimen preparation method is the same as that in Experimental Example 1) was measured, and the results are shown in Table 3.

[0086] Table 3

[0087]

[0088] As can be seen from Table 3, the dielectric constant of the ceramic substrate in the present invention can meet the requirements of actual use.

[0089] 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 principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-layer ceramic substrate, characterized in that, Raw materials comprising the following components in parts by weight: 100 parts of alumina, 2 - 3 parts of toughening agent, 3 - 6 parts of sintering aid, 2 - 3 parts of dispersant, 4 - 8 parts of binder, 0.5 - 1 part of additive, 4 - 6 parts of polyvinyl alcohol, 30 - 35 parts of solvent; the additive is composed of calcium carboxymethyl cellulose and calcium 2,5 - dihydroxybenzenesulfonate in a weight ratio of 1:1 - 3; The preparation method of the toughening agent is: adding cerium oxide, alumina fiber, and yttrium oxide into ethanol, then adding organic amine substances, and mixing and drying to obtain the toughening agent; The organic amine substances include one or more of ethylenediamine, diethylenetriamine, and triethylenetetramine.

2. A multi-layer ceramic substrate according to claim 1, wherein The sintering aid includes calcium oxide, beryllium oxide, and strontium oxide.

3. A multi-layer ceramic substrate according to claim 2, wherein, The preparation method of the sintering aid is: adding calcium oxide, beryllium oxide, and strontium oxide into water, adding aliphatic polyoxyethylene ether, and after mixing and drying, obtaining the sintering aid.

4. A multi-layer ceramic substrate according to claim 3, characterized in that, The HLB of the aliphatic polyoxyethylene ether is 6 - 13.

5. A multi-layer ceramic substrate according to claim 1, characterized in that, The binder includes one or more of polyvinyl alcohol, polyvinyl butyral, and polyacrylate.

6. A multi-layer ceramic substrate according to claim 1, characterized in that, The dispersant includes one or more of acrylate, polyvinylpyrrolidone, and triethyl phosphate.

7. A method for preparing a multi-layer ceramic substrate according to any one of claims 1 to 6, characterized in that Comprising the following steps: S1. Weigh alumina, plasticizer, sintering aid, dispersant, additive, polyvinyl alcohol, and solvent, and stir to obtain a mixture; S2. Add the binder to the mixture and stir to obtain a slurry, and the slurry is formed by doctor - blading to obtain a green ceramic sheet; S3. After drilling the green ceramic sheet, it undergoes surface printing, lamination, through - hole conduction, cutting, sintering, and cooling to obtain a multilayer ceramic substrate.

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