Aluminum oxide multi-layer ceramic substrate and its preparation method

Abstract

The present invention relates to the technical field of ceramic substrates, and provides an alumina multi-layer ceramic substrate and a preparation method thereof. The alumina multi-layer ceramic substrate comprises the following raw materials in parts by weight: 80-90 parts of pretreated alumina, 1-4 parts of sintering aid, 1-2 parts of dispersant, 6-12 parts of binder, and 85-95 parts of solvent; the preparation method of the pretreated alumina comprises the following steps: wet ball milling, drying, sintering, and pulverizing alumina, manganese dioxide, magnesia, and zirconia to obtain pretreated alumina. Through the above technical solution, the problem that the bending strength of the alumina multi-layer ceramic substrate prepared from alumina raw materials with a purity of 95% in the related art is relatively low is solved.

Description

Technical Field

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

[0002] Alumina ceramic substrates are usually classified according to the purity of alumina in the raw materials. Alumina ceramic substrates can be divided into multiple varieties such as 99 porcelain, 95 porcelain, 90 porcelain, 85 porcelain, etc. Generally speaking, the ceramic substrates prepared from alumina with a purity of 99% are superior in terms of density, mechanical properties, etc., but the cost is relatively high, which limits their large-scale application. In contrast, the 95% purity alumina multi-layer ceramic substrate is expected to have a better balance between cost and performance. However, since the 95% purity alumina raw material inevitably contains impurities such as iron oxide, these impurities will affect the growth of alumina crystals and the bonding between grains during the preparation process of the ceramic substrate, resulting in more micro-defects inside the prepared alumina multi-layer ceramic substrate, and further making its bending strength difficult to meet the growing high-end electronic packaging requirements.

[0003] Therefore, when using the alumina multi-layer ceramic substrate prepared from 95% purity alumina raw material, the problem of poor bending strength of the alumina multi-layer ceramic substrate needs to be solved urgently. Summary of the Invention

[0004] The present invention provides an alumina multi-layer ceramic substrate and a preparation method thereof, which solve the problem of low bending strength of the alumina multi-layer ceramic substrate prepared from 95% purity alumina raw material in the related art.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides an alumina multi-layer ceramic substrate, comprising the following raw materials in parts by weight: 80 - 90 parts of pretreated alumina, 1 - 4 parts of sintering aid, 1 - 2 parts of dispersant, 6 - 12 parts of binder, and 85 - 95 parts of solvent;

[0007] The preparation method of the pretreated alumina comprises the following steps:

[0008] Wet ball milling, drying, sintering, and pulverizing alumina, manganese dioxide, magnesium oxide, and zirconia to obtain pretreated alumina.

[0009] As a further technical solution, the solvent is water.

[0010] As a further technical solution, the mass ratio of alumina, manganese dioxide, and magnesium oxide is 100:1:2 - 3.

[0011] As a further technical solution, the mass ratio of alumina and zirconia is 150:0.5 - 1.5.

[0012] As a further technical solution, the rotation speed during wet ball milling is 800 - 1000 rpm, for example, it can be 800 rpm, 850 rpm, 900 rpm, 950 rpm, 1000 rpm.

[0013] As a further technical solution, the time during wet ball milling is 3 - 5 h, for example, it can be 3 h, 3.5 h, 4 h, 4.5 h, 5 h.

[0014] As a further technical solution, the rotation speed during wet ball milling is 900 rpm and the time is 4 h.

[0015] The sintering temperature is 1000 - 1200 °C and the time is 2 - 3 h.

[0016] As a further technical solution, during wet ball milling, the solvent is anhydrous ethanol.

[0017] As a further technical solution, the mass ratio of the anhydrous ethanol to the alumina is 1 - 2:1.

[0018] As a further technical solution, the particle size of the pretreated alumina is 10 - 15 μm, for example, it can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm.

[0019] As a further technical solution, the sintering aid includes one or more of CeO2, Y2O3, CaO, La2O3; among them, the sintering aid can be CeO2, Y2O3 and CaO, or it can be Y2O3 and CaO; preferably, the sintering aid is CeO2, Y2O3 and CaO with a mass ratio of 1:1:2.

[0020] The present invention selects CeO2, Y2O3 and CaO as the sintering aids for the alumina multi - layer ceramic substrate. CeO2 can reduce the surface energy and inhibit abnormal grain growth. Y2O3 forms a solid solution with alumina, reduces the sintering temperature and enhances the grain boundary bonding force, improving the ceramic density. CaO can promote particle rearrangement and mass transfer, accelerating sintering. Using CeO2, Y2O3 and CaO as the sintering aids for the alumina multi - layer ceramic substrate can ensure the strength and processability of the alumina multi - layer ceramic substrate.

[0021] The dispersant includes one or two of sodium polyacrylate and potassium polyacrylate, preferably sodium polyacrylate;

[0022] The binder includes one or more of carboxymethyl cellulose, polyvinyl alcohol, polyvinyl butyral, preferably polyvinyl alcohol.

[0023] As a further technical solution, the preparation method of the pretreated alumina comprises the following steps:

[0024] A1. Wet ball-mill alumina, manganese sesquioxide, magnesia and zirconia, dry, sinter, and pulverize to obtain a pretreated product;

[0025] A2. Mix the pretreated product with a 2-acetoxybenzoic acid solution, and dry to obtain the pretreated alumina.

[0026] In the present invention, before preparing the alumina multi-layer ceramic substrate, alumina is first wet ball-milled with manganese sesquioxide, magnesia and zirconia. After sintering treatment, 2-acetoxybenzoic acid is further used to compound and pretreat the alumina, effectively improving the fracture toughness of the alumina multi-layer ceramic substrate. Since 2-acetoxybenzoic acid contains a carboxyl group, it can be tightly adsorbed on the surface of the pretreated product particles, increasing the electrostatic repulsion between the particles and improving the dispersibility of the pretreated product. At the same time, the acetoxy part has an affinity for organic substances, which can build a bridge between the pretreated product particles and organic molecules such as binders, improving the compatibility between the two. Finally, a uniform and dense ceramic substrate is obtained, which can better resist cracks, thereby improving the fracture toughness of the alumina multi-layer ceramic substrate.

[0027] As a further technical solution, the mass ratio of the pretreated product to the 2-acetoxybenzoic acid solution is 1:3 to 5.

[0028] As a further technical solution, in the 2-acetoxybenzoic acid solution, the mass ratio of 2-acetoxybenzoic acid to ethanol is 1:10 to 12.

[0029] The present invention also provides a preparation method of an alumina multi-layer ceramic substrate for preparing the above-mentioned alumina multi-layer ceramic substrate, which comprises the following steps:

[0030] S1. Mix the pretreated alumina, sintering aid, dispersant and solvent to obtain a mixture;

[0031] S2. Add a binder to the mixture for mixing, tape-cast, and dry to obtain a green ceramic sheet;

[0032] S3. After punching the green ceramic sheet, perform surface printing, lamination, through-hole connection, cutting, sintering, and cooling to obtain the alumina multi-layer ceramic substrate.

[0033] The working principle and beneficial effects of the present invention are as follows:

[0034] In the present invention, alumina is wet ball-milled with manganese sesquioxide, magnesia, and zirconia, and after sintering treatment, pretreated alumina is obtained. The use of the pretreated alumina significantly improves the flexural strength of the alumina multi-layer ceramic substrate. In the prior art, alumina and other metal compounds are generally directly used as raw materials for ceramic substrates, while in the present invention, alumina pretreated with manganese sesquioxide, magnesia, and zirconia is used as the raw material for ceramic substrates, improving the flexural strength of the alumina multi-layer ceramic substrate from two aspects: impurity combination and sintering temperature reduction. During the wet ball-milling process, alumina, manganese sesquioxide, magnesia, and zirconia are fully mixed, refining the raw material particles and increasing the contact area between substances. During the sintering process, manganese sesquioxide, magnesia, and impurities in alumina form spinel phases. At the same time, after mixing the pretreated alumina with other raw materials to prepare the ceramic substrate, it can also become a reinforcing framework inside the ceramic. Among them, due to its special crystal structure, zirconia undergoes a phase change during the sintering process, absorbing energy and reducing the sintering temperature, which helps the uniform distribution of the spinel phases formed by impurities such as manganese sesquioxide, magnesia, and alumina. Therefore, in the present invention, alumina is wet ball-milled with manganese sesquioxide, magnesia, and zirconia, and after sintering treatment, pretreated alumina is obtained. The use of the pretreated alumina absorbs energy when the ceramic is stressed to prevent crack propagation, significantly improving the flexural strength of the alumina multi-layer ceramic substrate. Detailed implementation mode

[0035] The following will combine 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 a part of the embodiments of the present invention, rather than all 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.

[0036] In the following examples and comparative examples, the purity of alumina is 95%, the particle size is 20 μm, the particle size of manganese sesquioxide is 100 nm, the particle size of magnesia is 10 μm, the particle size of zirconia is 10 μm, the weight-average molecular weight of polyvinyl alcohol is 10,000, the particle size of CeO2 is 100 nm, the particle size of Y2O3 is 100 nm, and the particle size of CaO is 100 nm.

[0037] Example 1

[0038] The alumina multi-layer ceramic substrate includes the following raw materials in parts by weight: 80 parts of pretreated alumina, 1 part of sintering aid, 1 part of sodium polyacrylate, 6 parts of polyvinyl alcohol, and 85 parts of water; the sintering aid is CeO2, Y2O3, and CaO with a mass ratio of 1:1:2;

[0039] The preparation method of the pretreated alumina includes the following steps:

[0040] Wet ball mill alumina, manganese(III) oxide, magnesia and zirconia at 800 rpm for 5 h (the solvent is absolute ethanol, and the mass ratio of absolute ethanol to alumina is 2:1), dry, sinter at 1000 °C for 3 h, and pulverize to obtain pretreated alumina with a particle size of 10 μm; among them, the mass ratio of alumina, manganese(III) oxide and magnesia is 100:1:0.5, and the mass ratio of alumina and zirconia is 150:1.5;

[0041] A method for preparing an alumina multi-layer ceramic substrate, comprising the following steps:

[0042] S1. Mix the pretreated alumina, sintering aid, sodium polyacrylate and water to obtain a mixture;

[0043] S2. Add polyvinyl alcohol to the mixture for mixing, tape-cast and dry to obtain a green ceramic sheet;

[0044] S3. After punching the green ceramic sheet, perform surface printing, lamination (30 layers), through-hole conduction, cutting, sintering, and cooling to obtain an alumina multi-layer ceramic substrate.

[0045] Example 2

[0046] An alumina multi-layer ceramic substrate, comprising the following raw materials in parts by weight: 90 parts of pretreated alumina, 4 parts of sintering aid, 2 parts of sodium polyacrylate, 12 parts of polyvinyl alcohol, and 95 parts of water; the sintering aid is Y2O3 and CaO with a mass ratio of 1:2;

[0047] The preparation method of the pretreated alumina comprises the following steps:

[0048] Wet ball mill alumina, manganese(III) oxide, magnesia and zirconia at 1000 rpm for 3 h (the solvent is absolute ethanol, and the mass ratio of absolute ethanol to alumina is 1:1), dry, sinter at 1200 °C for 2 h, and pulverize to obtain pretreated alumina with a particle size of 15 μm; among them, the mass ratio of alumina, manganese(III) oxide and magnesia is 100:1:0.5, and the mass ratio of alumina and zirconia is 150:1;

[0049] A method for preparing an alumina multi-layer ceramic substrate, comprising the following steps:

[0050] S1. Mix the pretreated alumina, sintering aid, sodium polyacrylate and water to obtain a mixture;

[0051] S2. Add polyvinyl alcohol to the mixture for mixing, tape-cast and dry to obtain a green ceramic sheet;

[0052] S3. After punching the green ceramic sheet, perform surface printing, lamination (30 layers), through-hole conduction, cutting, sintering, and cooling to obtain an alumina multi-layer ceramic substrate.

[0053] Example 3

[0054] The alumina multi-layer ceramic substrate comprises raw materials in the following parts by weight: 85 parts of pretreated alumina, 2 parts of sintering aid, 1.5 parts of sodium polyacrylate, 8 parts of polyvinyl alcohol, and 90 parts of water; the sintering aid is CeO2, Y2O3 and CaO with a mass ratio of 1:1:2.

[0055] The preparation method of the pretreated alumina comprises the following steps:

[0056] Wet ball milling (the solvent is anhydrous ethanol, and the mass ratio of anhydrous ethanol to alumina is 1:1) of alumina, manganese sesquioxide, magnesia and zirconia at a rotation speed of 900 rpm for 4 h, drying, sintering at 1100 °C for 2.5 h, and pulverizing to obtain pretreated alumina with a particle size of 10 μm; wherein, the mass ratio of alumina, manganese sesquioxide and magnesia is 100:1:0.5, and the mass ratio of alumina and zirconia is 150:0.5.

[0057] The preparation method of the alumina multi-layer ceramic substrate comprises the following steps:

[0058] S1. Mix the pretreated alumina, sintering aid, sodium polyacrylate and water to obtain a mixture.

[0059] S2. Add polyvinyl alcohol to the mixture for mixing, casting and forming, and drying to obtain a green ceramic sheet.

[0060] S3. After punching the green ceramic sheet, perform surface printing, lamination (30 layers), upper and lower conduction, cutting, sintering, and cooling to obtain the alumina multi-layer ceramic substrate.

[0061] Example 4

[0062] The difference between this example and Example 3 is only that the mass ratio of alumina, manganese sesquioxide and magnesia is 100:1:4.

[0063] Example 5

[0064] The difference between this example and Example 3 is only that the mass ratio of alumina, manganese sesquioxide and magnesia is 100:1:2.

[0065] Example 6

[0066] The difference between this example and Example 3 is only that the mass ratio of alumina, manganese sesquioxide and magnesia is 100:1:3.

[0067] Example 7

[0068] The difference between this example and Example 6 is only that the preparation method of the pretreated alumina comprises the following steps:

[0069] A1. Wet ball mill alumina, manganese(III) oxide, magnesia, and zirconia at a rotation speed of 900 rpm for 4 h (the solvent is absolute ethanol, and the mass ratio of absolute ethanol to alumina is 1:1), dry, sinter at 1100 °C for 2.5 h, and pulverize to obtain a pretreated product with a particle size of 10 μm; among them, the mass ratio of alumina, manganese(III) oxide, and magnesia is 100:1:3, and the mass ratio of alumina and zirconia is 150:0.5;

[0070] A2. Mix 2-acetoxybenzoic acid and ethanol at a mass ratio of 1:10 to obtain a 2-acetoxybenzoic acid solution, and mix the pretreated product and the 2-acetoxybenzoic acid solution at a mass ratio of 1:5, then dry to obtain pretreated alumina.

[0071] Example 8

[0072] The difference between this example and Example 6 is only that the preparation method of pretreated alumina includes the following steps:

[0073] A1. Wet ball mill alumina, manganese(III) oxide, magnesia, and zirconia at a rotation speed of 900 rpm for 4 h (the solvent is absolute ethanol, and the mass ratio of absolute ethanol to alumina is 1:1), dry, sinter at 1100 °C for 2.5 h, and pulverize to obtain a pretreated product with a particle size of 10 μm; among them, the mass ratio of alumina, manganese(III) oxide, and magnesia is 100:1:3, and the mass ratio of alumina and zirconia is 150:0.5;

[0074] A2. Mix 2-acetoxybenzoic acid and ethanol at a mass ratio of 1:12 to obtain a 2-acetoxybenzoic acid solution, and mix the pretreated product and the 2-acetoxybenzoic acid solution at a mass ratio of 1:3, then dry to obtain pretreated alumina.

[0075] Comparative Example 1

[0076] The difference between this example and Example 3 is only that the preparation method of pretreated alumina includes the following steps:

[0077] Wet ball mill alumina, magnesia, and zirconia at a rotation speed of 900 rpm for 4 h (the solvent is absolute ethanol, and the mass ratio of absolute ethanol to alumina is 1:1), dry, sinter at 1100 °C for 2.5 h, and pulverize to obtain pretreated alumina with a particle size of 10 μm; among them, the mass ratio of alumina and magnesia is 100:0.5, and the mass ratio of alumina and zirconia is 150:0.5.

[0078] Comparative Example 2

[0079] The difference between this example and Example 3 is only that the preparation method of pretreated alumina includes the following steps:

[0080] Aluminum oxide, manganese(III) oxide and zirconium oxide were wet ball milled at a rotation speed of 900 rpm (the solvent was absolute ethanol, and the mass ratio of absolute ethanol to aluminum oxide was 1:1) for 4 h, dried, sintered at 1100 °C for 2.5 h, and pulverized to obtain pretreated aluminum oxide with a particle size of 10 μm; among them, the mass ratio of aluminum oxide to manganese(III) oxide was 100:1, and the mass ratio of aluminum oxide to zirconium oxide was 150:0.5.

[0081] Comparative Example 3

[0082] The difference between this example and Example 3 is only that the preparation method of the pretreated aluminum oxide includes the following steps:

[0083] Aluminum oxide, manganese(III) oxide and magnesium oxide were wet ball milled at a rotation speed of 900 rpm (the solvent was absolute ethanol, and the mass ratio of absolute ethanol to aluminum oxide was 1:1) for 4 h, dried, sintered at 1100 °C for 2.5 h, and pulverized to obtain pretreated aluminum oxide with a particle size of 10 μm; among them, the mass ratio of aluminum oxide, manganese(III) oxide and magnesium oxide was 100:1:0.5.

[0084] Comparative Example 4

[0085] The aluminum oxide multi-layer ceramic substrate comprises the following raw materials in parts by weight: 85 parts of pretreated aluminum oxide, 2 parts of sintering aid, 1.5 parts of sodium polyacrylate, 8 parts of polyvinyl alcohol, and 90 parts of water; the sintering aid is CeO2, Y2O3 and CaO with a mass ratio of 1:1:2;

[0086] The preparation method of the pretreated aluminum oxide includes the following steps:

[0087] Aluminum oxide, manganese(III) oxide, magnesium oxide and zirconium oxide were wet ball milled at a rotation speed of 900 rpm (the solvent was absolute ethanol, and the mass ratio of absolute ethanol to aluminum oxide was 1:1) for 4 h, dried to obtain pretreated aluminum oxide; among them, the mass ratio of aluminum oxide, manganese(III) oxide and magnesium oxide was 100:1:0.5, and the mass ratio of aluminum oxide to zirconium oxide was 150:0.5;

[0088] The preparation method of the aluminum oxide multi-layer ceramic substrate includes the following steps:

[0089] S1. Mix the pretreated aluminum oxide, sintering aid, sodium polyacrylate and water to obtain a mixture;

[0090] S2. Add polyvinyl alcohol to the mixture for mixing, tape casting, and drying to obtain a green ceramic sheet;

[0091] S3. After drilling holes in the green ceramic sheet, perform surface printing, lamination (30 layers), upper and lower conduction, cutting, sintering, and cooling to obtain the aluminum oxide multi-layer ceramic substrate.

[0092] Experimental Example 1

[0093] According to the test method specified in GB / T 6569-2006 "Test Method for Bending Strength of Fine Ceramics", the bending strength tests were respectively carried out on the alumina multi-layer ceramic substrates prepared in Examples 1-6 and Comparative Examples 1-4. The three-point bending method was adopted for the test, and the results are shown in Table 1.

[0094] Table 1 Performance test results

[0095]

[0096] Compared with Comparative Examples 1-4, the alumina multi-layer ceramic substrates obtained in Examples 1-6 have higher bending strength, indicating that alumina, manganese dioxide, magnesium oxide, and zirconia are wet-milled and then sintered to obtain pretreated alumina. Using the pretreated alumina as the raw material for the alumina multi-layer ceramic substrate significantly improves the bending strength of the alumina multi-layer ceramic substrate.

[0097] Experimental Example 2

[0098] According to the specimen requirements and determination method of GB / T 23806-2009 "Test Method for Fracture Toughness of Fine Ceramics - Single Edge Pre-Cracked Beam (SEPB) Method", the fracture toughness tests were respectively carried out on the alumina multi-layer ceramic substrates prepared in Examples 6-8. The test results are shown in Table 2.

[0099] Table 2 Performance test results

[0100]

[0101] Compared with Example 6, the alumina multi-layer ceramic substrates obtained in Examples 7-8 have higher fracture toughness, indicating that further treatment of the pretreated product with 2-acetoxybenzoic acid improves the fracture toughness of the alumina multi-layer ceramic substrate.

[0102] 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. Alumina multi-layer ceramic substrate, characterized in that, It comprises the following raw materials in parts by weight: 80 - 90 parts of pretreated alumina, 1 - 4 parts of sintering aid, 1 - 2 parts of dispersant, 6 - 12 parts of binder, and 85 - 95 parts of solvent; The preparation method of the pretreated alumina comprises the following steps: Wet ball - mill alumina, manganese sesquioxide, magnesia, and zirconia, dry, sinter, and pulverize to obtain pretreated alumina; The mass ratio of the alumina, manganese sesquioxide, and magnesia is 100:1:2 - 3.

2. The alumina multi-layer ceramic substrate according to claim 1, characterized in that, The mass ratio of the alumina and zirconia is 150:0.5 - 1.

5.

3. The alumina multi-layer ceramic substrate according to claim 1, wherein The rotation speed during the wet ball - milling is 800 - 1000 rpm, and the time is 3 - 5 h; The sintering temperature is 1000 - 1200 °C, and the time is 2 - 3 h.

4. The alumina multi-layer ceramic substrate according to claim 1, characterized in that, The particle size of the pretreated alumina is 10 - 15 μm.

5. The alumina multi-layer ceramic substrate according to claim 1, characterized in that, The sintering aid includes one or more of CeO2, Y2O3, CaO, La2O3; The dispersant includes one or both of triethyl phosphate and tributyl phosphate; The binder includes one or more of carboxymethyl cellulose, polyvinyl alcohol, and polyvinyl butyral.

6. The alumina multi-layer ceramic substrate according to claim 1, wherein The preparation method of the pretreated alumina comprises the following steps: A1. Wet ball - mill alumina, manganese sesquioxide, magnesia, and zirconia, dry, sinter, and pulverize to obtain a pretreated product; A2. Mix the pretreated product with a 2 - acetoxybenzoic acid solution, and dry to obtain the pretreated alumina.

7. The alumina multi-layer ceramic substrate according to claim 6, wherein The mass ratio of the pretreated product and the 2 - acetoxybenzoic acid solution is 1:3 - 5.

8. The alumina multi-layer ceramic substrate according to claim 6, wherein In the 2 - acetoxybenzoic acid solution, the mass ratio of 2 - acetoxybenzoic acid and ethanol is 1:10 - 12.

9. A method for preparing an alumina multi-layer ceramic substrate, which is used to prepare the alumina multi-layer ceramic substrate according to any one of claims 1 to 8, characterized in that, It includes the following steps: S1. Mix the pretreated alumina, sintering aid, dispersant, and solvent to obtain a mixture; S2. Add the binder to the mixture for mixing, tape - cast, and dry to obtain a green ceramic sheet; S3. After drilling holes in the green ceramic sheet, perform surface printing, lamination, through - hole connection, cutting, sintering, and cooling to obtain the alumina multi - layer ceramic substrate.

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