Alumina ceramic substrate and preparation method thereof

Abstract

The invention relates to the field of ceramic materials, in particular to an aluminum oxide ceramic substrate and a preparation method thereof.The preparation method comprises the steps that alpha-Al2O3, a sintering aid, a black pigment, deionized water and sodium polyacrylate are mixed and subjected to ball milling to obtain first slurry, organic monomers and N, N-methylene bisacrylamide are added into the first slurry, ball milling is conducted again to obtain second slurry, and the second slurry is added into the sintering aid and subjected to ball milling to obtain the aluminum oxide ceramic substrate; adding tetramethylethylenediamine and a free radical initiator into the second slurry, uniformly stirring, performing vacuum defoaming, injecting into a mold, performing curing molding, demolding to obtain a green body, and finally putting the green body into a muffle furnace for sintering, so that the aluminum oxide ceramic substrate prepared by the method is dark black in color and relatively excellent in mechanical strength.

Description

Technical Field

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

[0002] Alumina has the advantages of high strength, high thermal conductivity, strong corrosion resistance, good insulation performance and low cost, and is widely used in packaging substrate materials. Common alumina substrates are white and are used as LED substrates, high-frequency circuit substrates, etc. In the semiconductor integrated circuit industry, since many electronic devices (such as digital cameras, etc.) have obvious photosensitivity, the packaging substrates used need to have light-shielding properties to avoid reflecting light. Obviously, white alumina substrates cannot meet this requirement, so black alumina products have been developed, and the demand for black alumina ceramic substrates is increasing due to their unique light-shielding properties.

[0003] In the prior art, a large amount of heavy metal (such as chromium, nickel, etc.) coloring oxides is required for the preparation of black alumina ceramics. These heavy metal coloring oxides are volatile during high-temperature sintering, which is neither environmentally friendly nor affects the actual coloring effect. Summary of the Invention

[0004] Object of the Invention: Aiming at the above technical problems, the present invention provides an alumina ceramic substrate and a preparation method thereof.

[0005] The technical solution adopted is as follows: A preparation method of an alumina ceramic substrate is as follows: Mix α-Al2O3, sintering aid, black pigment, deionized water and sodium polyacrylate and ball-mill to obtain a first slurry. Add an organic monomer and N,N-methylenebisacrylamide to the first slurry, and ball-mill again to obtain a second slurry. Add tetramethylethylenediamine and a radical initiator to the second slurry and stir evenly. Then, after vacuum defoaming, inject it into a mold for curing and forming. After demolding, a green body is obtained. Finally, put the green body into a muffle furnace for sintering. The black pigment is composed of Cu x Ti 1-x O2, Fe2O3 and CoAl2O4, where 0 < x ≤ 0.1.

[0006] Further, x = 0.1.

[0007] Further, the mass ratio of Cu x Ti 1-x O2, Fe2O3 and CoAl2O4 is 2:1:1.

[0008] Further, the mass ratio of α-Al2O3, sintering aid and black pigment is 90-100:5-10:1-5.

[0009] Furthermore, the sintering aid is composed of B2O3, SiO2, MgO, and YF3 with a mass ratio of 1-2:1-2:3-6:1-2.

[0010] Furthermore, the organic monomer is composed of methacrylamide, acrylamide, and allyl benzoate with a mass ratio of 1-2:5-10:0.1-0.5.

[0011] Furthermore, the temperature for curing and forming is 60-80 °C.

[0012] Furthermore, the Cu x Ti 1-x O2 is prepared as follows: Dissolve tetrabutyl titanate in absolute ethanol to obtain solution A. Dissolve copper nitrate in deionized water, then add absolute ethanol and concentrated nitric acid to obtain solution B. Drop solution A into solution B, mix well after dropping, heat in a water bath at 70-90 °C for 1-5 h, then remove the water bath, and let it stand at room temperature for aging for 10-20 h to obtain a sol. The sol is freeze-dried at low temperature and then calcined at 300-400 °C for 1-5 h.

[0013] Furthermore, the sintering temperature is 1250-1350 °C, and the sintering time is 1-5 h.

[0014] Furthermore, during sintering, first heat up at a rate of 0.1-1 °C / min to 600-800 °C, keep it warm for 10-60 min, and then heat up to the sintering temperature at a rate of 5-10 °C / min.

[0015] The present invention provides an alumina ceramic substrate, which is prepared by the preparation method of the above-mentioned alumina ceramic substrate.

[0016] Advantages of the present invention: The present invention provides an alumina ceramic substrate, using Cu x Ti 1-x O2, Fe2O3, and CoAl2O4 combination as the black pigment. Not only does the obtained alumina ceramic substrate have good color development effect, high black purity, and good coloring stability, but also the use of heavy metals (such as chromium, nickel, etc.) is reduced, and the flexural strength of the alumina ceramic substrate is also improved, which is beneficial to the expansion of the application fields of the alumina ceramic substrate; B2O3 will form a liquid phase during sintering, reducing the sintering temperature, promoting mass transfer and rearrangement between alumina particles, thus accelerating the densification process of alumina ceramic substrates, improving the mechanical strength, and also avoiding unstable coloring caused by too high sintering temperature. The addition of SiO2 can fill the voids between alumina particles, improve the compactness of alumina ceramic substrates, and prevent excessive growth of alumina particles during sintering, thus ensuring dimensional accuracy and surface finish. MgO can not only reduce the sintering temperature, but also significantly improve the density and mechanical properties. YF3, as a flux, can react with alumina particles at high temperature, promoting the combination between alumina particles, thus improving the sintering performance of alumina and improving the crystal structure and microstructure of alumina; ‌ The alumina ceramic substrate of the present invention is prepared by a gel-casting molding process, which can effectively reduce the number and size of green body defects during molding, eliminate or reduce the density gradient, and is easy to be machined. The addition of allyl benzoate as an organic monomer can not only achieve in-situ curing through the polymerization reaction of the organic monomer, but also has a certain plasticizing effect, improving the processing performance and molding effect of the ceramic green body, and enhancing the mechanical strength after sintering. After testing, the color of the alumina ceramic substrate prepared by the present invention is dark black, and the mechanical strength is relatively excellent. Brief Description of the Drawings

[0017] Figure 1 It is a photograph of the alumina ceramic substrate prepared in Example 1. Detailed Description of the Invention

[0018] For those not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase. The technologies not mentioned in the present invention refer to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel tests and adopt the same treatment steps and parameters.

[0019] Example 1: A preparation method of an alumina ceramic substrate: 95 g of α-Al2O3, 9 g of sintering aid, 4 g of black pigment, 200 ml of deionized water and 0.5 g of sodium polyacrylate were added to a ball mill jar, and after mixing and ball milling on a planetary ball mill for 10 h, a first slurry was obtained. 23 g of organic monomer and 1 g of N,N-methylenebisacrylamide were added to the first slurry, and after ball milling for another 5 h, a second slurry was obtained. 0.05 g of tetramethylethylenediamine and 0.1 g of free radical initiator were added to the second slurry and stirred for 10 min to make it uniformly mixed. After degassing under vacuum, it was injected into a mold and cured at 70 °C for 60 min to form a shape. After demolding, a green body was obtained. Finally, the green body was placed in a muffle furnace for sintering. During sintering, it was first heated to 650 °C at a rate of 0.1 °C / min, held for 60 min, and then heated to 1300 °C at a rate of 10 °C / min and sintered for 2 h to obtain an alumina ceramic substrate. For details, please refer to Figure 1 photos; Among them, the black pigment consists of Cu 0.1 Ti 0.9 O2, Fe2O3 and CoAl2O4 with a mass ratio of 2:1:1; The sintering aid consists of B2O3, SiO2, MgO, YF3 with a mass ratio of 1:2:5:1; The organic monomer consists of methacrylamide, acrylamide and allyl benzoate with a mass ratio of 1:10:0.5; Cu 0.1 Ti 0.9 The preparation method of O2 is as follows: 30.6 g (0.09 mol) of tetrabutyl titanate was dissolved in 100 ml of absolute ethanol to obtain solution A. 1.876 g (0.01 mol) of copper nitrate was dissolved in 120 ml of deionized water, then 120 ml of absolute ethanol and 24 ml of concentrated nitric acid were added and mixed evenly to obtain solution B. Solution A was added dropwise to solution B. After dropping, it was stirred for 10 min to mix evenly, and then placed in an 80 °C water bath and heated for 2 h. After removing the water bath, it was left to stand at room temperature for aging for 15 h to obtain a sol. The sol was freeze-dried at -50 °C and then calcined at 400 °C for 2 h.

[0020] Example 2: A preparation method of an alumina ceramic substrate: 95 g of α-Al2O3, 9 g of sintering aid, 4 g of black pigment, 200 ml of deionized water and 0.5 g of sodium polyacrylate were added to a ball mill jar, and after mixing and ball milling on a planetary ball mill for 10 h, a first slurry was obtained. 23 g of organic monomer and 1 g of N,N-methylenebisacrylamide were added to the first slurry, and after ball milling for another 5 h, a second slurry was obtained. 0.05 g of tetramethylethylenediamine and 0.1 g of free radical initiator were added to the second slurry and stirred for 10 min to make the mixture uniform. After vacuum degassing, it was poured into a mold and cured at 70 °C for 60 min to form a shape. After demolding, a green body was obtained. Finally, the green body was placed in a muffle furnace for sintering. During sintering, it was first heated to 800 °C at a rate of 1 °C / min, held for 30 min, and then heated to 1350 °C at a rate of 10 °C / min and sintered for 4 h; Among them, the black pigment consists of Cu 0.1 Ti 0.9 O2, Fe2O3 and CoAl2O4 with a mass ratio of 2:1:1; The sintering aid consists of B2O3, SiO2, MgO, YF3 with a mass ratio of 1:2:5:1; The organic monomer consists of methacrylamide, acrylamide and allyl benzoate with a mass ratio of 1:10:0.5; Cu 0.1 Ti 0.9 The preparation method of O2 is the same as that in Example 1.

[0021] Example 3: A preparation method of an alumina ceramic substrate: 95 g of α-Al2O3, 9 g of sintering aid, 4 g of black pigment, 200 ml of deionized water and 0.5 g of sodium polyacrylate were added to a ball mill jar, and after mixing and ball milling on a planetary ball mill for 10 h, a first slurry was obtained. 23 g of organic monomer and 1 g of N,N-methylenebisacrylamide were added to the first slurry, and after ball milling for another 5 h, a second slurry was obtained. 0.05 g of tetramethylethylenediamine and 0.1 g of free radical initiator were added to the second slurry and stirred for 10 min to make the mixture uniform. After vacuum degassing, it was poured into a mold and cured at 70 °C for 60 min to form a shape. After demolding, a green body was obtained. Finally, the green body was placed in a muffle furnace for sintering. During sintering, it was first heated to 600 °C at a rate of 0.1 °C / min, held for 10 min, and then heated to 1250 °C at a rate of 5 °C / min and sintered for 2 h; Among them, the black pigment consists of Cu 0.1 Ti 0.9 O2, Fe2O3 and CoAl2O4 with a mass ratio of 2:1:1; The sintering aid consists of B2O3, SiO2, MgO, YF3 with a mass ratio of 1:2:5:1; The organic monomer is composed of methacrylamide, acrylamide, and allyl benzoate with a mass ratio of 1:10:0.5; Cu 0.1 Ti 0.9 The preparation method of O2 is the same as that in Example 1.

[0022] Example 4: A method for preparing an alumina ceramic substrate: Add 95 g of α-Al2O3, 9 g of sintering aid, 4 g of black pigment, 200 ml of deionized water, and 0.5 g of sodium polyacrylate into a ball milling tank, mix and ball mill for 10 h on a planetary ball mill to obtain the first slurry. Add 23 g of organic monomer and 1 g of N,N-methylenebisacrylamide to the first slurry, and ball mill for another 5 h to obtain the second slurry. Add 0.05 g of tetramethylethylenediamine and 0.1 g of free radical initiator to the second slurry and stir for 10 min to make it evenly mixed. After vacuum degassing, inject it into a mold and cure at 70 °C for 60 min to form. After demolding, obtain a green body. Finally, put the green body into a muffle furnace for sintering. When sintering, first heat it up to 800 °C at a rate of 0.1 °C / min, keep it warm for 60 min, and then heat it up to 1350 °C at a rate of 10 °C / min and sinter for 2 h; Among them, the black pigment is composed of Cu 0.1 Ti 0.9 O2, Fe2O3, and CoAl2O4 with a mass ratio of 2:1:1; The sintering aid is composed of B2O3, SiO2, MgO, and YF3 with a mass ratio of 1:2:5:1; The organic monomer is composed of methacrylamide, acrylamide, and allyl benzoate with a mass ratio of 1:10:0.5; Cu 0.1 Ti 0.9 The preparation method of O2 is the same as that in Example 1.

[0023] Comparative Example 1: Basically the same as Example 1, the difference is that the black pigment does not include Cu 0.1 Ti 0.9 O2.

[0024] Comparative Example 2: Basically the same as Example 1, the difference is that the black pigment does not include Fe2O3.

[0025] Comparative Example 3: Basically the same as Example 1, the difference is that the black pigment does not include CoAl2O4.

[0026] Comparative Example 4: Basically the same as Example 1, the difference is that the organic monomer does not include allyl benzoate.

[0027] Performance test: The alumina ceramic substrates prepared in Examples 1-4 and Comparative Examples 1-4 of the present invention were used as specimens for performance testing; A colorimeter (CM-3600A, Konica Minolta, Japan) was used to characterize the color values of the specimens. The black electroplated steel cover was used as the reflecting surface for testing. The L * value represents the brightness. The larger the value, the more the color tends to white, and the smaller the value, the more the color tends to black. The a * value represents the red-green value (a * > 0, the color tends to red, a * < 0, the color tends to green), and the b * represents the yellow-blue value (b * > 0, the color tends to yellow, b * < 0, the color tends to blue); According to the national standard GB6569-1986 "Test Method for Flexural Strength of Engineering Ceramics", the three-point bending strength of the ceramic body was tested through a universal testing machine (model HT-2404). The span of the specimen was 20 mm, and the loading speed was 0.5 mm / min; The test results are shown in Table 1 below:

[0028] As can be seen from Table 1 above, the color of the alumina ceramic substrate prepared by the present invention is dark black, and the mechanical strength is relatively excellent; By comparing the data of Example 1 with those of Comparative Examples 1-3, it can be seen that the addition of Cu 0.1 Ti 0.9 O2, Fe2O3 and CoAl2O4 will affect the color and mechanical properties of the prepared alumina ceramic substrate; By comparing the data of Example 1 with those of Comparative Example 4, it can be seen that the addition of allyl benzoate can improve the mechanical properties of the prepared alumina ceramic substrate.

[0029] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing an alumina ceramic substrate, characterized in that: The details are as follows: α-Al2O3, sintering aid, black pigment, deionized water and sodium polyacrylate are mixed and ball-milled to obtain a first slurry, organic monomer and N,N-methylenebisacrylamide are added to the first slurry, and a second slurry is obtained after ball-milling again, tetramethylethylenediamine and a free radical initiator are added to the second slurry and stirred evenly, and then injected into a mold for curing and molding after vacuum degassing, and a green body is obtained after demolding, and finally the green body is placed in a muffle furnace for sintering. The black pigment is Cu x Ti 1- x O2, Fe2O3 and CoAl2O4, where 0<x≤0.

1.

2. The method for preparing an alumina ceramic substrate according to claim 1, characterized in that: The Cu x Ti 1-x The mass ratio of O2, Fe2O3 and CoAl2O4 is 2:1:

1.

3. The method for preparing an alumina ceramic substrate according to claim 1, characterized in that: The mass ratio of the α-Al2O3, sintering aid and black colorant is 90-100:5-10:1-5.

4. The method for preparing an alumina ceramic substrate according to claim 1, characterized in that: The sintering aid is composed of B2O3, SiO2, MgO and YF3 in a mass ratio of 1-2:1-2:3-6:1-2.

5. The method for preparing an alumina ceramic substrate according to claim 1, characterized in that: The organic monomers are composed of methacrylic acid amide, acrylamide and allyl benzoate in a mass ratio of 1-2:5-10:0.1-0.

5.

6. The method for preparing an alumina ceramic substrate according to claim 1, characterized in that: The curing temperature is 60-80℃.

7. The method for preparing an alumina ceramic substrate according to claim 1, characterized in that: The Cu x Ti 1-x The preparation method of O2 is as follows: Tetrabutyl titanate is dissolved in anhydrous ethanol to obtain solution A, copper nitrate is dissolved in deionized water, anhydrous ethanol and concentrated nitric acid are added to obtain solution B, solution A is added dropwise to solution B, mixed after the dropping is completed, heated in a water bath at 70-90°C for 1-5h, then the water bath is removed, and the sol is allowed to stand and age at room temperature for 10-20h to obtain the sol, which is freeze-dried at low temperature and then calcined at 300-400°C for 1-5h.

8. The method for preparing an alumina ceramic substrate according to claim 1, characterized in that: The sintering temperature is 1250-1350°C and the sintering time is 1-5h.

9. The method for preparing an alumina ceramic substrate according to claim 8, characterized in that: During sintering, the temperature is first raised to 600-800°C at a rate of 0.1-1°C / min, kept at that temperature for 10-60 minutes, and then raised to the sintering temperature at a rate of 5-10°C / min.

10. An alumina ceramic substrate, characterized in that: The alumina ceramic substrate is prepared by the preparation method of any one of claims 1 to 9.

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