Aluminum oxide multilayer ceramic substrate with high surface smoothness and preparation method thereof

Abstract

The invention relates to the technical field of ceramic substrates, and provides an aluminum oxide multilayer ceramic substrate with high surface smoothness and a preparation method thereof. The aluminum oxide multilayer ceramic substrate with high surface smoothness comprises the following raw materials in parts by weight: 80-90 parts of aluminum oxide, 4-6 parts of a sintering aid, 3-4 parts of a dispersing aid, 6-8 parts of a binder and 75-85 parts of a solvent, the dispersing aid comprises triethyl phosphate, fumed silica and a phenyl phosphate compound. According to the technical scheme, the problem of poor surface smoothness of the aluminum oxide multilayer ceramic substrate in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic substrate, in particular, relates to high surface finish alumina multilayer ceramic substrate and preparation method thereof. BACKGROUND

[0002] Surface finish as one of the core performance indicators of alumina multilayer ceramic substrate, directly determines the quality of subsequent metallization and the accuracy of circuit pattern, however, in the prior art, the problem of poor surface finish is widespread, the root cause mainly concentrates on the interaction of material system.

[0003] The raw materials of alumina ceramic substrate mainly include alumina, sintering aid, organic aid (binder, dispersant) and solvent, wherein the inorganic alumina powder and the organic aid belong to two phases of different properties, the strength of the interaction between the two directly determines the dispersion uniformity of the mixed system and the microstructure stability of the green body, when there is a problem of insufficient interaction between the inorganic alumina powder and the organic aid, it will lead to uneven distribution of the two phases, the phenomenon of powder sedimentation and organic phase floating, ultimately causing the decrease of slurry uniformity, and further causing the uneven density of the subsequent tape casting green body, and the defects such as cracking, delamination and surface depression of the substrate after sintering, which seriously affects the surface finish of the ceramic substrate.

[0004] Therefore, it is necessary to develop an alumina multilayer ceramic substrate with high surface finish. SUMMARY

[0005] The present application provides a high surface finish alumina multilayer ceramic substrate and a preparation method thereof, which solves the problem of poor surface finish of alumina ceramic substrate in the related art.

[0006] The technical scheme of the present application is as follows: the present application provides a high surface finish alumina multilayer ceramic substrate, which comprises the following components by weight: 80-90 parts of alumina, 4-6 parts of sintering aid, 3-4 parts of dispersing aid, 6-8 parts of binder and 75-85 parts of solvent; the dispersing aid comprises triethyl phosphate, fumed silica and phenyl phosphate ester compound.

[0007] As a further technical scheme, the phenyl phosphate ester compound comprises one or both of monophenyl phosphate and diphenyl phosphate, preferably monophenyl phosphate.

[0008] In the alumina multilayer ceramic substrate of the present application, the phenyl phosphate ester compound is preferably monophenyl phosphate, compared with diphenyl phosphate containing two benzene rings, the phenyl content of monophenyl phosphate is moderate, which does not excessively prevent the adsorption of other substances on the surface of alumina due to steric hindrance, further improving the surface finish of the alumina multilayer ceramic substrate.

[0009] As a further technical solution, the mass ratio of the triethyl phosphate, the fumed silica and the phenyl phosphate compound is 2:1:0.8~1.

[0010] As a further technical solution, the fumed silica is composed of a first fumed silica and a second fumed silica, and the carbon content of the first fumed silica and the second fumed silica is different.

[0011] In the alumina multilayer ceramic substrate, the fumed silica is one of the dispersing aids, wherein the fumed silica is composed of a first fumed silica and a second fumed silica with different carbon contents.

[0012] As a further technical solution, the carbon content of the first fumed silica is 0.7wt%~1.3wt%, and the carbon content of the second fumed silica is 2.0wt%~4.0wt%.

[0013] In the alumina multilayer ceramic substrate, the carbon content of the first fumed silica is 0.7wt%~1.3wt%, which belongs to light organic modification, and the retention rate of the silanol on the surface of the fumed silica is high, which retains sufficient hydrophilicity to adapt to the core polar component of the system.

[0014] As a further technical solution, the mass ratio of the first fumed silica and the second fumed silica is 1~2:1.

[0015] In the alumina multilayer ceramic substrate, the mass ratio of the first fumed silica and the second fumed silica is 1~2:1, which is a moderate range, which can ensure the full combination with alumina and polar solvents, avoid inorganic phase agglomeration, meet the demand of uniform dispersion of organic phase, and avoid decomposition defects caused by too high total amount of carbon chain, further improve the strength of the alumina multilayer ceramic substrate.

[0016] As a further technical solution, the sintering aid is composed of magnesium oxide, silicon dioxide and calcium oxide with a mass ratio of 1:2:1~1.2.

[0017] The sintering aid added in the alumina multilayer ceramic substrate can inhibit abnormal growth of crystal grains, promote grain size homogenization, form a dense structure, and improve the mechanical strength of the ceramic substrate.

[0018] As a further technical solution, the binder includes one or both of polyvinyl butyral and polyvinyl alcohol, and preferably polyvinyl butyral.

[0019] The binder added in the alumina multilayer ceramic substrate is preferably polyvinyl butyral, and the binder is a core auxiliary material for connecting powder particles and a forming process. The binder can promote the formation of a green body with complete shape and uniform structure, and ensure the quality of the ceramic substrate.

[0020] As a further technical solution, the solvent includes one or more of isopropyl alcohol, ethyl acetate and anhydrous ethanol.

[0021] As a further technical solution, the solvent is composed of isopropyl alcohol and ethyl acetate with a mass ratio of 7:3.

[0022] The application further provides a preparation method of the high-surface-finish alumina multilayer ceramic substrate. S1, mixing the alumina, sintering aid, dispersant and solvent to obtain a mixture; S2, adding the binder to the mixture, performing flow casting, and drying to obtain a green ceramic sheet; S3, perforating the green ceramic sheet, performing surface printing, lamination, up-down conduction, cutting, sintering and cooling to obtain the high-surface-finish alumina multilayer ceramic substrate.

[0023] The working principle and advantages of the application are as follows: The present application adds dispersing aids triethyl phosphate, fumed silica and phenyl phosphate compounds in the alumina multilayer ceramic substrate, thereby improving the surface smoothness of the alumina multilayer ceramic substrate. In the prior art, due to the insufficient force between the inorganic alumina powder and the organic additive, the powder will settle and the organic phase will float, thereby causing the surface smoothness of the ceramic substrate to decrease. In the present application, triethyl phosphate, fumed silica and phenyl phosphate compounds are added as dispersing aids. The triethyl phosphate can be adsorbed on the surface of the alumina through the ester group, and the hydrophobic ethyl end can prevent the agglomeration of the alumina. The fumed silica contains silicon hydroxyl groups on its surface, which can interact with each other in the slurry to effectively prevent the settling of the alumina. The addition of the phenyl phosphate compound can introduce a benzene ring to the surface of the alumina powder, and the addition of the benzene ring can prevent the agglomeration of the alumina by utilizing its own steric hindrance. Through the synergistic effect of triethyl phosphate, fumed silica and phenyl phosphate compounds, the agglomeration of the alumina is effectively prevented, the settling problem of the alumina is alleviated, and a uniformly dispersed slurry is formed. After the slurry is flow-casted, the alumina particles are uniformly distributed in the green body without local aggregation or porosity, thereby improving the surface smoothness of the alumina ceramic substrate. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0025] In the following examples and comparative examples: Alumina: purity 99.6%, average particle size 0.4 μm; First fumed silica: model HB-612; Second fumed silica: model HB-132; Magnesium oxide: average particle size 100 nm; Calcium oxide: average particle size 20 nm; Silicon dioxide: average particle size 20 nm; Polyvinyl butyral: model BL-1.

[0026] Example 1 The preparation method of the high-surface-smoothness alumina multilayer ceramic substrate comprises the following steps: S1, mixing 80 parts of alumina, 4 parts of sintering aid, 3 parts of dispersing aid and 75 parts of solvent to obtain a mixture; S2, adding 6 parts of polyvinyl butyral to the mixture, flow-casting, drying to obtain a green ceramic sheet; S3, after the green ceramic sheet is punched, surface printing, layering (30 layers), up and down conduction, cutting, sintering at 1200 DEG C for 2.5h, cooling, to obtain the high surface finish alumina multilayer ceramic substrate; The sintering aid is composed of magnesium oxide, silicon dioxide and calcium oxide with a mass ratio of 1:2:1; The dispersing aid is composed of triethyl phosphate, fumed silica and monophenyl phosphate with a mass ratio of 2:1:0.8, and the fumed silica is the first fumed silica; The solvent is composed of isopropyl alcohol and ethyl acetate with a mass ratio of 7:3.

[0027] Example 2 The preparation method of the high surface finish alumina multilayer ceramic substrate comprises the following steps: S1, mixing 85 parts of alumina, 5 parts of sintering aid, 3.5 parts of dispersing aid and 80 parts of solvent to obtain a mixture; S2, adding 7 parts of polyvinyl butyral into the mixture, casting forming, drying to obtain a green ceramic sheet; S3, after the green ceramic sheet is punched, surface printing, layering (30 layers), up and down conduction, cutting, sintering at 1200 DEG C for 2.5h, cooling, to obtain the high surface finish alumina multilayer ceramic substrate; The sintering aid is composed of magnesium oxide, silicon dioxide and calcium oxide with a mass ratio of 1:2:1; The dispersing aid is composed of triethyl phosphate, fumed silica and monophenyl phosphate with a mass ratio of 2:1:0.8, and the fumed silica is the first fumed silica; The solvent is composed of isopropyl alcohol and ethyl acetate with a mass ratio of 7:3.

[0028] Example 3 The preparation method of the high surface finish alumina multilayer ceramic substrate comprises the following steps: S1, mixing 90 parts of alumina, 6 parts of sintering aid, 4 parts of dispersing aid and 85 parts of solvent to obtain a mixture; S2, adding 8 parts of polyvinyl butyral into the mixture, casting forming, drying to obtain a green ceramic sheet; S3, after the green ceramic sheet is punched, surface printing, layering (30 layers), up and down conduction, cutting, sintering at 1200 DEG C for 2.5h, cooling, to obtain the high surface finish alumina multilayer ceramic substrate; The sintering aid is composed of magnesium oxide, silicon dioxide and calcium oxide with a mass ratio of 1:2:1; The dispersing aid is composed of triethyl phosphate, fumed silica and monophenyl phosphate with a mass ratio of 2:1:0.8, and the fumed silica is the first fumed silica; The solvent consists of isopropyl alcohol and ethyl acetate in a mass ratio of 7:3.

[0029] Example 4 Example 4 differs from Example 2 in that the dispersion aid consists of triethyl phosphate, fumed silica, and monophenyl phosphate in a mass ratio of 2:1:1.

[0030] Example 5 Example 5 differs from Example 4 in that monophenyl phosphate is replaced by an equivalent amount of diphenyl phosphate.

[0031] Example 6 Example 6 differs from Example 4 in that the fumed silica is a second fumed silica.

[0032] Example 7 Example 7 differs from Example 4 in that the fumed silica consists of a first fumed silica and a second fumed silica in a mass ratio of 1:1.

[0033] Example 8 Example 8 differs from Example 4 in that the fumed silica consists of a first fumed silica and a second fumed silica in a mass ratio of 2:1.

[0034] Comparative Example 1 Comparative Example 1 differs from Example 2 in that the dispersion aid consists of triethyl phosphate and fumed silica in a mass ratio of 2:1.

[0035] Comparative Example 2 Comparative Example 2 differs from Example 2 in that the dispersion aid consists of triethyl phosphate and monophenyl phosphate in a mass ratio of 2:0.8.

[0036] Comparative Example 3 Comparative Example 3 differs from Example 2 in that the dispersion aid consists of fumed silica and monophenyl phosphate in a mass ratio of 1:0.8.

[0037] Comparative Example 4 Comparative Example 4 differs from Example 2 in that the dispersion aid is only triethyl phosphate.

[0038] Comparative Example 5 Comparative Example 5 differs from Example 2 in that monophenyl phosphate is replaced by an equivalent amount of monododecyl phosphate.

[0039] Experimental Example 1 The surface roughness of the alumina multilayer ceramic substrate prepared in Examples 1-5 and Comparative Examples 1-5 was tested using a surface roughness tester.

[0040] The test results are shown in Table 1: Table 1 Test results of the properties of the alumina multilayer ceramic substrate prepared in Examples 1-5 and Comparative Examples 1-5

[0041] As shown in Table 1, when triethyl phosphate, fumed silica and phenyl phosphate compound are added as dispersing aids, the surface smoothness of the alumina multilayer ceramic substrate can be improved.

[0042] Experimental Example 2 The bending strength of the alumina multilayer ceramic substrate prepared in Example 4 and Examples 6-8 was tested according to the test method specified in GB / T 6569-2006 "Fine Ceramic Bending Strength Test Method", and the test method used was three-point bending.

[0043] The test results are shown in Table 2: Table 2 Test results of the properties of the alumina multilayer ceramic substrate prepared in Example 4 and Examples 6-8

[0044] As shown in Table 2, when the fumed silica is composed of first fumed silica and second fumed silica with different carbon contents, the strength of the alumina multilayer ceramic substrate can be further improved.

[0045] The above is only the preferred embodiment of the present application, and is not intended to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A high-surface-smoothness alumina multilayer ceramic substrate, characterized in that, The raw materials include the following components in parts by weight: 80-90 parts alumina, 4-6 parts sintering aid, 3-4 parts dispersing aid, 6-8 parts binder, and 75-85 parts solvent; the dispersing aid includes triethyl phosphate, fumed silica, and phenyl phosphate compounds.

2. The high surface finish alumina multilayer ceramic substrate according to claim 1, characterized in that, The phenyl phosphate compound includes one or both of monophenyl phosphate and diphenyl phosphate.

3. The high surface finish alumina multilayer ceramic substrate according to claim 1, characterized in that, The mass ratio of the triethyl phosphate, fumed silica, and phenyl phosphate compound is 2:1:0.8~1.

4. The high surface finish alumina multilayer ceramic substrate according to claim 1, characterized in that, The fumed silica is composed of a first fumed silica and a second fumed silica, and the first fumed silica and the second fumed silica have different carbon contents.

5. The high surface finish alumina multilayer ceramic substrate according to claim 4, characterized in that, The carbon content of the first fumed silica is 0.7wt%~1.3wt%, and the carbon content of the second fumed silica is 2.0wt%~4.0wt%.

6. The high surface finish alumina multilayer ceramic substrate according to claim 4, characterized in that, The mass ratio of the first fumed silica to the second fumed silica is 1~2:

1.

7. The high surface finish alumina multilayer ceramic substrate according to claim 1, characterized in that, The sintering aid is composed of magnesium oxide, silicon dioxide and calcium oxide in a mass ratio of 1:2:1 to 1.

2.

8. The high surface finish alumina multilayer ceramic substrate according to claim 1, characterized in that, The adhesive includes one or both of polyvinyl butyral and polyvinyl alcohol.

9. The high surface finish alumina multilayer ceramic substrate according to claim 1, characterized in that, The solvent includes one or more of isopropanol, ethyl acetate, and anhydrous ethanol.

10. A method for preparing a high surface finish alumina multilayer ceramic substrate, used to prepare the high surface finish alumina multilayer ceramic substrate according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Mix the alumina, sintering aid, dispersant and solvent to obtain a mixture; S2. Add the binder to the mixture, cast it into a film, and dry it to obtain a raw ceramic tile; S3. After drilling holes in the raw ceramic sheet, the substrate is then subjected to surface printing, lamination, top and bottom conduction, cutting, sintering, and cooling to obtain the high surface finish alumina multilayer ceramic substrate.

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