High-toughness aluminum oxide ceramic substrate and preparation method thereof

Abstract

The invention relates to the technical field of ceramic substrates, and provides a high-toughness aluminum oxide ceramic substrate and a preparation method thereof, the high-toughness aluminum oxide ceramic substrate comprises the following raw materials by weight: 100 parts of aluminum oxide, 1-3 parts of a plasticizer, 4-6 parts of an auxiliary agent, 4-6 parts of a binder, 1-3 parts of a dispersant, and 55-65 parts of water; the auxiliary agent is composed of an auxiliary agent A and an auxiliary agent B, the auxiliary agent A comprises rare earth oxide, and the auxiliary agent B is composed of molybdenum boride, scandium oxide and zirconium oxide. According to the technical scheme, the problem of low toughness of the aluminum oxide ceramic substrate in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic substrates, and in particular to a high-toughness alumina ceramic substrate and a preparation method thereof. Background Art

[0002] Alumina ceramics, due to their excellent insulation, high hardness, high-temperature resistance, and chemical stability, are widely used in numerous fields, including electronics, aerospace, and machinery. While traditional alumina ceramic substrates offer certain performance advantages, they lack toughness and are prone to crack propagation and even rupture when subjected to mechanical and thermal stresses. Substrate failure can be particularly severe in applications with stringent reliability requirements, such as aerospace and automotive electronics. Currently, particle toughening (adding silicon carbide or titanium carbide) is commonly used to improve the toughness of alumina ceramic substrates, but this improvement is limited and can also affect the dielectric properties of the alumina ceramic substrates.

[0003] Therefore, developing a high-toughness alumina ceramic substrate is crucial to meeting the application requirements of modern high-end fields. Summary of the Invention

[0004] The present invention provides a high-toughness alumina ceramic substrate and a preparation method thereof, which solves the problem of low toughness of the alumina ceramic substrate in the related art.

[0005] The technical solutions of the present invention are as follows: The present invention provides a high-toughness alumina ceramic substrate, comprising the following raw materials in parts by weight: 100 parts of alumina, 1 to 3 parts of a plasticizer, 4 to 6 parts of an additive, 4 to 6 parts of a binder, 1 to 3 parts of a dispersant, and 55 to 65 parts of water; the additives include additive A and additive B, the additive A includes a rare earth oxide, and the additive B is composed of molybdenum boride, scandium oxide, and zirconium oxide.

[0006] The addition of a plasticizer to the alumina ceramic substrate of the present invention helps to improve the rheological properties of the slurry during the preparation process, making the molding process smoother and reducing defects, thereby improving the overall performance of the alumina ceramic substrate.

[0007] The addition of a dispersant to the alumina ceramic substrate of the present invention can play the following two roles: 1. It eliminates the interaction between the powders in the raw material of the alumina ceramic substrate, achieving uniform dispersion of the powders. After uniform dispersion, the powders are more densely packed, promoting density, and reducing pores and defects; 2. It improves the fluidity of the slurry during the preparation process of the alumina ceramic substrate, reduces the viscosity of the slurry, and improves the processing performance.

[0008] As a further technical solution, the additive B is composed of molybdenum boride, scandium oxide and zirconium oxide in a mass ratio of 1 to 2:3:8, for example, 1:3:8, 1.5:3:8, 2:3:8, preferably 1.5:3:8.

[0009] The present invention limits the proportions of the various components in additive B in the alumina ceramic substrate. The limited amounts of molybdenum boride and scandium oxide added can more effectively stabilize tetragonal zirconia and enhance its toughening effect. A mass ratio of molybdenum boride, scandium oxide, and zirconium oxide of 1.5:3:8 further enhances the stability of the tetragonal zirconia, improving the toughening effect of the zirconium oxide and, consequently, the toughness of the alumina ceramic substrate.

[0010] As a further technical solution, the rare earth oxide includes one or more of yttrium oxide, lanthanum oxide, and cerium oxide.

[0011] As a further technical solution, the mass ratio of the auxiliary agent A to the auxiliary agent B is 4:1-2, for example, 4:1, 4:1.5, or 4:2.

[0012] As a further technical solution, the plasticizer includes one or more of polyethylene glycol, dioctyl phthalate, and polypropylene alcohol.

[0013] As a further technical solution, the binder includes one or more of polyvinyl alcohol, polyvinyl butyral, and hydroxypropyl methylcellulose.

[0014] As a further technical solution, the dispersant is polyacrylic acid.

[0015] The present invention also proposes a method for preparing a high-toughness alumina ceramic substrate, which is used to prepare the high-toughness alumina ceramic substrate, comprising the following steps: S1. Mixing aluminum oxide, a plasticizer, an additive, a dispersant, and water to obtain a mixture; S2, adding a binder to the mixture to obtain a slurry, and tape-casting the slurry, and drying it to obtain a green porcelain sheet; S3, punching the green ceramic sheet, performing surface printing, laminating, upper and lower conductive bonding, cutting, sintering, and cooling to obtain a high-toughness alumina ceramic substrate.

[0016] As a further technical solution, in step S3, the sintering is first performed by heating the temperature to 1000°C at a heating rate of 10-20°C / min, and then heating the temperature to 1450-1500°C at a heating rate of 5-15°C / min for sintering.

[0017] The alumina ceramic substrate of the present invention limits the sintering heating rate during the preparation process, which can better play the role of the additive, reduce the defects of the alumina ceramic substrate, increase the density, and further improve the bending strength of the alumina ceramic substrate.

[0018] As a further technical solution, the sintering treatment time is 2 to 3 hours.

[0019] As a further technical solution, in step S3, the sintering is firstly heated to 1000°C at a heating rate of 10-20°C / min, and then heated to 1450-1500°C at a heating rate of 10°C / min for sintering.

[0020] As a further technical solution, in step S3, the material used for surface printing is tungsten paste.

[0021] The working principle and beneficial effects of the present invention are: The additives in the alumina ceramic substrate of the present invention consist of additive A (rare earth oxide) and additive B (molybdenum boride, scandium oxide, and zirconium oxide). The rare earth oxide inhibits abnormal grain growth, forms a fine-grained, reinforced structure, promotes the density of the alumina ceramic substrate, and ensures its strength. The addition of additive B improves the toughness of the alumina ceramic substrate. Prior art methods have been used to improve toughness by adding silicon carbide and titanium carbide to alumina ceramic substrates, but the improvement is limited. The addition of additive B in the present invention improves the toughness of the alumina ceramic substrate. The zirconium oxide in additive B primarily achieves toughness through phase transformation, and its toughening effect depends on the content of tetragonal zirconium oxide. However, tetragonal zirconium oxide is unstable. The addition of scandium oxide and molybdenum boride inhibits dislocation movement, inhibits the transformation of the tetragonal zirconium oxide phase to the monoclinic phase, improves the stability of the tetragonal zirconium oxide phase, and thus improves the toughness of the alumina ceramic substrate. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] In the following examples and comparative examples: Alumina: average particle size is 25μm; lanthanum oxide: average particle size is 40nm; molybdenum boride: average particle size is 10μm; yttrium oxide: average particle size is 5nm; zirconium oxide: average particle size is 30nm; scandium oxide: average particle size is 5μm; chromium oxide: average particle size is 50nm; the viscosity of hydroxypropyl methylcellulose is 100,000 mPa·s; the weight average molecular weight of polyacrylic acid is 1800.

[0024] Example 1 A method for preparing a high-toughness alumina ceramic substrate comprises the following steps: S1. Mix 100 parts of aluminum oxide, 3 parts of dioctyl phthalate, 6 parts of an additive, 3 parts of polyacrylic acid, and 65 parts of water to obtain a mixture; S2, adding 6 parts of hydroxypropyl methylcellulose to the mixture to obtain a slurry, and the slurry is tape-casted and dried to obtain a green porcelain sheet; S3, after punching the green ceramic sheet, surface printing (the material used is tungsten paste, the printing thickness is 15μm), lamination (40 layers of green ceramic sheets), upper and lower conductive, cutting, sintering, and cooling to obtain an alumina ceramic substrate; The specific process of sintering in step S3 is: first heating to 1000°C at a heating rate of 10°C / min, then heating to 1500°C at a heating rate of 5°C / min and sintering for 2h; The additives consist of additive A and additive B in a mass ratio of 2:1; Additive A is yttrium oxide; Additive B is composed of molybdenum boride, scandium oxide and zirconium oxide in a mass ratio of 1:3:8.

[0025] Example 2 A method for preparing a high-toughness alumina ceramic substrate comprises the following steps: S1. Mix 100 parts of aluminum oxide, 1 part of dioctyl phthalate, 4 parts of an additive, 1 part of polyacrylic acid, and 55 parts of water to obtain a mixture; S2, adding 4 parts of hydroxypropyl methylcellulose to the mixture to obtain a slurry, and the slurry is tape-casted and dried to obtain a green porcelain sheet; S3, after punching the green ceramic sheet, surface printing (the material used is tungsten paste, the printing thickness is 15μm), lamination (40 layers of green ceramic sheets), upper and lower conductive, cutting, sintering, and cooling to obtain an alumina ceramic substrate; The specific process of sintering in step S3 is: first heating to 1000°C at a heating rate of 20°C / min, then heating to 1450°C at a heating rate of 15°C / min and sintering for 3 hours; The additives consist of additive A and additive B in a mass ratio of 4:1; Additive A is yttrium oxide; Additive B is composed of molybdenum boride, scandium oxide and zirconium oxide in a mass ratio of 1:3:8.

[0026] Example 3 Compared with Example 1, the difference of this embodiment is that the additive B is composed of molybdenum boride, scandium oxide and zirconium oxide in a mass ratio of 2:3:8.

[0027] Example 4 Compared with Example 1, the difference of this embodiment is that the additive B is composed of molybdenum boride, scandium oxide and zirconium oxide in a mass ratio of 1.5:3:8.

[0028] Example 5 Compared with Example 4, the difference of this embodiment is that the additive B is composed of molybdenum boride, scandium oxide and zirconium oxide in a mass ratio of 3:1.5:8.

[0029] Example 6 Compared with Example 4, the difference of this embodiment is that the additive B is composed of molybdenum boride, scandium oxide and zirconium oxide in a mass ratio of 1:1:8.

[0030] Example 7 Compared with Example 4, the difference of this embodiment is that the specific process of sintering in step S3 is: first heating to 1000°C at a heating rate of 10°C / min, then heating to 1500°C at a heating rate of 15°C / min and sintering for 2h.

[0031] Example 8 Compared with Example 4, the difference of this embodiment is that the specific process of sintering in step S3 is: first heating to 1000°C at a heating rate of 10°C / min, and then heating to 1500°C at a heating rate of 10°C / min and sintering for 2h.

[0032] Comparative Example 1 Compared with Example 1, the difference of this comparative example is that the additive B is only zirconium oxide.

[0033] Comparative Example 2 Compared with Example 1, the difference of this comparative example is that the additive B consists of molybdenum boride and zirconium oxide in a mass ratio of 1:8.

[0034] Comparative Example 3 Compared with Example 1, the difference of this comparative example is that the additive B consists of scandium oxide and zirconium oxide in a mass ratio of 3:8.

[0035] Comparative Example 4 Compared with Example 1, the difference of this comparative example is that the additive B consists of molybdenum boride and scandium oxide in a mass ratio of 1:3.

[0036] Comparative Example 5 Compared with Example 1, the difference of this comparative example is that the auxiliary agent B is only molybdenum boride.

[0037] Comparative Example 6 Compared with Example 1, the difference of this comparative example is that the auxiliary agent B is only scandium oxide.

[0038] Comparative Example 7 Compared with Example 1, this comparative example is different in that scandium oxide in additive B is replaced by an equal amount of yttrium oxide.

[0039] Comparative Example 8 Compared with Example 1, the difference of this comparative example is that the scandium oxide in the additive B is replaced by an equal amount of chromium trioxide.

[0040] Comparative Example 9 Compared with Example 1, the difference in this comparative example is that the auxiliary agent B is silicon carbide.

[0041] Experimental example The properties of the alumina ceramic substrates in Examples 1 to 8 and Comparative Examples 1 to 9 were measured using the following method: (1) Fracture toughness: The fracture toughness was determined according to the method in GB / T 23806-2009 “Fine Ceramics Fracture Toughness Test Method Single Edge Precracked Beam (SEPB) Method”; (2) Flexural strength: Test the flexural strength of the specimen according to the test method (three-point bending method) specified in GB / T 6569-2006 “Test method for flexural strength of fine ceramics”; (3) Dielectric constant: The dielectric constant at 10 GHz was measured according to the method in GB / T 12636-1990 "Stripline test method for complex dielectric constant of microwave dielectric substrates"; The measurement results are shown in Tables 1 to 3.

[0042] Table 1 Fracture toughness test results of alumina ceramic substrates in Examples 1 to 6 and Comparative Examples 1 to 9

[0043] As can be seen from Table 1, the fracture toughness of the alumina ceramic substrates in Examples 1 to 6 of the present invention are all higher than those in Comparative Examples 1 to 9, indicating that the alumina ceramic substrates of the present invention have high fracture toughness.

[0044] Table 2 Bending strength test results of alumina ceramic substrates in Examples 4, 7, and 8

[0045] As can be seen from Table 2, by limiting the sintering conditions in the present invention, the effect of the additives in the alumina ceramic substrate can be better exerted, so that the alumina ceramic substrate has higher bending strength.

[0046] Table 3 Dielectric constant measurement results of Example 1 and Comparative Example 9

[0047] As shown in Table 3, the dielectric constant of the alumina ceramic substrate in the present invention is lower than that in Example 9, indicating that the additive B in the alumina ceramic substrate in the present invention, which is composed of molybdenum boride, scandium oxide, and zirconium oxide in a mass ratio of 1:3:8, can enable the alumina ceramic substrate to maintain a lower dielectric constant.

[0048] The above are only 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 should be included in the scope of protection of the present invention.

Claims

1. A high-toughness alumina ceramic substrate, characterized in that: The raw materials include the following components in parts by weight: 100 parts of aluminum oxide, 1 to 3 parts of plasticizer, 4 to 6 parts of additive, 4 to 6 parts of binder, 1 to 3 parts of dispersant, and 55 to 65 parts of water; The auxiliary agent consists of auxiliary agent A and auxiliary agent B. The auxiliary agent A includes rare earth oxide, and the auxiliary agent B consists of molybdenum boride, scandium oxide and zirconium oxide.

2. The high-toughness alumina ceramic substrate according to claim 1, characterized in that: The additive B is composed of molybdenum boride, scandium oxide and zirconium oxide in a mass ratio of 1-2:3:

8.

3. The high-toughness alumina ceramic substrate according to claim 1, characterized in that: The rare earth oxide includes one or more of yttrium oxide, lanthanum oxide, and cerium oxide.

4. The high-toughness alumina ceramic substrate according to claim 1, characterized in that: The mass ratio of the auxiliary agent A to the auxiliary agent B is 4:1-2.

5. The high-toughness alumina ceramic substrate according to claim 1, characterized in that: The binder includes one or more of polyvinyl alcohol, polyvinyl butyral, and hydroxypropyl methylcellulose.

6. The high-toughness alumina ceramic substrate according to claim 1, characterized in that: The dispersant is polyacrylic acid.

7. A method for preparing a high-toughness alumina ceramic substrate, for preparing the high-toughness alumina ceramic substrate according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Mixing aluminum oxide, a plasticizer, an additive, a dispersant, and water to obtain a mixture; S2, adding a binder to the mixture to obtain a slurry, and tape-casting the slurry, and drying it to obtain a green porcelain sheet; S3, punching the green ceramic sheet, performing surface printing, laminating, upper and lower conductive bonding, cutting, sintering, and cooling to obtain a high-toughness alumina ceramic substrate.

8. The method for preparing a high-toughness alumina ceramic substrate according to claim 7, characterized in that: In step S3, the sintering is firstly carried out by heating the temperature to 1000°C at a heating rate of 10-20°C / min, and then heating the temperature to 1450-1500°C at a heating rate of 5-15°C / min for sintering.

9. The method for preparing a high-toughness alumina ceramic substrate according to claim 8, characterized in that: The sintering time is 2 to 3 hours.

10. The method for preparing a high-toughness alumina ceramic substrate according to claim 7, characterized in that: In step S3, the material used for surface printing is tungsten paste.

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