Heat-resistant multilayer ceramic substrate and preparation method thereof

Abstract

The invention relates to the technical field of ceramic substrates, and provides a heat-resistant multilayer ceramic substrate and a preparation method thereof. The heat-resistant multilayer ceramic substrate comprises the following raw materials in parts by weight: 75-80 parts of aluminum oxide, 1-3 parts of a sintering aid, 82-92 parts of a solvent, 8-14 parts of a binder, 0.5-1.5 parts of a dispersant and 2-6 parts of a flexibilizer. The toughening agent comprises a core-shell structure compound and a calcium-containing compound; the core layer of the core-shell structure compound is titanium dioxide, and the shell layer of the core-shell structure compound is zirconium oxide. According to the technical scheme, the problem that the fracture toughness of the heat-resistant multilayer ceramic substrate is low in the prior art is solved.

Description

Technical Field

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

[0002] As a key basic material in high-end fields such as aerospace, automotive electronics, and high-power semiconductor devices, the performance of heat-resistant multi-layer ceramic substrates directly affects the stability and service life of the entire electronic system.

[0003] At present, heat-resistant multi-layer ceramic substrates generally have the problem of low fracture toughness, which is mainly due to a large number of defects such as micropores and cracks in the microstructure of heat-resistant multi-layer ceramic substrates. These defects are likely to become crack sources under external forces. Under the action of external forces, cracks will rapidly expand, leading to material fracture, reducing the toughness of the material, and making the ceramic substrate extremely prone to crack expansion or even fracture when subjected to thermal stress, mechanical stress, or impact load, seriously reducing the reliability and service life of electronic devices.

[0004] Therefore, there is a need to obtain a heat-resistant multi-layer ceramic substrate with high fracture toughness. Summary of the Invention

[0005] The present invention provides a heat-resistant multi-layer ceramic substrate and a preparation method thereof, which solve the problem of low fracture toughness of heat-resistant multi-layer ceramic substrates in related technologies.

[0006] The technical solution of the present invention is as follows: The present invention provides a heat-resistant multi-layer ceramic substrate, comprising the following raw materials in parts by weight: 75-80 parts of alumina, 1-3 parts of sintering aid, 82-92 parts of solvent, 8-14 parts of binder, 0.5-1.5 parts of dispersant, and 2-6 parts of toughening agent; The toughening agent includes a core-shell structure composite and a calcium-containing compound; The core layer of the core-shell structure composite is titanium dioxide, and the shell layer is zirconia.

[0007] As a further technical solution, the solvent includes water.

[0008] As a further technical solution, the mass ratio of the core-shell structure composite to the calcium-containing compound is 2:3-6.

[0009] In the raw materials of the heat-resistant multi-layer ceramic substrate of the present invention, when the mass ratio of the core-shell structure composite to the calcium-containing compound is 2:3-6, the core-shell structure composite has the functions of inhibiting the formation of intragranular pores and toughening by phase transformation, which promotes the effect of enhancing the grain boundary bonding force of the calcium-containing compound and reaches the best, more effectively preventing the crack from expanding inside the ceramic substrate, and further improving the fracture toughness of the heat-resistant multi-layer ceramic substrate.

[0010] As a further technical solution, the preparation method of the core-shell structure composite includes the following steps: Ultrasonically mix titanium dioxide and water, add a zirconia precursor and continue mixing, add a precipitating agent, keep the temperature at 85-95 °C for 2.5-3.5 h, centrifuge to obtain the solid and dry it, then calcine it to obtain the core-shell structure composite.

[0011] As a further technical solution, the frequency during ultrasonic mixing is 40-60 kHz and the time is 15-20 min; The calcination temperature is 900-950 °C and the time is 3-4 h.

[0012] As a further technical solution, the particle size of the titanium dioxide is 100-150 nm, for example, it can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm.

[0013] As a further technical solution, the precipitating agent includes one of urea and ammonia water; The zirconia precursor includes one or both of zirconium nitrate and zirconium sulfate.

[0014] As a further technical solution, the sintering aid includes one or more of Y2O3, B2O3, and La2O3; the sintering aid can be, for example, Y2O3 and La2O3, can be B2O3 and La2O3, can be Y2O3, B2O3, and La2O3. Preferably, the sintering aid is Y2O3, B2O3, and La2O3, wherein the mass ratio of Y2O3, B2O3, and La2O3 is 1:1:1.

[0015] As a further technical solution, the dispersant includes polyacrylate dispersants.

[0016] In the raw materials of the heat-resistant multi-layer ceramic substrate of the present invention, the dispersant includes polyacrylate dispersants. The carboxylic acid groups on its molecular chain can act through electrostatic repulsion, steric hindrance, etc., so that the inorganic raw material particles of the heat-resistant multi-layer ceramic substrate are more uniformly and stably dispersed in the solvent system. Among them, the polyacrylate dispersants include one or both of sodium polyacrylate and potassium polyacrylate.

[0017] As a further technical solution, the binder includes one or more of polyacrylamide, polyvinyl alcohol, and polyethylene oxide.

[0018] As a further technical solution, the mass ratio of the precipitating agent to the zirconia precursor is 1-1.5:1; The mass ratio of the titanium dioxide, water and zirconium oxide precursor is 3:80:0.5 to 0.8, and for example, it can be 3:80:0.5, 3:80:0.6, 3:80:0.7, 3:80:0.8.

[0019] As a further technical solution, the calcium-containing compound includes one or more of calcium oxide, calcium fluoride, and calcium chloride.

[0020] As a further technical solution, when the calcium-containing compound includes calcium fluoride and calcium oxide, the mass ratio of calcium fluoride to calcium oxide is 1:4 to 7.

[0021] In the raw materials of the heat-resistant multi-layer ceramic substrate of the present invention, when the calcium-containing compound includes calcium fluoride and calcium oxide, the mass ratio of calcium fluoride to calcium oxide can be, for example, 1:4, 1:5, 1:6, 1:7, and preferably 1:4; wherein, when the calcium-containing compound is calcium fluoride and calcium oxide, it can cooperate with the core-shell structure composite to further improve the bending strength of the heat-resistant multi-layer ceramic substrate.

[0022] The present invention also provides a method for preparing a heat-resistant multi-layer ceramic substrate for preparing the heat-resistant multi-layer ceramic substrate, comprising the following steps: S1. Mix alumina, toughening agent, sintering aid, dispersant and solvent to obtain a preliminary mixture; S2. Add a binder to the preliminary mixture for mixing, tape casting, drying to obtain a green ceramic sheet; S3. After punching the green ceramic sheet, perform surface printing, lamination, through-hole conduction, cutting, sintering, and cooling to obtain the heat-resistant multi-layer ceramic substrate.

[0023] The working principle and beneficial effects of the present invention are as follows: In the present invention, the raw materials of the multi-layer ceramic substrate are compounded with a core-shell structure composite having a titanium dioxide core layer and a zirconium oxide shell layer and a calcium-containing compound, significantly improving the fracture toughness of the multi-layer ceramic substrate. In the prior art, metal compounds are generally directly added, but the addition of metal compounds does not necessarily have a positive impact on the performance of the multi-layer ceramic substrate. For example, directly using titanium dioxide as the raw material of the alumina multi-layer ceramic substrate will cause lattice defect problems of intragranular pores, having an adverse effect on the performance of the multi-layer ceramic substrate. In the present invention, a core-shell structure composite having a titanium dioxide core layer and a zirconium oxide shell layer is used. The zirconium oxide shell layer in the core-shell structure composite limits the direct reaction between titanium dioxide and the alumina matrix, inhibiting the problem of a large number of lattice defects caused by the valence change of titanium dioxide, effectively improving the density of the ceramic green body. At the same time, when the core-shell structure composite is added to the multi-layer ceramic substrate, crack propagation can be prevented through transformation toughening when subjected to external forces, enhancing the fracture toughness. The calcium-containing compound helps to enhance the grain boundary bonding force and increase the resistance to crack propagation. Therefore, the core-shell structure composite having a titanium dioxide core layer and a zirconium oxide shell layer and the calcium-containing compound are used in synergy as the raw materials of the multi-layer ceramic substrate, improving the fracture toughness of the heat-resistant multi-layer ceramic substrate by inhibiting the formation of internal pores and enhancing the grain boundary bonding force. Detailed Embodiments

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0025] In the following embodiments and comparative examples, the particle size of alumina is 20 μm, the particle size of calcium oxide is 100 nm, the particle size of calcium fluoride is 10 μm, the particle size of calcium chloride is 10 μm, the weight average molecular weight of polyvinyl alcohol is 10,000, the particle size of Y2O3 is 100 nm, the particle size of La2O3 is 5 μm, and the particle size of B2O3 is 5 μm.

[0026] Example 1 A heat-resistant multi-layer ceramic substrate, comprising the following raw materials in parts by weight: 75 parts of alumina, 1 part of Y2O3, 1 part of La2O3, 85 parts of water, 10 parts of polyvinyl alcohol, 1 part of sodium polyacrylate, and 4 parts of toughening agent; the toughening agent is a core-shell structure composite and calcium oxide; the core layer of the core-shell structure composite is titanium dioxide, and the shell layer is zirconium oxide; the mass ratio of the core-shell structure composite to calcium oxide is 2:4; The preparation method of the core-shell structure composite includes the following steps: Mix titanium dioxide (particle size of 100 nm) and water by ultrasonic wave at 45 kHz for 20 min, add zirconium nitrate and continue mixing for 25 min, add urea, keep warm at 90 °C for 3 h, centrifuge to obtain the solid and dry it, then calcine at 900 °C for 4 h to obtain the core-shell structure composite; wherein, the mass ratio of titanium dioxide, water and zirconium nitrate is 3:80:0.6; the mass ratio of urea and zirconium nitrate is 1:1.

[0027] A preparation method of a heat-resistant multi-layer ceramic substrate includes the following steps: S1. Mix alumina, toughening agent, Y2O3, La2O3, sodium polyacrylate and water to obtain a preliminary mixture; S2. Add polyvinyl alcohol to the preliminary mixture for mixing, cast and form, and dry to obtain a green ceramic sheet; S3. After drilling holes in the green ceramic sheet, perform surface printing, stack 30 layers, conduct electricity up and down, cut, sinter at 1600 °C for 3 h, and cool to obtain the heat-resistant multi-layer ceramic substrate.

[0028] Example 2 A heat-resistant multi-layer ceramic substrate includes the following raw materials in parts by weight: 75 parts of alumina, 0.2 part of B2O3, 0.8 part of La2O3, 82 parts of water, 8 parts of polyvinyl alcohol, 0.5 part of sodium polyacrylate, 2 parts of toughening agent; the toughening agent is a core-shell structure composite and calcium oxide; the core layer of the core-shell structure composite is titanium dioxide, and the shell layer is zirconium oxide; the mass ratio of the core-shell structure composite and calcium oxide is 2:3; The preparation method of the core-shell structure composite includes the following steps: Mix titanium dioxide (particle size of 150 nm) and water by ultrasonic wave at 40 kHz for 15 min, add zirconium nitrate and continue mixing for 20 min, add urea, keep warm at 85 °C for 3.5 h, centrifuge to obtain the solid and dry it, then calcine at 900 °C for 4 h to obtain the core-shell structure composite; wherein, the mass ratio of titanium dioxide, water and zirconium nitrate is 3:80:0.5; the mass ratio of urea and zirconium nitrate is 1.5:1.

[0029] A preparation method of a heat-resistant multi-layer ceramic substrate includes the following steps: S1. Mix alumina, toughening agent, B2O3, La2O3, sodium polyacrylate and water to obtain a preliminary mixture; S2. Add polyvinyl alcohol to the preliminary mixture for mixing, cast and form, and dry to obtain a green ceramic sheet; S3. After drilling holes in the green ceramic sheet, perform surface printing, stack 30 layers, conduct electricity up and down, cut, sinter at 1500 °C for 4 h, and cool to obtain the heat-resistant multi-layer ceramic substrate.

[0030] Example 3 Heat-resistant multi-layer ceramic substrate, comprising the following raw materials in parts by weight: 80 parts of alumina, 1 part of Y2O3, 1 part of B2O3, 1 part of La2O3, 92 parts of water, 14 parts of polyvinyl alcohol, 1.5 parts of sodium polyacrylate, 6 parts of toughening agent; the toughening agent is a core-shell structure composite and calcium oxide; the core layer of the core-shell structure composite is titanium dioxide, and the shell layer is zirconium oxide; the mass ratio of the core-shell structure composite to calcium oxide is 2:2; The preparation method of the core-shell structure composite comprises the following steps: Ultrasonically mix titanium dioxide (particle size 150 nm) and water at 60 kHz for 15 min, add zirconium nitrate and continue to mix for 30 min, add urea and keep warm at 95 °C for 2.5 h, centrifuge to obtain the solid and dry it, and calcine it at 950 °C for 3 h to obtain the core-shell structure composite; wherein, the mass ratio of titanium dioxide, water and zirconium nitrate is 3:80:0.8; the mass ratio of urea to zirconium nitrate is 1.2:1.

[0031] The preparation method of the heat-resistant multi-layer ceramic substrate comprises the following steps: S1. Mix alumina, toughening agent, Y2O3, B2O3, La2O3, sodium polyacrylate and water to obtain a preliminary mixture; S2. Add polyvinyl alcohol to the preliminary mixture for mixing, casting molding, and drying to obtain a green ceramic sheet; S3. After punching the green ceramic sheet, perform surface printing, stack 30 layers, conduct upper and lower connections, cut, sinter at 1650 °C for 3 h, and cool to obtain the heat-resistant multi-layer ceramic substrate.

[0032] Example 4 The difference between this example and Example 3 is only that the mass ratio of the core-shell structure composite to calcium oxide is 2:7.

[0033] Example 5 The difference between this example and Example 3 is only that the mass ratio of the core-shell structure composite to calcium oxide is 2:6.

[0034] Example 6 The difference between this example and Example 3 is only that the mass ratio of the core-shell structure composite to calcium oxide is 2:3.

[0035] Example 7 The difference between this example and Example 6 is only that calcium oxide is replaced with a calcium-containing compound, and the calcium-containing compound is calcium chloride and calcium oxide with a mass ratio of 1:4.

[0036] Example 8 The difference between this example and Example 6 is only that calcium oxide is replaced with a calcium-containing compound, and the calcium-containing compound is calcium fluoride and calcium oxide with a mass ratio of 1:4.

[0037] Example 9 The difference between this embodiment and Embodiment 6 is only that calcium oxide is replaced by a calcium-containing compound, and the calcium-containing compound is calcium fluoride and calcium oxide with a mass ratio of 1:7.

[0038] Comparative Example 1 The difference between this comparative example and Embodiment 3 is only that the toughening agent is calcium oxide.

[0039] Comparative Example 2 The difference between this comparative example and Embodiment 3 is only that the toughening agent is a core-shell structure composite.

[0040] Comparative Example 3 The difference between this comparative example and Embodiment 3 is only that the core-shell structure composite is replaced by titanium dioxide.

[0041] Experimental Example 1 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 heat-resistant multi-layer ceramic substrates prepared in Examples 1 to 6 and Comparative Examples 1 to 3 was tested respectively, and the test results are shown in Table 1.

[0042] Table 1 Performance Test Results

[0043] Compared with Comparative Examples 1 to 3, the heat-resistant multi-layer ceramic substrates prepared in Examples 1 to 6 have higher fracture toughness, indicating that the core-shell structure composite with titanium dioxide as the core layer and zirconium oxide as the shell layer and the calcium-containing compound act synergistically as the raw materials of the multi-layer ceramic substrate, significantly improving the fracture toughness of the heat-resistant multi-layer ceramic substrate.

[0044] Experimental Example 2 According to the test method specified in GB / T 6569-2006 "Test Method for Flexural Strength of Fine Ceramics", the flexural strength of the heat-resistant multi-layer ceramic substrates prepared in Examples 6 to 9 was tested respectively. The test method was three-point bending, and the results are shown in Table 2.

[0045] Table 2 Performance Test Results

[0046] Compared with Examples 6 to 7, the heat-resistant multi-layer ceramic substrates prepared in Examples 8 to 9 have higher flexural strength, indicating that when the calcium-containing compound is calcium fluoride and calcium oxide and acts synergistically with the core-shell structure composite as the raw material of the multi-layer ceramic substrate, the flexural strength of the heat-resistant multi-layer ceramic substrate is improved.

[0047] Experimental Example 3 The average linear expansion coefficient of the heat-resistant multilayer ceramic substrates prepared in Examples 1 to 3 was measured in accordance with the standard GB / T 5594.3-2015 "Test Methods for Properties of Structural Ceramic Materials for Electronic Components - Part 3: Test Method for Average Linear Expansion Coefficient". During the test, the heating rate was 5°C / min and the temperature range was 30°C to 200°C. The results are shown in Table 3.

[0048] Table 3 Performance Test Results

[0049] As can be seen from Table 3, the average linear expansion coefficient of the multilayer ceramic substrates prepared in Examples 1 to 3 of the present invention is in the range of 6.0×10 -6 ·K -1 ~6.5×10 -6 ·K -1 and has excellent heat resistance.

[0050] 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 principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. Heat-resistant multi-layer ceramic substrate, characterized in that, It comprises the following raw materials in parts by weight: 75 - 80 parts of alumina, 1 - 3 parts of sintering aid, 82 - 92 parts of solvent, 8 - 14 parts of binder, 0.5 - 1.5 parts of dispersant, and 2 - 6 parts of toughening agent; The toughening agent comprises a core - shell structure composite and a calcium - containing compound; The core layer of the core - shell structure composite is titanium dioxide, and the shell layer is zirconium oxide.

2. The heat-resistant multi-layer ceramic substrate according to claim 1, wherein The mass ratio of the core - shell structure composite to the calcium - containing compound is 2:3 - 6.

3. The heat-resistant multi-layer ceramic substrate according to claim 1, wherein The preparation method of the core - shell structure composite comprises the following steps: Ultrasonically mix titanium dioxide and water, add a zirconium oxide precursor and continue mixing, add a precipitating agent, keep the temperature at 85 - 95 °C for 2.5 - 3.5 h, centrifuge to obtain the solid, dry it, and calcine it to obtain the core - shell structure composite.

4. The heat-resistant multi-layer ceramic substrate according to claim 3, wherein The frequency during the ultrasonic mixing is 40 - 60 kHz, and the time is 15 - 20 min; The calcination temperature is 900 - 950 °C, and the time is 3 - 4 h.

5. The heat-resistant multi-layer ceramic substrate according to claim 3, wherein, The particle size of the titanium dioxide is 100 - 150 nm.

6. The heat-resistant multi-layer ceramic substrate according to claim 3, characterized in that, The precipitating agent comprises one of urea and ammonia water; The zirconium oxide precursor comprises one or both of zirconium nitrate and zirconium sulfate; The sintering aid comprises one or more of Y2O3, B2O3, and La2O3; The dispersant comprises a polyacrylate - type dispersant; The binder comprises one or more of polyacrylamide, polyvinyl alcohol, and polyethylene oxide.

7. The heat-resistant multi-layer ceramic substrate according to claim 3, wherein The mass ratio of the precipitating agent to the zirconium oxide precursor is 1 - 1.5:1; The mass ratio of the titanium dioxide, water, and zirconium oxide precursor is 3:80:0.5 - 0.

8.

8. The heat-resistant multilayer ceramic substrate according to claim 1, wherein The calcium - containing compound comprises one or more of calcium oxide, calcium fluoride, and calcium chloride.

9. The heat-resistant multi-layer ceramic substrate according to claim 8, wherein, When the calcium - containing compound comprises calcium fluoride and calcium oxide, the mass ratio of calcium fluoride to calcium oxide is 1:4 - 7.

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

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