Ceramic frame for MLCC firing and preparation method and application thereof

Abstract

The invention relates to a ceramic frame for MLCC firing and a preparation method and application thereof, and relates to the technical field of ceramic product processing. The preparation method comprises the following steps: preparing a precursor solution: mixing and stirring an organic monomer, a cross-linking agent and a solvent to form the precursor solution; ceramic powder, a dispersing agent and the precursor solution are mixed, pH is adjusted, ball milling and slurry discharging are conducted, and the slurry is obtained; and preparing the ceramic frame: degassing the slurry, stirring, adding an initiator, stirring, injecting into a mold, preserving heat, gelatinizing the slurry, demolding to obtain a green body, inverting the green body on a plane, drying to obtain a dried green body, and carrying out primary firing to obtain the ceramic frame. According to the preparation method, the ceramic frame prepared through gel casting, drying and one-time sintering has the advantages of high temperature resistance, low deformation and good thermal shock resistance, and is suitable for an MLCC sintering process.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic product processing, and in particular to a ceramic frame for sintering MLCCs, and a preparation method and application thereof. Background Art

[0002] At present, ceramic substrates are widely used in the high-temperature sintering process of high-tech ceramics and other related industries, such as the MLCC (chip multilayer ceramic capacitor) industry. However, ceramic substrates are difficult to make into ultra-thin structures and have the disadvantage of insufficient air permeability when stacked in multiple layers.

[0003] Alumina ceramic materials are widely used in high-temperature sintering processes due to their high hardness, corrosion resistance, wear resistance, and good thermal shock resistance. However, traditional molding processes such as isostatic pressing and slip injection molding are difficult to manufacture some large-sized and complex-shaped ceramic products. The strength of the green body is low, which is not conducive to the subsequent processing of the product. Although the hot die casting process can produce some complex-shaped ceramic products, this molding process is complicated and energy-intensive. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for preparing a ceramic frame for MLCC firing. The ceramic frame prepared by the preparation method through gel injection molding, drying, and one-time firing has the advantages of high temperature resistance, low deformation, and good thermal shock resistance, and is suitable for the MLCC firing process.

[0005] The present invention provides a method for preparing a ceramic frame for MLCC firing, comprising the following steps:

[0006] Preparing a precursor solution: mixing an organic monomer, a cross-linking agent, and a solvent, and stirring to form a precursor solution;

[0007] Prepare slurry: mix ceramic powder, dispersant and precursor solution, adjust pH, ball mill and slurry to obtain slurry;

[0008] Preparation of ceramic frame: degas the slurry, stir, add initiator, stir, inject into mold, keep warm, gel the slurry, demould to obtain green body, invert the green body on a plane, dry to obtain dry green body, perform one firing, and obtain ceramic frame.

[0009] In the above preparation method, the blank is placed upside down on a plane with its supporting feet facing upwards before drying, which can ensure that the loading surface of the blank is supported by the plane and is not affected by gravity. During the slow room temperature drying process, the problem of the center of the bracket being concave and deformed will not occur.

[0010] In one embodiment, the drying is carried out by air drying at room temperature.

[0011] In one embodiment, the drying step includes: using a plurality of heavy objects to press the inverted blank so that the side of the blank used for placing objects is in contact with the plane, and air-drying at room temperature.

[0012] During the drying process, the inverted blank is pressed down by a plurality of small heavy objects so that the side of the blank used for placing objects fits tightly with the plane, further avoiding curling and deformation during the drying process, and at the same time will not affect the drying shrinkage of the blank.

[0013] In one embodiment, the weight comprises a ceramic block.

[0014] In one embodiment, the organic monomer includes acrylamide, the cross-linking agent includes N,N-methylenebisacrylamide, the solvent includes water, the dispersant includes triammonium citrate, and the initiator includes ammonium persulfate.

[0015] In one embodiment, the content of the organic monomer is 8-12wt% of the ceramic powder content, and the content of the cross-linking agent is 5-10wt% of the organic monomer content;

[0016] The content of the dispersant is 1-3wt% of the ceramic powder content, and the solid content of the slurry is 40%-60%;

[0017] The ratio of the organic monomer to the initiator is 5-15%.

[0018] In one embodiment, the ball milling time is 20-26 hours, the insulation temperature is 65-75° C., the insulation time is 1-2 hours, and the pH is adjusted to 3-5;

[0019] The conditions of the primary sintering include: heating to 400-600° C. at 2° C. / min, keeping the temperature for 1 hour, then heating to 1500-1550° C. at 5° C. / min, and keeping the temperature for 1 hour.

[0020] The present invention also provides a ceramic frame for sintering MLCC obtained by the preparation method.

[0021] In one of the embodiments, the ceramic frame for sintering MLCC is square and has a grid. Support feet are provided at two diagonal positions of the square, and grooves matching the support feet are provided at the remaining two diagonal positions.

[0022] The grooves matching the supporting feet allow the ceramic racks to be stacked in multiple layers, so that the sintering efficiency can be improved when the operator uses it.

[0023] In one embodiment, each of the four sides of the square is provided with a notch.

[0024] The ceramic frame will continue to undergo a sintering and cooling process during subsequent use. The above-mentioned notch can reduce the stress caused by its expansion and contraction during use, and reduce the risk of cracking during the continuous sintering and cooling process.

[0025] The present invention also provides application of the ceramic frame for sintering MLCC in preparing MLCC.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention discloses a ceramic frame for MLCC firing, a preparation method and an application thereof. The ceramic frame prepared by the preparation method through gel injection molding, drying and one-time firing has the advantages of high temperature resistance, low deformation and good thermal shock resistance, and is suitable for the MLCC firing process. The green body obtained by gel injection molding contains a high moisture content. The moisture evaporates quickly during the drying process, and the green body is prone to cracking. The drying process of the gelled green body is a complex and slow process. In particular, large-sized green bodies are more likely to produce uneven drying shrinkage, causing structural stress and residual stress concentration, thereby causing problems such as green body deformation and warping. Therefore, the present invention abandons the traditional drying method of heating the gel injection molding green body, and directly allows it to slowly dry at room temperature to prevent warping and deformation during the drying process. At the same time, since the gel injection molding process adds less organic matter, it is suitable for a one-time sintering process, which reduces the manufacturing cost of the final product. After sintering, the ceramic bracket of the present invention has high flatness, high density and high surface finish, and does not require subsequent processing; at the same time, the ceramic frame of the present invention has the characteristics of high temperature resistance, low deformation, good thermal shock resistance and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of the ceramic frame prepared in Example 3;

[0029] Figure 2 This is a schematic diagram of the ceramic frame prepared in Comparative Example 1. DETAILED DESCRIPTION

[0030] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] Unless otherwise specified, the reagents, materials, and equipment used in this example are all commercially available; the experimental methods are all conventional experimental methods in the art unless otherwise specified.

[0033] Example 1

[0034] A high-temperature low-deformation ceramic frame for MLCC firing and a manufacturing method thereof, comprising the following steps:

[0035] Prepare a precursor solution: 8 wt% of organic monomer acrylamide (AM) and cross-linking agent N,N-methylenebisacrylamide (the content of which is 5 wt% of the organic monomer) and pure water are mixed in a certain proportion and stirred to form a precursor solution.

[0036] Prepare slurry: add ceramic raw material powder (ceramic raw material powder composition and content: Al2O3: 98wt%, CaCO3: 0.6wt%, MgO: 0.4wt%, SiO2: 1wt%) and 1wt% of dispersant triammine citrate, adjust the pH value of the mixed solution to 3 with lactic acid, ball mill for 24 hours to obtain a low-viscosity slurry with a solid phase content of 40%.

[0037] Preparation of ceramic frame: After vacuum degassing, add appropriate amount of initiator ammonium persulfate APS under uniform stirring, the ratio of organic monomer to initiator is 5%, and inject the slurry into the mold after rapid stirring;

[0038] Keep the mixture in a thermostat at 70°C for 1 hour and demould it after the slurry is completely gelled;

[0039] Place the formed body with its feet facing upward on a flat surface, press it down with several small ceramic blocks, and let it dry slowly at room temperature to prevent warping during the drying process;

[0040] The dried green body was placed in a sintering furnace for sintering once. The temperature was first raised to 400°C at 2°C / min and kept at that temperature for 1 hour. The temperature was then raised to 1500°C at 5°C / min and kept at that temperature for 1 hour.

[0041] The high-temperature and low-deformation ceramic frame for MLCC firing prepared in this embodiment has a high surface finish and a density of 3.54 g / cm 3 .

[0042] Example 2

[0043] A high-temperature low-deformation ceramic frame for MLCC firing and a manufacturing method thereof, comprising the following steps:

[0044] Preparing a precursor solution: 10 wt% of an organic monomer acrylamide (AM) and a cross-linking agent N,N-methylenebisacrylamide (the content of which is 8 wt% of the organic monomer) and pure water are mixed in a certain proportion and stirred to form a precursor solution.

[0045] Prepare slurry: add ceramic raw material powder (ceramic raw material powder composition and content: Al2O3: 98wt%, CaCO3: 0.6wt%, MgO: 0.4wt%, SiO2: 1wt%) and 2wt% of dispersant triammine citrate, adjust the pH value of the mixed solution to 4 with lactic acid, ball mill for 24 hours to obtain a low-viscosity slurry with a solid phase content of 50%.

[0046] Preparation of ceramic frame: After vacuum degassing, add appropriate amount of initiator ammonium persulfate APS under uniform stirring, the ratio of organic monomer to initiator is 10%, and inject the slurry into the mold after rapid stirring;

[0047] Keep the mixture in a thermostat at 70°C for 1.5 hours and demould after the slurry is completely gelled;

[0048] Place the formed body with its feet facing upward on a flat surface, press it down with several small ceramic blocks, and let it dry slowly at room temperature to prevent warping during the drying process;

[0049] The dried green body was placed in a sintering furnace for sintering once. The temperature was first raised to 500°C at 2°C / min and kept at this temperature for 1 hour. The temperature was then raised to 1530°C at 5°C / min and kept at this temperature for 1 hour.

[0050] The high-temperature and low-deformation ceramic frame for MLCC firing prepared in this embodiment has a high surface finish and a density of 3.85 g / cm 3 .

[0051] Example 3

[0052] A high-temperature low-deformation ceramic frame for MLCC firing and a manufacturing method thereof, comprising the following steps:

[0053] Preparing a precursor solution: mixing 12 wt% of an organic monomer acrylamide (AM), a crosslinking agent N,N-methylenebisacrylamide (the content of which is 10 wt% of the organic monomer), and purified water in a certain proportion, and stirring to form a precursor solution;

[0054] Prepare slurry: add ceramic raw material powder (ceramic raw material powder composition and content: Al2O3: 98wt%, CaCO3: 0.6wt%, MgO: 0.4wt%, SiO2: 1wt%) and 3wt% of dispersant triammine citrate, adjust the pH value of the mixed solution to 5 with lactic acid, ball mill for 24 hours and then slurry to obtain a low-viscosity slurry with a solid content of 60%;

[0055] Preparation of ceramic frame: After vacuum degassing, add appropriate amount of initiator ammonium persulfate APS under uniform stirring, the ratio of organic monomer to initiator is 15%, and inject the slurry into the mold after rapid stirring;

[0056] Keep the mixture in a thermostat at 70°C for 2 hours and demould it after the slurry is completely gelled;

[0057] Place the formed body with its feet facing upward on a flat surface, press it down with several small ceramic blocks, and let it dry slowly at room temperature to prevent warping during the drying process;

[0058] The dried green body was placed in a sintering furnace for sintering once. The temperature was first raised to 600°C at 2°C / min and kept at this temperature for 1 hour. The temperature was then raised to 1550°C at 5°C / min and kept at this temperature for 1 hour.

[0059] The high temperature and low deformation ceramic frame for MLCC firing prepared in this embodiment has a high surface finish. Figure 1 As shown, the density is 3.91g / cm 3 .

[0060] Comparative Example 1

[0061] Compared with Example 3, the preparation method is basically the same, except that after demoulding, the molded embryo is not placed on a flat table with its feet facing upwards, but is directly placed upright on the table to allow it to dry slowly at room temperature.

[0062] The prepared ceramic frame showed obvious bending deformation and fracture, such as Figure 2 shown.

[0063] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a ceramic frame for MLCC firing, characterized in that: The following steps are involved: Preparing a precursor solution: mixing an organic monomer, a cross-linking agent, and a solvent, and stirring to form a precursor solution; Prepare slurry: mix ceramic powder, dispersant and precursor solution, adjust pH, ball mill and slurry to obtain slurry; Preparation of ceramic frame: degas the slurry, stir, add initiator, stir, inject into mold, keep warm, gel the slurry, demould to obtain green body, invert the green body on a plane, dry to obtain dry green body, perform one firing, and obtain ceramic frame.

2. The preparation method according to claim 1, characterized in that: The drying is carried out by air drying at room temperature.

3. The preparation method according to claim 2, characterized in that: The drying step comprises: using a plurality of heavy objects to press the inverted blank so that the surface of the blank used for placing objects is in contact with the plane, and air-drying at room temperature.

4. The preparation method according to claim 3, characterized in that: The weight includes a ceramic block.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The organic monomer includes acrylamide, the cross-linking agent includes N,N-methylenebisacrylamide, the solvent includes water, the dispersant includes triammonium citrate, and the initiator includes ammonium persulfate.

6. The preparation method according to claim 5, characterized in that: The content of the organic monomer is 8-12wt% of the ceramic powder content, and the content of the cross-linking agent is 5-10wt% of the organic monomer content; The content of the dispersant is 1-3wt% of the ceramic powder content, and the solid content of the slurry is 40%-60%; The ratio of the organic monomer to the initiator is 5-15%.

7. The preparation method according to claim 5, characterized in that: The ball milling time is 20-26 hours, the insulation temperature is 65-75° C., the insulation time is 1-2 hours, and the pH is adjusted to 3-5; The conditions of the primary sintering include: heating to 400-600° C. at 2° C. / min, keeping the temperature for 1 hour, then heating to 1500-1550° C. at 5° C. / min, and keeping the temperature for 1 hour.

8. A ceramic frame for sintering MLCC obtained by the preparation method according to any one of claims 1 to 7.

9. The ceramic rack for sintering MLCC according to claim 8, characterized in that: The ceramic frame for sintering the MLCC is square and provided with a grid. Support legs are provided at two diagonal positions of the square, and grooves matching the support legs are provided at the remaining two diagonal positions.

10. Use of the ceramic rack for sintering MLCC according to any one of claims 8 to 9 in preparing MLCC.

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