Brazing assembly and preparation method and application thereof

Abstract

The invention relates to a brazing assembly and a preparation method and application thereof.The preparation method comprises the following steps that after the surface of a ceramic green body is coated with intermediate layer slurry, drying and sintering are conducted in sequence, and a treated ceramic material is obtained; the treated ceramic material and kovar alloy are subjected to vacuum brazing, and the brazing assembly is obtained; solder for vacuum brazing is silver-copper solder, and the brazing assembly comprises a ceramic green body, a middle layer and kovar alloy which are sequentially arranged in a stacked mode. According to the method, the middle layer and the ceramic green body are sintered together, so that the adhesive strength of the middle layer can be improved, the wettability of the ceramic green body and the kovar alloy can be improved, and the welding strength of the brazing assembly is improved. In addition, in the welding flux, no titanium element is added, only silver-copper welding flux is adopted, and the wettability of the ceramic green body and the kovar alloy and the welding strength of a brazing assembly can be further improved.

Description

Technical Field

[0001] The present invention relates to the field of brazing technology, and relates to a brazing assembly, and particularly relates to a brazing assembly, a preparation method thereof and an application thereof. Background Art

[0002] In the field of semiconductor manufacturing equipment, an electrostatic chuck is a common device used to fix and support semiconductor wafers during the manufacturing process. By applying a high-voltage electric field, the working surface of the electrostatic chuck is positively charged, while the workpiece is negatively charged, thereby generating an electrostatic attraction force to tightly attach the workpiece to the working surface. This technology can achieve flat and uniform clamping of ultra-thin wafer sheets without damaging the wafer surface.

[0003] Ceramic materials have excellent properties such as high hardness, high melting point, high temperature resistance, and corrosion resistance, and are widely used in the fields of electronics, machinery, aerospace, etc. The electrostatic adsorption part of the electrostatic chuck is usually also made of ceramic materials, such as alumina ceramics, aluminum nitride ceramics, or silicon carbide ceramics, etc. In order to achieve the effect of electrostatic adsorption, a metal electrostatic adsorption layer is also designed inside the ceramic to communicate with an external power supply. However, the brittleness and difficult machinability of ceramic materials limit their application scope.

[0004] Kovar alloy, an iron-nickel-cobalt alloy, also known as a constant expansion alloy or a sealing alloy, is an alloy with a relatively constant low or medium expansion coefficient in the temperature range of -70°C to 500°C. Due to its good mechanical properties and machinability, it is often used for welding with ceramic materials to enhance the mechanical properties and machinability of ceramic materials.

[0005] In previous studies on the welding of ceramics and metals, there have been more studies on the welding of alumina or aluminum nitride ceramics and Kovar alloy. The main reason is that their thermal expansion coefficients are similar, and the residual stress during welding is small. When welding alumina ceramics or aluminum nitride ceramics and Kovar alloy, silver-copper-titanium filler metal or silver-copper filler metal is generally used. When using silver-copper-titanium filler metal, due to the presence of active titanium element, it has good wetting performance with ceramics. However, during the brazing process, the titanium element in the filler metal will diffuse towards the Kovar alloy side, and at the same time, the titanium element reacts with Fe and Ni in the Kovar alloy to generate brittle compounds such as Fe 2 Ni and Ni 3 Ti, which reduces the wetting performance of the silver-copper-titanium filler metal with ceramics; while when using silver-copper filler metal, the copper in the filler metal will preferentially spread along the grain boundaries of the Kovar alloy, and it is easy to form island-shaped copper-based solid solution regions before spreading, which will lead to a reduction in the welding strength of brazing.

[0006] CN115555669A discloses a method for brazing aluminum nitride ceramics and kovar alloy. The steps include: S1, pre-treating the aluminum nitride ceramics and the kovar alloy; S2, preparing a Ti layer with a thickness of 5 μm - 10 μm on the surface to be brazed of the aluminum nitride ceramics; S3, preparing a Ni layer with a thickness of 20 μm - 30 μm on the Ti layer on the surface to be brazed of the aluminum nitride ceramics; S4, preparing a Ni layer with a thickness of 20 μm - 30 μm on the surface to be brazed of the kovar alloy; S5, performing vacuum brazing on the aluminum nitride ceramics and the kovar alloy, and adding AgCu28 powder filler metal at the brazing gap. In the brazing process of the present invention, the addition of titanium element will reduce the wetting performance between the ceramic material and the kovar alloy, and further reduce the welding strength of the brazed assembly.

[0007] In the prior art, there are defects such as poor wettability between ceramic materials and kovar alloy or low welding strength. Therefore, how to improve the wettability and welding strength between ceramic materials and kovar alloy has become an urgent problem to be solved at present. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a brazed assembly, its preparation method and application. By co-sintering the intermediate layer and the ceramic green body, not only can the adhesion strength of the intermediate layer be improved, but also the wettability between the ceramic green body and the kovar alloy can be improved, thereby improving the welding strength of the brazed assembly. In addition, in the filler metal of the present invention, no titanium element is added, and only silver-copper filler metal is used, which can further improve the wettability between the ceramic green body and the kovar alloy and the welding strength of the brazed assembly.

[0009] To achieve this purpose, the present invention adopts the following technical solutions:

[0010] In the first aspect, the present invention provides a preparation method of a brazed assembly. The preparation method includes the following steps: after coating the intermediate layer slurry on the surface of the ceramic green body material, drying and sintering are carried out in sequence to obtain the treated ceramic material; the treated ceramic material and the kovar alloy are subjected to vacuum brazing to obtain the brazed assembly; the filler metal for the vacuum brazing is silver-copper filler metal; the brazed assembly includes a ceramic material, an intermediate layer and a kovar alloy which are stacked in sequence.

[0011] By co-sintering the intermediate layer and the ceramic green body, the present invention can not only improve the adhesion strength of the intermediate layer, but also improve the wettability between the ceramic green body and the kovar alloy, thereby improving the welding strength of the brazed assembly. In addition, in the filler metal of the present invention, no titanium element is added, and only silver-copper filler metal is used, which can further improve the wettability between the ceramic green body and the kovar alloy and the welding strength of the brazed assembly.

[0012] Preferably, the green ceramic material includes any one or a combination of at least two of alumina ceramics, aluminum nitride ceramics, or silicon carbide ceramics. Typical but non-limiting combinations include a combination of alumina ceramics and aluminum nitride ceramics, or a combination of alumina ceramics, aluminum nitride ceramics, and silicon carbide ceramics.

[0013] Preferably, the previous process of the green ceramic material includes any one or a combination of at least two of cold isostatic pressing process, tape casting process, or hot isostatic pressing process. Typical but non-limiting combinations include a combination of cold isostatic pressing process and tape casting process, or a combination of cold isostatic pressing process, tape casting process, and hot isostatic pressing process.

[0014] Preferably, the intermediate layer slurry includes any one or a combination of at least two of molybdenum-manganese slurry, tungsten-copper slurry, tungsten slurry, or nickel slurry. Typical but non-limiting combinations include a combination of molybdenum-manganese slurry and tungsten-copper slurry, or a combination of tungsten-copper slurry, tungsten slurry, and nickel slurry.

[0015] Preferably, the coating method includes spraying and / or printing.

[0016] Preferably, the thickness of the coating is 15μm - 30μm. For example, it can be 15μm, 18μm, 20μm, 25μm, 28μm, or 30μm, but is not limited to the listed values. Other unlisted values within the numerical range are equally applicable.

[0017] By further regulating the coating thickness of the intermediate layer, the present invention can improve the wettability between the green ceramic and the kovar alloy, and further improve the welding strength of the brazed assembly. Within the preferred range of coating thickness, during the drying and sintering processes of the intermediate layer, the shrinkage is uniform and does not cause abnormalities such as peeling or cracking of the intermediate layer. At the same time, it can further improve the wettability between the green ceramic and the kovar alloy, thereby further improving the welding strength of the brazed assembly.

[0018] Preferably, the coating method includes spraying and / or printing.

[0019] Among them, the spraying process includes: through a spray gun or a disc atomizer, with the aid of pressure or centrifugal force, dispersing the raw material into uniform and fine droplets, and applying them to the surface of the object to be coated.

[0020] The printing process includes: passing the printing material through the pattern area by a squeegee and printing it on the surface of the substrate to form a coating.

[0021] At the same time, those skilled in the art can select the coating method according to the previous process of the green ceramic material. For example, when the previous process of the green ceramic material is the cold isostatic pressing process, the coating method can be spraying; when the previous process of the green ceramic material is the tape casting process, the coating method can be printing.

[0022] Preferably, before the coating, cleaning and masking are also carried out in sequence.

[0023] Preferably, the cleaning method includes cleaning the welding surface with a dust removal device.

[0024] Preferably, the masking method includes preparing a template according to the shape to mask the area that does not need to be welded.

[0025] The template described in the present invention is a conventional device, and those skilled in the art can select the material and size of the template within a reasonable range.

[0026] Preferably, the heat preservation temperature for drying is 80°C - 100°C. For example, it can be 80°C, 85°C, 90°C, 95°C or 100°C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0027] Preferably, the heat preservation time for drying is 10 min - 30 min. For example, it can be 10 min, 15 min, 20 min, 25 min or 30 min, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0028] Preferably, the heat preservation temperature for sintering is 1600°C - 1800°C. For example, it can be 1600°C, 1650°C, 1700°C, 1750°C or 1800°C, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0029] The present invention further improves the structural stability, thermal stability and dimensional stability of the brazed assembly by further regulating the heat preservation temperature of sintering, and further improves the welding strength of the brazed assembly. Within the preferred heat preservation temperature range of sintering, the prepared brazed assembly has uniform grain size, uniform phase composition and no impurity phase, high density, excellent thermal stability, no deformation or microcracks, thereby further improving the welding strength of the brazed assembly.

[0030] Preferably, the heat preservation time for sintering is 2 h - 5 h. For example, it can be 2 h, 3 h, 4 h, 4.5 h or 5 h, but is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0031] Preferably, the ambient atmosphere for sintering includes an inert gas atmosphere.

[0032] Preferably, the ambient atmosphere for sintering also includes a reducing gas atmosphere.

[0033] Preferably, the inert gas atmosphere includes a nitrogen atmosphere and / or an argon atmosphere.

[0034] Preferably, the reducing gas atmosphere includes a hydrogen atmosphere.

[0035] Preferably, before the vacuum brazing, the treated ceramic material and the kovar alloy are respectively cleaned.

[0036] Preferably, the cleaning detergent includes deionized water.

[0037] Preferably, the number of cleaning times is 3 to 5 times, for example, it can be 3 times, 4 times or 5 times.

[0038] Preferably, the welding temperature of the vacuum brazing is 800°C - 850°C, for example, it can be 800°C, 810°C, 820°C, 830°C, 840°C or 850°C, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0039] By further regulating the welding temperature of the vacuum brazing, the present invention can further regulate the fluidity of the filler metal, thereby further improving the welding strength of the brazed assembly. Within the preferred welding temperature range, the fluidity and wettability of the filler metal are excellent, the pores of the filler metal are few, the welding quality is improved, and problems such as loss or erosion of the filler metal will not occur, thereby further improving the welding strength of the brazed assembly.

[0040] Preferably, the welding time of the vacuum brazing is 5 min - 15 min, for example, it can be 5 min, 8 min, 10 min, 13 min or 15 min, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0041] By further increasing the welding time of the vacuum brazing, the present invention can further improve the welding strength of the brazed assembly. Within the preferred welding time range, the fluidity and wettability of the filler metal are excellent, and the welded metal will not be eroded, thereby further improving the welding strength of the brazed assembly.

[0042] Preferably, in the silver-copper filler metal, the mass ratio of copper to silver is (5 - 7):(3 - 5), for example, it can be 5:3, 5:5, 6:3, 6:4, 7:3, 7:4 or 7:5, but it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0043] This application selects a silver-copper filler metal. On the one hand, silver has good wettability, is easy to spread, and has high fluidity; on the other hand, copper can improve the welding strength. By regulating the mass ratio of copper to silver in the silver-copper filler metal, the present application can further improve the strength, toughness and fatigue resistance of the solder joints. Within the preferred range of the copper-silver mass ratio, the brazed assembly prepared has high strength, high toughness and excellent fatigue resistance.

[0044] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0045] (1) After coating an intermediate layer of 15 μm - 30 μm on the surface of the green ceramic blank, drying and sintering are carried out in sequence to obtain the treated ceramic material; the holding temperature for drying is 80°C - 100°C, the holding time is 10 min - 30 min, the holding temperature for sintering is 1600°C - 1800°C, the holding time is 2 h - 5 h, the ambient atmosphere includes an inert gas atmosphere, and the ambient atmosphere also includes a reducing gas atmosphere.

[0046] (2) Clean the treated ceramic material and the kovar alloy, coat a paste silver-copper solder on the welding surface and assemble the kovar alloy to the corresponding position, and perform vacuum brazing on the assembled assembly to obtain the brazed assembly; the welding temperature for the vacuum brazing is 800°C - 850°C, the welding time is 5 min - 15 min, and in the silver-copper solder, the mass ratio of copper to silver is (5 - 7):(3 - 5).

[0047] In a second aspect, the present invention provides a brazed assembly, which is prepared by using the preparation method described in the first aspect.

[0048] In a third aspect, the present invention provides an application of the brazed assembly described in the second aspect, and the brazed assembly is applied to the preparation of an electrostatic chuck.

[0049] Compared with the prior art, the present invention has at least the following beneficial effects:

[0050] (1) By sintering the intermediate layer and the green ceramic blank together, the present invention can not only improve the adhesion strength of the intermediate layer, but also improve the wettability between the green ceramic blank and the kovar alloy, thereby improving the welding strength of the brazed assembly.

[0051] (2) In the solder of the present invention, no titanium element is added, and only a silver-copper solder is used, which can further improve the wettability between the green ceramic blank and the kovar alloy and the welding strength of the brazed assembly. Specific Embodiments

[0052] To facilitate the understanding of the present invention, the following examples are listed. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0053] Example 1

[0054] This example provides a preparation method for a brazed assembly, and the preparation method includes the following steps:

[0055] (1) After coating the surface of the green alumina ceramic blank with 20 μm of the intermediate layer tungsten paste, drying and sintering are carried out in sequence to obtain the treated alumina ceramic material; the holding temperature for drying is 90 °C and the holding time is 20 min, the holding temperature for sintering is 1600 °C and the holding time is 3 h, and the ambient atmosphere is a mixed atmosphere of nitrogen and hydrogen;

[0056] (2) The treated alumina ceramic material and kovar alloy are respectively cleaned 4 times with deionized water, a paste-like silver-copper solder is coated on the welding surface and the kovar alloy is assembled to the corresponding position, and the assembled assembly is subjected to vacuum brazing to obtain the brazed assembly; the welding temperature for the vacuum brazing is 830 °C and the welding time is 10 min. In the silver-copper solder, the mass ratio of copper to silver is 7:3.

[0057] Example 2

[0058] This embodiment provides a method for preparing a brazed assembly, and the preparation method includes the following steps:

[0059] (1) After coating the surface of the green aluminum nitride ceramic blank with 15 μm of the intermediate layer molybdenum-manganese paste, drying and sintering are carried out in sequence to obtain the treated aluminum nitride ceramic material; the holding temperature for drying is 80 °C and the holding time is 30 min, the holding temperature for sintering is 1700 °C and the holding time is 5 h, and the ambient atmosphere is a nitrogen atmosphere;

[0060] (2) The treated aluminum nitride ceramic material and kovar alloy are respectively cleaned 5 times with deionized water, a paste-like silver-copper solder is coated on the welding surface and the kovar alloy is assembled to the corresponding position, and the assembled assembly is subjected to vacuum brazing to obtain the brazed assembly; the welding temperature for the vacuum brazing is 800 °C and the welding time is 15 min. In the silver-copper solder, the mass ratio of copper to silver is 6:4.

[0061] Example 3

[0062] This embodiment provides a method for preparing a brazed assembly, and the preparation method includes the following steps:

[0063] (1) After coating the surface of the green silicon carbide ceramic blank with 30 μm of the intermediate layer nickel paste, drying and sintering are carried out in sequence to obtain the treated silicon carbide ceramic material; the holding temperature for drying is 100 °C and the holding time is 10 min, the holding temperature for sintering is 1800 °C and the holding time is 2 h, and the ambient atmosphere is an argon atmosphere;

[0064] (2) Wash the treated aluminum nitride ceramic material and kovar alloy with deionized water three times respectively. Coat the soldering surface with paste silver-copper solder and assemble the kovar alloy to the corresponding position. Then, perform vacuum brazing on the assembled assembly to obtain the brazed assembly; the welding temperature of the vacuum brazing is 850 °C, and the welding time is 5 min. In the silver-copper solder, the mass ratio of copper to silver is 5:5.

[0065] Example 4

[0066] The difference between this example and Example 1 is only that, except that the coating thickness of the intermediate tungsten paste in step (1) is 10 μm, the rest are the same as those in Example 1.

[0067] Example 5

[0068] The difference between this example and Example 1 is only that, except that the coating thickness of the intermediate tungsten paste in step (1) is 35 μm, the rest are the same as those in Example 1.

[0069] Example 6

[0070] The difference between this example and Example 1 is only that, except that the holding temperature of the sintering in step (1) is 1500 °C, the rest are the same as those in Example 1.

[0071] Example 7

[0072] The difference between this example and Example 1 is only that, except that the holding temperature of the sintering in step (1) is 1900 °C, the rest are the same as those in Example 1.

[0073] Example 8

[0074] The difference between this example and Example 1 is only that, except that the welding temperature of the vacuum brazing in step (2) is 750 °C, the rest are the same as those in Example 1.

[0075] Example 9

[0076] The difference between this example and Example 1 is only that, except that the welding temperature of the vacuum brazing in step (2) is 900 °C, the rest are the same as those in Example 1.

[0077] Example 10

[0078] The difference between this example and Example 1 is only that, except that in the silver-copper solder in step (2), the mass ratio of copper to silver is 8:2, the rest are the same as those in Example 1.

[0079] Example 11

[0080] The difference between this example and Example 1 is only that, except that in the silver-copper solder in step (2), the mass ratio of copper to silver is 2:8, the rest are the same as those in Example 1.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is only that, except that the intermediate layer tungsten paste is not coated in step (1), the rest are the same as those in Example 1.

[0083] Comparative Example 2

[0084] This comparative example provides a method for preparing a brazed assembly, and the preparation method includes the following steps:

[0085] (1) After the green alumina ceramic blank is dried and sintered in sequence, 20 μm of intermediate layer tungsten paste is coated to obtain the treated alumina ceramic material; the heat preservation temperature for drying is 90 °C, the heat preservation time is 20 min, the heat preservation temperature for sintering is 1600 °C, the heat preservation time is 3 h, and the ambient atmosphere is a mixed atmosphere of nitrogen and hydrogen;

[0086] (2) The treated alumina ceramic material and kovar alloy are respectively cleaned 4 times with deionized water, a paste-like silver-copper solder is coated on the welding surface, the kovar alloy is assembled to the corresponding position, and the assembled assembly is vacuum brazed to obtain the brazed assembly; the welding temperature for the vacuum brazing is 830 °C, the welding time is 10 min, and in the silver-copper solder, the mass ratio of copper to silver is 7:3.

[0087] Comparative Example 3

[0088] The difference between this comparative example and Example 1 is only that, except that a paste-like silver-copper-titanium solder is coated on the welding surface in step (2), the rest are the same as those in Example 1.

[0089] Testing Method

[0090] The brazed assemblies prepared in Examples 1 - 11 and Comparative Examples 1 - 3 are tested for welding strength and porosity. Among them, a universal tensile testing machine is used to test the welding strength, and the porosity is calculated by measuring the apparent density of the brazed assembly.

[0091] Table 1

[0092]

[0093]

[0094] It can be seen from the test results that:

[0095] (1) It can be seen from Examples 1 - 11 and Comparative Examples 1 - 3 that by co - sintering the intermediate layer and the green ceramic body, the present invention can not only improve the adhesion strength of the intermediate layer, but also improve the wettability between the green ceramic body and the Kovar alloy, thereby improving the welding strength of the brazing assembly. In addition, in the solder of the present invention, without adding titanium element and only using silver - copper solder, the wettability between the green ceramic body and the Kovar alloy and the welding strength of the brazing assembly can be further improved.

[0096] (2) It can be seen from Example 1 and Examples 4 - 5 that by further regulating the coating thickness of the intermediate layer, the present invention can further improve the wettability between the green ceramic body and the Kovar alloy and improve the welding strength of the brazing assembly.

[0097] (3) It can be seen from Example 1 and Examples 6 - 7 that by further regulating the holding temperature of sintering, the present invention can further improve the wettability between the green ceramic body and the Kovar alloy and improve the welding strength of the brazing assembly.

[0098] (4) It can be seen from Example 1 and Examples 8 - 9 that by further regulating the welding temperature of vacuum brazing, the present invention can further improve the wettability between the green ceramic body and the Kovar alloy and improve the welding strength of the brazing assembly.

[0099] (5) It can be seen from Example 1 and Examples 10 - 11 that by further regulating the mass ratio of copper and silver in the silver - copper solder, the present invention can further improve the wettability between the green ceramic body and the Kovar alloy and improve the welding strength of the brazing assembly.

[0100] (6) It can be seen from Example 1 and Comparative Examples 1 - 2 that if the intermediate layer is not coated or only the green ceramic body is sintered, brazing cannot be carried out, and thus the brazing assembly described in the present application cannot be prepared.

[0101] (7) It can be seen from Example 1 and Comparative Example 3 that if silver - copper - titanium solder is used, due to the presence of active Ti element, the wettability with ceramics is good, and the porosity of the brazing assembly is low. However, during the brazing process, the Ti element in the solder will diffuse towards the Kovar alloy side, and at the same time, the Ti element reacts with Fe and Ni in the Kovar alloy to form Fe 2 Ni and Ni 3 Ti brittle compounds, reducing the welding strength of the brazing assembly.

[0102] In summary, by co-sintering the intermediate layer and the green ceramic body, the present invention can not only improve the adhesion strength of the intermediate layer, but also improve the wettability between the green ceramic body and the kovar alloy, thereby improving the welding strength of the brazing assembly. In addition, in the solder of the present invention, no titanium element is added, and only silver-copper solder is used, which can further improve the wettability between the green ceramic body and the kovar alloy and the welding strength of the brazing assembly.

[0103] The applicant declares that the above description is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A method for preparing a brazing assembly, characterized in that: The preparation method comprises the following steps: After coating the intermediate layer slurry on the surface of the ceramic green body, drying and sintering are performed in sequence to obtain a treated ceramic material; vacuum brazing the treated ceramic material with the Kovar alloy to obtain the brazed assembly; The solder for vacuum brazing is silver-copper solder; The brazing assembly comprises a ceramic material, an intermediate layer and a kovar alloy which are stacked in sequence.

2. The preparation method according to claim 1, characterized in that: The ceramic green body material includes any one of aluminum oxide ceramics, aluminum nitride ceramics or silicon carbide ceramics, or a combination of at least two thereof; Preferably, the intermediate layer slurry includes any one of molybdenum-manganese slurry, tungsten-copper slurry, tungsten slurry or nickel slurry, or a combination of at least two of them.

3. The preparation method according to claim 1 or 2, characterized in that: The coating method includes spraying and / or printing; Preferably, the coating has a thickness of 15 μm-30 μm.

4. The preparation method according to any one of claims 1 to 3, characterized in that The heat preservation temperature of the drying is 80°C-100°C; Preferably, the drying heat preservation time is 10min-30min.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The sintering holding temperature is 1600°C-1800°C; Preferably, the sintering holding time is 2h-5h; Preferably, the sintering environment atmosphere includes an inert gas atmosphere; Preferably, the sintering environment atmosphere also includes a reducing gas atmosphere.

6. The preparation method according to any one of claims 1 to 5, characterized in that: Before the vacuum brazing, the treated ceramic material and the Kovar alloy are cleaned respectively; Preferably, the cleaning detergent comprises deionized water; Preferably, the cleaning is performed 3 to 5 times.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The welding temperature of the vacuum brazing is 800°C-850°C; Preferably, the vacuum brazing time is 5 min-15 min.

8. The preparation method according to any one of claims 1 to 7, characterized in that: In the silver-copper solder, the mass ratio of copper to silver is (5-7):(3-5).

9. A brazing assembly, characterized in that: The brazing assembly is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the brazing assembly according to claim 9, characterized in that: The brazing assembly is used in the preparation of an electrostatic chuck.

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