A seal, a vacuum-sealed radio frequency connection device and an assembly method thereof

Abstract

The present invention discloses a seal, a radio frequency connection device with vacuum seal and an assembly method thereof. The seal includes a cylindrical kovar alloy housing with openings at both ends and a cylindrical kovar alloy pin, and further includes an annular alumina ceramic sheet. Metal layers are provided on the inner hole surface and the outer circumferential surface of the alumina ceramic sheet. The outer diameter of the kovar alloy pin is welded to the inner hole of the alumina ceramic sheet, and the outer circle of the alumina ceramic sheet is welded to the inner hole of the kovar alloy housing. The present invention effectively solves the problem that the ordinary glass of the glass insulator cannot be welded at high temperature to make the radio frequency connection device applicable to a high-temperature vacuum environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum radio frequency connection, and specifically relates to a seal and a vacuum-sealed radio frequency connection device and an assembly method thereof. Background Art

[0002] Ordinary radio frequency connection devices and their structures do not have gas tightness. They cannot meet the environmental requirements of high-vacuum microwave transmission. In a vacuum environment, low-temperature solder joints will vaporize and contaminate the vacuum environment, so the use of low-temperature soldering processes is not allowed. During high-temperature soldering, due to the problem of ordinary glass softening at high temperatures, the glass insulator may change its electrical properties and cannot meet the usage requirements. Moreover, the glass insulator will crack due to internal stress problems after high-temperature soldering. Existing radio frequency connection devices cannot meet the usage requirements of waveguide transmission conversion to coaxial transmission in a vacuum environment. The current problem is that the ordinary glass of the glass insulator cannot be high-temperature soldered to make the radio frequency connection device suitable for a high-temperature vacuum environment. Summary of the Invention

[0003] The purpose of the present invention is to provide a seal and a vacuum-sealed radio frequency connection device and an assembly method thereof to solve the problem in the background art that the ordinary glass of the glass insulator cannot be high-temperature soldered to make the radio frequency connection device suitable for a high-temperature vacuum environment.

[0004] To solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0005] The first invention of the present invention provides a seal, which includes a cylindrical kovar alloy housing with two open ends and a cylindrical kovar alloy pin; it also includes a circular alumina ceramic sheet, and metal layers are provided on the inner hole surface and the outer circular surface of the alumina ceramic sheet. The outer diameter of the kovar alloy pin is welded to the inner hole of the alumina ceramic sheet, the outer circle of the alumina ceramic sheet is welded to the inner hole of the kovar alloy housing, and both ends of the kovar alloy pin extend out of the inner hole of the kovar alloy housing.

[0006] In a possible design, the kovar alloy housing includes a first end and a second end. A circular boss is provided on the outer diameter of the first end, and one end face of the boss is an installation face, and the installation face is parallel to the end face of the first end.

[0007] In a possible design, the distance between the end face of the first end and the end face of the nearest alumina ceramic sheet is 1-7 millimeters.

[0008] In a possible design, nickel layers are provided at the welding joints of the kovar alloy pin and the welding joints of the kovar alloy housing.

[0009] The second invention of the present invention provides a vacuum-sealed RF connection device, which includes an RF connector, a matching table, and any one of the seals described in the first invention. The RF connector includes an input end and an output end. A through hole is provided on the matching table, and the matching table is arranged between the input end of the RF connector and the end face of the alumina ceramic sheet close to the second end. The through hole forms an annular cavity between the RF connector and one end face of the alumina ceramic sheet. One end of the kovar alloy pin passes through the through hole and is connected to the input end of the RF connector.

[0010] In a possible design, an installation hole for disassembling and assembling the RF connector is also provided on the RF connector.

[0011] The third invention of the present invention provides an assembly method for a vacuum-sealed RF connection device, which is used to assemble any one of the vacuum-sealed RF connection devices described in the second invention on a vacuum chamber housing. An installation groove is provided on the vacuum chamber housing, and a waveguide hole is provided between the bottom surface of the installation groove and the vacuum chamber. The assembly method includes:

[0012] Step S1: Metallize the inner hole surface and the outer circular surface of the alumina ceramic sheet;

[0013] Step S2: Weld between the outer diameter of the kovar alloy pin and the inner hole of the alumina ceramic sheet, and weld between the outer circle of the alumina ceramic sheet and the inner hole of the kovar alloy housing;

[0014] Step S3: Connect one end of the kovar alloy pin to the vacuum chamber through the waveguide hole, and weld one end face of the kovar alloy housing to the bottom surface of the installation groove; or

[0015] Step S3: Connect one end of the kovar alloy pin to the vacuum chamber through the waveguide hole, and weld the installation surface of the boss to the bottom surface of the installation groove.

[0016] As an optimization, a threaded hole is also provided on the vacuum chamber housing, and the following steps are further included:

[0017] Step S4: Connect one end face of the matching table to the end face of the alumina ceramic sheet close to the second end, and connect the opposite end face to the input end of the RF connector. The through hole forms an annular cavity between the input end of the RF connector and the end face of the alumina ceramic sheet. One end of the kovar alloy pin passes through the annular cavity and is connected to the input end of the RF connector. Use screws to fixedly install the RF connector on the vacuum chamber housing.

[0018] As an optimization, the welding in both Step S2 and Step S3 is completed by vacuum brazing.

[0019] In a possible method, in step S2, the welding portion of the kovar alloy pin is nickel-plated before welding; in step S3, the welding portions of the vacuum chamber housing and the kovar alloy housing are nickel-plated before welding.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. A seal provided by the present invention replaces the glass material in a common glass insulator with a ceramic sheet made of alumina material, improving the high-temperature resistance performance of the seal. It will not soften or cause changes in electrical performance during high-temperature welding.

[0022] 2. A seal provided by the present invention is provided with metal layers on both the inner hole surface and the outer circular surface of the alumina ceramic sheet, providing feasibility for high-temperature welding of the kovar alloy housing 3 and the kovar alloy pin on the alumina ceramic sheet, so that the seal can meet the use requirements of waveguide transmission in a vacuum environment after high-temperature welding.

[0023] 3. For a seal provided by the present invention, when welding the outer diameter of the kovar alloy pin to the inner hole of the alumina ceramic sheet, due to the reasonable selection of materials, the expansion coefficients of the alumina ceramic material and the kovar alloy material are close, which can effectively reduce the stress concentration problem inside the alumina ceramic sheet and effectively avoid the rupture of the alumina ceramic sheet.

[0024] 4. A seal provided by the present invention is provided with an annular boss on the outer diameter of the first end. When welding the mounting surface of the boss to the device and welding the outer circle of the alumina ceramic sheet to the inner hole of the kovar alloy housing, due to the selection of the welding position, the pulling of the internal stress generated by the different expansion coefficients of the two different materials on the alumina ceramic sheet is effectively eliminated, and the rupture of the alumina ceramic can be effectively avoided; the boss can also increase the welding area at the end of the kovar alloy housing, reducing the welding difficulty and making the welding more stable.

[0025] 5. In a vacuum-sealed radio frequency connection device provided by the present invention, a relatively expensive radio frequency connector can use common standard parts, effectively avoiding the use of more special parts, reducing costs, reducing the welded parts, and simplifying the sealing structure.

[0026] 6. A vacuum-sealed radio frequency connection device provided by the present invention can form a cylindrical cavity between the input end of the radio frequency connector and the end face of the alumina ceramic sheet near the second end by setting a matching table to better meet the electrical performance in waveguide transmission.

[0027] 7. An assembly method of a vacuum-sealed radio frequency connection device provided by the present invention. In step S2, due to the reasonable selection of materials, the expansion coefficients of the alumina ceramic material and the kovar alloy material are close, which can effectively reduce the stress concentration problem inside the alumina ceramic sheet and effectively avoid the cracking of the alumina ceramic sheet. In step S3, due to the selection of the welding position, the pulling of the internal stress generated by the different expansion coefficients of the two different materials on the alumina ceramic sheet is effectively eliminated, and the cracking of the alumina ceramic can be effectively avoided.

[0028] 8. An assembly method of a vacuum-sealed radio frequency connection device provided by the present invention ensures the sealing performance requirements of the vacuum-sealed radio frequency connection device through the welding procedures in step S2 and step S3.

[0029] 9. In the assembly method of a vacuum-sealed radio frequency connection device provided by the present invention, the welding in step S2 and step S3 is completed by vacuum brazing. High-temperature welding can avoid the vaporization of the weld seam in a high-vacuum environment and damage the vacuum chamber environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the overall structure of the seal in the present invention;

[0031] Figure 2 It is a schematic diagram of the structure when the vacuum-sealed radio frequency connection device in the present invention is in use.

[0032] Reference numerals: 1 - alumina ceramic sheet; 2 - kovar alloy pin; 3 - kovar alloy housing; 31 - boss; 32 - first end; 33 - second end; 34 - chamfer; 4 - matching table; 41 - through hole; 5 - radio frequency connector; 51 - mounting hole; 6 - vacuum chamber housing; 7 - kovar alloy support; H1-1 - first solder joint; H1-2 - second solder joint; H2 - third solder joint; D - spacing distance. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0034] Embodiment

[0035] Embodiment 1

[0036] Please refer to Figure 1, A seal, comprising a cylindrical kovar alloy housing 3 with openings at both ends and a cylindrical kovar alloy pin 2, further comprising an annular alumina ceramic sheet 1. Metal layers are provided on both the inner hole surface and the outer circular surface of the alumina ceramic sheet 1. The outer diameter of the kovar alloy pin 2 is adapted to the inner hole of the alumina ceramic sheet 1. The kovar alloy pin 2 is inserted into the inner hole of the alumina ceramic sheet 1 and welded and fixed after reaching a suitable position. The welding makes the kovar alloy pin 2 and the inner hole of the alumina ceramic sheet 1 completely sealed. Both ends of the kovar alloy pin 2 extend beyond the inner hole of the alumina ceramic sheet 1. The outer circle of the alumina ceramic sheet 1 is adapted to the inner hole of the kovar alloy housing 3. After the outer circle of the alumina ceramic sheet 1 and the inner hole of the kovar alloy housing 3 are fitted at a suitable position, they are welded and fixed. Both ends of the kovar alloy pin 2 extend out of the inner hole of the kovar alloy housing 3.

[0037] Ordinary seals do not have gas tightness in their structures and cannot meet the environmental requirements of high-vacuum microwave transmission. In a vacuum system, since there will be vaporization phenomenon during low-temperature welding in a vacuum environment, which will contaminate the vacuum environment, the low-temperature welding process is not allowed. During high-temperature welding, the commonly used glass insulators may change their electrical properties due to the problem of ordinary glass softening at high temperature and cannot meet the usage requirements. Moreover, after high-temperature welding, the glass will crack due to stress problems inside, causing the equipment to malfunction and resulting in losses. Existing seals cannot meet the usage requirements of waveguide transmission to coaxial transmission in a vacuum environment. A seal provided in this embodiment uses a ceramic sheet made of alumina to replace the glass material in an ordinary glass insulator. At the same time, metal layers are provided on both the inner hole surface and the outer circular surface of the alumina ceramic sheet 1. The alumina ceramic sheet 1 material itself has high-temperature resistance, and metal layers are provided on both the inner hole surface and the outer circular surface of the alumina ceramic sheet 1, which provides feasibility for high-temperature welding of the kovar alloy housing 3 and the kovar alloy pin 2 on the alumina ceramic sheet 1, so that the seal can meet the usage requirements of waveguide transmission in a vacuum environment after high-temperature welding. Compared with glass, the alumina ceramic sheet 1 will not soften after high-temperature welding and will not crack due to stress problems, solving the problem of glass deformation during high-temperature welding, with more stable working performance, effectively reducing the number of maintenance times and reducing the maintenance cost. When the outer diameter of the kovar alloy pin 2 is welded to the inner hole of the alumina ceramic sheet 1, due to the reasonable selection of materials, the expansion coefficients of the alumina ceramic material and the kovar alloy material are close, which can effectively reduce the stress concentration problem inside the alumina ceramic sheet 1 and effectively avoid the rupture of the alumina ceramic sheet 1.

[0038] The kovar alloy housing 3 includes a first end 32 and a second end 33. A circular boss 31 is provided on the outer diameter of the first end 32. One end face of the boss 31 is an installation face, and the installation face is parallel to the end face of the first end 32.

[0039] By providing an annular boss 31 on the outer diameter of the first end 32, when welding the mounting surface of the boss 31 to the device and welding the outer circle of the alumina ceramic sheet 1 to the inner hole of the kovar alloy housing 3, due to the selection of the welding positions, the two welding positions, namely the welding position between the mounting surface and the device and the welding position between the outer circle of the alumina ceramic sheet 1 and the kovar alloy housing 3, are far apart, and the directions of stress generation during welding are different, effectively eliminating the pulling of the alumina ceramic sheet caused by the internal stress generated due to the different expansion coefficients of the two different materials, and effectively avoiding the cracking of the alumina ceramic. The boss 31 can also increase the welding area at the end of the kovar alloy housing 3, reduce the welding difficulty, and achieve a better welding stability effect.

[0040] The spacing distance D between the end face of the first end 32 and the end face of the nearest alumina ceramic sheet 1 is 1 - 7 mm. Preferably, the spacing distance D between the end face of the first end 32 and the end face of the nearest alumina ceramic sheet 1 is 7 mm, and the circular cavity formed by the kovar alloy housing 3 within this distance is filled with a circular kovar alloy support 7. By setting the spacing distance D between the end face of the first end 32 and the end face of the nearest alumina ceramic sheet 1 to 7 mm, the distance from the mounting surface of the boss 31 to the alumina ceramic sheet 1 can be increased, which can better disperse the stress generated at the welding position of the mounting surface of the boss 31, the welding position of the alumina ceramic sheet 1 and the kovar alloy housing 3, and further reduce the probability of the alumina ceramic sheet 1 cracking. By providing the kovar alloy support 7 to fill a section of the cavity near the first end 32 within the kovar alloy housing 3, the electrical performance during microwave conduction can be better satisfied.

[0041] A chamfer 34 is provided between the mounting surface and the outer circular surface of the kovar alloy housing 3. Without the chamfer 34, the angle between the mounting surface and the outer circular surface of the kovar alloy housing 3 is a right angle, and it is very easy to be blocked and unable to be correctly assembled when assembling with a right - angled groove. By providing the chamfer 34, the situation where the kovar alloy housing 3 cannot be correctly assembled due to the right angle between its mounting surface and outer circular surface can be avoided, making the assembly more likely to succeed.

[0042] Nickel layers are provided at the welding positions of the kovar alloy pin 2 and the welding positions of the kovar alloy housing 3. The nickel layer has better fluidity during welding, can effectively enhance the capillary action effect at the welding position, make the weld seam more dense, without defects such as gas entrapment and slag inclusion, and further improve the sealing performance at the welding position, enabling the seal to better meet the usage requirements in a vacuum environment.

[0043] Embodiment 2

[0044] Please refer to Figure 2 A vacuum - sealed radio - frequency connection device, including a radio - frequency connector 5, further includes a matching stage 4 and any one of the seals described in Embodiment 1.

[0045] The RF connector 5 includes an input end and an output end. A through hole 41 is provided on the matching table 4. The matching table 4 is disposed between the input end of the RF connector 5 and the end face of the alumina ceramic sheet 1 near the second end 33. The through hole 41 forms an annular cavity between the RF connector 5 and one end face of the alumina ceramic sheet 1. One end of the kovar alloy pin 2 passes through the through hole 41 and is connected to the input end of the RF connector 5.

[0046] In the waveguide vacuum system, for the sealing performance requirements of converting waveguide transmission into coaxial transmission, in the past, the RF connection device was integrally manufactured, with high manufacturing costs and complex structures. In this embodiment, the relatively expensive RF connector 5 can use common standard parts, effectively avoiding the use of more special parts, reducing costs, reducing the parts to be welded, and simplifying the sealing structure. By providing the matching table 4, a cylindrical cavity can be formed between the input end of the RF connector 5 and the end face of the alumina ceramic sheet 1 near the second end 33 to better meet the electrical performance in waveguide transmission.

[0047] The RF connector 5 is further provided with a mounting hole 51 for disassembling and assembling the RF connector 5. By providing the mounting hole 51, during use, the RF connector 5 with different frequencies can be replaced according to different working requirements, or the RF connector 5 can be replaced separately after it is damaged, making the use and installation more convenient, and effectively reducing the maintenance cost.

[0048] Embodiment 3

[0049] An assembly method of a vacuum-sealed RF connection device for assembling any one of the vacuum-sealed RF connection devices described in Embodiment 2 on the vacuum chamber housing 6. The vacuum chamber housing 6 is provided with a mounting groove, and a waveguide hole is provided between the bottom surface of the mounting groove and the vacuum chamber.

[0050] It is characterized in that: the assembly method includes:

[0051] Step S1: Metallize the inner hole surface and the outer circular surface of the alumina ceramic sheet 1; the metallization treatment methods include but are not limited to electroless Ni-P plating method, electroplating Ni method, and vacuum evaporation coating method. Through Step S1, the alumina ceramic sheet 1 is made to have the performance of welding other parts.

[0052] Step S2: Weld between the outer diameter of the kovar alloy pin 2 and the inner hole of the alumina ceramic sheet 1, and the welding point is the first welding point H1-1; weld between the outer circle of the alumina ceramic sheet 1 and the inner hole of the kovar alloy housing 3, and the welding point is the second welding point H1-2. Due to the reasonable selection of materials, the expansion coefficients of the alumina ceramic material and the kovar alloy material are close, which can effectively reduce the stress concentration problem inside the alumina ceramic sheet 1 and effectively avoid the cracking of the alumina ceramic sheet 1.

[0053] Step S3: When the Kovar alloy housing 3 does not have a boss 31, one end of the Kovar alloy pin 2 near the first end 32 is connected to the vacuum chamber through a waveguide hole, and one end face of the Kovar alloy housing 3 is welded to the bottom surface of the mounting groove, and the welding point here is the third welding point H2; or, Step S3: When the Kovar alloy housing 3 has a boss 31, one end of the Kovar alloy pin 2 is connected to the vacuum chamber through a waveguide hole, and the mounting surface of the boss 31 is welded to the bottom surface of the mounting groove, and the welding point here is the third welding point H2. When the Kovar alloy housing 3 does not have a boss 31, one end face of the Kovar alloy housing 3 is directly welded to the bottom surface of the mounting groove, with simple process and compact structure; when the Kovar alloy housing 3 has a boss 31, the mounting surface of the boss 31 is welded to the bottom surface of the mounting groove. Due to the selection of the welding position, the pulling of the alumina ceramic sheet caused by the internal stress generated by the different expansion coefficients of the two different materials is effectively eliminated, and the cracking of the alumina ceramic can be effectively avoided.

[0054] The welding in both Step S2 and Step S3 is completed by vacuum brazing. Vacuum brazing can weld devices with more complex and narrow channels, effectively improve the welding quality, increase the product yield, and make the working surface more firm and clean;

[0055] The specific welding method in Step S2 is to fix the Kovar alloy pin 2, the alumina ceramic sheet 1 and the Kovar alloy housing 3 with a tooling. There is solder at the welding point, and then the seal is placed in a vacuum brazing furnace. In a vacuum and high-temperature environment, the solder melts to weld and fix the Kovar alloy pin 2, the alumina ceramic sheet 1 and the Kovar alloy housing 3. Preferably, the solder is a silver-copper wire.

[0056] The specific welding method in Step S3 is to fix the Kovar alloy housing 3 on the vacuum chamber housing 6 with a tooling. There is solder at the welding point, and the Kovar alloy housing 3 and the vacuum chamber housing 6 are placed in a vacuum brazing furnace. In a vacuum and high-temperature environment, the solder melts to weld and fix the Kovar alloy housing 3 and the vacuum chamber housing 6. Preferably, the solder is a silver-copper solder sheet, and the shape and size of the solder sheet are adapted to the welding point.

[0057] After the welding in Step S2 and Step S3 is completed, helium leak detection is carried out. Only after passing the helium leak detection can the next step be carried out, which can effectively prevent the situation where the sealing performance during welding does not meet the standard.

[0058] The vacuum chamber housing 6 is also provided with threaded holes. It further includes step S4: One end face of the matching table 4 is connected to the end face of the alumina ceramic sheet 1 close to the second end 33, and the opposite end face is connected to the input end of the RF connector 5. The through hole 41 forms an annular cavity between the input end of the RF connector 5 and the end face of the alumina ceramic sheet 1. One end of the kovar alloy pin 2 passes through the annular cavity and is connected to the input end of the RF connector 5. The RF connector 5 is fixedly installed on the vacuum chamber housing 6 using screws. Through the above detachable connection, the RF connector 5 can be replaced with common and commonly used parts, effectively avoiding the use of more special parts, reducing costs, reducing the parts to be welded, and simplifying the sealing structure.

[0059] In step S2, the welding part of the kovar alloy pin 2 is nickel-plated before welding; in step S3, the welding parts of the vacuum chamber housing 6 and the kovar alloy housing 3 are nickel-plated before welding. Nickel has better fluidity during welding, can effectively enhance the capillary action effect at the welding part, make the weld more dense, and there will be no defects such as gas entrapment and slag inclusion, further improving the sealing performance of the welding part, so that the seal can better meet the use requirements in a high-vacuum environment.

[0060] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inner", "front", "center", "both ends", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to the present invention.

[0061] In the present invention, unless otherwise clearly defined and limited, terms such as "installation", "setting", "connection", "fixation", "swivel connection", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. It can be the internal communication of two elements or the interaction relationship between two elements. Unless otherwise clearly limited, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0062] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A seal, comprising a cylindrical kovar alloy housing (3) with openings at both ends and a cylindrical kovar alloy pin (2), characterized in that: It further comprises an annular alumina ceramic sheet (1), and metal layers are provided on both the inner hole surface and the outer circular surface of the alumina ceramic sheet (1). The outer diameter of the kovar alloy pin (2) is welded to the inner hole of the alumina ceramic sheet (1), and the outer circle of the alumina ceramic sheet (1) is welded to the inner hole of the kovar alloy housing (3). Both ends of the kovar alloy pin (2) extend out of the inner hole of the kovar alloy housing (3). The kovar alloy housing (3) includes a first end (32) and a second end (33). A circular boss (31) is provided on the outer diameter of the first end (32). One end face of the boss (31) is an installation surface, and the installation surface is parallel to the end face of the first end (32). The distance between the end face of the first end (32) and the end face of the nearest alumina ceramic sheet (1) is 1 - 7 mm. Increasing the distance from the installation surface of the boss (31) to the alumina ceramic sheet (1) can better disperse the stress generated at the welding joint of the installation surface of the boss (31), the welding joint of the alumina ceramic sheet (1) and the kovar alloy housing (3), and further reduce the probability of the alumina ceramic sheet (1) cracking. The kovar alloy pin (2), the alumina ceramic sheet (1) and the kovar alloy housing (3) are fixed using a tooling, solder is provided at the welding joints, and then the seal is placed in a vacuum brazing furnace. In a vacuum and high-temperature environment, the solder melts to weld and fix the kovar alloy pin (2), the alumina ceramic sheet (1) and the kovar alloy housing (3) together.

2. The seal according to claim 1, characterized in that: Nickel layers are provided at the welding joints of the kovar alloy pin (2) and the welding joints of the kovar alloy housing (3).

3. A vacuum-sealed radio frequency connection device, comprising a radio frequency connector (5), characterized in that: It further comprises a matching table (4) and a seal as described in any one of claims 1 - 2. The RF connector (5) includes an input end and an output end. A through hole (41) is provided on the matching table (4). The matching table (4) is arranged between the input end of the RF connector (5) and the end face of the alumina ceramic sheet (1) close to the second end (33). The through hole (41) forms an annular cavity between the RF connector (5) and an end face of the alumina ceramic sheet (1), and one end of the kovar alloy pin (2) passes through the through hole (41) to be connected to the input end of the RF connector (5).

4. A vacuum-sealed radio frequency connection device according to claim 3, characterized in that: An installation hole (51) for disassembling and assembling the RF connector (5) is further provided on the RF connector (5).

5. An assembly method for a vacuum-sealed RF connection device, used to assemble a vacuum-sealed RF connection device as described in any one of claims 3 - 4 on a vacuum chamber housing (6). An installation groove is provided on the vacuum chamber housing (6), and a waveguide hole is provided between the bottom surface of the installation groove and the vacuum chamber. It is characterized in that: The assembly method includes: Step S1: Metallize the inner hole surface and the outer circular surface of the alumina ceramic sheet (1). Step S2: Weld between the outer diameter of the kovar alloy pin (2) and the inner hole of the alumina ceramic sheet (1), and weld the outer circle of the alumina ceramic sheet (1) and the inner hole of the kovar alloy housing (3). Step S3: Connect one end of the kovar alloy pin (2) to the vacuum chamber through the waveguide hole, and weld one end face of the kovar alloy housing (3) to the bottom surface of the mounting groove; or Step S3: Connect one end of the kovar alloy pin (2) to the vacuum chamber through the waveguide hole, and weld the mounting surface of the boss (31) to the bottom surface of the mounting groove.

6. The assembling method of a vacuum-sealed radio frequency connection device according to claim 5, characterized in that: The vacuum chamber housing (6) is further provided with a threaded hole. The following steps are further included: Step S4: Connect one end face of the matching stage (4) to the end face of the alumina ceramic sheet (1) close to the second end (33), connect the opposite end face to the input end of the RF connector (5), and the through hole (41) forms an annular cavity between the input end of the RF connector (5) and the end face of the alumina ceramic sheet (1). One end of the kovar alloy pin (2) passes through the annular cavity and is connected to the input end of the RF connector (5), and use screws to fixedly mount the RF connector (5) to the vacuum chamber housing (6).

7. The assembling method of a vacuum-sealed radio frequency connection device according to claim 6, characterized in that: The welding in Step S2 and Step S3 is completed by vacuum brazing.

8. The assembling method of a vacuum-sealed radio frequency connection device according to claim 6, characterized in that: In Step S2, nickel plating is performed on the welding part of the kovar alloy pin (2) before welding; in Step S3, nickel plating is performed on the welding part of the vacuum chamber housing (6) and the welding part of the kovar alloy housing (3) before welding.

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