A copper welding method based on the metallization of microwave absorbing material thin film

Abstract

A copper welding method based on the metallization of a microwave absorbing material thin film is disclosed, which welds the microwave absorbing material to copper. The method includes: step S1, pretreating the microwave absorbing material and the copper to be welded; step S2, depositing an active metal layer on the surface of the microwave absorbing material to be welded by sputtering; step S3, depositing a welding metal layer on the surface of the active metal layer; step S4, preparing solder; and step S5, achieving the welding of the microwave absorbing material and copper. This invention has the advantage of producing a film layer with high bonding strength to the ceramic.

Description

Technical Field

[0001] This invention relates to the field of microwave absorbing material bonding technology, and in particular to a copper welding method based on the metallization of microwave absorbing material thin films. Background Technology

[0002] Ferrite materials have excellent electromagnetic loss and high-frequency characteristics, which can effectively attenuate or absorb radio frequency energy. They are commonly used materials for high-order mode absorbers in the development of large scientific facilities. Both domestically and internationally, bonding, magnetron sputtering, silvering, glass brazing and other methods are generally used for connection.

[0003] In the development of absorbers, ferrite ceramics absorb radio frequency energy and convert it into heat, which is then conducted away through a thermally conductive metal. This raises the issue of a good connection between the ferrite ceramic and the metal. Bonding typically uses epoxy resins to bond the ferrite to the metal, but this method has low bonding strength, is prone to gas release, and has poor thermal conductivity. Silver bonding also results in low bonding strength, and silver ions easily penetrate the ferrite, causing a decrease in absorption performance. Glass brazing often results in low bonding strength, high brittleness, and poor thermal conductivity; furthermore, glass brazing is generally performed in an atmospheric environment, causing severe oxidation of the metal. Summary of the Invention

[0004] The purpose of this invention is to provide a copper welding method based on the metallization of microwave absorbing material thin films, which has the advantage of high bonding strength between the prepared film and the ceramic.

[0005] To achieve the above objectives, this invention provides a copper welding method based on the metallization of a microwave absorbing material thin film, for welding the microwave absorbing material and copper; the method includes: step S1, pre-treating the microwave absorbing material and the copper to be welded; step S2, depositing an active metal layer on the surface of the microwave absorbing material to be welded by sputtering; step S3, depositing a welding metal layer on the surface of the active metal layer; in step S3, a welding metal layer is directly deposited on the surface of the active metal layer using a film deposition technique, or a thin welding metal layer is deposited first, and then the welding metal layer is thickened by electroplating; step S4, preparing solder; in step S3, a solder sheet is used, or a solder sheet is deposited on the welding metal... A 5-20 μm layer of solder is deposited on the surface of the layer, or solder is prepared in the form of solder paste; in step S5, the microwave absorbing material after solder deposition is assembled with copper in sequence, or the microwave absorbing material with deposited solder metal layer is assembled with solder sheet / solder paste and copper in sequence. Welding pressure is applied, and the temperature is heated to 200°C at a heating rate of 10°C / min under a pressure less than one standard atmosphere, and then held for 30 min. Then the temperature is heated to 250-450°C at a heating rate of 6-10°C / min and held for 10-120 min. Subsequently, the temperature is reduced to 200°C at a cooling rate of 5-10°C / min, and finally cooled to room temperature with the furnace to achieve the welding of microwave absorbing material and copper.

[0006] Preferably, the absorbing material includes ferrite ceramics and silicon carbide ceramics.

[0007] Preferably, step S1 includes: step S11, successively polishing the microwave absorbing material with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; step S12, successively polishing the copper with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; step S13, ultrasonically cleaning the polished microwave absorbing material and copper with an alkaline solution; step S14, ultrasonically cleaning the ultrasonically cleaned microwave absorbing material and copper with deionized water for 30-60 minutes; step S15, acid washing the copper after ultrasonic cleaning with deionized water; and step S16, drying the cleaned microwave absorbing material and copper at 100-150°C.

[0008] Preferably, in step S2, the active metal layer is titanium or chromium; the thickness of the active metal layer is 100~500 nm.

[0009] Preferably, in step S3, the welding metal layer is made of copper, silver, or gold.

[0010] Preferably, step S3 includes: directly depositing a 3-50 μm welding metal layer on the surface of the active metal layer; or first depositing a 1-3 μm welding metal layer, and then thickening the welding metal layer to 3-50 μm by electroplating.

[0011] Preferably, the solder in step S3 is tin.

[0012] Preferably, in step S5, the welding pressure is 0.6~2 N / cm. 2 .

[0013] In summary, compared with the prior art, the copper welding method based on the metallization of microwave absorbing material thin film provided by the present invention has the following beneficial effects:

[0014] First, the present invention sputters a thin metal film onto the surface of ferrite ceramic, thereby giving the surface of ferrite ceramic the weldability of metal, which can be used to weld ferrite together with other metals using metal solder.

[0015] Secondly, the film layer prepared by this invention has the characteristics of high bonding strength and good consistency with ceramics. After the low-temperature solder melts at its melting point, it undergoes liquid phase diffusion welding with the welding layer and copper, which enables welding to be achieved at a lower temperature and can be used at a higher welding temperature. This achieves reliable connection between absorbing materials such as ferrite ceramics and silicon carbide ceramics and metals. The resulting joint has high connection strength and good thermal conductivity, which can effectively conduct away the heat absorbed by the absorbing material. Attached Figure Description

[0016] Figure 1 These are micrographs of an embodiment of the present invention.

[0017] Figure 2 This is a flowchart of the present invention.

[0018] Figure 3 The data results are from an embodiment of the present invention. Detailed Implementation

[0019] The following will be combined with the appendix in the embodiments of the present invention. Figure 1 ~Appendix Figure 3 The technical solutions, structural features, objectives and effects achieved in the embodiments of the present invention will be described in detail.

[0020] It should be noted that the accompanying drawings are in a very simplified form and use non-precise proportions. They are only used to facilitate and clarify the purpose of illustrating the embodiments of the present invention, and are not intended to limit the implementation conditions of the present invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationship, or adjustments to the size should still fall within the scope of the technical content disclosed in the present invention, provided that they do not affect the effects and objectives that the present invention can produce.

[0021] It should be noted that, in this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only the expressly listed elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0022] This invention discloses a copper welding method based on the metallization of a thin film of microwave absorbing material, which welds the microwave absorbing material to copper. The microwave absorbing material includes ferrite ceramics, silicon carbide ceramics, etc. Taking ferrite ceramics as an example, conventional metal solders cannot effectively wet ferrite ceramics. This method sputters a thin metal film onto the surface of the ferrite ceramic, thus giving the ferrite ceramic surface metallic weldability, allowing the ferrite to be welded to other metals using metal solder.

[0023] like Figure 2 As shown, the method includes:

[0024] Step S1: Pre-treat the microwave absorbing material and the copper to be welded:

[0025] The surfaces of the absorbing materials to be welded are ground, cleaned, and dried; the surfaces of the copper to be welded are ground, pickled, and dried.

[0026] Step S2: An active metal layer is deposited on the surface of the microwave absorbing material to be welded by sputtering.

[0027] Specifically, the aforementioned technical effects can be achieved by using magnetron sputtering technology to deposit an active metal layer on the surface of the microwave absorbing material to be welded; or by using evaporation coating, ion plating, or other similar technologies.

[0028] Step S3: Deposit a welding metal layer on the surface of the active metal layer;

[0029] Specifically, by using coating technology, a welding metal layer is directly deposited on the surface of the active metal layer, or a thin welding metal layer is deposited first, and then the welding metal layer is thickened by electroplating.

[0030] Step S4, prepare solder;

[0031] Specifically, in some embodiments, the solder can be a solder sheet, or it can be a 5-20 μm layer of solder deposited on the surface of the solder metal layer, or solder paste to achieve the same technical effect.

[0032] Step S5: Sequentially assemble the microwave absorbing material after solder deposition with copper, or sequentially assemble the microwave absorbing material with deposited solder metal layer with solder sheet / solder paste and copper. Apply a certain pressure and heat to 200°C at a heating rate of 10°C / min under a pressure less than one standard atmosphere. Then hold at that temperature for 30 minutes. Next, heat to 250-450°C at a heating rate of 6-10°C / min and hold for 10-120 minutes. Then, cool down to 200°C at a cooling rate of 5-10°C / min. Finally, cool to room temperature with the furnace to achieve the welding of microwave absorbing material and copper.

[0033] The welding pressure is typically 0.6~2 N / cm. 2 This coefficient is calculated by multiplying the welding area by the weight placed on the weldment during welding; this needs to be adjusted adaptively according to the situation.

[0034] Furthermore, given that Sn has a melting point of 231.89℃, welding temperatures above this level cause Sn metal to melt and react chemically with Cu to form Sn-Cu intermetallic compounds. Since the melting point of Sn-Cu intermetallic compounds is higher than that of Sn, the welded parts can be used at temperatures exceeding the welding temperature. However, if excessively high welding temperatures are used, over-reaction can occur, leading to significant copper dissolution and the formation of voids, resulting in reduced weld strength.

[0035] In a specific embodiment, in step S5, a vacuum furnace is used for welding.

[0036] In a specific embodiment, step S1 includes:

[0037] Step S11: The microwave absorbing material is polished successively using sandpaper of 400 grit, 800 grit, 1000 grit and 2000 grit.

[0038] Step S12: The copper is polished successively using sandpaper of 400 grit, 800 grit, 1000 grit and 2000 grit.

[0039] The purpose of using sandpaper for polishing is that welding generally requires a certain degree of roughness. One reason is to increase the welding area, and the other is to facilitate atomic diffusion, thus achieving better results.

[0040] Step S13: Use an alkaline solution to perform ultrasonic cleaning on the polished microwave absorbing material and copper;

[0041] Step S14: After ultrasonic cleaning, the absorbing material and copper are ultrasonically cleaned with deionized water for 30 min to 60 min.

[0042] Step S15: Acid pickling is performed on the copper after ultrasonic cleaning with deionized water.

[0043] Step S16: Dry the cleaned microwave absorbing material and copper at 100~150℃.

[0044] In a specific embodiment, in step S2, the active metal layer is titanium or chromium; the thickness of the active metal layer is 100~500nm.

[0045] In a specific embodiment, in step S3, the welding metal layer is selected from copper, silver or gold; step S3 includes: directly depositing a 3-50 μm welding metal layer on the surface of the active metal layer; or first depositing a 1-3 μm welding metal layer, and then thickening the welding metal layer to 3-50 μm by electroplating.

[0046] In a specific embodiment, the solder in step S3 is tin.

[0047] The following are specific examples.

[0048] Example 1: The active metal layer is Ti, the welding metal layer is Cu, and the solder is Sn.

[0049] For the surface pretreatment of ferrite ceramics, the ferrite ceramic surfaces to be welded are polished successively with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; then ultrasonically cleaned with an alkaline solution, and finally ultrasonically cleaned with deionized water for 45 minutes; after cleaning, they are placed in an oven to dry at 120°C.

[0050] An active metal layer was deposited by magnetron sputtering on the ferrite ceramic surface to be welded.

[0051] A 15μm thick Cu welding metal layer is deposited directly on the surface of the active metal layer using magnetron sputtering technology.

[0052] Prepare solder, and prepare a 15μm thick Sn solder sheet;

[0053] Welding involves sequentially assembling the ferrite ceramic, Sn solder sheet, and copper surfaces to be welded after the deposition of the welding metal layer, applying a certain pressure, and placing them in a vacuum furnace for welding.

[0054] The material is heated to 200℃ at a heating rate of 10℃ / min, held at that temperature for 30 min, then heated to 300℃ at a heating rate of 8℃ / min and held for 20 min. Subsequently, the temperature is reduced to 200℃ at a cooling rate of 10℃ / min, and finally cooled to room temperature in the furnace to achieve the welding of the microwave absorbing material with copper.

[0055] Example 2: The active metal layer is Cr, the welding metal layer is Cu, and the solder is Sn.

[0056] For the surface pretreatment of ferrite ceramics, the ferrite ceramic surfaces to be welded are polished successively with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; then ultrasonically cleaned with an alkaline solution, and finally ultrasonically cleaned with deionized water for 45 minutes; after cleaning, they are placed in an oven to dry at 120°C.

[0057] An active metal layer was deposited by using magnetron sputtering technology to deposit a 300 nm thick Cr active metal layer on the ferrite ceramic surface to be welded.

[0058] A 15μm thick Cu welding metal layer is deposited directly on the surface of the active metal layer using magnetron sputtering technology.

[0059] Prepare solder, and prepare a 15μm thick Sn solder sheet;

[0060] Welding involves sequentially assembling the ferrite ceramic, Sn solder sheet, and copper surfaces to be welded after the deposition of the welding metal layer, applying a certain pressure, and placing them in a vacuum furnace for welding.

[0061] The material is heated to 200℃ at a heating rate of 10℃ / min, held at that temperature for 30 min, then heated to 250℃ at a heating rate of 6℃ / min and held for 20 min. Subsequently, the temperature is reduced to 200℃ at a cooling rate of 10℃ / min, and finally cooled to room temperature in the furnace to achieve the welding of the microwave absorbing material with copper.

[0062] Example 3: The active metal layer is Ti, the welding metal layer is Ag, and the solder is Sn.

[0063] For the surface pretreatment of ferrite ceramics, the ferrite ceramic surfaces to be welded are polished successively with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; then ultrasonically cleaned with an alkaline solution, and finally ultrasonically cleaned with deionized water for 45 minutes; after cleaning, they are placed in an oven to dry at 120°C.

[0064] An active metal layer was deposited by magnetron sputtering on the ferrite ceramic surface to be welded.

[0065] A 15μm thick Ag welding metal layer was deposited directly on the surface of the active metal layer using magnetron sputtering technology.

[0066] Prepare solder, and prepare a 15μm thick Sn solder sheet;

[0067] Welding involves sequentially assembling the ferrite ceramic, Sn solder sheet, and copper surfaces to be welded after the deposition of the welding metal layer, applying a certain pressure, and placing them in a vacuum furnace for welding.

[0068] The material is heated to 200℃ at a heating rate of 10℃ / min, held at that temperature for 30 min, then heated to 450℃ at a heating rate of 10℃ / min and held for 20 min. Subsequently, the temperature is reduced to 200℃ at a cooling rate of 5℃ / min, and finally cooled to room temperature in the furnace to achieve the welding of the microwave absorbing material with copper.

[0069] Example 4: The active metal layer is Ti, the welding metal layer is Cu, and the solder is Sn paste.

[0070] For the surface pretreatment of ferrite ceramics, the ferrite ceramic surfaces to be welded are polished successively with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; then ultrasonically cleaned with an alkaline solution, and finally ultrasonically cleaned with deionized water for 45 minutes; after cleaning, they are placed in an oven to dry at 120°C.

[0071] An active metal layer was deposited by magnetron sputtering on the ferrite ceramic surface to be welded.

[0072] A 15μm thick Cu welding metal layer is deposited directly on the surface of the active metal layer using magnetron sputtering technology.

[0073] To prepare solder, Sn powder is mixed with terpineol to form solder paste, which is then coated with a 20μm thick layer of Sn solder paste onto the Cu solder metal layer.

[0074] The welding process involves sequentially assembling the ferrite ceramic and copper surfaces to be welded after applying solder paste, applying a certain pressure, and then placing them in a vacuum furnace for welding.

[0075] The material is heated to 200℃ at a heating rate of 10℃ / min, held at that temperature for 30 min, then heated to 300℃ at a heating rate of 8℃ / min and held for 20 min. Subsequently, the temperature is reduced to 200℃ at a cooling rate of 10℃ / min, and finally cooled to room temperature in the furnace to achieve the welding of the microwave absorbing material with copper.

[0076] Example 5: The active metal layer is Ti, the welding metal layer is Cu, and the solder is Sn.

[0077] For the surface pretreatment of ferrite ceramics, the ferrite ceramic surfaces to be welded are polished successively with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; then ultrasonically cleaned with an alkaline solution, and finally ultrasonically cleaned with deionized water for 45 minutes; after cleaning, they are placed in an oven to dry at 120°C.

[0078] An active metal layer was deposited by magnetron sputtering on the ferrite ceramic surface to be welded.

[0079] A 15μm thick Cu welding metal layer is deposited directly on the surface of the active metal layer using magnetron sputtering technology.

[0080] Prepare solder, and prepare a 5μm thick Sn solder sheet;

[0081] Welding involves sequentially assembling the ferrite ceramic, Sn solder sheet, and copper surfaces to be welded after the deposition of the welding metal layer, applying a certain pressure, and placing them in a vacuum furnace for welding.

[0082] The material is heated to 200℃ at a heating rate of 10℃ / min, held at that temperature for 30 minutes, then heated to 450℃ at a heating rate of 8℃ / min and held for 3 minutes. Subsequently, the temperature is reduced to 200℃ at a cooling rate of 10℃ / min, and finally cooled to room temperature in the furnace to achieve the welding of the microwave absorbing material with copper.

[0083] Example 6: The active metal layer is Ti, the welding metal layer is Cu, and the solder is Sn.

[0084] For the surface pretreatment of silicon carbide ceramics, the surfaces of the silicon carbide ceramics to be welded are polished successively with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; then ultrasonically cleaned with an alkaline solution, and finally ultrasonically cleaned with deionized water for 45 minutes; after cleaning, they are placed in an oven to dry at 120°C.

[0085] An active metal layer was deposited by magnetron sputtering on the silicon carbide ceramic surface to be welded.

[0086] A 15μm thick Cu welding metal layer is deposited directly on the surface of the active metal layer using magnetron sputtering technology.

[0087] Prepare solder, and prepare a 15μm thick Sn solder sheet;

[0088] Welding involves sequentially assembling the silicon carbide ceramic, Sn solder sheet, and copper surface to be welded after the deposition of the welding metal layer, applying a certain pressure, and placing it in a vacuum furnace for welding.

[0089] The material is heated to 200℃ at a heating rate of 10℃ / min, held at that temperature for 30 min, then heated to 300℃ at a heating rate of 80℃ / min and held for 20 min. Subsequently, the temperature is reduced to 200℃ at a cooling rate of 10℃ / min, and finally cooled to room temperature in the furnace to achieve the welding of the microwave absorbing material with copper.

[0090] Comparative Example 1: The active metal layer is Ti, the welding metal layer is Cu, and the solder is Sn. The Cu layer is relatively thin.

[0091] For the surface pretreatment of ferrite ceramics, the ferrite ceramic surfaces to be welded are polished successively with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; then ultrasonically cleaned with an alkaline solution, and finally ultrasonically cleaned with deionized water for 45 minutes; after cleaning, they are placed in an oven to dry at 120°C.

[0092] An active metal layer was deposited by magnetron sputtering on the ferrite ceramic surface to be welded.

[0093] A 2μm thick Cu welding metal layer is deposited directly on the surface of the active metal layer using magnetron sputtering technology.

[0094] Prepare solder, and prepare a 15μm thick Sn solder sheet;

[0095] Welding involves sequentially assembling the ferrite ceramic, Sn solder sheet, and copper surfaces to be welded after the deposition of the welding metal layer, applying a certain pressure, and placing them in a vacuum furnace for welding.

[0096] Heat to 200℃ at a heating rate of 10℃ / min, hold for 30 min, then heat to 300℃ at a heating rate of 8℃ / min and hold for 20 min; then cool to 200℃ at a cooling rate of 10℃ / min, and finally cool to room temperature with the furnace.

[0097] Comparative Example 2: The active metal layer is Ti, the welding metal layer is Cu, and the solder is Sn. The Cu layer is relatively thick.

[0098] For the surface pretreatment of ferrite ceramics, the ferrite ceramic surfaces to be welded are polished successively with 400-grit, 800-grit, 1000-grit, and 2000-grit sandpaper; then ultrasonically cleaned with an alkaline solution, and finally ultrasonically cleaned with deionized water for 45 minutes; after cleaning, they are placed in an oven to dry at 120°C.

[0099] An active metal layer was deposited by magnetron sputtering on the ferrite ceramic surface to be welded.

[0100] A 50 μm thick Cu welding metal layer is deposited directly on the surface of the active metal layer using magnetron sputtering technology.

[0101] Prepare solder, and prepare a 15μm thick Sn solder sheet;

[0102] Welding involves sequentially assembling the ferrite ceramic, Sn solder sheet, and copper surfaces to be welded after the deposition of the welding metal layer, applying a certain pressure, and placing them in a vacuum furnace for welding.

[0103] The material is heated to 200℃ at a heating rate of 10℃ / min, held at that temperature for 30 min, then heated to 300℃ at a heating rate of 8℃ / min and held for 20 min. Subsequently, the temperature is reduced to 200℃ at a cooling rate of 10℃ / min, and finally cooled to room temperature in the furnace to achieve the welding of the microwave absorbing material with copper.

[0104] from Figure 1 As can be seen, the solder achieves a good metallurgical bond with the ferrite metal layer and copper, and there are no defects such as pores and microcracks in the joint interface. The Sn solder and brazing filler metal form CuSn intermetallic compounds with Cu, thereby forming a connection and achieving a good bond between the ferrite and the copper substrate.

[0105] like Figure 3 As shown, in Comparative Example 1, the Cu layer is thinner, resulting in a thinner reaction layer between Sn and Cu, which reduces the bonding strength. In Comparative Example 2, the Cu layer is thicker, and the coefficient of thermal expansion of Cu is much greater than that of ferrite. Furthermore, the thicker Cu layer tends to form large-sized grains, generating greater stress with the ferrite, which leads to a decrease in the welding strength of the ferrite-copper substrate. The other embodiments, however, show good results.

[0106] Other notes: This patent involves many common processes. Welding two parts together requires surface treatment of the machined parts, assembly of the parts and solder, brazing, etc. These processes are identical; the differences lie in the material handling methods, process formulas, solder selection, and design. This patent focuses on the design and treatment of the metal layer, using Sn solder to achieve low-temperature welding for high-temperature use. Cleaning and polishing are considered common processing steps and are not subject to protection requirements.

[0107] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for soldering copper under metallization of a thin film of wave absorbing material, characterized in that, The method comprises the following steps: S1, pretreating the wave-absorbing material and the copper to be welded; S2, depositing an active metal layer on the surface of the wave-absorbing material to be welded by sputtering; S3, depositing a welding metal layer on the surface of the active metal layer; In the step S3, a welding metal layer is directly deposited on the surface of the active metal layer by plating, or a thin welding metal layer is first deposited, and then the welding metal layer is thickened by electroplating; S4, preparing solder; in the step S3, a solder sheet is used, or a 5-20 μm solder layer is deposited on the surface of the welding metal layer, or the solder is prepared in the form of solder paste; S5, assembling the wave-absorbing material with the deposited solder and the copper, or assembling the wave-absorbing material with the deposited welding metal layer, the solder sheet / solder paste and the copper, applying welding pressure, heating at a temperature increasing rate of 10 ℃ / min to 200 ℃ under a pressure less than one standard atmosphere, then keeping the temperature for 30 min, and then heating at a temperature increasing rate of 6-10 ℃ / min to 250-450 ℃ and keeping the temperature for 10-120 min; then decreasing the temperature to 200 ℃ at a temperature decreasing rate of 5-10 ℃ / min, and finally cooling to room temperature in the furnace, so as to realize the welding of the wave-absorbing material and the copper; The wave-absorbing material comprises ferrite ceramic and silicon carbide ceramic; The step S1 comprises the following steps: S11, polishing the wave-absorbing material by using sandpaper with mesh numbers of 400, 800, 1000 and 2000 in sequence; S12, polishing the copper by using sandpaper with mesh numbers of 400, 800, 1000 and 2000 in sequence; S13, ultrasonic cleaning the polished wave-absorbing material and the copper by using an alkaline solution; S14, ultrasonic cleaning the wave-absorbing material and the copper cleaned by deionized water for 30-60 min; S15, acid cleaning the copper cleaned by deionized water; S16, drying the wave-absorbing material and the copper cleaned in the environment of 100-150 ℃; In the step S2, the active metal layer is titanium, and the thickness of the active metal layer is 100-500 nm; In the step S3, the welding metal layer is copper or gold; In the step S3, a 3-50 μm welding metal layer is directly deposited on the surface of the active metal layer, or a 1-3 μm welding metal layer is first deposited, and then the welding metal layer is thickened to 3-50 μm by electroplating; In the step S3, the solder is tin.

2. The brazing method of claim 1, wherein the wave-absorbing material film is metalized with copper. The welding pressure is 0.6-2 N / cm in the step S5 2 .

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