A V / W wave band low-loss metal waveguide and a preparation method thereof

Abstract

The present application relates to the technical field of millimeter wave communication, and particularly relates to a V / W wave band low-loss metal waveguide and a preparation method thereof. The preparation method provided by the present application combines metal additive manufacturing, inner wall conductive metal deposition, super-smooth inner surface polishing and external single-point diamond turning technology. The waveguide manufactured by the composite process chain comprises an aluminum-magnesium (zirconium) alloy waveguide structure manufactured by laser beam melting additive manufacturing, a copper (silver) inner wall coating deposited by chemical reduction plating technology, an inner wall surface with a roughness of less than 50 nm Ra processed by abrasive flow machining, and a self-aligning flange with a flatness of less than 0.1 microns and a butt joint surface roughness of less than 20 nm Ra processed by super-precision machining. The present application improves the electrical performance, thermal interface consistency and assembly accuracy. The preparation method of the present application solves the problems of high insertion loss of the existing waveguide structure in high-frequency applications, high-cost mode coupling caused by large structural assembly errors, uncontrollable inner wall roughness and the like.

Description

Technical Field

[0001] This invention relates to the field of millimeter-wave communication technology, and in particular to a V / W band low-loss metallic waveguide and its fabrication method. Background Technology

[0002] Currently, the satellite communication field shows a clear trend towards the V-band (40-75 GHz) and W-band (75-110 GHz). This trend is driven not only by the increasing saturation of low-frequency resources, but also by the enormous potential of the V / W bands in terms of ultra-large bandwidth, high security, miniaturized terminals, and the integration of 6G terrestrial and satellite networks. With breakthroughs in core radio frequency technologies and the gradual improvement of international standards, high-frequency bands will gradually replace low-frequency bands as the core frequency bands for satellite internet and 6G terrestrial and satellite networks.

[0003] However, the leap in frequency places unprecedentedly stringent demands on fundamental microwave components, especially metallic waveguide structures, which serve as critical channels for signal transmission. In the V / W band, the skin depth of electromagnetic waves decreases dramatically (e.g., only about 0.12 μm at 110 GHz), and current is highly concentrated on the conductor surface, making conductor loss the primary source of insertion loss, accounting for up to 80% or more. This means that the microscopic roughness of the waveguide's inner surface has become a core bottleneck restricting performance: any minute unevenness will trigger significant electron scattering, leading to a surge in insertion loss, signal mode distortion, and a decrease in inter-component coupling efficiency. Therefore, achieving submicron-level inner surface smoothness (typically requiring Ra < 50 nm) and excellent inter-surface conductivity are necessary conditions for ensuring high-frequency transmission efficiency.

[0004] Existing metal waveguide manufacturing technologies face multiple challenges, making it difficult to simultaneously meet the aforementioned performance and structural complexity requirements.

[0005] 1. Traditional subtractive manufacturing methods have the following limitations: traditional processes such as CNC machining or extrusion molding supplemented by machining are difficult to achieve the required high surface finish in narrow waveguide cavities (e.g., 3.0×6.0 mm cross-section) with large aspect ratios and complex structures. Furthermore, the structures assembled from multiple parts have seams, which can introduce reflection loss and performance instability.

[0006] 2. The difficulty in balancing electrical performance and manufacturability in material selection: Ideal materials for high-performance waveguides need to balance high conductivity with good machinability. While structural materials such as high-strength titanium alloys (e.g., Ti6Al4V) possess excellent mechanical properties, their extremely low conductivity (typically <1.5% IACS, approximately 1.5% of pure copper) leads to a sharp increase in conductor loss under conditions of very shallow skin depth in the V / W band, failing to meet the RF performance requirements of low insertion loss. Aluminum alloys (e.g., AlSi7Mg0.6 or AlSi10Mg), suitable for processes such as laser powder bed fusion (LPBF), can achieve integrated molding of complex structures and possess moderate conductivity (approximately 35% IACS), but the presence of hard silicon phase particles in their solidification structure greatly increases the difficulty of precision polishing and finishing of the inner surface, easily causing defects such as dragging and peeling, making it difficult to obtain a consistent and ultra-smooth electromagnetic transmission interface. On the other hand, high-conductivity materials such as pure copper or silver are difficult to use directly for the precision molding of complex structures.

[0007] 3. Technical Bottlenecks in Additive Manufacturing and Surface Treatment: Although additive manufacturing technologies such as laser powder bed fusion (LPBF) can achieve one-piece molding of complex structures, eliminating assembly interfaces, the resulting structures have high internal surface roughness (Ra ≥ 5 µm) and micropores, directly leading to a sharp increase in high-frequency losses. Subsequent internal wall coating technologies (such as electroplating or electroless plating) used to improve conductivity face the industry challenge of controlling the uniformity of the coating within deep holes / slender cavities, resulting in problems such as inconsistent coating thickness and insufficient density, which seriously restrict the final performance.

[0008] In summary, existing manufacturing and surface treatment technologies cannot simultaneously meet the combined requirements of high-frequency waveguides for smooth inner wall finish, optimized conductivity, integrated structural design, and manufacturing feasibility and cost control. Therefore, a novel manufacturing process is urgently needed that combines the structural flexibility of additive manufacturing with composite material structures featuring inner walls coated with highly conductive metals, and addresses these bottlenecks through inner surface polishing and precision machining of the outer surface. Summary of the Invention

[0009] In view of the problems of high loss, poor consistency and manufacturing difficulty caused by the rough inner surface, insufficient conductivity, structural assembly error and traditional processing limitations in the waveguide structure in high frequency (especially V and W band) applications, as mentioned above, this invention provides a waveguide structure preparation method based on additive manufacturing and inner wall metallization treatment, supplemented by inner surface polishing and outer surface single-point diamond turning (SPDT), to achieve a waveguide component with both high conductivity and manufacturing feasibility.

[0010] The first aspect of this invention provides a V / W band low-loss metallic waveguide, comprising an integrally formed waveguide body, wherein an electromagnetic wave transmission channel is formed inside the waveguide body; an integrated flange interface is provided at the end of the waveguide body for connection with an external waveguide; the wall of the waveguide body has at least one gradient wall thickness region, the wall thickness of the gradient wall thickness region varying along the axial direction of the electromagnetic wave propagation channel; and the inner surface of the waveguide body has an ultra-smooth conductive metal layer with a surface roughness Ra < 0.1 μm.

[0011] In some embodiments of the present invention, the wall thickness of the gradually thickened wall region gradually changes from a first thickness at the waveguide opening to a second thickness at the cavity, wherein the first thickness is 0.4~0.8mm and the second thickness is 1.0~1.4mm.

[0012] In some embodiments of the present invention, the mating surface of the integrated flange interface is a conical self-aligning structure.

[0013] In some embodiments of the present invention, the ultra-smooth conductive metal layer is a copper layer or a silver layer with a thickness of 8-12 μm.

[0014] In some embodiments of the present invention, the conductivity of the ultra-smooth conductive layer is ≥90% IACS, and the porosity is <3 particles / cm. 2 .

[0015] In some embodiments of the present invention, the surface roughness Ra of the outer end face of the integrated flange interface is less than 20 nm, the flatness is less than 0.1 μm, and the cone angle accuracy is within ±0.001°.

[0016] In some embodiments of the present invention, the waveguide body is made of aluminum alloy.

[0017] A second aspect of the present invention provides a method for fabricating a low-loss metallic waveguide in the V / W band, comprising the following steps:

[0018] (1) A waveguide component is integrally formed by metal additive manufacturing technology. The waveguide component integrates an electromagnetic wave transmission channel, has a flange interface integrated at its end, and has at least one gradually changing wall thickness region in its wall.

[0019] (2) The waveguide component is subjected to densification heat treatment to eliminate internal defects and residual stress;

[0020] (3) The inner surface of the waveguide component is subjected to catalytic activation treatment, and a highly conductive metal layer is deposited on its inner wall by chemical plating.

[0021] (4) Polish the inner surface of the waveguide component with a highly conductive metal layer deposited on the inner wall to obtain an ultra-smooth conductive metal layer;

[0022] (5) The key assembly interface of the waveguide component after the inner surface is polished is precision machined by single-point diamond turning technology to obtain the waveguide product; the key assembly interface is a precision mechanical interface used to realize the alignment and connection of the waveguide with external devices.

[0023] In some embodiments of the present invention, in step (1), the at least one tapered wall thickness region is located at the end of the waveguide body and extends to the root region of the flange interface.

[0024] In some embodiments of the present invention, in step (1), the raw material for the metal additive manufacturing technology is selected from AlSi7Mg0.6 or modified AlCu4Mg0.5Zr0.2 alloy powder.

[0025] In some embodiments of the present invention, in step (1), the metal additive manufacturing technology is selected from laser beam melting technology or electron beam melting technology.

[0026] In some embodiments of the present invention, in step (2), the densification heat treatment is selected from hot isostatic pressing or T6 heat treatment.

[0027] In some embodiments of the present invention, step (3) further includes degreasing and cleaning and surface roughening treatment before the catalytic activation treatment.

[0028] In some embodiments of the present invention, step (3) includes sensitization treatment and activation treatment.

[0029] In some embodiments of the present invention, in step (3), the highly conductive metal layer is a copper layer or a silver layer.

[0030] In some embodiments of the present invention, in step (4), the polishing is selected from abrasive flow polishing, chemical mechanical polishing or electrolytic polishing.

[0031] In some embodiments of the present invention, in step (4), when the polishing is selected from abrasive flow polishing or chemical mechanical polishing, the waveguide with a highly conductive metal layer deposited on its inner wall is placed in an abrasive flow polishing fixture; preferably, the abrasive flow polishing fixture includes a sleeve for bearing the axial clamping pressure applied by an external device; a support member disposed in the inner cavity of the sleeve, the shape of which matches the outer contour of the waveguide component, for supporting and positioning the waveguide component to be processed; two conical end caps detachably and sealingly connected to both ends of the sleeve; the conical end caps are provided with conical flow channels for connecting the internal channel of the waveguide with the external abrasive flow supply device to achieve a smooth transition and uniform flow of the abrasive medium.

[0032] In some embodiments of the present invention, in step (4), the abrasive medium for abrasive flow polishing is a high-viscosity polishing medium containing diamond particles, alumina or silicon carbide particles, and the particle size of the diamond particles, alumina or silicon carbide particles is 0.5~1μm.

[0033] In some embodiments of the present invention, in step (4), the fluid pressure of the abrasive flow polishing is 5-7 MPa, the flow rate is 5-15 cm / min, the single processing time is 80-100 s, and the number of reciprocations is 10-18.

[0034] In some embodiments of the present invention, in step (4), the polishing liquid for chemical mechanical polishing is a polishing liquid containing colloidal silica particles and a corrosion inhibitor, wherein the particle size of the colloidal silica particles is 40~60nm.

[0035] In some embodiments of the present invention, in step (4), a flexible polymer brush head is connected to the chemical mechanical polishing circuit, the fluid pressure is 2~4MPa, and the processing time is 15~25min.

[0036] In some embodiments of the present invention, in step (4), the current density of the electropolishing is 0.2~0.3A / dm², the pulse period is 100ms, and the duty cycle is 1:5.

[0037] In some embodiments of the present invention, in step (4), after the polishing is completed, gradient pressure cleaning is performed under an abrasive flow polishing fixture.

[0038] In some embodiments of the present invention, in step (4), the surface roughness Ra of the ultra-smooth conductive metal layer is less than 50 nm.

[0039] In some embodiments of the present invention, in step (5), the key assembly interface includes a flange face and a sealing contact face.

[0040] In some embodiments of the present invention, in step (5), the tip radius of the single-point diamond turning tool is 0.1 mm and the feed rate is 4~6 mm / min.

[0041] In some embodiments of the present invention, in step (5), the surface roughness Ra of the key assembly interface after finishing is <20nm.

[0042] The third aspect of the present invention provides the application of the waveguide prepared by the above-described V / W band low-loss metallic waveguide or the above-described method for preparing the V / W band low-loss metallic waveguide in radar systems, millimeter-wave communication modules or high-frequency electronic test equipment.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] The waveguide provided by this invention has low insertion loss. Through high-conductivity metallization and ultra-smooth polishing of the inner wall, surface resistance loss and scattering at high frequencies (V and W) are effectively reduced. Loss is controlled through a dual-mechanism approach: firstly, conductivity is improved, with the silver layer conductivity > 6 × 10⁻⁶. 7 S / m can reduce ohmic losses; secondly, by reducing the pore density to less than 3 pores / cm 2 In addition, the inner wall surface morphology was optimized (50 nm Ra) to effectively suppress surface plasmon polaritrile scattering and meet the performance requirements of high-frequency waveguides.

[0045] The waveguide provided by this invention has a structural integrity, and AM manufacturing avoids the assembly errors of traditional multi-segment assembly to ensure electromagnetic consistency. The gradient wall thickness design achieved through additive manufacturing gradually changes from a waveguide aperture wall thickness of 0.6 mm to a cavity wall thickness of 1.2 mm, which increases the mechanical strength of the waveguide by 30% while controlling the weight of the device.

[0046] The waveguide external flange and assembly surface provided by this invention are machined by single-point diamond turning, with a surface roughness of less than 20 nm Ra. The external flange and mating surface are machined with ultra-precision machining, and the flange flatness is less than 0.1 μm. The conical self-aligning flange has a conical angle tolerance of ±0.001°. Compared with the error of 0.01 mm in traditional assembly, the assembly error of the conical self-aligning flange after SPDT machining is less than 0.003 mm, improving the reliability and thermal interface performance of the waveguide module and system integration, and increasing thermal contact efficiency by 50%.

[0047] The waveguide fabrication method provided by this invention has mass production capability and excellent consistency. The process steps are standardized and highly repeatable, making it suitable for micro radar, communication, measurement and other systems. It is also highly versatile and applicable to high-frequency waveguides of various shapes, including rectangular, circular, gradient, and complex 3D coupling structures. Attached Figure Description

[0048] Figure 1 This is a flowchart illustrating the fabrication process of a V / W band low-loss metallic waveguide according to an embodiment of the present invention.

[0049] Figure 2 This is a front view of a waveguide component integrally formed by laser beam melting (LBM) additive manufacturing technology according to an embodiment of the present invention.

[0050] Figure 3 This is a side view of a waveguide component integrally formed using laser beam melting (LBM) additive manufacturing technology according to an embodiment of the present invention.

[0051] Figure 4 These are surface roughness morphology images of the inner wall of the waveguide component after LBM additive manufacturing (A) and after chemical reduction plating of copper layer (B) in Embodiment 1 of the present invention.

[0052] Figure 5 This is a cross-sectional schematic diagram of the abrasive flow polishing (AFM) fixture used in Embodiment 1 of the present invention.

[0053] Figure 6 This is a schematic diagram of the integrated flange interface structure with a tapered self-aligning structure after being processed by single-point diamond turning according to the present invention.

[0054] Reference numerals: 100-waveguide body; 150-integrated flange interface; 200-self-aligning flange face; 210-conical self-aligning structure; 400-sleeve; 410-support; 420-conical end cap. Detailed Implementation

[0055] The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates the present invention of a V / W band low-loss metallic waveguide and its fabrication method.

[0056] The first aspect of this invention provides a low-loss metallic waveguide in the V / W band, with reference to... Figure 2 and Figure 3 The waveguide body 100 is integrally formed, and an electromagnetic wave transmission channel is formed inside the waveguide body 100. An integrated flange interface 150 is provided at the end of the waveguide body 100 for connection with an external waveguide. The wall of the waveguide body 100 has at least one gradient wall thickness region, and the wall thickness of the gradient wall thickness region varies along the axial direction of the electromagnetic wave propagation channel. The inner surface of the waveguide body 100 has an ultra-smooth conductive metal layer with a surface roughness Ra < 0.1 μm.

[0057] The waveguide body 100 of this invention includes an internal electromagnetic wave transmission channel and an integrated flange interface at the end, which avoids separate assembly and eliminates interface reflection. The design of the gradually changing wall thickness region reduces the weight of the waveguide while meeting the waveguide stiffness requirements.

[0058] In some embodiments of the present invention, the wall thickness of the gradient wall thickness region gradually changes from a first thickness at the waveguide aperture to a second thickness at the cavity, wherein the first thickness is 0.4~0.8 mm and the second thickness is 1.0~1.4 mm. In some specific embodiments of the present invention, the first thickness is 0.5 mm and the second thickness is 1.0 mm. In other specific embodiments of the present invention, the first thickness is 0.6 mm and the second thickness is 1.2 mm.

[0059] In some embodiments of the present invention, the mating surface of the integrated flange interface is a conical self-aligning structure, which can greatly improve assembly accuracy and efficiency, eliminate human error, reduce assembly force deformation, and reduce assembly error to less than 0.003 mm. It can also significantly reduce interface reflection and insertion loss, and enhance mechanical stability and anti-interference ability.

[0060] In some embodiments of the present invention, the ultra-smooth conductive metal layer is a copper layer or a silver layer, and its thickness is 8-12 μm, which can be 8~9 μm, 9~10 μm, 10~11 μm, or 11~12 μm.

[0061] In some embodiments of the present invention, the conductivity of the ultra-smooth conductive layer is ≥90% IACS, and the porosity is <3 particles / cm. 2 It has a scattering loss of less than 0.01 dB / cm, high conductivity and low porosity, and dual-mechanism loss control to meet the performance requirements of high-frequency waves.

[0062] In some embodiments of the present invention, the surface roughness Ra of the outer end face of the integrated flange interface is less than 20 nm, the flatness is less than 0.1 μm, and the cone angle accuracy is within ±0.001°. This maximizes the effective contact area, minimizes the contact resistance, ensures a consistent and stable current distribution, eliminates signal reflection and radiation leakage caused by gaps, guarantees the uniformity and reliability of the mechanical connection, achieves a precise "self-alignment" function, has zero positioning error, avoids "point contact" and "line contact", and achieves "surface contact".

[0063] In some embodiments of the present invention, the waveguide body is made of aluminum alloy, such as AlSi7Mg0.6 or modified AlCu4Mg0.5Zr0.2 alloy powder.

[0064] A second aspect of the present invention provides a method for fabricating a low-loss metallic waveguide in the V / W band, comprising the following steps:

[0065] (1) A waveguide component is integrally formed by metal additive manufacturing technology. The waveguide component integrates an electromagnetic wave transmission channel, has a flange interface integrated at its end, and has at least one gradually changing wall thickness region in its wall.

[0066] (2) The waveguide component is subjected to densification heat treatment to eliminate internal defects and residual stress;

[0067] (3) The inner surface of the waveguide component is subjected to catalytic activation treatment, and a highly conductive metal layer is deposited on its inner wall by chemical plating.

[0068] (4) Polish the inner surface of the waveguide component with a highly conductive metal layer deposited on the inner wall to obtain an ultra-smooth conductive metal layer;

[0069] (5) The key assembly interface of the waveguide component after the inner surface is polished is precision machined by single-point diamond turning technology to obtain the waveguide product; the key assembly interface is a precision mechanical interface used to realize the alignment and connection of the waveguide with external devices.

[0070] In this invention, the waveguide component is integrally formed, and the waveguide component integrates an electromagnetic wave transmission channel and an integrated flange interface at the end, which avoids traditional assembly errors and improves structural consistency.

[0071] In some embodiments of the present invention, in step (1), the at least one gradually thickened wall region is located at the end of the waveguide body and extends to the root region of the flange interface; for example, in a specific embodiment, the wall thickness of the waveguide cavity gradually changes from 0.6 mm to 1.2 mm, which can reduce the waveguide weight while meeting the waveguide rigidity requirements.

[0072] In some embodiments of the present invention, in step (1), the raw material of the metal additive manufacturing technology is selected from AlSi7Mg0.6 or modified AlCu4Mg0.5Zr0.2 alloy powder.

[0073] In some embodiments of the present invention, in step (1), the metal additive manufacturing technology is selected from laser beam melting (LBM) technology or electron beam melting (EBM) technology.

[0074] In some embodiments of the present invention, in step (2), the densification heat treatment is selected from hot isostatic pressing or T6 heat treatment, which can eliminate internal residual stress, improve metal density, and improve the consistency of subsequent surface treatment. Preferably, the conditions for hot isostatic pressing are: temperature of 520~540℃, pressure of 100~120MPa, holding time of 1~3h, inert gas protection; more preferably, temperature of 530℃, pressure of 110MPa, holding time of 2h, to eliminate porosity and achieve a density of 99.5% or higher. Preferably, the conditions for T6 heat treatment are: temperature of 500~520℃, holding time of 0.5~1.5h, inert gas protection, quenching, low-temperature aging treatment at 150~180℃, holding time of 5~7h, cooling; more preferably, temperature of 510℃, holding time of 1h, low-temperature aging treatment holding time of 6h, to increase the hardness to 120HV.

[0075] In some embodiments of the present invention, step (3) further includes degreasing and cleaning and surface roughening treatment before the catalytic activation treatment. The purpose of degreasing and cleaning is to remove residual powder and grease. The purpose of surface roughening is to etch the oxide layer and roughen the surface. Preferably, the cleaning medium for degreasing and cleaning is an alkaline degreasing solution at 55~65°C, the cleaning method is ultrasonic cleaning, and the cleaning time is 8~12 min. More preferably, the alkaline degreasing solution is a NaOH solution, the temperature of the alkaline degreasing solution is 60°C, and the cleaning time is 10 min. Preferably, the surface roughening treatment includes the following steps: immersing the waveguide component in an acidic activation solution and treating it at room temperature for 1~1.5 min. More preferably, the acidic activation solution is 9% v / v dilute hydrochloric acid or dilute nitric acid, and the treatment time is 1 min. The room temperature mentioned in the present invention refers to 15~25°C, the same below.

[0076] In some embodiments of the present invention, step (3) includes a sensitization treatment and an activation treatment to form a catalytic layer on the inner wall of the waveguide that can be used for electroless copper or silver plating, providing uniform nucleation conditions for subsequent high-conductivity plating. Preferably, the sensitization solution for the sensitization treatment comprises SnCl2 with a concentration of 10-20 g / L and hydrochloric acid with a concentration of 8-16 g / L, and the treatment method is immersion at room temperature for 3-8 min. Preferably, the activation treatment involves immersing the sensitized waveguide component in a noble metal salt activation solution, depositing noble metal nanoparticles on the inner surface of the waveguide through a redox reaction to form catalytic active centers for electroless plating (density > 10). 8 pcs / cm 2 In some embodiments of the present invention, the noble metal salt activation solution is a palladium salt solution, and the noble metal nanoparticles are palladium nanoparticles; in other embodiments of the present invention, the noble metal salt activation solution is a silver ammonia complex solution, and the noble metal nanoparticles are silver nanoparticles.

[0077] The electroless plating method described in this invention can employ any conventional process known in the art for depositing a conductive metal layer on a non-metallic surface, including but not limited to the electroless copper or electroless silver plating processes described in the following embodiments. The key lies in forming a dense, uniform, and highly conductive metal layer on the inner wall of the waveguide through the electroless plating process.

[0078] In some embodiments of the present invention, a chemical copper plating process is employed, using CuSO4 as the main salt in the plating solution. The plating solution temperature is 50±2℃; the pH value is 12~13; the plating thickness is controlled at 8-12 µm; and the porosity is <3 cells / cm². 2 The resistivity of the resulting copper layer is ≤2.0 μΩ·cm.

[0079] In some embodiments of the present invention, optionally, a chemical silver plating process is employed, using a plating bath with AgNO3 as the main salt, a plating bath temperature of 60±2℃, a pH value of 8.5~9.5, a coating thickness controlled at 8-12µm, and a porosity of <3 cells / cm. 2 The resistivity of the resulting silver layer is ≤1.8 μΩ·cm.

[0080] In some embodiments of the present invention, in step (3), the highly conductive metal layer is a copper layer or a silver layer with a conductivity ≥90% IACS, which significantly reduces the roughness of the inner wall of the additively manufactured waveguide and ensures that electromagnetic transmission loss in the high-frequency band is minimized.

[0081] In some embodiments of the present invention, in step (4), the inner surface of the waveguide with the deposited highly conductive metal layer is polished to obtain an ultra-smooth conductive metal layer. In the present invention, the inner surface of the waveguide with the deposited highly conductive metal layer is subjected to directional abrasive flow machining (AFM), chemical mechanical polishing (CMP), or electrolytic polishing to further optimize the surface roughness of the inner wall from 4.0 µm (RMS) of the chemically plated metal coating to Ra < 50 nm (RMS), effectively reducing the conductor loss caused by the skin effect.

[0082] In some embodiments of the present invention, in step (4), when the polishing is selected from abrasive flow polishing or chemical mechanical polishing, the waveguide with a highly conductive metal layer deposited on the inner wall is placed in the abrasive flow polishing fixture; preferably, the abrasive flow polishing fixture includes a sleeve 400 for bearing the axial clamping pressure applied by the external equipment, avoiding the pressure from acting directly on the waveguide, and preventing the thin-walled waveguide from buckling or deforming; a support member 410 is disposed in the inner cavity of the sleeve 400, the shape of which matches the outer contour of the waveguide component, for supporting and positioning the waveguide component to be processed; two conical end caps 420 are detachably sealed to both ends of the sleeve 400; the conical end caps 420 are provided with conical flow channels for connecting the internal channel of the waveguide with the external abrasive flow supply equipment to achieve a smooth transition and uniform flow of the abrasive medium.

[0083] In some embodiments of the present invention, in step (4), the abrasive medium for the abrasive flow polishing is a high-viscosity polishing medium containing diamond particles, alumina, or silicon carbide particles, wherein the particle size of the diamond particles, alumina, or silicon carbide particles is 0.5~1μm. In some embodiments of the present invention, in step (4), the fluid pressure for the abrasive flow polishing is 5~7MPa, the flow rate is 5~15 cm / min, the single processing time is 80~100s, and the number of reciprocations is greater than 10, preferably 10~18.

[0084] In some embodiments of the present invention, in step (4), the polishing slurry for chemical mechanical polishing is a polishing slurry containing colloidal silica particles and a corrosion inhibitor. The particle size of the colloidal silica particles is 40-60 nm, which can be 40-50 nm or 50-60 nm, preferably 50 nm. In some embodiments of the present invention, in step (4), a flexible polymer brush head is connected to the chemical mechanical polishing circuit (to prevent polishing dead angles), the fluid pressure is 2-4 MPa, which can be 2-3 MPa or 3-4 MPa, and the processing time is 15-25 min, which can be 15-20 min or 20-25 min, preferably 20 min. Preferably, the corrosion inhibitor is selected from 0.1 wt% benzotriazole (BTA) to inhibit chemical corrosion of pure metals.

[0085] In some embodiments of the present invention, in step (4), after the abrasive flow polishing or chemical mechanical polishing is completed, gradient pressure cleaning is performed under the abrasive flow polishing fixture; preferably, stage 1: high-pressure deionized water rinsing (1MPa, Reynolds number > 4000), stage 2: supercritical CO2 drying (critical point 31℃ / 7.4MPa) to eliminate capillary adsorption. The residual polishing media after cleaning is ≤0.1 particles / cm³. 2 .

[0086] In some embodiments of the present invention, in step (4), the current density of the electropolishing is 0.2~0.4 A / dm. 2 It can be 0.2~0.3A / dm 2 It can also be 0.3~0.4A / dm 2 Preferably 0.3A / dm 2 The pulse period is 100ms, the duty cycle is 1:5, and the duration is 5~10min, which can be 5~6min, 6~7min, 7~8min, 8~9min, or 9~10min. The electropolishing process further smooths out surface micro-protrusions.

[0087] In some embodiments of the present invention, in step (4), the surface roughness Ra of the ultra-smooth conductive metal layer is less than 50 nm, which effectively reduces the conductor loss caused by the skin effect.

[0088] In some embodiments of the present invention, in step (5), the key assembly interface includes a flange face and a sealing contact face, which are precisely finished using single-point diamond turning (SPDT) technology to improve the contact accuracy, thermal conductivity and mechanical strength when the waveguide is connected to the external system.

[0089] In some embodiments of the present invention, in step (5), the tip radius of the single-point diamond turning tool is 0.1 mm, and the feed rate is 4~6 mm / min, which can be 4~5 mm / min or 5~6 mm / min, preferably 5 mm / min.

[0090] In some embodiments of the present invention, in step (5), reference is made to... Figure 6 The surface roughness of the key assembly interface after precision machining is Ra<20nm. The integrated flange interface 10 includes a self-aligning flange surface 200. Compared with the assembly error of traditional processes, the self-aligning flange surface 200 after SPDT machining has a conical self-aligning structure 210, which significantly reduces the assembly error and significantly improves the reliability and thermal interface performance of the waveguide module and system integration.

[0091] The third aspect of the present invention provides the application of the waveguide prepared by the above-described V / W band low-loss metallic waveguide or the above-described method for preparing the V / W band low-loss metallic waveguide in radar systems, millimeter-wave communication modules or high-frequency electronic test equipment.

[0092] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention.

[0093] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, this invention can be implemented using any prior art methods, apparatus, and materials similar to or equivalent to those described in the embodiments of this invention, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention.

[0094] Example 1

[0095] In this embodiment, the waveguide cavity of the V / W band low-loss metallic waveguide features a gradually varying wall thickness design, transitioning from a waveguide aperture wall thickness of 0.5 mm to a cavity wall thickness of 1.0 mm.

[0096] The fabrication method of the above-mentioned V / W band low-loss metallic waveguide is referred to Figure 1 This includes the following steps:

[0097] (1) Design a three-dimensional waveguide model, import the three-dimensional model into the printer slicing software, and set the layer thickness to 30μm; refer to Figure 2 Using AlSi7Mg0.6 alloy powder as the printing material, waveguide components (a one-piece waveguide body 100, reference) were printed on a support plate using laser beam melting (LBM) additive manufacturing. Figures 2-3 (Including the electromagnetic wave transmission channel and the integrated flange interface 150 at the end and the gradually changing wall thickness zone), with an error of <±5μm.

[0098] (2) The waveguide components after additive manufacturing are subjected to hot isostatic pressing (HIP) treatment with the following parameters: 530℃, 110MPa, heat preservation for 2 hours, and inert gas protection, thereby reducing porosity, improving structural consistency and thermal conductivity, and eliminating residual stress to prevent SPDT processing deformation.

[0099] (3) Palladium-catalyzed electroless copper plating:

[0100] S1. Pretreatment: First, degreasing and cleaning are performed. The waveguide component after HIP treatment is placed in an alkaline degreasing solution (50 g / L NaOH solution) at 60℃ and ultrasonically cleaned for 10 min to remove residual powder and grease. Then, it is repeatedly rinsed with deionized water until neutral. Next, surface roughening treatment is performed. The rinsed waveguide component is immersed in a 10% v / v dilute hydrochloric acid solution and treated at room temperature for 1 min to etch and remove the surface oxide layer and slightly roughen the surface, increase the specific surface area, and improve the adsorption of subsequent sensitizers. After treatment, it is thoroughly rinsed with deionized water.

[0101] S2. Sensitization Treatment: The surface-roughened waveguide component is immersed in a sensitization solution (the sensitization solution formula is: SnCl2 concentration of 15 g / L, 36wt% concentrated hydrochloric acid volume concentration of 30 ml / L), and treated for 5 minutes at room temperature with magnetic stirring, so that Sn... 2+ After sensitization, the ions are fully adsorbed onto the inner surface of the waveguide component. Then, the surface is thoroughly rinsed with deionized water to ensure complete removal of any residual Cl. - Ions are removed to prevent them from contaminating the subsequent activation solution.

[0102] S3. Activation Treatment: Immerse the sensitized waveguide component in an activation solution (the activation solution is a PdCl2 hydrochloric acid solution, where the PdCl2 concentration is 0.5 g / L and the volume concentration of 36wt% concentrated hydrochloric acid is 20 ml / L) and treat it at room temperature for 3 min (a redox reaction occurs: Sn...). 2+ +Pd 2+ →Sn 4+ +Pd↓), the resulting palladium (Pd) nanoparticles are uniformly deposited on the inner surface of the waveguide, forming densely distributed catalytic active centers, and then rinsed with deionized water.

[0103] S4. Electroless Copper Plating: The activated waveguide component is immediately transferred to an alkaline electroless copper plating solution. The main components of the alkaline electroless copper plating solution include: copper sulfate 10 g / L, EDTA-2Na 40 g / L, formaldehyde (37% concentration) 15 ml / L, pH=12.5. The plating solution is heated to 50±2℃ and maintained. A vacuum-assisted injection method is used: first, a vacuum is drawn into the waveguide cavity, and then the plating solution is drawn in and fills the entire inner cavity using negative pressure, ensuring that the plating solution is in full contact with all catalytic surfaces (to cause the Cu deposition reaction). 2+ +2HCHO+4OH - →Cu↓+ 2HCOO - (+H2↑+2H2O), deposition time 30 min, copper ions are reduced and deposited on the inner surface to form a dense, uniform, and well-bonded copper coating with a thickness of 9 μm and a porosity of <3 ions / cm. 2 . Figure 4 Showing LBM additive manufacturing after (e.g.) Figure 4 (as shown in Figure A) and after chemical reduction plating to deposit a copper plating layer (as shown in Figure A) Figure 4 (As shown in Figure B) Comparison of the surface roughness of the inner wall of the waveguide component. The surface roughness of the inner wall after the copper plating is reduced from 15µm after additive manufacturing to 4.0µm.

[0104] Inner surface polishing: Reference Figure 5 The waveguide, after copper plating, is carefully placed on the internal support 410 of the workpiece abrasive flow polishing (AFM) fixture, and then the entire assembly is installed into the rigid sleeve 400. The upper and lower conical end caps 420 are tightened to ensure a secure fixture assembly and the formation of a sealed cavity. The assembled fixture is then mounted on a dual-cylinder AFM machine, using a high-viscosity polishing medium containing diamond particles (50 wt.%) as the abrasive medium. The main process parameters are set as follows: system fluid pressure: 6 MPa; abrasive medium flow velocity in the workpiece channel: 5-15 cm / min; single reciprocating stroke time: 90 s. The AFM machine is started, and the two hydraulic cylinders alternately push the abrasive medium under computer control. The medium is forced through the internal channel of the waveguide component under high pressure, and the abrasive particles perform micro-cutting and rolling on the inner surface of the channel. The above polishing process is performed for a total of 15 reciprocating cycles to ensure that the inner surface is uniformly and consistently processed. After polishing, a gradient pressure cleaning process is performed under an AFM fixture: Stage 1: High-pressure deionized water rinsing (1 MPa, Reynolds number > 4000); Stage 2: Supercritical CO2 drying (critical point 31℃ / 7.4 MPa) to eliminate capillary adsorption. After cleaning, the residual polishing media is ≤0.1 particles / cm³. 2 , Ra<50nm.

[0105] External finishing: Key external mounting surfaces, flanges, and positioning holes are machined using single-point diamond turning (SPDT) for ultra-precision machining to obtain waveguide products with Ra < 20nm. Key process parameters: tool tip radius 0.1 mm, feed rate 5 mm / min. Surface finish Ra < 20nm (RMS); flatness λ / 10 (λ = 632nm); taper angle tolerance ±0.001. Figure 6 The integrated flange interface 150 includes a self-aligning flange face 200, which has a tapered self-aligning structure 210 after being processed by SPDT. Compared with the traditional assembly error of 0.01 mm, the integrated flange interface 150 with the tapered self-aligning structure 210 has an assembly error of less than 0.003 mm, which significantly improves the reliability and thermal interface performance of the waveguide module and system integration, and increases the thermal contact efficiency by 50%.

[0106] Example 2

[0107] In this embodiment, the waveguide cavity of the V / W band low-loss metallic waveguide features a gradually varying wall thickness design, transitioning from a waveguide aperture wall thickness of 0.5 mm to a cavity wall thickness of 1.0 mm.

[0108] The fabrication method of the above-mentioned V / W band low-loss metallic waveguide is referred to Figure 1 This includes the following steps:

[0109] (1) Design a three-dimensional waveguide model, import the three-dimensional model into the printer slicing software, and set the layer thickness to 40μm; refer to Figure 2 Using modified AlCu4Mg0.5Zr0.2 alloy powder as the printing material, waveguide components (an integrally formed waveguide body 100, including an electromagnetic wave transmission channel and an integrated flange interface 150 at the end and a gradually changing wall thickness area) are printed on a support plate using electron beam melting (EBM) additive manufacturing method, with an error of <±5μm.

[0110] (2) The waveguide component after additive manufacturing is subjected to T6 heat treatment with the following parameters: placed in an air circulation furnace, the temperature is set at 510℃, the heating rate is 80℃ / hour, the holding time is 1 hour, inert gas protection is used, after the holding time is completed, the component is quenched and transferred to an aging furnace, where it is subjected to low-temperature aging treatment in the range of 150~180℃, and held for 6 hours. After that, it is cooled with the furnace to reduce porosity, improve structural consistency and thermal conductivity, and eliminate residual stress to prevent deformation during SPDT processing.

[0111] (3) Silver-catalyzed electroless silver plating:

[0112] S1. Pretreatment: First, degreasing and cleaning are performed. The waveguide component after T6 heat treatment is placed in an alkaline degreasing solution (50 g / L NaOH solution) at 60℃ and ultrasonically cleaned for 10 minutes to thoroughly remove residual metal powder, grease, and contaminants from the inner cavity. Then, it is repeatedly rinsed with deionized water until neutral. Next, surface roughening treatment is performed. The rinsed waveguide blank is immersed in a 10% (v / v) dilute hydrochloric acid solution and treated at room temperature for 1 minute to etch away the surface oxide layer and slightly roughen the surface, increasing the specific surface area and thus significantly improving the adsorption capacity of the subsequent sensitizer. After treatment, it is thoroughly rinsed with deionized water.

[0113] S2. Sensitization Treatment: Immerse the surface-roughened component in a sensitization solution (the sensitization solution formula is: SnCl2 concentration of 10 g / L, 36wt% concentrated hydrochloric acid volume concentration of 10 ml / L). At room temperature, continuously stir the solution with a magnetic stirrer for 4 minutes to allow SnCl2 to sensitize. 2+ After the ions are fully adsorbed onto the inner surface of the component, and the sensitization is completed, it is thoroughly rinsed with deionized water to ensure that residual chloride ions are completely removed and to prevent them from contaminating the subsequent activation solution.

[0114] S3. Activation Treatment: Immerse the sensitized component in the activation solution (silver ammonia solution, AgNO3 concentration of 5 g / L, with ammonia added until the solution becomes a clear and transparent silver ammonia complex solution) and treat at room temperature for 5 min (reaction occurs: Sn...). 2+ +2[Ag(NH3)2] + →Sn 4+ The reaction (+2Ag↓+4NH3) produces nano-silver particles that adhere tightly to the inner surface of the waveguide, forming an active center for chemical silver plating. After activation, the nano-silver particles are gently rinsed with deionized water.

[0115] S4. Electroless Silver Plating: Immediately transfer the activated waveguide component into the electroless silver plating solution. The main components of the electroless silver plating solution include: 5g / L silver nitrate, ammonia (appropriate amount, to maintain solution clarity), 10ml / L hydrazine hydrate, pH=9.0; heat the plating solution to 60±2℃ and maintain it. Use a vacuum-assisted injection method, first evacuate the waveguide cavity, then use negative pressure to draw in the plating solution and fill the entire inner cavity, ensuring that the plating solution is in full contact with all catalytic surfaces (causing the deposition reaction 4[Ag(NH3)2)). + +N₂H₄+4OH - →4Ag↓+N2↑+8NH3+4H2O), deposition time 50 min. Under the initiation of the nano-silver catalytic center, silver ions are reduced to metallic silver by hydrazine and deposited layer by layer on the catalytic surface. The coating thickness is 12 μm and the porosity is <3 ions / cm. 2 .

[0116] (4) Inner surface polishing: Refer to Figure 5 The waveguide, after silver plating, is carefully placed on the internal support 410 of the abrasive flow polishing (AFM) fixture and then fitted into a rigid sleeve 400. This effectively resists the fluid pressure and circumferential stress generated during polishing, preventing deformation or micro-bending of the thin-walled waveguide. Chemical mechanical polishing is performed using a polishing slurry containing colloidal silica particles (50 nm in diameter), 0.1 wt% benzotriazole (BTA), and pH=10. The prepared polishing slurry is added to the supply system, and a flexible polymer brush head is connected to the slurry circuit. This brush head can flow with the fluid through the waveguide cavity. The equipment is started, and the polishing slurry and brush head are pushed to circulate back and forth in the waveguide cavity at a relatively low pressure (3 MPa). The processing time is approximately 20 minutes. After polishing, gradient pressure cleaning is performed under the AFM fixture: Stage 1: High-pressure deionized water rinsing (1 MPa, Reynolds number > 4000); Stage 2: Supercritical CO2 drying (critical point 31℃ / 7.4 MPa) to eliminate capillary adsorption. Polishing media residue after cleaning ≤0.1 particles / cm 2 , Ra<50nm.

[0117] (5) External finishing: Key external mounting surfaces, flanges, and positioning holes are precision machined using single-point diamond turning (SPDT) to obtain waveguide products with Ra < 20nm. Main process parameters: tool tip radius 0.1 mm, feed rate 5 mm / min; surface finish Ra < 20nm (RMS); flatness λ / 10 (λ = 632nm); taper angle tolerance ±0.001. Assembly error is less than 0.003 mm, which significantly improves the reliability and thermal interface performance of waveguide module and system integration compared to the traditional assembly error of 0.01 mm, and increases thermal contact efficiency by 50%.

[0118] Comparative Example 1

[0119] Except for not performing hot isostatic pressing (HIP) on the waveguide component after additive manufacturing, the rest is the same as in Example 1.

[0120] Comparative Example 2

[0121] Except for not performing sensitization and activation treatments on the waveguide components after surface roughening, the rest is the same as in Example 1.

[0122] Comparative Example 3

[0123] Except for not polishing the inner surface of the waveguide after the silver plating was deposited, the rest is the same as in Example 1.

[0124] Comparative Example 4

[0125] Except for not performing external finishing on the waveguide after the inner surface is polished, the rest is the same as in Example 1.

[0126] The waveguides prepared in Examples 1-2 and Comparative Examples 1-4 were subjected to coating adhesion and electrical property tests. Coating adhesion was tested using a pull-off test (standard based on ASTM D4541 / ISO 4624). Electrical conductivity was tested using a four-probe test to measure coating resistivity. Electrical properties were tested using a vector network analyzer (VNA) to measure S-parameters. The test results are shown in Table 1 below.

[0127] Table 1. Performance comparison results of waveguides fabricated in the embodiments and comparative examples.

[0128]

[0129] The waveguide manufactured in Example 1 has an inner wall polished by AFM abrasive flow polishing, resulting in Ra < 50 nm. The flange surface is SPDT machined, resulting in Ra < 20 nm. The coating conductivity is ≥ 90% IACS. It operates in the 92~96 GHz frequency band. Compared to conventional processes with insertion loss > 0.3 dB / cm, the waveguide manufactured in Example 1 has an insertion loss (S21) of less than 0.1 dB / cm and a return loss (S11) better than -15 dB in the same operating frequency band. Comparative Example 1 has a high residual porosity in the inner wall of the waveguide (18 porosities / cm). 2 In Comparative Example 2, the coating underwent localized peeling. SPDT machining increased flange surface deformation error (flatness > 5 μm). Micropores induced electromagnetic scattering, leading to an increase in insertion loss to -0.15~0.25 dB / cm. This may be due to the lack of HIP treatment, resulting in retained powder metallurgy porosity, high stress, and impaired conductivity and mechanical deformation control. In Comparative Example 2, the lack of SnCl2 / PdCl2 treatment resulted in uneven nucleation on the non-catalytic surface, leading to a discontinuous and unevenly distributed electroless coating (3-15 μm). This resulted in decreased coating adhesion and a peel force < 5 N / cm. 2 The distorted surface current distribution leads to unstable insertion loss, fluctuating between -0.2 and -0.4 dB / cm. This may be due to poor initial film formation caused by the lack of catalytic seeding, making it difficult for the coating to cover the deep channel structure. Comparative Example 3, without AFM or CMP polishing, maintains an inner wall coating roughness of Ra~3-5 μm. The S21 insertion loss rises to -0.3 dB / cm, and the S11 reflection characteristics deteriorate to >-10 dB. This is because the rough surface induces strong surface current scattering and modal deformation, resulting in significant high-frequency performance degradation. Comparative Example 4 has a flange flatness >10 μm, poor surface contact, a 40% decrease in thermal contact efficiency, interface reflection loss, causing high-frequency modal distortion, and pre-tightening of screws easily causes waveguide misalignment. The flange roughness Ra=120nm, mechanical vibration causes signal phase noise, and the insertion loss is -0.18 dB / cm. Furthermore, batch consistency is poor, and contact resistance and mechanical misalignment significantly affect electrical performance, indicating that SPDT is crucial for assembly surface accuracy.

[0130] As shown in Table 1, hot isostatic pressing, sensitization and activation, inner surface polishing and outer finishing are all key steps in manufacturing waveguides with low insertion loss (S21), high return loss (S11), high coating reliability and excellent mechanical interface performance.

[0131] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. In the above embodiments, the descriptions of each embodiment have different emphases; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A V / W band low-loss metallic waveguide, characterized in that, The waveguide includes an integrally formed waveguide body, the interior of which forms an electromagnetic wave transmission channel; the ends of the waveguide body are provided with integrated flange interfaces for connection with external waveguides; the wall of the waveguide body has at least one gradient wall thickness region, the wall thickness of which varies along the axial direction of the electromagnetic wave propagation channel; the inner surface of the waveguide body has an ultra-smooth conductive metal layer with a surface roughness Ra < 0.1 μm.

2. The V / W band low-loss metallic waveguide as described in claim 1, characterized in that, Includes one or more of the following characteristics: (a) The wall thickness of the gradually thickened wall region gradually changes from the first thickness of the waveguide opening to the second thickness of the cavity, wherein the first thickness is 0.4~0.8mm and the second thickness is 1.0~1.4mm; (b) The mating surface of the integrated flange interface is a conical self-aligning structure; (c) The ultra-smooth conductive metal layer is a copper layer or a silver layer with a thickness of 8-12 μm; (d) The conductivity of the ultra-smooth conductive metal layer is ≥90% IACS, and the porosity is <3 particles / cm²; (e) The surface roughness Ra of the outer end face of the integrated flange interface is less than 20 nm, the flatness is less than 0.1 μm, and the cone angle accuracy is within ±0.001°; (f) The waveguide body is made of aluminum alloy.

3. The application of the V / W band low-loss metallic waveguide as described in any one of claims 1 to 2 in the fabrication of radar systems, millimeter-wave communication modules, or high-frequency electronic test equipment.

4. A method for fabricating a low-loss metallic waveguide in the V / W band, characterized in that, Includes the following steps: (1) A waveguide component is integrally formed by metal additive manufacturing technology. The waveguide component integrates an electromagnetic wave transmission channel, has a flange interface integrated at its end, and has at least one gradually changing wall thickness region in its wall. (2) The waveguide component is subjected to densification heat treatment to eliminate internal defects and residual stress; the densification heat treatment is selected from hot isostatic pressing or T6 heat treatment; (3) The inner surface of the waveguide component is subjected to catalytic activation treatment, and a highly conductive metal layer is deposited on its inner wall by chemical plating. (4) Polish the inner surface of the waveguide component with the high conductivity metal layer deposited on the inner wall to obtain an ultra-smooth conductive metal layer; the polishing is selected from abrasive flow polishing, chemical mechanical polishing or electrolytic polishing; the surface roughness Ra of the ultra-smooth conductive metal layer is <0.1μm; (5) The key assembly interface of the waveguide component after the inner surface is polished is precision machined by single-point diamond turning technology to obtain the waveguide product; the key assembly interface is a precision mechanical interface used to realize the alignment and connection of the waveguide with external devices.

5. The method for fabricating a V / W band low-loss metallic waveguide as described in claim 4, characterized in that, Includes one or more of the following characteristics: (a) In step (1), the at least one tapered wall thickness region is located at the end of the waveguide body and extends to the root region of the flange interface; (b) In step (1), the raw material for the metal additive manufacturing technology is selected from AlSi7Mg0.6 or modified AlCu4Mg0.5Zr0.2 alloy powder; (c) In step (1), the metal additive manufacturing technology is selected from laser beam melting technology or electron beam melting technology.

6. The method for fabricating a V / W band low-loss metallic waveguide as described in claim 4, characterized in that, Includes one or more of the following characteristics: (d1) The conditions for hot isostatic pressing are: temperature 520~540℃, pressure 100~120MPa, holding time 1~3h, and inert gas protection. (d2) The conditions for the T6 heat treatment are: temperature of 500~520℃, holding time of 0.5~1.5h, inert gas protection, quenching, low temperature aging treatment at 150~180℃, holding time of 5~7h, and cooling.

7. The method for fabricating a V / W band low-loss metallic waveguide as described in claim 4, characterized in that, Includes one or more of the following characteristics: (a) In step (3), the catalytic activation treatment also includes degreasing and cleaning and surface roughening treatment before the catalytic activation treatment; (b) In step (3), the catalytic activation treatment includes sensitization treatment and activation treatment; (c) In step (3), the highly conductive metal layer is a copper layer or a silver layer.

8. The method for fabricating a V / W band low-loss metallic waveguide as described in claim 7, characterized in that, Includes one or more of the following characteristics: (a1) The cleaning medium for the degreasing cleaning is an alkaline degreasing solution at 55~65℃, the cleaning method is ultrasonic cleaning, and the cleaning time is 8~12min; (a2) The surface roughening treatment includes the following steps: immersing the waveguide component in an acidic activation solution and treating it at room temperature for 1~1.5 min; (b1) The sensitizing solution components of the sensitization treatment include SnCl2 with a concentration of 10~20 g / L and hydrochloric acid with a concentration of 8~16 g / L, and the treatment method is immersion at room temperature for 3~8 min; (b2) The activation process involves immersing the sensitized waveguide component in a noble metal salt activation solution and depositing noble metal nanoparticles on the inner surface of the waveguide through a redox reaction to form a chemical plating catalytic active center.

9. The method for fabricating a V / W band low-loss metallic waveguide as described in claim 7, characterized in that, Step (4) includes one or more of the following features: (a) When the polishing is selected from abrasive flow polishing or chemical mechanical polishing, the waveguide with a highly conductive metal layer deposited on the inner wall is placed in the abrasive flow polishing fixture; the abrasive flow polishing fixture includes a sleeve (400) for bearing the axial clamping pressure applied by the external equipment; a support (410) is disposed in the inner cavity of the sleeve (400), the shape of which matches the outer contour of the waveguide component, for supporting and positioning the waveguide component to be processed; two conical end caps (420) are detachably and sealed to both ends of the sleeve (400); the conical end caps (420) are provided with conical flow channels for connecting the internal channel of the waveguide with the external abrasive flow supply equipment to achieve a smooth transition and uniform flow of the abrasive medium; (b) The abrasive medium for the abrasive flow polishing is a high-viscosity polishing medium containing diamond particles, alumina or silicon carbide particles, wherein the particle size of the diamond particles, alumina or silicon carbide particles is 0.5~1μm; (c) The fluid pressure of the abrasive flow polishing is 5~7MPa, the flow rate is 5~15 cm / min, the single processing time is 80~100s, and the number of reciprocating cycles is 10~18. (d) The polishing slurry for chemical mechanical polishing is a polishing slurry containing colloidal silica particles and a corrosion inhibitor, wherein the particle size of the colloidal silica particles is 40~60nm; (e) A flexible polymer brush head is connected to the chemical mechanical polishing circuit, the fluid pressure is 2~4MPa, and the processing time is 15~25min; (f) The current density of the electropolishing is 0.2~0.4A / dm², the pulse period is 100ms, the duty cycle is 1:5, and the electrolysis time is 5~10min; (g) After the polishing is completed, gradient pressure cleaning is performed under the abrasive flow polishing fixture; (h) The surface roughness Ra of the ultra-smooth conductive metal layer is less than 50 nm.

10. The method for fabricating a V / W band low-loss metallic waveguide as described in claim 4, characterized in that, Step (5) includes one or more of the following features: (a) The key assembly interface includes the flange face and the sealing contact surface; (b) The single-point diamond turning tool tip radius is 0.1 mm and the feed rate is 4~6 mm / min; (c) The surface roughness Ra of the key assembly interface after finishing is less than 20 nm.

11. The waveguide fabricated by the method described in any one of claims 4 to 10 for the V / W band low-loss metallic waveguide is used in the fabrication of radar systems, millimeter-wave communication modules, or high-frequency electronic test equipment.

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