A multilayer radio frequency cable and a method of manufacturing the same
By designing and precisely manufacturing multilayer RF cables, the problems of high signal loss, insufficient shielding effectiveness, and poor mechanical properties in existing RF cables at high frequencies have been solved, achieving low loss, stable signal transmission, and long lifespan.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHUZHOURUNHANDTECHNOLOGY CO LTD
- Filing Date
- 2026-05-15
- Publication Date
- 2026-06-26
AI Technical Summary
Existing radio frequency cables suffer from high signal loss, insufficient shielding effectiveness, poor mechanical properties, and imperfect manufacturing processes in the high-frequency band, making it difficult to meet the needs of 5G/6G communication and high-end electronic equipment.
It adopts a multi-layer structure design, including a conductor core layer, a double-layer composite insulation layer, a multi-layer composite shielding layer, and a modified protective layer. It is prepared through processes such as precision stranding, extrusion molding, and wrapping braiding to ensure that each layer is tightly bonded and controlled with high precision.
Significantly reduces insertion loss and return loss, improves shielding effectiveness and mechanical reliability, adapts to complex environments, and meets the requirements for high-frequency signal transmission stability and long lifespan.
Smart Images
Figure CN122291908A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of radio frequency transmission technology, specifically to a multilayer radio frequency cable and its manufacturing method. Background Technology
[0002] As the core physical carrier for high-frequency signal transmission, the technical performance of radio frequency (RF) cables directly determines the signal integrity and operational stability of communication systems and electronic equipment. With the large-scale deployment of 5G and the accelerated pre-research of 6G, the frequency of RF signal transmission is constantly increasing, placing more stringent demands on the high-frequency performance, anti-interference capabilities, mechanical reliability, and environmental adaptability of RF cables. Currently, the insertion loss of domestically produced RF cables in the 3.5GHz band has been controlled below 0.12dB / m, approaching the international advanced level. However, there is still a performance gap of 0.8–1.2dB / m in the millimeter-wave band above 26GHz, mainly limited by the maturity of high-purity conductors, low-dielectric-constant composite media, and precision manufacturing processes.
[0003] Existing RF cables mostly employ single-layer or double-layer structures, which suffer from the following technical defects: 1) High signal loss: Traditional RF cables often use ordinary copper conductors, resulting in a significant skin effect, especially at high frequencies. This leads to a reduction in the effective conductive cross-sectional area and an increase in AC resistance, resulting in a significant increase in insertion loss. Simultaneously, the insulation layer often uses a single dielectric material, resulting in a high dielectric loss tangent, further exacerbating signal energy dissipation and making it difficult to meet the low-loss transmission requirements of millimeter-wave bands. For example, the loss tangent of a typical FR-4 substrate at 10GHz is as high as 0.02, which is 50 times that of polytetrafluoroethylene (PTFE), demonstrating a significant difference in dielectric loss under the same structure. 2) Insufficient shielding effectiveness: Existing RF cables often use single-layer braided or single-layer aluminum foil shielding structures, which are prone to electromagnetic leakage at high frequencies and crosstalk between adjacent cables, affecting the stability of signal transmission. A 2025 test report from the China Academy of Information and Communications Technology (CAICT) shows that the shielding effectiveness of single-layer braided RF cables in the 1–6 GHz band is only about 85 dB, far lower than the 105 dB of double-layer composite shielding structures. Furthermore, in bands above 18 GHz, due to the resonance effect of the braided aperture, the shielding effectiveness drops sharply to below 70 dB. 3) Poor mechanical performance and environmental adaptability: The multi-layer structure of traditional RF cables is not tightly bonded, making them prone to delamination and detachment. Simultaneously, they lack resistance to high and low temperatures, aging, and wear. In extreme environments (such as temperatures below -40°C, temperatures above 85°C, humidity, and vibration), signal transmission performance deteriorates significantly, and structural damage may even occur, making them unsuitable for complex applications such as automotive electronics and outdoor communication equipment. Existing technology indicates that RF cables without thermal compensation design can experience phase drift of ±15° / m@10 GHz under temperature cycling from -40°C to +85°C, exhibiting extremely poor stability. 4) Imperfect manufacturing process: Existing manufacturing methods mostly involve processing each layer independently in stages before assembly. This process is cumbersome, inefficient, and makes it difficult to guarantee the concentricity and fit between layers, easily leading to gaps and increased signal reflection and loss. Furthermore, inaccurate control of process parameters can result in insufficient conductor roundness and uneven insulation thickness, further affecting the overall performance of the RF cable. Existing measured data shows that without closed-loop feedback control, the standard deviation of return loss fluctuation for the entire cable roll can reach 1.8 dB at 26 GHz, indicating poor stability.
[0004] To address the aforementioned issues, there is an urgent need to design a multi-layered RF cable with high performance and multi-layered collaborative optimization, along with an efficient and precise fabrication method, to reduce high-frequency signal loss, improve shielding effectiveness and mechanical reliability, and meet the application requirements of next-generation communication technologies and various high-end electronic devices. Summary of the Invention
[0005] The purpose of this section is to outline some aspects of the embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.
[0006] Therefore, the purpose of this invention is to provide a multilayer radio frequency cable and its manufacturing method to solve the problems mentioned in the background art.
[0007] To address the aforementioned technical problems, according to one aspect of the present invention, the present invention provides the following technical solution:
[0008] A multilayer radio frequency cable includes, from the inside out, a conductor core layer, an insulation layer, a shielding layer and a protective layer, with each layer arranged coaxially and adjacent layers tightly bonded together by an adhesive layer;
[0009] The conductor core layer has a multi-strand stranded structure, the insulating layer is a composite dielectric layer, and the shielding layer is a multi-layer composite shielding structure.
[0010] As a preferred embodiment of the multilayer radio frequency cable described in this invention, the conductor core layer is made of multiple strands of silver-plated copper-clad steel stranded together, with the diameter of a single copper wire being 0.05-0.2 mm and the stranding pitch being 8-12 times the diameter of the silver-plated copper-clad steel strand.
[0011] The outer diameter of the conductor core layer is 0.5-2.0 mm, and the twist tightness coefficient is ≥0.92.
[0012] As a preferred embodiment of the multilayer radio frequency cable of the present invention, the insulation layer is a double-layer composite structure, consisting of an inner insulation layer and an outer insulation layer from the inside to the outside.
[0013] The inner insulation layer is made of modified polytetrafluoroethylene material with a thickness of 0.1-0.3 mm, a dielectric constant εᵣ=1.8-2.2, and a loss tangent tanδ≤0.0005. The outer insulation layer is made of liquid crystal polymer material with a thickness of 0.05-0.2 mm, a dielectric constant εᵣ=2.4-2.8, and a loss tangent tanδ≤0.0008.
[0014] As a preferred embodiment of the multilayer radio frequency cable described in this invention, the bonding layer is made of high-temperature resistant modified epoxy resin adhesive with a thickness of 0.01-0.03 mm, a bonding strength ≥1.5 MPa, a high temperature resistance range of -60℃ to 150℃, a dielectric constant εᵣ≤3.0, and a loss tangent tanδ≤0.001.
[0015] As a preferred embodiment of the multilayer radio frequency cable described in this invention, the shielding layer is a three-layer composite structure, consisting of an inner shielding layer, a middle shielding layer, and an outer shielding layer from the inside out.
[0016] The inner shielding layer is an aluminum foil wrapping layer with a thickness of 0.01-0.02 mm and a wrapping overlap rate of ≥50%. The middle shielding layer is a tin-plated copper wire braided layer with a tin plating thickness of ≥0.005 mm, a braiding density of ≥95%, and a copper wire diameter of 0.03-0.08 mm. The outer shielding layer is a copper strip longitudinal wrapping layer with a copper strip thickness of 0.01-0.02 mm and a longitudinal wrapping overlap width of 1 / 3-1 / 2 of the copper strip width.
[0017] As a preferred embodiment of the multilayer radio frequency cable described in this invention, the protective layer is made of modified polyetheretherketone material with a thickness of 0.08-0.2 mm, a Shore hardness of D75-D85, an elongation at break of ≥150%, and a high and low temperature resistance range of -60℃ to 180℃.
[0018] A method for fabricating a multilayer radio frequency cable, comprising the following steps:
[0019] S1. Select high-purity silver-plated copper-clad steel wire and use stranding equipment to regularly strand it. The stranding pitch is controlled to be 8-12 times the diameter of the silver-plated copper-clad steel wire, and the stranding tightness coefficient is ≥0.92. After stranding, the conductor core layer is annealed at a temperature of 300-400℃ for 10-20 minutes and then naturally cooled to room temperature to obtain a conductor core layer with a smooth surface, high roundness, and good flexibility.
[0020] S2. Using an extrusion molding process, the modified polytetrafluoroethylene material is heated to 380-420℃ to melt it, and then uniformly coated onto the surface of the conductor core layer prepared in step S1. The thickness of the inner insulation layer is controlled to be 0.1-0.3mm. During the coating process, the extrusion speed is controlled to be 5-10m / min, and the conductor core layer traction speed is synchronized with the extrusion speed. After the coating is completed, a cooling device is used for rapid cooling. The cooling temperature is 20-30℃, and the cooling time is 5-10min, to obtain a conductor core coated with an inner insulation layer.
[0021] S3. On the surface of the inner insulation layer obtained in step S2, an outer insulation layer is coated using an extrusion molding process. The liquid crystal polymer material is heated to 320-360℃ and melted, then uniformly coated on the surface of the inner insulation layer. The thickness of the outer insulation layer is controlled to be 0.05-0.2mm, the extrusion speed is 4-8m / min, and the traction speed is synchronized with the extrusion speed to ensure that the outer insulation layer and the inner insulation layer are tightly bonded without gaps. After coating, a cooling treatment is performed again at a temperature of 20-30℃ for 5-10 minutes to obtain a conductor core coated with an insulation layer.
[0022] S4. Apply the high-temperature resistant modified epoxy resin adhesive evenly to the surface of the outer insulation layer obtained in step S3. The coating thickness is 0.01-0.03 mm. The coating method is spraying or roller coating. During the coating process, control the coating speed to 3-6 m / min to ensure that the adhesive layer is uniform, without missed coating or accumulation. After the coating is completed, perform a pre-curing treatment. The pre-curing temperature is 80-100℃ and the pre-curing time is 5-10 min to allow the adhesive layer to initially cure.
[0023] S5. Using a wrapping device, uniformly wrap aluminum foil with a thickness of 0.01-0.02mm around the surface of the adhesive layer after pre-curing in step S4. The wrapping overlap rate is ≥50%, and the wrapping speed is 3-5m / min. Ensure that the aluminum foil is tightly wrapped to form an inner shielding layer. Using a braiding device, braid tin-plated copper wire onto the surface of the inner shielding layer. The braiding density is ≥95%, the braiding pitch is 0.5-1.0mm, and the braiding speed is 2-4m / min. Ensure that the braided layer is uniform and tightly formed to form an intermediate shielding layer. Using a longitudinal wrapping device, longitudinally wrap copper strip with a thickness of 0.01-0.02mm onto the surface of the intermediate shielding layer. The longitudinal wrapping overlap width is 1 / 3-1 / 2 of the copper strip width. The longitudinal wrapping speed is 3-5m / min. Form an outer shielding layer. Then, perform overall curing treatment. The curing temperature is 120-150℃, and the curing time is 15-25min. This ensures that the shielding layer is tightly bonded to the adhesive layer and the insulation layer.
[0024] S6. Using an extrusion molding process, the modified polyether ether ketone material is heated to 380-420℃ and melted. Then, it is uniformly coated onto the surface of the shielding layer obtained in step S5. The thickness of the protective layer is controlled to be 0.08-0.2mm, the extrusion speed is 3-6m / min, and the traction speed is synchronized with the extrusion speed to ensure that the protective layer is uniform, free of bubbles and damage, and tightly adheres to the shielding layer. After coating, a cooling treatment is performed at a temperature of 20-30℃ for 10-15min to obtain a preliminary multilayer radio frequency cable.
[0025] In a preferred embodiment of the method for preparing a multilayer radio frequency cable according to the present invention, in steps S3 and S6, the extrusion molding adopts a precision extruder with a screw speed of 30-50 r / min and a die temperature 5-10°C higher than the material melting temperature to ensure uniform material melting and accurate coating thickness; the cooling device adopts water cooling or air cooling, and the cooling rate is controlled at 5-10°C / min to avoid cracks in the insulation layer or protective layer due to excessively rapid cooling.
[0026] In a preferred embodiment of the method for preparing a multilayer radio frequency cable according to the present invention, in step S5, the wrapping equipment, braiding equipment and longitudinal wrapping equipment are all precision automated equipment with a positioning accuracy of ≤±0.01mm to ensure the concentricity and covering accuracy of the shielding layer; the curing treatment adopts a hot air circulating curing oven, and the wind speed is controlled at 1-2m / s during the curing process to ensure uniform temperature.
[0027] In a preferred embodiment of the method for preparing a multilayer radio frequency cable according to the present invention, in step S1, a high-speed precision stranding machine is used for stranding, and the tension is controlled at 5-10N during the stranding process to ensure that the copper wires are stranded evenly and tightly without loosening; the annealing treatment is carried out in a vacuum annealing furnace with a vacuum degree ≥10⁻³Pa to avoid oxidation of the copper wires.
[0028] Compared with the prior art, the beneficial effects of the present invention are:
[0029] 1. The conductor core layer of this invention uses silver-plated copper-clad steel wire, combined with a double-layer composite insulation layer, which effectively reduces the skin effect and dielectric loss. In the 1-40GHz frequency band, the insertion loss is ≤0.7dB / m@26GHz and ≤0.3dB / m@10GHz, the return loss is ≤-18dB, and the phase stability is ≤±2° / m@10GHz, which is significantly better than existing RF cables and can meet the high-frequency low-loss transmission requirements of high-end equipment such as 5G / 6G millimeter-wave communication and radar. At the same time, the characteristic impedance can be adjusted to 50Ω or 75Ω according to the requirements, adapting to different application scenarios and having strong compatibility.
[0030] 2. It adopts a three-layer composite shielding structure to block internal signal leakage and external electromagnetic interference in all directions. The shielding effectiveness is ≥105dB in the 1-6GHz frequency band and ≥85dB in the 18-40GHz frequency band. It effectively solves the problems of insufficient shielding and easy crosstalk in existing RF cables, ensuring the stability and integrity of signal transmission. It is especially suitable for dense cabling scenarios, which can significantly reduce the crosstalk between adjacent cables and improve the overall system performance.
[0031] 3. The layers are tightly bonded together by a high-temperature resistant adhesive layer. Combined with the modified PEEK material of the protective layer, the product has high tensile strength, high elongation at break, wear resistance, high and low temperature resistance (-60℃ to 180℃), aging resistance, and chemical corrosion resistance. The minimum bending radius can reach less than 6 times the outer diameter of the cable. It can adapt to complex and harsh operating environments such as outdoor, automotive electronics, and medical equipment. It is not prone to delamination, peeling, or damage. The service life can reach more than 15 years, which is significantly better than existing RF cables.
[0032] 4. This invention employs a continuous and automated manufacturing process, integrating conductor stranding, insulation extrusion, adhesive coating, shielding layer preparation, and protective layer extrusion. This reduces the cumbersome process of step-by-step processing and assembly, increasing production efficiency by more than 30%. Simultaneously, by precisely controlling the process parameters of each step, the dimensional accuracy, concentricity, and layer adhesion of the product are ensured, resulting in a product qualification rate of ≥98%, reducing production costs and rework rates. Furthermore, the use of vacuum annealing and hot air circulation curing further enhances the product's performance stability. Attached Figure Description
[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:
[0034] Figure 1 This is a schematic diagram of the structure of a multilayer radio frequency cable according to the present invention. Detailed Implementation
[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
[0036] Secondly, the present invention is described in detail with reference to the schematic diagrams. When detailing the embodiments of the present invention, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not according to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of the present invention. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.
[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.
[0038] Example 1
[0039] This embodiment provides a multilayer radio frequency cable, which, from the inside out, includes a conductor core layer 100, an insulation layer 200, an adhesive layer, a shielding layer 300, and a protective layer 400, as follows:
[0040] The conductor core layer 100 is made of silver-plated copper-clad steel wire. The diameter of a single silver-plated copper-clad steel wire is 0.1 mm, and a total of 19 strands are twisted together. The twisting pitch is 1.0 mm, the twisting tightness coefficient is 0.93, the outer diameter of the conductor core layer is 0.8 mm, and the twisting method is right-hand regular twisting. After annealing treatment (350℃, heat preservation for 15 min), the conductivity is ≥98% IACS.
[0041] The inner insulation layer 200 is made of modified polytetrafluoroethylene (mPTFE) with a thickness of 0.2 mm, dielectric constant εᵣ=2.0, and loss tangent tanδ=0.0004; the outer insulation layer is made of liquid crystal polymer (LCP) with a thickness of 0.1 mm, dielectric constant εᵣ=2.6, and loss tangent tanδ=0.0006; the total thickness of the insulation layer is 0.3 mm, and the outer diameter of the core after encapsulation is 1.4 mm.
[0042] The bonding layer uses a high-temperature resistant modified epoxy resin adhesive with a thickness of 0.02 mm, a bonding strength of 1.8 MPa, a high temperature resistance range of -60℃ to 150℃, a dielectric constant εᵣ=2.8, and a loss tangent tanδ=0.0009.
[0043] The inner shielding layer 310 of the shielding layer 300 is an aluminum foil wrapping layer with a thickness of 0.015 mm and a wrapping overlap rate of 55%; the middle shielding layer 320 is a tin-plated copper wire braided layer with a tin plating thickness of 0.006 mm, a copper wire diameter of 0.05 mm, a braiding density of 96%, and a braiding pitch of 0.8 mm; the outer shielding layer 330 is a copper strip longitudinal wrapping layer with a copper strip thickness of 0.015 mm and a longitudinal wrapping overlap width of 1 / 2 of the copper strip width; the total thickness of the shielding layer is 0.12 mm, and the outer diameter after wrapping is 1.64 mm.
[0044] The protective layer 400 is made of modified polyetheretherketone (PEEK) material with a thickness of 0.12mm, a Shore hardness of D80, an elongation at break of 160%, and a high and low temperature resistance range of -60℃ to 180℃. After the protective layer is applied, the overall outer diameter of the RF cable is 1.88mm and the characteristic impedance is 50Ω.
[0045] The method for fabricating the multilayer radio frequency cable in this embodiment includes the following steps:
[0046] Step 1: Preparation of conductor core layer: Select silver-plated copper-clad steel wire with a diameter of 0.1 mm, and use a high-speed precision stranding machine (tension 8N) to strand 19 strands in the right direction, with a stranding pitch of 1.0 mm and a stranding tightness coefficient of 0.93; place the stranded conductor core layer into a vacuum annealing furnace (vacuum degree 10⁻³Pa), hold at 350℃ for 15 min, and allow to cool naturally to room temperature to obtain the conductor core layer.
[0047] Step 2: Coating the inner insulation layer: Using a precision extruder, the mPTFE material is heated to 400℃ and melted, and then uniformly coated onto the surface of the conductor core at an extrusion speed of 8m / min. The thickness of the inner insulation layer is controlled at 0.2mm, and the traction speed is synchronized with the extrusion speed. After coating, the core is rapidly cooled by water cooling (cooling temperature 25℃, cooling time 8min) to obtain the core with the inner insulation layer.
[0048] Step 3: Coating the outer insulation layer: Using a precision extruder, the LCP material is heated to 340℃ and melted, and then uniformly coated onto the surface of the inner insulation layer at an extrusion speed of 6m / min. The thickness of the outer insulation layer is controlled at 0.1mm, and the traction speed is synchronized with the extrusion speed. After coating, the core is cooled by water cooling (cooling temperature 25℃, cooling time 8min) to obtain the core with the insulation layer.
[0049] Step 4: Apply adhesive layer: Apply high-temperature resistant modified epoxy resin adhesive evenly to the surface of the outer insulation layer by spraying, with a coating thickness of 0.02 mm and a coating speed of 4 m / min; after coating, pre-cur at 85℃ for 8 min to obtain the pre-cured core.
[0050] Step 5: Preparation of shielding layers: 1) Inner shielding layer: Using a wrapping device, wrap 0.015mm thick aluminum foil around the surface of the adhesive layer at a speed of 4m / min, with a wrapping overlap rate of 55%; 2) Middle shielding layer: Using a braiding device, braid 0.05mm thick copper wire with a 0.006mm tin plating layer around the surface of the inner shielding layer at a speed of 3m / min, with a braiding density of 96% and a braiding pitch of 0.8mm; 3) Outer shielding layer: Using a longitudinal wrapping device, longitudinally wrap 0.015mm thick copper strip around the surface of the middle shielding layer at a speed of 4m / min, with an overlap width of 1 / 2 the width of the copper strip; After the shielding layer is prepared, place it in a hot air circulating curing oven and keep it at 135℃ for 20 minutes for overall curing.
[0051] Step 6: The protective layer is coated using a precision extruder. The modified PEEK material is heated to 400℃ and melted, and then uniformly coated onto the surface of the shielding layer at an extrusion speed of 5m / min. The thickness of the protective layer is controlled at 0.12mm, and the traction speed is synchronized with the extrusion speed. After coating, the cable is cooled by water cooling (cooling temperature 25℃, cooling time 12min) to obtain a preliminary RF cable.
[0052] Step 7: Cut the pre-formed RF cable into 10m lengths, and grind and chamfer both ends; then age it at 130℃ for 36 hours; after aging, conduct a comprehensive test, and the test results are shown in Table 1.
[0053] Example 2
[0054] This embodiment provides a multilayer radio frequency cable, which, from the inside out, includes a conductor core layer 100, an insulation layer 200, an adhesive layer, a shielding layer 300, and a protective layer 400, as follows:
[0055] The conductor core layer 100 is made of silver-plated copper-clad steel wire. The diameter of a single silver-plated copper-clad steel wire is 0.08 mm, and a total of 37 strands are twisted together. The twisting pitch is 0.8 mm (10 times the diameter of the copper wire), and the twisting tightness coefficient is 0.94. The outer diameter of the conductor core layer is 1.2 mm, and the twisting method is left-hand regular twisting. After annealing treatment (320℃, heat preservation for 12 min), the conductivity is ≥98% IACS.
[0056] The inner insulation layer 200 is made of modified polytetrafluoroethylene (mPTFE) with a thickness of 0.25 mm, dielectric constant εᵣ=1.9, and loss tangent tanδ=0.0003; the outer insulation layer is made of liquid crystal polymer (LCP) with a thickness of 0.15 mm, dielectric constant εᵣ=2.5, and loss tangent tanδ=0.0005; the total thickness of the insulation layer is 0.4 mm, and the outer diameter of the core after encapsulation is 2.0 mm.
[0057] The bonding layer uses a high-temperature resistant modified epoxy resin adhesive with a thickness of 0.025 mm, a bonding strength of 2.0 MPa, a high temperature resistance range of -60℃ to 150℃, a dielectric constant εᵣ=2.7, and a loss tangent tanδ=0.0008.
[0058] The inner shielding layer 310 of the shielding layer 300 is an aluminum foil wrapping layer with a thickness of 0.012 mm and a wrapping overlap rate of 60%; the middle shielding layer 320 is a tin-plated copper wire braided layer with a tin plating thickness of 0.007 mm, a copper wire diameter of 0.06 mm, a braiding density of 97%, and a braiding pitch of 0.7 mm; the outer shielding layer 330 is a copper strip longitudinal wrapping layer with a copper strip thickness of 0.012 mm and a longitudinal wrapping overlap width of 1 / 2 of the copper strip width; the total thickness of the shielding layer is 0.15 mm, and the outer diameter after wrapping is 2.3 mm.
[0059] The protective layer 400 is made of modified polyetheretherketone (PEEK) material with a thickness of 0.15mm, a Shore hardness of D82, an elongation at break of 170%, and a high and low temperature resistance range of -60℃ to 180℃. After the protective layer is applied, the overall outer diameter of the RF cable is 2.6mm and the characteristic impedance is 75Ω.
[0060] The fabrication method of the multilayer radio frequency cable in this embodiment is the same as that in Embodiment 1, except for the following process parameter adjustments:
[0061] Step 1: Stranding tension is 7N, annealing temperature is 320℃, and holding time is 12min;
[0062] Step 2: mPTFE heating temperature 390℃, extrusion speed 7m / min, inner insulation layer thickness 0.25mm;
[0063] Step 3: LCP heating temperature 330℃, extrusion speed 5m / min, outer insulation layer thickness 0.15mm;
[0064] Step 4: Coating speed 3.5 m / min, pre-curing temperature 90℃, pre-curing time 7 min;
[0065] Step 5: Aluminum foil wrapping speed 3.5m / min, overlap rate 60%; copper wire braiding speed 2.5m / min, braiding density 97%, braiding pitch 0.7mm; copper strip longitudinal wrapping speed 3.5m / min; curing temperature 130℃, heat preservation time 18min;
[0066] Step 6: PEEK heating temperature 390℃, extrusion speed 4m / min, protective layer thickness 0.15mm;
[0067] Step 7: Aging temperature 125℃, aging time 40h; cutting length 10m, test results are shown in Table 1 below.
[0068] Example 3
[0069] This embodiment provides a multilayer radio frequency cable, which, from the inside out, includes a conductor core layer 100, an insulation layer 200, an adhesive layer, a shielding layer 300, and a protective layer 400. Specific structural parameters are as follows:
[0070] The conductor core layer 100 is made of silver-plated copper-clad steel wire. The diameter of a single silver-plated copper-clad steel wire is 0.12 mm, and a total of 13 strands are twisted together. The twisting pitch is 1.2 mm (10 times the diameter of the copper wire), and the twisting tightness coefficient is 0.92. The outer diameter of the conductor core layer is 0.6 mm, and the twisting method is right-hand regular twisting. After annealing treatment (380℃, heat preservation for 18 min), the conductivity is ≥98% IACS.
[0071] The insulation layer 200 is made of modified polytetrafluoroethylene (mPTFE) with a thickness of 0.15 mm, dielectric constant εᵣ=2.1, and loss tangent tanδ=0.0005; the outer insulation layer is made of liquid crystal polymer (LCP) with a thickness of 0.08 mm, dielectric constant εᵣ=2.7, and loss tangent tanδ=0.0007; the total thickness of the insulation layer is 0.23 mm, and the outer diameter of the core after encapsulation is 1.06 mm.
[0072] The bonding layer uses a high-temperature resistant modified epoxy resin adhesive with a thickness of 0.015 mm, a bonding strength of 1.6 MPa, a high temperature resistance range of -60℃ to 150℃, a dielectric constant εᵣ=2.9, and a loss tangent tanδ=0.0010.
[0073] The inner shielding layer 310 of the shielding layer 300 is an aluminum foil wrapping layer with a thickness of 0.018 mm and a wrapping overlap rate of 50%; the middle shielding layer 320 is a tin-plated copper wire braided layer with a tin plating thickness of 0.005 mm, a copper wire diameter of 0.04 mm, a braiding density of 95%, and a braiding pitch of 0.9 mm; the outer shielding layer 330 is a copper strip longitudinal wrapping layer with a copper strip thickness of 0.018 mm and a longitudinal wrapping overlap width of 1 / 3 of the copper strip width; the total thickness of the shielding layer is 0.11 mm, and the outer diameter after wrapping is 1.28 mm.
[0074] The protective layer 400 is made of modified polyetheretherketone (PEEK) material with a thickness of 0.1 mm, a Shore hardness of D78, an elongation at break of 155%, and a high and low temperature resistance range of -60℃ to 180℃. After the protective layer is applied, the overall outer diameter of the RF cable is 1.48 mm and the characteristic impedance is 50 Ω.
[0075] The fabrication method of the multilayer radio frequency cable in this embodiment is the same as that in Embodiment 1, except for the following process parameter adjustments:
[0076] Step 1: Stranding tension is 9N, annealing temperature is 380℃, and holding time is 18min;
[0077] Step 2: mPTFE heating temperature 410℃, extrusion speed 9m / min, inner insulation layer thickness 0.15mm;
[0078] Step 3: LCP heating temperature 350℃, extrusion speed 7m / min, outer insulation layer thickness 0.08mm;
[0079] Step 4: Coating speed 4.5 m / min, pre-curing temperature 80℃, pre-curing time 9 min;
[0080] Step 5: Aluminum foil wrapping speed 4.5m / min, overlap rate 50%; copper wire braiding speed 3.5m / min, braiding density 95%, braiding pitch 0.9mm; copper strip longitudinal wrapping speed 4.5m / min; curing temperature 140℃, heat preservation time 22min;
[0081] Step 6: PEEK heating temperature 410℃, extrusion speed 6m / min, protective layer thickness 0.1mm;
[0082] Step 7: Aging temperature 135℃, aging time 30h; cutting length 10m, test results are shown in Table 1 below.
[0083] Comparative Example 1 (Existing single-insulated, double-shielded RF cable)
[0084] A commercially available conventional radio frequency cable was selected, with the following structure: conductor core layer (ordinary copper wire, single diameter 0.1mm, 19 strands twisted together, outer diameter 0.8mm), single insulation layer (PE material, thickness 0.3mm, dielectric constant εᵣ=3.2, loss tangent tanδ=0.002), double shielding layer (aluminum foil wrapping + copper wire braiding), and protective layer (PVC material, thickness 0.12mm). The overall outer diameter is 1.88mm, and the characteristic impedance is 50Ω. Performance testing was conducted according to the same testing standards as in Example 1, and the test results are shown in Table 1 below.
[0085] Comparative Example 2 (Unbonded, single-layer shielded RF cable)
[0086] A comparative radio frequency cable was prepared, with a structure basically the same as that of Example 1, except that: there is no adhesive layer, and the shielding layer is a single-layer copper wire braided layer (braiding density 96%). The remaining structural parameters and preparation process are the same as those of Example 1. The performance of the cable was tested according to the same testing standards as that of Example 1, and the test results are shown in Table 1 below.
[0087] Comparative Example 3 (Single Insulation Layer, Triple Shielded RF Cable)
[0088] A comparative radio frequency cable was prepared, with a structure basically the same as that of Example 1, except that the insulation layer is a single mPTFE layer (thickness 0.3 mm), and the other structural parameters and preparation process are the same as those of Example 1. The performance of the cable was tested according to the same testing standards as that of Example 1, and the test results are shown in Table 1 below.
[0089] Table 1 Performance test results of Examples 1-3 and Comparative Examples 1-3
[0090] Testing items unit Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Insertion loss (10GHz) dB / m 0.28 0.26 0.29 0.52 0.35 0.32 Insertion loss (26GHz) dB / m 0.65 0.62 0.68 1.15 0.82 0.75 Return loss (10GHz) dB -19.2 -19.5 -18.8 -14.3 -16.5 -18.2 Return loss (26GHz) dB -18.5 -18.8 -18.2 -13.8 -15.8 -17.5 Characteristic impedance Ω 50±1 75±1.5 50±1 50±2.5 50±1.8 50±1.2 Shielding effectiveness (1-6GHz) dB 108 110 106 82 90 107 Shielding effectiveness (18-40GHz) dB 88 90 86 65 72 87 Phase stability (10GHz) ° / m ±1.8 ±1.6 ±1.9 ±8.5 ±4.2 ±2.5 Bond strength MPa 1.8 2.0 1.6 0.8 0.5 1.7 Elongation at break % 160 170 155 100 120 158 Minimum bending radius mm 11.3 15.6 8.9 20.7 15.0 11.5 High and low temperature resistance (-60℃ to 180℃) - No damage, no delamination, stable performance No damage, no delamination, stable performance No damage, no delamination, stable performance PVC layer cracks, insulation performance deteriorates Layering phenomenon, reduced shielding effectiveness No damage, no delamination, stable performance Performance retention rate after aging % 96 97 95 78 85 94
[0091] As can be seen from the test results in Table 1, the multilayer RF cables of Examples 1-3 of the present invention are significantly superior to those of Comparative Examples 1-3 in terms of insertion loss, return loss, shielding effectiveness, phase stability, mechanical properties, and environmental adaptability.
[0092] 1) Insertion loss and return loss: Examples 1-3 have an insertion loss of ≤0.29dB / m in the 10GHz band and ≤0.68dB / m in the 26GHz band, with a return loss of ≤-18.2dB. In contrast, Comparative Example 1 (existing product) has an insertion loss as high as 1.15dB / m in the 26GHz band and a return loss of only -13.8dB, showing a significant difference. This is mainly because the present invention uses a high-purity conductor core layer and a double-layer composite insulation layer, which effectively reduces the skin effect and dielectric loss. At the same time, the layers are tightly bonded, reducing signal reflection.
[0093] 2) Shielding effectiveness: Examples 1-3 have shielding effectiveness ≥106dB in the 1-6GHz band and ≥86dB in the 18-40GHz band, while Comparative Examples 1 and 2 have significantly lower shielding effectiveness, especially Comparative Example 1, which has a shielding effectiveness of only 65dB in the 18-40GHz band. This is because the present invention uses a three-layer composite shielding structure to block electromagnetic interference and signal leakage in all directions, while Comparative Example 1 has a double-layer shielding and Comparative Example 2 has a single-layer shielding, resulting in limited shielding effect.
[0094] 3) Phase stability: The phase stability of Examples 1-3 in the 10GHz band is ≤±1.9° / m, which is far better than ±8.5° / m of Comparative Example 1 and ±4.2° / m of Comparative Example 2. This is due to the double-layer composite insulation layer and the tightly fitted interlayer structure of the present invention, which effectively reduces the influence of temperature changes and mechanical deformation on the phase.
[0095] 4) Mechanical properties and environmental adaptability: The bonding strength of Examples 1-3 is ≥1.6MPa, the elongation at break is ≥155%, the minimum bending radius is small, the high and low temperature resistance is excellent, and the performance retention rate after aging is ≥95%; while the PVC protective layer of Comparative Example 1 has poor high and low temperature resistance, and the performance retention rate after aging is only 78%; Comparative Example 2 has no bonding layer, the interlayer bonding is not tight, and delamination occurs, with a bonding strength of only 0.5MPa.
[0096] 5) Characteristic impedance: The characteristic impedance deviation of Examples 1-3 is small (±1Ω or ±1.5Ω), while the characteristic impedance deviation of Comparative Example 1 reaches ±2.5Ω. This shows that the fabrication process of the present invention is precise and the dimensions of each layer are strictly controlled, which ensures the stability of the characteristic impedance and is suitable for high-frequency transmission requirements.
[0097] Furthermore, Comparative Example 3 uses a single mPTFE insulation layer, which has lower dielectric loss, but its mechanical strength and high temperature resistance are not as good as the double-layer composite insulation layer of the present invention. Its phase stability and performance retention rate after aging are slightly lower than those of Examples 1-3, further illustrating that the double-layer composite insulation layer design of the present invention has significant advantages.
[0098] Although the present invention has been described above with reference to embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, as long as there is no structural conflict, the features in the disclosed embodiments can be combined with each other in any manner. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
Claims
1. A multilayer radio frequency cable, characterized in that, From the inside out, it includes a conductor core layer (100), an insulation layer (200), a shielding layer (300), and a protective layer (400). Each layer is coaxially arranged, and adjacent layers are tightly bonded together by an adhesive layer. The conductor core layer (100) has a multi-strand stranded structure, the insulation layer (200) is a composite dielectric layer, and the shielding layer (300) is a multi-layer composite shielding structure.
2. The multilayer radio frequency cable according to claim 1, characterized in that, The conductor core layer (100) is made of multiple strands of silver-plated copper-clad steel stranded together, with a diameter of 0.05-0.2 mm for a single copper wire and a stranding pitch of 8-12 times the diameter of the silver-plated copper-clad steel strand. The outer diameter of the conductor core layer is 0.5-2.0 mm, and the twist tightness coefficient is ≥0.
92.
3. A multilayer radio frequency cable according to claim 1, characterized in that, The insulating layer (200) is a double-layer composite structure, consisting of an inner insulating layer and an outer insulating layer from the inside out; The inner insulation layer is made of modified polytetrafluoroethylene material with a thickness of 0.1-0.3 mm, a dielectric constant εᵣ=1.8-2.2, and a loss tangent tanδ≤0.0005. The outer insulation layer is made of liquid crystal polymer material with a thickness of 0.05-0.2 mm, a dielectric constant εᵣ=2.4-2.8, and a loss tangent tanδ≤0.0008.
4. A multilayer radio frequency cable according to claim 1, characterized in that, The adhesive layer is made of high-temperature resistant modified epoxy resin adhesive with a thickness of 0.01-0.03 mm, an adhesive strength ≥1.5 MPa, a high temperature resistance range of -60℃ to 150℃, a dielectric constant εᵣ≤3.0, and a loss tangent tanδ≤0.
001.
5. A multilayer radio frequency cable according to claim 1, characterized in that, The shielding layer (300) is a three-layer composite structure, consisting of an inner shielding layer (310), a middle shielding layer (320), and an outer shielding layer (330) from the inside out. The inner shielding layer (310) is an aluminum foil wrapping layer with a thickness of 0.01-0.02 mm and a wrapping overlap rate of ≥50%. The middle shielding layer (320) is a tin-plated copper wire braided layer with a tin plating thickness of ≥0.005 mm, a braiding density of ≥95%, and a copper wire diameter of 0.03-0.08 mm. The outer shielding layer (330) is a copper strip longitudinal wrapping layer with a copper strip thickness of 0.01-0.02 mm and a longitudinal wrapping overlap width of 1 / 3-1 / 2 of the copper strip width.
6. A multilayer radio frequency cable according to claim 1, characterized in that, The protective layer is made of modified polyetheretherketone material with a thickness of 0.08-0.2 mm, a Shore hardness of D75-D85, an elongation at break of ≥150%, and a high and low temperature resistance range of -60℃ to 180℃.
7. A method for manufacturing a multilayer radio frequency cable as described in any one of claims 1-6, characterized in that, The steps are as follows: S1. Select silver-plated copper-clad steel wire and use stranding equipment to strand it regularly. The stranding pitch is controlled to be 8-12 times the diameter of the silver-plated copper-clad steel wire, and the stranding tightness coefficient is ≥0.
92. After stranding, the conductor core layer is annealed at a temperature of 300-400℃ for 10-20 minutes and then naturally cooled to room temperature to obtain a conductor core layer with a smooth surface, high roundness, and good flexibility. S2. Using an extrusion molding process, the modified polytetrafluoroethylene material is heated to 380-420℃ to melt it, and then uniformly coated onto the surface of the conductor core layer prepared in step S1. The thickness of the inner insulation layer is controlled to be 0.1-0.3mm. During the coating process, the extrusion speed is controlled to be 5-10m / min, and the conductor core layer traction speed is synchronized with the extrusion speed. After the coating is completed, a cooling device is used for rapid cooling. The cooling temperature is 20-30℃, and the cooling time is 5-10min, to obtain a conductor core coated with an inner insulation layer. S3. On the surface of the inner insulation layer obtained in step S2, an outer insulation layer is coated using an extrusion molding process. The liquid crystal polymer material is heated to 320-360℃ and melted, then uniformly coated on the surface of the inner insulation layer. The thickness of the outer insulation layer is controlled to be 0.05-0.2mm, the extrusion speed is 4-8m / min, and the traction speed is synchronized with the extrusion speed to ensure that the outer insulation layer and the inner insulation layer are tightly bonded without gaps. After coating, a cooling treatment is performed again at a temperature of 20-30℃ for 5-10 minutes to obtain a conductor core coated with an insulation layer. S4. Apply the high-temperature resistant modified epoxy resin adhesive evenly to the surface of the outer insulation layer obtained in step S3. The coating thickness is 0.01-0.03 mm. The coating method is spraying or roller coating. During the coating process, control the coating speed to 3-6 m / min to ensure that the adhesive layer is uniform, without missed coating or accumulation. After the coating is completed, perform a pre-curing treatment. The pre-curing temperature is 80-100℃ and the pre-curing time is 5-10 min to allow the adhesive layer to initially cure. S5. Using a wrapping device, uniformly wrap aluminum foil with a thickness of 0.01-0.02mm around the surface of the adhesive layer after pre-curing in step S4. The wrapping overlap rate is ≥50%, and the wrapping speed is 3-5m / min. Ensure that the aluminum foil is tightly wrapped to form an inner shielding layer. Using a braiding device, braid tin-plated copper wire onto the surface of the inner shielding layer. The braiding density is ≥95%, the braiding pitch is 0.5-1.0mm, and the braiding speed is 2-4m / min. Ensure that the braided layer is uniform and tightly formed to form an intermediate shielding layer. Using a longitudinal wrapping device, longitudinally wrap copper strip with a thickness of 0.01-0.02mm onto the surface of the intermediate shielding layer. The longitudinal wrapping overlap width is 1 / 3-1 / 2 of the copper strip width. The longitudinal wrapping speed is 3-5m / min. Form an outer shielding layer. Then, perform overall curing treatment. The curing temperature is 120-150℃, and the curing time is 15-25min. This ensures that the shielding layer is tightly bonded to the adhesive layer and the insulation layer. S6. Using an extrusion molding process, the modified polyether ether ketone material is heated to 380-420℃ and melted. Then, it is uniformly coated onto the surface of the shielding layer obtained in step S5. The thickness of the protective layer is controlled to be 0.08-0.2mm, the extrusion speed is 3-6m / min, and the traction speed is synchronized with the extrusion speed to ensure that the protective layer is uniform, free of bubbles and damage, and tightly adheres to the shielding layer. After coating, a cooling treatment is performed at a temperature of 20-30℃ for 10-15min to obtain a preliminary multilayer radio frequency cable.
8. The method for manufacturing a multilayer radio frequency cable according to claim 7, characterized in that, In steps S3 and S6, the extrusion molding uses a precision extruder with a screw speed of 30-50 r / min and a die temperature 5-10℃ higher than the material melting temperature to ensure uniform material melting and precise coating thickness. The cooling device uses water cooling or air cooling, and the cooling rate is controlled at 5-10℃ / min to avoid cracks in the insulation or protective layer caused by excessively rapid cooling.
9. The method for manufacturing a multilayer radio frequency cable according to claim 7, characterized in that, In step S5, the wrapping equipment, braiding equipment, and longitudinal wrapping equipment all adopt precision automated equipment with a positioning accuracy of ≤±0.01mm to ensure the concentricity and covering accuracy of the shielding layer; the curing treatment adopts a hot air circulation curing oven, and the wind speed is controlled at 1-2m / s during the curing process to ensure uniform temperature.
10. A method for manufacturing a multilayer radio frequency cable according to claim 7, characterized in that, In step S1, a high-speed precision stranding machine is used for stranding. During the stranding process, the tension is controlled at 5-10N to ensure that the copper wires are stranded evenly and tightly without any looseness. The annealing treatment uses a vacuum annealing furnace with a vacuum degree ≥10⁻³Pa to avoid oxidation of the copper wires.