Mobile phone cable

Abstract

The application discloses a mobile phone cable, belongs to the technical field of mobile communication terminal supporting radio frequency cables, and is suitable for 5G and above high-frequency transmission scenarios; the cable adopts a four-layer coaxial structure, and a center conductor, a solid FEP insulating layer, a braided silver-plated copper flat wire shielding layer and a sheath are sequentially and coaxially tightly covered from inside to outside. By strictly controlling the ratio of the outer diameter of the center conductor to the solid FEP insulating layer to be 1: (2.7-2.9), the concentricity of the insulating layer is controlled to be more than 95%, and the wire diameter deviation is controlled to be within ±0.005 mm, so that the core problem of unstable characteristic impedance in the prior art is effectively solved; meanwhile, the silver-plated copper flat wire is used for high-density braided shielding, and the electromagnetic shielding performance and high-frequency transmission efficiency are improved. The overall outer diameter of the cable is not more than 1.3 mm, the cable has good softness and bending resistance, can be adapted to the small installation space in a mobile phone, and meets the performance requirements of 5G and above mobile phones on high-frequency radio frequency signal transmission.

Description

Technical Field

[0001] This invention relates to the field of mobile phone accessories technology, specifically mobile phone cables. Background Technology

[0002] With the full commercialization of fifth-generation mobile communication technology (5G) and the accelerated development of sixth-generation mobile communication technology (6G), the internal operating frequency of smartphones has jumped from the traditional MHz level to the GHz level. Mainstream 5G phones operate at 2.4GHz, 5GHz, and 6GHz, with some high-end models even having millimeter-wave antennas operating at frequencies exceeding 10GHz. Under high-frequency operating conditions, the skin effect of current becomes extremely significant, with current concentrating only on the very thin surface layer of the conductor. This places far more stringent requirements on the characteristic impedance consistency, signal transmission loss, and electromagnetic shielding performance of RF cables than on traditional cables. Simultaneously, as portable electronic devices, smartphones have extremely limited internal assembly space and a compact structure. Cables need to be bent and routed multiple times within this limited space, and during daily use, the cables are constantly in a dynamic bending state. This also places high demands on the cable's size, flexibility, and mechanical reliability.

[0003] The core problem of unstable characteristic impedance in existing mobile phone RF cables is insufficient precision in the FEP insulation extrusion process. Uneven dielectric thickness leads to significant fluctuations in the cable's characteristic impedance, deviating from the 50Ω standard value. This results in severe signal reflection, increased return loss, and exacerbated transmission loss, failing to meet the demands of GHz-level high-frequency transmission. Furthermore, existing cables often use a round braided shielding layer with large gaps between the round wires and low braiding coverage, resulting in poor high-frequency shielding. This makes them susceptible to external interference and prone to signal radiation, affecting the normal operation of other components in the mobile phone. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a mobile phone cable. By optimizing the cable's structural design and manufacturing process control, the core problem of unstable characteristic impedance in the prior art is solved. At the same time, the high-frequency transmission performance, electromagnetic shielding performance and bending resistance of the cable are improved to meet the usage requirements of 5G and above high-frequency mobile phones.

[0005] To achieve the above objectives, the present invention provides the following technical solution: The mobile phone cable consists of a central conductor, a solid FEP insulation layer, a braided silver-plated copper flat wire shielding layer, and a sheath, all tightly wrapped together in a coaxial manner from the inside out. The central conductor is a circular stranded conductor formed by regularly twisting together multiple metal monofilaments; The solid FEP insulation layer is coated on the outer surface of the center conductor by an extrusion process. The ratio of the outer diameter of the center conductor to the outer diameter of the solid FEP insulation layer is 1:(2.7-2.9), and the concentricity of the solid FEP insulation layer is ≥95%, and the wire diameter deviation in any direction of the same cross section is ≤±0.005mm, so as to stabilize the characteristic impedance of the cable within a preset range. The braided silver-plated copper flat wire shielding layer is wrapped around the outer surface of the solid FEP insulation layer through a cross-braiding process. The braided silver-plated copper flat wire shielding layer is made of multiple silver-plated copper flat wires with rectangular cross sections. The sheath is applied to the outer surface of the braided silver-plated copper flat wire shielding layer via an extrusion process.

[0006] Optionally, the center conductor is formed by regularly twisting seven silver-plated copper wires with a single wire diameter of 0.083 mm in the same direction, with a twisting pitch of 2.5-3.5 mm, a twisting roundness deviation of ≤±0.01 mm, and an outer diameter of 0.25 mm±0.01 mm after twisting.

[0007] Optionally, the solid FEP insulation layer is made by extrusion molding of polytetrafluoroethylene propylene resin with a melt index of 20-30 g / 10 min measured under test conditions of 372℃ and 5 kg load, and the extrusion outer diameter is controlled to be 0.7 mm ± 0.01 mm; the characteristic impedance of the cable is stable at 50 Ω ± 2 Ω.

[0008] Optionally, the thickness of the thinnest part of the solid FEP insulation layer is ≥0.21mm.

[0009] Optionally, the braided silver-plated copper flat wire shielding layer is braided using a 16-spindle high-speed braiding machine, with each spindle containing one silver-plated copper flat wire. The cross-sectional dimensions of a single silver-plated copper flat wire are 0.05mm × 0.22mm, and the silver plating layer thickness is 0.8-1.5μm. The braiding pitch is precisely controlled at 7.9mm ± 0.2mm, and the braiding coverage is ≥92%.

[0010] Optionally, the braided silver-plated copper flat wire shielding layer has a shielding attenuation of not less than 35dB at a frequency of 1GHz and a shielding attenuation of not less than 30dB at a frequency of 6GHz.

[0011] Optionally, the interlayer adhesion between the solid FEP insulation layer and the braided silver-plated copper flat wire shielding layer is 3-8N, and the interlayer adhesion between the braided silver-plated copper flat wire shielding layer and the sheath is 5-21N; after the cable undergoes 10,000 bending tests with a bending radius of 5 times the cable outer diameter, a bending angle of ±90°, and a bending frequency of 30 times / minute, the change rate of the conductor's DC resistance is ≤5%.

[0012] Optionally, the sheath is made of modified thermoplastic elastomer with a Shore hardness of 75-80A by extrusion molding, the sheath thickness is 0.18-0.20mm, and the overall outer diameter of the cable is ≤1.3mm; the temperature resistance range of the sheath is -40℃ to +85℃.

[0013] Optionally, the cable has an attenuation constant of ≤2.65dB / m in the 2.4GHz band and an attenuation constant of ≤4.4dB / m in the 6GHz band.

[0014] Optionally, the braided silver-plated copper flat wire shielding layer has a braiding coverage of ≥92%, and the mobile phone cable is used for transmission scenarios of 6GHz and above.

[0015] This invention provides a mobile phone cable, which has the following beneficial effects: This invention sets a fixed ratio of 1:(2.7-2.9) between the outer diameter of the center conductor and the outer diameter of the solid FEP insulation layer, controls the outer diameter deviation of the insulation layer within ±0.01mm, the wire diameter deviation in any direction of the same cross section within ±0.005mm, and the concentricity of the insulation layer above 95%. This process control ensures that the dielectric thickness is uniform throughout the entire length of the cable, and that the characteristic impedance of the cable is basically consistent throughout the entire length. This significantly reduces reflection during signal transmission, ensures the integrity of high-frequency signal transmission, reduces signal transmission loss, and enables the cable to meet the transmission requirements of 5G and above GHz high-frequency bands. This invention uses a braided silver-plated copper flat wire shielding layer to replace the traditional round wire braided shielding layer. The braiding density of the silver-plated copper flat wire shielding layer is higher than that of the traditional round wire braided shielding layer, and its braiding coverage is more than 15% higher than that of the same specification round wire braided shielding layer. This can suppress high-frequency electromagnetic interference and signal radiation, significantly improving the electromagnetic shielding performance of the cable. The cross-section of the silver-plated copper flat wire is rectangular, which allows the flat wires to fit more tightly during the braiding process, effectively reducing the braiding gap and improving the braiding coverage. At the same time, the silver plating layer has good conductivity and oxidation resistance, which can further reduce skin effect loss at high frequencies. This shielding layer structure can effectively suppress the influence of external electromagnetic interference on the internal signal of the cable, and also prevent the internal signal of the cable from radiating outward, avoiding interference with the normal operation of other components of the mobile phone. This invention optimizes the extrusion process between each layer to ensure that the interlayer adhesion meets the requirements; the adhesion between the solid FEP insulation layer and the braided silver-plated copper flat wire shielding layer is controlled at 3-8N, and the adhesion between the braided silver-plated copper flat wire shielding layer and the sheath is controlled at 5-21N; the good interlayer adhesion ensures that the cable will not delaminate or shift during long-term repeated bending, and the conductor DC resistance change rate and insulation resistance can remain stable, thus extending the service life of the cable; Furthermore, the overall outer diameter of the cable of this invention does not exceed 1.3mm, making it compact and suitable for the limited installation space inside mobile phones. The multi-strand fine copper wire twisted center conductor and the modified thermoplastic elastomer sheath give the cable good flexibility and a small bending radius, facilitating complex wiring inside mobile phones. The manufacturing process of this invention is mature and controllable, with clear quantitative standards for all key parameters. It has good consistency and high yield during the production process, making it suitable for large-scale industrial production and able to meet the large demand of the mobile phone industry for high-performance radio frequency cables. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the radial cross-sectional structure of the mobile phone cable of the present invention; Figure 2 This is an axial schematic diagram of the stranded structure of the central conductor of the present invention; Figure 3 This is a schematic diagram showing the unfolded braided silver-plated copper flat wire shielding layer of the present invention.

[0017] In the diagram: 1. Center conductor; 2. Solid FEP insulation layer; 3. Braided silver-plated copper flat wire shielding layer; 4. Sheath. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] The parameter tests for all embodiments of this invention comply with the following national standards: Conductor Dimension Measurement: GB / T 4909.2-2009 Bare Wire Test Methods Part 2: Dimension Measurement Insulation and sheath performance: GB / T 2951.11-2008 General test methods for insulation and sheath materials of cables and optical fibers - Part 11: General test methods for thickness and dimensional measurement and mechanical property test; Characteristic impedance: GB / T 17737.108-2018 Coaxial communication cables - Part 1-108: Electrical test methods - Characteristic impedance, phase delay, group delay, electrical length and propagation speed tests; Attenuation constant: GB / T 17737.113-2024 Coaxial communication cables - Part 1-113: Electrical test methods - Attenuation constant test; Return loss: GB / T 17737.112-2018 Coaxial communication cables - Part 1-112: Electrical test methods - Return loss (impedance conformance) test; Shielding attenuation: GB / T 31723.405-2015 Test methods for metallic communication cables - Part 4-5: Electromagnetic compatibility coupling or shielding attenuation absorption clamp method; DC resistance of conductors: GB / T 17737.101-2018 Coaxial communication cables - Part 1-101: Electrical test methods - DC resistance test of conductors; Bending test: GB / T 17737.314-2018 Coaxial communication cables - Part 1-314: Mechanical test methods - Bending test of cables; Adhesion test: GB / T 17737.313-2015 Coaxial communication cables - Part 1-313: Mechanical test methods - Adhesion of the medium and the sheath.

[0022] Example 1 The standard 5G radio frequency cable (RF113 double silver wire) uses RF as a general identifier for radio frequency (RF) cables and 113 as the industry standard model for fine-diameter RF cables. The double silver wire refers to a double-layer silver-plated structure in which the center conductor is made of silver-plated copper wire and the shielding layer substrate is made of silver-plated copper flat wire, which has both excellent solderability and high-frequency conductivity. This embodiment is a standard RF cable suitable for mainstream 5G mobile phones and is mainly used for signal transmission in the 2.4GHz, 5GHz and 6GHz frequency bands.

[0023] The specific structural parameters are as follows: The center conductor 1 is made of 7 silver-plated copper wires with a diameter of 0.083mm twisted in the same direction (multiple single wires are twisted evenly in the same direction at a fixed pitch, resulting in a stable and round structure). The twisting pitch (the axial distance of a single wire rotating around the conductor axis) is 3mm, the twisting roundness deviation (the difference between the maximum and minimum outer diameter of the twisted conductor) is ±0.009mm, and the outer diameter of the conductor after twisting is 0.25mm. The solid FEP insulation layer 2 is made of polytetrafluoroethylene propylene resin with a melt index (the mass of melt extruded from a standard-sized capillary within 10 minutes after the thermoplastic plastic melts at a specified temperature and under a specified weight load) of 25 g / 10 min. The test conditions are 372℃, 5 kg load, and an extrusion outer diameter of 0.70 mm. The ratio of the outer diameter of the center conductor to the outer diameter of the solid FEP insulation layer is 1:2.8, and the characteristic impedance is 50 Ω ± 1.5 Ω. The concentricity of the solid FEP insulation layer 2 is 96%, the diameter deviation in any direction of the same cross section is about ±0.003mm, the thickness of the thinnest part of the insulation layer is 0.22mm, and there are no bubbles, pinholes or impurities along the entire length. The braided silver-plated copper flat wire shielding layer 3 is braided using a 16-spindle high-speed braiding machine. Each spindle contains one silver-plated copper flat wire. The cross-sectional dimensions of a single silver-plated copper flat wire are 0.05mm (thickness) × 0.22mm (width), and the silver plating layer thickness is 1.0μm. The braiding pitch (axial distance of one revolution of the shielding layer flat wire) is 7.9mm, and the braiding coverage (the proportion of the shielding layer covering the insulation layer) is 93%. Sheath 4 is made of modified thermoplastic elastomer with a Shore hardness of 78A through extrusion molding. The sheath thickness is 0.19mm and the overall outer diameter of the cable is 1.28mm. The sheath surface is smooth and free of scratches, and the temperature resistance range is -40℃ to +85℃. Interlayer adhesion: The adhesion between the solid FEP insulation layer and the braided silver-plated copper flat wire shielding layer is 5N, and the adhesion between the braided silver-plated copper flat wire shielding layer and the sheath is 12N.

[0024] The specific preparation process is as follows: 1. Conductor stranding is performed using a high-speed stranding machine; seven silver-plated copper wires with a diameter of 0.083mm are installed on the pay-off frame, and the pay-off tension is adjusted to 2.5N / wire; the stranding pitch of the stranding machine is set to 3mm, and a regular stranding method in the same direction is adopted; after stranding, the center conductor is wound onto a special spool for later use. 2. Insulation extrusion is performed using a φ30 single-screw extruder; FEP resin with a melt index of 25g / 10min is added to the hopper, and the temperatures of each section of the extruder are set as follows: feeding section 325℃, plasticizing section 345℃, homogenizing section 355℃, and die head 358℃; the center conductor is passed through the die head mold, and the traction speed is adjusted to 38m / min; at the same time, a concentricity tester is used to adjust the position of the die head mold to ensure that the concentricity reaches 96%; after extrusion, the core wire is cooled and shaped in a 22℃ cooling water bath before being wound up; 3. The shielding braid is processed using a 16-spindle high-speed braiding machine; 16 silver-plated copper flat wires with a cross-sectional size of 0.05mm×0.22mm are installed on the spindles, one wire per spindle, and the braiding tension is adjusted to 7N / spindle; the braiding pitch is set to 7.9mm, and the braiding machine is started to perform cross braiding; the completed shielding wire is wound up for later use. 4. The sheath extrusion is performed using a φ25 single-screw extruder; modified TPE resin with a Shore hardness of 78A is added to the hopper, and the temperatures of each section of the extruder are set as follows: feeding section 165℃, plasticizing section 180℃, homogenizing section 185℃, and die head 188℃; the shielded wire is passed through the die head mold, and the traction speed is adjusted to 48m / min; the extruded cable is cooled and shaped in a 20℃ cooling water bath before being wound up. 5. The finished cables shall be tested for characteristic impedance, attenuation constant, return loss, shielding attenuation, interlayer adhesion, bending resistance and appearance dimensions in accordance with the above-mentioned national standards; after passing the tests, they shall be wound into reels and put into storage.

[0025] Example 2 The high-speed data transmission cable for 5G mobile phone periscope telephoto camera modules is mainly used to transmit the MIPICSI-2 high-speed serial data signal output by the image sensor, verify the reliability of the technical solution under boundary conditions, and solve the signal transmission distortion problem caused by the small internal space of the module, frequent dynamic bending, and complex electromagnetic environment.

[0026] Periscope telephoto camera modules achieve optical zoom through the movement of prisms and lens groups. Their internal wiring space is highly limited, requiring cables to undergo multiple 90° bends within a module housing less than 2mm thick. Furthermore, during zooming, the cables undergo repeated dynamic bends along with the lens group, accumulating tens of thousands of bends. In addition, the camera module is located close to the phone's motherboard and antenna unit, making it susceptible to electromagnetic interference from the motherboard's high-frequency digital signals and the antenna's radio frequency signals. Moreover, the 4K / 8K high-definition video signal transmission rate output by the image sensor exceeds 10Gbps, placing more stringent requirements on the cable's characteristic impedance consistency, transmission loss, and electromagnetic shielding performance than on ordinary radio frequency cables.

[0027] The specific structural parameters are as follows: The center conductor 1 is made of 7 silver-plated copper wires with a diameter of 0.083mm twisted in the same direction. The twisting pitch is 2.5mm, the twisting roundness deviation is ±0.008mm, and the outer diameter of the conductor after twisting is 0.24mm. The solid FEP insulation layer 2 is extruded from polytetrafluoroethylene propylene resin with a melt index of 20g / 10min. The test conditions are 372℃ and 5kg load, and the extrusion outer diameter is 0.69mm. The ratio of the outer diameter of the center conductor to the outer diameter of the solid FEP insulation layer is 1:2.88, and the characteristic impedance is 50Ω±2Ω. The concentricity of the solid FEP insulation layer 2 is 95%, the diameter deviation in any direction of the same cross section is about ±0.002mm, the thickness of the thinnest part of the insulation layer is 0.21mm, and there are no bubbles, pinholes or impurities along the entire length. The braided silver-plated copper flat wire shielding layer 3 is braided using a 16-spindle high-speed braiding machine. Each spindle contains one silver-plated copper flat wire with a cross-sectional dimension of 0.05mm × 0.22mm and a silver plating thickness of 0.8μm. The braiding pitch is 7.7mm, and the braiding coverage is 92%. Sheath 4 is made of modified thermoplastic elastomer with a Shore hardness of 75A through extrusion molding. The sheath thickness is 0.20mm and the overall outer diameter of the cable is 1.29mm. The sheath surface is smooth and free of scratches, and the temperature resistance range is -40℃ to +85℃. Interlayer adhesion: The adhesion between the solid FEP insulation layer and the braided silver-plated copper flat wire shielding layer is 3N, and the adhesion between the braided silver-plated copper flat wire shielding layer and the sheath is 5N.

[0028] The specific preparation process is as follows: 1. Conductor stranding is performed using a high-speed stranding machine; seven silver-plated copper wires with a diameter of 0.083mm are installed on the pay-off frame, and the pay-off tension is adjusted to 2.3N / wire; the stranding pitch of the stranding machine is set to 2.5mm, and a regular stranding method in the same direction is adopted; after stranding, the center conductor is wound onto a special spool for later use; 2. Insulation extrusion is performed using a φ30 single-screw extruder; FEP resin with a melt index of 20g / 10min is added to the hopper, and the temperatures of each section of the extruder are set as follows: feeding section 320℃, plasticizing section 340℃, homogenizing section 350℃, and die head 355℃; the center conductor is passed through the die head mold, and the traction speed is adjusted to 36m / min; at the same time, a concentricity tester is used to adjust the position of the die head mold to ensure that the concentricity reaches 95%; after extrusion, the core wire is cooled and shaped in a 20℃ cooling water bath before being wound up. 3. The shielding braid is processed using a 16-spindle high-speed braiding machine; 16 silver-plated copper flat wires with a cross-sectional size of 0.05mm×0.22mm are installed on the spindles, one wire per spindle, and the braiding tension is adjusted to 6.5N / spindle; the braiding pitch is set to 7.7mm, and the braiding machine is started to perform cross braiding; the completed shielding wire is wound up for later use. 4. The sheath extrusion is performed using a φ25 single-screw extruder; modified TPE resin with a Shore hardness of 75A is added to the hopper, and the temperatures of each section of the extruder are set as follows: feeding section 160℃, plasticizing section 175℃, homogenizing section 180℃, and die head 185℃; the shielded cable is passed through the die head mold, and the traction speed is adjusted to 45m / min; a laser diameter gauge is used to monitor the outer diameter of the sheath in real time, and the sheath thickness is controlled to be 0.20mm; after extrusion, the cable is cooled and shaped in a 20℃ cooling water bath before being wound up. 5. Perform characteristic impedance, attenuation constant, return loss, shielding attenuation, interlayer adhesion, bending resistance, and dimensional inspection on the finished cables according to the aforementioned national standards; focus on testing the performance stability after dynamic bending to ensure that it meets the requirements for use in camera modules; after passing the inspection, the cables are wound into coils and stored in the warehouse.

[0029] Application advantages With an overall outer diameter of only 1.29mm, the cable can easily pass through the narrow wiring slot inside the periscope camera module. Compared with traditional round shielded cables of the same specification, it leaves more design space for the optical components and drive mechanism inside the module. The cable features a multi-strand fine copper wire core conductor and a modified TPE sheath, giving it excellent flexibility with a minimum bending radius of 5.5mm (5 times the cable's outer diameter). In a dynamic bending test simulating camera zoom, after 10,000 reciprocating bends, the conductor's DC resistance change rate was only 5.0%, and the insulation resistance remained at 10 ohms. 12 Ω or higher, meeting the usage requirements throughout the entire life cycle of the camera; The precisely controlled outer diameter ratio of the center conductor 1 and the solid FEP insulation layer 2, along with 95% concentricity of the insulation layer, ensures that the cable's characteristic impedance remains stable at 50Ω±2Ω. At the commonly used transmission rates of 3.125Gbps, 6.25Gbps, and 10Gbps for the MIPICSI-2 interface, the cable's attenuation constants are 2.07dB / m, 3.07dB / m, and 3.98dB / m, respectively, and the return loss is greater than 20dB. This effectively avoids reflection and distortion during high-speed signal transmission, ensuring clear and stable 4K / 8K high-definition video images without noise or ghosting. The braided silver-plated copper flat wire shielding layer has a shielding attenuation of no less than 35dB at 1GHz and no less than 30dB at 6GHz. It can effectively isolate the interference of motherboard digital signals and antenna radio frequency signals on camera image signals, while preventing the high-speed data signals of the camera from radiating outward and affecting the normal operation of other components of the mobile phone. The cable of this embodiment was applied to the periscope telephoto camera module of a mainstream 5G mobile phone for overall performance testing. In multi-fold optical zoom mode, the 8K@30fps video signal output by the camera was transmitted stably without frame drops or screen distortion. When the mobile phone was performing multiple tasks simultaneously, such as making calls, accessing Wi-Fi, and connecting via Bluetooth, the imaging quality of the camera was not affected in any way. After high and low temperature cycling tests (-40℃ to +85℃) and zoom simulation tests, the cable performance showed no significant attenuation, and all functions of the camera were normal.

[0030] Example 3 High-frequency silver-plated conductor cables are used as feeders for millimeter-wave antennas in high-end 5G mobile phones and pre-research 6G mobile phones to verify the optimal performance of the technical solution under boundary conditions.

[0031] The specific structural parameters are as follows: The center conductor 1 is made of 7 silver-plated copper wires with a diameter of 0.083mm twisted in the same direction. The twisting pitch is 3.5mm, the twisting roundness deviation is ±0.01mm, and the outer diameter of the conductor after twisting is 0.26mm. The solid FEP insulation layer 2 is extruded from polytetrafluoroethylene propylene resin with a melt index of 30 g / 10 min. The test conditions are 372℃, 5 kg load, and extrusion outer diameter of 0.71 mm. The ratio of the outer diameter of the center conductor to the outer diameter of the solid FEP insulation layer is 1:2.73, and the characteristic impedance is 50 Ω ± 1 Ω. The concentricity of the solid FEP insulation layer 2 is 98%, the diameter deviation in any direction of the same cross section is about ±0.004mm, the thickness of the thinnest part of the insulation layer is 0.23mm, and there are no bubbles, pinholes or impurities along the entire length. The braided silver-plated copper flat wire shielding layer 3 is braided using a 16-spindle high-speed braiding machine. Each spindle contains one silver-plated copper flat wire. The cross-sectional dimensions of a single silver-plated copper flat wire are 0.05mm (thickness) × 0.22mm (width), and the silver plating thickness is 1.5μm. The braiding pitch is 8.1mm, and the braiding coverage is 95%. Sheath 4 is made of modified thermoplastic elastomer with a Shore hardness of 80A through extrusion molding. The sheath thickness is 0.18mm and the overall outer diameter of the cable is 1.27mm. The sheath surface is smooth and free of scratches, and the temperature resistance range is -40℃ to +85℃. Interlayer adhesion: The adhesion between the solid FEP insulation layer and the braided silver-plated copper flat wire shielding layer is 8N, and the adhesion between the braided silver-plated copper flat wire shielding layer and the sheath is 21N.

[0032] The specific preparation process is as follows: 1. Conductor stranding is performed using a high-speed stranding machine; seven silver-plated copper wires with a diameter of 0.083mm are installed on the pay-off frame, and the pay-off tension is adjusted to 2.2N / wire; the stranding pitch of the stranding machine is set to 3.5mm, and a regular stranding method in the same direction is adopted; after stranding, the center conductor is wound onto a special spool for later use; 2. Insulation extrusion is performed using a φ30 single-screw extruder; FEP resin with a melt index of 30g / 10min is added to the hopper, and the temperatures of each section of the extruder are set as follows: feeding section 330℃, plasticizing section 350℃, homogenizing section 360℃, and die head 362℃; the center conductor is passed through the die head mold, and the traction speed is adjusted to 36m / min; at the same time, a concentricity tester is used to adjust the position of the die head mold to ensure that the concentricity reaches 98%; after extrusion, the core wire is cooled and shaped in a 20℃ cooling water bath before being wound up. 3. The shielding braid is processed using a 16-spindle high-speed braiding machine; 16 spindles of silver-plated copper flat wire with a cross-sectional size of 0.05mm × 0.22mm are installed on the spindles, one wire per spindle, and the braiding tension is adjusted to 6.5N / spindle; the braiding pitch is set to 8.1mm, and the braiding machine is started for cross braiding; the braiding pitch and coverage are monitored in real time during the braiding process to ensure that the braiding coverage reaches 95%; the shielding wire is wound up and ready for use after braiding. 4. The sheath extrusion is performed using a φ25 single-screw extruder; modified TPE resin with a Shore hardness of 80A is added to the hopper, and the temperatures of each section of the extruder are set as follows: feeding section 170℃, plasticizing section 185℃, homogenizing section 190℃, and die head 192℃; the shielded cable is passed through the die head mold, and the traction speed is adjusted to 45m / min; the outer diameter of the sheath is monitored in real time using a laser diameter gauge, and the sheath thickness is controlled to be 0.18mm; after extrusion, the cable is cooled and shaped in a 20℃ cooling water bath before being wound up. 5. Perform characteristic impedance, attenuation constant, return loss, shielding attenuation, interlayer adhesion, bending resistance and appearance dimension tests on the finished cables according to the above national standards; focus on testing the transmission performance in the 6GHz high-frequency band to ensure that it meets the high-frequency transmission requirements; after passing the test, the cables are wound into reels and put into storage.

[0033] Comparative Example This comparative example uses the currently common RF113 type mobile phone radio frequency coaxial cable, which is a traditional thin-diameter coaxial radio frequency cable widely used in existing 5G mobile phones. Its specific structure, process parameters, and core differences from the embodiments of this invention are as follows: 1. The center conductor is made of 7 ordinary tinned copper wires with a diameter of 0.083mm. The precise control process of regular stranding in the same direction is not adopted. There is no quantitative control of the stranding pitch. The roundness deviation of the stranding is about ±0.02mm. The outer diameter of the conductor after stranding is 0.27mm.

[0034] 2. The insulation layer is coated with general-purpose FEP resin through conventional extrusion process. The ratio of the outer diameter of the conductor to the outer diameter of the insulation layer is not strictly limited. The extrusion process only controls the overall outer diameter tolerance. The concentricity of the insulation layer is about 85% to 90%. The diameter deviation in any direction of the same cross section is about ±0.02mm. The thickness of the thinnest part of the insulation layer is about 0.25mm.

[0035] 3. The shielding layer is woven with 16 spindles of tin-plated copper wire with a round cross section. Each spindle contains 3 round copper wires with a single wire diameter of 0.05mm. The weaving pitch is about 10mm, without high-precision control, and the weaving coverage is about 75%. The copper wire surface is not silver-plated.

[0036] 4. The sheath is made of ordinary PVC resin by extrusion molding, with a sheath thickness of about 0.25mm and an overall cable outer diameter of about 1.5mm.

[0037] 5. The manufacturing process adopts the traditional cable extrusion and braiding process, without high-precision process control links such as online concentricity detection, braiding pitch closed-loop control, and interlayer adhesion quantitative control. Only basic tests on the continuity and appearance dimensions of the finished product are performed.

[0038] Compared with the three embodiments of the present invention, the core structure and process differences are as follows: the ratio of the outer diameter of the center conductor to the outer diameter of the insulation layer of 1:(2.7-2.9) and the high concentricity control are not implemented; the shielding layer uses ordinary round copper wire instead of silver-plated copper flat wire, and the braiding coverage is low; the sheath material and thinning precision are insufficient; the overall process control precision is low, and there is no quantitative process guarantee for mechanical and electrical properties.

[0039] The performance indicators of the three embodiments and comparative examples of this application are shown in Table 1 below: Table 1. Cable performance indicators of embodiments and comparative examples in this application. Based on the test data in Table 1, the differences in various performance indicators and the corresponding technical principles are analyzed as follows: 1. Difference in characteristic impedance stability: The characteristic impedance deviation of the comparative example reaches ±5Ω, while the impedance deviations of embodiments 1-3 of this invention are controlled at ±1.5Ω, ±2Ω, and ±1Ω respectively, improving stability by 2-5 times. This difference directly stems from the core design of this invention: by strictly limiting the ratio of the outer diameter of the center conductor to the outer diameter of the solid FEP insulation layer to 1:(2.7-2.9), while increasing the concentricity of the insulation layer to over 95% and compressing the deviation of the wire diameter at the same cross-section to within ±0.005mm, the impedance fluctuations caused by uneven dielectric thickness are eliminated from the root of the coaxial structure, ensuring a high degree of consistency of characteristic impedance throughout the entire length of the cable. This fundamentally solves the industry pain point of unstable characteristic impedance in traditional cables and provides a structural basis for low-reflection transmission of high-frequency signals.

[0040] 2. Differences in transmission attenuation performance: In the 2.4GHz and 6GHz frequency bands, the attenuation constants of the three embodiments of this invention are only 75% to 85% of those of the comparative examples, significantly reducing high-frequency transmission loss. This effect is achieved through multiple design considerations: firstly, precise impedance matching greatly reduces signal reflection loss; secondly, high-purity, low-dielectric-loss FEP insulating dielectric combined with uniform thickness control reduces high-frequency dielectric loss; and thirdly, the silver-plated copper flat wire shielding layer and optional silver-plated conductor structure alleviate conductor loss caused by the skin effect of high-frequency current. Among them, Embodiment 3, which uses a silver-plated copper wire center conductor, exhibits the best attenuation performance in the high-frequency band, verifying that this structure can support millimeter-wave transmission scenarios at 6GHz and above.

[0041] 3. Difference in electromagnetic shielding performance: Compared to the control model, the shielding attenuation at 1GHz is only 20dB, while the shielding attenuation in Examples 1-3 of this invention can reach over 35dB, with a maximum of 40dB, representing an improvement in shielding performance of over 75%. This advantage stems from the structural innovation of the silver-plated copper flat wire shielding layer: the rectangular cross-section flat wire can be tightly bonded during the braiding process, achieving a braiding coverage of over 92%, far exceeding the approximately 75% coverage of traditional round wire braiding, effectively filling the braiding gaps; simultaneously, the silver plating layer on the surface of the copper flat wire possesses superior high-frequency conductivity. The combined effect of these two factors significantly improves the electromagnetic shielding effectiveness, resisting the influence of external electromagnetic interference on internal signals and preventing internal high-frequency signals from radiating outwards and interfering with other components of the mobile phone.

[0042] 4. Differences in interlayer adhesion and bending resistance: In the comparative example, the interlayer adhesion between the insulation and shielding layers is only 1-2N, and the DC resistance change rate of the conductor after 10,000 bends is ≥15%. The interlayer adhesion of the embodiment of this invention is improved by at least 100%, and the resistance change rate after bending is at most only 5%, significantly improving mechanical reliability. On the one hand, this invention optimizes process parameters such as extrusion temperature and braiding tension to form a stable bond between the insulation layer, shielding layer, and sheath, avoiding interlayer delamination and displacement during bending. On the other hand, the co-directional regular stranded center conductor, combined with the optimized stranding pitch, improves the conductor's fatigue resistance. Combined with the highly flexible modified TPE sheath, this ensures the cable's service life under repeated bending in confined spaces, meeting the long-term usage requirements of dynamic bending scenarios such as periscope cameras.

[0043] 5. Cable volume difference: The overall outer diameter of the comparative cable reaches 1.5mm, while the embodiments of this invention are all controlled within 1.3mm, reducing the wire diameter by about 13%. This invention, through the precise thin design of each layer structure, compresses the overall size without sacrificing electrical and mechanical performance, which can adapt to the increasingly compact wiring space inside mobile phones, reserving more space for the thinner and smaller design of terminal devices.

[0044] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A mobile phone cable, characterized in that, The central conductor (1), solid FEP insulation layer (2), braided silver-plated copper flat wire shielding layer (3), and sheath (4) are coaxially and tightly wrapped from the inside to the outside. The central conductor (1) is a circular stranded conductor formed by regularly twisting together multiple metal monofilaments; The solid FEP insulation layer (2) is coated on the outer surface of the center conductor (1) by an extrusion process. The ratio of the outer diameter of the center conductor (1) to the outer diameter of the solid FEP insulation layer (2) is 1:(2.7-2.9). The solid FEP insulation layer (2) has a concentricity of ≥95% and a wire diameter deviation of ≤±0.005mm in any direction of the same cross section, so as to stabilize the characteristic impedance of the cable within a preset range. The braided silver-plated copper flat wire shielding layer (3) is wrapped around the outer surface of the solid FEP insulation layer (2) by a cross-braiding process. The braided silver-plated copper flat wire shielding layer (3) is made of multiple silver-plated copper flat wires with rectangular cross sections. The sheath (4) is wrapped around the outer surface of the braided silver-plated copper flat wire shielding layer (3) by an extrusion process.

2. The mobile phone cable according to claim 1, characterized in that, The center conductor (1) is made of 7 silver-plated copper wires with a diameter of 0.083 mm twisted together in the same direction. The twisting pitch is 2.5-3.5 mm, the twisting roundness deviation is ≤ ±0.01 mm, and the outer diameter of the conductor after twisting is 0.25 mm ± 0.01 mm.

3. The mobile phone cable according to claim 2, characterized in that, The solid FEP insulation layer (2) is made by extrusion molding of poly(fluoroethylene propylene) resin with a melt index of 20-30 g / 10 min measured under test conditions of 372℃ and 5 kg load, and the extrusion outer diameter is controlled to be 0.7 mm ± 0.01 mm; the characteristic impedance of the cable is stable at 50 Ω ± 2 Ω.

4. The mobile phone cable according to claim 1, characterized in that, The thickness of the thinnest part of the solid FEP insulation layer (2) is ≥0.21mm.

5. The mobile phone cable according to claim 1, characterized in that, The braided silver-plated copper flat wire shielding layer (3) is braided by a 16-spindle high-speed braiding machine. Each spindle contains one silver-plated copper flat wire. The cross-sectional size of a single silver-plated copper flat wire is 0.05mm×0.22mm, and the silver plating thickness is 0.8-1.5μm. The braiding pitch is precisely controlled at 7.9mm±0.2mm, and the braiding coverage is ≥92%.

6. The mobile phone cable according to claim 5, characterized in that, The braided silver-plated copper flat wire shielding layer (3) has a shielding attenuation of not less than 35dB at 1GHz and a shielding attenuation of not less than 30dB at 6GHz.

7. The mobile phone cable according to claim 1, characterized in that, The interlayer adhesion between the solid FEP insulation layer (2) and the braided silver-plated copper flat wire shielding layer (3) is 3-8N, and the interlayer adhesion between the braided silver-plated copper flat wire shielding layer (3) and the sheath (4) is 5-21N. After the cable undergoes 10,000 bending tests with a bending radius of 5 times the outer diameter of the cable, a bending angle of ±90°, and a bending frequency of 30 times / minute, the change rate of the conductor's DC resistance is ≤5%.

8. The mobile phone cable according to claim 1, characterized in that, The sheath (4) is made of modified thermoplastic elastomer with a Shore hardness of 75-80A by extrusion molding. The sheath thickness is 0.18-0.20mm and the overall outer diameter of the cable is ≤1.3mm. The temperature resistance range of the sheath (4) is -40℃ to +85℃.

9. The mobile phone cable according to claim 1, characterized in that, The cable has an attenuation constant of ≤2.65dB / m in the 2.4GHz band and an attenuation constant of ≤4.4dB / m in the 6GHz band.

10. The mobile phone cable according to claim 1, characterized in that, The braided silver-plated copper flat wire shielding layer has a braiding coverage of ≥92%, and the mobile phone cable is used for transmission scenarios of 6GHz and above.

Images