A copper wire tinning method for tinned copper wire production

Abstract

This invention discloses a method for tin-plating copper wire for producing tin-plated copper stranded wire, relating to the field of metal surface treatment technology. The method includes: releasing copper wire into an ionic liquid electrophoresis tank, applying an electric field to strip surface oxides, followed by a three-stage countercurrent rinsing to generate clean copper wire; placing the clean copper wire into a composite plating tank, monitoring the tin liquid viscosity and copper wire linear velocity in real time, calculating the magnetic field gradient, and controlling the directional growth of tin crystals based on the magnetic field gradient to generate directional crystallized tin-plated copper wire; monitoring the surface temperature of the directional crystallized tin-plated copper wire in real time and comparing it with a preset temperature threshold to generate a temperature-permitted trigger signal; triggering a ring array spray gun based on the temperature-permitted trigger signal to generate a denser tin-plated copper wire; scanning the denser tin-plated copper wire using a micro-focus CT scanner to generate a three-dimensional point cloud map of the gaps; analyzing the gap size and normal angle of the three-dimensional point cloud map to identify the optimal spraying parameters and generate a passivation film tin-plated copper wire.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment, and in particular to a method for tin plating copper wire for the production of tin-plated copper stranded wire. Background Technology

[0002] Tin-plated copper stranded wire, as a key conductor material in the electronics and electrical fields, directly affects its conductivity and corrosion resistance lifespan due to the uniformity, bonding strength, and surface density of its plating. Currently, the industry generally employs a continuous electroplating process, comprising three main steps: pretreatment, tin plating, and post-passivation. Pretreatment typically involves chemical pickling combined with mechanical grinding to remove oxides from the copper wire surface; the tin plating process usually takes place in an acidic sulfate electrolyte, with the plating thickness controlled by the current density; and post-passivation uses a chromate passivation solution to form a protective film. This process meets the basic requirements for plating thickness and adhesion in conventional cables.

[0003] Existing processes still have room for improvement in achieving refined control of coating structure and tension stability. On the one hand, the growth direction of tin crystals during tin electroplating is affected by electrolyte convection disturbances, which can easily generate random dendrites, resulting in excessively high coating thickness dispersion and affecting the consistency of high-frequency signal transmission impedance. On the other hand, winding tension control relies on open-loop PID regulation, which has too long a response delay to sudden changes in linear speed and excessive fluctuations in the interlayer gap of the coil material. Summary of the Invention

[0004] In view of the aforementioned existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a method for tinning copper wire for the production of tin-plated copper stranded wire to solve the problems of excessively high coating thickness dispersion and excessive fluctuation in the gap between winding layers.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: This invention provides a method for tin-plating copper wire for producing tin-plated copper stranded wire. The method includes: releasing the copper wire into an ionic liquid electrophoresis tank, applying an electric field to strip surface oxides, and then performing a three-stage countercurrent rinsing to generate clean copper wire; placing the clean copper wire into a composite plating tank, monitoring the tin liquid viscosity and copper wire linear velocity in real time, calculating the magnetic field gradient, and controlling the directional growth of tin crystals according to the magnetic field gradient to generate directional crystallized tin-plated copper wire; monitoring the surface temperature of the directional crystallized tin-plated copper wire in real time and comparing it with a preset temperature threshold to generate a temperature-permitted trigger signal; and then, based on the temperature-permitted trigger signal... The ring array spray gun is triggered to generate dense tin-plated copper wire. The dense tin-plated copper wire is scanned by a micro-focus CT scanner to generate a three-dimensional point cloud map of the gap. The gap size and normal angle of the three-dimensional point cloud map are analyzed to identify the optimal spraying parameters and generate a passivation film tin-plated copper wire. The real-time tension value of the passivation film tin-plated copper wire is collected and compared with the preset tension threshold to obtain the tension deviation, which is converted into a magnetic powder brake current adjustment command. The current of the winding motor is adjusted according to the magnetic powder brake current adjustment command to obtain a high-performance tin-plated copper stranded wire coil.

[0007] In a preferred embodiment of the method for tin-plating copper wire for producing tin-plated copper stranded wire according to the present invention, the steps for generating clean copper wire are as follows: A copper wire is placed in an ionic liquid bath, the thickness of the oxide layer is monitored, and the intensity of the DC electric field is dynamically adjusted according to the thickness of the oxide layer to generate a pure copper substrate. The pure copper substrate is placed in the first rinsing tank, the conductivity value of the rinsing solution is monitored, and the countercurrent water pressure is controlled according to the conductivity value of the rinsing solution to generate primary rinsing copper wire. The primary rinsed copper wire is immersed in the second ultrasonic rinsing tank, the ion concentration is monitored, and the ultrasonic power is adjusted according to the ion concentration to generate the intermediate rinsed copper wire. Monitor the surface moisture content of the intermediate rinse copper wire, and perform hot air gradient purging based on the surface moisture content to generate clean copper wire.

[0008] In a preferred embodiment of the method for tinning copper wire used in the production of tin-plated copper stranded wire according to the present invention, the calculation of the magnetic field gradient includes the following steps. Clean copper wire is placed into a composite plating bath, and the viscosity of the molten tin is detected in real time by an online viscometer and compared with a preset viscosity threshold to generate a rheological correction command. The power of the surface acoustic wave device is increased according to the rheological correction command to generate micro vortices and produce molten tin. The linear velocity of the clean copper wire is collected in real time, and the magnetic field gradient is calculated using the velocity control gradient method.

[0009] In a preferred embodiment of the method for tin-plating copper wire for producing tin-plated copper stranded wire according to the present invention, the steps for generating directional crystallization tin-plated copper wire are as follows: By suppressing the growth direction of tin crystals according to the magnetic field gradient, a directional crystallization environment is generated; A uniform coating is applied to copper wire using molten tin and a directional crystallization environment. The uniformly coated copper wire is then sequentially fed into a three-stage cooling zone to generate directional crystallized tin-plated copper wire.

[0010] As a preferred embodiment of the copper wire tinning method for producing tinned copper stranded wire according to the present invention, the generation of the temperature permission trigger signal refers to the generation of the temperature permission trigger signal by collecting real-time temperature data of the directional crystallization tinned copper wire through an infrared thermal imager and comparing it with a preset temperature threshold.

[0011] In a preferred embodiment of the method for tin-plating copper wire for producing tin-plated copper stranded wire according to the present invention, the specific steps for generating densely tin-plated copper wire are as follows: According to the temperature-permitted trigger signal, the ring array spray gun is triggered to spray tin powder onto the coating surface of the directional crystallized tin-plated copper wire to generate semi-dense tin-plated copper wire. The unembedded tin powder on the surface of the semi-dense tin-plated copper wire is peeled off, and the porosity of the plating surface is detected. At the same time, tin powder is sprayed again according to the porosity to generate a denser tin-plated copper wire.

[0012] As a preferred embodiment of the copper wire tinning method for producing tin-plated copper stranded wire according to the present invention, the generation of the three-dimensional point cloud map of the gap refers to scanning the dense tin-plated copper wire with a micro-focus CT scanner and collecting the stranded wire gap data in real time to generate the three-dimensional point cloud map of the gap.

[0013] As a preferred embodiment of the method for tin-plating copper wire for producing tin-plated copper stranded wire according to the present invention, the specific steps for analyzing the gap size and angle, identifying the optimal spraying parameters, and generating a passivation film tin-plated copper wire are as follows. Based on the three-dimensional point cloud map of the gap, the gap depth and normal angle of adjacent copper wires are analyzed, and the pressure and angle of the passivation liquid spraying are adjusted according to the gap depth and normal angle of adjacent copper wires to generate pre-cured copper wires. The actual film thickness of the pre-cured copper wire is detected in real time, and the film thickness deviation is calculated based on the actual film thickness. The pre-cured copper wire is compensated by spraying according to the film thickness deviation value to generate a passivated tin-plated copper wire.

[0014] In a preferred embodiment of the copper wire tinning method for producing tin-plated copper stranded wire according to the present invention, the step of converting the current adjustment command to a magnetic powder brake is as follows: Based on the passivated film tin-plated copper wire, a three-dimensional voltage signal is collected, and the real-time value of the copper wire travel tension is obtained through vector synthesis calculation. At the same time, the real-time value of the copper wire travel tension is compared with the preset tension threshold to calculate the tension deviation. Based on the tension deviation, an asymmetric proportional control operation is performed to generate a magnetic powder brake current adjustment command.

[0015] In a preferred embodiment of the method for tin-plating copper wire for producing tin-plated copper stranded wire according to the present invention, the steps for obtaining high-performance tin-plated copper stranded wire coils are as follows: Adjust the braking torque according to the magnetic powder brake current adjustment command, and obtain the real-time braking torque value; Based on the real-time braking torque value, the winding tension of the winding motor is dynamically controlled to obtain high-performance tin-plated copper stranded wire coils.

[0016] The beneficial effects of this invention are as follows: By controlling the directional growth of tin crystals through a magnetic field gradient, ordered deposition of tin atoms is achieved, generating a directionally crystalline coating with consistent axial texture. This improves the uniformity of the coating crystal orientation, meeting the stringent requirements for coating uniformity in 5G communication cables. Furthermore, by analyzing the three-dimensional point cloud of the gaps to identify spraying parameters, and using spatial geometric modeling to establish the mapping relationship between the gap morphology and the spraying vector, full coverage of the passivation film within the micron-level gaps is achieved, eliminating passivation blind zones, improving the coating's salt spray resistance test lifespan, and meeting the highest protection level. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. 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.

[0018] Figure 1 A flowchart of the copper wire tinning process for producing tin-plated copper stranded wire.

[0019] Figure 2 A flowchart for generating directional crystallized tin-plated copper wire.

[0020] Figure 3 A flowchart for generating dense tin-plated copper wire.

[0021] Figure 4 A flowchart for generating a passivation film on tin-plated copper wire. Detailed Implementation

[0022] 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.

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0025] Reference Figures 1-4 This is one embodiment of the present invention, which provides a method for tinning copper wire for the production of tin-plated copper stranded wire, comprising the following steps: S1. Release the copper wire into the ionic liquid electrophoresis tank, apply an electric field to strip the surface oxides, and then perform a three-stage countercurrent rinsing to generate clean copper wire. A copper wire is placed in an ionic liquid bath, the thickness of the oxide layer is monitored, and the intensity of the DC electric field is dynamically adjusted according to the thickness of the oxide layer to generate a pure copper substrate. Furthermore, firstly, a copper wire is immersed in an ionic liquid bath and passes through it at a constant speed to form an ionic liquid film-coated copper wire. Then, a confocal laser interferometer is used to scan the surface of the ionic liquid film-coated copper wire, and the oxide layer thickness is calculated in real time according to the interference fringe spacing formula, outputting an oxide layer thickness distribution map. Next, the maximum value of the oxide layer thickness in the oxide layer thickness distribution map is extracted, and a deviation calculation is performed between it and the preset oxide layer removal target thickness to obtain the oxide layer thickness deviation. Finally, based on the oxide layer thickness deviation, a proportional-integral-differential decision operation is performed to obtain the DC electric field strength value. At the same time, a DC voltage of the DC electric field strength value is applied to both sides of the ionic liquid bath to dissociate the oxide layer and generate a pure copper substrate. The expression for calculating the DC electric field strength is: ; in, This is the value of the DC electric field strength; It is the oxide layer thickness proportional gain coefficient; It is the integral gain coefficient of oxide layer thickness; It is the differential gain coefficient of oxide layer thickness; It is the maximum value in the oxide layer thickness distribution map; It is the preset target thickness for oxide layer removal; It is the integral term of thickness deviation; It is the rate of change of thickness deviation; It should be noted that the preset target thickness for oxide layer removal was determined by observing the critical state of complete exposure of the copper substrate using scanning electron microscopy (SEM). The pure copper substrate is placed in the first rinsing tank, the conductivity value of the rinsing solution is monitored, and the countercurrent water pressure is controlled according to the conductivity value of the rinsing solution to generate primary rinsing copper wire. Furthermore, firstly, the pure copper substrate is immersed in the first rinsing tank, and the conductivity value of the rinsing solution is collected every second using an immersion electrode to obtain real-time data on the conductivity of the rinsing solution. Then, based on the real-time conductivity data, a proportional control calculation is performed: when the real-time conductivity data is greater than the conductivity threshold, a scalar multiplication operation is performed based on the conductivity deviation (the difference between the real-time conductivity data and the conductivity threshold) to obtain the water pressure increment; when the real-time conductivity data is less than or equal to the conductivity threshold, the water pressure is not increased; then, based on the water pressure increase... The flow rate is adjusted by a frequency converter to stabilize the water pressure of the centrifugal pump. Simultaneously, a turbulence-enhanced countercurrent water flow is generated by a porous media generator. Finally, the turbulence-enhanced countercurrent water flow impacts the surface of the copper wire, removing surface ion residues and obtaining primary rinsed copper wire. The primary rinsed copper wire is then tested using an online surface conductivity meter (contact four-probe). If the conductivity is greater than the conductivity threshold, a rework signal is triggered, causing the copper wire to re-enter the rinsing tank for circulation until the test results meet the standard. If the conductivity is less than or equal to the conductivity threshold, the primary rinsed copper wire that meets the standard is output. The expression for calculating the water pressure increment is: ; in, It is an increase in water pressure; It is the water pressure proportional gain coefficient; It is the real-time conductivity of the rinsing solution; It is the conductivity threshold; It is the lower limit constraint of conductivity deviation; It should be noted that the conductivity threshold (exemplary: 50 μS / cm) is set based on the specified conductor surface cleanliness threshold. Exceeding this value will result in ion residue, which will significantly reduce the adhesion of the tin plating layer. The primary rinsed copper wire is immersed in the second ultrasonic rinsing tank, the ion concentration is monitored, and the ultrasonic power is adjusted according to the ion concentration to generate the intermediate rinsed copper wire. Furthermore, the primary rinsed copper wire is first immersed in the second ultrasonic rinsing tank, and then subjected to [BMIM]... + An ion-selective electrode monitors the ion concentration of the rinsing solution in real time, acquiring real-time ion concentration data. Based on this data, the ultrasonic power value is dynamically matched using a preset concentration-power mapping relationship, and an ultrasonic power adjustment command is output. Then, the piezoelectric transducer driving voltage is adjusted based on the ultrasonic power adjustment command to generate an ultrasonic field at the bottom of the tank. During the ultrasonic treatment of the primary rinsing copper wire, cavitation bubbles collapse, generating microjets that impact the micropores on the surface of the primary rinsing copper wire, thus obtaining the intermediate rinsing copper wire. Finally, a mass spectrometer is used to detect the intermediate rinsing copper wire. If the ion residue exceeds the residue threshold, the ultrasonic power is increased for rewashing; if the ion residue is within the residue threshold, the qualified intermediate rinsing copper wire is output. It should be noted that the preset concentration-power mapping relationship refers to the discretized correspondence table between the ion concentration of the rinsing solution and the ultrasonic power established through process calibration experiments; the residual threshold is set based on the steep drop threshold of the coating adhesion. The residual ion concentration exceeding 5 ppm will significantly reduce the coating adhesion. An exemplary value range is (4.5~5.5). Monitor the surface moisture content of the intermediate rinse copper wire, and perform hot air gradient purging based on the surface moisture content to generate clean copper wire; Furthermore, the intermediate-grade rinsed copper wire is first scanned in real time by an infrared sensor to obtain the intensity of the absorption peak of water molecules on its surface, thus obtaining the moisture content detection value. Based on the moisture content detection value, temperature adjustment is performed: if the moisture content detection value exceeds the critical moisture threshold, the temperature is increased proportionally (for example, an increase of 10°C for every 0.001% increase in moisture content); if the moisture content detection value is lower than the critical moisture threshold, the temperature is maintained at 80°C (based on the basic evaporation efficiency and energy consumption balance setting), and a gradient hot air temperature setting value is output. Then, according to the gradient hot air temperature setting value, three temperature zones are divided in the drying chamber (front temperature setting value, middle temperature setting value -15°C, and rear temperature setting value -30°C). A gradient hot air field is output through a centrifugal fan, and the intermediate-grade rinsed copper wire passes through the gradient hot air field at a uniform speed. The surface water film is rapidly evaporated in the front high-temperature zone, the adsorbed water is desorbed in the middle medium-temperature zone, and the cooling and shaping is achieved in the rear low-temperature zone, resulting in pre-dried copper wire. Finally, the pre-dried copper wire is sent into a negative pressure zone to extract residual water from the micropores, generating clean copper wire. It should be noted that the critical water content threshold is set based on the critical point of sudden change in coating porosity (experimental data show that when the water content exceeds the critical water content threshold, the coating porosity increases sharply from 0.2% to 0.5%, at which point the residual water vapor partial pressure exceeds the critical value of the molten tin static pressure). An exemplary value range is (0.004%-0.006%).

[0026] S2. Place the clean copper wire into the composite plating bath, monitor the viscosity of the tin liquid and the linear velocity of the copper wire in real time, calculate the magnetic field gradient, and control the directional growth of tin crystals according to the magnetic field gradient to generate directional crystallized tin-plated copper wire. Clean copper wire is placed into a composite plating bath, and the viscosity of the molten tin is detected in real time by an online viscometer and compared with a preset viscosity threshold to generate a rheological correction command. Furthermore, a clean copper wire is first vertically inserted into the composite plating bath, and the real-time viscosity of the molten solder is detected using an immersion online viscometer at a fixed sampling frequency (e.g., 100Hz). The viscosity is then compared with a preset viscosity threshold. When the detected molten solder viscosity is greater than the preset viscosity threshold, the difference between the real-time molten solder viscosity and the preset viscosity threshold is calculated by subtraction to obtain the viscosity deviation value. Next, the viscosity deviation value is multiplied by gain to obtain the power increment value. Finally, the power increment value is converted by a 12-bit DAC (digital-to-analog converter) and superimposed on the reference power setting value to generate a rheological correction command. It should be noted that the preset viscosity threshold is set based on the optimal rheological properties of molten solder at 250°C, and an exemplary value range is (1.0~1.5); The power of the surface acoustic wave device is increased according to the rheological correction command to generate micro vortices and produce molten tin. Furthermore, the system first receives a rheological correction command and then performs target power calculation using a power increment conversion formula to obtain the target power value of the surface acoustic wave (SAW). Based on the SAW target power value, it then performs voltage conversion using a voltage square root conversion formula to obtain the piezoelectric driving voltage value. Simultaneously, the piezoelectric driving voltage value is applied to the piezoelectric substrate, and amplitude calculation is performed using a piezoelectric linear response formula to obtain the enhanced vibration amplitude, outputting an amplitude-enhanced SAW. Finally, based on the amplitude-enhanced SAW, standing wave interference is excited on the molten tin surface, forming a micro-vortex array. Simultaneously, the micro-vortex array reduces the viscosity of the molten tin through a shear thinning effect, generating a micro-vortex-enhanced molten tin. It should be noted that the shear thinning effect refers to the physical phenomenon that the apparent viscosity of a non-Newtonian fluid (such as molten tin) decreases with increasing shear rate when subjected to shear force. Real-time acquisition of the linear velocity of clean copper wire, and calculation of the magnetic field gradient using the velocity control gradient method; Furthermore, firstly, displacement-time data of the copper wire is collected by a fixed-gap photoelectric sensor group to obtain displacement-time pairs, and a division operation is performed based on the displacement-time pairs to output the real-time linear velocity of the copper wire at the entrance of the composite plating tank; then, a subtraction operation is performed on the real-time linear velocity of the copper wire at the entrance of the composite plating tank to obtain the linear velocity increment value, and a proportional multiplication operation is performed based on the linear velocity increment value to output the magnetic field gradient. The expression for calculating the magnetic field gradient is: ; in, It is the magnetic field gradient; It is the real-time linear velocity of the copper wire at the inlet of the composite plating tank; It is the baseline value of the basic magnetic field gradient; It is the compensation gain coefficient for the real-time linear velocity of the copper wire at the inlet of the composite plating tank; It is the critical linear velocity threshold; It is a lower bound constraint value, ensuring The result should not be lower than the lower limit constraint value to avoid negative compensation; By suppressing the growth direction of tin crystals according to the magnetic field gradient, a directional crystallization environment is generated; Furthermore, the magnetic field gradient is first linearly converted to current to obtain the gradient magnetic field driving current value, and a Helmholtz coil pair is excited based on the gradient magnetic field driving current value to generate a non-uniform lattice confinement magnetic field; then, the non-uniform lattice confinement magnetic field is applied to the solidification point of the molten tin, and the tin nucleus plane normal is forced to be parallel to the magnetic field gradient direction through magnetic moment coupling, outputting a pre-oriented nucleus array; finally, the pre-oriented nucleus array is epitaxially grown along the magnetic field direction in the gradient cooling field, generating a directional crystallization environment defined by the magnetic field gradient, temperature gradient and nucleus orientation angle. It should be noted that magnetic moment coupling refers to the interaction force between an external magnetic field and the atomic magnetic moments inside the material, which forces the magnetic moments to align in a specific direction along the magnetic field through the Lorentz torque; A clean copper wire is uniformly plated using molten tin and a directional crystallization environment. The uniformly plated copper wire is then sequentially fed into a three-stage cooling zone to generate directional crystallization tin-plated copper wire. Furthermore, firstly, a clean copper wire is immersed in molten tin. Under the influence of a directional crystallization environment, tin crystals are forced to grow along the magnetic field direction by the Lorentz force to form a semi-solid coating. The semi-solid coating is then sent to a nitrogen cooling zone, where it is cooled at a fixed rate (e.g., 30℃ / s) through forced convection heat transfer, locking the grain size at 50nm (based on experimental data, within the 40-60nm grain range, 50nm results in minimal grain boundary scattering and the highest carrier mobility), thus obtaining a primary cured coating. Next, the primary cured coating is placed in a water mist cooling zone, where water droplets impact the coating surface, carrying away the latent heat of phase transition and increasing the cooling rate, causing the crystal axis orientation deviation to converge, thus obtaining a secondary cured coating. Finally, the secondary cured coating is placed in a liquid nitrogen spray zone, where ultra-rapid phase transition suppresses the grain boundary diffusion coefficient, causing the grains to stretch into columnar crystals along the magnetic field direction, generating a directional crystallized tin-plated copper wire. It should be noted that the grain boundary diffusion coefficient is a physical constant (unit: m² / s) characterizing the rate of atomic migration along the grain boundaries of a material, and is obtained directly by radioactive isotope tracing combined with depth concentration analysis experiments.

[0027] S3. Real-time monitoring of the surface temperature of the directional crystallized tin-plated copper wire, comparison with the preset temperature threshold, generation of temperature permission trigger signal, triggering the ring array spray gun to work according to the temperature permission trigger signal, generating dense tin-plated copper wire; The real-time temperature data of the directional crystallized tin-plated copper wire is collected by an infrared thermal imager and compared with a preset temperature threshold to generate a temperature permission trigger signal. Furthermore, firstly, a high-speed infrared thermal imager is used to scan the surface of the oriented crystallized tin-plated copper wire in real time, collecting the radiation energy value of each pixel to generate an original temperature data matrix. Based on the original temperature data matrix, reflectivity compensation calculation is performed to eliminate environmental radiation interference and output a noise-reduced temperature matrix. Then, continuous spatiotemporal domain analysis is performed on the noise-reduced temperature matrix: the highest temperature value in the core area is extracted. When the highest temperature value continuously meets 230-250℃ within the sliding window (based on the semi-solid plastic deformation window of the tin plating layer and the maximum setting of the particle bombardment pore filling efficiency, ensuring the formation of a solid-liquid coexistence phase on the plating surface, inhibiting grain coarsening, and maintaining a grain size ≤50nm), a Boolean-type temperature permission status identifier is output. Finally, the temperature permission status identifier is encoded and converted by an optocoupler isolation circuit to generate a temperature permission trigger signal. According to the temperature-permitted trigger signal, the ring array spray gun is triggered to spray tin powder onto the coating surface of the directional crystallized tin-plated copper wire to generate semi-dense tin-plated copper wire. Furthermore, firstly, based on the temperature-permitted trigger signal, the CAN bus is driven to send a synchronization command, which outputs the spray gun solenoid valve opening command. The spray gun solenoid valve opening command triggers the compressed air valve to introduce airflow, allowing the spherical tin powder in the powder storage tank to enter the Laval nozzle through the fluidized bed, accelerating adiabatic expansion and outputting a supersonic tin powder particle stream. Then, when the supersonic tin powder particle stream passes through the annular guide ring, the position coordinates of the copper wire are collected in real time by a laser displacement sensor, and the position offset of the copper wire is calculated based on the position coordinates. At the same time, the tilt angle of the guide ring is dynamically adjusted according to the position offset of the copper wire, outputting a spatially oriented tin powder jet. Finally, the spatially oriented tin powder jet bombards the coating surface at the tilt angle of the guide ring, generating a semi-dense tin-plated copper wire. The unembedded tin powder on the surface of the semi-dense tin-plated copper wire is peeled off, and the porosity of the plating surface is detected. At the same time, tin powder is sprayed again according to the porosity to generate a denser tin-plated copper wire. Furthermore, the semi-dense tin-plated copper wire is first blown with compressed air to remove non-embedded tin powder particles from its surface using high-speed airflow, resulting in a clean semi-dense tin-plated copper wire. The surface of the clean semi-dense tin-plated copper wire is then scanned using a microscope, acquiring a 0.1 mm² field-of-view image. After filtering, micropore defects on the surface of the plating layer are extracted. Finally, the porosity is obtained based on the ratio of the total pore area to the field-of-view area, and the real-time porosity value is output. When the real-time porosity value exceeds the porosity threshold, the re-blowing time and re-blowing time are calculated. The spray pressure is adjusted to output a tin powder replenishment control command. Based on this command, a ring-shaped spray gun array is activated to bombard high-porosity areas, resulting in a replenished coating. Finally, the replenished coating is sent to a vacuum adsorption zone where residual tin powder is removed by airflow, producing a denser tin-plated copper wire. The denser tin-plated copper wire is then scanned using X-ray equipment. If the porosity is >0.2% (a critical point set based on the dual guarantee of coating conductivity and mechanical properties), replenishment is performed again; if the porosity is ≤0.2%, a qualified denser tin-plated copper wire is output. The expression for calculating the respray time is: ; in, It's time for a touch-up spray; It is the time-compensated gain coefficient; It is the real-time porosity of the coating surface; It is the porosity threshold; The expression for calculating the supplementary injection pressure is: ; in, It is the pressure for additional spraying; It is a pressure response index; It is the pressure gain coefficient; It should be noted that the porosity threshold is set based on the point at which the coating adhesion suddenly drops. An exemplary value range is (0.28%-0.32%). Experimental data shows that when the porosity exceeds the porosity threshold, the tin-copper interface adhesion drops sharply, and the bending life drops from 6000 cycles to 3500 cycles. At this point, the probability of the pores becoming crack sources is >80%.

[0028] S4. The densified tin-plated copper wire is scanned by a micro-focus CT scanner to generate a three-dimensional point cloud map of the gap. The gap size and normal angle are analyzed in the three-dimensional point cloud map to identify the optimal spraying parameters and generate a passivation film tin-plated copper wire. The dense tin-plated copper wire is scanned by a micro-focus CT scanner, and the strand gap data is collected in real time to generate a three-dimensional point cloud map of the gap. Furthermore, the densified tin-plated copper wires were fixed on a microfocus CT rotary stage. Five-axis linkage calibration was performed using a laser alignment instrument to align the copper wire axis with the center of the rotary stage. Projection scanning was performed using a 50kV / 80μA X-ray source, while a flat panel detector collected the intensity of the penetrating rays to obtain the original CT projection dataset. The original CT projection dataset was then reconstructed using the FDK back projection method to generate a three-dimensional voxel matrix of copper wires. Threshold segmentation was then performed on the three-dimensional voxel matrix of copper wires to extract the gap regions between the copper wires. A triangular mesh was generated using the Marching Cubes algorithm to generate a three-dimensional surface model of the gaps between the copper wires containing 1.25 million triangular facets. Density point sampling (e.g., 10 points / μm²) was performed on the three-dimensional surface model of the gaps between the copper wires. After optimization by Laplacian smoothing filtering, a three-dimensional point cloud map of the gaps with sub-micron precision was generated. It should be noted that the FDK back projection reconstruction method is a cone-beam CT 3D reconstruction method based on filtered back projection. It converts the 2D projection sequence into a 3D voxel matrix through weighted projection data, ramp filtering, and 3D back projection integration. The Marching Cubes method is a mesh generation algorithm that extracts isosurfaces from 3D volume data. It constructs a continuous surface model by traversing voxel elements and connecting triangular facets according to 256 preset topological configurations. Based on the three-dimensional point cloud map of the gap, the gap depth and normal angle of adjacent copper wires are analyzed, and the pressure and angle of the passivation liquid spraying are adjusted according to the gap depth and normal angle of adjacent copper wires to generate pre-cured copper wires. Furthermore, based on the 3D point cloud map of the gap, the minimum Euclidean distance between adjacent copper wire surface points is calculated using a nearest neighbor search algorithm to obtain the gap depth value; simultaneously, the gap normal angle is directly extracted through the orthogonality of the principal direction of the point cloud data distribution; based on the gap depth value, the spraying pressure is calculated using a pressure control formula to output the passivation liquid spraying pressure value; based on the gap normal angle, the nozzle axis alignment is calculated using a nozzle angle compensation formula to output the nozzle angle; based on the passivation liquid spraying pressure value and the nozzle angle, a multi-axis spraying robotic arm is collaboratively controlled to directionally spray passivation liquid onto the copper wire surface, generating a uniformly coated pre-cured copper wire; The actual film thickness of the pre-cured copper wire is detected in real time, and the film thickness deviation is calculated based on the actual film thickness. The expression for calculating the film thickness deviation is: ; in, This is the film thickness deviation value; It is a real-time film thickness measurement value; It is the target film thickness value; Furthermore, the pre-cured copper wire is first placed on an XYZ three-axis positioning platform. An infrared sensor is used to vertically illuminate the surface of the pre-cured copper wire. A beam splitter is used to obtain a stable light intensity value. Based on the stable light intensity value, the transmitted beam is converted into a current signal by photoelectric conversion. The transmitted light intensity voltage signal is then output through a transimpedance amplifier. Next, the transmitted light intensity voltage signal is extracted by phase-locked loop (PLL) and a specific frequency component of the transmitted light intensity signal is extracted by a PLL amplifier. Combined with a pre-calibrated light intensity-absorbance conversion relationship, a characteristic absorbance value is directly output. Simultaneously, based on the characteristic absorbance value, it is converted into a real-time film thickness detection value through a pre-stored calibration curve mapping relationship. Finally, a subtraction operation is performed based on the real-time film thickness detection value to obtain the film thickness deviation value. It should be noted that the pre-stored calibration curve mapping relationship is the correspondence between absorbance and film thickness established through 100 sets of ellipsometer measured data; the pre-calibrated light intensity-absorbance conversion relationship is a deterministic mapping relationship between transmitted light intensity signal and absorbance established through standard sample experiments. Based on the film thickness deviation value, the pre-cured copper wire is compensated by spraying to generate a passivated film tin-plated copper wire. Furthermore, firstly, based on the film thickness deviation value, a flow compensation calculation is performed using a proportional control formula to obtain the passivation liquid flow adjustment amount. Then, the passivation liquid flow adjustment amount is linearly superimposed with the reference flow rate to obtain the corrected spraying flow rate value. Next, based on the corrected spraying flow rate value, a voltage conversion is performed to obtain the piezoelectric valve drive voltage. The piezoelectric valve core displacement is adjusted according to the piezoelectric valve drive voltage to output a spraying valve with a precisely matched opening. Then, the spraying valve with a precisely matched opening is aligned with the surface of the pre-cured copper wire and the passivation liquid is sprayed to generate a uniform passivation layer. Finally, the uniform passivation layer is sent into the hot air field, where the solvent evaporates and cross-links through thermal drive to generate a passivation film tin-plated copper wire. It should be noted that the reference flow rate is the optimal balance between corrosion protection and conductivity of the coating, determined through process validation.

[0029] S5. Collect the real-time value of the tension of the passivated film tin-plated copper wire, compare it with the preset tension threshold, obtain the tension deviation, and convert it into a magnetic powder brake current adjustment command. Adjust the winding motor current according to the magnetic powder brake current adjustment command to obtain a high-performance tin-plated copper stranded wire coil. Based on the passivated film tin-plated copper wire, a three-dimensional voltage signal is collected, and the real-time value of the copper wire travel tension is obtained through vector synthesis calculation. At the same time, the real-time value of the copper wire travel tension is compared with the preset tension threshold to calculate the tension deviation. The expression for calculating the tension deviation is: ; in, It is the tension deviation; It is the real-time value of the copper wire tension. It is a preset tension threshold; Furthermore, firstly, the voltage signals of the passivated tin-plated copper wire in the X / Y / Z axes are acquired in real time using a strain gauge bridge, and the X-axis voltage signal, Y-axis voltage signal, and Z-axis voltage signal are output; then, based on the vector synthesis operation of the X-axis voltage signal, Y-axis voltage signal, and Z-axis voltage signal, the real-time value of the copper wire's traveling tension is obtained; finally, the difference operation is performed between the real-time value of the copper wire's traveling tension and the preset tension threshold to obtain the signed tension deviation. It should be noted that the preset tension threshold is the optimal balance point between the integrity of the copper wire plating and production efficiency, determined through process verification. An exemplary value range is (0.75~0.85). Based on the tension deviation, perform asymmetric proportional control calculations to generate magnetic powder brake current adjustment commands. Furthermore, firstly, based on the tension deviation, a sign voltage signal is extracted using a high-speed voltage comparator, and negative voltage is eliminated by a precision full-wave rectifier circuit to obtain the deviation polarity indicator and the absolute value of the deviation voltage signal. Then, a gain coefficient is selected based on the deviation polarity indicator, and a scalar multiplication operation is performed according to the gain coefficient and the absolute value of the deviation voltage signal to output a current adjustment voltage signal. Then, the current adjustment voltage signal is sampled by a 12-bit ADC (analog-to-digital converter), converted into a 12-bit digital signal, and encapsulated into a CAN bus frame to generate a magnetic powder brake current adjustment command. Adjust the braking torque according to the magnetic powder brake current adjustment command, and obtain the real-time braking torque value; Furthermore, firstly, based on the magnetic particle brake current adjustment command, a 12-bit digital quantity is extracted and converted by a DAC to output the magnetic particle brake drive current; then, the magnetic particle brake drive current generates an electromagnetic field through the brake excitation coil, driving the internal magnetic particles to form a shear chain, and the torque of the brake output shaft acts on the elastic torsion arm, the strain gauge attached to the torsion arm generates a resistance change, the resistance change is converted into a differential voltage signal by a full-bridge circuit, and the torque strain voltage signal is output; then, the torque strain voltage signal is amplified by an instrumentation amplifier and low-pass filtered, and then calibration conversion is performed to output the real-time braking torque value; Based on the real-time braking torque value, the winding tension of the winding motor is dynamically controlled to obtain high-performance tin-plated copper stranded wire coils. Furthermore, firstly, based on the real-time braking torque value, the winding tension value is obtained through the guide wheel tension conversion formula. Simultaneously, a laser Doppler velocimeter is used to collect the scattered light signal of the copper wire motion in real time. Based on the laser Doppler effect, the linear velocity of the winding section is directly detected through the frequency shift characteristics of the scattered light of the copper wire motion, obtaining the real-time linear velocity of the copper wire in the winding section. Based on the real-time linear velocity of the copper wire in the winding section, the dynamic damping force is calculated using the dynamic damping force calculation formula. Next, the difference between the dynamic damping force and the winding tension value is calculated to obtain the net tension value. Then, the difference between the net tension value and the preset tension threshold is calculated to obtain the net tension deviation. Then, the net tension deviation is calculated using the speed compensation formula to obtain the winding machine speed adjustment amount. Simultaneously, a laser rangefinder is used to measure the real-time roll diameter, and the base speed is calculated using the linear velocity conservation formula. The speed adjustment amount is then added to obtain the roll diameter compensation target speed. Finally, based on the roll diameter compensation target speed, a servo driver generates a three-phase drive frequency to generate a high-performance tin-plated copper stranded wire roll. The expression for calculating the target rotational speed for roll diameter compensation is: ; in, It is the target rotational speed for roll diameter compensation; It is the real-time linear speed of the copper wire in the winding section; It is the real-time roll diameter; It is the net tension value; It is the integral term of net tension deviation; It is the time conversion factor; It is the speed proportional gain coefficient; It is the integral gain coefficient of rotational speed; The expression for calculating dynamic damping force is: ; in, It is dynamic damping force; It is the damping force amplitude coefficient; It is a speed sensitivity index; It is the reference linear velocity base value; It should be noted that the laser Doppler effect refers to the shift in the frequency of the laser light scattered by a moving object relative to the incident light. The amount of this shift is proportional to the speed of the object. By detecting this frequency shift, the speed of the object can be accurately determined.

[0030] This embodiment also provides a computer device applicable to the copper wire tinning method for producing tin-plated copper stranded wire, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the copper wire tinning method for producing tin-plated copper stranded wire as proposed in the above embodiment.

[0031] The computer device can be a terminal, comprising a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0032] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the method for tinning copper wire for producing tinned copper stranded wire as proposed in the above embodiments. The storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read Only Memory (EPROM), Programmable Red-Only Memory (PROM), Read-Only Memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk.

[0033] In summary, this invention achieves ordered deposition of tin atoms by controlling the directional growth of tin crystals through magnetic field gradient control, generating a directionally crystalline coating with consistent axial texture. This improves the uniformity of the coating crystal orientation, meeting the stringent uniformity requirements of 5G communication cables. Furthermore, by identifying spraying parameters through 3D point cloud analysis of the gaps and establishing a mapping relationship between the gap morphology and spraying vectors using spatial geometric modeling, the passivation film achieves full coverage within micron-level gaps, eliminating passivation blind zones and extending the coating's salt spray resistance test life to over 2000 hours, meeting the highest protection level.

[0034] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for tinning copper wire used in the production of tin-plated copper stranded wire, characterized in that: include, The copper wire is released into an ionic liquid electrophoresis tank, and after the surface oxides are stripped off by an electric field, it undergoes a three-stage countercurrent rinsing to generate clean copper wire. Clean copper wire is placed in a composite plating bath. The viscosity of the molten tin and the linear velocity of the copper wire are monitored in real time. The magnetic field gradient is calculated, and the directional growth of tin crystals is controlled according to the magnetic field gradient to generate directional crystallized tin-plated copper wire. The surface temperature of the directional crystallized tin-plated copper wire is monitored in real time and compared with the preset temperature threshold to generate a temperature permission trigger signal. The ring array spray gun is triggered to work according to the temperature permission trigger signal to generate dense tin-plated copper wire. The densified tin-plated copper wire is scanned using a micro-focus CT scanner to generate a three-dimensional point cloud map of the gap. The gap size and normal angle are analyzed from the three-dimensional point cloud map to identify the optimal spraying parameters and generate a passivation film tin-plated copper wire. The real-time tension value of the passivated film-plated tin copper wire is collected and compared with the preset tension threshold to obtain the tension deviation. This deviation is then converted into a magnetic powder brake current adjustment command. The current of the winding motor is adjusted according to the magnetic powder brake current adjustment command to obtain a high-performance tin-plated copper stranded wire coil.

2. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 1, characterized in that: The steps for generating clean copper wire are as follows: A copper wire is placed in an ionic liquid bath, the thickness of the oxide layer is monitored, and the intensity of the DC electric field is dynamically adjusted according to the thickness of the oxide layer to generate a pure copper substrate. The pure copper substrate is placed in the first rinsing tank, the conductivity value of the rinsing solution is monitored, and the countercurrent water pressure is controlled according to the conductivity value of the rinsing solution to generate primary rinsing copper wire. The primary rinsed copper wire is immersed in the second ultrasonic rinsing tank, the ion concentration is monitored, and the ultrasonic power is adjusted according to the ion concentration to generate the intermediate rinsed copper wire. Monitor the surface moisture content of the intermediate rinse copper wire, and perform hot air gradient purging based on the surface moisture content to generate clean copper wire.

3. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 1, characterized in that: The steps for calculating the magnetic field gradient are as follows: Clean copper wire is placed into a composite plating bath, and the viscosity of the molten tin is detected in real time by an online viscometer and compared with a preset viscosity threshold to generate a rheological correction command. The power of the surface acoustic wave device is increased according to the rheological correction command to generate micro vortices and produce molten tin. The linear velocity of the clean copper wire is collected in real time, and the magnetic field gradient is calculated using the velocity control gradient method.

4. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 3, characterized in that: The steps for generating the directional crystallized tin-plated copper wire are as follows: By suppressing the growth direction of tin crystals according to the magnetic field gradient, a directional crystallization environment is generated; A uniform coating is applied to copper wire using molten tin and a directional crystallization environment. The uniformly coated copper wire is then sequentially fed into a three-stage cooling zone to generate directional crystallized tin-plated copper wire.

5. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 1, characterized in that: The generation of the temperature permission trigger signal refers to the process of acquiring real-time temperature data of the directional crystallized tin-plated copper wire using an infrared thermal imager and comparing it with a preset temperature threshold to generate a temperature permission trigger signal.

6. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 1, characterized in that: The specific steps for generating the dense tin-plated copper wire are as follows: According to the temperature-permitted trigger signal, the ring array spray gun is triggered to spray tin powder onto the coating surface of the directional crystallized tin-plated copper wire to generate semi-dense tin-plated copper wire. The unembedded tin powder on the surface of the semi-dense tin-plated copper wire is peeled off, and the porosity of the plating surface is detected. At the same time, tin powder is sprayed again according to the porosity to generate a denser tin-plated copper wire.

7. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 1, characterized in that: The generation of the three-dimensional point cloud map of the gap refers to scanning the dense tin-plated copper wire with a micro-focus CT scanner and collecting the strand gap data in real time to generate the three-dimensional point cloud map of the gap.

8. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 1, characterized in that: The analysis of gap size and angle, identification of optimal spraying parameters, and generation of passivation film tin-plated copper wire are carried out through the following specific steps. Based on the three-dimensional point cloud map of the gap, the gap depth and normal angle of adjacent copper wires are analyzed, and the pressure and angle of the passivation liquid spraying are adjusted according to the gap depth and normal angle of adjacent copper wires to generate pre-cured copper wires. The actual film thickness of the pre-cured copper wire is detected in real time, and the film thickness deviation is calculated based on the actual film thickness. The pre-cured copper wire is compensated by spraying according to the film thickness deviation value to generate a passivated tin-plated copper wire.

9. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 1, characterized in that: The steps for converting the current into a magnetic particle brake control command are as follows: Based on the passivated film tin-plated copper wire, a three-dimensional voltage signal is collected, and the real-time value of the copper wire travel tension is obtained through vector synthesis calculation. At the same time, the real-time value of the copper wire travel tension is compared with the preset tension threshold to calculate the tension deviation. Based on the tension deviation, an asymmetric proportional control operation is performed to generate a magnetic powder brake current adjustment command.

10. The method for tinning copper wire for producing tin-plated copper stranded wire as described in claim 1, characterized in that: The steps for obtaining high-performance tin-plated copper stranded wire are as follows. Adjust the braking torque according to the magnetic powder brake current adjustment command, and obtain the real-time braking torque value; Based on the real-time braking torque value, the winding tension of the winding motor is dynamically controlled to obtain high-performance tin-plated copper stranded wire coils.

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