A manufacturing method of a conductive plate and a rectangular terminal

Abstract

The present invention discloses a method for manufacturing a conductive plate and a rectangular terminal, which have the advantages of synergistically improving high conductivity and mechanical strength, effectively controlling grain boundary impurities, and enhancing the reliability of the coating bonding. The present invention uses a composite powder plasma ball milling combined with a stepped hot pressing process, coupled with three-way forging and grain boundary purification treatment, to significantly improve mechanical strength while maintaining high conductivity and effectively suppress the enrichment of grain boundary impurities. The advantages are synergistically improving high conductivity and mechanical strength, effectively controlling grain boundary impurities, and enhancing the reliability of the coating bonding.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical connector manufacturing, and in particular to a manufacturing method of a conductive plate and a rectangular terminal. Background Art

[0002] In the field of electrical connections, copper-based conductive plates are widely used due to their excellent conductivity, but existing manufacturing technologies still have significant defects: First, in terms of material properties, the pure copper matrix lacks mechanical strength to ensure high conductivity, and traditional strengthening methods such as adding metal oxides can improve strength but significantly degrade conductivity; second, there are three major difficulties in process control: high-activity copper powder is prone to surface oxidation during mixing and sintering, resulting in impurity enrichment at the grain boundaries and causing large fluctuations in resistivity; the temperature and pressure curves are not accurately matched during hot pressing, which can easily cause internal microcrack defects; third, in terms of surface treatment, due to the difference in thermal expansion coefficients between conventional coatings and the copper matrix, interface peeling is prone to occur under temperature cycling conditions.

[0003] Among existing improvements, carbon nanotube reinforcement technology creates conductive barriers due to dispersion issues. While high-temperature sintering can increase density, it leads to abnormal grain growth, severely impacting the material's fatigue resistance. Therefore, a comprehensive manufacturing solution is urgently needed that simultaneously addresses conductivity, strength, process stability, and coating reliability.

[0004] In view of the above problems, the existing technology is in urgent need of improvement. Summary of the Invention

[0005] (1) Technical issues to be resolved

[0006] To solve the above problems, the present invention proposes a method for manufacturing a conductive plate and a rectangular terminal, which have the advantages of synergistic improvement of high conductivity and mechanical strength, effective control of grain boundary impurities, and enhanced coating bonding reliability.

[0007] (2) Technical solution

[0008] A method for manufacturing a conductive plate of the present invention, wherein the formula ratio of the conductive plate includes:

[0009] Conductive matrix 98.9-99.6%, graphene nanosheets 0.3-0.8%, Ag@Sn core-shell particles 0.1-0.2%, grain boundary purification additives ≤0.05%,

[0010] The preparation process of the conductive plate includes the following steps:

[0011] S100, plasma ball milling oxygen-free copper powder, graphene nanosheets, and Ag@Sn core-shell particles under inert gas protection to obtain composite powder;

[0012] S200, place the composite powder in a mold and press it in a stepwise manner at a pressure of 80-120 MPa:

[0013] The first stage: 400±10℃ for 30min,

[0014] The second stage: reduce the temperature to 250±10℃ at 10℃ / min and maintain the pressure for 1h;

[0015] S300, perform three-way alternating forging on the hot pressed billet at room temperature, with a single deformation of 15-25%, a total deformation of ≥60%, and the forging direction extending horizontally to the left and right sides;

[0016] S400, annealing at 300±10℃ for 1-2h in H2 / N2 mixture, where the volume proportion of H2 is 3-5%;

[0017] S500, stamping into a conductive plate shape, processing mounting holes at both ends thereof, and finally preparing a composite conductive coating on the surface, the composite conductive coating comprising a tin matrix and a dispersed strengthening phase.

[0018] In the present invention, the dispersed strengthening phase is selected from any one of the following:

[0019] Boron element, present in the form of Ni-B alloy, with a boron content of 6-8wt%;

[0020] Silver-tin alloy particles, Ag content 65-75wt%;

[0021] Graphene nanosheets, lateral size ≤ 200 nm.

[0022] In the present invention, when the strengthening phase is boron, a pulse electroplating process is used with pulse parameters: Ton=5-15ms, Toff=40-60ms, and a peak current density of 6-10A / dm²;

[0023] When the strengthening phase is silver-tin alloy particles, the chemical plating process is adopted, the plating temperature is 70-80℃, and the pH value is 8.5-9.5;

[0024] When the reinforcing phase is graphene nanosheets, ultrasonic assisted electroplating is used with an ultrasonic frequency of 35-45kHz and a power density of 250-350W / m³.

[0025] In the present invention, the composite conductive coating is a multi-layer structure, comprising:

[0026] Bottom layer, pure tin or nickel-phosphorus alloy layer, thickness 0.3-1.0μm;

[0027] The functional layer, the composite layer containing the dispersed reinforcement phase, has a thickness of 0.2-0.5 μm.

[0028] In the present invention, the grain boundary purification additive is trimethyl borate or triethyl phosphate, the addition amount is 0.02-0.04%, and it is added simultaneously during plasma ball milling.

[0029] The present invention also includes:

[0030] S600. A wiring window is punched in the middle of the conductive plate, and anti-slip grooves are processed on the contact surface. The anti-slip grooves have a groove depth of 20-50 μm and a groove pitch of 0.2-0.5 mm.

[0031] In the present invention, the anti-slip lines include:

[0032] Radial grooves are provided in the contact area of ​​the wire clamping frame, wherein the groove depth of the radial grooves is 30-50 μm and the extension angle is 60°-90°;

[0033] The cross grid pattern is arranged near the through hole, the grid size of the cross grid pattern is 0.3×0.3 mm, and the protrusion height is 20-30 μm.

[0034] Another rectangular terminal of the present invention comprises a housing, a connector disposed within the housing, and a conductive plate obtained by the method for manufacturing a conductive plate according to any one of the above technical solutions, wherein the connectors are disposed at the left and right ends of the conductive plate, respectively, for connecting to an external circuit.

[0035] Both ends of the conductive plate are provided with mounting holes and studs passing through the mounting holes, and the connecting head is sleeved on the studs.

[0036] In the present invention, a cover is rotatably provided on the housing, and the cover is a semi-enclosed structure for shielding and protecting the connector;

[0037] One end of the cover shell is provided with a protrusion, and both ends of the shell are provided with grooves that match the protrusion. The cover shell and the shell are clamped together through the limiting cooperation of the protrusion and the groove.

[0038] Another rectangular terminal of the present invention comprises a housing, a connector disposed within the housing, and a conductive plate obtained by the method for manufacturing a conductive plate according to any one of the above technical solutions, wherein the connectors are disposed at the left and right ends of the conductive plate, respectively, for connecting to an external circuit.

[0039] Both ends of the conductive plate are provided with mounting holes and studs arranged through the mounting holes. The connecting head is sleeved on the studs. The conductive plate is provided with a wiring window and anti-slip patterns.

[0040] (3) Beneficial effects

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] The manufacturing method of a conductive plate and a rectangular terminal in the present invention use a composite powder plasma ball milling combined with a step hot pressing molding process, coordinated with three-way forging and grain boundary purification treatment, to significantly improve the mechanical strength while maintaining high conductivity, effectively inhibit the enrichment of grain boundary impurities, and have the advantages of synergistic improvement of high conductivity and mechanical strength, effective control of grain boundary impurities, and enhanced coating bonding reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] Figure 1 The first scheme is a schematic diagram of the overall process of the manufacturing method of the conductive plate;

[0045] Figure 2 The second scheme is a schematic diagram of the overall process of the manufacturing method of the conductive plate;

[0046] Figure 3 It is a schematic diagram of the three-dimensional structure of the rectangular terminal;

[0047] Figure 4 It is a schematic diagram of the internal structure of the rectangular terminal;

[0048] Figure 5 Schematic diagram of the exploded structure of the conductive plate and the connector.

[0049] 10. Housing, 101. Groove, 20. Conductive plate, 201. Stud, 30. Connector, 40. Cover, 401. Protrusion. DETAILED DESCRIPTION

[0050] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0051] Copper-based conductive plates are widely used in the field of electrical connections due to their excellent electrical conductivity, but they have long suffered from problems such as insufficient mechanical strength, easy oxidation during processing, and poor coating adhesion. Traditional strengthening methods often lead to a decrease in conductivity when improving material strength. During the mixed sintering process, copper powder oxidizes to form grain boundary impurities. The mismatch of hot pressing process parameters causes internal microcracks. The difference in thermal expansion coefficient between the surface coating and the substrate causes insufficient bonding. In a certain power equipment connector manufacturing scenario, a conductive plate is needed that maintains structural stability and low surface contact resistance under long-term current shocks. However, existing products are prone to problems such as coating peeling and microcrack propagation in high temperature and high humidity environments.

[0052] To address these issues, researchers discovered that traditional single-phase reinforcement methods couldn't simultaneously meet both conductivity and strength requirements. They therefore attempted to improve material properties through multi-scale synergistic reinforcement. To address grain boundary impurities, they proposed introducing a grain boundary purification mechanism during the powder processing stage. To address insufficient coating adhesion, they developed a composite coating structure design. By adjusting the temperature gradient and pressure distribution during the hot pressing process, they optimized the billet density. Ultimately, they developed a technical approach centered around multi-component composite reinforcement, combined with staged forming and interface optimization.

[0053] Therefore, refer to Figure 1-Figure 2 , this application proposes a method for manufacturing a conductive plate, the formula ratio of the conductive plate includes:

[0054] Conductive matrix 98.9-99.6%, graphene nanosheets 0.3-0.8%, Ag@Sn core-shell particles 0.1-0.2%, grain boundary purification additives ≤0.05%,

[0055] The preparation process of the conductive plate includes the following steps:

[0056] S100, plasma ball milling: plasma ball milling oxygen-free copper powder, graphene nanosheets, and Ag@Sn core-shell particles under inert gas protection to obtain composite powder.

[0057] A conductive matrix refers to a metal matrix that serves as the material's primary conductive pathway. Oxygen-free copper powder can be used as the raw material, and conductivity is ensured by controlling the oxygen content. Graphene nanosheets refer to carbon materials with a two-dimensional structure that can be embedded in a metal lattice to form a reinforced network. Ag@Sn core-shell microparticles are composite particles with a silver core coated with a tin layer, which form a liquid phase during sintering to promote densification. Grain boundary purification additives are compounds that can adsorb impurities at grain boundaries. Their simultaneous addition during ball milling can effectively remove impurities. Plasma ball milling refers to a mechanical alloying process performed in a high-energy plasma environment, enabling uniform dispersion at the nanometer level.

[0058] Specifically, oxygen-free copper powder as the matrix material mitigates the effects of oxides on conductivity. Graphene nanosheets form a two-dimensional conductive network within the matrix. The Ag@Sn core-shell particles generate a liquid phase during hot pressing to promote densification. Annealing in a reducing atmosphere eliminates processing stresses. The composite coating utilizes a multilayered design to match the thermal expansion coefficient of the substrate. Mounting holes are machined using a step-by-step stamping process to prevent edge cracking.

[0059] Furthermore, the grain boundary purification additive is trimethyl borate or triethyl phosphate, the addition amount is 0.02-0.04%, and it is added simultaneously during plasma ball milling.

[0060] Grain boundary purification additives refer to compounds used to remove impurity elements from grain boundaries during material processing. Specifically, this can be achieved using trimethyl borate or triethyl phosphate. These two esters decompose under high temperature conditions to generate active boron or phosphorus elements, which react with impurities such as oxygen and sulfur in the copper matrix. The addition amount in the range of 0.02-0.04% refers to the mass proportion of the additive in the formula. Specifically, it can be achieved by, for example, a range of 0.02% to 0.04%. It can effectively purify the grain boundaries and avoid excessive residues that affect the conductive properties. Synchronous addition during plasma ball milling refers to placing the additive and the raw material powder together in the grinding container during the ball milling process. Specifically, this can be achieved by mechanical alloying treatment under an inert gas protection environment so that the additive is evenly dispersed in the composite powder.

[0061] During the plasma ball milling process, trimethyl borate or triethyl phosphate undergoes thermal decomposition due to high-energy collisions. The released boron or phosphorus reacts chemically with impurities such as oxides and sulfides on the copper powder surface to form low-melting-point borate or phosphate compounds. These compounds preferentially migrate to the grain boundaries during subsequent hot pressing, forming a liquid film that envelops the impurity particles, effectively preventing impurity accumulation at the grain boundaries. By controlling the addition amount to, for example, 0.02% to 0.04%, the impurity elements in the raw materials are fully consumed while avoiding lattice distortion of the conductive matrix caused by excessive addition.

[0062] S200, step pressing: Place the composite powder in a mold and press it in a step-by-step process with a pressure of 80-120 MPa.

[0063] The first stage: 400±10℃ for 30min,

[0064] The second stage: reduce the temperature to 250±10℃ at 10℃ / min and maintain the pressure for 1h.

[0065] Step cooling pressing refers to a molding process that controls temperature and pressure in stages, which is beneficial to eliminating internal stress.

[0066] S300, three-way forging: The hot pressed billet is subjected to three-way alternating forging at room temperature, with a single deformation of 15-25%, a total deformation of ≥60%, and the forging direction extending horizontally to the left and right sides.

[0067] Plasma ball milling achieves nanoscale dispersion of components in an inert atmosphere, while step-cooling and pressing control the material's phase transitions through temperature gradients. Three-way alternating forging evenly distributes grains in multiple directions. Three-way alternating forging, a process that sequentially applies deformation forces in three orthogonal directions, refines the grain structure.

[0068] S400, Annealing: Annealing at 300±10℃ for 1-2h in H2 / N2 mixture, where the volume proportion of H2 is 3-5%.

[0069] This step is the core of material performance optimization, eliminating stress generated during machining. Dislocation stresses generated during three-way forging are released through recrystallization, preventing subsequent cracking. H2 reduces grain boundary oxides, and combined with grain boundary purification additives, low-melting-point boron / phosphorus compounds are generated, removing impurities and reducing grain boundary oxygen content to ≤8ppm.

[0070] 300°C is close to the copper recrystallization temperature of 200°C, inhibiting excessive grain growth and balancing strength and conductivity. The average grain size is approximately 100-200nm. The core value of annealing at 300°C lies in precisely controlling the microstructural evolution of the copper matrix. The theoretical recrystallization temperature of copper is approximately 200°C. When the annealing temperature is set at 300°C—higher than the recrystallization temperature but far below the copper melting point of 1083°C—two competing mechanisms occur simultaneously within the material:

[0071] On the one hand, the distorted lattice formed by cold working obtains enough energy to initiate recrystallization, and the dislocations are rearranged to form new equiaxed grains;

[0072] On the other hand, the grain boundary migration movement of newly formed grains is controlled within a moderate range.

[0073] The clever choice of this temperature window stabilizes the grain size in the nanoscale range of 100-200nm: if the temperature is lower than 280℃, the driving force for recrystallization is insufficient, and the residual work-hardening phase will cause a conductivity loss of more than 5%; if it exceeds 320℃, the grain boundary migration rate increases exponentially, and the grains will quickly coarsen to more than 250nm. At this time, although the plasticity is improved, the total grain boundary area is sharply reduced, which increases the probability of electron scattering. More importantly, the fine grain strengthening effect disappears, and the material yield strength plummets from 450MPa to below 300MPa.

[0074] Grain sizes of 100-200nm achieve a perfect balance of strength and conductivity. From a strength perspective, nanocrystals significantly enhance mechanical properties through the Hall-Petch effect—for every 100nm of grain refinement, the yield strength increases by approximately 100 MPa. At this point, a 200nm grain has a strength of approximately 220 MPa compared to a 20μm grain of conventional electrolytic copper, resulting in a significant strength gain. From a conductivity perspective, this size range circumvents the quantum size effect of nanomaterials: when the grain size is larger than the electron mean free path (approximately 40nm for pure copper), the effect of grain boundary scattering on resistivity is significantly reduced. Experimental measurements show that the resistivity of 100-200nm grains is only 3-5% higher than that of single-crystal copper, while the resistivity of grains below 50nm increases by over 15%. Even more ingenious is that the 4% H2 / N2 mixed gas introduced in the S400 stage activates a dual purification mechanism at 300°C: hydrogen reduces the Cu2O at the grain boundaries to water vapor. Simultaneously, the boron atoms produced by the decomposition of trimethyl borate added in the ball milling stage form low-melting-point borides with impurities such as sulfur and selenium. These liquid compounds are squeezed out of the material system under the capillary action of the grain boundaries, reducing the impurity oxygen content of the grain boundaries from 150ppm to below 8ppm. For every 10ppm reduction in oxygen content, the conductivity can be increased by 0.5%IACS and the grain boundary bonding strength can be increased by 8%.

[0075] This coordinated optimization of the microstructure directly determines the macroscopic performance of the terminal. Under a current load of 150A, the resistance loss of the low-impurity nanocrystalline copper substrate is only 3.2W. Compared with the coarse-grained copper substrate, the content of the substrate is reduced, and the corresponding operating temperature rise is reduced from 45K to 38K. Crucially, the high grain boundary density of the nanocrystals provides an ideal substrate for subsequent plating. The increase in the number of grain boundaries per unit area increases the density of bonding sites at the plating / substrate interface by three times. The bonding strength of the Ni-B plating reaches 52N, which is 48% higher than that of the coarse-grained substrate (35N), completely solving the problem of plating peeling under high current impact. All these performance gains rely on the precise determination of the grain size by 300℃ annealing: it is like a skilled micro-sculptor, carving out a perfect crystal structure at the nanoscale that can both pass current and resist mechanical stress.

[0076] S500, coating: stamping into a conductive plate shape, and processing mounting holes on the left and right ends thereof, and finally preparing a composite conductive coating on the surface, the composite conductive coating comprising a tin matrix and a dispersed strengthening phase.

[0077] A composite conductive coating is a surface treatment structure composed of different functional layers, including a conductive matrix and a reinforcement phase. The dispersed reinforcement phase is selected from any of the following: boron in the form of a Ni-B alloy with a boron content of 6-8wt%; silver-tin alloy particles with an Ag content of 65-75wt%; and graphene nanosheets with a lateral size of ≤200nm.

[0078] Boron element in the form of Ni-B alloy means that the boron element is distributed in the coating through the chemical form of nickel-boron alloy. Specifically, it can be achieved by nickel-boron co-deposition in the electroplating process. By controlling the boron content, the hardness and bonding strength of the coating can be adjusted.

[0079] The Ag content of the silver-tin alloy particles of 65-75wt% refers to the mass ratio of silver to tin in the alloy, which can be achieved by controlling the composition of the plating solution and the reduction conditions in the chemical plating process. This ratio can balance the conductivity and the density of the coating.

[0080] The lateral size of the graphene nanosheet ≤ 200 nm refers to the planar extension length of the nanosheet in the coating, which can be achieved by regulating the dispersion parameters in the ultrasonic-assisted electroplating process. This size range can avoid stress concentration in the coating.

[0081] When Ni-B alloy is selected as the strengthening phase, the boron element is embedded in the nickel matrix in the form of a solid solution, improving the deformation resistance of the coating through lattice distortion; when silver-tin alloy particles are selected, the high silver content particles act as conductive network nodes, enhancing the current-carrying capacity of the coating; when graphene nanosheets are selected, their nanoscale lateral dimensions can reduce the crack propagation path inside the coating.

[0082] When the reinforcing phase is boron, a pulse electroplating process is used, and the pulse parameters include a flow time of 5-15 milliseconds, an off-flow time of 40-60 milliseconds, and a peak current density of 6-10 amperes per square decimeter; when the reinforcing phase is silver-tin alloy particles, a chemical plating process is used, the plating solution temperature is controlled at 70-80 degrees Celsius, and the pH value is adjusted to 8.5-9.5; when the reinforcing phase is graphene nanosheets, ultrasonic-assisted electroplating is used, the ultrasonic frequency is set to 35-45 kilohertz, and the power density is controlled at 250-350 watts per cubic meter.

[0083] Pulse plating refers to an electroplating method that periodically switches the current on and off. This can be achieved using a pulse power supply device, where the metal ion deposition process is controlled by adjusting the on-time and off-time of the current. Chemical plating refers to a method of depositing a metal coating on a substrate surface through an autocatalytic reaction. This can be achieved using a plating solution system containing a reducing agent, where the reaction rate is adjusted by controlling the temperature and pH value of the plating solution. Ultrasonic-assisted plating refers to a method of applying ultrasonic vibrations during the electroplating process. This can be achieved by coupling an ultrasonic generator to an electroplating tank, where the flow of the plating solution and the dispersion of particles are promoted by setting the ultrasonic frequency and power density.

[0084] Specifically, when boron is used as a reinforcing phase, pulse plating uses an alternating on-off current pattern to uniformly distribute the boron in the coating as a Ni-B alloy. When silver-tin alloy particles are used, electroless plating embeds the alloy particles into the tin matrix through a reduction reaction in the plating solution under constant temperature conditions. The alkaline pH of the plating solution is conducive to silver-tin co-deposition. For the graphene nanosheet reinforcement phase, the cavitation effect generated by ultrasound can prevent nanosheet aggregation while promoting their directional alignment in the coating.

[0085] Furthermore, the composite conductive coating is a multi-layer structure, including a bottom layer, a pure tin or nickel-phosphorus alloy layer, with a thickness of 0.3-1.0 μm; and a functional layer, a composite layer containing a dispersed strengthening phase, with a thickness of 0.2-0.5 μm.

[0086] A composite conductive coating refers to a surface treatment structure formed by the superposition of different functional layers. It can be achieved by depositing different materials in stages using electroplating or chemical plating processes. The layered design balances the bonding strength and conductive properties between the coating and the substrate.

[0087] Among them, the bottom layer refers to the transition layer in direct contact with the substrate, which can be specifically realized by using pure tin or nickel-phosphorus alloy as the material. The pure tin layer improves the bonding strength by reducing the interface stress, and the nickel-phosphorus alloy layer inhibits grain boundary diffusion through the amorphous structure.

[0088] Among them, the functional layer refers to a functional coating that carries a reinforcing phase. Specifically, it can be achieved by using a composite coating containing boron elements, silver-tin alloy particles or graphene nanosheets, which improves conductivity and wear resistance by dispersing the reinforcing phase.

[0089] Specifically, the base layer first forms a dense transition layer on the substrate surface. Pure tin mitigates thermal expansion differences through ductility, and nickel-phosphorus alloy strengthens interfacial bonding through chemical bonding. The functional layer is then deposited on the base layer. The reinforcing phase is evenly dispersed in the tin matrix. Boron enhances hardness through solid solution strengthening. Silver-tin alloy particles reduce contact impedance through low resistance. Graphene nanosheets enhance carrier mobility through their two-dimensional structure. The multilayer structure reduces stress concentration between layers through gradient transitions while maintaining the continuity of the conductive path.

[0090] S600, grain processing: punching a connection window in the middle of the conductive plate, and processing anti-skid grains on the contact surface. The depth of the anti-skid grains is 20-50 μm, and the pitch is 0.2-0.5 mm.

[0091] The wiring window refers to the hollow area formed in the middle of the conductive plate through a stamping process. It can be achieved by die punching or laser cutting. This area is used to expose the internal conductive structure to facilitate wiring operations or inspections.

[0092] Among them, the anti-slip pattern refers to the surface microstructure formed on the contact surface of the conductive plate, which can be achieved by roll forming or chemical etching. The ratio of the pattern depth to the pattern pitch is controlled in the range of 1:4 to 1:10 to balance the friction coefficient and contact area.

[0093] Specifically, the wiring window is stamped in the uniformly stressed center of the conductive plate, using a step-by-step stamping process to minimize substrate deformation. The anti-slip pattern is applied after the conductive plate is plated, using multi-axis machining equipment to control the pattern orientation. The matching relationship between pattern pitch and depth is achieved by adjusting the tool feed speed and pressure. While the pattern is being formed on the plated surface, the interface between the coating and the substrate is preserved to prevent delamination of the coating due to machining.

[0094] Compared to existing technologies, traditional conductive plates lack wiring windows, requiring additional holes for installation or compromising the integrity of the coating. Existing anti-slip structures often use simple grooves, which can lead to stress concentrations due to an imbalance in the pitch-to-depth ratio. This solution optimizes the window position and pattern parameters to improve installation convenience while maintaining the stability of the coating structure.

[0095] Furthermore, the anti-slip texture includes:

[0096] Radial grooves are provided in the contact area of ​​the wire clamping frame, wherein the groove depth of the radial grooves is 30-50 μm and the extension angle is 60°-90°;

[0097] The cross grid pattern is arranged near the through hole, the grid size of the cross grid pattern is 0.3×0.3 mm, and the protrusion height is 20-30 μm.

[0098] Radial grooves are linear grooves radiating outward from the center of the cable clamp. These grooves are created using laser micro-engraving or precision stamping. Their angled extension creates multi-directional frictional resistance, preventing cable displacement under vibration. A cross-grid pattern is a regular pattern of interlaced micro-protrusions. This pattern is achieved using chemical etching or mechanical embossing. This grid-like structure disperses stress across the contact surface, preventing cracks in the coating caused by stress concentration.

[0099] Radial grooves with specific extension angles are arranged in the contact area of ​​the clamping frame. When the external cable is crimped, the groove edges form multiple points of contact, and the lateral resistance generated by the geometric angles enhances clamping stability. A cross-grid pattern is placed around the through-hole, and the mechanical interlocking effect between the grid protrusions and the base plating reduces the risk of plating delamination at the through-hole edges due to assembly stress. The combination of these two patterns creates a graded anti-slip structure on the contact surface, balancing anti-slip performance under dynamic loads with the stress distribution required for static assembly.

[0100] Compared to existing technologies, traditional anti-slip patterns often use a single form of parallel stripes or dotted protrusions, which are prone to unidirectional slippage under vibration conditions and lack targeted protection around the through-holes. This solution uses the synergistic effect of radial grooves and cross-grid patterns to form a multi-dimensional anti-slip system in key contact areas, improving the cable connection's vibration resistance while effectively protecting the integrity of the coating in stress concentration areas.

[0101] Example 1

[0102] The formula ratio of the conductive plate in this disclosure is:

[0103] 99.2% oxygen-free copper powder, 0.5% graphene nanosheets, 0.2% Ag@Sn core-shell particles, and 0.04% trimethyl sulfate, of which the lateral size of the graphene nanosheets is 150nm and the Ag core accounts for 70%.

[0104] Process flow:

[0105] S100, plasma ball mill:

[0106] Oxygen-free copper powder, graphene nanosheets, Ag@Sn core-shell particles, and trimethyl sulfate were plasma ball-milled into composite powders according to the component ratios in the above formula under the protection of argon gas. The power of the plasma ball mill was 5 kW, the ball-to-material ratio was 10:1, and the ball milling time was 2 h. The particle size of the final composite powder was required to be less than or equal to 1 μm.

[0107] S200, step suppression:

[0108] The composite powder obtained in the above steps is placed in a mold and pressed under a pressure of 100 MPa by stepwise cooling:

[0109] The first stage: keep the temperature at 400℃ for 30min until the Sn shell melts and densifies.

[0110] The second stage: reduce the temperature to 250℃ at 10℃ / min and maintain the pressure for 1h to eliminate thermal stress;

[0111] S300, three-way forging:

[0112] The hot pressed blank was subjected to X / Y / Z three-axis alternating forging three times at room temperature, with a single deformation of 20% and a total deformation of 75%, until the grain size was refined to 0.8μm;

[0113] S400, annealing:

[0114] Annealing was performed at 300 °C for 1.5 h in a H2 / N2 mixture, where the volume proportion of H2 was 4%.

[0115] S500, coating:

[0116] The bottom layer is a chemically plated nickel-phosphorus alloy layer with a thickness of 0.5μm. The functional layer is a pulse-plated Ni-B alloy with a boron content of 7%. The pulse parameters are Ton=10ms, Toff=50ms, and the peak current density is 8A / dm².

[0117] S600, grain processing:

[0118] A wiring window is punched in the middle of the conductive plate, and anti-slip grooves are processed on the contact surface. The radial grooves have a depth of 40 μm and an extension angle of 70°. The grid size of the cross grid pattern is 0.3×0.3 mm and the protrusion height is 25 μm.

[0119] Test items Example 1 Control group (traditional process) Electrical conductivity 101.2%IACS 98.5%IACS tensile strength 362MPa 295MPa Coating adhesion 16.3MPa 7.1MPa 1000 plug-in and pull-out resistance fluctuation ±1.2% ±8.7%

[0120] Example 2

[0121] Compared with Example 1, the formula ratio of the conductive plate in the present disclosure is:

[0122] Ag@Sn core-shell particles 0.25%, the rest are the same as in Example 1,

[0123] The difference between the process adjustment and Example 1 is:

[0124] Step S600 is omitted.

[0125] Example 3

[0126] Compared with Example 1, the formula ratio of the conductive plate in the present disclosure is:

[0127] The graphene content was increased to 0.7%, the grain boundary cleaner was omitted, and the rest was the same as in Example 1.

[0128] The difference between the process adjustment and Example 1 is:

[0129] S500, coating:

[0130] There is no bottom transition layer, only a single layer of ultrasonically electroplated graphene, where the electroplating frequency is 40kHz and the power density parameter is 300W / m³.

[0131] Example 4

[0132] The formula ratio of the conductive plate in this disclosure is the same as that in Example 1.

[0133] The difference between the process adjustment and Example 1 is:

[0134] S200, step suppression:

[0135] The first stage: the holding temperature is 350℃.

[0136] Example 5

[0137] The formula ratio of the conductive plate in this disclosure is the same as that in Example 1.

[0138] The difference between the process adjustment and Example 1 is:

[0139] S400, annealing:

[0140] H2 accounts for 8% of the volume.

[0141] Example 6

[0142] The formula ratio of the conductive plate in this disclosure is the same as that in Example 1.

[0143] The difference between the process adjustment and Example 1 is:

[0144] S300, three-way forging:

[0145] The hot pressed billet is subjected to only Y-axis unidirectional forging at room temperature, with a total deformation of 60%.

[0146] Example 7

[0147] The formula ratio of the conductive plate in this disclosure is:

[0148] Oxygen-free copper powder 99.25%, graphene nanosheets 0.65%, Ag@Sn core-shell particles 0.05%, trimethyl sulfate 0.05%.

[0149] The process steps are the same as those in Example 1.

[0150] Example 8

[0151] The formula ratio of the conductive plate in this disclosure is:

[0152] Electrolytic copper powder 99.2%, graphene nanosheets 0.5%, Ag@Sn core-shell particles 0.2%, trimethyl sulfate 0.1%.

[0153] The process steps are the same as those in Example 1.

[0154] Example Electrical conductivity (%IACS) Tensile strength (MPa) Coating adhesion (MPa) 1000 plug-in and pull-out resistance fluctuation Cost index (based on 1) Major flaws 1 101.2 362 16.3 ±1.2% 1.00 / 2 101.5 360 16.0 ±5.3% 0.98 No anti-slip texture, poor resistance to fretting wear 3 100.5 355 9.8 ±1.5% 0.95 No bottom transition layer, low coating bonding strength 4 96.0 285 15.8 ±1.3% 1.00 Insufficient pressing temperature and low density 5 100.8 210 15.5 ±1.8% 1.00 Low strength due to hydrogen embrittlement 6 99.8 340 15.9 ±1.3% 1.00 Anisotropy 7 99.8 285 10.2 ±1.5% 1.00 Insufficient Ag@Sn and poor density 8 100.1 350 15.8 ±1.3% 0.60 Magazine residue is slightly higher, but the cost is low

[0155] Key performance analysis:

[0156] 1. The golden balance between conductivity and strength

[0157] Example Conductivity advantage Strength advantage Balance defects 1 101.2% IACS (graphene network + low-oxygen grain boundaries) 362MPa (three-way forging fine grain strengthening) / 2 Increased by 0.3% (Ag@Sn increased) Decreased by 0.5% (Ag enrichment and slight softening) Resistance fluctuation worsened by 342% 7 Decreased by 1.4% (hole-scattered electrons) Decreased by 21.3% (hole stress concentration) Insufficient density 8 Decreased by 1.1% (impurity lattice distortion) Decreased by 3.3 (impurities weakened grain boundaries) Sacrificing performance for cost

[0158] The 0.5% graphene and 0.2% Ag@Sn in Example 1 form a dual channel. The graphene constructs a high-speed electron path to improve the carrier mobility, and the Ag@Sn liquid phase fills the grain boundary to reduce the porosity.

[0159] In contrast, while Example 2 saw a slight increase in conductivity to 101.5% IACS due to the increase in Ag@Sn to 0.25%, the excessive Ag enrichment led to grain boundary softening, resulting in a drop in strength to 360 MPa. More seriously, the lack of the anti-slip pattern worsened the plug-in resistance fluctuation to ±5.3%, a 342% increase compared to Example 1. In Example 7, due to the reduction in Ag@Sn to 0.05%, insufficient liquid phase during hot pressing resulted in 5-10 μm voids, resulting in a density of only 93.7%, and a simultaneous decline in conductivity and strength.

[0160] Example 8 uses low-cost electrolytic copper powder. Although the oxygen content is reduced from 1250 ppm to 18 ppm by 0.1% purifier + enhanced annealing, the residual impurities still cause lattice distortion, and the conductivity and strength are lower than those of Example 1.

[0161] 2. Determining factors of coating adhesion

[0162] Example Coating structure Bonding strength (MPa) Failure Mode 1 Nickel-phosphorus base layer + Ni-B 16.3 Substrate fracture (non-plating peeling) 3 Single-layer graphene coating 9.8 Interface delamination (missing transition layer) 5 Nickel-phosphorus base layer + Ni-B 15.5 <![CDATA[Hydrogen embrittlement microcracks (caused by high H2)]]>

[0163] The coating adhesion of Example 1 reaches 16.3 MPa, and the key lies in the multi-layer interface design: the 0.5μm nickel-phosphorus base layer forms an amorphous structure (P content 11%), which is chemically bonded to the copper substrate to reduce thermal stress; the functional layer is a Ni-B alloy with 7% boron, and nanocrystalline deposition is achieved through pulse electroplating. Boron solid solution strengthening brings the hardness to HV220.

[0164] Experiments show that the structure maintains interface integrity under a tensile force of 50N, and the failure mode is matrix fracture. In Example 3, the graphene coating is directly deposited after the nickel-phosphorus base layer is removed. Due to the missing transition layer, the interface thermal expansion coefficient mismatch occurs, and the bonding strength plummets to 9.8MPa. Microscopic observation shows that the coating peels off from the substrate over a large area. Although Example 5 retains the nickel-phosphorus base layer, 8% H2 annealing induces hydrogen embrittlement. Hydrogen atoms penetrate into the defects of the nickel-phosphorus layer to form H2 bubbles, which reduces the bonding strength to 15.5MPa, and microcracks propagate during fatigue testing.

[0165] This verifies the necessity of the nickel-phosphorus bottom layer for interface stability in claim 4 and the critical significance of the H2 concentration of 3-5% in claim 4.

[0166] 3. Key indicators of dynamic stability

[0167] Example Anti-slip texture Resistance fluctuation (1000 times) Texture damage rate 1 Complete texture ±1.2% 0% 2 No grain ±5.3% 100% 6 Complete texture ±1.3% 15%

[0168] The anti-slip pattern design of Example 1 reduces resistance fluctuation to only ±1.2% after 1,000 plug-in and pull-out cycles. The key lies in the geometric locking effect: the 70° radial grooves generate multi-directional friction resistance under vibration, with a tangential resistance coefficient of μ=0.38, while the grid pattern disperses 80% of the assembly stress through 0.3mm² raised units.

[0169] Comparative tests showed that the resistance fluctuation of Example 2, which lacks grooves, reached ±5.3% in the same plug-in test, due to the formation of oxidized debris on the contact surface due to micro-wear of the cable.

[0170] While Example 6 retains the texture, unidirectional forging results in anisotropy in the matrix, causing non-uniform stress in the textured area. 25% of the grooves exhibit microcracks in the coating, and resistance fluctuations increase to ±1.3%. This indicates that the texture structures of Claims 6-7 require synergy with the three-directional forging of Claim 1 to achieve optimal dynamic stability.

[0171] Example 9

[0172] Reference Figure 3-Figure 5 The present disclosure provides a rectangular terminal, which has a shell 10, a connecting head 30 arranged in the shell 10, and a conductive plate 20. The two ends of the conductive plate 20 have circular mounting holes and studs 201 arranged through the mounting holes. The connecting head 30 is sleeved on the studs 201; a cover is also rotatably provided on the shell 10, and the cover is a semi-enclosed structure for shielding and protecting the connecting head 30; a protrusion 401 is provided at one end of the cover, and grooves 101 that cooperate with the protrusion 401 are provided at both ends of the shell 10. The cover and the shell 10 are clamped together by the limiting cooperation of the protrusion 401 and the groove 101.

[0173] The cover refers to a protective structure that covers the outside of the connector 30 by rotating. Specifically, it can be implemented by injection-molded engineering plastics or metal sheet stampings. Its semi-enclosed shape can cover the top and both sides of the connector 30.

[0174] The limiting cooperation between the protrusion 401 and the groove 101 refers to the limiting fixation of the cover and the shell 10 through a mechanical structure, which can be specifically achieved by using the cooperation of a trapezoidal boss and a dovetail groove to ensure that the cover remains stable in the closed state.

[0175] The rotation setting means that the cover shell and the housing 10 are connected by a hinge or a rotating shaft, which can be specifically achieved by a combination structure of a micro bearing and a shaft pin, so that the cover shell can rotate around a fixed axis to open and close.

[0176] Specifically, after the conductive plate 20 and connector 30 are assembled, the cover rotates to cover the outer surface of the connector 30, forming a physical barrier. To inspect or adjust the connector 30 or perform wiring installation, the operator applies force to the edge of the cover, releasing the locking mechanism by means of the protrusion 401 and the groove 101, and then rotates the cover to open it.

[0177] When closing, rotate the cover counterclockwise so that the protrusion 401 is aligned with the groove 101 of the housing 10 and pushed in, automatically locking through the limit structure. This design not only prevents external foreign matter from invading the connection area, but also facilitates quick maintenance operations. In some specific embodiments, the rotation axis of the cover can be set in the middle of the side wall of the housing 10, so that the opening and closing angle of the cover reaches 90°; the protrusion 401 can be designed as an elastic snap-fit ​​structure, and the inner wall of the groove 101 is provided with a guide slope to reduce assembly resistance. In addition, a sealing strip can be added to the inner surface of the cover to further enhance the protection performance. Compared with the existing technology, traditional terminals usually adopt a fixed protective cover or a completely exposed connector 30 structure. The former requires the removal of screws to open, and the latter lacks effective protection. This solution significantly simplifies the operation steps while ensuring protection performance through the combination of rotating the cover and the limit clamping design, and no additional fasteners are required. The limit matching structure can maintain the relative position of the cover and the housing 10 when subjected to vibration or external force, preventing accidental opening.

[0178] Compared to existing technologies, traditional terminal covers often use threaded or plug-in designs, which can be cumbersome to operate or easily loosen. However, the use of a rotating design combined with a geometric stopper simplifies opening and closing while maintaining protective performance, and allows for tool-free assembly. The semi-enclosed structure provides sufficient protection while retaining the necessary operating space, balancing safety and convenience.

[0179] Through the above technical solution, the present application achieves convenient opening and closing and reliable locking of the connector 30, ensuring the safety of the electrical connection while improving operational and maintenance efficiency. The limited matching structure effectively prevents the cover from shifting in a vibrating environment, and the semi-enclosed design provides directional protection while minimizing space occupation, making it particularly suitable for dense installation scenarios with limited space.

[0180] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Any modifications and improvements made to the technical solution of the present invention by a person of ordinary skill in the art without departing from the design concept of the present invention shall fall within the scope of protection of the present invention. The technical content for which protection is sought in the present invention is fully set forth in the claims.

Claims

1. A method for manufacturing a conductive plate, characterized in that: The formula ratio of the conductive plate includes: Conductive matrix 98.9-99.6%, graphene nanosheets 0.3-0.8%, Ag@Sn core-shell particles 0.1-0.2%, grain boundary purification additives ≤0.05%, The preparation process of the conductive plate includes the following steps: S100, plasma ball milling oxygen-free copper powder, graphene nanosheets, and Ag@Sn core-shell particles under inert gas protection to obtain composite powder; S200, place the composite powder in a mold and press it in a stepwise manner at a pressure of 80-120 MPa: The first stage: 400±10℃ for 30min, The second stage: reduce the temperature to 250±10℃ at 10℃ / min and maintain the pressure for 1h; S300, perform three-way alternating forging on the hot pressed billet at room temperature, with a single deformation of 15-25%, a total deformation of ≥60%, and the forging direction extending horizontally to the left and right sides; S400, annealing at 300±10℃ for 1-2h in H2 / N2 mixture, where the volume proportion of H2 is 3-5%; S500, stamping into a conductive plate shape, processing mounting holes at both ends thereof, and finally preparing a composite conductive coating on the surface, the composite conductive coating comprising a tin matrix and a dispersed strengthening phase.

2. The method for manufacturing a conductive plate according to claim 1, wherein: The dispersed strengthening phase is selected from any one of the following: Boron element, present in the form of Ni-B alloy, with a boron content of 6-8wt%; Silver-tin alloy particles, Ag content 65-75wt%; Graphene nanosheets, lateral size ≤ 200 nm.

3. The method for manufacturing a conductive plate according to claim 2, wherein: When the strengthening phase is boron, a pulse electroplating process is used with pulse parameters: Ton=5-15ms, Toff=40-60ms, and peak current density of 6-10A / dm². When the strengthening phase is silver-tin alloy particles, the chemical plating process is adopted, the plating temperature is 70-80℃, and the pH value is 8.5-9.5; When the reinforcing phase is graphene nanosheets, ultrasonic assisted electroplating is used with an ultrasonic frequency of 35-45kHz and a power density of 250-350W / m³.

4. The method for manufacturing a conductive plate according to any one of claims 1 to 3, characterized in that: The composite conductive coating is a multi-layer structure, comprising: Bottom layer, pure tin or nickel-phosphorus alloy layer, thickness 0.3-1.0μm; The functional layer, the composite layer containing the dispersed reinforcement phase, has a thickness of 0.2-0.5 μm.

5. The method for manufacturing a conductive plate according to claim 4, wherein: The grain boundary purification additive is trimethyl borate or triethyl phosphate, the addition amount is 0.02-0.04%, and it is added simultaneously during plasma ball milling.

6. The method for manufacturing a conductive plate according to claim 1, wherein: Also includes: S600. A wiring window is punched in the middle of the conductive plate, and anti-slip grooves are processed on the contact surface. The anti-slip grooves have a groove depth of 20-50 μm and a groove pitch of 0.2-0.5 mm.

7. The method for manufacturing a conductive plate according to claim 6, wherein: The anti-slip pattern includes: Radial grooves are provided in the contact area of ​​the wire clamping frame, wherein the groove depth of the radial grooves is 30-50 μm and the extension angle is 60°-90°; The cross grid pattern is arranged near the through hole, the grid size of the cross grid pattern is 0.3×0.3 mm, and the protrusion height is 20-30 μm.

8. A rectangular terminal, characterized in that: A conductive plate having a housing, a connector disposed in the housing, and the conductive plate obtained by the method for manufacturing a conductive plate according to any one of claims 1 to 5, wherein the connectors are disposed at the left and right ends of the conductive plate, respectively, for connecting to an external circuit; Both ends of the conductive plate are provided with mounting holes and studs passing through the mounting holes, and the connecting head is sleeved on the studs.

9. The rectangular terminal according to claim 8, characterized in that: The housing is also rotatably provided with a cover, which is a semi-enclosed structure for shielding and protecting the connector; One end of the cover shell is provided with a protrusion, and both ends of the shell are provided with grooves that match the protrusion. The cover shell and the shell are clamped together through the limiting cooperation of the protrusion and the groove.

10. A rectangular terminal, characterized in that: A conductive plate having a housing, a connector disposed in the housing, and the conductive plate obtained by the method for manufacturing a conductive plate according to any one of claims 6 or 7, wherein the connectors are disposed at the left and right ends of the conductive plate, respectively, for connecting to an external circuit; Both ends of the conductive plate are provided with mounting holes and studs arranged through the mounting holes. The connecting head is sleeved on the studs. The conductive plate is provided with a wiring window and anti-slip patterns.

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