An electrical contact tube and a method of manufacturing the same

Abstract

The application provides an electric contact tube and a manufacturing method thereof, comprising the following steps: providing a core mold; sequentially performing a degreasing treatment, a polishing treatment and a zinc immersion treatment on the core mold to form a zinc film layer on the surface of the core mold, so as to obtain a zinc immersion core mold; electroplating an electric contact composite layer on the outer surface of the zinc film layer of the zinc immersion core mold to obtain an electroplating product; electrocasting a matrix layer on the outer surface of the electroplating product to obtain an electrocasting product; and removing the core mold and the zinc film layer of the electrocasting product by chemical corrosion to obtain a hollow electric contact tube. The process is simple and low in cost, and the electric contact tube has the advantages of high precision, high inner surface smoothness, good wear resistance of the contact surface, long plug-in life and good batch quality consistency.

Description

Technical Field

[0001] This application relates to the field of electroforming technology, specifically to an electrical contact tube and its manufacturing method. Background Technology

[0002] In recent years, with the development of science and technology, the manufacturing of tiny, precision parts has become increasingly important in the field of modern manufacturing technology. Industries such as aerospace, instrumentation, optical equipment, and micromechanics require certain tiny parts, some as small as a few micrometers, which presents significant challenges to their manufacturing.

[0003] From a manufacturing cost perspective, microtubes with apertures smaller than 0.25mm cannot be mass-produced like standard-sized sockets through machining, as the machining cost is too high. Instead, they are typically produced by drawing, cutting, and electroplating. However, drawn capillary tubes have a relatively large inner surface roughness. For example, a sleeve (detection probe tube) made from drawn phosphor bronze tubing, machined and electroplated, can be dissected and examined from its inner surface. Figure 4 It is evident that the inner surface is relatively rough, and the thickness of the gold and nickel plating layers on the inner surface is uneven, resulting in a significantly reduced probe lifespan compared to electroformed tubes (by orders of magnitude). Clearly, it is not the optimal choice for a high-reliability, long-life contact component.

[0004] In addition, existing microtube processing technologies also suffer from defects such as complex processes, difficult mold processing, irregular surface shape at the sizing zone, rough surface, and easy generation of drawing scratches; multiple drawing processes require vacuum annealing, have poor plasticity, are prone to eccentricity and wrinkles, require multiple drawing processes, and are prone to alloy strain corrosion and residual stress at the root of cracks; turning and drilling processes have low efficiency and high cost, and require high-speed lathes and special drill bits.

[0005] Therefore, there is a need to develop a new process for fabricating microtubes that is low-cost, has a high degree of inner surface smoothness, and high processing precision. Summary of the Invention

[0006] This application provides an electrical contact tube and its manufacturing method, which overcomes the defects of existing tube processing technology. The resulting product has a dimensional accuracy at the micron level and an inner surface finish of up to grade 11 (Rz<0.15).

[0007] Microtubes (microtubes refer to tubes with an inner diameter of less than 2 mm) are generally manufactured by turning. For the tube holes used in connectors and testing probes, these are capillary tubes with an inner diameter of approximately 0.15~0.45 mm. In terms of demand, capillary tubes for probes require a wider variety of specifications than those for twisted pin connectors. For example, there are products with the following specifications: Specification 1: outer diameter 0.19 mm, inner diameter 0.12 mm, and wall thickness 35 μm; Specification 2: outer diameter 0.18 mm, inner diameter 0.12 mm, and wall thickness 30 μm; Specification 3: outer diameter 0.14 mm, inner diameter 0.08 mm, and wall thickness 30 μm; Specification 4: outer diameter 0.08 mm, inner diameter 0.05 mm, and wall thickness 25 μm; Specification 5: outer diameter 0.34 mm, inner diameter 0.24 mm, and wall thickness 50 μm, etc.

[0008] From a manufacturing cost perspective, the manufacturing cost of electroforming microtubes can be significantly lower than that of turning and drilling. If 0.35mm is the cost balance line between the two processes, the cost difference between electroforming and turning / drilling is about double for every 0.05mm reduction in hole diameter. Moreover, 0.15mm is basically the limit for turning and drilling, while there is no essential difference in electroforming for different core diameters.

[0009] Electroforming is a process that uses electrochemical principles to deposit metal onto a mandrel, then separates the deposited metal layer from the mandrel to obtain metal parts that are difficult to form through machining. Electroformed parts can very accurately replicate the shape and microstructure of the cathode, offering advantages such as high dimensional accuracy, high surface finish, and good batch-to-batch quality consistency. Furthermore, the finished parts have high material purity, meeting certain special performance requirements. Therefore, electroforming technology can be used to manufacture precision, irregularly shaped, complex, and micro-sized metal parts.

[0010] This application provides a method for manufacturing an electrical contact tube, comprising: Provide core molds; The core mold is subjected to degreasing, polishing and zinc immersion treatment in sequence to form a zinc film layer on the surface of the core mold, thereby obtaining a zinc-immersed core mold; An electroplating composite layer is applied to the outer surface of the zinc film layer of the zinc-immersed core mold to obtain an electroplated product; Electroform the substrate layer on the outer surface of the electroplated product to obtain the electroformed product; The core mold and zinc film layer of the electroformed product are dissolved by chemical etching to obtain the hollow electrical contact tube.

[0011] Optionally, in some embodiments of this application, the electroplated electrical contact composite layer includes: sequentially electroplating a lubricating electrical contact layer, a wear-resistant electrical contact layer, and a wear-resistant and corrosion-resistant support layer.

[0012] Optionally, in some embodiments of this application, the electroformed product is further subjected to cutting before the chemical etching and to nozzle shaping after the chemical etching.

[0013] Optionally, in some embodiments of this application, the core mold is a cylindrical aluminum core mold with an outer diameter of 0.05mm to 0.45mm.

[0014] Optionally, in some embodiments of this application, the degreasing process includes: placing the core mold as the cathode and the graphite plate as the anode in a first electrolyte for electrolytic reaction, wherein the first electrolyte includes: sodium carbonate 5 g / l ~ 10 g / l, sodium phosphate 10 g / l ~ 20 g / l and sodium silicate 5 g / l ~ 10 g / l; The polishing process includes: placing the degreased core mold as the cathode and a graphite plate as the anode in a second electrolyte for electrolytic reaction, thereby reducing the surface roughness of the core mold to Rz. 0.15, the second electrolyte is dilute nitric acid containing a nonionic surfactant.

[0015] Optionally, in some embodiments of this application, the process parameters for the zinc immersion treatment are a temperature of 20°C to 24°C and a time of 25s to 40s; and / or, the zinc immersion solution used in the zinc immersion treatment includes: sodium hydroxide 120g / l to 140g / l, zinc oxide 20g / l to 22g / l, crystalline ferric chloride 1.5g / l to 2.0g / l, potassium sodium tartrate 45g / l to 55g / l and sodium nitrate 0.8g / l to 1.2g / l.

[0016] Optionally, in some embodiments of this application, the lubricating electrical contact layer is a pure gold layer, and the method for preparing the pure gold layer includes: depositing pure gold on the surface of the zinc film layer by means of an electrolytic reaction to form a pure gold layer.

[0017] Optionally, in some embodiments of this application, the electroplating solution for the pure gold layer includes: potassium gold cyanide 1.2 g / l to 3.0 g / l, potassium citrate 40 g / l to 80 g / l; and / or, the electroplating process parameters are: pH value 5.2 to 5.6, temperature 53℃ to 57℃, voltage 2.5 V to 3.5 V; and / or, the anode is a platinum titanium mesh.

[0018] Optionally, in some embodiments of this application, the wear-resistant electrical contact layer is a hard gold layer, and the preparation method of the hard gold layer includes: depositing a gold-nickel alloy or a gold-cobalt alloy on the surface of the lubricating electrical contact layer by means of an electrolytic reaction to obtain a gold-nickel alloy layer or a gold-cobalt alloy layer, which is the hard gold layer.

[0019] Optionally, in some embodiments of this application, the electroplating solution for the gold-cobalt alloy layer comprises: potassium gold cyanide 4.0 g / L ~ 12 g / L, cobalt sulfate 1.2 g / L - 1.8 g / L, potassium citrate 50 g / L ~ 70 g / L, potassium dihydrogen phosphate 50 g / L ~ 70 g / L, and a brightener; and / or, the electroplating process parameters are: pH value 4.0 ~ 4.5, temperature 40℃ ~ 60℃, and current density 0.5 A / dm³. 2 ~15 A / dm 2 ; and / or, the anode is a platinum titanium mesh.

[0020] Optionally, in some embodiments of this application, the wear-resistant and corrosion-resistant support layer is a nickel-tungsten alloy layer or a nickel-phosphorus alloy layer, and the preparation method of the nickel-tungsten alloy layer or the nickel-phosphorus alloy layer includes: depositing the nickel-tungsten alloy or the nickel-phosphorus alloy onto the surface of the wear-resistant electrical contact layer by means of an electrolytic reaction to obtain the nickel-tungsten alloy layer or the nickel-phosphorus alloy layer.

[0021] Optionally, in some embodiments of this application, the electroplating solution for the nickel-tungsten alloy layer comprises: sodium tungstate 80 g / L ~ 150 g / L, nickel aminosulfonate 50 g / L ~ 125 g / L, and citric acid 100 g / L ~ 150 g / L; and / or, the electroplating process parameters are: pH value 7.0 ~ 8.5, temperature 65℃ ~ 70℃, and current density 10 A / dm³. 2 ~20A / dm 2 ; and / or, the anode is made of 316L stainless steel.

[0022] Optionally, in some embodiments of this application, the substrate layer is a nickel layer or a copper layer, and the preparation method of the nickel layer or copper layer includes: depositing nickel or copper on the surface of the electroplated electrical contact composite layer by means of an electrolytic reaction to form a nickel layer or copper layer.

[0023] Optionally, in some embodiments of this application, the electroforming solution for the nickel layer comprises: 140 g / L to 150 g / L nickel ions and 30 g / L to 40 g / L boric acid; and / or, the electroforming process parameters are: pH value of 3.8 to 4.2, temperature of 60°C to 65°C, and current density of 25 A / dm³. 2 ~35 A / dm 2 .

[0024] Optionally, in some embodiments of this application, the chemical etching includes: removing the core mold with an ultrasonic-assisted alkaline solution; and removing the zinc film layer with an ultrasonic-assisted chromic acid solution.

[0025] Accordingly, this application also provides an electrical contact tube, which is prepared by the above method. Its structure includes, from the inner layer to the outer layer, an electrical contact composite layer and a substrate layer, wherein the substrate layer covers the surface of the electroplated electrical contact composite layer.

[0026] Optionally, in some embodiments of this application, the electrical contact composite layer includes a lubricating electrical contact layer, a wear-resistant electrical contact layer, and a wear-resistant and corrosion-resistant support layer stacked sequentially from the inner layer to the outer layer, wherein the wear-resistant electrical contact layer covers the surface of the lubricating electrical contact layer, and the wear-resistant and corrosion-resistant support layer covers the surface of the wear-resistant electrical contact layer.

[0027] Optionally, in some embodiments of this application, the thickness of the lubricating electrical contact layer is 0.025 μm to 0.15 μm; and / or, the thickness of the wear-resistant electrical contact layer is 0.5 μm to 1.5 μm; and / or, the thickness of the wear-resistant and corrosion-resistant support layer is 0.8 μm to 1.5 μm; and / or, the thickness of the substrate layer is greater than 25 μm.

[0028] Optionally, in some embodiments of this application, the hardness of the wear-resistant electrical contact layer is 130 HV to 210 HV; and / or, the hardness of the wear-resistant and corrosion-resistant support layer is 450 HV to 500 HV; and / or, the hardness of the substrate layer is 180 HV to 250 HV.

[0029] This application has at least one or more of the following beneficial effects: In this application, a core mold with controllable dimensions and easy removal is provided based on an electroforming method. The core mold undergoes pretreatment such as electrochemical degreasing, polishing, and zinc immersion. Electroplating and electroforming can then be performed directly on the core mold. After electroforming, the core mold is removed without damaging the electroformed layer, thereby producing an electrical contact tube with an inner surface coating finish of up to grade 11 (Rz<0.15). The electrical contact tube also has advantages such as high precision, good wear resistance of the contact surface, long insertion and extraction life, and good batch-to-batch quality consistency. It can be used as a micro-contact socket or probe sleeve.

[0030] In this application, the inner diameter of the electrical contact tube depends on the size of the controllable mandrel, and its wall thickness can be controlled from several hundred micrometers to several micrometers, thus providing a micro-tube processing method with adjustable diameter and controllable wall thickness. Compared with existing micro-tube processing technology and turning and drilling technology, the micro-electrical contact tube processed by this application is smaller in size, especially suitable for processing capillary electrical contact tubes with an inner diameter of about 0.15~0.45mm. At the same time, it also reduces the processing cost and solves the problems of low efficiency and high cost, as well as the need for high-speed lathes and special drills in existing turning and drilling processes. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a flowchart of the manufacturing method of the electrical contact tube provided in this application; Figure 2 This is a schematic cross-sectional view of the electrical contact tube provided in this application; Figure 3 This is a physical schematic diagram of the electrical contact tube provided in this application; Figure 4 This is a cross-sectional view of an existing related sleeve made and electroplated from drawn phosphor bronze tubing, as provided in this application; The diagram shows: 1. Core mold, 2. Zinc film layer, 3. Electrical contact composite layer, 4. Substrate layer, and 5. Electrical contact tube. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to up, down, left, and right in the actual use or working state of the device, specifically the drawing directions in the accompanying drawings.

[0034] This application provides an electrical contact tube and a method for manufacturing the same, which will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0035] Please see Figure 1 , Figure 1 This is a flowchart of a method for manufacturing an electrical contact tube provided in this application, which includes the following steps: S1 provides core mold 1.

[0036] S2, the mandrel undergoes degreasing, polishing, and zinc immersion treatment sequentially to form a zinc film layer 2 on the mandrel surface, resulting in a zinc-immersed mandrel. Degreasing removes the oxide film from the mandrel surface, improving surface cleanliness. Polishing enhances surface gloss. Zinc immersion increases the hydrogen evolution overpotential and strengthens the adhesion of the electrical contact composite layer.

[0037] S3, electroplating the outer surface of the zinc film layer 2 of the zinc-immersed core mold with an electrical contact composite layer 3 in sequence to obtain the electroplated product.

[0038] S4, electroform the substrate layer 4 onto the outer surface of the electroplated product to obtain the electroformed product. It should be noted that the outer diameter of the substrate layer 4 formed by electroforming can be easily controlled within 5 micrometers. Generally, the intermediate value of the final required size is added by 5 micrometers.

[0039] S5, using chemical etching to dissolve the core mold 1 and zinc film layer 2 of the electroforming product, a hollow electrical contact tube 5 is obtained.

[0040] Reference Figure 2 and Figure 3 The figure shows a physical image of an electrical contact tube obtained by the above manufacturing method. The figure shows that an ultra-smooth and uniformly thick electrical contact composite layer is formed on the inner surface of the electrical contact tube.

[0041] It should be noted that the electroplating described above can be performed using conventional methods such as rack plating, barrel plating, continuous plating, and brush plating. In some preferred embodiments, a continuous linear electroplating method is used, or a rack plating method can be used where the mandrel to be plated is stretched straight on a rack. The electroforming described above can be performed using conventional methods such as rack casting, barrel casting, continuous casting, and brush casting.

[0042] In the above method, the core mold is sequentially degreased and polished, resulting in a surface free of oil and with low roughness and a bright mirror finish. The core mold is then immersed in zinc, ensuring that the hydrogen evolution overpotential of the core mold surface in the plating solution is higher than the electrodeposition electrode potential of the plating metal. Simultaneously, the zinc immersion treatment ensures that the bonding strength between the metal plating on the inner surface of the electrical contact tube and the core mold reaches a level of over 5 MPa, guaranteeing that even when the metal plating on the inner surface of the product is thickened to over 2 micrometers, the bonding strength can resist the tensile stress of the metal plating, preventing cracking during the electroforming process. In some embodiments, the electroplated electrical contact composite layer includes: sequentially electroplating a lubricating electrical contact layer, a wear-resistant electrical contact layer, and a wear-resistant and corrosion-resistant support layer. For example, when the wear-resistant electrical contact layer is a hard gold layer, direct and short-term anodizing on the core mold followed by gold plating in a citric acid system cannot deposit gold, but gold can be deposited on the pre-zinc-immersed surface. This demonstrates that the pretreatment of the core mold enables electroforming to achieve the conditions for depositing a plating layer on the surface of industrial pure aluminum wire.

[0043] It should be noted that the pretreatment of the mandrel, including degreasing, polishing, and zinc immersion, is a crucial factor affecting the bonding strength in the early stages of electroforming. If these pretreatments are not performed properly, peeling, mottling, and other defects are very likely to occur during the subsequent electroforming process.

[0044] The manufacturing method provided in this embodiment can directly electroform electrical contact tubes onto pure aluminum wire. The inner diameter of the prepared electrical contact tube depends on the size of the controllable mandrel, and the wall thickness of the electrical contact tube can be controlled from several hundred micrometers to several micrometers. Compared with existing microtube processing technology and turning and drilling technology, the electrical contact tubes prepared in this embodiment are much smaller in size. In some embodiments, the mandrel is a cylindrical aluminum mandrel with an outer diameter of 0.05mm to 0.45mm. Aluminum mandrels are easier to remove by corrosion after electroforming without damaging the electroformed layer; therefore, aluminum and its alloys can be selected as mandrels. A cylindrical aluminum mandrel with an outer diameter of 0.05mm to 0.45mm is selected. Pure aluminum wire can be used for this specification of aluminum mandrel. Pure aluminum wire can achieve extremely high dimensional accuracy and surface finish. However, aluminum is an amphoteric metal with relatively active chemical properties, is easily oxidized in air, and is easily corroded in acidic or alkaline electrolytes. Therefore, directly plating gold onto pure aluminum wire presents the following problems: First, poor adhesion leads to discontinuous and uneven plating layers. Second, the hydrogen evolution overpotential on the aluminum surface is low in conventional gold plating solutions, making gold deposition difficult. For example, the hydrogen potential in a solution with a pH of 4 is -0.25V, while in acidic solutions, the hydrogen evolution overpotential on the aluminum surface is approximately -0.5~-0.6V, lower than the equilibrium potential of hydrogen. The hydrogen evolution potential is the hydrogen evolution overpotential on the aluminum surface. Assuming the free potassium cyanide in the plating solution is 5 g / L, the standard potential for gold deposition from potassium gold cyanide is approximately 1.692-0.0592. (2+38) = -0.68V. The cathodic hydrogen evolution potential of aluminum is higher than that of gold, so a gold layer cannot be deposited on the aluminum surface in an acidic micro-cyanide gold plating solution. Other electroplating processes on aluminum alloys cannot be directly applied. For example, it is usually feasible to deposit copper and nickel on a porous oxide film formed by anodic electrolysis, but gold cannot be plated in the commonly used citric acid micro-cyanide system. Conventional alkaline etching zinc immersion for gold plating reduces the surface smoothness of the aluminum wire. Existing aluminum chemical polishing and electrolytic polishing processes are difficult to control dimensions and inevitably produce over-corrosion, resulting in the inner surface precision and smoothness of the electroformed hole not meeting the requirements. III. Difficulty in pre-treatment of aluminum core molds. Gold plating aluminum alloys is far more difficult than gold plating copper or steel parts, and the process is more complex. This is mainly because aluminum and aluminum alloys have different properties than other metals. Aluminum is an amphoteric metal, reacting with both acids and alkalis. Even slight improper pretreatment can cause excessive surface corrosion. Furthermore, aluminum and aluminum alloys readily form oxide films in both air and solutions. If these oxide films are not thoroughly removed, they will affect the adhesion of the plating layer. Subsequent thickening of the hard gold plating layer will result in peeling, and the inner surface of the electroformed tube will become rough or even uneven. Fourth, the rapid diffusion of the replacement zinc layer and gold plating layer leads to a dull surface after zinc removal. Fifth, the low current density in electroforming nickel results in low production efficiency, while excessively high current density causes hydrogen generated in the aqueous solution to adsorb onto the cathode surface, hindering electrodeposition and forming pinholes. Impurities entering the plating solution cause an uneven surface, and this unevenness becomes more pronounced with increasing electroformed layer thickness. These problems make electroforming difficult, and selecting a suitable electroforming process is essential for success. The manufacturing method provided in this application solves the aforementioned difficulties in electroplating and electroforming on aluminum core molds, as detailed in the following embodiments.

[0045] In other embodiments of this application, the electroformed product undergoes a cutting process before chemical etching. This cutting can be performed by machining into small segments of the required size or by wire EDM cutting. The wire EDM process uses a medium-speed wire cutter to bundle the segments, which improves cutting efficiency. Specifically, cutting the electroformed wire into segments at the receiving end avoids bending, and then bundling the electroformed wire segments into bundles for wire EDM cutting into small segments of the required length.

[0046] After being cut into small segments, the core mold and zinc coating are removed segmentally using chemical etching. In some embodiments, the core mold is an aluminum core mold, and the removal of the aluminum core mold by chemical etching includes: removing the aluminum core mold using an ultrasonic-assisted alkaline solution at a temperature of 60°C to 70°C; the alkaline solution includes NaOH 50 g / L to 100 g / L and sodium gluconate 15 g / L to 30 g / L. The process parameters for chemical etching to remove the aluminum core mold are: ultrasonic frequency of 28 kHz to 40 kHz, ultrasonic power of 100 W per liter, and processing time until the aluminum core is completely dissolved. The zinc coating layer is then removed at room temperature using an ultrasonic-assisted 100 g / L to 150 g / L chromic acid solution for 1 to 3 minutes, with an ultrasonic frequency of 28 kHz to 40 kHz.

[0047] In another embodiment, after chemical etching, a pipe end shaping process is performed. Specifically, the pipe end is rounded. In practice, mechanical processing is used to clean the inner corner of the orifice to meet usage requirements. After the inner side of the pipe end is processed, the short pipe is placed in a micro-vibratory grinding machine, where vibratory grinding polishes the outer edge of the opening, reducing the outer diameter by 3 to 5 micrometers.

[0048] In other embodiments of this application, the degreasing process includes: placing a core mold serving as the cathode and a graphite plate serving as the anode in a first electrolyte for an electrolytic reaction. The first electrolyte comprises: 5 g / L to 10 g / L sodium carbonate, 10 g / L to 20 g / L sodium phosphate, and 5 g / L to 10 g / L sodium silicate. The process parameters for the degreasing process are: a temperature of 50°C to 60°C and a current density of 2 A / dm³. 2 ~5A / dm 2 .

[0049] The polishing process includes: placing the degreased mandrel as the cathode and a graphite plate as the anode in a second electrolyte for electrolytic reaction, thereby reducing the surface roughness of the mandrel to Rz. The second electrolyte is 15% dilute nitric acid containing 2 g / L to 5 g / L of low-foaming nonionic surfactant. The polishing process parameters are a current density of 3 A / dm³. 2 ~7A / dm 2 The processing time is approximately 1 minute. In some embodiments, cathodic electrolysis with dilute nitric acid containing a low-foaming nonionic surfactant is used to prevent corrosion of the aluminum core mold, thereby achieving a high degree of cleanliness on the surface of the aluminum core mold and further improving its gloss.

[0050] In other embodiments of this application, the mandrel is immersed in a zinc immersion solution at a temperature of 20°C to 24°C for 25 to 40 seconds. The zinc immersion solution comprises: sodium hydroxide 120 g / L to 140 g / L, zinc oxide 20 g / L to 22 g / L, crystalline ferric chloride 1.5 g / L to 2.0 g / L, potassium sodium tartrate 45 g / L to 55 g / L, and sodium nitrate 0.8 g / L to 1.2 g / L. The zinc immersion treatment facilitates the electroplating of a lubricating electrical contact layer on the surface of the mandrel, while increasing the adhesion between the lubricating electrical contact layer and the mandrel. This improves the continuity of the lubricating electrical contact layer, ensuring the continuity and adhesion of the subsequent wear-resistant electrical contact layer, wear-resistant and corrosion-resistant support layer, and substrate layer. In some embodiments, because zinc exists as a complex ion in strongly alkaline solutions, its potential is more negative than that of iron and nickel in general solutions. Therefore, the potential difference between zinc and aluminum in a strongly alkaline medium is lower than that between iron or nickel and aluminum in a single salt solution. When the aluminum core mold is immersed in a zincate solution, a thin and uniform zinc layer can be obtained, thereby ensuring good adhesion of the plating. Zinc immersion treatment increases the adhesion of the gold plating layer. In a specific example, the core mold is an aluminum core mold, and the lubricating electrical contact layer is a soft gold layer. After zinc immersion treatment, a gold layer can be deposited on the surface of the aluminum core mold in a weakly acidic citric acid microcyanide plating solution; otherwise, the low overpotential due to hydrogen evolution on the surface of the aluminum core mold is unfavorable for gold deposition.

[0051] In other embodiments of this application, the lubricating electrical contact layer is a pure gold layer. The method for preparing the pure gold layer includes: depositing pure gold onto the surface of a zinc film layer using an electrolytic reaction to form a pure gold layer. In terms of process, the pure gold layer serves as a transition layer for the subsequent wear-resistant electrical contact layer, matching the material of the hard gold layer; simultaneously, it provides lubrication for the final wear-resistant hard gold layer used for electrical contact.

[0052] In some embodiments, the electroplating solution for preparing the pure gold layer is a weakly acidic citrate-cyanide system. In other embodiments, the electroplating solution for the pure gold layer includes: potassium gold cyanide 1.2 g / L ~ 3.0 g / L, potassium citrate 40 g / L ~ 80 g / L; and / or, the electroplating process parameters are: pH value 5.2 ~ 5.6, temperature 53℃ ~ 57℃, and control voltage 2.5 V ~ 3.5 V; and / or, the anode is a platinum-titanium mesh.

[0053] In other embodiments of this application, the wear-resistant electrical contact layer is a hard gold layer, which is made of a gold-nickel alloy and a gold-cobalt alloy with a certain hardness, which is beneficial to improving the wear resistance of the electrical contact.

[0054] The preparation method of hard gold layer includes: depositing gold-nickel alloy or gold-cobalt alloy on the surface of lubricating electrical contact layer by electrolysis to obtain gold-nickel alloy layer or gold-cobalt alloy layer, which is hard gold layer.

[0055] In other embodiments of this application, the electroplating solution for the hard gold layer is a plating solution containing a gold-nickel alloy or a gold-cobalt alloy. In some embodiments, the electroplating solution formulation for the gold-nickel alloy layer includes: potassium gold cyanide 4.0 g / L ~ 12 g / L, N,N-ethylenediaminediacetic acid nickel 2.8 g / L ~ 3.5 g / L, potassium citrate 50 g / L ~ 70 g / L, potassium dihydrogen phosphate 30 g / L ~ 40 g / L, and citric acid to adjust the pH of the electroplating solution system to 4.0 ~ 4.5. The process parameters for electroplating the gold-nickel alloy layer are: temperature 40℃ ~ 60℃, current density 0.5 A / dm³. 2 ~15 A / dm 2 The specific value is related to the gold ion concentration, solution temperature, and stirring speed; the anode is a platinum titanium mesh.

[0056] In some embodiments, the electroplating solution formulation for the gold-cobalt alloy layer includes: potassium gold cyanide 4.0 g / L ~ 12 g / L, cobalt sulfate 1.5 g / L (divalent cobalt content 0.35 g / L ~ 0.50 g / L, 1:1 EDTA complex), potassium citrate 50 g / L ~ 70 g / L, potassium dihydrogen phosphate 50 g / L ~ 70 g / L, and a brightener 0.5 g / L ~ 3 g / L. The brightener can be pyridine sulfonic acid and polyethyleneimine. The pH value of the electroplating solution formulation system is 4.0 ~ 4.5. The process parameters for electroplating the gold-cobalt alloy layer are: temperature 40℃ ~ 60℃, current density 0.5 A / dm³. 2 ~15 A / dm 2 The specific value is related to the gold ion concentration, solution temperature, and stirring speed; the anode is a platinum titanium mesh.

[0057] It should be noted that the electroplating time for the hard gold layer is t (minutes) = kδ / D k k = 2.0~6.0 is related to gold concentration, solution temperature, and pH; δ is the gold thickness (micrometers); D k It is the cathode current density (taken as 1 A / dm for rack plating). 2 ~3 A / dm 2 High-speed plating of wire yields a value of 5 A / dm. 2 ~15 A / dm 2 The actual hard gold plating thickness is 1 micrometer, and the current density is 5 A / dm. 2 Therefore, the electroplating time is approximately 1.5 minutes (equivalent to 90 seconds).

[0058] In other embodiments of this application, the wear-resistant and corrosion-resistant support layer is a nickel-tungsten alloy layer or a nickel-phosphorus alloy layer. The preparation method of the nickel-tungsten alloy layer or nickel-phosphorus alloy layer includes: depositing the nickel-tungsten alloy or nickel-phosphorus alloy onto the surface of the wear-resistant electrical contact layer using an electrolytic reaction to obtain the nickel-tungsten alloy layer or nickel-phosphorus alloy layer. The nickel-tungsten alloy layer or nickel-phosphorus alloy layer has a certain degree of hardness to improve the wear resistance of the coating. The wear-resistant electrical contact layer, supported by an ultra-hard nickel-tungsten alloy layer or nickel-phosphorus alloy layer, provides good wear resistance, good insertion and extraction life, and good batch quality consistency for electrical contact surfaces. In other embodiments, the nickel-tungsten alloy layer or nickel-phosphorus alloy layer also exhibits strong resistance to galvanic corrosion of the gold layer, and the nickel base layer has strong corrosion resistance, allowing it to be reliably used as an electrical contact component in harsh environments for extended periods.

[0059] In other embodiments of this application, the nickel-tungsten alloy layer prepared by electroplating is a nanocrystalline nickel-tungsten alloy electrodeposition layer; the nickel-phosphorus alloy layer prepared by electroplating is an amorphous nickel-phosphorus alloy electrodeposition layer. In some embodiments, the electroplating solution for the nickel-tungsten alloy layer includes: sodium tungstate (Na2WO4•2H2O) 80 g / l ~ 150 g / l, nickel aminosulfonate [Ni(NH2SO3)2•4H2O)] 50 g / l ~ 125 g / l, citric acid (C6H8O7•H2O) 100 g / l ~ 150 g / l, with ammonia added to adjust the pH value to 7.0~8.5; the process parameters for electroplating the nickel-tungsten alloy layer or the nickel-phosphorus alloy layer are: temperature 65℃~70℃, current density 10 A / dm³. 2 ~20A / dm 2 The anode is a combination of a nickel plate and a 316L stainless steel plate. The nickel and tungsten components in the plating solution are supplemented with nickel citrate and ammonium tungstate to avoid the accumulation of salts in the plating solution.

[0060] It should be noted that the molar ratio of metal content in the electroplating solution is [W] / ([W]+[Ni]) ≥ 75%, resulting in a bright silvery-white nickel-tungsten alloy layer with a tungsten content ≥ 45%. Anode: 316L stainless steel plate; Time: t (minutes) 10δ / D K Actual current density 20A / dm 2 The time was 45 seconds, and the thickness of the nickel-tungsten alloy plating layer was 1.4 micrometers.

[0061] In some embodiments, the electroplating solution for the amorphous nickel-phosphorus alloy layer comprises: nickel aminosulfonate [Ni(NH2SO3)2•4H2O)] 310 g / L ~ 390 g / L, boric acid 30 ~ 40 g / L, phosphorous acid 60 g / L ~ 100 g / L, and sodium hydroxide to adjust the pH to 1.8 ~ 2.5; the temperature is 52℃ ~ 55℃, and the cathode current density is 10 A / dm³. 2 ~20A / dm 2 The anode is a nickel plate.

[0062] In other embodiments of this application, the substrate layer is a nickel layer or a copper layer, and the method for preparing the nickel layer or copper layer includes: depositing nickel or copper onto the surface of the wear-resistant and corrosion-resistant support layer using an electrolytic reaction to form a nickel layer or copper layer. In some embodiments, nickel is electroformed in a nickel sulfamate solution or copper is electroformed in an acidic copper plating solution.

[0063] In other embodiments of this application, the electroforming solution used for the nickel layer is a high-speed electroplating solution containing low-stress nickel sulfamate with a nickel ion concentration maintained at 110 g / L to 130 g / L. In some embodiments, the electroforming solution for the nickel layer includes: 140 g / L to 150 g / L nickel ions, 30 g / L to 40 g / L boric acid, and a saccharin-based softener; the pH value of the electroforming solution system is 3.8 to 4.2. The process parameters for the electroforming nickel layer are: temperature 60°C to 65°C, and cathode current density 25 A / dm³. 2 ~35A / dm 2 It should be noted that the electroforming time t (minutes) for the nickel layer is 5.1δ / D. K D K Select 20~45ASD; for example, if the actual current density is 25A / dm². 2 The process took 10 minutes, and the nickel layer was approximately 50 micrometers thick.

[0064] In other embodiments, the electroformed copper layer uses a high-speed electrolyte containing acidic copper ions. The copper electroforming solution comprises: copper sulfate 200 g / L ~ 240 g / L, sulfuric acid 40 g / L ~ 60 g / L, chloride ions 50 ~ 80 mg / L, polyethylene glycol (relative molecular weight 4000 ~ 6000) 0.05 g / L ~ 0.1 g / L, sodium polydithiopropane sulfonate 0.01 g / L ~ 0.02 g / L, 2-imidazolidinethione 0.0002 g / L ~ 0.0007 g / L, 2-mercaptobenzoimidazole 0.0003 g / L ~ 0.0010 g / L, a temperature of 15°C ~ 40°C, and a cathode current density of 1.5 A / dm³. 2 ~ 20A / dm 2 Anode current density 0.5 A / dm 2 ~ 3.0A / dm 2 .

[0065] It should be noted that electroplated nickel layers suffer from excessive internal stress, which can lead to cracking and blistering, ultimately affecting the product's performance and yield. In the electroplating process, the main factors influencing the performance of electroplated nickel include internal stress, mechanical properties, and grain size and arrangement in the microstructure. The parameters affecting the overall performance of the electroplated nickel layer primarily include cathode current density, temperature, and solution pH. Therefore, these parameters must be strictly controlled during electroplating. The recommended process parameters for electroplated nickel layers are: pH 3.8–4.2, temperature 60–65℃, and cathode current density 25 A / dm³. 2 ~35A / dm 2 This helps to avoid excessive internal stress in the nickel layer.

[0066] In other embodiments of this application, the method for manufacturing the electrical contact tube includes the following steps: Lay out the aluminum core mold (adjust the resistance to create a straightening effect) or stretch it taut on the glued stainless steel hanger.

[0067] The aluminum core mold is subjected to cathodic electrolytic degreasing for 0.5 to 1 minute, followed by two water spray washes.

[0068] After the first-stage electrolytic degreasing treatment, a second-stage cathodic electrolytic degreasing and electropolishing treatment is performed, which takes about 1 minute. After being rinsed with water, a zinc immersion treatment is performed for 0.5 minutes.

[0069] After zinc immersion treatment, the product is washed with water and then with pure water, followed by electroplating of a pure gold layer for 15-30 seconds, an electroplating of a gold-cobalt alloy layer for 120 seconds (Max 1.5 micrometers), and an electroplating of a nickel-phosphorus alloy layer for 120 seconds (Max 1.5 micrometers).

[0070] After the nickel-phosphorus alloy layer is electroplated, the nickel layer is electroformed for 10 minutes (Max 30 microns). After electroforming, the material is cleaned and dried in sequence. The material is continuously plated and cut into 50 cm lengths for collection. It is then cut into small segments of usable length and ultrasonically etched into the aluminum core mold. The residual zinc on the gold layer surface is removed with chromic acid. After recycling, the material is washed with water, hot pure water, and dried in sequence to obtain the electrical contact tube.

[0071] The manufacturing method described above can produce slender holes with diameters of 0.15 mm or less, even 0.05 mm, and can be applied to the manufacture of contact holes for twisted pin contacts and snap button contacts with extreme dimensions. In some applications, after electroforming, the electroformed wire with an outer diameter of 0.15 mm and an inner diameter of 0.11 mm can be cut into longer segments, bundled together, and cut using fast wire EDM and repeated. Finally, slow wire EDM is used to cut off the excess dimensions at both ends while trimming the end faces, etching to remove the aluminum core film, and then dry ice shot blasting to remove edge burrs. This can be used as a low-cost manufacturing method for sleeves for snap button contact modules.

[0072] Accordingly, embodiments of this application also provide an electrical contact tube, which is prepared using the method described in the above embodiments. It comprises, from the inner layer to the outer layer, an electrical contact composite layer and a substrate layer, with the substrate layer covering the surface of the electroplated electrical contact composite layer. In some embodiments, the electrical contact composite layer comprises, from the inner layer to the outer layer, a lubricating electrical contact layer, a wear-resistant electrical contact layer, and a wear-resistant and corrosion-resistant support layer, stacked sequentially. The wear-resistant electrical contact layer covers the surface of the lubricating electrical contact layer, and the wear-resistant and corrosion-resistant support layer covers the surface of the wear-resistant electrical contact layer. In other embodiments, the outer diameter of the electrical contact tube is 0.08 mm - 0.35 mm, the inner diameter is 0.05 mm - 0.45 mm, and the wall thickness is 25 μm - 50 μm.

[0073] In other embodiments of this application, the lubricating electrical contact layer of the electrical contact tube is a pure gold layer, the wear-resistant electrical contact layer is a hard gold layer, the wear-resistant and corrosion-resistant support layer is a nickel-tungsten alloy layer or a nickel-phosphorus alloy layer, and the base layer is a nickel layer or a copper layer. The electrical contact tube has good comprehensive mechanical properties, with the main nickel tube having a hardness of 180 HV ~ 250 HV, good ductility, and high mechanical strength, which can meet the deformation requirements for wire crimping.

[0074] In other embodiments of this application, the thickness of the lubricating electrical contact layer is 0.025 μm to 0.15 μm; and / or, the thickness of the wear-resistant electrical contact layer is 0.5 μm to 1.5 μm; and / or, the thickness of the wear-resistant and corrosion-resistant support layer is 0.8 μm to 1.5 μm; and / or, the thickness of the substrate layer is greater than 25 μm. In specific implementations, the thickness of the substrate layer can be determined according to the mechanical strength requirements. The lubricating electrical contact layer is a pure gold layer, and the material of the pure gold layer is pure gold. The wear-resistant electrical contact layer is a hard gold layer, and the material of the hard gold layer is a gold-nickel alloy or a gold-cobalt alloy. The wear-resistant and corrosion-resistant support layer is a nickel-tungsten alloy layer or a nickel-phosphorus alloy layer. The substrate layer is a nickel layer or a copper layer.

[0075] It should be noted that when considering the transmission performance of high-frequency (millimeter wave) and high-speed signals, using a copper layer or increasing the thickness of the nickel-tungsten alloy layer or nickel-phosphorus alloy layer to about 2 micrometers (even if the gold layer wears down, it will exceed the skin depth of high-frequency signals) can completely eliminate any concerns about magnetic permeability.

[0076] In other embodiments of this application, the hardness of the wear-resistant electrical contact layer is 130 HV to 210 HV; and / or, the hardness of the wear-resistant and corrosion-resistant support layer is 450 HV to 500 HV, which is beneficial to improving the mechanical insertion and extraction life of the product, more than 5 times that of conventional nickel substrates. And / or, the hardness of the substrate layer is 180 HV to 250 HV.

[0077] In other embodiments of this application, the provided electrical contact tube retains the pure gold and hard gold layers, uses a nickel-tungsten alloy as a wear-resistant and corrosion-resistant support layer, and a copper layer as a substrate layer. This structure can completely eliminate the influence of the magnetic permeability of ordinary nickel layers on the transmission of high-frequency and high-speed signals. For example, the skin depth of a 1GHz signal in the pure gold and hard gold layers is 2.38μm, exceeding the thickness range of approximately 1μm for typical gold plating. The skin depth of a 1GHz signal in the nickel-tungsten alloy layer is approximately 1.2μm. Therefore, using a 1.5μm nickel-tungsten layer plus a 1μm gold layer on the inner surface as a high-frequency and high-speed signal transmission plating layer can ensure signal integrity.

[0078] To enable those skilled in the art to clearly understand the above-described implementation details and operations of the present invention, and to demonstrate the significant advancements in the performance of the miniature electrical contact tube and its electroforming preparation method according to the embodiments of the present invention, the above technical solutions are illustrated below through several specific embodiments.

[0079] Example 1 A method for manufacturing an electrical contact tube is provided, using a ø0.30 high-purity aluminum wire as the aluminum core mold and employing a rack plating method: the aluminum wire is vertically stretched and placed on a stainless steel rack for conductivity, and the total plating area, including the rack, is calculated to be 1.5 square decimeters based on the total length. An electrical contact tube with an inner diameter of 0.295 mm and an outer diameter of 0.45~0.46 mm is obtained. The specific steps are as follows: S1, degreasing: sodium carbonate 5g / l, sodium phosphate 15g / l, sodium silicate 5g / l, T 60℃, cathode current 3.5A, anode using graphite plate, electrolysis for 1 minute.

[0080] S2, Degreasing and Electropolishing: Add approximately 15% dilute nitric acid with 2g / l of low-foaming nonionic surfactant as the electrolyte, use high-purity precision aluminum wire as the cathode and graphite plate as the anode, with a cathode current density of 5 A and a time of 1 min.

[0081] S3, Zinc Immersion: Sodium hydroxide 120g / l, zinc oxide 20g / l, crystalline ferric chloride 1.5g / l, potassium sodium tartrate 45g / l, sodium nitrate 1.0g / l, temperature 20℃, time 30 seconds.

[0082] S4, pre-plating gold, citric acid micro-cyanide system, potassium gold cyanide content 1.2g / l, potassium citrate 50g / l, pH 5.2, temperature 57℃, control voltage 3.0V, pre-plating time 1 minute, anode using platinum titanium mesh.

[0083] S5, gold plating, citric acid micro-cyanide system, potassium gold cyanide content 8.0 g / l, cobalt sulfate 1.5 g / l, EDTA 1.5 g / l, potassium citrate 50 g / l, potassium dihydrogen phosphate 50 g / l, pyridine sulfonic acid 0.3 g / l and polyethyleneimine 0.5 g / l as bright electroplating additives, pH 4.2, temperature 50℃, platinum titanium mesh is used as the anode, cathode current is 5 A; gold plating time is 1 minute.

[0084] The S6 nickel-tungsten plating solution formula is as follows: Sodium tungstate (Na2WO4•2H2O) 130g / l; Nickel aminosulfonate [Ni(NH2SO3)2•4H2O)] 100g / l; Citric acid (C6H8O7•H2O) 120g / l; Adjust the pH value to 7.2 with ammonia.

[0085] The electroplating process parameters are as follows: anode is 316L stainless steel plate; temperature is 70℃; current is 20 A; time is 1 minute; and the thickness of the nickel-tungsten alloy plating layer is 1.5 micrometers.

[0086] S7, electroplated nickel is a high-ammonia nickel concentration, low-stress system, with nickel ion content of 140 g / l, boric acid of 40 g / l, saccharin of 0.8 g / l, temperature of 60℃, pH of 4.0, working current of 6A, nickel plating time of 90 minutes, and nickel plating layer thickness of approximately 80 micrometers.

[0087] S8, after cleaning and drying, cut the electroforming wire multiple times, bundle it into a bundle, and cut the EDM wire into 4.0mm long segments.

[0088] S9, Ultrasonic alkaline solution dissolution of aluminum core: NaOH 100g / l, sodium gluconate 20g / l, 70℃, ultrasonic frequency 28~40KHz sweep, ultrasonic power 60W / L, until the aluminum core is completely dissolved.

[0089] S10, chromic acid to remove zinc film residue from gold surface: 100~150g / l of chromic acid, room temperature, 2~3 minutes, then clean and dry to obtain an electrical contact tube with a length of 4.0m, an inner diameter of 0.295mm, and an outer diameter of 0.45~0.46mm.

[0090] Example 2 A method for manufacturing an electrical contact tube is provided. High-purity bright aluminum wire (ø0.25 mm) is used as the aluminum core mold. A rack plating method is employed, where the aluminum wire is vertically stretched and placed on a stainless steel rack for conductivity. Including the rack, the total plating area is calculated to be 1.4 square decimeters. An electrical contact tube with an inner diameter of 0.245 mm and an outer diameter of 0.350~0.355 mm is obtained. The specific steps are as follows: S1, Cathode degreasing: Sodium carbonate 10g / l, sodium phosphate 15g / l, sodium silicate 10g / l, T (temperature) 60℃, cathode current 3.0A, anode using graphite plate, electrolysis for 1 minute.

[0091] S2, Electrolytic Degreasing and Electrolytic Polishing: 15% dilute nitric acid with 3g / l low-foaming nonionic surfactant is added as electrolyte. High-purity precision aluminum wire is used as cathode and graphite plate is used as anode. The cathode current density is 7 A and the time is 1 min.

[0092] S3, Zinc Immersion: Sodium hydroxide 120g / l, zinc oxide 20g / l, crystalline ferric chloride 1.5g / l, potassium sodium tartrate 45g / l, sodium nitrate 1.0g / l, temperature 20℃, time 25 seconds.

[0093] S4, pre-plated with gold, citric acid micro-cyanide system, potassium gold cyanide content 2.0g / l, potassium citrate 60g / l, pH 5.4, temperature 55℃, controlled voltage 3.2V, anode using platinum titanium mesh, time 1.5 minutes.

[0094] S5, gold plating, citric acid micro-cyanide system, potassium gold cyanide content 9.0 g / l, cobalt sulfate 1.5 g / l, EDTA 1.5 g / l, potassium citrate 65 g / l, potassium dihydrogen phosphate 60 g / l, pyridine sulfonic acid 0.3 g / l and polyethyleneimine 0.5 g / l as bright electroplating additives, pH value 4.3, temperature 45℃, anode using platinum titanium mesh, cathode current 5 A; gold plating time 1 minute, gold thickness 1.2 micrometers.

[0095] The S6 nickel-tungsten plating solution formula is as follows: Sodium tungstate (Na2WO4•2H2O) 140g / l; Nickel aminosulfonate [Ni(NH2SO3)2•4H2O)] 100g / l; Citric acid (C6H8O7•H2O) 120g / l; Adjust the pH value to 7.1 with ammonia.

[0096] The electroplating process parameters are as follows: anode is 316L stainless steel plate, temperature is 70℃; current is 21A; time is 1 minute, and the thickness of the nickel-tungsten alloy plating is 1.6 micrometers.

[0097] S7, electroplated nickel is a high-ammonia nickel concentration, low-stress system with nickel ion content of 135 g / l, boric acid of 40 g / l, saccharin of 0.6 g / l, temperature of 65℃, pH of 3.9, working current of 6A, nickel plating time of 55 minutes, and nickel plating layer thickness of approximately 50 micrometers.

[0098] S8, after cleaning and drying, cut the electroforming wire multiple times, bundle it into a bundle, and cut the EDM wire into 3.5mm long segments.

[0099] S9, Ultrasonic alkaline solution dissolution of aluminum core: NaOH 120g / l, sodium gluconate 20g / l, 70℃, ultrasonic frequency 28KHz fixed frequency, ultrasonic power 50W / L, until the aluminum core is completely dissolved.

[0100] S10, Chromic acid removal of zinc plating residue on gold surface: 120g / l chromic acid, room temperature, 2 minutes, then clean and dry to obtain an electrical contact tube with a length of 3.5mm, an inner diameter of 0.245mm, and an outer diameter of 0.350~0.355mm.

[0101] Example 3 A method for manufacturing an electrical contact tube is provided. High-purity bright aluminum wire (ø0.20) is used as the aluminum core mold. A rack plating method is employed, where the aluminum wire is vertically stretched and placed on a stainless steel rack for conductivity. Including the rack, the total plating area is calculated to be 1.3 square decimeters. An electrical contact tube with an inner diameter of 0.195 mm and an outer diameter of 0.30~0.31 mm is obtained. The specific steps are as follows: S1, Cathode degreasing: Sodium carbonate 10g / l, sodium phosphate 18g / l, sodium silicate 5g / l, T 60℃, cathode current 4.0A, anode using graphite plate, electrolysis for 1 minute.

[0102] S2, Electrolytic Degreasing and Electrolytic Polishing: 15% dilute nitric acid with 2.5 g / L low-foaming nonionic surfactant is added as the electrolyte. High-purity precision aluminum wire is used as the cathode, and graphite plate is used as the anode. The cathode current density is 5 A, and the time is 1 min.

[0103] S3, Zinc Immersion: Sodium hydroxide 135g / l, zinc oxide 22g / l, crystalline ferric chloride 1.0g / l, potassium sodium tartrate 45g / l, sodium nitrate 1.0g / l, temperature 22℃, time 30 seconds.

[0104] S4, pre-plated with gold, citric acid micro-cyanide system, potassium gold cyanide content 2.5g / l, potassium citrate 65g / l, pH 5.2, temperature 55℃, controlled voltage 2.8V, anode using platinum titanium mesh, time 1.0 minute.

[0105] S5, gold plating, citric acid micro-cyanide system, potassium gold cyanide content 7.0 g / l, cobalt sulfate 1.5 g / l, EDTA 1.5 g / l, potassium citrate 65 g / l, potassium dihydrogen phosphate 55 g / l, pyridine sulfonic acid 0.3 g / l and polyethyleneimine 0.5 g / l as bright electroplating additives, pH value 4.2, temperature 44℃, anode using platinum titanium mesh, cathode current 4.5 A; gold plating time 1 minute, gold thickness 1.1 micrometers.

[0106] The S6 nickel-tungsten plating solution formula is as follows: Sodium tungstate (Na2WO4•2H2O) 120g / l; Nickel aminosulfonate [Ni(NH2SO3)2•4H2O)] 90 g / L; Citric acid (C6H8O7•H2O) 125g / l; Adjust the pH value to 7.2 with ammonia.

[0107] The electroplating process parameters are as follows: anode is 316L stainless steel plate; temperature is 65℃; current is 20 A; The time was 45 seconds, and the thickness of the nickel-tungsten alloy plating layer was 1.2 micrometers.

[0108] S7 electroplated nickel is a high-ammonia nickel concentration, low-stress system with nickel ion content of 130 g / L, boric acid of 38 g / L, and saccharin of 0.7 g / L. The plating process is carried out at 65℃, pH 4.1, operating current of 6.5 A, and a plating time of 55 minutes, resulting in a nickel plating layer thickness of approximately 50 micrometers.

[0109] S8, after cleaning and drying, cut the electroforming wire multiple times, bundle it into a bundle, and cut the EDM wire into 2.5mm long segments.

[0110] S9, Ultrasonic alkaline solution dissolution of aluminum core: NaOH 130g / l, sodium gluconate 15g / l, 70℃, ultrasonic frequency 40KHz fixed frequency, ultrasonic power 70W / L, until the aluminum core is completely dissolved.

[0111] S10, Chromic acid removal of zinc plating residue on gold surface: 100g / l chromic acid, room temperature, 2 minutes, then clean and dry to obtain an electrical contact tube with a length of 2.5mm, an inner diameter of 0.195mm and an outer diameter of 0.30~0.31mm.

[0112] Example 4 A method for manufacturing an electrical contact tube is provided. High-purity bright aluminum wire (ø0.15 mm) is used as the aluminum core mold. A rack plating method is employed, where the aluminum wire is vertically stretched and placed on a stainless steel rack for conductivity. Including the rack, the total plating area is calculated to be 1.1 square decimeters. This yields an electrical contact tube with an inner diameter of 0.145 mm and an outer diameter of 0.25~0.26 mm. The specific steps are as follows: S1, Cathode degreasing: Sodium carbonate 15g / l, sodium phosphate 15g / l, sodium silicate 10g / l, T 60℃, cathode current 3.5A, anode using graphite plate, electrolysis for 1 minute.

[0113] S2, Electrolytic Degreasing and Electrolytic Polishing: 15% dilute nitric acid with 2.0 g / L low-foaming nonionic surfactant is added as the electrolyte. High-purity precision aluminum wire is used as the cathode, and graphite plate is used as the anode. The cathode current density is 5 A, and the time is 1 min.

[0114] S3, Zinc Immersion: Sodium hydroxide 130g / l, zinc oxide 20g / l, crystalline ferric chloride 1.5g / l, potassium sodium tartrate 45g / l, sodium nitrate 1.5g / l, temperature 24℃, time 25 seconds.

[0115] S4, pre-plated with gold, citric acid micro-cyanide system, potassium gold cyanide content 2.0g / l, potassium citrate 60g / l, pH 5.3, temperature 55℃, controlled voltage 3.0V, anode using platinum titanium mesh, time 1.0 minute.

[0116] S5, gold plating, citric acid micro-cyanide system, potassium gold cyanide content 5.0 g / l, cobalt sulfate 1.5 g / l, EDTA 1.5 g / l, potassium citrate 55 g / l, potassium dihydrogen phosphate 50 g / l, pyridine sulfonic acid 0.3 g / l and polyethyleneimine 0.5 g / l as electroplating additives, pH value 4.5, temperature 45℃, anode using platinum titanium mesh, cathode current 3.0 A; gold plating time 1 minute, gold thickness 1.0 micrometer.

[0117] S6, Nickel-Tungsten Plating Solution Formula: Sodium tungstate (Na2WO4•2H2O) 120g / l; Nickel aminosulfonate [Ni(NH2SO3)2•4H2O)] 90 g / L; Citric acid (C6H8O7•H2O) 125g / l; Adjust the pH value to 7.1 with ammonia.

[0118] The electroplating process parameters are as follows: anode is 316L stainless steel plate; temperature is 68℃; current is 20 A; time is 55 seconds; and nickel-tungsten plating thickness is 1.4 micrometers.

[0119] S7, electroformed nickel is a high-ammonia nickel concentration, low-stress system with nickel ion content of 135 g / l, boric acid of 40 g / l, saccharin of 0.50 g / l, temperature of 63℃, pH of 4.2, working current of 5.5 A, nickel plating time of 55 minutes, and nickel plating layer thickness of approximately 50 micrometers.

[0120] S8. After cleaning and drying, cut the electroforming wire multiple times, bundle it into a bundle, and cut the EDM wire into 2.5mm long segments.

[0121] S9. Ultrasonic alkaline solution dissolution of aluminum core: NaOH 150g / l, sodium gluconate 15g / l. Process parameters: temperature 70℃, ultrasonic frequency 40KHz fixed frequency, ultrasonic power 60W / L, time until the aluminum core is completely dissolved.

[0122] S10. Chromic acid removal of zinc plating residue on gold surface: 120 g / L chromic acid, room temperature, 2 minutes, then clean and dry to obtain an electrical contact tube with a length of 2.5 mm, an inner diameter of 0.145 mm, and an outer diameter of 0.25~0.26 mm.

[0123] The present application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present application. Therefore, the content of this specification should not be construed as a limitation of the present application.

Claims

1. A method for manufacturing an electrical contact tube, characterized in that, include: Provide core molds; The core mold is subjected to degreasing, polishing and zinc immersion treatment in sequence to form a zinc film layer on the surface of the core mold, thereby obtaining a zinc-immersed core mold; An electroplating composite layer is applied to the outer surface of the zinc film layer of the zinc-immersed core mold to obtain an electroplated product; The electroplated electrical contact composite layer comprises: a lubricating electrical contact layer, a wear-resistant electrical contact layer, and a wear-resistant and corrosion-resistant support layer, sequentially electroplated; the lubricating electrical contact layer is a pure gold layer, the wear-resistant electrical contact layer is a hard gold layer, and the wear-resistant and corrosion-resistant support layer is a nickel-tungsten alloy layer or a nickel-phosphorus alloy layer; the nickel-tungsten alloy layer is a nanocrystalline nickel-tungsten alloy electrodeposition layer, and the nickel-phosphorus alloy layer is an amorphous nickel-phosphorus alloy electrodeposition layer; wherein, the lubricating electrical contact layer is deposited in a gold plating solution in a weakly acidic citric acid microcyanide system. Electroplating a substrate layer on the outer surface of the electroplated product yields an electroplated product, wherein the substrate layer is a nickel layer or a copper layer. The core mold and zinc film layer of the electroformed product are dissolved by chemical etching to obtain the hollow electrical contact tube; The chemical etching includes: removing the core mold with an ultrasonic-assisted alkaline solution; and removing the zinc film layer with an ultrasonic-assisted chromic acid solution.

2. The method for manufacturing an electrical contact tube according to claim 1, characterized in that, The electroformed product is cut before undergoing the chemical etching process, and after the chemical etching process, the end is shaped.

3. The method for manufacturing an electrical contact tube according to claim 1, characterized in that, The core mold is a cylindrical aluminum core mold with an outer diameter of 0.05mm to 0.45mm.

4. The method for manufacturing an electrical contact tube according to claim 1, characterized in that, The degreasing process includes: placing the core mold as the cathode and the graphite plate as the anode in a first electrolyte for electrolysis, wherein the first electrolyte comprises: sodium carbonate 5 g / L ~ 10 g / L, sodium phosphate 10 g / L ~ 20 g / L and sodium silicate 5 g / L ~ 10 g / L; The polishing process includes: placing the degreased core mold as the cathode and the graphite plate as the anode in a second electrolyte for electrolytic reaction, thereby reducing the surface roughness of the core mold to Rz≤0.

15. The second electrolyte is dilute nitric acid containing a nonionic surfactant.

5. The method for manufacturing an electrical contact tube according to claim 1, characterized in that, The zinc immersion treatment process parameters are: temperature 20℃~24℃, time 25s~40s; and / or, The zinc immersion solution used in the zinc immersion treatment includes: sodium hydroxide 120 g / l~140 g / l, zinc oxide 20 g / l~22 g / l, crystalline ferric chloride 1.5 g / l~2.0 g / l, potassium sodium tartrate 45 g / l~55 g / l and sodium nitrate 0.8 g / l~1.2 g / l.

6. The method for manufacturing an electrical contact tube according to claim 1, characterized in that, The method for preparing the pure gold layer includes: depositing pure gold onto the surface of the zinc film layer using an electrolytic reaction to form a pure gold layer.

7. The method for manufacturing an electrical contact tube according to claim 6, characterized in that, The electroplating solution for the pure gold layer comprises: potassium gold cyanide 1.2 g / L ~ 3.0 g / L, potassium citrate 40 g / L ~ 80 g / L; and / or The electroplating process parameters are: pH value 5.2~5.6, temperature 53℃~57℃, voltage 2.5 V~3.5 V; and / or, The anode is a platinum titanium mesh.

8. The method for manufacturing an electrical contact tube according to claim 1, characterized in that, The method for preparing the hard gold layer includes: depositing a gold-nickel alloy or a gold-cobalt alloy onto the surface of the lubricating electrical contact layer using an electrolytic reaction to obtain a gold-nickel alloy layer or a gold-cobalt alloy layer, which is the hard gold layer.

9. The method for manufacturing an electrical contact tube according to claim 8, characterized in that, The electroplating solution for the gold-cobalt alloy layer comprises: potassium gold cyanide 4.0 g / L ~ 12 g / L, cobalt sulfate 1.2 g / L ~ 1.8 g / L, potassium citrate 50 g / L ~ 70 g / L, potassium dihydrogen phosphate 50 g / L ~ 70 g / L, and a brightener; and / or, The electroplating process parameters are: pH value 4.0~4.5, temperature 40℃~60℃, and current density 0.5 A / dm³. 2 ~15 A / dm 2 ; and / or, The anode is a platinum titanium mesh.

10. The method for manufacturing an electrical contact tube according to claim 1, characterized in that, The method for preparing the nickel-tungsten alloy layer or nickel-phosphorus alloy layer includes: depositing the nickel-tungsten alloy or nickel-phosphorus alloy onto the surface of the wear-resistant electrical contact layer using an electrolytic reaction to obtain the nickel-tungsten alloy layer or nickel-phosphorus alloy layer.

11. The method for manufacturing an electrical contact tube according to claim 10, characterized in that, The electroplating solution for the nickel-tungsten alloy layer comprises: sodium tungstate 80 g / L ~ 150 g / L, nickel aminosulfonate 50 g / L ~ 125 g / L, and citric acid 100 g / L ~ 150 g / L; and / or, The electroplating process parameters are: pH value 7.0~8.5, temperature 65℃~70℃, and current density 10 A / dm³. 2 ~20A / dm 2 ; and / or, The anode is made of 316L stainless steel.

12. The method for manufacturing an electrical contact tube according to claim 1, characterized in that, The method for preparing the nickel or copper layer includes: depositing nickel or copper onto the surface of the electroplated electrical contact composite layer using an electrolytic reaction to form a nickel or copper layer.

13. The method for manufacturing an electrical contact tube according to claim 12, characterized in that, The electroforming solution for the nickel layer comprises: nickel ions 140 g / L ~ 150 g / L and boric acid 30 g / L ~ 40 g / L; and / or, The electroforming process parameters are: pH value 3.8~4.2, temperature 60℃~65℃, and current density 25 A / dm³. 2 ~35 A / dm 2 .

14. An electrical contact tube, characterized in that, Prepared by the method described in any one of claims 1-13, the structure comprises, from the inner layer to the outer layer: an electrical contact composite layer and a substrate layer, wherein the substrate layer covers the surface of the electroplated electrical contact composite layer.

15. The electrical contact tube according to claim 14, characterized in that, The electrical contact composite layer includes a lubricating electrical contact layer, a wear-resistant electrical contact layer, and a wear-resistant and corrosion-resistant support layer stacked sequentially from the inner layer to the outer layer, wherein the wear-resistant electrical contact layer covers the surface of the lubricating electrical contact layer, and the wear-resistant and corrosion-resistant support layer covers the surface of the wear-resistant electrical contact layer.

16. The electrical contact tube according to claim 15, characterized in that, The thickness of the lubricating electrical contact layer is 0.025 μm to 0.15 μm; and / or, The thickness of the wear-resistant electrical contact layer is 0.5μm~1.5μm; and / or, The thickness of the wear-resistant and corrosion-resistant support layer is 0.8 μm to 1.5 μm; and / or, The thickness of the substrate layer is greater than 25 μm.

17. The electrical contact tube according to claim 15, characterized in that, The hardness of the wear-resistant electrical contact layer is 130 HV ~ 210 HV; and / or, The hardness of the wear-resistant and corrosion-resistant support layer is 450 HV ~ 500 HV; and / or, The hardness of the substrate layer is 180 HV ~ 250 HV.

18. The electrical contact tube according to any one of claims 14-17, characterized in that, The outer diameter of the electrical contact tube is 0.08 mm to 0.35 mm, the inner diameter is 0.05 mm to 0.45 mm, and the wall thickness is 25 μm to 50 μm.

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