Continuous electroplating process for electric connection terminal

Abstract

The invention relates to the technical field of electroplating production, in particular to a continuous electroplating process for an electric connection terminal. Comprising a discharging unit for releasing a terminal material strip, a surface pretreatment unit, an electrolytic degreasing unit, a tin plating unit, a high-temperature nickel plating unit, a nickel correction unit, a gold plating unit, an electrolytic activation unit, an acid pickling activation unit, an ultrasonic oil removal unit and a receiving unit for rolling the electroplated terminal material strip, which are sequentially arranged in a straight line. In the working treatment process of the electroplating equipment, due to the fact that the number of the nickel plating tanks is two, in the electroplating operation engineering of the coil stock workpiece, secondary nickel plating is conducted on the coil stock workpiece firstly, then gold plating is conducted on the coil stock workpiece, and through bottoming of the secondary nickel plating layer, combination of the gold plating layer and the coil stock workpiece is more compact and reliable; and particularly, after secondary nickel plating processing, the magnetism of the coil stock workpiece is basically eliminated, the effect is obvious, and the practicability is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electroplating equipment and process, in particular to a continuous electroplating process for electrical connection terminals. BACKGROUND

[0002] Electrodeposition is a technology that uses electrolysis principle to deposit metal coating on the surface of base material. This process can be used to form anti-erosion protective layer, improve the appearance effect, or adjust the physical and chemical properties of the material surface layer, so as to prepare a metal covering layer with specific composition and functionality. As a key surface treatment method, electrodeposition technology has been widely used in many industries.

[0003] Nickel plating plays a key transitional role therein: the nickel layer can serve as an intermediate layer to connect the underlying substrate and the external functional plating layer, significantly improving the interlayer bonding strength. At the same time, this plating layer can optimize the flatness and light reflection performance of the substrate surface, enhancing the visual effect of the product. Due to its dense structure, the nickel plating layer can also effectively block corrosive media, providing reliable protection performance. For this reason, in the field of electronic components and semiconductor packaging, this technology is particularly commonly used for copper and copper alloy substrates as an anti-oxidation coating to improve the durability and stability performance of the product, and has been widely used on a large scale. However, the existing nickel plating process has low reliability and needs to be further improved in terms of durability. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a continuous electroplating process for electrical connection terminals by adding one more nickel plating process based on the original single nickel plating process.

[0005] To solve the above technical problems, the present application adopts the following technical scheme: a continuous electroplating process for electrical connection terminals, comprising a feeding unit for releasing the terminal tape, a surface pretreatment unit, an electrolytic degreasing unit, a tin plating unit, a high-temperature nickel plating unit, a nickel correction unit, a gold plating unit, an electrolytic activation unit, an acid pickling activation unit, an ultrasonic oil removal unit, and a winding unit for winding the terminal tape after electroplating, which are arranged in sequence. In the surface pretreatment unit, the terminal tape is treated by pouring with an aqueous alkali solution, which comprises a buffer, a surfactant, a chelating agent, and sodium hydroxide with a mass concentration of 20-50 g / L. In the high-temperature nickel plating unit, the terminal tape is treated by pouring with nickel plating solution in the electroplating tank, which comprises nickel sulfamate, boric acid, sulfamic acid, and nickel chloride, and nickel beads are placed in the electroplating tank.

[0006] Preferably, in the surface pretreatment unit, the buffer is sodium carbonate or trisodium phosphate, the surfactant is alkyl sulfonate, and the chelating agent is ethylenediaminetetraacetic acid.

[0007] Preferably, in the tinning unit, the terminal material belt is subjected to showering treatment in the electroplating tank by using tinning liquid, the tinning liquid comprises tin methanesulfonate with a mass concentration of 55-75 g / L, methanesulfonic acid with a volume concentration of 175-245 ml / L and additives, and pure tin blocks are placed in the electroplating tank.

[0008] Preferably, in the tinning unit, the temperature of the electroplating tank is maintained at 45-55 degrees Celsius.

[0009] Preferably, in the nickel modification unit, the terminal material belt is subjected to showering treatment in the electroplating tank by using nickel modification liquid, the nickel modification liquid comprises nickel sulfamate, boric acid and additives, and nickel beads or nickel beads are placed in the electroplating tank.

[0010] Preferably, the material of the additives is a mixture of two or more of brightener, dispersant, stabilizer, leveling agent, wetting agent and complexing agent.

[0011] Preferably, in the electrolytic activation unit, the terminal material belt is subjected to showering treatment in the electroplating tank by using diluted activation acid in an environment of 20-28 degrees Celsius; in the pickling activation unit, the terminal material belt is subjected to showering treatment in the electroplating tank by using diluted industrial sulfuric acid in an environment of 20-26 degrees Celsius.

[0012] Preferably, in the electrolytic degreasing unit, the terminal material belt is subjected to showering treatment in the electroplating tank by using diluted and dissolved degreasing powder in an environment of 53-63 degrees Celsius.

[0013] Preferably, in the ultrasonic degreasing unit, the terminal material belt is subjected to showering treatment in the electroplating tank by using diluted and dissolved degreasing powder in an environment of 50-60 degrees Celsius, and an ultrasonic vibration generator is arranged at the bottom of the electroplating tank.

[0014] The present application has the advantages that the present application provides a continuous electroplating process for electrical terminal, in the process of electroplating nickel, the nickel electrode is used as anode and the workpiece to be plated is used as cathode. When electricity is applied in the electrolyte, nickel ions obtain electrons on the cathode, thereby being reduced into metal nickel and deposited on the workpiece to form a uniform and dense nickel plating layer, which lays a solid foundation for subsequent gold plating. In the working process of the electroplating equipment, the number of nickel plating tanks is two, the workpiece is subjected to secondary nickel plating before gold plating, the combination of the gold plating layer and the workpiece is more dense and reliable, and the magnetic property of the workpiece is basically eliminated after secondary nickel plating, which is obviously effective and practical. BRIEF DESCRIPTION OF DRAWINGS

[0015] Fig. 1This is a three-dimensional structural diagram of the continuous electroplating process equipment for electrical terminals according to the present invention.

[0016] Fig. 2 A top view of the continuous electroplating process equipment for electrical terminals of the present invention. Detailed Implementation

[0017] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments. The content mentioned in the embodiments is not intended to limit the present invention.

[0018] like Figs. 1-2 As shown, a continuous electroplating process for electrical terminals includes a feeding unit for releasing terminal strips, a surface pretreatment unit, an electrolytic degreasing unit, a tin plating unit 1, a high-temperature nickel plating unit 2, a nickel correction unit 3, a gold plating unit 4, an electrolytic activation unit 5, an acid pickling activation unit, an ultrasonic degreasing unit, and a receiving unit for winding up the electroplated terminal strips, arranged in sequence. In the surface pretreatment unit, the terminal strips are treated with an alkaline aqueous solution, which includes a buffer, a surfactant, a chelating agent, and sodium hydroxide with a mass concentration of 20–50 g / L, providing a high pH environment for degreasing and removing the oxide layer. In the high-temperature nickel plating unit 2, the terminal strips are treated with a nickel plating solution in an electroplating tank, which includes nickel sulfamate, boric acid, aminosulfonic acid, and nickel chloride, and nickel beads are placed in the electroplating tank.

[0019] In the nickel electroplating process, a nickel plating electrode is used as the anode, and the coil workpiece to be plated is used as the cathode. When an electric current is passed through the electrolyte, nickel ions gain electrons at the cathode, thereby being reduced to metallic nickel and deposited on the workpiece strip at the cathode, forming a uniform and dense nickel plating layer, laying a solid foundation for subsequent gold plating. In the working process of the electroplating equipment of this invention, since there are two nickel plating tanks, in the electroplating operation of the coil workpiece, the coil workpiece is first subjected to secondary nickel plating before gold plating. Through the secondary nickel plating layer, the bonding between the gold plating layer and the coil workpiece is more dense and reliable. In particular, after the secondary nickel plating process, the magnetism of the coil workpiece is basically eliminated, with significant effects and strong practicality.

[0020] In this embodiment, the surface pretreatment unit uses sodium carbonate or trisodium phosphate as a buffer to stabilize the pH value and enhance the emulsification effect. The surfactant is an alkyl sulfonate to assist in the emulsification of oils and improve the wettability of the electroplating solution. The chelating agent is ethylenediaminetetraacetic acid to prevent the precipitation of metal ions and ensure the reliable tin plating process.

[0021] In this embodiment, in the tin plating unit 1, the terminal strip is treated by pouring tin plating solution into the electroplating tank. The tin plating solution includes tin methanesulfonate with a mass concentration of 55–75 g / L, methanesulfonic acid with a volume concentration of 175–245 ml / L, and additives. Pure tin blocks are placed in the electroplating tank. Specifically, the temperature of the electroplating tank is maintained at 45–55 degrees Celsius.

[0022] In this embodiment, in the nickel correction unit 3, the terminal strip is treated by pouring nickel correction solution into the electroplating tank. The nickel correction solution includes nickel sulfamate, boric acid and additives, and nickel beads or nickel beads are placed in the electroplating tank.

[0023] In this embodiment, the additive is a mixture of two or more of the following: brightener, dispersant, stabilizer, leveling agent, wetting agent, and complexing agent. The brightener, benzaldehyde, is used to obtain a bright and fine plating structure. The dispersant, a nonionic surfactant, is used to solubilize the brightener, refine crystals, suppress acid mist, and ensure the stability of the electroplating process. The stabilizer effectively prevents the oxidation of divalent tin, keeping the plating solution clear. The leveling agent fills microscopic defects in the substrate to obtain a smooth surface. The wetting agent reduces surface tension, eliminates pinholes and pits, and further improves the smoothness of the plating surface. The complexing agent, EDTA or citrate, is used to stabilize the plating solution, improve the uniformity of the alkaline system, and significantly enhance reliability.

[0024] In this embodiment, in the electrolytic activation unit 5, the terminal strip is treated by pouring diluted activating acid into the electroplating tank at an environment of 20-28 degrees Celsius; in the pickling activation unit, the terminal strip is treated by pouring diluted industrial sulfuric acid into the electroplating tank at an environment of 20-26 degrees Celsius. This thoroughly removes the extremely thin passivation film on the surface of the workpiece to be plated and puts its surface in a highly activated and easily deposited state, thereby ensuring an extremely strong adhesion between the nickel plating layer and the substrate, making it highly practical.

[0025] In this embodiment, in the electrolytic degreasing unit, the terminal strip is treated by pouring diluted and dissolved degreasing powder into the electroplating tank at an environment of 53-63 degrees Celsius.

[0026] Electrolysis thoroughly removes various oils, greases, and minor impurities from the surface of metal workpieces, providing an absolutely clean active surface for subsequent electroplating, oxidation, or other surface treatments. This ensures excellent adhesion between the plating layer and the substrate. Ensuring that subsequent acid activation, electroplating, and other processes can be carried out on a perfectly clean substrate is a crucial guarantee for high-yield electroplated products. In this embodiment, in the ultrasonic degreasing unit, the terminal strip is treated by pouring diluted and dissolved degreasing powder into the electroplating tank at an environment of 50-60 degrees Celsius. An ultrasonic oscillation generator is installed at the bottom of the electroplating tank.

[0027] In the description of this invention, it should be noted that the directional terms such as "center", "horizontal (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", and "counterclockwise" indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific protection scope of this invention.

[0028] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features. Thus, the use of "first" and "second" to define a feature may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "assembly," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection; they can refer to a direct connection or a connection through an intermediate medium; or they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0030] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A continuous electroplating process for electrical terminals, characterized in that: It includes a feeding unit, a surface pretreatment unit, an electrolytic degreasing unit, a tin plating unit (1), a high-temperature nickel plating unit (2), a nickel correction unit (3), a gold plating unit (4), an electrolytic activation unit (5), an acid pickling activation unit, an ultrasonic degreasing unit, and a winding unit for rewinding the electroplated terminal strip, arranged in a straight line. In the surface pretreatment unit, the terminal strip is treated with an alkaline aqueous solution, which includes a buffer, a surfactant, a chelating agent and sodium hydroxide with a mass concentration of 20–50 g / L. In the high-temperature nickel plating unit (2), the terminal strip is treated by pouring nickel plating solution into the electroplating tank. The nickel plating solution includes nickel aminosulfonate, boric acid, aminosulfonic acid and nickel chloride. Nickel beads are placed in the electroplating tank.

2. The continuous electroplating process for electrical terminals according to claim 1, characterized in that: In the surface pretreatment unit, the buffer is sodium carbonate or trisodium phosphate, the surfactant is alkyl sulfonate, and the chelating agent is ethylenediaminetetraacetic acid.

3. The continuous electroplating process for electrical terminals according to claim 1, characterized in that: In the tin plating unit (1), the terminal strip is treated by pouring tin plating solution into the electroplating tank. The tin plating solution includes tin methanesulfonate with a mass concentration of 55–75 g / L, methanesulfonic acid with a volume concentration of 175–245 ml / L, and additives. Pure tin blocks are placed in the electroplating tank.

4. The continuous electroplating process for electrical terminals according to claim 3, characterized in that: In the tin plating unit (1), the temperature of the electroplating bath is maintained at 45-55 degrees Celsius.

5. The continuous electroplating process for electrical terminals according to claim 1, characterized in that: In the nickel correction unit (3), the terminal strip is treated by pouring nickel correction solution into the electroplating tank. The nickel correction solution includes nickel aminosulfonate, boric acid and additives. Nickel beads or nickel balls are placed in the electroplating tank.

6. The continuous electroplating process for electrical terminals according to claim 3 or 5, characterized in that: The additive is a mixture of two or more of the following: brightener, dispersant, stabilizer, leveling agent, wetting agent, and complexing agent.

7. The continuous electroplating process for electrical terminals according to claim 1, characterized in that: In the electrolytic activation unit (5), the terminal strip is treated by rinsing with diluted activating acid in the electroplating tank at an environment of 20-28 degrees Celsius; in the pickling activation unit, the terminal strip is treated by rinsing with diluted industrial sulfuric acid in the electroplating tank at an environment of 20-26 degrees Celsius.

8. The continuous electroplating process for electrical terminals according to claim 1, characterized in that: In the electrolytic degreasing unit, the terminal strip is treated by pouring diluted and dissolved degreasing powder into the electroplating tank at an environment of 53-63 degrees Celsius.

9. The continuous electroplating process for electrical terminals according to claim 1, characterized in that: In the ultrasonic degreasing unit, the terminal strip is treated by pouring diluted and dissolved degreasing powder into the electroplating tank at an environment of 50-60 degrees Celsius. An ultrasonic oscillation generator is installed at the bottom of the electroplating tank.

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