Process for uniformly distributing electronickelling layer

Abstract

The invention provides a process for uniformly distributing an electroplated nickel layer, which comprises the following steps: a self-adaptive adjustable electrode system is adopted, a workpiece is put into a plating solution, and the plating solution comprises nickel sulfate, nickel chloride, boric acid, saccharin sodium salt and butynediol; and the temperature, the current density and the electroplating time of the plating solution are controlled within the preset range, and the target plating layer thickness is achieved. A leveling agent saccharin sodium salt and a walking agent butynediol are added into the plating solution, so that the uniformity of a plating layer is improved. After the saccharin sodium is dissociated, organic anions of the saccharin sodium form an adsorption film in a cathode high-activity area, nickel ion deposition is slowed down, the deposition rate of a low-activity area is relatively increased, and the surface smoothness is improved. Butynediol forms an insulating layer in a high-current-density area through polarity adsorption to reduce current, adsorption in a low-current area is little, deposition is not restrained, and the current density difference is adjusted. And in cooperation with a self-adaptive adjustable electrode system, power supply current can be dynamically adjusted according to the shape and size of the workpiece, overall current distribution is optimized, and it is guaranteed that the coating thickness of the complex workpiece is uniform.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electroplating, and more particularly relates to a process for uniformly distributing an electroplated nickel layer. BACKGROUND

[0002] As a mature surface treatment technology, the electroplated nickel layer technology can form a nickel metal film on the surface of a metal or non-metal substrate through electrolysis, and has been applied in the industrial field for more than a hundred years. The functions of the electroplated nickel layer include three aspects. In terms of protection, it forms a dense barrier to resist corrosion, enhances wear resistance, and prolongs the service life of the workpiece; in terms of performance optimization, it improves mechanical properties, enhances hardness and fatigue resistance, optimizes roughness to ensure accuracy, and buffers deformation to prevent cracking; and in terms of function, it meets the needs of conduction, shielding and decoration, and the composite coating can also be extended to special scenarios such as high temperature resistance. Therefore, the electroplated nickel layer technology is widely used in the fields of mechanical manufacturing, electronics industry and aerospace.

[0003] In the production process of the electroplated nickel layer, ensuring uniform distribution of the nickel layer is the key to improving product quality. In the existing electroplated nickel technology, for workpieces with complex shapes, uneven distribution of current on the surface of the workpiece, unreasonable stirring mode, unstable plating solution and the like will all lead to large differences in the thickness of the nickel layer. For example, the current density is higher at the corners and edges of the workpiece, and the plating layer is prone to be too thick; while the current density is lower at the grooves and deep holes, and the plating layer is thinner. Non-uniformity of the electroplated nickel layer will seriously affect its function and the reliability of the workpiece. The areas with thin plating layer are prone to become corrosion breakthroughs, leading to premature rusting of the substrate, damaging the overall corrosion barrier and shortening the service life of the workpiece. The thick plating layer parts may also crack and peel off due to stress concentration, and the thin plating layer parts lack wear resistance, aggravating local wear. At the same time, the thickness difference will lead to differences in electrical conductivity, affecting the stability of signal transmission of electronic components. The electroplated nickel layer with decorative properties will reduce product quality due to unstable appearance quality. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a process for uniformly distributing an electroplated nickel layer to solve the technical problem that it is difficult to achieve uniform distribution of the electroplated nickel layer in the prior art.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present application is to provide a process for uniformly distributing an electroplated nickel layer, comprising the following steps: S1: using an adaptive adjustable electrode system, placing the workpiece into the plating solution, and the plating solution comprising nickel sulfate, nickel chloride, boric acid, sodium saccharin and butyne diol; S2: controlling the temperature, current density and electroplating time of the plating solution within a predetermined range to achieve the target plating layer thickness.

[0006] Optionally, the adaptive adjustable electrode system comprises a main electrode and an auxiliary electrode. The profile of the main electrode towards the workpiece side matches the profile of the workpiece towards the main electrode side, so that a preset and consistent distance is maintained between different positions on the main electrode and corresponding parts of the workpiece; The auxiliary electrode is installed near the deep hole or groove part of the workpiece to adjust the current output.

[0007] Optionally, before the main electrode and the auxiliary electrode of the adaptive adjustable electrode system are put into the plating solution, the surface is cleaned and then coated with a polyaniline coating.

[0008] Optionally, the plating solution comprises the following components at the following concentrations: 280-320 g / L of nickel sulfate, 45-55 g / L of nickel chloride, 35-45 g / L of boric acid, 0.02-0.05 g / L of sodium saccharin, and 0.01-0.03 g / L of butynediol.

[0009] Optionally, the plating solution is stirred by a combination of circulating spraying and ultrasonic stirring; The circulating spraying stirring mode uses multiple nozzles that can be adjusted in multiple directions to make the plating solution in the plating tank repeatedly circulate and spray onto the surface of the workpiece.

[0010] Optionally, multiple sensors are installed in the electroplating tank to monitor the thickness of the nickel layer, the concentration of the plating solution, and the temperature of the plating solution at different parts of the workpiece in real time, and the monitored data is transmitted to the intelligent control system.

[0011] Optionally, the intelligent control system receives and analyzes the monitored data; The intelligent control system is connected to the pulse power source, so that the intelligent control system adjusts the parameters of the pulse power source to control the current density at 1.5-3 A / dm 2 , and adjusts the current density of the local workpiece in coordination with the auxiliary electrode.

[0012] Optionally, the temperature of the plating solution is controlled by a constant temperature control system to be 50-55℃, and the temperature fluctuation during electroplating does not exceed 1℃ based on the set value.

[0013] Optionally, according to the target plating layer thickness and in combination with the current density and other parameters, the electroplating time is calculated according to the Faraday's law of electrolysis, and the electroplating is completed within the electroplating time.

[0014] The process for uniformly distributing the electroplated nickel layer has the beneficial effects that compared with the prior art, the plating solution of the present application further comprises the leveling agent sodium saccharin and the positioning agent butynediol in addition to the basic components nickel sulfate, nickel chloride, and boric acid. After the leveling agent sodium saccharin is dissociated in the plating solution, the organic anion (C7H4NO3S - ) forms an adsorption film in the high activity area of the workpiece to hinder the nickel ions (Ni² +Rapid deposition in these areas accelerates the nickel ion deposition rate in low-activity regions, eliminating microscopic unevenness on the workpiece surface and improving the uniformity and smoothness of the plating layer. The alkyne and hydroxyl groups in the butynediol molecule, a leveling agent, exhibit polar adsorption properties, preferentially adsorbing in areas of high current density in the plating bath to form an insulating adsorption layer that reduces the current density in those areas. Conversely, the adsorption of alkyne and hydroxyl groups is less in low-current-density areas, thus not inhibiting nickel ion deposition. By adjusting the current density differences in different regions, the electric field lines are more evenly distributed on the workpiece surface, ensuring uniform plating thickness across complex-shaped workpieces. The adaptive adjustable electrode system determines the electrode placement based on the overall shape and size of the workpiece, optimizing the overall current distribution and promoting the formation of a uniform electroplated nickel layer. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the 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.

[0016] Figure 1 A process flow diagram for uniformly distributing the electroplated nickel layer provided in the embodiments of this application; Figure 2 This is a schematic diagram of the test points for an electroplated nickel workpiece provided in an embodiment of this application; The following are the labeling elements in the figure: P1 - Test thickness point 1; P2 - Test thickness point 2; P3 - Test thickness point 3. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] As a mature surface treatment technology, electroplated nickel layer technology can be widely used in the fields of mechanical manufacturing, electronic industry and aerospace, etc. The key to improve product quality is to ensure the uniform distribution of electroplated nickel layer. However, it is difficult to achieve uniform distribution of electroplated nickel layer in the existing electroplated nickel technology. The uneven distribution of electroplated nickel layer will seriously affect its function and the reliability of the workpiece. The areas with thin plating layer are prone to become corrosion breakthroughs, leading to premature corrosion of the substrate, damaging the overall corrosion barrier and shortening the service life of the workpiece. The thick plating layer parts may also crack and peel off due to stress concentration, and the thin plating layer parts lack wear resistance, which aggravates local wear. At the same time, the uneven thickness will lead to differences in electrical conductivity, affecting the stability of signal transmission of electronic components, and the decorative plating layer will reduce product quality due to inconsistent appearance.

[0019] In order to solve the above problems, the present application provides a process for making electroplated nickel layer uniform distribution, comprising the following steps: S1: using a self-adaptive adjustable electrode system, the workpiece is placed in the plating solution, the plating solution includes nickel sulfate, nickel chloride, boric acid, sodium saccharin and butyne diol; S2: controlling the temperature, current density and electroplating time of the plating solution within a predetermined range to achieve the target plating layer thickness.

[0020] It should be noted that the self-adaptive adjustable electrode system provided by the present application is an intelligent device used to optimize the electric field distribution in the electroplating process. The self-adaptive adjustable electrode system can calculate the best placement position of the anode according to the inherent properties of the workpiece such as shape and size, so that the distance between the anode and the workpiece is as uniform as possible, thereby optimizing the electric field distribution from the source. The self-adaptive adjustable electrode system can also detect the current density data during the electroplating process and adjust the output parameters (such as current size) of the adjustable power supply equipment to meet the needs of different plating layer thicknesses.

[0021] At the same time, the parameter setting of the electroplating process also has an impact on the uniform distribution of the electroplated nickel layer. Suitable plating solution temperature can ensure the stability of ion activity and migration rate in the plating solution. If the temperature is too low, the migration speed of nickel ions will be slow, the deposition rate will be reduced, and the plating layer may be coarse and uneven. If the temperature is too high, the additives in the plating solution are easy to decompose, and the side reactions are intensified, which will also affect the quality and uniformity of the plating layer. The current density directly determines the reduction rate of nickel ions on the surface of the workpiece. If the current density is too high, the workpiece edge and tip will cause the electric power line to concentrate, resulting in rapid and thick deposition of the plating layer, and the phenomenon of burning; if the current density is too low, the deposition speed will be slow, the production efficiency will be low, and the plating layer may be uneven. Precise electroplating time is also one of the key factors to ensure the uniformity of the plating layer thickness. If the electroplating time is too short, the target plating layer thickness cannot be achieved; if the time is too long, the local plating layer may be too thick.

[0022] The plating solution used for electroplating nickel layer includes nickel sulfate, nickel chloride, boric acid, sodium saccharin and butyne diol. Among them, nickel sulfate as the main nickel salt provides the required nickel ions for electroplating. Under the action of electric field, nickel ions migrate to the cathode (workpiece), obtain electrons to undergo reduction reaction, realize the deposition of nickel atoms on the surface of the workpiece, and form the electroplated nickel layer. Nickel sulfate provides nickel ions stably, ensuring the continuity and uniformity of the deposition process.

[0023] Among them, nickel chloride as an auxiliary salt mainly improves the conductivity of the plating solution and prevents anode passivation. The dissociated chloride ions (Cl - ) of nickel chloride can increase the ionic strength of the plating solution, reduce the solution resistance, and make the current more uniformly distributed on the surface of the workpiece, especially for complex-shaped workpieces, which can reduce the phenomenon of high current density. At the same time, Cl - can react with the anode surface to destroy the possible oxide film (NiO) on the anode surface, generate soluble NiCl2, and ensure the normal dissolution of the anode. Nickel chloride can also maintain the stability of the Ni 2+ concentration in the plating solution, avoiding the decrease of current efficiency caused by anode passivation.

[0024] Among them, boric acid can stabilize the deposition environment by adjusting the pH value of the plating solution. During electroplating, the local pH value near the cathode is easily increased due to the reduction of hydrogen ions obtaining electrons, and the too high pH value may cause the hydrolysis of nickel ions to form nickel hydroxide precipitate, which is mixed in the coating to form defects. As a weak electrolyte, boric acid can reversibly dissociate into hydrogen ions and tetrakis-hydroxyborate ions in the pH range of 3.5-5.0. This equilibrium process enables boric acid to absorb hydroxyl ions in the plating solution, flexibly adjust the concentration of hydrogen ions, and thus stabilize the pH environment of the solution. At the same time, boric acid molecules can be adsorbed on the cathode surface, improve the cathode polarization, refine the coating grain, and improve the coating density. Among them, the core function of the leveling agent sodium saccharin (C7H4NNaO3S•2H2O) is to eliminate the micro concave-convex on the surface of the workpiece, so that the coating obtains a smooth appearance. After the dissociation of sodium saccharin in the plating solution, its organic anion (C7H4NO3S - ) has a stronger adsorption capacity on the high-activity area of the cathode (such as surface protrusions and corners), forming an adsorption film to hinder the rapid deposition of nickel ions (Ni 2+ ) in these areas. This inhibitory effect relatively accelerates the deposition rate of nickel ions in low-activity areas (such as recesses), gradually filling the surface defects through the difference in deposition rate, and realizing the micro-leveling of the coating. At the same time, the adsorbed organic molecules can refine the grain arrangement, reduce the surface roughness caused by irregular crystallization, and further enhance the leveling effect.

[0025] The key role of the walking agent butynediol is to improve the current distribution and ensure the uniformity of the coating thickness of each part of the complex-shaped workpiece. The acyl group and hydroxyl group in the butynediol molecule have polar adsorption characteristics, can migrate with the electric lines (virtual lines that the electric field distribution points from the anode to the cathode) in the plating solution and preferentially adsorb in the area with high current density (such as the edge and tip of the workpiece), forming an insulating adsorption layer to reduce the current density in this area. At the same time, the adsorption amount in the low current density area (such as the groove and pore) is small, which will not inhibit the deposition of nickel ions. By adjusting the current density difference in different areas, the electric lines are more evenly distributed on the surface of the workpiece, realizing the optimization of the current walking. This effect can effectively alleviate the edge effect and deep hole effect, ensure the uniformity of the coating thickness of the inner and outer surfaces of the complex structure workpiece and the high and low current areas, and improve the universality and stability of the process.

[0026] In another embodiment of the present application, an adaptive adjustable electrode system used in the electroplating process includes a main electrode and an auxiliary electrode. The profile of the main electrode towards the workpiece side matches the profile of the workpiece towards the main electrode side, so that the preset and consistent distance is maintained between different positions on the main electrode and the corresponding parts of the workpiece. The auxiliary electrode is installed near the deep hole or groove part of the workpiece to adjust the current output.

[0027] It should be noted that in this embodiment, the customized design of the main electrode and the targeted installation of the auxiliary electrode ensure the coverage of the basic current on the surface of the workpiece by the main electrode and the precise supplementary adjustment of the current by the auxiliary electrode, further optimize the current distribution and ensure the uniformity of the coating: The main electrode is the key component to provide the core current for electroplating, which is responsible for delivering the main current for the entire electroplating system and driving the nickel ions (Ni 2+) to the cathode (workpiece) and reduce the deposited base function. The main electrode is connected to the anode of the power supply, and under the action of the electric field, a network of main electric force lines is formed from the main electrode to the workpiece, ensuring the basic rate and coverage of the deposition of the plating layer. In the traditional fixed electrode processing process, the current is easily over-concentrated in the area close to the electrode on the surface of the workpiece with complex shape and various structures, and the current may be sparse in the area far from the electrode. This uneven distribution of current directly affects the quality and thickness consistency of the plating layer. The main electrode designed according to the specific shape of the workpiece can well solve this problem. The shape of the main electrode can be designed according to the specific shape of the workpiece, and the profile of the side of the main electrode facing the workpiece matches the profile of the side of the workpiece facing the main electrode. By accurately matching the actual profile and geometric characteristics of the workpiece, a predetermined and consistent gap can be maintained between the corresponding parts of the main electrode and the workpiece, so that the electric force line network generated by the main electrode can achieve more uniform coverage and distribution on the surface of the workpiece, and the uneven distribution of current caused by distance difference can be effectively reduced. This uniform current distribution provides a solid foundation for the overall thickness consistency of the subsequent plating layer.

[0028] The auxiliary electrode is used to supplement the main electrode in the electroplating process, and the auxiliary electrode works cooperatively with the main electrode to form a high-coverage electric field adjusting network, further improving the uniformity of the current distribution on the surface of the workpiece and promoting the deposition of the nickel layer on each part of the workpiece to achieve a high-quality deposition with uniform thickness. The auxiliary electrode is installed near the current-weak areas such as grooves and deep holes of the workpiece, and realizes accurate correction of the local weak electric field through current output. Due to structural obstruction or geometric characteristics, even if the distance of the main electrode is consistent, the electric force lines may still be difficult to penetrate or the edge current may be abnormal. The auxiliary electrode strengthens the local current output to supplement the current density in the current-weak areas. Through this process, the auxiliary electrode can eliminate the deposition deviation caused by complex structures, and finally cooperates with the main electrode designed according to the specific shape of the workpiece to realize the high uniformity of the thickness and quality of the plating layer on the surface of the workpiece.

[0029] In another embodiment of the present application, the main electrode and the auxiliary electrode of the self-adaptive adjustable electrode system are subjected to surface cleaning treatment before being put into the plating solution, and then a polyaniline coating is applied.

[0030] It should be noted that the surface cleaning treatment is a basic prerequisite for ensuring stable current. The ultrasonic cleaning removes oil stains, oxide scales and impurity particles on the surface of the electrode, eliminates the insulating barrier layer that may be formed by pollutants, and avoids local open circuit or resistance mutation during current transmission; the subsequent pickling activation can further remove the surface passivation film, increase the active sites on the surface of the electrode, ensure the full contact of the electrode with the plating solution, and reduce the fluctuation of the interface contact resistance.

[0031] The coated polyaniline coating is a conductive polymer coating, which can enhance the current stability from the aspects of electrical performance and chemical stability. The coating itself has good conductivity, can uniformly cover the electrode surface, reduce local resistance difference, and reduce current fluctuations caused by uneven electrode material or micro defects; at the same time, the polyaniline coating can isolate the direct contact between corrosive ions (such as chloride ions) in the plating solution and the electrode substrate, inhibit the side reactions such as hydrogen evolution and oxidation on the electrode surface, and avoid the decrease of current efficiency caused by electrode dissolution or surface state deterioration. In addition, the polyaniline coating has high sensitivity to current changes, and can quickly adapt to the dynamic changes of current output to meet the adjustment needs of the adaptive electrode system. The polyaniline coating as a transition layer can also improve the interfacial adhesion between the nickel plating layer and the electrode substrate material, so that the electrode has excellent properties such as corrosion resistance, conductive stability and long-term reliability, and meets the high requirements of the precision electrode field.

[0032] In another embodiment of the present application, the plating solution comprises the following components at the following concentrations: 280-320 g / L nickel sulfate, 45-55 g / L nickel chloride, 35-45 g / L boric acid, 0.02-0.05 g / L sodium saccharin, and 0.01-0.03 g / L butynediol.

[0033] It should be noted that the concentration of nickel sulfate as the main salt is the largest, which is the main source of the plated metal, and needs to ensure a high deposition rate. The 45-55 g / L nickel chloride can balance the conductivity and anode dissolution efficiency, while avoiding the corrosion risk caused by excessive chloride ions. Boric acid as a buffer stabilizes the pH value of the plating solution, and 35-45 g / L is close to the saturation solubility of boric acid (especially at the plating temperature, the solubility will increase slightly), which can provide sufficient buffering capacity while avoiding crystallization problems. The 0.02-0.05 g / L sodium saccharin can be fully adsorbed in the micro-high convex area, and the surface smoothness of the plated layer is improved by slowing down the local deposition, while the nickel lattice arrangement can be effectively adjusted to reduce internal stress, and the plated layer toughness meets the standard. In this concentration range, the effects of leveling and stress relief are balanced, and the overall deposition rate is not excessively inhibited. The 0.01-0.03 g / L butynediol can selectively adsorb in the high-current area, moderately hinder the edge deposition, guide the current distribution to the low-current area, and reduce the thickness difference of the plated layer in each part of the workpiece, thereby improving the deep plating capacity; at the same time, the crystal particles are refined, the brightness of the plated layer is uniform, and the bright current density range is expanded (i.e. it is not easy to appear dark when the current fluctuates). In this concentration, the walking, brightness and deposition rate are balanced, and the overall plating efficiency is not excessively inhibited.

[0034] In another embodiment of the present application, the stirring mode of the plating solution is a combination of circulating injection and ultrasonic stirring; Circulating spray utilizes multiple direction-adjustable nozzles to make the plating solution in the plating tank repeatedly circulate and spray to the surface of the workpiece. During electroplating, the nickel ions on the surface of the workpiece will be consumed due to reduction deposition. If the plating solution is static or insufficiently flows, a low-nickel-ion-concentration area will be formed near the workpiece. Circulating spray directly sprays fresh plating solution (containing high concentration of nickel ions) to the surface of the workpiece and key areas (such as deep holes and grooves) through directional nozzles, quickly replenishes the consumed nickel ions, and at the same time, takes away the reacted waste solution (containing low concentration of nickel ions), thereby avoiding the rough and coarse plating layer caused by insufficient supply of nickel ions. The complex-shaped workpiece is prone to have over-thick edge plating layer and over-thin recess due to current concentration. The multi-directional adjustable nozzles of the circulating spray can adjust the spray angle and intensity in a targeted manner: for high-current areas (edges and corners), moderate spray impact is used to reduce the excessive adsorption of leveling agents on the surface, thereby avoiding slow deposition; for low-current areas (recesses and deep holes), directional spray is used to enhance the flowability of the plating solution, thereby assisting the leveling agent to play a role, increasing the current density, and improving the thickness uniformity of the plating layer. The high-speed liquid flow of the circulating spray can flush the surface of the workpiece, forcibly strip the attached bubbles, and reduce the plating layer defects caused by the residual bubbles.

[0035] Ultrasonic agitation utilizes high-frequency vibration generated by an ultrasonic agitation device to achieve the effect of vibrating the plating solution. The microcirculation generated by ultrasonic vibration can break the coarse crystal nucleus formed during the growth of the plating layer, promote the formation of more fine crystal nucleus, thereby refining the plating layer crystal particles; and can also make the nickel ions, leveling agents and leveling agents uniformly distributed in the plating solution, thereby ensuring the uniformity of the adsorption amount on the surface of each part of the workpiece, and further improving the uniformity of the performance of the plating layer.

[0036] The diffusion layer is a thin stagnant liquid layer formed on the surface of the workpiece during electroplating due to the consumption of metal ions, which hinders the transmission of metal ions. The circulating spray can spray fresh plating solution to the surface of the workpiece to directly replenish the nickel ions consumed near the workpiece due to deposition, thereby further weakening the hindering effect of the diffusion layer; at the same time, the high-speed sprayed plating solution can continuously flush the surface of the workpiece, break the local liquid flow stagnation state, and form a synergistic effect with the ultrasonic agitation to jointly maintain the stability of the nickel ion concentration on the surface of the workpiece, thereby ensuring the uniformity of the plating layer deposition rate and reducing the plating layer defects caused by insufficient ion supply. At the same time, this combined agitation method also solves the problems of large-area plating solution renewal and near-surface diffusion layer breakthrough, thereby ensuring that the workpiece as a whole is in a fresh plating solution environment and strengthening the ion transmission to the workpiece. For complex workpieces with deep holes, narrow slits, and concave-convex structures, the directional nozzles of the circulating spray can send the plating solution into the deep cavity, and the ultrasonic agitation can strengthen the mass transfer inside the cavity, thereby solving the problems of traditional agitation such as not being able to plating in deep holes and uneven plating.

[0037] In another embodiment of the present application, a plurality of sensors are installed in the electroplating tank to monitor the thickness of the nickel layer, the concentration of the plating solution and the temperature of the plating solution in different parts of the workpiece in real time, and the monitored data is transmitted to the intelligent control system. It should be noted that the monitoring of the sensors can provide accurate local data support, and the local data of the thickness of the nickel layer and the concentration and temperature of the plating solution in different parts of the workpiece can be obtained, avoiding the blind area of traditional overall monitoring, so that the system can accurately perceive the local state. At the same time, the data monitored by the sensors can assist in optimizing the electroplating parameters, and the local data monitored can be transmitted to the intelligent control system for adjustment of the electroplating parameters in subsequent electroplating work, so as to maintain the uniformity of the electroplated nickel layer. Moreover, the labor cost is reduced, and the stability and efficiency of the electroplating process are improved.

[0038] In another embodiment of the present application, the intelligent control system receives and analyzes the data monitored by the sensors; The connection of the intelligent control system with the pulse power source enables the intelligent control system to control the parameters of the pulse power source and control the current density at 1.5-3 A / dm2, and adjust the current density of the local workpiece in cooperation with the auxiliary electrode.

[0039] It should be noted that the electroplating power source is the core equipment for controlling the current density. By adjusting the current output by the power source, in combination with the effective electroplating area of the plated part (current density = total current / effective electroplating area), the current density can be accurately controlled. The intelligent control system receives the data monitored by the sensors, analyzes the data, controls the parameters of the pulse power source, and controls the current density at 1.5-3 A / dm 2 . By adjusting the voltage or current of the pulse power source, the current density of 1.5-3 A / dm 2 can be achieved, which can not only ensure the quality of the plated layer and prevent overheating and coarse crystallization in the corner and other areas due to too high current density, but also prevent insufficient deposition and plating defects in deep holes and other parts due to too low current density, so as to ensure the flatness and uniformity of the plated layer; at the same time, the deposition efficiency and process stability can be balanced, the deposition speed can be adapted to the production demand, and the production cycle can be shortened due to too low electroplating efficiency or the plating solution ion consumption can be prevented from being too fast due to too high electroplating efficiency.

[0040] The pulse power source is a power source device that can output periodic and transiently changing current or voltage, dynamically adjust pulse parameters (such as width and frequency) to adapt to different regional impedance, and cooperatively control the local current density with the auxiliary electrode. The pulse width directly determines the effective time of the current in a single pulse: the longer the time, the easier it is for the current to penetrate high impedance areas; the shorter the time, the less likely it is for the current to accumulate excessively in low impedance areas. The overall pulse sequence includes high-frequency pulses and low-frequency pulses, which can prevent local overheating and coarse crystallization caused by high current, and ensure that the plated layer is basically flat and bright, while avoiding slow deposition and prolonged production cycle caused by low current.

[0041] High frequency pulse (above 10 kHz) is usually combined with narrow pulse width, so that the pulse period is short, the action time of single pulse is short, and the intelligent control system will control the output of high frequency narrow pulse current of the auxiliary electrode to flow to the low impedance area. When the workpiece surface with low impedance is monitored, the current density is high, the intelligent control system can reduce the current input of the auxiliary electrode to the high current density area by reducing the output proportion of high frequency pulse in the whole pulse sequence.

[0042] Low frequency pulse (below 1 kHz) is usually combined with wide pulse width, so that the pulse period is long, the action time of single pulse is long, and the intelligent control system can control the output of low frequency wide pulse current of the auxiliary electrode to penetrate into the high impedance area. When the deep hole or groove part with high impedance is monitored, the current with short time effect is difficult to break through the high impedance, and the intelligent control system increases the output proportion of low frequency pulse, so that the current output by the auxiliary electrode can easily penetrate into the deep hole or groove part, and balance the current distribution of deep and shallow parts.

[0043] In another embodiment of the present application, the temperature of the plating solution is controlled by a constant temperature control system at 50-55°C, and the fluctuation during electroplating is not more than 1°C based on the set value. The commonly used temperature range for electroplating nickel layer is 20-60°C, which varies depending on the process type. The temperature range of 50-55°C further limits the temperature range. At this temperature, the viscosity of the plating solution is moderate, the diffusion efficiency of nickel ions is high, and the deposition speed is stable; the adsorption deviation of additives can be reduced, which helps to refine the crystal; both low temperature deposition and high temperature can be avoided to prevent the decomposition of additives and the roughness of the plated layer, and the uniform and bright plated layer can be ensured.

[0044] In another embodiment of the present application, the electroplating time is calculated according to the target plated layer thickness and the current density, and the electroplating is completed within the electroplating time. This precise calculation of electroplating time based on target thickness and process parameters is a core control means to ensure the performance of the plated layer. By combining target thickness, current density and other parameters, the required time for electroplating is calculated according to Faraday's law of electrolysis, which can avoid the problems of too thin plated layer caused by insufficient time, resulting in failure of protection effect or function, or too thick plated layer caused by too long time, resulting in increased internal stress and damage to the structure of the plated layer. The electroplating is completed within the set time, which can ensure the precise thickness of the plated layer, and the coordinated control of current, temperature and other parameters can realize the stability and consistency of the density and uniformity of the plated layer, and provide reliable protection for the size accuracy and performance consistency of batch production.

[0045] According to Faraday's law of electrolysis, the calculation formula of the required time for electroplating is as follows: t = (h•ρ•M) / (J•z•F) Wherein, Faraday constant F≈96485 C / mol, t is the plating time, h is the target plating nickel layer thickness, M is the plating layer metal molar mass (nickel is about 58.69 g / mol), J is the current density, z is the metal ion valence (for example, Ni 2+ , z=2).

[0046] The present application is a process for uniformly distributing electroplated nickel layers, which is suitable for electroplating processing of metal parts, electronic components, molds and other products that require uniform nickel layers on the surface, especially for workpieces with complex shapes and high requirements for the uniformity of electroplated nickel layers. The core advantages of this process are as follows: Adaptive electrode system: through customized design of the main electrode and current adjustment of the auxiliary electrode, the current distribution on the surface of the workpiece is effectively balanced, solving the problem of uneven nickel layer in complex parts. Optimized plating solution and stirring: special plating solution formula improves the dispersion and coverage ability of the plating solution, and the composite stirring mode ensures uniform flow of the plating solution and uniform diffusion of nickel ions. Precise parameter control and intelligent adjustment: precise control of parameters such as temperature and current density, combined with real-time monitoring data for intelligent adjustment, to ensure the stability and uniformity of the nickel layer deposition process.

[0047] The present application is further illustrated by specific examples as follows: Example 1 A preparation step of electroplated nickel layer is as follows: (1) According to the shape of the workpiece, a shape-matched main electrode is customized and designed, and the main electrode and auxiliary electrode are subjected to ultrasonic cleaning treatment and pickling activation, and a polyaniline coating is coated on the surface of the main electrode and auxiliary electrode.

[0048] (2) The adaptive adjustable electrode system is used to place the workpiece into the plating solution, and the position angle of the main electrode and auxiliary electrode is adjusted. The plating solution includes 320 g / L nickel sulfate, 55 g / L nickel chloride, 45 g / L boric acid, 0.05 g / L sodium saccharin and 0.03 g / L butynediol.

[0049] (3) The combination of circulating spray and ultrasonic stirring is used for stirring to strengthen the flow of the plating solution. The constant temperature control system is controlled at 54 ℃, and the fluctuation during plating does not exceed 1 ℃ based on the set value. The current density is accurately controlled at 2.8 A / dm 2 . According to Faraday's law of electrolysis, the required time for electroplating is calculated, and the target plating nickel layer thickness of 2.5 mm is achieved after electroplating is completed.

[0050] Example 2 A preparation step of electroplated nickel layer is as follows: (1) The specific steps are the same as in Example 1.

[0051] (2) The workpiece is placed into the plating solution using an adaptive adjustable electrode system, and the position angle of the main electrode and auxiliary electrode is adjusted. The plating solution comprises 300 g / L nickel sulfate, 50 g / L nickel chloride, 40 g / L boric acid, 0.03 g / L sodium saccharin, and 0.02 g / L butynediol.

[0052] (3) The circulation spray and ultrasonic stirring combined stirring mode is used to strengthen the flow of the plating solution. The constant temperature control system is controlled at 52 °C, and the fluctuation during plating does not exceed 1 °C based on the set value. The current density is accurately controlled at 2.1 A / dm 2 by the intelligent control system. The required time for electroplating is calculated according to the Faraday's law of electrolysis, and the target electroplated nickel layer thickness of 2.5 mm is reached.

[0053] Example 3 The preparation steps of the electroplated nickel layer are as follows: (1) The specific steps are the same as those in Example 1.

[0054] (2) The workpiece is placed into the plating solution using an adaptive adjustable electrode system, and the position angle of the main electrode and auxiliary electrode is adjusted. The plating solution comprises 280 g / L nickel sulfate, 45 g / L nickel chloride, 35 g / L boric acid, 0.02 g / L sodium saccharin, and 0.01 g / L butynediol.

[0055] (3) The circulation spray and ultrasonic stirring combined stirring mode is used to strengthen the flow of the plating solution. The constant temperature control system is controlled at 50 °C, and the fluctuation during plating does not exceed 1 °C based on the set value. The current density is accurately controlled at 1.5 A / dm 2 by the intelligent control system. The required time for electroplating is calculated according to the Faraday's law of electrolysis, and the target electroplated nickel layer thickness of 2.5 mm is reached.

[0056] Example 4 The preparation steps of the electroplated nickel layer are as follows: (1) The specific steps are the same as those in Example 1.

[0057] (2) The workpiece is placed into the plating solution using an adaptive adjustable electrode system, and the position angle of the main electrode and auxiliary electrode is adjusted. The plating solution comprises 295 g / L nickel sulfate, 48 g / L nickel chloride, 38 g / L boric acid, 0.03 g / L sodium saccharin, and 0.02 g / L butynediol.

[0058] (3) The circulation spray and ultrasonic stirring combined stirring mode is used to strengthen the flow of the plating solution. The constant temperature control system is controlled at 52 °C, and the fluctuation during plating does not exceed 1 °C based on the set value. The current density is accurately controlled at 2.2 A / dm 2According to Faraday's law of electrolysis, the time required for electroplating is calculated, and the electroplating is completed to achieve the target electroplated nickel layer thickness of 2.5 mm.

[0059] Example 5 The preparation steps of the electroplated nickel layer are as follows: (1) The specific steps are the same as those in Example 1.

[0060] (2) The workpiece is placed in the plating solution using the adaptive adjustable electrode system, and the position angle of the main electrode and the auxiliary electrode is adjusted. The plating solution includes 310 g / L nickel sulfate, 53 g / L nickel chloride, 43 g / L boric acid, 0.04 g / L sodium saccharin, and 0.02 g / L butynediol.

[0061] (3) The circulation spray and ultrasonic stirring combination stirring mode is used to strengthen the flow of the plating solution. The constant temperature control system is controlled at 53°C, and the fluctuation during electroplating does not exceed 1°C based on the set value. The current density is accurately controlled at 2.5 A / dm 2 According to Faraday's law of electrolysis, the time required for electroplating is calculated, and the electroplating is completed to achieve the target electroplated nickel layer thickness of 2.5 mm.

[0062] Performance test Sample 1 and sample 2 are prepared according to Example 1; sample 3 and sample 4 are prepared according to Example 2; sample 5 and sample 6 are prepared according to Example 3; sample 7 and sample 8 are prepared according to Example 4; sample 9 and sample 10 are prepared according to Example 5.

[0063] Please refer to Figure 2 The electroplated nickel layer thickness of the three points P1, P2, and P3 of the prepared samples 1-10 is measured, and the uniformity of the electroplated nickel layer prepared under the process of the application is tested, and the thickness unit is mm.

[0064] The test data are as follows: From the various embodiments and corresponding sample test data, the 5 groups of embodiments (a total of 10 samples) are at the target electroplated nickel layer thickness of 2.5mm, the thickness values of P1, P2 and P3 points fluctuate around 2.5mm, the thickness difference of parallel samples of the same embodiment is also small, which shows that the electroplated nickel process can stably realize the thickness of each test point of the workpiece to approach the target value under different electroplating parameter settings (differences in plating solution composition, temperature, current density, etc.) or under the same conditions, the deviation is small, and the process repeatability and stability are good. In terms of a single sample, the thickness difference between different test points is extremely small, the maximum difference between two points is not more than 0.02mm, for example, sample 4: the electroplated nickel layer thickness of P2 point is 2.51mm, and the electroplated nickel layer thickness of P3 point is 2.49mm. It shows that the electroplated nickel layer prepared by the process exhibits excellent uniformity of electroplated nickel layer thickness at different points of the workpiece, the addition of walking agent and leveling agent, self-adaptive electrode system, combined stirring, and clear electroplating parameters effectively guarantee the uniform deposition of the plating layer thickness.

[0065] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An electroplating process for uniformly distributing an electroplated nickel layer, characterized in that, The method comprises the following steps: S1: using the adaptive electrode system, placing the workpiece into the plating solution, the plating solution comprising nickel sulfate, nickel chloride, boric acid, sodium saccharin and butynediol; S2: controlling the temperature, current density and plating time of the plating solution within a predetermined range to achieve the target plating layer thickness.

2. The process of claim 1, wherein: The adaptive electrode system comprises a main electrode and an auxiliary electrode. The profile of the main electrode on the side facing the workpiece matches the profile of the workpiece on the side facing the main electrode, so that the preset and consistent distance is maintained between different positions on the main electrode and the corresponding parts of the workpiece. The auxiliary electrode is installed near the deep hole or recess part of the workpiece and adjusts the current output.

3. The process of claim 2, wherein Before the main electrode and the auxiliary electrode of the adaptive electrode system are placed into the plating solution, the surface is cleaned and then coated with a polyaniline coating.

4. The process of claim 2, wherein, A plurality of sensors are installed in the plating tank to monitor the nickel layer thickness, plating solution concentration and plating solution temperature of different parts of the workpiece in real time, and the monitored data is transmitted to the intelligent control system.

5. The process of claim 4, wherein, The intelligent control system receives and analyzes the monitored data. The intelligent control system is connected with the pulse power supply, so that the intelligent control system regulates and controls the parameters of the pulse power supply, and the current density is controlled at 1.5-3A / dm 2 , and cooperates with the auxiliary electrode to adjust the current density of the local workpiece.

6. The process of claim 5, wherein, The plating solution temperature is controlled by a constant temperature control system to be within 50-55℃, and the plating solution temperature fluctuates by no more than 1℃ based on the set value during plating.

7. The process according to any one of claims 1 to 6, characterized in that: The plating solution comprises the following components at the following concentrations: 280-320g / L nickel sulfate, 45-55g / L nickel chloride, 35-45g / L boric acid, 0.02-0.05g / L sodium saccharin and 0.01-0.03g / L butynediol.

8. The process according to any one of claims 1 to 6, characterized in that: The plating solution is stirred by a combination of circulating injection and ultrasonic stirring. The circulating injection stirring method uses multiple direction-adjustable nozzles to make the plating solution in the plating tank repeatedly circulate and spray onto the surface of the workpiece.

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