Continuous High-Phosphorus Electroless Nickel Plating Method

Abstract

The present application provides a method for continuous electroless nickel plating with high phosphorus content. First, an electroless plating solution containing nickel salt, complexing agent, and additive is prepared. Then, a first reducing agent and a second reducing agent are added to the plating solution according to a mass ratio of (3 - 5):(1 - 2). The first reducing agent is an organic compound of phosphoric ester and / or phosphite ester, and the second reducing agent is one or more of lithium aluminum hydride, sodium borohydride, propionic acid, or succinic acid. The pH value of the plating solution needs to be adjusted to 4.5 - 5.5, and the temperature of the plating solution is controlled at 80 - 90 °C, and then continuous plating operation is carried out. The first reducing agent can stably release active phosphorus atoms at a relatively low temperature, providing a rich phosphorus source for the coating and ensuring that the coating reaches a high phosphorus content. The second reducing agent can effectively promote the reduction and deposition process of nickel ions and accelerate the deposition rate. The two reducing agent components cooperate with each other, making the plating solution maintain a high degree of stability, effectively inhibiting the fluctuation of the plating solution components, and significantly improving the consistency and stability of the coating quality.

Description

Technical Field

[0001] This application belongs to the technical field of electroless nickel plating, and more specifically, relates to a continuous high-phosphorus electroless nickel plating method. Background Art

[0002] The continuous high-phosphorus electroless nickel plating process is a process for depositing a high-phosphorus electroless nickel layer on the surface of a substrate, which can endow the substrate with excellent corrosion resistance, wear resistance and relatively high hardness. This process is applicable to a variety of substrates, such as aluminum alloys, stainless steels, alloy carbon steels, copper alloys, etc., and is widely used in industries such as the electronics industry and petroleum, as well as fields with high requirements for corrosion resistance.

[0003] In the traditional continuous high-phosphorus electroless nickel plating process, sodium hypophosphite is used as the main reducing agent. During plating, sodium hypophosphite in the plating solution promotes the reduction and deposition of nickel ions on the surface of the workpiece by virtue of its own reducibility, while releasing phosphorus atoms, thereby forming a high-phosphorus electroless nickel coating. Although this method can achieve electroless nickel plating, the stability of the plating solution is poor. With the extension of the plating time, the continuous consumption of sodium hypophosphite will cause large changes in key parameters such as the pH value and redox potential of the plating solution, resulting in unstable reaction activities of each component in the plating solution. Moreover, the reaction process of sodium hypophosphite is difficult to accurately control, resulting in a large fluctuation range of the phosphorus content in the coating, which is difficult to meet the requirements of high-end products with strict requirements for the phosphorus content of the coating. In terms of the coating performance, the hardness and corrosion resistance of the coating obtained in this way have limited improvement effects and cannot adapt to some special application environments. For example, in working conditions with high temperature, high humidity and corrosive media, problems such as coating corrosion and peeling are likely to occur, affecting the service life of the product. Summary of the Invention

[0004] The purpose of the embodiments of this application is to provide a continuous high-phosphorus electroless nickel plating method to solve the technical problem of insufficient stability of the plating solution in the prior art.

[0005] To achieve the above purpose, the technical solution adopted in this application is: to provide a continuous high-phosphorus electroless nickel plating method, including the following steps:

[0006] Prepare an electroless plating solution containing nickel salt, complexing agent and additive;

[0007] Add a first reducing agent and a second reducing agent to the plating solution according to a mass ratio of (3 - 5):(1 - 2), wherein the first reducing agent is a phosphoric ester and / or phosphite organic compound, and the second reducing agent is one or more of lithium aluminum hydride, sodium borohydride, propionic acid or succinic acid;

[0008] Adjust the pH value of the plating solution to 4.5 - 5.5;

[0009] Control the temperature of the plating solution at 80 - 90 °C;

[0010] Place the substrate in the plating solution for continuous plating operation.

[0011] In one embodiment, the first reducing agent is trimethyl phosphite or triethyl phosphite.

[0012] In one embodiment, the plating solution is configured with components in the following mass ratios:

[0013] Nickel salt 45% - 60%;

[0014] First reducing agent 15% - 25%;

[0015] Second reducing agent 5% - 10%;

[0016] Complexing agent 12% - 25%;

[0017] Additive 3% - 5%.

[0018] In one embodiment, the additive is one or more of a buffer, a stabilizer, a wetting agent, a surfactant, and a brightening agent.

[0019] In one embodiment, during the process of placing the substrate in the plating solution for continuous plating operation, stir the plating solution by ultrasonic waves.

[0020] In one embodiment, adjust the pH value of the plating solution to 4.5 - 5.5, including:

[0021] Real - time monitor the pH value of the plating solution through a pH sensor, and convert the obtained value into an electrical signal and transmit it to the control system;

[0022] When the pH value of the plating solution deviates from 4.5 - 5.5, the control system regulates the automatic dosing machine and the automatic titration device to accurately add a pH regulator to the plating solution.

[0023] In one embodiment, the pH regulator added to the plating solution is ammonia water or potassium carbonate.

[0024] In one embodiment, control the temperature of the plating solution at 80 - 90 °C, including:

[0025] Real - time monitor the temperature of the plating solution through a temperature sensor, and convert the obtained value into an electrical signal;

[0026] Transmit the electrical signal to the conditioning module for amplification and filtering processing and then transmit it to the control system;

[0027] When the temperature of the plating solution deviates from the range of 80 - 90 °C, the control system regulates the heating or cooling device to heat up or cool down the plating solution.

[0028] The beneficial effects of the continuous high-phosphorus electroless nickel plating method provided by this application are as follows: Compared with the prior art, this application adopts a combination form of two reducing agents, namely a first reducing agent and a second reducing agent. The first reducing agent is a phosphoric acid ester and / or phosphite organic compound. The first reducing agent can stably release active phosphorus atoms at a relatively low temperature, providing a rich phosphorus source for the coating and ensuring that the coating reaches a relatively high phosphorus content. The second reducing agent is one or more of lithium aluminum hydride, sodium borohydride, propionic acid, or succinic acid. The second reducing agent can effectively promote the reduction and deposition process of nickel ions and accelerate the deposition rate. The two reducing agent components cooperate with each other, enabling the plating solution to maintain a high degree of stability during continuous plating, effectively suppressing fluctuations in the components of the plating solution, and significantly improving the consistency and stability of the coating quality. Description of the Drawings

[0029] In order to more clearly illustrate the technical solutions in the embodiments of this application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0030] Figure 1 It is a flowchart of the continuous high-phosphorus electroless nickel plating method provided by the embodiments of this application. Detailed Embodiments

[0031] In order to make the technical problems, technical solutions, and beneficial effects to be solved by this application more clearly understood, the following further elaborates on this application in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0032] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0033] It should be understood that the orientation or positional relationship indicated by the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0034] In addition, the terms "first" and "second" are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality" means two or more, unless otherwise specifically defined.

[0035] Please refer to Figure 1 , and now the continuous high-phosphorus electroless nickel plating method provided by the embodiments of this application will be described. Herein, in this specification, "high phosphorus" means that the phosphorus content in the nickel plating layer is 9-14% (weight ratio). This kind of high-phosphorus content plating layer has better corrosion resistance and lower hardness, and is suitable for application occasions that require good corrosion resistance. The continuous high-phosphorus electroless nickel plating method includes the following steps:

[0036] Prepare an electroless plating solution containing nickel salt, complexing agent, and additive;

[0037] Add a first reducing agent and a second reducing agent to the plating solution according to a mass ratio of (3-5):(1-2), wherein the first reducing agent is a phosphoric acid ester and / or phosphite organic compound, and the second reducing agent is one or more of lithium aluminum hydride, sodium borohydride, propionic acid, or succinic acid;

[0038] Adjust the pH value of the plating solution to 4.5-5.5;

[0039] Control the temperature of the plating solution at 80-90 °C;

[0040] Place the substrate in the plating solution for continuous plating operation.

[0041] Specifically, the continuous high-phosphorus electroless nickel plating process requires specialized equipment such as plating baths, heaters, circulation pumps, filters, etc. to ensure the stability and uniformity of the plating solution. First, an electroless plating solution containing components such as nickel salts, complexing agents, and additives is prepared according to the conventional process. The nickel salt can be one or more of nickel sulfate, nickel chloride, nickel hypophosphite, nickel carbonate, and nickel acetate. The complexing agent can be one or more of glycolic acid, citric acid, lactic acid, malic acid, and succinic acid. The additives can be stabilizers, buffers, surfactants, or wetting agents, etc. Each component such as nickel salt, complexing agent, and additive is mixed and added to the plating bath in a predetermined ratio. Two combinations of reducing agents, namely the first reducing agent and the second reducing agent, are added to the plating solution in a mass ratio of (3 - 5):(1 - 2). The first reducing agent is an organic phosphate compound, an organic phosphite compound, or a mixture of both. For example, the first reducing agent can be trimethyl phosphite or triethyl phosphite. Both organic phosphate compounds and organic phosphite compounds have a certain degree of reducibility and can reduce nickel ions to nickel in the electroless nickel plating process, while releasing phosphorus atoms as a phosphorus source. The second reducing agent is one or more of lithium aluminum hydride, sodium borohydride, propionic acid, and succinic acid. The second reducing agent can effectively promote the reduction and deposition process of nickel ions, accelerate the deposition rate, and thus rapidly deposit a nickel-phosphorus alloy coating on the substrate surface. Then, the pH value of the plating solution needs to be adjusted to 4.5 - 5.5 through a pH regulator. For example, the initial pH value of the plating solution is detected by a pH sensor. If the pH value deviates from the range of 4.5 - 5.5, an acidic or alkaline pH regulator needs to be added to the plating solution for adjustment. Before starting the plating operation, the temperature of the plating solution also needs to be heated to 80 - 90 °C. For example, the plating solution can be heated to 80 - 90 °C by a heating rod installed in the plating bath. During the plating process, substrates such as aluminum alloys, stainless steels, carbon and alloy steels, copper alloys, and non-conductive materials are placed in the plating solution for continuous plating operations.

[0042] Throughout the entire process, the pH value of the plating solution always needs to be controlled within the range of 4.5 - 5.5, and the temperature of the plating solution needs to be controlled within the range of 80 - 90 °C to ensure the quality and performance of the coating. In addition, as the plating process progresses, the concentrations of core components such as nickel ions, reducing agents, and complexing agents will gradually decrease. To ensure the stability of the coating quality and performance, it is necessary to monitor the concentrations of core components such as nickel ions, reducing agents, and complexing agents in the plating solution in real time; when the concentrations of core components such as nickel ions, reducing agents, and complexing agents do not meet the set values, the corresponding components need to be added to the plating solution in a timely manner.

[0043] Compared with the prior art, the present application adopts a combination form of two reducing agents, namely a first reducing agent and a second reducing agent. The first reducing agent is a phosphoric ester and / or phosphite organic compound. The first reducing agent can stably release active phosphorus atoms at a relatively low temperature, providing a rich phosphorus source for the coating and ensuring a high phosphorus content in the coating. The second reducing agent is one or more of lithium aluminum hydride, sodium borohydride, propionic acid or succinic acid. The second reducing agent can effectively promote the reduction and deposition process of nickel ions and accelerate the deposition rate. The two reducing agent components cooperate with each other, enabling the plating solution to maintain a high degree of stability during continuous plating, effectively suppressing fluctuations in the plating solution components, and significantly improving the consistency and stability of the coating quality.

[0044] In one embodiment, the first reducing agent is trimethyl phosphite or triethyl phosphite. Trimethyl phosphite and triethyl phosphite have strong reducibility and can effectively provide electrons in the continuous electroless nickel plating reaction with high phosphorus content, promoting the reduction of nickel ions. During the reaction, trimethyl phosphite and triethyl phosphite can chelate with nickel ions, avoiding unnecessary side reactions, thereby improving the accuracy and efficiency of the reaction, ensuring uniform deposition of nickel, and preventing the generation of impurities or affecting the coating quality. In addition, trimethyl phosphite and triethyl phosphite are relatively stable under normal temperature and pressure and can maintain a long service life in the continuous electroless nickel plating reaction with high phosphorus content.

[0045] In one embodiment, the plating solution is prepared according to the following mass ratio components: nickel salt 45%-60%, first reducing agent 15%-25%, second reducing agent 5%-10%, complexing agent 12%-25%, additive 3%-5%. Among them, the nickel salt, which occupies a relatively large proportion, serves as the main nickel source, ensuring the main component of nickel in the coating. The first reducing agent serves as the main reducing agent, reducing nickel ions to metallic nickel during the electroless nickel plating process. The second reducing agent, as another reducing agent, acts together with the first reducing agent to jointly promote the reduction of nickel ions. The complexing agent is used to stabilize nickel ions in the plating solution, prevent their hydrolysis or precipitation, and also helps to regulate the composition and structure of the coating. The additive can be a surfactant, stabilizer, brightener, buffer, etc., and is used to improve the appearance, uniformity or other properties of the coating. Since the content of the first reducing agent as the phosphorus source is relatively large (15%-25%), the coating prepared with the plating solution configured in this way has a high phosphorus content, excellent properties such as corrosion resistance and wear resistance, the electroless nickel plating process is controllable, and it helps to obtain a stable and predictable coating quality and performance.

[0046] In one embodiment, the additive is one or more of a buffer, a stabilizer, a wetting agent, a surfactant, and a brightening agent. Among them, the buffer and the stabilizer help to improve the uniformity of the coating, the brightening agent helps to improve the appearance of the coating, and the surfactant and the wetting agent help to improve the wettability of the plating solution, making the plating solution more easily wet the surface of the substrate, thereby improving the adhesion and uniformity of the coating. In addition, the surfactant can also improve the fluidity of the plating solution, helping the plating solution to be more evenly distributed on the surface of the substrate, further improving the uniformity and density of the coating.

[0047] In one embodiment, during the continuous plating operation of placing the substrate in the plating solution, the plating solution is stirred by ultrasonic waves. Specifically, during the plating process, compared with the traditional mechanical stirring method, the ultrasonic stirring method promotes the uniform dispersion of the reducing agent and other components in the plating solution through the cavitation effect of ultrasonic waves, which helps to improve the uniformity of the coating.

[0048] In one embodiment, adjusting the pH value of the plating solution to 4.5 - 5.5 includes:

[0049] The pH value of the plating solution is monitored in real time by a pH sensor, and the obtained value is converted into an electrical signal and transmitted to the control system;

[0050] When the pH value of the plating solution deviates from 4.5 - 5.5, the control system controls the automatic dosing machine and the automatic titration device to accurately add a pH regulator to the plating solution.

[0051] During the production process of continuous high-phosphorus electroless nickel plating, a pH sensor can be installed in the plating tank, and the pH sensor is connected to the control system. In addition, an automatic dosing machine for adding a pH regulator and other components to the plating tank needs to be installed beside the plating tank. The pH sensor monitors the pH value of the electroless plating solution in the plating tank in real time, and converts the obtained value into an electrical signal and transmits it to the control system. The control system compares the pH value data obtained in real time with the preset value. When the pH value of the plating solution deviates from the range of 4.5 - 5.5, the control system issues an instruction to add a pH regulator to the plating solution by controlling the automatic dosing machine, and accurately controls the addition amount of the pH regulator through the automatic titration device.

[0052] In one embodiment, the pH regulator added to the plating solution is ammonia water or potassium carbonate. Among them, ammonia water has buffering ability and can effectively control the acidity and alkalinity of the plating solution, preventing the nickel ions from hydrolyzing or the stability of the plating solution from decreasing due to too high or too low acidity and alkalinity. And the waste water generated by adjusting the pH value with potassium carbonate has less pollution to the environment and is more environmentally friendly.

[0053] In one embodiment, controlling the temperature of the plating solution at 80 - 90 °C includes:

[0054] The temperature of the plating solution is monitored in real time by a temperature sensor, and the obtained value is converted into an electrical signal;

[0055] The electrical signal is transmitted to a conditioning module for amplification and filtering, and then transmitted to a control system;

[0056] When the temperature of the plating solution deviates from the range of 80 - 90 °C, the control system regulates the heating or cooling device to heat up or cool down the plating solution.

[0057] During the production process of continuous high-phosphorus electroless nickel plating, a temperature sensor, a heating device, and a cooling device can be installed in the plating bath. The temperature sensor, the heating device, and the cooling device are all connected to the control system. A conditioning module is also connected between the temperature sensor and the control system. The temperature sensor monitors the temperature of the plating solution in real time, converts the obtained value into an electrical signal, and then transmits the electrical signal to the conditioning module. The conditioning module amplifies and filters the obtained electrical signal and then transmits it to the control system. The control system compares the obtained real-time temperature data with a preset value. When the temperature of the plating solution deviates from the range of 80 - 90, the control system regulates the heating or cooling device to heat up or cool down the plating solution, so that the temperature of the plating solution is maintained within the range of 80 - 90 °C.

[0058] Example 1

[0059] A continuous high-phosphorus electroless nickel plating method includes:

[0060] First, nickel sulfate, citric acid, and ammonium chloride are added to the plating bath according to a mass ratio of: nickel sulfate 50%, trimethyl phosphite 18%, sodium borohydride 5%, citric acid 22%, ammonium chloride 5%;

[0061] Trimethyl phosphite and sodium borohydride are added to the plating bath to prepare a predetermined amount of plating solution;

[0062] The pH value of the plating solution is measured by a pH sensor, and the pH value of the plating solution is adjusted to 5 by adding a pH regulator;

[0063] The temperature of the plating solution is heated to 80 - 9° C by a heating device;

[0064] The substrate is placed in the plating solution for continuous plating operation, and the temperature of the plating solution is continuously monitored by a temperature sensor. When the temperature of the plating solution deviates from 80 - 90 °C, the plating solution is heated up or cooled down by a heating device or a cooling device to keep the temperature of the plating solution at 80 - 90 °C; and the pH value of the plating solution is continuously monitored by a pH sensor. When the pH value of the plating solution deviates from the range of 4.5 - 5.5, a pH regulator is added to the plating solution to keep the pH value of the plating solution within the range of 4.5 - 5.5.

[0065] Example 2

[0066] A continuous high-phosphorus electroless nickel plating method, comprising:

[0067] First, add nickel sulfate, citric acid, and ammonium chloride to the plating bath according to the mass ratio of: nickel sulfate 46%, triethyl phosphite 22%, lithium aluminum hydride 8%, citric acid 19%, ammonium chloride 5%;

[0068] Add triethyl phosphite and lithium aluminum hydride to the plating bath to prepare a predetermined amount of plating solution;

[0069] Measure the pH value of the plating solution through a pH sensor, and adjust the pH value of the plating solution to 5 by adding a pH regulator;

[0070] Heat the temperature of the plating solution to 80 - 90 °C through a heating device;

[0071] Place the substrate in the plating solution for continuous plating operation, and continuously monitor the temperature of the plating solution through a temperature sensor. When the temperature of the plating solution deviates from 80 - 90 °C, heat or cool the plating solution through a heating device or a cooling device to keep the temperature of the plating solution at 80 - 90 °C; and continuously monitor the pH value of the plating solution through a pH sensor. When the pH value of the plating solution deviates from the range of 4.5 - 5.5, add a pH regulator to the plating solution to keep the pH value of the plating solution within the range of 4.5 - 5.5.

[0072] Example 3

[0073] A continuous high-phosphorus electroless nickel plating method, comprising:

[0074] First, add nickel sulfate, citric acid, and ammonium chloride to the plating bath according to the mass ratio of: nickel sulfate 53%, trimethyl phosphite 16%, lithium aluminum hydride 10%, citric acid 17%, ammonium chloride 4%;

[0075] Add trimethyl phosphite and lithium aluminum hydride to the plating bath to prepare a predetermined amount of plating solution;

[0076] Measure the pH value of the plating solution through a pH sensor, and adjust the pH value of the plating solution to 5 by adding a pH regulator;

[0077] Heat the temperature of the plating solution to 80 - 90 °C through a heating device;

[0078] Place the substrate in the plating solution for continuous plating operation, and continuously monitor the temperature of the plating solution through a temperature sensor. When the temperature of the plating solution deviates from 80 - 90 °C, heat or cool the plating solution through a heating device or a cooling device to keep the temperature of the plating solution within 80 - 90 °C. Also, continuously monitor the pH value of the plating solution through a pH sensor. When the pH value of the plating solution deviates from the range of 4.5 - 5.5, add a pH regulator to the plating solution to keep the pH value of the plating solution within the range of 4.5 - 5.5.

[0079] Example 4

[0080] A method for continuous high-phosphorus electroless nickel plating, comprising:

[0081] Add nickel sulfate, citric acid, and ammonium chloride to the plating bath in a mass ratio of: nickel sulfate 50%, triphenyl phosphite 18%, sodium borohydride 5%, citric acid 22%, ammonium chloride 5%;

[0082] Add triphenyl phosphite and sodium borohydride to the plating bath to prepare a predetermined amount of plating solution;

[0083] Measure the pH value of the plating solution through a pH sensor, and adjust the pH value of the plating solution to 5 by adding a pH regulator;

[0084] Heat the plating solution to 80 - 90 °C through a heating device;

[0085] Place the substrate in the plating solution for continuous plating operation, and continuously monitor the temperature of the plating solution through a temperature sensor. When the temperature of the plating solution deviates from 80 - 90 °C, heat or cool the plating solution through a heating device or a cooling device to keep the temperature of the plating solution within 80 - 90 °C. Also, continuously monitor the pH value of the plating solution through a pH sensor. When the pH value of the plating solution deviates from the range of 4.5 - 5.5, add a pH regulator to the plating solution to keep the pH value of the plating solution within the range of 4.5 - 5.5.

[0086] Example 5

[0087] A method for continuous high-phosphorus electroless nickel plating, comprising:

[0088] Add nickel sulfate, citric acid, and ammonium chloride to the plating bath in a mass ratio of: nickel sulfate 50%, trimethyl phosphite 18%, propionic acid 5%, citric acid 22%, ammonium chloride 5%;

[0089] Add trimethyl phosphite and propionic acid to the plating bath to prepare a predetermined amount of plating solution;

[0090] Measure the pH value of the plating solution through a pH sensor, and adjust the pH value of the plating solution to 5 by adding a pH regulator;

[0091] Heat the temperature of the plating solution to 80 - 90 °C through a heating device;

[0092] Place the substrate in the plating solution for continuous plating operation, and continuously monitor the temperature of the plating solution through a temperature sensor. When the temperature of the plating solution deviates from 80 - 90 °C, heat or cool the plating solution through a heating device or a cooling device to keep the temperature of the plating solution at 80 - 90 °C; and continuously monitor the pH value of the plating solution through a pH sensor. When the pH value of the plating solution deviates from the range of 4.5 - 5.5, add a pH regulator to the plating solution to keep the pH value of the plating solution within the range of 4.5 - 5.5.

[0093] Plating is carried out on the same substrate according to the above five embodiments, and the phosphorus content of the obtained coatings is as follows:

[0094] It is found from the above embodiments that in Example 4, since triphenyl phosphite is used as the first reducing agent, and the reducibility of triphenyl phosphite is inferior to that of trimethyl phosphite or triethyl phosphite, although the phosphorus content of the coating obtained in Example 4 is also relatively high, the stability of the plating solution is worse than that of the other several embodiments. After continuous plating for 80 hours, the plating solution becomes turbid. In Example 5, propionic acid is used as the second reducing agent, and the deposition rate of the obtained coating decreases, resulting in an extension of the overall plating time. However, the phosphorus content of the coating is still higher than that of the coatings prepared by the prior art, so the corrosion resistance of the coating is still better than that of the prior art.

[0095] The above are only the preferred embodiments of the present application and are 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 within the protection scope of the present application.

Claims

1. A continuous high-phosphorus electroless nickel plating method, characterized in that, It includes the following steps: Configure an electroless plating solution containing nickel salt, complexing agent, and additive. The plating solution is configured according to the following mass ratio components: Nickel salt: 45% - 60%; First reducing agent: 15% - 25%; Second reducing agent: 5% - 10%; Complexing agent: 12% - 25%; Additive: 3% - 5%; Add the first reducing agent and the second reducing agent to the plating solution according to the mass ratio of (3 - 5):(1 - 2), where the first reducing agent is trimethyl phosphite or triethyl phosphite, and the second reducing agent is one or more of lithium aluminum hydride, sodium borohydride, propionic acid, or succinic acid; Adjust the pH value of the plating solution to 4.5 - 5.5; Control the temperature of the plating solution at 80 - 90 °C; Place the substrate in the plating solution for continuous plating operation.

2. The continuous high-phosphorus electroless nickel plating method according to claim 1, wherein The additive is one or more of a buffer, a stabilizer, a wetting agent, a surfactant, and a brightening agent.

3. The continuous high-phosphorus electroless nickel plating method according to claim 1 or 2, characterized in that, During the process of placing the substrate in the plating solution for continuous plating operation, stir the plating solution by ultrasonic waves.

4. The continuous high-phosphorus electroless nickel plating method according to claim 1 or 2, characterized in that, Adjusting the pH value of the plating solution to 4.5 - 5.5 includes: Real - time monitor the pH value of the plating solution through a pH sensor, and convert the obtained value into an electrical signal and transmit it to the control system; When the pH value of the plating solution deviates from 4.5 - 5.5, the control system regulates the automatic dosing machine and the automatic titration device to accurately add a pH regulator to the plating solution.

5. The continuous high-phosphorus electroless nickel plating method according to claim 4, characterized in that, The pH regulator added to the plating solution is ammonia water or potassium carbonate.

6. The continuous high-phosphorus electroless nickel plating method according to claim 1 or 2, characterized in that, Controlling the temperature of the plating solution at 80 - 90 °C includes: Real - time monitor the temperature of the plating solution through a temperature sensor, and convert the obtained value into an electrical signal; Transmit the electrical signal to the conditioning module for amplification and filtering processing and then transmit it to the control system; When the temperature of the plating solution deviates from the range of 80 - 90 °C, the control system regulates the heating or cooling device to heat up or cool down the plating solution.

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