Sulfite cyanide-free electrogilding solution maintenance method and intelligent management and control equipment

Abstract

The invention relates to the technical field of maintenance of cyanide-free electrogilding liquid, in particular to a sulfite cyanide-free electrogilding liquid maintenance method and intelligent management and control equipment. The maintenance method comprises the following steps: mixing a first sulfite solution, a first auxiliary complexing agent and a chloroaurate solution to obtain a gold supplement; mixing a second sulfite solution with a second auxiliary complexing agent to obtain a sulfite supplement; sampling the sulfite cyanide-free electrogilding solution to obtain a cyanide-free electrogilding solution to be detected; carrying out X-ray fluorescence analysis on the to-be-detected cyanide-free gold electroplating solution to obtain a first mass content; performing potentiometric titration analysis on the cyanide-free electrogilding solution by using hydrochloric acid and sodium thiosulfate standard solutions to obtain a second mass content; determining a first addition amount and a second addition amount; and according to the first adding amount and the second adding amount, the supplement is added into the sulfite cyanide-free electrogilding solution, and maintenance is completed. According to the maintenance method, the stability of the mass content of sulfite and gold in the sulfite cyanide-free gold plating solution can be improved.

Description

Technical Field

[0001] This application relates to the field of maintenance technology for cyanide-free electroplating gold solutions, and in particular to a maintenance method and intelligent control equipment for sulfite-based cyanide-free electroplating gold solutions. Background Technology

[0002] The existing mature maintenance method for sulfite-based cyanide-free gold plating solutions is to periodically analyze the content of major components such as sulfite and gold using chemical titration or instrumental analysis, and then directly replenish the consumption of sulfite-based cyanide-free gold plating solution based on the analysis results, thereby controlling the component content of the sulfite-based cyanide-free gold plating solution within the process range.

[0003] However, current maintenance methods for cyanide-free gold plating solutions cause significant fluctuations in the sulfite and gold content within the solution. The main reasons are as follows: (1) Chemical titration analysis or instrumental analysis requires a certain amount of time for manual sampling, sample preparation and analysis, which cannot be carried out in real time and cannot achieve digital control of the production line; (2) Sulfite cannot be added directly as a solid, but needs to be dissolved into an aqueous solution before it can be added, so as to avoid the sulfite not being fully dissolved. This method of addition requires sufficient liquid surface space in the plating tank. Generally, it is carried out by one analysis + multiple additions, which makes it difficult to add sulfite very accurately and in a timely manner; (3) Gold content is generally supplemented by chloroaurate or other gold-containing salts. During the addition process, these gold-containing salts need to undergo a complexation reaction with sulfite. Therefore, the addition of gold-containing salts will have a significant impact on the temperature and pH of the cyanide-free gold plating solution. Moreover, the addition process has certain requirements on pH and plating solution temperature. It is impossible to replenish in time during production. Production needs to be stopped, or after adding gold-containing salts, the temperature and pH of the cyanide-free gold plating solution need to be adjusted to the process range before production can be resumed. Therefore, in order to reduce the impact of maintenance methods on production, gold-containing salts can only be added in a concentrated period of time.

[0004] Based on the large fluctuations in the mass content of the above-mentioned maintenance methods, the current control methods in the industry have obvious disadvantages: (1) Replenishing the mass content of gold in the cyanide-free gold plating solution with gold salts requires high requirements for the state control of the cyanide-free gold plating solution and the operation level of the operators. It is easy for the gold salt complexing to be insufficient and precipitate out, which not only affects the effect of replenishing the mass content of gold in the cyanide-free gold plating solution with gold salts, but also makes the cyanide-free gold plating solution in the entire electroplating tank turbid, affecting the electroplating performance of the cyanide-free gold plating solution, and also causing the waste of precious metal resources in the cyanide-free gold plating solution. (2) The mass content of sulfite in the main complexing agent and gold in the main gold salt plays a key role in the control of the gold plating process parameters of the cyanide-free gold plating solution and the quality of the gold plating layer. If the mass content of sulfite and gold fluctuates greatly, the operators cannot accurately control the electroplating process parameters, making it difficult to accurately control the thickness of the plating layer, and may even cause poor appearance and scorching of the plating layer. Summary of the Invention

[0005] This application provides a maintenance method and intelligent control equipment for sulfite-based cyanide-free gold plating solution to solve the following technical problem: how to improve the stability of the mass content of sulfite and gold in the sulfite-based cyanide-free gold plating solution during the maintenance process.

[0006] In a first aspect, embodiments of this application provide a method for maintaining a sulfite-based cyanide-free gold plating solution, the method comprising: The first sulfite solution, the first auxiliary complexing agent, and the chloroaurate solution are mixed to obtain the gold supplement; The second sulfite solution and the second auxiliary complexing agent are mixed to obtain a sulfite supplement; A sample of the cyanide-free gold plating solution in the electroplating tank was taken to obtain the cyanide-free gold plating solution to be tested. The first mass content of gold was obtained by X-ray fluorescence analysis of the cyanide-free electroplating gold solution to be tested. The cyanide-free electroplating gold solution to be tested after X-ray fluorescence analysis was subjected to potentiometric titration analysis using hydrochloric acid and sodium thiosulfate standard solutions to obtain the second mass content of sulfite. The first amount of gold supplement and the second amount of sulfite supplement are determined based on the first mass content of gold and the second mass content of sulfite. The gold supplement and the sulfite supplement are added to the sulfite-free cyanide electroplating gold solution according to the first addition amount and the second addition amount, respectively, to complete the maintenance of the sulfite-free cyanide electroplating gold solution.

[0007] Optionally, the gold supplement includes a first gold component, a first sulfite component, and a first stabilizer component; the mass m1 of the first gold component and the volume V1 of the gold supplement satisfy: m1:V1 = (40 to 50):1, the mass m2 of the first sulfite component and the volume V1 of the gold supplement satisfy: m2:V1 = (200 to 300):1, the mass m3 of the first stabilizer component and the volume V1 of the gold supplement satisfy: m3:V1 = (15 to 30):1, and if the units of m1, m2, and m3 are g, then the unit of V1 is L.

[0008] Optionally, the second sulfite solution includes a second sulfite component and a second stabilizer component; the mass m4 of the second sulfite component and the volume V2 of the second sulfite solution satisfy: m4:V2 = (200 to 260):1, the mass m5 of the second stabilizer component and the volume V2 of the second sulfite solution satisfy: m5:V2 = (15 to 30):1, and if the units of m4 and m5 are g, then the unit of V1 is L.

[0009] Optionally, the sulfite-based cyanide-free gold plating solution includes a second gold component and a third sulfite component. The standard mass m6 of the second gold component and the volume V3 of the sulfite-based cyanide-free gold plating solution satisfy the following condition: m6:V3 = (0.1 to 20.0):1. The standard mass m7 of the third sulfite component and the volume V3 of the sulfite-based cyanide-free gold plating solution satisfy the following condition: m7:V3 = (100 to 200):1. If the units of m1 and m2 are g, then the unit of V3 is L.

[0010] Optionally, the types of the first auxiliary complexing agent and the second auxiliary complexing agent include: nitrogen-containing organic complexing agents and / or polycarboxylate salts; The mass m8 of the first auxiliary complexing agent is equal to the volume V1 of the gold supplement, satisfying: m8:V1 = (8 to 12):1. If the unit of m8 is g, then the unit of V1 is L. The mass m9 of the second auxiliary complexing agent is equal to the volume V2 of the second sulfite solution, satisfying: m9:V2 = (8 to 12):1. If the unit of m9 is g, then the unit of V2 is L.

[0011] Optionally, the preparation steps of the chloroaurate solution include: Gold was pretreated with aqua regia to obtain a gold-containing solution; The gold-containing solution is heated and concentrated to remove nitrogen dioxide, yielding gold trichloride. The gold trichloride was sequentially cooled and prepared into a solution to obtain a gold-containing solution. The pH of the gold-containing solution was adjusted to obtain a chloroaurate solution.

[0012] Optionally, the heating and concentration temperature is 70°C to 100°C; and / or The target pH value for pH adjustment is 8 to 10, and the temperature for pH adjustment is less than 25°C.

[0013] Optionally, the preparation methods of the first sulfite solution and the second sulfite solution respectively include the following steps: Sulfite is dissolved in distilled water at a preset temperature to obtain a first sulfite solution or a second sulfite solution; wherein the preset temperature is 50°C to 60°C.

[0014] Secondly, embodiments of this application provide an intelligent control device for a cyanide-free sulfite electroplating gold solution. The intelligent control device is adapted to the maintenance method described in the first aspect and is used to analyze and maintain the cyanide-free sulfite electroplating gold solution in the electroplating tank. The intelligent control device includes: The sampling unit includes a filtration and defoaming device, a sampling tube, a sampling pump, and a sampling solenoid valve. The sampling solenoid valve is located at the inlet of the sampling tube, the inlet of the sampling tube is connected to the outlet of the electroplating tank, the outlet of the sampling tube is connected to the inlet of the sampling pump, and the outlet of the sampling pump is connected to the inlet of the filtration and defoaming device. The analysis unit includes a flow-through titration stirring cup, a stirring motor, a syringe pump, an X-ray fluorescence spectrometer, a redox potential composite electrode, and a wastewater tank. The inlet of the flow-through titration stirring cup is connected to the outlet of the filtration and defoaming device. The power output of the stirring motor is connected to the rotating end of the flow-through titration stirring cup. The X-ray fluorescence spectrometer is used to determine the mass content of gold in the cyanide-free gold plating solution to be tested in the flow-through titration stirring cup. The outlet of the syringe pump is connected to the inlet of the flow-through titration stirring cup and is used to introduce hydrochloric acid and sodium thiosulfate standard solution into the flow-through titration stirring cup. The redox potential composite electrode is used to determine the mass content of sulfite in the cyanide-free gold plating solution to be tested in the flow-through titration stirring cup. The outlet of the flow-through titration stirring cup is connected to the inlet of the wastewater tank. The dosing unit includes a gold supplement storage device and a sulfite supplement storage device. The outlet of the gold supplement storage device is connected to the gold supplement inlet of the electroplating tank, and the outlet of the sulfite supplement storage device is connected to the sulfite supplement inlet of the electroplating tank. The display unit is connected to the X-ray fluorescence spectrometer and the redox potential composite electrode via electrical signals. The control unit includes a PLC controller, a gold supplement metering pump, and a sulfite supplement metering pump. The gold supplement metering pump is located at the outlet of the gold supplement storage device, and the sulfite supplement metering pump is located at the outlet of the sulfite supplement storage device. The PLC controller is connected to the sampling solenoid valve, the gold supplement metering pump, and the sulfite supplement metering pump via electrical signals.

[0015] Optionally, both the gold supplement storage device and the sulfite supplement storage device include a storage tank, an electric heating element, a temperature sensor, and a level gauge. The outlet of the storage tank is the outlet of either the gold supplement storage device or the sulfite supplement storage device. The electric heating element and the temperature sensor are located inside the storage tank. The level gauge is located inside the storage tank and is used to measure the liquid level inside the storage tank. The heating element, the temperature sensor, and the level gauge are all connected to the PLC controller via electrical signals.

[0016] The technical solutions provided in this application have the following advantages compared with the prior art: This application provides a method for maintaining a sulfite-based cyanide-free gold plating solution. The method first uses a first sulfite solution, a first auxiliary complexing agent, and a chloroaurate solution to form a gold replenisher. Through the synergistic effect of these three solutions, a double complexation is formed to stabilize the gold ions, ensuring the added gold ions remain stable in the sulfite-based cyanide-free gold plating solution for a long period. Furthermore, a second sulfite solution and a second auxiliary complexing agent are used to form the sulfite replenisher, preventing the reduction reaction between gold ions and excess sulfite in a single replenisher, which would lead to gold precipitation and sulfite loss. Simultaneously, the synergistic effect of the auxiliary complexing agent prolongs the stability of the added components in the sulfite-based cyanide-free gold plating solution. The cycle lays the material foundation for concentration stability. In addition, X-ray fluorescence analysis (XRF) is used to determine the mass content of gold in the cyanide-free gold plating solution to be tested, and potentiometric titration analysis is used to determine the mass content of sulfite in the cyanide-free gold plating solution to be tested. This ensures that the obtained concentration data truly reflects the actual state of the cyanide-free gold plating solution. Then, based on the determined actual state of the cyanide-free gold plating solution, the required amount of gold supplement and sulfite supplement can be calculated. The supplementation amount can be calculated differently and adapted to different consumption rates to avoid secondary fluctuations in the cyanide-free gold plating solution caused by excessive supplementation. This improves the stability of the mass content of sulfite and gold in the cyanide-free gold plating solution during maintenance. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A schematic diagram of a maintenance method for a cyanide-free electroplating gold solution provided in this application embodiment; Figure 2 A schematic diagram of the preparation steps of the chloroaurate solution provided in the embodiments of this application; Figure 3 This is a schematic diagram of the preparation method of the first sulfite solution or the second sulfite solution provided in the embodiments of this application; Figure 4 This application provides a schematic diagram of the logic structure of an intelligent control device for a sulfite-based cyanide-free gold plating solution. Figure 5 This application provides an actual distribution diagram of the intelligent control equipment for a sulfite-based cyanide-free gold plating solution. Among them, 1-electroplating tank, 2-filtration and defoaming device, 3-sampling tube, 4-sampling pump, 5-sampling solenoid valve, 6-flow-through titration stirring cup, 7-stirring motor, 8-injection pump, 9-X-ray fluorescence spectrometer, 10-oxidation-reduction potential composite electrode, 11-wastewater tank, 12-gold supplement storage device, 1201-storage tank, 1202-heating tube, 1203-temperature sensor, 1204-level gauge, 13-sulfite supplement storage device, 14-display unit, 15-PLC controller, 16-gold supplement metering pump, 17-sulfite supplement metering pump. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The range descriptions used in this application, such as numerical ranges and proportional ranges, include all possible sub-ranges and single numerical values ​​within that range. For example, the range descriptions of "1 to 6" or "1~6" cover all sub-ranges (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6) between 1 and 6. Unless otherwise specified, the terms "comprising" and others used herein mean "including but not limited to"; relational terms such as "first" and "second" are used only to distinguish different entities or operations and do not imply an actual order or relationship; "and / or" indicates that multiple situations can exist individually or simultaneously; expressions such as "at least one," "multiple," and "at least one" refer to any combination of the corresponding objects, including combinations of single or multiple objects. The proportional relationships involved in this document, such as mass ratios and molar ratios, should be understood as the correspondence between the first and second terms of a proportional formula, according to the order of description. The raw materials, reagents, instruments, and equipment used herein can all be obtained by purchasing from the market or by existing methods.

[0022] Figure 1 An exemplary schematic diagram of a maintenance method for a cyanide-free electroplating gold solution provided in an embodiment of this application is shown. like Figure 1 As shown in the embodiment of this application, a method for maintaining a sulfite-based cyanide-free gold plating solution is provided. The maintenance method includes: S1. Mix the first sulfite solution, the first auxiliary complexing agent, and the chloroaurate solution to obtain the gold supplement; S2. Mix the second sulfite solution and the second auxiliary complexing agent to obtain a sulfite supplement; S3. Take a sample of the cyanide-free gold plating solution in the electroplating tank to obtain the cyanide-free gold plating solution to be tested; S4. Perform X-ray fluorescence analysis on the cyanide-free electroplating gold solution to be tested to obtain the first mass content of gold; S5. The cyanide-free electroplating gold solution to be tested after X-ray fluorescence analysis was subjected to potentiometric titration analysis using hydrochloric acid and sodium thiosulfate standard solutions to obtain the second mass content of sulfite. S6. Determine the first amount of gold supplement and the second amount of sulfite supplement added based on the first mass content of gold and the second mass content of sulfite; S7. According to the first addition amount and the second addition amount, the gold supplement and the sulfite supplement are added to the sulfite cyanide-free electroplating gold solution respectively to complete the maintenance of the sulfite cyanide-free electroplating gold solution.

[0023] It should be noted that in the potentiometric titration analysis, the pH of the cyanide-free gold plating solution to be tested is first adjusted with hydrochloric acid, and then the potential difference is measured by back titration using a sodium thiosulfate standard solution through an oxidation-reduction potential composite electrode (ORP electrode). The mass content of sulfite in the cyanide-free gold plating solution to be tested can be calculated from the corresponding potential difference.

[0024] It should be noted that the maintenance method for a cyanide-free sulfite electroplating gold solution provided in this application embodiment employs four core logics: targeted supplement design, precise dual-component detection, quantitative on-demand replenishment, and step-by-step safe replenishment. This systematically suppresses concentration fluctuations of gold and sulfite in the cyanide-free sulfite electroplating gold solution from four dimensions: supplement effectiveness, detection accuracy, replenishment compatibility, and mixing safety, ultimately achieving long-term stability of their mass content. The specific mechanism is as follows: I. Targeted supplement design: Ensuring the effectiveness and compatibility of supplemented ingredients from the source.

[0025] The maintenance method provided in this application provides separate preparations of gold supplements and sulfite supplements, instead of using a single mixed supplement. By adapting to the consumption characteristics of gold and sulfite in the cyanide-free sulfite electroplating gold solution and the requirements for chemical stability, the loss or interference of components during the replenishment process is avoided. 1. Gold Supplement: Stabilizes the gold ion form in sulfite-free gold plating solution, preventing precipitation loss. (1) The gold supplement is composed of a first sulfite solution, a first auxiliary complexing agent, and a chloroaurate solution: Chloroaurate is a stable source of gold ions, ensuring that the gold consumed by electroplating deposition in the sulfite-free gold plating solution can be quickly replenished after replenishment. (2) The first sulfite and the first auxiliary complexing agent work synergistically to form a dual complexation stability for gold ions: the sulfite acts as the main complexing agent, forming a stable [Au(SO3)2] with gold ions. 3- The complexed ion system avoids the precipitation caused by the hydrolysis of gold ions; the auxiliary complexing agent (such as citric acid, EDTA, etc.) further enhances the stability of the complexed ion system, inhibits the aggregation of gold ions in the sulfite cyanide-free electroplating gold solution or their reduction to elemental gold, and ensures that the added gold ions can exist stably in the sulfite cyanide-free electroplating gold solution for a long time.

[0026] 2. Sulfite supplements: Prevent oxidative loss and precisely replenish effective ingredients. (1) The sulfite supplement is composed of a second sulfite solution and a second auxiliary complexing agent: The second sulfite (such as sodium sulfite or potassium sulfite) is directly used as an effective ingredient to replenish the sulfite consumed in the cyanide-free electroplating gold solution due to oxidation (oxidation by oxygen in the air or oxidants generated during the electroplating process) and decomposition. The second auxiliary complexing agent (such as sodium metabisulfite, glycolic acid, etc.) has the dual function of anti-oxidation and complexing impurities: on the one hand, it inhibits the oxidation of sulfites to sulfates (losing the ability to complex alloy ions), and on the other hand, it adsorbs trace metal impurities (such as Fe) in cyanide-free gold plating solutions that may catalyze the decomposition of sulfites. 3+ Cu 2+ This reduces the ineffective consumption of sulfites at the source, ensuring that the added sulfites can maintain an effective concentration for a long time.

[0027] 3. Core Functions: The two supplements are specifically designed for the components in the sulfite-free cyanide electroplating gold solution, avoiding the reduction reaction between gold ions and excess sulfite (leading to gold precipitation and sulfite loss) that occurs with a single supplement. At the same time, through the synergistic effect of the auxiliary complexing agent, the stability period of the added components in the sulfite-free cyanide electroplating gold solution is extended, laying the material basis for concentration stability.

[0028] II. Precise dual-component detection: providing unbiased data support for stable regulation.

[0029] The maintenance method provided in this application uses a proprietary detection scheme that combines X-ray fluorescence analysis (XRF) to determine the gold content in the cyanide-free gold plating solution with potentiometric titration analysis to determine the sulfite content. This solves the problems of large errors and long processing times associated with traditional detection methods (such as colorimetry and gravimetric methods), ensuring that the obtained concentration data accurately reflects the actual state of the sulfite-free gold plating solution. 1. Gold content testing: non-destructive, rapid, and precise quantification. (1) XRF analysis is a non-destructive testing technique. It does not require the addition of chemical reagents to the cyanide-free electroplating gold solution to be tested, thus avoiding changes in the valence state of gold ions during the testing process (such as being reduced to zero valence gold) or disruption of complexation equilibrium, ensuring that the test results can truly reflect the mass content of effective gold ions in the cyanide-free electroplating gold solution to be tested. (2) XRF has high quantitative accuracy for metal elements and can accurately capture the small fluctuations in the gold content in the cyanide-free electroplating gold solution to be tested, avoiding excessive or insufficient addition due to detection errors.

[0030] 2. Sulfite content detection: anti-interference, clear endpoint, rapid response. (1) A comprehensive system of hydrochloric acid acidification + back titration with sodium thiosulfate standard solution + ORP electrode potential determination is adopted: hydrochloric acid acidification can eliminate the interference of impurities such as carbonate in the cyanide-free electroplating solution to be tested, while the reaction between sodium thiosulfate and sulfite is specific (1:1 quantitative reaction). The ORP electrode can accurately determine the titration endpoint through the potential jump in the cyanide-free electroplating solution to be tested, avoiding the subjective error caused by visual judgment of the endpoint in traditional manual titration. This detection method is quick and can rapidly respond to the dynamic consumption of sulfites, avoiding the situation where the concentration of sulfites in the cyanide-free gold plating solution deviates from the set range for too long due to detection lag.

[0031] 3. Core function: The accurate, rapid, and interference-resistant detection of the two components ensures real-time and accurate perception of the mass concentration of gold and sulfite, providing an unbiased data basis for subsequent supplementation calculations and avoiding the vicious cycle of data distortion → inaccurate supplementation → concentration fluctuation.

[0032] 3. Quantitative replenishment on demand: Achieving a dynamic balance between how much is consumed and how much is replenished.

[0033] The core of the maintenance method provided in this application, which determines the amount to be added based on the first mass content and the second mass content, is to break away from the blindness of traditional fixed-ratio replenishment and achieve precise matching between the replenishment amount and the actual consumption amount. 1. Differentiated calculation of replenishment amount to adapt to different consumption rates: During the electroplating process, the consumption rate of gold in the cyanide-free sulfite electroplating gold solution is directly related to the electroplating current density, workpiece surface area, and electroplating time (following Faraday's law), while the consumption rate of sulfite is related to factors such as the temperature, aeration intensity, and impurity content of the cyanide-free sulfite electroplating gold solution. The consumption rates of the two are not in a fixed ratio.

[0034] The maintenance method provided in this application embodiment detects the actual concentrations of the two components separately and compares them with the set standard concentrations (e.g., Au: 0.1g / L to 20g / L, sodium sulfite: 100g / L to 200g / L), calculates the concentration difference between them, and then, combined with the volume of the cyanide-free sulfite electroplating gold solution in the electroplating tank and the concentration of the effective component in the supplement, accurately calculates the first addition amount and the second addition amount {formula: addition amount = (standard concentration - actual concentration) × volume of cyanide-free sulfite electroplating gold solution / effective concentration of supplement}.

[0035] 2. Avoid secondary fluctuations caused by excessive supplementation: If a single mixed supplement is used, it may lead to an excess of sulfite to meet the gold replenishment requirement, or vice versa. Excess gold results in coarse grains and reduced gloss in the electroplated layer, while excess sulfite increases the viscosity of the cyanide-free sulfite electroplating solution and reduces the plating rate. Furthermore, excess sulfite is easily oxidized to sulfate (which, upon accumulation, affects the complexation balance of gold ions). The maintenance method provided in this application, through targeted calculations, ensures that both components return to their standard concentration range after replenishment, avoiding secondary concentration fluctuations caused by excessive replenishment.

[0036] 3. Core function: The quantitative on-demand replenishment achieves dynamic balance control of gold and sulfite in the cyanide-free sulfite electroplating gold solution, ensuring that the replenishment amount always closely follows the actual consumption, fundamentally suppressing the periodic fluctuations of low concentration → excessive concentration → low concentration, and maintaining the mass concentration of gold and sulfite in the cyanide-free sulfite electroplating gold solution within the set range.

[0037] IV. Step-by-step safe replenishment: to avoid local concentration imbalance and component loss during the replenishment process.

[0038] The maintenance method provided in this application, which involves adding gold supplement and sulfite supplement separately, aims to prevent localized reactions when the two supplements are mixed, ensuring that the added components are evenly dispersed in the cyanide-free sulfite electroplating gold solution. 1. Add separately to avoid localized reaction losses: If the gold supplement and sulfite supplement are added simultaneously, the high concentration of chloroaurate and excess sulfite may undergo a local reduction reaction (sulfite reduces gold ions to gold precipitate), resulting in the loss of both gold ions and sulfite. This reduces the supplementation efficiency, introduces impurities, and compromises the stability of the cyanide-free sulfite gold plating solution. When added separately, both supplements are slowly dispersed under stirring in the cyanide-free sulfite gold plating solution, gradually reducing the concentration gradient and avoiding side reactions caused by excessively high local concentrations.

[0039] 2. Disperse evenly to ensure consistent overall concentration: When added in stages, the two supplements can be fully mixed with the sulfite-free gold plating solution in batches, avoiding situations where the gold concentration is too high or too low in some areas, or where the sulfite concentration is too high or too low in some areas. This ensures that the concentrations of the two components in each area of ​​the sulfite-free gold plating solution are uniform and consistent, thereby guaranteeing the consistency of the electroplating product quality.

[0040] 3. Core function: Step-by-step replenishment avoids component loss and local concentration imbalance during the replenishment process from the perspective of process control, ensuring that the added effective components can play their role, and the overall concentration of the sulfite-free cyanide electroplating gold solution is uniform, further enhancing the concentration stability of the sulfite-free cyanide electroplating gold solution.

[0041] In summary, the present application provides a maintenance method for a cyanide-free sulfite electroplating gold solution. This method achieves a closed-loop control throughout the entire process by using a dedicated supplement to ensure component stability, accurately detecting and capturing concentration changes, quantitatively calculating and matching actual consumption, and adding the solution step by step to avoid process interference. This systematically solves four major pain points in traditional maintenance methods: easy loss of added components, inaccurate detection data, mismatched addition amounts, and easy interference during the mixing process. Ultimately, it achieves long-term stability of the gold and sulfite content in the cyanide-free sulfite electroplating gold solution, ensuring the continuity of the electroplating process and the consistency of product quality.

[0042] In some optional embodiments, the gold supplement includes a first gold component, a first sulfite component, and a first stabilizer component; the mass m1 of the first gold component and the volume V1 of the gold supplement satisfy: m1:V1 = (40 to 50):1, the mass m2 of the first sulfite component and the volume V1 of the gold supplement satisfy: m2:V1 = (200 to 300):1, the mass m3 of the first stabilizer component and the volume V1 of the gold supplement satisfy: m3:V1 = (15 to 30):1, and if the units of m1, m2, and m3 are g, then the unit of V1 is L.

[0043] In these embodiments, a gold supplement comprising a first gold component, a first sulfite component, and a first stabilizer component is used. The ratio of the mass of the first gold component to the volume of the gold supplement is controlled to be (40 to 50) g:1L, the ratio of the volume of the first sulfite component to the volume of the gold supplement is controlled to be (200 to 300) g:1L, and the ratio of the mass of the first stabilizer component to the volume of the gold supplement is controlled to be (15 to 30) g:1L. Through the interaction between the first gold component, the first sulfite component, and the first stabilizer component, the gold ion morphology in the cyanide-free sulfite electroplating gold solution is stabilized, and the loss of the gold supplement is avoided due to gold precipitation during the replenishment process.

[0044] The mass m1 of the first gold component can be 40, 41, 42, 43, 44, 45 or 50.

[0045] The mass m2 of the first sulfite component can be 200, 210, 220, 230, 240, 250 or 300.

[0046] The mass m3 of the first stabilizer component can be 15, 18, 19, 20, 21, 22, 23, 24, 25 or 30.

[0047] In some optional embodiments, the second sulfite solution includes a second sulfite component and a second stabilizer component; the mass m4 of the second sulfite component and the volume V2 of the second sulfite solution satisfy: m4:V2 = (200 to 260):1, the mass m5 of the second stabilizer component and the volume V2 of the second sulfite solution satisfy: m5:V2 = (15 to 30):1, and if the units of m4 and m5 are g, then the unit of V1 is L.

[0048] In these embodiments, a second sulfite solution comprising a second sulfite component and a second stabilizer component is used, and the ratio of the mass of the second sulfite component to the volume of the second sulfite solution is controlled to be (200 to 260) g:1L, and the ratio of the mass of the second stabilizer component to the volume of the second sulfite solution is controlled to be (15 to 30) g:1L. Through the interaction between the second sulfite component and the second stabilizer component, the reduction reaction between gold ions and excess sulfite in a single supplement is avoided, which would lead to gold precipitation and sulfite loss. At the same time, through the synergistic effect of the auxiliary complexing agent, the stabilization period of the added components in the sulfite-free cyanide electroplating gold solution is extended.

[0049] The mass m4 of the second sulfite component can be 200, 210, 220, 230, 240, 250 or 260.

[0050] The mass m5 of the second stabilizer component can be 15, 18, 19, 20, 21, 22, 23, 24, 25 or 30.

[0051] In some optional embodiments, the sulfite-based cyanide-free electroplating gold solution includes a second gold component and a third sulfite component. The standard mass m6 of the second gold component and the volume V3 of the sulfite-based cyanide-free electroplating gold solution satisfy the following ratio: m6:V3 = (0.1 to 20.0):1. The standard mass m7 of the third sulfite component and the volume V3 of the sulfite-based cyanide-free electroplating gold solution satisfy the following ratio: m7:V3 = (100 to 200):1. If the units of m1 and m2 are g, then the unit of V3 is L.

[0052] In these embodiments, a cyanide-free sulfite electroplating gold solution comprising a second gold component and a third sulfite component is used. The ratio of the standard mass of the second gold component to the volume of the cyanide-free sulfite electroplating gold solution is controlled to be (0.1 to 20.0) g:1L, and the ratio of the standard mass of the third sulfite component to the volume of the cyanide-free sulfite electroplating gold solution is controlled to be (100 to 200) g:1L. This can cover most of the components of the cyanide-free sulfite electroplating gold solution, which is beneficial to the application objects of the maintenance method provided in the embodiments of this application.

[0053] The standard mass m6 of the two metal components can be 0.1, 0.2, 0.3, 0.4, 0.5, 1.0, 1.5, 2.0, 2.5, 5.0, 10.0, 15.0 or 20.0.

[0054] The standard mass m7 of the third sulfite component can be 100, 110, 120, 130, 140, 150 or 200.

[0055] In some optional embodiments, the types of the first auxiliary complexing agent and the second auxiliary complexing agent include: nitrogen-containing organic complexing agents and / or polycarboxylate salts; The mass m8 of the first auxiliary complexing agent is equal to the volume V1 of the gold supplement, satisfying: m8:V1 = (8 to 12):1. If the unit of m8 is g, then the unit of V1 is L. The mass m9 of the second auxiliary complexing agent is equal to the volume V2 of the second sulfite solution, satisfying the formula: m9:V2 = (8 to 12):1. If the unit of m9 is g, then the unit of V2 is L. In these embodiments, by using a nitrogen-containing organic complexing agent and / or a first auxiliary complexing agent and a second auxiliary complexing agent of a polycarboxylate, and controlling the mass ratio of the first auxiliary complexing agent to the volume of the gold supplement to (8 to 12):1, and controlling the mass ratio of the second auxiliary complexing agent to the volume of the second sulfite solution to (8 to 12):1, the stability period of the added components (gold supplement and sulfite supplement) in the sulfite-free gold plating solution can be extended through complexation and synergistic effect with other components.

[0056] It should be noted that when the first and second auxiliary complexing agents are nitrogen-containing organic complexing agents, they can specifically be ethylenediamine or triethanolamine. When the first and second auxiliary complexing agents are polycarboxylate salts, they can specifically be citrate salts.

[0057] Figure 2 An exemplary schematic diagram of the preparation steps of the chloroaurate solution provided in the embodiments of this application is shown; In some alternative implementations, such as Figure 2 As shown, the preparation steps of the chloroaurate solution include: S101. Gold is pretreated with aqua regia to obtain a gold-containing solution; S102. The gold-containing solution is heated and concentrated to remove nitrogen dioxide from the gold-containing solution, yielding gold trichloride; S103. The gold trichloride is cooled and prepared into a solution sequentially to obtain a gold-containing solution; S104. Adjust the pH of the gold-containing solution to obtain a chloroaurate solution.

[0058] In these embodiments, pretreating gold with aqua regia converts solid gold into a liquid gold-containing solution. Heating and concentration then not only increases the gold concentration in the solution but also removes nitrogen dioxide formed during the gold dissolution process, improving the purity of gold trichloride. Cooling and dissolving the gold trichloride further yields a gold-containing solution with a specific concentration. Finally, pH adjustment makes the solution slightly alkaline, which is beneficial for the subsequent formation of a chloroaurate solution.

[0059] It should be noted that the pretreatment can be performed by first cutting high-purity (>99.98%) gold into small pieces; then washing and drying the small pieces to obtain dried gold particles; and then dissolving the dried gold particles in aqua regia under well-ventilated conditions and water bath heating to obtain a gold-containing solution.

[0060] It should be noted that potassium hydroxide solution is generally used in the pH adjustment process. The potassium hydroxide solution neutralizes the acidic components in the gold-containing solution, increasing the pH while simultaneously converting a large number of gold ions into chloroaurate ions, thus forming a chloroaurate solution such as potassium chloroaurate. Furthermore, due to the exothermic nature of the neutralization reaction, and considering the characteristics of chloroaurate solutions, the pH adjustment temperature must be controlled below 25°C.

[0061] In some alternative embodiments, the temperature for heat concentration is 70°C to 100°C; and / or The target pH value for pH adjustment is 8 to 10, and the temperature for pH adjustment is less than 25°C.

[0062] In these embodiments, heating and concentration at temperatures between 70°C and 100°C not only increases the mass concentration of gold in the gold-containing solution but also removes the nitrogen dioxide component formed during the gold dissolution process in aqua regia, thereby improving the purity of gold trichloride. Furthermore, pH adjustments to a target value of 8 to 10 and a temperature below 25°C ensure that gold ions in the gold-containing solution are stably converted to chloroaurate ions, preventing the decomposition of chloroaurate due to the exothermic neutralization reaction and thus avoiding the loss of the gold supplement.

[0063] The heating and concentration temperature can be 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃.

[0064] The target pH value for this pH adjustment can be 8, 8.5, 9, 9.5, or 10.

[0065] Figure 3 An exemplary schematic diagram of the preparation method of the first sulfite solution or the second sulfite solution provided in the embodiments of this application is shown; In some alternative implementations, such as Figure 3 As shown, the preparation methods of the first sulfite solution and the second sulfite solution respectively include the following steps: S201. Dissolve sulfite in distilled water at a preset temperature to obtain a first sulfite solution or a second sulfite solution; wherein the preset temperature is 50°C to 60°C.

[0066] In these embodiments, distilled water at a preset temperature can effectively dissolve nitrites in sulfites and form a uniformly dispersed first or second sulfite solution.

[0067] The preset temperature can be 50℃, 51℃, 52℃, 53℃, 54℃, 55℃ or 60℃.

[0068] Figure 4An exemplary illustration shows a schematic diagram of the logic structure of an intelligent control device for a sulfite-based cyanide-free electroplating gold solution, as provided in an embodiment of this application. Figure 5 An exemplary diagram of the actual distribution of an intelligent control device for a cyanide-free sulfite electroplating gold solution, as provided in an embodiment of this application, is shown. Based on a general inventive concept, such as Figure 4 and Figure 5 As shown in the illustration, this application provides an intelligent control device for a cyanide-free sulfite electroplating gold solution. The intelligent control device is adapted to the maintenance method and is used to analyze and maintain the cyanide-free sulfite electroplating gold solution in electroplating tank 1. The intelligent control device includes: The sampling unit includes a filtration and defoaming device 2, a sampling tube 3, a sampling pump 4, and a sampling solenoid valve 5. The sampling solenoid valve 5 is located at the inlet of the sampling tube 3. The inlet of the sampling tube 3 is connected to the outlet of the electroplating tank 1. The outlet of the sampling tube 3 is connected to the inlet of the sampling pump 4. The outlet of the sampling pump 4 is connected to the inlet of the filtration and defoaming device 2. The analysis unit includes a flow-through titration stirring cup 6, a stirring motor 7, a syringe pump 8, an X-ray fluorescence spectrometer 9, a redox potential composite electrode 10, and a wastewater tank 11. The inlet of the flow-through titration stirring cup 6 is connected to the outlet of the filtration and defoaming device 2. The power output of the stirring motor 7 is connected to the rotation end of the flow-through titration stirring cup 6. The X-ray fluorescence spectrometer 9 is used to determine the mass content of gold in the cyanide-free electroplating gold solution to be tested in the flow-through titration stirring cup 6. The outlet of the syringe pump 8 is connected to the inlet of the flow-through titration stirring cup 6 and is used to pour hydrochloric acid and sodium thiosulfate standard solution into the flow-through titration stirring cup 6. The redox potential composite electrode 10 is used to determine the mass content of sulfite in the cyanide-free electroplating gold solution to be tested in the flow-through titration stirring cup 6. The outlet of the flow-through titration stirring cup 6 is connected to the inlet of the wastewater tank 11. The dosing unit includes a gold supplement storage device 12 and a sulfite supplement storage device 13. The outlet of the gold supplement storage device 12 is connected to the gold supplement inlet of the electroplating tank 1, and the outlet of the sulfite supplement storage device 13 is connected to the sulfite supplement inlet of the electroplating tank 1. Display unit 14 is connected to X-ray fluorescence spectrometer 9 and redox potential composite electrode 10 via electrical signals; The control unit includes a PLC controller 15, a gold supplement metering pump 16, and a sulfite supplement metering pump 17. The gold supplement metering pump 16 is located at the outlet of the gold supplement storage device 12, and the sulfite supplement metering pump 17 is located at the outlet of the sulfite supplement storage device 13. The PLC controller 15 is connected to the sampling solenoid valve 5, the gold supplement metering pump 16, and the sulfite supplement metering pump 17 via electrical signals.

[0069] The intelligent control device is implemented based on the above maintenance method. The specific steps of the maintenance method can be referred to the above embodiments. Since the intelligent control device adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here.

[0070] It should be noted that the sampling pump 4 can be a corrosion-resistant peristaltic pump, and the sampling tube 3 can be a corrosion-resistant and wear-resistant flexible tube. In addition, the opening and closing control of the sampling solenoid valve 5 can selectively sample multiple electroplating tanks 1, thereby enabling online sampling and analysis of multiple electroplating tanks 1 with a single set of equipment.

[0071] It should be noted that the sampling tube 3, sampling pump 4 and filtration and defoaming device 2 work together to systematically filter and defoam the cyanite-free gold plating solution in the electroplating tank 1 to obtain the cyanite-free gold plating solution to be tested, and then introduce the cyanite-free gold plating solution to be tested into the flow-through titration stirring cup 6.

[0072] It should be noted that in the flow-through titration stirring cup 6, the mass content of gold in the cyanide-free electroplating solution to be tested is first determined by X-ray fluorescence spectrometer 9 (XRF spectrometer). Then, hydrochloric acid and sodium thiosulfate standard solution are added through syringe pump 8. In the flow-through titration stirring cup 6, the cyanide-free electroplating solution to be tested is back-titrated using redox potential composite electrode 10 (ORP electrode). The mass content of sulfite in the cyanide-free electroplating solution to be tested is calculated by the potential difference corresponding to the endpoint of the back titration. Therefore, the mass content of gold and sulfite in the cyanide-free electroplating solution to be tested can be quickly determined by a single analytical unit.

[0073] It should be noted that in the control unit, the PLC controller 15 can use a programmable logic controller (such as the Mitsubishi FX2N-32MR-001 PLC controller), and receive various transmitted signals through the signal receiving terminal of the PLC controller 15. Then, the chip in the PLC controller 15 processes and analyzes the results of the uploaded signals to determine whether the mass content of gold and sulfite in the cyanide-free electroplating gold solution to be tested is within the set standard range, form the analysis results, and transmit the data results to the display unit 14 for display. If the analysis results show that the mass content of gold and sulfite in the tested cyanide-free gold plating solution is lower than the set standard range, the PLC controller 15 needs to adjust the flow rates of the gold replenishment metering pump 16 and the sulfite replenishment metering pump 17 according to the difference between the mass content of gold and sulfite in the tested cyanide-free gold plating solution and the set standard range, based on the PID algorithm. This allows the metering pumps to automatically draw the required amount of chemicals from the gold replenishment storage device 12 and the sulfite replenishment storage device 13, precisely controlling the dosing instructions executed by the dosing unit, thereby achieving precise replenishment of gold and sulfite in the cyanide-free gold plating solution. Simultaneously, in addition to automatic replenishment of gold and sulfite replenishment, the PLC controller 15 can also achieve timed and quantitative addition and manual addition of gold and sulfite, catering to the production needs of different electroplating tanks 1.

[0074] It should be noted that the display unit 14 visualizes the overall intelligent control equipment's operating status, analysis results, and parameter settings through a series of displays, making it easier for operators to observe and intervene.

[0075] In some optional embodiments, both the gold supplement storage device 12 and the sulfite supplement storage device 13 include a storage tank 1201, a heating element 1202, a temperature sensor 1203, and a level gauge 1204. The outlet of the storage tank 1201 is the outlet of either the gold supplement storage device 12 or the sulfite supplement storage device 13. The heating element 1202 is disposed inside the storage tank 1201, and the temperature sensor 1203 is disposed inside the storage tank 1201. The level gauge 1204 is disposed inside the storage tank 1201 and is used to measure the liquid level in the storage tank 1201. The heating element 1202, the temperature sensor 1203, and the level gauge 1204 are all connected to the PLC controller 15 via electrical signals.

[0076] In these embodiments, the gold supplement storage device 12 and the sulfite supplement storage device 13 are configured as a combination structure including a storage tank 1201, an electric heating element 1202, a temperature sensor 1203, and a level gauge 1204. The electric heating element 1202 maintains the temperature of the storage tank 1201 at a constant level, and the temperature sensor 1203 detects the temperature data in the storage tank 1201 in real time and transmits the temperature data to the PLC controller 15. The PLC controller 15 can output data and control the heating level of the electric heating element 1202 to maintain the temperature of the storage tank 1201 at a constant level. In addition, the design of the level gauge 1204 can prevent excessive gold and sulfite supplements from entering the electroplating tank 1 from the storage tank 1201, which would cause the solution in the electroplating tank 1 to overflow, thereby achieving precise control of the mass content of gold and sulfite in the cyanide-free gold plating solution.

[0077] It should be noted that the medicine storage tank 1201 can be made of polypropylene (PP). The heating element 1202 can be made of corrosion-resistant material.

[0078] It should be noted that in this intelligent control device, the PLC controller 15 can determine the amount of gold supplement and sulfite supplement to be added to the electroplating tank 1 from the gold supplement storage device 12 and the sulfite supplement storage device 13 based on the input volume of the electroplating tank 1 and the standard mass content of gold and sulfite in the sulfite-free gold plating solution, combined with the first mass content of gold and the second mass content of sulfite measured in the analysis unit. The PLC controller 15 then transmits the calculated dosage to the gold supplement metering pump 16 and the sulfite supplement metering pump 17, so that the gold supplement metering pump 16 and the sulfite supplement metering pump 17 can respectively draw the corresponding dosage from the gold supplement storage device 12 and the sulfite supplement storage device 13, thereby achieving the maintenance of the sulfite-free gold plating solution in the electrolytic tank.

[0079] It should be noted that the storage tank 1201 in the gold supplement storage device 12 can be equipped with a stirring device, a heating temperature control device, and a pH display device, etc., to facilitate control of the preparation conditions of the gold supplement. Similarly, the storage tank 1201 in the sulfite supplement storage device 13 can also be equipped with a stirring device, a heating temperature control device, and a pH display device, etc., to facilitate control of the preparation conditions of the sulfite supplement.

[0080] The present application is further illustrated below with reference to specific embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national / industry standards; if there is no corresponding national / industry standard, they are performed according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0081] Example 1 like Figure 1 As shown, a method for maintaining a sulfite-based cyanide-free gold plating solution includes: S1. Mix the first sulfite solution, the first auxiliary complexing agent, and the chloroaurate solution to obtain the gold supplement; S2. Mix the second sulfite solution and the second auxiliary complexing agent to obtain a sulfite supplement; S3. Take a sample of the cyanide-free gold plating solution (total volume of 20L) in the electroplating tank to obtain the cyanide-free gold plating solution to be tested; S4. The cyanide-free gold plating solution to be tested was subjected to X-ray fluorescence analysis to obtain the first mass content of gold (5 g / L). S5. The cyanide-free electroplating gold solution to be tested after X-ray fluorescence analysis was subjected to potentiometric titration analysis using hydrochloric acid and sodium thiosulfate standard solutions to obtain the second mass content of sulfite (100 g / L). S6. Based on the first mass content of gold and the second mass content of sulfite, determine the first addition amount of gold supplement (5.56L) and the second addition amount of sulfite supplement (5.65L). S7. Add the gold supplement and sulfite supplement to the sulfite cyanide-free gold plating solution according to the first and second addition amounts, respectively, to complete the maintenance of the sulfite cyanide-free gold plating solution.

[0082] The gold supplement comprises a first gold component, a first sulfite component, and a first stabilizer component; the mass m1 of the first gold component and the volume V1 of the gold supplement satisfy the following ratio: m1:V1=45:1; the mass m2 of the first sulfite component and the volume V1 of the gold supplement satisfy the following ratio: m2:V1=250:1; the mass m3 of the first stabilizer component and the volume V1 of the gold supplement satisfy the following ratio: m3:V1=25:1. If the units of m1, m2, and m3 are g, then the unit of V1 is L.

[0083] The second sulfite solution includes a second sulfite component and a second stabilizer component; the mass m4 of the second sulfite component and the volume V2 of the second sulfite solution satisfy the ratio m4:V2=230:1, the mass m5 of the second stabilizer component and the volume V2 of the second sulfite solution satisfy the ratio m5:V2=25:1, and if the units of m4 and m5 are g, then the unit of V1 is L.

[0084] The cyanide-free sulfite electroplating gold solution includes a second gold component and a third sulfite component. The standard mass m6 of the second gold component and the volume V3 of the cyanide-free sulfite electroplating gold solution satisfy the following formula: m6:V3 = (15 to 20):1. The standard mass m7 of the third sulfite component and the volume V3 of the cyanide-free sulfite electroplating gold solution satisfy the following formula: m7:V3 = (150 to 180):1. If the units of m1 and m2 are g, then the unit of V3 is L.

[0085] The first and second auxiliary complexing agents are ethylenediamine.

[0086] like Figure 2 As shown, the preparation steps of chloroaurate solution include: S101. Gold is pretreated with aqua regia to obtain a gold-containing solution; S102. The gold-containing solution is heated and concentrated to remove nitrogen dioxide from the gold-containing solution, yielding gold trichloride; S103. Gold trichloride is cooled and prepared sequentially to obtain a gold-containing solution; S104. Adjust the pH of the gold-containing solution to obtain a chloroaurate solution.

[0087] The temperature for heating and concentration is 90°C to 100°C; The target pH value for pH adjustment is 8 to 10, and the temperature for pH adjustment is less than 25°C.

[0088] like Figure 3 As shown, the preparation methods of the first sulfite solution and the second sulfite solution respectively include the following steps: S201. Dissolve sulfite in distilled water at a preset temperature to obtain a first sulfite solution or a second sulfite solution; wherein the preset temperature is 50°C to 60°C.

[0089] Example 2 Compared to Example 1, the differences in this example are as follows: The mass m1 of the first gold component and the volume V1 of the gold supplement satisfy the following ratio: m1:V1=40:1. The mass m2 of the first sulfite component and the volume V1 of the gold supplement satisfy the following ratio: m2:V1=200:1. The mass m3 of the first stabilizer component and the volume V1 of the gold supplement satisfy the following ratio: m3:V1=15:1. If the units of m1, m2 and m3 are g, then the unit of V1 is L.

[0090] The mass m4 of the second sulfite component and the volume V2 of the second sulfite solution satisfy the following ratio: m4:V2=200:1. The mass m5 of the second stabilizer component and the volume V2 of the second sulfite solution satisfy the following ratio: m5:V2=15:1. If the units of m4 and m5 are g, then the unit of V1 is L.

[0091] The standard mass m6 of the second gold component and the volume V3 of the sulfite-based cyanide-free gold plating solution satisfy the following formula: m6:V3 = (10 to 15.0):1. The standard mass m7 of the third sulfite component and the volume V3 of the sulfite-based cyanide-free gold plating solution satisfy the following formula: m7:V3 = (100 to 150):1. If the units of m1 and m2 are g, then the unit of V3 is L. The heating and concentration temperature is 70°C to 80°C.

[0092] Example 3 Compared to Example 1, the differences in this example are as follows: The mass m1 of the first gold component and the volume V1 of the gold supplement satisfy the following ratio: m1:V1=50:1. The mass m2 of the first sulfite component and the volume V1 of the gold supplement satisfy the following ratio: m2:V1=300:1. The mass m3 of the first stabilizer component and the volume V1 of the gold supplement satisfy the following ratio: m3:V1=30:1. If the units of m1, m2 and m3 are g, then the unit of V1 is L.

[0093] The mass m4 of the second sulfite component and the volume V2 of the second sulfite solution satisfy the following ratio: m4:V2=260:1. The mass m5 of the second stabilizer component and the volume V2 of the second sulfite solution satisfy the following ratio: m5:V2=30:1. If the units of m4 and m5 are g, then the unit of V1 is L.

[0094] The standard mass m6 of the second gold component and the volume V3 of the sulfite-based cyanide-free gold plating solution satisfy the following formula: m6:V3 = (5 to 10.0):1. The standard mass m7 of the third sulfite component and the volume V3 of the sulfite-based cyanide-free gold plating solution satisfy the following formula: m7:V3 = (180 to 200):1. If the units of m1 and m2 are g, then the unit of V3 is L. The heating and concentration temperature is 80°C to 90°C.

[0095] Example 4 Based on Example 1, a smart control device for sulfite cyanide-free electroplating gold solution is further provided.

[0096] like Figure 4 and Figure 5 As shown, an intelligent control device for a cyanide-free sulfite electroplating gold solution, and an intelligent control device adapted for maintenance, are used to analyze and maintain the cyanide-free sulfite electroplating gold solution in electroplating tank 1, including: The sampling unit includes a filtration and defoaming device 2, a sampling tube 3, a sampling pump 4, and a sampling solenoid valve 5. The sampling solenoid valve 5 is located at the inlet of the sampling tube 3. The inlet of the sampling tube 3 is connected to the outlet of the electroplating tank 1. The outlet of the sampling tube 3 is connected to the inlet of the sampling pump 4. The outlet of the sampling pump 4 is connected to the inlet of the filtration and defoaming device 2. The analysis unit includes a flow-through titration stirring cup 6, a stirring motor 7, a syringe pump 8, an X-ray fluorescence spectrometer 9, a redox potential composite electrode 10, and a wastewater tank 11. The inlet of the flow-through titration stirring cup 6 is connected to the outlet of the filtration and defoaming device 2. The power output of the stirring motor 7 is connected to the rotating end of the flow-through titration stirring cup 6. The X-ray fluorescence spectrometer 9 is used to determine the mass content of gold in the cyanide-free electroplating gold solution to be tested in the flow-through titration stirring cup 6. The outlet of the syringe pump 8 is connected to the inlet of the flow-through titration stirring cup 6 and is used to pour hydrochloric acid and sodium thiosulfate standard solution into the flow-through titration stirring cup 6. The redox potential composite electrode 10 is used to determine the mass content of sulfite in the cyanide-free electroplating gold solution to be tested in the flow-through titration stirring cup 6. The outlet of the flow-through titration stirring cup 6 is connected to the inlet of the wastewater tank 11. The dosing unit includes a gold supplement storage device 12 and a sulfite supplement storage device 13. The outlet of the gold supplement storage device 12 is connected to the gold supplement inlet of the electroplating tank 1, and the outlet of the sulfite supplement storage device 13 is connected to the sulfite supplement inlet of the electroplating tank 1. Display unit 14 is connected to X-ray fluorescence spectrometer 9 and redox potential composite electrode 10 via electrical signals; The control unit includes a PLC controller 15, a gold supplement metering pump 16, and a sulfite supplement metering pump 17. The gold supplement metering pump 16 is located at the outlet of the gold supplement storage device 12, and the sulfite supplement metering pump 17 is located at the outlet of the sulfite supplement storage device 13. The PLC controller 15 is connected to the sampling solenoid valve 5, the gold supplement metering pump 16, and the sulfite supplement metering pump 17 via electrical signals.

[0097] Both the gold supplement storage device 12 and the sulfite supplement storage device 13 include a storage tank 1201, an electric heating element 1202, a temperature sensor 1203, and a level gauge 1204. The outlet of the storage tank 1201 is the outlet of either the gold supplement storage device 12 or the sulfite supplement storage device 13. The electric heating element 1202 is located inside the storage tank 1201, and the temperature sensor 1203 is located inside the storage tank 1201. The level gauge 1204 is located inside the storage tank 1201 and is used to measure the liquid level inside the storage tank 1201. The heating element 1202, temperature sensor 1203 and level gauge 1204 are all connected to the PLC controller 15 via electrical signals.

[0098] Comparative Example 1 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: Instead of using the intelligent control equipment, manual measurement and supplementation are used directly.

[0099] Comparative Example 2 Compared to Example 1, the differences in this comparative example are as follows, while the rest are the same: Instead of using an XRF spectrometer, the traditional method for determining the mass content of gold was used directly.

[0100] Relevant experimental and effect data: The time, repeatability, and accuracy of the maintenance methods for the sulfite cyanide-free electroplating gold solution in Examples 1 to 3 and Comparative Examples 1 to 2 were statistically analyzed, and the results are shown in Table 1.

[0101]

[0102] As shown in Table 1, the maintenance method for cyanide-free sulfite electroplating gold solution provided in this application embodiment ensures component stability through a closed-loop control process: a dedicated supplement agent to guarantee component stability, accurate detection to capture concentration changes, quantitative calculation to match actual consumption, and step-by-step replenishment to avoid process interference. This systematically solves the four major pain points of traditional maintenance methods: easy loss of replenished components, inaccurate detection data, mismatched replenishment amounts, and easy interference during the mixing process. Ultimately, it achieves long-term stability of the gold and sulfite content in the cyanide-free sulfite electroplating gold solution, ensuring the continuity of the electroplating process and the consistency of product quality.

[0103] In addition, compared with Example 1, Comparative Example 1 uses a traditional manual measurement method, and the maintenance method takes 40 to 50 minutes. Therefore, compared with Comparative Example 1, the maintenance method of Example 1 is twice as efficient. Moreover, compared with traditional manual analysis, the maintenance method provided by this application has high repeatability and accuracy, and the analysis results are highly consistent with traditional manual analysis.

[0104] In summary, the present application provides a maintenance method for a cyanide-free sulfite electroplating gold solution. This method employs four core logics: targeted supplement design, precise dual-component detection, quantitative on-demand replenishment, and step-by-step safe replenishment. From four dimensions—the effectiveness of the supplement, the accuracy of detection, the suitability of replenishment, and the safety of mixing—it systematically suppresses the concentration fluctuations of gold and sulfite in the cyanide-free sulfite electroplating gold solution, ultimately achieving long-term stability of their mass content.

[0105] In addition, the embodiment of this application provides a maintenance method for a cyanide-free sulfite electroplating gold solution. The gold supplement and sulfite supplement prepared by this maintenance method can exist stably for a long time, and the mass content of the gold supplement and sulfite supplement can meet the real-time replenishment needs. The addition method is simple, does not require a secondary complexation reaction, and does not pose a risk of affecting the cyanide-free sulfite electroplating gold solution in the electroplating tank 1. No production stoppage or replenishment is required.

[0106] Furthermore, this application provides an intelligent control device for a cyanide-free sulfite electroplating gold solution. This intelligent control device can control the mass content of gold and sulfite in the cyanide-free sulfite electroplating gold solution in the electroplating tank 1 within ±3%. Based on the process characteristics of the maintenance method and the set standard mass content range, it has a small impact on the control of process parameters in the production process and the performance fluctuation of the cyanide-free sulfite electroplating gold solution, thereby effectively controlling the consistency of the gold plating layer quality in batch production.

[0107] Furthermore, this application provides an intelligent control device for cyanide-free sulfite electroplating gold solution. This intelligent control device has high precision and reliability. By setting the test time, it can complete the cycle of analysis, measurement, and addition of cyanide-free sulfite electroplating gold solution in electroplating tank 1 every 2 hours. Compared with the traditional manual measurement and replenishment method, the overall analysis frequency is higher. Moreover, the prepared gold supplement and sulfite supplement can adapt to the automatic addition needs of the intelligent control device, ensuring the stability of the quality content of cyanide-free sulfite electroplating gold solution. It is suitable for the needs of producing batch gold plating layers in automated production lines and can realize high-precision digital control of the production process parameters of the gold plating layer and the state of the cyanide-free sulfite electroplating gold solution.

[0108] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed in this application.

Claims

1. A method for maintaining a sulfite-based cyanide-free gold plating solution, characterized in that, The maintenance method includes: The first sulfite solution, the first auxiliary complexing agent, and the chloroaurate solution are mixed to obtain the gold supplement; The second sulfite solution and the second auxiliary complexing agent are mixed to obtain a sulfite supplement; A sample of the cyanide-free gold plating solution in the electroplating tank was taken to obtain the cyanide-free gold plating solution to be tested. The first mass content of gold was obtained by X-ray fluorescence analysis of the cyanide-free electroplating gold solution to be tested. The cyanide-free electroplating gold solution to be tested after X-ray fluorescence analysis was subjected to potentiometric titration analysis using hydrochloric acid and sodium thiosulfate standard solutions to obtain the second mass content of sulfite. The first amount of gold supplement and the second amount of sulfite supplement are determined based on the first mass content of gold and the second mass content of sulfite. The gold supplement and the sulfite supplement are added to the sulfite-free cyanide electroplating gold solution according to the first addition amount and the second addition amount, respectively, to complete the maintenance of the sulfite-free cyanide electroplating gold solution.

2. The maintenance method according to claim 1, characterized in that, The gold supplement comprises a first gold component, a first sulfite component, and a first stabilizer component; the mass m1 of the first gold component and the volume V1 of the gold supplement satisfy: m1:V1 = (40 to 50):1, the mass m2 of the first sulfite component and the volume V1 of the gold supplement satisfy: m2:V1 = (200 to 300):1, the mass m3 of the first stabilizer component and the volume V1 of the gold supplement satisfy: m3:V1 = (15 to 30):1, and if the units of m1, m2, and m3 are g, then the unit of V1 is L.

3. The maintenance method according to claim 1, characterized in that, The second sulfite solution includes a second sulfite component and a second stabilizer component; the mass m4 of the second sulfite component and the volume V2 of the second sulfite solution satisfy: m4:V2 = (200 to 260):1, the mass m5 of the second stabilizer component and the volume V2 of the second sulfite solution satisfy: m5:V2 = (15 to 30):1, if the units of m4 and m5 are g, then the unit of V1 is L.

4. The maintenance method according to claim 1, characterized in that, The sulfite-based cyanide-free electroplating gold solution comprises a second gold component and a third sulfite component. The standard mass m6 of the second gold component and the volume V3 of the sulfite-based cyanide-free electroplating gold solution satisfy the following condition: m6:V3 = (0.1 to 20.0):

1. The standard mass m7 of the third sulfite component and the volume V3 of the sulfite-based cyanide-free electroplating gold solution satisfy the following condition: m7:V3 = (100 to 200):

1. If the units of m1 and m2 are g, then the unit of V3 is L.

5. The maintenance method according to claim 1, characterized in that, The types of the first auxiliary complexing agent and the second auxiliary complexing agent include: nitrogen-containing organic complexing agents and / or polycarboxylate salts; The mass m8 of the first auxiliary complexing agent is equal to the volume V1 of the gold supplement, satisfying: m8:V1 = (8 to 12):

1. If the unit of m8 is g, then the unit of V1 is L. The mass m9 of the second auxiliary complexing agent is equal to the volume V2 of the second sulfite solution, satisfying: m9:V2 = (8 to 12):

1. If the unit of m9 is g, then the unit of V2 is L.

6. The maintenance method according to claim 1, characterized in that, The preparation steps of the chloroaurate solution include: Gold was pretreated with aqua regia to obtain a gold-containing solution; The gold-containing solution is heated and concentrated to remove nitrogen dioxide, yielding gold trichloride. The gold trichloride was sequentially cooled and prepared into a solution to obtain a gold-containing solution. The pH of the gold-containing solution was adjusted to obtain a chloroaurate solution.

7. The maintenance method according to claim 6, characterized in that, The heating and concentration temperature is 70°C to 100°C; and / or The target pH value for pH adjustment is 8 to 10, and the temperature for pH adjustment is less than 25°C.

8. The maintenance method according to claim 1, characterized in that, The preparation methods of the first sulfite solution and the second sulfite solution respectively include the following steps: Sulfite is dissolved in distilled water at a preset temperature to obtain a first sulfite solution or a second sulfite solution; wherein the preset temperature is 50°C to 60°C.

9. An intelligent control device for a sulfite-based cyanide-free gold plating solution, characterized in that, The intelligent control device is adapted to the maintenance method according to any one of claims 1 to 8, and is used to analyze and maintain the sulfite-free gold plating solution in the electroplating tank. The intelligent control device includes: The sampling unit includes a filtration and defoaming device, a sampling tube, a sampling pump, and a sampling solenoid valve. The sampling solenoid valve is located at the inlet of the sampling tube, the inlet of the sampling tube is connected to the outlet of the electroplating tank, the outlet of the sampling tube is connected to the inlet of the sampling pump, and the outlet of the sampling pump is connected to the inlet of the filtration and defoaming device. The analysis unit includes a flow-through titration stirring cup, a stirring motor, a syringe pump, an X-ray fluorescence spectrometer, a redox potential composite electrode, and a wastewater tank. The inlet of the flow-through titration stirring cup is connected to the outlet of the filtration and defoaming device. The power output of the stirring motor is connected to the rotating end of the flow-through titration stirring cup. The X-ray fluorescence spectrometer is used to determine the mass content of gold in the cyanide-free gold plating solution to be tested in the flow-through titration stirring cup. The outlet of the syringe pump is connected to the inlet of the flow-through titration stirring cup and is used to introduce hydrochloric acid and sodium thiosulfate standard solution into the flow-through titration stirring cup. The redox potential composite electrode is used to determine the mass content of sulfite in the cyanide-free gold plating solution to be tested in the flow-through titration stirring cup. The outlet of the flow-through titration stirring cup is connected to the inlet of the wastewater tank. The dosing unit includes a gold supplement storage device and a sulfite supplement storage device. The outlet of the gold supplement storage device is connected to the gold supplement inlet of the electroplating tank, and the outlet of the sulfite supplement storage device is connected to the sulfite supplement inlet of the electroplating tank. The display unit is connected to the X-ray fluorescence spectrometer and the redox potential composite electrode via electrical signals. The control unit includes a PLC controller, a gold supplement metering pump, and a sulfite supplement metering pump. The gold supplement metering pump is located at the outlet of the gold supplement storage device, and the sulfite supplement metering pump is located at the outlet of the sulfite supplement storage device. The PLC controller is connected to the sampling solenoid valve, the gold supplement metering pump, and the sulfite supplement metering pump via electrical signals.

10. The intelligent control device according to claim 9, characterized in that, Both the gold supplement storage device and the sulfite supplement storage device include a storage tank, an electric heating element, a temperature sensor, and a level gauge. The outlet of the storage tank is the outlet of either the gold supplement storage device or the sulfite supplement storage device. The electric heating element and the temperature sensor are located inside the storage tank. The level gauge is located inside the storage tank and is used to measure the liquid level inside the storage tank. The heating element, the temperature sensor, and the level gauge are all connected to the PLC controller via electrical signals.

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