Cyanide-free alkaline copper bottoming plating solution and manufacturing method thereof

Abstract

The invention discloses a cyanide-free alkaline copper bottoming plating solution and a manufacturing method thereof, and relates to the technical field of plating solution production. Comprising the following components in parts by weight: 70-80 parts of deionized water, 8-12 parts of copper sulfate pentahydrate, 32-50 parts of HEDP, 30-60 parts of anhydrous potassium carbonate, 40-60 parts of a potassium hydroxide solution, 0.5-2 parts of a leveling agent, 0.5-1.5 parts of a modified preservative and 0.3-1.5 parts of a brightener. According to the cyanide-free formula, the environment-friendly requirement is met, the pollution to the environment is reduced, the environmental risk caused by using highly toxic cyanide is avoided, and the environment-friendly effect is achieved. Meanwhile, wastewater treatment difficulty and cost are reduced, sustainable production is facilitated, the modified preservative effectively inhibits growth of mould, the plating solution is prevented from mildewing and going bad, and the service cycle of the plating solution is prolonged. According to the special preparation method, all the components have a synergistic effect, the coating binding force is not affected while corrosion prevention is achieved, stable coating quality is guaranteed, and production continuity and stability are guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of plating solution production, and in particular to a cyanide-free alkaline copper base plating solution and a manufacturing method thereof. Background Art

[0002] With the development of modern industry, metal electroplating technology has been widely used in many fields, such as electronics, automobiles, decoration and other industries. In the electroplating process, the base plating solution plays a vital role. It provides a good adhesion foundation for the subsequent plating layer and directly affects the overall quality of the plating layer.

[0003] Traditional cyanide copper plating primer bath has been widely used for a long time because of its good coating adhesion and covering ability. However, cyanide is highly toxic and poses a serious threat to the health of operators during the use of the bath. At the same time, its wastewater treatment is extremely difficult and the treatment cost is high, which causes serious pollution to the environment. In the research and development of cyanide-free alkaline copper primer bath, there are many challenges. On the one hand, it is necessary to ensure that the coating can achieve the same or even better quality as traditional cyanide copper plating, including good adhesion, brightness, hardness, wear resistance and corrosion resistance. Many existing cyanide-free plating baths are difficult to fully meet these requirements in terms of coating performance. For example, the coating may have problems such as insufficient adhesion, rough surface, and poor brightness. In addition, the anti-corrosion problem of the plating bath during use cannot be ignored. The growth of microorganisms such as mold can cause the plating bath to deteriorate and affect the quality of the coating. Traditional preservatives sometimes have an adverse effect on the adhesion of the coating. Therefore, the development of modified preservatives that can effectively prevent corrosion without affecting the performance of the coating has become one of the research focuses. Summary of the invention

[0004] In view of the shortcomings of the prior art, the technical solution adopted by the present invention to solve the technical problems is: a cyanide-free alkaline copper primer plating solution, comprising the following weight components: 70-80 parts of deionized water; 8-12 parts of copper sulfate pentahydrate; 32-50 parts of hydroxyethylidene diphosphonic acid; 30-60 parts of anhydrous potassium carbonate; 40-60 parts of potassium hydroxide solution; 0.5-2 parts of a leveling agent; 0.5-1.5 parts of a modified preservative; 0.3-1.5 parts of a brightener; Deionized water removes various ionic impurities in the water to prevent these impurities from mixing into the plating solution and affecting the quality of the coating; copper sulfate pentahydrate is the main source of copper ions in the plating solution, and the stability of the copper ion supply affects the crystal structure and performance of the coating. A stable copper ion concentration helps to form a dense and smooth coating, thereby improving the brightness, bonding strength and other properties of the coating, giving the coating a good appearance and physical and chemical properties; HEDP, as a chelating agent, forms a stable complex with copper ions, which can control the release rate and activity of copper ions, making the coating crystallization more delicate and uniform, avoiding the rough coating caused by the excessive deposition of copper ions, and helping to maintain the stability of the plating solution; anhydrous potassium carbonate plays a role in buffering the pH value in the plating solution, helping to maintain the overall chemical stability of the plating solution, and synergizing with other components to prevent precipitation or other instability in the plating solution, ensuring that the plating solution maintains good performance during long-term use; Potassium hydroxide solution is used to accurately adjust the pH value of the plating solution, providing a suitable alkaline environment for the plating solution, which is conducive to the stable existence and reaction of metal ions. Under alkaline conditions, the components in the plating solution can play a better role and promote the formation of the coating. The leveling agent inhibits the deposition rate of metal ions, so that the coating can be more evenly distributed during the growth process, reducing surface protrusions and depressions, thereby obtaining a smoother and smoother coating surface and avoiding the phenomenon of local coating being too thick or too thin; effectively inhibiting the growth and reproduction of microorganisms such as mold in the plating solution to prevent the plating solution from moldy and deteriorating. Compared with ordinary preservatives, the modified preservatives pay more attention to the effect on the bonding force of the coating while inhibiting the growth of microorganisms; brighteners help to refine the crystal particles of the coating and make the coating structure more compact. The refined crystal structure can not only improve the brightness of the coating, but also enhance the physical properties of the coating, such as hardness, wear resistance and corrosion resistance.

[0005] Wherein, the specific preparation method of the modified preservative is as follows: Step A1: adding ethanol to a reaction kettle, starting stirring, and then adding benzotriazole to the reaction kettle under the monitoring of a mixing monitoring system, stirring to obtain a stirring liquid; Step A2: Add methylbenzotriazole into the reaction kettle, raise the temperature to 45 degrees at a uniform rate over ten minutes, and continue stirring for 20-30 minutes to dissolve the methylbenzotriazole and mix it with the stirring liquid to obtain a premixed liquid; Step A3: adding 2-mercaptobenzothiazole into a reaction kettle and stirring the mixture to mix the 2-mercaptobenzothiazole with the premixed solution to obtain a mixed solution; Step A4: Add a surfactant, a sustained-release enhancer and an antioxidant to the mixed solution and stir. After mixing, cool to room temperature and filter the reaction solution through a filter to obtain a modified preservative.

[0006] The present invention is further configured as follows: the amount of benzotriazole in step A1 is 8%-14% of the mass of ethanol, the amount of methylbenzotriazole is 6%-10% of the mass of ethanol, and the amount of 2-mercaptobenzothiazole is 5%-8% of the mass of ethanol. Benzotriazole is a corrosion inhibitor for metal corrosion protection. In the plating solution, it can form a protective film on the copper surface to prevent copper from being oxidized, and it will not make the coating brittle. Because it does not interfere with the normal arrangement of copper atoms during the deposition process, it will not introduce impurities or defects that cause the coating to become brittle. Toluene triazole has a good corrosion inhibition effect on copper and its alloys, and inhibits corrosion reactions by forming a chemical adsorption film on the copper surface. It will not change the internal organizational structure and stress state of the coating. 2-mercaptobenzothiazole, the sulfur and nitrogen atoms in its molecules can be chemically adsorbed with the copper surface to form a stable protective film, which can effectively isolate air and other corrosive media, it will not change the crystallization process and internal structure of the coating, and will not introduce factors that make the coating brittle.

[0007] The present invention is further configured as follows: in the step A4, the surfactant is sodium dodecylbenzene sulfonate, and the amount is 2%-3% of the mass of ethanol; the slow-release synergist is sodium molybdate, and the amount is 0.5%-1.5% of the mass of ethanol; the antioxidant is tert-butylhydroquinone, and the amount is 0.5%-1.5% of the mass of ethanol; the antioxidant is tert-butylhydroquinone, and the amount is 0.5%-1.5% of the mass of ethanol. Sodium molybdate forms molybdate ions in the solution, and these ions can be adsorbed on the metal surface, react with metal ions, and form a complex protective film. This protective film has good barrier properties, can prevent corrosive substances from approaching the metal surface, and tert-butylhydroquinone is oxidized by itself, thereby protecting the metal and the effective ingredients of the preservative. Its antioxidant effect is mainly based on its phenolic hydroxyl (-OH) structure, which can provide hydrogen atoms to neutralize free radicals and prevent the oxidation chain reaction from proceeding. When used together with modified preservatives, it prolongs the effective action time of the preservatives, ensuring effective protection of the coating for a longer period of time.

[0008] The present invention is further configured that the stirring time in step A1 is 10-15 minutes and the stirring temperature is 26°C; the stirring time in step A3 is 30-50 minutes and the stirring temperature is 50-60°C; the stirring time in step A4 is 15-20 minutes The present invention is further configured to include the following steps: Step S1: add 10 g of copper sulfate pentahydrate into 60 ml of deionized water, stir and dissolve, and after complete dissolution, transfer the solution into a 100 ml volumetric flask, rinse the beaker with deionized water 2-3 times, pour the rinse solution into the volumetric flask, and then dilute to 100 ml to obtain solution U1; Step S2: weigh 42 g of hydroxyethylidene diphosphonic acid and put it into a reaction kettle with a stirring device, then take 700 ml of deionized water, pour it into the reaction kettle, turn on the stirrer to stir until the hydroxyethylidene diphosphonic acid is dissolved, and obtain solution U2; Step S3: weighing 2 g of a leveling agent, 1.5 g of a modified preservative and 1.5 g of a brightener, respectively, and placing them in three beakers of the same specifications, and adding 10 ml of deionized water for stirring and mixing, to prepare a leveling agent solution, a preservative solution and a brightener solution, respectively; Step S4: Pour solution U1 into a reactor containing solution U2 for mixing. After the mixing is completed, add potassium hydroxide solution dropwise for secondary mixing until the pH value is adjusted to 8 to obtain a reaction solution. Step S5: adding 30 g of anhydrous potassium carbonate to the reaction solution, stirring and mixing, and after the mixing is completed, adding potassium hydroxide solution dropwise again to mix until the pH value is adjusted to 11, thereby preparing a preliminary plating solution; Step S6: adding the leveling agent solution, preservative solution and brightener solution prepared in step S3 to the preliminary plating solution in sequence and stirring and mixing them; after the mixing is completed, the plating solution is fixed to 1 L with deionized water to prepare a cyanide-free alkaline copper primer plating solution.

[0009] The present invention is further configured that, in step A1, the specific monitoring method of the hybrid monitoring system is as follows: Step b1: Acquire solution concentration data through a solution acquisition module, install a temperature sensor, a flow sensor and a stirring speed sensor in the reactor, and record them through a data acquisition card to acquire solution mixing data; Step b2: input the data obtained from step b1 into the data processing module, establish a multivariate linear regression model, and output the solution mixing effect data; Step b3: formulate an implementation plan based on the solution mixing effect data. If the solution mixing effect data is lower than the preset data in the storage module, start the feedback adjustment mechanism to adjust the stirring speed and duration until the solution mixing effect data is higher than the preset data and the mixing is completed.

[0010] The present invention is further configured such that the solution mixing data includes: the temperature of the solution in the reactor, the flow rate of the solution and the stirring speed of the stirrer.

[0011] The present invention is further configured that the step of establishing the multivariate linear regression model in step b2 is to collect the initial volume, temperature, stirring speed, mass of each solute, dissolution time and corresponding mixing uniformity index data of ethanol through various sensors and solution collection modules in the reactor, and determine the independent variable and the dependent variable; assume that there is a linear relationship between the dependent variable and the independent variable, and express it with a linear equation, and assume that the random error term obeys a specific normal distribution, and use the least squares method to estimate the regression coefficient using the collected data; perform a goodness of fit test, a significance test and a residual analysis to judge the rationality of the model, and optimize the model according to the test results. The calculation formula of the multivariate linear regression model is as follows:

[0012] Said is the initial volume of ethanol, is the temperature, S is the stirring speed, and the masses of benzotriazole, methylbenzotriazole, and 2-mercaptobenzothiazole are , and The dissolution time is , and , define the mixing uniformity index as M, and its value range is 0-1, M=0 means completely unmixed, and M=1 means completely mixed.

[0013] The present invention is further configured that, in step b3, the specific operation steps of executing the scheme are: Step c1: presetting a critical value for the solution mixing to reach an ideal state from the storage module; Step c2: receiving solution mixing effect data from the data processing module based on the multivariate linear regression model, and comparing the received solution mixing effect data with preset data; Step c3: If the solution mixing effect data is greater than or equal to the preset data, it is determined that the solution has been mixed, and a "yes" result is output. The next step can be continued according to the normal process flow; if the solution mixing effect data is less than the preset data, it is determined that the solution has not been mixed, and a "no" result is output. The feedback adjustment mechanism is started to adjust the stirring speed and duration parameters so that they can eventually reach or exceed the preset data.

[0014] The beneficial effects of the present invention are as follows: 1. The present invention makes the coating have good brightness, bonding strength, hardness, wear resistance and corrosion resistance through the synergistic effect of various components in the plating solution. Copper sulfate pentahydrate provides a stable copper ion source, which helps to form a dense and flat coating; HEDP controls the release of copper ions and refines the crystallization; the leveling agent improves the flatness; the brightener refines the crystal structure, which together improves the appearance and performance of the coating.

[0015] 2. The present invention maintains the stability of the plating solution by arranging the complexation of HEDP and copper ions; anhydrous potassium carbonate buffers the pH value and cooperates with other components to prevent unstable phenomena such as precipitation. The stable plating solution performance ensures the consistency of the coating quality, extends the service life of the plating solution, reduces the coating quality problems and the cost of replacing the plating solution caused by the instability of the plating solution, and the potassium hydroxide solution accurately adjusts the pH value to provide a suitable alkaline environment, which is conducive to the stable existence and reaction of metal ions, ensures the normal chemical reaction in the plating solution, affects the crystallization process of the coating, and plays an important role in the quality indicators such as the bonding strength and brightness of the coating.

[0016] 3. The present invention meets environmental protection requirements through a cyanide-free formula, reduces environmental pollution, avoids environmental risks caused by the use of highly toxic cyanide, and reduces the difficulty and cost of wastewater treatment, which is conducive to sustainable production. The modified preservative effectively inhibits mold growth, prevents the plating solution from mold and deterioration, and extends the plating solution life cycle. Its special preparation method enables the various components to work synergistically, while preventing corrosion without affecting the bonding strength of the coating, ensuring stable coating quality, and ensuring production continuity and stability.

[0017] 4. The present invention ensures that the composition of the plating solution is uniform and accurate, and improves production efficiency and product quality consistency by setting detailed plating solution preparation steps, dissolution of each component, mixing order and conditions, etc. For example, different reagents are added at different pH value stages to ensure that the reaction is fully carried out. The mixing detection system calculates the mixing uniformity through a multivariate linear regression model, monitors the solution mixing process in real time, and can promptly detect mixing problems and issue an alarm. Operators can adjust the process parameters accordingly to ensure uniform solution mixing, improve the stability of plating solution quality, and reduce coating defects caused by uneven mixing. DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with specific embodiments. The embodiments of the present invention are provided for the purpose of illustration and description, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and to enable those of ordinary skill in the art to understand the present invention and thereby design various embodiments with various modifications suitable for specific uses. Example

[0019] Deionized water, copper sulfate pentahydrate, HEDP, anhydrous potassium carbonate, potassium hydroxide solution, leveling agent, modified preservative, brightener, and aluminum sheet as a metal test piece were prepared.

[0020] Preparation of modified preservatives: Experimental Group 1 Step A1: Add ethanol to a reactor, start stirring, and then add 8% benzotriazole by weight of ethanol to the reactor under the monitoring of a mixing monitoring system, and stir at room temperature of 26° C. for 10 minutes until the benzotriazole is dissolved to obtain a stirring liquid; Step A2: 6% methylbenzotriazole by weight of ethanol is added into the reaction kettle, the temperature is slowly raised to 40° C., and stirring is continued for 20 minutes to dissolve the methylbenzotriazole and mix with the stirring liquid to obtain a premixed liquid; Step A3: adding 2-mercaptobenzothiazole in an amount of 5% by mass of ethanol into a reaction kettle, stirring at 50° C. for 30 minutes to allow the 2-mercaptobenzothiazole to be mixed with the premixed solution to obtain a mixed solution; Step A4: Add 2% by weight of ethanol of a surfactant, 0.5% by weight of ethanol of a sustained-release enhancer and 0.5% by weight of ethanol of an antioxidant to the mixed solution, stir for 15 minutes to disperse the surfactant in the mixed solution, and after the reaction is completed, cool to room temperature, filter the reaction solution to remove impurities, and obtain a modified preservative.

[0021] Experimental Group 2 Step A1: Add ethanol to a reactor, start stirring, and then add 14% benzotriazole by weight of ethanol to the reactor under the monitoring of a mixing monitoring system, and stir at room temperature of 26° C. for 15 minutes until the benzotriazole is dissolved to obtain a stirring liquid; Step A2: 10% methylbenzotriazole by weight of ethanol is added into the reaction kettle, the temperature is slowly raised to 50° C., and stirring is continued for 30 minutes to dissolve the methylbenzotriazole and mix with the stirring liquid to obtain a premixed liquid; Step A3: adding 2-mercaptobenzothiazole in an amount of 8% by mass of ethanol into a reaction kettle, stirring at 60° C. for 50 minutes to allow the 2-mercaptobenzothiazole to be mixed with the premixed solution to obtain a mixed solution; Step A4: Add 3% of the mass of ethanol to the mixed solution, 1.5% of the mass of ethanol to the sustained-release enhancer and 1.5% of the mass of ethanol to the antioxidant, stir for 20 minutes to disperse the surfactant in the mixed solution, and after the reaction is completed, cool to room temperature, filter the reaction solution to remove impurities, and obtain a modified preservative.

[0022] Preparation of cyanide-free alkaline copper base plating solution: Experimental group B1 Step S1: add 10 g of copper sulfate pentahydrate into 60 ml of deionized water, stir and dissolve, and after complete dissolution, transfer the solution into a 100 ml volumetric flask, rinse the beaker 2-3 times with a small amount of deionized water, pour the rinse solution into the volumetric flask, and then dilute to 100 ml to obtain solution U1; Step S2: Weigh 42 g of HEDP and put it into a reaction kettle with a stirring device, take 700 ml of deionized water, pour it into the reaction kettle, turn on the stirrer to stir until the HEDP is dissolved, and obtain solution U2; Step S3: 2 g of a leveling agent, 1.5 g of the modified preservative in Experimental Group 1, and 1.5 g of a brightener were weighed and placed in different beakers, and 10 ml of deionized water was added and stirred to prepare a leveling agent solution, a preservative solution, and a brightener solution; Step S4: Pour the U1 solution into the reaction kettle containing the U2 solution for mixing. After the mixing is completed, add a potassium hydroxide solution dropwise for mixing until a predetermined pH value is reached to obtain a reaction solution. Step S5: adding 30 g of anhydrous potassium carbonate to the reaction solution, stirring and mixing, and after the mixing is completed, adding potassium hydroxide solution dropwise again to mix until a predetermined pH value is reached to prepare a preliminary plating solution; Step S6: adding the dissolved leveling agent solution, preservative solution and brightener solution to the preliminary plating solution in sequence and stirring and mixing them; after the mixing is completed, the plating solution is fixed to 1 L with deionized water to prepare a cyanide-free alkaline copper primer plating solution.

[0023] Experimental group B2 Step S1: add 12 g of copper sulfate pentahydrate into 60 ml of deionized water, stir and dissolve, and after complete dissolution, transfer the solution into a 100 ml volumetric flask, rinse the beaker 2-3 times with a small amount of deionized water, pour the rinse solution into the volumetric flask, and then dilute to 100 ml to obtain solution U1; Step S2: weigh 50 g of HEDP and put it into a reactor with a stirring device, take 700 ml of deionized water, pour it into the reactor, turn on the stirrer to stir until the HEDP is dissolved, and obtain solution U2; Step S3: weighing 2 g of a leveling agent, 1.5 g of a modified preservative and 1.5 g of a brightener into different beakers, respectively, and adding 10 ml of deionized water to stir and mix, thereby preparing a leveling agent solution, a preservative solution and a brightener solution; Step S4: Pour the U1 solution into the reaction kettle containing the U2 solution for mixing. After the mixing is completed, add a potassium hydroxide solution dropwise for mixing until a predetermined pH value is reached to obtain a reaction solution. Step S5: adding 60 g of anhydrous potassium carbonate to the reaction solution, stirring and mixing, and after the mixing is completed, adding potassium hydroxide solution dropwise again to mix until a predetermined pH value is reached to prepare a preliminary plating solution; Step S6: adding the dissolved leveling agent solution, preservative solution and brightener solution to the preliminary plating solution in sequence and stirring and mixing them; after the mixing is completed, the plating solution is fixed to 1 L with deionized water to prepare a cyanide-free alkaline copper primer plating solution.

[0024] Control group Step 1: Weigh 5g of copper sulfate and place it in a 250ml beaker. Use a measuring cylinder to measure 80ml of deionized water and slowly add it to the beaker while stirring with a glass rod until the copper sulfate is completely dissolved to obtain a copper sulfate solution. Step 2: Weigh 30 g of disodium ethylenediaminetetraacetate and 20 g of sodium citrate, put them into a 500 ml beaker, add 150 ml of deionized water, turn on the magnetic stirrer, and stir until the reagents are completely dissolved to obtain a complexing agent solution; Step 3: slowly pour the copper sulfate solution into the complexing agent solution, stirring while pouring to make the solution evenly mixed, and adjust the pH value of the mixed solution to between 9 and 10 with sodium hydroxide solution. During the pH adjustment process, slowly add the sodium hydroxide solution dropwise and stir continuously; Step 4: Add 5 g of sodium carbonate and continue stirring until the sodium carbonate is completely dissolved. Add deionized water to the solution to make it 1 L and stir evenly. Step 5: Filter the prepared plating solution through filter paper to remove possible insoluble impurities to obtain a traditional cyanide-free alkaline copper primer plating solution.

[0025] Several aluminum sheets of 5cm×5cm×0.5mm were taken and numbered respectively. After pretreatment such as degreasing and zinc immersion, the aluminum sheets were immersed in the plating solutions prepared by the experimental group B1, experimental group B2 and control group respectively, and electroplated at a current density of 0.5A / dm², a temperature of 26℃ and an electroplating time of 30 minutes to obtain aluminum-plated sheet samples with a coating thickness of approximately 5μm. Wipe the surface of the aluminum-plated sheet sample clean to remove dust and impurities on the surface, and use a gloss meter to measure the glossiness of the metal coating surface; according to the cross-hatch method, place a crosshatch knife perpendicular to the sample surface, and scratch horizontally and vertically at a uniform speed and pressure. The depth of the cross-hatch is to the aluminum base metal, and 3M tape is pasted on the cross-hatch area, and then the tape is quickly torn off at a 90° angle to the sample surface. Observe the shedding of the coating, and evaluate the bonding strength based on the shedding area. If the shedding area is less than 5%, the bonding strength is excellent, 5%-15% is good, 15%-30% is fair, and more than 30% is poor; Using a microhardness tester, select at least 5 different positions on the sample surface for hardness testing. Load the test force at each position for 15 seconds and then unload it. Read the hardness value displayed by the hardness tester, and finally take the average value as the hardness value of the sample. Use a friction and wear tester to set the test parameters: load 2N, speed 200r / min, friction time 30 minutes, and calculate the wear amount according to the formula: wear amount Δm = m0 - m1. The smaller the wear amount, the better the wear resistance. Through the neutral salt spray test, hang the prepared samples in the salt spray test box to ensure that the samples do not contact each other and the spray can evenly cover the sample surface. Start the salt spray test box, take out the sample after continuous spraying for 24 hours, remove the surface salt spray deposits, and then wipe or blow dry with a soft cloth. Weigh the sample mass m3 again with an electronic balance, and calculate the corrosion weight loss rate according to the formula: corrosion weight loss rate = (m2-m3) / m2×100%. The smaller the corrosion weight loss rate, the better the corrosion resistance.

[0026] Compared with the control group without modified preservatives, the anti-rust effect of adding modified preservatives is significantly improved, and the service life of the plating solution is extended. Its special preparation method enables the various components to work synergistically, and does not affect the bonding strength of the coating while preventing corrosion, ensuring the stability of the coating quality. This proves that modified organic preservatives play an important role in anti-corrosion performance, refer to Table 1; From the results of the comprehensive embodiment, it can be seen that when the weight of copper sulfate pentahydrate is 10g, the weight of HEDP is 42g, the weight of anhydrous potassium carbonate is 30g, the leveling agent is 2g, the modified preservative is 1.5g and the brightener is 1.5g, the cyanide-free alkaline copper primer plating solution prepared at a pH value of 11 has the best comprehensive performance in brightness, bonding strength, hardness, wear resistance and corrosion resistance.

[0027] Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without creative work should fall within the scope of protection of the present invention. The structures, devices and operating methods not specifically described and explained in the present invention are implemented according to the conventional means in the field unless otherwise specified and limited.

Claims

1. A cyanide-free alkaline copper primer plating solution, characterized in that: The invention comprises the following components by weight: 70-80 parts of deionized water; 8-12 parts of copper sulfate pentahydrate; 32-50 parts of hydroxyethylidene diphosphonic acid; 30-60 parts of anhydrous potassium carbonate; 40-60 parts of potassium hydroxide solution; 0.5-2 parts of leveling agent; 0.5-1.5 parts of modified preservative; 0.3-1.5 parts of brightener; Wherein, the specific preparation method of the modified preservative is as follows: Step A1: adding ethanol to a reaction kettle, starting stirring, and then adding benzotriazole to the reaction kettle under the monitoring of a mixing monitoring system, stirring to obtain a stirring liquid; Step A2: Add methylbenzotriazole into the reaction kettle, raise the temperature to 45 degrees at a uniform rate over ten minutes, and continue stirring for 20-30 minutes to dissolve the methylbenzotriazole and mix it with the stirring liquid to obtain a premixed liquid; Step A3: adding 2-mercaptobenzothiazole into a reaction kettle and stirring the mixture to mix the 2-mercaptobenzothiazole with the premixed solution to obtain a mixed solution; Step A4: Add a surfactant, a sustained-release enhancer and an antioxidant to the mixed solution and stir. After mixing, cool to room temperature and filter the reaction solution through a filter to obtain a modified preservative.

2. A cyanide-free alkaline copper primer plating solution according to claim 1, characterized in that: The amount of benzotriazole in step A1 is 8%-14% of the mass of ethanol, the amount of methylbenzotriazole is 6%-10% of the mass of ethanol, and the amount of 2-mercaptobenzothiazole is 5%-8% of the mass of ethanol.

3. A cyanide-free alkali copper base plating solution according to claim 1, characterized in that: In the step A4, the surfactant is sodium dodecylbenzene sulfonate, and the amount used is 2%-3% of the mass of ethanol. The sustained-release enhancer is sodium molybdate, and the amount used is 0.5%-1.5% of the mass of ethanol. The antioxidant is tert-butylhydroquinone, and the amount used is 0.5%-1.5% of the mass of ethanol.

4. A cyanide-free alkaline copper base plating solution according to claim 1, characterized in that: The stirring time in step A1 is 10-15 minutes and the stirring temperature is 26° C.; the stirring time in step A3 is 30-50 minutes and the stirring temperature is 50-60° C.; the stirring time in step A4 is 15-20 minutes.

5. A method for manufacturing a cyanide-free alkaline copper primer plating solution, characterized in that: The following steps are involved: Step S1: add 10 g of copper sulfate pentahydrate into 60 ml of deionized water, stir and dissolve, and after complete dissolution, transfer the solution into a 100 ml volumetric flask, rinse the beaker with deionized water 2-3 times, pour the rinse solution into the volumetric flask, and then dilute to 100 ml to obtain solution U1; Step S2: weigh 42 g of hydroxyethylidene diphosphonic acid and put it into a reaction kettle with a stirring device, then take 700 ml of deionized water, pour it into the reaction kettle, turn on the stirrer to stir until the hydroxyethylidene diphosphonic acid is dissolved, and obtain solution U2; Step S3: weighing 2 g of a leveling agent, 1.5 g of a modified preservative and 1.5 g of a brightener, respectively, and placing them in three beakers of the same specifications, and adding 10 ml of deionized water for stirring and mixing, to prepare a leveling agent solution, a preservative solution and a brightener solution, respectively; Step S4: Pour solution U1 into a reactor containing solution U2 for mixing. After the mixing is completed, add potassium hydroxide solution dropwise for secondary mixing until the pH value is adjusted to 8 to obtain a reaction solution. Step S5: adding 30 g of anhydrous potassium carbonate to the reaction solution, stirring and mixing, and after the mixing is completed, adding potassium hydroxide solution dropwise again to mix until the pH value is adjusted to 11, thereby preparing a preliminary plating solution; Step S6: adding the leveling agent solution, preservative solution and brightener solution prepared in step S3 to the preliminary plating solution in sequence and stirring and mixing them; after the mixing is completed, the plating solution is fixed to 1 L with deionized water to prepare a cyanide-free alkaline copper primer plating solution.

6. The cyanide-free alkaline copper base plating solution according to claim 1, characterized in that: In step A1, the specific monitoring method of the hybrid monitoring system is as follows: Step b1: Acquire solution concentration data through a solution acquisition module, install a temperature sensor, a flow sensor and a stirring speed sensor in the reactor, and record them through a data acquisition card to acquire solution mixing data; Step b2: input the data obtained from step b1 into the data processing module, establish a multivariate linear regression model, and output the solution mixing effect data; Step b3: formulate an implementation plan based on the solution mixing effect data. If the solution mixing effect data is lower than the preset data in the storage module, start the feedback adjustment mechanism to adjust the stirring speed and duration until the solution mixing effect data is higher than the preset data and the mixing is completed.

7. The cyanide-free alkaline copper base plating solution according to claim 6, characterized in that: The solution mixing data includes: the temperature of the solution in the reactor, the flow rate of the solution and the stirring speed of the stirrer.

8. The cyanide-free alkaline copper base plating solution according to claim 6, characterized in that: The steps of establishing the multivariate linear regression model in step b2 are: collecting the initial volume of ethanol, temperature, stirring speed, mass of each solute, dissolution time and corresponding mixing uniformity index data through various sensors and solution collection modules in the reactor, and determining the independent variable and the dependent variable; assuming that there is a linear relationship between the dependent variable and the independent variable, expressed by a linear equation, assuming that the random error term obeys a specific normal distribution, and using the least squares method to estimate the regression coefficient using the collected data; performing a goodness of fit test, a significance test and a residual analysis to determine the rationality of the model, and optimizing the model according to the test results. The calculation formula of the multivariate linear regression model is as follows: Said is the initial volume of ethanol, is the temperature, S is the stirring speed, and the masses of benzotriazole, methylbenzotriazole, and 2-mercaptobenzothiazole are , and The dissolution time is , and , define the mixing uniformity index as M, and its value range is 0-1, M=0 means completely unmixed, and M=1 means completely mixed.

9. The cyanide-free alkaline copper base plating solution according to claim 6, characterized in that: In step b3, the specific operation steps of the implementation scheme are: Step c1: presetting a critical value for the solution mixing to reach an ideal state from the storage module; Step c2: receiving solution mixing effect data from the data processing module based on the multivariate linear regression model, and comparing the received solution mixing effect data with preset data; Step c3: If the solution mixing effect data is greater than or equal to the preset data, it is determined that the solution has been mixed well, and a "yes" result is output, and the next step can be continued according to the normal process flow; If the solution mixing effect data is less than the preset data, it is determined that the solution has not been mixed well, and a "no" result is output. The feedback adjustment mechanism is started to adjust the stirring speed and duration parameters so that they can eventually reach or exceed the preset data.

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