阅读说明：本技术 一种应用于印制线路板的镀镍溶液及其电镀镍方法 (Nickel plating solution applied to printed circuit board and nickel electroplating method thereof ) 是由 洪学平 姚吉豪 于 2021-11-17 设计创作，主要内容包括：本发明公开了一种应用于印制线路板的镀镍溶液及其电镀镍方法,包括以下质量浓度的组分：镍盐35-50g/L；导电盐20-40g/L；防老化剂10-15g/L；复合络合剂5-15g/L；反应加速剂50-80mg/L；去应力剂50-80mg/L；界面活性剂5-10mg/L；复合稳定剂0.2-5mg/L；所述复合络合剂包括A组分和B组分,所述A组分与B组分按照质量浓度比例为3:1-2;所述A组分包括质量浓度为1-5g/L的柠檬酸,1-2g/L的乙酸铵,1-5g/L的苹果酸。该发明溶液保证了镀层与基体之间的结合力强度,使得镀镍层具有良好的附着性好,镀层均匀；该工艺不仅保证了电镀的均匀性,而且使得电镀时间更短。(The invention discloses a nickel plating solution applied to a printed circuit board and a nickel electroplating method thereof, wherein the nickel plating solution comprises the following components in mass concentration: 35-50g/L of nickel salt; 20-40g/L of conductive salt; 10-15g/L of anti-aging agent; 5-15g/L of composite complexing agent; reaction accelerator 50-80 mg/L; 50-80mg/L stress remover; 5-10mg/L of surfactant; 0.2-5mg/L of composite stabilizer; the composite complexing agent comprises a component A and a component B, wherein the mass concentration ratio of the component A to the component B is 3:1-2, and the component A comprises citric acid with the mass concentration of 1-5g/L, ammonium acetate with the mass concentration of 1-2g/L and malic acid with the mass concentration of 1-5 g/L. The solution ensures the bonding strength between the plating layer and the substrate, so that the nickel plating layer has good adhesiveness and uniform plating layer; the process not only ensures the uniformity of electroplating, but also shortens the electroplating time.)

1. The nickel plating solution applied to the printed circuit board is characterized by comprising the following components in mass concentration:

nickel salt 35-50g/L

Conductive salt 20-40g/L

Anti-aging agent 10-15g/L

5-15g/L of composite complexing agent

Reaction accelerator 50-80mg/L

Stress relieving agent 50-80mg/L

Surfactant 5-10mg/L

0.2-5mg/L composite stabilizer

The composite complexing agent comprises a component A and a component B, wherein the mass concentration ratio of the component A to the component B is 3:1-2, and the component A comprises citric acid with the mass concentration of 1-5g/L, ammonium acetate with the mass concentration of 1-2g/L and malic acid with the mass concentration of 1-5 g/L;

the component B comprises polyacrylamide, aminocarboxylic acid resin, hyperbranched polyurethane sulfonate and beta-nicotinamide adenine dinucleotide according to the mass concentration ratio of 1:1:2:2, wherein the component A and the component B are uniformly stirred and mixed according to the concentration ratio to form the composite complexing agent;

after the components are uniformly mixed according to the proportion, the pH value of the solution is adjusted to 4.3-4.6, then a pH buffering agent with the mass concentration of 25% is added, and finally the preparation of the nickel plating solution is completed.

2. The nickel plating solution for the printed circuit board according to claim 1, wherein the composite stabilizer is a composite of cerium sulfate and benzotriazole, and the mass concentration ratio of cerium sulfate to benzotriazole is 4: 1.

3. A nickel plating solution applied to a printed circuit board according to claim 1, wherein the mass concentration ratio of the reaction accelerator to the stress remover in use is 1:1, and the stress remover comprises 50-60% of saccharin, 10-30% of 2-mercaptobenzothiazole and 10-30% of 4-methoxybenzothiazole in percentage by mass.

4. A nickel plating solution for printed circuit boards according to claim 1, wherein the anti-aging agent is a ketoamine anti-aging agent.

5. A nickel plating solution for printed circuit boards according to claim 1, wherein the reaction accelerator is a complex of 2, 6-diaminopyridine and 3-pyridinemethanol, and the mass concentration ratio of 2, 6-diaminopyridine to 3-pyridinemethanol is (1-2): 1.

6. A nickel plating solution for printed circuit boards according to claim 1, wherein the nickel salt is nickel sulfate or nickel sulfamate, and the surfactant is sodium methallylsulfonate.

7. A nickel electroplating method of a nickel plating solution applied to a printed circuit board is characterized by comprising the following specific steps,

step 1, bombarding the surface of a plated part by adopting vacuum plasma to remove various pollutants and oxidation layers on the surface of the plated part;

step 2, putting the treated plated piece into a nickel tank with the nickel plating solution of any one of claims 1 to 6 to carry out first-stage nickel electroplating treatment, wherein the specific conditions of the nickel electroplating treatment are that the electroplating temperature is 60 to 75 ℃, and the electroplating density is 2 to 2.5A/dm²The electroplating time is 5-10 minutes, and the thickness of the nickel layer can reach 3-6 mu m;

step 3, performing second-stage nickel electroplating treatment on the plated part after the first-stage nickel electroplating treatment, wherein the specific conditions of the nickel electroplating treatment are that the electroplating temperature is 45-50 ℃, and the electroplating density is 0.7-1.5A/dm²The electroplating time is 10-15 minutes, and the thickness of the nickel layer can reach 2-5 mu m; forming a nickel plating layer after the total thickness of the nickel layer is 5-11 mu m;

step 4, bombarding the surface of the plated part with the nickel plating layer by adopting vacuum plasma again;

and 5, carrying out the next electroplating process on the plated part subjected to the surface treatment.

8. The method for electroplating nickel by using a nickel plating solution for a printed circuit board according to claim 7, wherein the specific conditions of the vacuum plasma bombardment in the step 4 are as follows: the working medium adopted by the vacuum plasma bombardment is a mixed gas of hydrogen and nitrogen, wherein the volume ratio of the hydrogen to the nitrogen is (1-2): 3; the distance of the plasma bombardment is controlled to be 3-5 cm; the treatment temperature is 30-40 ℃; the treatment time is 15-25 s.

9. The method for electroplating nickel by using a nickel plating solution for a printed circuit board according to claim 7, wherein the specific conditions of the vacuum plasma bombardment in the step 1 are as follows: the working medium adopted by the vacuum plasma bombardment is a mixed gas of hydrogen and nitrogen, wherein the volume ratio of the hydrogen to the nitrogen is (1-2): 3, controlling the bombardment distance to be 20-25 mm; the treatment temperature is 90-110 ℃; the treatment time is 15-25 s.

10. The method for electroplating nickel by using a nickel plating solution for a printed circuit board according to claim 7, wherein the nickel plating solution in the step 3 is drained into a nickel plating solution recovery tank after being used; and concentrating the nickel recovery solution in the nickel plating recovery tank, controlling the concentration of the recovered nickel plating solution, and recovering the nickel plating solution into the nickel plating solution tank for recycling.

Technical Field

The invention relates to the technical field of nickel electroplating, in particular to a nickel plating solution applied to a printed circuit board and a nickel electroplating method thereof.

Background

Printed circuit boards (PCB boards), also known as printed circuit boards, are providers of electrical connections for electronic components. Printed circuit boards have evolved from single-layer to double-sided, multi-layer and flex boards, and have continued to evolve toward high precision, high density and high reliability. The size is continuously reduced, the cost is reduced, and the performance is improved, so that the printed circuit board still keeps strong vitality in the development process of future electronic products. The development trend of the production and manufacturing technology of the future printed circuit board is to develop the printed circuit board in the directions of high density, high precision, fine aperture, fine lead, small spacing, high reliability, multilayering, high-speed transmission, light weight and thin type.

Most of the traditional printed circuit boards are made of copper as a base material, but in recent years, more and more printed circuit boards made of aluminum base materials are used, and neither the copper base material nor the aluminum base material can be used as a final material of the printed circuit board. Therefore, in order to protect the base material, nickel is electroplated outside the base material in the industry, so that the effects of protecting the base material chemically and physically, increasing the smoothness and decorating the base material are achieved.

Through the long-term use in the market, the existing electroplated nickel has the following defects: 1) the electroplating temperature is higher, usually between 75 ℃ and 85 ℃, which easily causes the crystal degree and rigidity of the produced plated part to be too high, so that the roughened surface becomes brittle, and further causes almost no binding force between the plating layer and the matrix, and the plating layer is easy to fall off under the high-temperature circulation condition. 2) Because the time in the current nickel electroplating industry is between 30 and 50min, the stability of the nickel electroplating solution is poorer and poorer along with the prolonging of the electroplating time, the discharge deposition effect of metal nickel ions is greatly influenced, the electroplating cannot be normally carried out, and the quality of a plating layer is influenced finally.

Disclosure of Invention

Aiming at the defects in the technology, the invention provides the nickel plating solution applied to the printed circuit board and the nickel electroplating method thereof, and the solution ensures the bonding strength between the plating layer and the substrate, so that the nickel plating layer has good adhesiveness and uniform plating layer; the process not only ensures the uniformity of electroplating, but also shortens the electroplating time.

In order to realize the aim, the invention provides a nickel plating solution applied to a printed circuit board, which comprises the following components in mass concentration:

nickel salt 35-50g/L

Conductive salt 20-40g/L

Anti-aging agent 10-15g/L

5-15g/L of composite complexing agent

Reaction accelerator 50-80mg/L

Stress relieving agent 50-80mg/L

Surfactant 5-10mg/L

0.2-5mg/L composite stabilizer

The composite complexing agent comprises a component A and a component B, wherein the mass concentration ratio of the component A to the component B is 3:1-2, and the component A comprises citric acid with the mass concentration of 1-5g/L, ammonium acetate with the mass concentration of 1-2g/L and malic acid with the mass concentration of 1-5 g/L;

the component B comprises polyacrylamide, aminocarboxylic acid resin, hyperbranched polyurethane sulfonate and beta-nicotinamide adenine dinucleotide according to the mass concentration ratio of 1:1:2:2, wherein the component A and the component B are uniformly stirred and mixed according to the concentration ratio to form the composite complexing agent;

after the components are uniformly mixed according to the proportion, the pH value of the solution is adjusted to 4.3-4.6 by using a pH buffering agent with the mass concentration of 25 percent, and then the preparation of the chemical nickel solution is completed.

The composite stabilizer is a composite of cerium sulfate and benzotriazole, and the mass concentration ratio of the cerium sulfate to the benzotriazole is 4: 1.

The mass concentration ratio of the reaction accelerator to the stress remover in use is 1:1, and the stress remover comprises 50-60% of saccharin, 10-30% of 2-mercaptobenzothiazole and 10-30% of 4-methoxybenzothiazole in percentage by mass.

Wherein the anti-aging agent is a ketoamine anti-aging agent.

Wherein the reaction accelerator is a compound of 2, 6-diaminopyridine and 3-pyridinemethanol, and the mass concentration ratio of the 2, 6-diaminopyridine to the 3-pyridinemethanol is (1-2): 1.

Wherein the nickel salt is nickel sulfate or nickel sulfamate, and the surfactant is sodium methallyl sulfonate.

In order to achieve the above objects, the present invention also provides a nickel electroplating method of a nickel plating solution for a printed wiring board, comprising the following steps,

step 1, bombarding the surface of a plated part by adopting vacuum plasma to remove various pollutants and oxidation layers on the surface of the plated part;

step 2, plating the treated piecePlacing into a nickel tank containing the nickel plating solution, and performing first-stage nickel electroplating treatment at 60-75 deg.C and plating density of 2-2.5A/dm²The electroplating time is 5-10 minutes, and the thickness of the nickel layer can reach 3-6 mu m;

step 3, performing second-stage nickel electroplating treatment on the plated part after the first-stage nickel electroplating treatment, wherein the specific conditions of the nickel electroplating treatment are that the electroplating temperature is 45-50 ℃, and the electroplating density is 0.7-1.5A/dm²The electroplating time is 10-15 minutes, and the thickness of the nickel layer can reach 2-5 mu m; forming a nickel plating layer after the total thickness of the nickel layer is 5-11 mu m;

step 4, bombarding the surface of the plated part with the nickel plating layer by adopting vacuum plasma again;

and 5, carrying out the next electroplating process on the plated part subjected to the surface treatment.

Wherein, the specific conditions of the vacuum plasma bombardment in the step 4 are as follows: the working medium adopted by the vacuum plasma bombardment is a mixed gas of hydrogen and nitrogen, wherein the volume ratio of the hydrogen to the nitrogen is (1-2): 3; the distance of the plasma bombardment is controlled to be 3-5 cm; the treatment temperature is 30-40 ℃; the treatment time is 15-25 s.

Wherein, the specific conditions of the vacuum plasma bombardment in the step 1 are as follows: the working medium adopted by the vacuum plasma bombardment is a mixed gas of hydrogen and nitrogen, wherein the volume ratio of the hydrogen to the nitrogen is (1-2): 3, controlling the bombardment distance to be 20-25 mm; the treatment temperature is 90-110 ℃; the treatment time is 15-25 s.

Draining the nickel plating solution used in the step 3 into a nickel plating solution recovery tank; and concentrating the nickel recovery solution in the nickel plating recovery tank, controlling the concentration of the recovered nickel plating solution, and recovering the nickel plating solution into the nickel plating solution tank for recycling.

The invention has the beneficial effects that: compared with the prior art, the nickel plating solution applied to the printed circuit board and the nickel electroplating method thereof provided by the invention have the following advantages:

1) the reaction accelerator, the composite stabilizer and the composite complexing agent are added on the basis of the original components of the nickel plating solution, the reaction accelerator accelerates the activation reaction speed of the nickel plating solution and reduces the activation time; particularly, on the composite complexing agent, a specially-prepared component A and a component B are adopted, the component A is used as a main complexing agent, and polyacrylamide in the component B has good scale inhibition performance, has a function of adsorbing impurities, and has good colloid characteristics and a dispersing function; but because the complexing capacity is small, the phenomenon of instability is easily caused by the small capacity in the complexing process, and nickel ions can be deposited on the wall of the tank all the time along with the lengthening of the electroplating time, in order to solve the problems, polyacrylamide, amino carboxylic acid resin, hyperbranched polyurethane sulfonate and beta-nicotinamide adenine dinucleotide are used as a part of a complexing agent, and the macromolecular substances have the characteristic of high macromolecular viscosity while being complexed; when electroplating, the composite complexing agent can promote reaction and simultaneously avoid metal ion deposition, so that the bonding strength between the plating layer and the matrix is very stable, the plated part can not fall off even in subsequent high-temperature recycling, and the service life of the plated part is further prolonged.

2) By adopting the components of the scheme, a reaction accelerator, a specially-prepared composite complexing agent of conductive salt and a specially-prepared composite stabilizer are added on the basis of the original components, and the complexing agent of the technology has the stabilizing effect of high molecular viscosity on the basis of the original complexing effect, so that the conductive salt increases the conductive effect, and the complexed metal nickel ions are discharged and deposited on the surface of a cathode to meet the larger resistance of the cathode, thereby generating larger negative polarization, and further greatly improving the dispersion capacity and the covering capacity of the plating solution; the stability of the composite complexing agent and the stability of the composite stabilizer are the same, and the solution can realize perfect electroplating without electroplating at the original high temperature by dual stable use; and the dual stability is favorable for adjusting the plating speed and the plating quality of electroplating, ensures the bonding strength between the plating and the matrix, and simultaneously ensures that the plated part is easy to spread on the surface of the electrode to achieve the purpose of uniform plating, thereby further achieving the effect of filling the wafer packaging micropores without holes and gaps.

3) The invention adopts vacuum plasma to bombard the surface of the plated part before and after electroplating, not only removes various pollutants and oxide layers on the surface of the plated part, but also ensures the surface of the plated part to be compact and smooth after cleaning, has high surface cleaning degree, is beneficial to the tight combination of a plating layer and a base material, and further ensures the bonding strength between the plating layer and the base body.

4) Generally, the plating layer is easy to fall off due to the overhigh temperature during nickel electroplating; when the nickel plating solution is used for electroplating, the treatment is carried out in two electroplating stages; the first stage can be completed in a short time by adopting high temperature and high density of 60-75 ℃ due to the very good stability and complexation property at the beginning of use, and the nickel precipitation speed is very high under the action of the composite complexing agent in the process, so that most of procedures of nickel electroplating can be completed quickly; the stability is reduced along with the progress of electroplating, the temperature and the density are reduced within the time, the electroplating time is prolonged, even under the condition of 45-50 ℃, the dispersion capacity and the covering capacity of the plating solution can ensure that the discharge deposition effect of the metal nickel ions is not influenced due to the action of the composite complexing agent, so that the continuation of electroplating is ensured, and finally the proper thickness of a nickel plating layer is achieved. The technology adopts a two-stage mode of different temperatures and different densities to carry out electroplating, so that the phenomenon that a plating layer is easy to fall off at high temperature is avoided; the bonding strength between the plating layer and the substrate is further ensured, so that the nickel plating layer has good adhesiveness and uniform plating layer; the process not only ensures the uniformity of electroplating, but also shortens the electroplating time.

5) In addition, the technology adopts a mode of different temperatures and different densities for electroplating in two stages; when the thickness of the nickel plating required by the plating layer is between 3 and 6 mu m, the second stage of electroplating can be stopped, so that the same solution can be used for electroplating a thin nickel layer and a thick nickel layer, and the application range of the solution is further enlarged.

Detailed Description

In order to more clearly describe the present invention, the present invention is further described below in terms of words.

The invention provides a nickel plating solution applied to a printed circuit board, which comprises the following components in mass concentration:

nickel salt 35-50g/L

Conductive salt 20-40g/L

Anti-aging agent 10-15g/L

5-15g/L of composite complexing agent

Reaction accelerator 50-80mg/L

Stress relieving agent 50-80mg/L

Surfactant 5-10mg/L

0.2-5mg/L composite stabilizer

The composite complexing agent comprises a component A and a component B, wherein the mass concentration ratio of the component A to the component B is 3:1-2, and the component A comprises citric acid with the mass concentration of 1-5g/L, ammonium acetate with the mass concentration of 1-2g/L and malic acid with the mass concentration of 1-5 g/L;

the component B comprises polyacrylamide, aminocarboxylic acid resin, hyperbranched polyurethane sulfonate and beta-nicotinamide adenine dinucleotide according to the mass concentration ratio of 1:1:2:2, wherein the component A and the component B are uniformly stirred and mixed according to the concentration ratio to form the composite complexing agent;

after the components are uniformly mixed according to the proportion, the pH value of the solution is adjusted to 4.3-4.6 by using a pH buffering agent with the mass concentration of 25 percent, and then the preparation of the chemical nickel solution is completed.

In this embodiment, the composite stabilizer is a composite of cerium sulfate and benzotriazole, and the mass concentration ratio of cerium sulfate to benzotriazole is 4: 1. Benzotriazole is a high molecular stabilizer, is adopted, is matched with cerium sulfate, and has a mass ratio of 4:1, so that the stability of the nickel plating solution is ensured, and simultaneously, metal oxide generated by dissolution in the electroplating process can be prevented from being formed between a matrix and a nickel layer, thereby ensuring the fine crystallization and compactness of the obtained nickel layer; and further improve the binding force between the nickel layer and the substrate.

In the embodiment, the mass concentration ratio of the reaction accelerator to the stress remover in use is 1:1, and the stress remover comprises 50-60% of saccharin, 10-30% of 2-mercaptobenzothiazole and 10-30% of 4-methoxybenzothiazole in percentage by mass. The reaction accelerator is a compound of 2, 6-diaminopyridine and 3-pyridinemethanol, and the mass concentration ratio of the 2, 6-diaminopyridine to the 3-pyridinemethanol is (1-2): 1; the accelerator adopts a composite mode, so that the phenomenon that the operation range of a single reaction accelerator is narrow is avoided; the setting of accurate concentration accelerates the activation reaction speed and reduces the activation time; in addition, the stress remover is composed of saccharin, 2-mercaptobenzothiazole and 4-methoxybenzothiazole, and the stress remover can realize the control of the internal stress of the plating layer; so that the bonding strength between the nickel-plated layer and the base material is better; the composite stress remover is added, so that the effect of reducing or completely eliminating the internal stress of the nickel plating layer is achieved, and the obtained nickel plating layer is fine, uniform and good in brightness effect.

In this embodiment, the specific process for preparing the chemical nickel solution is as follows:

step a, preparing nickel salt, a composite complexing agent, conductive salt, an anti-aging agent, a reaction accelerator, a stress remover, a surfactant and a composite stabilizer according to a mass concentration ratio;

b, pouring the conductive salt, the composite stabilizer, the stress remover, the anti-aging agent and the surfactant into a nickel tank according to the proportion, carrying a stirring pump, stirring after pouring, wherein the stirring speed is 50-100r/min, and adding 1/2 composite complexing agent in the stirring process;

step C, adding a reaction accelerator and nickel salt into the solution C in sequence, stirring at a stirring speed of between 100 and 200r/min, adding the remaining 1/2 composite complexing agent during stirring, and stirring uniformly for 30 seconds to form a solution D;

and D, adjusting the pH value of the solution D to 4.3-4.6, and then adding a pH buffer with the mass concentration of 25% to form the nickel plating solution.

The composite complexing agent is added in a separate mode in the using process, and is not poured into the plating solution at one time, because the composite complexing agent mainly plays a promoting role in the above steps, the uniform mixing of the five components is promoted, the nickel salt is added in the last step in the configuration process, and the composite complexing agent mainly plays a complexing role in the back, so that the stability of the plating solution is improved; the nickel salt is added in the last step, so that the oxidation of the nickel salt is reduced, and the deposition speed of the nickel liquid is improved; particularly, the composite complexing agent increases certain stability on the basis of the original complexing action, so that the stability of the plating solution is kept lasting for a long time.

In this embodiment, the nickel salt is nickel sulfate or nickel sulfamate, and the surfactant is sodium methallylsulfonate. The conductive ions of the conductive salt can greatly improve the conductive effect of the plating solution on the basis of ensuring the conductive performance; the anti-aging agent is the conventional anti-aging agent on the market; the anti-aging agent is ketoamine anti-aging agent, currently the most commonly used is 6-ethoxy-2, 2, 4-trimethyl-1, 2-dihydroquinoline, and the trade name is anti-aging agent AW; the conductive salt can be acid or alkali substances and is also a conventional conductive salt on the market.

In order to achieve the above objects, the present invention also provides a nickel electroplating method of a nickel plating solution for a printed wiring board, comprising the following steps,

step 1, bombarding the surface of a plated part by adopting vacuum plasma to remove various pollutants and oxidation layers on the surface of the plated part;

step 2, carrying out first-stage nickel electroplating treatment, wherein the specific conditions of the nickel electroplating treatment are that the electroplating temperature is 60-75 ℃, and the electroplating density is 2-2.5A/dm²The electroplating time is 5-10 minutes, and the thickness of the nickel layer can reach 3-6 mu m;

step 3, performing second-stage nickel electroplating treatment on the plated part after the first-stage nickel electroplating treatment, wherein the specific conditions of the nickel electroplating treatment are that the electroplating temperature is 45-50 ℃, and the electroplating density is 0.7-1.5A/dm²The electroplating time is 10-15 minutes, and the thickness of the nickel layer can reach 2-5 mu m; forming a nickel plating layer after the total thickness of the nickel layer is 5-11 mu m;

step 4, bombarding the surface of the plated part with the nickel plating layer by adopting vacuum plasma again;

and 5, carrying out the next electroplating process on the plated part subjected to the surface treatment.

In this embodiment, the specific conditions of the vacuum plasma bombardment in the step 4 are as follows: the working medium adopted by the vacuum plasma bombardment is a mixed gas of hydrogen and nitrogen, wherein the volume ratio of the hydrogen to the nitrogen is (1-2): 3; the distance of the plasma bombardment is controlled to be 3-5 cm; the treatment temperature is 30-40 ℃; the treatment time is 15-25 s. The specific conditions of the vacuum plasma bombardment in the step 1 are as follows: the working medium adopted by the vacuum plasma bombardment is a mixed gas of hydrogen and nitrogen, wherein the volume ratio of the hydrogen to the nitrogen is (1-2): 3, controlling the bombardment distance to be 20-25 mm; the treatment temperature is 90-110 ℃; the treatment time is 15-25 s. The step 1 and the step 4 both adopt the mixed gas of hydrogen and nitrogen as the working medium for bombarding the surface of the plated part, the cleaning degree of the method is much better than that of the existing method adopting ultrapure water cleaning, the method is more favorable for the tight combination of the nickel plating layer and the base material, and the bonding strength between the plating layer and the base material is further improved. The bombardment is mainly different in distance; the closer the distance is, the greater the bombardment strength is, because the plated piece before nickel plating can be cleaned more deeply, so the bombardment distance is controlled to be 3-5 cm; step 4, nickel plating is finished, the surface of the nickel plated part has certain brittleness along with the time, the bombardment distance is lengthened, the surface of the plated part can become compact and smooth while cleaning, and the void ratio is reduced; and the bonding degree of the coating and the base material can be further enhanced in the bombardment process.

Compared with the prior art, the invention has the following advantages: 1) the reaction accelerator, the composite stabilizer and the composite complexing agent are added on the basis of the original components of the nickel plating solution, the reaction accelerator accelerates the activation reaction speed of the nickel plating solution and reduces the activation time; particularly, on the composite complexing agent, a specially-prepared component A and a component B are adopted, the component A is used as a main complexing agent, and polyacrylamide in the component B has good scale inhibition performance, has a function of adsorbing impurities, and has good colloid characteristics and a dispersing function; but because the complexing capacity is small, the phenomenon of instability is easily caused by the small capacity in the complexing process, and nickel ions can be deposited on the wall of the tank all the time along with the lengthening of the electroplating time, in order to solve the problems, polyacrylamide, amino carboxylic acid resin, hyperbranched polyurethane sulfonate and beta-nicotinamide adenine dinucleotide are used as a part of a complexing agent, and the macromolecular substances have the characteristic of high macromolecular viscosity while being complexed; when electroplating, the composite complexing agent can promote reaction and simultaneously avoid metal ion deposition, so that the bonding strength between the plating layer and the matrix is very stable, the plated part can not fall off even in subsequent high-temperature recycling, and the service life of the plated part is further prolonged.

2) By adopting the components of the scheme, a reaction accelerator, a specially-prepared composite complexing agent of conductive salt and a specially-prepared composite stabilizer are added on the basis of the original components, and the complexing agent of the technology has the stabilizing effect of high molecular viscosity on the basis of the original complexing effect, so that the conductive salt increases the conductive effect, and the complexed metal nickel ions are discharged and deposited on the surface of a cathode to meet the larger resistance of the cathode, thereby generating larger negative polarization, and further greatly improving the dispersion capacity and the covering capacity of the plating solution; the stability of the composite complexing agent and the stability of the composite stabilizer are the same, and the solution can realize perfect electroplating without electroplating at the original high temperature by dual stable use; and the dual stability is favorable for adjusting the plating speed and the plating quality of electroplating, ensures the bonding strength between the plating and the matrix, and simultaneously ensures that the plated part is easy to spread on the surface of the electrode to achieve the purpose of uniform plating, thereby further achieving the effect of filling the wafer packaging micropores without holes and gaps.

3) The invention adopts vacuum plasma to bombard the surface of the plated part before and after electroplating, not only removes various pollutants and oxide layers on the surface of the plated part, but also ensures the surface of the plated part to be compact and smooth after cleaning, has high surface cleaning degree, is beneficial to the tight combination of a plating layer and a base material, and further ensures the bonding strength between the plating layer and the base body.

4) Generally, the plating layer is easy to fall off due to the overhigh temperature during nickel electroplating; when the nickel plating solution is used for electroplating, the treatment is carried out in two electroplating stages; the first stage can be completed in a short time by adopting high temperature and high density of 60-75 ℃ due to the very good stability and complexation property at the beginning of use, and the nickel precipitation speed is very high under the action of the composite complexing agent in the process, so that most of procedures of nickel electroplating can be completed quickly; the stability is reduced along with the progress of electroplating, the temperature and the density are reduced within the time, the electroplating time is prolonged, even under the condition of 45-50 ℃, the dispersion capacity and the covering capacity of the plating solution can ensure that the discharge deposition effect of the metal nickel ions is not influenced due to the action of the composite complexing agent, so that the continuation of electroplating is ensured, and finally the proper thickness of a nickel plating layer is achieved. The technology adopts a two-stage mode of different temperatures and different densities to carry out electroplating, so that the phenomenon that a plating layer is easy to fall off at high temperature is avoided; the bonding strength between the plating layer and the substrate is further ensured, so that the nickel plating layer has good adhesiveness and uniform plating layer; the process not only ensures the uniformity of electroplating, but also shortens the electroplating time.

5) In addition, the technology adopts a mode of different temperatures and different densities for electroplating in two stages; when the thickness of the nickel plating needed by the plating layer is between 3 and 6 mu m, the second stage of electroplating can be stopped, and the application range of the solution is enlarged.

In this embodiment, the nickel plating solution in step 3 is drained into a nickel plating solution recovery tank after use; and concentrating the nickel recovery solution in the nickel plating recovery tank, controlling the concentration of the recovered nickel plating solution, and recovering the nickel plating solution into the nickel plating solution tank for recycling. Because the nickel price is high and has certain toxicity, the nickel is recycled after being immediately recycled, and the nickel plating cost is greatly reduced.

The following are several specific examples of the invention

Example 1

A nickel plating solution applied to a printed circuit board comprises the following components in mass concentration:

nickel sulfate 35g/L

Conductive salt 40g/L

Antiager AW 10 g/L

7g/L composite complexing agent

Reaction accelerator 80mg/L

Stress relieving agent 80mg/L

Sodium methallylsulfonate 10mg/L

Composite stabilizer 3mg/L

The composite complexing agent comprises a component A and a component B, wherein the mass concentration ratio of the component A to the component B is 3:1, and the component A comprises citric acid with the mass concentration of 2g/L, ammonium acetate with the mass concentration of 1g/L and malic acid with the mass concentration of 2.25 g/L; the component B is a mixture of polyacrylamide, aminocarboxylic acid resin, hyperbranched polyurethane sulfonate and beta-nicotinamide adenine dinucleotide, and the mass concentration is 1.75 g/L. The pH value of the solution is adjusted to be between 4.5, and then the solution is buffered by a pH buffering agent with the mass concentration of 25 percent to form the nickel plating solution.

The nickel plating solution prepared by the components is adopted to electroplate the printed circuit board by adopting the nickel electroplating method, the temperature of the first stage is 70 ℃, and the density is 2.5A/dm²The time is 8 minutes, and the thickness of the nickel layer obtained in the first stage is 6 microns; the temperature in the second stage was 55 ℃ and the density was 1.5A/dm²The time is 15 minutes, the thickness of the nickel layer obtained in the second stage is 5 micrometers, and the thickness of the total nickel layer is 11 micrometers; the whole electroplating process is used for 21 minutes totally, the whole electroplating time is shorter than that of the conventional electroplating time of 30-35 minutes, and the obtained nickel-plated layer has uniform crystallization and smooth surface; the nickel-plated layer is tested by a 180-degree bending test, and then a bent part is inspected by a magnifying glass which is amplified by 100 times, so that obvious cracks are not observed, and the peeling and falling phenomena are not generated; the bonding force of the nickel plating layer is good.

The stress remover consists of 50 percent of saccharin, 20 percent of 2-mercaptobenzothiazole and 30 percent of 4-methoxybenzothiazole by mass percentage.

The reaction accelerator consists of 40 mg/L2, 6-diaminopyridine and 40 mg/L3-pyridinemethanol complex.

The composite stabilizer is a compound of 2.4mg/L cerium sulfate and 0.6mg/L benzotriazole, and the conductive salt can be sodium acetate.

Example 2

A nickel plating solution applied to a printed circuit board comprises the following components in mass concentration:

nickel sulfamate 50g/L

Conductive salt 20g/L

Antiager AW 15g/L

5g/L composite complexing agent

Reaction accelerator 75mg/L

Stress relieving agent 75mg/L

5mg/L sodium methallyl sulfonate

Composite stabilizer 0.2mg/L

The composite complexing agent comprises a component A and a component B, wherein the mass concentration ratio of the component A to the component B is 3:2, and the component A comprises citric acid with the mass concentration of 1g/L, ammonium acetate with the mass concentration of 1g/L and malic acid with the mass concentration of 1 g/L; the mass concentration of the component B is 2 g/L. The nickel plating solution can be formed after the pH value of the solution is adjusted to be 4.6 by using a pH buffering agent with the mass concentration of 25 percent.

The nickel plating solution prepared by the components is adopted to electroplate a printed circuit board by adopting the nickel electroplating method, the temperature of the first stage is 60 ℃, the time is 10 minutes, and the density is 2A/dm²The thickness of the nickel layer obtained in the first stage is 4 micrometers, the whole electroplating process is used for 10 minutes totally, the thickness of the required nickel layer is just 4 micrometers, only the electroplating in the first stage is carried out, the second stage is not needed, other steps are not changed, and the obtained nickel layer is uniform in crystallization and smooth in surface; the nickel-plated layer is tested by a 180-degree bending test, and then a bent part is inspected by a magnifying glass which is amplified by 100 times, so that obvious cracks are not observed, and the peeling and falling phenomena are not generated; the bonding force of the nickel plating layer is good.

The stress remover consists of 55 percent of saccharin, 25 percent of 2-mercaptobenzothiazole and 20 percent of 4-methoxybenzothiazole by mass percentage.

The reaction accelerator consisted of 50mg/L of 2, 6-diaminopyridine and 25mg/L of 3-pyridinemethanol complex.

The composite stabilizer is a compound of 0.16mg/L cerium sulfate and 0.04mg/L benzotriazole, and the conductive salt can be sodium acetate.

Example 3

A nickel plating solution applied to a printed circuit board comprises the following components in mass concentration:

nickel sulfate 40g/L

Conductive salt WA 40g/L

Anti-aging agent 12g/L

15g/L of composite complexing agent

Reaction accelerator 70mg/L

70mg/L stress relieving agent

Sodium methallylsulfonate 10mg/L

Composite stabilizer 5mg/L

The composite complexing agent comprises a component A and a component B, wherein the mass concentration ratio of the component A to the component B is 3:2, and the component A comprises citric acid with the mass concentration of 4g/L, ammonium acetate with the mass concentration of 2g/L and malic acid with the mass concentration of 3 g/L; the mass concentration of the component B is 6 g/L. The nickel plating solution can be formed after the pH value of the solution is adjusted to be 4.6 by using a pH buffering agent with the mass concentration of 25 percent.

The nickel plating solution prepared by the components is adopted to electroplate the printed circuit board by adopting the nickel electroplating method, the temperature of the first stage is 65 ℃, the time is 5 minutes, and the density is 2A/dm²The thickness of the nickel layer obtained in the first stage is 4 microns; the temperature of the second stage was 40 ℃ for 15 minutes and the density was 0.7A/dm²The thickness of the nickel layer obtained in the second stage is 3 microns, and the thickness of the total nickel layer is 7 microns; the whole electroplating process is used for 20 minutes totally, and the obtained nickel-plated layer has uniform crystallization and smooth surface; the nickel-plated layer is tested by a 180-degree bending test, and then a bent part is inspected by a magnifying glass which is amplified by 100 times, so that obvious cracks are not observed, and the peeling and falling phenomena are not generated; the bonding force of the nickel plating layer is good.

The stress remover consists of 60 percent of saccharin, 10 percent of 2-mercaptobenzothiazole and 30 percent of 4-methoxybenzothiazole by mass percentage.

The reaction accelerator consists of 35mg/L of 2, 6-diaminopyridine and 35mg/L of 3-pyridinemethanol complex.

The composite stabilizer is a compound of 4mg/L cerium sulfate and 1mg/L benzotriazole, and the conductive salt can be sodium acetate.

Example 4

A nickel plating solution applied to a printed circuit board comprises the following components in mass concentration:

nickel sulfamate 40g/L

Conductive salt 20g/L

Anti-aging agent WA 12g/L

Composite complexing agent 9g/L

Reaction accelerator 50mg/L

Stress relieving agent 50mg/L

5mg/L sodium methallyl sulfonate

Composite stabilizer 5mg/L

The composite complexing agent comprises a component A and a component B, wherein the mass concentration ratio of the component A to the component B is 3:1.5, and the component A comprises citric acid with the mass concentration of 3g/L, ammonium acetate with the mass concentration of 1.5g/L and malic acid with the mass concentration of 3 g/L; the component B is a mixture of polyacrylamide, amino carboxylic acid resin, hyperbranched polyurethane sulfonate and beta-nicotinamide adenine dinucleotide, and the mass concentration of the mixture is 2 g/L. The pH value of the solution is adjusted to be between 4.5, and then the solution is buffered by a pH buffering agent with the mass concentration of 25 percent to form the nickel plating solution.

The nickel plating solution prepared by the components is adopted to electroplate the printed circuit board by adopting the nickel electroplating method, the temperature of the first stage is 60 ℃, the time is 5 minutes, and the density is 2A/dm²The thickness of the nickel layer obtained in the first stage is 3.5 microns; the temperature in the second stage was 55 ℃ for 15 minutes and the density was 1.5A/dm²The thickness of the nickel layer obtained in the second stage is 5 microns, and the total thickness of the nickel-plated layer is 8.5 microns; the whole electroplating process is used for 20 minutes totally, and the obtained nickel-plated layer has uniform crystallization and smooth surface; the nickel-plated layer is tested by a 180-degree bending test, and then a bent part is inspected by a magnifying glass which is amplified by 100 times, so that obvious cracks are not observed, and the peeling and falling phenomena are not generated; the bonding force of the nickel plating layer is good.

The stress remover consists of 60 percent of saccharin, 30 percent of 2-mercaptobenzothiazole and 10 percent of 4-methoxybenzothiazole by mass percentage.

The reaction accelerator consists of 30mg/L of 2, 6-diaminopyridine and 20mg/L of 3-pyridinemethanol complex.

The composite stabilizer is a compound of 4mg/L cerium sulfate and 1mg/L benzotriazole, and the conductive salt can be sodium acetate.

Comparative example 1

Nickel salt 30g/L

Citric acid 25g/L

Complexing agent 25g/L

5mg/L cerium sulfate

Antimony potassium tartrate 3mg/L

Surfactant 8mg/L

Saccharin 15g/L

The nickel plating solution prepared by the components is electroplated by a conventional electroplating mode, the electroplating temperature is more than 80 ℃, the finally obtained nickel plating layer is 15 microns, and the electroplating time is 35 minutes; the nickel plating layer is subjected to 180-degree bending test, then a bent part is inspected by a magnifying glass which is amplified by 100 times, cracks are obviously observed, and peeling and falling are generated; the bonding force between the nickel-plated layer and the base material does not reach the effect of market demand.

In addition, the plated articles obtained in the four specific examples and comparative example 1 were subjected to a rubbing and polishing test by the following specific operation method: putting the plated part in a vibration polishing machine, and performing a friction polishing test by using a soap aqueous solution as a lubricant; the plated parts obtained in the specific examples 1 to 4 have uniform surface plating and flat appearance, and no bubbling phenomenon occurs; however, in comparative example 1, the surface had a remarkable foaming phenomenon.

Through the four specific examples and the comparative example 1 of the invention, the comparative example 1 adopts a conventional electroplating method because a composite complexing agent, an accelerating reagent and a composite stabilizer are not adopted, the electroplating time is long, the thickness of a nickel plating layer is large, the expected requirements cannot be met, and the product yield is low; the binding force between the plating layer and the base material is not high; the nickel layer of the plated part obtained by the invention has smooth appearance and uniform crystal lattice size of the plating layer; the microscopic observation shows that the structure of the plating layer is very compact, the crystallization of the plating layer is fine and uniform, and no crack exists; through 180-degree bending test, the bonding force of the plating layer is good, and no obvious crack is observed when the plating layer is amplified by 100 times; by using a friction polishing experiment method, the surface of the plated part obtained by the invention is firm and uniform, and the phenomenon of foaming is completely avoided, which shows that the bonding force between the nickel plating layer obtained by the invention and the base material is very good, thereby perfectly ensuring the compactness of the plating layer structure.

The above disclosure is only an example of the present invention, but the present invention is not limited thereto, and any variations that can be made by those skilled in the art should fall within the scope of the present invention.