An industrial nickel stripper suitable for use in stripping nickel from circuit boards and a method of using the same

Abstract

An industrial nickel stripping agent suitable for nickel-plated circuit board, which is composed of hydrofluoric acid, citric acid, hydrogen peroxide, benzotriazole and brightener. The concentration of the hydrofluoric acid is 20-100 ml / L, the concentration of the citric acid is 10-50 ml / L, the concentration of the hydrogen peroxide is 30-150 ml / L, the concentration of the benzotriazole is 0.1-0.6 g / L, and the concentration of the brightener is 5-20 ml / L. The industrial nickel stripping agent is mixed by the components with the above concentrations, and the nickel-plated circuit board is directly immersed in the industrial nickel stripping agent at room temperature for nickel stripping. The industrial nickel stripping agent uses the three of hydrofluoric acid, citric acid and hydrogen peroxide as a whole to solve the technical problem of copper substrate damage in the stripping process. At the same time, when used, the nickel stripping agent is used at room temperature, avoiding the corrosion of the acid gas evaporated to the human body and other objects, so as to protect the environment and reduce the production cost. The application also provides a use method of the industrial nickel stripping agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circuit board manufacturing, in particular to an industrial nickel stripping agent suitable for nickel-plated circuit boards and a use method thereof. BACKGROUND

[0002] In the electronic industry, circuit boards have become an indispensable component. In the process of making circuit boards, in order to set a barrier layer between the copper layer and the gold layer to prevent gold and copper from diffusing with each other and affecting the solderability and service life of the board, a nickel layer is usually plated on the copper layer. However, during the process of chemical or electroplated nickel, many poor nickel-plated products often occur. In order to reduce costs and improve efficiency, the process of stripping and re-plating is generally adopted for treatment. At present, there are generally two methods for stripping, one is chemical stripping, and the other is electrolytic stripping. These two stripping methods have their own characteristics and are widely used. The main component of the chemical stripping agent is nitric acid or cyanide. The nitric acid stripping method not only has the problems of damaging the substrate and incomplete stripping, but also has the problems of long time, high concentration of harmful substances, strong pollution, large amount of reagent (20% nitric acid), unsafe operation and high cost. Although the cyanide stripping method can completely strip, the residual liquid is highly toxic and difficult to handle, and the operation process is harmful to the human body. The electrolytic method has the problems of incomplete electrolysis, damage to the substrate, and inability to electrolyze in the local non-conductive area. SUMMARY

[0003] Therefore, the present application provides an industrial nickel stripping agent suitable for nickel-plated circuit boards and a use method thereof, which can solve the above technical problems.

[0004] An industrial nickel stripping agent suitable for nickel-plated circuit boards is composed of hydrofluoric acid, citric acid, hydrogen peroxide, benzotriazole, and brightener. The concentration of the hydrofluoric acid is 20-100 ml / L, the concentration of the citric acid is 10-50 ml / L, the concentration of the hydrogen peroxide is 30-150 ml / L, the concentration of the benzotriazole is 0.1-0.6 g / L, and the concentration of the brightener is 5-20 ml / L. The industrial nickel stripping agent is mixed by the above components with the above concentrations, and the nickel-plated circuit board is directly immersed in the industrial nickel stripping agent at room temperature for nickel stripping.

[0005] Further, the concentration of the hydrofluoric acid is 36-44 ml / L.

[0006] Further, the concentration of the citric acid is 27-33 ml / L.

[0007] Further, the concentration of the hydrogen peroxide is 72-88 ml / L.

[0008] Further, the concentration of the benzotriazole is 0.3 g / L.

[0009] A method for using an industrial nickel stripping agent for nickel-plated circuit boards, comprising the following steps:

[0010] S1: providing hydrofluoric acid, citric acid, hydrogen peroxide, benzotriazole, and brightener, wherein the concentration of the hydrofluoric acid is 20-100 ml / L, the concentration of the citric acid is 10-50 ml / L, the concentration of the hydrogen peroxide is 30-150 ml / L, the concentration of the benzotriazole is 0.1-0.6 g / L, and the concentration of the brightener is 5-20 ml / L;

[0011] S2: taking a container with a capacity of 200-300 L, adding 85-120 L of pure water, 4-5 L of hydrofluoric acid, 3-3.5 L of citric acid, and 8-10 L of hydrogen peroxide, and stirring to form a mixture;

[0012] S3: adding the benzotriazole and the brightener to the mixture, and stirring to form the industrial nickel stripping agent, wherein the benzotriazole is 3-6 g, and the brightener is 5-6 L;

[0013] S4: providing a nickel-plated circuit board, and immersing the nickel-plated circuit board in the industrial nickel stripping agent at room temperature for 2-3 minutes to complete the nickel stripping process.

[0014] Further, in step S2, the prepared industrial nickel stripping agent is filled in a plastic bucket or a plastic bottle.

[0015] Compared with the prior art, the present application uses relatively low-concentration hydrofluoric acid to achieve nickel stripping, and the hydrofluoric acid does not react with the copper substrate, thereby protecting the copper substrate from damage. Meanwhile, the relatively low-concentration citric acid and hydrogen peroxide are used to slightly etch the copper substrate, thereby achieving polishing. Since the concentrations of the citric acid and the hydrogen peroxide are low, the damage to the copper substrate is small. The benzotriazole is used as an inhibitor, which can protect the copper substrate from oxidation. The present application uses the hydrofluoric acid, the citric acid, and the hydrogen peroxide as a whole to solve the technical problem of copper substrate damage in the stripping process. Meanwhile, the industrial nickel stripping agent is used at room temperature, avoiding the emission of acidic gas to corrode the human body and other objects, thereby protecting the environment and reducing production costs. In addition, the industrial nickel stripping agent is easy to use, and direct immersion is not necessary. Moreover, the industrial nickel stripping agent is low in price and easy to popularize. Since the amounts of the hydrofluoric acid and the hydrogen peroxide are small, the residual liquid is easy to handle, and the cost is low. The ordinary acid-base neutralization method can be used to handle the residual liquid, and the cyanide waste liquid treatment process is not necessary. DETAILED DESCRIPTION

[0016] The following further describes specific embodiments of the present application. It should be understood that the description of the embodiments of the present application herein is not intended to limit the protection scope of the present application.

[0017] The present application provides an industrial nickel stripping agent for nickel-plated circuit board, which is composed of hydrofluoric acid, citric acid, hydrogen peroxide, benzotriazole and brightener. The hydrofluoric acid is a prior art, which can react with nickel to achieve the purpose of stripping when used in stripping of nickel-plated circuit board. The concentration of the hydrofluoric acid is 20-100 ml / L, preferably 36-44 ml / L. The concentration of the hydrofluoric acid cannot be less than 20 ml / L or greater than 100 ml / L, because when the concentration of the hydrofluoric acid is less than 20 ml / L, the stripping time is prolonged by 57 seconds and the stripping efficiency is low, and when the concentration of the hydrofluoric acid is greater than 100 ml / L, the stripping is slower and the copper substrate is damaged. The citric acid is also a prior art, which will not be described here. The concentration of the citric acid is 10-50 ml / L, preferably 27-33 ml / L. The concentration of the citric acid cannot be less than 10 ml / L or greater than 50 ml / L, because when the concentration of the citric acid is less than 10 ml / L, the stripping time is long and the stripped copper substrate is not bright, and when the concentration of the nitric acid is greater than 50 ml / L, the concentration will damage the copper substrate. In actual use, the citric acid is a weak acid with low concentration, so it does not react with copper. However, the citric acid and hydrogen peroxide have a certain etching effect on the copper substrate of the circuit board, so that the copper substrate is brighter and the original color of the copper substrate is revealed. Therefore, the concentration of the hydrogen peroxide is 30-150 ml / L, preferably 72-88 ml / L. In actual use, the concentration of the hydrogen peroxide cannot be less than 30 ml / L or greater than 150 ml / L, because when the concentration of the hydrogen peroxide is less than 30 ml / L, the stripping efficiency is low and the stripping is not clean, and when the concentration of the hydrogen peroxide is greater than 150 ml / L, the hydrogen peroxide with this concentration reacts with copper under acidic conditions, which directly damages the copper substrate. Of course, the hydrogen peroxide can react with copper under acidic conditions, but the concentration is low and the reaction is weak, so its effect on the copper substrate can be ignored.

[0018] The benzotriazole is a prior art, which can effectively protect the copper substrate of the circuit board. Its working mechanism is that after the copper substrate is exposed, the benzotriazole can quickly adhere to the surface of the copper, thereby effectively preventing the copper substrate from being corroded. The weight percentage of the benzotriazole is 0.1-0.6 g / L. The brightener is used to enhance the brightness of the copper substrate and effectively protect the copper substrate. Specifically, after the copper substrate of the circuit board is exposed, the brightener can quickly adhere to the copper substrate, enhance the uniformity and brightness of the copper substrate, and prevent it from being corroded. In this embodiment, the concentration of the brightener is 5-20 ml / L.

[0019] The application also provides a use method of the industrial nickel stripping agent for nickel-plated circuit board, which comprises the following steps:

[0020] S1: providing hydrofluoric acid, citric acid, hydrogen peroxide, benzotriazole and brightener, wherein the concentration of the hydrofluoric acid is 20-100 ml / L, the concentration of the citric acid is 10-50 ml / L, the concentration of the hydrogen peroxide is 30-150 ml / L, the concentration of the benzotriazole is 0.1-0.6 g / L, and the concentration of the brightener is 5-20 ml / L;

[0021] S2: taking 200-300 L of a container, adding 85-120 L of pure water, 4-5 L of hydrofluoric acid, 3-3.5 L of citric acid and 8-10 L of hydrogen peroxide, and stirring to form a mixture;

[0022] S3: adding the benzotriazole and the brightener to the mixture, and stirring to form the industrial nickel stripping agent, wherein the benzotriazole is 3-6 g, and the brightener is 5-6 L;

[0023] S4: providing a nickel-plated circuit board, and immersing the nickel-plated circuit board in the industrial nickel stripping agent at room temperature for 2-3 minutes to complete the nickel stripping process.

[0024] In step S2, the added amount of the hydrofluoric acid is 4.5 L, the added amount of the citric acid is 3.2 L, and the added amount of the hydrogen peroxide is 9 L. The prepared industrial nickel stripping agent must be filled in a plastic bucket, a plastic bottle or the like, and cannot be filled in a glass or metal device to prevent chemical reaction of the hydrofluoric acid with glass or metal.

[0025] In step S3, the added amount of the benzotriazole is 4 g, and the added amount of the brightener is 5.4 L.

[0026] In addition, a cyanide-free nickel stripping agent has been put on the market in recent years, but the price is relatively high, about 68 yuan / kg or more, and the nickel stripping time is 15 min or more (nickel thickness 3-5 um). Through actual verification, the price of the industrial nickel stripping agent is 15 yuan / kg, and the main components and the optimal ratio are as follows: the concentration of the hydrofluoric acid is 40+ / -4 ml / L, the concentration of the citric acid is 30+ / -3 ml / L, the concentration of the hydrogen peroxide is 80+ / -8 ml / L, and the nickel stripping time is 120 s (nickel thickness 3-5 um).

[0027] Compared with the prior art, the present application realizes nickel stripping by using relatively low concentration of hydrofluoric acid, and the hydrofluoric acid does not react with the base material copper, thereby well protecting the base material copper from damage, and meanwhile, the base material copper is micro-etched by using relatively low concentration of citric acid and hydrogen peroxide, thereby playing a polishing role. Since the concentration of citric acid and hydrogen peroxide in the present application is very low, damage to the base material copper is small, and meanwhile, benzotriazole is used as a corrosion inhibitor, and the effect is better, which can protect the base material copper from oxidation. The present application uses hydrofluoric acid, citric acid and hydrogen peroxide as a whole to solve the technical problem of damage to the base material copper in the stripping process. Meanwhile, in use, the nickel stripper is used at normal temperature, avoiding the evaporation of acidic gas to form corrosion to the human body and other objects, thereby protecting the environment and reducing production cost. In addition, the industrial nickel stripper is convenient to use, directly immersed without spraying, and low in price, thereby being convenient to popularize. Moreover, since the amount of hydrofluoric acid and hydrogen peroxide is small, the residual liquid is simple to handle, low in cost, and can be treated by using ordinary acid-base neutralization method without treatment according to the cyanide waste liquid treatment process.

[0028] Example one: nickel-plated PCB stripping

[0029] 1, the stripping solution is composed of the following: hydrofluoric acid concentration: 40ml / L, citric acid concentration: 30ml / L, hydrogen peroxide concentration: 80ml / L, benzotriazole: 0.3g / L, and brightener: 10ml / L.

[0030] 2, the stripping and replating process of the stripping solution is as follows: unqualified nickel-plated product—nickel stripping—water washing—oil removal—water washing—micro-etching—water washing—amino acid—water washing—nickel plating—water washing—gold plating—water washing—drying—inspection;

[0031] 3, the implementation steps are as follows:

[0032] (1) unqualified product nickel stripping: the stripping solution is composed of the following: hydrofluoric acid 40ml / L, citric acid 30ml / L, hydrogen peroxide 80ml / L, benzotriazole 0.3g / L, and brightener 10ml / L, time 161s, temperature: normal temperature;

[0033] (2) water washing: the product is water washed by air rolling for 20 seconds;

[0034] (3) oil removal: the concentration of acidic oil removal agent is 10g / L, the oil removal temperature is 40-50℃, and the time is 2 minutes;

[0035] (4) water washing: the product is water washed by air rolling for 20 seconds;

[0036] (5) micro-etching: the solution is composed of the following: sodium persulfate 40-60g / L, and sulfuric acid 30-50g / L, and the time is 2 minutes;

[0037] (6) water washing: the product is water washed by air rolling for 20 seconds;

[0038] (7) Sulfamic acid: 6-10% sulfamic acid solution, 10 seconds;

[0039] (8) Water washing: 10 seconds of air rolling water washing of the product;

[0040] (9) Nickel plating: 14-18 g / L of sulfamic acid, 130-150 g / L of sulfamic acid nickel plating solution, 1-2 A / dm2 of current density, 8 minutes of plating, 3-5 um of nickel thickness;

[0041] (10) Water washing: 20 seconds of air rolling water washing of the product;

[0042] (11) Gold plating: 1-2 minutes of hard gold cylinder gold plating, 2-4 um of gold thickness;

[0043] (12) Water washing: 20 seconds of air rolling water washing of the product;

[0044] (13) Drying: 80°C high temperature air drying of the surface moisture of the single product, 2 minutes of time.

[0045] (14) Inspection: inspection of the appearance, no abnormality.

[0046] Example Two: Chemical nickel aluminum oxide PCB stripping

[0047] 1. The stripping solution is composed of the following: 40 ml / L of hydrofluoric acid, 30 ml / L of citric acid, 80 ml / L of hydrogen peroxide, 0.3 g / L of benzotriazole, and 10 ml / L of brightener.

[0048] 2. The stripping solution stripping process is as follows: chemical nickel PCB product - nickel stripping - water washing - drying - inspection;

[0049] 3. The implementation steps are as follows:

[0050] (1) Chemical nickel PCB product stripping: the stripping solution is composed of the following: 40 ml / L of hydrofluoric acid, 30 ml / L of citric acid, 80 ml / L of hydrogen peroxide, 0.3 g / L of benzotriazole, and 10 ml / L of brightener, 60 seconds of time, room temperature;

[0051] (2) Water washing: 20 seconds of air rolling water washing of the product;

[0052] (3) Drying: 80°C high temperature air drying of the surface moisture of the single product, 2 minutes of time.

[0053] (4) Inspection: inspection of the appearance, no abnormality, no nickel metal residue after nickel stripping.

[0054] Conclusion: through the above two examples, the stripping solution can effectively remove the nickel plating layer and the chemical nickel layer, the product after stripping has high smoothness and flatness, and has less damage to the substrate, the cost of the stripping solution is 4.5 times lower than that of the traditional stripping agent, the stripping qualified rate is high, and the stripping requirements of the nickel metal can be better met.

[0055] The above are only preferred embodiments of the present application and are not used to limit the protection scope of the present application, and any modification, equivalent replacement or improvement within the spirit of the present application is covered within the protection scope of the claims of the present application.

Claims

1. An industrial nickel stripping agent suitable for nickel-plated circuit boards, characterized in that: The industrial nickel stripping agent suitable for nickel-plated circuit board is composed of hydrofluoric acid, citric acid, hydrogen peroxide, benzotriazole and brightener, the concentration of the hydrofluoric acid is 20-100 ml / L, the concentration of the citric acid is 10-50 ml / L, the concentration of the hydrogen peroxide is 30-150 ml / L, the concentration of the benzotriazole is 0.1-0.6 g / L, and the concentration of the brightener is 5-20 ml / L, the industrial nickel stripping agent is mixed by the components with the above concentrations, and the nickel-plated circuit board is directly subjected to nickel stripping by being soaked in the industrial nickel stripping agent at room temperature, the nickel-plated circuit board is soaked in the industrial nickel stripping agent at room temperature for 2-3 minutes, and the nickel stripping process is completed.

2. The industrial nickel etchant for nickel-plated circuit boards according to claim 1, wherein: The concentration of the hydrofluoric acid is 36-44 ml / L.

3. The industrial nickel etchant for nickel-plated circuit boards according to claim 1, wherein: The concentration of the citric acid is 27-33 ml / L.

4. The industrial nickel etchant for nickel-plated circuit boards according to claim 1, wherein: The concentration of the hydrogen peroxide is 72-88 ml / L.

5. The industrial nickel etchant suitable for nickel-plated circuit board according to claim 1, wherein: the pH of the etchant is 0.5 to 2.

0. The concentration of the benzotriazole is 0.3 g / L.