Method for removing phosphorus-nickel coating

Abstract

The invention discloses a method for removing a phosphorus-nickel coating, and belongs to the technical field of chemical nickel plating. The method for removing the phosphorus-nickel coating comprises the following steps that a base material plated with the phosphorus-nickel coating is soaked in a phosphorus-nickel coating removing agent at the temperature of 45-80 DEG C, and the phosphorus-nickel coating removing agent is used for removing the phosphorus-nickel coating; the content of each component of the phosphorus-nickel coating removing agent is as follows. According to the present invention, the process adopted by the present invention is stable and easy to control, meets the environmental protection policy, can rapidly and completely remove the phosphorus-nickel coating on the base material without leaving the residual coating, and the nickel-plated part treated by the process almost does not corrode the base material, such that the corrosion resistance of the nickel-plated part is good, and the service life of the nickel-plated part is prolonged. And the treated base material can completely reach the standard of secondary use.

Description

Technical Field

[0001] The invention relates to the field of chemical nickel plating, in particular to a method for removing a phosphorus nickel plating layer. Background Art

[0002] As a transitional surface treatment and final surface treatment, chemical nickel deposition technology is widely used in the sealing electronics industry. The process is green and environmentally friendly, with excellent corrosion resistance and welding performance. The phosphorus content of chemical nickel plating can be adjusted according to specific application requirements. It is generally divided into three categories: low phosphorus, medium phosphorus and high phosphorus, with phosphorus contents of 1-4%, 5-9% and 10-14% respectively. Platings with different phosphorus contents have different characteristics in hardness, wear resistance and corrosion resistance. Choosing the appropriate phosphorus content can meet different usage requirements.

[0003] In the nickel plating process of sealing electronic products, chemical nickel deposition technology is often used to nickel plate the electronic products. The nickel layer of the electronic products after nickel plating is often a high-phosphorus nickel layer. However, when there is external pollution or process control problems in the nickel plating process of sealing electronic products, defective products will appear.

[0004] As a transition and final surface treatment process, chemical nickel deposition generally gives priority to removing the surface treatment coating for rework in order to consider manufacturing costs. The following requirements are generally met for this removal process: (1) The coating is completely removed without leaving any residual coating; (2) There is no attack corrosion on the underlying metal, or there is acceptable slight corrosion; (3) The process is stable and easy to control, and complies with environmental protection policies. These requirements become increasingly difficult to achieve as the phosphorus content of the coating increases.

[0005] In the process of implementing the embodiments of the present invention, the inventors found that the background technology has at least the following defects: Chinese patent CN108754498A discloses a nickel stripping agent and a preparation method thereof. The strong acid mixed acid solution used in the process has a certain degree of corrosiveness to the underlying metal copper, and the diethylenetriamine used in the process can cause harm to the operator's body.

[0006] Chinese patent CN102268674B discloses a nickel stripping agent and a preparation method thereof. The ammonium persulfate used in the process is combustion-supporting and can cause harm to the operator.

[0007] Therefore, the applicant has found that the nickel stripping methods in the prior art are either highly polluting and easily harmful to operators and the environment, and as the phosphorus content of the coating increases, not only does it become more difficult to remove nickel, resulting in a long nickel removal time, but it also corrodes the base metal, resulting in the product after nickel removal not meeting the conditions for reuse, resulting in low yield, high nickel stripping costs, and extended delivery time.

[0008] Therefore, in order to overcome the defects of the existing nickel stripping methods on the market, it is of great significance to develop a high-phosphorus nickel layer stripping method that has good stripping effect on the high-phosphorus nickel layer, low corrosion to the underlying metal, fast processing speed and low cost. Summary of the invention

[0009] In order to overcome the deficiencies of the above-mentioned prior art, the inventors have found that the use of hydrogen peroxide 2-4%, sulfuric acid concentration 2.5-3‰, and water as a solvent as a phosphorus nickel coating stripping agent can significantly improve the stripping effect of the high-phosphorus nickel layer at a temperature above 55 degrees. Under the same other conditions, the temperature is 30 degrees and it can basically only remove a high-phosphorus nickel layer of about 1 micron in 10 hours. In general, the thickness of the high-phosphorus nickel layer to be stripped is mostly 4-8 microns, and the nickel removal speed will be as high as more than 40 hours, which cannot fully meet the needs of normal production. However, if the temperature is raised to about 60 degrees and the content of hydrogen peroxide therein is still maintained at 2.5-3%, it is found that the phosphorus nickel coating of 4-12 microns can be removed within 1.5 hours, so that it can achieve a high nickel removal efficiency under basically pollution-free conditions, so that it can fully meet the standards of normal production. Therefore, the inventors have repeatedly studied and practiced, and the present invention is implemented by the following technical solutions; A method for removing a phosphorus-nickel coating, wherein the method is as follows: Nickel removal: The substrate plated with phosphorus-nickel coating is immersed in a phosphorus-nickel coating remover at a temperature of 45-80°C, wherein the contents of the components of the phosphorus-nickel coating remover are as follows: hydrogen peroxide 2-4%, sulfuric acid concentration 2.5-3‰, and the solvent is water.

[0010] Furthermore, before the nickel removal step, a preparation step is required; the preparation step is as follows: sulfuric acid, hydrogen peroxide and water are prepared in advance to configure the phosphorus-nickel plating remover, sulfuric acid is first added to the water, and then the remaining hydrogen peroxide is added when the water temperature is 60-80°C to configure it to a phosphorus-nickel plating remover with a temperature of 55-65°C, 2-4% hydrogen peroxide, 2.5-3‰ sulfuric acid concentration, and water as the solvent, and then the nickel removal step is performed when the temperature is 55-65°C.

[0011] Preferably, the temperature of the phosphorus-nickel plating stripping agent in the nickel removal step is 55-65°C.

[0012] Preferably, in the phosphorus-nickel plating remover, the specific gravity of hydrogen peroxide is 2.8-3%, and the specific gravity of sulfuric acid is 2.5-3‰.

[0013] According to actual tests conducted by the inventor, the nickel stripping effect is better when the following conditions are met for the substrate coated with phosphorus nickel.

[0014] Furthermore, the phosphorus content of the phosphorus-nickel coating on the substrate is above 8%.

[0015] Preferably, the metal activity of the substrate is lower than that of iron, such as alloys or metals such as 4J29, 4J42, and 4J50.

[0016] Preferably, the substrate plated with the phosphorus-nickel coating has a phosphorus content of more than 10%.

[0017] Preferably, the phosphorus nickel coating is a nickel coating produced by a chemical nickel deposition process.

[0018] In the nickel plating of sealed electronic products, the electronic products as the substrate and the nickel plating layer basically meet these conditions, that is to say, the method of the present invention can completely solve the problem. When there is external pollution or process control problems in the nickel plating process of sealed electronic products, there will be a demand for nickel stripping after defective products. Beneficial Effects

[0019] The phosphorus nickel coating on the substrate can be quickly and completely removed by the process of the present application without leaving any residual coating; The nickel-plated parts treated by the process of the present application will hardly corrode the substrate, and the treated substrate can fully meet the standards for secondary use.

[0020] The process used in this application is stable and easy to control, and complies with environmental protection policies. DETAILED DESCRIPTION

[0021] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0022] The phosphorus-nickel-plated substrate used in the present embodiment of the present application is a substrate made of 4J29 and having a nickel layer thickness of 5 microns.

[0023] Embodiment 1: A method for removing a phosphorus nickel coating, wherein the method for removing the phosphorus nickel coating is as follows: Nickel removal: The substrate plated with phosphorus-nickel coating is immersed in a phosphorus-nickel coating remover at a temperature of 55-60°C, wherein the contents of the components of the phosphorus-nickel coating remover are as follows: 2.5% hydrogen peroxide, 2.5‰ sulfuric acid concentration, and water as solvent.

[0024] Embodiment 2: A method for removing a phosphorus-nickel coating, wherein the method for removing the phosphorus-nickel coating is as follows: Nickel removal: The substrate plated with phosphorus-nickel coating is immersed in a phosphorus-nickel coating remover at a temperature of 60-65°C, wherein the contents of the components of the phosphorus-nickel coating remover are as follows: 3% hydrogen peroxide, 3‰ sulfuric acid concentration, and water as solvent.

[0025] Embodiment 3: A method for removing a phosphorus-nickel coating, wherein the method for removing the phosphorus-nickel coating is as follows: Preparation: Weigh in advance the hydrogen peroxide, sulfuric acid and water used to prepare 3% hydrogen peroxide and 3‰ sulfuric acid concentration, with the solvent being water; add sulfuric acid to the water under drainage conditions; after heating to 80°C, add hydrogen peroxide to prepare the phosphorus-nickel plating remover of the present invention, that is, obtain the phosphorus-nickel plating remover with a temperature of 65-70°C.

[0026] Nickel removal: Soak the substrate plated with phosphorus-nickel coating in a phosphorus-nickel coating remover at a temperature of 70-75°C.

[0027] Embodiment 4: A method for removing a phosphorus-nickel coating, wherein the method for removing the phosphorus-nickel coating is as follows: Preparation: Prepare sulfuric acid, hydrogen peroxide and water for preparing the phosphorus-nickel coating remover in advance, add sulfuric acid to the water under drainage conditions, and then add the remaining hydrogen peroxide when the water temperature is 55-60°C to prepare a phosphorus-nickel coating remover with a temperature of 55-60°C, 2.5% hydrogen peroxide, 2.5‰ sulfuric acid concentration, and water as the solvent, so as to obtain a phosphorus-nickel coating remover with a temperature of 60-65°C.

[0028] Nickel removal: Soak the substrate plated with phosphorus-nickel coating in a phosphorus-nickel coating remover at a temperature of 60-65°C.

[0029] Example 5: As a control group, a method for removing the phosphorus nickel coating is as follows: Nickel removal: The substrate plated with phosphorus-nickel coating is immersed in a phosphorus-nickel coating remover at a temperature of 30°C, wherein the contents of the components of the phosphorus-nickel coating remover are as follows: 2.5% hydrogen peroxide, 2.5‰ sulfuric acid concentration, and water as solvent.

[0030] Experiment 1: Under the conditions of Examples 1-5, the substrate material is 4J29, the nickel layer thickness is 5 microns, and the phosphorus content of the nickel layer is 8%, 10%, 12%, 10%, and 10%, respectively. The substrate is plated with a phosphorus nickel coating, and the removal of the phosphorus nickel coating is visually recorded by a camera. The corrosion of the underlying metal by the phosphorus nickel coating remover can be detected by a scanning electron microscope. The nickel removal time results are as follows:

[0031] From the above results, it can be seen that the 5-micron-thick high-phosphorus nickel layer can be removed within 1.5 hours using the process of the present application, and the corrosion of the base layer by the nickel remover can be avoided, and it can also be seen that the nickel removal speed is greatly affected by the temperature and the phosphorus content of the nickel layer. The inventors have further discovered that the phosphorus-nickel coating removal method of the present invention can jointly oxidize the phosphorus-nickel layer by sulfuric acid and hydrogen peroxide, and significantly increase the oxidation and carbonization rate of the phosphorus in the phosphorus-nickel layer at a temperature above 55 degrees, so that the phosphorus-nickel layer can be peeled off by oxidizing and carbonizing the phosphorus in the phosphorus-nickel layer, so that the phosphorus-nickel layer falls off in pieces, and the dissolution of the components that have fallen off is accelerated, reducing the damage to the substrate, thereby greatly increasing the nickel removal speed. However, at room temperature, this effect will not be achieved, but the nickel removal time will be greatly increased.

[0032] Experiment 2 The substrate material is 4J29, the nickel layer thickness is 5 microns, and the substrate is plated with a high-phosphorus nickel layer, and the phosphorus content of the high-phosphorus nickel layer is 10%. Nickel removal: Add the substrate plated with a high-phosphorus nickel layer into a high-phosphorus nickel layer remover at 30°C, 45°C, 55°C, 60°C, 65°C, and 70°C, respectively. The contents of the components of the high-phosphorus nickel layer remover are as follows: 2.5% hydrogen peroxide, 2.5‰ sulfuric acid concentration, and water as the solvent. The removal of the phosphorus-nickel coating is visually recorded by a camera. The corrosion of the phosphorus-nickel coating remover on the underlying metal can be detected by a scanning electron microscope. The nickel removal time results are as follows:

[0033] From the above results, it can be seen that the nickel removal speed of the process of the present application increases significantly above 55°C, and the nickel removal time is shortened to less than 1.5 hours when the temperature reaches above 60°C. Both the nickel removal time and the degree of pollution can fully meet the needs of daily production and greatly improve the processing efficiency. Although the processing time is longer when the temperature is 55-45 degrees, it can still play a good anti-pollution effect compared with some traditional nickel removal processes. Secondly, although the long processing time will increase the processing cost to a certain extent, on the whole, it still has certain advantages over the traditional nickel removal process. Although the efficiency is higher at 70-80°, the consumption of hydrogen peroxide will increase, and the high activity of the treated substrate metal may cause substrate corrosion problems. Therefore, technical personnel in this field can make a choice according to specific requirements.

[0034] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for removing a phosphorus-nickel coating, characterized in that: The removal method is as follows: Nickel removal: The substrate plated with phosphorus-nickel coating is immersed in a phosphorus-nickel coating remover at a temperature of 45-80°C, wherein the contents of the components of the phosphorus-nickel coating remover are as follows: hydrogen peroxide 2-4%, sulfuric acid concentration 2.5-3‰, and the solvent is water.

2. The method for removing phosphorus nickel plating according to claim 1, characterized in that: ； Before the nickel removal step, a preparation step is required; the preparation step is as follows: sulfuric acid, hydrogen peroxide and water are prepared in advance to configure the phosphorus-nickel plating remover, sulfuric acid is first added to the water, and then the remaining hydrogen peroxide is added when the water temperature is 60-80°C to configure the phosphorus-nickel plating remover with a temperature of 55-65°C, 2-4% hydrogen peroxide, 2.5-3‰ sulfuric acid concentration, and water as the solvent, and then the nickel removal step is performed when the phosphorus-nickel plating remover is at a temperature of 55-65°C.

3. The method for removing phosphorus nickel plating according to claim 1, characterized in that: ； The temperature of the phosphorus nickel plating stripping agent in the nickel removal step is 55-65°C.

4. The method for removing phosphorus nickel plating according to claim 1, characterized in that: ； In the phosphorus nickel plating remover, the proportion of hydrogen peroxide is 2.8-3%, and the proportion of sulfuric acid is 2.5-3%.

5. The method for removing phosphorus nickel plating according to claim 1, characterized in that: ； The phosphorus content of the phosphorus-nickel coating on the substrate is above 8%.

6. The method for removing a phosphorus-nickel coating according to claim 5, characterized in that: The invention is characterized in that the metal activity of the substrate is lower than that of iron.

7. A method for removing a phosphorus-nickel coating according to any one of claims 1 to 6, characterized in that: ； The phosphorus content of the phosphorus-nickel coating on the substrate is above 8%.

8. The method for removing a phosphorus-nickel coating according to claim 7, characterized in that: The feature of the invention is that the phosphorus nickel plating layer is a nickel plating layer produced by a chemical nickel deposition process.

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