Stripping hanging liquid and preparation method thereof

Abstract

The invention discloses a stripping and hanging liquid and a preparation method of the stripping and hanging liquid. The stripping and hanging liquid comprises an acid solution, wherein the acid solution comprises an oxidizing agent, strong acid and urotropine; wherein the mass concentration of the oxidizing agent is [100, 200] g / L, the volume concentration of the strong acid is [50, 100] mL / L, and the mass concentration of the urotropine is [0.1, 0.5] g / L. The stripping and hanging liquid and the preparation method of the stripping and hanging liquid can solve the problem of low stripping and hanging efficiency of a stripping and hanging liquid on a metal coating on a workpiece in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of chemical stripping, in particular to a stripping liquid and a method for preparing the stripping liquid. Background Art

[0002] During the electroplating process, a coating will be deposited on the supporting workpiece. The workpiece needs to be used repeatedly, so the coating needs to be completely stripped off.

[0003] At present, the stripping methods for the raised particles or copper thorns at the clamping mouth of the conductive clamp in the prior art mainly include electrolytic stripping method and chemical stripping method. However, the electrolytic stripping method in the prior art is complicated to operate and the cost is too high. In the chemical stripping method, when the existing stripping liquid is used to strip the metal coating, it is easy to have the adverse effect of corrosion on the workpiece; some stripping liquids are added with concentrated nitric acid or ammonium nitrate and other ingredients, which are easy to produce a large amount of harmful gases during the actual stripping process and are easy to explode when heated, causing certain pollution to the environment and causing harm to the human body. In addition, the stripping liquid in the prior art has a low efficiency in stripping the metal coating on the surface of the workpiece. Summary of the invention

[0004] The main purpose of the present invention is to provide a stripping liquid and a method for preparing the stripping liquid, which at least solves the problem of low stripping efficiency of the metal coating on the workpiece by the stripping liquid in the prior art.

[0005] According to one aspect of the present invention, there is provided a stripping liquid, comprising:

[0006] an acidic solution comprising an oxidant, a strong acid and hexamethylenetetramine;

[0007] Wherein, the mass concentration of the oxidant is [100, 200] g / L, the volume concentration of the strong acid is [50, 100] mL / L, and the mass concentration of hexamethylenetetramine is [0.1, 0.5] g / L.

[0008] Furthermore, the oxidant includes sodium persulfate or hydrogen peroxide.

[0009] Furthermore, the strong acid includes one of hydrochloric acid, sulfuric acid or nitric acid.

[0010] Furthermore, the pH value of the stripping solution is (0,3].

[0011] Furthermore, the stripping solution also includes copper ions.

[0012] Furthermore, the copper ions are copper ions provided by copper sulfate or copper nitrate.

[0013] Furthermore, the mass concentration of the copper sulfate is [3,7] g / L.

[0014] On the other hand, the present invention also provides a method for preparing a stripping liquid, the stripping liquid preparation method includes the above-mentioned stripping liquid, and the stripping liquid preparation method includes the following steps:

[0015] Step S11: adding pure water into the container;

[0016] Step S12: adding sulfuric acid into the container while stirring;

[0017] Step S13: adding sodium persulfate into the container and stirring to completely dissolve the sodium persulfate;

[0018] Step S14: adding hexamethylenetetramine to the container and stirring to completely dissolve the hexamethylenetetramine;

[0019] Step S15: adding copper sulfate to the container and stirring to completely dissolve the copper sulfate to obtain a stripping solution in which the mass concentration of the sodium persulfate is [100, 200] g / L, the volume concentration of the sulfuric acid is [50, 100] mL / L, and the mass concentration of the urotropine is [0.1, 0.5] g / L.

[0020] Furthermore, in the step S11, the volume of the pure water accounts for 60% of the volume of the container.

[0021] Furthermore, in the step S12, after adding the sulfuric acid into the container, the temperature in the container is lowered to (0,30]°C.

[0022] In the present invention, the stripping liquid made of sodium persulfate, sulfuric acid and urotropine can realize the stripping of the copper layer at the clamp mouth of the conductive clamp. Among them, sulfuric acid provides an acidic environment, and sodium persulfate is used as an oxidant in the solution. After being dissolved in water, the persulfate ion exists in the form of ions. When it contacts the copper layer at the clamp mouth of the conductive clamp, the copper layer can be oxidized so that the copper layer exists in the form of copper ions in the stripping liquid, thereby achieving the effect of removing the copper layer. And urotropine is both a promoter and a corrosion inhibitor in the stripping liquid. Hexamine can promote the stripping liquid to realize rapid stripping of the copper layer at the clamp mouth of the conductive clamp, improve the stripping efficiency, and ensure that the conductive clamp is basically not corroded by the stripping liquid. In addition, copper sulfate is also added to the stripping liquid, so that the stripping liquid can be used to strip the copper layer at the clamp mouth of the conductive clamp immediately after the preparation is completed, thereby improving the stripping rate of the copper layer at the clamp mouth of the conductive clamp by the stripping liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0024] Figure 1The present invention is a flow chart of a method for preparing a peeling liquid disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0027] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0028] As mentioned in the background art, a coating will be deposited on the workpiece during the electroplating process, and the workpiece needs to be used repeatedly, so the coating needs to be completely stripped off. When the stripping liquid in the prior art strips the metal coating, it is easy to have an adverse effect of corrosion on the workpiece with the metal coating. Some stripping liquids add ingredients such as concentrated nitric acid or ammonium nitrate. In the actual production process, a large amount of harmful gases are easily generated and explosive decomposition occurs when heated, which causes certain pollution to the environment and harm to the human body. In addition, the stripping rate of the metal coating by the stripping liquid is low. Therefore, the present invention provides a stripping liquid, which reduces the use of the types of agents, and has the advantages of improving the stripping efficiency of the stripping liquid on the metal coating on the workpiece such as the conductive clip, and protecting the workpiece such as the conductive clip from being almost corroded by the stripping liquid.

[0029] Specifically, the stripping solution in the present application is an acidic solution.

[0030] In the present application, the acidic solution includes an oxidant, a strong acid and hexamethylenetetramine; wherein the mass concentration of the oxidant is

[0031] [100,200]g / L, the volume concentration of strong acid is [50,100]mL / L, and the mass concentration of urotropine is [0.1,0.5]g / L.

[0032] In the present application, by adopting oxidant, the copper layer on workpiece is oxidized. Optionally, the mass concentration of the oxidant in the present embodiment is between 100g / L and 200g / L, such as 100g / L, 110g / L, 150g / L, 160g / L, 180g / L, 200g / L etc. Strong acid provides an acidic environment, is conducive to the carrying out of oxidation reaction. Optionally, the volume concentration of the strong acid in this implementation is between 50mL / L and 100mL / L, such as 50mL / L, 60mL / L, 70mL / L, 90mL / L, 100mL / L etc. Adding urotropine in the stripping liquid can not only improve the stripping efficiency of the metal coating on the workpiece by the stripping liquid, but also can protect the conductive clip from being corroded by the stripping liquid. Optionally, in this embodiment, the mass concentration of hexamethylenetetramine is between 0.1 g / L and 0.5 g / L, such as 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, etc. In addition, the stripping liquid does not produce any environmentally harmful substances during the preparation and stripping of the copper layer on the workpiece.

[0033] In the present application, the oxidant may be sodium persulfate, hydrogen peroxide (commonly known as hydrogen peroxide), or oxygen introduced into the stripping solution through a device, as long as the oxidant can oxidize the copper layer on the workpiece.

[0034] Among them, sodium persulfate has good stability, water solubility, strong oxidizing property, and the friendliness of reaction products, which can make up for the shortcomings of other oxidants. Sodium persulfate decomposition can generate new active substances: sulfate free radicals (SO 4 - ·), SO 4 - · has a pair of lone pairs of electrons, and its oxidizing ability exceeds that of sodium persulfate itself, and is almost the same as that of hydroxyl radicals (·OH), and SO 4 - The half-life of · is longer, and the half-life can reach 4s at 40°C, which can more fully contact with pollutants and improve the degradation effect. In the present invention, the reaction principle of sodium persulfate and copper layer is: Cu+Na 2 S 2 O 8 →

[0035] CuSO 4+Na 2 SO 4 .

[0036] Hydrogen peroxide has oxidizing and reducing properties. Its oxidation, reduction or decomposition products are water and (or) oxygen, which can be called a clean redox agent. Hydrogen peroxide can be used as an oxidant, bleaching agent, disinfectant, dechlorinating agent, and is also used to make rocket fuel, peroxides and foam plastics. In the present invention, the solution contains sulfuric acid. Therefore, in an acidic environment, the reaction principle of hydrogen peroxide and the copper layer is: Cu+H 2 SO 4 +H 2 O 2 →CuSO 4 +2H 2 O.

[0037] In an acid environment, the reaction principle between oxygen and copper layer is: 2Cu+O 2 →2CuO,CuO+H 2 SO 4 →CuSO 4 +H 2 O. The copper layer on the surface of the workpiece is oxidized into copper oxide, and the copper oxide reacts with sulfuric acid in the solution to generate copper sulfate, thereby achieving the purpose of removing the copper layer.

[0038] The relationship between the oxidizing properties of the above three substances is: sodium persulfate>hydrogen peroxide>oxygen. Therefore, in order to efficiently strip the copper layer on the workpiece, in this embodiment, sodium persulfate is preferably used as the oxidant.

[0039] In the present application, the strong acid may be hydrochloric acid, sulfuric acid, or nitric acid. In the present invention, sulfuric acid is preferably used as a strong acid. Since the electroplating solution in water electroplating is a sulfuric acid solution, in order to prevent the conductive clip from being not cleaned after peeling or from being directly introduced into the electroplating solution due to incorrect operation without being cleaned and dried after peeling, other ions are introduced to contaminate the electroplating solution, thereby affecting the electroplating effect of the composite current collector. In addition, if concentrated nitric acid is used as a strong acid to maintain an acidic environment, the concentrated nitric acid is both an acid and a strong oxidant when reacting with copper, and a large amount of harmful gases (NO X ), commonly known as Huanglong, seriously pollutes the environment, causes harm to the health of operators, and corrodes the containers containing the stripping liquid.

[0040] In the present application, the stripping liquid is a strongly acidic solution with a pH value of (0,3]. Optionally, the pH value can be 1, 2, 3, etc., as long as the pH value of the stripping liquid is less than or equal to 3. The pH value affects the stripping efficiency of the stripping liquid on the copper layer at the clamping mouth of the conductive clamp. When the pH value is higher than 3, the reaction between the stripping liquid and the copper layer at the clamping mouth of the conductive clamp will be inhibited, and it may even occur that the stripping liquid and the copper layer do not react.

[0041] In the present application, the stripping solution also includes copper ions, which are obtained by dissolving copper sulfate in the stripping solution. When the stripping solution contains a certain concentration of copper ions, the stripping solution can be used to strip the copper layer on the surface of the workpiece after preparation, and the stripping efficiency is high. Exemplarily, the copper-containing substance can be copper sulfate, copper nitrate, etc. In this embodiment, the strong acid in the stripping solution is sulfuric acid. In order not to introduce other ions to affect the activity of the stripping solution, the copper-containing substance is preferably copper sulfate.

[0042] Further, the mass concentration of copper sulfate is [3,7] g / L. Exemplarily, the mass concentration of copper sulfate can be 3g / L, 4g / L, 5g / L, 6g / L, 7g / L, etc. In the present invention, the mass concentration of copper sulfate is preferably 5g / L. When the mass concentration of copper sulfate is less than 5g / L, when the stripping solution is prepared and used to strip the copper layer on the workpiece, it takes a long time for the stripping solution to have a stripping effect on the copper layer. When the mass concentration of copper sulfate reaches 5g / L, when the stripping solution is prepared and used to strip the copper layer, the stripping solution can immediately achieve the stripping effect on the copper layer. The concentration of copper ions has a certain influence on the stripping process. If the concentration of added copper ions is too high, it may inhibit the reaction of the stripping solution with the copper layer on the workpiece. Therefore, the amount of copper sulfate added to promote the stripping solution to be prepared and can be used to achieve stripping needs to be kept within a suitable range.

[0043] In order to verify the technical effect of the peeling liquid of the present invention, the present invention provides the following specific embodiments and comparative examples:

[0044] Example 1

[0045] Add pure water that accounts for 60% of the volume of the container into a fixed container, the pure water is RO water (i.e., water treated by a reverse osmosis membrane), add sulfuric acid into the pure water, and reduce the temperature of the sulfuric acid solution in the container to (0,30]°C; add sodium persulfate into the sulfuric acid solution and stir until it is completely dissolved; then add hexamethylenetetramine and stir until it is completely dissolved; finally, add copper sulfate and stir until it is completely dissolved to obtain a stripping solution.

[0046] In this embodiment, the sulfuric acid is concentrated sulfuric acid with a purity of 98%, the mass concentration of sodium persulfate in the stripping solution is 100 g / L, the volume concentration of sulfuric acid is 50 mL / L, the mass concentration of hexamethylenetetramine is 0.1 g / L, and the temperature of the stripping solution is 45°C.

[0047] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 60 seconds.

[0048] Example 2

[0049] The stripping solution of Example 2 is substantially the same as that of Example 1, except that, in this example, the mass concentration of sodium persulfate in the stripping solution is 150 g / L.

[0050] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 55 seconds.

[0051] Example 3

[0052] The stripping solution of Example 3 is substantially the same as that of Example 1, except that, in this example, the mass concentration of sodium persulfate in the stripping solution is 200 g / L.

[0053] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 45 seconds.

[0054] Example 4

[0055] The stripping solution of Example 4 is substantially the same as that of Example 3, except that, in this example, the volume concentration of sulfuric acid in the stripping solution is 100 mL / L.

[0056] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 40 seconds.

[0057] Example 5

[0058] The stripping solution of Example 5 is substantially the same as that of Example 4, except that, in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.2 g / L.

[0059] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 38 seconds.

[0060] Example 6

[0061] The stripping solution of Example 6 is substantially the same as that of Example 4, except that, in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.3 g / L.

[0062] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 35 seconds.

[0063] Example 7

[0064] The stripping solution of Example 7 is substantially the same as that of Example 4, except that, in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.4 g / L.

[0065] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 30 seconds.

[0066] Example 8

[0067] The stripping solution of Example 8 is substantially the same as that of Example 4, except that, in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.5 g / L.

[0068] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the preparation of the composite current collector, the time taken to strip the 1 μm thick copper layer is 25 seconds.

[0069] Comparative Example 1

[0070] The stripping solution of Comparative Example 1 is substantially the same as that of Example 1, except that, in this example, the mass concentration of sodium persulfate in the stripping solution is 250 g / L.

[0071] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 45 seconds.

[0072] Comparative Example 2

[0073] The stripping solution of Comparative Example 2 is substantially the same as that of Example 3, except that, in this example, the volume concentration of sulfuric acid in the stripping solution is 150 mL / L.

[0074] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector, the time taken to strip the 1 μm thick copper layer is 40 seconds.

[0075] Comparative Example 3

[0076] The stripping solution of Comparative Example 3 is substantially the same as that of Example 4, except that, in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.6 g / L.

[0077] When the stripping solution in this embodiment is used to strip the conductive clip having a 1 μm copper layer used in the preparation of the composite current collector, the time taken to strip the 1 μm thick copper layer is 25 seconds.

[0078] According to the above examples and comparative examples, Table 1 is as follows:

[0079] Table 1:

[0080] Serial number Sodium persulfate (g / L) Sulfuric acid (mL / L) Hexamethylenetetramine(g / L) Reaction temperature (℃) Reaction time(s) Example 1 100 50 0.1 45 60 Example 2 150 50 0.1 45 55 Example 3 200 50 0.1 45 45 Example 4 200 100 0.1 45 40 Example 5 200 100 0.2 45 38 Example 6 200 100 0.3 45 35 Example 7 200 100 0.4 45 30 Example 8 200 100 0.5 45 25 Comparative Example 1 250 50 0.1 45 45 Comparative Example 2 200 150 0.1 45 40 Comparative Example 3 200 100 0.6 45 25

[0081] According to Table 1: By comparing Example 1, Example 2 and Example 3, it can be seen that when the volume concentration of sulfuric acid and the mass concentration of urotropine in the stripping solution remain unchanged, as the mass concentration of sodium persulfate increases, the time for the stripping solution to strip the conductive clip having a 1 μm copper layer used in the process of preparing the composite current collector becomes shorter, thereby increasing the stripping rate of the copper layer at the clamping mouth of the conductive clip by the stripping solution.

[0082] By comparing Example 3 and Example 4, it can be seen that the mass concentrations of sodium persulfate and hexamethylenetetramine in the stripping liquid remain unchanged. As the volume concentration of sulfuric acid increases, the time for the stripping liquid to strip the conductive clip having a 1 μm copper layer used in the preparation of the composite current collector becomes shorter, thereby increasing the stripping rate of the copper layer at the clamping mouth of the conductive clip by the stripping liquid.

[0083] By comparing Examples 5 to 8, it can be seen that the mass concentration of sodium persulfate and the volume concentration of sulfuric acid in the stripping solution remain unchanged. As the mass concentration of hexamine increases, the time for the stripping solution to strip the conductive clip having a 1 μm copper layer used in the preparation of the composite current collector becomes shorter, thereby increasing the stripping rate of the copper layer at the clamping mouth of the conductive clip by the stripping solution.

[0084] By comparing Table 1, Examples 1 to 3, and Comparative Example 1, it can be found that when the mass concentration of sodium persulfate in the stripping solution is too large (i.e., the mass concentration of sodium persulfate is greater than 250 g / L), and the concentrations of other substances remain unchanged, the stripping time of the 1 μm copper layer on the conductive clip by the stripping solution first decreases and then remains unchanged.

[0085] By comparing Table 1, Example 3, Example 4 and Comparative Example 2, it is found that when the mass concentrations of sodium persulfate and hexamethylenetetramine in the stripping solution remain unchanged, the volume concentration of sulfuric acid is increased (that is, the volume concentration of sulfuric acid is increased to 150 mL / L), the time for the stripping solution to completely strip the copper layer at the clamping mouth of the conductive clamp first decreases and then remains unchanged.

[0086] By comparing Table 1, Examples 5 to 8 and Comparative Example 3, it is found that when the concentrations of sodium persulfate and sulfuric acid in the stripping solution remain unchanged, the concentration of urotropine is too large (i.e., the mass concentration of urotropine reaches 0.6 g / L), and the time for the stripping solution to completely strip the 1 μm thick copper layer on the conductive clip first decreases and then remains unchanged.

[0087] Specifically, the above situation occurs mainly because the solute has a fixed solubility in the solution at a certain temperature. The present application selects the most suitable temperature to prevent the decomposition of sodium persulfate and the inactivation of the stripping solution. At this temperature, the solubility of sodium persulfate, sulfuric acid and hexamethylenetetramine in the stripping solution reaches a saturated state. If these substances are further added, the mass concentration of the solution will not change, and therefore the reaction will not be promoted.

[0088] In summary, the stripping liquid made of sodium persulfate, sulfuric acid and urotropine can achieve the stripping effect of the copper layer at the clamp mouth of the conductive clamp. Among them, sulfuric acid provides an acidic environment, and sodium persulfate is used as an oxidant in the solution. After being dissolved in water, the persulfate ion exists in the form of ions. When it contacts the copper layer at the clamp mouth of the conductive clamp, the copper layer can be oxidized so that the copper layer exists in the form of ions in the stripping liquid, thereby achieving the effect of removing the copper layer. And urotropine is both a promoter and a corrosion inhibitor in the stripping liquid. Hexamine can promote the stripping liquid to achieve rapid stripping of the copper layer at the clamp mouth of the conductive clamp, improve the stripping efficiency, and ensure that the conductive clamp is basically not corroded by the stripping liquid. In addition, copper sulfate is also added to the stripping liquid, so that the stripping liquid can be used to strip the copper layer at the clamp mouth of the conductive clamp immediately after the preparation is completed, thereby improving the stripping effect of the stripping liquid on the copper layer at the clamp mouth of the conductive clamp.

[0089] The present invention experiments the stripping efficiency of the copper layer at the clamping mouth of the conductive clamp by preparing stripping liquids of different concentrations. By analyzing the experimental data, the experimental results show that the stripping liquid prepared by sodium persulfate, sulfuric acid and urotropine can realize the stripping of the copper layer on the workpiece such as the conductive clamp. However, in the stripping liquid, the addition amount of sodium persulfate, sulfuric acid and urotropine has an influence on the stripping efficiency. Specifically, when the concentration of the added substance exceeds the maximum value of the appropriate range, the solubility of various substances in the stripping liquid reaches the maximum value, thereby having no promoting effect on the stripping of the copper layer. Therefore, in the actual production process, the concentration of various substances needs to maintain a suitable range value, so that the copper layer at the clamping mouth of the conductive clamp can be stripped efficiently without causing waste of resources.

[0090] like Figure 1 As shown, the present invention also provides a method for preparing a stripping liquid, which is used to prepare the above-mentioned stripping liquid. Specifically, the method for preparing the stripping liquid in this embodiment includes the following steps:

[0091] Step S11: Add pure water into the container.

[0092] When executing step S11, pure water can be added by a water injection pipe. In the present application, pure water is RO water (i.e., water treated by a reverse osmosis membrane). It is worth noting that in the present application, the volume of pure water added accounts for 60% of the volume of the container, mainly to prevent pure water from splashing out due to stirring when adding solutes, causing the concentration of the stripping liquid to change, thereby causing the stripping efficiency of the stripping liquid to decrease when stripping the copper layer.

[0093] Step S12: Add sulfuric acid into the container while stirring.

[0094] Sulfuric acid is added to a container in which pure water accounts for 60%. In the present application, the sulfuric acid is concentrated sulfuric acid with a purity of 98% (analytical pure). Stirring is performed with an agitator while adding. Exemplarily, the types of agitators include: propeller agitators, turbine agitators, paddle agitators, anchor agitators, etc., and the specific type is selected according to the actual processing. Since concentrated sulfuric acid releases heat immediately when added to pure water, if the amount added at one time is too large and stirring is not performed, safety accidents may occur. In addition, if the amount of concentrated sulfuric acid added at one time is too large, sulfuric acid mist will be generated while generating heat, which is harmful to the personal safety and health of the operator. In the actual preparation process of the stripping liquid, if the volume of sulfuric acid added is large, it can be added in small amounts multiple times, with an interval of time, and the next addition of sulfuric acid will be performed after the temperature of the solution in the container cools to a predetermined temperature. It is worth noting that in the present application, after the concentrated sulfuric acid is added, the temperature in the container needs to be reduced to (0,30]°C before adding sodium persulfate. For example, the temperature in the container can be reduced to 10°C, 20°C, 30°C, etc. This setting prevents the sodium persulfate from decomposing due to excessive temperature, thereby causing the stripping liquid to be inactivated and the copper layer at the clamping mouth of the conductive clip cannot be stripped.

[0095] Specifically, the cooling method includes natural cooling and forced cooling. Natural cooling is usually used in some quantitative experiments, and the natural cooling time is longer. Forced cooling methods include air cooling, water cooling and ice salt cooling. In the present application, the preferred cooling method is forced cooling, which accelerates the cooling of the solution, reduces the time required in the preparation process, and improves work efficiency.

[0096] Step S13: Add sodium persulfate into a container and stir to completely dissolve the sodium persulfate.

[0097] Add the prepared sodium persulfate to the solution that has been added with concentrated sulfuric acid, and stir with a stirrer, so as to accelerate the dissolution of sodium persulfate in the solution and improve work efficiency. Sodium persulfate acts as an oxidant in the solution. After being dissolved in water, persulfate exists in the form of ions. When it comes into contact with the copper layer at the clamping mouth of the conductive clamp, it can oxidize the copper layer so that the copper layer at the clamping mouth of the conductive clamp exists in the form of copper ions in the stripping solution, achieving the effect of removing the copper layer.

[0098] Step S14: adding hexamethylenetetramine into the container and stirring to completely dissolve the hexamethylenetetramine.

[0099] A certain amount of hexamethylenetetramine is added to the solution of sulfuric acid and sodium persulfate. Hexamethylenetetramine is both a promoter and a corrosion inhibitor in the stripping solution. Hexamethylenetetramine can promote the stripping solution to quickly strip the copper layer at the clamping mouth of the conductive clip, thereby improving the stripping efficiency. In addition, hexamethylenetetramine can also ensure that the conductive clip is basically not corroded by the stripping solution.

[0100] Step S15: Add copper sulfate into the container and stir to completely dissolve the copper sulfate to obtain a stripping solution having a mass concentration of sodium persulfate of [100, 200] g / L, a volume concentration of sulfuric acid of [50, 100] mL / L, and a mass concentration of hexamethylenetetramine of [0.1, 0.5] g / L.

[0101] A certain amount of copper sulfate is added to the solution of sulfuric acid, sodium persulfate and hexamethylenetetramine. The copper ion concentration in the stripping solution affects the stripping effect of the stripping solution on the copper layer at the clamping mouth of the conductive clamp. When the stripping solution does not contain copper ions, the reaction time is long when the stripping solution strips the copper layer at the clamping mouth of the conductive clamp, which affects the stripping reaction rate. When the prepared stripping solution contains a certain amount of copper ions, when the stripping solution is prepared and used to strip the copper layer, the stripping solution can immediately achieve the stripping effect on the copper layer, thereby improving the stripping efficiency.

[0102] It can be seen from the above embodiments that the present invention can at least achieve the following technical effects:

[0103] (1) In the stripping solution provided by the present invention, the mass concentration of sodium sulfate is [100, 200] g / L, the volume concentration of sulfuric acid is [50, 100] mL / L, and the mass concentration of hexamethylenetetramine is [0.1, 0.5] g / L, which can achieve efficient stripping of the copper layer on workpieces such as conductive clips;

[0104] (2) In the method for preparing the stripping solution provided by the present invention, adding an appropriate amount of copper sulfate can promote the stripping solution to be used for stripping the copper layer on the workpiece after the stripping solution is prepared, thereby enhancing the stripping effect of the stripping solution on the copper layer on the workpiece.

[0105] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A peeling liquid, characterized in that: include: an acidic solution comprising an oxidant, a strong acid and hexamethylenetetramine; Wherein, the mass concentration of the oxidant is [100, 200] g / L, the volume concentration of the strong acid is [50, 100] mL / L, and the mass concentration of hexamethylenetetramine is [0.1, 0.5] g / L.

2. The peeling liquid according to claim 1, characterized in that: The oxidizing agent includes sodium persulfate or hydrogen peroxide.

3. The peeling liquid according to claim 1 or 2, characterized in that: The strong acid includes one of hydrochloric acid, sulfuric acid or nitric acid.

4. The peeling liquid according to claim 1 or 2, characterized in that: The pH value of the stripping solution is (0,3].

5. The peeling liquid according to claim 1 or 2, characterized in that: The stripping solution also contains copper ions.

6. The peeling liquid according to claim 5, characterized in that: The copper ions are copper ions provided by copper sulfate or copper nitrate.

7. The peeling liquid according to claim 6, characterized in that: The mass concentration of the copper sulfate is [3,7] g / L.

8. A method for preparing the stripping solution according to any one of claims 1 to 7, comprising the following steps: Step S11: adding pure water into the container; Step S12: adding sulfuric acid into the container while stirring; Step S13: adding sodium persulfate into the container and stirring to completely dissolve the sodium persulfate; Step S14: adding hexamethylenetetramine to the container and stirring to completely dissolve the hexamethylenetetramine; Step S15: adding copper sulfate to the container and stirring to completely dissolve the copper sulfate to obtain a stripping solution in which the mass concentration of the sodium persulfate is [100, 200] g / L, the volume concentration of the sulfuric acid is [50, 100] mL / L, and the mass concentration of the urotropine is [0.1, 0.5] g / L.

9. The method for preparing a stripping liquid according to claim 8, characterized in that: In the step S11, the volume of the pure water accounts for 60% of the volume of the container.

10. The method for preparing a stripping liquid according to claim 8 or 9, characterized in that: In the step S12, after adding the sulfuric acid into the container, the temperature in the container is lowered to (0,30]°C.

Images