Stripping and hanging method

Abstract

The invention discloses a stripping and hanging method. The stripping and hanging method is at least used for stripping and hanging a copper layer at a clamping opening of a conductive clamp in water electroplating. The stripping and hanging method comprises the following steps: a pretreatment step: carrying out pretreatment on the conductive clamp; a stripping and hanging step: the conductive clamp is placed in a stripping and hanging solution and kept for a first preset time so as to remove a copper layer at a clamp opening of the conductive clamp, the stripping and hanging solution is an acid solution, the acid solution comprises an oxidizing agent, a strong acid and urotropine, 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; and a post-processing step: taking out the conductive clamp, and carrying out post-processing. The stripping and hanging method can solve the problem that the stripping and hanging method in the prior art is low in efficiency when stripping and hanging are carried out on the copper layer on the conductive clamp.

Description

Technical Field

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

[0002] In the prior art, the preparation process of the composite current collector involves water electroplating, and common water electroplating devices are divided into conductive clamp type and conductive roller type. Among them, in the conductive clamp type water electroplating device, when the conductive clamp is used to clamp the film for electroplating, the conductive clamp will inevitably come into contact with the plating solution, causing the metal ions in the plating solution to be deposited on the surface of the conductive clamp, and eventually forming larger protruding particles or copper thorns, which in turn scratches, punctures, and even breaks the electroplated film, affecting the final product quality.

[0003] At present, the stripping methods for protruding particles or copper thorns at the clamping mouth of the conductive clip 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 has high cost; there is a problem that the electroplating solution causes serious corrosion to the conductive clip, resulting in the conductive clip being unable to be reused; some stripping methods will also have an adverse impact on the environment during use; and most of the stripping methods in the prior art have the problem of low stripping efficiency of the metal plating at the clamping mouth of the conductive clip. Summary of the invention

[0004] The main purpose of the present invention is to provide a stripping method, which at least solves the problem of low efficiency of the stripping method in the prior art when stripping the copper layer on the conductive clip.

[0005] According to one aspect of the present invention, a stripping method is provided, which is used at least to strip a copper layer at a clamping opening of a conductive clamp in water electroplating, and the stripping method comprises:

[0006] Pre-treatment step: pre-treating the conductive clip;

[0007] Stripping step: placing the conductive clip in a stripping solution and keeping it for a first predetermined time to remove the copper layer at the clamping mouth of the conductive clip, wherein the stripping solution is an acidic solution, the acidic solution includes an oxidant, a strong acid and urotropine, 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 the urotropine is [0.1, 0.5] g / L;

[0008] Post-processing step: taking out the conductive clip and performing post-processing.

[0009] Furthermore, in the peeling step, the temperature of the peeling liquid is [35,45]°C.

[0010] Furthermore, in the stripping step, while placing the conductive clip in the stripping liquid or after a second predetermined time, air or oxygen is introduced into the clamping opening of the conductive clip or into the stripping liquid.

[0011] Furthermore, the step of introducing air or oxygen into the clamping opening of the conductive clamp or into the stripping liquid comprises:

[0012] Using an ejector to continuously introduce air or oxygen into the clamping opening of the conductive clamp or into the stripping liquid; or,

[0013] Step S1: using an ejector to introduce air or oxygen into the jaws of the conductive clamp or into the stripping liquid for a third predetermined time; Step S2: stopping introducing air or oxygen into the jaws of the conductive clamp or into the stripping liquid for a fourth predetermined time, and then repeating steps S1 and S2 until the step of introducing air or oxygen into the jaws of the conductive clamp or into the stripping liquid for a fifth predetermined time.

[0014] Furthermore, in the peeling and hanging step, the first predetermined time is [25, 120] s.

[0015] Furthermore, the step of pre-processing the conductive clip includes:

[0016] Cleaning the conductive clip using a first solution;

[0017] The cleaned conductive clip is blown dry at a first predetermined temperature.

[0018] Furthermore, the first predetermined temperature is [20, 30]°C.

[0019] Furthermore, the first solution is a sulfuric acid solution, and the mass fraction of sulfuric acid in the sulfuric acid solution is [1%, 3%].

[0020] Furthermore, the step of post-processing the conductive clip includes:

[0021] Cleaning the conductive clip with a second solution;

[0022] The cleaned conductive clip is blown dry at a second predetermined temperature.

[0023] Furthermore, the second solution includes pure water and / or a sulfuric acid solution, wherein the mass fraction of sulfuric acid in the sulfuric acid solution is [3%, 7%].

[0024] Furthermore, the second predetermined temperature is [30, 40]°C.

[0025] Furthermore, the stripping step is performed simultaneously with the water electroplating. In the stripping step, the oxidant in the stripping solution is sodium persulfate, and the strong acid is sulfuric acid.

[0026] In the present invention, the conductive clip taken out from the electroplating solution is cleaned with a sulfuric acid solution having a mass fraction of sulfuric acid of [1%, 3%], and then the conductive clip is blown dry at [20, 30]°C with a pressurized blower. This pretreatment can effectively clean the electroplating solution remaining on the conductive clip and prevent contamination of the stripping solution. The conductive clip is cleaned with a sulfuric acid solution having a mass fraction of sulfuric acid of [1%, 3%], ensuring that the sulfuric acid in the stripping solution will not be diluted.

[0027] Then, the pre-treated conductive clip is placed in a stripping solution. In the stripping solution, the mass concentration of sodium persulfate is [100, 200] g / L, the volume concentration of sulfuric acid is [50, 100] mL / L, the mass concentration of urotropine is [0.1, 0.5] g / L, and the temperature is maintained at [35, 45] °C to ensure the activity of the stripping solution, which is beneficial for stripping the copper layer on the conductive clip. At the same time, an ejector is used to introduce air or oxygen into the clamping opening of the conductive clip or into the stripping solution, which is beneficial for efficiently stripping the copper layer on the conductive clip and improving the stripping efficiency. Through the above method, the copper layer on the conductive clip can be completely stripped off, avoiding scratches, punctures, or even film breakage of the electroplated film by the copper layer on the conductive clip, thereby improving the quality of the final product.

[0028] Finally, the stripped conductive clip is post-processed to effectively prevent the stripping liquid remaining on the conductive clip from contaminating the electroplating solution. The conductive clip is cleaned with pure water, then ultrasonically cleaned, and finally sprayed with a sulfuric acid solution with a mass fraction of [3%, 7%] of sulfuric acid. This can clean the stripping liquid remaining on the conductive clip without diluting the sulfuric acid in the electroplating solution. The cleaned conductive clip is blown dry at [30, 40]℃ using a pressurized fan and a heating pack to reduce the impact on the temperature of the electroplating solution and improve the efficiency of the electroplating process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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:

[0030] Figure 1 The present invention is a flowchart of a peeling and hanging method disclosed in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] 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.

[0032] 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.

[0033] 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.

[0034] As mentioned in the background technology, currently, the stripping methods for the raised particles or copper thorns at the clamping mouth of the conductive clip 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; there is a problem that the electroplating solution causes serious corrosion to the conductive clip, resulting in the conductive clip cannot be reused, and some stripping methods will also have an adverse impact on the environment during use, and most of the stripping methods in the prior art have the problem of low stripping efficiency of the metal plating at the clamping mouth of the conductive clip. To this end, the present invention provides a stripping method, which can solve the problem of low efficiency when stripping the copper layer on the conductive clip.

[0035] See also Figure 1 As shown, the present invention provides a stripping method, which is at least used for stripping the copper layer at the clamping mouth of the conductive clamp in water electroplating, and the stripping method comprises the following steps:

[0036] Pre-treatment step: pre-treat the conductive clip.

[0037] In the present application, the composition of the plating solution and the stripping solution is different. In order to avoid the residual plating solution on the conductive clip from contaminating the stripping solution, the conductive clip taken out of the plating solution is first cleaned with pure water, wherein the pure water is RO water (i.e., water treated by a reverse osmosis membrane), and then the conductive clip washed with pure water is cleaned with the first solution. Specifically, the first solution is a sulfuric acid solution, in which the mass fraction of sulfuric acid is [1%, 3%]. Exemplarily, the mass fraction of sulfuric acid in the sulfuric acid solution may be 1%, 2%, 3%, etc. In the present invention, a sulfuric acid solution having a mass fraction of sulfuric acid of 2% is preferably used to clean the plating solution attached to the clamping mouth of the conductive clip. Using a 2% sulfuric acid solution can reduce the effect of the cleaning solution on the concentration of the stripping solution. Finally, the cleaned conductive clip is dried at [20, 30]°C using a pressurized fan to reduce the effect on the concentration of the stripping solution. For example, the drying temperature can be 20°C, 25°C, 28°C, 30°C, etc. In the present application, the conductive clip can be dried at room temperature, which does not waste energy and does not increase production costs. The conductive clip is cleaned and dried before being placed in the stripping solution, which avoids contamination of the stripping solution by the components contained in the electroplating solution, thereby affecting the stripping effect of the stripping solution on the copper layer on the conductive clip.

[0038] In the present application, the stripping step is carried out simultaneously with water electroplating. In the stripping step, the conductive clip is placed in the stripping solution and maintained for a first predetermined time to remove the copper layer at the clamping mouth of the conductive clip. The stripping solution is an acidic solution, specifically, the acidic solution includes an oxidant, a strong acid and urotropine. 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 urotropine is [0.1,0.5] g / L. Under this reagent ratio, the copper layer on the conductive clip can be effectively stripped.

[0039] Specifically, the oxidant can oxidize the copper layer on the conductive clip. The mass concentration of the oxidant in this embodiment is [100,200] g / L, such as 100g / L, 110g / L, 150g / L, 160g / L, 180g / L, 200g / L, etc. The strong acid provides an acidic environment, which is conducive to the oxidation reaction. Exemplarily, the volume concentration of the strong acid can be 50mL / L, 60mL / L, 70mL / L, 90mL / L, 100mL / L, etc. Adding urotropine to the stripping liquid can not only improve the stripping efficiency of the metal coating on the conductive clip by the stripping liquid, but also protect the conductive clip from being corroded by the stripping liquid. Optionally, in this embodiment, the mass concentration of urotropine can be 0.1g / L, 0.2g / L, 0.3g / L, 0.4g / L, 0.5g / L, etc. In addition, the stripping liquid will not generate any substance harmful to the environment during the process of configuring and stripping the copper layer on the conductive clip.

[0040] 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 conductive clip.

[0041] 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 (SO4 - ·), SO4 - · has a pair of lone electrons, and its oxidizing ability exceeds that of sodium persulfate itself, and is almost the same as that of hydroxyl radical (·OH), and SO4 - The half-life is longer, reaching 4s at 40°C, which allows for more complete contact with pollutants and improves the degradation effect. The principle of the reaction between sodium persulfate and copper layer is: Cu+Na2S2O8→CuSO4+Na2SO4.

[0042] 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 this embodiment, the solution contains sulfuric acid. Therefore, in an acidic environment, the reaction principle of hydrogen peroxide and the copper layer is: Cu+H2SO4+H2O2→CuSO4+2H2O.

[0043] In an acid environment, the reaction principle between oxygen and copper layer is: 2Cu+O2→2CuO, CuO+H2SO4→CuSO4+H2O. The copper layer at the clamping mouth of the conductive clamp 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.

[0044] The relationship between the oxidizing properties of the above three substances is: sodium persulfate>hydrogen peroxide>oxygen. Therefore, in order to efficiently peel off the copper layer on the conductive clip, in this embodiment, sodium persulfate is preferably used as the oxidant.

[0045] 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 the 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 (NOX ), commonly known as Huanglong, seriously pollutes the environment, causes harm to the health of operators, and corrodes the containers containing the stripping liquid.

[0046] In summary, in the present invention, the stripping liquid is an acidic solution, and the acidic solution specifically has 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. The stripping liquid can effectively strip the copper layer on the conductive clip.

[0047] 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 at the clamping mouth of the conductive clamp after it is prepared, 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.

[0048] 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 conductive clip, 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 conductive clip. 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.

[0049] 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. In the present invention, the pH value affects the stripping efficiency of the stripping liquid on the copper layer on the conductive clip. When the pH value is higher than 3, the reaction between the stripping liquid and the copper layer on the conductive clip is inhibited, and it may even occur that the stripping liquid and the copper layer do not react.

[0050] In the present application, the conductive clip is placed in a stripping liquid and maintained for a first predetermined time to remove the copper layer at the jaws of the conductive clip. In the present embodiment, the temperature of the stripping liquid is [35,45]°C. For example, the temperature of the stripping liquid may be 35°C, 36°C, 38°C, 40°C, 45°C, etc. When the temperature of the stripping liquid is maintained within this range, the stripping liquid can increase the stripping rate of the copper layer at the jaws of the conductive clip. If the temperature of the stripping liquid is lower than 35°C, the activity of the stripping liquid will decrease, and the rate of reaction with the copper layer at the jaws of the conductive clip will decrease, increasing the stripping time; if the temperature is higher than 45°C, the stripping liquid may fail and cannot effectively strip the copper layer at the jaws of the conductive clip. Therefore, in the actual working process, the temperature of the stripping liquid needs to be controlled within a suitable range, which is conducive to increasing the stripping rate of the copper layer on the conductive clip.

[0051] Furthermore, when the stripping liquid is kept at a suitable temperature, the conductive clip is placed in the stripping liquid for a first predetermined time. In the present embodiment, the first predetermined time is preferably [25,120] s, for example, the first predetermined time may be 25s, 30s, 35s, 38s, 40s, 45s, 60s, 120s, etc. In the actual stripping process, if the temperature of the stripping liquid is kept within a suitable range, and the concentration of each component in the stripping liquid is kept within a set range, and the time for placing the conductive clip in the stripping liquid is less than 25s, the stripping liquid may not be able to completely strip the copper layer on the conductive clip; if the conductive clip is placed in the stripping liquid for more than 120s, the copper layer on the conductive clip has been completely stripped, and it has been in the stripping liquid, which will affect the remaining conductive clips to be stripped, increase the time of the entire stripping process, and cause a waste of resources.

[0052] In the present application, insufficient oxygen in the stripping liquid affects the rate of the stripping reaction. When the conductive clip is placed in the stripping liquid or after a second predetermined time, air or oxygen is introduced into the clamping opening of the conductive clip or into the stripping liquid. In the present invention, preferably, air or oxygen is introduced into the clamping opening of the conductive clip when the conductive clip is placed in the stripping liquid. This arrangement can accelerate the oxidation of the copper layer at the clamping opening of the conductive clip, thereby making it easier to react with the stripping liquid and increasing the stripping rate of the copper layer.

[0053] In the present invention, the injection of oxygen can be provided by an ejector or a microbubble generator, etc. The ejector has a simple structure and is easy to operate. In the present application, the preferred oxygen or air supply device is an ejector. The working principle of the ejector is as follows: based on the dynamic characteristics of the fluid, when the pressurized fluid enters the nozzle of the ejector to form a high-speed jet, the liquid passing through the jet channel increases in speed, resulting in a decrease in absolute pressure, thereby generating a vacuum inside the ejector. This vacuum effect allows the liquid or gas additive to be thoroughly mixed into the water flow. The ejector shears, crushes, and emulsifies the air in the inhaled gas or liquid through the combined action of a strong negative pressure and a high-speed jet, greatly increasing the specific surface area of ​​the bubbles and reducing the mass transfer resistance, thereby effectively completing the mass transfer process of gas and water, and providing support for oxygenation in the peeling liquid.

[0054] The steps of introducing air or oxygen using an ejector include:

[0055] Use an ejector to continuously introduce air or oxygen into the clamping opening of the conductive clamp or into the stripping liquid. The following steps may also be included, wherein step S1: use an ejector to introduce air or oxygen into the clamping opening of the conductive clamp or into the stripping liquid for a third predetermined time; step S2: stop introducing air or oxygen into the clamping opening of the conductive clamp or into the stripping liquid for a fourth predetermined time, and then repeat step S1 and step S2 until the fifth predetermined time. It is understood that the third predetermined time, the fourth predetermined time, and the fifth predetermined time mentioned here are related to the thickness of the copper layer to be stripped, which can be determined based on experiments, and are not specifically limited in this application.

[0056] In the present invention, it is preferred to continuously introduce air or oxygen into the jaws of the conductive clamp using an ejector. In the actual production and processing process, a pump with a matching air intake volume and liquid circulation volume is selected, so that air is continuously supplied during the entire stripping process, and the oxidation rate of the copper layer is accelerated, thereby increasing the stripping rate of the copper layer. Continuously introducing air or oxygen during stripping promotes the oxidation reaction of the copper layer at the jaws of the conductive clamp, is more conducive to the removal of the copper layer, and increases the stripping rate of the copper layer at the jaws of the conductive clamp.

[0057] Post-processing steps: Take out the conductive clip and perform post-processing.

[0058] In the present application, since the composition of the stripping liquid and the electroplating liquid is different, the stripping liquid remaining on the conductive clip is avoided from polluting the electroplating liquid, and the conductive clip taken out from the stripping liquid is cleaned with a second solution. Among them, the second solution includes pure water and sulfuric acid solution. First, it is washed with pure water, and the pure water is RO water (i.e., water treated with a reverse osmosis membrane), and the stripping liquid remaining on the conductive clip is rinsed off. Then it is ultrasonically cleaned, and the ultrasonic cleaning is also cleaned with pure water. An ultrasonic cleaning nozzle is provided at the bottom of the cleaning tank. The ultrasonic cleaning is used to further clean the stripping liquid between the gaps at the clamping mouth of the conductive clip, and avoid contamination of the electroplating liquid. Finally, it is sprayed and rinsed. It is worth noting that during the spray rinsing, a sulfuric acid solution with a mass fraction of sulfuric acid of [3%, 7%] is used for cleaning. For example, the mass fraction of sulfuric acid in the sulfuric acid solution can be 3%, 4%, 5%, 6%, 7%, etc. In the present invention, it is preferred that the sulfuric acid solution with a mass fraction of sulfuric acid of 5% is used to spray and rinse the conductive clip. This arrangement is because the conductive clip needs to be returned to the electroplating tank after peeling and used for water electroplating of the composite current collector. The mass fraction of sulfuric acid in the electroplating solution in the electroplating tank is [3%, 7%]. The use of a sulfuric acid solution with a mass fraction of 5% sulfuric acid will not dilute the sulfuric acid in the electroplating solution, and will not affect the electroplating effect of the composite current collector during the water electroplating process.

[0059] Furthermore, the cleaned conductive clip is blown dry at a temperature of [30,40]°C using a pressurized fan, for example, the temperature can be 30°C, 32°C, 34°C, 35°C, 40°C, etc. The use of a pressurized fan can increase the drying speed of the conductive clip. If the temperature needs to be controlled at this stage, a heating pack is set at the outlet of the pressurized fan, which can effectively adjust the required temperature so that the temperature of the conductive clip is kept within the required range. After drying, the liquid in the cleaning step can be reduced from entering the electroplating solution, and the conductive clip can reduce the impact on the two ends of the composite current collector. Since the temperature of the electroplating solution is [30,40]°C, the conductive clip is blown dry at this temperature to reduce the impact of the conductive clip on the temperature of the electroplating solution when it enters the electroplating solution, improve the efficiency of electroplating, and thus ensure the quality of the conductive film.

[0060] In order to verify the stripping effect of the stripping liquid of the present invention on the copper layer on the conductive clip, the present invention provides the following specific embodiments and comparative examples:

[0061] Example 1

[0062] The conductive clip taken out from the electroplating solution is first cleaned with pure water, which is RO water (i.e., water treated by a reverse osmosis membrane), and then cleaned with a sulfuric acid solution with a mass fraction of 2%, and finally dried with a pressurized fan at [20,30]°C. The dried conductive clip is placed in a stripping solution for stripping.

[0063] Add pure water accounting for 60% of the volume of the container into a fixed container, 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.

[0064] 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 35°C.

[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 120 seconds.

[0066] Take the stripped conductive clip out of the stripping liquid, wash off the stripping liquid attached to the conductive clip with pure water, then use ultrasonic cleaning, and finally spray rinse the conductive clip with a sulfuric acid solution with a mass fraction of 5%. Use a pressurized fan to blow dry the conductive clip at [30,40]℃ after spraying. Put the dried conductive clip into the electroplating tank.

[0067] Example 2

[0068] The stripping liquid of Example 2 is substantially the same as that of Example 1, except that in this example, the temperature of the stripping liquid is 45°C.

[0069] 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.

[0070] Example 3

[0071] The stripping solution of Example 3 is substantially the same as that of Example 2, except that, in this example, the mass concentration of sodium persulfate in the stripping solution is 150 g / L.

[0072] 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.

[0073] Example 4

[0074] The stripping solution of Example 4 is substantially the same as that of Example 2, except that, in this example, the mass concentration of sodium persulfate in the stripping solution is 200 g / L.

[0075] 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.

[0076] Example 5

[0077] The stripping solution of Example 5 is substantially the same as that of Example 4, except that, in this example, the volume concentration of sulfuric acid in the stripping solution is 100 mL / L.

[0078] 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.

[0079] Example 6

[0080] The stripping solution of Example 6 is substantially the same as that of Example 5, except that, in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.2 g / L.

[0081] 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.

[0082] Example 7

[0083] The stripping solution of Example 7 is substantially the same as that of Example 5, except that in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.3 g / L.

[0084] 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.

[0085] Example 8

[0086] The stripping solution of Example 8 is substantially the same as that of Example 5, except that in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.4 g / L.

[0087] 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.

[0088] Example 9

[0089] The stripping solution of Example 9 is substantially the same as that of Example 5, except that in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.5 g / L.

[0090] 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.

[0091] Comparative Example 1

[0092] The stripping liquid of Comparative Example 1 is substantially the same as that of Example 1, except that in this example, the temperature of the stripping liquid is 25°C.

[0093] 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 180 seconds.

[0094] Comparative Example 2

[0095] The stripping liquid of Comparative Example 2 is substantially the same as that of Example 1, except that in this example, the temperature of the stripping liquid is 55°C.

[0096] 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.

[0097] Comparative Example 3

[0098] The stripping solution of Comparative Example 3 is substantially the same as that of Example 2, except that, in this example, the mass concentration of sodium persulfate in the stripping solution is 250 g / L.

[0099] 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.

[0100] Comparative Example 4

[0101] The stripping solution of Comparative Example 4 is substantially the same as that of Example 4, except that, in this example, the volume concentration of sulfuric acid in the stripping solution is 150 mL / L.

[0102] 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.

[0103] Comparative Example 5

[0104] The stripping solution of Comparative Example 5 is substantially the same as that of Example 6, except that, in this example, the mass concentration of hexamethylenetetramine in the stripping solution is 0.6 g / L.

[0105] 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.

[0106] According to the above examples and comparative examples, Table 1 is as follows:

[0107] Table 1:

[0108]

[0109]

[0110] According to Table 1: By comparing Example 1 and Example 2, it can be seen that as the temperature of the stripping liquid increases, the time it takes for the stripping liquid 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 on the conductive clip by the stripping liquid.

[0111] By comparing Examples 2 to 4, it can be seen that 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 preparation of the composite current collector becomes shorter, thereby improving the stripping rate of the copper layer on the conductive clip by the stripping solution.

[0112] By comparing Example 4 and Example 5, it can be seen that the mass concentrations of sodium persulfate and hexamethylenetetramine in the stripping solution remain unchanged. As the volume concentration of sulfuric acid 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 on the conductive clip by the stripping solution.

[0113] By comparing Examples 5 to 9, 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 improving the stripping rate of the copper layer on the conductive clip by the stripping solution.

[0114] By comparing Table 1, Example 1, Example 2, Comparative Example 1 and Comparative Example 2, it can be found that when the temperature of the stripping liquid gradually increases to 55° C., the stripping time of the 1 μm copper layer on the conductive clip by the stripping liquid first decreases and then remains unchanged.

[0115] By comparing Table 1, Examples 2 to 4, and Comparative Example 3, 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.

[0116] By comparing Table 1, Example 4, Example 5 and Comparative Example 4, 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 on the conductive clip first decreases and then remains unchanged.

[0117] By comparing Table 1, Examples 5 to 9 and Comparative Example 5, 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.

[0118] Specifically, the temperature of the stripping liquid affects the activity of the stripping liquid. When the temperature of the stripping liquid is low, the stripping time of the copper layer on the conductive clip by the stripping liquid is long, which affects the stripping process. When the temperature of the stripping liquid increases, the activity of the stripping liquid is increased, and the stripping of the copper layer on the conductive clip by the stripping liquid is accelerated. However, it is worth noting that the temperature of the stripping liquid affects the material components in the stripping liquid. When the temperature of the stripping liquid is too high, the sodium persulfate in the stripping liquid will decompose, thereby inactivating the stripping liquid and failing to oxidize the copper layer.

[0119] Furthermore, if the amount of material components added to the stripping solution is too large, the stripping rate of the copper layer will first increase and then remain unchanged. This is 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, so there is no promoting effect on the reaction.

[0120] In summary, the stripping liquid made of sodium persulfate, sulfuric acid and urotropine of the present invention keeps the concentration of each material component in the stripping liquid within a certain range, improves the activity of the stripping liquid, and can realize efficient stripping of the copper layer on the conductive clip. 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 radical exists in the form of ions. When it contacts the copper layer on the conductive clip, 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 realize rapid stripping of the copper layer on the conductive clip, improve the stripping efficiency, and ensure that the conductive clip 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 on the conductive clip immediately after the preparation is completed, thereby improving the stripping effect of the stripping liquid on the copper layer on the conductive clip.

[0121] The present invention experiments the stripping efficiency of the copper layer on the conductive clip by configuring stripping liquids of different concentrations. The experimental data are analyzed and shown that: in the stripping liquid prepared by sodium persulfate, sulfuric acid and urotropine, when the temperature of the stripping liquid is kept within a suitable range, an ejector is used to continuously provide air or oxygen to the stripping liquid, and the stripping liquid can realize efficient stripping of the copper layer on the conductive clip and other workpieces. If the temperature of the stripping liquid is too high, the stripping liquid will be inactivated, and the stripping of the copper layer on the conductive clip cannot be realized. At the same time, 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 suitable 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, while maintaining a suitable temperature, the concentration of various substances needs to maintain a suitable range value, thereby realizing efficient stripping of the copper layer on the conductive clip without causing waste of resources.

[0122] It can be known from the above embodiments and comparative examples that in the present application, the conductive clip taken out from the electroplating solution is firstly cleaned with a sulfuric acid solution having a mass fraction of sulfuric acid of [1%, 3%] in the sulfuric acid solution, and then the conductive clip is blown dry with a pressurized blower. This pre-treatment can effectively clean the electroplating solution remaining on the conductive clip, prevent contamination of the stripping solution, and use a sulfuric acid solution having a mass fraction of sulfuric acid of [1%, 3%] to clean the conductive clip, ensuring that the sulfuric acid in the stripping solution will not be diluted.

[0123] Then, the pre-treated conductive clip is placed in a stripping solution. In the stripping solution, the mass concentration of sodium persulfate is [100, 200] g / L, the volume concentration of sulfuric acid is [50, 100] mL / L, the mass concentration of urotropine is [0.1, 0.5] g / L, and the temperature is maintained at [35, 45] °C, which can ensure the activity of the stripping solution and is conducive to stripping the copper layer on the conductive clip. And an ejector is used to introduce air or oxygen into the conductive clip opening or the stripping solution. This is conducive to efficiently stripping the copper layer on the conductive clip and improves the stripping efficiency. Through the above method, the copper layer on the conductive clip can be completely stripped off, avoiding scratches, punctures, or even film breakage caused by the copper layer on the conductive clip, thereby improving the quality of the final product.

[0124] Finally, the post-processing of the stripped conductive clip can effectively avoid the contamination of the electroplating solution. The conductive clip is first cleaned with pure water, then ultrasonically cleaned, and finally sprayed with a sulfuric acid solution with a mass fraction of [3%, 7%] of sulfuric acid to clean the residual stripping liquid on the conductive clip. The cleaned conductive clip is blown dry at [30, 40] ℃ using a pressurized fan and a heating pack, which reduces the impact on the temperature of the electroplating solution and improves the efficiency of the electroplating process.

[0125] 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 stripping method, which is used at least for stripping the copper layer at the clamping mouth of the conductive clamp in water electroplating, characterized in that: The peeling and hanging method comprises: Pre-treatment step: pre-treating the conductive clip; Stripping step: placing the conductive clip into a stripping solution and keeping it for a first predetermined time to remove the copper layer at the clamping mouth of the conductive clip, wherein the stripping solution is an acidic solution, the acidic solution comprises an oxidant, a strong acid and hexamethylenetetramine, 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 the hexamethylenetetramine is [0.1, 0.5] g / L; Post-processing step: taking out the conductive clip and performing post-processing.

2. The peeling and hanging method according to claim 1, characterized in that: In the peeling step, the temperature of the peeling liquid is [35,45]°C.

3. The peeling and hanging method according to claim 2, characterized in that: In the stripping step, at the same time when the conductive clip is placed in the stripping liquid or after a second predetermined time, air or oxygen is introduced into the clamping opening of the conductive clip or into the stripping liquid.

4. The peeling and hanging method according to claim 3, characterized in that: The step of introducing air or oxygen into the clamping opening of the conductive clamp or into the stripping liquid comprises: Use an ejector to continuously introduce air or oxygen into the jaws of the conductive clamp or the stripping liquid; or, step S1: use an ejector to introduce air or oxygen into the jaws of the conductive clamp or the stripping liquid for a third predetermined time; step S2: stop introducing air or oxygen into the jaws of the conductive clamp or the stripping liquid for a fourth predetermined time, then repeat steps S1 and S2 until the step of introducing air or oxygen into the jaws of the conductive clamp or the stripping liquid reaches a fifth predetermined time.

5. The peeling and hanging method according to any one of claims 1 to 4, characterized in that: In the peeling and hanging step, the first predetermined time is [25, 120] s.

6. The peeling and hanging method according to any one of claims 1 to 4, characterized in that: The step of pre-treating the conductive clip comprises: Cleaning the conductive clip using a first solution; The cleaned conductive clip is blown dry at a first predetermined temperature.

7. The peeling and hanging method according to claim 6, characterized in that: The first predetermined temperature is [20, 30]°C.

8. The peeling and hanging method according to claim 6, characterized in that: The first solution is a sulfuric acid solution, and the mass fraction of sulfuric acid in the sulfuric acid solution is [1%, 3%].

9. The peeling and hanging method according to any one of claims 1 to 4, 7 and 8, characterized in that: The step of post-processing the conductive clip comprises: Cleaning the conductive clip with a second solution; The cleaned conductive clip is blown dry at a second predetermined temperature.

10. The peeling and hanging method according to claim 9, characterized in that: The second solution includes pure water and / or a sulfuric acid solution, wherein the mass fraction of sulfuric acid in the sulfuric acid solution is [3%, 7%].

11. The peeling and hanging method according to claim 9, characterized in that: The second predetermined temperature is [30, 40]°C.

12. The peeling and hanging method according to any one of claims 1 to 4, 7, 8, 10 and 11, characterized in that: The stripping step is carried out simultaneously with the water electroplating. In the stripping step, the oxidant in the stripping solution is sodium persulfate, and the strong acid is sulfuric acid.

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