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: carrying out pretreatment on the conductive clamp; the conductive clamp is placed in the stripping and hanging liquid and kept for a first preset time to remove a copper layer at a clamp opening of the conductive clamp, meanwhile, the concentration of copper ions in the stripping and hanging liquid is monitored, and when the concentration of the copper ions is higher than a first set value, the copper ions in the stripping and hanging liquid are electrolyzed to enable the concentration of the copper ions in the stripping and hanging liquid to be smaller than or equal to the first set value; and taking out the conductive clamp, and carrying out post-treatment. According to the stripping and hanging method, the problem of low stripping and hanging efficiency caused by too high copper ion concentration in a stripping and hanging method in the prior art can be solved.

Description

Technical Field

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

[0002] During the water electroplating process of the conductive film, a coating is easily deposited on the supporting conductive clip. The conductive clip needs to be used repeatedly, so the coating needs to be completely stripped off with a stripping liquid.

[0003] At present, 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 too costly, and the stripping liquid causes serious corrosion to the conductive clip, resulting in the conductive clip being unable to be reused; in addition, some stripping methods will also have an adverse impact on the environment during use. Moreover, in most of the stripping methods in the prior art, after a period of stripping, the metal ion concentration in the stripping liquid is relatively high, and the metal ion concentration has an impact on the stripping efficiency of the metal coating on the conductive clip. When the metal ion concentration is too high, the reaction between the stripping liquid and the metal coating is inhibited. 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 stripping efficiency caused by excessively high copper ion concentration in the stripping method in the prior art.

[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-processing the conductive clip;

[0007] Placing the conductive clip into a stripping solution and keeping it for a first predetermined time to remove the copper layer at the clamping opening of the conductive clip, and monitoring the concentration of copper ions in the stripping solution at the same time, and electrolyzing the copper ions in the stripping solution according to a predetermined setting;

[0008] The conductive clip is taken out and post-processed.

[0009] Furthermore, in the predetermined setting, the copper ion concentration in the stripping solution is [5,100) g / L.

[0010] Furthermore, in the step of electrolyzing the copper ions in the stripping solution, pure copper is used as the cathode pole and an insoluble anode is used as the anode pole.

[0011] Furthermore, in the step of electrolyzing the copper ions in the stripping solution, the current density of the power supply connected between the anode pole and the cathode pole is [0.5, 0.9] A / dm 2 .

[0012] Furthermore, the step of placing the conductive clamp into the stripping liquid and keeping it for a first predetermined time to remove the copper layer at the clamping mouth of the conductive clamp, monitoring the copper ion concentration in the stripping liquid is performed in a first container, and the step of electrolyzing the copper ions in the stripping liquid is performed in a second container, and a pumping mechanism is provided between the first container and the second container.

[0013] Furthermore, the first predetermined time is [25, 120] s.

[0014] Furthermore, the conductive clip is placed in a stripping liquid and maintained for a first predetermined time to remove the copper layer at the clamping mouth of the conductive clip, wherein the stripping liquid is an acidic solution, the acidic solution includes sodium persulfate, sulfuric acid and urotropine, 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.

[0015] Furthermore, the temperature of the stripping liquid is [35,45]°C.

[0016] Furthermore, 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.

[0017] Furthermore, the step of introducing air or oxygen into the clamping opening of the conductive clamp or into the stripping liquid comprises:

[0018] Using an ejector to continuously introduce air or oxygen into the clamping opening of the conductive clamp or into the stripping liquid; or,

[0019] 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.

[0020] In the present invention, the conductive clip taken out from the electroplating solution is cleaned by using a sulfuric acid solution with a mass fraction of pure water and sulfuric acid of [1%, 3%], and then the conductive clip is blown dry at [20, 30]°C by a pressurized blower. This pretreatment can effectively clean the electroplating solution remaining on the conductive clip and prevent contamination of the stripping solution. In addition, the conductive clip is cleaned by using a sulfuric acid solution with a mass fraction of sulfuric acid of [1%, 3%], which ensures that the sulfuric acid in the stripping solution will not be diluted.

[0021] Then, the pre-treated conductive clip is placed in the first container. The stripping liquid in the first container 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 urotropine of [0.1, 0.5] g / L. The temperature is maintained at [35, 45] °C, which can ensure the activity of the stripping liquid and is conducive to stripping the copper layer on the conductive clip. At the same time, an ejector is used to introduce air or oxygen into the clamping mouth of the conductive clip or the stripping liquid. This is conducive to efficiently stripping the copper layer on the conductive clip and improves the stripping efficiency. A copper ion sensor is used to monitor the copper ion concentration in the stripping liquid in the first container in real time. When the copper ion concentration in the stripping liquid is too high, the pumping mechanism is started to transport the stripping liquid to the second container for electrolysis. When the copper ion concentration is about 5 g / L, the electrolysis is stopped to prevent the stripping liquid from stripping the copper layer on the conductive clip and affecting the stripping rate. By electrolysis, the copper ion concentration in the stripping solution is maintained at [5,100) g / L. This is beneficial to improving the stripping efficiency of the copper layer on the conductive clip by the stripping solution. By the above method, the copper layer on the conductive clip can be completely stripped, avoiding scratches, punctures and even film breakage of the electroplated film by the copper layer on the conductive clip, thereby improving the quality of the final product.

[0022] Finally, the post-processing of the stripped conductive clip can effectively avoid the contamination of the electroplating solution. Specifically, 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 to reduce the impact on the temperature of the electroplating solution and improve the efficiency of the electroplating process. 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 1 The present invention is a flowchart of a peeling and hanging method 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 technology, the stripping methods for the raised particles or copper thorns at the clamp 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 serious corrosion of the electroplating solution to the conductive clip, which makes the conductive clip unable to 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 a high metal ion concentration in the stripping solution after a period of stripping, and the metal ion concentration has an impact on the stripping efficiency of the metal coating on the conductive clip. When the metal ion concentration is too high, it will inhibit the reaction between the stripping solution and the metal coating. To this end, the present invention provides a stripping method, which can monitor the copper ion concentration in the stripping solution while realizing the stripping of the copper layer on the upper surface of the conductive clip, and electrolyze the stripping solution to keep the copper ion concentration within a suitable range, which helps to improve the stripping efficiency.

[0029] 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:

[0030] Pre-treatment step: pre-treat the clamping mouth of the conductive clip;

[0031] 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 cleaned conductive clip 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%] (referring to 1% ≤ mass fraction of sulfuric acid ≤ 3%). Exemplarily, the mass fraction of sulfuric acid may be 1%, 2%, 3%, etc. In the present invention, a sulfuric acid solution having a mass fraction of 2% of sulfuric acid in the sulfuric acid solution is preferably used to clean the plating solution attached to the clamping mouth of the conductive clip. Using a sulfuric acid solution having a mass fraction of 2% of sulfuric acid can reduce the effect of the cleaning solution on the concentration of the stripping solution. The cleaned conductive clip is then dried at [20, 30]°C using a pressurized fan to reduce the effect of the liquid on the concentration of the stripping solution. Optionally, the drying temperature can be 20°C, 25°C, 26°C, 30°C, etc. The conductive clip can be dried at room temperature without additional heating. The conductive clip is cleaned and dried before being placed in the stripping solution to prevent the components contained in the electroplating solution from contaminating the stripping solution, thereby affecting the stripping effect of the stripping solution on the copper layer on the conductive clip.

[0032] Stripping step: placing the conductive clip into the stripping liquid and keeping it for a first predetermined time to remove the copper layer at the clamping mouth of the conductive clip, and simultaneously monitoring the copper ion concentration in the stripping liquid, and electrolyzing the copper ions in the stripping liquid according to the predetermined setting.

[0033] In the present application, 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.

[0034] Specifically, the oxidant oxidizes 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, during the preparation of the stripping liquid and the process of stripping the copper layer on the conductive clip, no substances harmful to the environment are generated.

[0035] 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.

[0036] 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 sodium persulfate on the copper layer is: Cu+Na2S2O8→CuSO4+Na2SO4.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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 (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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 reaction time of stripping; 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.

[0046] Furthermore, the conductive clip is placed in the stripping liquid and maintained for a first predetermined time. In the present invention, the first predetermined time is

[0047] [25,120]s, illustratively, 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 solution is maintained within a suitable range, and the concentrations of the components in the stripping solution are maintained within a set range, if the time for placing the conductive clip in the stripping solution is less than 25s, the stripping solution may not be able to completely strip the copper layer on the conductive clip; if the time for placing the conductive clip in the stripping solution is greater than 120s, the copper layer on the conductive clip has been completely stripped and has been in the stripping solution, which will affect the remaining conductive clips to be stripped, increase the time of the entire stripping process, and cause waste of resources.

[0048] In the present application, insufficient oxygen in the stripping liquid will affect 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.

[0049] In the present invention, the injection of oxygen or air can be provided by an ejector or a microbubble generator. 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.

[0050] The steps of introducing air or oxygen using an ejector include:

[0051] 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 can be 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.

[0052] 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.

[0053] In the present application, while the stripping is being performed and the copper ion concentration in the stripping solution is monitored at the same time, the copper ions in the stripping solution are electrolyzed according to a predetermined setting, so that the copper ion concentration in the stripping solution is maintained within a first set value range. Specifically, the predetermined setting for starting the electrolysis includes: the first: monitoring the copper ion concentration in the stripping solution, and determining whether to start the electrolysis program according to the value of the copper ion concentration; the second: periodically starting the electrolysis according to the copper ion concentration; the third: electrolyzing the stripping solution all the time. In the present application, the preferred electrolysis starting method is to determine whether to perform the electrolysis according to the copper ion concentration.

[0054] Exemplarily, the copper ion concentration monitoring device can be a copper ion sensor. Specifically, the first set value is [5,100) g / L. For example, the first set value of the copper ion concentration in the stripping liquid can be 5 g / L, 10 g / L, 50 g / L, 60 g / L, 90 g / L, etc. If the copper ion concentration in the stripping liquid is too high, it will inhibit the stripping effect of the stripping liquid on the copper layer on the conductive clip; if the copper ion concentration in the stripping liquid is too low, the stripping rate of the copper layer on the conductive clip by the stripping liquid is very low, and even the copper layer on the conductive clip cannot be stripped. Specifically, when it is monitored that the copper ion concentration in the stripping liquid is greater than or equal to 100 g / L, the copper ion concentration in the stripping liquid is too high, which will inhibit the stripping liquid from continuing to react with the copper layer on the conductive clip, reducing the stripping rate, so it is necessary to electrolyze the copper ions in the stripping liquid. When the copper ion sensor detects that the copper ion concentration in the stripping solution is lower than 5.0g / L, electrolysis needs to be stopped. Because when the copper ion concentration is lower than 5.0g / L, the activity of the stripping solution will be affected, affecting the stripping rate and stripping effect of the copper layer at the clamping mouth of the conductive clamp.

[0055] In the present application, the electrolysis device and the stripping device can be arranged in the same container, or they can be arranged separately in two containers. If the electrolysis device and the stripping device are arranged in the same container, the anode pole and the cathode pole in the electrolysis device will occupy the space in the container, resulting in the stripping process being affected. In addition, since the conductive clip itself is also charged, if the electrolysis process is carried out in the stripping tank, it will conflict with the stripping reaction of the copper layer on the conductive clip, affecting the stripping efficiency. Therefore, in the present invention, a first container and a second container are arranged respectively. The stripping device is arranged in the first container, and the electrolysis device is arranged in the second container, and the step of electrolyzing the copper ions in the stripping liquid is performed in the second container. Copper ion sensors are arranged in both the first container and the second container, and a pumping mechanism is arranged between the first container and the second container, so as to facilitate the transportation of the stripping liquid and electrolysis and recycling thereof. Specifically, when the copper ion sensor detects that the copper ion concentration in the stripping liquid in the first container is greater than or equal to 100g / L, the pumping mechanism is started to transport the stripping liquid in the first container to the second container. When the copper ion sensor in the second container detects that the copper ion concentration is greater than or equal to 100g / L, the electrolysis device is started to electrolyze the copper ions in the stripping liquid.

[0056] Furthermore, in the electrolysis step, the cathode pole uses pure copper and the anode pole uses an insoluble anode. With such a configuration, after the stripping solution is electrolyzed, copper ions are deposited on the cathode pole, and copper can be recovered without further separation. In copper smelting, electrolysis has two purposes: (1) extracting copper from a copper-containing solution; (2) purifying copper from crude copper, that is, separating copper from crude copper containing impurities. In this embodiment, the electrolysis process is mainly to extract copper from a copper-containing solution, and is called electrolytic deposition. This avoids the effect of introducing new copper ions from the pole on the copper ion concentration in the stripping solution, so the anode pole is an insoluble pole. Specifically, the insoluble anode pole includes a graphite electrode, a lead dioxide electrode (PbO2 metal electrode, PbO2 / plastic electrode, PbO2 / ceramic electrode, PbO2 / graphite electrode, etc.), a titanium anode metal oxide coating electrode, etc. In the actual production process, any one of them can be used.

[0057] Furthermore, the specific principle of electrolysis is: the anode pole is used to transfer current to the stripping solution, so that the copper sulfate (CuSO4) in the stripping solution is decomposed into copper ions (Cu 2+ ) and sulfate (SO4 2- ), copper ions gain electrons (e) at the cathode and are reduced to metallic copper, which is deposited on the cathode. The specific principle is: the copper sulfate solution produced during peeling and hanging, after power is applied, H + and Cu 2+ Move to the cathode, where Cu 2+ +2e -=Cu, thereby reducing the copper ion concentration in the stripping solution, reducing the inhibitory effect of high concentration copper ions on stripping, and thus improving the removal efficiency of the copper layer at the clamping mouth of the conductive clamp by the stripping solution.

[0058] Specifically, in the step of electrolyzing the copper ions in the stripping solution, the current density of the power supply connected between the anode pole and the cathode pole is [0.5, 0.9] A / dm 2 For example, the current density may be 0.5 A / dm 2 , 0.6A / dm 2 , 0.7A / dm 2 , 0.8A / dm 2 , 0.9A / dm 2 In the electrolysis step, if the current density is less than 0.5A / dm 2 When the current density is too small, less than or equal to 0.1A / dm 2 When the current density is greater than 1.0A / dm 2 When the current density is too large, the copper electrolyzed on the cathode pole will turn into powder, which is not conducive to the collection of the electrolyzed copper.

[0059] Post-processing steps: Take out the conductive clip and perform post-processing.

[0060] 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 again after peeling and hanging 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 sulfuric acid in the sulfuric acid solution of 5% 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.

[0061] 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.

[0062] In order to verify the stripping effect of the stripping solution of the present invention on the copper layer on the conductive clip, explore the influence of the copper ion concentration in the stripping solution on the stripping reaction and the influence of the current density between the anode pole and the cathode pole on the electrolysis efficiency of the copper ions, the present invention provides the following specific embodiments and comparative examples:

[0063] Example 1

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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 then 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. The dried conductive clip enters the electroplating tank.

[0069] Example 2

[0070] 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.

[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 60 seconds.

[0072] Example 3

[0073] 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.

[0074] 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 55 seconds.

[0075] Example 4

[0076] 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.

[0077] 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.

[0078] Example 5

[0079] 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.

[0080] 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.

[0081] Example 6

[0082] 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.

[0083] 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.

[0084] Example 7

[0085] 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.

[0086] 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.

[0087] Example 8

[0088] 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.

[0089] 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.

[0090] Example 9

[0091] 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.

[0092] 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.

[0093] Example 10

[0094] The stripping solution of Example 10 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 6 g / L.

[0095] 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.

[0096] Embodiment 11

[0097] The stripping solution of Example 11 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 10 g / L.

[0098] 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.

[0099] Example 12

[0100] The stripping solution of Example 12 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 20 g / L.

[0101] 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.

[0102] Example 13

[0103] The stripping solution of Example 13 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 50 g / L.

[0104] 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.

[0105] Embodiment 14

[0106] The stripping solution of Example 14 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 70 g / L.

[0107] 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.

[0108] Embodiment 15

[0109] The stripping solution of Example 15 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 80 g / L.

[0110] 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.

[0111] Example 16

[0112] The stripping solution of Example 16 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 90 g / L.

[0113] 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.

[0114] Embodiment 17

[0115] The stripping liquid of Example 17 is substantially the same as that of Example 11, except that in this example, 0.5 A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0116] When using 0.5A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 6 g / L, and the efficiency of electrolytic copper is 40%.

[0117] Embodiment 18

[0118] The stripping liquid of Example 18 is substantially the same as that of Example 11, except that in this example, 0.6A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0119] When using 0.6A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 5g / L, and the efficiency of electrolytic copper is 50%.

[0120] Embodiment 19

[0121] The stripping liquid of Example 19 is substantially the same as that of Example 11, except that in this example, 0.7A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0122] When using 0.7A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 4 g / L, and the efficiency of electrolytic copper is 60%.

[0123] Embodiment 20

[0124] The stripping liquid of Example 20 is substantially the same as that of Example 11, except that in this example, 0.8 A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0125] When using 0.8A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 3g / L, and the efficiency of electrolytic copper is 70%.

[0126] Embodiment 21

[0127] The stripping liquid of Example 21 is substantially the same as that of Example 11, except that in this example, 0.9A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0128] When using 0.9A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 2g / L, and the efficiency of electrolytic copper is 80%.

[0129] Comparative Example 1

[0130] 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.

[0131] 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.

[0132] Comparative Example 2

[0133] 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.

[0134] 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.

[0135] Comparative Example 3

[0136] 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.

[0137] 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.

[0138] Comparative Example 4

[0139] 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.

[0140] 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.

[0141] Comparative Example 5

[0142] 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.

[0143] 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.

[0144] Comparative Example 6

[0145] The stripping solution of Comparative Example 6 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 3 g / L.

[0146] 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.

[0147] Comparative Example 7

[0148] The stripping solution of Comparative Example 7 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 4 g / L.

[0149] 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.

[0150] Comparative Example 8

[0151] The stripping solution of Comparative Example 8 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 100 g / L.

[0152] 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 27 seconds.

[0153] Comparative Example 9

[0154] The stripping solution of Comparative Example 9 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 101 g / L.

[0155] 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.

[0156] Comparative Example 10

[0157] The stripping solution of Comparative Example 10 is substantially the same as that of Example 9, except that, in this example, the mass concentration of copper ions in the stripping solution is 110 g / L.

[0158] 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.

[0159] Comparative Example 11

[0160] The stripping liquid of Comparative Example 11 is substantially the same as that of Example 11, except that in this example, 0.1 A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0161] When using 0.1A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 10g / L, and the efficiency of electrolytic copper is 0.

[0162] Comparative Example 12

[0163] The stripping liquid of Comparative Example 12 is substantially the same as that of Example 11, except that in this example, 0.2 A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0164] When using 0.2A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 9 g / L, and the efficiency of electrolytic copper is 10%.

[0165] Comparative Example 13

[0166] The stripping liquid of Comparative Example 13 is substantially the same as that of Example 11, except that in this example, 0.3A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0167] When using 0.3A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 8 g / L, and the efficiency of electrolytic copper is 20%.

[0168] Comparative Example 14

[0169] The stripping liquid of Comparative Example 14 is substantially the same as that of Example 11, except that in this example, 0.4A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0170] When using 0.4A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 7 g / L, and the efficiency of electrolytic copper is 30%.

[0171] Comparative Example 15

[0172] The stripping liquid of Comparative Example 15 is substantially the same as that of Example 11, except that in this example, 1.0 A / dm 2 The copper ions in the stripping solution were electrolyzed with a current of , and the electrolysis time was 10 min.

[0173] When using 1.0A / dm 2 The copper ion concentration in the stripping solution is electrolyzed with a current of . After 10 minutes of electrolysis, the copper ion concentration in the stripping solution is 2g / L, and the efficiency of electrolytic copper is 80%.

[0174] According to the above examples and comparative examples, Table 1, Table 2 and Table 3 are as follows:

[0175] Table 1:

[0176] Serial number Sodium persulfate(g / L) Sulfuric acid (mL / L) Hexamethylenetetramine(g / L) Reaction temperature (℃) Reaction time(s) Example 1 100 50 0.1 35 120 Example 2 100 50 0.1 45 60 Example 3 150 50 0.1 45 55 Example 4 200 50 0.1 45 45 Example 5 200 100 0.1 45 40 Example 6 200 100 0.2 45 38 Example 7 200 100 0.3 45 35 Example 8 200 100 0.4 45 30 Example 9 200 100 0.5 45 25 Comparative Example 1 100 50 0.1 25 180 Comparative Example 2 100 50 0.1 55 60 Comparative Example 3 250 50 0.1 45 45 Comparative Example 4 200 150 0.1 45 40 Comparative Example 5 200 100 0.6 45 25

[0177] 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.

[0178] 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 increasing the stripping rate of the copper layer on the conductive clip by the stripping solution.

[0179] 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.

[0180] 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.

[0181] 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 increases (that is, when the temperature of the stripping liquid reaches 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.

[0182] 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.

[0183] 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.

[0184] 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.

[0185] 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.

[0186] Furthermore, when the amount of the substance components added to the stripping solution is too large, the stripping rate of the copper layer first increases and then remains 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.

[0187] Table 2:

[0188]

[0189]

[0190] By comparing Table 2 and Examples 9 to 16, it can be seen that, when the concentration of the components in the stripping solution is kept constant and the temperature is kept constant, as the copper ion concentration in the stripping solution increases, when it is between 5 g / L and 100 g / L (excluding 100 g / L), the copper ion concentration has no obvious inhibitory effect on the stripping reaction. However, it is worth noting that when the copper ion concentration in the stripping solution reaches 100 g / L, the copper ion concentration in the stripping solution inhibits the stripping reaction between the stripping solution and the copper layer on the conductive clip, and the time required for the stripping reaction becomes longer and longer.

[0191] By comparing Table 2, Examples 9 to 16, and Comparative Examples 6 to 10, it can be seen that when the copper ion concentration in the stripping solution is lower than 5 g / L, the stripping reaction is limited by the low copper ion concentration, and the rate of the stripping reaction is low. Specifically, the time for the stripping solution to completely strip the 1 μm thick copper layer on the conductive clip shows a trend of gradually decreasing; when the copper ion concentration in the stripping solution is higher than 100 g / L, the time for the stripping solution to completely strip the 1 μm thick copper layer on the conductive clip shows a trend of gradually increasing. This shows that when the copper ion concentration in the stripping solution is too high, the stripping reaction is inhibited.

[0192] Specifically, the copper ion concentration in the stripping liquid affects the stripping rate of the copper layer on the conductive clip by the stripping liquid. When the copper ion concentration in the stripping liquid is lower than 5g / L, the stripping rate of the copper layer on the conductive clip by the stripping liquid is low, and it takes a long time to completely strip the copper layer. When the copper ion concentration in the stripping liquid is greater than or equal to 100g / L, the stripping rate of the copper layer on the conductive clip by the stripping liquid also appears to be inhibited. As the copper ion concentration gradually increases, the time to completely strip the copper layer on the conductive clip becomes longer and longer, which is not conducive to the stripping reaction. Therefore, it is necessary to electrolyze the stripping liquid to promote the stripping of the copper layer on the conductive clip by the stripping liquid. It is worth noting that during the electrolysis process, it is also necessary to monitor the concentration of copper ions in the stripping liquid in real time. When the copper ion concentration is lower than 5g / L, it is necessary to stop the electrolysis immediately to avoid the copper ion concentration in the stripping liquid being too low, resulting in the rate of the stripping reaction being affected.

[0193] Table 3:

[0194]

[0195]

[0196] By comparing Table 3, Examples 17 to 21, and Comparative Examples 11 to 15, it can be seen that as the current density increases, the electrolytic copper efficiency gradually increases. However, when the current density increases to 1.0 A / dm 2 When the efficiency of electrolytic copper is 0.9A / dm 2 The electrolytic copper efficiency remains unchanged. However, when the current density is 0.1A / dm 2 When the current density is too small, the copper ions in the stripping solution cannot be electrolyzed. Therefore, in the actual electrolysis process, the current density in the electrolysis step needs to be reasonably controlled to ensure the electrolysis step.

[0197] In summary, the stripping liquid made of sodium persulfate, sulfuric acid and urotropine of the present invention, the concentration of each material component in the stripping liquid is maintained within a certain range, and the copper layer on the conductive clip can be efficiently stripped. 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 on the conductive clip, the copper layer can be oxidized so that the copper layer exists in the stripping liquid in the form of ions, 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.

[0198] The present invention experiments the stripping efficiency of the copper layer on the conductive clip by preparing 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, during the stripping process, an ejector is used to continuously provide air or oxygen to the clamping mouth of the conductive clip or in the stripping liquid, which is conducive to the stripping liquid to efficiently strip the copper layer on the conductive clip and other workpieces. It is worth noting that 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 achieved. At the same time, in the stripping liquid, the addition amount of sodium persulfate, sulfuric acid and urotropine has an impact on the stripping efficiency. Specifically, when the concentration of the added substance exceeds the maximum value of the suitable range, the solubility of various substance components 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, so that the copper layer on the conductive clip can be efficiently stripped without causing waste of resources.

[0199] The present invention verifies the influence of copper ion concentration on the stripping reaction by changing the concentration of copper ions in the stripping solution in the stripping solution with the same concentration of material components. Through the analysis of experimental data, the results show that when the copper ion concentration in the stripping solution is less than 5g / L, the stripping rate of the copper layer on the conductive clip by the stripping solution is low, and the time required for the reaction is long. When the copper ion concentration is between 5g / L and 100g / L (excluding 100g / L), the influence of the copper ion concentration on the stripping reaction does not change significantly. However, when the copper ion concentration is greater than or equal to 100g / L, the copper ion concentration increases, suppresses the progress of the stripping reaction, and the time required for the reaction is getting longer and longer. Therefore, it is necessary to monitor the copper ion concentration in the stripping solution in real time, and when the copper ion concentration is greater than or equal to 100g / L, immediately start the pumping mechanism to transport the stripping solution to the second container for electrolysis.

[0200] The present invention also verifies the influence of current density on electrolytic copper by setting up experiments. The experimental data show that when the current density is less than or equal to 0.1A / dm 2 When the current density is greater than 0.9A / dm 2 When the current density is less than 0.5A / dm, the electrolytic copper efficiency reaches the maximum value. If the current density is further increased, the copper ions in the stripping solution cannot be electrolyzed. 2 When the current density is greater than 0.9A / dm 2When the current density is too high, the copper electrolyzed will become powder, which is not conducive to collection. Therefore, when electrolyzing the copper ions in the stripping solution, it is necessary to select a suitable current density to facilitate the electrolysis of copper ions and the collection of electrolytic copper.

[0201] 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 with a mass fraction of pure water and sulfuric acid of [1%, 3%], 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 to prevent contamination of the stripping solution. The conductive clip is cleaned with a sulfuric acid solution with a mass fraction of sulfuric acid of [1%, 3%] to ensure that the sulfuric acid in the stripping solution will not be diluted.

[0202] The pre-treated conductive clip is then placed in a first container, wherein the stripping solution in the first container 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 urotropine of

[0203] [0.1,0.5]g / L, the temperature is maintained at [35,45]℃, which can ensure the activity of the stripping liquid and is conducive to stripping the copper layer on the conductive clip. During the stripping process, an ejector is used to introduce air or oxygen into the clamping mouth of the conductive clip or into the stripping liquid. This is conducive to efficiently stripping the copper layer on the conductive clip and improves the stripping efficiency. At the same time, a copper ion sensor is used to monitor the copper ion concentration in the stripping liquid in real time. When the copper ion concentration of the stripping liquid in the first container is greater than or equal to 100g / L, the pumping mechanism is started to transport the stripping liquid to the second container, and [0.5,0.9]A / dm 2 The copper ions in the stripping solution are electrolyzed at a current density of . A copper ion sensor is used to monitor the copper ion concentration in the second container in real time. When the copper ion concentration is about 5 g / L, the electrolysis is stopped to prevent the stripping solution from stripping the copper layer on the conductive clip and affecting the stripping rate. In the above manner, the copper layer on the conductive clip can be completely stripped off, which prevents the copper layer on the conductive clip from scratching, puncturing or even breaking the electroplated film, thereby improving the quality of the final product.

[0204] 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 sulfuric acid of [3%, 7%]. In this way, the residual stripping liquid on the conductive clip can be cleaned. The cleaned conductive clip is blown dry at [30, 40] ℃ with 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.

[0205] 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 to strip the copper layer at the clamping mouth of the conductive clamp in water electroplating, characterized in that: The peeling and hanging method comprises: Pre-processing the conductive clip; Placing the conductive clip into a stripping solution and keeping it for a first predetermined time to remove the copper layer at the clamping opening of the conductive clip, and monitoring the concentration of copper ions in the stripping solution at the same time, and electrolyzing the copper ions in the stripping solution according to a predetermined setting; The conductive clip is taken out and post-processed.

2. The peeling and hanging method according to claim 1, characterized in that: In the predetermined setting, the copper ion concentration in the stripping solution is [5,100) g / L.

3. The peeling and hanging method according to claim 1 or 2, characterized in that: In the step of electrolyzing the copper ions in the stripping solution, pure copper is used as the cathode pole and an insoluble anode is used as the anode pole.

4. The peeling and hanging method according to claim 3, characterized in that: In the step of electrolyzing the copper ions in the stripping solution, the current density of the power supply connected between the anode pole and the cathode pole is [0.5, 0.9] A / dm 2 .

5. The peeling and hanging method according to any one of claims 1, 2 and 4, characterized in that: The steps of placing the conductive clamp into the stripping liquid and keeping it for a first predetermined time to remove the copper layer at the clamping mouth of the conductive clamp and monitoring the copper ion concentration in the stripping liquid are performed in a first container, and the step of electrolyzing the copper ions in the stripping liquid is performed in a second container, and a pumping mechanism is provided between the first container and the second container.

6. The peeling and hanging method according to claim 5, characterized in that: The first predetermined time is [25, 120] s.

7. The peeling and hanging method according to any one of claims 1, 2, 4 and 6, characterized in that: The conductive clip is placed in a stripping liquid and kept for a first predetermined time to remove the copper layer at the clamping mouth of the conductive clip, wherein the stripping liquid is an acidic solution, the acidic solution includes sodium persulfate, sulfuric acid and urotropine, 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.

8. The peeling and hanging method according to claim 7, characterized in that: The temperature of the stripping liquid is [35,45]°C.

9. The peeling and hanging method according to claim 7, characterized in that: 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.

10. The peeling and hanging method according to claim 9, 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.

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