CN115537880A

CN115537880A - Metal ion recovery device and electrode manufacturing device provided with same

Info

Publication number: CN115537880A
Application number: CN202210729789.9A
Authority: CN
Inventors: 文太均; 李晙赫; 田承勋; 徐俊喆; 许; 申贤哲; 金成玟; 李相赫; 金荣光; 金龙会; 安容燮
Original assignee: Dongjin Semichem Co Ltd
Current assignee: Dongjin Semichem Co Ltd
Priority date: 2021-06-29
Filing date: 2022-06-24
Publication date: 2022-12-30
Also published as: KR20230001974A

Abstract

The present invention relates to a system for recovering metal ions and an apparatus for manufacturing electrodes for displays, which can effectively recover and regenerate metal ions from a solution containing metal ions by using a grounding process and an additional cooling process for the recovery of metal ions.

Description

Metal ion recovery device and electrode manufacturing device provided with same

Technical Field

The present invention relates to a metal ion recovery device and an electrode manufacturing device provided with the recovery device.

Background

In a display manufacturing process having an Ag electrode, a multi-layer film containing Ag, such as ITO/Ag/ITO, is etched using an acidic etching solution (etchant) to form an electrode pattern. The acidic etching solution can be repeatedly used as long as the etching performance is maintained, but as the number of times the acidic etching solution is used increases, the concentration of Ag contained in the acidic etching solution increases, and when it reaches a specific critical concentration or more, a problem of Ag deposition on the electrode pattern occurs. The quality of the acidic etching solution is deteriorated, possibly resulting in the occurrence of defects in the products produced by etching. Therefore, there is a need to develop a technology that can recover Ag generated in the etching process from the acidic spent etching solution for regeneration to recycle it for reuse in the etching process.

As conventional Ag recovery methods, a method of passing through an ion exchange resin, an electrolytic method, a cooling crystallization method, an electro-reduction method, and the like are known. The ion exchange resin method is a method of passing a solution containing Ag through a column (column) filled with an ion exchange resin to adsorb Ag on the surface of the ion exchange resin, and then recovering Ag through a post-treatment process. The electrolytic method is a method in which a solution containing Ag is passed through a recovery tank provided with an electrode to reduce Ag on the surface of the electrode. The cooling crystallization method is a method of cooling a solution containing Ag to form a needle-like ice crystal layer and then separating Ag impurities attached to the surface of the formed crystal layer.

However, the conventional ion exchange resin method has high recovery efficiency, but has low durability and high cost.

In addition, the electrolysis method has disadvantages of low efficiency and direct deposition of metal on the electrode surface, and therefore, the electrode needs to be frequently replaced, and it is difficult to apply the method in a recycling manner.

The cooling crystallization method is not economical and requires the acid etching solution to be kept at a constant temperature, thus being difficult to apply to a display production line.

In addition, since the electro-reduction method deposits metal directly on the surface of the electrode, the electrode needs to be replaced frequently.

In addition, there is a method of perfecting the existing electro-reduction method so that metal is precipitated in the form of nanostructures in a solution, rather than directly on the electrode surface. The method has advantages that the electrode can be used for a long period of time, and the precipitated Ag nanostructures can be easily recovered.

However, when the acidic waste etching solution regenerated by this method is reused, there is a problem of over-etching as compared with the conventional method, and the Ag nanostructure grows at a low rate, and therefore, it remains in the filtered waste etching solution, and the performance of the electrode may be affected.

Therefore, there is a need to develop a method for easily recovering Ag from a waste etching solution without causing excessive etching when reused after regeneration.

Documents of the prior art

Patent document 1: korean patent application laid-open No. 10-2017-0061096

Patent document 2: korean patent application laid-open publication No. 10-2014-0136552

Patent document 3: korean patent application laid-open publication No. 10-2012-7028736

Disclosure of Invention

Technical problem to be solved

The present specification aims to provide a metal ion recovery apparatus and an electrode manufacturing apparatus, which can easily reduce and regenerate metal ions from a solution containing metal ions by using a grounding means and an additional cooling means, and can prevent excessive etching when the regenerated solution (e.g., regenerated etching solution) is reused.

Further, the present specification aims to provide a method for regenerating an etching solution, which can prevent the metal nanostructure from further precipitating and avoid the problem of the etching process as much as possible.

In addition, the present specification aims to provide a metal ion recovery apparatus and an electrode manufacturing apparatus, which can automatically supply and manage insufficient components to a regenerated etching solution by confirming the component concentration of the etching solution changed during the regeneration process in real time through a monitoring device so that the etching solution meets the standard used in the conventional etching process.

Means for solving the problems

The present specification provides a metal ion recovery device, which includes: a metal ion reduction unit for reducing the metal ions from a solution containing the metal ions; and a potential difference changing unit for changing a potential difference of the solution in which the metal ions are reduced, wherein an Open Circuit Voltage (OCV) of the solution in which the potential difference is changed satisfies a first equation below.

The first mathematical formula:

0.158V<OCV<0.820V

in addition, the present specification provides a metal ion recovery device, including: a metal ion reduction unit for reducing the metal ions from a solution containing the metal ions; and a grounding unit connected to the metal ion reduction unit.

In addition, the present specification provides an electrode manufacturing apparatus including: an etching device for etching metal; a tank for supplying a solution containing metal ions of the metal; and any one of the above metal ion recovery devices.

Hereinafter, a metal ion recovery apparatus and an electrode manufacturing apparatus according to an embodiment of the present invention will be described.

The terminology used in the description is for the purpose of describing the exemplary embodiments only and is not intended to be limiting of the invention. The singular forms include the plural unless the context clearly dictates otherwise.

In the present specification, the terms "comprises," "comprising," "includes," "including," or "including," etc., are intended to specify the presence of stated features, integers, steps, operations, elements, or components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. However, the present invention is not limited to the specific forms disclosed, and it should be understood that all changes, equivalents, and substitutions included in the spirit and technical scope of the present invention are included in the scope of the present invention.

In the present specification, the contact angle refers to a contact angle of the electrode with respect to water. Specifically, the contact angle may be a static contact angle (static contact angle method) in which a contact angle to water (ultrapure water) 20 (content unit such as μ l, ml) is detected with a digital video contact angle analyzer (phoenix-10, SE 0) with respect to the outermost surface of the electrode as a contact angle detection object.

The present invention relates to a metal ion recovery apparatus and an electrode manufacturing apparatus including the same, wherein the recovery apparatus includes a potential difference changing unit and an additional cooling unit, and can effectively reduce metal ions from a solution containing metal ions.

The metal ion-containing solution may include a waste etching solution used in an etching process of a display production process.

Therefore, when the apparatus is used, a process of supplying an acidic etching solution from a tank and a process of etching an ITO/Ag/ITO multilayer film in an etching apparatus to form an electrode pattern may be performed, and after the etching process, a regeneration process of a contaminated waste etching solution may be continuously performed.

In particular, general regeneration liquid causes over-etching when it is reused for an etching process, but since the metal ion recovery apparatus according to an embodiment of the present invention includes a potential difference changing unit that can change a potential difference of the solution, over-etching can be prevented when the regeneration liquid is reused.

In addition, the metal ions are reduced after the solution containing the metal ions passes through the metal ion reduction unit, and thus the metal ions can be precipitated in the solution as the nanostructure.

In this case, the present specification provides an apparatus in which the solution containing the precipitated nanostructure is passed through a cooling unit before passing through a potential difference changing unit to grow the nanostructure, thereby allowing easy filtration in a filtration unit thereafter.

The grown nanostructures are recovered in a filtering unit, and the etching solution with the recovered nanostructures can be continuously recycled to the etching process for reuse.

Hereinafter, the present invention will be described more specifically.

Metal ion recovery device

According to an embodiment of the present invention, there is provided a metal ion recovery device including: a metal ion reduction unit for reducing the metal ions from a solution containing the metal ions; and a potential difference changing unit for changing a potential difference of the solution in which the metal ions are reduced, wherein an Open Circuit Voltage (OCV) of the solution in which the potential difference is changed satisfies a first equation below.

The first mathematical formula:

0.158V<OCV<0.820V

the metal ion recovery apparatus is characterized by comprising a metal ion reduction unit utilizing an electrical reduction method and a potential difference changing unit for reducing the potential difference of a solution of metal ions to be recovered.

In particular, in the present specification, the metal ion recovery apparatus includes a potential difference changing unit that can change a potential difference of the solution passing through the metal ion reduction unit by supplying electrons to the solution, thereby preventing excessive etching of the regeneration solution.

In addition, the solution containing the metal ions may be an etching solution (i.e., a waste etching solution) used in an etching process of a display process.

Therefore, the present specification includes a process of recovering Ag from an acidic etching solution used in a display anode manufacturing process by an electro-reduction method and then regenerating the Ag.

Specifically, the etching solution that has passed only through the metal ion reduction unit causes excessive etching when reused. For example, when the solution containing metal ions is an etching solution used in an etching process, an etching loss (hereinafter referred to as a C/D skew) of the etching solution passing through the metal ion recovery apparatus is greater than a C/D skew of an initial etching solution. This is related to the decomposition reaction of nitrate ions contained in the etching solution when the current is applied.

More specifically, the metal ion reduction unit generates decomposition (reduction) reaction of nitrate ions when energized, and such overall reaction equations are shown in reaction equations 1 and 2.

Reaction scheme 1

NO ₃ ^- +H ₂ O+2e ^- →NO ₂ ^- +2OH

At this time, the reaction formula is as follows:

reaction formula 2

Step 1: NO (nitric oxide) ₃ ^- +e ^- →NO ₂ ^- + O (State after power-on)

Step 2: o is ^- +e ^- +H ₂ O→2OH ^- (Rate determining step)

From the equation 2, oxygen is generated in step 1 in the decomposition reaction of nitrate ions, and since oxygen ions are unstable, a reaction with additional electrons occurs to be converted into a stable state. In addition, hydroxyl ions are generated by the reaction between the oxygen ions, water and electrons in step 2.

Therefore, when the etching solution is regenerated by the metal ion recovery device in which only the metal ion reduction unit is energized and the regenerated etching solution is applied to the ITO/Ag/ITO multilayer film, the oxygen ions remain in the regenerated etching solution, and the Ag of the multilayer film functions as an electron supply source. As a result, ag of the multilayer film is further etched to supply electrons, thereby generating over-etching, and the reaction at this time is as shown in the following reaction formula 3.

Reaction formula 3

Ag+H ₂ O+O ^- →Ag ⁺ +2OH-

The general reaction formula is as follows: NO ₃ ^- +H ₂ O+2Ag→NO ₂ ^- +2Ag ⁺ +2OH ^-

As described above, if the solution containing the metal ions is treated only with the metal ion reduction unit, there is a problem in that metal ion over-etching is generated when the regenerated solution is reused for the etching process.

Therefore, in the present invention, the solution passing through the metal ion reduction means is subjected to further application of the potential difference changing means so as to satisfy the condition of the first expression, thereby preventing excessive etching of the multilayer film when the regeneration solution is reused.

Therefore, according to an embodiment of the present invention, for the solution passing through the metal ion reduction unit, the solution receives electrons by the potential difference changing unit, so that it is possible to prevent the over-etching of metal ions (e.g., ag). The reaction formula in this case is as follows.

Reaction formula 4

O ^- +e ^- +H ₂ O→2OH ^-

The general reaction formula is as follows: NO ₃ ^- +H ₂ O+2e ^- →NO ₂ ^- +2OH ^-

On the other hand, the potential difference changing means may be any device capable of supplying electrons to the solution. For example, the potential difference changing unit may be selected from the group consisting of a grounding device, an electron beam, and an electron gun. More specifically, the potential difference changing unit may be a ground device.

The potential difference changing means may be connected to the metal ion reduction means, or may be provided as a separate member.

Therefore, according to another embodiment of the present invention, there may be provided a metal ion recovery device including: a metal ion reduction unit for reducing metal ions from a solution containing the metal ions; and a grounding unit connected to the metal ion reduction unit.

In addition, when the OCV is less than 0.158V or less in the first equation, even though a predetermined metal ion removal rate is shown, excessive etching may occur in the etching process using the regeneration solution because the C/D skew is greater than the initial etching solution value. In addition, if the OCV satisfies the condition of 0.820V or more, the temperature of the etching solution passing through the metal ion reduction unit is increased, and in this case, the temperature of the etching solution is increased, and thus some components (nitric acid and the like) of the etching solution are volatilized, and etching itself may not be achieved.

In this case, the OCV value of the waste etching solution can be detected by EIS (Electrochemical Impedance Spectroscopy). For example, in the OCV detection method, 150ml of a solution passing through a filtration unit is filled in a container having IrO2 on the cathode and FTO (Fluorine doped-Tin Oxide) on the anode, and then detection can be performed using EIS.

On the other hand, the metal ion reduction unit according to an embodiment may include: a container for containing a solution containing metal ions; a first electrode and a second electrode disposed inside the container; and a power supply for supplying electric energy to the first and second electrodes, wherein among the first and second electrodes, an electrode receiving the electric energy of the power supply to supply electrons to the metal ions may have a contact angle with water of 4 ° to 50 °.

When the solution containing the metal ions passes through the metal ion reduction unit, the metal ions in the solution can be precipitated as gel-like nanostructures.

In the present invention, the gel state refers to a form in which the metal nanostructure is dispersed in a solution in a state of losing fluidity and being solidified. That is, the gel state refers to a state in which the metal nanostructure is dispersed in the solution in a state of losing fluidity and being solidified, in any structure such as a structure in which the metal nanostructure is aggregated and dispersed in the solution and a structure in which the metal nanostructure is dispersed alone.

In addition, the ground unit according to one embodiment described above may include: a container for containing a solution in which metal ions are reduced; a third electrode fitted inside the container; and a grounding device connected to the third electrode and ground.

The third electrode may be connected to the metal ion reduction unit, and the third electrode may include a metal or a metal oxide having a contact angle with water of 4 ° to 50 °. In addition, the third electrodes may be provided in a plurality of, e.g., 10 to 50 sets.

In addition, the metal ion recovery apparatus may further include a cooling unit.

The cooling unit may grow an average particle size of the metal nanostructures in which the metal ions are reduced. Since the average particle size of the metal nanostructures is increased by the cooling unit, it is easily filtered out in a filtering unit described below, so that the recovery rate of metal ions can be improved.

Therefore, the metal ion recovery apparatus may further include a cooling unit for cooling the nanostructure precipitated in the metal ion reduction unit.

Such a cooling unit may be provided with a supply and a discharge of cooling water. The cooling unit may comprise means for regulating the flow of cooling water.

Cooling water having a temperature of-20 ℃ to 5 ℃ may be supplied to the cooling unit to cool the nanostructures precipitated at the metal ion reduction unit.

The nanostructure precipitated in a gel-like state maintains a particle size at a level of 10 to 20nm after passing through a metal ion reduction unit. In this case, the filtering effect may be insufficient due to the small particle size, and the nanostructure may be adhered to the ITO/Ag/ITO substrate when reused.

In the present invention, the average particle size of the precipitated nanostructure is grown by cooling, so that it is easily filtered by the filtering unit, thereby having a feature of improving the filtering efficiency. That is, the Ag nanostructure grows as the average particle size becomes higher by cooling, and the filter efficiency increases as it is filtered by the filter. In addition, the cooling unit may provide an effect of preventing partial over-etching similar to a grounding effect.

At this time, the cooling method may be performed by supplying cooling water having a temperature of-20 ℃ to 5 ℃ to the solution passing through the metal ion recovery apparatus. By supplying the cooling water in the temperature range, the average particle size of the deposited nanostructure can be grown to a size that can be easily recovered in the filtration unit. More specifically, when the cooling water is supplied in the range of-5 ℃ to 1 ℃, the supply of the cooling water is smoother, so that the cooling effect of the precipitated nanostructures is maximized and the nanostructures can be grown to a size that is easily recovered.

In addition, the cooling unit may be located between the metal ion reduction unit and the potential difference changing unit.

The metal ion recovery apparatus may further include a filtering unit for filtering the metal reduced by the metal ions in the metal ion reduction unit.

The filter unit may include two or more detachable filters, and at least one filter unit may further include cooling water.

The filtering unit may be disposed at a rear end of the potential difference changing unit or the grounding unit.

The filter unit may include one or more selected from the group consisting of a centrifuge (centrifuge), a filter selected from the group consisting of a micro filter, an acid-resistant filter, a nano filter, polytetrafluoroethylene (PTFE), polypropylene (PP), polyethersulfone (PES), and cellulose, or an adsorbent selected from the group consisting of an ion exchange resin, a Molecular sieve (Molecular sieve), silica, alumina, activated carbon, and zeolite. More specifically, the filter unit may be a microfilter having a pore size of 0.1 μm to 100 μm.

Hereinafter, the invention of the present application will be described with reference to the drawings.

Fig. 1 is a schematic structural view of a metal ion recovery apparatus according to an embodiment of the present invention.

The metal ion recovery apparatus may include a metal ion reduction unit 110, a cooling unit 112, a potential difference changing unit 114, and a filtering unit 116. As described above, the potential difference changing means may be the grounding means 115.

Fig. 2 is a view for describing a metal ion reduction unit according to an embodiment of the present invention.

As shown in fig. 2, the metal ion reduction unit 110 includes a container 60, first and

second electrodes

70 and 80, and a power supply 90.

The container 60 is used to contain a solution containing metal ions and may function as a reactor for performing an electrochemical reaction for reducing the metal ions. In addition, the container includes not only a case where the reaction solution is charged so as to be stagnant but also a case where it flows (has a flow rate).

In the solution containing metal ions, the metal ions may be selected from the group consisting of sodium ions, magnesium ions, aluminum ions, potassium ions, calcium ions, titanium ions, vanadium ions, chromium ions, manganese ions, iron ions, cobalt ions, nickel ions, copper ions, zinc ions, molybdenum ions, palladium ions, silver ions, cadmium ions, indium ions, tin ions, barium ions, tungsten ions, platinum ions, gold ions, mercury ions, lead ions, and mixtures thereof, and may be specifically Ag ions.

The solution containing metal ions supplied into the container may be an acidic substance-containing solution. Specifically, the solution containing metal ions may have a pH of-3 to 6. The acidic substance may be an inorganic acid such as phosphoric acid, nitric acid, etc.; or organic acids such as acetic acid, succinic acid, malonic acid, malic acid, formic acid, maleic acid, citric acid, tartaric acid, etc.

The acidic substance may further include a sulfonic acid compound, a hydrogen sulfate compound, a nitrogen-containing Dicarbonyl (Dicarbonyl) compound, an amino acid derivative compound, an iron-containing oxidant compound, and other additives and buffers, as necessary.

As an example of the present invention, the solution containing metal ions may be a waste etching solution generated in a process of manufacturing an electrode for a display. In addition, the metal ion-containing solution may be an acidic solution containing a concentration of metal powder.

The metal ion-containing solution may further include additives such as ammonium salt compounds (ammonium salt), amino acids, and buffers, as needed. In addition, the solution containing metal ions may be an inorganic solution or an organic solution.

The metal ion-containing solution may be an inorganic solution including one or more selected from phosphoric acid, nitric acid, organic acids, ammonium salts, and amino acids, in addition to metal ions.

When the metal ion-containing solution is an inorganic solution, the metal ion-containing solution may contain, based on the content of the total solution, 40 to 65% by weight of phosphoric acid, 3 to 10% by weight of nitric acid, 1 to 25% by weight of an organic acid, 1 to 10% by weight of an ammonium salt compound and an amino acid, 300 to 10000ppm of metal ions, and the balance of water.

In addition, the metal ion-containing solution may be an organic solution including one or more selected from nitric acid, citric acid, acetic acid, a sulfonic acid compound, a hydrogen sulfate compound, a nitrogen-containing dicarbonyl compound, an amino acid derivative compound, and an iron-containing oxidant compound, in addition to the metal ions.

In addition, when the metal ion-containing solution is an organic solution, the metal ion-containing solution may contain, based on the content of the total solution, 18 to 30% by weight of citric acid, 15 to 20% by weight of acetic acid, 8.1 to 9.9% by weight of nitric acid, 1 to 4.9% by weight of a sulfonic acid compound, 10 to 20% by weight of a bisulfate compound, 1 to 5% by weight of a nitrogen-containing dicarbonyl compound, 1 to 5% by weight of an amino acid-derived compound, 0.1 to 2% by weight of an iron-containing oxidant compound, 300 to 10000ppm of metal ions, and the balance of water.

In addition, as described above, the content of the metal ion in the metal ion-containing solution may be 300ppm to 10000ppm based on the content of the total solution, but is not limited thereto. That is, in the etching step of the photolithography process, the content of the metal ion may vary depending on the content of the metal ion contained in the conductive film, and thus the content thereof is not particularly limited.

On the other hand, the first electrode 70 and the second electrode 80 induce an electrochemical reaction for recovering a metal, specifically, a metal ion is precipitated by supplying an electron to the metal ion contained in the solution to reduce the metal ion.

Among the first and second electrodes, an electrode receiving the power of the power supply to supply electrons to the metal ions may have a contact angle with water of 4 to 50 °. In this case, the metal ions are precipitated in the solution as gel-like nanostructures, and can be easily removed.

When the contact angle of the electrode with water is more than 50 °, metal ions are precipitated as adhering to the surface of the electrode, and the replacement cycle of the electrode becomes short, which disadvantageously decreases productivity. When the contact angle is less than 4 °, there is a problem that the acid recovery solution causes damage to the electrode due to poor acid resistance of the electrode. Specifically, the contact angle may range from 4 to 30 °, in which case the electrode is not damaged, and the metal ion recovery speed satisfies a certain range, thereby recovering metal ions from a solution containing metal ions more easily than ever.

In addition, both the first electrode and the second electrode may have a contact angle with water of 4 to 50 °. When both the first electrode and the second electrode have contact angles satisfying the range, metal ions are precipitated in the solution as gel-like nanostructures, and thus can be easily removed, and since a reverse voltage can be applied, both electrodes can be alternately used as electrodes for reducing metal ions, thereby having an effect of extending the lifetime of the device.

In addition, at least any one of the first electrode and the second electrode is an electrode for supplying electrons to the metal ions by receiving electric energy from the power source. In such an electrode, the difference (Δ γ) between the contact angle with water and the contact angle of the metal recovered in the metal ion recovery device may be 20 ° or more and 75 ° or less, and specifically may be 50 ° or more and 75 ° or less. When the difference (Δ γ) between the contact angles of the metal recovered by the metal ion recovery apparatus and the electrode is within the above range, the metal ions are precipitated in the solution as gel-like nanostructures, and can be easily removed.

Herein, the difference (Δ γ) between the contact angles of the recovered metal and the electrode is defined by the following second mathematical formula.

Second mathematical formula

The difference between the contact angles of the recovered metal and the electrode (. DELTA.. Gamma.) = the contact angle of the recovered metal to water (. Gamma.1) -the contact angle of the electrode material to water (. Gamma.2)

At least one of the first and

second electrodes

70 and 80 satisfying the contact angle may include a metal or a metal oxide. For example, both the first electrode 70 and the second electrode 80 may include a metal oxide.

In addition, any one of the first electrode and the second electrode may be a cathode, and the remaining one may be an anode. Specifically, the first electrode 70 may be a cathode and the second electrode 80 may be an anode.

In addition, any one of the first electrode 70 and the second electrode 80 may be a photo electrode. That is, one of the first electrode and the second electrode is an electrode having a contact angle with water of 4 to 50 ° for supplying electrons to the metal ions by receiving the electric power of the power source, and the remaining one may be a photoelectrode.

For example, the first and second electrodes may comprise a metal selected from the group consisting of magnesium oxide (magnesium oxide), aluminum oxide (aluminum oxide), silicon oxide (silicon oxide), titanium oxide (titanium oxide), vanadium oxide (vanadium oxide), chromium oxide (chromium oxide), manganese oxide (manganese oxide), iron oxide (iron oxide), cobalt oxide (cobalt oxide), copper oxide (copper oxide), zinc oxide (zinc oxide), gallium oxide (gallium oxide), germanium oxide (germanium oxide), strontium oxide (strontium oxide), molybdenum oxide (molybdenum oxide), ruthenium oxide (ruthenium oxide), rhodium oxide (rhodium oxide), platinum oxide (indium oxide), indium oxide (indium oxide), tin oxide (tin oxide), barium oxide (barium oxide), tungsten oxide (tungsten oxide), iridium oxide (iridium oxide), bismuth oxide (bismuth oxide), and mixtures thereof including bismuth oxide. The metal may be selected from the group consisting of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, molybdenum, palladium, indium, tin, tungsten, platinum, gold, mercury, lead, tantalum, and mixtures thereof.

Examples of contact angles to water of these materials constituting the first electrode and the second electrode are shown in table 1.

TABLE 1

A plurality of electrode groups of one or more groups may be arranged in parallel inside the container, based on one group of the first electrode 70 and the second electrode 80. Specifically, a set of the first electrode and the second electrode is used as a standard, and 10 sets or more and 50 sets or less of electrodes may be arranged in parallel in the container. Therefore, for the container, the size can be adjusted and changed according to the number of the electrode groups configured in plural.

In the first and second electrodes, a gap between the electrodes may be 1mm to 10mm. When the gap between the electrodes is within the range, the removal efficiency of the metal ions can be improved due to the formation of a strong electric field. When the gap is 1mm or less, an electrical short circuit (short) may occur due to excessive approach between electrodes, and when the gap is 10mm or more, there is a problem in that removal efficiency of metal ions is lowered due to a weak electric field.

The power supply 90 is connected to the first electrode 70 and the second electrode 80, and supplies electric energy to the first electrode 70 and the second electrode 80 through a power supply device to supply electrons, so that metal ions are reduced (precipitated) into metal through an electro-reduction method.

In this case, the reduction efficiency of the metal is improved as the current intensity of the power supply is higher, but if the current is excessively increased, there is a possibility that the life of the electrode is shortened.

The power supply supplies electrons to the first electrode and the second electrode, thereby reducing (precipitating) metal ions into metal by an electro-reduction method. Although the reduction efficiency of the metal is higher as the current intensity is higher, if the current is excessively increased, there is a possibility that the life of the electrode becomes short.

Thus, the power supply is capable of supplying electrical energy to the first and second electrodes at a current of 0.3 to 300A, in particular at a current of 3 to 100A, or 10 to 80A, or 20 to 50A, respectively. When the current supplied by the power supply is greater than 300A, electrode damage may occur resulting in a shortened electrode life. On the other hand, when the current supplied from the power supply is less than 0.3A, metal is hardly precipitated, and thus the removal efficiency of metal ions is lowered.

The Ag ions (Ag +) that give electrons are reduced to silver (Ag), and the reduced silver forms smaller crystal aggregates, thereby achieving nucleation. Due to the complicated factors, the generated nuclei can grow, and the grown nanostructures are in an unstable state and thus precipitate in the solution. The nanostructures may be nanoparticles, nanowires, nanorods, nanotubes, nanoplates, nanodiscs, etc., in particular nanoparticles or nanowires.

By adjusting the voltage and current, the removal efficiency of the metal ions can be improved. In addition, the size of the first electrode and the second electrode and the number of electrode groups can be adjusted.

On the other hand, fig. 3 is a view for describing the ground unit according to an embodiment of the present invention.

As shown in fig. 3, the ground unit may include: a container 60 for containing the solution passed through the metal ion reduction unit; a third electrode 72 fitted inside the container; and a grounding device connected to the third electrode and ground.

The third electrode may include a metal or a metal oxide having a contact angle with water of 4 ° to 50 °.

The grounding device comprises a grounding rod which is connected to the third electrode and is connected to the ground.

The material of the third electrode may be the same as or different from the first electrode and the second electrode constituting the metal ion recovery device. Specifically, in terms of acid resistance, the third electrode preferably uses the same electrode as the first electrode and the second electrode.

In addition, examples of the contact angle of the material constituting the third electrode to water may be as shown in table 1 above.

The metal may be selected from the group consisting of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, molybdenum, palladium, indium, tin, tungsten, platinum, gold, mercury, lead, tantalum, niobium, zirconium, ruthenium, rhodium, iridium, and mixtures thereof. The metal oxide may be selected from the group consisting of magnesium oxide, aluminum oxide, silicon oxide, titanium oxide, vanadium oxide, chromium oxide, manganese oxide, iron oxide, cobalt oxide, copper oxide, zinc oxide, gallium oxide, germanium oxide, strontium oxide, molybdenum oxide, ruthenium oxide, rhodium oxide, indium oxide, tin oxide, barium oxide, tungsten oxide, iridium oxide, bismuth oxide, niobium (V) oxide, tantalum oxide, zirconium oxide, gold oxide, silver oxide, and mixtures thereof.

In addition, fig. 4 is a view for describing a cooling unit according to an embodiment of the present invention.

In fig. 4, the cooling unit may include a bath (bath) capable of containing a cooler (Chiller) and a solution, including a barrier and a mesh inside, and provided with a cooler line.

In addition, as described above, the cooling unit may be provided with a device capable of supplying and discharging cooling water in a continuous circulation manner. Furthermore, the cooling means may comprise means for regulating the flow of cooling water. The temperature of the cooling water may be-20 to 5 ℃.

The precipitated nanostructures may be removed by the filtration unit described above.

When the metal ion recovery apparatus as described above is used, it is possible to efficiently recover and regenerate metals from a high-concentration metal ion-containing solution, particularly from an acidic etching solution used in an etching process of a display production process. In addition, the metal ion recovery apparatus can prevent excessive etching when the regeneration solution is reused by the grounding unit. Further, in the present specification, since the grounding unit and the cooling unit are included, it is possible to efficiently recover the metal from the solution containing the metal ions and regenerate the solution, compared to the prior art. In particular, according to the present invention, since silver (Ag) is not directly grown on the surface of an electrode but is grown in the form of nanostructures in a solution, the electrode can be used for a long time and has an advantage of easily recovering the grown nanostructures.

Electrode manufacturing apparatus

According to another embodiment of the present invention, there may be provided an electrode manufacturing apparatus including: an etching device for etching metal; a tank for supplying a solution containing metal ions of the metal; and any one of the above metal ion recovery devices.

According to the present specification, the electrode manufacturing apparatus may be used for a display. That is, the metal ion recovery apparatus including the potential difference changing unit or the grounding unit can be applied to a display electrode manufacturing apparatus.

In addition, the electrode manufacturing apparatus may include a monitoring device for detecting a concentration of a substance contained in the metal ion-containing solution. Furthermore, the device can be configured in a cyclic manner. Therefore, the electrode manufacturing apparatus may be such that the etching apparatus, the tank, the metal ion recovery apparatus, and the monitoring apparatus are arranged in a cyclic manner.

The monitoring means refers to a system for detecting the concentration of a substance contained in the regenerated etching solution and for supplying a substance having a changed composition in the etching solution to the regenerated etching solution.

Therefore, in the present specification, since the electrode manufacturing apparatus is used, a step of containing an acidic waste etching solution discharged after use in a display element pattern forming process and a step of regenerating the acidic waste etching solution using a metal ion recovery apparatus are included. Further, the method includes a grounding step of regenerating the etching solution passing through the metal ion reduction unit provided in the metal ion recovery device. In addition, the present invention may include a cooling step of cooling the regenerated acidic spent etching solution by a cooling unit to increase the particle size of the Ag nanostructure to precipitate it. In addition, a filtering step of filtering the Ag nanostructures precipitated in the cooling step and a step of recycling the regenerated acidic spent etching solution may be included. In addition, the present invention may include an etching solution regeneration method including an OMS (Online Monitoring System) for Monitoring and managing a composition of a composition automatically supplied and changed by a change in the composition of an acidic etching solution in real time.

On the other hand, fig. 5 and 6 are schematic structural views of an electrode manufacturing apparatus according to an embodiment of the present invention. Specifically, fig. 5 and 6 are views for describing an anode manufacturing process of a display and an etching solution regeneration process with a monitoring device.

As shown in fig. 5 and 6, the electrode manufacturing apparatus may include: a metal ion recovery device 100; a tank 200 for supplying a solution containing metal ions of the metal; an etching apparatus 300 for etching a metal; and a monitoring device 400, which may be of a cyclic type. In addition, the metal ion recovery apparatus 100 may be such that the metal ion reduction unit 110, the cooling unit 112, the grounding unit 115, and the filtering unit 116 are configured in a circulation manner. Although the ground unit is illustrated in the drawings, any one selected from the potential difference changing units 114 described above may be used in the ground process instead of the ground unit.

In addition, a pump 50 may be further included between the tank and the metal ion recovery device. The pump may be provided in order to supply the spent etching solution from the tank 200 to the metal ion recovery unit 110. Further, optionally, as shown in fig. 6, a pump 50 may be further included between the tank 200 and the monitoring device 400. In addition, although not shown in the drawings, the filtering means may be connected to a discharging means provided for removing and recovering the precipitated nanostructures.

At this time, the anode may be patterned through a photolithography process of coating Photoresist (PR), exposing, developing, etching, stripping photoresist (PR strip), and washing.

In the photoetching process, the ITO/Ag/ITO multilayer film is etched by using an acid etching solution, so that an electrode pattern is formed.

The spent etching solution then passes through the electrode manufacturing apparatus, whereby metal ions can be recovered and regenerated.

The etching solution regenerated by the regeneration step may be recycled and reused in the etching process. In addition, the regenerated etching solution can be reused after being purified in real time on an assembly line or after being recycled to a spare tank for purification in a circulating manner.

In addition, the circulation system includes an OMS (Online monitoring system) device for monitoring the changed components in the regeneration step in real time to automatically supply and manage the changed compositions to the regenerated etching solution.

At this time, the regeneration step of the waste etching solution may utilize a process of applying an electric current to the waste etching solution.

As described above, in the present specification, since the electrode manufacturing apparatus can be applied to a display process, a waste etching solution contaminated after an etching step is effectively regenerated and then continuously reused in the etching process, compared to the prior art.

Effects of the invention

When the metal ion recovery apparatus and the electrode manufacturing apparatus according to the present invention are used, metal ions can be easily removed from an etching solution used in an etching process of a display production process and regenerated. Particularly, the present invention can prevent an over-etching phenomenon generated in an etching process when a regeneration liquid is used by performing a grounding process or selectively further performing a cooling process on a solution passing through a metal ion reduction unit, and can improve filtering performance by rapid growth of Ag nanostructures, thereby minimizing a problem of a defect occurring in the etching process.

Drawings

Fig. 3 is a view for describing a grounding unit according to an embodiment of the present invention.

Fig. 4 is a view for describing a cooling unit according to an embodiment of the present invention.

Fig. 5 is a schematic configuration diagram of an electrode manufacturing apparatus according to an embodiment of the present invention.

Fig. 6 is a schematic configuration diagram of an electrode manufacturing apparatus according to another embodiment of the present invention.

Fig. 7 is a view showing etching performance according to the embodiment and the comparative example.

Fig. 8 is a view for describing the reason why over-etching is prevented when oxygen ions are generated along with decomposition of nitrate ions and grounded depending on whether or not a grounding unit is applied in the electrode manufacturing apparatus.

Fig. 9 is a view comparatively showing the average particle size of the nanostructure bodies before and after applying cooling according to whether or not the cooling unit is applied in the electrode manufacturing apparatus.

Fig. 10 is a view for describing Ag concentration variation and side etching loss (C/D skew) variation in time unit when the ground unit and the cooling unit according to an embodiment of the present invention are applied.

Detailed Description

Hereinafter, the present invention will be described in further detail by way of specific examples. The following examples are intended to illustrate the present invention, and the present invention is not limited to the following examples.

Production example

Manufacture of metal ion reduction unit

The container is made of Teflon material with a capacity of 3.5L, and the electrode is made of iridium oxide (IrO) in mesh ₂ ) (contact angle to water is 23 °). The electrodes (first electrode, second electrode) were set up 47 in total (24 groups), and the first electrode and the second electrode in the container were set up at an interval of 2 to 3mm, and were connected to make the first electrode the cathode and the second electrode the anode when connected to a power supply. At this time, the flow rate of the metal ion-containing solution was 100ml/min.

Manufacture of potential difference changing unit

The container was made of Teflon material with a capacity of 3.5L, and the third electrode used iridium oxide IrO in a mesh form ₂ . The third electrodes were arranged in a total of 47 (24 groups), the interval of the third electrodes in the container was set to 2 to 3mm, and the third electrodes and the ground rod were connected to make a potential difference changing unit.

Manufacture of cooling units

The cooling unit utilizes a Bath (Bath) that can hold a cooler (Chiller) whose temperature is set to 0 ℃ and a solution.

EXAMPLE 1 Metal ion recovery apparatus and recovery method

After the metal ion recovery device provided with the metal ion reduction means and the potential difference changing means is manufactured, the metal ions are recovered by the manufactured metal ion recovery device, and the recovery method is as follows.

First, an etching solution used in an etching apparatus of a photolithography process (hereinafter, referred to as a waste etching solution, an acidic waste etching solution discharged after being used in a display element pattern forming process) is transferred to a tank and stored.

Then, the spent etching solution was maintained at a temperature of 40 ℃ and injected from the tank into the metal ion reduction unit by pumping. In order to reduce Ag ions injected into the waste etching solution of the metal ion reduction unit, a current of 47A was applied to a solution containing iridium oxide (IrO) ₂ ) The application time to the cathode and anode was 4 hours. At this time, ag ions in the waste etching solution precipitate as metal nanostructures.

The waste etching solution from which the metal nanostructures were precipitated was injected into a potential difference changing unit to change the OCV of the waste etching solution to 0.168V. Then, the metal nanostructures in the waste etching solution in which the OCV was changed were filtered using a detachable filter (polypropylene (PP) filter having a pore size of 1 um).

Then, the solution in which the metal nanostructures were filtered was monitored by an OMS device to confirm the changed components, and the components that need to be regenerated were supplied to the etching apparatus.

At this time, the OCV of the waste etching solution was measured by EIS (Electrochemical Impedance Spectroscopy), and the OCV value was 0.158V. In this case, the OCV was measured by filling 150ml of a solution passing through a filtration unit into a container having IrO2 on the cathode and FTO (Fluorine doped-Tin Oxide) on the anode, and then using EIS.

After applying the etching solution regenerated by the above results to an ITO/Ag/ITO substrate and etching, C/D deviation was confirmed.

Example 2

The same metal ion reduction means and potential difference changing means as in example 1 were provided, and the OCV of the spent etching solution was changed to 0.265V by the potential difference changing means. Except for this, metal ions were recovered by the same method as in example 1.

Example 3

A metal ion recovery apparatus was prepared in which a cooling means was further provided between the metal ion reduction means and the potential difference changing means in the same manner as in example 1, and the OCV of the spent etching solution was changed to 0.288V by the potential difference changing means. Except for this, metal ions were recovered by the same method as in example 1.

Example 4

The same metal ion recovery apparatus as in example 3 was provided, and the OCV of the spent etching solution was changed to 0.316V by the potential difference changing means. Except for this, metal ions were recovered by the same method as in example 3.

Example 5

The same metal ion reduction means and potential difference changing means as in example 1 were provided, and the OCV of the spent etching solution was changed to 0.508V by the potential difference changing means. Except for this, metal ions were recovered by the same method as in example 1.

Example 6

The same metal ion reduction means and potential difference changing means as in example 1 were provided, and the OCV of the waste etching solution was changed to 0.795V by the potential difference changing means. Except for this, metal ions were recovered by the same method as in example 1.

Comparative example 1

A metal ion recovery apparatus excluding the potential difference changing means in the metal ion recovery apparatus of example 1 was manufactured, and metal ions were recovered by the same method as in example 1, except that a metal ion recovery apparatus without a potential difference changing means was used. At this time, the OCV of the waste etching solution was measured by EIS (Electrochemical Impedance Spectroscopy), and the OCV value was 0.158V. In this case, the OCV was measured by filling 150ml of a solution passing through a filtration unit into a container having IrO2 on the cathode and FTO (Fluorine doped-Tin Oxide) on the anode, and then using EIS.

In the case of comparative example 1, the silver removal rate was similar to that of example 1, but the C/D skew was higher by 1.2um, which was confirmed to cause over-etching.

Comparative example 2

The same metal ion reduction means and potential difference changing means as in example 1 were provided, and the OCV of the spent etching solution was changed to 0.820V by the potential difference changing means. Except for this, metal ions were recovered by the same method as in example 1. In order to change the OCV of the waste etching solution to 0.820V, the temperature of the waste etching solution was heated to 80 ℃. In this case, since the temperature conditions are higher than in the examples, a part of the components (nitric acid and the like) in the waste etching solution volatilizes, so that there arises a problem that etching itself cannot be realized.

Specifically, when the temperature of the waste etching solution is increased, the solubility of the solution increases, and a problem of re-dissolution of a part of the metal nanostructures generated by electricity will occur. Thus, in comparative example 2, it was confirmed that the recovery rate of silver ions was lower than that when the temperature of the waste etching solution was 40 ℃. Further, the boiling point of nitric acid is 83 ℃ and when the temperature of the waste etching solution is increased to 80 ℃, the boiling point of the waste etching solution approaches the boiling point of nitric acid, and further, there is a problem that the waste etching solution is easily volatilized. That is, the component directly affecting silver etching is nitric acid, and the higher the temperature of the waste etching solution is, the more volatile the nitric acid is, and the change in the component occurs. Therefore, in comparative example 2, it was confirmed that etching of the substrate became impossible.

Therefore, the silver removal rate of comparative example 2 was lower than that of the examples, and the C/D skew was confirmed to be poor.

Examples of the experiments

Recovery of metal ions

In order to confirm the removal rate of silver (Ag) ions of examples 1 to 6 and comparative examples 1 to 2, samples were taken at a time point of 4 hours, and the results thereof are shown in table 2.

That is, after filtering out the silver (Ag) nanostructures formed in the acidic etching solution, the concentration of silver (Ag) ions contained in the acidic etching solution was detected by an inductively coupled plasma mass spectrometer (ICP-MS), and the removal rate and removal rate of silver (Ag) ions were calculated, and the results are shown in table 2.

In table 2 below, "removal rate of silver (Ag) ions" is represented by a reduction rate (%) of "content of silver (Ag) ions remaining in the acidic etching solution after the recovery treatment of silver (Ag)" and "content of silver (Ag) ions contained in the acidic etching solution before the recovery treatment of silver (Ag)" in terms of a reduction rate (%) (4 hours of energization).

Evaluation of the Properties of the regenerated etching solution

An etching solution (reference solution, REF) was prepared, which was composed of 58 wt% of phosphoric acid, 5.5 wt% of nitric acid, 3 wt% of ammonium acetate, 5 wt% of citric acid, and 28.5 wt% of water. The reference solution and a regeneration solution 20L of the spent etching solution subjected to the recovery process under the conditions of example 1 were prepared, and the etching process was performed in an Etcher (Etcher).

The substrate etching method performs End Point Detection (EPD). Then, over Etching (Over Etching) is performed for a certain time to etch the substrate to a desired thickness.

In order to compare the etching characteristics, the C/D skew values were measured, and SEM photographs of the etching profiles are shown in fig. 7 (the left side is the reference liquid, and the right side is the evaluation liquid). The standard for over-etching is above 0.4 um.

For C/D skew, samples were taken at 1 hour, 2 hour time points, respectively.

That is, fig. 7 is a view showing etching performance according to embodiment 1. Specifically, FIG. 7 is a view ((a) C/D Skew value and (b) SEM photograph) showing the etching level in time units before and after grounding was applied (CD Sview is side etching damage by a scanning electron microscope; critical Dimension Sview) according to whether or not a grounding device is applied in the display electrode manufacturing apparatus.

In addition, fig. 8 is a view for describing the reason why over-etching is prevented when oxygen ions are generated along with decomposition of nitrate ions and grounded depending on whether or not a grounding unit is applied in the electrode manufacturing apparatus.

As shown in fig. 7 and 8, when the etching solution regenerated through the grounding process according to example 1 was used, over-etching did not occur, having excellent etching performance, compared to the reference solution in which the grounding process was not performed. That is, if the grounding means is not provided, excessive etching of Ag occurs on the surface of the conductive film, but by providing the grounding means, excessive etching can be prevented from occurring.

Detecting the average particle size of the nanostructures before and after cooling

The average particle size over time before and after cooling of example 3 and example 4 were compared.

Specifically, the solution passed through the metal ion recovery apparatus of example 3 and the solution passed through the metal ion recovery apparatus and the cooling apparatus of example 4 were prepared, left at normal temperature and low temperature (0 ℃) for 10 minutes, 30 minutes, and 120 minutes, respectively, and then the precipitated nanostructures were filtered to detect the average particle size, the results of which are shown in fig. 8.

In addition, in the case of example 4 in which the cooling device and the grounding device were applied, sampling was performed at a 2-hour time point for the C/D skew. Further, changes in Ag concentration and changes in C/D skew were observed in time units, and the results are shown in fig. 10.

TABLE 2

As shown in Table 2 above, examples 1 to 6 are such that OCVs of the spent etching solutions satisfy the first equation, and therefore not only are the Ag ion removal rates excellent, but also the C/D skews are lower than those of comparative examples 1 to 2, thereby preventing over-etching.

In particular, examples 3 and 4 satisfy the first equation while adding a cooling unit, and thus the average particle size of Ag nanostructures is increased, compared to examples 1, 2, 5, and 6, thereby having more excellent Ag ion removal rate.

Description of the reference numerals

50: the pump 60: container with a lid

70: first electrode 80: second electrode

72: third electrode

90: power supply (power supply)

200: tank body

100: metal ion recovery device

110: metal ion reduction unit 112: cooling unit

114: potential difference changing unit

115: the grounding unit 116: filter unit

300: the etching apparatus 400: and a monitoring device.

Claims

1. A metal ion recovery device, comprising:

a metal ion reduction unit for reducing the metal ions from a solution containing the metal ions; and

a potential difference changing unit for changing a potential difference of the solution in which the metal ions are reduced,

the open circuit voltage of the solution for changing the potential difference satisfies the following first expression,

the first mathematical formula:

0.158V<OCV<0.820V。

2. the metal ion recovery apparatus according to claim 1,

the potential difference changing unit is selected from the group consisting of a grounding device, an electron beam, and an electron gun.

3. The metal ion recovery apparatus according to claim 1,

the metal ion reduction unit includes:

a container for containing a solution containing metal ions;

a first electrode and a second electrode disposed inside the container; and

a power supply for supplying electrical energy to the first electrode and the second electrode,

among the first and second electrodes, an electrode receiving electric power from the power supply to supply electrons to the metal ions has a contact angle with water of 4 ° to 50 °.

4. The metal ion recovery apparatus according to claim 1, further comprising a cooling unit.

5. The metal ion recovery apparatus according to claim 1, further comprising:

and the filtering unit is used for filtering the metal reduced by the metal ions.

6. The metal ion recovery apparatus according to claim 5,

the filter unit comprises more than two detachable filters.

7. The metal ion recovery apparatus according to claim 5,

the filter unit further includes cooling water.

8. The metal ion recovery apparatus according to claim 5,

the filtration unit includes one or more selected from the group consisting of a centrifuge, a filter selected from the group consisting of a micro-filter, an acid-resistant filter, a nano-filter, polytetrafluoroethylene, polypropylene, polyethersulfone, and cellulose, or an adsorbent selected from the group consisting of an ion exchange resin, a molecular sieve, silica, alumina, activated carbon, and zeolite.

9. The metal ion recovery apparatus according to claim 8,

the filtration unit is a microfilter having a pore size of 0.1 to 100 μm.

10. A metal ion recovery device, comprising:

a grounding unit connected to the metal ion reduction unit.

11. The metal ion recovery apparatus according to claim 10,

the grounding unit includes:

a container for containing the solution in which the metal ions are reduced;

a third electrode fitted inside the container; and

and the grounding device is connected to the third electrode and the ground.

12. The metal ion recovery apparatus according to claim 11,

the third electrode includes a metal or a metal oxide having a contact angle with water of 4 ° to 50 °.

13. The metal ion recovery apparatus according to claim 10, further comprising a cooling unit.

14. The metal ion recovery apparatus according to claim 10, further comprising:

15. An electrode manufacturing apparatus, comprising:

an etching device for etching metal;

a tank for supplying a solution containing metal ions of the metal; and

the metal ion recovery device of any one of claims 1 to 14.

16. The electrode manufacturing apparatus according to claim 15,

the etching apparatus, the tank, the metal ion recovery apparatus, and the monitoring apparatus are arranged in a circulating manner.

17. The electrode manufacturing apparatus according to claim 15,

the electrode manufacturing apparatus is a display electrode manufacturing apparatus.