Plating composition and method for producing same

Abstract

Provided is a method for efficiently producing a plating composition usable for plating treatment from plating waste liquid. This method for producing a plating composition comprises: removing a portion of water from a first plating composition containing first metal ions and water via a separation membrane to obtain a first concentrated liquid; removing a portion of water from the first concentrated liquid under a low oxygen partial pressure environment to obtain a second concentrated liquid; introducing the second concentrated liquid into a working electrode chamber provided with a working electrode to reduce at least a portion of the first metal ions in the second concentrated liquid to metal, with the working electrode serving as a cathode, the working electrode chamber being separated from a counter electrode chamber provided with a counter electrode by at least one membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane; and oxidizing a metal of the same kind as the reduced metal into second metal ions having a lower oxidation number than the first metal ions, with the working electrode serving as an anode, to obtain a second plating composition containing the second metal ions and water.

Description

Plating composition and method of manufacturing the same

[0001] The present invention relates to a plating composition and a method for making the same.

[0002] In relation to plating compositions used in metal plating, Japanese Patent Laid-Open Publication No. 2003-213435 proposes a treatment system for plating wastewater, which is composed of an effluent storage tank for storing plating wastewater, an intermediate treatment device connected to the effluent storage tank, a concentration and volume reduction device connected to the intermediate treatment device, and a recovery device for recovering concentrated fluid from the concentration and volume reduction device, and describes a method for concentrating plating wastewater under reduced pressure.

[0003] However, the invention described in JP 2003-213435 A can concentrate and reduce the volume of plating wastewater, but cannot prevent the plating wastewater itself from being discharged. One aspect of the present invention aims to provide a method for efficiently producing a plating composition by efficiently reducing highly oxidized metal ions in plating wastewater to less oxidized metal ions.

[0004] A first aspect is a method for producing a plating composition, the method comprising: removing a portion of the water from a first plating composition containing first metal ions and water through a separation membrane to obtain a first concentrated solution; removing a portion of the water from the first concentrated solution in a low oxygen partial pressure environment to obtain a second concentrated solution; introducing the second concentrated solution into a working electrode chamber separated by a counter electrode chamber having a counter electrode and at least one membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane and having a working electrode, thereby reducing at least a portion of the first metal ions in the second concentrated solution to a metal, using the working electrode as a cathode; and oxidizing a metal similar to the reduced metal to a second metal ion having a lower oxidation number than the first metal ion, using the working electrode as an anode, to obtain a second plating composition containing the second metal ions and water.

[0005] A second aspect is a plating composition produced by the method for producing a plating composition.

[0006] According to one aspect of the present invention, a method for efficiently producing a plating composition can be provided by efficiently reducing metal ions in a high oxidation state in a plating wastewater solution to metal ions in a low oxidation state.

[0007] 1 is a flow chart illustrating an example of the process sequence of a method for producing a plating composition. 2 is a schematic diagram illustrating an example of the process of a method for producing an electronic component.

[0008] As used herein, the term "process" refers not only to an independent process, but also to processes that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved. Furthermore, the content of each component in a composition refers to the total amount of the multiple substances present in the composition, unless otherwise specified, when multiple substances corresponding to each component are present in the composition. Furthermore, the upper and lower limits of the numerical ranges described herein can be arbitrarily selected and combined from the numerical values ​​exemplified as numerical ranges. Below, embodiments of the present invention are described in detail. However, the embodiments described below are intended to exemplify plating compositions and methods for producing the same in order to embody the technical concept of the present invention, and the present invention is not limited to the plating compositions and methods for producing the same shown below.

[0009] A method for producing a plating composition includes a first concentration step of removing a portion of the water from a first plating composition containing first metal ions and water through a separation membrane to obtain a first concentrated solution, a second concentration step of removing a portion of the water from the first concentrated solution in a low-oxygen partial pressure environment to obtain a second concentrated solution, a first metal ion reduction step of introducing the second concentrated solution into a working electrode chamber separated by a counter electrode chamber containing a counter electrode and at least one diaphragm selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane and containing a working electrode, and reducing at least a portion of the first metal ions in the second concentrated solution to metal using the working electrode as a cathode, and a second metal ion oxidation step of oxidizing a metal similar to the reduced metal to a second metal ion having a lower oxidation number than the first metal ion using the working electrode as an anode to obtain a second plating composition containing the second metal ions and water. In one embodiment, the method for producing a plating composition may further include an impurity removal step of removing at least a portion of impurities from the first plating composition.

[0010] By concentrating the first plating composition by removing a portion of the water, the first metal ions can be efficiently reduced by the metal. Furthermore, by removing water through a separation membrane, the first plating composition can be concentrated at a high rate to obtain a first concentrated solution while suppressing oxidation of the metal ions. Furthermore, by removing water from the first concentrated solution in a low-oxygen partial pressure environment, the load on the reduction reaction in the first metal ion reduction step can be reduced while suppressing oxidation of the low-oxidized metal ions contained in the first concentrated solution, thereby enabling more efficient production of the plating composition. The plating composition production method may also be a plating composition regeneration method for regenerating a plating composition usable for plating processing (e.g., a second plating composition) from a used plating composition or plating wastewater (e.g., a first plating composition).

[0011] One embodiment of a method for producing a plating composition will be described with reference to the drawings. FIG. 1 is a flowchart showing an example of the process sequence of the method for producing a plating composition. The method for producing a plating composition may include an optional impurity removal step S101, a first concentration step S102, a second concentration step S103, a first metal ion reduction step S104, and a second metal ion oxidation step S105. In the impurity removal step S101, at least a portion of impurities is removed from the first plating composition, which is a plating wastewater recovered from a plating tank or a water rinsing tank. In the first concentration step S102, a portion of water is removed from the first plating composition after impurity removal through a separation membrane to obtain a first concentrated solution. In the second concentration step S103, a portion of water is removed from the first concentrated solution in a low oxygen partial pressure environment to obtain a second concentrated solution. In the first metal ion reduction step S104, a first metal ion (e.g., tin(IV) ion) in a high oxidation state contained in the second concentrated solution is reduced to a metal (e.g., metallic tin) using an electrochemical device. The electrochemical apparatus includes a working electrode chamber equipped with a working electrode and a counter electrode chamber equipped with a counter electrode, separated by a diaphragm. The reduction of the first metal ions is carried out by introducing a second concentrated solution into the working electrode chamber and applying current to the working electrode as a cathode, resulting in the deposition of a metal on the working electrode. The second metal ion oxidation step S105 is carried out by applying current to a metal of the same type as the metal deposited on the working electrode as an anode, whereby the metal of the same type as the metal deposited on the working electrode is oxidized to a second metal ion (e.g., tin(II) ion) of a lower oxidation number (low oxidation state) and dissolved in the second concentrated solution in the working electrode chamber, thereby obtaining a second plating composition usable for plating.

[0012] 1, the first concentration step S102 and the second concentration step S103 are performed after the impurity removal step S101, but the impurity removal step S101 may be performed after the first concentration step S102 or the second concentration step S103, and then the first metal ion reduction step S104 may be performed. Also, the impurity removal step S101 may not be performed.

[0013] Impurity Removal Step In the impurity removal step, at least some of the impurities are removed from a first plating composition containing first metal ions and water. The plating composition from which at least some of the impurities have been removed is concentrated by removing some of the water, and the first metal ions are then electrochemically reduced using an electrochemical device including a counter electrode chamber and a working electrode chamber separated by a membrane, such as an ion exchange membrane, that is impermeable to the first metal ions. This can be explained, for example, as follows: Removing at least some of the impurities contained in the first plating composition is thought to suppress inhibition of the reduction of the first metal ions due to interactions between the impurities and the cathode, thereby further improving the reduction efficiency of the first metal ions at the cathode. Furthermore, for example, it is thought that inhibition of reduction due to impurities adhering to or damaging the ion exchange membrane or the like is suppressed, thereby further improving the reduction efficiency of the first metal ions at the cathode. Furthermore, for example, it is thought that impurities clog or damage the separation membrane in the first concentration step, reducing the concentration efficiency. However, removing at least some of the impurities is thought to suppress this decrease in concentration efficiency.

[0014] The first plating composition may be, for example, a plating wastewater used in metal plating, or a plating wastewater obtained by rinsing a metal-plated article with water. The first plating composition may contain impurities. The impurities refer to substances that may inhibit the reduction of the first metal ions in the first metal ion reduction step described below, substances that may inhibit concentration in the first concentration step described below, and the like. Specific examples of impurities include additives such as surfactants, leveling agents, brighteners, and antioxidants, metal components other than the first metal ions, dust, precipitates, and the like.

[0015] The first plating composition may contain a surfactant as at least a portion of the impurities. The surfactant contained in the first plating composition may be any of a nonionic surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, etc. Furthermore, the surfactant may function as a so-called brightener, leveler, etc. in the plating composition. From the viewpoint of the reduction efficiency of the first metal ion, the surfactant may contain at least one surfactant selected from the group consisting of a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant. The first plating composition may contain only one surfactant, or a combination of two or more surfactants.

[0016] Examples of nonionic surfactants include ester surfactants in which a polyhydric alcohol such as glycerin, sorbitol, or sucrose is ester-bonded to a fatty acid; ether surfactants formed by adding ethylene oxide, propylene oxide, or the like to a compound having a hydroxyl group such as a higher alcohol or an alkylphenol; and ester-ether surfactants formed by adding ethylene oxide, propylene oxide, or the like to an ester surfactant. Specific examples of nonionic surfactants include polyethylene glycol, polypropylene glycol, polyoxyethylene octylphenol, polyoxyethylene β-naphthyl ether, polyoxyethylene alkylamine, polyoxyethylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, glycerin fatty acid ester and its ethylene oxide adduct, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid monoethanolamide and its ethylene oxide adduct, fatty acid N-methyl monoethanolamide and its ethylene oxide adduct, fatty acid diethanolamide and its ethylene oxide adduct, sucrose fatty acid ester, alkyl (poly)glycerin ether, polyglycerin fatty acid ester, polyethylene glycol fatty acid ester, fatty acid methyl ester ethoxylate, N-long-chain alkyldimethylamine oxide, etc. Nonionic surfactants may have fluorine atoms substituted in their structures.

[0017] Examples of cationic surfactants include amine salts and quaternary ammonium salts.Specific examples of cationic surfactants include alkyl (or alkenyl) trimethyl ammonium salts, alkyl (or alkenyl) triethyl ammonium salts, dialkyl (or alkenyl) dimethyl ammonium salts, alkyl (or alkenyl) quaternary ammonium salts, mono- or dialkyl (or alkenyl) quaternary ammonium salts containing ether groups, ester groups, or amide groups, alkyl (or alkenyl) pyridinium salts, alkyl (or alkenyl) dimethyl benzyl ammonium salts, alkyl (or alkenyl) isoquinolinium salts, dialkyl (or alkenyl) morphonium salts, polyoxyethylene alkyl (or alkenyl) amines, alkyl (or alkenyl) amine salts, polyamine fatty acid derivatives, amyl alcohol fatty acid derivatives, benzalkonium chloride, benzethonium chloride, etc.These cationic surfactants may have fluorine atoms substituted in their structures.

[0018] Amphoteric surfactants exhibit the properties of anionic surfactants in the alkaline range and the properties of cationic surfactants in the acidic range. Examples of amphoteric surfactants include carboxylates and sulfonates, and may be either amino acid-type or betaine-type. Specific examples of amphoteric surfactants include alkyldimethylaminoacetic acid betaine, alkyldimethylacetic acid betaine, alkyldimethylcarboxybetaine, alkyldimethylcarboxymethyleneammonium betaine, alkyldimethylammonioacetate, fatty acid amidopropyldimethylamino acid betaine, alkyloylamidopropyldimethylglycine, 2-alkyl-1-(2-hydroxyethyl)imidazolium-1-acetate, alkyldiaminoethylglycine, dialkyldiaminoethylglycine, and alkyldimethylamine oxide.

[0019] Examples of the anionic surfactant include carboxylates, sulfonates, sulfates, and phosphates.

[0020] When the first plating composition contains a surfactant, the surfactant content in the first plating composition may be, for example, 0.01 g / L or more and 10 g / L or less, and preferably 0.1 g / L or more or 5 g / L or less. The surfactant content in the plating composition after the impurities have been removed in the impurity removal step may be, for example, 0.005 g / L or more. The surfactant content can be measured using surface tension as an index. Specifically, it can be measured using a drop counter, a surface tensiometer, or the like.

[0021] The first metal ion contained in the first plating composition may be a metal ion in a more highly oxidized state than the second metal ion, or may be formed by oxidation of the second metal ion contained in the plating composition prior to use. Examples of the first metal ion include tin(IV) ions and iron(III) ions. The first metal ion contained in the first plating composition may be a simple metal ion or a complex ion. Examples of complexing agents that form complex ions include carboxylic acids, including gluconic acid (including gluconolactone), citric acid, glutaric acid, succinic acid, malic acid, tartaric acid, lactic acid, and salts or derivatives thereof; phosphoric acids, including tripolyphosphate, hydroxyethanediphosphonic acid, and salts thereof; sugars, including sorbitol, mannitol, and salts thereof; amino acids, including phenylalanine, glutamic acid, aspartic acid, alanine, glycine, and salts thereof; HEDTA, EDTA, and the like. The complexing agent may include at least one selected from the group consisting of these, and may include at least gluconic acid. The complexing agent may be used alone or in combination of two or more. When the first metal ion is a complex ion, the pH of the plating composition used for plating can be set to a weak acidity to a weak alkalinity, and corrosion of the plated object that is sensitive to strong acids or strong alkalis (for example, an object using an oxide as a component, such as a ceramic capacitor) can be suppressed.

[0022] The content of the first metal ion in the first plating composition may be, for example, 0.1 g / L or more and 100 g / L or less, and preferably 1 g / L or more. The content of the complexing agent in the plating composition may be, for example, equimolar to 20 times the molar amount of the first metal ion, and preferably 10 times or less. The content of the first metal ion in the plating composition is measured, for example, by inductively coupled plasma atomic emission spectroscopy (ICP-AES) or by oxidation-reduction titration with potassium iodate after reduction with iron powder.

[0023] The first plating composition may contain a second metal ion in addition to the first metal ion. A specific example of the second metal ion is a tin(II) ion when the first metal ion is a tin(IV) ion. Furthermore, a specific example of the second metal ion is an iron(II) ion when the first metal ion is an iron(III) ion. The second metal ion may be a simple metal ion or a complex ion. The complexing agent that forms the complex ion is the same as that for the first metal ion. When the first plating composition contains a second metal ion, the content of the second metal ion contained in the first plating composition may be, for example, 100 g / L or less, preferably 20 g / L or less. The content of the second metal ion contained in the plating composition is measured in the same manner as that for the first metal ion.

[0024] The second metal ion constituting the plating composition before use may be derived from a water-soluble metal salt. Specific examples of water-soluble metal salts include sulfates, chlorides, boron fluorides, alkanesulfonates, alkanolsulfonates, and aromatic sulfonates. The plating composition may contain at least one selected from the group consisting of these, and may contain at least an alkane sulfonate. Examples of the alkane sulfonate include alkanesulfonic acids having 1 to 3 carbon atoms, such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and 2-propanesulfonic acid.

[0025] The first plating composition may further contain alkali metal ions, ammonium ions, etc. The inclusion of alkali metal ions, ammonium ions, etc. increases the electrical conductivity, suppresses heat generation due to solution resistance during electroplating, and tends to improve electrodeposition uniformity. Examples of alkali metal ions include lithium ions, sodium ions, potassium ions, rubidium, and cesium. The alkali metal ions, ammonium ions, etc. may be added to the first plating composition, for example, as salts with an acid component. The inclusion of an acid component in the first plating composition improves, for example, the stability of the first plating composition. Examples of acid components include sulfuric acid, hydrochloric acid, alkanesulfonic acid, alkanolsulfonic acid, aromatic sulfonic acid, phosphoric acid, alkylcarboxylic acid, and arylcarboxylic acid. The first plating composition may contain at least one selected from the group consisting of these acids. These acids may be used alone or in combination of two or more.

[0026] The pH of the first plating composition may be, for example, 1 or more and 13 or less, preferably 3 or more or 4 or more, and preferably 11 or less or 9 or less. When the pH of the first plating composition is within the above range, the first metal ions tend to be reduced more efficiently. The pH of the first plating composition may be adjusted to a desired range, for example, with a pH adjuster. Examples of pH adjusters include alkali metal hydroxides, ammonia, and the like, in addition to the acid components described above.

[0027] The first plating composition may further contain an antioxidant. The inclusion of an antioxidant can, for example, improve the stability of the first plating composition and extend the bath life. Examples of antioxidants include hydroquinone, ascorbic acid, catechol, hypophosphorous acid, and erythorbic acid. When the first plating composition contains an antioxidant, the content of the antioxidant in the first plating composition may be, for example, 0.01 g / L or more and 20 g / L or less, and preferably 0.1 g / L or more or 5 g / L or less.

[0028] If the first plating composition includes an antioxidant, the impurity removal step may include removing at least a portion of the antioxidant, which may be accomplished by activated carbon treatment.

[0029] The first plating composition contains water as a solvent. The total concentration of solutes in the first plating composition may be, for example, 150 g / L or less, preferably 100 g / L or less, or 80 g / L or less. The total concentration of solutes in the first plating composition may be, for example, 1 g / L or more.

[0030] Examples of methods for removing impurities in the impurity removal step include thread filtration, activated carbon treatment, microfiltration, ultrafiltration, and gel filtration. The method for removing impurities in the impurity removal step may preferably include activated carbon treatment. The method for removing impurities using activated carbon treatment may include, for example, contacting the plating composition with activated carbon. By using activated carbon, at least a portion of the impurities can be more efficiently removed from the first plating composition. The impurity removal step may combine a method for electrostatically adsorbing impurities (e.g., contacting with an ion exchange resin) with activated carbon treatment.

[0031] Activated carbon is a porous material whose main component is carbon and that has been subjected to a chemical or physical activation process. The activated carbon used in the activated carbon process may be activated with chemicals or gases. The activated carbon may be powdered activated carbon, granular activated carbon, or a combination of these.

[0032] The specific surface area of ​​activated carbon is, for example, 200 m ２ / g or more 1500m ２ / g or less, and preferably 300m ２ / g or more, or 700m ２ / g or less. The specific surface area is measured based on the BET (Brunauer Emmett Teller) theory using nitrogen gas after heat treatment at 200°C for 6 hours as a pretreatment. The average pore diameter of the activated carbon may be, for example, 1.5 nm or more and 3.5 nm or less, and preferably 2.0 nm or more and 3.0 nm or less. The mesopore shape of the activated carbon may be, for example, an average pore width on the adsorption side measured by the INNES method of 2 nm or more and 30 nm or less, and preferably 4 nm or more and 10 nm or less. The average pore width on the desorption side measured by the INNES method may be, for example, 2 nm or more and 5 nm or less, and preferably 2 nm or more and 3.5 nm or less.

[0033] The amount of activated carbon used in contact with the first plating composition may be selected appropriately depending on the type of activated carbon. The amount of activated carbon used may be an amount sufficient to remove at least a portion of the impurities (e.g., surfactants) contained in the first plating composition, preferably an amount sufficient to remove 50% by mass or more, 70% by mass or more, or 90% by mass or more of the surfactants. The amount of activated carbon used may be selected depending on the method of contact with the first plating composition. For example, when contacting in a single pass, a larger amount of activated carbon may be required than when contacting by circulating the first plating composition.

[0034] The first plating composition may be contacted with the activated carbon by, for example, mixing the first plating composition with the activated carbon followed by solid-liquid separation, or by passing the plating composition through activated carbon held in a filter, cartridge, etc. The contact temperature between the first plating composition and the activated carbon may be, for example, 0°C or higher or 70°C or lower.

[0035] First Concentration Step In the first concentration step, a first concentrated solution is obtained by removing a portion of the water from a first plating composition containing first metal ions and water through a separation membrane. Generally, when concentrating a plating composition containing oxidizable metal ions by removing a portion of the water, the lower the metal ion concentration and the higher the temperature, the more likely the oxidation of the metal ions will proceed. By using a separation membrane to concentrate the first plating composition, the first plating composition can be concentrated quickly and in large quantities while suppressing the oxidation of the metal ions. The separation membrane may be a filtration membrane that can preferentially separate water from the first plating composition, and is preferably a filtration membrane that can selectively separate water.

[0036] In one embodiment, the separation membrane may be a filtration membrane known as a reverse osmosis membrane. A reverse osmosis membrane (hereinafter also referred to as an RO membrane) is a type of filtration membrane that allows water molecules to pass through while blocking substances other than water molecules, such as ions. A reverse osmosis membrane separates a high-salt solution A (e.g., a first plating composition) from a low-salt solution B (e.g., water). When a pressure greater than the difference in osmotic pressure between solutions A and B is applied to the high-salt solution A, only water molecules move from solution A to solution B. This removes a portion of the water from the first plating composition to obtain a first concentrated solution, and also provides reverse osmosis membrane-treated water.

[0037] Examples of the material for the separation membrane include polyamide, polysulfone, cellulose acetate, etc., and preferably polyamide including aromatic polyamide or crosslinked aromatic polyamide. For concentrating the first plating composition using the separation membrane, for example, a tubular module, a spiral module, etc. equipped with a separation membrane can be used.

[0038] The liquid feed pressure when concentrating the first plating composition using a separation membrane may be appropriately selected depending on the type of separation membrane used. The liquid feed pressure during concentration may be, for example, 0.1 MPa or more, preferably 0.5 MPa or more, 1 MPa or more, or 2 MPa or more. The liquid feed pressure may be, for example, 10 MPa or less. The temperature during concentration may be, for example, 0°C or more and 50°C or less, preferably 10°C or more and 40°C or less.

[0039] The first plating composition subjected to concentration using a separation membrane may be the first plating composition from which at least a portion of the impurities have been removed in the impurity removal step, or may be the first plating composition from which the impurities have not been removed, preferably the first plating composition from which at least a portion of the impurities have been removed in the impurity removal step.

[0040] The ratio of the volume of the first plating composition to the volume of the first concentrated solution from which some of the water has been removed via the separation membrane (concentration factor) may be, for example, 2 or more, and preferably 3 or more.

[0041] In the second concentration step, a portion of the water is removed from the first concentrate in a low-oxygen partial pressure environment to obtain a second concentrate. By removing a portion of the water from the first concentrate in a low-oxygen partial pressure environment, a second concentrate from which a portion of the water has been further removed can be obtained while effectively suppressing oxidation of metal ions contained in the first concentrate.

[0042] The low oxygen partial pressure environment in the second concentration step may be an environment in which the oxygen partial pressure is lower than that of the atmosphere, and can be achieved by substitution with an inert gas, reduced pressure, etc. Specifically, the oxygen partial pressure in the low oxygen partial pressure environment may be, for example, 10 kPa or less, preferably 2 kPa or less, or 1 kPa or less.

[0043] The low oxygen partial pressure environment in the second concentration step can be realized as an inert gas atmosphere by substitution with an inert gas. Examples of the inert gas in the inert gas atmosphere include rare gases such as argon, nitrogen gas, etc. The concentration of the inert gas in the inert gas atmosphere may be, for example, 80% by volume or more, preferably 90% by volume or more, 95% by volume or more, 98% by volume or more, or 99% by volume or more. The pressure in the inert gas atmosphere may be normal pressure or may be reduced below atmospheric pressure. The inert gas atmosphere under reduced pressure may be substituted with an inert gas and then reduced pressure, or an inert gas atmosphere may be created by supplying an inert gas when adjusting the degree of vacuum.

[0044] The low oxygen partial pressure environment in the second concentration step may be a low-pressure environment. The low-pressure environment may be a reduced-pressure environment lower than atmospheric pressure, and specifically, the pressure in the low-pressure environment may be, for example, 50 hPa or less, preferably 10 hPa or less, or 1 hPa or less.

[0045] In one embodiment, the second concentration step may be a step of removing a portion of water from the first concentrate in a low oxygen partial pressure environment to obtain a second concentrate. The low oxygen partial pressure environment may be, for example, an oxygen partial pressure of 10 kPa or less or an oxygen concentration of 10% by volume or less, preferably an oxygen partial pressure of 2 kPa or less or an oxygen concentration of 2% by volume or less, or preferably an oxygen partial pressure of 1 kPa or less or an oxygen concentration of 1% by volume or less.

[0046] Examples of methods for removing water in the second concentration step include a first concentration method in which a portion of the water is removed from the first concentrated liquid under reduced pressure, a second concentration method in which the first concentrated liquid is frozen and then a portion of the water is removed from the frozen first concentrated liquid under reduced pressure, and a third concentration method in which a mist containing water is generated from the first concentrated liquid under an inert gas atmosphere or under reduced pressure and at least a portion of the generated mist is removed.

[0047] In the first concentration method, a portion of the water is removed from the first concentrated liquid under reduced pressure. The degree of vacuum in the first concentration method can be, for example, 500 hPa or less, preferably 200 hPa or less, or 100 hPa or less. The degree of vacuum may be, for example, 1 hPa or more, or a reduced pressure of 100 hPa or more. In the first concentration method, a portion of the water may be removed while heating the first concentrated liquid under reduced pressure. When the first concentrated liquid is heated, the temperature may be, for example, 30°C or more and 80°C or less, preferably 35°C or more or 38°C or more, and preferably 70°C or less or 60°C or less. In the first concentration method, the first concentrated liquid may be stirred. The stirring method can be appropriately selected from commonly used stirring methods. Examples of stirring methods include a method of rotating a container containing the first concentrated liquid to stir, a method of stirring the first concentrated liquid in a container using a rotor or the like, and a method of pouring the first concentrated liquid into a container while spraying it. In the first concentration method, the atmosphere inside the container can be replaced with an inert gas before reducing the pressure, thereby removing part of the water under an inert gas atmosphere.

[0048] The second concentration method includes freezing the first concentrated liquid and removing a portion of the water from the frozen first concentrated liquid under reduced pressure. The freezing of the first concentrated liquid can be performed by lowering the liquid temperature of the first concentrated liquid to, for example, −15°C or lower, preferably −25°C or lower. It is preferable to replace the atmosphere inside the container with an inert gas during freezing. In the second concentration method, the container containing the frozen first concentrated liquid is depressurized, and a portion of the water contained in the first concentrated liquid is removed by freeze-drying, which sublimes the solid state. The degree of vacuum in the second concentration method may be, for example, 10 hPa or lower, preferably 1 hPa or lower. The second concentration method can be performed, for example, using a freeze dryer. According to the second concentration method, water can be removed at low temperatures under highly reduced pressure, thereby more effectively suppressing oxidation of metal ions. In the second concentration method, a portion of the water can be removed under an inert gas atmosphere by replacing the atmosphere inside the container with an inert gas before depressurizing.

[0049] The third concentration method involves generating a mist containing water from the first concentrated liquid (hereinafter also referred to as "atomization") and removing at least a portion of the generated mist. One method for generating a mist containing water from the first concentrated liquid is ultrasonic atomization, which applies ultrasonic vibrations to the first concentrated liquid. Ultrasonic atomization is a phenomenon in which ultrasonic vibrations are applied to a liquid, generating a fountain-like liquid column on the liquid surface, and fine droplets (mist), mainly measuring several microns, are generated from the sides of the liquid column. Ultrasonic atomization can separate substances at the molecular cluster level by misting the liquid without heating it. Separation of substances by ultrasonic atomization is possible, for example, by utilizing the fact that molecules of the same substance tend to cluster in liquid and the fact that clusters vary in size depending on the substance. The third concentration method can be performed, for example, using an atomization separation device (e.g., manufactured by NanoMist Technologies, Inc.).

[0050] Specifically, a portion of the water can be removed from the first concentrated liquid as follows. Ultrasonic vibrations are applied to the first concentrated liquid to generate a mist consisting of water clusters and a mist containing water and other components contained in the first concentrated liquid. The generated mist is separated using a classification device such as a cyclone, with the "light mist" consisting of water clusters rising and the "heavy mist" containing components other than water falling. The light mist, water, is liquefied by condensation through cooling or other means and removed from the first concentrated liquid. Meanwhile, the heavy mist can be recovered by allowing it to fall under its own weight and liquefy. In the third concentration method, ultrasonic atomization is performed in an inert gas atmosphere, and an inert gas is used in the airflow used in the cyclone, thereby removing a portion of the water in an inert gas atmosphere. According to the third concentration method, a portion of the water can be removed in an inert gas atmosphere without heating the first concentrated liquid, thereby more effectively suppressing the oxidation of metal ions.

[0051] In the third concentration method, ultrasonic atomization may be performed while heating the first concentrated liquid. When ultrasonic atomization is performed while heating, the liquid temperature of the first concentrated liquid may be, for example, 20°C or higher and 80°C or lower, preferably 20°C or higher or 30°C or higher, and preferably 70°C or lower.

[0052] The total concentration of solutes in the second concentrate obtained by removing a portion of the water from the first concentrate may be, for example, 30 g / L or more, preferably 50 g / L or more, or 80 g / L or more. The total concentration of solutes in the second concentrate may be, for example, 500 g / L or less. In the first concentration step, the ratio of the volume of the first concentrate to the volume of the second concentrate (concentration factor) may be, for example, 2 or more and 20 or less, preferably 3 or more or 10 or less. By controlling the concentration factor of the first concentrate in the first concentration step within the above range, the first metal ions can be reduced more efficiently in the first metal ion reduction step.

[0053] First Metal Ion Reduction Step In the first metal ion reduction step, the first metal ions contained in the second concentrated solution are reduced using the working electrode of the electrochemical device as the cathode to obtain a metal element formed by the reduction of the first metal ions. The first metal ion reduction step may be performed using an electrochemical device including a working electrode chamber having a working electrode and a counter electrode chamber having a counter electrode, the working electrode chamber and the counter electrode chamber being separated by at least one diaphragm selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane. The second concentrated solution is introduced into the working electrode chamber of the electrochemical device. An aqueous solution containing conductive ions may be placed in the counter electrode chamber of the electrochemical device. Placing the aqueous solution containing conductive ions in the counter electrode chamber enables more efficient reduction of the first metal ions.

[0054] Examples of materials for the working electrode provided in the working electrode chamber include gold, platinum, platinum-coated titanium, silver, nickel, graphite, tin, titanium, iridium oxide, and ruthenium oxide. Examples of materials for the counter electrode include platinum, platinum-coated titanium, gold, nickel, iridium oxide, ruthenium oxide, titanium, graphite, and palladium. The working electrode chamber and the counter electrode chamber are separated, for example, by an ion exchange membrane. This allows for more efficient reduction of the first metal ion. The ion exchange membrane may be a cation exchange membrane, an anion exchange membrane, or a combination of both. The ion exchange membrane may be appropriately selected from commercially available ion exchange membranes. The ion exchange membrane may include at least a cation exchange membrane from the viewpoint of the reduction efficiency of the first metal ion. For example, the cation exchange membrane may include a fluororesin copolymer based on sulfonated tetrafluoroethylene. In addition, instead of the ion exchange membrane, a membrane that is difficult for the first metal ions to pass through, such as a reverse osmosis membrane (RO membrane) or a nanofiltration membrane (NF membrane, loose RO membrane), may be used.

[0055] When a conductive ion-containing aqueous solution is placed in the counter electrode chamber, the conductive ion-containing aqueous solution may contain at least water and a water-soluble metal salt. The water-soluble metal salt may contain, as metal ions, for example, alkali metal ions, alkaline earth metal ions, etc. The water-soluble metal salt may also contain, as anions, for example, sulfate ions, nitrate ions, phosphate ions, etc.

[0056] In the first metal ion reduction step, at least a portion of the first metal ions in the second concentrated solution introduced into the working electrode chamber are reduced to elemental metals by a first electrolysis process using the working electrode as a cathode. The elemental metals produced by the reduction may be deposited on the working electrode, for example. The current density in the electrolysis of the first metal ions may be appropriately selected depending on the type of first metal ions. The current density may be, for example, 0.05 A / dm ２ 10A / dm or more ２ may be less than or equal to 0.1 A / dm ２ or more, or 5A / dm ２The temperature during electrolysis may be, for example, 20° C. or higher and 80° C. or lower, and preferably 30° C. or higher or 75° C. or lower. The time required for electrolysis may be, for example, 10 minutes or longer and 200 hours or shorter.

[0057] Second Metal Ion Oxidation Step In the second metal ion oxidation step, a metal of the same type as the metal produced by reduction in the first metal ion reduction step is oxidized to second metal ions by a second electrolysis process using the working electrode as the anode. In the second metal ion oxidation step, a metal of the same type as the metal deposited on the working electrode in the first metal ion reduction step may be oxidized to second metal ions by electrolysis using the working electrode as the anode. The second metal ion oxidation step may be performed using the same electrochemical device subsequent to the reduction of the first metal ions in the first metal ion reduction step. That is, the metal deposited on the working electrode in the first metal ion reduction step may be oxidized to second metal ions by electrolysis using the working electrode as the anode.

[0058] The current density in the electrolysis of a metal may be appropriately selected depending on the type of metal. For example, the current density is 0.5 A / dm ２ More than 100A / dm ２ The temperature for electrolysis of the metal may be, for example, 10° C. or higher and 80° C. or lower, and preferably 15° C. or higher or 75° C. or lower. The time required for electrolysis may be, for example, 0.2 hours or higher and 10 hours or lower.

[0059] When the method for producing a plating composition includes an impurity removal step and the removed impurities include a surfactant, the method for producing a plating composition may further include a step of adding a surfactant to the second plating composition obtained in the second metal ion oxidation step. Plating is performed using a plating composition to which a surfactant has been added, resulting in a plating having a better surface. The surfactant added may be the same type as the surfactant removed in the impurity removal step. Furthermore, the amount of surfactant added may be approximately the same as the amount of surfactant removed in the impurity removal step.

[0060] The method for producing a plating composition according to this embodiment may be used in combination with a plating method or a method for producing electronic components that includes a plating step. By using the method for producing a plating composition in combination, it is possible to suppress discharge of plating wastewater in the plating method or the method for producing electronic components.

[0061] Plating Method The plating method includes a plating composition production step and a plating step of contacting an object to be plated with a plating solution containing at least a portion of the plating composition obtained in the production step to form a plating layer on the surface of the object to be plated. The plating composition production step is the same as the plating composition production method described above. By using a plating solution containing the plating composition obtained by the plating composition production method described above, a plating layer of excellent quality equivalent to that formed when a plating solution prepared immediately before use is used can be formed on the object to be plated.

[0062] In the plating process, a plating solution is brought into contact with an object to be plated to form a plating layer on the surface of the object to be plated. The plating layer may be, for example, a tin plating layer. The plating process may be electrolytic plating or electroless plating, preferably electrolytic plating. The plating solution may be a commonly used tin plating solution, except that it contains at least a portion of the plating composition produced in the manufacturing process. The plating solution may be composed of, for example, tin (II) ions, a surfactant, a complexing agent, etc. In addition to the produced plating composition, the plating solution may further contain, as necessary, a surfactant or the like that may be removed in the manufacturing process.

[0063] There are no particular limitations on the object to be plated to which the plating method is applied, as long as it is an article on whose surface a plating layer can be formed, such as a ceramic body having a conductive layer on its surface, a composite body containing a resin and a metal magnetic powder, a substrate, an electrode provided on a base material, etc.

[0064] The thickness of the plating layer formed in the plating step is not particularly limited and may be appropriately selected depending on the purpose, etc. The thickness of the plating layer may be, for example, 0.01 μm to 100 μm, preferably 0.1 μm to 50 μm, more preferably 0.3 μm to 10 μm, for example, 0.3 μm to 3 μm or 1 μm to 5 μm.

[0065] In the plating step, a known plating method can be applied, such as barrel plating, centrifugal plating, rack plating, or the like.

[0066] 2. Method for Manufacturing Electronic Components The method for manufacturing electronic components includes a step of manufacturing a plating composition, and a step of contacting a substrate having a conductive layer on its surface with a plating solution containing at least a portion of the plating composition obtained in the manufacturing step, to form an electrode layer including a plating layer on the surface of the conductive layer. The manufacturing step of the plating composition is the same as in the manufacturing method of the plating composition described above. By using a plating solution containing the plating composition obtained by the manufacturing method of the plating composition described above, it is possible to form external electrodes including an electrode layer of excellent quality equivalent to that obtained by using a plating solution prepared just before use, and it is possible to manufacture highly reliable electronic components.

[0067] For details of electronic components manufactured by the manufacturing method for electronic components, see, for example, JP 2021-027195 A, WO 2023 / 171394, WO 2020 / 218218 (the disclosures of these documents are incorporated herein by reference in their entirety).

[0068] In the electrode formation step, a plating solution is brought into contact with an element having a conductive layer on its surface to form an electrode layer including a plating layer. The plating method in the electrode formation step may be electrolytic plating or electroless plating, preferably electrolytic plating. The plating solution may be a commonly used plating solution except that it contains at least a portion of the plating composition obtained in the plating composition production step. The plating solution may be composed of, for example, tin (II) ions, a surfactant, a complexing agent, etc. In addition to the produced plating composition, the plating solution may further contain, as necessary, a surfactant or the like that may be removed during the production step.

[0069] The element body subjected to the electrode formation step may be a component body of an electronic component. The component body is not particularly limited, and may be, for example, a multilayer ceramic capacitor, an inductor, a resistor, an LC composite component, a thermistor, or the like. In one embodiment, the component body may be a multilayer ceramic capacitor. The component body may be constructed using a method commonly used depending on the type of component body. The material of the component body is not particularly limited, and may be a material commonly used depending on the type of component body. Examples of materials include ceramic, resin, metal, and composites thereof. In one embodiment, the material of the component body may be ceramic.

[0070] The thickness of the plating layer included in the electrode layer formed in the electrode formation step is not particularly limited and may be appropriately selected depending on the purpose, etc. The thickness of the electrode layer may be, for example, 0.01 μm to 100 μm, preferably 0.1 μm to 50 μm, more preferably 0.3 μm to 10 μm, for example, 0.3 μm to 3 μm or 1 μm to 5 μm.

[0071] In the electrode formation step, a known plating method can be applied, such as barrel plating, centrifugal plating, rack plating, or the like.

[0072] An example of steps included in a method for manufacturing an electronic component will be described with reference to the drawings. FIG. 2 is a schematic diagram showing a portion of the steps of a method for manufacturing an electronic component according to one embodiment of the present invention. In this method, element bodies having a conductive layer on their surfaces are introduced into a tin plating tank 10 by an introduction means 12, and an electrode layer including a tin plating layer is formed on the conductive layer of the element bodies introduced into the tin plating tank 10. Water evaporates 16 from the tin plating tank 10. Next, the element bodies with the electrode layer formed thereon are pumped out of the tin plating tank by an extraction means 14 into a rinsing tank 20. For example, a countercurrent multistage rinsing tank is used as the rinsing tank 20. The element bodies are pumped downstream of the countercurrent multistage rinsing tank and move upstream. The element bodies with the electrode layer formed thereon are separated from the countercurrent multistage rinsing tank in the most upstream tank by a separation means 24. The element bodies with the separated electrode layer formed thereon are subjected to a drying process. In the countercurrent multistage rinsing tank 20, water is supplied from the upstream side by a water supply means 22, and the rinsing water moves downstream. The rinsing water (first plating composition) 26 taken out from the most downstream tank is introduced into a plating composition manufacturing apparatus 30.

[0073] In the plating composition manufacturing apparatus 30, at least a portion of impurities (e.g., surfactants) is removed from tin-containing wash water using an impurity removal means 32 employing activated carbon. A first concentrator 36 employing a separation membrane removes a portion of the water from the wash water, yielding a first concentrate. Water 36a removed from the wash water is supplied to the wash tank 20 as reclaimed water 26. A second concentrator 37 removes a portion of the water from the first concentrate, yielding a second concentrate, in a low-oxygen partial pressure environment. Water 37a removed from the second concentrate is supplied to the wash tank 20 as reclaimed water 26, along with water 36a removed from the wash water. The second concentrate is introduced into an electrochemical device 34 having a working electrode chamber and a counter electrode chamber separated by a membrane. The second concentrate may contain tin(IV) ions as the first metal ions and may further contain tin(II) ions as the second metal ions. In the electrochemical device 34, at least a portion of the tin(IV) ions in the rinse water are reduced to metallic tin using the working electrode as the cathode. Furthermore, if the second concentrate contains tin(II) ions, at least a portion of the tin(II) ions in the second concentrate may be reduced to metallic tin using the working electrode as the cathode. Next, at least a portion of the reduced metallic tin or the tin substrate is oxidized to tin(II) ions using the working electrode as the anode to produce a second plating composition 38 that can be reused in plating processes. The produced second plating composition 36 may be added with additives such as surfactants as needed, and then introduced into the tin plating tank 10 for reuse. According to one aspect of this embodiment, tin-containing rinse water that would previously have been discarded can be reused as a regenerated plating composition, contributing to a reduction in waste.

[0074] The invention according to the present disclosure may include, for example, the following aspects: [1] A method for producing a plating composition, comprising: removing at least a portion of impurities from a first plating composition containing first metal ions and water, removing a portion of the water from the first plating composition through a separation membrane to obtain a first concentrated solution, removing a portion of the water from the first concentrated solution in a low oxygen partial pressure environment to obtain a second concentrated solution, introducing the second concentrated solution into a working electrode chamber separated by a counter electrode chamber having a counter electrode and at least one membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane and having a working electrode, reducing at least a portion of the first metal ions in the second concentrated solution to a metal using the working electrode as a cathode, and oxidizing a metal identical to the reduced metal to a second metal ion having a lower oxidation number than the first metal ion using the working electrode as an anode to obtain a second plating composition containing the second metal ions and water.

[0075] [2] The manufacturing method according to [1], wherein the first plating composition further contains a surfactant.

[0076] [3] The method according to [2], further comprising removing at least a portion of the surfactant from the first plating composition.

[0077] [4] The method according to any one of [1] to [3], wherein the separation membrane comprises a reverse osmosis membrane.

[0078] [5] The method according to any one of [1] to [4], wherein obtaining the second concentrated liquid includes removing a portion of the water from the first concentrated liquid under reduced pressure.

[0079] [6] The production method according to any one of [1] to [5], wherein obtaining the second concentrated liquid includes freezing the first concentrated liquid and removing a portion of the water from the frozen first concentrated liquid under reduced pressure.

[0080] [7] The manufacturing method according to any one of [1] to [4], wherein obtaining the second concentrated liquid includes generating a mist containing water from the first concentrated liquid and removing at least a portion of the generated mist.

[0081] [8] The manufacturing method according to any one of [1] to [7], wherein the first plating composition has a total solute concentration of 150 g / L or less.

[0082] [9] The manufacturing method according to any one of [1] to [8], wherein the second concentrated solution has a total solute concentration of 30 g / L or more.

[0083]

[10] The manufacturing method according to any one of [1] to [9], wherein the first metal ions include tin (IV) ions, and the second metal ions include tin (II) ions.

[0084]

[11] A plating composition obtained by the manufacturing method according to any one of [1] to

[10] .

[0085] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0086] Preparation of Plating Composition A plating composition having the composition shown below was prepared using purified water, potassium stannate (IV) as a tin (IV) ion source, tin (II) methanesulfonate as a tin (II) ion source, gluconic acid, a cationic surfactant containing decyltrimethylammonium chloride, hydroquinone, and sodium methanesulfonate.

[0087] Composition: Tin (IV) ions: 0.16 mol / L, Tin (II) ions: 0.04 mol / L, Gluconic acid: 0.8 mol / L, Methanesulfonic acid: 1.2 mol / L, Surfactant: 1 g / L, Hydroquinone: 1 g / L, Sodium ions: 1.4 mol / L

[0088] Example 1: The plating composition prepared above was diluted 30 times with purified water to form a first plating composition. The resulting first plating composition was passed through an activated carbon filter (FCC-S, manufactured by Nippon Filter Co., Ltd.) at a feed pressure of 0.1 MPa to remove the surfactant and obtain a filtered solution. The filtered solution was then passed through a reverse osmosis membrane (RO membrane; DRA991C, manufactured by Daisen Membrane Systems Co., Ltd.) at a feed pressure of 2 MPa to remove a portion of the water and concentrate the solution, thereby obtaining a first concentrated solution concentrated to a concentration of approximately 1 / 5 of the target concentration. The resulting first concentrated solution was then purged with nitrogen gas and then concentrated using a rotary evaporator (N-2110, manufactured by Tokyo Rikakikai Co., Ltd.) under a nitrogen atmosphere at 100 hPa, 60°C, and 60 rpm to obtain a second concentrated solution with component concentrations equal to those of the prepared plating composition.

[0089] Metallic tin was reduced and precipitated from the second concentrated solution as follows: A Pt plate was used as the working electrode, a Pt / Ti mesh plate was used as the counter electrode, and a cation exchange membrane (Nafion （ＴＭ） An electrochemical device was prepared, isolated by a separator (424). The second concentrated solution was introduced into the working electrode chamber of the electrochemical device, and a methanesulfonic acid solution was introduced into the counter electrode chamber. The working electrode was set as the cathode, and the counter electrode was set as the anode, and a current of 1 A / dm ２ The reduction reaction of tin ions was carried out at a current density of 1 A / dm. The solution temperature was kept at 65°C or less. Then, the working electrode was used as the anode and the counter electrode was used as the cathode. ２ The deposited metallic tin was subjected to an oxidation reaction at a current density of 1000 kJ / min to obtain a second plating composition.

[0090] The components of the obtained second plating composition were confirmed by analysis, and it was confirmed that the second plating composition could be reused as a tin plating solution by adding components that were lacking in the plating composition.

[0091] Comparative Example 1 A second concentrated liquid was obtained in the same manner as in Example 1, except that the first concentrated liquid was concentrated in the air.

[0092] Evaluation of Tin(II) Ion Concentration The tin(II) ion concentrations of the second concentrated solutions obtained in Example 1 and Comparative Example 1 were evaluated as follows. The results are shown in Table 1. The first plating composition before concentration was designated Reference Example 0, a sample that was left for 8 hours at room temperature (27°C) in a nitrogen atmosphere without being concentrated using a rotary evaporator was designated Reference Example 1, and a sample that was left for 8 hours at room temperature (27°C) in an air atmosphere without being concentrated using a rotary evaporator was designated Reference Example 2. Table 1 shows the relative concentrations, with the tin(II) ion concentration in Reference Example 0 set to 100%.

[0093] The concentrations of tin(IV) ions and tin(II) ions were evaluated by combining redox titration and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Specifically, the redox titration was performed by titrating starch as an indicator in 2 M hydrochloric acid with an iodine standard solution to calculate the concentration of tin(II) ions. The total concentration of tin ions was calculated using ICP-AES, and the concentration of tin(IV) ions was calculated by subtracting the concentration of tin(II) ions.

[0094]

[0095] Table 1 shows that concentration under a nitrogen atmosphere suppresses the oxidation of tin (II) ions.

[0096] Example 2 Instead of concentration using a rotary evaporator, a freeze dryer (freeze dryer FDU-1110 manufactured by Tokyo Rikakikai Co., Ltd.) was used to perform concentration as follows. 1500 mL of the first concentrate was placed in a container, frozen in a freezer set to -30°C, and then set in the freeze dryer. The freeze dryer was set to -40°C and the degree of vacuum was 10 Pa. The atmosphere inside the device was replaced with nitrogen before reducing the pressure. After processing in the freeze dryer for about one day, the concentrate was concentrated to 300 mL.

[0097] The tin (II) ion concentration in the second concentrate after concentration by freeze-drying was 5 times that of the first concentrate before concentration. Considering the concentration ratio, it is believed that there was no oxidation of the tin (II) ions during freeze-drying.

[0098] Example 3 Instead of concentration using a rotary evaporator, concentration was carried out using an atomization separation device (NanoMist Technologies Inc., atomization separation device USA-L5) that removes water by misting using ultrasonic vibrations, as follows. 1500 mL of the first concentrated liquid was placed in a container connected to the device. The inside of the device was purged with nitrogen gas to replace the nitrogen atmosphere. The bath was heated to a liquid temperature of 60°C, and the liquid was concentrated to 300 mL by treatment for approximately 8 hours.

[0099] The tin (II) ion concentration of the second concentrate after concentration by the atomization separation device was 5 times that of the first concentrate before concentration. Considering the concentration ratio, it is thought that there was no oxidation of tin (II) ions in the atomization separation device.

[0100] The disclosure of Japanese Patent Application No. 2024-012029 (filing date: January 30, 2024) is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A method for producing a plating composition, comprising: removing a portion of the water from a first plating composition containing first metal ions and water through a separation membrane to obtain a first concentrated solution; removing a portion of the water from the first concentrated solution in a low oxygen partial pressure environment to obtain a second concentrated solution; introducing the second concentrated solution into a working electrode chamber separated by a counter electrode chamber and at least one membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, and reducing at least a portion of the first metal ions in the second concentrated solution to metal, using the working electrode as a cathode; and oxidizing a metal identical to the reduced metal to a second metal ion having a lower oxidation number than the first metal ion, using the working electrode as an anode, to obtain a second plating composition containing the second metal ions and water.

2. The manufacturing method according to claim 1, wherein the first plating composition further comprises a surfactant.

3. The method of claim 2, further comprising removing at least a portion of said surfactant from said first plating composition.

4. The method according to any one of claims 1 to 3, wherein the separation membrane comprises a reverse osmosis membrane.

5. A manufacturing method according to any one of claims 1 to 4, wherein obtaining the second concentrated liquid comprises removing a portion of the water from the first concentrated liquid by vaporizing the water under reduced pressure.

6. A manufacturing method described in any one of claims 1 to 5, wherein obtaining the second concentrated liquid includes freezing the first concentrated liquid and removing a portion of the water from the frozen first concentrated liquid under reduced pressure.

7. A manufacturing method described in any one of claims 1 to 4, wherein obtaining the second concentrated liquid includes generating a mist containing water from the first concentrated liquid and removing at least a portion of the generated mist.

8. A manufacturing method according to any one of claims 1 to 7, wherein the first plating composition has a total solute concentration of 150 g / L or less.

9. A manufacturing method according to any one of claims 1 to 8, wherein the second concentrated solution has a total solute concentration of 30 g / L or more.

10. The method of any one of claims 1 to 9, wherein the first metal ions include tin (IV) ions and the second metal ions include tin (II) ions.

11. A plating composition obtained by the manufacturing method according to any one of claims 1 to 10.

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