Manufacturing method of plating composition

Abstract

To provide a method for manufacturing a plating composition that can be reused as a plating treatment liquid from a plating composition derived from a used plating treatment liquid.SOLUTION: A manufacturing method of a plating composition comprises: in a working electrode chamber having a working electrode and including a first plating composition comprising a metal complex including a first metal ion and a complexing agent, and a complexing agent, reducing a part of the first metal ions included in the first plating composition to metal with the working electrode as a cathode to obtain a reduction treatment liquid and a working electrode to which metal is adhered; separating the reduction treatment liquid into a permeate that passes through a nanofilter having a molecular weight cut-off of 300 Da or more and 800 Da or less and includes the complexing agent, and a concentrate that does not pass through the nanofilter and includes the metal complex; and introducing the permeate into the working electrode chamber having the working electrode to which metal is adhered, and oxidizing at least a part of the adhered metal to a second metal ion with the working electrode to which metal is adhered as an anode in the permeate to obtain a second plating composition including the second metal ion and the complexing agent.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a plating composition. [Background technology]

[0002] Regarding plating compositions used in metal plating, Patent Document 1 proposes a method for regenerating a plating solution in which electrolytically deposited tin is used to reduce tin(IV) ions to tin(II) ions. Patent Document 2 also proposes a method for regenerating a plating composition by oxidizing and reducing two types of metal components in the plating composition using an apparatus equipped with a working electrode chamber, a counter electrode chamber, and an ion exchange membrane separating them. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2004-534151 [Patent Document 2] Special Publication No. 2015-518923 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one aspect of the present invention is to provide a method for producing a plating composition that can efficiently produce a plating composition that contains metal ions in a low oxidation state and that can be reused as a plating treatment solution from a plating composition that is derived from a used plating treatment solution and contains metal ions in a high oxidation state. [Means for solving the problem]

[0005] The first aspect is a method for producing a plating composition, which includes the steps of: reducing a portion of the first metal ions contained in the first plating composition to metal using the working electrode as a cathode in a working electrode chamber equipped with a working electrode; permeating the reduced solution through a nanofilter having a molecular weight cutoff of 300 Da to 800 Da to separate it into a permeate containing the complexing agent and a concentrated solution that does not permeate the nanofilter and contains the metal complex; introducing the permeate into a working electrode chamber equipped with the working electrode equipped with the metal; and oxidizing at least a portion of the metal attached to the working electrode, using the working electrode equipped with the metal as an anode, in the permeate to second metal ions having a lower oxidation number than the first metal ions to obtain a second plating composition containing the second metal ions and the complexing agent. [Effects of the Invention]

[0006] According to one aspect of the present invention, it is possible to provide a method for producing a plating composition that can efficiently produce a plating composition that contains metal ions in a low oxidation state and that can be reused as a plating treatment solution from a plating composition that is derived from a used plating treatment solution and contains metal ions in a high oxidation state. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a flowchart showing an example of the order of steps in a method for producing a plating composition. [Figure 2] 1 is a flowchart showing an example of the order of steps in a method for producing a plating composition according to another embodiment. [Figure 3] 1A to 1C are schematic diagrams illustrating an example of a process for manufacturing an electronic component. DETAILED DESCRIPTION OF THE INVENTION

[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, when a composition contains multiple substances corresponding to each component, the term refers to the total amount of the multiple substances present in the composition, unless otherwise specified. 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. Hereinafter, embodiments of the present invention will be described in detail. However, the embodiments described below are merely examples of methods for producing plating compositions to embody the technical concepts of the present invention, and the present invention is not limited to the methods for producing plating compositions described below.

[0009] Method for producing plating composition The method for producing a plating composition includes a first plating composition containing a metal complex including a first metal ion and a complexing agent, and the complexing agent, and includes a first step of reducing a portion of the first metal ions contained in the first plating composition to metal in a working electrode chamber equipped with a working electrode, using the working electrode as a cathode, to obtain a reduced-treatment solution and a working electrode having a metal attached thereto; a second step of passing the reduced-treatment solution through a nanofilter having a molecular weight cutoff of 300 Da to 800 Da, and separating the reduced-treatment solution into a permeate containing the complexing agent and a concentrated solution that does not pass through the nanofilter and contains the metal complex; and a third step of introducing the permeate into a working electrode chamber equipped with a working electrode having a metal attached thereto, and oxidizing at least a portion of the attached metal in the permeate, using the working electrode having the metal attached as an anode, to second metal ions having a lower oxidation number than the first metal ions, to obtain a second plating composition containing the second metal ions and the complexing agent.

[0010] The reduction treatment solution, from which a portion of the first metal ions has been removed, is passed through a nanofilter having a specific molecular weight cutoff to separate it into a permeate and a concentrate, and the second metal ions are oxidized in the permeate to produce a second plating composition, which exhibits excellent plating quality when reused as a plating treatment solution. This is thought to be because, for example, the nanofilter can separate components contained in the reduction treatment solution that may cause quality degradation during plating treatment into the concentrate.

[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 a first metal ion reduction step S101, a membrane permeation step S102, and a second metal ion generation step S103. In the first metal ion reduction step (also referred to as the first step) S101, a first metal ion (e.g., tin(IV) ion) with a high oxidation state contained in the first plating composition is reduced to a metal (e.g., metallic tin) using an electrochemical device. The electrochemical device is configured by separating a working electrode chamber equipped with a working electrode and a counter electrode chamber equipped with a counter electrode by a diaphragm. The first metal ion is reduced by introducing the first plating composition into the working electrode chamber and applying a current to the working electrode as a cathode. When the first metal ion is reduced, a metal is deposited on the working electrode, resulting in a working electrode with the metal attached and a reduction-treated solution in which some of the first metal ions have been removed from the first plating composition. In the membrane permeation step S102, the reduction treatment solution is passed through a nanofilter with a molecular weight cutoff of, for example, 300 Da to 800 Da, thereby separating it into a permeate that permeates the nanofilter and a concentrated solution that does not permeate the nanofilter. The membrane permeation step removes components unnecessary for the plating treatment solution from the permeate. In the second metal ion generation step (also referred to as the third step) S103, the permeate is introduced into a working electrode chamber equipped with a working electrode to which a metal is attached, and at least a portion of the attached metal in the permeate is oxidized to second metal ions having a lower oxidation number than the first metal ions, using the working electrode to which the metal is attached as the anode, thereby obtaining a second plating composition containing the second metal ions.

[0012] FIG. 2 is a flowchart showing an example of the process sequence of another embodiment of the method for producing a plating composition. Another embodiment of the method for producing a plating composition may include a surfactant removal step S201 in which at least a portion of the surfactant is removed from plating wastewater recovered from a plating tank or a water-rinsing tank to obtain a first plating composition. Alternatively, the first plating composition may be obtained by further removing a portion of the water in a concentration step S202 after removing the surfactant, or by obtaining the first plating composition after the surfactant removal step S201 without going through a concentration step. Details of the surfactant removal step and the concentration step will be described later. From the obtained first plating composition, a second plating composition is obtained through a first metal ion reduction step S203, a membrane permeation step S204, and a second metal ion generation step S205, as described above.

[0013] In yet another embodiment, the method for producing a plating composition may include removing a portion of the water from a plating wastewater recovered from a plating tank or a water-rinsing tank through a concentration step, and then removing at least a portion of the surfactant through a surfactant removal step, thereby obtaining a first plating composition.

[0014] Furthermore, the concentration step may include a first concentration step in which a part of the water is removed from the plating waste liquid through a reverse osmosis membrane to obtain a first concentrated solution, and a second concentration step in which a part of the water is removed from the first concentrated solution under an inert gas atmosphere or a low-pressure environment to obtain a second concentrated solution.

[0015] 1st step In the first step, first metal ions contained in the first plating composition are reduced using a working electrode of an electrochemical device as the cathode to obtain an elemental metal resulting from the reduction of the first metal ions. The elemental metal may be deposited on the working electrode, for example, to form a metal-adhered working electrode. The first step may be performed using an electrochemical device comprising a working electrode chamber containing a working electrode and a counter electrode chamber containing a counter electrode, the working electrode chamber and the counter electrode chamber being separated by a diaphragm. The diaphragm may be one selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane. The first plating composition 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 allows for more efficient reduction of the first metal ions.

[0016] The first plating composition may be, for example, a plating waste solution used in metal plating, or a plating waste solution obtained by rinsing a metal-plated article with water.

[0017] 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 produced by oxidation of the second metal ion constituting the plating composition prior to use. Examples of the first metal ion include tin(IV) ions, Cu(II) ions, and Fe(III) ions.

[0018] 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 first plating composition may also contain a complexing agent, and the content thereof 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 complexing agent in the first plating composition may be, for example, 0.2 mol / L or more and 2.5 mol / L or less. The content of the first metal ion in the first 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.

[0019] 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 to permeate the first metal ions, such as a reverse osmosis membrane (RO membrane) or a nanofiltration membrane (NF membrane, loose RO membrane), may be used.

[0020] 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 conductive ions. The conductive ions may be derived from a water-soluble metal salt or a water-soluble acidic compound (acid component). Examples of conductive ions include cations such as hydrogen ions, alkali metal ions, and alkaline earth metal ions; and anions such as sulfate ions, nitrate ions, phosphate ions, halogen ions, alkanesulfonate ions, alkanolsulfonate ions, aromatic sulfonate ions, alkylcarboxylate ions, and arylcarboxylate ions.

[0021] In the first step, a portion of the first metal ions in the first plating composition introduced into the working electrode chamber are reduced to elemental metals by a first electrolysis treatment using the first working electrode as the cathode. The elemental metals produced by the reduction may, for example, deposit and adhere to the first working electrode. The current density in the electrolysis treatment of the first metal ions may be selected appropriately depending on the type of first metal ions. The current density is, for example, 0.05 A / dm 2 More than 10A / dm 2 may be less than or equal to 0.1 A / dm 2 or more, or 5A / dm 2 The temperature in the electrolysis treatment may be, for example, 20° C. or higher and 80° C. or lower, and preferably 35° C. or higher or 75° C. or lower. The time required for the electrolysis treatment may be, for example, 10 minutes or longer and 200 hours or shorter.

[0022] 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, such as gluconic acid (including gluconolactone), citric acid, glutaric acid, succinic acid, malic acid, tartaric acid, lactic acid, acetic acid, malonic acid, and salts or derivatives thereof; phosphoric acids, such as tripolyphosphoric acid and hydroxyethanediphosphonic acid, and salts thereof; sugars, such as sorbitol, mannitol, and salts thereof; amino acids, such as phenylalanine, glutamic acid, aspartic acid, alanine, glycine, and salts thereof; HEDTA, EDTA, and the like. The complexing agent may contain at least one selected from the group consisting of these, and may contain at least gluconic acid. Complexing agents may be used alone or in combination of two or more. By forming a complex ion from the first metal ion, it becomes possible to set the pH of the plating composition used for plating to a weakly acidic to weakly alkaline range, thereby suppressing corrosion of the object to be plated that is sensitive to strong acids or strong alkalis (for example, ceramic capacitors and other objects that use oxides as components).

[0023] The first plating composition may contain, in addition to the first metal ion, a second metal ion having a lower oxidation number than 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. A specific example of the second metal ion is an Fe(II) ion when the first metal ion is an Fe(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 for the first metal ion. When the first plating composition contains the 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 first plating composition is measured in the same manner as for the first metal ion.

[0024] The total content of the first metal ions and the second metal ions in the first plating composition may be, for example, 0.1 g / L or more and 100 g / L or less, preferably 1 g / L or more, 5 g / L or more, or 10 g / L or more, and preferably 70 g / L or less, or 50 g / L or less.

[0025] The second metal ions may be derived from the plating composition prior to use. The second metal ions constituting the plating composition prior to 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 sulfonic acid in the alkane sulfonate include alkanesulfonic acids having 1 to 3 carbon atoms, such as methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and 2-propanesulfonic acid.

[0026] The first plating composition may further contain alkali metal ions, alkaline earth metal ions, ammonium ions, etc., derived from the plating composition prior to use. The inclusion of a conductive agent such as alkali metal ions, alkaline earth metal ions, or ammonium ions increases 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. Examples of alkaline earth metal ions include calcium ions, strontium ions, and barium ions. The alkali metal ions, alkaline earth metal ions, ammonium ions, etc. may be added to the plating composition prior to use as salts with an acid component, for example. The inclusion of an acid component in the plating composition prior to use, for example, further improves the stability of the plating composition. The acid component may also be included in the plating composition as a conductive agent. Examples of acid components include sulfuric acid, hydrochloric acid, alkanesulfonic acid, alkanolsulfonic acid, aromatic sulfonic acid, phosphoric acid, alkylcarboxylic acid, and arylcarboxylic acid, and at least one selected from the group consisting of these may be included. These acids may be used alone or in combination of two or more.

[0027] The pH of the first plating composition may be, for example, 0 or more and 14 or less, preferably 0.5 or more, 3 or more, or 4 or more, and preferably 11 or less, 9 or less, or 7 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.

[0028] The first plating composition may further contain an antioxidant derived from the plating composition prior to use. The inclusion of an antioxidant can, for example, improve the stability of the plating composition prior to use and extend the plating 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.

[0029] If the first plating composition includes an antioxidant, the first step may include removing at least a portion of the antioxidant, which may be accomplished by treatment with activated carbon.

[0030] The first plating composition contains water as a solvent. The total concentration of solutes in the first plating composition may be, for example, 750 g / L or less, preferably 400 g / L or less, or 300 g / L or less. The total concentration of solutes in the first plating composition may be, for example, 50 g / L or more.

[0031] The first plating composition may contain a surfactant derived from the plating composition prior to use. The surfactant 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.

[0032] Nonionic surfactants include, for example, 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 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.

[0033] 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 an ether group, an ester group, or an amide group, 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, and benzethonium chloride. The cationic surfactants may have fluorine atoms substituted in their structures.

[0034] 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, alkylylamidopropyldimethylglycine, 2-alkyl-1-(2-hydroxyethyl)imidazolium-1-acetate, alkyldiaminoethylglycine, dialkyldiaminoethylglycine, and alkyldimethylamine oxide.

[0035] Examples of the anionic surfactant include carboxylates, sulfonates, sulfates, and phosphates.

[0036] 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 can be measured using surface tension as an index. Specifically, it can be measured using a drop counter, a surface tensiometer, or the like.

[0037] If the first plating composition contains a surfactant, a surfactant removal step of removing at least a portion of the surfactant from the first plating composition may be carried out prior to the first step. This allows the reduction of the first metal ions to be carried out more efficiently. The surfactant content in the first plating composition after removal in the surfactant removal step may be, for example, 0.01 g / L or less.

[0038] Examples of methods for removing the surfactant in the surfactant removal step include activated carbon treatment and gel filtration treatment. The surfactant removal method may preferably include activated carbon treatment. The surfactant removal method using activated carbon treatment may include, for example, contacting the first plating composition with activated carbon. By using activated carbon, at least a portion of the surfactant can be more efficiently removed from the first plating composition. In the surfactant removal step, a method of electrostatically adsorbing the surfactant (e.g., contacting the surfactant with an ion exchange resin) may be combined with activated carbon treatment.

[0039] 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.

[0040] The specific surface area of ​​activated carbon is, for example, 200m 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 a pretreatment of heat treatment at 200°C for 6 hours. 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.

[0041] 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 surfactant 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 surfactant. The amount of activated carbon used may also be selected depending on the method of contact with the first plating composition. For example, when contacting with the first plating composition in a single pass, a larger amount of activated carbon may be required than when contacting with the first plating composition by circulating the first plating composition.

[0042] 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.

[0043] In one embodiment, the method for producing a plating composition may further include a concentration step in which a portion of the water is removed from the plating waste liquid to obtain a first plating composition. By performing the first step using the concentrated first plating composition, the first metal ions can be removed more efficiently. The plating waste liquid subjected to the concentration step may be one from which at least a portion of the surfactant has been removed in the surfactant removal step, or may be a plating waste liquid from which the surfactant has not been removed. Preferably, the plating waste liquid may be one from which at least a portion of the surfactant has been removed. From the viewpoint of concentration efficiency, the concentration step may include a first concentration step in which a portion of the water is removed through a reverse osmosis membrane (hereinafter also referred to as an RO membrane) to obtain a first concentrated liquid, and a second concentration step in which a portion of the water is removed from the first concentrated liquid under an inert gas atmosphere or a low-pressure environment to obtain a second concentrated liquid.

[0044] In the first concentration step, a first concentrated solution is obtained by removing a portion of the water from a plating wastewater containing first metal ions and water through a reverse osmosis membrane (hereinafter also referred to as an RO membrane). Generally, when concentrating a plating wastewater 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 reverse osmosis membrane to concentrate the plating wastewater, it is possible to concentrate the plating wastewater quickly and in large quantities while suppressing the oxidation of the metal ions.

[0045] A reverse osmosis membrane is a type of filtration membrane that allows water molecules to pass through but blocks substances other than water molecules, such as ions. A reverse osmosis membrane separates a solution A with a high salt concentration (e.g., a first plating composition) from a solution B with a low salt concentration (e.g., water). When a pressure greater than the difference in osmotic pressure between solutions A and B is applied to the side of solution A with a high salt concentration, only water molecules move from solution A to solution B. This allows a portion of the water to be removed from the plating wastewater to obtain a first concentrated solution, and water can also be obtained as reverse osmosis membrane-treated water.

[0046] Examples of materials for the reverse osmosis membrane include polyamide, polysulfone, cellulose acetate, etc., and preferably include polyamides including aromatic polyamides or crosslinked aromatic polyamides. For concentrating the plating wastewater using a reverse osmosis membrane, for example, a tubular module or a spiral module equipped with a reverse osmosis membrane can be used.

[0047] The liquid feed pressure when concentrating plating wastewater using a reverse osmosis membrane may be appropriately selected depending on the type of reverse osmosis membrane used. The liquid feed pressure during concentration may be, for example, 0.5 MPa or more, preferably 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.

[0048] The ratio (concentration factor) of the volume of the plating waste solution to the volume of the first concentrated solution from which part of the water has been removed via the reverse osmosis membrane may be, for example, 2 or more, and preferably 3 or more.

[0049] In the second concentration step, a portion of the water is removed from the first concentrated liquid under an inert gas atmosphere or a low-pressure environment to obtain a second concentrated liquid. By removing a portion of the water from the first concentrated liquid under an inert gas atmosphere or a low-pressure environment, it is possible to obtain a second concentrated liquid from which a portion of the water has been further removed while effectively suppressing oxidation of metal ions contained in the first concentrated liquid.

[0050] Examples of the inert gas in the inert gas atmosphere in the second concentration step 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, or 95% 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 replaced with an inert gas before being reduced in pressure, or an inert gas atmosphere may be created by supplying an inert gas when adjusting the degree of vacuum.

[0051] The low-pressure environment in the second concentration step may be an environment under reduced pressure 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.

[0052] In one embodiment, the second concentration step may be a step of removing a portion of water from the first concentrated solution in a low-oxygen environment to obtain the second concentrated solution. The low-oxygen environment may have an oxygen concentration of, for example, 2% by volume or less, preferably 1% by volume or less, or 0.5% by volume or less.

[0053] 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 reduced pressure and at least a portion of the generated mist is removed.

[0054] 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 can also be, for example, 1 hPa or more, or 100 hPa or more. In the first concentration method, a portion of the water can be removed while heating the first concentrated liquid under reduced pressure. When the first concentrated liquid is heated, the temperature can be, for example, 30°C or more and 80°C or less, preferably 35°C or more or 40°C or more, and preferably 70°C or less or 60°C or less. In the first concentration method, the first concentrated liquid can also 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, by replacing the atmosphere in the container with an inert gas before reducing the pressure, part of the water can be removed under an inert gas atmosphere.

[0055] 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 first concentrated liquid can be frozen by lowering the liquid temperature to, for example, −15°C or lower, preferably −25°C or lower. The atmosphere inside the container is preferably purged with an inert gas before 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. The second concentration method allows water to be removed at a low temperature under a highly reduced pressure, thereby more effectively suppressing the oxidation of metal ions. In the second concentration method, the atmosphere inside the container can be purged with an inert gas before depressurizing, thereby removing a portion of the water under an inert gas atmosphere.

[0056] 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, in which ultrasonic vibrations are applied to the first concentrated liquid. Ultrasonic atomization is a phenomenon in which, when ultrasonic vibrations are applied to a liquid, a fountain-like liquid column is generated on the liquid surface, and fine droplets (mist), mainly measuring several microns, are generated from the sides of the liquid column. By atomizing a liquid without heating it using ultrasonic atomization, substances can be separated at the molecular cluster level. Separation of substances by ultrasonic atomization is possible, for example, by utilizing the fact that molecules of the same substance tend to cluster in a 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.).

[0057] 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. A classification device such as a cyclone is used to separate the generated mist, with the "light mist" consisting of water clusters rising and the "heavy mist" containing components other than water falling. The light mist, water, is condensed by cooling or other means to liquefy and be 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 a 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.

[0058] 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.

[0059] 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 second 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 third step within the above range, the first metal ions can be reduced more efficiently in the first step.

[0060] The reduction treatment solution obtained in the first step may contain a metal complex containing a first metal ion and a complexing agent, the complexing agent, and water. The reduction treatment solution may further contain a second metal ion in addition to the first metal ion. The total content of the first metal ion and the second metal ion in the reduction treatment solution may be, for example, 1 g / L or more and 20 g / L or less, and preferably 2 g / L or more or 10 g / L or less. The content of the complexing agent in the reduction treatment solution may be, for example, 0.2 mol / L or more and 2.5 mol / L or less, and preferably 0.5 mol / L or more or 1.0 mol / L or less.

[0061] The reduction treatment solution may further contain a conductive agent, such as an acid component, and cations derived from the first plating composition, such as alkali metal ions, alkaline earth metal ions, and ammonium ions. Details of the cations and acid components are as described above. The content of the specific cations in the reduction treatment solution, including at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions, may be, for example, 0.2 mol / L to 2.5 mol / L, and preferably 0.5 mol / L to 1.5 mol / L. The content of the acid component in the reduction treatment solution may be, for example, 0.2 mol / L to 2.5 mol / L, and preferably 0.5 mol / L to 1.5 mol / L.

[0062] 2nd process In the second step, a nanofilter with a molecular weight of 300 Da to 800 Da is used to separate the reduction treatment solution obtained in the first step into a permeate that passes through the nanofilter and a concentrate that does not pass through the nanofilter. The concentrate contains components that do not pass through the nanofilter and at least a metal complex containing a first metal ion and a complexing agent. The permeate contains components that pass through the nanofilter and at least a complexing agent derived from the metal complex. This may be because, for example, the metal complex contained in the reduction treatment solution cannot pass through the nanofilter due to its relatively large molecular weight, while the complexing agent can pass through the nanofilter. By separating the metal complex contained in the reduction treatment solution as a concentrate using the nanofilter, the content of the metal complex contained in the second plating composition produced can be reduced, thereby maintaining high plating quality when used as a plating treatment solution.

[0063] The molecular weight cutoff of a nanofilter is an index that represents the separation characteristics of the nanofilter and is also called the nominal molecular weight cutoff. It is generally expressed as the molecular weight at which the permeation rejection rate is 90% or 95%. The molecular weight cutoff is measured using a standard substance with a known molecular weight, such as insulin, polyethylene glycol, or dextran. The molecular weight cutoff of the nanofilter used in the second step may preferably be 300 Da or more, or 500 Da or more, and may preferably be 800 Da or less, or 700 Da or less. The numerical value listed in the nanofilter's specifications can be applied to the molecular weight cutoff of the nanofilter.

[0064] Examples of materials for the nanofilter include polyamide, polysulfone, polyethersulfone, cellulose acetate, and polyvinylidene fluoride, and preferably include polyamides including aromatic polyamides and crosslinked aromatic polyamides. For separation of the reduction treatment liquid using a nanofilter, for example, a tubular module or a spiral module equipped with a nanofilter can be used.

[0065] The filtration method using the nanofilter in the second step may be either a dead-end method or a cross-flow method. The cross-flow method is preferable. The dead-end method is a method in which the entire amount of the feed liquid is filtered, while the cross-flow method is a method in which the feed liquid is filtered while flowing parallel to the membrane surface. Filtration using the cross-flow method can suppress deposition of the target substance (e.g., metal complex) on the membrane surface due to shear flow of the feed liquid near the membrane surface, allowing for steady filtration.

[0066] The liquid feed pressure when filtering the reduction-treated liquid using a nanofilter may be appropriately selected depending on the type of nanofilter used, etc. The liquid feed pressure during filtration may be, for example, 0.5 MPa or more, preferably 1 MPa or more, or 2 MPa or more. The liquid feed pressure may be, for example, 10 MPa or less. The temperature during filtration may be, for example, 0°C or more and 50°C or less, preferably 10°C or more and 40°C or less.

[0067] The reduction treatment liquid to be filtered using a nanofilter may have the same concentration as that obtained in the first step, or may be appropriately diluted before filtration. When the reduction treatment liquid obtained in the first step is diluted, the dilution ratio may be, for example, 20 times or less, and preferably 10 times or less, 5 times or less, 3 times or less, or 2 times or less. In one embodiment, the reduction treatment liquid may be filtered at the concentration obtained in the first step. When filtration is performed using a nanofilter having a specific molecular weight cutoff, the liquid can be efficiently separated into a permeate and a concentrate even without dilution, and the recovery efficiency of the complexing agent and the like in the permeate is excellent.

[0068] Filtration through a nanofilter in the second step may be performed only once or multiple times. When filtration through a nanofilter is performed multiple times, the permeate may be filtered multiple times using one nanofilter, or may be filtered in multiple stages using multiple nanofilters. The number of filtrations may be, for example, 1 to 100, and preferably 10 or less. Filtration multiple times allows the metal complex to be removed more effectively.

[0069] In the permeate obtained by filtering the reduction-treated solution through a nanofilter, at least a portion of the metal complex has been removed from the reduction-treated solution. The ratio of the content of the metal complex contained in the permeate to the content of the metal complex contained in the reduction-treated solution may be, for example, 0.05 or less, preferably 0.03 or less. That is, the removal rate of the metal complex contained in the reduction-treated solution by the nanofilter may be, for example, 95% or more, preferably 97% or more. Here, the content of the metal complex in the reduction-treated solution and the permeate can be measured by redox titration or inductively coupled plasma atomic emission spectroscopy (ICP-AES).

[0070] The permeated liquid contains at least a complexing agent derived from the reduction treatment liquid. The ratio of the content of the complexing agent contained in the permeated liquid to the content of the complexing agent contained in the reduction treatment liquid may be, for example, 0.75 or more, preferably 0.8 or more, or 0.9 or more. That is, the transmittance of the complexing agent contained in the reduction treatment liquid by the nanofilter may be, for example, 75% or more, preferably 80% or more, or 90% or more. Note that the content of the complexing agent in the reduction treatment liquid and the permeated liquid refers to the content of free complexing agent that has not formed a metal complex. Here, the content of the complexing agent in the reduction treatment liquid and the permeated liquid can be measured by titration.

[0071] In addition to the complexing agent, the permeate may further contain cations such as alkali metal ions, alkaline earth metal ions, and ammonium ions, and conductive agents such as acid components. When the permeate contains specific cations including at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions, the ratio of the content of the specific cations in the permeate to the content of the specific cations in the reduction treatment solution may be, for example, 0.75 or more, preferably 0.8 or more, or 0.9 or more. That is, the transmittance of the specific cations in the reduction treatment solution through the nanofilter may be, for example, 75% or more, preferably 80% or more, or 90% or more. When the permeate contains an acid component, the ratio of the content of the acid component in the permeate to the content of the acid component in the reduction treatment solution may be, for example, 0.75 or more, preferably 0.8 or more, or 0.9 or more. That is, the transmittance of the acid component contained in the reduction-treated solution through the nanofilter may be, for example, 75% or more, preferably 80% or more, or 90% or more. Here, the content of specific cations in the reduction-treated solution and the permeated solution can be measured by inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the content of acid components can be measured by capillary electrophoresis (CE).

[0072] 3rd process In the third step, the permeated solution is introduced into a working electrode chamber equipped with a working electrode having a metal attached thereto, and in the permeated solution, the working electrode having the metal attached thereto is used as an anode to oxidize at least a portion of the attached metal to second metal ions having a lower oxidation number than the first metal ions, thereby obtaining a second plating composition containing the second metal ions and a complexing agent.

[0073] At least a portion of the metal complex is removed, and the metal attached to the working electrode is oxidized to second metal ions using a permeate containing a complexing agent to prepare a second plating composition, thereby achieving excellent plating quality when used in a plating process.

[0074] The oxidation of the metal attached to the working electrode to the second metal ion is carried out by electrolysis in the permeate introduced into the working electrode chamber, with the working electrode to which the metal is attached serving as the anode. The current density in the electrolysis of the metal may be selected appropriately depending on the type of metal. The current density is, for example, 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.

[0075] The method for producing a plating composition may further include a step of adding a surfactant to the second plating composition obtained in the third step. Plating using a plating composition containing a surfactant results in a plating having a better surface. The surfactant added may be the same type as the surfactant removed in the surfactant removal step described above. The amount of surfactant added may be approximately the same as the amount of surfactant removed in the surfactant removal step.

[0076] The method for producing a plating composition may further include a fourth step of reducing at least the first metal ions contained in the concentrated solution obtained in the second step to a metal using the working electrode as a cathode. By including the fourth step, the recovery rate of the metal from the first plating composition can be further improved.

[0077] In the fourth step, an electrochemical device may be used, which includes a working electrode chamber with a working electrode and a counter electrode chamber with a counter electrode, the working electrode chamber and the counter electrode chamber being separated by a diaphragm. The concentrated solution is introduced into the working electrode chamber, and electrolysis is performed using the working electrode as the cathode. The details of the electrochemical device are the same as those of the electrochemical device in the first step. In addition to reducing the first metal ions, the fourth step may further include reducing the second metal ions contained in the concentrated solution to metal by electrolysis using the working electrode as the cathode. This can further improve the metal recovery rate.

[0078] The current density in the electrolysis treatment in the fourth step may be appropriately selected depending on the types of the first metal ions and the second metal ions. The current density is, for example, 0.05 A / dm 2 More than 10A / dm 2 may be less than or equal to 0.1 A / dm 2 or more, or 5A / dm 2 The temperature in the 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 the electrolysis may be, for example, 10 minutes or longer and 200 hours or shorter. In the electrolysis treatment in the fourth step, it is expected that the reduction of the first metal ion will proceed more easily than in the electrolysis treatment in the first step.

[0079] In the fourth step, for example, a metal may be deposited on the working electrode. The metal deposited on the working electrode can be reused in the third step by oxidizing it to a second metal ion in the permeate using the working electrode as the anode.

[0080] The method for producing a plating composition may further include a fifth step of adjusting the pH of the concentrate obtained in the second step to obtain a precipitate containing at least the first metal ion. The fifth step may further include obtaining a precipitate of the second metal ion contained in the concentrate by adjusting the pH. The inclusion of the fifth step can further improve the recovery rate of the metal from the first plating composition.

[0081] The pH of the concentrate can be adjusted by mixing an acidic or alkaline compound with the concentrate. Examples of acidic compounds include inorganic acids such as sulfuric acid, hydrochloric acid, and nitric acid, and organic acids such as aliphatic or aromatic sulfonic acids, aliphatic or aromatic carboxylic acids, and aliphatic or aromatic sulfamic acids. Examples of alkaline compounds include hydroxides of alkali metals, alkaline earth metals, and the like, and amines. In the fifth step, the pH of the concentrate may be adjusted, for example, to between 1 and 3, or between 9 and 11.

[0082] The precipitate obtained in the fifth step includes hydroxides, oxides, etc. The precipitate obtained in the fifth step can be reused, for example, as a refining raw material.

[0083] 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.

[0084] Plating Method The plating method includes a plating composition production step and a plating step of contacting a substrate 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 substrate. 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 substrate.

[0085] 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 regenerated plating composition obtained in the regeneration process. The plating solution may be composed of, for example, tin(II) ions, a surfactant, a complexing agent, etc. In addition to the regenerated plating composition, the plating solution may further contain, as needed, the surfactant, etc. removed in the regeneration process.

[0086] 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.

[0087] 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.

[0088] In the plating step, a known plating method can be applied, such as barrel plating, centrifugal plating, rack plating, or the like.

[0089] Manufacturing method of electronic components The method for producing an electronic component includes a plating composition production step and an electrode formation 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 production step, to form an electrode layer containing a plating layer on the surface of the conductive layer. The plating composition production step is the same as in the method for producing a plating composition described above. By using a plating solution containing a recycled plating composition obtained by the method for producing a plating composition described above, it is possible to form external electrodes containing electrode layers of excellent quality equivalent to those obtained by using a plating solution prepared just before use, and it is possible to produce highly reliable electronic components.

[0090] For details of electronic components manufactured by the method for manufacturing electronic components, reference can be made to, for example, Patent Publication No. 2021-027195, International Publication No. 2023 / 171394, and International Publication No. 2020 / 218218 (the disclosures of these documents are incorporated herein by reference in their entirety).

[0091] 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, surfactants and the like removed in the production step.

[0092] 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.

[0093] 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.

[0094] In the electrode formation step, a known plating method can be applied, such as barrel plating, centrifugal plating, rack plating, or the like.

[0095] An example of steps included in a method for manufacturing an electronic component will be described with reference to the drawings. FIG. 3 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 using 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 using pumping 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 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.

[0096] In the plating composition manufacturing apparatus 30, at least a portion of the surfactant is removed from the tin-containing wash water using a surfactant removal means 32 that uses activated carbon. A first concentrator 36 using a reverse osmosis 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 an inert gas atmosphere or a low-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 that includes 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, a portion of the tin(IV) ions in the wash water is reduced to metallic tin in the first working electrode chamber 34a using the working electrode as the cathode. This results in a working electrode with metallic tin attached to its surface and a reduced-treatment solution from which some of the tin(IV) ions have been removed. If the second concentrated solution contains tin(II) ions, at least a portion of the tin(II) ions in the second concentrated solution may be reduced to metallic tin using the working electrode as the cathode. The reduced-treatment solution is filtered through a membrane separation means 35 equipped with a nanofilter having a specific molecular weight cutoff to separate it into a permeate containing a complexing agent and a concentrated solution containing a metal complex. The permeate obtained from the separation means 35 is then introduced into the second working electrode chamber 34b. In the second working electrode chamber 34b, at least a portion of the reduced metallic tin is oxidized to tin(II) ions by electrolysis using the working electrode with metallic tin attached as the anode, producing a second plating composition 38 that can be reused in plating processes. The produced second plating composition 36 is reused by adding additives such as surfactants as needed and introducing the resulting second plating composition 36 into the tin plating tank 10. According to one aspect of the present embodiment, tin-containing wash water that would conventionally be discarded can be reused as a regenerated plating composition, thereby contributing to a reduction in waste.

[0097] The invention according to the present disclosure may include, for example, the following aspects. [1] A method for producing a plating composition, comprising: a first plating composition containing a metal complex containing a first metal ion and a complexing agent, and the complexing agent, in a working electrode chamber equipped with a working electrode, reducing a portion of the first metal ions contained in the first plating composition to metal using the working electrode as a cathode to obtain a reduced-treatment solution and a working electrode having the metal attached thereto; permeating the reduced-treatment solution through a nanofilter having a molecular weight cutoff of 300 Da to 800 Da to separate the reduced-treatment solution into a permeated solution containing the complexing agent and a concentrated solution that does not permeate the nanofilter and contains the metal complex; introducing the permeated solution into a working electrode chamber equipped with the working electrode having the metal attached thereto, and oxidizing at least a portion of the attached metal in the permeated solution to second metal ions having a lower oxidation number than the first metal ions using the working electrode having the metal attached as an anode to obtain a second plating composition containing the second metal ions and the complexing agent.

[0098] [2] The method according to [1], wherein the ratio of the content of the metal complex in the permeated liquid to the content of the metal complex in the reduction treatment liquid is 0.05 or less.

[0099] [3] The method according to [1] or [2], wherein the ratio of the content of the complexing agent in the permeated liquid to the content of the complexing agent in the reduction treatment liquid is 0.75 or more.

[0100] [4] The method according to any one of [1] to [3], wherein the first metal ion is a tetravalent tin ion and the second metal ion is a divalent tin ion.

[0101] [5] The manufacturing method according to [4], wherein the first plating composition has a total tin ion content of 5 g / L or more and 70 g / L or less, and a complexing agent content of 0.2 mol / L or more and 2.5 mol / L or less.

[0102] [6] The manufacturing method according to [4] or [5], wherein the reduction treatment solution has a total tin ion content of 1 g / L or more and 10 g / L or less, and a complexing agent content of 0.2 mol / L or more and 2.5 mol / L or less.

[0103] [7] The manufacturing method according to any one of [1] to [6], wherein the first plating composition further contains a specific cation including at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions, and an acid component.

[0104] [8] The manufacturing method according to [7], wherein the reduction treatment solution has a content of the specific cation of 0.2 mol / L or more and 2.5 mol / L or less, and a content of the acid component of 0.2 mol / L or more and 2.5 mol / L or less.

[0105] [9] The manufacturing method according to [7] or [8], wherein the ratio of the content of specific cations in the permeated liquid to the content of specific cations in the reduction treatment liquid is 0.75 or more, and the ratio of the content of acid components in the permeated liquid to the content of acid components in the reduction treatment liquid is 0.75 or more.

[0106]

[10] The method according to any one of [1] to [9], further comprising removing at least a portion of a surfactant from a plating waste solution derived from a plating solution used in a plating process to obtain the first plating composition.

[0107]

[11] The method according to any one of [1] to

[10] , further comprising removing at least a portion of water from a plating waste solution derived from a plating solution used in a plating treatment to obtain the first plating composition.

[0108]

[12] The manufacturing method according to any one of [1] to

[11] , further comprising reducing at least the first metal ions contained in the concentrated solution to a metal using a working electrode as a cathode.

[0109]

[13] The method according to any one of [1] to

[11] , further comprising adjusting the pH of the concentrated solution to obtain a precipitate containing at least the first metal ion. [Example]

[0110] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0111] Preparation of Plating Composition A plating composition having the following composition was prepared using purified water, sodium stannate (IV) as a tin (IV) ion source, gluconic acid, and sodium methanesulfonate.

[0112] composition Tin(IV) ion: 0.02 mol / L Complexing agent: gluconic acid: 0.8 mol / L Conductive agent: methanesulfonic acid: 1.2 mol / L Cation: Sodium ion: 1.4 mol / L

[0113] Example 1 The plating composition prepared above was diluted 10-fold with purified water and filtered through a nanofilter with a molecular weight cutoff of 600 Da to 800 Da to obtain a permeate. The content of each component in the permeate was quantified, and the transmittance relative to the content of each component in the diluted solution before filtration was calculated. The results are shown in Table 1. The content of each component was quantified using inductively coupled plasma atomic emission spectroscopy (ICP-AES), redox titration, or capillary electrophoresis (CE).

[0114] Comparative Examples 1 to 3 The permeates were obtained in the same manner as in Example 1, except that nanofilters with a molecular weight cutoff of 150 Da to 300 Da, 200 Da, or 1000 Da were used, and the transmittance of each component in each permeate was calculated. The results are shown in Table 1.

[0115] [Table 1]

[0116] In plating compositions, tin(IV) ions are thought to form metal complexes with complexing agents. More than 60% of the metal complexes passed through nanofilters with a molecular weight cutoff of 1000 Da, but the pass rate was less than 10% through nanofilters with molecular weight cutoffs of 600 Da to 800 Da.

[0117] Examples 2 and 3 The plating composition prepared above was diluted three times with purified water and filtered through a nanofilter with a molecular weight cutoff of 600 Da to 800 Da or 300 Da to 500 Da to obtain a permeate. The content of each component in the permeate was quantified, and the transmittance relative to the content of each component in the diluted solution before filtration was calculated. The results are shown in Table 2.

[0118] Comparative Example 4 The permeates were obtained in the same manner as in Example 2, except that a nanofilter with a molecular weight cutoff of 150 Da to 300 Da was used, and the transmittance of each component in each permeate was calculated. The results are shown in Table 2.

[0119] [Table 2]

[0120] Example 4 The plating composition stock solution prepared above was filtered through a nanofilter with a molecular weight cutoff of 600 Da to 800 Da to obtain a permeate. The content of each component in the permeate was quantified, and the transmittance relative to the content of each component in the diluted solution before filtration was calculated. The results are shown in Table 3, along with the results of Examples 1 and 2.

[0121] [Table 3]

[0122] Examples 5 and 6 The plating composition stock solution prepared above, or a solution diluted three times with purified water, was filtered through a nanofilter with a molecular weight cutoff of 300 Da to 500 Da to obtain a permeate. The content of each component in the permeate was quantified, and the transmittance relative to the content of each component in the diluted solution before filtration was calculated. The results are shown in Table 4.

[0123] [Table 4]

[0124] Tables 3 and 4 show that the transmittance of each component is higher when the prepared plating composition is not diluted.

[0125] Example 7 A first plating composition having the composition shown below was prepared using purified water, sodium stannate (IV) as a tin (IV) ion source, tin (II) methanesulfonate as a tin (II) ion source, gluconic acid, and sodium methanesulfonate.

[0126] Tin(IV) ion: 0.16 mol / L Tin(II) ion: 0.04 mol / L Gluconic acid: 0.8 mol / L Methanesulfonic acid: 1.2 mol / L Sodium ion: 1.4 mol / L

[0127] 2 L of the first plating composition prepared above was introduced into the working electrode chamber of the electrochemical device. The electrochemical device was equipped with a platinum-coated titanium electrode as the working electrode and a platinum-coated titanium electrode as the counter electrode, and the working electrode chamber and the counter electrode chamber were separated by a cation exchange membrane (Noafion (TM)424) The electrolysis equipment was placed in a counter electrode chamber with a 10 g / L aqueous solution of sodium sulfate, and the working electrode was set as the cathode. The temperature of the solution was between 40 and 70°C, and the current was 0.1 A / dm 2 from 0.5A / dm 2 The electrolysis treatment was carried out for 1 hour at a current density of 36.1 A. The reduced solution was removed from the working electrode chamber and, without dilution, filtered through a nanofilter with a molecular weight cutoff of 600 Da to 800 Da to obtain a permeate. The permeate separated by the nanofilter was then introduced into the working electrode chamber of the electrochemical device, and the working electrode was used as the anode, and the solution was filtered at a temperature of 20 to 70 °C and a current density of 1 A / dm. 2 from 80A / dm 2 The electrolysis treatment was carried out at a current density of 1000 kJ / min and a current value of 34.3 A for 0.5 hours to obtain a recycled plating composition as a treated second plating composition.

[0128] The regenerated plating composition exhibits good quality in the plating process. [Explanation of symbols]

[0129] 10 Tin plating bath 20 Wash tank 30 Plating composition manufacturing equipment

Claims

1. a first plating composition containing a metal complex containing first metal ions and a complexing agent, and the complexing agent, and in a working electrode chamber equipped with a working electrode, reducing a portion of the first metal ions contained in the first plating composition to a metal using the working electrode as a cathode, thereby obtaining a reduction treatment solution and a working electrode to which the metal is attached; permeating the reduction treatment liquid through a nanofilter having a molecular weight cutoff of 300 Da or more and 800 Da or less, and separating the reduction treatment liquid into a permeate containing the complexing agent and a concentrate which does not permeate the nanofilter and contains the metal complex; introducing the permeated solution into a working electrode chamber equipped with a working electrode having the metal attached thereto, and oxidizing, in the permeated solution, the working electrode having the metal attached thereto as an anode, at least a portion of the attached metal to second metal ions having a lower oxidation number than the first metal ions, thereby obtaining a second plating composition comprising the second metal ions and the complexing agent.

2. 2. The method according to claim 1, wherein the ratio of the content of the metal complex in the permeated liquid to the content of the metal complex in the reduction treatment liquid is 0.05 or less.

3. 2. The method according to claim 1, wherein the ratio of the content of the complexing agent in the permeated liquid to the content of the complexing agent in the reduction treatment liquid is 0.75 or more.

4. 2. The method according to claim 1, wherein the first metal ion is a tetravalent tin ion and the second metal ion is a divalent tin ion.

5. 5. The manufacturing method according to claim 4, wherein the first plating composition has a total tin ion content of 5 g / L or more and 70 g / L or less, and a complexing agent content of 0.2 mol / L or more and 2.5 mol / L or less.

6. 5. The manufacturing method according to claim 4, wherein the reduction treatment solution has a total tin ion content of 1 g / L or more and 10 g / L or less, and a complexing agent content of 0.2 mol / L or more and 2.5 mol / L or less.

7. 2. The manufacturing method according to claim 1, wherein the first plating composition further contains a specific cation including at least one selected from the group consisting of alkali metal ions, alkaline earth metal ions, and ammonium ions, and an acid component.

8. The manufacturing method according to claim 7, wherein the reduction treatment solution has a content of the specific cation of 0.2 mol / L or more and 2.5 mol / L or less, and a content of the acid component of 0.2 mol / L or more and 2.5 mol / L or less.

9. The manufacturing method described in claim 7, wherein the ratio of the content of specific cations in the permeated liquid to the content of specific cations in the reduction treatment liquid is 0.75 or more, and the ratio of the content of acid components in the permeated liquid to the content of acid components in the reduction treatment liquid is 0.75 or more.

10. The method according to claim 1 , further comprising obtaining the first plating composition by removing at least a portion of a surfactant from a plating waste solution derived from a plating solution used in a plating process.

11. The method according to claim 1 , further comprising removing at least a portion of water from a plating waste solution derived from a plating solution used in a plating process to obtain the first plating composition.

12. The method according to claim 1 , further comprising reducing at least the first metal ions contained in the concentrated solution to a metal using a working electrode as a cathode.

13. The method according to claim 1 , further comprising adjusting the pH of the concentrated solution to obtain a precipitate containing at least the first metal ion.

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