Method and device for regenerating plating composition

Abstract

Provided is a method for regenerating a plating composition, capable of efficiently reducing metal ions in a higher oxidation state in the plating composition to metal ions in a low oxidation state. This method for regenerating a plating composition involves: removing, from a plating composition including tin(IV) ions and a surfactant, at least part of the surfactant; introducing the plating composition from which at least part of the surfactant has been removed into a work electrode chamber, wherein the work electrode chamber includes a work electrode and is separated from a counter electrode chamber including a counter electrode by one type of membrane selected from the group consisting of an ion-exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane; reducing at least part of the tin(IV) ions in the introduced plating composition to metal tin using the work electrode as a cathode; and oxidizing at least part of the reduced metal tin to tin(II) ions using the work electrode as an anode.

Description

Plating composition regeneration method and regeneration device

[0001] The present invention relates to a method and apparatus for regenerating a plating composition.

[0002] In relation to plating compositions used in metal plating, JP 2004-534151 A proposes a method for regenerating a plating solution in which electrolytically deposited tin is used to reduce tin(IV) ions to tin(II) ions. JP 2015-518923 A 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.

[0003] One aspect of the present invention aims to provide a method for regenerating a plating composition that can efficiently reduce metal ions in a high oxidation state in the plating composition to metal ions in a low oxidation state.

[0004] A first aspect is a method for regenerating a plating composition, the method comprising: removing at least a portion of the surfactant from a plating composition containing tin(IV) ions and the surfactant; introducing the plating composition from which at least a portion of the surfactant has been removed into a counter electrode chamber having a counter electrode and a working electrode chamber separated by a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, the counter electrode chamber having a working electrode; reducing at least a portion of the tin(IV) ions in the introduced plating composition to metallic tin using the working electrode as a cathode; and oxidizing at least a portion of the reduced metallic tin to tin(II) ions using the working electrode as an anode.

[0005] A second aspect is an apparatus for regenerating a plating composition, the apparatus comprising: a surfactant removal means; a working electrode chamber having a working electrode; a counter electrode chamber having a counter electrode; and one type of membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, which separates the working electrode chamber from the counter electrode chamber.

[0006] According to one aspect of the present invention, a method for regenerating a plating composition can be provided that can efficiently reduce metal ions in a high oxidation state in a plating composition to metal ions in a low oxidation state.

[0007] 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 components present in the composition, unless otherwise specified, if the composition contains multiple substances corresponding to each component. 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 a plating composition recycling method and recycling apparatus for embodying the technical concept of the present invention, and the present invention is not limited to the plating composition recycling method and recycling apparatus described below.

[0008] 2. Method for Regenerating Plating Composition The method for regenerating a plating composition includes a first step of removing at least a portion of the surfactant from a plating composition containing tin(IV) ions and a surfactant; a second step of introducing the plating composition from which at least a portion of the surfactant has been removed into a counter electrode chamber having a counter electrode and a working electrode chamber having a working electrode, the counter electrode chamber being separated by a 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 tin(IV) ions in the introduced plating composition to metallic tin using the working electrode as the cathode; and a third step of oxidizing at least a portion of the reduced metallic tin to tin(II) ions using the working electrode as the anode.

[0009] By removing at least a portion of the surfactant from the plating composition and then electrochemically reducing the tin(IV) ions using an electrochemical device including a counter electrode chamber and a working electrode chamber separated by a membrane that is difficult for tin ions to permeate, such as an ion exchange membrane, it is possible to efficiently reduce the tin(IV) ions to metallic tin. This can be explained, for example, as follows: By removing at least a portion of the surfactant contained in the plating composition, inhibition of the reduction of the tin(IV) ions due to the interaction between the surfactant and the cathode is suppressed, and the efficiency of the reduction of the tin(IV) ions at the cathode is thought to be improved.

[0010] In the first step, at least a portion of the surfactant is removed from a plating composition containing tin(IV) ions and a surfactant. The plating composition may be an electrolytic plating solution or an electroless plating solution. The plating composition may preferably be an electrolytic plating solution or an electrolytic tin plating solution, and more preferably a used electrolytic tin plating solution. The plating composition may be a liquid medium in which at least tin(IV) ions and a surfactant are dissolved. The liquid medium constituting the plating composition may contain at least water, and may further contain a water-soluble organic solvent or the like in addition to water, as necessary.

[0011] The surfactant contained in the 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 tin (IV) ions, the surfactant may include at least one selected from the group consisting of a nonionic surfactant, a cationic surfactant, and an amphoteric surfactant. The plating composition may contain only one surfactant, or a combination of two or more surfactants.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] Examples of the anionic surfactant include carboxylates, sulfonates, sulfates, and phosphates.

[0016] The surfactant content in the plating composition may be, for example, 0.01 g / L or more and 10 g / L or less, preferably 0.1 g / L or more or 5 g / L or less. The surfactant content in the plating composition after removal in the first 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.

[0017] The tin(IV) ions contained in the plating composition may be derived from, for example, a water-soluble tin(IV) salt or may be produced by oxidation of tin(II) ions contained in the plating composition prior to use. The tin(IV) ions contained in the plating composition may be simple metal ions or complex ions. 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 their salts or derivatives; phosphoric acids, including tripolyphosphate, hydroxyethanediphosphonic acid, and their salts; sugars, including sorbitol, mannitol, and their salts; amino acids, including phenylalanine, glutamic acid, aspartic acid, alanine, glycine, and their salts; 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. The complexing agents may be used alone or in combination of two or more. Since the tin (IV) ion is a complex ion, the pH of the plating composition can be set to a weakly acidic to weakly alkaline range, thereby suppressing corrosion of objects to be plated that are susceptible to strong acids or strong alkalis (e.g., objects that use oxides as components, such as ceramic capacitors).

[0018] The content of tin(IV) ions in the 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 tin ions, and preferably 10 times the molar amount. The content of tin(IV) ions 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.

[0019] The plating composition may contain tin(II) ions in addition to tin(IV) ions. The tin(II) ions may be simple metal ions or complex ions. The complexing agent that forms the complex ions is the same as that for tin(IV) ions. When the plating composition contains tin(II) ions, the content of tin(II) ions in the plating composition may be, for example, 100 g / L or less, preferably 20 g / L or less. The content of tin(II) ions in the plating composition is measured in the same manner as for tin(IV) ions.

[0020] The source of the tin(II) ion may be any water-soluble tin(II) salt. Specific examples of water-soluble tin(II) salts include stannous sulfate, stannous chloride, tin fluoroborate, tin(II) alkanesulfonate, tin(II) alkanolsulfonate, and tin(II) aromatic sulfonate. The water-soluble tin(II) salt may contain at least one selected from the group consisting of these, and may contain at least tin(II) alkanesulfonate. Examples of the alkane sulfonic acid in the tin(II) alkanesulfonate include alkanesulfonic acids having 1 to 3 carbon atoms, and specific examples include methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and 2-propanesulfonic acid.

[0021] The plating composition may further contain, in addition to tin ions, other metal ions other than tin, such as salts of lead ions, copper ions, silver ions, bismuth ions, cobalt ions, and nickel ions.

[0022] The 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 throwing power. 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 plating composition as salts with an acid component, for example. The inclusion of an acid component in the plating composition improves, for example, the stability of the 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, and the plating composition may contain at least one selected from the group consisting of these. These acids may be used alone or in combination of two or more.

[0023] The pH of the 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 plating composition is within the above range, tin (IV) ions tend to be reduced more efficiently. The pH of the plating composition may be adjusted to a desired range, for example, with a pH adjuster. Examples of the pH adjuster include alkali metal hydroxides, ammonia, and the like in addition to the acid components described above.

[0024] The plating composition may further contain an antioxidant. The inclusion of an antioxidant can, for example, improve the stability of the plating composition and extend the bath life. Examples of antioxidants include hydroquinone, ascorbic acid, catechol, hypophosphorous acid, and erythorbic acid. When the plating composition contains an antioxidant, the content of the antioxidant in the 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.

[0025] If the 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.

[0026] Examples of the method for removing the surfactant in the first step include activated carbon treatment and gel filtration treatment. The method for removing the surfactant in the first step may preferably include activated carbon treatment. The method for removing the surfactant by activated carbon treatment may include, for example, contacting the plating composition with activated carbon. By using activated carbon, at least a portion of the surfactant can be more efficiently removed from the plating composition. In the first step, a method for electrostatically adsorbing the surfactant (e.g., contacting the plating composition with an ion exchange resin) may be combined with activated carbon treatment.

[0027] 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.

[0028] 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.

[0029] The amount of activated carbon used for contact with the 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 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 be selected depending on the method of contact with the 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 plating composition.

[0030] The plating composition may be contacted with the activated carbon by, for example, mixing the 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 plating composition and the activated carbon may be, for example, 0°C or higher or 70°C or lower.

[0031] In the second step, a plating composition from which at least a portion of the surfactant has been removed is introduced into the working electrode chamber of an electrochemical device having a working electrode chamber and a counter electrode chamber having a counter electrode, the working electrode chamber and the counter electrode chamber being separated by a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, and at least a portion of the tin (IV) ions in the introduced plating composition are reduced to metallic tin using the working electrode as the cathode. An aqueous solution containing conductive ions may be placed in the counter electrode chamber of the electrochemical device. By placing the aqueous solution containing conductive ions in the counter electrode chamber, the tin (IV) ions can be reduced more efficiently.

[0032] Examples of materials for the working electrode provided in the working electrode chamber include gold, platinum, platinum-coated titanium, silver, nickel, graphite, tin, titanium, and iridium oxide. Examples of materials for the counter electrode include platinum, platinum-coated titanium, gold, nickel, iridium oxide, titanium, graphite, and palladium. The working electrode chamber and the counter electrode chamber are separated by an ion exchange membrane. This allows for more efficient reduction of tin(IV) ions. 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. From the perspective of tin(IV) ion reduction efficiency, the ion exchange membrane may include at least a cation exchange membrane. 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 tin ions to pass through, such as a reverse osmosis membrane (RO membrane) or a nanofiltration membrane (NF membrane, loose RO membrane), may be used.

[0033] 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.

[0034] In the second step, at least a portion of the tin (IV) ions in the plating composition introduced into the working electrode chamber is reduced to metallic tin by a first electrolysis treatment using the working electrode as a cathode. The metallic tin produced by the reduction may be deposited on the working electrode, for example. The current density in the electrolysis of tin (IV) ions is, for example, 0.05 A / dm ２ 1A / dm or more ２ may be less than or equal to 0.1 A / dm ２ or more, or 0.5A / dm ２The temperature during electrolysis may be, for example, 30° C. or higher and 80° C. or lower, and preferably 35° 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.

[0035] In the third step, at least a portion of the tin metal produced by reduction in the second step is oxidized to tin(II) ions by a second electrolysis treatment using the working electrode as the anode. In the third step, the tin metal deposited on the working electrode in the second step may be oxidized to tin(II) ions by electrolysis using the working electrode as the anode. That is, the third step may be performed using the same electrochemical device subsequent to the reduction of tin(IV) ions in the second step.

[0036] The current density in the electrolysis of metal tin is, for example, 0.5 A / dm ２ More than 100A / dm ２ The temperature in the electrolysis of metallic tin 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 the electrolysis may be, for example, 0.2 hours or higher and 10 hours or lower.

[0037] The method for regenerating a plating composition may further include a step of adding a surfactant to the plating composition after the third step. By using a plating composition to which a surfactant has been added, a plating having a better surface is formed. The surfactant added may be the same type as the surfactant removed in the first step. Furthermore, the amount of surfactant added may be approximately the same as the amount removed in the first step.

[0038] 1. Plating composition regeneration device The plating composition regeneration device comprises a surfactant removal means, a working electrode chamber having a working electrode, a counter electrode chamber having a counter electrode, and one membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane that separates the working electrode chamber from the counter electrode chamber. The plating composition regeneration device can be used in the plating composition regeneration method described above.

[0039] Examples of surfactant removal means provided in the regeneration device include activated carbon treatment and gel filtration treatment. The surfactant removal means may preferably include activated carbon treatment. Removal of surfactants by activated carbon treatment may include, for example, contacting the plating composition with activated carbon. By using activated carbon, surfactants can be more efficiently removed from the plating composition. Contacting the plating composition with activated carbon may be achieved, for example, by passing the plating composition through activated carbon held in a cartridge or the like. That is, the regeneration device may include a cartridge filled with activated carbon and configured to allow the plating composition to pass through.

[0040] The regeneration device may include an electrochemical device configured to perform electrolysis, the electrochemical device including a working electrode chamber, a counter electrode chamber, and a membrane separating the working electrode chamber from the counter electrode chamber, the membrane being selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane. The regeneration device may further include a power supply unit, a control unit, a temperature control unit, etc. that enable the electrolysis.

[0041] The present invention may include the following aspects: <1> A method for regenerating a plating composition, comprising: removing at least a portion of the surfactant from a plating composition containing tin (IV) ions and the surfactant; introducing the plating composition from which at least a portion of the surfactant has been removed into a working electrode chamber separated from a counter electrode by a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, the working electrode chamber being separated from the counter electrode by a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane; reducing at least a portion of the tin (IV) ions in the introduced plating composition to metallic tin using the working electrode as a cathode; and oxidizing at least a portion of the reduced metallic tin to tin (II) ions using the working electrode as an anode.

[0042] <2> The regeneration method according to <1>, wherein at least a portion of the tin(IV) ions form a tin(IV) gluconate complex.

[0043] <3> The regeneration method according to <1> or <2>, wherein the ion exchange membrane is a cation exchange membrane.

[0044] <4> The regeneration method according to any one of <1> to <3>, wherein the pH of the working electrode chamber is 1 or more and 13 or less.

[0045] <5> The regeneration method according to any one of <1> to <4>, wherein the counter electrode chamber contains an aqueous solution containing conductive ions.

[0046] <6> The regeneration method according to any one of <1> to <5>, wherein removing at least a portion of the surfactant from the plating composition includes contacting the plating composition with activated carbon.

[0047] <7> The regeneration method according to any one of <1> to <6>, wherein the surfactant includes at least one selected from the group consisting of nonionic surfactants and cationic surfactants.

[0048] <8> The regeneration method according to any one of <1> to <7>, wherein the plating composition contains an antioxidant.

[0049] <9> A plating composition regeneration device comprising: a surfactant removal means; a working electrode chamber having a working electrode; a counter electrode chamber having a counter electrode; and one type of membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, which separates the working electrode chamber from the counter electrode chamber.

[0050] <10> Use of a plating composition regeneration device in the plating composition regeneration method according to any one of <1> to <8>, wherein the plating composition regeneration device comprises a surfactant removal means, a working electrode chamber including a working electrode, a counter electrode chamber including a counter electrode, and one type of membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, which separates the working electrode chamber from the counter electrode chamber.

[0051] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0052] Reference Example 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.

[0053] 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

[0054] Example 1 Two liters of the plating composition prepared above was passed through an activated carbon cartridge (MX, manufactured by Kankyo Technos Co., Ltd.) attached to a filter at room temperature (25°C) and introduced into the working electrode chamber of an electrochemical device. The electrochemical device had 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） The electrolysis device 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 to 0.5 A / dm ２ Then, the working electrode was used as the anode, and the solution temperature was set to 20°C to 70°C, and the current density was set to 36.1 A, and the solution was electrolyzed for 1 hour at a current density of 1 A / dm ２ to 80 A / 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, thereby obtaining a recycled plating composition as the plating composition after the treatment.

[0055] The concentrations of tin(IV) ions and tin(II) ions in the regenerated plating compositions were evaluated using a combination of redox titration and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Specifically, the redox titration was performed using 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 from the total concentration.

[0056] As a result, the concentration of tin(IV) ions in the regenerated plating composition was 0.04 mol / L, and the concentration of tin(II) ions was 0.16 mol / L. From these results, the reduction efficiency of tin(IV) ions was evaluated to be 95%. The reduction efficiency was calculated by dividing the integrated current value in the third step by half the integrated current value in the second step.

[0057] The activated carbon contained in the activated carbon cartridge (MX) has a specific surface area of ​​437 m2 as measured by the BET method. ２ The average pore size was 2.4 nm. The mesopore shape was measured by the INNES method, and the average pore width on the adsorption side was 6.0 nm, and the average pore width on the desorption side was 2.1 nm.

[0058] Similar results were obtained when the activated carbon cartridge was changed to YCC-R manufactured by Nippon Filter Co., Ltd.

[0059] The activated carbon contained in the activated carbon cartridge (YCC-R) has a specific surface area of ​​1237 m2 as measured by the BET method. ２ The average pore size was 1.8 nm. The mesopore shape was measured by the INNES method, and the average pore width on the adsorption side was 2.5 nm and the average pore width on the desorption side was 4.0 nm.

[0060] Comparative Example 1 Electrolysis treatment was carried out twice in the same manner as in Example 1, except that the plating composition was introduced directly into the working electrode chamber without passing through an activated carbon cartridge, to obtain a treated plating composition.

[0061] The concentrations of tin(IV) ions and tin(II) ions in the resulting plating composition after treatment were evaluated in the same manner, and the concentrations of tin(IV) ions were found to be 0.19 mol / L and 0.01 mol / L, respectively. From these results, the reduction efficiency of tin(IV) ions was evaluated to be 0%.

[0062] Comparative Example 2 Electrolysis treatment was carried out twice in the same manner as in Example 1, except that an electrolyzer in which the working electrode chamber and the counter electrode chamber were not separated by a cation exchange membrane and were in a state in which liquids could pass through each other was used, and a plating composition after treatment was obtained.

[0063] The concentrations of tin(IV) ions and tin(II) ions in the resulting plating composition after treatment were evaluated in the same manner, and the concentration of tin(IV) ions was found to be 0.20 mol / L and the concentration of tin(II) ions was found to be 0.0 mol / L. From these results, the reduction efficiency of tin(IV) ions was evaluated to be 0%.

[0064] The disclosure of Japanese Patent Application No. 2022-189216 (filing date: November 28, 2022) is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described 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. removing at least a portion of the surfactant from a plating composition comprising tin (IV) ions and the surfactant; introducing a plating composition from which at least a part of the surfactant has been removed into a counter electrode chamber having a counter electrode and a working electrode chamber having a working electrode, the counter electrode chamber being separated by one type of membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, and reducing at least a part of the tin (IV) ions in the introduced plating composition to metallic tin using the working electrode as a cathode; and oxidizing at least a portion of the reduced tin metal to tin (II) ions using the working electrode as the anode.

2. 2. The method of claim 1, wherein at least a portion of the tin(IV) ions form a tin(IV) gluconate complex.

3. 2. The regeneration method according to claim 1, wherein the ion exchange membrane is a cation exchange membrane.

4. 2. The method according to claim 1, wherein the pH of the working electrode chamber is 1 or more and 13 or less.

5. The regeneration method according to claim 1 , wherein an aqueous solution containing conductive ions is placed in the counter electrode chamber.

6. 2. The method of claim 1, wherein removing at least a portion of the surfactant from the plating composition comprises contacting the plating composition with activated carbon.

7. 2. The regeneration method according to claim 1, wherein the surfactant comprises at least one selected from the group consisting of nonionic surfactants, cationic surfactants, and amphoteric surfactants.

8. The regenerating method of claim 1 , wherein the plating composition includes an antioxidant.