Plating method and method for manufacturing electronic components

Abstract

Provided are: a plating method which uses a plating composition that is recycled by efficiently reducing metal ions in a high oxidation state to metal ions in a low oxidation state; and a method for manufacturing an electronic component. The method for manufacturing an electronic component comprises: removing at least a part of a surfactant from a plating composition containing tin(IV) ions and the surfactant; introducing the plating composition, from which at least a part of the surfactant has been removed, into a working electrode chamber which is provided with a working electrode, and is isolated from a counter electrode chamber provided with a counter electrode by means of one membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, and reducing at least a part of the tin(IV) ions in the introduced plating composition to metallic tin by using the working electrode as a cathode; obtaining a recycled plating composition by oxidizing at least part of the metallic tin obtained through reduction to tin(II) ions by using the working electrode as an anode; and forming a second electrode layer including a tin plating layer on a first electrode layer by bringing a plating solution containing at least part of the recycled plating composition into contact with an element body which has the first electrode layer on the surface thereof.

Description

[Technical Field]

[0001] This invention relates to a plating method and a method for manufacturing electronic components. [Background technology]

[0002] In relation to plating compositions used in metal plating, Japanese Patent Publication No. 2004-534151 proposes a method for regenerating a plating solution by reducing tin(IV) ions to tin(II) ions using electrolytically produced tin. Furthermore, Japanese Patent Publication No. 2015-518923 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. [Overview of the Initiative] [Problems that the invention aims to solve]

[0003] One aspect of the present invention aims to provide a plating method and a method for manufacturing electronic components that use a plating composition regenerated by efficiently reducing highly oxidized metal ions to a low-oxidized metal ion state. [Means for solving the problem]

[0004] The first embodiment is a method for manufacturing an electronic component, comprising: removing at least a portion of the surfactant from a plating composition containing tin(IV) ions and a surfactant; introducing the plating composition from which at least a portion of the surfactant has been removed into a working electrode chamber, which is isolated by a counter electrode chamber equipped with a counter electrode and a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane and a nanofiltration membrane, and is equipped with a working electrode; reducing at least a portion of the tin(IV) ions in the introduced plating composition to metallic tin with the working electrode as the cathode; oxidizing at least a portion of the reduced metallic tin to tin(II) ions with the working electrode as the anode to obtain a regenerated plating composition; and contacting a plating solution containing at least a portion of the regenerated plating composition with a substrate having a first electrode layer on its surface, thereby forming a second electrode layer including a tin plating layer on the first electrode layer.

[0005] The second embodiment is a plating method comprising: removing at least a portion of the surfactant from a plating composition containing tin(IV) ions and a surfactant; introducing the plating composition from which at least a portion of the surfactant has been removed into a working electrode chamber, which is isolated by a counter electrode chamber equipped with a counter electrode and a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane and a nanofiltration membrane, and is equipped with a working electrode; reducing at least a portion of the tin(IV) ions in the introduced plating composition to metallic tin with the working electrode as the cathode; oxidizing at least a portion of the reduced metallic tin to tin(II) ions with the working electrode as the anode to obtain a regenerated plating composition; and contacting a plating solution containing at least a portion of the regenerated plating composition with an object to be plated to form a tin plating layer on the surface of the object to be plated. [Effects of the Invention]

[0006] According to one aspect of the present invention, it is possible to provide a plating method and a method for manufacturing electronic components that use a plating composition regenerated by efficiently reducing highly oxidized metal ions to a low-oxidized metal ion state. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic cross-sectional view of a multilayer ceramic capacitor, an example of an electronic component. [Figure 2] This is a flowchart showing the process sequence for manufacturing electronic components. [Figure 3] This is a schematic diagram illustrating an example of a conventional manufacturing process for electronic components. [Figure 4] This is a schematic diagram illustrating an example of the manufacturing process for the electronic component according to this embodiment. [Figure 5] This is a schematic diagram illustrating an example of the manufacturing process for the electronic component according to this embodiment. [Figure 6A] This is a schematic diagram illustrating the second step in the regeneration process of the plating composition. [Figure 6B] This is a schematic diagram illustrating the second step in the regeneration process of the plating composition. [Figure 6C] This is a schematic diagram illustrating the third step in the regeneration process of a plating composition. [Figure 6D] This is a schematic diagram illustrating the third step in the regeneration process of a plating composition. [Modes for carrying out the invention]

[0008] In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved. Furthermore, the content of each component in a composition refers to the total amount of multiple substances present in the composition, unless otherwise specified, if multiple substances corresponding to each component exist in the composition. In addition, 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. Embodiments of the present invention will now be described in detail. However, the embodiments shown below are illustrative examples of plating methods and methods for manufacturing electronic components to embody the technical concept of the present invention, and the present invention is not limited to the plating methods and methods for manufacturing electronic components shown below.

[0009] Plating method The plating method includes a regeneration step of a plating composition, a plating solution containing at least a part of the regenerated plating composition obtained in the regeneration step, and a plating step of bringing the plating solution into contact with a plating object to form a tin plating layer on the surface of the plating object. By using a plating solution containing the regenerated plating composition obtained in the regeneration step of the plating composition described later, a tin plating layer of excellent quality equivalent to that when using a plating solution prepared at the time of use can be formed on the plating object.

[0010] In the plating step, the plating solution is brought into contact with the plating object to form a tin plating layer on the surface of the plating object. The plating step may be electrolytic plating or electroless plating, and preferably may be electrolytic plating. The plating solution may be a commonly used tin plating solution except that it contains at least a part of the regenerated plating composition obtained in the regeneration step. The plating solution may be composed of, for example, tin (II) ions, a surfactant, a complexing agent, etc. The plating solution may further contain, as necessary, a surfactant or the like removed in the regeneration step in addition to the regenerated plating composition.

[0011] The plating object to which the plating method is applied is not particularly limited as long as it is an article on which a tin plating layer can be formed on the surface. Examples of the plating object include a ceramic body having a conductive layer on the surface, a composite body containing a resin and metal magnetic powder, a substrate, an electrode provided on a base material, etc.

[0012] The tin plating layer formed in the plating step may further contain gold, silver, etc. in addition to tin. The tin plating layer may further contain other trace substances, for example, trace elements that may be unavoidably mixed in. The thickness of the tin plating layer is not particularly limited and may be appropriately selected according to the purpose or the like. The thickness of the tin plating layer may be, for example, 0.01 μm or more and 100 μm or less, preferably 0.1 μm or more and 50 μm or less, more preferably 0.3 μm or more and 10 μm or less, for example 0.3 μm or more and 3 μm or less or 1 μm or more and 5 μm or less.

[0013] For the plating process, known plating methods can be applied, such as barrel plating, centrifugal plating, rack plating, etc.

[0014] Method for manufacturing an electronic component The method for manufacturing an electronic component includes a regeneration step of a plating composition, a plating solution containing at least a part of the regenerated plating composition obtained in the regeneration step, and a substrate having a first electrode layer on its surface, and an electrode formation step of forming a second electrode layer including a tin plating layer on the surface of the first electrode layer. By using a plating solution containing the regenerated plating composition obtained in the regeneration step of the plating composition described later, an external electrode including a second electrode layer of excellent quality equivalent to that when using a plating solution prepared at the time of use can be formed, and a highly reliable electronic component can be manufactured.

[0015] For details of the electronic component manufactured by the method for manufacturing an electronic component, reference can be made to the descriptions in, for example, Japanese Patent Application Laid-Open No. 2021-027195, International Publication No. 2023 / 171394, International Publication No. 2020 / 218218 (the disclosures of these documents are incorporated herein by reference in their entirety), etc.

[0016] In the electrode formation step, a plating solution and a substrate having a first electrode layer on its surface are brought into contact to form a second electrode layer including a tin plating layer on the surface of the first electrode layer. The plating method in the electrode formation step may be electrolytic plating or electroless plating, and preferably may be electrolytic plating. The plating solution may be a commonly used tin plating solution except that it contains at least a part of the regenerated plating composition obtained in the regeneration step. The plating solution may be composed of, for example, containing tin (II) ions, a surfactant, a complexing agent, etc. The plating solution may further contain, as necessary, a surfactant etc. removed in the regeneration step in addition to the regenerated plating composition.

[0017] The substrate used in the electrode formation process may be the component body of an electronic component. The component body is not particularly limited and may be, for example, a multilayer ceramic capacitor, an indicator, a resistor, an LC composite component, a thermistor, etc. In one embodiment, the component body may be a multilayer ceramic capacitor. The component body may be constructed using methods that are normally used depending on its type. The material of the component body is not particularly limited and may be a material that is normally used depending on the type of component body. Examples of materials include ceramics, resins, metals, and composites thereof. In one embodiment, the material of the component body may be ceramic.

[0018] The first electrode layer, which is placed on the surface of the base body, may consist of at least one pair of electrodes. The first electrode layer may include, for example, a base layer formed on the surface of the base body and an intermediate layer containing nickel (Ni) placed on the base layer. The base layer may be, but is not limited to, a layer of Cu, Ag, Ni, or Pd or an alloy thereof. The base layer may also contain other trace substances, such as trace atoms that may inevitably be mixed in. The base layer is provided on the surface of the component body, preferably in contact with the component body. The thickness of the base layer is not particularly limited, and may be, for example, 1 μm to 500 μm, preferably 3 μm to 300 μm, more preferably 5 μm to 100 μm, for example, 5 μm to 50 μm or 10 μm to 30 μm. The method for forming the base layer is not particularly limited, and may include, for example, plating (e.g., electroplating or electroless plating), sputtering, applying Cu paste and curing or baking it.

[0019] The intermediate layer may be a conductive layer containing nickel (Ni). In addition to Ni, the intermediate layer may further contain Pd, Sn, Ag, Cu, Co, Ti, Ba, Mn, Ca, Sr, Na, K, Mg, Al, Fe, etc. The thickness of the intermediate layer is not particularly limited, and 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. The method for forming the intermediate layer is not particularly limited and may include, for example, plating (e.g., electroplating or electroless plating), sputtering, etc.

[0020] The tin plating layer in the second electrode layer formed in the electrode formation process may further contain gold, silver, etc., in addition to tin. The tin plating layer may also further contain other trace substances, such as trace elements that may inevitably be mixed in. The thickness of the second electrode layer is not particularly limited and may be appropriately selected depending on the purpose. The thickness of the second electrode layer may be, for example, 0.01 μm or more and 100 μm or less, preferably 0.1 μm or more and 50 μm or less, more preferably 0.3 μm or more and 10 μm or less, for example, 0.3 μm or more and 3 μm or less or 1 μm or more and 5 μm or less.

[0021] Known plating methods can be applied to the electrode formation process, including barrel plating, centrifugal plating, rack plating, and the like.

[0022] An example of an electronic component manufactured by the electronic component manufacturing method will be described with reference to the drawings. Figure 1 is a schematic cross-sectional view of a multilayer ceramic capacitor, which is an example of an electronic component. The multilayer ceramic capacitor 1a has a component body 2 and external electrodes 3a and 3b provided on the surface of the component body. The component body 2 has internal electrodes 5a and 5b and a dielectric portion (dielectric layer) 6. The external electrodes 3a and 3b each consist of a first electrode layer consisting of a base layer 11a and 11b and an intermediate layer 12a and 12b, and a second electrode layer 13a and 13b including a tin plating layer.

[0023] An example of a manufacturing process for electronic components will be explained with reference to Figure 2, which is a flowchart illustrating the process sequence. A method for manufacturing electronic components may include: an input step (S101) in which a base body having a base layer on its surface is introduced into a nickel plating tank; a nickel plating step (S102) in which an intermediate layer containing nickel is formed on the base layer of the base body introduced into the nickel plating tank by electroplating; a water washing step (S103) in which the base body with the intermediate layer formed is pumped out of the nickel plating tank into a water washing tank and washed in the water washing tank; a tin plating step (S104) in which the washed base body is pumped out into a tin plating tank and a second electrode layer containing tin is formed in the tin plating tank by electroplating; a water washing step (S105) in which the base body with the second electrode layer formed is pumped out of the tin plating tank into a water washing tank and washed in the water washing tank; an extraction step (S106) in which the base body with the external electrode formed is extracted from the water washing tank; a drying step (S107) in which the extracted base body is dried; and a separation step (S108) in which the dried base body is separated. In the method for manufacturing electronic components, the plating solution in the tin plating tank used in the tin plating process contains a regenerated tin plating composition obtained in the regeneration process.

[0024] An example of a manufacturing process for electronic components will be explained using a schematic diagram. Figure 3 is a schematic diagram showing the process of a conventional manufacturing method for electronic components. In the conventional manufacturing method, a substrate having a base layer on its surface is placed in a nickel plating tank (Ni plating tank), and an intermediate layer containing nickel is formed on the base layer of the substrate placed in the nickel plating tank. The substrate with the intermediate layer formed on it is pumped out of the nickel plating tank to a first washing tank. For example, a counter-flow multi-stage washing tank is used as the first washing tank. The substrate is pumped out to the downstream side of the counter-flow multi-stage washing tank and moves upstream. Water is supplied from the upstream side to the counter-flow multi-stage washing tank, and the washing water moves downstream. Washing water is collected from the downstream washing tank and put into the nickel plating tank to replenish the moisture that evaporates from the nickel plating tank. The substrate removed from the counter-flow multi-stage washing tank is placed in a tin plating tank (Sn plating tank), where a second electrode layer containing a tin plating layer is formed on the intermediate layer. Using a pump, the electronic components with the second electrode layer formed are removed from the tin plating tank to the second washing tank. For example, a counter-flow multi-stage washing tank is used as the second washing tank. The electronic components are pumped to the downstream end of the counter-flow multi-stage washing tank, move upstream, and are separated from the counter-flow multi-stage washing tank in the upstream end. The separated electronic components are then dried. The washing water containing tin is removed from the downstream end of the counter-flow multi-stage washing tank as tin wastewater and discarded.

[0025] Figure 4 is a schematic diagram showing the process of a method for manufacturing an electronic component, which is one aspect of this embodiment. In the schematic diagram of the process shown in Figure 4, the rinse water (plating composition) taken out from the downstreammost tank of the countercurrent multi-stage rinse tank, which is the second rinse tank, is introduced into a regeneration device for the plating composition, which differs from the conventional schematic diagram of the process shown in Figure 3. In the regeneration device, at least a portion of the surfactant is removed from the rinse water containing tin using activated carbon. The rinse water from which at least a portion of the surfactant has been removed is introduced into an electrochemical apparatus equipped with a working electrode chamber and a counter electrode chamber separated by a membrane. The rinse water may contain tin(IV) ions, and may also contain tin(II) ions. In the electrochemical apparatus, at least a portion of the tin(IV) ions in the rinse water is reduced to metallic tin with the working electrode as the cathode. Furthermore, if the rinse water contains tin(II) ions, at least a portion of the tin(II) ions in the rinse water may be reduced to metallic tin with the working electrode as the cathode. Next, at least a portion of the reduced metallic tin is oxidized to tin(II) ions with the working electrode as the anode, thereby obtaining a regenerated plating composition. The obtained regenerated plating composition is introduced into a tin plating tank. In one aspect of this embodiment, tin-containing rinse water, which would conventionally be discarded, can be reused as a regenerated plating composition, contributing to the reduction of waste.

[0026] Figure 5 is a schematic diagram showing the process of a method for manufacturing an electronic component, which is one embodiment of this product. In the schematic diagram of the process shown in Figure 5, the rinse water from which at least a portion of the surfactant has been removed is concentrated by a concentration device before being introduced into the electrochemical device, which is a difference from the schematic diagram of the process shown in Figure 4. In the concentration device, at least a portion of the water is removed from the rinse water from which at least a portion of the surfactant has been removed. By introducing the rinse water, from which at least a portion of the water has been removed and whose tin ion concentration has increased, into the electrochemical device, a more efficiently regenerated plating composition can be obtained. Furthermore, the water removed in the concentration device is introduced into the uppermost tank of a countercurrent multi-stage rinsing tank and reused as rinse water.

[0027] Regeneration process of plating composition The regeneration process for the plating composition includes: a first step of removing at least a portion of the surfactant from the plating composition containing tin(IV) ions and the surfactant; a second step of introducing the plating composition from which at least a portion of the surfactant has been removed into a working electrode chamber, which is isolated by a counter electrode chamber equipped with a counter electrode and a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane and a nanofiltration membrane, and equipped with a working electrode, and reducing at least a portion of the tin(IV) ions in the introduced plating composition to metallic tin with 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 with the working electrode as the anode.

[0028] By removing at least a portion of the surfactant from the plating composition, and then electrochemically reducing the tin(IV) ions using an electrochemical apparatus equipped with a counter electrode chamber and a working electrode chamber separated by a membrane that is impermeable to tin ions, such as an ion exchange membrane, the tin(IV) ions can be efficiently reduced to metallic tin. This can be thought of, for example, as follows: By removing at least a portion of the surfactant contained in the plating composition, the inhibition of tin(IV) ion reduction due to the interaction between the surfactant and the cathode is suppressed, and the reduction efficiency of tin(IV) ions at the cathode is thought to be improved.

[0029] In the first step, at least a portion of the surfactant is removed from the plating composition containing tin(IV) ions and the 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 water-soluble organic solvents or the like as needed.

[0030] The surfactant included in the plating composition may be any of the following: nonionic surfactant, cationic surfactant, anionic surfactant, amphoteric surfactant, etc. The surfactant may also 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 nonionic surfactants, cationic surfactants, and amphoteric surfactants. The plating composition may contain only one surfactant, or a combination of two or more.

[0031] Examples of nonionic surfactants include ester-type surfactants formed by ester bonding of polyhydric alcohols such as glycerin, sorbitol, and sucrose with fatty acids; ether-type surfactants formed by adding ethylene oxide, propylene oxide, etc., to compounds having hydroxyl groups such as higher alcohols and alkylphenols; and ester-ether-type surfactants formed by adding ethylene oxide, propylene oxide, etc., to ester-type surfactants. 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, and N-long-chain alkyldimethylamine oxide. Nonionic surfactants may have fluorine atoms substituted in their structures.

[0032] Examples of cationic surfactants include amine salts and quaternary ammonium salts. Specifically, examples of cationic surfactants include alkyl (or alkenyl) trimethylammonium salts, alkyl (or alkenyl) triethylammonium salts, dialkyl (or alkenyl) dimethylammonium salts, alkyl (or alkenyl) quaternary ammonium salts, mono or dialkyl (or alkenyl) quaternary ammonium salts containing an ether group, ester group, or amide group, alkyl (or alkenyl) pyridinium salts, alkyl (or alkenyl) dimethylbenzylammonium 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. Cationic surfactants may have fluorine atoms substituted in their structures.

[0033] Amphoteric surfactants exhibit the properties of anionic surfactants in alkaline regions and cationic surfactants in acidic regions. Examples of amphoteric surfactants include carboxylate salts and sulfonates, and they may be of the amino acid type, betaine type, etc. Specific examples of amphoteric surfactants include alkyldimethylaminoacetic acid betaine, alkyldimethylcarboxybetaine, alkyldimethylcarboxymethyleneammonium betaine, alkyldimethylammonium acetate, fatty acid amidopropyl dimethylamino acid betaine, alkylylamidopropyl dimethylglycine, 2-alkyl-1-(2-hydroxyethyl)imidazolium-1-acetate, alkyldiaminoethylglycine, dialkyldiaminoethylglycine, and alkyldimethylamine oxide.

[0034] Examples of anionic surfactants include carboxylates, sulfonates, sulfates, and phosphates.

[0035] 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 indicator. Specifically, it can be measured using a dropper.

[0036] The tin(IV) ions contained in the plating composition may originate from, for example, a water-soluble tin(IV) salt, or may be generated by the oxidation of tin(II) ions that constitute the plating composition before use. Furthermore, 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, such as gluconic acid (including gluconolactone), citric acid, glutaric acid, succinic acid, malic acid, tartaric acid, lactic acid and their salts or derivatives; phosphoric acids, such as tripolyphosphate, hydroxyethanediphosphonic acid and their salts; sugars, such as sorbitol, mannitol and their salts; amino acids, such as phenylalanine, glutamic acid, aspartic acid, alanine, glycine and their salts; and HEDTA, EDTA, etc. The complexing agent may contain at least one selected from the group consisting of these, and may contain at least gluconic acid. The complexing agent may be used alone or in combination of two or more. Because the tin(IV) ion is a complex ion, it is possible to set the pH of the plating composition from weakly acidic to weakly alkaline, thereby suppressing corrosion of the plated object (for example, ceramic capacitors and other materials that use oxides as components) that are sensitive to strong acids or strong alkalis.

[0037] The tin(IV) ion content in the plating composition may be, for example, 0.1 g / L or more and 100 g / L or less, preferably 1 g / L or more. The complexing agent content in the plating composition may be, for example, equimolar to 20 times the molar amount of the tin ions, preferably 10 times the molar amount or less. The tin(IV) ion content in the plating composition is measured, for example, by inductively coupled plasma atomic emission spectrometry (ICP-AES) or by redox titration with potassium iodate after reduction with iron powder.

[0038] 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 tin(II) ion content in the plating composition may be, for example, 100 g / L or less, and preferably 20 g / L or less. The tin(II) ion content in the plating composition is measured in the same manner as for tin(IV) ions.

[0039] The tin(II) ion can be derived from any water-soluble tin(II) salt. Specific examples of water-soluble tin(II) salts include, for example, stannous sulfate, stannous chloride, stannous borofluoride, tin(II) alkanesulfonic acid, tin(II) alkanolsulfonic acid, and tin(II) aromatic sulfonic acid. The mixture may contain at least one selected from this group, and may contain at least tin(II) alkanesulfonic acid. Examples of alkanesulfonic acids in tin(II) alkanesulfonic acid include alkanesulfonic acids having 1 to 3 carbon atoms, specifically methanesulfonic acid, ethanesulfonic acid, propanesulfonic acid, and 2-propanesulfonic acid.

[0040] The plating composition may further contain other metal ions besides tin in addition to tin ions. Examples of other metal ions include salts of lead ions, copper ions, silver ions, bismuth ions, cobalt ions, nickel ions, etc.

[0041] The plating composition may further contain alkali metal ions, ammonium ions, etc. The inclusion of alkali metal ions, ammonium ions, etc. tends to increase conductivity, suppress heat generation due to liquid resistance during electroplating, and improve uniform electrodeposition. Examples of alkali metal ions include lithium ions, sodium ions, potassium ions, rubidium, cesium, etc. Alkali metal ions, ammonium ions, etc. may be added to the plating composition, for example, as a salt with an acid component. The inclusion of an acid component in the plating composition improves stability, for example. Examples of acid components include sulfuric acid, hydrochloric acid, alkanesulfonic acid, alkanolsulfonic acid, aromatic sulfonic acid, phosphoric acid, alkyl carboxylic acid, aryl carboxylic acid, etc., and may contain at least one selected from this group. These acids may be used individually or in combination of two or more.

[0042] The pH of the plating composition may be, for example, 1 to 13, preferably 3 or higher, or 4 or higher, and preferably 11 or lower, or 9 or lower. 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 adjusting agent. Examples of pH adjusting agents include alkali metal hydroxides, ammonia, etc., in addition to the acid components mentioned above.

[0043] The plating composition may further contain an antioxidant. Including an antioxidant can improve the stability of the plating composition and extend the bath life, for example. Examples of antioxidants include hydroquinone, ascorbic acid, catechol, hypophosphorous acid, and erythorbic acid. When the plating composition contains an antioxidant, the antioxidant content in the plating composition may be, for example, 0.01 g / L or more and 20 g / L or less, preferably 0.1 g / L or more, or 5 g / L or less.

[0044] If the plating composition contains an antioxidant, the first step may include removing at least a portion of the antioxidant. The removal of the antioxidant may be carried out by activated carbon treatment.

[0045] Examples of methods for removing surfactants in the first step include activated carbon treatment and gel filtration treatment. The method for removing surfactants in the first step preferably includes activated carbon treatment. The method for removing surfactants 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 removed from the plating composition more efficiently. In the first step, a method of electrostatically adsorbing the surfactant (for example, contacting it with an ion exchange resin) and the activated carbon treatment may be combined.

[0046] Activated carbon is a porous material whose main component is carbon, and which has been subjected to chemical or physical activation treatment. The activated carbon used in activated carbon treatment may be chemically activated or gas-activated. Furthermore, the activated carbon may be powdered activated carbon, granular activated carbon, or a combination of these.

[0047] The specific surface area of ​​activated carbon is, for example, 200 m². 2 / g or more 1500m 2 It may be less than or equal to / g, preferably 300m 2 / g or more, or 700m 2The amount may be less than or equal to / g. The specific surface area is measured using nitrogen gas after heat treatment at 200°C for 6 hours as a pretreatment, based on the BET (Brunauer Emmett Teller) theory. The average pore size of the activated carbon may be, for example, 1.5 nm to 3.5 nm, preferably 2.0 nm to 3.0 nm. The mesopore shape of the activated carbon may have an average pore width on the adsorption side measured by the INNES method of, for example, 2 nm to 30 nm, preferably 4 nm to 10 nm. The average pore width on the desorption side measured by the INNES method may be, for example, 2 nm to 5 nm, preferably 2 nm to 3.5 nm.

[0048] The amount of activated carbon used in contact with the plating composition may be appropriately selected depending on the type of activated carbon. The amount of activated carbon used should be sufficient to remove at least a portion of the surfactant contained in the plating composition, preferably an amount sufficient to remove 50% or more by mass, 70% or more by mass, or 90% or more by mass of the surfactant. The amount of activated carbon used may also be selected depending on the method of contact with the plating composition. For example, when contact is made in a single pass, the amount of activated carbon required may be greater than when the plating composition is circulated and contacted.

[0049] Contact between the plating composition and activated carbon may be achieved, for example, by mixing the plating composition and activated carbon and then separating the solid and liquid components, or by passing the plating composition through activated carbon held in a filter, cartridge, etc. The contact temperature between the plating composition and activated carbon may be, for example, 0°C or higher, or 70°C or lower.

[0050] 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 apparatus, which comprises a working electrode chamber equipped with a working electrode and a counter electrode chamber equipped with a counter electrode, and the working electrode chamber and the counter electrode chamber are separated by a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane and a nanofiltration membrane. At least a portion of the tin(IV) ions in the introduced plating composition is reduced to metallic tin using the working electrode as the cathode. A conductive ion-containing aqueous solution may be placed in the counter electrode chamber of the electrochemical apparatus. By placing a conductive ion-containing aqueous solution in the counter electrode chamber, the tin(IV) ions can be reduced more efficiently.

[0051] Examples of materials for the working electrode provided in the working electrode chamber include gold, platinum, platinum-clad titanium, silver, nickel, graphite, tin, titanium, and iridium oxide. Examples of materials for the counter electrode include platinum, platinum-clad 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 can be appropriately selected from commercially available ion exchange membranes. From the viewpoint of the reduction efficiency of tin(IV) ions, the ion exchange membrane may include at least a cation exchange membrane. For example, the cation exchange membrane may include a copolymer of fluororesin based on sulfonated tetrafluoroethylene. Alternatively, instead of an ion exchange membrane, a membrane that does not easily pass tin ions, such as a reverse osmosis membrane (RO membrane) or a nanofiltration membrane (NF membrane, loose RO membrane), may be used.

[0052] 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, for example, alkali metal ions, alkaline earth metal ions, etc., as metal ions. The water-soluble metal salt may also contain, for example, sulfate ions, nitrate ions, phosphate ions, etc., as anions.

[0053] In the second step, at least a part of the tin (IV) ions in the plating composition introduced into the working electrode chamber is reduced to metallic tin by subjecting the working electrode as a cathode to a first electrolysis treatment. The metallic tin produced by reduction may, for example, be deposited on the working electrode. The current density in the electrolysis of tin (IV) ions may be, for example, 0.05 A / dm 2 or more and 1 A / dm 2 or less, preferably 0.1 A / dm 2 or more, or 0.5 A / dm 2 or less. The temperature in the electrolysis may be, for example, 30°C or more and 80°C or less, preferably 35°C or more, or 75°C or less. The time required for electrolysis may be, for example, 10 minutes or more and 200 hours or less.

[0054] In the third step, at least a part of the metallic tin produced by reduction in the second step is oxidized to tin (II) ions by subjecting the working electrode as an anode to a second electrolysis treatment. In the third step, the metallic tin deposited on the working electrode in the second step may be electrolyzed with the working electrode as an anode to be oxidized to tin (II) ions. That is, the third step may be carried out using the same electrochemical device following the reduction of tin (IV) ions in the second step.

[0055] The current density in the electrolysis of metallic tin may be, for example, 0.5 A / dm 2 or more and 100 A / dm 2 or less. Also, the temperature in the electrolysis of metallic tin may be, for example, 10°C or more and 80°C or less, preferably 15°C or more, or 75°C or less. The time required for electrolysis may be, for example, 0.2 hours or more and 10 hours or less.

[0056] The regeneration step for the plating composition may further include a step of adding a surfactant to the plating composition after the third step. By using the plating composition to which the surfactant has been added, a plating with a better surface can be formed. The surfactant added may be the same type as the surfactant removed in the first step. Also, the amount of surfactant added may be about the same as the amount removed in the first step.

[0057] The second and third steps in the regeneration process of the plating composition will be explained with reference to the schematic diagrams in Figures 6A to 6D. Figures 6A and 6B schematically show the second step, and Figures 6C and 6D schematically show the third step. Figure 6A is a schematic diagram showing the state in which the plating composition, from which at least a portion of the surfactant has been removed, has been introduced into the working electrode chamber 50 of the electrochemical apparatus 100. The electrochemical apparatus 100 comprises a working electrode chamber 50 equipped with a working electrode 20 and a counter electrode chamber 60 equipped with a counter electrode 30, and the working electrode chamber 50 and the counter electrode chamber 60 are separated by a specific membrane 40 selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane. Electrolyte 70 is also present in the working electrode chamber 50 and the counter electrode chamber 60.

[0058] 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 50, so that tin(IV) ions become present in the working electrode chamber 50, as shown in Figure 6A. As shown in Figure 6A, tin(II) ions may also be present in the working electrode chamber 50. In Figure 6A, by passing a current with the working electrode 20 as the cathode, the tin(IV) ions are reduced at the working electrode 20, and metallic tin is deposited on the working electrode 20, as shown in Figure 6B. If tin(II) ions are present in the working electrode chamber, the tin(II) ions may also be reduced at the working electrode 20, and metallic tin may be deposited on the working electrode 20.

[0059] In the third step, as shown in Figure 6C, metallic tin is deposited on the working electrode 20. In Figure 6C, by passing an electric current through the working electrode 20 as the anode, the metallic tin on the working electrode 20 is partially oxidized, as shown in Figure 6D, and tin(II) ions are released from the working electrode 20 into the working electrode chamber 50.

[0060] Plating composition regeneration device The plating composition regeneration apparatus comprises a surfactant removal means and an electrochemical apparatus comprising a working electrode chamber equipped with a working electrode, a counter electrode chamber equipped with a counter electrode, and a 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 apparatus can be used in the plating composition regeneration method described above.

[0061] Examples of surfactant removal means provided by 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 removed from the plating composition more efficiently. Contact between the plating composition and 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.

[0062] The regeneration apparatus may include an electrochemical apparatus configured to enable electrolysis, comprising a working electrode chamber, a counter electrode chamber, and a 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 and the counter electrode chamber. The regeneration apparatus may further include a power supply, control device, temperature control device, etc., that enable electrolysis.

[0063] The present invention may encompass the following embodiments. <1> A method for manufacturing an electronic component, comprising: removing at least a portion of the surfactant from a plating composition containing tin(IV) ions and a surfactant; introducing the plating composition from which at least a portion of the surfactant has been removed into a working electrode chamber, which is isolated by a counter electrode chamber equipped with a counter electrode and a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane and a nanofiltration membrane, and is equipped with a working electrode; reducing at least a portion of the tin(IV) ions in the introduced plating composition to metallic tin with the working electrode as the cathode; oxidizing at least a portion of the reduced metallic tin to tin(II) ions with the working electrode as the anode to obtain a regenerated plating composition; and contacting a plating solution containing at least a portion of the regenerated plating composition with a substrate having a first electrode layer on its surface, thereby forming a second electrode layer including a tin plating layer on the first electrode layer.

[0064] <2> At least a portion of the tin(IV) ions form a tin(IV) gluconate complex. <1> The manufacturing method described above.

[0065] <3> The ion exchange membrane is a cation exchange membrane. <1> or <2> The manufacturing method described above.

[0066] <4> The pH of the working electrode chamber is between 1 and 13. <1> from <3> A manufacturing method described in any of the following.

[0067] <5> The counter electrode chamber comprises an aqueous solution containing conductive ions. <1> from <4> A manufacturing method described in any of the following.

[0068] <6> Removing at least a portion of the surfactant from the plating composition includes contacting the plating composition with activated carbon. <1> from <5> A manufacturing method described in any of the following.

[0069] <7> The surfactant includes at least one selected from the group consisting of nonionic surfactants and cationic surfactants. <1> from <6> A manufacturing method described in any of the following.

[0070] <8> The aforementioned plating composition contains an antioxidant <1> from <7> A manufacturing method described in any of the following.

[0071] <9> A plating method comprising: removing at least a portion of the surfactant from a plating composition containing tin(IV) ions and a surfactant; introducing the plating composition from which at least a portion of the surfactant has been removed into a working electrode chamber, which is isolated by a counter electrode chamber equipped with a counter electrode and a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane and a nanofiltration membrane, and is equipped with a working electrode; reducing at least a portion of the tin(IV) ions in the introduced plating composition to metallic tin with the working electrode as the cathode; oxidizing at least a portion of the reduced metallic tin to tin(II) ions with the working electrode as the anode to obtain a regenerated plating composition; and contacting a workpiece to be plated with a plating solution containing at least a portion of the regenerated plating composition to form a tin plating layer on the surface of the workpiece to be plated.

[0072] <10> At least a portion of the tin(IV) ions form a tin(IV) gluconate complex. <9> The plating method described above.

[0073] <11> The ion exchange membrane is a cation exchange membrane. <9> or <10> The plating method described above.

[0074] <12> The pH of the working electrode chamber is between 1 and 13. <9> from <11> A plating method as described in any of the following.

[0075] <13> The counter electrode chamber comprises an aqueous solution containing conductive ions. <9> from <12> A manufacturing method described in any of the following.

[0076] <14> Removing at least a portion of the surfactant from the plating composition includes contacting the plating composition with activated carbon. <9> from <13> A manufacturing method described in any of the following.

[0077] <15> The surfactant includes at least one selected from the group consisting of nonionic surfactants and cationic surfactants. <9> from <14> A manufacturing method described in any of the following.

[0078] <16> The aforementioned plating composition contains an antioxidant <9> from <15> A manufacturing method described in any of the following.

[0079] <17> <1> from <16> The use of the regenerated plating composition in any of the methods described herein, wherein the regenerated plating composition is produced by a method for regenerating a plating composition comprising: removing at least a portion of the surfactant from a plating composition comprising tin(IV) ions and a surfactant; introducing the plating composition from which at least a portion of the surfactant has been removed into a working electrode chamber, which is isolated by a counter electrode chamber equipped with a counter electrode and a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane and a nanofiltration membrane, and which is equipped with a working electrode; reducing at least a portion of the tin(IV) ions in the introduced plating composition to metallic tin with the working electrode as the cathode; and oxidizing at least a portion of the reduced metallic tin to tin(II) ions with the working electrode as the anode to obtain a regenerated plating composition. [Examples]

[0080] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[0081] Reference example Preparation of plating composition A plating composition having the following composition was prepared using purified water, potassium stan(IV)ate as a tin(IV) ion source, tin(II) methanesulfonate as a tin(II) ion source, a cationic surfactant containing gluconic acid and decyltrimethylammonium chloride, hydroquinone, and sodium methanesulfonate.

[0082] 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: 1g / L Hydroquinone: 1g / L Sodium ions: 1.4 mol / L

[0083] Example 1 The 2 L of the plating composition prepared above was passed through an activated carbon cartridge (manufactured by Kankyo Technos Co., Ltd.; MX) attached to a filter at room temperature (25°C) and introduced into the working electrode chamber of the electrochemical apparatus. The electrochemical apparatus is 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 are separated by a cation exchange membrane (Noafion). (TM) It is isolated in 424). A 10 g / L sodium sulfate aqueous solution is placed in the counter electrode chamber of the electrolysis apparatus, with the working electrode as the cathode, and at a liquid temperature of 40°C to 70°C, 0.1 A / dm 2 From 0.5A / dm 2 At a current density of 36.1A, electrolysis was performed for 1 hour. Subsequently, with the working electrode as the anode, at a liquid temperature of 20°C to 70°C, 1A / dm 2 From 80A / dm 2 At a current density of 34.3A and 0.5 hours, electrolysis treatment was performed to obtain a regenerated plating composition as the treated gas plating composition.

[0084] The concentrations of tin(IV) 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 involved titrating with iodine standard solution in 2M hydrochloric acid using starch as an indicator 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 this total concentration.

[0085] As a result, the regenerated plating composition had a tin(IV) ion concentration of 0.04 mol / L and a tin(II) ion concentration of 0.16 mol / L. From these results, the reduction efficiency of tin(IV) ions is evaluated to be 95%. The reduction efficiency is calculated by dividing the integrated current value in the third step by half the integrated current value in the second step.

[0086] Here, the activated carbon contained in the activated carbon cartridge (MX) has a specific surface area of ​​437 m² as determined by the BET method. 2 The concentration was / g, and the average pore size was 2.4 nm. Furthermore, the mesopore shape, measured by INNES, showed an average pore width of 6.0 nm on the adsorption side and an average pore width of 2.1 nm on the desorption side.

[0087] Similar results were obtained when the activated carbon cartridge was changed to a YCC-R manufactured by Nippon Filter Co., Ltd.

[0088] Here, the activated carbon contained in the activated carbon cartridge (YCC-R) has a specific surface area of ​​1237 m² as determined by the BET method. 2 The concentration was / g, and the average pore size was 1.8 nm. Furthermore, the mesopore shape, measured by INNES, showed an average pore width of 2.5 nm on the adsorption side and an average pore width of 4.0 nm on the desorption side.

[0089] Comparative Example 1 The plating composition was subjected to two electrolytic treatments in the same manner as in Example 1, except that the plating composition was introduced directly into the working electrode chamber without passing through the activated carbon cartridge, to obtain the plated composition after treatment.

[0090] The concentrations of tin(IV) ions and tin(II) ions in the resulting plated composition were evaluated in the same manner. The concentration of tin(IV) ions was 0.19 mol / L, and the concentration of tin(II) ions was 0.01 mol / L. From these results, the reduction efficiency of tin(IV) ions is evaluated to be 0%.

[0091] Comparative Example 2 Except for using an electrolysis apparatus in which the working electrode chamber and the counter electrode chamber were not separated by a cation exchange membrane and were able to pass liquid through each other, two electrolysis treatments were performed in the same manner as in Example 1 to obtain the plated composition after treatment.

[0092] The concentrations of tin(IV) ions and tin(II) ions in the resulting plated composition were evaluated in the same manner. The concentration of tin(IV) ions was 0.20 mol / L, and the concentration of tin(II) ions was 0.0 mol / L. From these results, the reduction efficiency of tin(IV) ions is evaluated to be 0%.

[0093] Manufacturing example A plating solution containing the regenerated plating composition obtained in Example 1 is prepared. A component body having a first electrode layer consisting of a base layer and a nickel plating layer on the surface of a ceramic body is placed in the plating solution, a tin plating layer is formed by barrel plating to form a second electrode layer, and then an electronic component is manufactured by washing with water and drying. The resulting electronic component has a highly reliable external electrode.

[0094] The disclosures of Japanese Patent Application No. 2022-189216 (filing date: November 28, 2022) and International Patent Application No. PCT / JP2023 / 026074 (international filing date: July 14, 2023) are incorporated herein by reference in their entirety. All documents, patent applications, and technical standards described herein are incorporated by reference to the same extent as if each individual document, patent application, and technical standard had been specifically and individually indicated as being incorporated by reference.

Claims

1. Removing at least a portion of the surfactant from a plating composition containing tin(IV) ions and a surfactant, A counter electrode chamber equipped with a counter electrode is separated by a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, and a working electrode chamber equipped with a working electrode is introduced into the working electrode chamber, from which at least a portion of the surfactant has been removed, and at least a portion of the tin(IV) ions in the introduced plating composition is reduced to metallic tin using the working electrode as a cathode. To obtain a regenerated plating composition by oxidizing at least a portion of the reduced metallic tin to tin(II) ions using the working electrode as the anode, A plating solution containing at least a portion of the regenerated plating composition is brought into contact with a substrate having a first electrode layer on its surface, thereby forming a second electrode layer containing a tin plating layer on the first electrode layer. A method for manufacturing electronic components including [specific components].

2. Removing at least a portion of the surfactant from a plating composition containing tin(IV) ions and a surfactant, A counter electrode chamber equipped with a counter electrode is separated by a membrane selected from the group consisting of an ion exchange membrane, a reverse osmosis membrane, and a nanofiltration membrane, and a working electrode chamber equipped with a working electrode is introduced into the working electrode chamber, from which at least a portion of the surfactant has been removed, and at least a portion of the tin(IV) ions in the introduced plating composition is reduced to metallic tin using the working electrode as a cathode. To obtain a regenerated plating composition by oxidizing at least a portion of the reduced metallic tin to tin(II) ions using the working electrode as the anode, The process involves bringing a plating solution containing at least a portion of the regenerated plating composition into contact with an object to be plated, thereby forming a tin plating layer on the surface of the object to be plated. A plating method that includes [a specific type of plating].

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

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

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

6. The method according to claim 1 or 2, wherein a conductive ion-containing aqueous solution is disposed in the counter electrode chamber.

7. The method according to claim 1 or 2, wherein removing at least a portion of the surfactant from the plating composition is further comprising contacting the plating composition with activated carbon.

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

9. The plating composition according to claim 1 or 2, comprising an antioxidant.

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