JP2007046142A - Silver-based plating bath containing no cyanide, plated body and plating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver-based plating bath containing no cyanide, wherein the stability of silver ions is improved and a sufficient complexing ability is obtained, and the production cost is reduced and practical usability is excellent. <P>SOLUTION: The silver-based plating bath containing no cyanide comprises soluble salts including a silver salt and one or more kinds of sulfide compounds selected from the group comprising compounds each expressed by general formula (I) or the like, wherein n represents an integer of 2-4; R<SB>1</SB>and R<SB>2</SB>are same or different and each represent 1-3C alkyl group or 2-6C alkylene group which may be substituted with hydroxyl group; and M represents hydrogen, alkali metal, alkaline earth metal, ammonium or organic amine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cyanide-free silver-based plating bath, a plated body, and a plating method.

  Known silver-based plating baths include silver plating baths in which silver ions are dissolved in the bath and silver alloy plating baths that further contain metal ions other than silver ions in addition to silver ions. The silver alloy plating bath generally contains a complexing agent for chelating metal ions that are counterparts of silver ions.

As a conventional silver-based plating bath containing a complexing agent, a plating bath containing cyanide or thiourea is known. A cyan bath containing a cyanide compound is preferably used as a silver alloy plating bath including a silver-tin alloy plating bath.
However, the cyan bath is highly toxic, requires special wastewater treatment, and can be used only in the alkaline region, so that there are demerits such that the type of the counterpart metal is limited or the application is limited.

Therefore, a plating bath containing a sulfide compound having a sulfide group as a complexing agent has already been proposed as a silver plating bath in which silver ions can be stably dissolved in a wide pH range including a strongly acidic region. (For example, see Patent Documents 1 to 4).
Among these, Patent Documents 1 and 4 indicate that a compound having a plurality of sulfide groups in one molecule is used as a complexing agent. Patent Documents 2 and 3 show that a compound having two sulfide groups and a sulfonic acid group as a terminal group is used as a complexing agent in a substitutional electroless plating solution.

JP 2000-328286 A JP 2000-309876 A JP 2000-309875 A Japanese Patent Application Laid-Open No. 11-269691

  Although the above complexing agent comprising the conventional sulfide compound can be put into practical use, it cannot obtain a sufficient complexing power for silver ions in the bath, and has a high concentration of silver due to its low water solubility. When ions are used, a problem arises that a sufficient amount cannot be added to the plating solution, and the cost of the raw material for the complexing agent is high.

The object of the present invention is to provide a cyanide-free silver-based plating bath excellent in practicality, which can improve the stability of silver ions in the bath, obtain a sufficient complexing power, and reduce production costs. There is to do.
Another object of the present invention is to provide a plated body and a plating method using the same.

The cyanide-free silver-based plating bath of the present invention comprises a soluble salt containing a silver salt and the following general formula (I):
And one or more sulfide compounds selected from the group consisting of the compounds respectively represented by (II) and (III).
Formula (I):

(.M .R ₁ and R ₂ in the formula, n is an integer of 2 to 4 represent the same or different, optionally C ₂ ~ ₆ alkylene group C ₁ ~ ₃ alkyl or hydroxyl group is substituted, Represents hydrogen, an alkali metal, an alkaline earth metal, ammonium or an organic amine.)
General formula (II):

(Wherein, R _1, R ₂ and R ₃ are the same or different, .A representing a C ₁ ~ ₃ alkyl or hydroxyl substitutable C ₂ ~ ₆ alkylene group, B and C are the same or different , Hydroxyl group, carboxylic acid or salt thereof, sulfonic acid or salt thereof, phosphonic acid or salt thereof, or substituted or unsubstituted amine —N (R ₄ ) (R ₅ ) or —N (R ₆ ). , the alkali metal, alkaline earth metal, .R ₄ and R ₅ represents an ammonium or organic amine are the same or different, represent hydrogen or C ₁ ~ ₅ alkyl, R ₆ is hydrogen or one to three hydroxyl groups compounds represented by the representative. ") the substituted C ₁ ~ ₅ alkyl group, and,
Formula (III):

_{(Wherein, R 1, R 2, R} 3 and R ₄ are the same or different, .A representing a C ₁ ~ ₃ alkyl or hydroxyl group may be substituted C ₂ ~ ₆ alkylene group, B, C and D Are the same or different and are a hydroxyl group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphonic acid or a salt thereof, or a substituted or unsubstituted amine —N (R ₄ ) (R ₅ ) or —N (R ₆ ). represents. "salts are alkali metal, .R ₄ and R ₅ represents an alkali earth metal, ammonium or an organic amine are the same or different, represent hydrogen or C ₁ ~ ₅ alkyl, R ₆ is hydrogen or 1 three hydroxyl groups represents a C ₁ ~ ₅ alkyl group substituted. "), a compound represented by.

The cyanide-free silver plating bath of the present invention contains at least the compound of general formula (I), and the compounds of general formula (I) are represented by the following formulas (IV) and (V), respectively. It may be at least one of the compounds.
Formula (IV):

And a compound represented by
Formula (V):

A compound represented by

  Furthermore, in the cyanide-free silver-based plating bath of the present invention, the soluble salt further contains a metal salt of a metal other than silver, and the metal salt is tin, bismuth, indium, lead, copper, zinc, nickel, It may be one or more metals selected from the group consisting of gold, palladium and platinum.

The cyanide-free silver plating bath of the present invention further contains at least one surfactant selected from a nonionic surfactant, an anionic surfactant, a cationic surfactant and an amphoteric surfactant. Also good.
Furthermore, the cyanide-free silver-based plating bath of the present invention may further contain an antioxidant.

The plated body of the present invention is obtained by plating the object to be plated using the cyanide-free silver plating bath of the present invention. The object to be plated may be an electronic component having a portion made of a copper-based material.
The plating method of the present invention includes the step of plating the object to be plated using the cyanide-free silver plating bath of the present invention.

  According to the present invention, as a result of containing at least one selected from the group consisting of the compounds represented by the general formulas (I), (II) and (III) as a complexing agent, silver ions in the bath A cyanide-free silver-based plating bath having excellent stability can be obtained. Further, by containing such a complexing agent, sufficient complexing power can be obtained even in a wide pH range including strong acidity, and it is excellent not only in the initial stage but also after a relatively long period of time. Can keep complexing power.

  Furthermore, since such a complexing agent can be obtained at a lower cost than conventional sulfide compounds, it can be obtained in high purity with less contamination of impurities and decomposition products compared to conventional sulfide compounds. Since the quality or performance as described above can be ensured in this construction bath, the production cost of the plating bath can be reduced.

  Further, according to the present invention, by using a cyanide-free silver-based plating bath excellent in silver ion stability and complexing power, it is possible to efficiently plate the object to be plated.

The cyanide-free silver-based plating bath of the present invention is a silver-based plating bath containing no cyanide, and contains a soluble salt and a sulfide-based compound as a complexing agent.
The soluble salt includes at least a soluble silver salt that generates monovalent silver ions in a bath (hereinafter also referred to as a soluble silver salt), but does not exclude a hardly soluble salt.

  Soluble silver salts include inorganic acid silver salts such as silver sulfate, silver sulfite, silver carbonate, silver nitrate, silver borofluoride, silver sulfamate, silver oxide, silver sulfosuccinate, silver organic sulfonate, silver citrate, silver tartrate Further, organic acid silver salts such as silver gluconate and silver oxalate can be used, and silver chloride which can be secured to some extent by the action of a sulfide compound although it is originally a hardly soluble salt can be used.

  Examples of the organic sulfonate silver include silver methanesulfonate, silver ethanesulfonate, silver propanesulfonate, silver 2-propanesulfonate, silver butanesulfonate, silver 2-butanesulfonate, silver pentanesulfonate, and 2-hydroxyethane. Silver 1-sulfonate, silver 2-hydroxypropane-1-sulfonate, silver 2-hydroxybutane-1-sulfonate, silver 2-hydroxypentanesulfonate, silver p-toluenesulfonate, silver p-phenolsulfonate Among them, silver methanesulfonate, silver ethanesulfonate, silver 2-hydroxypropane-1-sulfonate, silver phenolsulfonate, silver citrate and the like are preferable.

  The soluble salt may further contain a metal salt of a metal other than silver. Examples of the metal other than silver include tin, bismuth, indium, lead, copper, zinc, nickel, gold, palladium, and platinum. Silver salts of metals other than silver may be used alone or in combination. In addition, tin, copper, gold | metal | money, palladium, and platinum are mentioned as preferable metals other than silver, Tin and copper are mentioned as a more preferable metal.

  The content of the soluble silver salt in terms of metal salt is 0.0001 to 200 g / L, preferably 0.1 to 80 g / L.

As the complexing agent, one or more selected from the group consisting of compounds represented by the following general formulas (I), (II) and (III) are used.
Formula (I):

(In the formula, n represents an integer of 1 to 4 (in the case of n = 1, it is used only as an electroplating bath, and in the case of n = 2 to 4, any of an electroplating bath and an electroless plating bath) can also be used for) .R ₁ and R ₂ are the same or different, .M representing a C ₁ ~ ₃ alkyl or hydroxyl group may be substituted C ₂ ~ ₆ alkylene group, a hydrogen, alkali metal, alkaline Represents an earth metal, ammonium or an organic amine.)
General formula (II):

(Wherein, R _1, R ₂ and R ₃ are the same or different, .A representing a C ₁ ~ ₃ alkyl or hydroxyl substitutable C ₂ ~ ₆ alkylene group, B and C are the same or different , Hydroxyl group, carboxylic acid or salt thereof, sulfonic acid or salt thereof, phosphonic acid or salt thereof, or substituted or unsubstituted amine —N (R ₄ ) (R ₅ ) or —N (R ₆ ). , alkali metals, alkaline earth metals, .R ₄ and R ₅ represents an ammonium or organic amine are the same or different, represent hydrogen or C ₁ ~ ₅ alkyl, R ₆ is hydrogen or one to three hydroxyl groups compounds represented by the representative. ") the substituted C ₁ ~ ₅ alkyl group, and,
Formula (III):

_{(Wherein, R 1, R 2, R} 3 and R ₄ are the same or different, .A representing a C ₁ ~ ₃ alkyl or hydroxyl group may be substituted C ₂ ~ ₆ alkylene group, B, C and D Are the same or different and are a hydroxyl group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphonic acid or a salt thereof, or a substituted or unsubstituted amine —N (R ₄ ) (R ₅ ) or —N (R ₆ ). represents. "salts are alkali metal, .R ₄ and R ₅ represents an alkali earth metal, ammonium or an organic amine are the same or different, represent hydrogen or C ₁ ~ ₅ alkyl, R ₆ is hydrogen or 1 three hydroxyl groups represents a C ₁ ~ ₅ alkyl group substituted. "), a compound represented by.

In these compounds, the C ₁ ~ ₃ alkyl, methyl, ethyl, n- propyl, i- propyl and the like.

The C ₂ ~ ₆ alkylene group, can be exemplified ethylene, trimethylene, propylene, butylene, tetramethylene, pentamethylene, 3,3-dimethyl trimethylene, a linear or branched alkylene group such as hexamethylene group or the like, in particular, propylene and C ₃ ~ ₄ alkylene group such as butylene preferred.

  Examples of organic amines include alkylamines such as ethylamine, propylamine, and butylamine.

The C ₁ ~ ₅ alkyl, said C ₁ ~ ₃ other alkyl, n- butyl group, i- butyl group, sec- butyl group, t- butyl group can be exemplified by pentyl group.

The C ₁ ~ ₅ alkyl group, said C ₁ ~ ₅ other alkyl, hexyl group, heptyl group, octyl group and the like.

In addition, in the compounds of the general formulas (I) to (III), the compounds in which R ₁ to ₄ are propylene groups are particularly preferable because they are excellent in stabilizing the silver plating bath.

The compounds of the general formulas (I) to (III) can be obtained by reacting mercaptans and halides in the usual manner in the presence of a base. For example, in the formula (I), n = 2, R _1-2 is propylene, and M is Na, 1 mol of 2,2′-thiodiethanethiol and 2 mol of sodium 3-chloropropanesulfonate It can be obtained by heating in a solvent such as water or alcohol in the presence of 2 mol of sodium hydroxide.

  Moreover, it is preferable that the cyanide-free silver-based plating bath of the present invention further contains a base acid.

Examples of the base acid include organic acids, inorganic acids, and salts thereof.
The organic acid is preferably an organic sulfonic acid such as alkane sulfonic acid, alkanol sulfonic acid or aromatic sulfonic acid, which is relatively easy to treat waste water, or an aliphatic carboxylic acid.

Examples of inorganic acids include borohydrofluoric acid, silicohydrofluoric acid, sulfamic acid, hydrochloric acid, sulfuric acid, nitric acid, perchloric acid, and the like.
These acids or salts thereof can be used singly or in combination, and the content thereof is 0.1 to 400 g / L, preferably 20 to 250 g / L, based on 1 L of bath.

As the alkane sulfonic acid, those represented by the chemical formula C _n H _{2n + 1} SO ₃ H (for example, n = 1 to 5, preferably 1 to 3) can be used. Specifically, methane sulfonic acid, ethane sulfone can be used. In addition to acids, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid, and the like, hexanesulfonic acid, decanesulfonic acid, dodecanesulfonic acid, and the like can be given.

As the alkanol sulfonic acid, those represented by the chemical formula C _m H _{2m + 1} —CH (OH) —C _p H _2p —SO ₃ H (for example, m = 0 to 6, p = 1 to 5) can be used. Specific examples include 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 2-hydroxypentane-1-sulfonic acid, and the like. Hydroxypropane-2-sulfonic acid, 3-hydroxypropane-1-sulfonic acid, 4-hydroxybutane-1-sulfonic acid, 2-hydroxyhexane-1-sulfonic acid, 2-hydroxydecane-1-sulfonic acid, 2- Examples thereof include hydroxydodecane-1-sulfonic acid.

  Examples of the aromatic sulfonic acid include benzene sulfonic acid, alkyl benzene sulfonic acid, phenol sulfonic acid, naphthalene sulfonic acid, and alkyl naphthalene sulfonic acid. More specifically, 1-naphthalene sulfonic acid, 2-naphthalene sulfonic acid, Examples include toluenesulfonic acid, xylenesulfonic acid, p-phenolsulfonic acid, cresolsulfonic acid, sulfosalicylic acid, nitrobenzenesulfonic acid, sulfobenzoic acid, diphenylamine-4-sulfonic acid, and the like.

  In general, a carboxylic acid having 1 to 6 carbon atoms can be used as the aliphatic carboxylic acid. Specific examples include acetic acid, propionic acid, butyric acid, citric acid, tartaric acid, gluconic acid, sulfosuccinic acid, and trifluoroacetic acid.

  The cyanide-free silver-based plating bath of the present invention includes various known surfactants, antioxidants, smoothing agents, brightening agents, semi-brightening agents, pH adjusting agents, buffering agents, preservatives, and the like depending on purposes. An additive may be further contained. These additive concentrations can be arbitrarily adjusted and selected in accordance with barrel plating, rack plating, high-speed continuous plating, rackless plating, electroless plating, and the like. The cyanide-free silver plating bath of the present invention can be prepared by a conventional method.

Surfactant is added mainly to improve the denseness, smoothness, adhesion, etc. of the deposited silver film. Nonionic surfactants, amphoteric surfactants, cationic surfactants and anionic surfactants One or more of these can be used.
The addition amount is 0.01 to 100 g / L, preferably 0.1 to 50 g / L.

  Specific examples of nonionic surfactants include C1-C20 alkanols, phenols, naphthols, bisphenols, (poly) C1-C25 alkylphenols, (poly) arylalkylphenols, C1-C25 alkylnaphthols, C1-C25 alkoxylated phosphoric acids. Or a salt thereof, a sorbitan ester, a polyalkylene glycol, a C1-C22 aliphatic amine, a C1-C22 aliphatic amide, etc., and 2-300 mol addition-condensation of ethylene oxide (EO) and / or propylene oxide (PO), Examples thereof include C1-C25 alkoxylated phosphoric acid or a salt thereof.

  C1-C20 alkanols for addition condensation of ethylene oxide and / or propylene oxide include methanol, ethanol, n-butanol, t-butanol, n-hexanol, octanol, decanol, lauryl alcohol, tetradecanol, hexadecanol, stearyl alcohol Eicosanol, oleyl alcohol, docosanol and the like. Examples of bisphenols include bisphenol A, bisphenol B, and bisphenol F. (Poly) C1-C25 alkylphenols include mono-, di- or trialkyl-substituted phenols such as p-methylphenol, p-butylphenol, p-isooctylphenol, p-nonylphenol, p-hexylphenol, 2,4-di. Examples include butylphenol, 2,4,6-tributylphenol, dinonylphenol, p-dodecylphenol, p-laurylphenol, and p-stearylphenol. Examples of the arylalkylphenol include 2-phenylisopropylphenol, cumylphenol, (mono, di or tri) styrenated phenol, (mono, di or tri) benzylphenol and the like. Examples of the alkyl group of the C1-C25 alkyl naphthol include methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl, octadecyl and the like, and may be at an arbitrary position of the naphthalene nucleus. Examples of the polyalkylene glycol include polyoxyethylene glycol, polyoxypropylene glycol, and polyoxyethylene polyoxypropylene copolymer.

C1-C25 alkoxylated phosphoric acid or a salt thereof is represented by the following general formula (a).
Ra, Rb, (MO) P = O (a)
(In the formula (a), Ra and Rb represent the same or different C1-C25 alkyl groups, provided that one of them may be hydrogen. M represents hydrogen or an alkali metal.)

  Sorbitan esters include mono-, di- or triesterized 1,4-, 1,5- or 3,6-sorbitan, such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan distearate, sorbitan dioleate, Examples include sorbitan mixed fatty acid esters. C1-C22 aliphatic amines include propylamine, butylamine, hexylamine, octylamine, decylamine, laurylamine, myristylamine, stearylamine, oleylamine, beef tallow amine, ethylenediamine, propylenediamine, and other saturated and unsaturated fatty acid amines. Can be mentioned. Examples of the C1-C22 aliphatic amide include amides such as propionic acid, butyric acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid, coconut oil fatty acid, and beef tallow fatty acid. .

Furthermore, as a nonionic surfactant,
R1N (R2) 2 = O
(Wherein R1 represents a C5 to C25 alkyl group or RCONHR3 (R3 represents a C1 to C5 alkylene group. R2 represents the same or different C1 to C5 alkyl group) or the like, and an amine oxide represented by Can do.

As the cationic surfactant, a quaternary ammonium salt represented by the following general formula (b)
(R1, R2, R3, R4N) +. X- (b)
(In the formula (b), X represents a halogen group, a hydroxyl group, a C1-C5 alkanesulfonic acid group or sulfuric acid. R1, R2, R3 and R4 may be the same or different, each having a C1-C20 alkyl, Represents an aryl or benzyl group) or a pyridinium salt represented by the following general formula (c).
R6- (C5H4N-R5) +. X- (c)
(In formula (c), C5H4N represents a pyridine ring. X represents a halogen group, a hydroxyl group, a C1-C5 alkanesulfonic acid group or sulfuric acid. R5 represents a C1-C20 alkyl group. R6 represents hydrogen or C1. Represents a C10 alkyl group.

  Examples of cationic surfactants in the form of salts include lauryl trimethyl ammonium salt, stearyl trimethyl ammonium salt, lauryl dimethyl ethyl ammonium salt, octadecyl dimethyl ethyl ammonium salt, dimethyl benzyl lauryl ammonium salt, cetyl dimethyl benzyl ammonium salt, octadecyl dimethyl Benzylammonium salt, trimethylbenzylammonium salt, triethylbenzylammonium salt, dimethyldiphenylammonium salt, benzyldimethylphenylammonium salt, hexadecylpyridinium salt, laurylpyridinium salt, dodecylpyridinium salt, stearylamine acetate, laurylamine acetate, octadecylamine acetate, etc. Is mentioned.

  Anionic surfactants include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl benzene sulfonates, {(mono, di, tri) alkyl} naphthalene sulfonates, and the like. Can be mentioned. Examples of the alkyl sulfate include sodium lauryl sulfate and sodium oleyl sulfate. Examples of the polyoxyethylene alkyl ether sulfate include sodium polyoxyethylene (EO5) nonyl ether sulfate and sodium polyoxyethylene (EO15) dodecyl ether sulfate. Examples of the polyoxyethylene alkylphenyl ether sulfate include polyoxyethylene (EO15) nonylphenyl ether sulfate. Examples of the alkyl benzene sulfonate include sodium dodecylbenzene sulfonate. Examples of the {(mono, di, tri) alkyl} naphthalene sulfonate include naphthalene sulfonate, sodium dibutyl naphthalene sulfonate, and naphthalene sulfonate formalin condensate.

  Examples of amphoteric surfactants include carboxybetaine, imidazoline betaine, sulfobetaine, and aminocarboxylic acid. Further, a sulfated product or a sulfonated adduct of a condensation product of ethylene oxide and / or propylene oxide and an alkylamine or diamine can also be used.

  Representative carboxybetaines or imidazoline betaines are lauryldimethylaminoacetic acid betaine, myristyldimethylaminoacetic acid betaine, stearyldimethylaminoacetic acid betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, 2-undecyl-1-carboxymethyl-1- And hydroxyethyl imidazolinium betaine, 2-octyl-1-carboxymethyl-1-carboxyethyl imidazolinium betaine, and the like. Examples of sulfated and sulfonated adducts include sulfated adducts of ethoxylated alkylamines and lauryl sulfonated sulfonates. Examples include acid derivative sodium salts.

  Examples of sulfobetaines include coconut oil fatty acid amidopropyldimethylammonium-2-hydroxypropanesulfonic acid, sodium N-cocoylmethyltaurine, sodium N-palmitoylmethyltaurine, and the like. Examples of the aminocarboxylic acid include dioctylaminoethylglycine, N-laurylaminopropionic acid, octyldi (aminoethyl) glycine sodium salt, and the like.

  Antioxidant is added for the purpose of preventing air oxidation of metal ions in the bath, ascorbic acid or a salt thereof, erythorbic acid or a salt thereof, hydroquinone, resorcin, catechol, hydroquinonesulfonic acid or a salt thereof, catecholsulfonic acid or The salt, phenolsulfonic acid or its salt etc. are mentioned. Antioxidants are particularly effective when obtaining silver alloy plating baths such as silver-tin alloys.

  As the smoothing agent, β-naphthol, β-naphthol-6-sulfonic acid, β-naphthalenesulfonic acid, benzaldehyde, m-chlorobenzaldehyde, p-nitrobenzaldehyde, p-hydroxybenzaldehyde, (o-, p-) methoxybenzaldehyde , Vanillin, (2,4-, 2,6-) dichlorobenzaldehyde, (o-, p-) chlorobenzaldehyde, 1-naphthaldehyde, 2-naphthaldehyde, 2 (4) -hydroxy-1-naphthaldehyde, 2 (4) -Chloro-1-naphthaldehyde, 2 (3) -thiophenecarboxaldehyde, 2 (3) -furaldehyde, 3-indolecarboxaldehyde, salicylaldehyde, o-phthalaldehyde, formaldehyde, acetaldehyde, paraaldehyde, butyl Aldehyde, isobutyl al Dehydr, propionaldehyde, n-valeraldehyde, acrolein, crotonaldehyde, glyoxal, aldol, succinaldehyde, capronaldehyde, isovaleraldehyde, allylaldehyde, glutaraldehyde, 1-benzylidene-7-heptanal, 2,4-hexadiene Nal, cinnamaldehyde, benzylcrotonaldehyde, amine-aldehyde condensate, mesityl oxide, isophorone, diacetyl, hexanedione-3,4, acetylacetone, benzylideneacetone, 3-chlorobenzylideneacetone, sub.pyridylideneacetone, sub. Diacetone, sub.tenylideneacetone, 4- (1-naphthyl) -3-buten-2-one, 4- (2-furyl) -3-buten-2-one, 4- (2-thiopheny) ) -3-buten-2-one, curcumin, benzylideneacetylacetone, benzalacetone, acetophenone, (2,4-, 3,4-) dichloroacetophenone, benzylideneacetophenone, 2-cinnamylthiophene, 2- (ω- (Benzoyl) vinyl furan, vinyl phenyl ketone, acrylic acid, methacrylic acid, ethacrylic acid, ethyl acrylate, methyl methacrylate, butyl methacrylate, crotonic acid, propylene-1,3-dicarboxylic acid, cinnamic acid, (o-, m-, p-) toluidine, (o-, p-) aminoaniline, aniline, (o-, p-) chloroaniline, (2,5-3,4-) chloromethylaniline, N-monomethylaniline, 4,4'-diaminodiphenylmethane, N-phenyl- (α-, β-) naphthylamine, methylbenztriazole, 1,2 , 3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,3-benztriazine, imidazole, 2-vinylpyridine, indole, quinoline, aniline, phenanthroline, neocuproin, picolinic acid, Examples thereof include a reaction product of monoethanolamine and o-vanillin, polyvinyl alcohol, catechol, hydroquinone, resorcin, polyethyleneimine, disodium ethylenediaminetetraacetate, polyvinylpyrrolidone and the like.

  Gelatin, polypeptone, N- (3-hydroxybutylidene) -p-sulfanilic acid, N-butylidenesulfanilic acid, N-cinnamoylidenesulfanilic acid, 2,4-diamino-6- (2'-methylimidazolyl) (1 ′)) ethyl-1,3,5-triazine, 2,4-diamino-6- (2′-ethyl-4-methylimidazolyl (1 ′)) ethyl-1,3,5-triazine, 2, 4-Diamino-6- (2'-undecylimidazolyl (1 ')) ethyl-1,3,5-triazine, phenyl salicylate, or benzothiazoles are also effective as a smoothing agent.

  Examples of benzothiazoles include benzothiazole, 2-methylbenzothiazole, 2-mercaptobenzothiazole, 2- (methylmercapto) benzothiazole, 2-aminobenzothiazole, 2-amino-6-methoxybenzothiazole, 2-methyl- 5-chlorobenzothiazole, 2-hydroxybenzothiazole, 2-amino-6-methylbenzothiazole, 2-chlorobenzothiazole, 2,5-dimethylbenzothiazole, 6-nitro-2-mercaptobenzothiazole, 5-hydroxy- Examples include 2-methylbenzothiazole, 2-benzothiazolethioacetic acid and the like.

Examples of the pH adjuster include various acids such as hydrochloric acid and sulfuric acid, various bases such as aqueous ammonia, potassium hydroxide, and sodium hydroxide.
Examples of the buffer include boric acids, phosphoric acids such as phosphinic acid and phosphonic acid, phosphoric acid and tripolyphosphoric acid, dicarboxylic acids such as oxalic acid and succinic acid, oxycarboxylic acids such as lactic acid and tartaric acid, and ammonium chloride and ammonium sulfate. It is done.

Examples of the preservative include boric acid, 5-chloro-2-methyl-4-isothiazolin-3-one, benzalkonium chloride, phenol, phenol polyethoxylate, thymol, resorcin, isopropylamine, and guaiacol.
Examples of antifoaming agents include pluronic surfactants, higher aliphatic alcohols, acetylene alcohols and polyalkoxylates thereof.

  The plated body of the present invention is obtained by plating a body to be plated using the above-described cyanide-free silver plating bath of the present invention, and the body to be plated has a portion made of a copper-based material. Electronic parts are mentioned. Examples of such electronic components include printed circuit boards, semiconductor integrated circuits, resistors, variable resistors, capacitors, filters, inductors, thermistors, crystal resonators, switches, lead wires, and the like. The copper-based material refers to a material made of copper or a copper alloy.

  The plating method of the present invention includes a step of plating the object to be plated using the above-described cyanide-free silver plating bath of the present invention. In this step, specifically, a silver or silver alloy film is formed on the surface of the object to be plated by immersing the object to be plated in a cyanide-free silver-based plating bath for an appropriate time.

For example, when electroplating is performed, the bath temperature is generally 70 ° C. or lower, preferably about 10 to 50 ° C. Cathode current density, but there are some differences depending on the type of plating bath, typically 0.01~150A / dm ² mm, preferably is 0.1~50A / dm ² about. As the cathode, silver, a silver alloy, an insoluble anode, or the like can be used.

  When performing substitution silver plating, the pH of the bath is adjusted to 8.0 or less, and the object to be plated is immersed in such a bath for about 1 second to 30 minutes, and plating is performed until a desired film thickness is obtained. Deposit a film. In this case, the bath temperature is preferably about 10 ° C. to 80 ° C., and the plating time is determined depending on the film thickness. Furthermore, it is preferable to stir the bath as necessary.

Examples of the present invention will be specifically described below.
Example 1
A silver-tin alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 1g / l
Stannous methanesulfonate (as Sn ²⁺ ) 40 g / l
Methanesulfonic acid (as free acid) 120g / l
Methylnaphthol polyethoxylate (EO21) 2g / l
Compound of formula (I) (n = 2, R ₁ = R ₂ = propylene, M = Na) 12.4 g / l

(Example 2)
A silver-tin alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 0.7g / l
Stannous sulfate (as Sn ²⁺ ) 20g / l
96% sulfuric acid (as free acid) 150g / l
Octylphenol polyethoxylate (EO17.5) 5 g / l
Hexadecyldimethylbenzylammonium methanesulfonate 1g / l
β-naphthol-6-sulfonic acid 0.2 g / l
Compound of formula (I) (n = 3, R ₁ = R ₂ = ethylene, M = K) 10 g / l

(Example 3)
A silver-tin alloy plating bath was constructed with the following composition.
Silver 2-hydroxypropane-1-sulfonate (as Ag ⁺ ) 3 g / l
2-hydroxypropane-1-stannic acid stannate (as Sn ²⁺ ) 60 g / l
2-hydroxypropane-1-sulfonic acid (as free acid) 70 g / l
Dodecyldimethylaminoacetic acid betaine 1g / l
Hexadecyldimethylbenzylammonium ethanesulfonate 1g / l
Hydroquinone 1g / l
Compound of formula (I) (n = 2, R ₁ = R ₂ = propylene, M = NH ₄ ) 38 g / l

Example 4
A silver-tin alloy plating bath was constructed with the following composition.
Silver ethanesulfonate (as Ag ⁺ ) 5 g / l
Stannous ethanesulfonate (as Sn ²⁺ ) 30g / l
Methanesulfonic acid (as free acid) 100g / l
Gluconic acid 0.7mol / l
Polyethyleneimine (Molecular weight: 16,000) 5g / l
Diethyl-β-naphthol polyethoxylate (EO19) 1 g / l
Catechol 0.5g / l
Compounds of formula _{(II) (R 1 ~ 3} = ethylene, A~C = OH) 32g / l
pH 4.0 (adjusted with NaOH)

(Example 5)
A silver-tin alloy plating bath was constructed with the following composition.
Silver borofluoride (as Ag ⁺ ) 10g / l
Stannous borofluoride (as Sn ²⁺ ) 20g / l
Borohydrofluoric acid (as free acid) 130g / l
Boric acid 30g / l
2-undecyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine 10 g / l
Dodecyldimethylbenzylammonium methanesulfonate 1g / l
Methylnaphthol polyethoxylate (EO17) 1g / l
Compounds of formula _{(II) (R 1 ~ 3} = propylene, A~C = OH) 120g / l

(Example 6)
A silver-bismuth alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 20 g / l
Bismuth methanesulfonate (as Bi ³⁺ ) 10g / l
Methanesulfonic acid (as free acid) 150g / l
Polyethoxylate (EO25) Polypropoxylate (PO25)
Block copolymer 10g / l
Methylnaphthol polyethoxylate (EO21) 3g / l
Orthochlorobenzaldehyde 0.1g / l
Compounds of formula _{(II) (R 1 ~ 4} = _{ethylene, A~D = SO 3 K) 276g} / l

(Example 7)
A silver-indium alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 20 g / l
Indium sulfate (as In ³⁺ ) 20g / l
Methanesulfonic acid (as free acid) 120g / l
Polyvinyl alcohol 7g / l
Dibutyl-β-naphthol polyethoxylate (EO15) 2 g / l
Tetrabutylammonium methanesulfonate 2g / l
Compounds of formula _{(II) (R 1 ~ 4} = 2- _{hydroxypropylene, A~D = SO 3 K) 320g} / l

(Example 8)
A silver-tin alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 20 g / l
Tin methanesulfonate (as Sn ²⁺ ) 20g / l
Methanesulfonic acid (as free acid) 70g / l
Distyrenated phenol polyethoxylate (EO30) 8g / l
Benzyldimethyldodecyl ammonium methanesulfonate 1g / l
2-mercaptobenzothiazole 0.2 g / l
Compound of formula (I) (n = 1, R _{1 to} R ₂ = propylene, M = Na) 275 g / l

Example 9
A silver-copper alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 20 g / l
Cupric sulfate (as Cu ²⁺ ) 20g / l
96% sulfuric acid (as free acid) 100 g / l
Bisphenol F polyethoxylate (EO23) 5g / l
Dibutylphenol polyethoxylate (EO16) 1g / l
2,2′-bipyridyl 0.03 g / l
Resorcin 0.3g / l
Compounds of formula _{(III) (R 1 ~ 4} = _{propylene, A~D = SO 3 K) 300g} / l

(Example 10)
A silver-zinc alloy plating bath was constructed with the following composition.
Silver nitrate (as Ag ⁺ ) 20 g / l
Zinc sulfate (as Zn ²⁺ ) 20g / l
96% sulfuric acid (as free acid) 100 g / l
Coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine 2g / l
β-naphthol 1g / l
Compounds of formula _{(II) (R 1 ~ 3} = 2- hydroxypropylene, A~C = SO ₃ K) 314g
/ L

(Example 11)
A silver-nickel alloy plating bath was constructed with the following composition.
Silver nitrate (as Ag ⁺ ) 20 g / l
Nickel sulfate (as Ni ²⁺ ) 5g / l
96% sulfuric acid (as free acid) 100 g / l
p-Methoxybenzyltributylammonium hydroxide 1.5 g / l
2,6-dihydroxynaphthalene 1g / l
Compounds of formula _{(III) (R 1 ~ 4} = _{propylene, A~D = SO 3 Na) 273g} / l

(Example 12)
A silver-palladium alloy plating bath was constructed with the following composition.
Silver ethanesulfonate (as Ag ⁺ ) 10 g / l
Palladium methanesulfonate (as Pb2 ⁺ ) 1g / l
2-hydroxypropane-1-sulfonic acid (as free acid) 100 g / l
Polyvinylpyrrolidone 5g / l
Dibenzylphenol polyethoxylate (EO28) 8g / l
Ethylenediaminetetraacetic acid disodium 1g / l
Formula (III) compounds of the (R ₁ ~ ₄ = 2- hydroxypropylene, to D = OH)
128g / l

(Example 13)
A silver-gold alloy plating bath was constructed with the following composition.
2-hydroxypropane-1-sulfonic acid silver (as Ag ⁺ ) 10 g / l
Gold 2-hydroxypropane-1-sulfonate (as Au ⁺ ) 1 g / l
2-hydroxypropane-1-sulfonic acid (as free acid) 100 g / l
Didodecylphenol polyethoxylate (EO32) 1g / l
Octyldi (aminoethyl) glycine sodium 1.5 g / l
Imidazole 0.5g / l
Compounds of formula _{(II) (R 1 ~ 3} = _{propylene, A~C = SO 3 Na) 121g} / l

(Example 14)
A silver plating bath was constructed with the following composition.
Silver tartrate (as Ag ⁺ ) 20g / l
Tartaric acid 100g / l
Coconut oil amine polyethoxylate (EO24) 1g / l
2-octyl-1-carboxymethyl-1-carboxyethyl
Imidazolinium betaine 5g / l
Compounds of formula _{(II) (R 1 ~ 3} = _{propylene, A~C = SO 3 Na) 242g} / l
pH = 4.0 (adjusted with ammonia)

(Example 15)
A silver-tin-copper alloy plating bath was constructed with the following composition.
Silver 2-hydroxypropane-1-sulfonate (as Ag ⁺ ) 1 g / l
Stannous ethanesulfonate (as Sn ²⁺ ) 50g / l
Copper methanesulfonate (Cu ²⁺ ) 0.2g / l
Methanesulfonic acid (as free acid) 120g / l
Bisphenol F polyethoxylate (EO15) 5g / l
Tristyrenated phenol polyethoxylate (EO30) 3g / l
Compounds of formula (I) (n = 2, R 1 ~ 2 = propylene, M = Na) 12g / l

(Example 16)
A silver-lead alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 10 g / l
Lead methanesulfonate (as Pb2 ⁺ ) 10g / l
Methanesulfonic acid (as free acid) 100g / l
Methyl-β-naphthol polyethoxylate (EO21) 12 g / l
Polypeptone 1g / l
Compounds of formula _{(II) (R 1 ~ 3} = 2- hydroxypropylene, A~C = OH) 85g / l

(Example 17)
A silver plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 1g / l
Methanesulfonic acid (as free acid) 50g / l
Dibutyl-β-naphthol polyethoxylate (EO21) 1 g / l
Compounds of formula _{(III) (R 1 ~ 4} = _{propylene, A~D = N (CH 3)} 2) 15g / l

(Example 18)
A silver-tin alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 0.1 g / l
Stannous sulfate (as Sn ²⁺ ) 30g / l
96% sulfuric acid (as free acid) 70 g / l
Octylphenol polyethoxylate (EO15) 5g / l
Hexadecyldimethylbenzylammonium methanesulfonate 1g / l
Dibutylphenol polyethoxylate (EO17) 0.5g / l
β-naphthol-6-sulfonic acid 0.2 g / l
Compounds of formula _{(II) (R 1 ~ 3} = _{propylene, A~C = SO 3 Na) 1.5g} / l
Hypophosphorous acid 15g / l

(Comparative Example 1)
A silver-tin alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 1g / l
Stannous methanesulfonate (as Sn ²⁺ ) 40 g / l
Methanesulfonic acid (as free acid) 120g / l
Methylnaphthol polyethoxylate (EO21) 2g / l
Thiourea 2.2g / l

(Comparative Example 2)
A silver-tin alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 1g / l
Stannous methanesulfonate (as Sn ²⁺ ) 40 g / l
Methanesulfonic acid (as free acid) 120g / l
Methylnaphthol polyethoxylate (EO21) 2g / l
HOCH ₂ CH _2- (S-CH ₂ CH ₂ ) ₂ -S-CH ₂ CH ₂ OH 7 g / l

(Comparative Example 3)
A silver-tin alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 1g / l
Stannous methanesulfonate (as Sn ²⁺ ) 40 g / l
Methanesulfonic acid (as free acid) 120g / l
Methylnaphthol polyethoxylate (EO21) 2g / l
HOCH ₂ CH ₂ CH ₂ -S-CH ₂ CH ₂ -S-CH ₂ CH ₂ CH ₂ OH 10 g / l

(Comparative Example 4)
A silver plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 1g / l
Methanesulfonic acid (as free acid) 50g / l
Dibutyl-β-naphthol polyethoxylate (EO21) 1 g / l
Thiourea 2.2g / l

(Comparative Example 5)
A silver-tin alloy plating bath was constructed with the following composition.
Silver methanesulfonate (as Ag ⁺ ) 0.1 g / l
Stannous sulfate (as Sn ²⁺ ) 30g / l
96% sulfuric acid 70g / l
Octylphenol polyethoxylate (EO15) 5g / l
Hexadecyldimethylbenzylammonium methanesulfonate 1g / l
Dibutylphenol polyethoxylate (EO17) 0.5g / l
β-naphthol-6-sulfonic acid 0.2 g / l
Compounds of formula (I) (n = 1, R 1 ~ 2 = ethylene, M = Na) 1g / l
Hypophosphorous acid 15g / l

  In silver-based plating baths that do not contain cyanide, the stability of the bath is extremely important because the bath is likely to decompose above all and silver is likely to precipitate. Therefore, in the following test, first, the change with time of the bath was observed to determine whether the bath maintained practical stability (the change test with time of the plating bath). Moreover, while measuring the silver eutectoid rate in the electrodeposition film obtained from a plating bath (silver eutectoid rate measurement test), the presence or absence of abnormality of the electrodeposition film (that is, whether the film appearance is at a practical level) (1) Confirmation test was conducted (appearance test of plating film).

<Plating bath aging test>
Each plating bath of the above examples and comparative examples is accommodated in a 1 L beaker, and these are kept warm for 1008 hours in a water bath set at a constant temperature of 50 ° C., and the degree of deterioration (decomposition) state of each plating solution. The stability over time was visually evaluated by observing. Table 1 shows the results.

In Table 1, the evaluation criteria for stability over time are as follows.
○: The plating bath was stable at the time when 1008 hours had passed, and the transparency was high, and there was no change compared to the initial bathing.
Δ: Turbidity and precipitation occurred from 168 hours to 504 hours, and the plating bath was decomposed.
X: Turbidity and precipitation occurred by 168 hours, and the plating bath was decomposed.

<Measurement test of silver eutectoid rate and appearance test of plating film>
For Examples 1 to 16 and Comparative Examples 1 to 3, electroplating was performed while changing the current density conditions, and the eutectoid rate of silver in the electrodeposition film obtained from the bath was determined using an ICP emission analyzer (fluorescent X-ray film). It was measured using a thickness gauge. Also, visually observe the appearance of the obtained electrodeposition coating to check for abnormalities such as burnt, dendrite, or powdering, and the minimum necessary level for a practical plating film It was evaluated whether it was equipped.

  Moreover, about Examples 17-18 and Comparative Examples 4-5, each electroless-plating bath was hold | maintained at 65 degreeC, and the film carrier of TAB (tape automatic bonding) patterned by VLP (a kind of electrolytic copper foil) The test piece was dipped for 10 minutes and subjected to electroless silver or silver-tin alloy plating.

  And about each obtained plating film, while measuring the composition ratio (%) of the silver in a film | membrane, about the electroless plating film | membrane, the film thickness (micrometer) of the film | membrane was measured with the apparatus. Further, the appearance was visually observed to check for the presence of stains and color unevenness. Table 1 shows the results.

In Table 1, the evaluation criteria for the appearance test are as follows.
◯: There was no abnormality in the appearance of the film, the appearance was white, the metallic luster was maintained, and the practical level was maintained.
(Triangle | delta): Powdering etc. were recognized and the film | membrane external appearance was inferior from the practical use level.
X: Discoloration, dendrite, etc. were remarkably observed, and the film appearance was extremely inferior. Or brown and brown spots and color unevenness were observed.

As is apparent from Table 1, when the compound of formula (I) where n = 1 is used as the sulfide-based compound, when it is prepared as an electroplating bath as in Example 8, the stability of the bath Both the electrodeposition and the appearance of the electrodeposition film gave good results, but when prepared as an electroless plating bath as in Comparative Example 5, satisfactory results were not obtained.

Claims (8)

Soluble salts including silver salts,
Formula (I):
(.M .R ₁ and R ₂ in the formula, n is an integer of 2 to 4 represent the same or different, optionally C ₂ ~ ₆ alkylene group C ₁ ~ ₃ alkyl or hydroxyl group is substituted, Represents hydrogen, an alkali metal, an alkaline earth metal, ammonium or an organic amine.)
General formula (II):
(Wherein, R _1, R ₂ and R ₃ are the same or different, .A representing a C ₁ ~ ₃ alkyl or hydroxyl substitutable C ₂ ~ ₆ alkylene group, B and C are the same or different , Hydroxyl group, carboxylic acid or salt thereof, sulfonic acid or salt thereof, phosphonic acid or salt thereof, or substituted or unsubstituted amine —N (R ₄ ) (R ₅ ) or —N (R ₆ ). , alkali metals, alkaline earth metals, .R ₄ and R ₅ represents an ammonium or organic amine are the same or different, represent hydrogen or C ₁ ~ ₅ alkyl, R ₆ is hydrogen or one to three hydroxyl groups compounds represented by the representative. ") the substituted C ₁ ~ ₅ alkyl group, and,
Formula (III):
_{(Wherein, R 1, R 2, R} 3 and R ₄ are the same or different, .A representing a C ₁ ~ ₃ alkyl or hydroxyl group may be substituted C ₂ ~ ₆ alkylene group, B, C and D Are the same or different and are a hydroxyl group, a carboxylic acid or a salt thereof, a sulfonic acid or a salt thereof, a phosphonic acid or a salt thereof, or a substituted or unsubstituted amine —N (R ₄ ) (R ₅ ) or —N (R ₆ ). represents. "salts are alkali metal, .R ₄ and R ₅ represents an alkali earth metal, ammonium or an organic amine are the same or different, represent hydrogen or C ₁ ~ ₅ alkyl, R ₆ is hydrogen or 1 three hydroxyl groups represents a C ₁ ~ ₅ alkyl group substituted. ") 1 or more and sulfide compound selected from the group consisting of compounds represented by,
Cyanide-free silver-based plating bath containing At least a compound of general formula (I),
The compound of general formula (I) is
Formula (IV):
And a compound represented by
Formula (V):
At least one of the compounds represented by:
The cyanide-free silver-based plating bath according to claim 1. The soluble salt further comprises a metal salt of a metal other than silver,
The metal salt is one or more metals selected from the group consisting of tin, bismuth, indium, lead, copper, zinc, nickel, gold, palladium, and platinum.
The cyanide-free silver-based plating bath according to claim 1 or 2.   The cyanide according to any one of claims 1 to 3, further comprising at least one surfactant selected from a nonionic surfactant, an anionic surfactant, a cationic surfactant, and an amphoteric surfactant. Non-containing silver plating bath.   The cyanide-free silver-based plating bath according to any one of claims 1 to 4, further comprising an antioxidant.   A plated body obtained by plating a body to be plated using the cyanide-free silver-based plating bath according to any one of claims 1 to 5.   The plated body according to claim 6, wherein the body to be plated is an electronic component having a portion made of a copper-based material. A plating method comprising a step of plating a member to be plated using the cyanide-free silver plating bath according to any one of claims 1 to 5.