JPH09143786A - Silver and silver alloy plating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a silver and silver alloy plating bath equal to a conventional plating bath using a cyanide-based compd. in a deposited film and a bath control, etc., without using the cyanide-based compd. SOLUTION: This silver plating bath contains Ag<+> ion, one or more kinds of sulfur-containing compd. and a nonionic surface active agent and does not contain cyanide-based compd. This silver alloy plating bath further contains one or more kinds of metal ion selected from a group consisting of Sn<2+> , Cu<2+> , In<3+> , Tl<+> , Zn<2+> and Bi<3+> and does not contain the cyanide-based compd.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a silver and silver alloy plating bath, and more particularly to a silver and silver alloy plating bath that does not use a cyan compound.

[0002]

2. Description of the Related Art Cyan-based baths have long been known as plating baths such as silver and silver alloy plating baths. This cyan-based noble metal plating bath is excellent in terms of the density of the deposited metal crystals, uniform electrodeposition, and ease of bath management. It is used for plating not only ornaments but also semiconductor parts and printed circuit boards. It is also widely used in.

However, since these plating baths use cyanide, which is highly toxic, the working environment,
There were many problems in terms of environmental protection and wastewater treatment.

[0004]

Therefore, it is possible to provide a silver and silver alloy plating bath that is equivalent to a conventional cyanide-based plating bath in terms of deposition film and bath management without using a cyanide-based compound. It was wanted.

[0005]

The inventors of the present invention have conducted earnest research on silver and silver alloy plating baths that do not use cyanide compounds.
If silver and silver alloy plating baths containing nonionic surfactants are added as g ⁺ ion displacement preventive agents, silver and silver alloy coatings equivalent to those obtained using cyanide plating baths can be obtained. And completed the present invention.

That is, the present invention relates to the following three components (a)-
(C) (a) Ag ⁺ ion (b) One or more kinds of sulfur-containing compounds (c) Non-ionic surfactant is contained and a silver plating bath characterized by containing no cyanide compound is provided. It is a thing.

The present invention also provides the following four components (a)-
(D) (a) Ag ⁺ ion (b) One or more sulfur-containing compounds (c) Nonionic surfactant (d) Sn ²⁺ , Cu ²⁺ , In ³⁺ , Tl ⁺ , Zn ²⁺ And a silver alloy plating bath containing one or more metal ions selected from the group consisting of Bi ³⁺ and containing no cyanide compound.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The Ag ⁺ ion which is the component (a) of the acidic silver and silver alloy plating bath of the present invention is a silver alkane sulfonate such as silver methane sulfonate or silver ethane sulfonate, or a silver isopropanol sulfonate. It can be obtained by dissolving a water-soluble silver salt such as a silver salt of an alkanol sulfonic acid such as the above, a silver oxide, a silver chloride, a silver nitrate or the like in water. Preferred water-soluble silver salts include silver alkane sulfonates and silver alkanol sulfonates.

Further, the sulfur-containing compound which is the component (b) of the present invention is a compound containing a sulfur atom in the molecule and which functions as a substitution inhibitor for Ag ^{+ in} the bath.

Examples of the sulfur-containing compound include thiourea,
Thiourea dioxide, 1-acetyl-2-thiourea, allylthiourea, ethylenethiourea, sym.-di-o-tolylthiourea, sym.-di-p-tolylthiourea, 1,3
-Bis (hydroxymethyl) thiourea, 1-phenyl-
3- (2-thiazolyl) -2-thiourea, benzylisothiourea hydrochloride, 2-malonylthiourea, S-methylisothiourea sulfate, N, N'-diphenylthiourea, trimethylthiourea, N, N'-diethylthio Urea, 1-naphthylthiourea, 1,3-bis (dimethylaminopropyl)
Thiourea compounds such as 2-thiourea and tributylthiourea; 2-mercaptobenzothiazole, dibenzothiazole disulfide, cyclohexylamine salt of 2-mercaptobenzothiazole, 2- (N, N-diethylthiocarbamoylthio) benzothiazole , 2- (4'-
Thiazole compounds such as morpholinodithio) benzothiazole; N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, N-oxydiethylene-2
-Sulfenamide compounds such as benzothiazolyl sulfenamide and N, N-dicyclohexyl-2-benzothiazolyl sulfenamide; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetrakis (2-ethylhexyl) Thiuram-based compounds such as thiuram disulfide, tetramethylthiuram monosulfide, dipentamethylene thiuram tetrasulfide; pentamethylenedithiocarbamic acid piperidine salt, pipecolyl dithiocarbamic acid pipecoline salt, sodium diethyldithiocarbamate, dithiocarbamate salts such as sodium dibutyldithiocarbamate Compounds; 4,4'-thiobis (3-
Bisphenol-based compounds such as methyl-6-tert-butylphenol); benzimidazole-based compounds such as 2-mercaptobenzimidazole and 2-mercaptomethylbenzimidazole; organic thioacid-based compounds such as dilauryl thiodipropionate; N-cyclohexylthio Anti-scorch agents such as phthalimide; Vulcanizing agents such as 4,4'-dithiomorpholine; Mastication accelerators such as o, o'-dibenzamide diphenyl disulfide; Others, 2-benzoxazole thiol, 2,5-dimercapto -1,3,4-thiadiazole, 2,5-dimercapto-1,3,4-thiadiazole dipotassium, diethylammonium diethyldithiocarbamate, sodium diethyldithiocarbamate trihydrate, thioglycol, thioglycolic acid,
Examples thereof include sulfur-containing compounds such as thiodiglycolic acid and β-thiodiglycol. These sulfur-containing compounds may be blended in one kind, but it is preferable to combine two or more kinds in combination, and it is particularly preferable to combine a plurality of sulfur-containing compounds centering on a thiourea compound.

Further, the nonionic surfactant which is the component (c) of the present invention is used for obtaining a dense and smooth plated surface with good adhesiveness, and it is satisfactory in the present invention to lack this component. No clear silver and silver alloy plating film can be obtained.

Specific preferred examples of the component (c) include those containing a compound represented by any one of the following general formulas (1) to (4) as a main component.

[0013]

Embedded image

[In the formula, R ₁ is an aliphatic alcohol having 8 to 22 carbon atoms, a phenol substituted with an alkyl group having 1 to 25 carbon atoms, and a β substituted with an alkyl group having 1 to 25 carbon atoms.
-Naphthol, alkoxylated phosphoric acid having 1 to 25 carbon atoms, sorbitan esterified with fatty acid having 8 to 22 carbon atoms or styrenated phenol (the hydrogen of the phenol nucleus is substituted with an alkyl group having 1 to 4 carbon atoms or a phenyl group) R ₂ is a carbon atom having a carbon number of 8 or less.
To 18 alkyl groups, R ₃ and R _{4 each} represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and A represents —CH ₂ CH ₂ O.
- a, B represents a _{-CH 2 CH (CH 3) O-} , m 1 and n ₁ is 0 to 30 _{integer, m 2, n 2, m} 3 and n ₃ 0
40 integers, m ₄ and n ₄ is 0-20 of integer respectively. However, m ₁ and n ₁ , m ₂ and n ₂ , m ₃ and n _3, and m ₄ and n ₄ do not become 0 at the same time, and m ₁ ~
m ₄ and n _{1 to} n ₄ mean the total number of substituents,
The positions where A and B are present are not limited]

These nonionic surfactants are all corresponding aliphatic alcohols, substituted phenols, alkyl-substituted β-naphthols, alkoxylated phosphoric acids, esterified sorbitans, styrenated phenols, ethylenediamines, monoalkylamines, It can be prepared by adding a predetermined number of moles of ethylene oxide and / or propylene oxide to an alkyl-substituted diphenol, but it is also easily available as a commercial product.

As an example of a commercially available product, the one represented by the above-mentioned formula (1) is Pullurafak LF401 (BASF
(Manufactured by Asahi Denka Kogyo Co., Ltd.) and the like, and those represented by formula (3) are those represented by formula (2).
Examples of the compound represented by the formula (4) such as 207 (manufactured by NOF Corporation) include Liponox NC-100 (manufactured by Lion Corporation).

Furthermore, the component (d) of the present invention is S
An ion of a metal selected from n ²⁺ , Cu ²⁺ , In ³⁺ , Tl ⁺ , Zn ²⁺ and Bi ³⁺ (hereinafter, these metals may be referred to as “alloy component”), It is obtained by dissolving a water-soluble salt in water.

Among the water-insoluble salts of the alloy components, examples of tin salts include tin methanesulfonate, tin ethanesulfonate, tin isopropanolsulfonate, stannous chloride, stannous oxide, stannic oxide, and sulfuric acid. Examples of the copper salt such as stannous tin are
Copper methanesulfonate, copper ethanesulfonate, copper isopropanolsulfonate, copper sulfate, cupric oxide, copper nitrate, cuprous chloride, cupric chloride, copper carbonate, etc. Examples of the thallium salt include indium acid salt, indium ethanesulfonate, indium isopropanol sulfonate, and indium, and examples of thallium salts include thallium methanesulfonate, thallium ethanesulfonate, thallium isopropanolsulfonate, thallium oxide, thallium sulfate, thallium chloride, and thallium chloride. , Thallium acetate, etc., examples of zinc salts include zinc methanesulfonate, zinc ethanesulfonate, zinc isopropanolsulfonate, zinc chloride, zinc nitrate, zinc carbonate, zinc sulfate, etc., examples of bismuth salts include methane. Bismuth sulfonate, bis ethane sulfonate Scan, isopropanol sulfonic acid bismuth, bismuth oxide, bismuth nitrate, and the like, respectively.

The silver and silver alloy baths of the present invention are prepared by adding the components (a) to (c) or (a) to (d) in an acidic bath according to a conventional method. Specifically, after adding the sulfur-containing compound, which is the component (b), to an aqueous solution acidified with sulfuric acid, alkane sulfonic acid, alkanol sulfonic acid or the like and sufficiently dissolving it,
It is prepared by adding the water-soluble silver salt and the water-soluble salt of the alloy component, and further adding the nonionic surfactant as the component (c).

In the silver and silver alloy baths of the present invention, it is preferable to use alkane sulfonic acid and alkanol sulfonic acid because they not only make the bath properties acidic but also keep the metal ions in the bath stable. . Specifically, it is preferable to use methanesulfonic acid, ethanesulfonic acid, or the like.

When the water-soluble tin salt or the water-soluble salt of the alloy component is an alkane sulfonate or an alkanol sulfonate, these acids may be the same as or different from the acid group of those salts. Or two or more kinds may be used in combination. The concentration of alkanesulfonic acid and alkanolsulfonic acid in the bath is about 5 as its ion concentration.
~ 300 g / l is suitable.

The total metal ion concentration in the silver and silver alloy bath of the present invention is suitably about 0.5 to 240 g / l. Further, the amounts of the component (a) and the component (d) in the silver alloy bath must be adjusted according to the target alloy composition, but the component (a) is generally 5 to 20 as Ag ^+.
It is preferably about 0 g / l, and the component (d) is preferably about 0.1 to 40 g / l, although it varies depending on the type of alloy component ions. (B)
Although the amount of the component varies depending on the concentration of the component (a), it is generally about 0.01 to 40 g / l, and preferably about 0.1 to 20 g / l. Furthermore, the amount of component (c) is
The amount is sufficient to obtain a dense and smooth plated surface with good adhesion and is generally about 0.5 to 30 g / l.

In the silver and silver alloy plating bath of the present invention, in addition to the above-mentioned components, a brightening agent, an antioxidant, a wetting agent and the like can be added, if necessary, within a range not impairing the effects of the present invention. .

When Sn ²⁺ is used, a hydroxyphenyl compound such as phenol, catechol, resorcin, hydroquinone, pyrogallol, L-ascorbic acid, sorbitol or the like can be used as an antioxidant for tin. .

When plating is performed using the acidic silver and silver alloy bath of the present invention thus obtained, for example, the bath temperature of the plating bath is about 10 to 60 ° C., preferably about 20 to 30 ° C.
The cathode current density may be about 0.01 to 100 A / dm ² , and preferably about 0.1 to 10 A / dm ² . In addition, an insoluble electrode or the like can be used as the anode.

The above-mentioned silver plating or silver alloy plating film obtained from the acidic silver and silver alloy plating bath has the same degree of compactness as the silver or silver alloy plating film obtained in the conventional cyan plating bath. It can be used as a plating bath for electrical component terminals and printed wiring boards.

[0027]

The following examples, comparative examples and test examples are given.
The present invention will be described, but the present invention is not limited to these examples.

Example 1 A silver plating bath having the following composition was prepared by a conventional method. (Composition) Silver (I) methanesulfonate 10 g / l Methanesulfonic acid (free acid) 100 g / l Allylthiourea 20 g / l 2-Mercaptobenzimidazole 1 g / l Nonylphenol ethoxylate 10 g / l Ethylene Oxide 12 mol adduct

Example 2 A silver alloy plating bath having the following composition was prepared by a conventional method. (Composition) Silver (I) methanesulfonate 1 g / l Tin (II) methanesulfonate 40 g / l Methanesulfonic acid (free acid) 120 g / l Thiourea 5 g / l N, N'-diethylthiourea 5 g / l 8 g / l laurylamine 8 g / l ethylene oxide 7 mol adduct catechol 1 g / l

Example 3 A silver alloy plating bath having the following composition was prepared by a conventional method. (Composition) Silver (I) methanesulfonate 1 g / l Tin (II) methanesulfonate 30 g / l Bismuth (II) methanesulfonate 3 g / l Methanesulfonic acid (free acid) 80 g / l Thioglycol Acid 5 g / l 2-benzoxazole thiol 3 g / l β-naphthol 4 g / l ethylene oxide 8 mol adduct

Example 4 A silver alloy plating bath having the following composition was prepared by a conventional method. (Composition) Silver ethanesulfonate (I) 0.5 g / l Tin ethanesulfonate (II) 20 g / l Zinc ethanesulfonate (I) 40 g / l Ethanesulfonate (free acid) 100 g / l 2-Mercaptobenzothiazole 2 g / l Sodium diethylthiocarbamate 0.5 g / l Ethylenediamine ethylene oxide 5 g / l 48 mol, Propylene oxide 44 mol adduct Octylphenol ethoxylate 5 g / l Ethylene oxide 10 mol addition Stuff

Example 5 A silver alloy plating bath having the following composition was prepared by a conventional method. (Composition) Silver (I) methanesulfonate 1 g / l Tin (II) methanesulfonate 20 g / l Copper (II) methanesulfonate 20 g / l Methanesulfonic acid (free acid) 80 g / l β- Thiodiglycol 4 g / l N, N'-diethyl 4 g / l sodium dithiocarbamate Ethylene oxide 5 g / l 15 mol adduct of lauryl ether

Example 6 A silver alloy plating bath having the following composition was prepared by a conventional method. (Composition) Silver (I) methanesulfonate 0.5 g / l Tin (II) methanesulfonate 10 g / l Indium (III) methanesulfonate 1 g / l Methanesulfonic acid (free acid) 100 g / l 2-mercaptobenzimidazole 0.5 g / l diethyldithiocarbamic acid 2 g / l diethylammonium dodecylamine ethylene oxide 10 g / l 8 mol adduct octylphenol ethoxylate 2 g / l ethylene oxide 10 mol adduct

Comparative Example 1 A silver plating bath having the following composition was prepared by a conventional method. (Composition) Silver (I) methanesulfonate 10 g / l Methanesulfonic acid (free acid) 100 g / l Nonylphenol ethoxylate 10 g / l Ethylene oxide 12 mol adduct

Comparative Example 2 A silver alloy plating bath having the following composition was prepared by a conventional method. (Composition) Silver (I) methanesulfonate 1 g / l Tin (II) methanesulfonate 40 g / l Methanesulfonic acid (free acid) 120 g / l 8 g / l laurylamine 8 g / l 7-mol ethylene oxide adduct Catechol 1 g / l

Comparative Example 3 A silver alloy plating bath having the following composition was prepared by a conventional method. (Composition) Silver (I) methanesulfonate 1 g / l Tin (II) methanesulfonate 30 g / l Bismuth (II) methanesulfonate 3 g / l Methanesulfonate (free acid) 80 g / l β- Naphthol 4 g / l ethylene oxide 8 mol adduct

Test Example 1 Using the plating baths of the above Examples 1 to 6 and Comparative Examples 1 to 3, a 30 mm × 10 mm copper plate was immersed for 5 minutes to compare the turbidity of the bath and the substitution of silver. Table 1 shows the results.

(Results) Table 1 ──────────────────────────── Plating bath Bath turbidity Silver substitution ───── ─────────────────────── Example 1 No No Example 2 No No Example 3 No No Example 4 No No Example 5 No No Example 6 No No ──────────────────────────── Ratio Comparison Example 1 Yes Yes Ratio Example 2 Yes Yes Ratio Comparative Example 3 Yes Yes ────────────────────────────

Test Example 2 In a plating bath having the following composition, a silver alloy plating bath was prepared in which the combination of two kinds of the sulfur-containing compounds A and B was changed, and a 30 mm × 10 mm copper plate was immersed therein for 5 minutes. , Bath turbidity and silver displacement were compared. The results are shown in Tables 2-7.

(Composition) Silver (I) methanesulfonate 1 g / l Tin (II) methanesulfonate 40 g / l Methanesulfonic acid (free acid) 120 g / l Sulfur-containing compound A X g / l Sulfur-containing Compound B Y g / l Laurylamine 8 g / l Ethylene oxide 7 mol adduct Catechol 1 g / l

1. Thiourea-based combination: (1) Sulfur-containing compound A is thiourea, X = 5 is constant; Table 2 ──────────────────── ─────────────── Sulfur-containing compound B (Y = 5) Bath turbidity Silver substitution ───────────────────── ──────────── Allyl thiourea No No Ethylene thiourea No No No thiourea dioxide No No S-methylisothiourea sulfate No No Trimethylthiourea No No (thiourea only) Yes No ───── ────────────────────────────

(2) Sulfur-containing compound A is N, N'-diethylthiourea, X = 5 is constant; Table 3 ─────────────────────── ─────────── Sulfur-containing compound B (Y = 5) Bath turbidity Silver substitution ──────────────────────── ───────── Allylthiourea No No Ethylenethiourea No No Thiourea dioxide No No S-Methylisothiourea Sulfate No No Trimethylthiourea No No (N, N'-diethylthiourea only) Yes No ─── ──────────────────────────────

2. Combination of thiourea type and thiazole type: (1) Sulfur-containing compound A is S-methylisothiourea sulfate, and X = 5 is constant; Table 4 ───────────── ───────────────────── Sulfur-containing compound B (Y = 1) Bath turbidity Silver substitution ────────────── ─────────────────── 2-Mercaptobenzothiazole None Dibenzothiazyl disulfide None None 2-Mercaptobenzothiazole None None Cyclohexylamine salt 2- (N, N ' -Diethylthio None None Carbamoylthio) benzothiazole 2- (4'-morpholinodithio) None None Benzothiazole (S-methylisothiourea sulfate only) Yes No ────────────────── ────────────────

(2) Sulfur-containing compound A is 2-mercaptobenzothiazole, X = 1 is constant; Table 5 ───────────────────────── ───────── Sulfur-containing compound B (Y = 5) Bath turbidity Silver substitution ─────────────────────────── ─────── 1-Acetyl-2-thiourea No No benzylisothiourea hydrochloride No No 2-malonylthiourea No No 1-naphthylthiourea No No Tributylthiourea No No (2-mercaptobenzothiazole only) Yes None ──────────────────────────────────

3. Combination of thiourea system and other sulfur-containing compound: (1) Sulfur-containing compound A is N, N'-diphenylthiourea, X = 5 is constant; Table 6 ──────── ────────────────────────── Sulfur-containing compounds B (Y = 1) Bath turbidity Silver substitution ───────── ──────────────────────── 2-Benzoxazole Thiol None None Diethyldithiocarbamate None None Diethylammonium Diethyldithiocarbamate None None Trihydrate Thio Glycolic acid No No Thiodiglycolic acid No No (N, N'-diphenylthiourea only) Yes No ──────────────────────────── ──────

(2) Sulfur-containing compound A is sodium diethyldithiocarbamate trihydrate, X = 1 is constant; Table 7 ────────────────────── ──────────── Sulfur-containing compound B (Y = 5) Bath turbidity Silver substitution ─────────────────────── ────────── 1-Acetyl-2-thiourea No No benzylisothiourea hydrochloride No No 2-malonylthiourea No No 1-naphthylthiourea No No Tributylthiourea No No (sodium diethyldithiocarbamate Yes Non-trihydrate only) ─────────────────────────────────

Test Example 3 Using the plating baths obtained in Examples 1 to 6, a 30 mm × 10 mm copper plate was plated under the following conditions.

(Plating conditions) Cathode current density 4 A / dm ² bath temperature 25 ° C. agitation gentle stirrer agitation membrane pressure 5 μm

The plated copper plates processed using the plating baths of Examples 1 to 6 all had a plating film having uniform and fine crystals.

[0050]

The silver and silver alloy coatings obtained by the silver and silver alloy plating baths of the present invention have the same degree of compactness as the silver or silver alloy plating coatings obtained by conventional cyanide-based plating baths. . Since the silver and silver alloy plating bath of the present invention does not contain a cyanide compound that adversely affects the human body, it is advantageous in terms of safety and pollution prevention. that's all

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshihiko Yada 1-1-6 Yoshiyukizaka, Fujisawa City, Kanagawa Prefecture

Claims (5)

[Claims] 1. One or more of the following three components (a) to (c) (a) Ag ⁺ ion (b) sulfur-containing compound (c) nonionic surfactant, and cyan compound A silver plating bath characterized by the absence thereof. 2. One or more of the following four components (a) to (d) (a) Ag ⁺ ion (b) sulfur-containing compound (c) nonionic surfactant (d) Sn ²⁺ , Cu ² A silver alloy plating bath containing one or more metal ions selected from the group consisting of ⁺ , In ³⁺ , Tl ⁺ , Zn ²⁺ and Bi ³⁺ and containing no cyanide compound. . 3. The sulfur-containing compound is a thiourea compound,
The compound selected from the group consisting of thiazole compounds, sulfenamide compounds, thiuram compounds, dithiocarbamate compounds, bisphenol compounds, benzimidazole compounds and organic thioacid compounds. The plating bath according to item 2. 4. The plating bath according to claim 1, further containing at least one kind of alkane sulfonate ion or alkanol sulfonate ion. 5. The nonionic surfactant is represented by the following formula (1):
(4) [In the formula, R ₁ is an aliphatic alcohol having 8 to 22 carbon atoms,
A phenol substituted with an alkyl group having 1 to 25 carbon atoms,
Β-naphthol substituted with alkyl having 1 to 25 carbons, alkoxylated phosphoric acid having 1 to 25 carbons, 8 carbons
Obtained by removing hydrogen atoms of hydroxyl groups from sorbitan or styrenated phenol esterified with ~ 22 fatty acid (the hydrogen of the phenol nucleus may be substituted with an alkyl group having 1 to 4 carbon atoms or a phenyl group) Represents a residue or a hydrogen atom, R ₂ is an alkyl group having 8 to 18 carbon atoms, R ₃ and R ₄ are hydrogen atoms or 1 to 5 carbon atoms
Represents an alkyl group of, A is —CH ₂ CH ₂ O—, and B is —
CH ₂ CH (CH ₃ ) O—, wherein m ₁ and n ₁ are 0 to 3
An integer of 0, m ₂ , n ₂ , m ₃ and n ₃ are integers of 0 to 40,
m ₄ and n ₄ each represent an integer of 0-20. However, m ₁ and n ₁ , m ₂ and n ₂ , m ₃ and n ₃ and m ₄ and n ₄ do not become 0 at the same time, and m _{1 to} m ₄ and n ₁
To n ₄ mean the total number of substituents, and the positions where A and B are present are not limited], and the plating bath according to claim 1 or 2.