JP3419995B2 - Electroless tin-silver alloy plating bath - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroless tin-silver alloy plating bath, and more particularly to a non-cyan complex plating agent for obtaining a deposit having a smooth and good adhesion from a bath stabilized with a non-cyan complexing agent. Cyan-based electroless tin-silver alloy plating bath.

[0002]

2. Description of the Related Art Joining with a solder containing tin-lead as a basic composition is widely performed as an indispensable technique in the electronic industry. In order to perform soldering quickly and reliably, it is necessary to apply a film with good solderability to the parts to be soldered in advance.As this solderability film, a tin-lead alloy plating film is generally used. It's being used. However, in recent years, there is concern about the effects of lead on health and the environment, and the idea of controlling tin-lead solder containing harmful lead is rapidly spreading. No lead-free solder that can replace tin-lead solder has been established so far, and research and development is being conducted mainly in Japan, the US, and Europe. Binary or multi-component alloys of tin and silver, bismuth, copper, indium, antimony, zinc, etc. are listed as possible alternatives to tin-lead solders, and tin-silver alloys are also promising alternatives to tin-lead solders. It is one of the candidates. In response to alternative solder, it is necessary to change the plating film for soldering to one that does not contain lead. The tin-lead alloy plating film is obtained not only by electroplating but also by electroless plating depending on the industrially targeted parts. As for tin-silver alloy plating, no report has been found so far on the method of obtaining by electroless plating.

[0003]

In electroplating, in 1971, Matsushita used a cyan-pyrophosphoric acid mixed bath (Matsushita: Metal Surface Technology 22,60 (1971)), and in 1983, Kubota et al. Pyrophosphate bath as a bath (Kubota et al .: Metal Surface Technology 34, 37 (198
A tin-silver alloy coating is obtained from 3)). These were developed and researched mainly for the purpose of replacing silver plating or improving the performance of silver plating. Corresponding to the idea of controlling tin-lead solder containing harmful lead, as alternative solders are being investigated, the plating film for soldering is also being investigated, and tin-silver alloy electroplating bath Has begun to be researched again, and recently, potassium stannate-silver nitrate bath by Ise et al. (Ise et al .: Surface Technology Association 93rd Lecture Meeting Preliminary Collection 205 (1996)), and Arai et al. Pyrophosphate-iodide bath. (Arai et al .: The Surface Technology Association 93rd Lecture Meeting Preliminary Collection 195 (1996)) is reported. Silver forms insoluble salts with chloride and sulfate ions. In addition, even if dissolved in the form of a water-soluble salt such as sulfate or sulfonate, it will form an insoluble salt in the presence of ions such as chloride and sulfate, and is unstable in the form of simple ions. , It is easy to generate black metallic silver upon exposure to light. Further, since the potential is higher than that of tin, silver is preferentially precipitated in co-deposition with tin, resulting in an alloy having a high silver content. Due to such various problems, no report has been found so far on a method of obtaining tin-silver alloy plating by electroless plating.

[0004]

Means for Solving the Problems The inventor of the present invention stably dissolves silver ions in a bath in a liquid consisting of divalent tin ions and monovalent silver ions, and suppresses preferential silver precipitation. The addition of a non-cyan complexing agent with a large stability constant enables the electroless tin-silver alloy plating with a low silver content in the film, which is a problem in terms of environment, hygiene and pollution.
By providing a non-cyan electroless tin-silver alloy plating bath for obtaining a non-lead solderable plating film which is indispensable for replacing lead solder, the present inventors have solved the alternative solder problem.

SUMMARY OF THE INVENTION That is, the present invention, (I) a non-cyanide divalent tin and monovalent non-cyanide compounds of silver, and (II) to maintain the monovalent silver compounds stably in the liquid A necessary amount of (a) thiourea and a mono- or di-alkyl thiourea having an alkyl group having 1 to 3 carbon atoms, (b) thiosulfate, (c)
Non-cyanide tin-silver alloy containing one or more compounds selected from iodine compounds, (d) bromine compounds, (e) succinimide, and (f) mercaptosuccinic acid or salts thereof as essential components. An electroless plating solution is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the non-cyan type electroless tin-silver alloy plating solution of the present invention, any known divalent tin compound can be used, and examples thereof include tin oxide, tin sulfate and tin sulfate.
Tin chloride, tin borofluoride, tin fluorosilicate, tin sulfamate, tin oxalate, tin tartrate, tin gluconate, tin sulfosuccinate, tin pyrophosphate, 1-hydroxyethane-1,1
-Tin bisphosphonate, tin tripolyphosphate, or a tin salt of an aliphatic sulfonic acid represented by the following general formulas (i) and (ii), or an aromatic sulfonic acid represented by the following general formula (iii) A tin salt or the like can be used alone or in an appropriate mixture.

(I) General formula (X ₁ ) _n —R—SO ₃ H [wherein R represents a C _{1 to} C ₅ alkyl group, X ₁ is hydrogen, a hydroxyl group, an alkyl group, an aryl group or an alkyl group. Represents an aryl group, a carboxyl group or a sulfonic acid group, and may be at any position of the alkyl group, n is 0 to 3
Is an integer. ] And (ii) general formula

[Chemical 1] [Here, R ₁ represents a C ₁ -C ₃ alkyl group, and R 1
₂ represents a C ₁ -C ₃ alkylene group, the hydroxyl group may be located at any position of the alkylene group, X represents halogen of chlorine and fluorine, and chlorine or fluorine substituted with hydrogen of the alkyl group and alkylene group. The number of substitutions of 1 to 1 is saturated substitution of all hydrogens coordinated to an alkyl group or an alkylene group, the number of substituted halogen species is one or two, and the chlorine or fluorine substituent is optional. May be in the position. Y represents hydrogen or a sulfonic acid group, and the substitution number of the sulfonic acid group represented by Y is in the range of 0 to 2. ] The tin salt of an aliphatic sulfonic acid represented by
(iii) general formula

[Chemical 2] [Wherein X ₂ represents a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, an aldehyde group, a carboxyl group, a nitro group, a mercapto group, a sulfonic acid group or an amino group, or two X ₂ are a benzene ring. Together, they can form a naphthalene ring, and m is an integer of 0-3. ] The tin salt of aromatic sulfonic acid represented by these.

Examples of these tin salts of organic sulfonic acids of the general formulas (i) to (iii) are methanesulfonic acid, methanedisulfonic acid, methanetrisulfonic acid, trifluoromethanesulfonic acid, ethanesulfonic acid, propanesulfonic acid. Two
-Propanesulfonic acid, butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid, 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 2
-Hydroxypentanesulfonic acid, 1-carboxyethanesulfonic acid, 1,3-propanedisulfonic acid, arylsulfonic acid, 2-sulfoacetic acid, 2- or 3-sulfopropionic acid, sulfosuccinic acid, sulfomaleic acid, sulfofumaric acid, Benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, nitrobenzenesulfonic acid,
Sulfobenzoic acid, sulfosalicylic acid, benzaldehyde sulfonic acid, phenol sulfonic acid, phenol-2,
It is a tin salt such as 4-disulfonic acid. In particular, tin methanesulfonate, tin methanedisulfonate, tin sulfosuccinate,
Tin trifluoromethanesulfonate, tin p-toluenesulfonate and tin sulfobenzoate are preferred.

The amount of the tin compound used is not particularly limited in both the upper and lower limits, but since the precipitation rate decreases as the concentration decreases, approximately 1 g / L is required, and an extremely high concentration will stabilize the bath. 50g / L because it reduces the
It is not preferable to exceed. Therefore, the tin content is 1 to
About 50 g / L is suitable, and preferably 5 to 30 g / L.
It is about L.

As the monovalent silver compound, any of known compounds can be used, and examples thereof include silver oxide, silver nitrate, silver sulfate, silver chloride, silver bromide, silver iodide, silver benzoate, silver sulfamate and citric acid. Acid silver, silver lactate, silver mercaptosuccinate, silver phosphate, silver trifluoroacetate, silver pyrophosphate, silver 1-hydroxyethane-1,1-bisphosphonate, or the following general formulas (i) and (ii) The silver salt of an aliphatic sulfonic acid represented by the above, or the silver salt of an aromatic sulfonic acid represented by the following general formula (iii) and the like can be used alone or in an appropriate mixture. The upper and lower limits of the amount of silver compound used are not particularly limited, but when the concentration is extremely low, it is difficult to control the bath, so about 0.05 g / L is necessary, and A high concentration will increase the silver content of the precipitate, so approximately 10 g
It is not preferable to exceed / L. Therefore, the silver content is suitably about 0.05 to 10 g / L, preferably about 0.1 to 5 g / L. However, when a tin-silver alloy plating film having a high silver content is to be obtained, the silver concentration is not limited to this, and the silver concentration can be about 50 g / L.

(I) General formula (X ₁ ) _n —R—SO ₃ H [wherein R represents a C _{1 to} C ₅ alkyl group, X ₁
Represents hydrogen, a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, a carboxyl group or a sulfonic acid group,
It may be at any position of the alkyl group, and n is 0 to
It is an integer of 3. ] And (ii) general formula

[Chemical 3] [Here, R ₁ represents a C ₁ -C ₃ alkyl group, and R 1
₂ represents a C ₁ -C ₃ alkylene group, the hydroxyl group may be located at any position of the alkylene group, X represents halogen of chlorine and fluorine, and chlorine or fluorine substituted with hydrogen of the alkyl group and alkylene group. The number of substitutions of 1 to 1 is saturated substitution of all hydrogens coordinated to an alkyl group or an alkylene group, the number of substituted halogen species is one or two, and the chlorine or fluorine substituent is optional. May be in the position. Y represents hydrogen or a sulfonic acid group, and the substitution number of the sulfonic acid group represented by Y is in the range of 0 to 2. ] A silver salt of an aliphatic sulfonic acid represented by
(iii) general formula

[Chemical 4] [Wherein X ₂ represents a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, an aldehyde group, a carboxyl group, a nitro group, a mercapto group, a sulfonic acid group or an amino group, or two X ₂ are a benzene ring. Together, they can form a naphthalene ring, and m is an integer of 0-3. ] The tin salt of aromatic sulfonic acid represented by these. Examples of the sulfonic acid of these organic sulfonic acid silver salts may be the same as those described for the tin salt. In particular, silver methanesulfonate,
Silver methanedisulfonate, silver sulfosuccinate, silver trifluoromethanesulfonate, silver p-toluenesulfonate and silver sulfobenzoate are preferred.

Known compounds can be used as thiourea or its derivative or thiosulfuric acid (and its salts) or iodine compound and bromine compound, which are added to keep the monovalent silver compound stable in the liquid. The urea derivative includes dimethylthiourea, and the iodine compound includes potassium iodide and sodium iodide, but silver iodide can also be used. The amount to be used should be adjusted depending on the silver concentration in the plating bath, and the upper and lower limits should not be limited, but since the bath becomes unstable as the ratio of complexing agent to silver decreases, it is generally It is necessary to have about 5 times the molar amount of silver, and when the concentration of the complexing agent is extremely high, phenomena such as an increase in the viscosity of the bath appear. Should be. Therefore, the amount of the silver complexing agent used is 5 per mol of silver ion.
~ 400 times the amount is added, preferably 10-300 times the amount. Although it is technically possible to perform plating by using thiocyanic acid or a salt thereof as a substitute for the complexing agent, it is not preferable in terms of pollution prevention and environmental protection.

Further, in the plating bath of the present invention, in order to keep the divalent tin compound stable in the aqueous solution, the following (a) to
One or more of the complexing agents selected from (j) can be added. (A) an aliphatic dicarboxylic acid having 0 to 3 carbon atoms in the alkyl group, (b) an aliphatic hydroxymonocarboxylic acid having 1 to 2 carbon atoms in the alkyl group, and (c) 1 to 3 carbon atoms in the alkyl group
3 aliphatic hydroxypolycarboxylic acids, (d) monosaccharides and partially oxidized polyhydroxycarboxylic acids and their cyclic ester compounds, (e) aliphatic mono-alkyl groups having 1 to 4 carbon atoms Alternatively, di-amino, mono- or di-carboxylic acid, (f) an aliphatic monomercaptomonocarboxylic acid having an alkyl group having 2 to 3 carbon atoms, an aliphatic monomercaptodicarboxylic acid, and an aliphatic monomercaptomonoaminomonocarboxylic acid , (G) an aliphatic monosulfomonocarboxylic acid and an aliphatic monosulfodicarboxylic acid having 2 to 3 carbon atoms in the alkyl group, (h) the following aminecarboxylic acid: ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid (IDA) , Nitrilotriacetic acid (NTA),
Diethylenetriamine pentaacetic acid (DTPA), triethylenetetramine hexaacetic acid (TTHA), ethylenedioxybis (ethylamine) -N, N, N ', N'-tetraacetic acid, glycol ethylenediaminetetraacetic acid (G
EDTA) and N-hydroxyethylethylenediaminetetraacetic acid (HEEDTA), (i)
Condensed phosphoric acid and (j) hydroxyalkane bisphosphonic acid having 1 to 3 carbon atoms of alkane.

Of the complexing agents (a) to (j), preferred examples are (a) aliphatic dicarboxylic acid: oxalic acid, malonic acid and succinic acid, and (b) aliphatic dicarboxylic acid. As the hydroxymonocarboxylic acid, glycolic acid,
(C) Aliphatic hydroxypolycarboxylic acids include tartaric acid and citric acid, (d) monosaccharides and partially oxidized polyhydroxycarboxylic acids, and cyclic ester compounds thereof include ascorbic acid and gluconic acid. Glucoheptonic acid, δ-gluconolactone, etc., (e) glycine as the aliphatic aminocarboxylic acid, (f) mercaptosuccinic acid as the aliphatic mercaptocarboxylic acid, (g) aliphatic sulfocarboxylic acid For example, sulfosuccinic acid, (h) aminecarboxylic acid, ethylenediaminetetraacetic acid, iminodiacetic acid, nitrilotriacetic acid, (i) condensed phosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, (j) hydroxyalkanebisphosphone Examples of the acid include 1-hydroxyethane-1,1-bisphosphonic acid. That. The amount used is appropriately selected according to the type of the complexing agent, but the amount used should be adjusted depending on the tin concentration and pH in the plating bath, and neither upper nor lower limit is particularly limited. However, since the bath becomes unstable with a decrease in the ratio of the complexing agent to tin, a molar number approximately equal to that of tin is necessary. When the concentration of the complexing agent is extremely high, the viscosity of the bath becomes high. Since a phenomenon appears, it should be suppressed to about 50 times the mole of tin. Therefore, the amount of the tin complexing agent used is 1 to 50 times the molar amount of tin ions, preferably 2 to 3 times.
Add 0 volumes.

The pH to be used is appropriately selected according to the type of each complexing agent, and the preferred pH range of a typical complexing agent is as follows. Oxalic acid: pH 5 to 5.5 Malonic acid: pH 1 to 2.5 Succinic acid: pH <1 to 2 Glycolic acid: pH <1 to 1 Citric acid: pH 1 to 6 Tartaric acid: pH 1 to 9 Gluconic acid: pH 1 to 14 <δ -Gluconolactone: pH 1-13 Glycine: pH 1.5-2.5 Ethylenediaminetetraacetic acid: pH <1-7 Pyrophosphoric acid: pH <1-9 Tripolyphosphoric acid: pH <1-8 1-Hydroxyethane-1,1 -Diphosphonic acid: pH 1-10

In the plating bath of the present invention, a surfactant can be added in order to obtain finer plated metal particles and a smooth plated film. As the surfactant, one or more known surfactants can be added and used. The surfactants added include nonionic surfactants, cationic surfactants, amphoteric surfactants, and anionic surfactants, and specifically, polyoxyethylene nonylphenyl ether, polyoxyethylene laurylphenyl. Polyoxyalkylene alkyl ether-based surfactants such as ethers, polyoxyalkylene alkyl amide ether-based surfactants such as polyoxyethylene stearyl amide ethers, polyoxyalkylene alkyl amine ether-based surfactants such as polyoxyethylene oleyl amine ethers, Polyoxyethylene propylene block polymer surfactant, alkylamine, alkyltrimethylamine, alkyldimethylamine, alkylpyridinium, alkyloxazoline, alkylimidazoline,
Examples thereof include salts such as alkylaminotriazole and aminodioxane.

More specifically, preferred ones among them are: (A) general formula:

[Chemical 5] [Here, R represents an alkyl group (C ₁ -C ₂₅ ),
Represents hydrogen or an alkali metal. ] A naphthalene sulfonic acid-based surfactant represented by, for example, sodium salt of alkyl (propyl, butyl ...) Naphthalene sulfonic acid, etc. (B) General formula: HO- (A) _m- (B) _n -H [Where A and B are —CH ₂ —CH ₂ —O— or —C
_{H 2 -C (CH 3) H} -O- and represented, their existing position is not limited, m and n is an integer of 0 to 40.
However, the sum of m and n is in the range of 1 to 40. ]
A polyoxyalkylene-based surfactant represented by, for example, ethylene glycol, polyethylene glycol such as di- (tri-, tetra-, octa ...) Ethylene glycol, propylene glycol, di- (tri-, tetra-, Octa ...) Polypropylene glycol such as propylene glycol, condensate of ethylene oxide and propylene oxide, and the like, (C) General formula: RD- (A) _m- (B) _n -H [where A and B is -CH ₂ -CH ₂ -O- or -C
H ₂ —C (CH ₃ ) H—O— is represented, and the position where they are present is not limited, and m and n represent an integer of 0-40. However, the sum of m and n is in the range of 1 to 40. R is an alkyl group having 1 to 22 carbon atoms or 1 to 2 carbon atoms
Represents sorbitan esterified with the fatty acid of 5. D
Represents -O- or -COO-. ] Polyoxyalkylene alkyl ether (or ester) represented by
-Based surfactants such as alkyl (eg oleyl, cetyl, stearyl, lauryl ...
·) Ethers or fatty acid esters, sorbitan esters and the like, (D) the general _{formula: R-O- (A) m} - (B) n -H [ wherein, A and B are -CH ₂ -CH ₂ -O- or -C
H ₂ —C (CH ₃ ) H—O— is represented, and the position where they are present is not limited, and m and n represent an integer of 0-40. However, the sum of m and n is in the range of 1 to 40. R represents a phenyl group or a phenyl group substituted with an alkyl group (C ₁ -C ₂₅ ). ] A polyoxyalkylene phenyl (or alkyl phenyl) ether-based surfactant represented by, for example, a phenyl ether such as polyethylene glycol or polypropylene glycol of the above (B) or an alkyl-substituted phenyl ether, etc., (E) a general formula:

[Chemical 6] [Where A and B are —CH ₂ —CH ₂ —O— or —C
_{H 2 -C (CH 3) H} -O- and represented, their existing position is not limited, m and n is an integer of 0 to 40.
However, the sum of m and n is in the range of 1 to 40. R
Represents hydrogen or an alkyl group (C ₁ -C ₂₅ ). ] A polyoxyalkylene naphthyl (or alkyl naphthyl) ether-based surfactant represented by, for example, ethylene oxide and / or propylene oxide adduct of naphthol or alkyl naphthol, etc. (F) General formula:

[Chemical 7] [Where A and B are —CH ₂ —CH ₂ —O— or —C
_{H 2 -C (CH 3) H} -O- and represented, their existing position is not limited, m and n is an integer of 0 to 40.
However, the sum of m and n is in the range of 1 to 40. R
_a , R _b and R _c are each independently hydrogen, a phenyl group,
Alkyl group (C ₁ ~C ₄₎ or -CH (CH ₃₎ represent -.phi. Provided that at least one is assumed to be a phenyl group or -CH (CH ₃₎ -φ. ] A polyoxyalkylene styrenated phenyl ether-based surfactant represented by, for example, ethylene oxide and / or propylene oxide adduct of styrenated phenol or α-methylstyrenated phenol, etc. (G) General formula:

[Chemical 8] [Where A and B are —CH ₂ —CH ₂ —O— or —C
H ₂ —C (CH ₃ ) H—O— is represented, and their positions are not limited. R _c1 and R _c2 each independently represent hydrogen, a phenyl group or an alkyl group (C _{1 to} C ₄ ), R _d and R _e each independently represent hydrogen or —CH ₃ , and m ₁ and m ₂ , N ₁ and n ₂ are each independently 0 to
Represents an integer of 40. However, m ₁ and n ₁ , and further m
The sum of ₂ and n ₂ is in the range 1-40. ] The polyoxyalkylene styrenated phenyl ether represented by the formula [1] to a phenyl group to which a polyoxyalkylene chain is further added, for example, bisphenol A bis (ethylene oxide and / or propylene oxide adduct), etc. (H ) General formula:

[Chemical 9] [Where R _a and R _b are hydrogen or an alkyl group (C
_{1 to} C ₂₅ ) and may be the same or different. A and B are -CH ₂ -CH ₂ -O- or -CH ₂ -C (CH
₃ ) Represents H-O-, and the position where they are present is not limited. m ₁ , m ₂ , n ₁ and n ₂ are each independently 0 to 40
Represents the integer. However, the sum of m ₁ and n ₁ , and further the sum of m ₂ and n ₂ is within the range of 1 to 40. M represents hydrogen or an alkali metal. ] A phosphoric acid ester-based surfactant represented by, for example, sodium salt of alkylphosphoric acid, sodium salt of polyoxyethylenated and / or polyoxypropyleneized phosphoric acid, etc. (I) General formula:

[Chemical 10] [Wherein R represents an alkyl group (C _{1 to} C ₃₀ ), alkenyl (C _{1 to} C ₃₀ ), or an acyl group (C _{1 to} C ₃₀ ),
A and B are -CH ₂ -CH ₂ -O- or -CH ₂ -C
(CH ₃₎ H-O- and represented, their existing position is not limited. m ₁ , m ₂ , n ₁ and n ₂ are independently 0
Represents an integer of ~ 6. However, m ₁ and n ₁ , and further m ₂
And n ₂ is in the range 1 to 6. CH ₂ -C
H (CH ₃₎ number of moles of added -O will not larger than molar number of addition of CH ₂ -CH-O. ] A polyoxyalkylene alkyl (or alkenyl) amine (or amide) -based surfactant represented by, for example, an ethylene oxide and / or propylene oxide adduct of an alkyl (or alkenyl) amine (or amide), etc. (J) General formula:

[Chemical 11] [Where A and B are —CH ₂ —CH ₂ —O— or —C
H ₂ —C (CH ₃ ) H—O— is represented, and their positions are not limited. m ₁ , m ₂ , m ₃ , m ₄ , n ₁ , n
₂ , n ₃ and n ₄ are integers and m ₁ + m ₂ + m ₃ + m ₄ = 5
˜70, n ₁ + n ₂ + n ₃ + n ₄ = 5-70. m
₁ , m ₂ , n ₁ and n ₂ each independently represent an integer of 0 to 6. However, the sum of m ₁ and n ₁ , and further the sum of m ₂ and n ₂ is within the range of 1 to 6. x represents an integer of 2 or 3. R represents an alkyl group (C ₁ ~C ₃₀₎ or alkenyl group (C ₁ ~C _30). ] An alkylene oxide adduct-based surfactant of alkylene diamine represented by the following, for example, ethylene oxide and / or propylene oxide N adduct of ethylene diamine, (K) general formula:

[Chemical 12] [Here, R _a represents an alkyl group (C _{1 to} C ₂₀ ),
R _b is (CH ₂ ) _m OH or (CH ₂ ) OCH ₂ COO
^- a represents R _c is an alkyl group _{(C 1 ~C 4), (} CH
₂ ) _n COO ⁻ , (CH ₂ ) _n SO ₃ ^— or CH (OH)
CH ₂ SO ₃ ^— , m and n each represent an integer of 1 to 4. M represents an alkali metal, and X represents a halogen, a hydroxyl group or an alkanesulfonic acid group (C _{1 to} C ₅ ). R
_{When c} is an alkyl group, M is absent. When R _c is other than an alkyl group, M may or may not be present.
X does not exist when does not exist. ] Alkylimidazolinium betaine-based surfactants represented by, for example, 2-lauryl (oleyl, cetyl, stearyl, behenyl ...)-N-methyl-N-hydroxyethylimidazolinium betaine, (L ) General formula:

[Chemical 13] [Here, R _a represents hydrogen or a methyl group, or may have no bond. R _b represents hydrogen or a methyl group or an ethyl group, and one hydrogen atom of the alkyl group may be bonded to an acyloxy group via an ether bond. R _c
Represents an alkyl group (C ₅ -C ₂₀ ). The carboxyl group may be ionically bonded to hydrogen or an alkali metal.
m represents an integer of 1 to 4, and n represents an integer of 0 to 4. ] An alkyl (or amido) betaine-based surfactant represented by, for example, dimethyllauryl (oleyl, cetyl, stearyl, behenyl ...) Betaine, etc., (M) General formula:

[Chemical 14] [Wherein, X represents a halogen, a hydroxyl group or an alkane sulfonic acid group (C ₁ -C _5), R _a represents an alkyl group (C ₁
To C ₂₀ ), R _b and R _c are alkyl groups (C ₁ to
C ₄ ) or an alkoxyl group (C _{1 to} C ₁₀ ) and R
_d represents an alkyl group (C ₁ ~C _10), a benzyl group or a fatty acid (CH _{2) n} COOH, where, n represents 1 to 18
Represents the integer. R _e represents an alkyl group _{(C 8 ~C 20), R} f represents hydrogen or an alkyl group (C ₁ ~C _4). ] Ammonium or pyridinium quaternary salt-based surfactants represented by, for example, lauryl (oleyl, cetyl, stearyl, behenyl ...) Tri (di) methylammonium chloride and the like can be used.

Further, among them, those which can be easily obtained as a commercial product are specifically mentioned. As those represented by the above formula (A), Perex NB-L and Demol N (manufactured by Kao Corporation). And the like are represented by the above formula (B), such as Epan 720, Epan 740, Epan 750, Epan 450 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Pluronic L
64, Pluronic L101, Pluronic P103,
Pluronic PP150 (manufactured by Asahi Denka Co., Ltd.), Nikkor BO-20 (manufactured by Nikko Chemicals Co., Ltd.), Emulgen L-40 (manufactured by Kao Corporation), 50HB-20
00/5000 (manufactured by Sanyo Kasei Co., Ltd.) and the like are those represented by the above formula (C), which are BLAUNON EL-130
3, Braunon EL-1509, Braunon CH-31
0 (manufactured by Aoki Yushi Kogyo Co., Ltd.), Newcol 1110
(Manufactured by Nippon Emulsifier Co., Ltd.), Nikkor BL, Nikkor MYL-10 (manufactured by Nikko Chemicals Co., Ltd.), Neugen ET-170 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) and the like are represented by the formula (D). Neugen EA-15 as represented by
0, Neugen EA-130T (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Blaunon NK-808, N-512, DP-9.
(Aoki Yushi Kogyo Co., Ltd.), Newcall 704, Newcall 707, Newcall 710, Newcall 714, Newcall 723 (Nippon Emulsifier Co., Ltd.), Braunon LPE-1007 (Aoki Yushi Industry Co., Ltd.) ), Adecatol NP-15, Adecatol NP-720 (manufactured by Asahi Denka Kogyo Co., Ltd.) and the like, as those represented by the above formula (E), Braunon BN-18.
(Aoki Yushi Kogyo Co., Ltd.), ADEKA TOL PC-10
(Asahi Denka Kogyo Co., Ltd.), Neugen EN-10 (Daiichi Kogyo Seiyaku Co., Ltd.) and the like are those represented by the formula (F), Newcol 2607 (Nippon Emulsifier Co., Ltd.). Manufactured by Aoki Yushi Kogyo Co., Ltd., and the like, as those represented by the formula (G), Ribonox NC-100 (manufactured by Lion Co., Ltd.) and the like. As represented by (H), ADEKA COL PS-4
40E, ADEKA COL CS-141E, ADEKA COL T
S-230E (manufactured by Asahi Denka Kogyo Co., Ltd.) and the like are those represented by the above formula (I), such as Nymeen L207, Nymeen T2-210, and Nymeen S-215 (Nippon Yushi Kogyo Co., Ltd.). , Newcol 420 (manufactured by Nippon Emulsifier Co., Ltd.), BLAUNON O-205 (manufactured by Aoki Yushi Kogyo Co., Ltd.), etc. are represented by the formula (J) as Tetronic TR-701, TE Tronic TR-7
No. 02 (manufactured by Asahi Denka Kogyo Co., Ltd.) and the like, as those represented by the above (K), softazoline, softazoline CL, softazoline CH, softazoline CHS, softazoline N
S, softazoline SF (manufactured by Kawaken Fine Chemicals Co., Ltd.), Nissan Anon GLM-R (manufactured by NOF Corporation), Levon 101-H (manufactured by Sanyo Chemical Industry Co., Ltd.),
Nikkor AM-103EX (manufactured by Nikko Chemicals Co., Ltd.) and the like are represented by the above formula (L) as Nissan Anon BF, Nissan Anon BL, Nissan Anon L.
G, Nissan Anon BDF-R (manufactured by NOF Corporation), Amfotage KJ-2 (manufactured by LONZA),
Acetamine 24 (manufactured by Kao Co., Ltd.) or the like is the above formula (M).
Examples thereof include Nikkor CA2150, Nikkor CA101 (manufactured by Nikko Chemicals Co., Ltd.), Texnol R-5 (manufactured by Nippon Emulsifier Co., Ltd.) and the like. The kind and amount of the surfactant added are not particularly limited, but if the concentration is extremely low, the smoothing effect will not be recognized, so about 0.01 g / L is necessary, and about 50 g / L. When the concentration is higher than L, a phenomenon such as cloudiness of the bath occurs. Therefore, the usage amount is usually 0.0
It is set to 1 to 50 g / L, particularly 0.5 to 20 g / L.

Furthermore, in the plating bath of the present invention, an antioxidant and / or a reducing agent can be added in order to stabilize tin in the plating solution and at the same time increase the plating rate. Known antioxidants and / or reducing agents can be used, resorcinol, pyrocatechol, hydroquinone, phlorogricinol, pyrogallol, hydrazine hydrate, formalin, hypophosphorous acid and its salts, glyoxy acid and its salts, dimethyl. There are amine borane, trivalent titanium and the like. The amount used is 0.05 to 50 g / L
The degree is appropriate, and preferably 0.1 to 10 g / L.

The pH range in which the plating bath of the present invention can be used is strongly acidic to pH 13, preferably strongly acidic to pH 11.
Therefore, when used in the neutral range, a pH buffering agent can be added to reduce the pH fluctuation of the bath. Known buffers can be used, for example, ammonium chloride or sodium, potassium and ammonium salts of phosphoric acid, acetic acid, boric acid, tartaric acid, etc.,
Further, in the case of a polybasic acid, an acid salt containing hydrogen ions or the like can be used alone or in an appropriate mixture. The amount of the pH buffer used is appropriately about 1 to 50 g / L, preferably about 1 to 20 g / L.

Further, a crystal refining agent can be used in order to refine the crystals of the precipitate according to the purpose and obtain a plating film having semi-gloss or gloss. Examples of the crystal refining agent include the following (1) to (18). These can be used alone or in admixture as appropriate. When the natural polymer substance of (1) below is used, the amount used is 0.5 to 50 g / L, and preferably 1 to 20 g / L. 0.005 to 30 g / L is suitable for the crystal refining agent of the following groups (2) to (18), and preferably 0.02 to 20 g / L is added.

(1) Gelatin and peptone. (2) General formula:

[Chemical 15] [Here, R _b represents hydrogen, an alkyl group (C _{1 to} C ₄ ), or a phenyl group, and R _a represents hydrogen or an alkyl group (C ₁
To C ₄ ), R _c represents hydrogen or a hydroxyl group, and A
Represents a single bond, an alkyl group (C ₁ -C ₄ ), a benzyl group or a phenylene group. ] The sulfanilic acid derivative and its salt represented by these. (3) General formula:

[Chemical 16] [Here, X represents hydrogen or an alkyl group (C _{1 to} C ₄ ), R represents hydrogen or —CH ₃ , and n is 2 to 1
Represents an integer of 5. ] Quinolines represented by (4) General formula:

[Chemical 17] [Where X is hydrogen, halogen, an alkyl group (C ₁ -C
₄ ), acetyl group, amino group, hydroxyl group or carboxyl group, R _b represents hydrogen or hydroxyl group, n
Represents an integer of 0 to 12. ] The benzotriazole and its derivative represented by these. (5) General formula:

[Chemical 18] [Here, R < ₁ >, R < ₂ >, R < ₃ >, R < ₄ >, R < ₅ > may be the same or different, and -H: -SH: -OH: -O.
R (R is a C ₁ -C ₆ alkyl group optionally substituted with —COOH), halogen, —COOH, —
COCOOH, aryl, -SR (R is -C if desired.
C ₁ -C ₆ alkyl optionally substituted with OOH),

[Chemical 19] -NH _2, -NRR '(R and R' may be C ₁ -C ₆ alkyl or together form a ring), - NHCO
R (R is C ₁ -C ₆ alkyl), —NHCO aryl,
-NHNH _2, -NO _2, -CONH aryl, -CS
NH _{aryl, -CN, -CHO: -SO 3 H} : -SO
₂ NH ₂ or —SO ₂ NRR ′ (R and R ′ are C _{1 to} C
₆ alkyl or may together form a ring). ] Benzothiazoles represented by. (6) General formula:

[Chemical 20] [Here, R _a1 and R _a2 each independently represent hydrogen and a hydroxyl group, and R _b1 and R _b2 each independently represent an alkyl group (C _{1 to} C ₅ ). ] Imines represented by. (7) General formula:

[Chemical 21] [Where R _a is hydrogen, halogen, an alkyl group (C _1-
C ₄ ), R _b represents hydrogen or a hydroxyl group, and n represents an integer of 0-12. ] Triazines represented by. (8) General formula:

[Chemical formula 22] [Here, R _a and R _b may be the same or different and each is hydrogen, an alkyl group (C _{1 to} C ₁₈ ), an alkoxy group (C ₁
To C ₁₈ ) or a C _{3 to} C ₇ cycloalkyl group,
A represents a lower alkylene group. ] Triazines represented by. (9) General formula:

[Chemical formula 23] [Wherein, R represents an alkyl group (C ₁ ~C ₄₎ or phenyl group. ] The ester of aromatic oxycarboxylic acid represented by these. (10) the general _{formula: R a -CR b = CH-} CO-X-R c [ wherein, R _a and R _c are phenyl, naphthyl, pyridyl, quinolyl, thienyl, furyl and pyronyl, amino group, hydroxyl group, or A group selected from hydrogen, which is C ₁ -C ₆ alkyl, C ₁ -C ₆ alkyloxy, C
₁ -C ₆ acyl, C ₁ -C ₆ alkylthio, OH, halogen, carboxyl group, -NO ₂ and -NR _d R _e (R
_d and R _e are the same or different and each is hydrogen or C ₁ -C.
₄ alkyl) having 1 or more same or different substituents selected from
There may be four, or R _a and R _c may combine to form a ring, or R _c may be R _a —CR _b ═CH—C.
It may be equal to O-. X is a single bond or -CH ₂
− R _b is hydrogen or C ₁ -C ₄ alkyl. ] The compound which has a double bond in the conjugate position with C = O represented by these. (11) General formula: R-CHO [wherein R is a group selected from C ₁ -C ₆ alkyl, phenyl, naphthyl, acenaphthyl, pyridyl, quinolyl, thienyl, furyl, indole and pyronyl, an aldehyde group or hydrogen. And the group is C ₁ -C ₆ alkyl, C ₁ -C ₆ alkyloxy, C ₁ -C ₆ acyl, C
₁ -C ₆ alkylthio, OH, halogen, NO ₂ and -
NR _{d Re} (R _d and R _e may be the same or different and each is hydrogen or C ₁ -C ₄ alkyl) and may have 1 to 4 substituents which are the same or different. ] Aldehydes represented by (12) the general _{formula: R a -CO- (CH 2)} n -CO-R b [ where, R _a and R _b are the same or different from each other hydrogen, C ₁ -C ₆ alkyl and -C ₂ H ₄ -CO-CO-
A C ₂ H _5, n is an integer of 0-2. ] The diketones represented by. (13) General formula: in R _a -NH-R _b [where, R _a is a phenyl group, said group C ₁ -C ₃
It may be substituted with an alkyl, halogen or amino group. R _b is hydrogen, C ₁ -C ₃ alkyl, -NH-CS-
N = N-φ and -CH ₂ -φ-NH ₂ . ] An aniline derivative represented by. (14) General formula:

[Chemical formula 24] [Here, R _a and R _b are the same or different and each represents hydrogen, a lower alkyl group, a hydroxyl group, a nitro group, a carboxyl group or a sulfonic acid group. ] The nitro compound represented by these, or its sodium, potassium, or ammonium salt. (15) General formula: HOOC-CHR-SH [wherein R is hydrogen or C ₁ -C ₂ alkyl, and the alkyl group may be substituted with a carboxyl group. ] The mercaptocarboxylic acid represented by these. (16) Heterocyclic compounds selected from the following: 1,10
-Phenanthroline, 2-vinylpyridine, 2-cinnamylthiophene, 1,2,3- (or 1,2,4- or 1,3,5-) triazine, 2,4-diamino-6-
(2'-undecylimidazolyl (1 ') methyl-S-
Triazine, 1,2,3-benzotriazine, indole, imidazole, 2-mercaptobenzimidazole, 2-mercaptobenzoxazole, quinoline. (17) Acetophenone and halogenated acetophenone. (18) Amine-aldehyde condensate.

Of these crystal refining agents, particularly preferred examples include a product obtained by adding 5 mol of propylene oxide to 8-hydroxyquinoline, N, N'-diisobutylidene-o-phenylenediamine, Benzothiazole, 2
-Amino-4-chlorobenzothiazole, 2-amino-
6-methoxybenzothiazole, 2-hydroxybenzothiazole, 2-chlorobenzothiazole, 2-methyl-5-chlorobenzothiazole, 2,5-dimethylbenzothiazole, 5-hydroxy-2-methylbenzothiazole, 6-chloro- 2-methyl-4-methoxybenzothiazole, 2- (n-butyl) mercapto-6-aminobenzothiazole, 2-benzothiazolethioacetic acid,
2-benzothiazoleoxyacetic acid, 2-methylbenzothiazole, 2-mercaptobenzothiazole, 6-ethoxy-2-mercaptobenzothiazole, N-butylidene sulfanilic acid, N-cinnamoylidene sulfanilic acid, N- (3-hydroxy Butylidene) -p-sulfanilic acid, aldol, benzaldehyde, m-chlorobenzaldehyde, p-nitrobenzaldehyde, p-hydroxybenzaldehyde, (o-, m-, p-) methoxybenzaldehyde, o-vanillin, veratrumaldehyde, ( 2,4-, 2,6-Dichlorobenzaldehyde, (o-, p-) chlorobenzaldehyde, 1-naphthaldehyde, 2-naphthaldehyde, 2 (4) -hydroxy-1-naphthaldehyde, 2 (4)- Chlor-
1-naphthaldehyde, 5-methoxynaphthaldehyde, picolinaldehyde, 3-acenaphthaldehyde,
2 (3) -thiophenecarboxaldehyde, 2 (3)
-Furaldehyde, 3-indolecarboxaldehyde, salicylaldehyde, o-phthalaldehyde, formaldehyde, acetaldehyde, paraaldehyde, butyraldehyde, isobutyraldehyde, propionaldehyde, n-valeraldehyde, acrolein, crotonaldehyde, glyoxal, succinaldehyde, Capronaldehyde, isovaleraldehyde, allylaldehyde, glutaraldehyde, 1-benzylidene-7-heptenal, 2,4-hexadienal, cinnamaldehyde, benzylcrotonaldehyde, amine-aldehyde condensate, mesityl oxide, isophorone,
Diacetyl, hexanedione-3,4-acetylacetone, 3-chlorobenzylideneacetone, sub, pyridylideneacetone, sub, furfuridineacetone, su
b, tenylideneacetone, 4- (1-naphthyl) -3-
Buten-2-one, 4- (2-furyl) -3-butene-
2-one, 4- (2-thiophenyl) -3-butene-2
-On, curcumin, benzylidene acetylacetone,
Benzalacetone, acetophenone, (2,4-, 3,
4-) Dichloroacetophenone, benzylideneacetophenone, benzylidenemethylethylketone, benzylidenecetone alcohol, p-toluideneacetone, p-hydroxybenzylideneacetone, benzylidenemethylisobutylketone, 4- (1-naphthyl) -3-butene-
2-one, 2-cinnamylthiophene, 2- (ω-benzoyl) vinylfuran, vinylphenylketone, biphenylpropenylketone, phenylisobutenylketone,
Phenyl-2-methylpropenyl ketone, p-fluoro or chlorophenylpropenyl ketone, p-hydroxyphenylpropenyl ketone, m-nitrophenylpropenyl ketone, p-methylphenylpropenyl ketone,
2,4,6-trimethylphenylpropenyl ketone, p
-Methoxyphenylpropenyl ketone, p-methoxyphenylbutenyl ketone, p-methylthiophenylpropenyl ketone, p-isobutylphenylpropenyl ketone, α-naphthyl-1-methylpropenyl ketone, 4-
Methoxynaphthylpropenyl ketone, 2-thienylpropenyl ketone, 2-furylpropenyl ketone, 1-methylpyrrolepropenyl ketone, acrylic acid, methacrylic acid, ethacrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, butyl methacrylate, croton Acid, itaconic acid, propylene-1,3-dicarboxylic acid, cinnamic acid, acrylamide, diacetone acrylamide, t-butyl acrylamide, N-methoxydimethyl acrylamide, (o-, m-, p-) toluidine,
(O-, p-) aminoaniline, aniline, (o-, p
-) Chloraniline, (2,5-, 3,4-) chloromethylaniline, N-monomethylaniline, 4,4'-diaminodiphenylmethane, N-phenyl- (α-, β
-) Naphthylamine, dithizone, benzotriazole,
4-hydroxybenzotriazole, 4-carboxybenzotriazole, 4-methylbenzotriazole,
1,2,3-triazine, 1,2,4-triazine,
1,3,5-triazine, 1,2,3-benztriazine, 2,4-diamino-6- [2'-methylimidazolyl (1 ') ethyl] -1,3,5-triazine, 2,4
-Diamino-6- [2'-ethylimidazolyl (1 ')
Ethyl] -1,3,5-triazine, 2,4-diamino-6- [2'-undecylimidazolyl (1 ') ethyl] -1,3,5-triazine, β-N-dodecylaminopropioguanamine , Β-N-hexylaminopropioguanamine, piperidine propioguanamine, cyclohexylaminopropioguanamine, morpholine propioguanamine, β-N- (2-ethylhexyloxypropylamino) propioguanamine, β-N- (lauryl) Oxypropylamino) propioguanamine, o- (m
-, P-) methyl benzoate, phenyl salicylate, p-
Nitrophenol, Nitrobenzenesulfonic acid, 2,4
-Dinitrobenzenesulfonic acid, m-nitrobenzoic acid,
Examples thereof include thioglycolic acid, mercaptosuccinic acid, imidazole, 2-vinylpyridine, indole and quinoline.

Furthermore, nitrate ions can be added to the plating bath of the present invention as a promoter of the plating rate.
As the source of nitrate ions, known sources can be used,
Nitric acid, sodium nitrate, potassium nitrate, ammonium nitrate, silver nitrate, etc. can be used. Addition of nitrate ions improves the rate of substitution tin plating, but the effect is significantly reduced at 0.01 mol / L or less, so the lower limit of the addition rate is 0.01 mol / L. Further, when the concentration is extremely high, the copper of the base material is excessively dissolved, so it is preferable to set the upper limit to about 0.5 mol / L.

[0025]

EXAMPLES Next, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples, and the composition of the plating bath and the plating conditions are appropriately set in accordance with the above-mentioned object. It can be changed arbitrarily. A tin-silver alloy electroless plating bath having the following composition was prepared.
A sodium hydroxide aqueous solution and sulfuric acid were used to adjust the pH. The obtained plating bath was heated to a predetermined temperature, and the copper plate pretreated in the steps of buff polishing → benzine degreasing → electrolytic degreasing → water washing → 5% sulfuric acid immersion → water washing was immersed for 20 minutes. Also in the following examples, the same treatment was performed except for the conditions such as temperature conditions which are clearly specified.

Comparative Example Tin methanesulfonate 0.1 mol / L Silver methanesulfonate 0.004 mol / L pH 1 Bath temperature 60 ° C. The plating solution becomes cloudy when heated and cannot be used as a plating solution. There wasn't.

Example 1   Tin methanedisulfonate 0.1 mol / L   Silver methanesulfonate 0.004 mol / L   Thiourea 1 mol / L   Sodium pyrophosphate 0.5 mol / L   Potassium oxalate 0.1 mol / L   pH 5   Bath temperature 60 ℃

Example 2   Tin sulfate 0.1 mol / L   Silver pyrophosphate 0.004 mol / L   Potassium iodide 0.5 mol / L   Thiourea 1 mol / L   Sodium pyrophosphate 0.5 mol / L   EDTA 0.1 mol / L   Demol N (manufactured by Kao Corporation) 0.5 g / L   Softazoline CH (Kawaken Fine Chemicals Co., Ltd.) 1 g / L   Gelatin 5 g / L   Ammonium chloride 5 g / L   pH 7   Bath temperature 90 ℃

Example 3   2-Hydroxypropanol tin sulfonate 0.1 mol / L   Silver citrate 0.004 mol / L   Potassium iodide 0.5 mol / L   Thiourea 1 mol / L   Sodium gluconate 1 mol / L   Sodium citrate 0.2 mol / L   Sulfosuccinic acid 0.2 mol / L   Nikkor CA101 (manufactured by Nikko Chemicals Co., Ltd.) 1 g / L   Softazoline CH (Kawaken Fine Chemicals Co., Ltd.) 0.5 g / L   1,3,5-benzotriazine 2 g / L   pH 4   Bath temperature 90 ℃

Example 4   Tin chloride 0.1 mol / L   Silver chloride 0.004 mol / L   Sodium thiosulfate 0.5 mol / L   Thiourea 1 mol / L   Potassium pyrophosphate 0.5 mol / L   Glycolic acid 0.2 mol / L   Liponox NC-100 (manufactured by Lion Corporation) 0.1 g / L   Softazoline CH (Kawaken Fine Chemicals Co., Ltd.) 2 g / L   2-methylbenzothiazole 0.1 g / L   Methacrylic acid 5 g / L   N, N'-isobutylidene-o-phenylenediamine 0.15 g / L   Nitric acid 20 g / L   pH 1   Bath temperature 70 ℃

Example 5   Tin pyrophosphate 0.25 mol / L   Silver oxide 0.1 mol / L   Potassium iodide 0.5 mol / L   Thiourea 1 mol / L   Sodium pyrophosphate 0.6 mol / L   Newcol 2607 (Nippon Emulsifier Co., Ltd.) 0.2 g / L   ADEKA COL PS-440E (manufactured by Asahi Denka Co., Ltd.) 0.3 g / L   Mercaptosuccinic acid 30 g / L   2,4-Diamino-6- [2'-methylimidazolyl (1 ') ethyl]                             -1,3,5-triazine 0.05 g / L   To 8-hydroxyquinoline           5 mol propylene oxide addition product 1 g / L   Benzotriazole 0.05 g / L   pH 4   Bath temperature 80 ℃

Example 6   Tin methanesulfonate 0.004 mol / L   Mercaptosuccinate silver 0.0005 mol / L   Mercaptosuccinic acid 0.001 mol / L   Potassium iodide 0.5 mol / L   Thiourea 1 mol / L   Sodium gluconate 0.2 mol / L   1-hydroxyethane-1,1-bisphosphonic acid 0.01 mol / L   ADEKA TOL PS-10 (manufactured by Asahi Denka Co., Ltd.) 0.01 g / L   Nymeen L207 (Nippon Yushi Co., Ltd.) 0.1 g / L   Acetamine 24 (manufactured by Kao Corporation) 20 g / L   β-N-dodecylaminopropioguanamine 0.1 g / L   Nitrobenzoic acid 1 g / L   Diacetyl 0.1 g / L   Hydroquinone 1 g / L   pH 6   Bath temperature 70 ℃

Example 7 A test panel having nickel plating of about 3 μm was used as a sample. Tin borofluoride 0.1 mol / L Silver nitrate 0.004 mol / L Potassium bromide 0.004 mol / L Potassium iodide 0.5 mol / L Thiourea 1 mol / L Sodium gluconate 1 mol / L Ascorbic acid 0 .2 mol / L Neugen EA-150 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) 0.05 g / L Tetronic TR-701 (manufactured by Asahi Denka Co., Ltd.) 0.3 g / L Nikkor CA101 ( Nikko Chemicals Co., Ltd.) 0.5 g / L Phenyl salicylate 0.5 g / L 3,4-chloromethylaniline 0.5 g / L N- (3-hydroxybutylidene) -p-sulfanilic acid 5 g / L Isovaleraldehyde 0.005 g / L Glyoxylic acid 5 g / L Ammonium nitrate 20 g / L pH 13 Bath temperature 40 ° C

Example 8   Tin sulfamate 0.1 mol / L   Silver iodide 0.004 mol / L   Succinimide 0.004 mol / L   Potassium iodide 0.5 mol / L   Thiourea 1 mol / L   Sodium pyrophosphate 0.5 mol / L   Glycine 0.1 g / L   Brownon EL-1509 (Aoki Yushi Kogyo Co., Ltd.) 0.05 g / L   Epan 740 (Daiichi Kogyo Seiyaku Co., Ltd.) 0.05 g / L   2,4-dichloroacetophenone 0.5 g / L   o-Toluidine and acetaldehyde condensate 5 g / L   Hydrazine 1 g / L   Ammonium dihydrogen phosphate 5 g / L   pH 3   Bath temperature 80 ℃

The results of the electroless plating test obtained from each plating bath are summarized in Table 1.

[Table 1]

[0036]

INDUSTRIAL APPLICABILITY The electroless tin-silver alloy plating bath according to the present invention has a smooth and dense tin-silver alloy plating film obtained from a non-cyan bath. The present invention provides a surface treatment compatible with silver solder.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-8-239774 (JP, A) JP-A-5-221763 (JP, A) JP-A-5-287543 (JP, A) JP-A-5- 112874 (JP, A) JP 4-289178 (JP, A) JP 7-97467 (JP, A) JP 50-20362 (JP, A) JP 9-296274 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C23C 18/48

Claims (8)

(57) [Claims] 1. A non-cyan type tin-silver alloy electroless plating solution containing the following (I) and (II) as essential components: (I) a non-cyan compound of divalent tin and a non-cyan of monovalent silver. A compound, and (II) a mono- or di-alkyl thiourea in which the amount of (a) thiourea and the alkyl group having 1 to 3 carbon atoms are sufficient to keep the monovalent silver compound stable in the liquid, (b) Thiosulfate, (c)
One or more compounds selected from iodine compounds, (d) bromine compounds, (e) succinimide, and (f) mercaptosuccinic acid, or salts thereof. 2. Further, one or more complexing agents selected from the following (a) to (j) are added in order to keep the divalent tin compound stable in the aqueous solution. Item 1. Non-cyanide tin-silver alloy electroless plating solution according to Item 1: (a) Aliphatic dicarboxylic acid having an alkyl group having 0 to 3 carbon atoms, (b) Aliphatic hydroxy having an alkyl group having 1 to 2 carbon atoms A monocarboxylic acid, (c) an aliphatic hydroxypolycarboxylic acid having an alkyl group having 1 to 3 carbon atoms, (d) a monosaccharide and a polyhydroxycarboxylic acid in which a part thereof is oxidized, and a cyclic ester compound thereof, (e) ) Aliphatic mono- or di-amino, mono- or di-carboxylic acid having 1 to 4 carbon atoms in the alkyl group, (f) Aliphatic monomercaptomonocarboxylic acid and fat having 2 to 3 carbon atoms in the alkyl group Group Monomercapto dicarb An acid and an aliphatic monomercaptomonoaminomonocarboxylic acid, (g) an aliphatic monosulfomonocarboxylic acid and an aliphatic monosulfodicarboxylic acid having an alkyl group having 2 to 3 carbon atoms, (h) the following aminecarboxylic acid: Ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), triethylenetetraminehexaacetic acid (TTHA), ethylenedioxybis (ethylamine)
-N, N, N ', N'-tetraacetic acid, glycol ethylenediaminetetraacetic acid (GEDTA) and N-hydroxyethylethylenediaminetetraacetic acid (HEEDTA)
Selected from the following: (i) condensed phosphoric acid, and (j) hydroxyalkane bisphosphonic acid having 1 to 3 carbon atoms. 3. The electroless tin-silver alloy plating solution according to claim 1, further comprising one or more surfactants added. 4. The electroless tin-silver alloy plating solution according to claim 1, further comprising one or more reducing agents and / or antioxidants. 5. The electroless tin-silver alloy plating solution according to claim 1, further comprising one or more pH buffering agents. 6. The electroless tin-silver alloy plating solution according to claim 1, further comprising one or more smoothing additives. 7. The electroless tin-silver alloy plating solution according to claim 1, further comprising nitrate ions added as a precipitation accelerator. 8. An object to be plated is dipped in the electroless plating solution according to any one of claims 1 to 7 to form a tin-silver alloy plating film on the object to be plated. Electrolytic tin-silver alloy plating method.