JP2001172791A - Tin-copper base alloy plating bath and electronic part with tin-copper base alloy film formed by the plating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely coprecipitate tin with copper, etc., in a high composition ratio in a tin-copper base ternary alloy plating bath and to prevent the formation of whiskers and the cracking in bending. SOLUTION: This tin-copper base ternary alloy plating bath contains (A) a soluble stannous salt, (B) a soluble copper salt, (C) a soluble salt of the third- component metal selected from a group consisting of iron, cobalt, nickel, bismuth, antimony, titanium and zirconium and (D) a surfactant. When the surfactant is incorporated into the tin-copper-X alloy plating bath (metallic X=iron, nickel, bismuth, etc.), the polarization of the copper and metallic X nobler in the standard electrode potential is increased, and tin is surely coprecipitated with the metallic X in a high composition ratio. Further, the formation of whiskers and the cracking in bending are prevented, and an electrodeposited film excellent in solderability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a tin-copper ternary alloy plating bath such as a tin-copper-iron alloy, a tin-copper-nickel alloy, a tin-copper-bismuth alloy, and the use of the plating bath. For electronic components with a tin-copper alloy film formed, together with copper and third component metals such as iron, nickel and bismuth, tin is reliably eutectoidized at a high composition ratio, and tin whiskers and cracks are generated. It provides a plating film that prevents corrosion and has excellent solderability.

[0002]

BACKGROUND OF THE INVENTION In recent years, there has been a concern about the influence of lead on the human body and the environment, and whiskers may occur in pure tin plating. Therefore, there is a demand for the development of lead-free solder plating. . Lead-free solders include tin-silver alloys, tin-bismuth alloys, or tin-silver alloys.
Copper alloys and the like are being studied, but tin-silver alloy plating tends to decompose the plating bath, resulting in poor bath stability, and is expensive, and whiskers are more likely to occur in tin alloys . Whisker is unlikely to occur in a tin-bismuth alloy, but cracks are likely to occur in bending and the like. On the other hand, in the case of a tin-copper alloy, on the contrary, the above cracks are hardly generated and the cost is low, but a problem that whiskers are easily generated remains. Therefore, each of the various tin alloys described above has excellent advantages, but also has problems, and is not a sufficient candidate for a lead-free solder.

On the other hand, tin-copper ternary alloys such as tin-copper-iron alloy, tin-copper-nickel alloy and tin-copper-bismuth alloy have lower costs than tin-silver alloy and the like. An effect can be expected in terms of suppressing the adverse effects of whisker generation of the tin-copper alloy.

[0004]

2. Description of the Related Art For example, JP-A-8-13185 discloses (a) Sn ²⁺ ion, (b) Ag ⁺ , Cu ²⁺ , In ³⁺ ,
A lead-free tin alloy plating bath containing at least one metal ion selected from the group consisting of Tl ⁺ and Zn ²⁺ and (c) a nonionic surfactant is described in Example 3 (the same publication). (See paragraph 28)), a tin-copper alloy plating bath composed of stannous methanesulfonate, copper methanesulfonate, methanesulfonic acid, and an ethylene oxide adduct of octylphenol ethoxylate;
In Example 4 (see paragraph 29 of the publication), a tin-copper alloy plating bath composed of stannous methanesulfonate, copper methanesulfonate, methanesulfonic acid, and an ethylene oxide adduct of laurylamine was used, respectively. It has been disclosed.

However, tin-copper-iron alloys, tin-
Plating baths such as copper-nickel alloys and tin-copper-bismuth alloys are not found in the above-mentioned publications, and it is difficult to find reports in other publications in the field of plating.

[0006]

When the tin-copper ternary alloy described above is examined, for example, as a typical tin-copper-bismuth alloy, the standard electrode potentials of tin, bismuth and copper are as follows. is there. Sn ²⁺ + 2e ⁻ → Sn E ° = −0.138 Bi ³⁺ + 3e ⁻ → Bi E ° = + 0.320 Cu ²⁺ + 2e ⁻ → Cu E ° = + 0.337 As seen in the above table, bismuth and copper Since the standard electrode potential is more noble than tin, when electroplating is performed using a tin-copper-bismuth alloy plating bath, copper or bismuth actually precipitates preferentially, and tin has a high composition ratio. It is not easy to eutectoid with metal.

According to the present invention, an electrodeposition film excellent in solderability, etc., in addition to copper and a third component metal such as iron, nickel, bismuth, etc., in which tin is reliably eutectoidized, whiskers and cracks are prevented from being generated. It is a technical object to develop a tin-copper alloy plating bath capable of obtaining the following.

[0008]

First, the present inventors have found that, for example, when a tin-copper-bismuth alloy plating bath contains a surfactant, the polarization of noble copper and bismuth at a standard electrode potential becomes large. It has been found that tin can be eutectoidized with copper and bismuth at a high composition ratio. Next, specific tin-copper ternary alloys such as the tin-copper-bismuth alloy, tin-copper-iron alloy, and tin-copper-nickel alloy are effective in generating whiskers and cracks during bending. In addition, it is excellent in solderability, so to say, while combining the advantages of tin-copper alloy and tin-X alloy (X = third component metal such as iron, nickel and bismuth), The inventors have found that the problems of the original alloy can be reduced, and have completed the present invention.

That is, the present invention 1 relates to a (A) soluble stannous salt, (B) a soluble copper salt, (C) iron, cobalt, nickel, bismuth, antimony, titanium, zirconium. A tin-copper alloy plating bath containing at least one soluble salt of a three-component metal and (D) a surfactant.

The present invention is characterized in that the above-mentioned surfactant of the present invention comprises C ₁ -C ₂₀ alkanol, phenol, naphthol, bisphenols, C ₁ -C ₂₅ alkylphenol, arylalkylphenol, C ₁ -C ₂₅ alkylnaphthol, C ₁ -C ₂₅ alkoxylated phosphoric acid, sorbitan ester, polyalkylene glycol, C ₁ -C ₂₂
A tin nonionic surfactant comprising an adduct of ethylene oxide and / or propylene oxide such as an aliphatic amine or a C _{1 to} C ₂₂ aliphatic amide;
This is a copper-based alloy plating bath.

The present invention relates to (A) a soluble stannous salt, (B)
Soluble copper salt, (C) iron, cobalt, nickel, bismuth,
At least one soluble salt of the third component metal selected from the group consisting of antimony, titanium, and zirconium; (D) an organic sulfonic acid, an aliphatic carboxylic acid, an oxycarboxylic acid,
This is a tin-copper alloy plating bath containing at least one kind of organic acids such as aminocarboxylic acids and salts thereof.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the soluble stannous salt, the soluble copper salt and the soluble metal salt of the third component are mixed in the plating bath with a soluble copper salt / soluble stannous salt. A tin-copper system wherein the salt is 0.001 to 0.25 and the weight ratio of the third component soluble metal salt / soluble stannous salt is 0.0001 to 0.1. This is an alloy plating bath.

[0013] The present invention 5 is a tin-copper alloy plating bath characterized in that the plating bath of any of the above-mentioned present inventions 1-4 further contains an antioxidant.

According to a sixth aspect of the present invention, there is provided a semiconductor device, a connector, a switch, a resistor, and a tin-copper alloy plating film formed on a substrate by electroplating using the plating bath according to any one of the first to fifth aspects. Electronic components such as variable resistors, capacitors, filters, inductors, thermistors, crystal units, and lead wires.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The soluble metal salt used in the tin-copper ternary alloy plating bath of the present invention basically refers to any organic or inorganic metal salt that generates a corresponding metal ion in water. Specific examples of the soluble stannous salts include stannous salts of organic sulfonic acids such as methanesulfonic acid, ethanesulfonic acid, 2-propanolsulfonic acid, p-phenolsulfonic acid, stannous borofluoride, sulfosuccinic acid and the like. Stannous acid, stannous sulfate, stannous oxide, stannous chloride and the like can be mentioned. Examples of the soluble copper salt include the above-mentioned copper salts of organic sulfonic acids, copper sulfate, copper chloride, copper oxide, copper carbonate, copper acetate, copper pyrophosphate, copper oxalate and the like. Soluble third component metal salts include third component metals (ie,
Oxides, chlorides, bromides, nitrates, sulfates, salts of the above organic sulfonic acids, sulfosuccinates, and the like of iron, cobalt, nickel, bismuth, antimony, titanium, and zirconium (hereinafter, referred to as metal X). The soluble stannous salts, soluble copper salts, and soluble third component metal salts can be used alone or in combination. Therefore, the plating bath of the present invention is basically a ternary alloy plating bath of tin-copper-X,
4 or more alloy plating bath using more than one kind of X metal salt
(For example, a tin-copper-iron-nickel alloy) (for the sake of convenience, the present invention refers to a tin-copper ternary alloy plating bath).

In the tin-copper ternary alloy plating bath of the present invention, as shown in the present invention 4, the soluble stannous salt, the soluble copper salt and the soluble metal salt of the third component (that is, X
Metal salts) in the following weight ratios. Soluble copper salt / soluble stannous salt = 0.001 to 0.25 Soluble X metal salt / soluble stannous salt = 0.0001 to
When the weight ratio of 0.1 soluble copper / soluble stannous salt exceeds 0.25, the solderability of the resulting electrodeposited film may be reduced, and whiskers may be generated. /
If the weight ratio of the soluble stannous salt exceeds 0.1, cracks may be generated during bending of the electrodeposited film.
Among the soluble salts obtained by summing the soluble stannous salt, the soluble copper salt, and the soluble X metal salt, the total content as metal ions is 5 to 100 g / L with respect to the plating bath.
Preferably it is 7-70 g / L.

The tin-copper-X alloy plating bath (metal X = iron, cobalt, nickel, bismuth, etc.) of the present invention is composed based on an acid or a salt thereof. Organic acids such as aliphatic carboxylic acids, oxycarboxylic acids, and aminocarboxylic acids are exemplified. The above-mentioned organic sulfonic acid is excellent in terms of easy drainage treatment, high solubility of metal salts, high-speed plating, and high conductivity. Further, the above aliphatic carboxylic acids, oxycarboxylic acids, aminocarboxylic acids, and the like are effective in preventing hydrolysis of metal salts in a pH range of about 1 to 10. The above organic acids or salts thereof can be used alone or in combination, and the content thereof is 10 to 400 g / L, preferably 50 to 250 g.
/ L.

The organic sulfonic acid used in the bath base is alkanesulfonic acid, alkanolsulfonic acid, aromatic sulfonic acid and the like, and the alkanesulfonic acid is represented by the chemical formula C _n H _{2n + 1} SO ₃ H (for example, n = 1 to 11), specifically, methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 2-
Examples thereof include propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, decanesulfonic acid, and dodecanesulfonic acid.

[0019] Examples of the alkanol sulfonic acid, the formula _{C m H 2m + 1 -CH (} OH) -C p H 2p -SO 3 H ( e.g., m = 0
~ 6, p = 1 ~ 5), specifically, 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-
1-sulfonic acid (2-propanolsulfonic acid), 2-hydroxybutane-1-sulfonic acid, 2-hydroxypentane-1-sulfonic acid, etc., as well as 1-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-hydroxydodecane-
1-sulfonic acid and the like.

The aromatic sulfonic acid is basically benzenesulfonic acid, alkylbenzenesulfonic acid, phenolsulfonic acid, naphthalenesulfonic acid, alkylnaphthalenesulfonic acid, naphtholsulfonic acid and the like. Examples include acid, 2-naphthalenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, p-phenolsulfonic acid, cresolsulfonic acid, sulfosalicylic acid, nitrobenzenesulfonic acid, sulfobenzoic acid, and diphenylamine-4-sulfonic acid. Among the organic sulfonic acids described above, methanesulfonic acid, ethanesulfonic acid, 2-propanolsulfonic acid, phenolsulfonic acid and the like are preferable.

As the aliphatic carboxylic acid used in the bath base, generally, a carboxylic acid having 1 to 6 carbon atoms can be used, and specific examples thereof include acetic acid, propionic acid, butyric acid, sulfosuccinic acid, and trifluoroacetic acid. No. Examples of the oxycarboxylic acid include citric acid, gluconic acid, tartaric acid, malic acid and the like. Examples of the aminocarboxylic acid include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (N
TA), iminodiacetic acid (IDA), iminodipropionic acid
(IDP), hydroxyethylethylenediamine triacetic acid
(HEDTA), triethylenetetramine hexaacetic acid (TTH
A), glycine, alanine, N-methylglycine, lysine, glutamic acid, aspartic acid, and the like. These aminocarboxylic acids can be used in combination with the above organic sulfonic acid, aliphatic carboxylic acid, or oxycarboxylic acid. Useful.

On the other hand, the tin-copper-X alloy plating bath of the present invention
Examples of the surfactant contained in (metal X = iron, cobalt, nickel, bismuth, etc.) include nonionic, anionic, cationic, and amphoteric surfactants, and these may be used alone or in combination. it can. The addition amount is 0.0
It is 1 to 100 g / L, preferably 0.1 to 50 g / L.

The above surfactant is used for the appearance of the plating film,
Used to improve the smoothness, smoothness, adhesion and throwing power
In particular, nonionic surfactants have large
An improvement effect can be expected. The nonionic surfactant,
C₁~ C₂₀Alkanol, phenol, naphthol, bi
Sphenols, C₁~ C_{twenty five}Alkyl phenols, ants
Alkyl phenol, C₁~ C_{twenty five}Alkyl naphtho
Le, C₁~ C_{twenty five}Alkoxylated phosphoric acid (salt), sorbitan
Ester, styrenated phenol, polyalkylene glycol
Cole, C ₁~ C_{twenty two}Aliphatic amine, C₁~ C_{twenty two}Fatty amy
Ethylene oxide (EO) and / or propylene
Oxide (PO) obtained by addition condensation of 2 to 300 moles
You. Therefore, certain alkanols, phenols, naphtho
Adduct of EO alone, adduct of PO alone, or
Any of adducts in which EO and PO coexist may be used.

C ₁ -C ₂₀ alkanols for addition condensation of ethylene oxide (EO) and / or propylene oxide (PO) include octanol, decanol, lauryl alcohol, tetradecanol, hexadecanol, stearyl alcohol, eicosanol and cetyl alcohol. , Oleyl alcohol, docosanol and the like. Similarly, bisphenols include bisphenol A and bisphenol B. C ₁ -C ₂₅ alkylphenols include mono-, di- or trialkyl-substituted phenols such as p-butylphenol, p-isooctylphenol, p-nonylphenol, p-hexylphenol, 2,4-dibutylphenol, 2,4, Examples include 6-tributylphenol, p-dodecylphenol, p-laurylphenol, p-stearylphenol and the like. Examples of the arylalkylphenol include 2-phenylisopropylphenyl and the like.

The alkyl group of the C ₁ -C ₂₅ alkyl naphthol includes methyl, ethyl, propyl, butylhexyl, octyl, decyl, dodecyl, octadecyl and the like, and may be located at any position on the naphthalene nucleus. C
_1- C ₂₅ alkoxylated phosphoric acid (salt) has the following general formula (a)
It is represented by During Ra · Rb · (MO) P = O ... (a) ( formula (a), R _a and R _b identical or different C ₁ -C ₂₅ alkyl, provided that one is better even H .M is H or an alkali metal is shown.)

As the sorbitan ester, mono-, di- or triester-converted 1,4-, 1,5- or 3,6-sorbitan such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan distearate, sorbitan diester Oleate, sorbitan mixed fatty acid ester and the like can be mentioned. Examples of the C ₁ -C ₂₂ aliphatic amine include saturated and unsaturated fatty acid amines such as propylamine, butylamine, hexylamine, octylamine, decylamine, laurylamine, stearylamine, ethylenediamine, and propylenediamine. C _1-
The C ₂₂ aliphatic amides, propionic acid, butyric acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, amides such as behenic acid.

[0027] As the cationic surfactant, quaternary ammonium salt _{(R 1 · R 2 · R} 3 · R 4 N) represented by the following formula ^{(b) + · X - ...} (b) (In the formula (b), X is halogen, hydroxy, C ₁ -C ₅ alkanesulfonic acid or sulfuric acid, R ₁ , R ₂ and R ₃ are the same or different C ₁ -C ₂₀ alkyl, and R ₄ is C ₁ -C Represents ₁₀ alkyl or benzyl.) Or a pyridinium salt represented by the following general formula (c). R _6- (C ₅ H ₅ N—R ₅ ) ⁺ · X ⁻ (c) (In the formula (c), C ₅ H ₅ N is a pyridyl group, X is a halogen, hydroxy, C ₁ -C ₅ alkane sulfone. Acid or sulfuric acid, R ₅
Represents C ₁ -C ₂₀ alkyl, and R ₆ represents H or C ₁ -C ₁₀ alkyl. )

Examples of the 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 Octadecyldimethylbenzylammonium salt, trimethylbenzylammonium salt, triethylbenzylammonium salt, hexadecylpyridinium salt, laurylpyridinium salt, dodecylpyridinium salt, stearylamine acetate,
Laurylamine acetate, octadecylamine acetate and the like can be mentioned.

Examples of the anionic surfactant include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkylbenzene sulfonates, (mono, di, tri)
Alkyl naphthalene sulfonate 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 (EO12) nonyl ether sulfate and sodium polyoxyethylene (EO15) dodecyl ether sulfate. As polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene (E
O15) Nonyl phenyl ether sulfate and the like. Examples of the alkyl benzene sulfonate include sodium dodecyl benzene sulfonate. Examples of the (mono, di, tri) alkylnaphthalenesulfonate include sodium dibutylnaphthalenesulfonate.

Examples of the amphoteric surfactant include carboxybetaine, imidazoline betaine, sulfobetaine, aminocarboxylic acid and the like. Sulfation or sulfonated adducts of condensation products of ethylene oxide and / or propylene oxide with alkylamines or diamines can also be used.

Representative carboxybetaines or imidazoline betaines include betaine lauryldimethylaminoacetate, betaine myristyldimethylaminoacetate, betaine stearyldimethylaminoacetate, coconut fatty acid amidopropyldimethylaminoacetate betaine, 2-undecyl-1- Carboxymethyl-1-hydroxyethylimidazolinium betaine, 2-octyl-1-carboxymethyl-1-carboxyethylimidazolinium betaine, and the like. Examples of the sulfated and sulfonated adducts include sulfate addition of ethoxylated alkylamine. And sodium salts of sulfonated lauric acid derivatives.

Examples of the sulfobetaine include coconut 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.

On the other hand, the tin-copper-X alloy plating bath of the present invention
(Metal X = iron, cobalt, nickel, bismuth, etc.)
It goes without saying that various additives such as known antioxidants, brighteners, semi-brighteners, complexing agents, pH adjusters, and buffering agents can be mixed in addition to the above-mentioned surfactants according to the purpose. The antioxidant is intended to prevent the oxidation of tin in the bath, as specific examples thereof, ascorbic acid or a salt thereof, hydroquinone, catechol, resorcin, phloroglucin, cresolsulfonic acid or a salt thereof, phenolsulfonic acid or a salt thereof, And naphtholsulfonic acid or a salt thereof.

Examples of the above brightener include various aldehydes such as m-chlorobenzaldehyde, p-nitrobenzaldehyde, p-hydroxybenzaldehyde, 1-naphthaldehyde, benzylidene aldehyde, salicylaldehyde and paraaldehyde, vanillin, triazine, imidazole, indole, Quinoline, 2-vinylpyridine,
Aniline and the like.

As the semi-brightening agent, thioureas, N-
(3-hydroxybutylidene) -p-sulfanilic acid, N
-Butylidene sulfanilic acid, N-cinnamoylidene sulfanilic acid, 2,4-diamino-6- (2′-methylimidazolyl (1 ′)) ethyl-1,3,5-triazine,
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 benzothiazole, 2-methylbenzothiazole, 2- (methylmercapto) benzothiazole, 2-aminobenzothiazole, 2-amino-6-methoxybenzothiazole, 2-methyl-5-chlorobenzothiazole, 2-hydroxy Benzothiazole, 2-amino-6
-Methylbenzothiazole, 2-chlorobenzothiazole, 2,5-dimethylbenzothiazole, 2-mercaptobenzothiazole, 6-nitro-2-mercaptobenzothiazole, 5-hydroxy-2-methylbenzothiazole, 2-benzothiazolethio Benzothiazoles such as acetic acid are exemplified.

The above-mentioned complexing agent is mainly for stably promoting the dissolution of copper, metal X (X = iron, cobalt, nickel, bismuth, etc.) or tin in a bath. Gluconic acid, glucoheptonic acid, ethylenediamine, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), iminodiacetic acid
(IDA), iminodipropionic acid (IDP), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylenetetramine hexaacetic acid (TTHA), oxalic acid, citric acid, tartaric acid, Rochelle salt, lactic acid, malic acid, malonic acid, acetic acid Or salts thereof, thiourea or derivatives thereof. Examples of the pH adjuster include various acids such as hydrochloric acid and sulfuric acid, and various bases such as ammonium hydroxide and sodium hydroxide. Examples of the buffer include boric acids, phosphoric acids, and ammonium chloride.

The content of the various additives in the tin-copper ternary alloy plating bath of the present invention can be arbitrarily adjusted and selected according to barrel plating, rack plating, high-speed continuous plating, rackless plating, and the like. .

When electroplating is performed using the tin-copper ternary alloy plating bath of the present invention, the bath temperature is 0 ° C. or higher, preferably about 10 to 50 ° C. Cathode current density is 0.01
To 150 A / dm ² , preferably 0.1 to 30 A / dm ²
It is about. Further, the pH of the bath can be applied to a range from acidic to almost neutral, but a range from weakly acidic to strongly acidic is particularly preferable.

The present invention 6 provides a tin-copper-X alloy plating film (metal X = iron,
(Cobalt, nickel, bismuth, etc.) formed on a substrate, such as semiconductor devices, resistors, variable resistors, capacitors, filters, inductors, thermistors, crystal oscillators and other chip components, connectors, A mechanical component such as a switch, a hoop material, a wire (for example, a lead wire), and the like are included.

[0040]

In a tin-copper-X alloy plating bath (metal X = iron, cobalt, nickel, bismuth, etc.), when no surfactant is present, the polarization of copper or metal X is small.
When a current density is applied to the plating bath, these metals preferentially precipitate over tin, and it is not easy to form a ternary alloy of tin-copper-X. On the other hand, when a surfactant is contained in the tin-copper-X alloy plating bath, the polarization curve of copper and metal X changes, and the polarization of noble copper and metal X at the standard electrode potential increases, resulting in tin. Since it approaches, it can be estimated that tin is eutectoid with copper and metal X reliably at a high composition ratio.

[0041]

(1) As shown in the test examples described below, in a plating bath having no surfactant, only copper is preferentially precipitated, or copper and metal X (metal X = iron, cobalt, nickel , Bismuth, etc.), the precipitate has a very large composition ratio of copper, or a composition ratio of copper and metal X, and is inferior in solderability, and has a practical level of appearance and denseness. Can not do. On the other hand, in the present invention, since the tin-copper-X alloy plating bath contains a surfactant,
Tin can be eutectoidized smoothly with copper and metal X, and a ternary alloy plating film of tin-copper-X at a practical level can be favorably formed.
In addition, the tin-copper-based alloy plating film of the present invention is a lead-free solder film having little adverse effect on the human body and the environment.
It has high practicality.

(2) In the present invention, tin-copper-based ternary alloy plating baths include tin-copper-iron alloy, tin-copper-cobalt alloy, tin-copper-nickel alloy, tin-copper-bismuth alloy, etc. In order to limit to the specific ternary alloy plating bath, the resulting alloy plating film is excellent in solderability, can effectively prevent the occurrence of cracks during whisker and bending work, and can be used for tin-silver alloy plating film etc. The cost can also be reduced.

(3) In the present invention 3, tin-copper-X (metal X =
In a ternary alloy plating bath of iron, cobalt, nickel, bismuth, etc., the relationship between soluble stannous salt, soluble copper salt, and soluble X metal salt is expressed as: soluble copper salt / soluble stannous salt = 0.001. To 0.25 and the weight ratio of soluble X metal salt / soluble stannous salt = 0.0001 to 0.1 (see Test Examples below), so that the appearance of the coating and the solderability are improved. Alternatively, a more remarkable effect can be expected in preventing the occurrence of cracks during whisker or bending.

(4) In the present invention 2, since a nonionic surfactant is selected as the surfactant (see the test example described later),
The appearance and denseness of the deposited electrodeposition film can be more effectively improved.

[0045]

EXAMPLES Examples of tin-copper ternary alloy plating baths will be described below in order, as well as the appearance of the electrodeposited film obtained from the plating bath, the degree of occurrence of cracks during bending, the degree of occurrence of whiskers, and Various test examples such as solderability will be described. It should be noted that the present invention is not limited to the following examples and test examples, and it is needless to say that any modifications can be made within the technical idea of the present invention.

In the tin-copper alloy plating baths of the following Examples and Comparative Examples, Examples 1 to 9 and Comparative Examples 1 to 3 are examples of tin-copper-bismuth alloy plating baths. Nos. 1 to 7 indicate that Cu ²⁺ / Sn ²⁺ is 1/4 or less and Bi ³⁺ /
This is an example in which Sn ²⁺ is 0.1 or less, and basically, the type of the surfactant is variously changed. Specifically, Examples 1 and 3 and 4 are examples using a nonionic surfactant, Example 2 is an example of an anionic surfactant, Examples 6 and 7 are examples of an amphoteric surfactant, Example 5 is an example in which a nonionic surfactant and a cationic surfactant are used in combination. Further, in the weight ratio of the soluble metal salt in the bath, Example 8 is an example where Cu ²⁺ / Sn ²⁺ exceeds 1/4, and Example 9 is an example where Bi ³⁺ / Sn ²⁺ exceeds 0.1. It is. In contrast, Comparative Example 1 was a blank example of a surfactant based on Example 1, Comparative Example 2 was a blank example of a surfactant based on Example 3, and Comparative Example 3 was based on Example 4. 1 is a blank example of a surfactant (and an antioxidant). Example 4
Examples 7 to 7 are examples in which an antioxidant is added, and Example 6 is an example of a weakly acidic bath.

Examples 10 to 14 are examples of tin-copper-iron alloy plating baths. Among them, Examples 10 to 12 are Cu ²⁺ / Sn ^{2+ in terms} of the weight ratio of soluble metal salt in the bath. Is 1
/ 4 or less and Fe ²⁺ / Sn ²⁺ is 0.1 or less. Example 13 is an example where Cu ²⁺ / Sn ²⁺ exceeds 1/4, and Example 14 is an example where Fe ²⁺ / Sn ²⁺ exceeds 0.1. On the other hand, Comparative Example 4 is a blank example containing no surfactant in the tin-copper-iron alloy plating bath based on Example 10.

Examples 15 to 19 are examples of tin-copper-nickel alloy plating baths.
Is based on the weight ratio of soluble metal salts in the bath, Cu ²⁺ / S
This is an example in which n ²⁺ is 1/4 or less and Ni ²⁺ / Sn ²⁺ is 0.1 or less. Example 18 is an example where Cu ²⁺ / Sn ²⁺ exceeds 1/4, and Example 19 is an example where Ni ²⁺ / Sn ²⁺ exceeds 0.1. On the other hand, Comparative Example 5 is a blank example containing no surfactant in the tin-copper-nickel alloy plating bath based on Example 15.

Examples 20 to 24 are examples of tin-copper-cobalt alloy plating baths.
Is based on the weight ratio of soluble metal salts in the bath, Cu ²⁺ / S
This is an example in which n ²⁺ is 1/4 or less and Co ³⁺ / Sn ²⁺ is 0.1 or less. In Example 23, Cu ²⁺ / Sn ²⁺ was 1
In Example 24, the ^ratio of Co ³⁺ / Sn ²⁺ was 0.1.
It is an example that exceeds. On the other hand, Comparative Example 6 is the same as Example 2
This is an example of a blank containing no surfactant in a tin-copper-cobalt alloy plating bath based on 0.

Examples 25 and 26 were tin-copper-antimony
These are examples of alloy plating baths, all of which are soluble metals in the bath.
In terms of salt weight ratio, Cu²⁺/ Sn²⁺Is less than 1/4,
And Sb³⁺/ Sn²⁺Are examples of 0.1 or less. Also,
Comparative Example 7 is tin-copper-antimony based on Example 25.
Example of a blank containing no surfactant in the alloy plating bath
It is. Example 27 is a tin-copper-titanium alloy plating bath.
By way of example, in the weight ratio of soluble metal salts in the bath, Cu
²⁺/ Sn²⁺Is less than 1/4 and Ti³⁺/ Sn²⁺But
This is an example of 0.1 or less. Comparative Example 8 is similar to Example 27.
Surface activity in standard tin-copper-titanium alloy plating bath
This is a blank example containing no agent. Example 28 is tin-
This is an example of a copper-zirconium alloy plating bath.
In terms of the weight ratio of the reactive metal salt, Cu²⁺/ Sn²⁺Is 1/4 or more
Below and Zr²⁺/ Sn ²⁺Is less than 0.1
You. Comparative Example 9 is tin-copper based on Example 28.
-Do not include surfactants in the zirconium alloy plating bath.
This is a blank example.

(A) Examples 1 to 9 and Comparative Examples 1 to 3 of a tin-copper-bismuth alloy plating bath are shown (see FIG. 1). << Example 1 >> A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous sulfate (as Sn ²⁺ ) 20 g / L Copper sulfate (as Cu ²⁺ ) 1 g / L Bismuth sulfate (as Bi ³⁺ ) 2 g / L Sulfuric acid 100 g / L Tristyrenated phenol polyethoxylate (EO15) − Polypropoxylate (PO3) 5g / L

Example 2 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous sulfate (as Sn ²⁺ ) 20 g / L Copper sulfate (as Cu ²⁺ ) 1 g / L Bismuth sulfate (as Bi ³⁺ ) 2 g / L Sulfuric acid 100 g / L Sodium dibutylnaphthalene sulfonate 2 g / L

Example 3 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 2 g / L Bismuth sulfate (as Bi ³⁺ ) 4 g / L Methanesulfonic acid 100 g / L Lauryl alcohol polyethoxylate (EO15 ) 10g / L

Example 4 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper methanesulfonate (as Cu ²⁺ ) 2 g / L Bismuth methanesulfonate (as Bi ³⁺ ) 4 g / L Methanesulfonic acid 150 g / L α-naphthol Polyethoxylate (EO10) 10g / L Catechol 1g / L

Example 5 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous phenolsulfonate (as Sn ²⁺ ) 50 g / L Copper chloride (as Cu ²⁺ ) 4 g / L Bismuth sulfate (as Bi ³⁺ ) 8 g / L Phenolsulfonic acid 150 g / L Nonylphenol polyethoxylate (EO13) 15g / L Cetyldimethylbenzylammonium chloride 1g / L Gallic acid 1.2g / L

Example 6 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 20 g / L Copper methanesulfonate (as Cu ²⁺ ) 2 g / L Bismuth methanesulfonate (as Bi ³⁺ ) 1 g / L Methanesulfonic acid 100 g / L Sodium gluconate 200 g / L nitrilotriacetic acid 20 g / L 2-undecyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine 2 g / L ascorbic acid 2 g / L pH = 5 (adjusted with aqueous ammonia)

Example 7 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous sulfate (as Sn ²⁺ ) 15 g / L Copper sulfate (as Cu ²⁺ ) 1 g / L Bismuth sulfate (as Bi ³⁺ ) 1 g / L Citric acid 200 g / L Lauryl dimethylaminoacetate betaine 2 g / L Gallic acid 1g / L pH = 3 (adjusted with sodium hydroxide)

Example 8 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 15 g / L Bismuth sulfate (as Bi ³⁺ ) 4 g / L Methanesulfonic acid 100 g / L Lauryl alcohol polyethoxylate (EO15 ) 10g / L

Example 9 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 2 g / L Bismuth sulfate (as Bi ³⁺ ) 10 g / L Methanesulfonic acid 100 g / L Lauryl alcohol polyethoxylate (EO15 ) 10g / L

Comparative Example 1 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous sulfate (as Sn ²⁺ ) 20 g / L Copper sulfate (as Cu ²⁺ ) 1 g / L Bismuth sulfate (as Bi ³⁺ ) 2 g / L Sulfuric acid 100 g / L

Comparative Example 2 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 2 g / L Bismuth sulfate (as Bi ³⁺ ) 4 g / L Methanesulfonic acid 100 g / L

Comparative Example 3 A tin-copper-bismuth alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper methanesulfonate (as Cu ²⁺ ) 2 g / L Bismuth methanesulfonate (as Bi ³⁺ ) 4 g / L Methanesulfonic acid 150 g / L

(B) Example 1 of tin-copper-iron alloy plating bath
0 to 14 and Comparative Example 4 are shown (see FIG. 2A). Example 10 A tin-copper-iron alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 7 g / L Ferrous sulfate (as Fe ²⁺ ) 0.5 g / L Methanesulfonic acid 100 g / L Tristyrenation Phenol polyethoxylate (EO15)-polypropoxylate (PO3) 10 g / L

Example 11 A tin-copper-iron alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 7 g / L Ferrous sulfate (as Fe ²⁺ ) 3 g / L Methanesulfonic acid 100 g / L Tristyrenated phenol poly Ethoxylate (EO15)-Polypropoxylate (PO3) 10g / L

Example 12 A tin-copper-iron alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 1 g / L Ferrous sulfate (as Fe ²⁺ ) 0.5 g / L Methanesulfonic acid 100 g / L Tristyrenation Phenol polyethoxylate (EO15)-polypropoxylate (PO3) 10 g / L

Example 13 A tin-copper-iron alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 20 g / L Ferrous sulfate (as Fe ²⁺ ) 0.5 g / L Methanesulfonic acid 100 g / L Tristyrenation Phenol polyethoxylate (EO15)-polypropoxylate (PO3) 10 g / L

Example 14 A tin-copper-iron alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 7 g / L Ferrous sulfate (as Fe ²⁺ ) 6 g / L Methanesulfonic acid 100 g / L Tristyrenated phenol poly Ethoxylate (EO15)-Polypropoxylate (PO3) 10g / L

Comparative Example 4 A tin-copper-iron alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 7 g / L Ferrous sulfate (as Fe ²⁺ ) 0.5 g / L Methanesulfonic acid 100 g / L

(C) Examples 15 to 19 of the tin-copper-nickel alloy plating bath and Comparative Example 5 are shown (see FIG. 2B).
Example 15 A tin-copper-nickel alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 3 g / L Nickel sulfate (as Ni ²⁺ ) 1 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Example 16 A tin-copper-nickel alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 9 g / L Nickel sulfate (as Ni ²⁺ ) 1 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Example 17 A tin-copper-nickel alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 3 g / L Nickel sulfate (as Ni ²⁺ ) 4 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Example 18 A tin-copper-nickel alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 25 g / L Nickel sulfate (as Ni ²⁺ ) 1 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Example 19 A tin-copper-nickel alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 3 g / L Nickel sulfate (as Ni ²⁺ ) 7 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Comparative Example 5 A tin-copper-nickel alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 3 g / L Nickel sulfate (as Ni ²⁺ ) 1 g / L Methanesulfonic acid 100 g / L

(D) Examples 20 to 24 of the tin-copper-cobalt alloy plating bath and Comparative Example 6 are shown (see FIG. 3A). Example 20 A tin-copper-cobalt alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 3 g / L Cobalt sulfate (as Co ³⁺ ) 1 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Example 21 A tin-copper-cobalt alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 9 g / L Cobalt sulfate (as Co ³⁺ ) 1 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Example 22 A tin-copper-cobalt alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 3 g / L Cobalt sulfate (as Co ³⁺ ) 4 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Example 23 A tin-copper-cobalt alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 25 g / L Cobalt sulfate (as Co ³⁺ ) 1 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Example 24 A tin-copper-cobalt alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 3 g / L Cobalt sulfate (as Co ³⁺ ) 7 g / L Methanesulfonic acid 100 g / L β-naphthol polyethoxylate ( EO10) 8g / L

Comparative Example 6 A tin-copper-cobalt alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Copper sulfate (as Cu ²⁺ ) 3 g / L Cobalt sulfate (as Co ³⁺ ) 1 g / L Methanesulfonic acid 100 g / L

(E) Examples 25 to 26 of the tin-copper-antimony alloy plating bath and Comparative Example 7 are shown (see FIG. 3B). Example 25 A tin-copper-antimony alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 20 g / L Copper methanesulfonate (as Cu ²⁺ ) 2 g / L Antimony chloride (as Sb ³⁺ ) 1 g / L Methanesulfonic acid 100 g / L Sodium gluconate 200 g / L L Nitrilotriacetic acid 20 g / L 2-undecyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine 2 g / L Ascorbic acid 2 g / L pH = 5 (adjusted with aqueous ammonia)

Example 26 A tin-copper-antimony alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 20 g / L Copper methanesulfonate (as Cu ²⁺ ) 2 g / L Antimony chloride (as Sb ³⁺ ) 0.5 g / L Methanesulfonic acid 100 g / L Sodium gluconate 200 g / L nitrilotriacetic acid 20 g / L 2-undecyl-1-carboxymethyl-1-hydroxyethylimidazolinium betaine 2 g / L ascorbic acid 2 g / L pH = 5 (adjusted with aqueous ammonia)

Comparative Example 7 A tin-copper-antimony alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 20 g / L Copper methanesulfonate (as Cu ²⁺ ) 2 g / L Antimony chloride (as Sb ³⁺ ) 1 g / L Methanesulfonic acid 100 g / L Sodium gluconate 200 g / L L Nitrilotriacetic acid 20 g / L Ascorbic acid 2 g / L pH = 5 (adjusted with aqueous ammonia)

(F) Example 27 and Comparative Example 8 of the tin-copper-titanium alloy plating bath are shown (see FIG. 4A). << Example 27 >> A tin-copper-titanium alloy plating bath was constructed with the following composition. Stannous phenolsulfonate (as Sn ²⁺ ) 50 g / L Copper chloride (as Cu ²⁺ ) 4 g / L Titanium chloride (as Ti ³⁺ ) 3 g / L Phenolsulfonic acid 150 g / L Nonylphenol polyethoxylate (EO13) 15g / L Cetyldimethylbenzylammonium chloride 1g / L Gallic acid 1.2g / L

Comparative Example 8 A tin-copper-titanium alloy plating bath having the following composition was prepared. Stannous phenolsulfonate (as Sn ²⁺ ) 50 g / L Copper chloride (as Cu ²⁺ ) 4 g / L Titanium chloride (as Ti ³⁺ ) 3 g / L Phenolsulfonic acid 150 g / L Gallic acid 1.2 g / L

(G) Example 28 and Comparative Example 9 of a tin-copper-zirconium alloy plating bath are shown (see FIG. 4B). Example 28 A tin-copper-zirconium alloy plating bath having the following composition was prepared. Stannous phenolsulfonate (as Sn ²⁺ ) 50 g / L Copper chloride (as Cu ²⁺ ) 4 g / L Zirconium chloride (as Zr ²⁺ ) 3 g / L Phenolsulfonic acid 150 g / L Nonylphenol polyethoxylate (EO13) 15g / L Cetyldimethylbenzylammonium chloride 1g / L Gallic acid 1.2g / L

Comparative Example 9 A tin-copper-zirconium alloy plating bath having the following composition was prepared. Stannous phenolsulfonate (as Sn ²⁺ ) 50 g / L Copper chloride (as Cu ²⁺ ) 4 g / L Zirconium chloride (as Zr ²⁺ ) 3 g / L Phenolsulfonic acid 150 g / L Gallic acid 1.2 g / L

<< Measurement Test Example of Film Thickness, Composition and Appearance of Plating Film >> Then, Examples 1 to 28 and Comparative Examples 1 to
Using a ternary alloy plating bath of each tin-copper-X (X = bismuth, iron, nickel, cobalt, antimony, titanium, and zirconium; the same applies to the following test examples), a 42 alloy plate (25 × 25 mm), electroplating was performed under the conditions of the cathode current density (A / dm ² ), plating time (min), and bath temperature (° C.) shown in the left column of FIG. The film thickness was measured using a film thickness meter (manufactured by Seiko Denshi Kogyo; SFT3300S), and the appearance of the film was visually observed. Further, the plating film was dissolved at 70 ° C. with reverse aqua regia, and the composition of the film was measured by an atomic absorption spectrophotometry. The evaluation criteria for the appearance test are as follows. A: White uniform appearance. ：: Gray uniform appearance. Δ: Color tone was uneven. ×: A black appearance was observed, or a powder or dendrite was precipitated.

The results are shown in the center columns of FIGS. When the test results of each tin-copper-X alloy plating bath were observed for each type of bath, the weight ratio of soluble metal salt was Cu ²⁺
/ Sn ²⁺ is 以下 or less and X ^{n +} (n = 2 or 3) /
Looking at the examples in which Sn ²⁺ is 0.1 or less (for example, in the case of a tin-copper-bismuth alloy plating bath, see Examples 1 to 7), regardless of the type of the plating bath, the copper in the deposited plating film Is 1
It was 0% by weight or less, and the maximum of metal X was 9.2% by weight in the case of Bi (see Example 5). On the other hand, Cu ²⁺ / Sn ²⁺ is １ ／ in weight ratio of soluble metal salt.
(For example, in the case of a tin-copper-bismuth alloy plating bath, see Example 8), the composition ratio of copper in the deposited plating film increases, but stays at around 20% by weight at the maximum. On the contrary, X ^{n +} / Sn ²⁺ is 0.1.
(For example, in the case of a tin-copper-bismuth alloy plating bath, see Example 9), the composition ratio of the metal X in the deposited plating film is increased, but also at a maximum of 10%.
It was less than a little by weight. These results were the same regardless of the type of plating bath. This ensures that tin has a high composition ratio and is eutectoid with copper and metal X, and a specific tin-copper ternary alloy (tin-copper-X alloy) plating film is formed smoothly. Was confirmed. In particular, it is noted that a tin-copper-titanium alloy or a tin-copper-zirconium alloy can be formed. In contrast, in the plating baths of Comparative Examples 1 to 9, copper was preferentially precipitated, and particularly in Comparative Examples 1 to 3 of the tin-copper-bismuth alloy plating bath, copper and bismuth were both preferentially precipitated. .

Regarding the appearance of the plating film, regardless of the type of bath,
In Examples in which Cu ²⁺ / Sn ²⁺ is １ ／ or less and X ^{n +} / Sn ²⁺ is 0.1 or less, the evaluation is の to ○, and one of the above two conditions is evaluated. In an embodiment having a large weight ratio,
O was evaluated. In Comparative Examples 1 to 9, as a result of the preferential precipitation of copper as described above, the powder was substantially in the form of powder or dendrite, and did not form a body as a plating film.
Met. By the way, the appearance of the plating film is often affected by the type or concentration of the soluble metal salt or complexing agent, etc., but attention was paid to the tin-copper-bismuth alloy plating bath. Observing the results, as can be seen from the comparison between Examples 1 and 3 to 7 and Example 2, when a nonionic surfactant is generally selected as the surfactant, the evaluation of the film appearance tends to improve to ◎. It was strong.

<< Example of crack generation test at bending process >>
Each tin-copper of Examples 1-28 and Comparative Examples 1-9
Using an X alloy plating bath, electroplating is performed on a lead frame made of 42 alloy under the same conditions as in the test example of the above appearance and the like, and it is bent only once at 90 degrees, and the outer surface of the bent portion where the tensile force is concentrated. The scanning electron microscope (1000
Microscopic observation). The evaluation criteria for this test are as follows. A: No crack. ：: The average value of the crack width was 0.5 μm or less. Δ: The average value of the crack width was 0.5 μm or more. In addition, as can be seen from the results of the plating appearance test, the precipitates of Comparative Examples 1 to 9 do not form a plating film,
The bending test could not be performed because it was extremely insufficient.

The second column from the right of FIGS. 1 to 4 shows the results. Regardless of the type of plating bath, in the examples where X ^{n +} / Sn ²⁺ is 0.1 or less in the weight ratio of the plating bath, the composition ratio of metal X in the obtained film is small, and the bending test result is as follows. In the examples where X ^{n +} / Sn ²⁺ exceeds 0.1, the composition ratio of the metal X is increased, and the bending test result is generally evaluated as Δ. For example, in the tin-copper-bismuth alloy plating bath, the evaluations of Examples 6 to 7 were ◎, and the evaluation of Example 9 was △.
(See FIG. 1). In the tin-copper-nickel alloy plating bath, the evaluation of Example 15 was ○, and the evaluation of Example 19 was △ (see FIG. 2B). In the tin-copper-cobalt alloy plating bath, the evaluation of Example 20 was ○, and the evaluation of Example 24 was △ (see FIG. 3A). However, in the tin-copper-iron alloy plating bath, the evaluation of Example 13 in which Cu ²⁺ / Sn ²⁺ exceeded 1/4 was Δ, and conversely, X ^{n +} / Sn
The evaluation of Example 14 in which ²⁺ exceeded 0.1 was evaluated as ○ (FIG. 2).
A). Also, tin-copper-nickel alloy, tin-copper-
In the cobalt alloy plating bath, the evaluations of Examples 18 and 23 where Cu ²⁺ / Sn ²⁺ exceeded 1/4 were △ (FIG. 2B,
(See FIG. 3A).

<< Example of Whisker Generation Test >>
28 and each of the tin-copper-X alloy plating baths of Comparative Examples 1 to 9 under the same conditions as in the above-described test examples such as appearance, and
Electroplating was performed on a four-piece lead frame, and the temperature was 8
After being stored for one month under the conditions of 5 ° C. and 85% relative humidity, the surface of the plating was microscopically observed using a scanning electron microscope (× 1000). The evaluation criteria for the whisker test are as follows. ：: No whisker was observed. X: One or more whiskers were observed. In addition, the whisker test could not be performed because the precipitates of Comparative Examples 1 to 9 did not form the body of the plating film or were extremely insufficient.

The results are shown in the third column from the right in FIGS. Regardless of the type of the plating bath, the examples were all evaluated as ○, and it was revealed that the tin-copper ternary alloy of the present invention can effectively prevent the generation of whiskers.

<< Test Example of Solderability >>
28 and each of the tin-copper-X alloy plating baths of Comparative Examples 1 to 9 under the same conditions as in the above whisker test example.
Electroplating was performed on a lead frame made of 94 materials, aging was performed at a temperature of 105 ° C. and a relative humidity of 100% for 8 hours, and each of the obtained samples was immersed in a solder bath under the following conditions to obtain a zero cross time (sec. ) Was measured. Solder bath: Sn-2 wt% Ag-3 wt% Bi-0.
75 wt% Cu flux: 25 wt% rosin in isopropyl alcohol Temperature: 250 ° C. Time: 5 seconds Immersion speed: 25 mm / sec Immersion depth: 2 mm

The rightmost columns in FIGS. 1 to 4 show the results. In Examples 1 to 28, the zero cross time was extremely small regardless of the type of the plating bath. That is, when the respective examples were compared with Comparative Examples 1 to 9 having a large zero-crossing time between plating baths of the same type, it was revealed that the plating films of the respective examples had excellent solderability. In addition, when focusing on the test results for each type of plating bath, comparing the zero cross times between the examples in which the soluble copper salt concentration in the bath is different, the examples of Examples in which Cu ²⁺ / Sn ²⁺ is １ ／ or less are obtained. The zero cross time was smaller than that of the examples in which Cu ²⁺ / Sn ²⁺ exceeded １ ／. For example, in a tin-copper-bismuth alloy plating bath, the zero cross time of Example 1 was smaller than that of Example 8, confirming that the solderability was further improved.

[Brief description of the drawings]

FIG. 1 shows the coating composition, appearance, degree of cracking during folds, degree of whisker generation, and soldering of the electrodeposited films obtained from the tin-copper-bismuth alloy plating baths of Examples 1 to 9 and Comparative Examples 1 to 3. 5 is a table showing the results of various tests such as attaching properties.

FIG. 2A is a chart showing various test results of each tin-copper-iron alloy plating bath of Examples 10 to 14 and Comparative Example 4.
FIG. 2B is a chart showing various test results of the tin-copper-nickel alloy plating baths of Examples 15 to 19 and Comparative Example 5.

FIG. 3A is a table showing various test results of each of the tin-copper-cobalt alloy plating baths of Examples 20 to 24 and Comparative Example 6, and FIG. 3B is a table showing each of the tin-copper-cobalt alloy plating baths of Examples 25 to 26 and Comparative Example 7. It is a table | surface which shows the various test results of a copper-antimony alloy plating bath.

FIG. 4A is a graph showing the tin content of each of Examples 27 and Comparative Example 8.
4B is a chart showing various test results of the copper-titanium alloy plating bath, and FIG. 4B is a chart showing various test results of the tin-copper-zirconium alloy plating baths of Example 28 and Comparative Example 9.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Keigo Obata 21 Futami-cho, Futami-cho, Akashi City, Hyogo Prefecture 8 Inside Daiwa Kasei Research Laboratories (72) Inventor Takao Takeuchi 21 Futami-cho, Futami-cho, Akashi-shi, Hyogo 8 Daiwa Chemical Research Laboratories F Term (Reference) 4K023 AB34 BA06 BA26 BA29 CB03 CB05 CB13 CB21 CB28 CB33 DA02 DA06 DA07 DA08 4K024 AA21 BB09 CA01 CA02 CA03 CA04 CA06 GA16

Claims (6)

[Claims] 1. A soluble stannous salt, (B) a soluble copper salt, (C) iron, cobalt, nickel, bismuth, antimony,
A tin-copper alloy plating bath containing at least one soluble salt of a third component metal selected from the group consisting of titanium and zirconium, and (D) a surfactant. 2. The method according to claim 1, wherein the surfactant is C ₁ to C ₁ .
C ₂₀ alkanols, phenol, naphthol, bisphenol, C ₁ -C ₂₅ alkyl phenols, aryl phenols, C ₁ -C ₂₅ alkyl naphthol, C ₁
-C ₂₅ alkoxylated phosphoric acid, sorbitan ester, polyalkylene glycol, C ₁ -C ₂₂ aliphatic amine, C ₁
Tin, characterized in that -C ₂₂ a nonionic surfactant consisting of adducts of ethylene oxide and / or propylene oxide, such as fatty amide - copper alloy plating baths. 3. A soluble stannous salt, (B) a soluble copper salt, (C) iron, cobalt, nickel, bismuth, antimony,
At least one soluble salt of a third component metal selected from the group consisting of titanium and zirconium; (D) organic acids such as organic sulfonic acids, aliphatic carboxylic acids, oxycarboxylic acids, and aminocarboxylic acids; A tin-copper alloy plating bath containing at least one kind. 4. A method according to claim 1, wherein the soluble stannous salt, the soluble copper salt and the soluble metal salt of the third component are contained in the plating bath at a ratio of 0.001 to 0.25 of soluble copper salt / soluble stannous salt. 3 components soluble metal salt / soluble stannous salt = 0.0001 to 0.1
4. The composition of claim 1, wherein the weight ratio is
The tin-copper alloy plating bath according to any one of the above. 5. A tin-copper alloy plating bath, wherein the plating bath according to claim 1 further comprises an antioxidant. 6. A semiconductor device, a connector, a switch, a resistor, and a tin-copper alloy plating film formed on a substrate by electroplating using the plating bath according to claim 1. Electronic components such as variable resistors, capacitors, filters, inductors, thermistors, crystal units, and lead wires.