JPH11152594A - Tin and tin alloy plating bath and preparation of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the transparency of a plating bath with the elapse of time by incorporating a soluble salt composed of one of a stannous salt and a mixture of the stannous salt with a metallic salt such as lead, one or more kinds of acids among organic acids and inorganic acids and one ore more kinds of antioxidants. SOLUTION: As the antioxidant contained in a tin and a tin alloy plating bath, phenols expressed by the formula are exemplified. In the formula, R is SO3 X (X is hydrogen, a metal such as Na, K and Ca, NH4 or the like), COOY (Y is hydrogen, a metal such as Na, K and Ca), CH3 , OCH3 , CH2 OH, CH2 CH2 OH, NH2 and a halogen, (n) is integer of 1-4 and (m) is integer of 1-2. Wherein, when m=2, R is substituents same as or different from each other. When n=1 and m=1, R is a group except SO3 H. When n=1 and m=2, R is a group except the combination of SO3 H with CH3 . When n=2 and m=1, R is a group except SO3 X.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a tin and tin alloy plating bath for electroplating and a method for preparing the same. The present invention relates to a novel antioxidant or a coagulation accelerator for controlling the generation of stannic oxide in the bath. The present invention provides a plating bath capable of promoting aggregation of the fine particles and effectively removing the fine particles even if suspended particles of stannic oxide are generated by long-term use of the bath.

[0002]

BACKGROUND OF THE INVENTION In recent years, tin plating baths or tin alloy plating baths such as tin-lead alloys have been widely used as coatings for improving solderability and for surface treatment of electronic components such as semiconductor devices, connectors and chip components. It's being used. In the field of the tin or tin alloy plating bath, hydrochloric acid,
Sulfuric acid, plating baths based on inorganic acids such as hydrofluoric acid, and organic acids such as organic sulfonic acids and aliphatic carboxylic acids are used.
BACKGROUND ART Plating baths based on organic sulfonic acids such as alkanesulfonic acids and alkanolsulfonic acids are widely used because of their low corrosiveness.

However, in such a tin or tin alloy plating bath, in general, stannous ions in the bath undergo oxidation or anodic oxidation by oxygen in the air and become stannic ions as the bath is used for a long time. Further, the ions are hydrolyzed to generate stannic oxide fine particles. The particle diameter of the stannic oxide fine particles is 0.1 μm to several μm.
, The particles are dispersed as suspended particles without settling in the plating bath, and the transparency of the plating bath is significantly reduced.

[0004] Usually, a filtering device is attached to the plating apparatus for the purpose of removing foreign substances mixed in the plating bath, and the plating bath is continuously filtered. However, the pore size of the filter used for filtration is several μm to several tens μm due to pressure loss, easiness of maintenance, or restrictions such as cost.
The fine particles of the stannic oxide suspended in the plating bath are finer than the pore size of the filter, and it is almost difficult to capture and remove the fine particles with a filter. Was.

On the other hand, fine particles of stannic oxide generated in a tin or tin alloy plating bath are considered to have many water molecules adsorbed on the surface thereof. Is applied, stannic oxide particles adsorbing many water molecules are eutectoid in the electrodeposition film. As described above, when many water molecules are contained in the plating film together with stannic oxide, water is vaporized due to heat generated when the plated component is soldered, and the volume expands greatly. There is a problem that voids (bubbles) occur in the part.

In recent years, since electronic components have been miniaturized year by year and the area to be joined by soldering has also been miniaturized, it has been strongly required to ensure the reliability of the joining strength at the joining portion. When such voids occur, the reliability of the bonding strength is significantly impaired. For this reason,
In a tin or tin alloy plating bath, it is an important issue to remove stannic oxide generated during long-term use.

[0007]

2. Description of the Related Art Japanese Patent Laid-Open Publication No. Sho 56-116894 discloses a conventional electroplating bath for tin, in which the conductivity of the plating bath is increased, and the drainage treatment is easier than that of a conventional acidic or alkaline bath. Hydrazine, hypophosphorous acid, phosphorous acid, etc. for the purpose of preventing oxidation of divalent tin to this based on neutral plating bath of pyrophosphoric acid
A tin plating bath to which ascorbic acid or a salt thereof is added is disclosed.

Further, as a prior art 2 of a tin-lead alloy electroplating bath, JP-A-59-193296 describes
Hydrazine dichloride as a reducing agent for reducing tetravalent tin to divalent based on stannous chloride, lead acetate and hydrochloric acid,
Or tin added with hydroquinone, hypophosphorous acid, etc.
A lead alloy plating bath is disclosed.

[0009]

The above prior art 1 or 2
Are both antioxidants such as hydroquinone and hypophosphorous acid
(Or a reducing agent) is added to the plating bath to prevent oxidation of stannous ions (Sn ²⁺ ) in the electroplating bath.
Although there is an effect of delaying the oxidation rate of stannous ions to some extent, suspended particles of stannic oxide are generated from about 2 to 3 months of use, and the transparency of the plating bath is often lost. Then, once the quality of the plating bath is reduced to such a state, it is difficult to remove the plating bath as described above, so that the reliability of the bonding strength of the electrodeposition film obtained from the plating bath can be secured. Disappears.

As described above, in a tin or tin alloy electroplating bath, fine particles of stannic oxide cause voids. Therefore, first, the generation of stannic oxide is effectively suppressed, and at the same time, Even when fine particles of stannic oxide are generated, it is practical to take measures to smoothly remove the fine particles. An object of the present invention is to stabilize the transparency of a tin or tin alloy plating bath over time based on this policy.

[0011]

Means for Solving the Problems The present inventors have studied to suppress the oxidation of stannous ions in a tin plating bath or a tin alloy plating bath such as a tin-lead alloy, and have studied the oxides thereof. That is, the behavior of stannic oxide in a bath was examined. Generally, fine particles of stannic oxide generated in a tin plating bath or a tin alloy plating bath are extremely unlikely to grow or agglomerate, and have the property of existing as fine particles. Therefore, the present inventors have proposed that when stannic oxide fine particles are generated in a plating bath, the crystal growth of the stannic oxide fine particles is promoted or the fine particles are united and aggregated to form particles. By increasing the diameter, these particles can be trapped by filtration and removed from the plating bath,
The idea was to stabilize the clarity of the bath over time. The present applicant has conducted intensive research based on this idea,
It has been found that a specific phosphorus compound promotes agglomeration of stannic oxide fine particles to increase the particle diameter, and has previously been proposed in Japanese Patent Application No. 9-165322.

On the other hand, as described above, the present inventors proceeded with research on the first problem of suppressing oxidation of stannous ions in a tin plating bath or a tin alloy plating bath,
First, specific phenols and naphthols having a predetermined number of hydroxyl groups and a functional group other than a hydroxyl group at a predetermined position not only have an antioxidant effect, but also have the above-described aggregation promoting effect of stannic oxide. I found something new. Next, the present inventors have found that a specific organic acid or a salt thereof different from the above-mentioned compound of the prior application, and an analog of the phosphorus compound are excellent in promoting the aggregation of stannic oxide. Then, it was confirmed that stabilization with time of the transparency of the tin or tin alloy plating bath could be achieved by utilizing these novel antioxidants and aggregation promoters, and the present invention was completed.

That is, the present invention relates to (A) a stannous salt and a salt of a stannous salt and a metal selected from lead, silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony. And (B) alkanesulfonic acid, alkanolsulfonic acid, organic acids such as aliphatic carboxylic acids, or selected from inorganic acids such as hydrochloric acid, sulfuric acid, and borofluoric acid. At least one kind of acid,
(C) at least one antioxidant represented by the following formulas (1) and (2),

Embedded image (In the formula (1), R is SO ₃ X (X is a metal such as hydrogen, sodium, potassium, calcium, NH ₄ or the like), COOY (Y is a metal such as hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH _2, is halogen; n is an integer of from 1 to 4; m is an integer of 1-2, provided that when the m = 2, R
Are the same or different substituents; n = 1, m = 1
R excludes SO ₃ H; n = 1, m = 2;
R excludes the combination of SO ₃ H and CH ₃ ; n = 2, m =
If 1, R excludes SO ₃ X. )

Embedded image (In the formula (2), R is SO ₃ X (X is hydrogen, sodium, potassium, calcium, etc., NH ₄ etc.), COOY (Y is hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH _2, is halogen; n is an integer of from 1 to 4; m is an integer of 1-2, provided that when the m = 2, R
Are the same or different substituents from each other; when n and m = 1, R excludes SO ₃ H. ), Which is a tin and tin alloy plating bath.

The present invention 2 is the invention according to the above-mentioned invention 1, wherein (1)
The antioxidant of the formula is at least one of the compounds represented by the following formulas (3) to (4)

Embedded image (In the formula (3), R is SO ₃ X (X is hydrogen, sodium, potassium, calcium, etc., NH ₄ etc.), COOY (Y is hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ and halogen. )

Embedded image (In the formula (4), R is SO ₃ X (X is a metal such as hydrogen, sodium, potassium, calcium, NH ₄ or the like), COOY (Y is a metal such as hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ and halogen. ).

The present invention 3 is the invention according to the above invention 1 or 2, wherein the antioxidant of the formula (2) is at least one of the compounds represented by the following formulas (5) to (6):

Embedded image (In the formula (5), R is SO ₃ X (X is hydrogen, sodium, potassium, calcium, etc., NH ₄ etc.), COOY (Y is hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ and halogen. )

Embedded image (In the formula (6), R is SO ₃ X (X is hydrogen, sodium, potassium, calcium or the like, NH ₄ or the like), COOY (Y is hydrogen, sodium, potassium, calcium or the like, N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ and halogen. ).

The present invention provides a mixture of (A) a stannous salt and a salt of a stannous salt and a metal selected from lead, silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony. And (B) at least one selected from organic acids such as alkanesulfonic acid, alkanolsulfonic acid, and aliphatic carboxylic acid, or at least one selected from inorganic acids such as hydrochloric acid, sulfuric acid, and borofluoric acid. Acid of (C)
Tartaric acid, sodium tartrate, ammonium tartrate, potassium tartrate, calcium tartrate, magnesium tartrate,
Tin containing at least one coagulation accelerator for stannic oxide fine particles selected from tartrate such as Rochelle salt, sodium monohydrogen phosphate and hydrogen phosphate such as ammonium dihydrogen phosphate And a tin alloy plating bath.

[0017] The present invention 5 is a tin and tin alloy plating bath characterized in that it further contains a surfactant in addition to the plating bath of any of the above-mentioned present inventions 1-4.

[0018] The present invention 6 is a tin and tin alloy plating bath characterized in that it further contains a brightener in addition to the plating bath of any of the above-mentioned present inventions 1 to 5.

[0019] The present invention 7 is a tin and tin alloy plating bath characterized by further containing a semi-brightening agent in addition to the plating bath of any of the above-mentioned present inventions 1 to 6.

[0020] The present invention 8 includes the above-mentioned inventions 1 to 3 and 5 to 7
In any one of the plating baths, an antioxidant is preliminarily mixed with at least one of an acid, a soluble metal salt, a surfactant, a brightener, and a semi-brightener, and the mixture is added to the remaining bath components at the time of building bath. And a method for preparing a tin and tin alloy plating bath.

According to a ninth aspect of the present invention, in the plating bath according to any one of the fourth to seventh aspects, the coagulation promoter is an acid, a soluble metal salt,
A method for preparing a tin and tin alloy plating bath, characterized in that the mixture is previously mixed with at least one of a surfactant, a brightener, or a semi-brightener, and that the mixture is mixed with the remaining bath components at the time of bathing. is there.

A tenth aspect of the present invention provides a tin and tin antioxidant according to any one of the first to third aspects, wherein the antioxidant is added to a concentrated aqueous solution of a tin salt to suppress oxidation of stannous ions in the aqueous solution. This is a method for storing a tin salt aqueous solution for a tin alloy plating bath.

The present invention 11 is selected from catechol, hydroquinone, resorcin, pyrogallol, phloroglucin, phenolsulfonic acid, cresolsulfonic acid, catecholsulfonic acid, hydroquinonesulfonic acid, naphtholsulfonic acid, ascorbic acid, and salts thereof. A method for storing a tin salt aqueous solution for a tin and tin alloy plating bath, characterized in that at least one antioxidant is added to a concentrated aqueous solution of a tin salt to suppress oxidation of stannous ions in the aqueous solution.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The antioxidant of the present invention 1 is generally represented by the above-mentioned specific phenols of the formula (1) and the specific naphthols of the formula (2). Examples thereof include catechols having one substituent represented by the formula (3) and pyrogallols having one substituent represented by the formula (4). Further, the divalent naphthols of the formula (2) include 2,3-having a substituent at the 6-position represented by the formula (5).
Dihydroxynaphthalene and 2,3-dihydroxynaphthalene having a substituent at the 5-position represented by the formula (6) are preferable.

Specific examples of the catechols of the above formula (3) are as follows. 3,4-dihydroxybenzoic acid (see formula (7) below)

Embedded image 4-methoxycatechol (see formula (8) below)

Embedded image 3,4-dihydroxybenzyl alcohol ((9) below)
(See formula)

Embedded image 4-methylcatechol (see formula (10) below)

Embedded image Catechol sodium polysulfonate (including Tiron; see formula (11) below)

Embedded image (In the formula (11), n is 2, 3, and 4.)

Specific examples of the pyrogallols of the above formula (4) include:
And gallic acid (see the following formula (12)).

Embedded image

The compounds contained in the phenols of the above formula (1) may be those which do not belong to the polyhydric phenols of the formulas (3) and (4). It is as follows. o-Methoxyphenol (common name guaiacol, see the following formula (13))

Embedded image 2 (4-hydroxyphenyl) ethyl alcohol (see formula (14) below)

Embedded image

On the other hand, specific examples of the divalent naphthols of the above formula (5) or (6) are as follows. 2,3-dihydroxynaphthalene-6-sulfonic acids
(See formula (15) below)

Embedded image (In the formula (15), X is hydrogen, a metal such as sodium, potassium, calcium, NH ₄ or the like.) 2,3-Dihydroxynaphthalene-5-sulfonic acids
(See formula (16) below)

Embedded image (In the formula (16), X is hydrogen, a metal such as sodium, potassium, calcium or the like, NH ₄ or the like.)

The compounds contained in the naphthols of the above formula (2) may be those which do not belong to the polyvalent naphthols of the formulas (5) and (6). 2-Naphthol-6,8-disulfonic acid dipotassium
(See formula (17) below).

Embedded image

In the antioxidant of the above formula (1), the number n of the hydroxyl groups bonded to the benzene ring is 1 to 4, and the number m of the substituent R is 1 to 2. When there are two substituents R, both may be the same substituent or may be different such as a sulfonic acid group and a carboxyl group. However, when both the hydroxyl group and the substituent are one, the substituent R excludes a sulfonic acid group, and when the number of the hydroxyl group is one and the substituent is two, the substituent R is a combination of a sulfonic acid group and a methyl group. In the case where there are two hydroxyl groups and one substituent, the substituent R excludes a sulfonic acid group (or a salt thereof). In other words, from the phenols of the formula (1) to phenolsulfonic acid,
Cresol sulfonic acid and catechol sulfonic acids are excluded.

In the antioxidant of the above formula (2), the number n of the hydroxyl groups bonded to the naphthalene ring is from 1 to 4, and the number m of the substituent R is from 1 to 2. When there are two substituents R,
Both may be the same substituent, or may be different such as a sulfonic acid group and a carboxyl group. However, when both the hydroxyl group and the substituent are one, the substituent R excludes a sulfonic acid group, in other words, α-naphtholsulfonic acid, β-naphtholsulfonic acid and the like are excluded from the naphthols of the formula (2). .

The addition amount of the antioxidants of the present invention 1 to 3 is generally 0.05 to 50 g / L, preferably 0.1 to 10 g / L, based on the whole plating bath.

The above-mentioned coagulation accelerator is the following compound. Tartaric acid or tartrate such as sodium tartrate, ammonium tartrate, potassium tartrate, calcium tartrate, magnesium tartrate, Rochelle salt (potassium sodium tartrate), sodium monohydrogen phosphate, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate Hydrogen Phosphate The coagulation accelerator can be used alone or in combination. The amount of the coagulation accelerator is generally 0.01 to 100 g / L, preferably 0.05 to 10 g / L, more preferably 0.1 to 100 g / L based on the entire plating bath. 1 to
It is 5 g / L.

The present invention is directed to tin plating baths and tin alloy plating baths, which, as described above, contain tin, lead, silver, zinc, bismuth, indium, nickel, cobalt, copper, gold, An alloy with a metal selected from antimony. Specifically, tin-lead, tin-zinc, tin-silver, tin-bismuth, tin-nickel, tin-indium, tin-cobalt, tin-copper, tin-gold, tin-
In addition to binary tin alloys such as antimony, ternary tin alloys such as tin-nickel-zinc and tin-copper-zinc are also included. As the mixture of the stannous salt or the stannous salt and the salt of a metal other than tin, any soluble salts can be used, and salts with the above-mentioned acids (particularly, organic sulfonic acids) are preferable. And the total concentration of the other metals (added amount as a metal) is generally 5 to 100 g / L.

Examples of the above-mentioned acids include alkanesulfonic acid, which has a relatively mild reaction in a plating bath and is easily treated for drainage.
Organic sulfonic acids such as alkanolsulfonic acids or organic acids such as aliphatic carboxylic acids are preferred, but inorganic acids such as hydrochloric acid, hydrofluoric acid, sulfuric acid, hydrofluorosilicic acid and perchloric acid may also be selected. it can. The above acids are used alone or in combination, and the amount of the acid added is generally 0.1 to 400 g / L,
Preferably it is 70-150 g / L.

As the alkanesulfonic acid, those represented by the chemical formula C _n H _{2n + 1} SO ₃ H (for example, n = 1 to 11) can be used. Specifically, methanesulfonic acid, ethanesulfonic acid, Examples thereof include 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid, hexanesulfonic acid, decanesulfonic acid, and dodecanesulfonic acid.

[0037] 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
~ 2, p = 1 ~ 10), specifically, 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-
In addition to 1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 2-hydroxypentane-1-sulfonic acid, etc., 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.

As the aliphatic carboxylic acid, generally,
A carboxylic acid having 1 to 6 carbon atoms can be used. In particular,
Acetic acid, propionic acid, butyric acid, citric acid, tartaric acid, gluconic acid, sulfosuccinic acid and the like can be mentioned.

In the tin or tin alloy plating bath of the present invention,
By adding a surfactant, the plating appearance can be improved and a dense plating film can be obtained. As the surfactant, at least one of a nonionic surfactant, a cationic surfactant, an anionic surfactant, and an amphoteric surfactant can be used.

[0040] Specific examples of the nonionic surfactants, 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 (salt), sorbitan esters, styrenated phenols, polyalkylene glycols, C ₁ -C ₂₂ aliphatic amines, C ₁ -C _22, such as ethylene oxide aliphatic amides (EO) and / or propylene oxide ( the PO) and those engaged 2-300 mol adduct condensation, and the like C ₁ -C ₂₅ alkoxylated phosphoric acid (salt).

Examples of the C ₁ -C ₂₀ alkanol 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. Examples of the alkyl group of the C ₁ -C ₂₅ alkyl naphthol include methyl, ethyl, propyl, butylhexyl, octyl, decyl, dodecyl, octadecyl and the like, and may be at any position on the naphthalene nucleus.
C ₁ -C ₂₅ alkoxylated phosphoric acid (salt) has the following general formula
(a).

[0042]

Embedded image (In the formula (a), R _a and R _b are the same or different C ₁ -C ₂₅ alkyl, provided that one of them may be H. M represents H or an alkali metal.)

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.

Further, as the nonionic surfactant, R ₁ N (R ₂ ) ₂ → O (where R ₁ is a C ₅ -C ₂₅ alkyl or RCONHR ₃ (R
₃ represents C ₁ -C ₅ alkylene), R ₂ is the same or different
Represents ₁ to ₅ alkyl; ) And the like.

Two or more nonionic surfactants may be mixed, and the amount of the plating bath added is generally 0.05 to 1%.
00 g / L, preferably 0.1 to 50 g / L.

As the cationic surfactant, a quaternary ammonium salt represented by the following general formula (b):

[0047]

Embedded image (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).

[0048]

Embedded image (In the formula (c), X is halogen, hydroxy, C ₁ -C ₅ alkanesulfonic acid or sulfuric acid, R ₅ is C ₁ -C ₂₀ alkyl, R
₆ represents H or C ₁ -C ₁₀ alkyl. )

Examples of the cationic surfactant in the form of a salt 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 an alkyl sulfate, a polyoxyethylene alkyl ether sulfate, a polyoxyethylene alkyl phenyl ether sulfate, and an alkylbenzene sulfonate.
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
(EO15) nonylphenyl ether sulfate and the like. Examples of the alkyl benzene sulfonate include sodium dodecyl benzene sulfonate.

As the amphoteric surfactant, betaine,
Sulfobetaine, aminocarboxylic acid and the like.
Sulfated or sulfonated adducts of the condensation products of ethylene oxide and / or propylene oxide with alkylamines or diamines can also be used. The betaine is represented by the following general formula (d) or (e).

[0052]

Embedded image (In the formula (d), R ₇ is C ₁ -C ₂₀ alkyl, R ₈ and R ₉ are the same or different C ₁ -C ₅ alkyl, and n is an integer of 1-3.)

[0053]

Embedded image (In the formula (e), R ₁₀ is C ₁ -C ₂₀ alkyl, R ₁₁ is (CH ₂ ) _m
OH or (CH ₂ ) _m OCH ₂ CO ₂ ⁻ , R ₁₂ is (CH ₂ ) _n CO _{2
^{-, (CH 2) n SO}} 3 -, CH (OH) CH 2 SO 3 -, m and n
Represents an integer of 1 to 4. )

Representative betaines are lauryl dimethyl ammonium betaine, stearyl dimethyl ammonium betaine, 2-undecyl-1-carboxymethyl-1
-Hydroxyethyl imidazolinium betaine, 2-octyl-1-carboxymethyl-1-carboxyethyl imidazolinium betaine, and the like. Examples of the sulfated and sulfonated adducts include sulfuric acid adducts of ethoxylated alkylamines and sulfonated adducts. Lauric acid derivative sodium salt and the like.

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

Two or more of these surfactants other than the nonionic surfactant may be used in combination, and the amount added to the plating bath is generally 0.05 to 100 g / L, preferably 0.1.
５０50 g / L.

Specific examples of the brightener usable in the present invention 6 include m-chlorobenzaldehyde, p-nitrobenzaldehyde, p-hydroxybenzaldehyde,
(o-, p-) methoxybenzaldehyde, vanillin,
(2,4-, 2,6-) dichlorobenzaldehyde, (o-,
p-) chlorobenzaldehyde, 1-naphthaldehyde, 2-naphthaldehyde, 2 (4) -hydroxy-1-
Naphthaldehyde, 2 (4) -chloro-1-naphthaldehyde, 2 (3) -thiophenecarboxaldehyde, 2
(3) -furaldehyde, 3-indolecarboxaldehyde, salicylaldehyde, o-phthalaldehyde,
Formaldehyde, acetaldehyde, paraaldehyde, butyraldehyde, isobutyraldehyde, propionaldehyde, n-valeraldehyde, acrolein, crotonaldehyde, glyoxal, aldol, succindialdehyde, capronaldehyde, isovaleraldehyde, allylaldehyde, glutaraldehyde, 1-benzylidene -7-heptanal, 2,4-
Hexadienal, cinnamaldehyde, benzylcrotonaldehyde, amine-aldehyde condensate, mesityl oxide, isophorone, diacetyl, hexanedione-3,
4, acetylacetone, 3-chlorobenzylideneacetone, sub. Pyridylideneacetone, sub. Furfuridinacetone, sub. Tenylideneacetone, 4- (1-naphthyl) -3-buten-2-one, 4- (2- Frill)
3-buten-2-one, 4- (2-thiophenyl) -3-
Buten-2-one, curcumin, benzylideneacetylacetone, benzalacetone, acetophenone, (2,4
-, 3,4-) dichloroacetophenone, benzylideneacetophenone, 2-cinnamylthiophene, 2- (ω-
(Benzoyl) vinylfuran, vinylphenylketone, acrylic acid, methacrylic acid, ethacrylic acid, ethyl acrylate, methyl methacrylate, butyl methacrylate, crotonic acid, propylene-1,3-dicarboxylic acid, cinnamic acid, (o-, m-, p-) toluidine, (o-, p-) aminoaniline, aniline, (o-, p-) chloroaniline,
(2,5-, 3,4-) chloromethylaniline, N-monomethylaniline, 4,4'-diaminodiphenylmethane,
N-phenyl- (α-, β-) naphthylamine, methylbenztriazole, 1,2,3-triazine, 1,2,4-
Examples thereof include triazine, 1,3,5-triazine, 1,2,3-benztriazine, imidazole, 2-vinylpyridine, indole, quinoline, and a reaction product of monoethanolamine and o-vanillin.

These brighteners can be used alone or in combination, and the amount added to the plating bath is generally 0.005 to 40 g / L, preferably 0.01 to 20 g / L.

The plating bath of the present invention may contain the above-mentioned semi-brightener of the present invention 7 in order to improve the smoothness of the plating surface. The semi-brightening agent has a further synergistic effect when used in combination with various surfactants. The semi-brightening agent in this case can be used in principle as long as it is a semi-brightening agent generally used for tin or tin-lead alloy plating.
and those represented by (f) to (i).

[0060]

Embedded image (In the formula (f), R is hydrogen, an alkyl group (C ₁ -C ₄ ) or a phenyl group, R ^I is hydrogen, a hydroxyl group, or R ^II
Is an alkylene group (C ₁ -C ₄ ), phenylene group or benzyl group, and R ^III is hydrogen or an alkyl group (C ₀ -C ₄ ). )

[0061]

Embedded image (In the formula (g), R, is R ^I is an alkyl group (C ₁ ~C _18).)

[0062]

Embedded image (In the formula (h), R is hydrogen, an alkyl group (C ₁ -C ₄ ) or a phenyl group.)

[0063]

Embedded image (In the formula (i), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, respectively, and (1) H, (2) -SH, (3) -OH, (4 )
OR (R is a C ₁ -C ₆ alkyl group optionally substituted with —COOH), (5) OH, halogen, —COO
H, - (CO) COOH, means optionally substituted C ₁ -C ₆ alkyl aryl or OC ₁ -C ₆ alkyl group. )

Among the above semi-brightening agents, in particular, 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, 2,4
-Diamino-6- (2'-ethyl-4-methylimidazolyl (1 ')) ethyl-1,3,5-triazine, 2,4-diamino-6- (2'-undecylimidazolyl (1')) Ethyl-1,3,5-triazine, phenyl salicylate and the like can be mentioned.

Similarly, the benzothiazole semi-brighteners of the above general formula (i) include, in particular, benzothiazole,
2-methylbenzothiazole, 2- (methylmercapto)
Benzothiazole, 2-aminobenzothiazole, 2-
Amino-6-methoxybenzothiazole, 2-methyl-
5-chlorobenzothiazole, 2-hydroxybenzothiazole, 2-amino-6-methylbenzothiazole,
2-chlorobenzothiazole, 2,5-dimethylbenzothiazole, 6-nitro-2-mercaptobenzothiazole, 5-hydroxy-2-methylbenzothiazole,
2-benzothiazolethioacetic acid and the like.

The amount of the semi-brightening agent added is generally 0.00
It is 1 to 10 g / L, preferably 0.1 to 5 g / L.

The method of preparing the plating baths of the present inventions 8 to 9 is characterized in that the antioxidants of the present inventions 1 to 3 or the coagulation promoters of the present invention 4 are mixed with the components of the plating baths such as acid, soluble salt and surfactant. Characterized in that it is previously mixed with at least one of a brightening agent and a semi-brightening agent, and is mixed with the remaining bath components at the time of building bath, such as a soluble salt, a surfactant, a brightening agent, or a semi-brightening agent. Specifically, the term “contamination” refers to the addition of these to an aqueous solution or the like.

The concentration of each of the above components in the plating bath of the present invention is determined by barrel plating, rack plating, high-speed continuous plating,
It can be arbitrarily adjusted and selected according to rackless plating. Further, in the plating bath of the present invention, in addition to various additives such as the brightener, a complexing agent used in a normal plating bath,
Needless to say, a pH adjuster, a buffer and the like can be added.

The storage method of the present invention 10 is an independent storage method of a tin salt aqueous solution for a tin or tin alloy plating bath, and the antioxidants of the present invention 1 to 3 are added to the adjusted plating bath. Instead, it is a method of adding to a concentrated aqueous solution of a tin salt before preparation to suppress oxidation of stannous ions. The concentrated aqueous solution of the present invention 10 to 11 means 50 g / L or more in terms of a soluble salt of tin. Instead of adding the novel antioxidants of the present inventions 1 to 3, the storage method of the present invention 11 uses catechol, hydroquinone, resorcinol, pyrogallol, phloroglucin, phenolsulfonic acid, cresolsulfonic acid, ascorbic acid, or a mixture thereof. Use of well-known or known antioxidants such as salts, and antioxidants such as catecholsulfonic acid, hydroquinonesulfonic acid, naphtholsulfonic acid, or salts thereof (not included in the present invention 1 to 3) It was done. The present invention 10
In 11, the antioxidants can be used alone or in combination, and the antioxidants of the inventions 1 to 3 can be combined with well-known or known (or catecholsulfonic acid or the like) antioxidants to form a concentrated aqueous solution of a tin salt. It may be added. The content of the antioxidant is generally 10 ppm to 10% with respect to the concentrated aqueous solution of the tin salt.
0 g / L, preferably 100 ppm to 10 g / L.

[0070]

(1) When the antioxidants of the present invention 1 to 3 are contained in a tin or tin alloy plating bath, first, as shown in the test examples described below, first, stannic oxide is contained in the bath. Can be effectively suppressed (see FIGS. 1B to 14B). Second, even if oxidation of the plating bath (air oxidation or anodic oxidation) progresses over a long period of use and fine particles of stannic oxide are generated, the particles are promoted to aggregate, or the particles are grown by crystal growth. The diameter can be increased (see FIGS. 1A to 14A). That is, the antioxidant of the present invention has not only an antioxidant effect of stannous ions but also an aggregation promoting effect of particles of stannic oxide which is an oxide thereof. In particular, among the above antioxidants, predetermined pyrogallols such as gallic acid and 3,4-dihydroxybenzoic acid, or catechols, sodium 2,3-dihydroxynaphthalene-6-sulfonate,
Divalent naphthols such as sodium 2,3-dihydroxynaphthalene-5-sulfonate have a large aggregation promoting effect on stannic oxide particles. Further, unlike known antioxidants such as catechol, among the antioxidants of the present invention, 3,4-dihydroxybenzoic acid, guaiacol, 2 (4-hydroxyphenyl) ethyl alcohol,
-Naphthol-6,8-disulfonic acid dipotassium has a strong tendency to suppress turbidity of the bath and maintain transparency.

(2) When the coagulation accelerator of the present invention 4 is contained in a tin or tin alloy plating bath, the coagulation of stannic oxide particles is reduced in the same manner as in (1) above, as shown in the test examples described below. Can be effectively promoted (FIGS. 10A to 11A, 14A
reference). Among the above-mentioned coagulation accelerators, tartaric acid and a salt thereof showed an approximate coagulation accelerating action, and ammonium dihydrogen phosphate had a slightly higher coagulation ability than tartaric acids. In the present invention, the ultimate goal is to maintain the transparency of the tin or tin alloy plating bath. To that end, as described above, first, the generation of stannic oxide fine particles should be suppressed as much as possible. ,Secondly,
When stannic oxide is generated due to long-term use or the like, it is efficient to increase the particle size of the oxide and capture and remove it with a filter. Therefore, the antioxidant of the present invention is basically used independently for the first problem, and the aggregation promoter of the present invention is basically used independently for the second problem. However, the antioxidant of the present invention generally has an aggregation promoting action. Therefore, the first and second problems can be satisfied at the same time, and the aggregation promoter can be omitted by utilizing the antioxidant.

(3) As in the present invention 5, when a surfactant is additionally added to the plating bath, the appearance of particles, adhesion, and denseness of the tin or tin alloy plating film can be further favorably promoted.

(4) As in the present invention 6 or 7, when a brightener or semi-brightener is additionally mixed into the plating bath, the gloss or smoothness of the plating film can be favorably promoted.

(5) As in the case of the present invention 8 or 9, when preparing an electroplating bath, a novel antioxidant or a coagulation accelerator may be separately added to an aqueous solution such as an acid, a surfactant, a semi-brightening agent or the like. ) Is mixed in advance with at least one of them and then combined with other bath components at the time of bathing, so that the coagulation promoting action of stannic oxide can be kept higher and the antioxidant or coagulation The accelerator can be dissolved uniformly and the preparation of the bath becomes easy.

(6) The present invention 10 or 11 is characterized in that the novel antioxidant of the present invention 1 to 3, catecholsulfonic acid, Hydroquinone sulfonic acid, naphthol sulfonic acid, or a well-known, well-known antioxidant is a storage method for suppressing the oxidation of stannous ions in a tin salt aqueous solution, since the tin salt aqueous solution to be added is concentrated, The volume of the entire aqueous solution containing a predetermined amount of tin salt can be reduced, the storage containers can be made compact, and the storage space can be saved. Usually, the oxidation of tin salt, which is a component of the plating bath, needs to be suppressed within 5% within six months. However, by adding an antioxidant to a concentrated aqueous solution of tin salt, this problem can be smoothly achieved. Moreover, the content of the antioxidant is 10 pp.
Even small amounts of m (preferably 100 ppm) are effective. For this reason, the method of including an antioxidant in a concentrated aqueous solution of a tin salt is a sufficiently practical storage method that can be used instead of integrally managing the plating bath.

[0076]

EXAMPLES In the following, examples of tin or tin alloy electroplating baths will be sequentially described, and the degree of suspension of the bath by stannic oxide when the plating bath of each embodiment is aerated for a long period of time will be described. An example of the test is described below. It should be noted that the present invention is not limited to the following embodiments, and it goes without saying that many modifications can be made within the scope of the technical idea of the present invention.

Examples 1 to 11 below are tin-lead alloy plating baths. Among them, Examples 1 to 9 are examples in which a new antioxidant is added, and Examples 10 to 11 are new aggregation promoters. This is an example in which is added. In Examples 12 to 19, tin-
Tin alloy plating baths other than lead alloys, Examples 20 to 21 are tin plating baths.

Example 1 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Gallic acid 1.2 g / L The test was carried out by a one-bath system in which the bath components were simultaneously mixed. Further, the initial value of the content of tetravalent tin ions in the plating bath was about 3 g / L (this preparation method and initial values are described in Examples 2 to 21 and Comparative Examples 1 to 5 below).
Both are the same).

Example 2 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L 3,4-dihydroxybenzoic acid 1.4 g / L

Example 3 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L 4-methylcatechol 1.1 g / L

Example 4 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L 2,3-dihydroxynaphthalene-6-sodium sulfonate 2 .4g / L

Example 5 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L 3,4-dihydroxybenzyl alcohol 1.3 g / L

Example 6 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Guayacol 1.1 g / L

Example 7 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L 2 (4-hydroxyphenyl) ethyl alcohol 1.3 g / L L

Example 8 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Dipotassium 2-naphthol-6,8-disulfonic acid 3 .5g / L

Example 9 A tin-lead alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L 2,3-dihydroxynaphthalene-5-sodium 5-sulfonate 2 .4g / L

Example 10 A tin-lead alloy plating bath having the following composition was prepared (example of adding a coagulation accelerator). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Tartaric acid 10 g / L

Example 11 A tin-lead alloy plating bath having the following composition was prepared (example of adding a coagulation accelerator). Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Ammonium dihydrogen phosphate 0.2 g / L

Example 12 A tin-cobalt alloy plating bath having the following composition was prepared (example of adding a coagulation promoter). Stannous chloride 45 g / L Cobalt sulfate 300 g / L Methanesulfonic acid 50 g / L Gluconic acid 80 g / L pH (adjusted with ammonia water) 4.0 Ammonium dihydrogen phosphate 0.1 g / L

Example 13 A tin-indium alloy plating bath having the following composition was prepared (an example of adding a coagulation accelerator). Stannous 2-propanol sulfonate (as Sn ²⁺ ) 10 g / L Indium chloride (as In ³⁺ ) 10 g / L 2-propanol sulfonic acid 100 g / L Sodium gluconate 100 g / L pH (adjusted with sodium hydroxide) 2.0 Tartaric acid 1g / L

Example 14 A tin-nickel alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous chloride 45 g / L Nickel chloride (hexahydrate) 300 g / L Ammonium chloride 100 g / L Hydrochloric acid (35%) 50 ml / L Ammonium fluoride 60 g / L pH (adjusted with aqueous ammonia) 4.0 Catechol 1. 0g / L Gallic acid 1.2g / L

Example 15 A tin-bismuth alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 40 g / L Bismuth methanesulfonate (as Bi ³⁺ ) 4 g / L Methanesulfonic acid 100 g / L Polyoxyethylene laurylamine (EO10) 5 g / L 3,4-dihydroxy Benzoic acid 1.2g / L

Example 16 A tin-silver alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 17.5 g / L Silver methanesulfonate (as Ag ⁺ ) 0.5 g / L Methanesulfonic acid 10 g / L Gluconic acid 0.9 mol / L Potassium iodide 1.5 mol / L Triethanolamine 0.15 mol / L Reaction product of monoethanolamine and o-vanillin 4 g / L pH (adjusted with sodium hydroxide) 4.5 2,3-Dihydroxynaphthalene-6-sodium sulfonate 2.4 g / L L

Example 17 A tin-zinc alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous sulfosuccinate (as Sn ²⁺ ) 24 g / L Zinc sulfosuccinate (as Zn ²⁺ ) 6 g / L Sulfosuccinic acid 0.6 mol / L Naphthol polyethoxylate (EO13) 2 g / L Lauryldimethylammonium betaine 0.1 g / L L-ascorbic acid 1.0 g / L pH (adjusted with sodium hydroxide) 4.5 3,4-dihydroxybenzyl alcohol 1.3 g / L

Example 18 A tin-antimony alloy plating bath having the following composition was prepared (example of adding an antioxidant). Stannous sulfate (SnSO ₄ ) 50 g / L Antimony chloride (SbCl ₃ ) 0.4 g / L Sulfuric acid 100 g / L Ammonium fluoride 5 g / L Glue 0.5 g / L Phenol 5 g / L Gallic acid 1.0 g / L

Example 19 A tin-copper alloy plating bath was prepared according to the following composition (example of adding a coagulation promoter). Stannous sulfate (SnSO ₄₎ 50g / L copper sulfate (CuSO ₄₎ 5g / L sulfuric acid 100 g / L nonylphenol polyethoxylate (EO15) 10g / L 2- mercaptobenzothiazole 0.5 g / L-tartaric acid 1.0 g / L

Example 20 A tin plating bath having the following composition was prepared (example of adding an antioxidant). Stannous methanesulfonate (as Sn ²⁺ ) 20 g / L 2-propanolsulfonic acid 150 g / L o-cresolsulfonic acid 10 g / L α-naphthol polyethoxylate (EO10) 10 g / L 2,3-dihydroxynaphthalene − Sodium 6-sulfonate 2.0g / L

Example 21 A tin plating bath having the following composition was prepared (an example of addition of an aggregation promoter). Stannous sulfate (SnSO ₄ ) 50 g / L Sulfuric acid 100 g / L Nonylphenol polyethoxylate (EO15) 10 g / L 2-mercaptobenzothiazole 0.5 g / L Tartaric acid 1.0 g / L

Comparative Example 1 A tin-lead alloy plating bath having the following composition was prepared. Comparative Example 1 is a blank example of a so-called tin-lead alloy plating bath in which neither an antioxidant nor an aggregation promoter was added. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L

Comparative Example 2 A tin-lead alloy plating bath having the following composition was prepared. In Comparative Example 2, catechol, a known antioxidant, was added. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Catechol 1.0 g / L

Comparative Example 3 A tin-lead alloy plating bath having the following composition was prepared. In Comparative Example 3, polyacrylamide, which is a known aggregation promoter, was added. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L polyacrylamide 0.05 g / L The above polyacrylamide is A commercial product having a molecular weight of about 10 million was used.

Comparative Example 4 A tin plating bath having the following composition was prepared. Comparative Example 4 is a so-called tin plating bath blank example in which neither an antioxidant nor a coagulation accelerator was added. Stannous sulfate (SnSO ₄₎ 50g / L sulfuric acid 100 g / L nonylphenol polyethoxylate (EO15) 10g / L 2- mercaptobenzothiazole 0.5 g / L

Comparative Example 5 A tin plating bath having the following composition was prepared. In Comparative Example 5, catechol, a known antioxidant, was added. Stannous methanesulfonate (as Sn ²⁺ ) 20 g / L 2-propanolsulfonic acid 150 g / L o-cresolsulfonic acid 10 g / L α-naphthol polyethoxylate (EO10) 10 g / L Catechol 1.0 g / L

Then, a long-term aeration was applied to each plating bath, and the degree of stannic oxide generation (that is, the degree of oxidation of stannous ions) in each plating bath was generated according to the test example shown below. The particle size of stannic oxide and the degree of turbidity of the bath were measured over time on a weekly basis.

<< Evaluation Test Example of Plating Bath with Time >> 500 mL of the prepared plating solution for each tin or tin alloy bath was put into a 1-liter tall beaker, and this beaker was placed in a thermostat maintained at 50 ° C. Next, aeration (bubbling) was performed by continuously blowing air into the plating solution at a rate of 1.5 L / min using a pump.

(1) Measurement of the amount of generated stannic oxide The air blowing operation was continued for a maximum of about 35 days, and each plating solution was sampled as a sample every predetermined number of days, and Sn in the solution was sampled. The total content of ²⁺ and Sn ⁴⁺ was measured by atomic absorption spectrometry, and the content of Sn ²⁺ was measured by iodometric titration, and the latter was subtracted from the former to obtain tetravalent in each sample. Was calculated for each tin ion (Sn ⁴⁺ ), and the amount of stannic oxide generated in the bath was evaluated. However,
It is presumed that the stannic oxide obtained in the measurement includes both those suspended as particles in the bath and those dissolved therein.

(2) Measurement of Particle Size of Stannic Oxide After the start of the aeration operation in (1) above, each plating solution was sampled as a sample after a lapse of a predetermined number of days, and the stannic oxide generated in each sample was sampled. Laser diffraction type particle size distribution analyzer (LA-500; Horiba, Ltd.)
(Manufactured by K.K.).

(3) Measurement of turbidity of plating solution After the start of the aeration operation in (1) above, each plating solution was sampled as it was without filtering, and the absorbance of each sample was measured using pure water. Was measured at a wavelength of 660 nm using a spectrophotometer (U-2000 type double beam spectrophotometer; manufactured by Hitachi, Ltd.).

<< Evaluation of Plating Bath >> FIGS. 1A, 1B, 1C to 14
A, B, and C and FIGS. 15A, B, C to 19A, B, and C show the results. The present invention is basically a matter of oxidation of stannous ions in a tin or tin alloy plating bath and agglomeration of oxides, and a test of similar or similar tendency among various tin alloy plating baths. The results were obtained, and the tin-lead alloy bath can be represented by a tin alloy plating bath.In the following evaluation of each plating bath, the tin-lead alloy plating bath and the tin plating bath were evaluated as model cases, and the tin-plating bath was evaluated. −
As a tin alloy plating bath other than a lead alloy, only a tin-bismuth alloy bath is described separately.

(1) Comparative evaluation of the amount of stannic oxide generated (see B in each figure) Regarding the tin-lead alloy plating bath, the amount of stannic oxide generated was first tested in Comparative Example 1 (blank). Although it increased steeply toward 85% over two weeks after the start (see FIG. 15B), in Comparative Example 2 to which a known antioxidant (catechol) was added, almost 1% was obtained.
The transition was in the range of slightly less than 0% to 20% (see FIG. 16B), and a certain antioxidant effect was observed. Also, known coagulation accelerators
In Comparative Example 3 in which (polyacrylamide) was added, the result was the same as that of the blank. On the other hand, in Examples 1 to 6 and 9 to which a new antioxidant was added, 10%
推移 20%, and the same antioxidant effect as catechol was observed. In Examples 7 and 8, the amount of generation slightly increased with the passage of days, but a clear antioxidant effect was observed as compared with the blank. Further, in Examples 10 to 11 in which a new aggregation promoter was added, the same results as in Comparative Example 1 of the blank were shown, and it was found that the antioxidant effect could not be expected as a matter of course. Regarding tin-bismuth alloy plating bath As shown in Example 15 (see FIG. 12B), when a new antioxidant (3,4-dihydroxybenzoic acid) is added, the amount of generated stannic oxide is about 10%. And the result was similar to that of the tin-lead alloy plating bath. Regarding the tin plating bath As shown in Example 20 (see FIG. 13B), when a new antioxidant (sodium 2,3-dihydroxynaphthalene-6-sulfonate) is added, the amount of generated stannic oxide is almost 10%. Can be kept low, also known antioxidants
(Catechol), an antioxidant effect superior to Comparative Example 5 (see FIG. 19B) was observed. However, in Example 21 (see FIG. 14B) in which a new aggregation promoter (tartaric acid) was added,
As in Comparative Example 4 of the blank (see FIG. 18B), no antioxidant effect could be expected.

(2) Comparative evaluation of median diameter of stannic oxide
(See A in each figure.) Regarding the tin-lead alloy plating bath, the median diameter of the generated stannic oxide was 2 μm or less in Comparative Example 1 of the blank, and it was found that it was suspended in the bath as colloidal particles. In Comparative Example 2 to which catechol was added, the fine particles also changed to about 2 μm, indicating no aggregation promoting effect. In Comparative Example 3 in which polyacrylamide was added, the particle size of stannic oxide increased,
A certain coagulation promoting effect was observed. On the other hand, in Example 1 in which a new antioxidant was added, the median diameter was 1
It increases rapidly from about a week, and 60 μm in 2 to 4 weeks
To a high degree, showing a high coagulation capacity. Example 2 also showed an aggregation ability of about 7 μm or more over a period of 4 weeks, and retained the original aggregation ability even after 4 weeks. In particular, Example 3 showed a remarkable aggregation ability exceeding 160 μm in about two weeks. Also in Example 4, the median diameter increased with the passage of days, approaching 18 μm in about 4 weeks. In Example 5, although the median diameter decreases with the passage of days, the median diameter still decreases by 15 days.
μm or more was maintained. Example 9 in which divalent naphthols differing in the position of the sulfonic acid group had similar results. Example 8 shows better aggregation ability than catechol,
Examples 6 and 7 were comparable to catechol. Example 10 in which a new aggregation promoting agent (tartaric acid) was added showed an aggregation ability of 8 μm or more after one week, and Example 11 in which ammonium dihydrogen phosphate was added showed an aggregation ability superior to tartaric acid. Further, although not shown, salts such as sodium salt and potassium salt of tartaric acid had similar results to tartaric acid. Regarding tin-bismuth alloy plating bath As shown in Example 15 (see FIG. 12A), when a new antioxidant is added, the median diameter of stannic oxide becomes 10 μm.
It grew as described above and exhibited the same coagulation ability as the tin-lead alloy plating bath. Example 20 in which a new antioxidant was added for a tin plating bath (see FIG. 13A),
In both Example 21 and the new coagulation promoter-added example (see FIG. 14A), the median diameter of stannic oxide continued to grow and increased, and only blank Comparative Example 4 (see FIG. 18A) and catechol were added. As compared with Comparative Example 5 (see FIG. 19A), remarkable aggregation ability was observed.

(3) Comparative evaluation of absorbance (see C in each figure) Tin-lead alloy plating bath Absorbance increases when the turbidity of the bath is large, and turbidity and the absorbance are basically in a proportional relationship. First, the turbidity increased with the passage of days in the blank Comparative Example 1. Although the slopes of Comparative Example 3 to which polyacrylamide was added and Comparative Example 2 to which catechol was added were slightly gentler than Comparative Example 1, similar results were obtained. On the other hand, Examples 3 and 5 to 8 to which the new antioxidant was added showed little turbidity at the initial stage and with the passage of days, and Examples 5 to 8 were particularly excellent. Example 1
2, 4, and 9 give the turbidity a step further to catechol,
The blank did not show a linear increasing tendency as in Comparative Example 1, and the turbidity did not progress beyond a certain value. In Examples 10 and 11 to which a new coagulation accelerator was added, there were few things to be seen in terms of turbidity. Regarding the tin-bismuth alloy plating bath In Example 15 (see FIG. 12C) to which a new antioxidant was added, the turbidity with the initial and days elapsed was small as in the case of the tin-lead alloy plating bath. In the case of Example 20 (see FIG. 13C) in which a new antioxidant was added to the tin plating bath, the turbidity with the initial and days elapsed was also small. Example 21 (FIG. 1) containing a new aggregation promoter was added.
4C) and Comparative Example 5 in which only catechol was added (FIG. 19C).
(See FIG. 18C), the turbidity increased compared to Example 20 although the blank did not have a linear increasing tendency as in Comparative Example 4 (see FIG. 18C).

(4) Comprehensive evaluation Regarding the tin-lead alloy plating bath In the plating bath to which a known antioxidant was added (Comparative Example 2),
Although there was a certain prevention effect on the generation of stannic oxide, the generated stannic oxide remained as fine particles, and the turbidity of the bath did not decrease (see FIG. 16). On the other hand, in the plating bath (Comparative Example 3) to which the known coagulation accelerator was added, on the contrary, the effect of preventing the generation of stannic oxide was not increased and the turbidity of the bath was increased. Showed a certain coagulation ability
(See FIG. 17). On the other hand, in Examples 1 to 9 in which a new antioxidant was added, the generation of stannic oxide can be effectively suppressed as a whole, and the generated stannic oxide particles have a high aggregation ability. It had both the ability to prevent oxidation of tin ions and the ability to promote the aggregation of oxide particles. In many cases, turbidity of the plating bath could be suppressed. In Examples 10 to 11 in which a new aggregation promoter was added, the effect of preventing the generation of stannic oxide could not be expected, but the aggregation ability of the stannic oxide particles was high. Regarding the tin-bismuth alloy plating bath In Example 15 (see FIG. 12) in which a new antioxidant was added, similarly to the tin-lead alloy plating bath, the antioxidant ability of stannous ions and the promotion of agglomeration of the oxide particles were obtained. He had the ability. In addition, the turbidity of the plating bath was relatively suppressed. Regarding the tin plating bath, in comparison with Comparative Example 4 (see FIG. 18) of a blank and Comparative Example 5 (see FIG. 19) in which only catechol was added, Example 20 (see FIG. 13) in which a new antioxidant was added was the first. The antioxidant ability of tin ions and the ability to promote the aggregation of the oxide particles were well combined. Further, Example 21 (see FIG. 14) to which a novel aggregation promoter was added showed excellent aggregation ability of stannic oxide. Therefore, the effect of adding a new antioxidant or a coagulation promoter to the tin plating bath was almost the same as that of the tin-lead alloy plating bath.

As described above, when the novel antioxidant of the present invention is added to a tin or tin alloy plating bath, the antioxidant has a function of preventing oxidation of stannous ions and a function of promoting aggregation of stannic oxide. In addition to effectively suppressing the oxidation of stannous ions, even when the oxidation of the plating bath progresses over a long period of use and fine particles of stannic oxide are generated, the particles are promoted to agglomerate, or the median is grown by crystal growth. The diameter can be increased. For this reason, the stannic oxide particles can be easily captured and removed by using a filter attached to the plating apparatus, whereby the transparency of the plating bath can be stabilized with time (continued for a long time). Even when the novel aggregation promoter of the present invention is added, the aggregation of stannic oxide particles is similarly promoted, and the transparency of the plating bath can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a view showing a test result when aeration is applied to a tin-lead alloy plating bath of Example 1, and FIG. 1A is a time-dependent change diagram showing a median diameter of generated stannic oxide particles, and FIG. 1B. FIG. 1 is a temporal change diagram showing the content of tetravalent tin ions in the bath, and FIG. 1C is a temporal change diagram showing the absorbance of the bath.

FIG. 2 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 2.

FIG. 3 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 3.

FIG. 4 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 4.

FIG. 5 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 5.

FIG. 6 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 6.

FIG. 7 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 7.

FIG. 8 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 8.

FIG. 9 is a view corresponding to FIG. 1, showing a tin-lead alloy plating bath of Example 9.

FIG. 10 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 10.

FIG. 11 is a view corresponding to FIG. 1 showing a tin-lead alloy plating bath of Example 11.

FIG. 12 is a view corresponding to FIG. 1, illustrating a tin-bismuth alloy plating bath of Example 15.

FIG. 13 is a view corresponding to FIG. 1, showing a tin plating bath of Example 20.

FIG. 14 is a view corresponding to FIG. 1, showing a tin plating bath of Example 21.

FIG. 15 shows a tin-lead alloy plating bath of Comparative Example 1.
FIG.

FIG. 16 shows a tin-lead alloy plating bath of Comparative Example 2.
FIG.

FIG. 17 shows a tin-lead alloy plating bath of Comparative Example 3.
FIG.

FIG. 18 is a view corresponding to FIG. 1 showing a tin plating bath of Comparative Example 4.

FIG. 19 is a view corresponding to FIG. 1 showing a tin plating bath of Comparative Example 5.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Masakazu Yoshimoto, Inventor of Daiwa Kasei Research Laboratories at 21 Minami Futami, Futami-cho, Akashi City, Hyogo Prefecture

Claims (11)

[Claims] (A) stannous salt, stannous salt and lead,
A soluble salt composed of any one of a mixture of salts of a metal selected from silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony; (B) alkanesulfonic acid, alkanolsulfonic acid, and aliphatic carboxylic acid Such as an organic acid, or at least one acid selected from inorganic acids such as hydrochloric acid, sulfuric acid, and hydrofluoric acid; (C) at least one antioxidant represented by the following formulas (1) to (2) , Embedded image (In the formula (1), R is SO ₃ X (X is a metal such as hydrogen, sodium, potassium, calcium, NH ₄ or the like), COOY (Y is a metal such as hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH _2, is halogen; n is an integer of from 1 to 4; m is an integer of 1-2, provided that when the m = 2, R
Are the same or different substituents; n = 1, m = 1
R excludes SO ₃ H; n = 1, m = 2;
R excludes the combination of SO ₃ H and CH ₃ ; n = 2, m =
If 1, R excludes SO ₃ X. ) (In the formula (2), R is SO ₃ X (X is hydrogen, sodium, potassium, calcium, etc., NH ₄ etc.), COOY (Y is hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH _2, is halogen; n is an integer of from 1 to 4; m is an integer of 1-2, provided that when the m = 2, R
Are the same or different substituents from each other; when n and m = 1, R excludes SO ₃ H. ), Comprising a tin and tin alloy plating bath. 2. The antioxidant of the formula (1) is at least one of the compounds represented by the following formulas (3) to (4): (In the formula (3), R is SO ₃ X (X is hydrogen, sodium, potassium, calcium, etc., NH ₄ etc.), COOY (Y is hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ and halogen. ) (In the formula (4), R is SO ₃ X (X is a metal such as hydrogen, sodium, potassium, calcium, NH ₄ or the like), COOY (Y is a metal such as hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ and halogen. 2. The tin and tin alloy plating bath according to claim 1, wherein 3. The antioxidant of the formula (2) is at least one of the compounds represented by the following formulas (5) to (6): (In the formula (5), R is SO ₃ X (X is hydrogen, sodium, potassium, calcium, etc., NH ₄ etc.), COOY (Y is hydrogen, sodium, potassium, calcium, etc., N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ and halogen. ) (In the formula (6), R is SO ₃ X (X is hydrogen, sodium, potassium, calcium or the like, NH ₄ or the like), COOY (Y is hydrogen, sodium, potassium, calcium or the like, N
H ₄ ), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ and halogen. The tin and tin alloy plating bath according to claim 1 or 2, wherein (A) stannous salt, stannous salt and lead,
A soluble salt composed of any one of a mixture of salts of a metal selected from silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony; (B) alkanesulfonic acid, alkanolsulfonic acid, and aliphatic carboxylic acid Such as organic acids, or at least one acid selected from inorganic acids such as hydrochloric acid, sulfuric acid, and hydrofluoric acid; (C) tartaric acid, sodium tartrate, ammonium tartrate;
At least one kind of coagulation accelerator for stannic oxide fine particles selected from potassium tartrate, calcium tartrate, magnesium tartrate, tartrate such as Rochelle salt, and hydrogen phosphate such as sodium monohydrogen phosphate and ammonium dihydrogen phosphate A tin and tin alloy plating bath, characterized by containing: 5. A tin and tin alloy plating bath, which further comprises a surfactant in addition to the plating bath according to claim 1. Description: 6. A tin and tin alloy plating bath, which further comprises a brightener in addition to the plating bath according to claim 1. Description: 7. A tin and tin alloy plating bath, which further comprises a semi-brightening agent in addition to the plating bath according to claim 1. Description: 8. The plating bath according to claim 1, wherein the antioxidant is at least one of an acid, a soluble metal salt, a surfactant, a brightener, and a semi-brightener. A method for preparing a tin and tin alloy plating bath, wherein the mixture is mixed in advance with any one of the components and the mixture is mixed with the remaining bath components at the time of building the bath. 9. The plating bath according to claim 4, wherein the coagulation promoter is added to at least one of an acid, a soluble metal salt, a surfactant, a brightener, and a semi-brightener. A method for preparing a tin and tin alloy plating bath, comprising mixing and mixing the mixture with the remaining bath components at the time of bathing. 10. An antioxidant according to claim 1, which is added to a concentrated aqueous solution of a tin salt to suppress oxidation of stannous ions in the aqueous solution. How to store tin salt aqueous solution for tin alloy plating bath. 11. Catechol, hydroquinone, resorcin, pyrogallol, phloroglucin, phenolsulfonic acid, cresolsulfonic acid, catecholsulfonic acid,
Adding at least one antioxidant selected from hydroquinone sulfonic acid, naphthol sulfonic acid, ascorbic acid, or a salt thereof to a concentrated aqueous solution of a tin salt to suppress oxidation of stannous ions in the aqueous solution. A method for storing a tin salt aqueous solution for a tin and tin alloy plating bath.