JP3425645B2 - Tin and tin alloy plating baths, methods for managing and preparing the plating baths - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a tin and tin alloy plating bath for electroplating, and a control method and a preparation method thereof. By adding a combination of an antioxidant and a coagulation accelerator, stannic oxide (EN) A plating bath capable of suppressing generation and suppressing turbidity and continuously stabilizing transparency.

[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 for surface treatment of electronic parts such as semiconductor devices, connectors and chip parts as films for improving solderability. It's being used. In the field of the tin or tin alloy plating bath, hydrochloric acid,
Inorganic acids such as sulfuric acid and borofluoric acid, and plating baths based on organic acids such as organic sulfonic acids and aliphatic carboxylic acids are used.
Plating baths based on organic sulfonic acids such as alkane sulfonic acids and alkanol sulfonic 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 are converted to stannic ions by being oxidized or anodized by oxygen in the air with long-term use, Further, the ions are hydrolyzed to generate fine particles of stannic oxide. The particle size of the fine particles of stannic oxide is 0.1 μm to several μm.
Since the particles are distributed within the range, the particles do not settle in the plating bath and are dispersed as suspended particles, and the transparency of the plating bath is significantly reduced.

Usually, the plating apparatus is provided with a filter for the purpose of removing foreign matters mixed in the plating bath, and the plating bath is continuously filtered. However, the filter used for filtration has a pore size of several μm to several tens of μm due to pressure loss, ease of maintenance, and constraints such as cost.
Since the fine particles of stannic oxide suspended in the plating bath become finer than the pore size of the filter, it is almost difficult to capture and remove the fine particles with a filter. It was

On the other hand, since the fine particles of stannic oxide generated in the tin or tin alloy plating bath are considered to adsorb many water molecules on the surface thereof, tin or tin alloy plating is performed in the presence of the fine particles. When this is applied, stannic oxide particles adsorbing many water molecules are co-deposited in the electrodeposition film. In this way, when many water molecules are contained in the plating film together with stannic oxide, the heat of soldering the plated components causes the water to evaporate and greatly expand in volume. There is a problem that voids (air bubbles) are generated in the part.

By the way, recently, electronic parts have been downsized year by year and the area to be joined by soldering has been miniaturized. Therefore, it is strongly demanded to secure 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 tin or tin alloy plating baths, smooth removal of stannic oxide generated during long-term use has become an important issue.

[0007]

2. Description of the Related Art As the prior art 1 for tin electroplating bath, Japanese Patent Application Laid-Open No. 56-116894 discloses that the electroconductivity of the plating bath is increased so that wastewater treatment is easier than conventional acid or alkaline baths. For the reason such as being based on the neutral plating bath of pyrophosphoric acid, for the purpose of preventing the oxidation of divalent tin, hydrazine, hypophosphorous acid, phosphorous 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, Japanese Patent Laid-Open No. 193296/1984 discloses:
Hydrazine dichloride as a reducing agent for reducing tetravalent tin to divalent based on stannous chloride, lead acetate and hydrochloric acid,
Or tin with addition of hydroquinone, hypophosphorous acid, etc.
A lead alloy plating bath is disclosed.

[0009]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Prior Art 1 or 2
Are both antioxidants such as hydroquinone and hypophosphorous acid.
By adding (or a reducing agent) to the plating bath, it is intended to prevent the oxidation of stannous ions (Sn ²⁺ ) in the electroplating bath. With these known antioxidants, etc.,
Although it has the effect of delaying the oxidation rate of stannous ions to some extent, suspended particles of stannic oxide may be generated from the time when the usage period is over 2 to 3 months, and the plating bath may become turbid and lose transparency. Many. Once the quality of the plating bath deteriorates to such a state, it is difficult to remove suspended particles of stannic oxide, which causes the turbidity of the bath, as described above. It also becomes impossible to secure the reliability of the bonding strength of the electrodeposition coating.

As described above, in the tin or tin alloy electroplating bath, the fine particles of stannic oxide cause voids. Since the generation of tin is related to the turbidity of the plating bath, it is realistic to take measures to suppress the turbidity of the bath and maintain the transparency. Based on this policy, the present invention aims to stabilize the transparency of a tin or tin alloy plating bath over time.

[0011]

Means for Solving the Problems The present inventors have studied a method for suppressing the oxidation of stannous ions in a tin plating bath or a tin alloy plating bath such as a tin-lead alloy, and have investigated the cause of turbidity. Egg oxide (that is, stannic oxide)
The behavior in the bath was investigated. Generally, when stannic oxide is generated in the tin plating bath or the tin alloy plating bath, the turbidity of the bath progresses, but the behavior of stannic oxide in the bath is unclear at many points, which is beyond the speculation range, Stannous oxide is considered to be not only suspended in the form of fine particles in the bath but also partially dissolved due to hydration, etc., so it is difficult to determine that everything will become cloudy. On the other hand, the fine particles of stannic oxide formed in the bath are extremely unlikely to undergo crystal growth or aggregation, and have the property of existing as fine particles, and this is the main reason why the turbidity of the bath cannot be eliminated. Absent.

[0012] Therefore, the inventors of the present invention, when fine particles of stannic oxide are generated in the plating bath, promote the crystal growth of the fine particles of stannic oxide, or coalesce and aggregate the fine particles. By enlarging the particle size, it was possible to capture these particles by an intermittent filtration process to remove them from the plating bath, thereby suppressing turbidity of the bath and maintaining transparency. As a result of intensive research based on the above idea of increasing the particle size of stannic oxide, the present applicant has found that a specific phosphorus compound promotes crystal growth or aggregation of stannic oxide particles, It was previously proposed in Japanese Patent Application No. 9-165322.

Next, in the course of proceeding with the research, the inventors of the present invention focused on suppressing the turbidity of tin or tin alloy plating bath, for example, catechol sulfonic acid, naphthol sulfonic acid, or gallic acid. When an antioxidant and a coagulation accelerator are added together to the bath, such as a combination of 3,4-dihydroxybenzoic acid and polyacrylamide, pyrophosphoric acid, or tartaric acid, the stannous ion in the bath is oxidized. In addition to suppressing the above, it was found that the turbidity of the plating bath can be suppressed and the transparency can be stabilized for a long period of time by intermittent filtration treatment of the bath, and the present invention has been completed.

That is, the present invention 1 is (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. Selected from the group consisting of (B) organic acids such as alkane sulfonic acid, alkanol sulfonic acid, and aliphatic carboxylic acid, or inorganic acids such as hydrochloric acid, sulfuric acid, and borofluoric acid. At least one acid, (C) 3,4-dihydroxybenzoic acid, 4-methoxycate
Cole, 3,4-dihydroxybenzyl alcohol, 4
-Methylcatechol, gallic acid, o-methoxypheno
2 (4-hydroxyphenyl) ethyl alcohol,
2,3-dihydroxynaphthalene-6-sulfonic acids,
2,3-dihydroxynaphthalene-5-sulfonic acids,
2-Naphthol-6,8-disulfonate dipotassium, or
Is a small amount of antioxidants selected from the group consisting of these salts.
At least one, selected from the group consisting of (D) phosphorus compounds, tartaric acid, sodium tartrate, ammonium tartrate, potassium tartrate, tartrate salts such as calcium tartrate, magnesium tartrate and Rochelle salt, and polymeric flocculants such as polyacrylamide. A tin and tin alloy plating bath containing at least one kind of aggregation promoter of stannic oxide fine particles.

[0015]

The present invention 2 is a tin and tin alloy plating bath characterized in that it further contains a surfactant in addition to the plating bath of the present invention 1 .

The third aspect of the present invention is the plating according to the first or second aspect of the present invention.
In addition to the bath , a tin and tin alloy plating bath is characterized by further containing a brightening agent.

The present invention 4 is any one of the above inventions 1 to 3.
The tin and tin alloy plating bath is characterized in that it further contains a semi-brightening agent in addition to the above plating bath.

The present invention 5 is (A) a mixture of a stannous salt and a stannous salt and a salt of a metal selected from lead, silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony. And (B) an organic acid such as alkane sulfonic acid, alkanol sulfonic acid or aliphatic carboxylic acid, or an inorganic acid such as hydrochloric acid, sulfuric acid or borofluoric acid. In a tin and tin alloy plating bath containing at least one of an acid and its salt, the soluble metal salt (A) and the acid (B) are added with the following (1) to
The compound represented by the formula (2), catechol sulfonic acid, hydroxy
Non-sulfonic acid, naphthol sulfonic acid, catechol,
Hydroquinone, resorcin, pyrogallol, phloroglu
Syn, phenol sulfonic acid, cresol sulfonic acid,
Selected from the group consisting of ascorbic acid or salts thereof
The antioxidant (C) and the aggregation promoter (D) of the present invention 1 are added in combination,

[Chemical 3] (In the formula (1), R is SO ₃ X (X is hydrogen, a metal such as sodium, potassium and calcium, NH ₄ etc.), COOY (Y is a metal such as hydrogen, sodium, potassium and calcium, N
H _4, etc.), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ , halogen; n is an integer of 1 to 4; m is an integer of 1 to 2, provided that when m = 2, R
Are mutually the same or different substituents; n = 1, m = 1
In the case of, R excludes SO ₃ H; in the case of n = 1 and m = 2,
R excludes combinations of SO ₃ H and CH ₃ ; n = 2, m =
In the case of 1, R excludes SO ₃ X. )

[Chemical 4] (In the formula (2), R is SO ₃ X (X is a metal such as hydrogen, sodium, potassium and calcium, NH _{4 and the} like), COOY (Y is a metal such as hydrogen, sodium, potassium and calcium, N
H _4, etc.), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ , halogen; n is an integer of 1 to 4; m is an integer of 1 to 2, provided that when m = 2, R
May be the same or different substituents; n, m
= 1, R excludes SO ₃ H. ) By intermittently repeating the filtration treatment in the coexistence of the antioxidant and the coagulation promoter to capture and remove the stannic oxide particles outside the bath, the turbidity of the plating bath is prevented and the transparency is improved with time. It is a method of controlling tin and tin alloy plating baths, which is characterized by making it stable.

The present invention 6 is (A) a mixture of a stannous salt and a stannous salt and a salt of a metal selected from lead, silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony. And (B) an organic acid such as alkane sulfonic acid, alkanol sulfonic acid or aliphatic carboxylic acid, or an inorganic acid such as hydrochloric acid, sulfuric acid or borofluoric acid. In a tin and tin alloy plating bath containing at least one acid, or further containing at least one of a surfactant, a brightening agent and a semi-brightening agent, the antioxidant of the present invention 5
The aggregating promoter of the present invention 1 is mixed in advance with at least one of an acid, a soluble metal salt, a surfactant, a brightener, and a semi-brightener, and the mixture is mixed with the remaining bath constituents at the time of building a bath. A method for preparing a tin and tin alloy plating bath, comprising:

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is firstly directed to a specific antioxidant.
Tin or tin alloy plating containing a stopping agent and a coagulation promoter
Bath, secondly, how to manage tin or tin alloy plating bath
Third, the preparation of the same tin or tin alloy plating bath
Is the way. In this case, the antioxidant of the second to third inventions
And the aggregation accelerator, as shown below, a known compound
Can be widely used including. The first invention is to prevent these oxidation.
Antioxidants and aggregation promoters, especially antioxidants limited to specific compounds
It is a fixed one. The second to third inventions (that is, the present invention)
Antioxidant used in the control method or preparation method of 5-6)
The stopping agent is a compound generally represented by the specific phenols of the formula (1) and the specific naphthols of the formula (2), or catechol sulfonic acid, hydroquinone sulfonic acid, naphthol sulfonic acid, catechol, hydroquinone, Resorcy
, Pyrogallol, phloroglucin, phenol sulfo
Acid, cresol sulfonic acid, ascorbic acid, or
It is selected from the group consisting of these salts. Above (1)
Examples of the phenols of the formula include catechols having one substituent represented by the following formula (3) and pyrogallols having one substituent represented by the formula (4).

[Chemical 5] (In the formula (3), R is SO ₃ X (X is hydrogen, a metal such as sodium, potassium, or calcium, NH ₄ or the like), COOY (Y is a metal such as hydrogen, sodium, potassium, or calcium, N
H _4, etc.), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ , halogen; n is an integer of 1 to 4; m is an integer of 1 to 2, provided that when m = 2, R
May be the same or different substituents; n, m
= 1, R excludes SO ₃ H. )

[Chemical 6] (In the formula (4), R is SO ₃ X (X is hydrogen, a metal such as sodium, potassium and calcium, NH ₄ etc.), COOY (Y is a metal such as hydrogen, sodium, potassium and calcium, N
H _4, etc.), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ , halogen; n is an integer of 1 to 4; m is an integer of 1 to 2, provided that when m = 2, R
May be the same or different substituents; n, m
= 1, R excludes SO ₃ H. )

Further, the divalent naphthols of the formula (2) have a substituent at the 6-position represented by the formula (5) below, 2,3
-Dihydroxynaphthalene and 2,3-dihydroxynaphthalene having a substituent at the 5-position represented by the formula (6) are preferable.

[Chemical 7] (In the formula (5), R is SO ₃ X (X is hydrogen, a metal such as sodium, potassium, calcium, NH ₄ or the like), COOY (Y is a metal such as hydrogen, sodium, potassium, calcium, or the like, N
H _4, etc.), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ , halogen; n is an integer of 1 to 4; m is an integer of 1 to 2, provided that when m = 2, R
May be the same or different substituents; n, m
= 1, R excludes SO ₃ H. )

[Chemical 8] (In the formula (6), R is SO ₃ X (X is hydrogen, a metal such as sodium, potassium, or calcium, NH ₄ or the like), COOY (Y is a metal such as hydrogen, sodium, potassium, or calcium, N
H _4, etc.), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ , halogen; n is an integer of 1 to 4; m is an integer of 1 to 2, provided that when m = 2, R
May be the same or different substituents; n, m
= 1, R excludes SO ₃ H. )

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

[Chemical 9] 4-methoxycatechol (see formula (8) below)

[Chemical 10] 3,4-dihydroxybenzyl alcohol ((9) below
(See formula)

[Chemical 11] 4-methylcatechol (see formula (10) below)

[Chemical 12] Catechol sodium polysulfonate (including Tyrone; see formula (11) below)

[Chemical 13] (In the formula (11), n is 2, 3, and 4.)

Specific examples of the pyrogallols of the above formula (4) are:
For example, gallic acid (see formula (12) below).

[Chemical 14]

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), and specific examples thereof are as follows. Is the street. o-Methoxyphenol (common name guaiacol, see formula (13) below)

[Chemical 15] 2 (4-Hydroxyphenyl) ethyl alcohol (See formula (14) below)

[Chemical 16]

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

[Chemical 17] (In the formula (15), X is hydrogen, a metal such as sodium, potassium, or calcium, NH ₄ or the like.) 2,3-dihydroxynaphthalene-5-sulfonic acid
(See formula (16) below)

[Chemical 18] (In the formula (16), X is hydrogen, a metal such as sodium, potassium, or calcium, NH ₄ or the like.)

Further, the compound contained in the naphthols of the above formula (2) may be one which does not belong to the polyvalent naphthols of the formulas (5) and (6), and its specific example is 2-Naphthol-6,8-disulfonate dipotassium
(See the formula (17) below) and the like.

[Chemical 19]

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

In the antioxidant of the above formula (2), the number n of hydroxyl groups bonded to the naphthalene ring is 1 to 4 and the number m of substituents R is 1 to 2. When the number of substituents R is 2,
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 the sulfonic acid group, in other words, α-naphtholsulfonic acid, β-naphtholsulfonic acid, etc. are excluded from the naphthols of the formula (2). . The amount of the above-mentioned antioxidant added is generally 0.05 to 50 g / L, preferably 0.1 to 10 g / L, based on the whole plating bath.

The control method or preparation method of the above inventions 5 to 6
The aggregating accelerator used in is a phosphorus compound, tartaric acid, or
It refers to sodium tartrate, ammonium tartrate, potassium tartrate, calcium tartrate, magnesium tartrate, tartrate salts such as Rochelle's salt (potassium sodium tartrate), and polymeric flocculants such as polyacrylamide. The phosphorus compound is as follows. (1) Orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid, hypophosphorous acid, phosphorous acid, and their sodium salts, potassium salts, calcium salts, magnesium salts, ammonium salts, barium salts, iron salts, zinc salts Inorganic phosphorus compounds such as salts such as sodium phosphate monobasic, hydrogen phosphate such as ammonium dihydrogen phosphate, and the like. (2) aminotri (methylenephosphonic acid), 1-hydroxyethylidene-1-diphosphonic acid, ethylenediaminetetra (methylenephosphonic acid), alkyl phosphates (e.g., ethylphosphoric acid, diethylphosphoric acid, etc.), and their sodium salts, potassium Organic phosphorus compounds such as salts, calcium salts, magnesium salts, ammonium salts, barium salts, iron salts, zinc salts and the like. The above coagulation accelerators can be used alone or in combination, and the addition amount thereof is generally 0.01 to 100 g / L, preferably 0.05 to 10 g / L with respect to the entire plating bath.
L, more preferably 0.1 to 5 g / L.

[0031]

In the control method or preparation method of the present invention 5-6
Is basically a novel antioxidant such as gallic acid, 3,4-dihydroxybenzoic acid, 4-methylcatechol, guaiacol, dihydroxynaphthalenesulfonic acid and naphtholdisulfonic acid, or catecholsulfonic acid, hydroquinonesulfonic acid, With respect to naphthol sulfonic acid or a salt thereof, the type of coagulation promoting agent on the other side is not so restricted and they can be freely combined. Also,
For well-known or known antioxidants such as catechol, hydroquinone, resorcin, pyrogallol, phloroglucin, phenolsulfonic acid, cresolsulfonic acid, ascorbic acid, or salts thereof, tartaric acid, sodium tartarate, tartaric acid such as ammonium tartarate, etc. A salt, a hydrogen phosphate such as sodium monohydrogen phosphate or ammonium dihydrogen phosphate, or an aggregation promoter such as polyacrylamide can be combined.

As described above, the management method of the present invention 5 or 6 or
In the preparation method, if 3,4-dihydroxybenzoic acid, gallic acid, dihydroxynaphthalene sulfonic acid, naphthol disulfonic acid, catechol sulfonic acid, etc. are selected as antioxidants, they are not so restricted by the type of coagulation promoter of the other party. In addition, the generation of stannic oxide can be suppressed, and the transparency of the bath can be maintained for a long time. On the contrary, when tartaric acid and its salt, hydrogen phosphate, polyacrylamide and the like are selected as the aggregation accelerator, similar results can be obtained without being restricted by the kind of the antioxidant. On the other hand
The first aspect of the invention (that is, the first aspect of the invention) is to suppress the turbidity of the bath and to make
From the standpoint of stability of brightness over time, the antioxidants and coagulants mentioned above
The collection accelerator is limited to specific components, especially
As the inhibitor, a specific compound different from the known compounds is selected.
It is a thing. That is, the above antioxidant is 3,4-dihydric
Droxybenzoic acid, 4-methoxycatechol, 3,4-
Dihydroxybenzyl alcohol, 4-methylcatechol
, Gallic acid, o-methoxyphenol, 2 (4-hydride)
Roxyphenyl) ethyl alcohol, 2,3-dihydroxy
Sinaphthalene-6-sulfonic acids, 2,3-dihydroxy
Sinaphthalene-5-sulfonic acids, 2-naphthol-
From dipotassium 6,8-disulfonate or salts thereof
At least one selected from the group consisting of Well
In addition, the agglomeration promoter is a phosphorus compound, tartaric acid, sodium tartarate.
Thorium, ammonium tartrate, potassium tartrate, tartar
Calcium acid, magnesium tartrate, Rochelle salt, etc.
Polymeric flocculants such as tartrate and polyacrylamide
Is at least one selected from the group consisting of:
The following specific examples are preferable as the combination of these specific antioxidants and aggregation accelerators. Antioxidant Aggregation promoter (1) 3,4-Dihydroxybenzoic acid Pyrophosphoric acid (2) Gallic acid Tartaric acid (3) Gallic acid Ammonium dihydrogen phosphate (4) 2,3-Dihydroxynaphthalene Polyacrylamide-6-sulfonic acid Sodium (5) Gallic acid Pyrophosphate (6) 2,3-Dihydroxynaphthalene Pyrophosphate-5-sulfonate sodium (7) Guayacol pyrophosphate (8) Gallic acid Ammonium tartrate (9) 3,4-Dihydroxybenzoic acid Tartrate ( 10) 3,4-Dihydroxybenzoic acid hypophosphorous acid (11) Gallic acid Sodium hypophosphite (12) 3,4-Dihydroxytartaric acid-benzyl alcohol (13) 2 (4-Hydroxyphenyl) ammonium dihydrogen phosphate -Ethyl alcohol (14) 2,3-dihydroxynaphthalene Ammonium dihydrogen phosphate-6-sulfonate sodium (15) 2,3-Dihydroxyna The array type ammonium tartrate 5-sodium sulfonate

The plating bath of the present invention 1 or the present invention 5 to 6
In the control method or preparation method of, the tin plating bath and the tin alloy plating bath are targeted, and this tin alloy contains tin, lead, silver, zinc, bismuth, indium, nickel, cobalt, and copper as described above. , Tin, nickel, and two-component tin alloys such as gold, lead, tin-silver, tin-bismuth, tin-nickel, tin-indium, tin-cobalt, tin-copper, tin-gold, tin-antimony. A ternary tin alloy such as zinc or tin-copper-zinc is also included. As the mixture of the stannous salt or the stannous salt and the salt of a metal other than tin, any soluble salt can be used, but salts with the acid (particularly, organic sulfonic acid) are preferable, and tin. In addition, the total concentration of the other metals (the added amount converted as the metal) is generally 5 to 100 g / L.

As the above-mentioned acid, alkanesulfonic acid, which has a relatively mild reaction in the plating bath and is easy to treat wastewater,
Organic sulfonic acids such as alkanol sulfonic acids or organic acids such as aliphatic carboxylic acids are preferable, but inorganic acids such as hydrochloric acid, borofluoric acid, sulfuric acid, hydrosilicofluoric acid and perchloric acid can also be selected. it can. The above-mentioned acids are used alone or in combination, and the addition amount of the acid is generally 0.1 to 400 g / L,
It is preferably 70 to 150 g / L.

As the above 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.

The above alkanol sulfonic acid has the chemical formula C _m H _{2m + 1} -CH (OH) -C _p H _2p -SO ₃ H (for example, m = 0.
~ 2, p = 1 to 10) can be used. Specifically, 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-
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 can be mentioned.

As the above-mentioned aliphatic carboxylic acid, generally,
A carboxylic acid having 1 to 6 carbon atoms can be used. In particular,
Examples thereof include acetic acid, propionic acid, butyric acid, citric acid, tartaric acid, gluconic acid, and sulfosuccinic acid.

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 selected from nonionic surfactants, cationic surfactants, anionic surfactants and amphoteric surfactants can be used.

Specific examples of the nonionic surfactant include C _{1 to} C ₂₀ alkanols, phenols, naphthols, bisphenols, C _{1 to} C ₂₅ alkylphenols, arylalkylphenols, C _{1 to} C ₂₅ alkylnaphthols, C ₁ to C ₂₅ alkoxylated phosphoric acid (salt), sorbitan ester, styrenated phenol, polyalkylene glycol, C ₁ -C ₂₂ aliphatic amine, C ₁ -C ₂₂ aliphatic amide and the like are added to ethylene oxide (EO) and / or propylene oxide ( Examples thereof include those obtained by addition-condensing 2 to 300 mol of PO), C _{1 to} C ₂₅ alkoxylated phosphoric acid (salt), and the like.

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, cetyl alcohol. , Oleyl alcohol, docosanol and the like. Similarly, examples of bisphenols include bisphenol A and bisphenol B. As C ₁ -C ₂₅ alkylphenols, mono-, di-, or trialkyl-substituted phenols such as p-butylphenol, p-isooctylphenol, p-nonylphenol, p-hexylphenol, 2,4-dibutylphenol, 2,4, 6-tributylphenol, p-dodecylphenol, p-laurylphenol, p-stearylphenol and the like can be mentioned. Examples of the arylalkylphenol include 2-phenylisopropylphenyl and the like. Examples of the alkyl group of the C ₁ -C ₂₅ alkylnaphthol include methyl, ethyl, propyl, butylhexyl, octyl, decyl, dodecyl, octadecyl and the like, which may be at any position of the naphthalene nucleus.
The C ₁ -C ₂₅ alkoxylated phosphoric acid (salt) has the following general formula:
It is represented by (a).

[0042]

[Chemical 20] (In the formula (a), R _a and R _b are the same or different C _{1 to} C ₂₅ alkyl, but one of them may be H. M is H or an alkali metal.)

The sorbitan ester is a mono-, di- or triester-esterified 1,4-, 1,5- or 3,6-sorbitan such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan distearate, sorbitan diester. Examples thereof include oleate and sorbitan mixed fatty acid ester. Examples of C ₁ -C ₂₂ aliphatic amines include propylamine, butylamine, hexylamine, octylamine, decylamine, laurylamine, stearylamine, saturated and unsaturated fatty acid amines such as ethylenediamine and propylenediamine. C ₁ ~
Examples of the C ₂₂ aliphatic amide include amides such as propionic acid, butyric acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and behenic acid.

Further, as the nonionic surfactant, R ₁ N (R ₂ ) ₂ → O (in the above formula, R ₁ is C ₅ -C ₂₅ alkyl or RCONHR ₃ (R
₃ represents C ₁ -C ₅ alkylene), R ₂ is the same or different C
Shows the ₁ -C ₅ alkyl. ) Etc. can be used.

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

As the above cationic surfactant, a quaternary ammonium salt represented by the following general formula (b) is used.

[0047]

[Chemical 21] (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. ₁₀ alkyl or benzyl) or a pyridinium salt represented by the following general formula (c).

[0048]

[Chemical formula 22] (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 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,
Examples include lauryl amine acetate and octadecyl amine acetate.

Examples of the anionic surfactants include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkylphenyl ether sulfates, alkylbenzene sulfonates and the like.
Examples of the alkyl sulfates include sodium lauryl sulfate and sodium oleyl sulfate. Examples of the polyoxyethylene alkyl ether sulfate include polyoxyethylene (EO12) sodium nonyl ether sulfate and polyoxyethylene (EO15) sodium dodecyl ether sulfate. As polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene
(EO15) nonyl phenyl ether sulfate and the like. Examples of the alkylbenzene sulfonate include sodium dodecylbenzene sulfonate.

As the amphoteric surfactant, betaine,
Examples thereof include sulfobetaine and aminocarboxylic acid.
Also, a sulfated or sulfonated adduct of a condensation product of ethylene oxide and / or propylene oxide with an alkylamine or a diamine can be used. The betaine is represented by the following general formula (d) or (e).

[0052]

[Chemical formula 23] (In the formula (d), R ₇ represents C ₁ -C ₂₀ alkyl, R ₈ and R ₉ represent the same or different C ₁ -C ₅ alkyl, and n represents an integer of _{1 to} 3.)

[0053]

[Chemical formula 24] (In formula (e), R ₁₀ is C ₁ -C ₂₀ alkyl, and 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 can be mentioned. Sulfated and sulfonated adducts include sulfuric acid adducts of ethoxylated alkylamines and sulfonated Examples thereof include sodium salt of lauric acid derivative.

Examples of the sulfobetaines include coconut oil fatty acid amidopropyldimethylammonium-2-hydroxypropanesulfonic acid, N-cocoylmethyltaurine sodium, N-palmitoylmethyltaurine sodium 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 above nonionic surfactants may be used in combination, and the amount added to the plating bath is generally 0.05 to 100 g / L, preferably 0.1.
~ 50 g / L.

Specific examples of the brightening agent that can be used in the present invention 4 are 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.furfuridineacetone, sub.tenylideneacetone, 4- (1-naphthyl) -3-buten-2-one, 4- (2- Frill)-
3-buten-2-one, 4- (2-thiophenyl) -3-
Butene-2-one, curcumin, benzylidene acetylacetone, benzalacetone, acetophenone, (2,4
-, 3,4-) dichloroacetophenone, benzylideneacetophenone, 2-cinnamylthiophene, 2- (ω-
(Benzoyl) vinyl furan, vinyl phenyl ketone, acrylic acid, methacrylic acid, ethacrylic acid, ethyl acrylate, methyl methacrylate, butyl methacrylate, crotonic acid, pyropyrene-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.

In addition, the plating bath of the present invention may contain the semi-brightening agent of the present invention 5 in order to improve the smoothness of the plating surface. When the semi-brightening agent is used in combination with various kinds of the above surfactants, a more synergistic effect is exhibited. The semi-brightening agent in this case can generally be used as long as it is a semi-brightening agent used for tin or tin-lead alloy plating, but as a particularly useful semi-brightening agent, the following general formula can be used.
Examples include those represented by (f) to (i).

[0060]

[Chemical 25] (In the formula (f), R is hydrogen, an alkyl group (C ₁ -C ₄ ), or a phenyl group, and R ^I is hydrogen, a hydroxyl group, or, if not present, R ^II.
Is an alkylene group (C ₁ -C ₄ ), a phenylene group or a benzyl group, and R ^III is hydrogen or an alkyl group (C ₀ -C ₄ ). )

[0061]

[Chemical formula 26] (In the formula (g), R and R ^I are alkyl groups (C _{1 to} C ₁₈ ).)

[0062]

[Chemical 27] (In the formula (h), R is hydrogen, an alkyl group (C ₁ -C ₄ ), or a phenyl group.)

[0063]

[Chemical 28] (In the formula (i), R ₁ , R ₂ , R ₃ , R ₄ and R ₅ may be the same or different, and are (1) H, (2) -SH, (3) -OH, (4 )
OR (R is a C ₁ -C ₆ alkyl group optionally substituted by —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, especially 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')) Examples include ethyl-1,3,5-triazine and phenyl salicylate.

Similarly, as the benzothiazole type semi-brightener of the general formula (i), 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-benzothiazole thioacetic acid and the like can be mentioned.

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

The addition concentration of each of the above components in the plating bath of the present invention is barrel plating, rack plating, high speed continuous plating,
It can be arbitrarily adjusted and selected for rackless plating. Further, in the plating bath of the present invention, in addition to various additives such as the above brightener, a complexing agent used in a usual plating bath,
Of course, a pH adjuster, a buffer, etc. can be added.

[0068]

[Effects of the Invention] (1) In a tin bath or a tin alloy bath, addition of an antioxidant alone has a certain preventive effect on the generation of stannic oxide, but the turbidity of the bath increases with the passage of days. (See FIGS. 14 to 15 and FIG. 17) On the contrary, when the coagulation accelerator is added alone, there is no effect of preventing the generation of stannic oxide, and turbidity of the bath cannot be suppressed (FIGS. 16 and 18).
reference). On the other hand, as in the present invention 1 or 2, or 6, an antioxidant and a coagulation accelerator are combined and added to a tin or tin alloy plating bath, and intermittent filtration treatment is performed under the coexistence thereof.
As a matter of fact , as shown in the test examples described later (see FIGS. 1 to 13), the synergistic effect of the stannic oxide can be effectively suppressed as a whole, and in particular, the turbidity of the plating bath can be tested. During the entire period from the beginning to the end of the bath, the degree of transition remained at a low level and the transparency of the bath was maintained. That is,
If an antioxidant and a coagulation accelerator are added to the tin or tin alloy bath together and the filtration process is repeated intermittently, not only the oxidation of stannous ions in the bath can be effectively suppressed but also the number of days after the bath preparation elapses. Even if stannic oxide fine particles are generated due to the progress of oxidation in the bath, the combined use of the above treatments promotes aggregation of stannic oxide, or crystal growth causes oxidation of stannic oxide with an increased particle size. It can be captured every time the tin is filtered. Therefore, stannic oxide in the plating bath can be easily removed to the outside, and thus the transparency of the plating bath can be maintained for a long period of time (stabilized over time).

In this case, the combined use of the treating agent of the present invention is
As shown in Example 4 below (see FIG. 4), catechol,
Alternatively, a known antioxidant such as hydroquinone may be combined with a known aggregation promoter such as polyacrylamide, or as shown in Example 2 (see FIG. 2) described later, a novel oxidation agent such as gallic acid may be used. A combination of an inhibitor and a new aggregation accelerator such as tartaric acid may be used. In addition, as shown in Example 1 below (see FIG. 1), novel compounds such as 3,4-dihydroxybenzoic acid and gallic acid, catechol sulfonic acid, hydroquinone sulfonic acid, naphthol sulfonic acid, or salts thereof. A combination of an antioxidant selected from the above and an aggregation accelerator such as pyrophosphoric acid proposed by the present applicant in the above-mentioned prior application may be used. Specifically, 3,4-dihydro
Xybenzoic acid and pyrophosphoric acid, gallic acid and pyrophosphoric acid,
3,4-dihydroxybenzoic acid and tartaric acid, gallic acid and sake
A combination of formic acid, gallic acid and ammonium dihydrogen phosphate
The combination can be expected to have a remarkable effect in suppressing both generation of stannic oxide and turbidity of the bath. Especially, with regard to the stability over time of the transparency of the plating bath (persistence) ,
When gallic acid is selected , the type of aggregation partner of the combination partner does not matter so much. Conversely, when tartaric acid or a salt thereof, or hydrogen phosphate is selected as the aggregation promoter, the type of antioxidant of the combination partner is selected. The excellent effect can be expected regardless of.

(2) When a surfactant is additionally mixed in the plating bath as in the case of the present invention 2 , the particle appearance, adhesion, denseness, etc. of the tin or tin alloy plating film can be further favorably promoted.

(3) When a brightening agent or a semi-brightening agent is additionally mixed in the plating bath as in the third or fourth aspect of the present invention , the glossiness or smoothness of the plating film can be favorably promoted.

(4) In preparing the electroplating bath as in the present invention 6, an antioxidant and an aggregation accelerator are separately added with an acid,
If it is mixed with at least one of surfactants, semi-brightening agents, etc. in advance, and then combined with other bath constituents when building the bath,
The coagulation promoting action of stannic oxide can be maintained higher, and the antioxidant and the coagulation promoting agent can be uniformly dissolved in the plating bath, which facilitates bath preparation.

[0073]

[Examples] Examples of electroplating baths of tin or tin alloys will be sequentially described below, and when the plating baths of the examples are aerated for a long period of time, basically when filtration is repeated every one week, A test example in which the degree of suspension of the bath with stannic oxide was measured with time will be described. It should be noted that the present invention is not limited to the following embodiments, and many modifications can be made within the scope of the technical idea of the present invention.

The following Examples 1 to 10 and Comparative Examples 1 to 3 are tin-lead alloy plating baths, and Comparative Examples 1 and 2 are examples in which an antioxidant (catechol, catechol sulfonic acid) is added alone, and Comparative Examples. No. 3 is an example in which a coagulation accelerator (tartaric acid) was added alone. Further, Examples 11 to 18 are examples of tin alloy plating baths other than tin-lead alloys, and Examples 19 to 20 are examples of tin plating baths.

Example 1 A tin-lead alloy plating bath having the following composition was prepared. 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 Pyroline Acid 1.0 g / L However, the preparation was carried out by a one-bath system in which all the bath constituents 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 the initial values are the following Examples 2 to 20 and Comparative Examples 1 to 5).
Both are the same).

Example 2 A tin-lead alloy plating bath having the following composition was prepared. 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 Tartaric acid 1.0 g / L

Example 3 A tin-lead alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Catechol-4-sulfonic acid (35%) 5.0 g / L Ammonium tartrate 1.2g / L

Example 4 A tin-lead alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Catechol-4-sulfonic acid (35%) 5.0 g / L polyacrylamide 0.05 g / L Incidentally, as the polyacrylamide, a commercially available product having a molecular weight of about 10 million was used.

Example 5 A tin-lead alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonate 67.2 g / L Gallic acid 1.2 g / L Ammonium dihydrogen phosphate 0 .1 g / L

Example 6 A tin-lead alloy plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonate 67.2 g / L 2,3-dihydroxynaphthalene-6-sodium sulfonate 1 0.0 g / L Polyacrylamide 0.05 g / L

Example 7 A tin-lead alloy plating bath was prepared with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonate 67.2 g / L Catechol-4-sulfonic acid (35%) 5 g / L Ammonium dihydrogen phosphate 0.1 g / L

Example 8 A tin-lead alloy plating bath was prepared with the following composition. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonate 67.2 g / L Catechol-4-sulfonic acid (35%) 5 g / L Pyrophosphoric acid 1 g / L

Example 9 A tin-lead alloy plating bath having the following composition was prepared. 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 Pyrophosphate 1.0 g / L

Example 10 A tin-lead alloy plating bath was prepared with the following composition. 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 Tartaric acid 1.0 g / L

Example 11 A tin-cobalt alloy plating bath having the following composition was prepared. Stannous chloride 45 g / L Cobalt sulfate 300 g / L Methanesulfonic acid 50 g / L Gluconic acid 80 g / L pH (adjusted with aqueous ammonia) 4.0 Catechol-4-sulfonic acid (35%) 5 g / L Dihydrogen phosphate Ammonium 0.1 g / L

Example 12 A tin-indium alloy plating bath having the following composition was prepared. 2-Propanol sulfonic acid stannous (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 Gallic acid 1.2g / L Tartaric acid 1.0g / L

Example 13 A tin-nickel alloy plating bath was prepared with the following composition. 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 ammonia water) 4.0 3,4 -Dihydroxybenzoic acid 1.2 g / L Pyrophosphoric acid 1.0 g / L

Example 14 A tin-bismuth alloy plating bath having the following composition was prepared. 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 1.0 g / L Ammonium dihydrogen phosphate 0.1 g / L

Example 15 A tin-silver alloy plating bath having the following composition was prepared. 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 1.0 g / L polyacrylamide 0.05g / L

Example 16 A tin-zinc alloy plating bath having the following composition was prepared. 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 Lauryl dimethyl ammonium 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 Tartaric acid 1.0 g / L

Example 17 A tin-antimony alloy plating bath was prepared with the following composition. 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 1.2 g / L Pyroline Acid 1.0g / L

Example 18 A tin-copper alloy plating bath was prepared with the following composition. 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 catechol-4-sulfonic acid 1.7 g / L Tartaric acid 1.0 g / L

Example 19 A tin plating bath having the following composition was prepared. Stannous sulfate (SnSO ₄ ) 50 g / L Sulfuric acid 100 g / L Nonylphenol polyethoxylate (EO15) 10 g / L 2-Mercaptobenzothiazole 0.5 g / L Gallic acid 1.0 g / L Tartaric acid 1.0 g / L

Example 20 A tin plating bath having the following composition was prepared. Stannous methanesulfonate (as Sn ²⁺ ) 20 g / L 2-propanol sulfonic acid 150 g / L o-cresol sulfonic acid 10 g / L α-naphthol ethoxylate (EO10) 10 g / L 2,3-dihydroxynaphthalene-6 -Sodium sulfonate 1.2 g / L Pyrophosphoric acid 1.0 g / L

Comparative Example 1 A tin-lead alloy plating bath having the following composition was prepared. Comparative Example 1 is an example in which an antioxidant is added alone. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonate 67.2 g / L Catechol 1.0 g / L

Comparative Example 2 A tin-lead alloy plating bath was prepared with the following composition. Comparative Example 2 is an example in which another type of antioxidant was added alone. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonic acid 67.2 g / L Catechol-4-sulfonic acid (35%) 5.0 g / L

Comparative Example 3 A tin-lead alloy plating bath was prepared with the following composition. Comparative Example 3 is an example in which the aggregation promoter was added alone. Stannous methanesulfonate (as Sn ²⁺ ) 30 g / L Lead methanesulfonate (as Pb ²⁺ ) 3 g / L Free methanesulfonate 67.2 g / L Tartaric acid 7 g / L

Comparative Example 4 A tin plating bath having the following composition was prepared. Comparative Example 4 is an example in which tartaric acid was omitted and only gallic acid (antioxidant) was added alone based on Example 19 described above. Stannous sulfate (SnSO ₄ ) 50 g / L Sulfuric acid 100 g / L Nonylphenol polyethoxylate (EO15) 10 g / L 2-Mercaptobenzothiazole 0.5 g / L Gallic acid 1.0 g / L

Comparative Example 5 A tin plating bath having the following composition was prepared. Comparative Example 5 is an example in which gallic acid was omitted and only tartaric acid (aggregation promoter) was added alone based on Example 19 described above. 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

Therefore, the bath filtration was repeated intermittently while subjecting each plating bath to aeration for a long period of time, and the degree of generation of stannic oxide in each plating bath after filtration ( That is, the degree of oxidation of stannous ion) and the degree of turbidity of the bath were measured over time.
However, as an index for measuring the degree of aggregation of stannic oxide, the median diameter of stannic oxide is important, but in this test example,
Since the bath is filtered intermittently, in the measurement of the median diameter of stannic oxide present in the bath after filtration, only the fine particles that have passed through the filter medium can be measured, so there is little meaning in the measurement. Basically, the measurement test of the median diameter was omitted.

<< Example of Evaluation Test of Plating Bath with Time >> 500 mL of the prepared tin or tin alloy bath plating solution was placed in a 1-liter tall beaker, and the beaker was placed in a constant temperature bath maintained at 50.degree. Then, while continuously blowing air into the plating solution at a rate of 1.5 L / min by a pump, the filtration process is basically repeated every week to maintain the transparency of the plating bath. Tested mainly on sex.

(1) Measurement of Stannous Oxide Generation Rate The above-mentioned air blowing operation was continued for a maximum of about 35 days, and each plating solution was taken as a sample at the elapse of a predetermined number of days, and Sn in the solution was sampled. The total content of ²⁺ and Sn ⁴⁺ was measured by atomic absorption spectrophotometry, and the content of Sn ²⁺ was measured by iodometric titration method. The content (%) of tin ion (Sn ⁴⁺ ) was calculated for each, and the amount of stannic oxide generated in the bath was evaluated. However,
The stannic oxide obtained by the measurement is presumed to include both suspended particles as particles in the bath and dissolved particles.

(2) Measurement of turbidity of plating solution After starting the aeration operation of (1) above, each plating solution after filtration was sampled for each filtration treatment, and the absorbance of each sample was measured with pure water as a reference wavelength. Each measurement was performed at 660 nm using a spectrophotometer (U-2000 type double beam spectrophotometer; manufactured by Hitachi, Ltd.).

<< Evaluation of Plating Bath >> FIGS. 1A-B to 13A-
B and FIGS. 14A-B to 18A-B show the results. The present invention is basically a problem of the oxidation of stannous ions in a tin or tin alloy plating bath and the agglomeration of oxides, and a test of similar or similar tendencies among various tin alloy plating baths. Since the results are obtained and it is possible to represent the tin alloy plating bath with the tin-lead alloy bath, in the evaluation of each plating bath below, the tin-lead alloy plating bath and the tin plating bath are evaluated as model cases, and As the tin alloy plating bath other than the lead alloy, a tin-bismuth alloy bath is described only as an example.

(1) Comparative evaluation of the amount of stannic oxide generated (see A in each figure) Regarding the amount of stannic oxide generated in the tin-lead alloy plating bath, a comparison was made by adding an antioxidant (catechol) alone. In Example 1, it has remained at a little over 10% (Fig. 1
4A), a certain antioxidant effect was observed. Comparative Example 2 in which another type of antioxidant (catechol-4-sulfonic acid) was added alone remained around 10% (see FIG. 15A). In Comparative Example 3 in which the aggregation promoter (tartaric acid) was added alone,
After the lapse of 2 weeks, the content rate of stannic ions increased to about 85% (see FIG. 16A), and it was found that the antioxidant effect could not be expected. On the other hand, among Examples 1 to 10 in which the antioxidant and the aggregation accelerator are combined, first, 3,4-
In Example 1 in which dihydroxybenzoic acid and pyrophosphoric acid were combined, as in Comparative Example 2 of catecholsulfonic acid, 1
The change was around 0%, and an effective antioxidant effect was confirmed (see FIG. 1A). Similar results were obtained in Examples 2 to 4 and 6, 9 to 10 (see FIGS. 2A to 4A, 6A, and 9A to 10A). In particular, in Examples 5 and 7 to 8, the generation amount approached zero with the lapse of days, and a remarkable antioxidant effect was confirmed (see FIGS. 5A and 7A to 8A). In Example 14 (see FIG. 11A) in which 3,4-dihydroxybenzoic acid and ammonium dihydrogen phosphate were combined in the tin-bismuth alloy plating bath, the amount of stannic oxide generated was from about 10% to about 5%. It continued to decrease and the excellent antioxidant effect was confirmed. In the tin plating bath, the amount of stannic oxide generated was around 10% in Comparative Example 4 (see FIG. 17A) in which only gallic acid was added, whereas in Example 19 in which gallic acid and tartaric acid were added (see FIG. 12A) or Example 20 in which sodium 2,3-dihydroxynaphthalene-6-sulfonate and pyrophosphoric acid were added (FIG. 13).
(See A), the rate remained below 10%. In Comparative Example 5 (FIG. 18A) to which only tartaric acid was added, the content of stannic ions increased to about 85% after 3 weeks, and the antioxidant effect could not be expected.

(2) Comparative Evaluation of Absorbance (Refer to B of Each Figure) Regarding tin-lead alloy plating bath, when the turbidity of the bath is large, the absorbance also increases, and basically the turbidity and the absorbance are in a proportional relationship. First, Comparative Examples 1 and 2 in which catechol or catechol sulfonic acid was added alone showed the same result. In the plating baths in which the antioxidant or the coagulation accelerator was added respectively, was the turbidity of the bath increased? However, it was confirmed that the level of turbidity was high and turbidity could not be effectively suppressed (Fig. 1
4B-15B). In Comparative Example 3 in which tartaric acid was added alone, the turbidity level was low, but the turbidity increased with the passage of days (see FIG. 16B). On the other hand, among Examples 1 to 10 in which the antioxidant and the aggregation accelerator were combined, Example 1 in which 3,4-dihydroxybenzoic acid and pyrophosphoric acid were combined was compared with Comparative Examples 1 to 3 above. Example 3 in which gallic acid and tartaric acid were combined, Example 3 in which catechol sulfonic acid and ammonium tartrate were combined, and catechol sulfonic acid and polyacrylamide were maintained, maintaining a markedly low turbidity throughout the entire period of 30 days from the beginning. Example 4 in combination or 2,3-dihydroxynaphthalene-6
-Example 6 in which sulfonate and polyacrylamide were combined, Example 9 in which gallic acid and pyrophosphoric acid were combined, and Example 10 in which 3,4-dihydroxybenzoic acid and tartaric acid were combined also showed low turbidity ( 1B-
4B, FIG. 6B, and FIGS. 9B to 10B). In Example 5 in which gallic acid and ammonium dihydrogen phosphate were combined, the initial turbidity was slightly high, but thereafter the turbidity was sharply reduced, and the turbidity was further reduced while continuing to decrease (FIG. 5B).
reference). In Example 7 in which catechol sulfonic acid and ammonium dihydrogen phosphate were combined, the initial turbidity was the same as that in Example 5, but the turbidity was almost suppressed over 2 to 3 weeks, and catechol sulfonic acid and pyrophosphoric acid were added. The combined Example 8 also showed a remarkable tendency that the initial turbidity was slightly high, but the turbidity was sharply reduced after 1 week. In Example 14 (see FIG. 11B) in which 3,4-dihydroxybenzoic acid and ammonium dihydrogen phosphate were combined in the tin-bismuth alloy plating bath, the initial turbidity was relatively small, and thereafter, the turbidity was low, and tin- The level was as good as that of the lead alloy plating bath (transparency). In Comparative Example 4 in which only gallic acid was added to the tin plating bath (see FIG. 17B) and Comparative Example 5 in which only tartaric acid was added (FIG. 18B), the turbidity of the bath tended to increase. On the other hand, Example 19 in which gallic acid and tartaric acid were added (see FIG. 12B) and Example 20 in which sodium 2,3-dihydroxynaphthalene-6-sulfonate and pyrophosphoric acid were added (see FIG. 13B), The level of turbidity was generally low, and the difference with Comparative Examples 4 to 5 was clear.

(4) Comprehensive Evaluation In Comparative Examples 1 and 2 in which an antioxidant was added alone to the tin-lead alloy plating bath, there was a certain preventive effect on the generation of stannic oxide, but the turbidity of the bath passed for several days. It increased with the increase (see FIGS. 14 to 15). Further, in Comparative Example 3 in which the aggregation promoter was added alone, there was no effect of preventing the generation of stannic oxide, and turbidity of the bath could not be suppressed (see FIG. 16). On the other hand, in Examples 1 to 10 in which the antioxidant and the coagulation accelerator were used in combination, the generation of stannic oxide can be effectively suppressed as a whole, and in particular, the turbidity of the plating bath was from the initial stage to the final stage of the test. The degree of transparency of the bath remained high throughout the entire period up to and including (Fig. 1
10). In Example 14 in which the antioxidant and the coagulation accelerator were added together with respect to the tin-lead alloy plating bath, the generation of stannic oxide can be effectively suppressed and the bath can be effectively suppressed as in the case of the tin-lead alloy plating bath. The transparency was also persistent (see Figure 11). Regarding the tin plating bath, also in the case of the tin plating bath, Examples 19 to 20 (FIGS.
3) and Comparative Examples 4 to 5 (see FIGS. 17 to 18), when the antioxidant and the coagulation accelerator are added together, the oxidation of the same amount as that of the tin-lead alloy plating bath occurs. The generation of bistin was effectively suppressed, and the transparency of the bath was long-lasting.

As described above, when the antioxidant and the coagulation accelerator are added together to the tin or tin alloy bath and the filtration treatment is repeated intermittently, the oxidation of stannous ion in the bath can be effectively suppressed. Even if the oxidation of the bath progresses with the lapse of days after preparation of the bath and fine particles of stannic oxide are generated, the fine particles are promoted aggregation or crystal growth due to the synergistic action of the above-mentioned treatment agent, and the particle diameter is increased. It means that the stannic oxide with increased amount is captured every time the filtration process is performed (that is, each time the filter attached to the plating device is intermittently driven). Therefore,
The stannic oxide in the bath is easily removed to the outside, so that the transparency of the plating bath is maintained for a long time (stabilized over time).

[Brief description of drawings]

FIG. 1 is a diagram showing test results in the case where a tin-lead alloy plating bath of Example 1 was subjected to intermittent filtration treatment while aerating, and FIG.
FIG. 1B is a time-dependent change diagram showing the absorbance of the bath after filtration, showing the time-dependent change in the content of valent tin ions.

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

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

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.

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.

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.

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

11 is a view corresponding to FIG. 1 showing a tin-bismuth alloy plating bath of Example 15. FIG.

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

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

14 is a view showing a tin-lead alloy plating bath of Comparative Example 1. FIG.
FIG.

FIG. 15 is a view showing a tin-lead alloy plating bath of Comparative Example 2;
FIG.

16 is a view showing a tin-lead alloy plating bath of Comparative Example 3. FIG.
FIG.

FIG. 17 is a view corresponding to FIG. 1 showing a tin plating bath of Comparative Example 4.

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

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masakazu Yoshimoto 8 21 21 Minami Futami, Futami-cho, Akashi-shi, Hyogo Inside Daiwa Kasei Laboratory Co., Ltd. (56) Reference JP-A-58-42786 (JP, A) JP JP-A-9-78285 (JP, A) JP-A-8-269770 (JP, A) JP-A-8-260186 (JP, A) JP-A-8-260185 (JP, A) JP-A-8-74097 (JP , A) JP 8-53790 (JP, A) JP 7-3493 (JP, A) JP 5-171489 (JP, A) JP 5-44074 (JP, A) JP 4-236796 (JP, A) JP-A-2-301589 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C25D 3/32 C25D 3/60

Claims (6)

(57) [Claims] 1. (A) stannous salt, stannous salt and lead,
(B) alkane sulfonic acid, alkanol sulfonic acid, aliphatic carboxylic acid, which is a soluble salt consisting of a mixture of salts of metals selected from silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony Or at least one acid selected from inorganic acids such as hydrochloric acid, sulfuric acid and borofluoric acid, (C) 3,4-dihydroxybenzoic acid, 4-methoxycate
Cole, 3,4-dihydroxybenzyl alcohol, 4
-Methylcatechol, gallic acid, o-methoxypheno
2 (4-hydroxyphenyl) ethyl alcohol,
2,3-dihydroxynaphthalene-6-sulfonic acids,
2,3-dihydroxynaphthalene-5-sulfonic acids,
2-Naphthol-6,8-disulfonate dipotassium, or
Is a small amount of antioxidants selected from the group consisting of these salts.
At least one, selected from the group consisting of (D) phosphorus compounds, tartaric acid, sodium tartrate, ammonium tartrate, potassium tartrate, tartrate salts such as calcium tartrate, magnesium tartrate and Rochelle salt, and polymeric flocculants such as polyacrylamide. A tin and tin alloy plating bath containing at least one aggregation promoting agent of stannic oxide particles. 2. A tin and tin alloy plating bath, which further contains a surfactant in addition to the plating bath of claim 1. 3. A tin and tin alloy plating bath, which further contains a brightening agent in addition to the plating bath according to claim 1 or 2. 4. A tin and tin alloy plating bath, which further contains a semi-brightening agent in addition to the plating bath according to any one of claims 1 to 3. 5. (A) stannous salt, stannous salt and lead,
A soluble metal salt consisting of a mixture of salts of metals selected from silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony, and (B) alkanesulfonic acid, alkanolsulfonic acid, aliphatic In a tin and tin alloy plating bath containing an organic acid such as carboxylic acid or an acid selected from inorganic acids such as hydrochloric acid, sulfuric acid and borofluoric acid and at least one salt thereof, the above-mentioned soluble metal salt (A ) And acid (B), the following (1) to (2)
Compounds shown, catechol sulfonic acid, hydroquinone sulphate
Fonic acid, naphthol sulfonic acid, catechol, hydroxy
Non, resorcin, pyrogallol, phloroglucin, fu
Enolsulfonic acid, cresolsulfonic acid, ascor
Antioxidant selected from the group consisting of binic acid or salts thereof.
The inhibitor (C) and the aggregation accelerator (D) of claim 1 are added together, and (In the formula (1), R is SO ₃ X (X is hydrogen, a metal such as sodium, potassium and calcium, NH ₄ etc.), COOY (Y is a metal such as hydrogen, sodium, potassium and calcium, N
H _4, etc.), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ , halogen; n is an integer of 1 to 4; m is an integer of 1 to 2, provided that when m = 2, R
Are mutually the same or different substituents; n = 1, m = 1
In the case of, R excludes SO ₃ H; in the case of n = 1 and m = 2,
R excludes combinations of SO ₃ H and CH ₃ ; n = 2, m =
In the case of 1, R excludes SO ₃ X. ) [Chemical 2] (In the formula (2), R is SO ₃ X (X is a metal such as hydrogen, sodium, potassium and calcium, NH _{4 and the} like), COOY (Y is a metal such as hydrogen, sodium, potassium and calcium, N
H _4, etc.), CH ₃ , OCH ₃ , CH ₂ OH, CH ₂ CH ₂ O
H, NH ₂ , halogen; n is an integer of 1 to 4; m is an integer of 1 to 2, provided that when m = 2, R
May be the same or different substituents; n, m
= 1, R excludes SO ₃ H. ) By intermittently repeating the filtration treatment in the coexistence of the antioxidant and the coagulation promoter to capture and remove the stannic oxide particles outside the bath, the turbidity of the plating bath is prevented and the transparency is improved with time. A method for controlling tin and tin alloy plating baths, which is characterized by making it stable. 6. (A) stannous salt, stannous salt and lead,
A soluble metal salt consisting of a mixture of salts of metals selected from silver, zinc, bismuth, indium, nickel, cobalt, copper, gold and antimony, and (B) alkanesulfonic acid, alkanolsulfonic acid, aliphatic It contains an organic acid such as carboxylic acid or at least one acid selected from inorganic acids such as hydrochloric acid, sulfuric acid and borofluoric acid, or further contains a surfactant, a brightening agent or a semi-brightening agent. A tin and tin alloy plating bath containing at least one of the antioxidant according to claim 5 and the aggregation accelerator according to claim 1,
A tin and tin compound characterized by being mixed in advance with at least one of an acid, a soluble metal salt, a surfactant, a brightening agent, or a semi-brightening agent, and mixing the mixture with the remaining bath constituents at the time of building a bath. How to prepare a gold plating bath.