JPH1121692A - Plating method and plated products - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel tin-silver alloy electroplating method. SOLUTION: Electroplating is conducted by the use of the tin-silver alloy electroplating bath with bivalent and/or quadrivalent tin ions, univalent silver ion and tin and silver complexing agent as the essential components. In this case, the catholyte (plating soln.) and anolyte are separated by the diaphragm or partition permeable to the solns. and/or the component ions, and plating is performed by using an aq. soln. contg. at least bivalent and/or quadrivalent tin ions, an acid in the amt. sufficient to keep the ions soluble, an alkali and/or a complexing agent as the anolyte. Since the anolyte and catholyte (plating bath) are separated by the diaphragm or partition, the impurities generated in the anode are not diffused in the plating soln. but trapped, hence the plating bath is not deteriorated, and the operation is continued for a long period while balancing the bath components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment technique, and more particularly to an electroplating method and a plated product for forming a tin-silver alloy film having good solderability to a tin-silver brazing material.

[0002]

2. Description of the Related Art In the electronics industry, joining with a solder (brazing material) having a basic composition of tin-lead is widely performed as an indispensable technique. In order to perform soldering quickly and reliably, a component with good solderability is preliminarily applied to the component to be soldered, and a tin-lead alloy plating film is generally used as this solderable film. It's being used.

[0003] In recent years, however, there has been a concern about the effects of lead on health and the environment, and the idea of regulating tin-lead solder containing harmful lead is rapidly spreading. Considering industrial production conditions and usage conditions, there is no lead-free solder that has properties that can be substituted for tin-lead solder, and research and development is being conducted mainly in Japan, Europe, and the United States. is there. It is thought that tin is used as the first element as an alternative to tin-lead solder,
As the second element, silver, bismuth, copper, indium, antimony, zinc, and the like are listed as candidates, and binary alloys thereof or multi-element alloys further added with a third element are listed as candidates. Among them, a tin-silver alloy is one of the most promising alternative alloy candidates.

It is necessary to change the plating film for soldering (solderable film) to one containing no lead in accordance with the alternative solder (brazing material). On the contrary,
As a plating bath for obtaining a tin-silver alloy plating film, a plating bath containing silver as a main component has been used for a long time, but there is no satisfactory non-cyan tin-silver alloy plating bath containing tin as a main component. Has not been done.

As a plating bath of silver alone, a cyan bath has been used for a long time. Silver nitrate bath, sulfamic acid bath, silver chloride bath, thiocyanic acid bath, thiosulfate bath, etc. have been studied in place of cyanide bath which is not preferable for pollution prevention. Because of its small size, the crystals of the precipitate were coarse compared to the cyanide bath, and did not have a performance satisfying industrial applications. Recently, a bath in which a precipitate of finer particles than these are obtained is disclosed in JP-A-2-290993, in which a plating bath containing a silver salt of an organic sulfonic acid and potassium iodide and a derivative of a sulfanilic acid are added. A bath using succinimide or a derivative thereof as a complexing agent is described in JP-A-7-166391, but does not describe the possibility of alloy plating with tin.

[0006] The fact that a tin-silver alloy film can be obtained by electroplating has been known for a long time, and a cyan bath has generally been used. For example, cyan - pyrophosphate mixing bath, Matsushita 1971 (metal surface technology 22, 6
0 (1971)), and Kubota et al. In 1983 (Metal Surface Technology 34 , 37 (1983);
6691) to obtain a tin-silver alloy film.

However, since the use of cyan is also not preferable from the viewpoint of environmental hygiene, pollution, and management of poisonous substances, baths other than cyan are also being studied, and in recent years it has become the mainstream. As tin-silver alloy plating baths other than the cyanide bath, recently, potassium stannate-hydantoin bath using tetravalent tin by Ise et al. (Preliminary collection of the 93rd conference of Surface Technology Association, 205 (1996); Preliminary collection of the 94th Lecture Meeting 80 (1996), Preliminary Collection of the 95th Lecture Meeting of the Surface Technology Association 183 (1997)), and as a bath using divalent tin, Arai et al.
Iodide bath (Preliminary collection of the 93rd lecture meeting of Surface Technology Association 1
95 (1996), Preliminary Collection of the 94th Lecture Meeting of the Surface Technology Association 83 (1996)). Arai has also applied a pyrophosphoric acid-iodide bath to a ternary alloy system of tin-silver-copper and reported the results (Preliminary Report of the 94th Conference of Surface Technology Association, 85 ( 1996)).

The inventors of the present invention have conducted intensive studies to obtain a denser, smoother, and more excellent plating property of the solderability, and have found that the addition of various organic compounds can improve the smoothness of the coating. He has applied for a headline and a patent (Japanese Patent Application No. 8-143481). Further, although it is a bath that requires aging over time after the addition of a brightener, a bath capable of bright plating is found, and plating is performed using this bath, so that a solder joint using a tin-silver brazing material is performed. Of electrical and electronic circuit parts suitable for the application
-207683). Subsequently, a gloss bath which does not require aging over time using an amine-aldehyde reaction product has been filed (Japanese Patent Application No. 8-278593).

With such efforts, a bath has been developed which can provide a good plating film within a certain time range from the construction bath. However, since the unipolar potentials of tin and silver are largely separated, and both metals are in an aqueous solution. Because the stability in the bath is not good, the problem of industrial operation, that is, deterioration of the bath with time, has not been solved in any of the plating baths.

[0010]

Against this background, there is a need for a technique for continuously operating a tin-silver alloy plating bath under industrially satisfactory conditions. The purpose was.

[0011]

The present inventors have conducted intensive studies to enable the industrial operation of a tin-silver-based alloy plating bath, and found that most of the causes of the aging of the above-described bath are due to the anode surface. In addition, it was found that various reactions occurred in the vicinity of the anode, and the above-mentioned problems were solved by isolating the anode and the cathode, thereby enabling continuous industrial operation under proper conditions.

That is, in a tin-silver alloy plating bath,
The unipolar potentials of tin and silver are greatly separated, silver ions are easily reduced and precipitated as metallic silver, and divalent tin is easily oxidized to tetravalent tin. Also, in a tetravalent tin bath,
The anode partially dissolves as divalent and is one cause of the deterioration of the bath.

[0013] The problem of bath stability in the tin-silver alloy plating bath is that the plating bath not only keeps both tin and silver in a soluble state, but also makes the deposition potential as close as possible. Due to the restriction that such a complexing agent must be selected, there is a situation that it is necessary to use a complexing agent having a problem with stability, and there is also a problem that there is deterioration of the bath due to decomposition of the complexing agent. included.

As an example of the cause of deterioration clarified by the present inventors, for example, in a bath using potassium iodide as a complexing agent, I ⁻ is oxidized to I ₂ at the anode and reacted with Sn ^{2+ in} the bath. elucidates that Sn ⁴⁺ generated when returning to ^- again I was. It has also been confirmed that in a bath using carboxylic acids or amino acids, they are decomposed. On the other hand, all baths developed in recent years have the problem of deterioration with time, but the mechanism of such bath deterioration has not been fully elucidated in each bath. However, the present inventors have determined that various reactions in the anode and in the vicinity of the anode are greatly involved in the deterioration.

Based on the understanding of such deterioration, the inventors of the present invention have separated the anolyte and the catholyte (plating bath) by a diaphragm or a partition and electrolyzed.
By adopting a method in which impurities generated at the anode and adversely affecting them are trapped without diffusing into the plating solution, deterioration of the plating bath is suppressed, or the balance of bath components is maintained. The present invention that enables long-term operation has been completed.

That is, the present invention provides electroplating from a tin-silver alloy electroplating bath containing divalent and / or tetravalent tin ions, monovalent silver ions, and a complexing agent of tin and silver as essential components. In doing so, the catholyte (plating solution) and the anolyte are separated by a diaphragm or partition capable of moving the solution and / or component ions, and the divalent and / or tetravalent tin ions and their anolyte are used as the anolyte. A method for electroplating a tin-silver alloy, comprising plating using an aqueous solution containing at least an acid, an alkali and / or a complexing agent in an amount sufficient to keep ions in a soluble state.

[0017]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a tin-silver alloy electroplating bath containing a divalent and / or tetravalent tin compound, a monovalent silver compound and a complexing agent of tin and silver as essential components. As shown in FIG. 1, a conceptual diagram of the electroplating of a cathode solution (plating solution) (5) into which a plating object (4) is immersed
And an anolyte (3) in which the anode (2) is immersed, and a membrane or partition (1) capable of moving solution and / or component ions.
And plating is performed. The manner of disposing the anode chamber may be appropriately selected according to the type of the object to be plated. For example, the anode chamber may be disposed on both sides of the plating tank (7) as shown in FIG. As shown in (1), it may be arranged on one side of the plating tank (7). Furthermore, depending on the shape of the plating object, it can be arranged at the bottom of the plating tank.

[0018] In the method of the present invention, as the diaphragm,
It is possible to use an ordinary filter cloth, but by using an ion-exchange membrane, it is possible to prevent components that adversely affect the plating generated on the anode surface or near the anode from moving from the anode chamber to the plating solution. At the same time, a method in which only tin and / or silver ions are supplied to the cathode chamber can be adopted. When an ion exchange membrane is used, a cation exchange membrane is used. The type of the exchange membrane is not particularly limited, and may be a commercially available product. For example, Neosepta CL-25T, CM-1, CM-2, CMS, CMH,
C66-10F (Tokuyama Soda Co., Ltd.), CR61A
ZL-386, CR61AZL-389 (Yuasa Ionics Co., Ltd.), Aciplex S-1002, S
-1004, S-1104, S-1112 (above, Asahi Kasei Corporation) and the like are used.

The catholyte (plating solution) used in the method of the present invention will be described in detail later. As the anolyte, at least divalent and / or tetravalent tin ions and those ions in a soluble state can be used. A sufficient amount of acid to hold,
An aqueous solution containing an alkali and / or a complexing agent is used. That is, since tin ions are supplied to the cathode chamber through the diaphragm, conditions are selected for the anolyte such that tin and / or silver can be present in the solution as ions. In particular, when an ion exchange membrane is used, there is an advantage that an anolyte having a considerably different composition from the plating solution can be used as the anolyte, and it is necessary to control the composition more strictly than the plating solution in the cathode chamber. Since it is not available, its composition can be selected relatively easily. That is, the same solution as the catholyte may be used, but a simple solution such as an acidic solution of tin may be used.

As described above, when tin is supplied from the anode using a tin anode, an acidic solution containing a free acid is preferably used. However, when an insoluble anode is selected, tin is supplied to the anode chamber. By replenishing the compound or a solution containing the same, tin ions will be supplied to the cathode chamber. In such a case, the above-mentioned tin and silver compounds or the above-described complexing agent are used. The solution solubilized in is preferably used.

That is, replenishment of tin and / or silver to the anolyte may be carried out by dissolving the anodic electrode, or by adding a compound (or a solution thereof) to the plating solution or anolyte. Can also. As the anode, tin, a tin-silver alloy, silver, or an insoluble anode may be used depending on the composition of the plating solution. In general, tin or an insoluble anode is used.

Regarding the replenishment by adding the compound (or its solution), the silver concentration in the plating bath is generally considerably lower than the tin concentration, and thus the replenishment of silver ions is carried out via the anode chamber. Although it may be carried out, it is often safe to supply directly to the cathode chamber.

Further, the anolyte may be prepared by suspending an adsorbent for adsorbing the generated impurities in the anolyte, forming the adsorbent in a fluidized bed, or continuously or intermittently supplying the anolyte. Then, a method can be adopted in which the generated impurities are immediately adsorbed and removed from the anolyte to prevent diffusion into the catholyte.

As the adsorbent, any generally used adsorbent can be used as long as it adsorbs the generated impurities. For example, adsorbents such as activated carbon, charcoal, activated clay, and zeolite are preferably used.

When it is difficult to separate the anode and cathode by a diaphragm or a partition wall due to a limitation of a bath space, an anode bag can be used as a substitute for the diaphragm. However, in this case, since the amount of the anolyte is extremely small relative to the amount of the catholyte (plating solution), the concentration of a substance that causes deterioration tends to be high. It is necessary to use a material in which the adsorbent is suspended as described above or the adsorbent is fixed to the anode bag itself, so that a substance causing a deterioration factor does not leak out of the anode bag.

Furthermore, since the anode and cathode bipolar chambers are separated by a diaphragm or a partition wall, this is an obstacle, and all the tin ions dissolved at the anode do not move to the cathode chamber, and the metal concentration in the cathode chamber gradually increases. May drop. In such a case, as shown in FIG. 2 as a conceptual diagram of an example of the method, an auxiliary tank (8) is provided in addition to the plating tank (7), and the auxiliary tank is provided in the same manner as the plating tank (7). In addition, the cathode and anode compartments can be separated by a diaphragm or a partition (1) so that a substance causing a deterioration factor is not diffused into the cathode compartment, and tin ions and / or silver ions can be supplied. At this time, the anode (2) and the dummy cathode (6) may be arranged in the auxiliary tank as shown in FIG. 2 and a DC voltage may be applied in the same manner as in the main plating tank. Since the driving force for the movement of the ions is due to the effects of electrophoresis and osmotic pressure,
Normally, it is not necessary to pass a large current comparable to plating.

The plating bath used in the plating method of the present invention contains, as essential components, divalent and / or tetravalent tin ions, monovalent silver ions, and a complexing agent of tin and silver. Sources of divalent or tetravalent tin, one of the essential components, include sulfate, halide, borofluoride, silicofluoride, sulfamate, pyrophosphate, acetate, sodium stannate, and stannic acid. Potassium or the following general formula (A)
In addition to tin salts generally used, such as tin salts of sulfonic acids represented by (E), tin hydroxide or tin oxide is used, for example, polyvalent carboxylic acid, oxycarboxylic acid, mercaptocarboxylic acid,
General formulas (1) to (1) listed as complexing agents such as sulfocarboxylic acid added to the plating bath used in the present invention.
One or two selected from solubilized tin complexes formed by a complexing agent selected from the compounds represented by 3)
More than one kind can be used alone or in appropriate mixture.

General formula (A) R-SO ₃ H (A) wherein R is a C ₁ -C ₁₂ alkyl group or C ₂ -C ₃
And the hydrogen of R may be substituted with a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, a carboxyl group or a sulfonic acid group in the range of 0 to 3; May be in the position. ] The salt of the aliphatic sulfonic acid represented by these.

General formula (B)

Embedded image [Where R represents a C ₁ -C ₃ alkyl group. X represents a halogen of chlorine and / or fluorine, and may be at any position of the R, and the number of substitutions n1 of the halogen substituted with the hydrogen of the R is from 1 to all hydrogens coordinated to the R. Represents saturated substituents, and the substituted halogen species are one or two types. The hydroxyl group may be at any position of the R, and the number of substitutions n2 of the hydroxyl group substituted with the hydrogen of the R is 0 or 1. Y represents a sulfonic acid group, which may be located at any position of R; and the number of substitutions n3 of the sulfonic acid group represented by Y is in the range of 0 to 2. A halogenated alkanesulfonic acid or a halogenated alkanolsulfonic acid represented by the formula:

General formula (C)

Embedded image [Where X represents a hydroxyl group, an alkyl group, an aryl group, an alkylaryl group, an aldehyde group, a carboxyl group, a nitro group, a mercapto group, a sulfonic acid group or an amino group, or two X's together with a benzene ring To form a naphthalene ring, and the number of substitutions n of the group is in the range of 0 to 3. ] The aromatic sulfonic acid represented by these.

General formula (D) HO ₃ S—R—COOH (D) wherein R is a C ₁ -C ₆ alkylene group or C ₂ -C
Represents ₆ alkenylene groups, wherein the hydrogen of R may be substituted with a hydroxyl group or a carboxyl group. ] The aliphatic sulfo (hydroxy) carboxylic acid represented by these.

General formula (E)

Embedded image [Where X represents hydrogen, a hydroxyl group or a carboxyl group. The sulfonic acid group, carboxyl group and X may be at any position. ] The aromatic sulfo (hydroxy) carboxylic acid represented by these.

Preferred examples of the sulfonic acids represented by the general formulas (A) to (E) include methanesulfonic acid, methanedisulfonic acid, methanetrisulfonic acid, trifluoromethanesulfonic acid, and ethanesulfonic acid. Acid, propanesulfonic acid, 2-propanesulfonic acid, butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid,
-Hydroxyethane-1-sulfonic acid, 2-hydroxypropane-1-sulfonic acid, 2-hydroxybutanesulfonic acid, 2-hydroxypentanesulfonic acid, 1-carboxyethanesulfonic acid, 1,3-propanedisulfonic acid, arylsulfonic acid , 2-sulfoacetic acid, 2- or 3
-Sulfopropionic acid, sulfosuccinic acid, sulfomethylsuccinic acid, sulfomaleic acid, sulfofumaric acid, benzenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, nitrobenzenesulfonic acid, benzaldehydesulfonic acid, phenolsulfonic acid, phenol-2,4-
Disulfonic acid, 2-sulfobenzoic acid, 3-sulfobenzoic acid, 5-sulfosalicylic acid, 4-sulfophthalic acid, 5
-Sulfoisophthalic acid and 2-sulfoterephthalic acid.

The concentration of tin in the plating bath is desirably increased or decreased depending on the type of bath to be used and the object to be plated. However, a tin content of about 1 to 150 g / l is appropriate, and preferably about 5 to 80 g / l. And

The concentration of the metal in the plating bath is desirably increased or decreased depending on the type of bath to be used and the object to be plated. However, the tin content is generally about 1 to 80 g / l, preferably about 5 to 30 g / l. And

As a source of non-cyanide monovalent silver which is an essential component of the bath used in the plating method of the present invention, for example, nitrates, nitrites, sulfates, thiosulfates, thiocyanates, sulfites , Bisulfite, metabisulfite, chloride, chlorate, perchlorate, bromide, bromate, iodide, iodate, borofluoride, silicofluoride, benzoate, sulfamate, citrate Acid salt, lactate, phosphate, trifluoroacetate, pyrophosphate, 1-hydroxyethane-1,1-bisphosphonate, or sulfonic acid represented by the above general formulas (A) to (E) In addition to silver salts generally used widely such as silver salts, silver hydroxide or silver oxide is selected from a complexing agent such as iodine and mercaptocarboxylic acids or a silver complex complexed with ammonia and solubilized, or 2 or more It can be used alone or in appropriate combination.

The preferred sulfonic acids (A) to (E) constituting the silver salt are the same as those described for the tin compound in the preceding section.

The amount of the silver compound used is desirably increased or decreased depending on the type of bath used or the object to be plated, but it is appropriate that the silver content is about 0.05 to 10 g / l, preferably 0.1 to 5 g / l. / L. However, when obtaining a tin-silver alloy plating film having a high silver content,
The silver concentration is not limited to this, and can be about 50 g / l.

As a complexing agent for tin and / or silver, which is an essential component of the plating bath used in the plating method of the present invention, (1) condensed phosphoric acid (pyrophosphoric acid, triphosphoric acid, etc.)
Or salts thereof, (2) iodine, bromine, iodic acid,
Bromic acid, sulfurous acid, bisulfite, metabisulfite, thiosulfate,
Acids or salts that generate thiocyanic acid, acetic acid, and ammonium ions, and one or two or more selected from complexing agents represented by the following (3) to (13), alone or appropriately. Can be mixed and used.

(3) General formula X—R—COOH wherein R represents a single bond or a C ₁ -C ₄ alkylene group, and the hydrogen of R may be in any position within a range of up to half of the number. , -S-CH _3, methyl group, an amino group, may be substituted by a hydroxyl group and (or) a carboxyl group. X represents hydrogen (except when R is a single bond), a carboxyl group, or CH ₂ OH. And the salts thereof.

Of these, particularly preferred are oxalic acid, malonic acid, succinic acid, glycolic acid, lactic acid,
Tartaric acid, citric acid, glycine and the like can be mentioned.

(4) Monosaccharides and partially oxidized polyhydroxycarboxylic acids and cyclic ester compounds thereof.

Of these, particularly preferred ones include ascorbic acid, gluconic acid, δ-gluconolactone and the like.

(5) General formula

Embedded image [Where R represents a C ₁ -C ₅ alkylene group, and the hydrogen of the alkyl may be substituted with an amino group or a carboxyl group, or may be bonded to an acetyl group via the amino group. Good. And mercaptosulfonic acid or a salt thereof.

Among these, particularly preferred are, for example, mercaptosuccinic acid, 3-mercaptopropionic acid, mercaptoacetic acid, 2-mercaptopropionic acid, penicylamine, 3-mercaptopropanesulfonic acid, acetylcysteine, cysteine and the like. No.

(6) General formula HO ₃ S—R—COOH wherein R is a C ₁ -C ₆ alkylene group or C ₂ -C
Represents ₆ alkenylene groups, wherein the hydrogen of R may be substituted with a hydroxyl group or a carboxyl group. ] The aliphatic sulfo (hydroxy) carboxylic acid represented by these, or their salts.

Of these, particularly preferred ones are, for example, 2-sulfoacetic acid, 2-sulfopropionic acid, 3-sulfopropionic acid, sulfosuccinic acid, sulfomethylsuccinic acid, sulfofumaric acid and sulfomaleic acid. Can be

(7) General formula

Embedded image [Where X represents hydrogen, a hydroxyl group or a carboxyl group. The sulfonic acid group, carboxyl group and X may be at any position. ] The aromatic sulfo (hydroxy) carboxylic acid represented by these, or their salts.

Among these, particularly preferred ones are, for example, 2-sulfobenzoic acid, 3-sulfobenzoic acid, 4-sulfobenzoic acid, 4-sulfophthalic acid, 5-sulfoisophthalic acid, 2-sulfoterefic acid. Tar acid, 5-sulfosalicylic acid, and the like.

(8) General formula

Embedded image [Wherein, X is -CH ₂ COOH or -C ₂ H ₄ COO
H represents Y and —CH ₂ COOH or —C ₂ H ₄ COO
H represents —CH ₂ OH, and Z represents —CH ₂ COOH or —C ₂ H ₄ COOH or —CH ₂ OH or hydrogen. A is a single bond, -CH (0H) -, or -CH ₂ -N
(CH ₂ COOH) —CH ₂ —, wherein B represents hydrogen, or when A is a single bond, B may be bonded via a methylene group to form a saturated 6-membered ring. Or a salt thereof.

Of these, particularly preferable ones include ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid iminodiacetic acid, nitrilotriacetic acid and the like.

(9) Hydroxyalkanebisphosphonic acids having 1 to 3 carbon atoms in the alkane or salts thereof.

Among these, particularly preferred ones include 1-hydroxyethane-1,1-bisphosphonic acid.

(10) General formula

Embedded image [Where X ₁ , X ₂ , X ₃ and X ₄ represent carbon or nitrogen, and when each of X _{1 to} X ₄ is nitrogen, R bonded to each X
_{1 ~R 4} does not exist. Not all X are nitrogen at the same time. R ₁ , R ₂ , R ₃ and R ₄ each independently represent hydrogen, a hydroxyl group or a C ₁ -C ₄ alkyl group, wherein the hydrogen of the alkyl group is substituted by a hydroxyl group, a carboxyl group or a halogen. May be. R ₁
May form a benzene ring via R ₂ and a methylene group, and the hydrogen of the benzene ring is substituted by halogen, C ₁ -C ₄ alkyl, C ₁ -C ₄ alkoxy, hydroxyl or carboxyl. May have been. R ₅ is hydrogen,
Alkyl or alkenyl of C ₁ -C ₅ represents a phenyl group, the alkyl group, alkenyl group, and (or)
The hydrogen of the phenyl group may be substituted by a hydroxyl group or an amino group, a monomethylamino group or a dimethylamino group. A pyrrole, a pyrroline, an indole, an isoindole, an imidazole, a benzimidazole, an imidazoline, a triazole, a benzotriazole or a tetrazole.

Among these, particularly preferred are pyrrole, pyrroline, indole, isoindole, imidazole, imidazoline, benzimidazole, 2-ethylimidazole, triazole, benzotriazole, 2- (or 4) methylbenzo. Triazole, 4-hydroxybenzotriazole, 4-carboxybenzotriazole, tetrazole and the like.

(11) General formula

Embedded image _{[Wherein, R 1, R 2, R} 3, R 4 and R ₅ each independently represent an alkyl group or an alkoxy group of hydrogen or C ₁ -C _5. X represents nitrogen or carbon, and when X is nitrogen, R ₄ is not present. ], A succinimide or a maleic imide, and derivatives thereof.

Among these, particularly preferred are hydantoin, 5-n-propylhydantoin,
5,5-dimethylhydantoin, 2,2-dimethylsuccinimide, 2-methyl-2-ethylsuccinimide,
2-methylsuccinimide, 2-ethylsuccinimide, 1,1,2,2-tetramethylsuccinimide,
Examples include 1,1,2-trimethylsuccinimide, 2-butylsuccinimide, 2-ethylmaleimide, 1-methyl-2-ethylmaleimide, 2-butylmaleimide and the like.

(12) General formula

Embedded image [Wherein R ₁ and R ₂ each independently represent hydrogen, an amino group or a C ₁ -C ₅ alkyl group. R ₃ and R ₄ each independently represent hydrogen, a C ₁ -C ₅ alkyl or alkenyl group or a phenyl group, wherein the hydrogen of the alkyl, alkenyl and / or phenyl group is a hydroxyl group or an amino group, a monomethylamino group or It may be substituted with a dimethylamino group, and R ₃ and R ₄ may combine to form a ring. R ₅ represents an alkyl group, an allyl group or a hydroxy group. X represents nitrogen or carbon, and Y represents oxygen or sulfur. At the time of the X Haga nitrogen, R ₅ is not present. Urea, thiourea or thioacetamide and derivatives thereof.

Among these, particularly preferred are, for example, imidazolidinone, 2-imidazolidinthione, thiourea, trimethylthiourea, N, N'-di-n-butylthiourea, tetramethylthiourea, 1-allyl -2-
Thiourea, N, N 'diethylthiourea, 1,3-bis (dimethylaminopropyl) -2-thiourea, N, N dimethylthiourea, N, N-dimethylolurea, thiosemicarbazide, 4-phenyl-3-thiosemicarbazide ,
2-thiobarbituric acid and the like.

(13) General formula

Embedded image [Where Ra, Rb and Rc each independently represent hydrogen, a hydroxyl group or a C ₁ -C ₅ alkyl group, and the hydrogen of the alkyl group may be substituted with a hydroxyl group, an amino group or chlorine. And the alkyl groups may combine with each other to form a ring. And salts thereof.

Of these, particularly preferred are ethylenediamine, ethylamine isopropylamine, n-butylamine, isobutylamine, dipropylamine, dibutylamine, diethylamine, monoethanolamine, diethanolamine, triethanolamine, N-methyl Ethanolamine, 2-amino-2-
(Hydroxymethyl) -1,3-propanediol, 2
-Chloroethylammonium chloride and the like.

The amount of the complexing agent to be used is appropriately selected depending on the kind and combination of the complexing agent. When the complexing agent is added as a main complexing agent, the amount is 1 to 1 mol of the metal in the bath. ~ 2
About 0 mol is appropriate, and preferably about 2 to 15 mol. However, when it is used as an auxiliary complexing agent, the concentration is as low as about 0.001 mol / l in absolute concentration, and is equivalent to the main complexing agent per 1 mol of metal in the bath.
Used in a high concentration range up to about 20 mol.

The tin-silver alloy plating bath used in the method of the present invention may further comprise one or more of a conductive salt, a pH buffer, a surfactant, a smoothing additive, a gloss additive, and an antioxidant. The above can be added and used. It is known that such components are added to tin and tin alloy plating baths, and they can be added to the plating bath used in the plating method of the present invention. these,
Known compounds conventionally used in tin and tin alloy plating baths can be used as the conductive salt, pH buffer, surfactant, leveling additive, gloss additive, and antioxidant.

That is, as the compound preferably used as the conductive salt, sodium, potassium or ammonium salts such as sulfuric acid, hydrochloric acid and sulfonic acid which have been conventionally used in tin and tin alloy plating baths can be used alone or as appropriate. Used in combination. The amount of use is not specifically limited, but generally 5 to 200 g / l, more preferably 10 to 100 g / l is used.

Compounds preferably used as the pH buffer include sodium, potassium or ammonium salts such as phosphoric acid, acetic acid, carbonic acid, boric acid and citric acid which have been conventionally used in tin and tin alloy plating baths. )
These acid salts and the like are used alone or in combination as appropriate. The same salt can be used as both a conductive salt and a pH buffer. The amount of use is not specifically limited, but generally 5 to 200 g / l, more preferably 10 to 100 g / l is used.

Compounds preferably used as surfactants include cationic surfactants and anionic surfactants which have been conventionally used in tin and tin alloy plating baths.
Nonionic surfactant, both amphoteric surfactant,
It is used alone or in combination as appropriate.

Suitable surfactants include cationic surfactants such as tetra-lower alkylammonium halide, alkyltrimethylammonium halide, hydroxyethylalkylimidazoline, polyoxyethylenealkylmethylammonium halide, alkylbenzalkonium halide and dialkyl. Dimethylammonium halide, alkyldimethylbenzylammonium halide, alkylamine hydrochloride, alkylamine acetate,
Alkylamine oleate, alkylaminoethylglycine, alkylpyridinium halides, and the like.

Examples of the anionic surfactant include alkyl (or formalin condensate) -β-naphthalenesulfonic acid (or a salt thereof), fatty acid soap, alkylsulfonic acid salt, α-olefinsulfonic acid salt, alkylbenzenesulfonic acid salt. , Alkyl (or alkoxy) naphthalene sulfonate, alkyl diphenyl ether disulfonate, alkyl ether sulfonate, alkyl sulfate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenol ether sulfate, higher alcohol phosphorus Acid monoester salt, polyoxyalkylene alkyl ether phosphate (salt), polyoxyalkylene alkyl phenyl ether phosphate, polyoxyalkylene phenyl ether phosphate, polyoxyethylene Alkylether acetates,
Alkyloyl sarcosine, alkyloyl sarcosine, alkyloyl methyl alanine salt, alkyl sulfo acetate, acyl methyl taurate, alkyl fatty acid glycerin sulfate, hydrogenated coconut oil fatty acid glyceryl sulfate, alkyl sulfocarboxylate, Alkyl sulfosuccinates, dialkyl sulfosuccinates, alkyl polyoxyethylene sulfosuccinates, sulfosuccinate monooleylamide sodium salt (or ammonium, TEA salt) and the like.

Examples of the nonionic surfactant include polyoxyalkylene alkyl ether (or ester), polyoxyalkylene phenyl (or alkyl phenyl) ether, polyoxyalkylene naphthyl (or alkyl naphthyl) ether, polyoxyalkylene styrenated phenyl. Ether (or an activator in which a polyoxyalkylene chain is further added to the phenyl group), polyoxyalkylene bisphenol ether, polyoxyethylene polyoxypropylene block polymer, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene sorbite fatty acid ester, polyethylene glycol Fatty acid ester, polyoxyalkylene glycerin fatty acid ester, polyoxyalkylene alkylamine, ethylenediamine poly Xylylene alkylene condensate adduct, polyoxyalkylene fatty acid amide, polyoxyalkylene castor (and / or hydrogenated castor oil) oil, polyoxyalkylene alkylphenyl formalin condensate, glycerin (or polyglycerin) fatty acid ester, pentaerythritol fatty acid ester , Sorbitan mono (sesqui,
Tri) fatty acid esters, higher fatty acid mono (di) ethanolamide, alkyl / alkyloamide, oxyethylenealkylamine and the like.

The amphoteric surfactants include 2-alkyl-N-
Carboxymethyl (or ethyl) -N-hydroxyethyl (or methyl) imidazolinium betaine, 2-alkyl-N-carboxymethyl (or ethyl) -N-carboxymethyloxyethyl imidazolinium betaine, dimethylalkyl betaine, N -Alkyl-β-aminopropionic acid (or its sodium salt), alkyl (poly) aminoethylglycine, N-alkyl-N-methyl-β-alanine (or its sodium salt), fatty acid amidopropyldimethylaminoacetic acid betaine and the like. is there.

The use amount of these surfactants is appropriately selected, but is generally used in the range of 0.001 g / l to 50 g / l, and more preferably in the range of 0.01 g / l to 50 g / l. Used.

Compounds which are preferably used as smoothing additives and gloss additives include polyethylene glycol, sulfanilic acids, amine-aldehyde condensates conventionally used in tin and tin alloy or silver and silver alloy plating baths. Are used alone or in combination as appropriate.

The amount used is generally 0.01 to 50 g /
1 and more preferably 0.1 to 30 g / l.

Oxidation of tin ions is not only at or near the anode surface, but is also gradually oxidized during the operation by oxygen in the air to change to tetravalent tin, thereby forming a precipitate or forming a complexing agent. Some are accumulated in the bath in a dissolved state,
All of these have a detrimental effect on plating.
An antioxidant is used to suppress or prevent this.

Antioxidants include hydroquinone, catechol, resorcinol, phloroglucinol, pyrogallol, 3-aminophenol, hydroquinone (or catechol, resorcinol) sulfonic acid (and catechol, resorcinol) conventionally used in tin and tin alloy plating baths. Esters thereof), gallic acid, 3,4-dihydroxybenzoic acid, 4-methylpyrocatechol, pyrophosphoric acid, tartaric acid,
Citric acid, ascorbic acid and the like are used alone or in combination as appropriate.

The amount used is generally 0.005 to 20 g
/ L is used, and more preferably 0.01 to 10 g / l
Is used.

The tin-silver alloy plating bath used in the electroplating method of the present invention can be used to adjust the crystal growth of the alloy film,
In order to lower the melting point, one or more and / or two or more third metals selected from bismuth, copper, antimony, zinc, indium, palladium, arsenic and nickel can be used.

The addition of a third metal to a tin-silver alloy plating bath to lower the melting point of the alloy film is described in Arai's report (Surface Technology Association 94th Annual Conference Preliminary Collection 85 (1)
996)), the plating method of the present invention includes one of the above-mentioned metals and / or 2
It can also be applied to baths containing more than one species.

Electric / electronic circuit components having solder joints to which plating is applied according to the tin-silver alloy plating method of the present invention include, for example, electronic devices such as IC semiconductors and the like.
Examples include passive components such as resistors and capacitors, and joining components such as connectors, switches, and printed wiring boards.
Therefore, another subject of the present invention is these electric / electronic parts plated with a tin-silver alloy by the plating method of the present invention.

[0080]

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. It can be changed arbitrarily.

Comparative Example 1 800 ml of the following bath 1 was used as a plating bath, and plating was performed using tin as an anode without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver almost equivalent to the deposited amount was supplied in the form of a solution. The silver replenisher was a solution complexed with potassium iodide. Bath 1 Sn ²⁺ (as tin chloride (divalent) dihydrate) 0.18 mol / l Ag ⁺ (as silver iodide) 0.02 mol / l potassium pyrophosphate 0.54 mol / l potassium iodide 2.0 mol / l pH 8.9 Temperature 25 ° C Current density 2 A / dm ²

Example 1 The cathode compartment and the anode compartment were separated by separating them with a filter cloth. The bath 1 was used for plating on the negative and positive electrode solutions. Silver was supplied only to the catholyte.

After the current was supplied at 6 A · hr / l, Comparative Example 1 and Example 1 were compared. In Comparative Example 1, silver substitution precipitation was remarkably observed on the tin anode, free iodine was accumulated, and the plating film appearance was deteriorated. On the other hand, in Example 1, very little silver was deposited on the anode, but good plating was obtained.

Comparative Example 2 Using 800 ml of the following bath 2 as a plating bath, tin was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver almost equivalent to the deposited amount was supplied in the form of a solution. The silver replenisher was a solution complexed with gluconic acid and mercaptosuccinic acid. Bath 2 Sn ²⁺ (as tin chloride (divalent) dihydrate) 0.08 mol / l Ag ⁺ (as silver nitrate) 0.37 mol / l gluconic acid (50% aqueous solution) 80 ml / l mercaptosuccinic acid 0.6 mol / l arsenic trioxide 80 mg / l polyethylene glycol 0.1 g / l pH 0.3 temperature 25 ° C current density 2 A / dm ²

Example 2 A cathode compartment and an anode compartment were separated by a cation exchange membrane (CMH manufactured by Tokuyama Soda Co., Ltd.). A 400 ml bath 2 was used in the cathode compartment, and silver nitrate was removed from the bath 2 in the anode compartment. 400 ml of solution
And a tin anode was arranged. Silver was supplied only to the catholyte.

After energizing at 6 A · hr / l, Comparative Example 2 and Example 2 were compared. In Comparative Example 2, silver substitution precipitation was remarkably recognized on the tin anode, and coloring of the solution considered to be due to the altered product of gluconic acid was recognized, and the appearance of the plating film was deteriorated. On the other hand, in Example 2, although very little silver was deposited on the anode, good plating was obtained.

Comparative Example 3 The following bath 3 of 800 ml was used as a plating bath, and plating was performed using tin as an anode without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. It was added as a solution complexed with mercaptosuccinic acid and gluconic acid, supplemented with silver almost equivalent to the amount deposited every 8 hours of energization. Bath 3 Sn ²⁺ (as tin chloride (divalent) dihydrate) 0.08 mol / l Ag ⁺ (as silver nitrate) 0.09 mol / l gluconic acid (50% aqueous solution) 80 ml / l mercaptosuccinic acid 0.3 mol / l pH 0.7 Temperature 25 ° C Current density 1 A / dm ²

Example 3 The cathode compartment and the anode compartment were separated by a cation exchange membrane (CMH manufactured by Tokuyama Soda Co., Ltd.), and a 400 ml bath 3 was used for the cathode and anode compartments. A platinum plated titanium anode was placed. The tin and silver were added to the anolyte at a rate of approximately equal to the amount deposited every 8 hours of energization. Both tin and silver were added as a solution complexed with mercaptosuccinic acid and gluconic acid.

After energizing at 6 A · hr / l, Comparative Example 3 and Example 3 were compared. In Comparative Example 3, coloring of the solution, which is considered to be due to the altered substance of gluconic acid, was observed, and the appearance of the plating film was deteriorated. On the other hand, in Example 3, good plating was obtained.

Comparative Example 4 800 ml of the following bath 4 was used as a plating bath, and plating was performed using tin as an anode without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver almost equivalent to the deposited amount was supplied in the form of a solution. The silver replenisher was a solution complexed with potassium iodide. Bath 4 Sn ²⁺ (as tin methanesulfonate) 0.25 mol / l Ag ⁺ (as silver methanesulfonate) 0.015 mol / l potassium pyrophosphate 0.8 mol / l potassium iodide 1.5 mol / l l Triethanolamine 0.4 mol / l Dimethylalkyl betaine 0.5 g / l Formalin condensate addition-β-naphthalene sodium sulfonate 0.5 g / l Reaction product of o-vanillin and N-methylethanolamine 0 0.0117 mol / l pH 5 temperature 25 ° C. current density 2 A / dm ²

Example 4 The cathode compartment and the anode compartment were separated by a filter cloth, and 400 ml of the cathode compartment was placed in the cathode compartment.
Bath 4 was used, and 400 g of a solution obtained by removing silver nitrate from (Bath 4) was used, and 10 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the anode chamber, and a tin anode was placed. Silver which was almost equivalent to the amount of deposition was supplied to the catholyte every 8 hours of energization. The supply liquid of silver was a solution complexed with potassium iodide.

After energizing at 8 A · hr / l, Comparative Example 4 and Example 4 were compared. In Comparative Example 4, silver substitution precipitation was remarkably recognized on the tin anode, free iodine was accumulated, and the plating film appearance was deteriorated. On the other hand, in Example 4, such a phenomenon was not observed, and good plating was obtained.

Comparative Example 5 800 ml of the following bath 5 was used as a plating bath, tin was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver almost equivalent to the deposited amount was supplied in the form of a solution. The silver replenisher was a solution complexed with potassium iodide. Bath 5 Sn ²⁺ (as tin methanesulfonate) 0.25 mol / l Ag ⁺ (as silver methanesulfonate) 0.012 mol / l sodium gluconate 0.8 mol / l potassium iodide 1.5 mol / l l glycine 0.6 mol / l EDTA.4Na 0.004 mol / l 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine 20 g / l ascorbic acid 1 g / l pH 10 temperature 25 ° C. current density 2 A / dm ²

Example 5 Using an 800 ml bath 5, a tin anode was wrapped in an anode bag, and 20 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was charged into the anode bag and plated.

After the current was supplied at 8 A · hr / l, Comparative Example 5 and Example 5 were compared. In Comparative Example 5, silver substitution precipitation was remarkably observed on the tin anode, coloring of the solution and accumulation of free iodine, which are considered to be due to altered gluconic acid, were observed, and the plating film appearance was deteriorated. On the other hand, in Example 5, such a phenomenon was not observed, and good plating was obtained.

Example 6 A cathode compartment and an anode compartment were separated by a cation exchange membrane (CMH manufactured by Tokuyama Soda Co., Ltd.). A 400 ml bath 5 was used for the catholyte, and methanesulfonic acid 1 mol / mol
l, solution of tin methanesulfonate 0.1 mol / l 400
ml and a tin anode was placed. Only catholyte was replenished with silver.

After the current was supplied at 8 A · hr / l, Comparative Example 5 and Example 6 were compared. In Example 5, good plating was obtained.

Comparative Example 6 Using 800 ml of the following bath 6 as a plating bath, tin was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver almost equivalent to the deposited amount was supplied in the form of a solution. The silver replenisher was a solution complexed with acetylcysteine. Bath 6 Sn ²⁺ (as tin methanesulfonate) 0.25 mol / l Ag ⁺ (as silver methanesulfonate) 0.015 mol / l potassium pyrophosphate 0.8 mol / l acetylcysteine 0.045 mol / l tri Ethanolamine 0.4 mol / l EDTA-4Na 0.01 mol / l Sodium acetate 0.48 mol / l Polyoxyethylene alkylamine 0.4 g / l Methanesulfonic acid pH5 Temperature 30 ° C Current density 2 A / dm ²

Comparative Example 7 An experiment was performed under the same conditions as in Comparative Example 6, except that the tin anode was replaced with a platinum-plated titanium anode.

Example 7 The cathode compartment and the anode compartment were separated by a filter cloth, and 400 ml of the cathode compartment was placed in the cathode compartment.
The bath 6 was used, and 400 ml of a solution obtained by removing silver nitrate from the bath 6 was used in the anode chamber, and granular activated carbon (Kanto Chemical Co., Ltd.) was used so that the tin anode placed on the bottom of the anode chamber was completely covered.
Was added and a plating was performed. It was added as a solution complexed with acetylcysteine, supplemented with silver almost equal to the amount deposited every 8 hours.

After energizing at 8 A · hr / l, Comparative Example 6, Comparative Example 7, and Example 7 were compared. In Comparative Example 6, silver substitution precipitation was remarkably recognized on the tin anode, and although the cause was unknown, the bath was considered to be deteriorated due to the generated impurities, and the plating film appearance was deteriorated. In Comparative Example 7,
Tetravalent tin ions accumulated in the bath, and the appearance of the plating film deteriorated. On the other hand, in Example 7, such a phenomenon was not observed, and good plating was obtained.

Comparative Example 8 800 ml of the following bath 7 was used as a plating bath, tin was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver almost equivalent to the deposited amount was supplied in the form of a solution. The silver replenisher was a solution complexed with sodium potassium tartrate and imidazole. Bath 7 Sn ²⁺ (as tin sulfate) 0.20 mol / l Ag ⁺ (as silver acetate) 0.008 mol / l sodium potassium tartrate 0.8 mol / l imidazole 0.02 mol / l pH 8 temperature 30 ℃ Current density 2 A / dm ²

Example 8 The cathode compartment and the anode compartment were separated by a filter cloth, and 400 ml of the cathode compartment was placed in the cathode compartment.
The bath 7 was used, and 400 ml of a solution obtained by removing silver acetate from the bath 7 was used in the anode chamber, and the anolyte was continuously filtered with activated carbon for plating. It was added as a solution complexed with sodium potassium tartrate and imidazole, supplemented with silver approximately equivalent to the amount deposited every 8 hours of energization.

After energizing at 8 A · hr / l, Comparative Example 8 and Example 8 were compared. In Comparative Example 8, silver substitution precipitation was remarkably observed on the tin anode, and although the cause was unknown, bath deterioration occurred, and the plating film appearance deteriorated. on the other hand,
In Example 8, such a phenomenon was not observed, and good plating was obtained.

Comparative Example 9 800 ml of the following bath 8 was used as a plating bath, and tin was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver and copper, almost equal to the amount of deposition, were replenished in the form of a solution. The silver replenisher was a solution complexed with potassium iodide. The copper replenisher was a copper pyrophosphate solution. Bath 8 Sn ²⁺ (as tin chloride (divalent) dihydrate) 0.18 mol / l Ag ⁺ (as silver iodide) 0.02 mol / l Cu ²⁺ (as copper pyrophosphate) 0.18 mol / l potassium pyrophosphate 0.54 mol / l potassium iodide 2.0 mol / l pH 9 mol / l temperature 25 ° C. current density 1 A / dm ²

Example 9 The cathode compartment and the anode compartment were separated by a filter cloth. Plating was performed using bath 8 for the catholyte. A solution obtained by removing silver and copper from the bath 8 was used as the anolyte, and silver and copper, which were almost equivalent to the deposition amount, were supplied to the catholyte every 8 hours of energization. Copper was a copper pyrophosphate solution, and silver was iodine. It was added as a solution complexed with potassium chloride.

After energizing at 6 A · hr / l, Comparative Example 9 and Example 9 were compared. In Comparative Example 9, silver substitution precipitation was remarkably observed on the tin anode, and the appearance of the plating film was deteriorated. It is thought to be due to free iodine. On the other hand, in Example 9, such a phenomenon was not observed, and good plating was obtained.

Comparative Example 10 The following bath 9 of 800 ml was used as a plating bath, and plating was performed using tin as an anode without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver almost equivalent to the deposited amount was supplied in the form of a solution. The silver replenisher was a solution complexed with potassium iodide. Bath 9 Sn ²⁺ (as tin methanesulfonate) 0.25 mol / l Ag ⁺ (as silver methanesulfonate) 0.012 mol / l sodium gluconate 0.8 mol / l potassium iodide 1.5 mol / l 1 glycine 0.6 mol / l EDTA.4Na 0.004 mol / l 2-alkyl-N-carboxymethyl-N-hydroxyethyl imidazolinium betaine 20 g / l ascorbic acid 1 g / l pH 10 temperature 30 ° C. current density 2 A / dm ²

Example 10 The cathode compartment and the anode compartment were separated by a filter cloth. Bath 9 was used for the anion and ambipolar solutions. An auxiliary tank was provided, and the auxiliary tank was separated by separating the cathode chamber and the anode chamber with a filter cloth. The catholyte in the main tank and the auxiliary tank was continuously moved by a pump. Activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the anode chamber of both the main tank and the auxiliary tank. Use a copper wire for the cathode of the auxiliary tank and tin for the anode, and use 2V
Voltage was applied.

After energizing at 20 A · hr / l, Comparative Example 10 and Example 10 were compared. In Comparative Example 10, silver substitution precipitation was remarkably observed on the tin anode, and the appearance of the plating film was deteriorated. On the other hand, in Example 10, such a phenomenon was not observed, and good plating was obtained.

Comparative Example 11 The following bath 10 of 800 ml was used as a plating bath, and a platinum-plated titanium plate was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Every 8 hours of current supply, silver almost equivalent to the deposited amount was supplied in the form of a solution. The silver replenisher was a solution complexed with dimethylhydantoin. Bath 10 Sn ⁴⁺ (as potassium stannate trihydrate) 0.25 mol / l Ag ⁺ (as silver nitrate) 0.0001 mol / l 5,5-dimethylhydantoin 1 mol / l potassium dihydrogen phosphate 10 g / L Potassium hydroxide pH 10.5 Temperature 30 ° C Current density 1 A / dm ²

Example 11 The cathode chamber and the anode chamber were separated by a cation exchange membrane (CMH manufactured by Tokuyama Soda Co., Ltd.). 400 ml of bath 10 was used for the catholyte, and 400 ml of a solution obtained by removing silver nitrate from bath 10 was used for the anode compartment, and a platinum-plated titanium anode was arranged. Silver was supplied only to the catholyte.

Comparative Example 11 and Example 11 were compared after applying 6 A · hr / l. In Comparative Example 11, silver substitutional precipitation was recognized on the tin anode, and the bath was considered to be degraded due to hydantoin degradation, and the plating film appearance was degraded. On the other hand, in Example 11, good plating was obtained.

Comparative Example 12 800 ml of the following bath 11 was used as a plating bath, and a platinum-plated titanium plate was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. At every 8 hours of energization, tin and silver, almost equivalent to the amount of deposition, were replenished in the form of a solution. The tin and silver replenisher was a solution complexed with gluconic acid and mercaptosuccinic acid. Bath 11 Sn ⁴⁺ (as tin chloride (tetravalent) pentahydrate) 0.08 mol / l Ag ⁺ (as silver nitrate) 0.09 mol / l potassium gluconate 0.26 mol / l mercaptosuccinic acid 0 0.3 mol / l pH 1 temperature 30 ° C. current density 2 A / dm ²

Example 12 The cathode compartment and the anode compartment were separated by a cation exchange membrane (CMH manufactured by Tokuyama Soda Co., Ltd.). 400m each for Yin and Yang bipolar fluid
1 bath 11 and a platinum-plated titanium anode was placed.

After energizing at 6 A · hr / l, Comparative Example 12 and Example 12 were compared. In Comparative Example 12, the bath was colored and deteriorated, which was considered to be the decomposition of gluconic acid and mercaptosuccinic acid, and the appearance of the plating film was deteriorated.
On the other hand, in Example 12, good plating was obtained.

Comparative Example 13 800 ml of the following bath 12 was used as a plating bath, and a platinum-plated titanium plate was used for the anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. At every 8 hours of energization, tin and silver, almost equivalent to the amount of deposition, were replenished in the form of a solution. The tin and silver replenisher was a solution complexed with gluconic acid and mercaptosuccinic acid. Bath 12 Sn ⁴⁺ (as tin chloride (tetravalent) pentahydrate) 0.08 mol / l Ag ⁺ (as silver nitrate) 0.37 mol / l potassium gluconate 0.26 mol / l mercaptosuccinic acid 0 0.3 mol / l pH 1.9 Temperature 60 ° C. Current density 2 A / dm ²

Example 13 Using an 800 ml bath 12, a platinum-plated titanium anode was wrapped in an anode bag, and 20 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was charged into the anode bag. Plated with replenishment of tin and silver.

After energizing at 8 A · hr / l, Comparative Example 13 and Example 13 were compared. In Comparative Example 13, the bath was colored and deteriorated, which was considered to be decomposition of gluconic acid and mercaptosuccinic acid, and the plating film appearance was deteriorated.
On the other hand, in Example 13, such a phenomenon was not observed, and good plating was obtained.

Comparative Example 14 800 ml of the following bath 13 was used as a plating bath, and a platinum-plated titanium plate was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Tin which is almost equal to the amount of deposition every 8 hours of energization,
Silver and arsenic were replenished in the form of a solution. Each replenisher was a solution complexed with gluconic acid and mercaptosuccinic acid. Bath 13 Sn ⁴⁺ (as tin chloride (tetravalent) pentahydrate) 0.08 mol / l Ag ⁺ (as silver nitrate) 0.37 mol / l potassium citrate 0.1 mol / l mercaptosuccinic acid 0 2.6 mol / l arsenic trioxide 240 mg / l pH 3.2 temperature 60 ° C current density 2 A / dm ²

Example 14 The cathode chamber and the anode chamber were separated by a cation exchange membrane (CMH manufactured by Tokuyama Soda Co., Ltd.). 400m each for Yin and Yang bipolar fluid
1 bath 13 and a platinum-plated titanium anode was placed.
20 g of activated carbon was added to the anolyte.

After energizing at 8 A · hr / l, Comparative Example 14 and Example 14 were compared. In Comparative Example 14, the bath was colored and deteriorated, which might be caused by decomposition of gluconic acid and mercaptosuccinic acid, and the plating film appearance was deteriorated.
On the other hand, in Example 14, good plating was obtained.

Comparative Example 15 800 ml of the following bath 14 was used as a plating bath, and a platinum-plated titanium plate was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Tin which is almost equal to the amount of deposition every 8 hours of energization,
Silver and arsenic were replenished in the form of a solution. Each replenisher was a solution complexed with gluconic acid and mercaptosuccinic acid. Bath 14 Sn ⁴⁺ (as potassium stannate) 0.08 mol / l Ag ⁺ (as silver nitrate) 0.37 mol / l gluconic acid (50% aqueous solution) 40 ml / l potassium citrate 0.1 mol / l Mercaptosuccinic acid 0.6 mol / l Arsenic trioxide 240 mg / l pH 3.2 Temperature 60 ° C Current density 2 A / dm ²

Example 15 The cathode compartment and the anode compartment were separated by a filter cloth. A 400-ml bath 14 was used for each of the negative and positive electrode solutions, and a platinum-plated titanium anode was arranged. 20 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the anolyte.

After energizing at 8 A · hr / l, Comparative Example 15 and Example 15 were compared. In Comparative Example 15, the bath was colored and deteriorated, which was considered to be the decomposition of gluconic acid and mercaptosuccinic acid, and the plating film appearance was deteriorated. On the other hand, in Example 15, good plating was obtained.

Comparative Example 16 The following bath 15 of 800 ml was used as a plating bath, and a platinum-plated titanium plate was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Tin which is almost equal to the amount of deposition every 8 hours of energization,
Silver and palladium were supplied in the form of a solution. Each replenisher was a solution complexed with gluconic acid and mercaptosuccinic acid. Bath 15 Sn ⁴⁺ (as potassium stannate) 0.25 mol / l Ag ⁺ (as silver nitrate) 0.37 mol / l palladium diamine dinitrate 200 mg / l potassium gluconate 0.26 mol / l mercaptosuccinic acid 0.1 mol / l ammonium nitrate 60 g / l boric acid 10 g / l pH 10.3 temperature 45 ° C. current density 2 A / dm ²

Example 16 The cathode compartment and the anode compartment were separated with a filter cloth. A 400-ml bath 15 was used for each of the negative and positive electrode solutions, and a platinum-plated titanium anode was arranged. 20 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the anolyte.

Comparative Example 16 and Example 16 were compared after applying 8 A · hr / l. In Comparative Example 16, the bath was colored and deteriorated, which might be caused by the decomposition of gluconic acid and mercaptosuccinic acid, and the plating film appearance was deteriorated. On the other hand, in Example 16, good plating was obtained.

Comparative Example 17 The following bath 16 of 800 ml was used as a plating bath, and a platinum-plated titanium plate was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Tin which is almost equal to the amount of deposition every 8 hours of energization,
Silver, arsenic and nickel were replenished in the form of a solution. Each replenisher was a solution complexed with gluconic acid and mercaptosuccinic acid. Bath 16 Sn ⁴⁺ (as tin chloride (tetravalent) pentahydrate) 0.08 mol / l Ag ⁺ (as silver diamine dinitrate) 0.37 mol / l arsenic trioxide 100 mg / l Ni ²⁺ (Added as nickel chloride) 1 g / l gluconic acid (50% aqueous solution) 80 ml / l 2-mercaptopropionic acid 0.5 mol / l pH 4.0 temperature 40 ° C current density 2 A / dm ²

Example 17 The cathode chamber and the anode chamber were separated by a filter cloth. A 400-ml bath 16 was used for each of the negative and positive electrode solutions, and a platinum-plated titanium anode was arranged. 20 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the anolyte.

Comparative Example 17 and Example 17 were compared after applying 8 A · hr / l. In Comparative Example 17, the bath was colored and deteriorated, which might be caused by the decomposition of gluconic acid and mercaptosuccinic acid, and the plating film appearance was deteriorated. On the other hand, in Example 17, good plating was obtained.

Comparative Example 18 800 ml of the following bath 17 was used as a plating bath, and a platinum-plated titanium plate was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Tin which is almost equal to the amount of deposition every 8 hours of energization,
Silver and arsenic were replenished in the form of a solution. Each replenisher was a solution complexed with mercaptopropionic acid. Bath 17 Ag ⁺ (as silver nitrate) 0.37 mol / l Sn ⁴⁺ (as tin chloride (tetravalent) pentahydrate) 0.12 mol / l 3-mercaptopropionic acid 0.65 mol / l trioxide Arsenic 100 mg / l pH 7.8 Temperature 30 ° C Current density 2 A / dm ²

Example 18 The cathode compartment and the anode compartment were separated by a filter cloth. A 400-ml bath 17 was used for each of the negative and positive electrode solutions, and a platinum-plated titanium anode was arranged. 20 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the anolyte.

After energizing at 8 A · hr / l, Comparative Example 18 and Example 18 were compared. In Comparative Example 18, the bath was colored and deteriorated, which was considered to be the decomposition of mercaptopropionic acid, and the plating film appearance was deteriorated. On the other hand, in Example 18, good plating was obtained.

Comparative Example 19 Using 800 ml of the following bath 18 as a plating bath, plating was carried out using a platinum-plated titanium plate as an anode without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Tin which is almost equal to the amount of deposition every 8 hours of energization,
Silver and palladium were supplied in the form of a solution. Each replenisher was a solution complexed with mercaptoacetic acid. Bath 18 Ag ⁺ (as silver nitrate) 0.37 mol / l Sn ⁴⁺ (as tin chloride (tetravalent) pentahydrate) 0.12 mol / l mercaptoacetic acid 0.65 mol / l pH 7.1 Temperature 40 ° C Current density 2 A / dm ²

Example 19 The cathode compartment and the anode compartment were separated by a filter cloth. A 400-ml bath 18 was used for each of the positive and negative electrode solutions, and a platinum-plated titanium anode was arranged. 20 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the anolyte.

After energizing at 8 A · hr / l, Comparative Example 19 and Example 19 were compared. In Comparative Example 19, the bath was colored and deteriorated, which was considered to be the decomposition of mercaptoacetic acid, and the plating film appearance was deteriorated. On the other hand, in Example 19, good plating was obtained.

Comparative Example 20 The following bath 19 of 800 ml was used as a plating bath, and a platinum-plated titanium plate was used as an anode, and plating was performed without using a diaphragm. Eight hours of electricity and 16 hours of rest (at night) were repeated. Tin which is almost equal to the amount of deposition every 8 hours of energization,
Silver and arsenic were replenished in the form of a solution. Each replenisher was a solution complexed with mercaptopropanesulfonic acid. Bath 19 Sn ⁴⁺ (as tin chloride (tetravalent) pentahydrate) 0.12 mol / l Ag ⁺ (as silver nitrate) 0.37 mol / l 3-mercaptopropanesulfonic acid Na salt 1 mol / l 3 Arsenic oxide 100 mg / l pH 4.6 Temperature 40 ° C Current density 1 A / dm ²

Example 20 The cathode compartment and the anode compartment were separated by a filter cloth. A 400-ml bath 19 was used for each of the negative and positive electrode solutions, and a platinum-plated titanium anode was arranged. 20 g of activated carbon (Shirasagi A manufactured by Takeda Pharmaceutical Co., Ltd.) was added to the anolyte.

After energizing at 8 A · hr / l, Comparative Example 20 and Example 20 were compared. In Comparative Example 20, the bath was degraded, which was considered to be the decomposition of mercaptopropanesulfonic acid, and the plating film appearance was degraded. On the other hand, in Example 20, good plating was obtained.

[0141]

According to the method of the present invention, the anolyte solution and the catholyte solution (plating bath) are separated by a diaphragm or a partition, and furthermore, the impurities generated at the anode are trapped without diffusing into the plating solution. This makes it possible to suppress the deterioration of the plating bath or to perform a long-term operation while maintaining the balance of the bath components.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a method of plating by separating a cathode and an anode by a diaphragm.

FIG. 2 is a conceptual diagram of a method of plating by providing an auxiliary tank in which a cathode and an anode are separated by a diaphragm.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diaphragm 2 ... Anode 3 ... Anolyte 4 ... Cathode (plating object) 5 ... Catholyte (plating solution) 6 ... Cathode (dummy) 7 ... Plating tank 8 ... Auxiliary tank

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tetsuya Kondo 21-8 Minami-Futami, Futami-cho, Akashi-shi, Hyogo Inside the Daiwa Chemical Research Laboratory (72) Keigo Obata 21-8 Minami-Futami, Futami-cho, Akashi-shi, Hyogo Inside the Daiwa Chemical Research Laboratory (72) Inventor Kazuhiro Aoki 5-26 Nishiyanagiwara-cho, Hyogo-ku, Kobe-shi, Hyogo Inside Ishihara Pharmaceutical Co., Ltd. (72) Hidemi Nawafune 5-38-34 Magamicho, Takatsuki-shi, Osaka

Claims (9)

[Claims] 1. A cathode for electroplating from a tin-silver alloy electroplating bath containing a divalent and / or tetravalent tin ion, a monovalent silver ion, and a complexing agent of tin and silver as essential components. The solution (plating solution) and the anolyte are separated by a membrane or a partition capable of moving the solution and / or component ions, and furthermore, the anolyte contains divalent and / or tetravalent tin ions and soluble ions thereof. An amount of acid sufficient to hold the condition,
A method for electroplating a tin-silver alloy, comprising plating using an aqueous solution containing at least an alkali and / or a complexing agent. 2. The method of claim 1, wherein the diaphragm is an ion exchange membrane. 3. An anolyte in which an adsorbent for adsorbing impurities generated in the anolyte is suspended, and / or the adsorbent is made into a fluidized bed. The tin-silver-based alloy electroplating method according to claim 1, wherein adsorbent filtration is performed periodically or intermittently. 4. A plating method in which an adsorbent for adsorbing impurities is suspended in an anode bag, or plating is performed using an anode bag made of a material to which an adsorbent is fixed. The tin-silver-based alloy electroplating method according to any one of claims 1 to 3, characterized in that: 5. An auxiliary tank, wherein the auxiliary tank is provided.
5. A method for electroplating a tin-silver alloy, comprising replenishing a plating solution with tin ions and / or silver ions by the method according to any one of claims 4 to 4. 6. The tin and / or silver complexing agent in a plating solution for tin-silver alloy electroplating is a substance selected from the following (1) to (13): Items 1 to 5
The electroplating method of a tin-silver alloy according to any one of the above. (1) condensed phosphoric acid or a salt thereof, (2) an acid which forms each ion of iodine, bromine, iodic acid, bromic acid, sulfurous acid, bisulfite, metabisulfite, thiosulfate, thiocyanic acid, acetic acid, ammonium or salt, (3) the general formula X-R-COOH [wherein, R represents a single bond or an alkylene group C ₁ -C _4, hydrogen of the R is in the range up to the half, at any position, -S-CH _3, methyl group, an amino group, may be substituted by a hydroxyl group and (or) a carboxyl group. X represents hydrogen (except when R is a single bond), a carboxyl group, or CH ₂ OH. Oxycarboxylic acids, polycarboxylic acids or amino acids or salts thereof, (4) monosaccharides and partially oxidized polyhydroxycarboxylic acids and cyclic ester compounds thereof, (5) general formula: Formula 1 [Where R represents a C ₁ -C ₅ alkylene group, and the hydrogen of the alkyl may be substituted with an amino group or a carboxyl group, or may be bonded to an acetyl group via the amino group. Good. ] Represented by mercaptocarboxylic acid or mercaptosulfonic acid or salts thereof,
(6) General formula HO ₃ S—R—COOH [where R is a C ₁ -C ₆ alkylene group or C ₂ -C
Represents ₆ alkenylene groups, wherein the hydrogen of R may be substituted with a hydroxyl group or a carboxyl group. An aliphatic sulfo (hydroxy) carboxylic acid or a salt thereof represented by the general formula (7): [Where φ represents a benzene ring, X represents hydrogen, a hydroxyl group or a carboxyl group. The sulfonic acid group, carboxyl group and X may be at any position. An aromatic sulfo (hydroxy) carboxylic acid or a salt thereof represented by the general formula (8): [Wherein, X is -CH ₂ COOH or -C ₂ H ₄ COO
H represents Y and —CH ₂ COOH or —C ₂ H ₄ COO
H represents —CH ₂ OH, and Z represents —CH ₂ COOH or —C ₂ H ₄ COOH or —CH ₂ OH or hydrogen. A is a single bond, -CH (0H) -, or -CH ₂ -N
(CH ₂ COOH) —CH ₂ —, wherein B represents hydrogen, or when A is a single bond, B may be bonded via a methylene group to form a saturated 6-membered ring. (9) a hydroxyalkanebisphosphonic acid having 1 to 3 carbon atoms of an alkane or a salt thereof, and (10) a general formula: [Where X ₁ , X ₂ , X ₃ and X ₄ represent carbon or nitrogen, and when each of X _{1 to} X ₄ is nitrogen, R bonded to each X
_{1 ~R 4} does not exist. Not all X are nitrogen at the same time. R ₁ , R ₂ , R ₃ and R ₄ each independently represent hydrogen, a hydroxyl group or a C ₁ -C ₄ alkyl group, wherein the hydrogen of the alkyl group is substituted with a hydroxyl group, a carboxyl group or a halogen. May be. R _{1 and} R ₂ may form a benzene ring via a methylene group;
Hydrogen of the benzene ring, a halogen, an alkyl group of C ₁ -C _4, alkoxy group of C ₁ -C _4, may be substituted with a hydroxyl group or a carboxyl group. R ₅ is hydrogen, C
₁ alkyl or alkenyl of -C ₅ represents a phenyl group, the alkyl group, hydrogen alkenyl and (or) a phenyl group a hydroxyl group or amino group, may be substituted by mono-methylamino group or a dimethylamino group. A nitrogen-containing 5-membered heterocyclic compound represented by the formula (1):
1) General formula _{[Wherein, R 1, R 2, R} 3, R 4 and R ₅ each independently represent an alkyl group or an alkoxy group of hydrogen or C ₁ -C _5. X represents nitrogen or carbon, and when X is nitrogen, R ₄ is not present. A hydantoin compound represented by the formula: succinimide or maleic imide and derivatives thereof, (12) [Wherein R ₁ and R ₂ each independently represent hydrogen, an amino group or a C ₁ -C ₅ alkyl group. R ₃ and R ₄ each independently represent hydrogen, a C ₁ -C ₅ alkyl or alkenyl group or a phenyl group, wherein the hydrogen of the alkyl, alkenyl and / or phenyl is a hydroxyl group or an amino group, a monomethylamino group or a dimethyl group; It may be substituted with an amino group, and R ₃ and R ₄ may combine to form a ring. R ₅ represents an alkyl group, an allyl group or a hydroxy group. X represents nitrogen or carbon, and Y represents oxygen or sulfur. At the time of the X Haga nitrogen, R ₅ is not present. Urea, thiourea or thioacetamide and derivatives thereof represented by the formula: (13) [Where Ra, Rb and Rc each independently represent hydrogen, a hydroxyl group or a C ₁ -C ₅ alkyl group, wherein the hydrogen of the alkyl group is substituted with a hydroxyl group, an amino group or chlorine. The alkyl groups may be combined with each other to form a ring. And salts thereof. 7. A catholyte (plating solution) to which one or more of a conductive salt, a pH buffer, a surfactant, a smoothing additive, a gloss additive, and an antioxidant are further added. The tin according to any one of claims 1 to 6,
Silver alloy electroplating method. 8. A catholyte (plating solution) obtained by further adding one and / or two or more kinds of third metals selected from bismuth, copper, antimony, zinc, indium, palladium, arsenic and nickel. The method of electroplating a tin-silver alloy according to any one of claims 1 to 7, wherein 9. An electric / electronic circuit component plated with a tin-silver alloy using the tin-silver alloy electroplating method according to claim 1.