JPH111791A - Tin and alloy plating bath, method for controlling same and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly capture stannic oxide particles even if the particles are generated in a tin or tin alloy plating bath after use over a long period of time and to stabilize the transparency of the bath with the lapse of time by incorporating an org. or inorg. acid and a phosphorus compd. as a flocculation accelerator besides a soluble stannous salt or a mixture of the stannous salt with soluble salts of eight kinds of metals such as Pb. SOLUTION: The tin or tin alloy plating bath contains a soluble stannous salt or a mixture of the stannous salt with soluble salts of metals selected from among Pb, Ag, Zn, Bi, In, Ni, Co and Cu, at least one of org. acids such as alkanesulfonic acids, alkanolsulfonic acids and aliphatic carboxylic acids or inorg. acids such as hydrochloric acid, sulfuric acid and hydroborofluoric acid and an inorg. phosphorus compd. such as orthophosphoric acid or its salt or an org. phosphorus compd. such as methylenephosphonic acid or its salt as a flocculation accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tin and tin alloy plating bath for electroplating, and a method of controlling and preparing the same. Further, the present invention provides a plating bath capable of stabilizing transparency over time by promoting aggregation of the fine particles and quickly removing the fine particles with a filter.

[0002]

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

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

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

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

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

[0007]

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

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

[0009]

The above prior art 1 or 2
Both are intended to prevent the oxidation of stannous ions in the electroplating bath by adding a reducing agent such as hydrazine or hydroquinone (or an antioxidant) to the plating bath, but in fact, It only has the effect of delaying the oxidation rate of stannous ions to some extent, and even if the reducing agent is added, suspended fine particles of stannic oxide are generated within two to three months, and the transparency of the plating bath is lost. Then, once the quality of the plating bath is reduced to such a state, it is difficult to remove the plating bath as described above, so that the reliability of the bonding strength of the electrodeposition film obtained from the plating bath can be secured. Disappears.

[0010] The present invention provides a tin or tin alloy electroplating bath which can stably trap the particles and stabilize the transparency over time even if stannic oxide particles are generated by long-term use. Development is a technical issue.

[0011]

In general, fine particles of stannic oxide generated in a tin plating bath or a tin alloy plating bath such as a tin-lead alloy are extremely unlikely to grow or agglomerate, and have a property of being present as fine. have. Therefore,
The present inventors have promoted the crystal growth of stannic oxide particles in a plating bath, or coalesced and agglomerated the particles to increase the particle size, so that these particles can be captured by a filtration treatment and plated. The idea was to remove it from the bath and thereby stabilize the clarity of the bath over time. And, in a tin or tin alloy plating bath, as a result of earnestly studying what behavior the fine particles of stannic oxide show in the presence of various compounds, when a phosphorus compound is added to the plating bath,
The present inventors have found that the fine particles of stannic oxide promote aggregation and increase the particle diameter, thereby completing the present invention.

That is, the present invention 1 relates to (A) a stannous salt and a mixture of a stannous salt and a salt of a metal selected from lead, silver, zinc, bismuth, indium, nickel, cobalt and copper. A soluble salt composed of any of them, (B) an organic acid such as an alkanesulfonic acid, an alkanolsulfonic acid, or an aliphatic carboxylic acid, or at least one acid selected from inorganic acids such as hydrochloric acid, sulfuric acid, and borofluoric acid And (C) a tin and tin alloy plating bath containing a coagulation accelerator comprising a phosphorus compound.

[0013] The present invention 2 is a tin and tin alloy plating bath characterized by further containing a surfactant in addition to the plating bath of the present invention 1 described above.

[0014] The present invention 3 is a tin and tin alloy plating bath characterized by further containing a brightener in addition to the plating bath of the present invention 1 or 2.

[0015] The present invention 4 is a tin and tin alloy plating bath characterized by further containing a semi-brightening agent in addition to the plating bath of any of the above-mentioned present inventions 1 to 3.

[0016] The present invention 5 is a tin and tin alloy plating bath characterized by further containing an antioxidant in addition to the plating bath according to any one of the above-mentioned present inventions 1-4.

The present invention provides a plating bath according to any one of the above inventions 1 to 5, wherein the soluble metal salt of (A) and the acid of (B)
A phosphorus compound is added to a plating bath containing at least one of its salts to promote aggregation of fine particles of stannic oxide generated in the plating bath in the presence of the phosphorus compound, and stannic oxide is filtered by a treatment. This is a method for managing a tin and tin alloy plating bath, wherein the plating bath can be removed from the plating bath.

The present invention 7 provides the plating bath according to any one of the above-mentioned inventions 1 to 5, wherein the phosphorus compound is an acid, a soluble metal salt,
A tin and tin alloy plating bath, which is previously mixed with at least one of a surfactant, a semi-brightening agent, a brightening agent, or an antioxidant, and the mixture is mixed with the remaining bath components at the time of building bath. Preparation method of

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The phosphorus compound as an aggregation promoter includes orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, polyphosphoric acid, hypophosphorous acid, phosphorous acid, and their sodium, potassium and calcium salts, Inorganic phosphorus compounds such as magnesium salts, ammonium salts, barium salts, iron salts, salts such as zinc salts, aminotri (methylene phosphonic acid), 1-hydroxyethylidene-1-diphosphonic acid,
Ethylene diamine tetra (methylene phosphonic acid), alkyl phosphate (e.g., ethyl phosphate, diethyl phosphate, etc.),
And organic phosphorus compounds such as sodium salts, potassium salts, calcium salts, magnesium salts, ammonium salts, salts such as barium salts, iron salts, and zinc salts. The phosphorus compound can be used alone or in combination. The amount of the phosphorus compound is generally 0.01 to 100 g / L, preferably 0.05 to 10 g / L, more preferably 0.1 to 5 g, based on the entire plating bath.
/ L.

The above-mentioned acid is preferably an organic sulfonic acid such as alkanesulfonic acid or alkanolsulfonic acid, which has a relatively mild reaction in the plating bath, or an organic acid such as aliphatic carboxylic acid. Inorganic acids such as hydrofluoric acid, sulfuric acid, hydrofluorosilicic acid and perchloric acid can also be selected. The above acids are used alone or in combination, and the amount of the acid added is generally 0.1 to 400 g / L, preferably 70 to 400 g / L.
It is 150 g / L.

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

[0022] Examples of the alkanol sulfonic acid, the formula _{C m H 2m + 1 -CH (} OH) -C p H 2p + 1 -SO 3 H ( e.g., m =
0-2, p = 1-10), specifically, 2-hydroxyethane-1-sulfonic acid, 2-hydroxypropane-
In addition to 1-sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 2-hydroxypentane-1-sulfonic acid, etc., 1-hydroxypropane-2-sulfonic acid, 3-hydroxypropane-1-sulfonic acid, 4- Hydroxybutane-1-sulfonic acid, 2-hydroxyhexane-1-
Sulfonic acid, 2-hydroxydecane-1-sulfonic acid,
2-hydroxydodecane-1-sulfonic acid and the like.

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

The present invention is directed to a tin plating bath and a tin alloy plating bath. As described above, the tin alloy is selected from tin and lead, silver, zinc, bismuth, indium, nickel, cobalt, and copper. Alloys with metals. More specifically, it includes binary tin alloys such as tin-lead, tin-zinc, tin-silver, tin-bismuth, tin-nickel, tin-indium, tin-cobalt, and tin-copper.
Also includes tin-based alloys. As the mixture of the stannous salt or the stannous salt and the salt of a metal other than tin, any soluble salts can be used, and salts with the above-mentioned acids (particularly, organic sulfonic acids) are preferable. And the total concentration of other metals (equivalent addition amount as a metal) is generally 5 to 100
g / L.

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

[0026] Specific examples of the nonionic surfactants, C ₁ -C ₂₀ alkanols, phenol, naphthol, bisphenol, C ₁ -C ₂₅ alkyl phenols, aryl phenols, C ₁ -C ₂₅ alkyl naphthol, C ₁ ~ C ₂₅ alkoxylated phosphoric acid (salt), sorbitan esters, styrenated phenols, polyalkylene glycols, C ₁ -C ₂₂ aliphatic amines, C ₁ -C _22, such as ethylene oxide aliphatic amides (EO) and / or propylene oxide ( the PO) and those engaged 2-300 mol adduct condensation, and the like C ₁ -C ₂₅ alkoxylated phosphoric acid (salt).

The C ₁ -C ₂₀ alkanol for addition condensation of ethylene oxide (EO) and / or propylene oxide (PO) includes octanol, decanol, lauryl alcohol, tetradecanol, hexadecanol, stearyl alcohol, eicosanol, cetyl alcohol , Oleyl alcohol, docosanol and the like. Similarly, bisphenols include bisphenol A and bisphenol B. C ₁ -C ₂₅ alkylphenols include mono-, di- or trialkyl-substituted phenols such as p-butylphenol, p-isooctylphenol, p-nonylphenol, p-hexylphenol, 2,4-dibutylphenol, 2,4, Examples include 6-tributylphenol, p-dodecylphenol, p-laurylphenol, p-stearylphenol and the like. Examples of the arylalkylphenol include 2-phenylisopropylphenyl and the like. Examples of the alkyl group of the C ₁ -C ₂₅ alkyl naphthol include methyl, ethyl, propyl, butylhexyl, octyl, decyl, dodecyl, octadecyl and the like, and may be at any position on the naphthalene nucleus.
C ₁ -C ₂₅ alkoxylated phosphoric acid (salt) has the following general formula
(a).

[0028]

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

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

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

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

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

[0033]

Embedded image (In the formula (b), X is halogen, hydroxy, C ₁ -C ₅ alkanesulfonic acid or sulfuric acid, R ₁ , R ₂ and R ₃ are the same or different C ₁ -C ₂₀ alkyl, and R ₄ is C ₁ -C Represents ₁₀ alkyl or benzyl.) Or a pyridinium salt represented by the following general formula (c).

[0034]

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

Examples of the cationic surfactant in the form of a salt include lauryl trimethyl ammonium salt, stearyl trimethyl ammonium salt, lauryl dimethyl ethyl ammonium salt, octadecyl dimethyl ethyl ammonium salt, dimethyl benzyl lauryl ammonium salt, cetyl dimethyl benzyl ammonium salt Octadecyldimethylbenzylammonium salt, trimethylbenzylammonium salt, triethylbenzylammonium salt, hexadecylpyridinium salt, laurylpyridinium salt, dodecylpyridinium salt, stearylamine acetate,
Laurylamine acetate, octadecylamine acetate and the like can be mentioned.

Examples of the above anionic surfactant include alkyl sulfate, polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate, and alkylbenzene sulfonate.
Examples of the alkyl sulfate include sodium lauryl sulfate and sodium oleyl sulfate. Examples of the polyoxyethylene alkyl ether sulfate include sodium polyoxyethylene (EO12) nonyl ether sulfate and sodium polyoxyethylene (EO15) dodecyl ether sulfate. As polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene
(EO15) nonylphenyl ether sulfate and the like. Examples of the alkyl benzene sulfonate include sodium dodecyl benzene sulfonate.

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

[0038]

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

[0039]

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

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

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

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

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

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

Further, the antioxidant of the present invention 5 can be added to the plating bath of the present invention in order to suppress the oxidation of divalent tin, and the addition amount is generally 0.05 to 50 g / L, preferably. Is 0.1 to 10 g / L. As the antioxidant, ascorbic acid or a salt thereof, hydroquinone,
Cresol sulfonic acid or its salt, phenol sulfonic acid or its salt, catechol, resorcin, phloroglucin and the like can be mentioned.

Further, the plating bath of the present invention can contain the above-mentioned semi-brightener of the present invention 3 in order to improve the smoothness of the plating surface. The semi-brightening agent has a further synergistic effect when used in combination with various surfactants. The semi-brightening agent in this case is generally tin or tin-
Any semi-brightening agent used for lead alloy plating can be used in principle, but particularly useful semi-brightening agents include those represented by the following general formulas (f) to (i).

[0047]

Embedded image (In the formula (f), R is hydrogen, an alkyl group (C ₁ -C ₄ ) or a phenyl group, R ^I is hydrogen, a hydroxyl group or, if not present, R ^II is an alkylene group (C ₁ -C ₄ ), a phenylene group Or a benzyl group, R ^III is hydrogen or an alkyl group (C ₀ -C ₄ ).)

[0048]

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

[0049]

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

[0050]

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

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

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

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

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

[0055]

【The invention's effect】

(1) In the tin or tin alloy electroplating bath of the present invention, a phosphorus compound (inorganic phosphorus compound or organic phosphorus compound), which is an aggregation promoter, is added. Even if fine particles are generated, aggregation of the fine particles or crystal growth of the fine particles can be promoted, and the particle diameter of stannic oxide can be increased. Therefore, these particles are filtered by a filter provided with a plating apparatus. Can be easily captured using In particular, when a phosphorus compound is added to an organic sulfonic acid bath, a synergistic effect of an organic sulfonic acid and a phosphorus compound can be expected, as compared with an inorganic acid bath or the like. A remarkable capturing effect can be exhibited.
For this reason, as shown in a test example described later, the stannic oxide particles are promptly removed from the plating bath, whereby the transparency of the bath can be stabilized with time.

Incidentally, the mechanism of the aggregation or crystal growth of the fine particles of tin oxide is extremely difficult to analyze because a plurality of factors are intertwined in a complicated manner. Water molecules are adsorbed, and this water molecule is considered to be the main inhibitor of the aggregation of stannic oxide and crystal growth, and the phosphorus compound added to the plating bath acts on this water molecule, It can be guessed temporarily that this is a trigger for promoting the aggregation (or crystal growth) of stannic oxide.

Accordingly, in the conventional plating bath, fine particles of stannic oxide are suspended and dispersed in the plating bath due to long-term use and cannot be removed by a filter. Was mixed in the obtained plating film, and when soldering the plated part, there was a problem that voids were generated due to vaporization of water, but the present invention can effectively solve this problem. As a result, in the electrodeposition film obtained from the tin or tin alloy plating bath of the present invention,
(That is, when the management method of the present invention 6 is applied to a tin or tin alloy plating bath), the reliability of the bonding strength can be kept high.

(2) When hypophosphorous acid, phosphorous acid, or a salt thereof is selected as the phosphorus compound as an aggregation promoter, it is not enough to increase the particle diameter of stannic oxide generated in the plating bath. In addition, as shown in the test examples described below, the amount of stannic oxide generated itself can be suppressed to a low level, and stannic oxide can be more smoothly removed from the plating bath.

(3) As in the present invention 2, when a surfactant is additionally mixed into the plating bath, the particle appearance, adhesion, and denseness of the tin or tin alloy plating film can be further promoted.

(4) As in the present invention 3 or 4, when a brightening agent or a semi-brightening agent is additionally mixed into the plating bath, the gloss or smoothness of the plating film can be favorably promoted.

(5) As described in the present invention 5, when an antioxidant is additionally added to the plating bath, as described above, the rate at which divalent tin is oxidized to tetravalent can be slowed down. Tin production itself can be suppressed to some extent.

(6) As in the present invention 7, in preparing an electroplating bath, a phosphorus compound is separately added to an acid, a surfactant,
After previously mixed with at least one of a semi-brightening agent and the like, when combined with other bath components at the time of building the bath, as shown in the test examples described below, the aggregation promoting action of stannic oxide can be kept even higher. In addition, the phosphorus compound can be uniformly dissolved in the plating bath, and the preparation of the bath becomes easy.

[0063]

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

Example 1 A tin-lead alloy plating bath having the following composition was prepared. However, the preparation was carried out by a one-bath system in which all bath components were mixed simultaneously. 2-Hydroxypropanesulfonic acid-stannous (as Sn2 ⁺ ) 18g / L Lead 2-hydroxypropanesulfonate (as Pb2 ⁺ ) 2g / L Free 2-hydroxypropanesulfonic acid 140g / L Nonylphenol polyethoxylate ( EO15) 8g / L Catechol 1g / L Phosphorous acid 1g / L

Comparative Example 1 Comparative Example 1 was prepared by using the plating bath of Example 1 as a basic composition and omitting phosphorous acid.
(Accordingly, the addition conditions of each component were exactly the same except for the omitted component; the same applies to each of the following Comparative Examples) to prepare a tin-lead alloy plating bath.

Example 2 Among the plating baths of Example 1 above, the one in which lead 2-hydroxypropanesulfonate was omitted and other compositions were set under the same conditions was used as Example 2 and tin plating was performed by a single bath method. A bath was prepared.

Comparative Example 2 Comparative Example 2 was prepared by omitting the phosphorous acid while using the plating bath of Example 2 as the basic composition.
A tin plating bath was prepared.

Next, in the following Examples 3 to 6, the tin-lead alloy plating bath having the same composition as that of Example 1 was replaced with a one-bath method, and an inorganic phosphorus compound was used as one of the constituent components of the bath. And then mixed with the remaining bath components to prepare the respective components.

Example 3 Phosphorous acid was previously dissolved in an aqueous solution of stannous 2-hydroxypropanesulfonate (10% by weight as Sn ²⁺ ) at a rate of 0.56% by weight. (Amount: 180 g / L) and other bath components were combined to prepare a tin-lead alloy plating bath having the same composition as in Example 1.

Example 4 Phosphorous acid was previously dissolved in an aqueous solution of lead 2-hydroxypropanesulfonate (20% by weight as Pb ²⁺ ) at a ratio of 10% by weight. L) and other bath components were combined to prepare a tin-lead alloy plating bath having the same composition as in Example 1.

Example 5 Phosphorous acid was added to an aqueous solution (80% by weight) of free 2-hydroxypropanesulfonic acid in advance.
The mixture was dissolved at a ratio of 57% by weight,
2 g / L) and other bath components were combined to prepare a tin-lead alloy plating bath having the same composition as in Example 1.

Example 6 80 g / L of nonylphenol polyethoxylate (EO15), 10 g / L of catechol and 10 g / L of phosphorous acid were mixed in advance with water as a solvent, and this mixture was added (100 mL / L). And the other bath components were combined to prepare a tin-lead alloy plating bath having the same composition as in Example 1.

Example 7 A tin-lead alloy plating bath having the following composition was prepared by a one-bath method. Stannous ethanesulfonate (as Sn ²⁺ ) 16 g / L Lead ethanesulfonate (as Pb ²⁺ ) 4 g / L Free ethanesulfonic acid 120 g / L Sodium diisopropylnaphthalenedisulfonic acid 0.7 g / L Distyrenated phenol polyethoxy Rate (EO20) 7.5 g / L Hydroquinone 0.3 g / L Pyrophosphate 1.2 g / L

Comparative Example 3 A tin-lead alloy plating bath was prepared in the same manner as in Comparative Example 3 except that the plating bath of Example 7 was used as a basic composition and pyrophosphoric acid was omitted.

Example 8 Of the plating baths of Example 7 above, the one in which lead ethanesulfonate was omitted and the other compositions were set under the same conditions was used as Example 8, and a tin plating bath was used in a one-bath system. Prepared.

Comparative Example 4 A tin plating bath was prepared by using the plating bath of Example 8 as a basic composition and omitting pyrophosphoric acid as Comparative Example 4.

Example 9 A tin-lead alloy plating bath having the following composition was prepared by a one-bath method. Stannous methanesulfonate (as Sn ²⁺ ) 36 g / L Lead methanesulfonate (as Pb ²⁺ ) 4 g / L Free methanesulfonic acid 150 g / L Laurylamine polyethoxylate (EO15) 10 g / L Lauryldimethylammonium betaine 1 g / L 1-naphthaldehyde 0.1 g / L Methacrylic acid 1 g / L Resorcinol 2 g / L Sodium hypophosphite 5 g / L

Comparative Example 5 A tin-lead alloy plating bath was prepared using Comparative Example 5 in which the plating bath of Example 9 was used as a basic composition and sodium hypophosphite was omitted.

Example 10 A tin plating bath was prepared by a one-bath method using the plating bath of Example 9 except that lead methanesulfonate was omitted and other compositions were set under the same conditions. did.

Comparative Example 6 A tin plating bath was prepared as Comparative Example 6 except that sodium hypophosphite was omitted while using the plating bath of Example 10 as a basic composition.

Example 11 A tin-lead alloy plating bath having the following composition was prepared by a one-bath method. 2-hydroxyethane-1-sulfonic acid-stannous (as Sn2 ⁺ ) 54 g / L lead ethanesulfonate (as Pb2 ⁺ ) 6 g / L free methanesulfonic acid 100 g / L bisphenol A polyethoxylate (EO20) 8 g / L sodium n-butyl naphthalenedisulfonic acid 0.65 g / L triethylbenzylammonium chloride 1 g / L catechol 0.5 g / L orthophosphoric acid 10 g / L

Comparative Example 7 A tin-lead alloy plating bath was prepared in the same manner as in Comparative Example 7 except that the plating bath of Example 11 was used as a basic composition and orthophosphoric acid was omitted.

Example 12 A tin plating bath was prepared by a one-bath method using the plating bath of Example 11 except that lead ethanesulfonate was omitted and the other compositions were set under the same conditions. did.

Comparative Example 8 A tin plating bath was prepared by using the plating bath of Example 12 as a basic composition and omitting orthophosphoric acid as Comparative Example 8.

Example 13 A tin-lead alloy plating bath having the following composition was prepared by a one-bath method. Stannous propanesulfonate (as Sn ²⁺ ) 48 g / L Lead propanesulfonate (as Pb ²⁺ ) 12 g / L Free propanesulfonic acid 150 g / L β-naphthol polyethoxylate (EO13) -polypropoxylate (PO5 ) 8 g / L 2-aminobenzothiazole 0.1 g / L Hydroquinone 1 g / L Polyphosphoric acid 0.1 g / L

Comparative Example 9 A tin-lead alloy plating bath was prepared as Comparative Example 9 except that the plating bath of Example 13 was used as a basic composition and polyphosphoric acid was omitted.

Example 14 A tin plating bath was prepared by a one-bath method using Example 13 as the plating bath of Example 13 except that lead propane sulfonate was omitted and other compositions were set under the same conditions. did.

Comparative Example 10 A tin plating bath was prepared by using the plating bath of Example 13 as a basic composition and omitting the polyphosphoric acid as Comparative Example 10.

<< Comparative Example 11 >> A comparative example in which 5 g / L of sodium hypophosphite was omitted while replacing the plating bath of Example 9 with the basic composition and 5 g / L of hydrazine was used as Comparative Example 11, -A lead alloy plating bath was prepared.

Example 15 A tin-zinc alloy plating bath having the following composition was prepared by a one-bath method. Stannous sulfosuccinate (as Sn ²⁺ ) 24 g / L Zinc sulfosuccinate (as Zn ²⁺ ) 6 g / L Sulfosuccinic acid 0.6 mol / L Naphthol polyethoxylate (EO13) 2 g / L Lauryldimethylammonium betaine 0.1 g / L L-ascorbic acid 1.0 g / L pH (adjusted with sodium hydroxide) 4.5 Amino tri (methylene phosphonic acid) 0.1 g / L

Comparative Example 12 A tin-zinc alloy plating bath was prepared in the same manner as in Example 15 except that aminotri (methylenephosphonic acid) was omitted while using the plating bath of Example 15 as a basic composition.

Example 16 A tin-silver alloy plating bath having the following composition was prepared by a one-bath method. 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 Ethylenediaminetetra (methylenephosphonic acid) 0.3 g / L

Comparative Example 13 Comparative Example 13 was prepared by omitting ethylenediaminetetra (methylenephosphonic acid) while using the plating bath of Example 16 as a basic composition.
A tin-silver alloy plating bath was prepared.

Example 17 A tin-bismuth alloy plating bath having the following composition was prepared by a one-bath method. 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 Catechol 1 g / L Pyroline Acid 1g / L

Comparative Example 14 A tin-bismuth alloy plating bath was prepared as Comparative Example 14 except that the plating bath of Example 17 was used as a basic composition and pyrophosphoric acid was omitted.

Example 18 A tin-nickel alloy plating bath having the following composition was prepared by a one-bath method. Stannous chloride 45 g / L Nickel chloride (hexahydrate) 300 g / L Ammonium chloride 100 g / L Hydrochloric acid (35%) 50 ml / L Ammonium fluoride 60 g / L pH (adjusted with aqueous ammonia) 4.0 1-hydroxy Ethylidene-1-triphosphonic acid trisodium 0.2 g / L

Comparative Example 15 A tin-nickel alloy plating bath was prepared by using the plating bath of Example 18 as a basic composition and omitting the diphosphonate as Comparative Example 15.

Example 19 A tin-indium alloy plating bath having the following composition was prepared by a one-bath method. Stannous 2-propanol sulfonate (as Sn ²⁺ ) 10 g / L Indium chloride (as In ³⁺ ) 10 g / L 2-propanol sulfonic acid 100 g / L Sodium gluconate 100 g / L pH (adjusted with sodium hydroxide) 2.0 Phosphorous acid 0.5g / L

Comparative Example 16 A tin-indium alloy plating bath was prepared by using the plating bath of Example 19 as a basic composition and omitting phosphorous acid as Comparative Example 16.

Example 20 A tin-cobalt alloy plating bath having the following composition was prepared by a one-bath method. 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 1-Hydroxyethylidene-1-trisodium diphosphonate 0.2 g / L

Comparative Example 17 A tin-cobalt alloy plating bath was prepared in the same manner as in Comparative Example 17 except that the plating bath of Example 20 was used as a basic composition and the diphosphonate was omitted.

Then, by subjecting each plating bath to long-term aeration, the degree of generation of stannic oxide particles in each plating bath was compared and measured. << Evaluation test example of plating bath over time >> 500 mL of the prepared plating solution for each tin or tin-lead alloy bath was put into a 1-liter tall beaker, and this beaker was accommodated in a thermostat kept at 50 ° C. Next, aeration was performed by continuously blowing air at a rate of 1.5 L / min into the plating solution using a pump. 2 weeks and 4 days after the start of the air blowing operation
After a lapse of a week, each plating solution is collected and a laser diffraction particle size distribution analyzer (LA-500; Horiba, Ltd.)
The median diameter and the 2 μm sieved amount (volume fraction (%)) of the suspended stannic oxide particles were measured using the above method.

After 4 weeks, each plating solution was filtered with a # 5B filter paper, and the absorbance of each sample before and after the filtration was measured using a pure water as a reference at a wavelength of 660 nm at a spectrophotometer (U-2000 double type). Each was measured using a beam spectrophotometer (manufactured by Hitachi, Ltd.).

FIGS. 1 and 2 show the results. (1) Looking at the median diameter of stannic oxide in FIGS.
7.7 μm after 2 weeks with each plating solution of Examples 1 to 20
As mentioned above, after 4 weeks, it grew to 8.3 μm or more, whereas in Comparative Examples 1 to 17, it was 1.05 μm or less after 2 weeks.
Even after 4 weeks, it was 1.28 μm or less. In each of the plating solutions of Examples 1 to 20 in which an inorganic or organic phosphorus compound was added, the fine particles of stannic oxide promoted aggregation or crystal growth as compared with Comparative Examples 1 to 17 in which no plating solution was added. A remarkable increase in diameter was observed. In particular, in Examples 7 to 8 and 17 to which pyrophosphoric acid was added, 15.1 to 2 to 2 weeks later.
After 4 weeks, 16.7 μm, it grew to 18.1 to 20.3 μm, and the particle diameter of stannic oxide became the largest in the examples. This indicates that pyrophosphoric acid has a large effect of promoting the aggregation of stannic oxide particles among the phosphorus compounds.

(2) Looking at the 2 μm sieving amount in FIGS.
In Examples 1 to 20, as shown in the result of the above (1), since the particle diameter of stannic oxide is large, the ratio of transmission through the 2 μm sieve is 1.6% of Example 1 after 2 weeks, 0.7 of Example 2
With the exception of%, the rest were all 0%. Incidentally, in Examples 1 and 2, the sieving amount after 4 weeks was both 0%, and
Examples 3 to 6 in which a tin-lead alloy plating solution having the same composition as in Example 1 was prepared in a divided system instead of a single bath system.
In both cases, the sieving amount after 2 weeks was 0%. On the other hand, in Comparative Examples 1 to 17, since the stannic oxide particles are fine as shown in the above (1), the ratio of transmission through the 2 μm sieve is less than 95% to 100% even after 4 weeks. Met. This shows that it is difficult to remove the stannic oxide particles from the plating bath because the plating solution is almost permeated even if the plating solution is filtered using a filter attached to the plating apparatus. I have.

(3) Looking at the absorbance before and after filtration in FIGS. 1 and 2, in each of Examples 1 to 20, the absorbance was large due to the presence of stannic oxide generated in the plating solution before filtration. After filtration, the absorbance slightly decreased because the particles were almost completely removed by the filter paper. Incidentally, the absorbance before filtration is related to the amount of stannic oxide generated after 4 weeks, but in Examples 9 to 10 to which hypophosphite was added, the absorbance before filtration was different from that of other stannic oxides. It was considerably smaller than the example. this is,
Since hypophosphite has a reducing action, unlike other phosphorous compounds such as orthophosphoric acid and pyrophosphoric acid, it can be estimated that the generation of stannic oxide itself was suppressed, and the absorbance after filtration was observed. It can be seen that, since the particle diameter of stannic oxide generated in a small proportion is large, it can be easily removed. On the other hand, in Comparative Examples 1 to 17, since the generated stannic oxide particles were fine, the filtering effect by the filter paper could not be expected, and the absorbance before and after the filtration hardly changed. Incidentally, Example 9 in which hypophosphite was added,
Comparing Comparative Example 11 in which this hypophosphorous acid was replaced with hydrazine commonly used as a reducing agent in an electroless plating bath, a large difference was recognized in each of the median diameter, the amount under the sieve, and the absorbance after filtration.

(4) According to the above (1) to (3), when a phosphorus compound is added to a tin or tin alloy plating bath, oxidation of the plating bath (air oxidation or air oxidation) due to long-term use is greater than when no phosphorus compound is added. Even when anodic oxidation proceeds, fine particles of stannic oxide are generated, the particles can be promoted to aggregate or crystal grow to increase the median diameter. For this reason, the stannic oxide particles can be easily removed using a filter attached to the plating apparatus, and the transparency of the plating bath can be stabilized with time.

[Brief description of the drawings]

FIG. 1 shows the median diameter of the generated stannic oxide particles, the sieving amount of 2 μm, and before and after filtration of a plating solution when aeration is applied to each tin or tin alloy plating bath according to Examples 1 to 20. 4 is a chart showing the measurement results of absorbance.

FIG. 2 is a diagram corresponding to FIG. 1 showing measurement results of each plating bath of tin or tin alloy for Comparative Examples 1 to 17.

Continued on the front page (72) Inventor Kyoko Uchida 5-26 Nishiyanagihara-cho, Hyogo-ku, Kobe-shi, Hyogo Inside Ishihara Pharmaceutical Co., Ltd. (72) Inventor Takao Takeuchi Eight-stock company at 21 Futami-cho, Futami-cho, Akashi-shi, Hyogo Inside Daiwa Kasei Research Laboratories (72) Inventor Masakazu Yoshimoto 8 stocks at 21 Futami-cho Minami Futami-cho, Akashi City, Hyogo Prefecture Inside the Daiwa Kasei Research Laboratories (72) Shingo Kitamura 8 stocks at 21 Futami-cho Minami-Futami, Akashi-shi Hyogo Prefecture Daiwa Kasei Research Laboratories

Claims (7)

[Claims] (A) stannous salt, stannous salt and lead,
A soluble salt composed of any one of a mixture of a salt of a metal selected from silver, zinc, bismuth, indium, nickel, cobalt, and copper; (B) an organic acid such as an alkanesulfonic acid, an alkanolsulfonic acid, or an aliphatic carboxylic acid; Or a tin and tin alloy comprising an acid selected from inorganic acids such as hydrochloric acid, sulfuric acid, and borofluoric acid, and a coagulation accelerator comprising at least one (C) phosphorus compound of a salt thereof. Gold plating bath. 2. A tin and tin alloy plating bath, which further comprises a surfactant in addition to the plating bath according to claim 1. 3. A tin and tin alloy plating bath, further comprising a brightener in addition to the plating bath according to claim 1. 4. A tin and tin alloy plating bath, which further comprises a semi-brightening agent in addition to the plating bath according to claim 1. 5. A tin and tin alloy plating bath, further comprising an antioxidant in addition to the plating bath according to claim 1. Description: 6. The plating bath according to claim 1, wherein the plating bath containing the soluble metal salt of (A) and the acid of (B) and at least one of the salts thereof contains a phosphorus compound. To promote agglomeration of fine particles of stannic oxide generated in the plating bath in the presence of the phosphorus compound, and to remove stannic oxide from the plating bath by a filtration treatment. And management method of tin alloy plating bath. 7. The plating bath according to claim 1, wherein the phosphorus compound is an acid, a soluble metal salt, a surfactant, a semi-brightener, a brightener, or an antioxidant. A method for preparing a tin and tin alloy plating bath, wherein the mixture is mixed in advance with a crab and the mixture is mixed with the remaining bath components at the time of building the bath.