JP2014122410A - Tin or tin alloy plating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve, on a tin or tin alloy electroplating occasion, the homogeneity and stability of a plating film.SOLUTION: A sulfur-containing compound including a monocyclic heterocyclic group or condensed heterocyclic group including 1 to 5 members of at least one type of atom selected from among nitrogen, sulfur, and oxygen (excluding benzimidazole, benzothiazole, and benzoxazole cyclic groups) in a state where a sulfide group or mercapto group is coupled adjacently to the heterocyclic group is added to a tin bath or tin alloy bath such as a tin-nickel alloy, tin-zinc alloy, tin-indium alloy, etc. By virtue of the inclusion of the specified sulfur-containing compound including the heterocyclic group and sulfide group (or mercapto group), it becomes possible to improve the homogeneity of the thickness of the plating film and the homogeneity of the alloy composition and to stably preserve the film thickness and alloy composition even if the component concentration of the plating bath varies.

Description

  The present invention provides a tin or tin alloy plating bath that can improve the uniformity of the plating film, more specifically the uniformity of the film thickness and alloy composition and the stability of the plating film.

Tin plating or tin alloy plating such as tin-silver alloy, tin-copper alloy, tin-bismuth alloy, tin-lead alloy has good corrosion resistance and solder wettability. Recently, it is widely used as an industrial plating for electronic industry parts, but recently, due to the increase in environmental conservation, the demand for lead-free plating such as tin, tin-silver alloy, tin-bismuth alloy has increased. Yes.
In the tin plating and tin alloy plating, it is important to keep the film thickness and alloy composition of the electrodeposition film obtained from the plating bath uniform (hereinafter referred to as the uniformity of the plating film). It is also important that the film thickness and the alloy composition are stable (hereinafter referred to as the stability of the plating film) even if the component concentration varies.
To elaborate on this point, even if the appearance of the plating film is good, for example, if the uniformity of the plating film is impaired, when an electronic component is bonded to the substrate, bonding failure occurs at a thin film thickness part. In addition, if the alloy composition of the tin alloy film is not uniform and the composition is different at each part, a part where the film does not melt occurs due to the difference in melting point, resulting in poor bonding and lowering the reliability of the product. End up.

Accordingly, a tin or tin alloy plating bath whose main purpose is to improve the uniformity of the plating film, the appearance of the film, or the soldering property is as follows. However, Patent Documents 1 to 5 are disclosed by the present applicant.
(1) Patent Document 1
Add a benzoazole sulfonic acid compound, one of which is a benzoazole ring on the monosulfide bond and the other is an alkylene sulfonic acid (salt) group, to a tin or tin alloy plating bath to provide a coating appearance and soldering over a wide current density range. (Claim 1, paragraphs 1, 5, and 44).
Examples of the benzoazole-based sulfonic acid compound include 2-mercaptobenzimidazole-S-methanesulfonate, 2-mercaptobenzothiazole-S-propanesulfonate, 5-ethyl-2-mercaptobenzoxazole-S-butanesulfone. Examples thereof include sulfides having a sulfide group bonded adjacent to a benzoazole ring group such as an acid salt (paragraphs 17 to 18).

(2) Patent Document 2
Specific sulfide compounds with basic nitrogen atoms such as dipyridyl disulfide, triazolyl disulfide, ditetrazolyl disulfide, diimidazolyl disulfide, dithiazolyl disulfide, dimorpholino disulfide, dipyridazinyl disulfide, diquinolyl disulfide Addition to a silver alloy plating bath containing a tin-silver alloy improves the appearance of the electrodeposition film, the stability of the plating bath over time, the eutectoidization of silver and other metals, etc. (Claims 1 and 2, paragraphs) 1, 7).

(3) Patent Document 3
A 2-mercaptobenzoazole derivative is added to a tin or tin alloy plating bath to give the plating film a beautiful coating appearance (claims 1 and 2, paragraphs 1 and 17).
The 2-mercaptobenzoazole derivative includes sulfides having a sulfide group bonded adjacent to a benzoazole ring group such as 2- (3-hydroxypropylthio) benzothiazole and 2- (4-hydroxybutylthio) benzothiazole. (Claim 3, paragraph 22).

(4) Patent Document 4
A dibenzoazole disulfide sulfonic acid compound is added to a tin or tin alloy plating bath to improve plating film uniformity, film appearance, solderability, etc. over a wide current density range (Claim 1, paragraphs 1 and 18). .
The dibenzoazole disulfide sulfonic acid compound has a sulfonic acid (salt) group on both sides of the sulfide group such as dibenzothiazolyl disulfide disulfonate, dibenzooxazolyl disulfide disulfonate, dibenzimidazolyl disulfide disulfonate. Examples thereof include sulfides to which a benzoazole ring group is bonded (paragraph 22).

(5) Patent Document 5
Aromatic sulfides and aromatic mercaptans are added to the tin-silver alloy plating bath to improve plating appearance and solderability (Claims 1 and 4 and paragraphs 1 and 18).
2,2'-dipyridyl disulfide, 2,2'-dithiodianiline, 3,4,5-trihydroxydiphenyl sulfide for aromatic sulfides, mercaptopyridine, 2-aminothiophenol, etc. for aromatic mercaptans (Paragraphs 30 to 31).

(6) Patent Document 6
Thioureas, 2-mercapto group-containing aromatic compounds, and nonionic surfactants are added to a tin-copper alloy plating bath to improve solderability and bath stability (claim 1, paragraph). 8).
Examples of the 2-mercapto group-containing aromatic compound include mercaptopyridine, 2-mercaptobenzimidazole compound, 2-mercaptobenzoxazole compound, 2-mercaptobenzothiazole compound, mercaptophenol, 2-mercaptoethylamine and the like. (Claim 2, paragraph 22).

(7) Patent Document 7
Add soluble tartrate, bismuth salt, anionic surfactant, nitrogen-containing compound, and sulfur-containing compound to the cyanide tin-copper alloy plating bath to achieve smoothness and gloss in a wide current density range. (Claims 1 to 4)
Examples of the sulfur-containing compound include mercaptans composed of 2-mercaptobenzimidazole, 2-mercaptobenzothiazole, or derivatives thereof, dibenzothiazyl disulfide, benzothiazyl morpholino sulfide, sulfides composed of benzothiazyl morpholino disulfide, and the like. And sulfur-containing heterocyclic compounds (see paragraph 15, chemical formulas 3 to 4).

(8) Patent Document 8
An aromatic thiol compound or an aromatic sulfide compound is added to a non-cyan tin-silver alloy plating bath to improve the stability of the bath, and a thin film of 1 to 30 μm is obtained (claims 1 and 2, paragraph 10). ).
Examples of the aromatic thiol compound include mercaptophenol, thiosalicylic acid, hensenthiophenol, and mercaptopyridine. Examples of the aromatic sulfide compound include 2,2-dipyridyl disulfide, 4,4-thiodiphenol, and thiobisthiophenol. 2,2-dithiodibenzoic acid and the like (claim 3, paragraph 6).

Japanese Patent Laid-Open No. 10-025595 Japanese Patent Application Laid-Open No. 11-269691 JP 2009-185358 A JP 2010-265491 A JP 2006-265573 A JP 2002-080993 A Japanese Patent Application Laid-Open No. 8-027590 Japanese Patent Laid-Open No. 10-204675

As a compound to be added to the tin or tin alloy bath of Patent Documents 1 to 8, a sulfur-containing compound is mainly used as a main component. However, a tin- or tin-alloy plating film is uniformly formed by adding a sulfur-containing compound to a plating bath. When trying to improve property and appearance, for example, among 2-mercaptobenzoazole derivatives disclosed in Patent Document 3, 2- (3-hydroxypropylthio) benzothiazole is added to a tin or tin alloy plating bath. However, the plating film obtained has a problem that the film thickness is not uniform over the entire surface and the film uniformity is poor.
Further, among aromatic sulfide compounds disclosed in Patent Document 8, 4,4-thiodiphenol may be added to a tin or tin alloy plating bath, or a derivative of thiodiphenol disclosed in Patent Document 4 Even if 3,4,5-trihydroxydiphenyl sulfide is added, the uniformity of the plating film is similarly poor.
Thus, even if the various sulfur-containing compounds disclosed in Patent Documents 1 to 8 are added to a tin or tin alloy plating bath, it is insufficient to improve the uniformity of the plating film. Even if the film thickness and alloy composition of the film are kept uniform or the concentration of the plating bath varies, it is difficult to stabilize the film thickness and alloy composition.

  This invention makes it a technical subject to improve the uniformity and stability of a plating film at the time of electrotin and tin alloy plating.

The present inventors have started from aromatic sulfur-containing compounds such as compounds having a benzoazole ring disclosed in Patent Documents 1 to 8 above, focusing on related cyclic compounds, and these are tin or tin compounds. We have intensively studied the effects on the uniformity and stability of the resulting plating film when added to a gold plating bath.
As a result, sulfide containing an atom selected from nitrogen, sulfur and oxygen and adjacent to a monocyclic heterocyclic group or a condensed heterocyclic group excluding the so-called benzoazole ring group of benzimidazole, benzothiazole and benzoxazole When a sulfur-containing compound to which a group or a mercapto group is bonded is added to a specific tin alloy plating bath excluding tin or a tin-silver alloy and a tin-copper alloy, the thickness of the resulting plating film and the variation in the alloy composition are suppressed. The uniformity of the plating film can be improved, and the film thickness and alloy composition can be stabilized even if the concentration of the plating bath varies. For the tin-copper alloy plating bath, the above excluding pyridine, morpholine, and benzoazole ring groups Addition of a sulfur-containing compound having a sulfide group or mercapto group bonded adjacent to the heterocyclic group, For plating baths, the addition of sulfur-containing compounds with mercapto groups bonded adjacent to the above heterocyclic groups excluding pyridine, morpholine, and benzoazole ring groups can also improve the uniformity and stability of the plating film. As a result, the present invention has been completed.

That is, the present invention 1 is any one of (A) a stannous salt and a mixture of a stannous salt and a metal salt selected from zinc, nickel, bismuth, cobalt, indium, antimony, gold, and lead. Soluble salts,
(B) an acid;
(C) a monocyclic heterocyclic group or a condensed heterocyclic group containing 1 to 5 atoms selected from nitrogen, sulfur and oxygen (excluding benzimidazole, benzothiazole and benzoxazole ring groups) And a tin and tin alloy plating bath containing a sulfur-containing compound having a sulfide group or a mercapto group bonded adjacent to the heterocyclic group.

Invention 2 comprises (A) a mixture of a soluble stannous salt and a soluble copper salt;
(B) an acid;
(C) Monocyclic heterocyclic group or condensed heterocyclic group containing 1 to 5 atoms selected from nitrogen, sulfur and oxygen (provided that pyridine, morpholine, benzimidazole, benzothiazole, benzoxazole ring group) And a sulfur-containing compound having a sulfide group or a mercapto group bonded to the heterocyclic group adjacent to the heterocyclic group.

Invention 3 comprises (A) a mixture of a soluble stannous salt and a soluble silver salt,
(B) an acid;
(C) Monocyclic heterocyclic group or condensed heterocyclic group containing 1 to 5 atoms selected from nitrogen, sulfur and oxygen (excluding pyridine, benzimidazole, benzothiazole, benzoxazole ring group) And a sulfur-containing compound having a mercapto group bonded adjacent to the heterocyclic group.

  Invention 4 is the invention according to any one of Inventions 1 to 3, wherein the monocyclic heterocyclic group or condensed heterocyclic group provided in the sulfur-containing compound is tetrazole, triazole, thiazole, thiadiazole, imidazole, quinoline, furan, Morpholine, thiophene, pyridine, oxazole, oxadiazole, pyrrole, pyrazole, pyrazine, isothiazole, isoxazole, pyrazolidine, pyrimidine, pyridazine, pyrrolidine, indolizine, indole, isoindole, indazole, purine, isoquinoline, naphthyridine, quinoxaline, Carbazole, phenanthroline, phenazine, phenothiazine, phenothiazine, phenoxazine, phenanthridine, pyrroline, imidazolidine, pyrazoline, imidazoline, piperidine, piperazi , Indoline, tin and tin-alloy plating baths which is characterized in that either a heterocyclic group selected from thianthrene.

  Invention 5 contains at least one additive selected from surfactants, antioxidants, brighteners, semi-brighteners, complexing agents, and pH adjusters in any of the present inventions 1-4. This is a tin and tin alloy plating bath.

  The present invention 6 is a tin and tin alloy plating method characterized by forming a tin or tin alloy film on an electronic component using the tin or tin alloy plating bath according to any one of the present inventions 1 to 5.

  The present invention 7 is an electronic component having a tin or tin alloy film formed by the plating method of the present invention 6.

A film of an electrodeposition film obtained from a plating bath to add a specific sulfide or mercaptan having a monocyclic heterocyclic group or condensed heterocyclic group containing nitrogen, sulfur or oxygen to a tin or tin alloy plating bath The thickness and alloy composition can be kept uniform, the plating film uniformity is excellent, and the film thickness and alloy composition can be stabilized even if the concentration of the plating bath varies.
For this reason, the electrodeposited film is formed on the substrate using various tin alloy plating baths such as tin or tin-silver alloy, tin-copper alloy, tin-bismuth alloy, tin-zinc alloy, tin-nickel alloy of the present invention. Even if formed, it is possible to prevent the occurrence of a portion with a thin film thickness over the entire surface of the plating or a portion with a different alloy composition of the coating, so that the electronic component can be satisfactorily bonded to the substrate through the plating coating. Improve product reliability.

Patent Document 1 describes a tin and tin alloy plating bath containing a benzoazole sulfonic acid compound such as 2-mercaptobenzimidazole-S-methanesulfonate and 2-mercaptobenzothiazole-S-propanesulfonate. Patent Document 3 (Japanese Patent Laid-Open No. 2009-185358) discloses 2-mercaptobenzothiazole derivatives such as 2- (3-hydroxypropylthio) benzothiazole and 2- (4-hydroxybutylthio) benzothiazole. Is added to a tin or tin alloy plating bath, and Patent Document 4 (Japanese Patent Laid-Open No. 2010-265491) describes dibenzoazole disulfide disulfonates such as dibenzothiazolyl disulfide disulfonate as tin or tin. Addition to alloy plating bath is described, or , JP 2001-254194, 2-mercaptobenzothiazole, 2-mercaptobenzimidazole tin bath benzazole compounds such as, or tin - are described to be added to the lead alloy bath.
All of these compounds are sulfur-containing compounds in which a benzoazole ring group and a sulfide group are adjacent to each other. However, in the sulfur-containing compounds added to the tin and tin alloy plating bath of the present invention, the sulfur-containing compounds constitute the sulfur-containing compounds. The monocyclic heterocyclic group or condensed heterocyclic group to be used does not include a so-called benzoazole ring group.

Patent Document 2 discloses monocyclic compounds such as dipyridyl disulfide, triazolyl disulfide, ditetrazolyl disulfide, diimidazolyl disulfide, dithiazolyl disulfide, dimorpholino disulfide, dipyridazinyl disulfide, and diquinolyl disulfide. It is described that a specific sulfide compound having a heterocyclic group or a condensed heterocyclic group is added to a silver alloy plating bath containing a tin-silver alloy.
Patent Documents 5 and 8 also describe the addition of aromatic sulfides such as 2,2′-dipyridyl disulfide and aromatic mercaptans such as mercaptopyridine to the tin-silver alloy plating bath.
These compounds are all sulfur-containing compounds in which a heterocyclic group such as a pyridine ring, a triazole ring group, an imidazoline ring group and a sulfide group are adjacent to each other, but are added to the tin-silver alloy plating bath of the present invention. In this case, only the mercapto group is bonded to the monocyclic heterocyclic group or condensed heterocyclic group constituting the sulfur-containing compound, the sulfide group is excluded, and the pyridine ring group is added to the heterocyclic group. Is not included.
Further, the tin alloy plating baths of Patent Documents 1 and 3-4 include a tin-silver alloy plating bath. In Patent Document 1, benzoazole-based sulfonic acid compounds belonging to sulfides are used, and in Patent Document 3, 2 belonging to sulfides. -A mercaptobenzoazole derivative is added to each dibenzoazole disulfide sulfonic acid compound belonging to sulfides in Patent Document 4, but the heterocyclic group constituting the sulfur-containing compound added to the tin-silver alloy plating bath of the present invention includes In addition, a so-called benzoazole ring group is not included, and a mercapto group, not a sulfide group, is bonded to the heterocyclic group.

Patent Document 6 describes that 2-mercapto group-containing aromatic compounds such as mercaptopyridine and 2-mercaptobenzimidazole compounds are added to a tin-copper alloy plating bath, and Patent Document 7 discloses cyan tin. -In the copper alloy plating bath, mercaptans such as 2-mercaptobenzimidazole and 2-mercaptobenzothiazole, and sulfides such as dibenzothiazolyl disulfide and benzothiazolyl morpholino disulfide are described.
In addition, as described above, the tin alloy plating baths of Patent Documents 1 and 3 to 4 include a tin-copper alloy plating bath. In Patent Document 1, a benzoazole-based sulfonic acid compound belonging to a sulfide is used, and in Patent Document 3, a sulfide is used. Patent Document 4 describes that a 2-mercaptobenzoazole derivative belonging to 1 is added and a dibenzoazole disulfidesulfonic acid compound belonging to sulfide is added.
However, the monocyclic heterocyclic group or condensed heterocyclic group constituting the sulfur-containing compound added to the tin-copper alloy plating bath of the present invention includes both a pyridine ring group, a morpholine ring group, or a so-called benzoazole ring group. Not included.

The present invention firstly relates to tin and tin-zinc containing a sulfur-containing compound in which a sulfide group or a mercapto group is bonded adjacent to a monocyclic heterocyclic group or condensed heterocyclic group containing nitrogen, sulfur or oxygen. Specific tin alloy plating baths such as alloys, tin-nickel alloys, tin-bismuth alloys, etc. Second, similar monocyclic heterocyclic group or condensed heterocyclic group and sulfide group or mercapto group are located adjacent to each other A tin-copper alloy plating bath containing a sulfur-containing compound, and third, a tin-containing sulfur-containing compound in which the same monocyclic heterocyclic group or condensed heterocyclic group and a mercapto group are located adjacent to each other A silver alloy plating bath, and fourth, a tin and tin alloy plating method for forming an electrodeposition film on electronic parts using these tin or tin alloy plating baths, and fifth, electrodeposition by the plating method Film The formed which is an electronic component.
In this case, in the first invention (that is, the tin bath of the present invention 1 or a specific tin alloy bath), a benzimidazole, a benzothiazole, a benzoxazole ring group is selected from a monocyclic heterocyclic group or a condensed heterocyclic group. The so-called benzoazole ring group is removed, and the specific tin alloy bath does not include tin-copper alloy and tin-silver alloy plating baths.
In the second invention (the tin-copper alloy plating bath of the present invention 2), the pyridine ring group, the morpholine ring group, and the benzoazole ring group are excluded from the monocyclic heterocyclic group or the condensed heterocyclic group.
In the third invention (the tin-silver alloy plating bath of the present invention 3), the pyridine ring group and the benzoazole ring group are removed from the monocyclic heterocyclic group or the condensed heterocyclic group, and the heterocyclic group is Only the mercapto group is adjacent and the sulfide group is excluded.

The present invention 1 comprises a tin plating bath and a tin alloy plating bath. One tin plating bath comprises (A) a soluble stannous salt, (B) an acid, and (C) a monocyclic heterocyclic group or a condensed heterocyclic group. And a sulfur-containing compound having a sulfide group or a mercapto group bonded adjacent to the heterocyclic group.
On the other hand, the tin alloy plating bath of the present invention 1 is a plating bath of a specific tin alloy excluding tin-copper alloy and tin-silver alloy. (A) stannous salt and zinc, nickel, bismuth, cobalt, indium And a soluble salt of any of a mixture of metal salts selected from antimony, gold, and lead, (B) an acid, and the sulfur-containing compound (C).

The feature of the present invention 1 is that the sulfur-containing compound (C) is added to a tin bath or a tin alloy bath, and the monocyclic heterocyclic group or condensed heterocyclic group constituting the sulfur-containing compound is nitrogen, sulfur, 1 to 5 of at least one atom selected from oxygen is contained.
Preferred examples of the monocyclic heterocyclic group or the condensed heterocyclic group include tetrazole, triazole, thiazole, thiadiazole, imidazole, quinoline, furan, morpholine, thiophene, pyridine, oxazole, oxadiazole, pyrrole, pyrazole, pyrazine, Isothiazole, isoxazole, pyrazolidine, pyrimidine, pyridazine, pyrrolidine, indolizine, indole, isoindole, indazole, purine, isoquinoline, naphthyridine, quinoxaline, carbazole, phenanthroline, phenazine, phenothiazine, phenothiazine, phenoxazine, phenanthridine, pyrroline Imidazolidine, pyrazoline, imidazoline, piperidine, piperazine, indoline, thianthrene (see the present invention 4), Ri preferably tetrazole, triazole, thiazole, thiadiazole, thiophene, pyridine, imidazole, quinoline, phenanthroline, imidazolidine, imidazoline, piperidine.
As described above, with respect to the monocyclic or complex heterocyclic group, in the tin-copper alloy plating bath of the present invention 2, a so-called benzoazole ring group or pyridine ring formed of benzimidazole, benzothiazole, or benzoxazole is used. Since the group and the morpholine ring group are removed, a preferable one is selected from the heterocyclic groups except these.
In the tin-silver alloy plating bath of the present invention 3, the benzoazole ring group and the pyridine ring group are removed. In the tin plating bath of the present invention 1, or in the specific tin alloy plating bath excluding the tin-silver alloy and the tin-copper alloy, The benzoazole ring group is excluded, and the specific selection from the remaining heterocyclic group is the same as in the case of the tin-copper alloy plating bath.

In the present invention 1-2, the sulfur-containing compound (C) has a sulfide group or a mercapto group adjacent to a monocyclic heterocyclic group or a condensed heterocyclic group, but the tin-silver alloy plating bath of the present invention 3 Then, only the mercapto group is adjacent to the heterocyclic group, and the sulfide group is excluded.
The sulfide group includes not only monosulfides but also polysulfides having 2 to 5 sulfur atoms bonded thereto such as disulfides, trisulfides, tetrasulfides and the like.
In the case of a sulfide group adjacent to a heterocyclic group, a C1-C6 alkylene group may be interposed between monosulfide or polysulfide. However, even in this case, the adjacent to the heterocyclic group is necessarily a sulfide group, not an alkylene group.
In addition, in the bond between the heterocyclic group and the sulfide group, the heterocyclic group may be bonded adjacent to both sides of the sulfide group, or the heterocyclic group is bonded adjacent to only one side of the sulfide group, For example, other than a heterocyclic group such as an aryl group, an alkyl group, an alkenyl group, and an arylalkyl group may be bonded.
1 to 5 substituents such as alkyl, alkenyl, hydroxyl, hydroxyalkyl, carboxyl, amino, halogen, sulfonic acid group, acetyl, nitro, mercapto, alkylsulfonic acid group may be bonded to the heterocyclic group. However, it may be unsubstituted.
The total concentration of the sulfur-containing compound (C) in the bath is preferably 0.0001 to 10 mol / L, more preferably 0.001 to 5 mol / L.

The sulfur-containing compound of the present invention can be synthesized by various conventional methods.
For example, a compound in which a monosulfide group is adjacent to a monocyclic heterocyclic group or a condensed heterocyclic group is synthesized by a conventional method such as reacting sodium thiolate with a halide to form a monosulfide bond. A compound in which a disulfide group is adjacent to a monocyclic heterocyclic group or a condensed heterocyclic group is synthesized by a conventional method such as oxidizing a thiol compound with an oxidizing agent such as hydrogen peroxide or iodine to form a disulfide bond. The
A compound in which a mercapto group is adjacent to a monocyclic heterocyclic group or a condensed heterocyclic group is synthesized by a conventional method such as reacting a halide with hydrogen sulfide in the presence of an alkali.

Incidentally, the sulfur-containing compound of the present invention can basically be obtained as a commercial product.
Specific examples of the sulfur-containing compound of the present invention that can be obtained include 5,5'-dithiobis (1-phenyl-1H-tetrazole), 4,4'-diimidazole disulfide, 2-mercapto-1-methyl. Imidazole, 5-mercapto-1-methyltetrazole, (2-mercapto-4-methylthiazol-5-yl) acetic acid, 4-mercaptomorpholine, 3,3′-dithiobis-1H-1,2,4-triazole, 2 , 2'-dithiodipyridine, 4-mercaptoquinoline-3-sulfonic acid, 2-methyl-3-furanthiol, 2,2'-dithienyl disulfide, 2-mercaptopyridine, methyl-2-pyridyl sulfide, 2- Mercapto-3-pyridinecarboxylic acid, 2,2'-dithiobis (5-nitropyridine), 2-pyrimidinethiol, 4, '-Dimethylpyrimidine-2-thiol, 4,6'-dihydroxy-2-mercaptopyrimidine, 4,6'-diamino-2-mercaptopyrimidine, 1,3'-dithiolen-2-thione, 2-mercaptothiophene, , 3,5-triazole-2-trithiol, 1,3,4-thiadiazole-2-thiol, 2,5-dimercapto-1,3,4-thiadiazole, 5-methylthio-1,3,4-thiadiazole-2 -Thiol, 2-mercapto-5-methyl-1,3,4-thiadiazole, 3,3- (trimethylenebisthio) bis [4-amino-1H-1,2,4-triazole-5 (4H)- Thion], 3- (2-pyridinethio) -propanesulfonic acid, and the like.

  In the tin or tin alloy plating bath of the present invention 1, the soluble stannous salt (A) is basically a tin salt of an organic acid or an inorganic acid that generates Sn 2+ in water. Tin, stannous acetate, stannous borofluoride, stannous sulfamate, stannous pyrophosphate, stannous chloride, stannous gluconate, stannous tartrate, stannous oxide, sodium stannate, Examples include potassium stannate, stannous methanesulfonate, stannous ethanesulfonate, stannous 2-hydroxyethanesulfonate, stannous 2-hydroxypropanesulfonate, and stannous sulfosuccinate.

In the specific tin alloy plating bath of the present invention 1, the metal of the tin counterpart that forms the tin alloy is selected from zinc, nickel, bismuth, cobalt, indium, antimony, gold, and lead.
As for the soluble salt of the other metal, for example, the soluble salt of bismuth includes bismuth sulfate, bismuth gluconate, bismuth nitrate, bismuth oxide, bismuth carbonate, bismuth chloride, bismuth methanesulfonate, 2-hydroxypropanesulfonic acid. There is bismuth.
Soluble salts of indium include indium sulfamate, indium sulfate, indium borofluoride, indium oxide, indium methanesulfonate, and indium 2-hydroxypropanesulfonate.
Soluble zinc salts include zinc sulfate, zinc nitrate, zinc chloride, zinc pyrophosphate, zinc cyanide, zinc methanesulfonate, zinc 2-hydroxyethanesulfonate, zinc 2-hydroxypropanesulfonate, and the like.
Soluble salts of antimony include antimony borofluoride, antimony chloride, potassium antimony tartrate, potassium pyroantimonate, antimony tartrate, antimony methanesulfonate, and antimony 2-hydroxypropanesulfonate.
Soluble nickel salts include nickel sulfate, nickel formate, nickel chloride, nickel sulfamate, nickel borofluoride, nickel acetate, nickel methanesulfonate, nickel 2-hydroxypropanesulfonate.
Soluble lead salts include lead acetate, lead nitrate, lead carbonate, lead borofluoride, lead sulfamate, lead methanesulfonate, lead ethanesulfonate, lead 2-hydroxyethanesulfonate, lead 2-hydroxypropanesulfonate, etc. There is.
Examples of the soluble salt of cobalt include cobalt sulfate, cobalt chloride, cobalt acetate, cobalt borofluoride, cobalt methanesulfonate, and cobalt 2-hydroxypropanesulfonate.

The total concentration of the metal soluble salt in the bath is generally 1 to 200 g / L, preferably 10 to 100 g / L in terms of metal salt.
Moreover, what is necessary is just to adjust suitably the mixing ratio of soluble stannous salt and the soluble salt of the metal of the other party which forms an alloy according to the composition ratio of the desired tin alloy plating film.

The tin alloy of the present invention 1 is an alloy of tin and at least one metal selected from the group consisting of zinc, nickel, bismuth, cobalt, indium, antimony, gold, lead, and specifically, tin-bismuth. , Tin-indium, tin-zinc, tin-antimony, tin-nickel, tin-gold, tin-cobalt, tin-lead alloys, tin-zinc-nickel, tin-bismuth-silver, tin -Includes alloys of three or more components such as bismuth-lead and tin-lead-silver.
From the viewpoint of bath management, the aforementioned two-component tin alloy is preferable.

In the tin or tin alloy plating bath of the present invention 1, the acid (B) used as a bath base is an organic acid, an inorganic acid, or an alkali metal salt, alkaline earth metal salt, ammonium salt, amine salt, or the like thereof.
Examples of the organic acid include organic sulfonic acid and aliphatic carboxylic acid, and examples of the inorganic acid include sulfuric acid, hydrochloric acid, borohydrofluoric acid, hydrofluoric acid, and sulfamic acid. Among these, a bath of an organic sulfonic acid or a salt thereof is preferable from the standpoint of sulfuric acid bath, tin solubility, ease of wastewater treatment, and the like.
The acid or salt thereof can be used singly or in combination, and its content is 0.1 to 10 mol / L, preferably 0.5 to 5 mol / L.

  Examples of the organic sulfonic acid include alkane sulfonic acid, alkanol sulfonic acid, sulfosuccinic acid, and aromatic sulfonic acid. As the alkane sulfonic acid, those represented by the chemical formula CnH2n + 1SO3H (for example, n = 1 to 11) are used. Specific examples include methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid, and the like.

Examples of the alkanol sulfonic acid include chemical formula CmH2m + 1-CH (OH) -CpH2p-SO3H (for example, m = 0 to 6, p = 1 to 5).
In particular, 2-hydroxyethane-1-sulfonic acid (isethionic acid), 2-hydroxypropane-1-sulfonic acid (2-propanolsulfonic acid), 3-hydroxypropane-1 -Sulfonic acid, 2-hydroxybutane-1-sulfonic acid, 2-hydroxypentane-1-sulfonic acid and the like, 1-hydroxypropane-2-sulfonic acid, 4-hydroxybutane-1-sulfonic acid, 2-hydroxy Examples include hexane-1-sulfonic acid.

The aromatic sulfonic acid is basically benzene sulfonic acid, alkyl benzene sulfonic acid, phenol sulfonic acid, naphthalene sulfonic acid, alkyl naphthalene sulfonic acid, naphthol sulfonic acid, etc., specifically, 1-naphthalene sulfonic acid, 2 -Naphthalenesulfonic acid, toluenesulfonic acid, xylenesulfonic acid, p-phenolsulfonic acid, cresolsulfonic acid, sulfosalicylic acid, nitrobenzenesulfonic acid, sulfobenzoic acid, diphenylamine-4-sulfonic acid and the like.
Among the organic sulfonic acids, methanesulfonic acid, ethanesulfonic acid, 2-propanolsulfonic acid, 2-hydroxyethanesulfonic acid, and the like are preferable.

The tin-copper alloy plating bath of the present invention 2 contains (A) a mixture of a soluble stannous salt and a soluble copper salt, (B) an acid, and (C) a sulfur-containing compound.
Among the components (A), the soluble salts of copper include copper sulfate, copper nitrate, copper carbonate, copper pyrophosphate, copper chloride, copper cyanide, copper borofluoride, copper sulfamate, copper methanesulfonate, 2-hydroxy Examples include copper ethane sulfonate and copper 2-hydroxypropane sulfonate.
The acid of component (B) is the same as that of the present invention 1.
The sulfur-containing compound of component (C) is basically the same as in the present invention 1 except that the pyridine ring group and the morpholine ring group are excluded from the heterocyclic group in addition to the benzoazole ring group.
Accordingly, a tin-copper alloy bath to which not only a benzoazole compound such as 2-mercaptobenzothiazole but also a sulfur-containing compound such as mercaptopyridine and morpholino sulfide is added is excluded from the tin-copper alloy plating bath of the present invention 2. .
In the case of the tin-copper alloy plating bath of the present invention 2, preferred examples of the monocyclic heterocyclic group or the condensed heterocyclic group include tetrazole, triazole, thiazole, thiadiazole, imidazole, quinoline, furan, thiophene, oxazole, and oxadi. Azole, pyrrole, pyrazole, pyrazine, isothiazole, isoxazole, pyrazolidine, pyrimidine, pyridazine, pyrrolidine, indolizine, indole, isoindole, indazole, purine, isoquinoline, naphthyridine, quinoxaline, carbazole, phenanthroline, phenazine, phenothiazine, phenothiazine, Phenoxazine, phenanthridine, pyrroline, imidazolidine, pyrazoline, imidazoline, piperidine, piperazine, indoline, thianthrene 4 reference), more preferably tetrazole, triazole, thiazole, thiadiazole, thiophene, pyridine, imidazole, quinoline, phenanthroline, imidazolidine, imidazoline, piperidine.

The tin-silver alloy plating bath of the present invention 3 contains (A) a mixture of a soluble stannous salt and a soluble silver salt, (B) an acid, and (C) a sulfur-containing compound.
Among the components (A), the soluble salts of silver include silver acetate, silver nitrate, silver chloride, silver oxide, silver cyanide, potassium silver cyanide, silver methanesulfonate, silver 2-hydroxyethanesulfonate, 2-hydroxy Examples thereof include silver propane sulfonate.
The acid of component (B) is the same as that of the present invention 1.
The sulfur-containing compound of component (C) excludes the pyridine ring group in addition to the benzoazole ring group from the heterocyclic group, and the mercapto group bonded adjacent to the heterocyclic group excludes the sulfide group Except for the point which is done, it is basically the same as the present invention 1.
Accordingly, a sulfur-containing compound in which a benzoazole ring group and a mercapto group are bonded, such as 2-mercaptobenzothiazole, a sulfur-containing compound in which a pyridine ring group and a mercapto group are bonded, such as mercaptopyridine, or triazole sulfide, diimidazole disulfide, etc. The tin-copper alloy bath to which the sulfur-containing compound in which the monocyclic heterocyclic group and sulfide group are bonded is excluded from the tin-silver alloy plating bath of the third invention.
In the case of the tin-silver alloy bath of the present invention 3, preferred examples of the monocyclic heterocyclic group or the condensed heterocyclic group include tetrazole, triazole, thiazole, thiadiazole, imidazole, quinoline, furan, morpholine, thiophene, oxazole, oxa Diazole, pyrrole, pyrazole, pyrazine, isothiazole, isoxazole, pyrazolidine, pyrimidine, pyridazine, pyrrolidine, indolizine, indole, isoindole, indazole, purine, isoquinoline, naphthyridine, quinoxaline, carbazole, phenanthroline, phenazine, phenothiazine, phenothiazine Phenoxazine, phenanthridine, pyrroline, imidazolidine, pyrazoline, imidazoline, piperidine, piperazine, indoline, thianthrene Referring present invention 4), more preferably tetrazole, triazole, thiazole, thiadiazole, thiophene, pyridine, imidazole, quinoline, phenanthroline, imidazolidine, imidazoline, piperidine.

The present invention 1 to 3 can be applied to tin or tin alloy plating baths in any pH range such as acidic and neutral (including weakly acidic).
Basically, stannous ions are stable when acidic, but white precipitates are likely to occur near neutrality. For this reason, when applying this invention to the tin plating bath near neutrality, it is preferable to contain a complexing agent for the purpose of stabilizing tin ions.
Examples of the complexing agent include oxycarboxylic acid, polycarboxylic acid, and monocarboxylic acid. Specifically, gluconic acid, citric acid, glucoheptonic acid, gluconolactone, glucoheptlactone, formic acid, acetic acid, propionic acid , Butyric acid, ascorbic acid, oxalic acid, malonic acid, succinic acid, glycolic acid, malic acid, tartaric acid, diglycolic acid, or salts thereof. Preferably, gluconic acid, citric acid, glucoheptonic acid, gluconolactone, glucoheptlactone, or a salt thereof.
In addition, ethylenediamine, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), iminodipropionic acid (IDP), hydroxyethylethylenediaminetriacetic acid (HEDTA), triethylene Tetramine hexaacetic acid (TTHA), ethylenedioxybis (ethylamine) -N, N, N ', N'-tetraacetic acid, glycines, nitrilotrimethylphosphonic acid, 1-hydroxyethane-1,1-diphosphonic acid, or these Polyamines such as these salts and aminocarboxylic acids are also effective as complexing agents.

In addition, in the tin alloy plating baths of the present invention 1 to 3, since the partner electrode silver, copper, bismuth, etc. that form an alloy with tin has a higher electrode potential than tin, these various ions are stable in the bath. From the viewpoint of co-depositing with tin, it is preferable to add a stabilizer as appropriate.
The stabilizer includes thiourea, or thioamides such as thiourea derivatives such as dimethylurea, dimethylthiourea, trimethylthiourea, diethylthiourea, allylthiourea, acetylthiourea, thiosemicarbazide, thioglycol (HS-CH2CH2OH), thioglycolic acid (HSCH2COOH), mercaptopropionic acid (CH3CH (SH) COOH), mercaptans such as mercaptosuccinic acid, thiodiglycol (HOCH2CH2-S-CH2CH2OH), thiobis (dodecaethylene glycol) (H- (OCH2CH2) 12-S- (CH2CH2O) 12-H), thiodiglycolic acid (HOOCCH2-S-CH2COOH), dithiodianiline, dipyridyl disulfide, 3,6-dithio-1,8-octanediol, 4,7-dithio- Examples thereof include sulfides such as 1,10-decanediol, or sulfites.
Furthermore, the oxycarboxylic acids, polycarboxylic acids or salts thereof listed as the complexing agent, polyamines, aminocarboxylic acids and the like are also effective.

In addition to the complexing agents and stabilizers, the tin and tin alloy plating baths of the present invention 1 to 3 include an antioxidant, a surfactant, a smoothing agent, a brightening agent, a semi-glossing agent, and a pH adjusting agent. Various additives such as conductive salts, preservatives and antifoaming agents can be contained.
The above-mentioned antioxidant is for the purpose of preventing the oxidation of Sn2 + in the bath. Ascorbic acid or a salt thereof, hydroquinone, catechol, resorcin, hydroquinone, phloroglucin, cresolsulfonic acid or a salt thereof, phenolsulfonic acid or a salt thereof, catechol Examples include sulfonic acid or a salt thereof, hydroquinone sulfonic acid or a salt thereof, hydroxynaphthalene sulfonic acid or a salt thereof, and hydrazine. For example, in a neutral bath, ascorbic acid or a salt thereof is preferable.
For the purpose of improving the appearance, denseness, smoothness, adhesion and the like of the plating film, various surfactants such as ordinary anionic, cationic, nonionic or amphoteric surfactants can be used.
Examples of the anionic surfactant include alkyl sulfates, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl phenyl ether sulfates, alkyl benzene sulfonates, and alkyl naphthalene sulfonates. Examples of the cationic surfactant include mono-trialkylamine salts, dimethyldialkylammonium salts, and trimethylalkylammonium salts. Nonionic surfactants include C1-C20 alkanols, phenols, naphthols, bisphenols, C1-C25 alkylphenols, arylalkylphenols, C1-C25 alkylnaphthols, C1-C25 alkoxyl phosphates (salts), sorbitan esters, polyalkylene glycols. , C1-C22 aliphatic amides and the like obtained by addition condensation of 2-300 moles of ethylene oxide (EO) and / or propylene oxide (PO). Examples of amphoteric surfactants include carboxybetaine, imidazoline betaine, and aminocarboxylic acid.

Examples of the smoothing agent include β-naphthol, β-naphthol-6-sulfonic acid, β-naphthalenesulfonic acid, 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, propi Onaldehyde, n-valeraldehyde, acrolein, crotonaldehyde, glyoxal, aldol, succindialdehyde, capronaldehyde, isovaleraldehyde, allylaldehyde, glutaraldehyde, 1-benzylidene-7-heptanal, 2,4-hexadienal, Cinnamaldehyde, benzylcrotonaldehyde, amine-aldehyde condensate, mesityl oxide, isophorone, diacetyl, hexanedione-3,4, acetylacetone, 3-chlorobenzylideneacetone, sub.pyridylideneacetone, sub.furfuridineacetone, sub. Tenylideneacetone, 4- (1-naphthyl) -3-buten-2-one, 4- (2-furyl) -3-buten-2-one, 4- (2-thiophenyl) -3-butene-2- On, Kurkumi 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-triazine 1,3,5-triazine, 1,2,3-benztriazine, imidazole, 2-vinylpyridine, indole, quinoline, reaction product of monoethanolamine and o-vanillin, polyvinyl alcohol, catechol, hydroquinone, resorcin, polyethylene Examples include imine, disodium ethylenediaminetetraacetate, and polyvinylpyrrolidone.
Gelatin, polypeptone, N- (3-hydroxybutylidene) -p-sulfanilic acid, N-butylidenesulfanilic acid, N-cinnamoylidenesulfanilic 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, or benzothiazoles are also effective as a smoothing agent.
Examples of the benzothiazoles include benzothiazole, 2-methylbenzothiazole, 2-mercaptobenzothiazole, 2- (methylmercapto) benzothiazole, 2-aminobenzothiazole, 2-amino-6-methoxybenzothiazole, and 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.

  As the above-mentioned brightener or semi-brightener, there are some overlaps with the above-mentioned smoothing agent, but benzaldehyde, o-chlorobenzaldehyde, 2,4,6-trichlorobenzaldehyde, m-chlorobenzaldehyde, p-nitrobenzaldehyde, p-hydroxy. Benzaldehyde, furfural, 1-naphthaldehyde, 2-naphthaldehyde, 2-hydroxy-1-naphthaldehyde, 3-acenaphthaldehyde, benzylideneacetone, pyridideneacetone, furfurylideneacetone, cinnamaldehyde, anisaldehyde, salicylaldehyde, Various aldehydes such as crotonaldehyde, acrolein, glutaraldehyde, paraaldehyde, vanillin, triazine, imidazole, indole, quinoline, 2-vinylpyridine, aniline, phena Toroline, neocuproine, picolinic acid, thioureas, N- (3-hydroxybutylidene) -p-sulfanilic acid, N-butylidenesulfanilic acid, N-cinnamoylidenesulfanilic 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, or benzothiazole, 2-methylbenzothiazole, 2- Aminobenzothiazole, 2-amino-6-methoxybenzothiazole, 2-methyl-5-chlorobenzothiazole, 2-hydroxybenzothiazole, 2-amino-6-methylben Thiazole, 2-chloro-benzothiazole, 2,5-dimethyl benzothiazole, benzothiazole such as 5-hydroxy-2-methyl-benzothiazole.

Examples of the pH adjuster include various acids such as hydrochloric acid and sulfuric acid, various bases such as aqueous ammonia, potassium hydroxide and sodium hydroxide, monocarboxylic acids such as formic acid, acetic acid and propionic acid, and boron. Dicarboxylic acids such as acids, phosphoric acids, oxalic acid and succinic acid, and oxycarboxylic acids such as lactic acid and tartaric acid are also effective.
Examples of the conductive salt include sodium salts such as sulfuric acid, hydrochloric acid, phosphoric acid, sulfamic acid, and sulfonic acid, potassium salts, magnesium salts, ammonium salts, and amine salts. is there.
Examples of the preservative include boric acid, 5-chloro-2-methyl-4-isothiazolin-3-one, benzalkonium chloride, phenol, phenol polyethoxylate, thymol, resorcin, isopropylamine, and guaiacol.
Examples of the antifoaming agent include pluronic surfactants, higher aliphatic alcohols, acetylene alcohols and polyalkoxylates thereof.

The present invention 6 is a tin and tin alloy plating method for forming an electrodeposition film of tin or a tin alloy on an electronic component using the tin or tin alloy plating bath according to any one of the present inventions 1 to 5, and the present invention. 7 is an electronic component in which a tin or tin alloy electrodeposition film is formed by the plating method.
Examples of the electronic component include a printed wiring board, a glass substrate, a silicon substrate, a semiconductor integrated circuit, a resistor, a variable resistor, a capacitor, a filter, an inductor, a thermistor, a crystal resonator, a switch, a lead wire, and a solar cell.
In the electroplating using the tin or tin alloy plating bath of the present invention, various plating methods such as barrel plating, rack plating, high-speed continuous plating, rackless plating, cup plating, and dip plating can be employed.
As electroplating conditions, the bath temperature is 0 ° C. or higher, preferably about 10 to 50 ° C., and the cathode current density is 0.001 to 30 A / dm 2, preferably 0.01 to 10 A / dm 2.

Examples of tin and tin alloy plating baths of the present invention, uniformity test examples of film thicknesses of the respective electrodeposition films obtained from the plating baths of the examples, and electrodepositions obtained from the tin alloy baths of the examples An example of the uniformity test of the alloy composition of the film and an example of the stability test of the plating film will be sequentially described.
The present invention is not limited to the following synthesis examples, examples, and test examples, and it goes without saying that arbitrary modifications can be made within the scope of the technical idea of the present invention.

<< Examples of tin and tin alloy plating bath >>
Among Examples 1 to 11, Examples 1 and 2 are examples of a tin plating bath, Example 3 is an example of a tin-gold alloy plating bath, Example 4 is an example of a tin-copper alloy plating bath, and Example 5 is tin. Example of zinc alloy plating bath, Example 6 is an example of tin-nickel alloy plating bath, Example 7 is an example of tin-bismuth alloy plating bath, Example 8 is an example of tin-cobalt alloy plating bath, Example 9 Is an example of a tin-indium alloy plating bath, Example 10 is an example of a tin-lead alloy plating bath, and Example 11 is an example of a tin-antimony alloy plating bath.
In Examples 1 to 11, Examples 1 to 2, 7 to 8 and 11 are examples of sulfides in which the sulfur-containing compound of the present invention has a heterocyclic group. Examples 3 to 6 and 9 to 10 are heterocyclic groups. Examples of mercaptans having

  On the other hand, Comparative Example 1 is an example containing a sulfur-containing compound different from the present invention based on Example 1, and Comparative Example 2 is a blank example based on Example 1 and not containing the sulfur-containing compound of the present invention. Comparative Example 3 is an example containing a sulfur-containing compound different from the present invention based on Example 3, and Comparative Example 4 is a blank example based on Example 3 and not containing the sulfur-containing compound of the present invention. Comparative Example 5 is an example containing a sulfur-containing compound different from the present invention based on Example 4, and Comparative Example 6 is a blank example not containing the sulfur-containing compound of the present invention. Comparative Example 7 is an example containing a sulfur-containing compound different from the present invention based on Example 5, and Example 8 is a blank example based on Example 5 and not containing the sulfur-containing compound of the present invention. Comparative Example 9 is an example containing a sulfur-containing compound different from the present invention based on Example 6, and Comparative Example 10 is a blank example based on Example 6 and not containing the sulfur-containing compound of the present invention. Comparative Example 11 is an example containing a sulfur-containing compound different from the present invention on the basis of Example 7, and Comparative Example 12 is a blank example based on Example 7 and not containing the sulfur-containing compound of the present invention. Comparative Example 13 is an example containing a sulfur-containing compound different from the present invention, and Comparative Example 14 is a blank example which is based on Example 8 and does not contain the sulfur-containing compound of the present invention. Comparative Example 15 is an example containing a sulfur-containing compound different from the present invention based on Example 9, and Comparative Example 16 is a blank example based on Example 9 and not containing the sulfur-containing compound of the present invention. Comparative Example 17 is an example containing a sulfur-containing compound different from the present invention based on Example 10, and Comparative Example 20 is a blank example based on Example 10 and not containing the sulfur-containing compound of the present invention.

(1) Example 1
A tin plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Sulfuric acid 125g / L
5,5′-dithiobis (1-phenyl-1H-tetrazole) 5 g / L
Bisphenol A polyethoxylate (EO13 mol) 5g / L
Sodium alkylnaphthalene sulfonate 3g / L
Catechol 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(2) Example 2
A tin plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 35g / L
Methanesulfonic acid 150g / L
4,4'-diimidazole disulfide 0.5 g / L
Pluronic surfactant 10g / L
2,2'-bipyridyl 0.03 g / L
Catechol 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 30 ° C

(3) Example 3
A tin-gold alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 10g / l
Sodium gold sulfite (as Au +) 2g / L
Sodium sulfite 80g / L
2-mercapto-1-methylimidazole 30 g / L
Tetronic surfactant 10g / L
β-naphthol polyethoxylate (EO12 mol) 3g / L
Hydroquinone 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(4) Example 4
A tin-copper alloy plating bath was constructed with the following composition.
Stannous propanesulfonate (as Sn2 +) 10g / L
Copper propanesulfonate (as Cu2 +) 35g / L
Propanesulfonic acid 120g / L
5-mercapto-1-methyltetrazole 2 g / L
Alkylglycine amphoteric surfactant 2.5g / L
Polyvinylpyrrolidone 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(5) Example 5
A tin-zinc alloy plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Zinc sulfate (as Zn2 +) 2g / L
Sulfuric acid 100g / L
(2-Mercapto-4-methylthiazol-5-yl) acetic acid 3.5 g / L
Dodecyl alcohol polyethoxylate (EO 15 mol) 5 g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 30 ° C

(6) Example 6
A tin-nickel alloy plating bath was constructed with the following composition.
Stannous sulfamate (as Sn2 +) 20g / L
Nickel sulfamate (as Ni2 +) 40g / L
Sulfamic acid 125g / L
Boric acid 30g / L
4-mercaptomorpholine 1g / L
Octylphenol polyethoxylate (EO10 mol) 5g / L
Catechol 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 50 ° C

(7) Example 7
A tin-bismuth alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 15g / L
Bismuth methanesulfonate (as Bi3 +) 40g / L
Methanesulfonic acid 100g / L
3,3′-dithiobis-1H-1,2,4-triazole 2 g / L
Styrenated polyethoxylate (EO10 mol) 5g / L
Hydroquinone 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(8) Example 8
A tin-cobalt alloy plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Cobalt sulfate (as Co2 +) 10g / L
Sulfuric acid 150g / L
2,2'-dithiodipyridine 10g / L
Bisphenol F polyethoxylate (EO15 mol) 10g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(9) Example 9
A tin-indium alloy plating bath was constructed with the following composition.
Stannous sulfamate (as Sn2 +) 50g / L
Indium sulfamate (as In3 +) 10g / L
Sulfamic acid 150g / L
4-mercaptoquinoline-3-sulfonic acid 4 g / L
Bisphenol A polyethoxylate (EO15 mol) 10g / L
Benzyltributylammonium hydroxide 2g / L
Polyethyleneimine 1g / L
Catechol 0.5g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(10) Example 10
A tin-lead alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 50g / L
Lead methanesulfonate (as Pb2 +) 40g / L
Methanesulfonic acid 150g / L
2-Methyl-3-furanthiol 0.3g / L
Cumylphenol polyethoxylate (EO20 mol) 10g / L
Tetronic surfactant 2g / L
Catechol 0.75g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(11) Example 11
A tin-antimony alloy plating bath was constructed with the following composition.
Stannous chloride (as Sn2 +) 50g / L
Antimony chloride (as Sb2 +) 50g / L
Sodium fluoride 40g / L
Acidic ammonium fluoride 20g / L
2,2'-dithienyl disulfide 5g / L
Styrenated phenol polyethoxylate (EO20 mol) 10g / L
Polyethylene glycol (molecular weight 4000) 10g / L
Imidazoline-based amphoteric surfactant 0.5g / L
Hydroquinone 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(12) Comparative Example 1
A tin plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Sulfuric acid 125g / L
Bis (3-sulfopropyl) disulfide 5g / L
Bisphenol A polyethoxylate (EO13 mol) 5g / L
Sodium alkylnaphthalene sulfonate 3g / L
Catechol 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(13) Comparative Example 2
A tin plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Sulfuric acid 125g / L
Bisphenol A polyethoxylate (EO13 mol) 5g / L
Sodium alkylnaphthalene sulfonate 3g / L
Catechol 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 30 ° C

(14) Comparative Example 3
A tin-gold alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 10g / l
Sodium gold sulfite (as Au +) 2g / L
Sodium sulfite 80g / L
DL-methionine 1.5 g / L
Tetronic surfactant 10g / L
β-naphthol polyethoxylate (EO12 mol) 3g / L
Hydroquinone 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(15) Comparative example 4
A tin-gold alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 10g / l
Sodium gold sulfite (as Au +) 2g / L
Sodium sulfite 80g / L
Tetronic surfactant 10g / L
β-naphthol polyethoxylate (EO12 mol) 3g / L
Hydroquinone 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(16) Comparative Example 5
A tin-copper alloy plating bath was constructed with the following composition.
Stannous propanesulfonate (as Sn2 +) 10g / L
Copper propanesulfonate (as Cu2 +) 35g / L
Propanesulfonic acid 120g / L
Thiourea 3g / L
Alkylglycine amphoteric surfactant 2.5g / L
Polyvinylpyrrolidone 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(17) Comparative Example 6
A tin-copper alloy plating bath was constructed with the following composition.
Stannous propanesulfonate (as Sn2 +) 10g / L
Copper propanesulfonate (as Cu2 +) 35g / L
Propanesulfonic acid 120g / L
Alkylglycine amphoteric surfactant 2.5g / L
Polyvinylpyrrolidone 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(18) Comparative Example 7
A tin-zinc alloy plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Zinc sulfate (as Zn2 +) 2g / L
Sulfuric acid 100g / L
3-mercapto-1-propanesulfonic acid 5.0 g / L
Dodecyl alcohol polyethoxylate (EO15 mol) 5g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 35 ° C

(19) Comparative Example 8
A tin-zinc alloy plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Zinc sulfate (as Zn2 +) 2g / L
Sulfuric acid 100g / L
Dodecyl alcohol polyethoxylate (EO15 mol) 5g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 35 ° C

(20) Comparative Example 9
A tin-nickel alloy plating bath was constructed with the following composition.
Stannous sulfamate (as Sn2 +) 20g / L
Nickel sulfamate (as Ni2 +) 40g / L
Sulfamic acid 125g / L
Boric acid 30g / L
4,4-thiodiphenol 1g / L
Octylphenol polyethoxylate (EO 10 mol) 5 g / L
Catechol 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 50 ° C

(21) Comparative Example 10
A tin-nickel alloy plating bath was constructed with the following composition.
Stannous sulfamate (as Sn2 +) 20g / L
Nickel sulfamate (as Ni2 +) 40g / L
Sulfamic acid 125g / L
Boric acid 30g / L
Octylphenol polyethoxylate (EO10 mol) 5g / L
Catechol 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 50 ° C

(22) Comparative Example 11
A tin-bismuth alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 15g / L
Bismuth methanesulfonate (as Bi3 +) 40g / L
Methanesulfonic acid 100g / L
3,3'-dithiobis-propanesulfonic acid disodium salt 4.5 g / L
Styrenated polyethoxylate (EO10 mol) 5g / L
Hydroquinone 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(23) Comparative Example 12
A tin-bismuth alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 15g / L
Bismuth methanesulfonate (as Bi3 +) 40g / L
Methanesulfonic acid 100g / L
Styrenated polyethoxylate (EO 10mol) 5g / L
Hydroquinone 3g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(24) Comparative Example 13
A tin-cobalt alloy plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Cobalt sulfate (as Co2 +) 10g / L
Sulfuric acid 150g / L
Dithiodianiline 10g / L
Bisphenol F polyethoxylate (EO15 mol) 10g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(25) Comparative Example 14
A tin-cobalt alloy plating bath was constructed with the following composition.
Stannous sulfate (as Sn2 +) 50g / L
Cobalt sulfate (as Co2 +) 10g / L
Sulfuric acid 150g / L
Bisphenol F polyethoxylate (EO15 mol) 10g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(26) Comparative Example 15
A tin-indium alloy plating bath was constructed with the following composition.
Stannous sulfamate (as Sn2 +) 50g / L
Indium sulfamate (as In3 +) 10g / L
Sulfamic acid 150g / L
Imidazole 10g / L
Bisphenol A polyethoxylate (EO15 mol) 10g / L
Benzyltributylammonium hydroxide 2g / L
Polyethyleneimine 1g / L
Catechol 0.5g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(27) Comparative Example 16
A tin-indium alloy plating bath was constructed with the following composition.
Stannous sulfamate (as Sn2 +) 50g / L
Indium sulfamate (as In3 +) 10g / L
Sulfamic acid 150g / L
Bisphenol A polyethoxylate (EO15 mol) 10g / L
Benzyltributylammonium hydroxide 2g / L
Polyethyleneimine 1g / L
Catechol 0.5g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(28) Comparative Example 17
A tin-lead alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 50g / L
Lead methanesulfonate (as Pb2 +) 40g / L
Methanesulfonic acid 150g / L
Taurine 20g / L
Cumylphenol polyethoxylate (EO20 mol) 10g / L
Tetronic surfactant 2g / L
Catechol 0.75g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(29) Comparative Example 18
A tin-lead alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn2 +) 50g / L
Lead methanesulfonate (as Pb2 +) 40g / L
Methanesulfonic acid 150g / L
Cumylphenol polyethoxylate (EO20 mol) 10g / L
Tetronic surfactant 2g / L
Catechol 0.75g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(30) Comparative Example 19
A tin-antimony alloy plating bath was constructed with the following composition.
Stannous chloride (as Sn2 +) 50g / L
Antimony chloride (as Sb2 +) 50g / L
Sodium fluoride 40g / L
Acidic ammonium fluoride 20g / L
2-Aminoethanethiol 2.5 g / L
Styrenated phenol polyethoxylate (EO20 mol) 10g / L
Polyethylene glycol (molecular weight 4000) 10g / L
Imidazoline-based amphoteric surfactant 0.5g / L
Hydroquinone 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(31) Comparative Example 20
A tin-antimony alloy plating bath was constructed with the following composition.
Stannous chloride (as Sn2 +) 50g / L
Antimony chloride (as Sb2 +) 50g / L
Sodium fluoride 40g / L
Acidic ammonium fluoride 20g / L
2,2'-dithienyl disulfide 5g / L
Styrenated phenol polyethoxylate (EO20 mol) 10g / L
Polyethylene glycol (molecular weight 4000) 10g / L
Imidazoline-based amphoteric surfactant 0.5g / L
Hydroquinone 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

Therefore, electroplating was performed using each of the tin or tin alloy plating baths of Examples 1 to 11 and Comparative Examples 1 to 20, and the obtained electrodeposition coatings were uniform in plating film thickness and alloy composition. Alternatively, an evaluation test of the stability of the plating film was performed.
<< Example of uniformity of plating film thickness test >>
Electroplating is performed on a flat steel plate of 25 mm x 25 mm square under the conditions of a cathode current density of 3 A / dm2 and a plating time of 30 minutes, and the film thickness at 10 selected points is measured by appropriately varying the entire surface of the obtained plating film. Of these 10 measured values, the fluctuation rate Qa (%) expressed by the following equation is calculated from the maximum film thickness La, the minimum film thickness Sa, and the average film thickness Ta, and the film thickness is calculated according to the following criteria. The superiority or inferiority of the uniformity was evaluated.
Qa = [(La−Sa) / Ta] × 100
[Evaluation criteria]
◯: The fluctuation rate Qa is 20% or less.
X: Fluctuation rate Qa is larger than 20%.

<Example of uniformity test of alloy composition of plating film>
Electroplated tin alloy was plated on a 25 mm x 25 mm square flat steel plate under the conditions of a cathode current density of 3 A / dm2 and a plating time of 30 minutes. Of these 10 measured values, the variation rate Qb (%) represented by the following formula is calculated from the maximum composition Lb, the minimum composition Sb, and the average composition Tb of the counterpart metal of tin. Then, the superiority or inferiority of the uniformity of the alloy composition was evaluated.
Qb = [(Lb−Sb) / Tb] × 100
[Evaluation criteria]
O: The fluctuation rate Qb is 20% or less.
X: Fluctuation rate Qb is greater than 20%.

<< Example of stability test of plating film >>
Each plating solution component has a concentration of 0.8 and 1.2 times, and the plating film thickness or tin alloy composition obtained by using each plating solution is 1.0 times the plating solution. When the composition was used, the film thickness and the alloy composition were examined for differences, and the superiority or inferiority of the stability of the plating film was evaluated according to the following criteria.
[Evaluation criteria]
◯: The difference was within ± 15%, indicating good stability.
X: The difference exceeded ± 15%, and the stability was low.

The table below shows the results of the above tests.
Plating bath type Film thickness uniformity Alloy composition uniformity Stability Example 1 Sn ○--○ Example 2 Sn ○--○ Example 3 Sn-Au ○ ○ ○ Example 4 Sn-Cu ○ ○ ○ Example 5 Sn-Zn O O O Example 6 Sn-Ni O O O Example 7 Sn-Bi O O O Example 8 Sn-Co O O O Example 9 Sn-In O O O Example 10 Sn-Pb O O Example 11 Sn-Sb ○ ○ ○ Comparative Example 1 Sn × −− ○ Comparative Example 2 Sn × −− ○ Comparative Example 3 Sn—Au × ○ ○ Comparative Example 4 Sn—Au × × ×
Comparative Example 5 Sn—Cu ○ × ×
Comparative Example 6 Sn—Cu × × ○ Comparative Example 7 Sn—Zn × × ○ Comparative Example 8 Sn—Zn × ○ ○ Comparative Example 9 Sn—Ni × × ○ Comparative Example 10 Sn—Ni × × ×
Comparative Example 11 Sn-Bi × ○ ×
Comparative Example 12 Sn-Bi ○ × ×
Comparative Example 13 Sn—Co ○ × ○ Comparative Example 14 Sn—Co ○ × ×
Comparative Example 15 Sn-In ○ ○ ×
Comparative Example 16 Sn-In No No No
Comparative Example 17 Sn-Pb Yes No Yes Comparative Example 18 Sn-Pb Yes No Yes Comparative Example 19 Sn-Sb No Yes Yes Comparative Example 20 Sn-Sb No No Yes

<< Comprehensive evaluation based on test results of uniformity and stability of plating film >>
According to the above table, Comparative Example 4 (tin-gold alloy bath), Comparative Example 10 (tin-nickel alloy bath) and Comparative Example 16 (tin-indium alloy bath) which are blank examples not containing the sulfur-containing compound of the present invention. In the three test items of plating film thickness, uniformity of alloy composition, and stability, it was inferior. Similarly, Comparative Example 6 (tin-copper alloy bath) of the blank example and Comparative Example 12 (tin-bismuth alloy bath) ), Comparative Example 14 (tin-cobalt alloy bath) and Comparative Example 20 (tin-antimony alloy bath), two of the three test items were inferior. Moreover, the uniformity of film thickness is inferior in Comparative Example 2 (tin bath) of the blank example, and the remaining blank examples (Comparative Example 8 (tin-zinc alloy bath), Comparative Example 18 (tin-lead alloy bath)), etc. ) But one of the three test items was inferior.
On the other hand, in Examples 1 to 11 in which the sulfur-containing compound of the present invention was added to a tin bath or a specific tin alloy bath, all three test items showed good results, and a monocyclic heterocyclic group or a condensed group was obtained. When the sulfur-containing compound of the present invention having a sulfide group or mercapto group bonded adjacent to the heterocyclic group is added to the tin bath or tin alloy bath, not only the uniformity of the plating film thickness but also the uniformity of the alloy composition can be obtained. It was also confirmed that these film thicknesses and alloy compositions can be stably maintained even when the component concentration of the plating bath changes.

On the other hand, in Comparative Example 1 in which a sulfur-containing compound (aliphatic sulfide) different from the present invention was added to the tin bath, the stability of the plating film was good, but the film thickness was inferior. . Similarly, Comparative Example 3 in which aliphatic sulfides were added to the tin-gold alloy bath or Comparative Example 19 in which the tin-antimony alloy bath was added also had poor film thickness uniformity. In Comparative Example 7 in which aliphatic mercaptans were added to the tin-zinc alloy bath instead of sulfides, both the uniformity of the film thickness and the uniformity of the alloy composition were inferior. In Comparative Example 5 in which thiourea was added to the tin-copper alloy bath, the uniformity of the alloy composition and the stability of the plating film were inferior.
In Comparative Example 9 in which aromatic sulfides were added to the tin-nickel alloy bath, the uniformity of the film thickness and the uniformity of the alloy composition were inferior. In Comparative Example 13 in which the same was added to the tin-cobalt alloy bath, the alloy composition was also reduced. The uniformity of was poor.
In Comparative Example 15 in which a sulfur-containing compound having a heterocyclic group different from the present invention was added to a tin-indium alloy bath, the stability of the plating film was inferior, and in Comparative Example 17 added to a tin-lead alloy bath, the alloy composition was inferior. It was inferior in uniformity.
On the other hand, in Examples 1 to 11 where the sulfur-containing compound of the present invention was added to a tin bath or a tin alloy bath, all three test items showed good results. Comparative examples of the sulfur-containing compounds of the present invention in which a sulfide group or a mercapto group is bonded adjacent to a specific heterocyclic group in terms of uniformity and stability of the plating film (an odd number such as Comparative Examples 3 and 5). The superiority to the compound of Example) was confirmed.

Claims (7)

(A) a soluble salt of any one of a stannous salt and a mixture of a salt of a metal selected from stannous salt and zinc, nickel, bismuth, cobalt, indium, antimony, gold, lead;
(B) an acid;
(C) a monocyclic heterocyclic group or a condensed heterocyclic group containing 1 to 5 atoms selected from nitrogen, sulfur and oxygen (excluding benzimidazole, benzothiazole and benzoxazole ring groups) A tin and tin alloy plating bath comprising a sulfur-containing compound having a sulfide group or a mercapto group bonded adjacent to the heterocyclic group. (A) a mixture of a soluble stannous salt and a soluble copper salt;
(B) an acid;
(C) Monocyclic heterocyclic group or condensed heterocyclic group containing 1 to 5 atoms selected from nitrogen, sulfur and oxygen (provided that pyridine, morpholine, benzimidazole, benzothiazole, benzoxazole ring group) And a sulfur-containing compound having a sulfide group or a mercapto group bonded adjacent to the heterocyclic group. (A) a mixture of a soluble stannous salt and a soluble silver salt,
(B) an acid;
(C) Monocyclic heterocyclic group or condensed heterocyclic group containing 1 to 5 atoms selected from nitrogen, sulfur and oxygen (excluding pyridine, benzimidazole, benzothiazole, benzoxazole ring group) And a sulfur-containing compound having a mercapto group bonded adjacent to the heterocyclic group.   The monocyclic heterocyclic group or condensed heterocyclic group provided in the sulfur-containing compound is tetrazole, triazole, thiazole, thiadiazole, imidazole, quinoline, furan, morpholine, thiophene, pyridine, oxazole, oxadiazole, pyrrole, pyrazole, Pyrazine, isothiazole, isoxazole, pyrazolidine, pyrimidine, pyridazine, pyrrolidine, indolizine, indole, isoindole, indazole, purine, isoquinoline, naphthyridine, quinoxaline, carbazole, phenanthroline, phenazine, phenothiazine, phenoxazine, phenanthridine, pyrroline , Imidazolidine, pyrazoline, imidazoline, piperidine, piperazine, indoline, or a heterocyclic group selected from thianthrene Tin and tin alloy plating bath according to any one of claims 1 to 3, wherein the door.   5. The composition according to claim 1, comprising at least one additive selected from a surfactant, an antioxidant, a brightener, a semi-brightener, a complexing agent, and a pH adjuster. The described tin and tin alloy plating bath.   A tin or tin alloy plating bath is formed on an electronic component using the tin or tin alloy plating bath according to claim 1.   An electronic component in which tin or a tin alloy film is formed by the plating method according to claim 6.