JP5150016B2 - Tin or tin alloy plating bath and barrel plating method using the plating bath - Google Patents

Description

  The present invention relates to a tin or tin alloy plating bath and a barrel plating method using the plating bath, improving the uniformity and smoothness of the plating film in a wide current density range, and imparting good film appearance and solder wettability. In addition, it is possible to provide a material capable of smoothly preventing aggregation of conductive media during barrel plating.

Tin plating, or tin alloy plating such as tin-silver alloy, tin-bismuth alloy, tin-lead alloy, etc. has good corrosion resistance and solder wettability. Widely used as industrial plating for parts. However, recently, the demand for lead-free plating of tin, tin-silver alloy, tin-bismuth alloy and the like is increasing due to the increase in environmental conservation.
However, in tin plating and tin alloy plating, the applicable current density range is narrow even when the film appearance is good, or the solder wettability is inferior even when the film appearance is good and the applicable current density range is wide. The actual situation is that there are various problems such as inability to make the film thickness of the electrodeposition film uniform in the plating operation.

Accordingly, a tin or tin alloy plating bath whose main purpose is to improve the film appearance and solder wettability (or solderability) is as follows. However, Patent Documents 1 to 3 are disclosed by the present applicant.
(1) Patent Document 1
It is described that by adding a benzothiazole compound such as 2-mercaptobenzothiazole (Example 10) to a tin or tin-lead alloy plating bath, a good plating film can be obtained with a uniform film thickness in a wide current density range. (2nd page upper left column, same page lower right column).

(2) Patent Document 2
A benzoazole sulfonic acid compound in which one of the monosulfide bonds is a benzoazole ring and the other is an alkylene sulfonic acid (salt) group (2-mercaptobenzimidazole-S-methanesulfonate, 2-mercaptobenzothiazole-S-propane It is described that by adding sulfonate, etc .; paragraph 17) to a tin or tin alloy plating bath, excellent film appearance and solderability can be imparted in a wide current density range (paragraphs 1, 5, 44). .

(3) Patent Document 3
A linear aliphatic hydrocarbon compound in which a specific alkylene oxide group or the like is present in the molecule or adjacent to both sides or one side of a mono- or disulfide bond, and a specific benzoazole compound (such as 2-mercaptobenzothiazole) ) Is added to a tin or tin-lead alloy plating bath to improve the film appearance and solder wettability in a wide pH range from acidic to alkaline.

In the above-mentioned Patent Document 1, improvement of the film appearance and solder wettability (or solderability) can be realized without much restraint by the current density. However, the compound of Patent Document 1 is difficult to dissolve in water or the mercapto group is oxidized. It is easy to receive, there is a possibility that it becomes a poorly soluble compound and does not exhibit its effect, and the same applies to Patent Document 3.
In addition, the compound of Patent Document 2 attempts to overcome the water solubility of the compound of Patent Document 1 by introducing a sulfonic acid group into the molecule.

  In general, electroplating using a tin or tin alloy bath includes various methods such as rack plating, barrel plating, and continuous high-speed plating. Among these, barrel plating is a chip resistor, a chip capacitor, and a quartz crystal cap. The advantage is that the maintenance is easy and the productivity is high in that the small parts such as are put in the barrel without being racked and plated.

Normally, in barrel plating, the objects to be plated are mixed with a spherical conductive medium (common name: dummy) made of steel, copper, brass or the like having a diameter of about 0.2 to 1 mm to improve the power supply. The electroplating is performed in a state where the particles are smoothly mixed. However, the conductive media are often aggregated during plating, and as a result, they are often gathered in a superimposed manner to grow into a larger lump.
When the conductive medium agglomerates into a lump, the object to be plated of small parts is taken into this, causing poor plating due to insufficient power supply, or when screening the object to be plated and the conductive medium, There is a problem that the lump does not pass through the sieve, and it takes time to sort the object to be plated from the conductive medium.
In addition, when barrel plating is performed only on an object to be plated without using a conductive medium, the objects to be plated are not likely to agglomerate with each other, which may result in poor plating and a decrease in productivity.

  The present applicant previously described in Patent Document 4 by adding specific metal ions such as bismuth, indium, and zinc to a tin plating bath at a predetermined trace concentration, so that the conductive medium and the objects to be plated are subjected to barrel plating. A technique for smoothly preventing aggregation has been disclosed.

JP-A-4-28893 Japanese Patent Laid-Open No. 10-25595 JP 2001-254194 A JP 2003-201593 A

However, in the above-mentioned Patent Document 4, since different metals such as bismuth and indium are added to the plating bath from the viewpoint of preventing agglomeration between the dummy and the object to be plated, the metal co-deposits on the film and the mechanical properties of the film are obtained. May change.
Further, the compound of Patent Document 1 can obtain a good plating film with a uniform film thickness in a wide current density range, but has a poor function of preventing aggregation of dummy and objects to be plated during barrel plating. In addition to having good water-solubility, the compound of Literature 2 can provide good film appearance and solderability in a wide current density range, but it also has an insufficient function to prevent aggregation of dummy and the like during barrel plating. It is.

  The present invention aims to improve the uniformity and smoothness of the plating film over a wide current density range, improve the film appearance and solder wettability, and apply a tin or tin alloy plating bath to barrel plating. A technical problem is to smoothly carry out barrel plating by preventing aggregation of the dummy.

The present inventors refer to the compounds of Patent Documents 1 and 2 above, and when a compound having a benzoazole ring is added to a tin or tin alloy plating bath, the uniformity of the obtained plating film, film appearance or We have intensively studied the effects on solder wettability, etc., and whether or not the dummy and the objects to be plated can be suppressed when the plating bath is applied to barrel plating.
As a result, dibenzoazole disulfide sulfonic acid compounds, each having a benzoazole ring with sulfonic acid groups bonded on both sides of the disulfide bond, are highly soluble in water and are not modified by oxidation, so they are added to tin or tin alloy plating baths. Then, the uniformity and smoothness of the plating film can be improved in a wide current density range, and the film appearance and solder wettability can be improved. Especially, when this plating bath is applied to barrel plating, aggregation of dummy etc. is prevented smoothly. We found what we could do and completed the present invention.

（式(1)中、ＸはＳ、Ｎ、Ｏである。；ｍ及びｎは０〜２の整数である。但し、ｍとｎが共に０になることはない。；ＲはＣ₁〜Ｃ₃アルキル、Ｃ₁〜Ｃ₃アルコキシ、ハロゲン、アミノ、ニトロ、カルボキシルである。；ａ及びｂは０〜２の整数である。；ＡはＨ、Ｎａ、Ｋである。）
含有することを特徴とするスズ又はスズ合金メッキ浴である。
That is, the present invention 1 includes (A) a stannous salt and a mixture of a stannous salt and a metal salt selected from the group consisting of silver, copper, bismuth, indium, zinc, antimony, nickel, and lead. A soluble salt comprising any of the following:
(B) an acid or a salt thereof;
(C) a dibenzoazole disulfide sulfonic acid compound represented by the following general formula (1):

(In Formula (1), X is S, N, and O; m and n are integers of 0 to 2, provided that m and n are not 0; R is C ₁ to C ₃ alkyl, C ₁ -C ₃ alkoxy, halogen, amino, nitro, carboxyl; a and b are integers from 0 to 2; A is H, Na, K.)
A tin or tin alloy plating bath characterized by containing.

  The present invention 2 is the same as the present invention 1, further selected from a complexing agent, a stabilizer, an antioxidant, a surfactant, a smoothing agent, a brightening agent, a semi-glossing agent, a conductive salt, a pH adjusting agent, and a buffering agent. It is a tin or tin alloy plating bath characterized by containing at least one kind of additive.

  The present invention 3 is a barrel plating method characterized by subjecting an object to be plated to barrel plating using the tin or tin alloy plating bath of the present invention 1 or 2.

  According to the present invention 4, in the present invention 3, the object to be plated is selected from a resistor, a variable resistor, a capacitor, a filter, an inductor, a thermistor, a crystal resonator, a switch, a lead wire, a printed circuit board, a semiconductor integrated circuit, and a module. It is a barrel plating method characterized by being an electronic component.

(1) When the plating bath of the present invention is applied to electroplating, the uniformity and smoothness of the plating film can be improved in a wide electric density range.
Regardless of the electroless or electroless plating method, the obtained plating film is excellent in appearance and solder wettability.
In the compound of Patent Document 1, it is difficult to dissolve in water, or the mercapto group is susceptible to oxidation and may become a poorly soluble compound and may not exhibit the effect. However, in the compound of the present invention, sulfonic acid (salt) There is no such problem because it has a disulfide bond with the group.

(2) When the plating bath of the present invention is applied to barrel plating, it is possible to smoothly prevent the dummy and the objects to be plated from agglomerating and improve the productivity of barrel plating.
In Patent Document 4, since different metals such as bismuth and indium are added (dope) to the plating bath in order to prevent agglomeration between the dummy and the object to be plated, the metal co-deposits on the film and the mechanical properties of the film are increased. The compound of the present invention is a disulfide disulfonic acid compound having a benzoazole ring, and there is no eutectoid of dissimilar metals as in the above-mentioned document 4, which adversely affects the mechanical properties of the plating film. There is nothing.

The present invention first includes a dibenzoazole disulfide sulfonic acid compound having a benzoazole ring on both sides of a disulfide bond and having at least one sulfonic acid group bonded to at least one of the benzoazole rings on both sides. A tin plating bath, or a predetermined tin alloy plating bath such as a tin-silver alloy or a tin-bismuth alloy, and second, a plating method in which these plating baths are applied to barrel plating.
However, the first plating bath may be an electroplating bath or an electroless plating bath.

As described above, the dibenzoazole disulfide sulfonic acid compound of the present invention is represented by the general formula (1), and the atom X arranged at the 3-position of the benzoazole ring is sulfur, nitrogen or oxygen, in which sulfur is preferable. That is, when X is a sulfur atom, the benzoazole ring is a benzothiazole ring, and similarly, when nitrogen is a benzimidazole ring, when oxygen is a benzoxazole ring, a benzothiazole ring is preferable.
The numbers m and n of the sulfonic acid (salt) groups bonded to the benzoazole ring are 0 to 2, respectively, but neither m nor n is 0. That is, from the viewpoint of water solubility, one or more sulfonic acid (salt) groups need to be bonded to the right and left benzoazole rings. Generally, the more sulfonic acid (salt) groups, the more water soluble. The atom A of the sulfonic acid (salt) group (= SO ₃ A) is hydrogen, sodium or potassium, and is either in the form of sulfonic acid (free acid) or in the form of sodium or potassium salt of sulfonic acid. .
The substituent R bonded to each of the right and left benzoazole rings with a disulfide bond in between can be selected from the group consisting of C ₁ -C ₃ alkyl, C ₁ -C ₃ alkoxy, halogen, amino, nitro, carboxyl, In particular, C ₁ -C ₃ alkyl, C ₁ -C ₃ alkoxy, halogen, nitro, carboxyl are preferred. The substituent R may be the same or different in the left and right benzoazole rings.
The numbers a and b of the substituents R are 0 to 2 and may be unsubstituted (a = b = 0), or each benzoazole ring may have 1 to 2 substituents.

Examples of the dibenzoazole disulfide sulfonic acid compound of the present invention include dibenzothiazolyl disulfide disulfonic acid, dibenzothiazolyl disulfide trisulfonic acid, dibenzothiazolyl disulfide monosulfonic acid, dibenzooxazolyl disulfide disulfonic acid, dibenzimidazolyl disulfide Examples thereof include disulfonic acid, or a salt thereof, or an acid or a salt thereof having a substituent on the benzoazole ring.
More specific examples of such compounds include disodium dibenzothiazolyl disulfide disulfonate, trisodium dibenzothiazolyl disulfide trisulfonate, potassium dibenzothiazolyl disulfide monosulfonate, di (4-methylbenzothiazoli D) Disodium disulfide disulfonate, disodium di (6-chlorobenzothiazolyl) disulfide disulfonate, disodium di (6-methoxybenzothiazolyl) disulfide disulfonate, di (6-nitrobenzothiazolyl) Disodium disulfide disulfonate, di (6-methylbenzothiazolyl) disulfide trisulfonic acid, dibenzoxazolyl disulfide disodium disulfonate, di (6-methylbenzoxazolyl) disulfide disulfonate dina Potassium, di-benzimidazolyl disulfide disulfonic acid disodium, and di (6-methoxy-benzimidazolyl) disulfide disulfonic acid disodium is preferred.

The dibenzoazole disulfide sulfonic acid compound of the present invention can be used alone or in combination, and its content is suitably a small amount of 0.01 to 10 g / L, preferably 0.1 to 3 g / L with respect to the entire plating bath.
When the content is less than 0.01 g / L, the effect of improving the smoothness and uniformity of the plating film, the appearance of the film, and the solderability is not exhibited, and the effect of preventing aggregation is reduced during barrel plating. On the other hand, if the content is more than 10 g / L, the low current density part may become matte plating in electroplating.

The dibenzoazole disulfide sulfonic acid compound of the present invention is a method in which a dibenzoazole disulfide compound is reacted in the presence of concentrated sulfuric acid or fuming sulfuric acid at 70 to 180 ° C., preferably 100 to 140 ° C. for 5 to 60 hours. Can be produced by a conventional method.
Incidentally, the dibenzoazole disulfide compound (for example, dibenzothiazole disulfide compound) is commercially available.

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

In the predetermined tin alloy plating bath of the present invention, the soluble salt of the tin counterpart metal that forms the tin alloy will be described. For example, the soluble salt of silver includes silver acetate, silver nitrate, silver chloride, silver oxide, cyanide. Examples include silver, potassium potassium cyanide, silver methanesulfonate, silver 2-hydroxyethanesulfonate, and silver 2-hydroxypropanesulfonate.
The soluble salts of copper include copper sulfate, copper nitrate, copper carbonate, copper pyrophosphate, copper chloride, copper cyanide, copper borofluoride, copper sulfamate, copper methanesulfonate, copper 2-hydroxyethanesulfonate, 2- Examples include copper hydroxypropane sulfonate.
Soluble salts of bismuth include bismuth sulfate, bismuth gluconate, bismuth nitrate, bismuth oxide, bismuth carbonate, bismuth chloride, bismuth methanesulfonate, and bismuth 2-hydroxypropanesulfonate.
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.

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 tin and another metal according to the composition ratio of the desired tin alloy plating film.

The tin alloy of the present invention is an alloy of tin and at least one metal selected from the group consisting of silver, copper, bismuth, indium, zinc, antimony, nickel, lead, specifically, tin-silver, Tin-copper, tin-bismuth, tin-indium, tin-zinc, tin-antimony, tin-nickel, tin-lead alloys, tin-silver-copper, tin-bismuth-copper, tin- Includes alloys of three or more components such as zinc-nickel.
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, the bath base is an organic acid, an inorganic acid, or an alkali metal salt, alkaline earth metal salt, ammonium salt or amine salt 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, chemical formula C _n H _{2n + 1} SO ₃ H (for example, n = 1 to 11) In particular, methanesulfonic acid, ethanesulfonic acid, 1-propanesulfonic acid, 2-propanesulfonic acid, 1-butanesulfonic acid, 2-butanesulfonic acid, pentanesulfonic acid and the like can be used. Can be mentioned.

Examples of the alkanol sulfonic acid include chemical formula C _m H _{2m + 1} —CH (OH) —C _p H _2p —SO ₃ H (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 present invention 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.

Further, in the tin alloy plating bath of the present invention, there are more metals having a higher electrode potential than tin in the counterpart silver, copper, bismuth, etc. that form an alloy with tin. From the standpoint of co-deposition, it is preferable to add a stabilizer appropriately.
The stabilizer includes thiourea, or thioamides such as thiourea derivatives such as dimethylthiourea, trimethylthiourea, diethylthiourea, allylthiourea, acetylthiourea, thiosemicarbazide, thioglycol (HS-CH ₂ CH ₂ OH). , Thioglycolic acid (HSCH ₂ COOH), mercaptopropionic acid (CH ₃ CH (SH) COOH), mercaptans such as mercaptosuccinic acid, thiodiglycol (HOCH ₂ CH ₂ —S—CH ₂ CH ₂ OH), thiobis (Dodecaethylene glycol) (H— (OCH ₂ CH ₂ ) ₁₂ —S— (CH ₂ CH ₂ O) ₁₂ —H), thiodiglycolic acid (HOOCCH ₂ —S—CH ₂ COOH), dithiodianiline, dipyridyl Disulfide, 3,6-dithio-1,8-octanediol, 4,7-dithio-1, Examples thereof include sulfides such as 10-decanediol, and 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 above complexing agents and stabilizers, the tin plating bath of the present invention includes an antioxidant, a surfactant, a smoothing agent, a brightening agent, a semi-brightening agent, a pH adjusting agent, a conductive salt, a preservative. Various additives such as an antifoaming agent can be contained.
The above-mentioned antioxidant is for the purpose of preventing the oxidation of Sn ^{2+ 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 Catecholsulfonic acid or a salt thereof, hydroquinonesulfonic acid or a salt thereof, hydroxynaphthalenesulfonic acid or a salt thereof, hydrazine and the like. 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. Examples of the nonionic surfactant, 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 alkoxyl phosphoric acid (salt ), Sorbitan ester, polyalkylene glycol, C ₁ -C ₂₂ aliphatic amide and the like, and 2-300 mol addition-condensation 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.

As described above, the tin or tin alloy plating bath of the present invention can be applied regardless of electroplating or electroless plating.
In electroplating, various plating methods such as barrel plating, rack plating, high-speed continuous plating, and rackless 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 .
The bath temperature in electroless plating is generally about 0 to 50 ° C. as in the above electroplating.

The present invention 3 is a method of barrel-plating an object to be plated using a tin or tin alloy plating bath containing the dibenzoazole disulfide sulfonic acid compound.
In the barrel plating, the object to be plated and the conductive medium are accommodated in the barrel, and the barrel is immersed in the tin plating bath to perform electroplating on the object to be plated, but the conductive medium is not used. Alternatively, a method may be used in which only the object to be plated is accommodated in the barrel for plating.
When the plating bath of the present invention is applied particularly to barrel plating among electroplating, there is an advantage that aggregation of conductive media can be prevented, which is also effective in preventing aggregation of small objects to be plated.
In the barrel plating, it is needless to say that any barrel plating apparatus such as a horizontal or inclined rotary barrel type, a swing barrel type, or a vibrating barrel type can be used.
The conditions of the bath temperature and cathode current density in barrel plating may be the same as the general conditions in the electroplating.
The present invention 4 is a resistor, variable resistor, capacitor, filter, inductor, thermistor, crystal resonator, switch, connector, lead wire, hoop material, printed circuit board, semiconductor integrated circuit (including TAB film carrier, BGA substrate, etc.) This is a barrel plating method in which electronic parts such as modules are to be plated. In particular, small parts such as a chip resistor, a chip capacitor, and a quartz resonator cap are suitable as the plated object.

Hereinafter, synthesis examples of the dibenzoazole disulfide disulfonic acid compound of the present invention, examples of the tin and tin alloy plating baths of the present invention containing the compound, and various current densities using the plating baths obtained in the examples. Evaluation test example of uniformity and smoothness of electrodeposited film when rack plating is applied, evaluation test example of solder wettability using each plating bath obtained in the above examples, and tin bath of the present invention were used A tin film appearance evaluation test example by electroless plating and an aggregation suppression evaluation test example when barrel plating is performed using the tin or tin alloy plating bath of the present invention 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.

First, as a representative example of the dibenzoazole disulfide disulfonic acid compound of the present invention, a synthesis example of dibenzothiazole disulfide disulfonate will be described.
<< Synthesis Example of Dibenzothiazole Disulfide Disulfonate >>
A 500 ml four-necked flask equipped with a thermometer, condenser and stirrer was charged with 94 ml of 30% fuming sulfuric acid. Thereafter, the mixture was cooled with ice water, and 100 g of dibenzothiazolyl disulfide was added at 20 ° C. with stirring.
Subsequently, it was rapidly heated to 115 ° C. and reacted for 24 hours. After the reaction, the mixture was cooled to 80 ° C., 200 ml of water was added, and an aqueous solution in which 145 g of sodium hydroxide was dissolved in 300 ml of water was added dropwise at 30 ° C. Further, 48% aqueous sodium hydroxide was added to adjust the pH to 9.5. After standing overnight, the sodium sulfate precipitated by suction filtration was separated by filtration to obtain 1550 ml of an aqueous solution of disodium dibenzothiazolyl disulfide disulfonate.

<< Examples of tin and tin alloy plating bath >>
Examples 1, 10, and 12 are examples of tin plating baths, Examples 2, 11, and 13 are examples of tin-silver alloy plating baths, Example 3 is an example of tin-copper alloy plating baths, and Example 4 is tin-bismuth. Example of alloy plating bath, Example 5 is an example of tin-indium alloy plating bath, Example 6 is an example of tin-zinc alloy plating bath, Example 7 is an example of tin-antimony alloy plating bath, Example 8 is tin An example of a lead alloy plating bath, Example 9 is an example of a tin-nickel alloy plating bath.
Examples 1 to 9 are examples in which the dibenzoazole disulfide sulfonic acid compound of the present invention is a benzothiazole disulfide sulfonic acid compound, examples 10 to 11 are examples of benzoxazole disulfide sulfonic acid compounds, and examples 12 to 13 are benz It is an example of an imidazole disulfide sulfonic acid compound.

(1) Example 1
A tin plating bath was constructed with the following composition.
Stannous isethionate (as Sn ²⁺ ) 20g / L
Sulfuric acid (specific gravity 1.84) 100g / L
Dodecylamine polyethoxylate (EO20) 10g / L
Catechol 0.5g / L
Dibenzothiazolyl disulfide disulphonate disodium salt 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 30 ° C

(2) Example 2
A tin-silver alloy plating bath was constructed with the following composition.
Stannous ethanesulfonate (as Sn ²⁺ ) 30g / L
Ethanesulfonic acid silver (as Ag ⁺ ) 0.8g / L
Ethanesulfonic acid (as free acid) 100g / L
Trimethylthiourea 16g / L
Distyrenated phenol polyethoxylate (EO20) 10g / L
Hydroquinone 1g / L
Dibenzothiazolyl disulfide trisulfonate trisodium salt 0.4 g / L
Potassium dibenzothiazolyl disulfide monosulfonate 0.8 g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(3) Example 3
A tin-copper alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 30g / L
Silver methanesulfonate (as Cu ²⁺ ) 3g / L
Methanesulfonic acid (as free acid) 130g / L
1-naphthol polyethoxylate (EO10) 10g / L
Benzalacetone 0.2g / L
Di (4-methylbenzothiazolyl) disulfide
-Disodium disulfonate 0.8g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(4) Example 4
A tin-bismuth alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 55g / L
Bismuth methanesulfonate (as Bi ³⁺ ) 7g / L
Methanesulfonic acid (as free acid) 130g / L
Tristyrenated phenol polyethoxylate (EO23) 10g / L
Di (6-chlorobenzothiazolyl) disulfide
-Disodium disulfonate 0.8g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(5) Example 5
A tin-indium alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 10g / L
Indium sulfamate (as In ³⁺ ) 10g / L
Sulfamic acid 130g / L
Aminocaproic acid 60g / L
Glycine 50g / L
Dimethyl alkyl betaine 5g / L
Hydroquinone 0.2g / L
Di (6-methoxybenzothiazolyl) disulfide
-Disodium disulphonate 1.2g / L
Ion-exchanged water balance pH (adjusted with ammonia) 2.0
[Plating temperature]
Bath temperature: 25 ° C

(6) Example 6
A tin-zinc alloy plating bath was constructed with the following composition.
Stannous sulfosuccinate (as Sn ²⁺ ) 56.4 g / L
Zinc methanesulfonate (as Zn ²⁺ ) 3.6g / L
Sulfosuccinic acid 100g / L
Ascorbic acid 2g / L
Bisphenol F polyethoxylate (EO12) 3g / L
Laurylamine polyethoxylate (EO15) 1g / L
Di (6-nitrobenzothiazolyl) disulfide
-Disodium disulphonate 0.5g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(7) Example 7
A tin-antimony alloy plating bath was constructed with the following composition.
Stannous sulfate (as Sn ²⁺ ) 25g / L
Antimony chloride (as Sb ³⁺ ) 0.87 g / L
Sulfuric acid 100g / L
Antimony fluoride 5g / L
Gelatin 0.5g / L
Phenol 5g / L
Di (6-methylbenzothiazolyl) disulfide trisulfonic acid 0.5 g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 45 ° C

(8) Example 8
A tin-lead alloy plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 50g / L
Lead methanesulfonate (as Pb ²⁺ ) 4.2g / L
Methanesulfonic acid (as free acid) 110g / L
1-naphthol polyethoxylate (EO10) 7g / L
Dibenzothiazolyl disulfide disulphonate disodium salt 0.5 g / L
Dibenzothiazolyl disulfide trisulfonic acid trisodium salt 0.3 g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(9) Example 9
A tin-nickel alloy plating bath was constructed with the following composition.
Stannous sulfate (as Sn ²⁺ ) 30g / L
Nickel sulfate (as Ni ²⁺ ) 0.75g / L
Sodium gluconate 220g / L
Thiobis (dodecaethylene glycol) 20g / L
Sodium sulfate 50g / L
Di (6-chlorobenzothiazolyl) disulfide
-Disodium disulphonate 0.3g / L
Ion-exchanged water balance pH (adjusted with sodium hydroxide) 4.0
[Plating temperature]
Bath temperature: 25 ° C

(10) Example 10
A tin plating bath was constructed with the following composition.
Stannous isethionate (as Sn ²⁺ ) 20g / L
Sulfuric acid (specific gravity 1.84) 100g / L
Dodecylamine polyethoxylate (EO20) 10g / L
Catechol 0.5g / L
Dibenzoxazolyl disulfide disulphonate disodium salt 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 30 ° C

(11) Example 11
A tin-silver alloy plating bath was constructed with the following composition.
Stannous ethanesulfonate (as Sn ²⁺ ) 30g / L
Ethanesulfonic acid silver (as Ag ⁺ ) 0.8g / L
Ethanesulfonic acid (as free acid) 100g / L
Trimethylthiourea 16g / L
Distyrenated phenol polyethoxylate (EO20) 10g / L
Hydroquinone 1g / L
Di (6-methylbenzoxazolyl) disulfide
-Disodium disulfonate 0.8g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(12) Example 12
A tin plating bath was constructed with the following composition.
Stannous isethionate (as Sn ²⁺ ) 20g / L
Sulfuric acid (specific gravity 1.84) 100g / L
Dodecylamine polyethoxylate (EO20) 10g / L
Catechol 0.5g / L
Dibenzimidazolyl disulfide disulphonate disodium salt 1g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 30 ° C

(13) Example 13
A tin-silver alloy plating bath was constructed with the following composition.
Stannous ethanesulfonate (as Sn ²⁺ ) 30g / L
Ethanesulfonic acid silver (as Ag ⁺ ) 0.8g / L
Ethanesulfonic acid (as free acid) 100g / L
Trimethylthiourea 16g / L
Distyrenated phenol polyethoxylate (EO20) 10g / L
Hydroquinone 1g / L
Di (6-methoxybenzimidazolyl) disulfide
-Disodium disulfonate 0.8g / L
Ion exchange water balance
[Plating temperature]
Bath temperature: 25 ° C

(14) Comparative Example 1
Based on the plating bath of Example 1, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed in the same manner as in Example 1 to obtain a tin plating bath of Comparative Example 1. In addition, bath temperature conditions are also the same as Example 1 (The bath temperature conditions are the same as the corresponding Example also in the comparative examples 2-13 mentioned later).

(15) Comparative example 2
Based on the plating bath of Example 2, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 2, and the tin-silver alloy plating bath of Comparative Example 2 was used. It was.

(16) Comparative Example 3
Based on the plating bath of Example 3, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 3, and the tin-copper alloy plating bath of Comparative Example 3 was used. It was.

(17) Comparative example 4
Based on the plating bath of Example 4, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 4, and the tin-bismuth alloy plating bath of Comparative Example 4 was used. It was.

(18) Comparative Example 5
Based on the plating bath of Example 5, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 5, and the tin-indium alloy plating bath of Comparative Example 5 was used. It was.

(19) Comparative Example 6
Based on the plating bath of Example 6, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 6, and the tin-zinc alloy plating bath of Comparative Example 6 was used. It was.

(20) Comparative Example 7
Based on the plating bath of Example 7, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 7, and the tin-antimony alloy plating bath of Comparative Example 7 was used. It was.

(21) Comparative Example 8
Based on the plating bath of Example 8, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 8, and the tin-lead alloy plating bath of Comparative Example 8 was used. It was.

(22) Comparative Example 9
Based on the plating bath of Example 9, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 9, and the tin-nickel alloy plating bath of Comparative Example 9 was used. It was.

(23) Comparative Example 10
Based on the plating bath of Example 10, the benzoxazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed in the same manner as in Example 10 to obtain a tin plating bath of Comparative Example 10.

(24) Comparative Example 11
Based on the plating bath of Example 11, the benzoxazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 11, and the tin-silver alloy plating bath of Comparative Example 11 was used. It was.

(25) Comparative Example 12
Based on the plating bath of Example 12, the benzimidazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed in the same manner as in Example 12 to obtain a tin plating bath of Comparative Example 12.

(26) Comparative Example 13
Based on the plating bath of Example 13, the benzimidazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 13, and the tin-silver alloy plating bath of Comparative Example 13 was used. It was.

Therefore, rack plating is performed using the tin or tin alloy plating baths obtained in Examples 1 to 13 and Comparative Examples 1 to 13 under the following current density ranges and conditions, and the electrodeposition film at each current density is applied. The superiority and inferiority of uniformity and smoothness were evaluated.
<< Evaluation Test Example 1 for Uniformity and Smoothness of Plating Film >>
That is, while stirring each of the plating baths with a stirrer, using platinum-coated titanium as an anode and a copper plate as a cathode, while varying the current density and plating time at the predetermined bath temperatures shown in the examples or comparative examples, Then, electroplating was performed by a rack method, and the state of the plating film at each current density was visually observed. The evaluation criteria are as follows.
A: A very smooth and uniform appearance was exhibited.
○: The film appearance was normal and showed a practical level appearance.
(Triangle | delta): The film particle was coarse and the external appearance which the uniformity and smoothness were a little inferior from a practical use level was shown.
X: Inferior smoothness, unevenness, and poor appearance.

The table below shows the test results.
No. Current density range of Hull cell test Example Comparative example 1 0.5 to 5 A / dm ² ◎ △
2 1-5 A / dm ² ◎ △
3 1-5A / dm ² ◎ ×
4 1-5 A / dm ² ◎ ×
5 5-15A / dm ² ◎ ×
6 2-10 A / dm ² ◎ ×
7 1-5A / dm ² ○ ×
8 1-20 A / dm ² ◎ △
9 0.1-3 A / dm ² ○ ×
10 0.5-5 A / dm ² ◎ △
11 1-5 A / dm ² ◎ △
12 0.5-5 A / dm ² ◎ △
13 1-5 A / dm ² ◎ △

Subsequently, using each tin or tin alloy plating bath obtained in Examples 1 to 13 and Comparative Examples 1 to 13, a plating film was formed on a predetermined copper plate, and the superiority or inferiority of solder wettability was evaluated.
<< Evaluation test example 2 of solder wettability of plating film >>
Using each plating bath of Examples and Comparative Examples on a test piece of a rolled copper plate of 25 mm × 25 mm, after performing tin or tin alloy plating at the predetermined bath temperature shown in each example and the current density shown in the table below, After immersing in a flux (25% rosin-containing isopropanol solution) for 5 seconds, then immersed in a molten solder bath maintained at 250 ° C. for 5 seconds and washed with isopropanol, the surface of the solder wettability was visually observed. The evaluation criteria of solder wettability are as follows.
A: Wet 95% or more.
○: Wet by 90% or more.
X: Wetting was less than 90%.

The table below shows the test results.
No. Cathode current density Example Comparative example 1 2 A / dm ²
2 3A / dm ² ◎ ×
3 3A / dm ² ◎ ×
4 3A / dm ² ◎ ×
5 7.5A / dm ² ◎ ×
6 5A / dm ² ○ ×
7 3A / dm ² ○ ×
8 10A / dm ² ◎ ×
9 0.25 A / dm ² ○ ×
10 0.5-5 A / dm ² ◎ ×
11 1-5 A / dm ² ○ ×
12 0.5-5A / dm ² ◎ ×
13 1-5 A / dm ² ○ ×

Next, as shown below, each of the electroless tin plating baths of Examples 14 to 15 and Comparative Examples 14 to 15 was constructed, and a tin plating film was formed on the inner lead of the TAB film carrier. Superiority or inferiority was evaluated.
<< External evaluation test example 3 of tin plating film >>
First, an electroless tin plating bath was constructed as follows.
[Example of plating bath]
(1) Example 14
An electroless tin plating bath was constructed with the following composition.
3-hydroxypropane
-1 stannous sulfonate (as Sn ²⁺ ) 0.25 mol / L
Ethanesulfonic acid 0.50 mol / L
Citric acid 0.50 mol / L
Thiourea 2.00 mol / L
Hypophosphorous acid 0.50 mol / L
1-naphthol polyethoxylate (EO10) 5.0 g / L
Dibenzothiazolyl disulfide disulphonate disodium salt 0.4 g / L

(2) Example 15
An electroless tin plating bath was constructed with the following composition.
3-hydroxypropane
-1 stannous sulfonate (as Sn ²⁺ ) 0.35 mol / L
3-hydroxypropane-1-propanesulfonic acid 1.00 mol / L
Malic acid 1.00 mol / L
Thiourea 1.50 mol / L
Hypophosphorous acid 0.10 mol / L
Palm oil fatty acid amidopropyldimethylamine oxide 6.0 g / L
Dibenzothiazolyl disulfide trisulfonate trisodium salt 0.6 g / L

(3) Comparative Example 14
Based on the plating bath of Example 14, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed in the same manner as in Example 14 to obtain an electroless tin plating bath of Comparative Example 14. .

(4) Comparative Example 15
Based on the plating bath of Example 15, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed in the same manner as in Example 15 to obtain an electroless tin plating bath of Comparative Example 15. .

[Evaluation test example]
Next, a TAB film carrier patterned with SLP (a kind of electrolytic copper foil) is used as an object to be plated, and the tin plating baths of Examples 14 to 15 and Comparative Examples 14 to 15 are placed on the inner leads of the film carrier. Then, electroless plating was performed under conditions of a bath temperature of 65 ° C. and a plating time of 5 minutes, and the deposited state of the obtained tin film was observed microscopically to evaluate the film appearance.
The evaluation criteria are as follows.
○: Abnormal particles were not recognized.
X: Abnormal particles were generated.

The table below shows the test results.
Appearance of tin plating film Example 14 ○
Example 15
Comparative Example 14 ×
Comparative Example 15 ×

Next, as described below, each tin or tin alloy plating bath of Examples 16 to 18 and Comparative Examples 16 to 18 containing the compound of the present invention was constructed, and barrel plating was performed using each of the electroplating baths. The superiority or inferiority of the degree of inhibition of aggregation of the conductive medium (dummy ball) was evaluated.
<< Aggregation suppression evaluation test example 4 in barrel plating >>
First, a tin or tin alloy plating bath was constructed as follows.
[Example of plating bath]
(1) Example 16
A tin-silver alloy plating bath was constructed with the following composition.
Stannous ethanesulfonate (as Sn ²⁺ ) 30g / L
Silver 2-propanol sulfonate (as Ag ⁺ ) 0.1 g / L
Isethonic acid (as free acid) 200g / L
Thiourea 3g / L
2-Naphthol polyethoxylate (EO10) 10g / L
Pluronic TR-720 1g / L
Dibenzothiazolyl disulfide disulphonate disodium salt 0.3g / L
Dibenzothiazolyl disulfide trisulfonate trisodium 0.2 g / L
Potassium dibenzothiazolyl disulfide monosulfonate 0.1 g / L
Ion-exchanged water balance The above Pluronic TR-720 is a commercial product manufactured by Asahi Denka Kogyo Co., Ltd.

(2) Example 17
A tin plating bath was constructed with the following composition.
Stannous ethanesulfonate (as Sn ²⁺ ) 15g / L
Isethonic acid (as free acid) 35g / L
Potassium gluconate 120g / L
Succinic acid 10g / L
Oleylamine polyethoxylate (EO15) 2g / L
Laurylisoquinolinium methanesulfonate 0.5g / L
Hydroquinone 0.3g / L
Dibenzothiazolyl disulfide trisulfonate trisodium 0.7 g / L
Ion exchange water balance

(3) Example 18
A tin plating bath was constructed with the following composition.
Stannous methanesulfonate (as Sn ²⁺ ) 10g / L
Methanesulfonic acid (as free acid) 30g / L
Cumylphenol polyethoxylate (EO12) 3g / L
Polyoxyethylene lauryl ammonium (EO15) 3g / L
Sodium gluconate 100g / L
Sodium citrate 50g / L
Sodium 1-hydroxy-4-naphthalenesulfonate 0.2 g / L
Dibenzothiazolyl disulfide disulphonate disodium salt 0.4 g / L
Potassium dibenzothiazolyl disulfide monosulfonate 0.1 g / L
Ion-exchanged water balance pH (adjusted with sodium hydroxide) 5.0

(4) Comparative Example 16
Based on the plating bath of Example 16, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed similarly to Example 16, and the tin-silver alloy plating bath of Comparative Example 16 was used. It was.

(5) Comparative Example 17
Based on the plating bath of Example 17, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed in the same manner as in Example 17 to obtain a tin plating bath of Comparative Example 17.

(6) Comparative Example 18
Based on the plating bath of Example 18, the benzothiazole disulfide disulfonic acid compound of the present invention was not added, and the other compositions were constructed in the same manner as in Example 18 to obtain a tin plating bath of Comparative Example 18.
[Evaluation test example]
Using immersion type horizontal rotating barrel plating equipment (manufactured by Kondo Co., Ltd .; trade name: mini-barrel), steel balls with a size of 500 μm are used as objects to be plated, and steel balls with a diameter of about 10 mm are used as cohesive grinding dummy balls and conductive media. Both the object to be plated having a capacity of 100 ml and the conductive medium of 10 inputs are accommodated in a barrel, and the barrel is immersed in each of the tin or tin alloy plating baths of Examples 16 to 18 and Comparative Examples 16 to 18, and Barrel plating treatment was performed under the conditions described above.
Bath temperature: 25 ° C
Cathode current density: 0.4 A / dm ²
Plating time: 60 minutes Then, after finishing plating, remove the cohesive grinding dummy balls from the object to be plated, and screen the object to be plated using a mesh (0.85 mm) sieve. The superiority or inferiority of the anti-aggregation effect of each tin or tin alloy plating bath was evaluated based on the residual ratio (%) of the object to be plated.
Residual rate of plating object (%) ＝
Number of objects to be plated remaining on sieve (weight) / Total number of objects to be plated accommodated in barrel (total weight)

The table below shows the test results.
Residual ratio of plating object (%)
Example 16 0.1
Example 17 0.3
Example 18 0.4
Comparative Example 16 18.5
Comparative Example 17 22.3
Comparative Example 18 20.7

<< Comprehensive evaluation of various tests >>
In Test Example 1 in which rack plating was performed by changing the cathode current density range using the plating baths of Comparative Examples 1 to 13, which are blank examples to which the compound of the present invention was not added, the uniformity of the obtained electrodeposition film In Examples 1 to 13 to which the compound of the present invention was added, many of them were excellent in smoothness and uniformity over a wide current density range, whereas the smoothness was inferior or lower than the practical level. Even in the examples, a practical level was sufficiently provided.
Also, in the solder wettability test example 2, all evaluations were x in comparative examples 1 to 13, but in examples 1 to 13 the evaluation was ◎ in more than half of the examples, and other examples Was also rated as good.
Thus, in the electrodeposition film of tin or tin alloy obtained in the above Examples 1 to 13, since it is excellent in smoothness, uniformity and solder wettability, a plating bath to which the compound of the present invention is added is used. When electroless plating was performed, the appearance of the obtained tin film was excellent in the film appearance as no abnormal particles were observed as seen in Test Example 3. In Comparative Examples 14 to 15, which are blank examples to which the compound of the present invention was not added, abnormal particles were generated in the obtained tin coating.
Therefore, regarding the smoothness and uniformity of the plating film over a wide current density range, or the film appearance and solder wettability, the tin or tin alloy plating bath to which the compound of the present invention is added is different from the plating bath to which no plating is added. There was a significant advantage, and this advantage was confirmed regardless of electroplating or electroless plating.

  When the tin or tin alloy plating bath to which the compound of the present invention is added is applied to barrel plating, as shown in Test Example 4, in the blank examples not added (Comparative Examples 16 to 18), the residual rate of the object to be plated is all. Although it was high and the sieving operation was not easy, it was confirmed that all of the added Examples 16 to 18 had a very low residual rate and could smoothly perform barrel plating.

Claims (4)

(A) a soluble salt comprising any one of a stannous salt and a mixture of a salt of a metal selected from the group consisting of stannous salt and silver, copper, bismuth, indium, zinc, antimony, nickel, lead; ,
(B) an acid or a salt thereof;
(C) a dibenzoazole disulfide sulfonic acid compound represented by the following general formula (1):

(In Formula (1), X is S, N, and O; m and n are integers of 0 to 2, provided that m and n are not 0; R is C ₁ to C ₃ alkyl, C ₁ -C ₃ alkoxy, halogen, amino, nitro, carboxyl; a and b are integers from 0 to 2; A is H, Na, K.)
A tin or tin alloy plating bath characterized by containing . Furthermore, it contains at least one additive selected from a complexing agent, a stabilizer, an antioxidant, a surfactant, a smoothing agent, a brightening agent, a semi-brightening agent, a conductive salt, a pH adjusting agent, and a buffering agent. The tin or tin alloy plating bath according to claim 1.   3. A barrel plating method comprising subjecting an object to be barrel-plated using the tin or tin alloy plating bath according to claim 1 or 2.   The object to be plated is an electronic component selected from a resistor, a variable resistor, a capacitor, a filter, an inductor, a thermistor, a crystal resonator, a switch, a lead wire, a printed circuit board, a semiconductor integrated circuit, and a module. 3. The barrel plating method according to 3.