JPH11279787A - Silver or silver alloy acidic electroplating bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably dissolve silver ion or silver and other ions even at a high temp. for a long time and to maintain certain plating performance without incorporating cyanides by incorporating a specified aminothiophenol compd. into an alloy acidic electroplating bath containing silver or silver and metals such as Sn and Bi. SOLUTION: An aminothiophenol compd. expressed by the formula is added to an alloy acidic electroplating bath containing silver or silver and one or more metals of Sn, Bi, Zn, In, Cu, Sb, Ti, Fe, Ni and Co. In the formula, R<1> , R<2> , R<4> , R<5> are each H or NH2 , R<3> is H, NH2 , OH, COOH, Cl, Br, NO2 , CH3 or OCH3 , and at least one of R<1> to R<3> is NH2 . In order to render the plating bath into acidic, any acidic materials can be added, and among those, alkane sulfonic acids, alkanol sulfonic acids and sulfamic acid are preferably used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acidic silver plating bath and an acidic silver alloy plating bath containing substantially no cyanide.

2. Description of the Related Art An alkaline cyanide bath containing a cyanide compound has been known as a tin-silver alloy plating bath used for forming a tin-silver alloy plating film on a metal substrate or the like. However, this bath is extremely toxic because it contains a toxic cyanide, so that special care must be taken in handling it, and it is necessary to perform special wastewater treatment and the working environment is deteriorated. there were. On the other hand, examples of the acidic bath containing no cyanide compound include mercaptoalkanecarboxylic acid and / or mercaptoalkanesulfonic acid bath described in JP-A-7-252684, JP-A-8-13185 and JP-A-8-185.
No. 41676 discloses an alkanesulfonic acid or alkanolsulfonic acid bath. But,
In these acid baths, silver, which is an essential component for forming a tin-silver alloy, cannot be stably dissolved together with tin, and silver is insolubilized as a black or brown precipitate immediately after plating bath preparation or within 24 hours. It was difficult to maintain the bath component concentration.

On the other hand, silver and silver alloy plating baths containing no cyanide include aminocarboxylic acid baths described in JP-A-60-100679 and JP-A-7-18008.
No. 5, JP-A-8-104993, and a bath using a hydantoin compound as a silver complexing agent.
Succinimide or a derivative thereof has been proposed as a silver complexing agent disclosed in Japanese Patent No. 166391, but these baths are weakly acidic to alkaline plating baths having a pH of 4 to 13. Japanese Patent Application Laid-Open No. 7-25268 discloses acidic silver and silver alloy plating containing no cyanide.
Japanese Patent Application Laid-Open No. 8-1 / 1994 discloses a mercaptoalkanecarboxylic acid and / or mercaptoalkanesulfonic acid bath disclosed in Japanese Patent Application Laid-Open No.
Alkanesulfonic acid or alkanolsulfonic acid baths disclosed in JP-A-3185 and JP-A-8-41676 have been proposed. However, in these acidic baths, silver, which is an essential component of the plating bath, cannot be stably dissolved. Immediately after the preparation of the plating bath or within 24 hours, silver becomes insoluble as black or brown precipitates, and the bath component concentration is maintained. It was difficult to do.

On the other hand, as a result of diligent research, the present applicant has developed an acid bath which is an alkanesulfonic acid and / or sulfamic acid bath containing a thioamide compound and a thiol compound as a silver complexing agent. 7-333043
No. 7 (Japanese Patent Application Laid-Open No. 9-170994). Here, the thiol compound is preferably a compound having 4 to 8 carbon atoms, such as mercaptosuccinic acid and mercaptolactic acid. Although this plating bath does not precipitate or insolubilize silver immediately after preparation or within 24 hours, when this plating bath is left or used for a long period of time, a thioamide compound and a thiol compound such as mercaptosuccinic acid or mercaptolactic acid have a plating performance. In particular, there is a problem that the smoothness and throwing power of the plating film are adversely affected. Further, when left at a high temperature, the above-mentioned JP-A-7-252684 is used.
As in the case of the acidic baths disclosed in Japanese Patent Application Laid-Open No. 8-13185 and JP-A-8-13185, silver was insoluble as a black or brown precipitate within 24 hours, and it was difficult to maintain the bath component concentration.

[0004] Accordingly, the applicant of the present application has conducted further intensive studies on the silver complexing agent in the acid bath, and as a result, has developed an acid bath containing an alkanesulfonic acid or an alkanolsulfonic acid and a sulfamic acid containing an aromatic thiol and an aromatic sulfide compound. And Japanese Patent Application No. 9-007555. In the acidic plating bath disclosed in Japanese Patent Application No. 9-007555, silver does not precipitate or insolubilize immediately after preparation or within 24 hours, and can stably dissolve silver even when left at a high temperature. It is more excellent in maintaining the bath component concentration than the acidic bath which is a alkanesulfonic acid and / or sulfamic acid bath containing a thioamide compound and a thiol compound disclosed in JP-A-9-170994. However, several types of plating baths containing an aromatic thiol and an aromatic sulfide compound shown in Japanese Patent Application No. 9-007555 are similar to the acidic baths containing a thioamide compound and a thiol compound shown in Japanese Patent Application Laid-Open No. 9-170994. Plating performance when left for a period or when used,
In particular, there is a problem that the smoothness and the throwing power of the plating film are adversely affected. Also, Japanese Patent Application Laid-Open No. 9-143
In an acidic bath which is an alkanesulfonic acid or alkanolsulfonic acid bath disclosed in Japanese Patent No. 786, a thiourea is used as a sulfur-containing compound similar to or other than the silver complexing agent described in the above-mentioned applicant's Japanese Patent Application Laid-Open No. Hei 9-17004. Compounds, tyrazole compounds, sulfenamide compounds, thiuram compounds, dithiocarbamate compounds, bisphenol compounds, benzimidazole compounds and organic thioacid compounds are shown as silver complexing agents. Among these sulfur-containing compounds, alkane sulfone Compounds that stably dissolve in the acidic region, such as acids and alkanolsulfonic acids, are limited. Further, in order to prevent substitution of silver in the plating object, and to keep the plating bath stable without turbidity, a plurality of sulfur-containing compounds, mainly thiourea-based compounds, must be used. In such cases, bath management becomes complicated, and it is difficult to maintain a constant plating performance for a long period of time.

[0005]

The present invention can stably dissolve silver or silver and other metal ions in a bath for a long period of time even at a high temperature without containing a cyanide compound. It is another object of the present invention to provide an acidic silver and silver alloy plating bath capable of maintaining a constant plating performance for a long period of time.

SUMMARY OF THE INVENTION The present invention is based on the finding that a single aminothiophenol-based compound has an action of stably dissolving silver itself or all of silver and other metal ions in an acid bath containing no cyanide compound. It was made based on the knowledge of. That is, the present invention relates to silver or silver and Sn, B
i, Zn, In, Cu, Sb, Tl, Fe, Ni and C
An alloy acidic electroplating bath containing at least one metal selected from the group consisting of: o, containing an aminothiophenol-based compound represented by the following general formula (I) and containing no cyanide compound: A silver or silver alloy acidic electroplating bath is provided.

[0006]

Embedded image

(Where R¹, R^Two, R^FourAnd R^FiveIs H
Or NH_TwoGroup, R^ThreeIs H, NH _Two, OH, COO
H, Cl, Br, NO_Two, CH_ThreeOr OCH_ThreeIs the base
Is R ¹~ R^ThreeAt least one is NH_TwoHaving a group.
R^FourAnd R^FiveIs preferably H. )

BEST MODE FOR CARRYING OUT THE INVENTION The silver compound used in the present invention may be any compound capable of releasing silver ions into an acidic bath, for example, one of silver oxide, silver sulfate, silver chloride, silver nitrate and the like. Mixtures of two or more are mentioned. The silver ion concentration in the plating bath can be arbitrarily set, but is preferably 0.01 to 100 g / l as silver, more preferably 0.01 to 80 g / l.
l, more preferably 0.1 to 50 g / l.

The metal elements other than silver for forming the silver alloy used in the present invention are Sn, Bi, Zn, In,
One or a mixture of two or more of Cu, Sb, Tl, Fe, Ni and Co can be mentioned. In the present invention, the compound of these metal elements may be any compound that can release these metal ions in an acidic bath.For example, each element is an oxide, chloride, sulfate, nitrate, carbonate,
Sulfide, iodide, citrate, oxalate, acetate,
One or a mixture of two or more tartrate salts. The concentration of the added metal element ion other than silver in the plating bath can be arbitrarily determined.
It is preferably set to 00 g / l, more preferably 0.01 to 80 g / l.

[0009] Of the above metal elements, tin is more preferable,
For example, one or a mixture of two or more of stannous oxide, stannous sulfate, tin chloride, tin sulfide, tin iodide, tin citrate, tin oxalate, stannous acetate and the like can be used. The tin ion concentration in the plating bath is preferably from 1 to 100 g / l, and more preferably from 10 to 60 g / l. In the present invention, Sn, Bi, Zn,
It is preferable to contain at least one metal selected from the group consisting of In, Cu, Sb, Tl, Fe, Ni and Co. Examples of the aminothiophenol-based compound used in the present invention include 2-aminothiophenol, 4-aminothiophenol, and 4-hydroxy-2-
Aminothiophenol, 4-chloro-2-aminothiophenol, 4-carboxy-2-aminothiophenol, 4-methyl-2-aminothiophenol, 4-methoxy-2-aminothiophenol, 4-bromo-2- It is preferable to use an aminothiophenol-based compound such as aminothiophenol.

The aminothiophenol compounds to be used preferably have a structure having an NH ₂ group at the ortho position. In the present invention, the aminothiophenol-based compound may be used alone or in combination, or may be used as a mixture of two or more types. However, even when used alone, it is sufficiently effective in maintaining bath stability and plating performance. They also act as brighteners. The amount of the aminothiophenol compound used in the present invention can be any amount as long as silver or silver and all other metal elements in the bath can be stably dissolved, but the amount is 0.1 to 200 g / l. It is preferable that the amount be 0.2 to 50 g / l.

In the present invention, the pH of the silver and silver alloy plating bath
In order to make the compound acidic, any acidic substance can be contained. Among them, alkanesulfonic acids, for example, alkanesulfonic acids having 1 to 3 carbon atoms such as methanesulfonic acid, ethanesulfonic acid, and hydroxypropanesulfonic acid. It is preferable to use acids, benzenesulfonic acids and phenolsulfonic acids such as those having 6 to 7 carbon atoms such as sulfosalicylic acid and cresolsulfonic acid, and alkanolsulfonic acids such as isopropanolsulfonic acid and sulfamic acid. . These acids can be used as one kind or as a mixture of two or more kinds. The acid concentration of the plating bath can be arbitrarily set within a range in which both silver and silver and other metal ions can be dissolved.
It is good to be 500 g / l, more preferably 50 to 400 g / l. In particular, the bath is preferably contained so as to have a pH of 2 or less, more preferably 1 or less.

In the present invention, the above components are essential, and the balance can be water. However, additives such as a brightener and a smoothing agent may be further contained. For example, the brightener may be any of those used as brighteners for silver and silver alloys. For example, nonionic surfactants, anionic surfactants, cationic surfactants, amphoteric surfactants, synthetic polymers (PVA) PEG, PVP), amines (hexamethylenetetramine, triethanolamine, etc.), ketones (benzalacetone, acetophenone, etc.), aliphatic aldehydes (formalin, crotonaldehyde, etc.),
Aromatic aldehydes (salicylaldehyde, vanillin, etc.), unsaturated aliphatic aldehydes and amine compounds and reactants, or Sb or Se, Cu, In, Zn, C
One or a mixture of two or more kinds of metal compounds such as a and Ba can be used. The brightener is preferably used in an amount of 0.05 to 50 g / l, more preferably in an amount of 0.1 to 30 g / l.

In the case of a silver-tin-based alloy plating bath, a hydroxyphenyl compound such as phenol, catechol, pyrogallol, hydroquinone, L-ascorbic acid, sorbitol, etc. may be used as an antioxidant for tin. . Using the acidic silver plating bath or the acidic silver alloy plating bath of the present invention, silver or silver alloy plating can be applied to various metal substrates, for example, iron, copper, and their alloys, by a conventional method. Specifically, a metal substrate as a cathode, a silver plate, an alloy plate of silver and another metal element, or a plate of another metal element or an insoluble electrode as an anode, immersed in a silver or silver alloy plating bath, Then, a current of about 0.1 to 100 A is applied for 0.5 to 10
100% by weight of silver or 0.0% of silver
1 to 99.9% by weight, with the balance being another metal element having a thickness of 1
A film having a thickness of ５０50 μm, preferably 1-30 μm can be formed on a metal substrate.

[0014]

The silver or silver alloy plating bath of the present invention has the advantage of being less toxic and having higher safety than conventional alkaline cyanide baths because it is a cyanide-free bath.
In addition, silver is apt to form insoluble salts with various silver, but in the silver or silver alloy plating bath of the present invention, it is stably present for a long period of time, and the plating performance (particularly the smoothness and throwing power of the plating film). There is no change. Further, since no special wastewater treatment is required, there is an advantage that the wastewater treatment cost is reduced. Next, the present invention will be described with reference to examples.

EXAMPLE 1 An acidic silver plating bath comprising the following components and the balance being water was prepared. Ag ₂ O 35 g / l Methanesulfonic acid 150 g / l 2-aminothiophenol 80 g / l

Example 2 An acidic silver-tin alloy plating bath comprising the following components and the balance being water was prepared. Ag ₂ O 2 g / l Methanesulfonic acid 350 g / l 2-aminothiophenol 5 g / l SnO 30 g / l Example 3 An acidic silver-tin alloy plating bath having the following components and the balance being water was prepared. Ag ₂ O 1 g / l Methanesulfonic acid 150 g / l 2-aminothiophenol 8 g / l SnO 30 g / l Anionic surfactant (Sanrex BNS manufactured by Nikka Kagaku) 4 g / l Benzal acetone 0.5 g / l

Example 4 An acidic silver-tin alloy plating bath comprising the following components and the balance being water was prepared. Ag ₂ SO ₄ 10 g / l hydroxypropanesulfonic acid 100 g / l sulfamic acid 50 g / l 2-aminothiophenol 5 g / l 4-aminothiophenol 8 g / l SnO 10 g / l polyvinylpyrrolidone K-30 5 g / l 35% Formalin 10 g / l Antimonyl potassium tartrate 0.1 g / l

Example 5 An acidic silver-copper alloy plating bath comprising the following components and the balance being water was prepared. Ag ₂ SO ₄ 20 g / l Isopropanol sulfonic acid 250 g / l 2-aminothiophenol 5 g / l CuSO ₄ .5H ₂ O 16 g / l Example 6 An acidic silver-bismuth alloy plating comprising the following components, with the balance being water A bath was prepared. Ag ₂ O 15 g / l Methanesulfonic acid 250 g / l 4-chloro-2-aminothiophenol 5 g / l Bi ₂ O ₃ 12 g / l

Example 7 An acidic silver-antimony alloy plating bath comprising the following components and the balance being water was prepared. Ag ₂ SO ₄ 25 g / l Isopropanol sulfonic acid 100 g / l Sulfamic acid 50 g / l 4-aminothiophenol 25 g / l Sb ₂ O ₃ 10 g / l Example 8 Acid silver comprising the following components, the balance being water An indium alloy plating bath was prepared. Ag ₂ O 1.2g / l methanesulfonic acid 180 g / l 2-aminothiophenol _{7g / l In 2 (SO 4} ) 3 · 9H 2 O 105g / l

Example 9 An acidic silver-zinc alloy plating bath having the following components and the balance being water was prepared. Ag ₂ SO ₄ 4 g / l Hydroxypropanesulfonic acid 150 g / l 4-hydroxy-2-aminothiophenol 7 g / l ZnSO ₄ .7H ₂ O 80 g / l Example 10 An acid consisting of the following components, the balance being water A silver-tin-copper alloy plating bath was prepared. Ag ₂ O 2 g / l Methanesulfonic acid 250 g / l 2-aminothiophenol 20 g / l SnO 40 g / l CuSO ₄ .5H ₂ O 4 g / l

Example 11 An acidic silver-tin-bismuth alloy plating bath having the following components and the balance being water was prepared. It consists Ag ₂ O 1g / l phenol sulfonic acid 50 g / l methanesulfonic acid 250 g / l 2-aminothiophenol 5g / l SnO 30g / l Bi 2 O 3 5g / l Example 12 the following ingredients, the balance being water An acidic silver-tin-indium alloy plating bath was prepared. Ag ₂ O 10g / l hydroxypropane sulfonic acid 150 g / l 2-aminothiophenol 5 g / l 4-aminothiophenol 15g / l SnO 1 0g / l In 2 (SO 4) 3 · 9H 2 O 15g / l polyvinylpyrrolidone K-15 10 g / l Crotonaldehyde 10 g / l Triethylenetetramine 2 g / l

Example 13 An acidic silver-tin-bismuth-copper alloy plating bath having the following components and the balance being water was prepared. Ag ₂ O 0.8 g / l Methanesulfonic acid 150 g / l 2-aminothiophenol 5 g / l SnO 30 g / l Bi ₂ O ₃ 8 g / l CuSO ₄ .5H ₂ O 3 g / l PEG 11000 4 g / l Anionic surfactant Agent (Rapidol B-80, manufactured by NOF Corporation) 10 g / l Benzal acetone 1.5 g / l

Example 14 An acidic silver-tin-zinc-antimony alloy plating bath having the following components and the balance being water was prepared. Ag ₂ O 2g / l isopropanol sulfonic acid 150 g / l ethanesulfonic acid 50 g / l 4-aminothiophenol 5g / l SnO 30g / l ZnSO 4 · 7H 2 O 30g / l tartrate antimony Le potassium 2 g / l anionic surfactants (Nichika Chemical S-010S) 6g / l Piperonal 0.1g / l Hexamethylenetetramine 4g / l

Comparative Example 1 An acidic silver plating bath comprising the following components and the balance being water was prepared. Ag ₂ O 35 g / l Methanesulfonic acid 150 g / l Comparative Example 2 An acidic silver-tin alloy plating bath having the following components and the balance being water was prepared. Ag ₂ O 2 g / l Methanesulfonic acid 150 g / l SnO 30 g / l Comparative Example 3 An acidic silver-tin alloy plating bath comprising the following components and the balance being water was prepared. Ag ₂ O 5 g / l Isopropanol sulfonic acid 150 g / l SnO 30 g / l

Comparative Example 4 An acidic silver-tin alloy plating bath comprising the following components and the balance being water was prepared. AgNO ₃ 63 g / l SnCl ₄ .5H ₂ O 30 g / l thiomalic acid 90 g / l potassium citrate 26 g / l Comparative Example 5 An acidic silver plating bath comprising the following components and the balance being water was prepared. Ag ₂ O 5 g / l Methanesulfonic acid 150 g / l Thiourea 5 g / l

Comparative Example 6 An acidic silver-tin alloy plating bath having the following components and the balance being water was prepared. Ag ₂ O 2 g / l Methanesulfonic acid 150 g / l Thiourea 3 g / l SnO 30 g / l Sn-222 (dip sole tin-plated brightener) 30 g / l Comparative Example 7 Consisting of the following components, the balance being water An acidic silver-tin alloy plating bath was prepared. Ag ₂ O 1 g / l Methanesulfonic acid 150 g / l SnO 30 g / l thiourea 3 g / l Nonionic surfactant (Sanmol BN-13D manufactured by Nikka Chemical) 4 g / l hexamethylenetetramine 4 g / l benzal acetone 1 0.5 g / l potassium antimonyl tartrate 0.1 g / l

Comparative Example 8 An acidic silver-tin alloy plating bath comprising the following components and the balance being water was prepared. Ag ₂ O 3 g / l Methanesulfonic acid 150 g / l 2,2-diaminodiphenyl disulfide 5 g / l SnO 30 g / l Nonionic surfactant (Evan 450 manufactured by Daiichi Kogyo Seiyaku) 4 g / l Benzal acetone 0.2 g / l Comparative Example 9 An acidic silver-tin alloy plating bath having the following components and the balance being water was prepared. Ag ₂ SO ₄ 4 g / l hydroxypropanesulfonic acid 180 g / l thiosalicylic acid 200 g / l SnSO ₄ 54 g / l Sn-222 (dip sole tin plating brightener) 30 g / l Comparative Example 10 An acidic silver-tin alloy plating bath as water was prepared. Ag ₂ O 2 g / l Ethanesulfonic acid 180 g / l 4,4-thiodiphenol 5 g / l SnO 30 g / l Nonionic surfactant (Cedran FF-180 manufactured by Sanyo Chemical) 4 g / l hexamethylenetetramine 4 g / l benzal Acetone 1.5g / l Potassium antimonyl tartrate 0.1g / l

After adjusting the plating baths of Examples 1 to 14 and Comparative Examples 1 to 10, the plates were allowed to stand at room temperature for 4 hours and 10 days.
After 30 days and 120 days, the presence or absence of precipitation in the plating bath was visually observed, and the silver concentration was analyzed by atomic absorption spectrophotometry. The results are shown in Table-1.

[0028]

[Table 1] Table-1 Silver concentration in the presence or absence bath precipitate (g / l) a b c d a b c d Example 1 ○ ○ ○ ○ 32.6 32.5 32.6 32.6 Example 2 ○ ○ ○ ○ 1.86 1.85 1.85 1.86 Example 3 ○ ○ ○ ○ 0.93 0.93 0.91 0.92 Example 4 ○ ○ ○ ○ 6.92 6.92 6.93 6.92 Example 5 ○ ○ ○ ○ 13.8 13.7 13.8 13.7 Example 6 ○ ○ ○ ○ 13.9 13.9 14.0 13.9 Example 7 ○ ○ ○ ○ 17.3 17.3 17.3 17.2 Example 8 ○ ○ ○ ○ 1.12 1.12 1.12 1.11 Example 9 ○ ○ ○ ○ 2.76 2.76 2.77 2.76 Example 10 ○ ○ ○ ○ 1.86 1.86 1.86 1.86 Example 11 ○ ○ ○ 0.92 0.93 0.93 0.93 Example 12 ○ ○ ○ ○ 9.30 9.31 9.31 9.31 Example 13 ○ ○ ○ ○ 0.74 0.73 0.74 0.74 Example 14 ○ ○ ○ ○ 1.86 1.86 1.86 1.86 Comparative Example 1 × × × × 0.00 0.00 0.00 0.00 Comparative Example 2 × × × × 0.00 0.00 0.00 0.00 Comparative Example 3 × × × × 0.00 0.00 0.00 0.00 Comparative Example 4 ○ × × × 40.0 8.76 0.00 0.00 Comparative Example 5 ○ ○ ○ ○ 4.66 4.65 4.66 4.65 Comparative Example ○ ○ ○ ○ 1.86 1.85 1.86 1.86 Comparative Example 7 ○ ○ ○ ○ 0.93 0.93 0.93 0.93 Comparative Example 8 ○ ○ ○ ○ 2.79 2.78 2.79 2.79 Comparative Example 9 ○ ○ ○ ○ 2.76 2.76 2.77 2.77 Comparative Example 10 ○ ○ ○ ○ 1.86 1.86 1.86 1.87

：: No precipitation a 4 hours after preparation of plating bath X: Precipitation b 10 days after preparation of plating bath c 30 days after preparation of plating bath d 120 days after preparation of plating bath Using the plating baths of Examples 1 to 14 and Comparative Examples 5 to 7, after preparation of the plating baths,
After 4 hours, 10 days, 30 days, and 120 days, the presence or absence of precipitation in the plating bath was visually observed, and the silver concentration was analyzed by atomic absorption spectrophotometry. Table 2 shows the results.

[0030]

[Table 2] Table-2 Silver concentration in the presence or absence bath precipitate (g / l) a b c d a b c d Example 1 ○ ○ ○ ○ 32.6 32.5 32.6 32.6 Example 2 ○ ○ ○ ○ 1.86 1.85 1.85 1.86 Example 3 ○ ○ ○ ○ 0.93 0.93 0.91 0.92 Example 4 ○ ○ ○ ○ 6.92 6.92 6.93 6.92 Example 5 ○ ○ ○ ○ 13.8 13.7 13.8 13.7 Example 6 ○ ○ ○ ○ 13.9 13.9 14.0 13.9 Example 7 ○ ○ ○ ○ 17.3 17.3 17.3 17.2 Example 8 ○ ○ ○ ○ 1.12 1.11 1.12 1.11 Example 9 ○ ○ ○ ○ 2.76 2.76 2.77 2.76 Example 10 ○ ○ ○ ○ 1.86 1.86 1.86 1.86 Example 11 ○ ○ ○ 0.92 0.93 0.93 0.93 Example 12 ○ ○ ○ ○ 9.30 9.31 9.31 9.31 Example 13 ○ ○ ○ ○ 0.74 0.73 0.74 0.74 Example 14 ○ ○ ○ ○ 1.86 1.86 1.86 1.86 Comparative Example 5 ○ × × × 2.01 0.00 0.00 0.00 Comparative Example 6 ○ × × × 0.74 0.00 0.00 0.00 Comparative Example 7 ○ × × × 0.36 0.00 0.00 0.00 Comparative Example 8 ○ ○ ○ ○ 2.79 2.78 2.79 2.79 Comparative Example 9 ○ ○ ○ ○ 2.76 2.76 2.77 2.77 Ratio Comparative Example 10 ○ ○ ○ ○ 1.86 1.86 1.86 1.87

○: No precipitation a 4 hours after plating bath preparation ×: Precipitation b 10 days after plating bath preparation c 30 days after plating bath preparation d 120 days after plating bath preparation Using the plating baths of Examples 1 to 14 and Comparative Examples 5 to 7, after preparing the plating bath,
The Hull cell test was performed for 10 hours, 30 days, and every 120 days under the following conditions. (Test conditions) Bath temperature: 25 ° C Anode plate: Insoluble anode (Ti-Pt) Negative plate: Polished steel plate Current: 3A Plating time: 10 minutes

In the plating baths of Examples 1 to 14, the appearance of the plating did not change with the lapse of time, and the eutectoid rates of silver and other metals did not change. In the plating baths of Comparative Example 5 and Comparative Example 8, coarse deposition occurred in the high current density portion with the lapse of time, and the throwing power of the plating decreased. In the plating baths of Comparative Examples 6 and 9, coarse precipitation occurred in the high current density portion with the lapse of time, and the silver-tin alloy ratio increased with the silver alloy ratio. In the plating baths of Comparative Examples 7 and 10, the glossiness and the smoothness of the plating film decreased with the lapse of time, and the silver-tin alloy ratio decreased with the silver alloy ratio. 1cm, 5cm, 9 from the high current density side of each Hull cell test panel
Table 3 shows the eutectoid ratios of silver and other metals analyzed by dissolving the film in the cm portion and analyzing by atomic absorption spectrometry.

[0033]

[Table 3] Table-3 Eutectoid ratio of silver and other metals in the coating (% by weight) Elapsed time of standing 4 hours 10 days High current density side 1cm 5cm 9cm 1cm 5cm Distance from 9cm Example 1 Ag 100.0 100.0 100.0 100.0 100.0 100.0 Example 2 Ag 3.5 3.7 4.2 3.6 3.7 4.1 Sn 96.5 96.3 95.8 96.4 96.3 95.9 Example 3 Ag 4.2 3.7 5.6 4.0 3.6 5.7 Sn 95.8 96.3 94.4 96.0 96.4 94.3 Example 4 Ag 58.4 61.2 77.8 59.0 60.7 78.5 Sn 41.6 39.8 22.2 41.0 39.3 21.5 Example 5 Ag 77.5 74.5 72.6 78.2 72.6 72.6 Cu 22.5 25.5 27.4 21.8 27.4 27.4 Example 6 Ag 57.7 56.2 60.2 56.4 57.1 59.7 Bi 42.3 43.8 39.8 45.6 42.9 40.3 Example 7 Ag 65.4 71.3 73.6 64.8 70.7 73.1 Sb 34.6 28.7 26.4 35.2 29.3 26.9 Example 8 Ag 3.8 3.6 4.1 4.2 3.8 3.9 In 96.2 96.4 95.9 95.8 96.2 96.1 Example 9 Ag 85.1 77.4 62.8 85.5 78.1 63.2 Zn 14.9 22.6 37.2 14.5 21.9 36.8 Example 10 Ag 5.5 3.7 2.9 5.5 3.5 3.0 Sn 94.1 95.8 96.4 94.0 96.0 96.2 Cu 0.4 0.5 0.7 0.5 0.5 0.8 Example 11 Ag 4.2 3.4 2.8 4.3 3.3 2.6 Sn 93.3 92.3 92.1 93.4 92.3 92.5 Bi 2.5 4. 3 5.1 2.3 4.4 4.9 Example 12 Ag 36.7 24.5 18.8 37.8 25.4 18.5 Sn 59.1 70.0 74.1 58.1 69.2 74.6 In 4.2 5.5 7.1 4.1 5.4 6.9 Example 13 Ag 2.0 1.9 1.8 2.1 2.0 1.9 Sn 90.4 90.2 89.9 90.3 89.8 89.8 Bi 7.3 7.5 7.7 7.2 7.7 7.6 Cu 0.3 0.4 0.6 0.4 0.5 0.7 Example 14 Ag 7.5 5.1 3.1 7.6 5.3 3.3 Sn 91.29 93.98 96.06 91.19 93.88 95.85 Zn 1.2 0.9 0.8 1.2 0.8 0.8 Sb 0.01 0.02 0.04 0.01 0.02 0.05 Comparative example 5 Ag 100.0 100.0 100.0 100.0 100.0 No precipitation Comparative Example 6 Ag 7.8 5.5 2.8 8.5 6.4 3.1 Sn 92.2 94.5 97.2 91.5 93.6 96.9 Comparative Example 7 Ag 5.6 3.4 1.9 4.4 2.1 1.1 Sn 94.4 96.6 98.1 95.6 97.9 98.9

[0034]

[Table 4] Table-3 (continued) Eutectoid ratio of silver and other metals in the coating (% by weight) Elapsed time of storage 30 days 120 days High current density side 1cm 5cm 9cm 1cm 5cm Distance from 9cm Example 1 Ag 100.0 100.0 100.0 100.0 100.0 100.0 Example 2 Ag 3.5 3.8 4.2 3.5 3.7 4.2 Sn 96.5 96.2 95.8 96.5 96.3 95.8 Example 3 Ag 4.1 3.7 5.7 4.2 3.8 5.6 Sn 95.9 96.3 94.3 95.8 96.2 94.4 Example 4 Ag 58.1 61.6 78.2 58.4 60.5 77.3 Sn 41.9 38.4 21.8 41.6 39.5 22.7 Example 5 Ag 77.1 73.4 73.6 78.1 74.2 72.5 Cu 22.9 26.6 26.4 21.9 25.8 27.5 Example 6 Ag 56.8 56.9 60.5 57.4 55.8 59.9 Bi 43.2 43.1 39.5 42.6 44.2 40.1 Example 7 Ag 64.8 71.5 73.2 65.8 71.5 73.5 Sb 35.2 28.5 26.8 34.2 28.5 26.5 Example 8 Ag 4.1 3.4 3.4 3.3 3.1 4.0 In 95.9 96.6 96.6 96.7 96.9 96.0 Example 9 Ag 85.1 77.1 62.6 85.5 77.7 62.7 Zn 14.9 22.9 37.4 14.5 22.3 37.3 Example 10 Ag 5.7 3.5 3.1 5.5 3.6 3.0 Sn 93.9 96.0 96.1 94.0 95.7 96.2 Cu 0.4 0.5 0.8 0.5 0.7 0.8 Example 11 Ag 4.0 3.3 2.6 4.2 3.4 2.7 Sn 93.4 92.2 92.4 93.4 92.2 92.3 B i 2.6 4.5 5.0 2.4 4.4 5.0 Example 12 Ag 36.5 24.9 18.5 36.8 24.7 18.7 Sn 59.5 69.7 74.5 59.1 69.9 74.3 In 4.0 5.4 7.0 4.1 5.4 7.0 Example 13 Ag 2.2 2.1 1.7 2.0 1.8 1.8 Sn 90.2 89.9 90.1 90.5 90.1 89.8 Bi 7.3 7.5 7.4 7.2 7.6 7.7 Cu 0.3 0.5 0.8 0.3 0.5 0.7 Example 14 Ag 7.8 5.0 3.3 7.6 5.1 3.2 Sn 91.08 93.98 95.86 91.19 94.08 96.06 Zn 1.1 1.0 0.8 1.2 0.8 0.7 Sb 0.02 0.02 0.04 0.01 0.02 0.04 Comparative example 5 Ag 100.0 100.0 Not yet Precipitation 100.0 100.0 No precipitation Comparative Example 6 Ag 9.8 6.9 3.7 9.7 7.0 3.8 Sn 90.2 93.1 96.3 90.3 93.0 96.2 Comparative Example 7 Ag 3.6 1.6 0.9 3.4 1.4 0.8 Sn 96.4 98.4 99.1 96.6 98.6 99.2

Claims (3)

[Claims] 1. Silver or silver and Sn, Bi, Zn, In, C
u, Sb, Tl, Fe, Ni and Co.
Alloy acid containing at least one metal
A bath which is an amino acid represented by the following general formula (I)
Containing a thiophenol compound and a cyanide compound
Silver or silver alloy acidic electrode
A bath. Embedded image(Where R¹, R^Two, R^FourAnd R^FiveIs H or NH
_TwoGroup, R^ThreeIs H, NH _Two, OH, COOH, Cl, B
r, NO_Two, CH_ThreeOr OCH_ThreeIs a group, ¹~ R
^ThreeAt least one is NH_TwoHaving a group. ) 2. The acidic plating bath according to claim 1, which contains at least one selected from the group consisting of alkanesulfonic acid, alkanolsulfonic acid and sulfamic acid. 3. Sn, Bi, Zn, In, Cu, S
2. The acidic plating bath according to claim 1, comprising at least one metal selected from the group consisting of b, Tl, Fe, Ni and Co.