WO2016021439A1

WO2016021439A1 - Copper-tin alloy plating bath

Info

Publication number: WO2016021439A1
Application number: PCT/JP2015/071330
Authority: WO
Inventors: 貴光辻本; 敏光長尾; 原　健二; 順一片山; 邦顕大塚
Original assignee: 奥野製薬工業株式会社
Priority date: 2014-08-08
Filing date: 2015-07-28
Publication date: 2016-02-11
Also published as: CA2957587A1; HK1232261A1; TWI641729B; JP6048712B2; CN106661752A; EP3178969A1; EP3178969A4; CA2957587C; JPWO2016021439A1; TW201612362A; CN106661752B; US20170204528A1; EP3178969B1

Abstract

The objective of the present invention is to provide a copper-tin alloy plating bath which is capable of forming a thick film without using cyanide ions, and which is able to be suited to barrel plating. The present invention relates to a copper-tin alloy plating bath which is composed of an aqueous solution that contains a water-soluble copper compound, a water-soluble divalent tin compound, a sulfur-containing compound represented by formula (1) and an aromatic compound having a hydroxyl group. R-(CH₂)_l-S-(CH₂)_m-S-(CH₂)_n-R (1) (In the formula, R represents H, OH or SO₃Na; and each of l, m and n independently represents an integer of 0-3.)

Description

Copper-tin alloy plating bath

The present invention relates to a copper-tin alloy plating bath.

Nickel plating has been widely used in electroplating. However, in nickel plating, the problem of nickel allergy in which skin irritation or irritation occurs due to the metal element (nickel) contained in the plating film has been pointed out, and an alternative technique to replace this is required.

On the other hand, the copper-tin alloy was known as an alloy having a white appearance and film characteristics comparable to those of nickel. Therefore, copper-tin alloy plating has attracted attention as an alternative to nickel plating.

Conventionally, a plating bath containing cyan ions (cyan bath) has been used as a plating bath for copper-tin alloy plating, but there are problems from the viewpoint of working environment and wastewater treatment regulations. In recent years, pyrophosphoric acid baths (for example, Patent Documents 1 to 3), acidic baths (for example, Patent Documents 4 to 5), etc. have been proposed as copper-tin alloy baths that do not contain cyan ions (hereinafter, also referred to as “no cyanide”). Has been. However, the pyrophosphoric acid bath has a higher internal stress in the formed plating film than the cyan bath, and cracks are generated during plating, making it difficult to increase the thickness of the plating film. In addition, since the precipitation potential of copper and tin is not adjusted in the acidic bath, there is a problem that copper is preferentially precipitated in the case of barrel plating with a large current density fluctuation, and the alloy composition is largely destroyed.

From the above, there is a demand for a plating bath that can increase the thickness of the plating film in the same manner as the cyan bath and can also be used for barrel plating.

JP-A-10-102278 JP 2001-295092 A JP 2004-035980 A JP 2009-161804 A JP 2010-189753 A

The present invention has been made in view of the above-described problems of the prior art, and its main object is to enable thickening without using cyan ions and to cope with barrel plating. A copper-tin alloy plating bath is provided.

The present inventors have conducted intensive research to achieve the above-described purpose. As a result, by using a specific sulfur-containing compound and an aromatic compound having a hydroxyl group, a copper-tin alloy plating bath that can be thickened without using cyan ions and can also be used for barrel plating. It was found that can be obtained. The present invention has been completed as a result of further studies based on such findings.

That is, the present invention provides the following copper-tin alloy plating bath and the like.
Item 1. Water-soluble copper compound, water-soluble divalent tin compound, general formula (1):
R— (CH ₂ ) ₁ —S— (CH ₂ ) _m —S— (CH ₂ ) _n —R (1)
(Wherein R is H, OH or SO ₃ Na, and l, m and n are each independently an integer of 0 to 3), and an aromatic compound having a hydroxyl group A copper-tin alloy plating bath comprising an aqueous solution containing
Item 2. The water-soluble copper compound is 1 to 60 g / L in terms of copper ion, the water-soluble divalent tin compound is 5 to 40 g / L in terms of divalent tin ion, the sulfur-containing compound is 5 to 500 g / L, and the hydroxyl group is Item 4. The copper-tin alloy plating bath according to Item 1, which contains 1 to 50 g / L of the aromatic compound.
Item 3. The sulfur-containing compound is methanedithiol, 1,2-ethanedithiol, 1,3-propanedithiol, 3,6-dithia-1,8-octanediol, and 3,3′-dithiobis (sodium 1-propanesulfonate) 3. The copper-tin alloy plating bath according to

item

1 or 2, which is at least one selected from the group consisting of:
Item 4. The above items 1 to 3, wherein the aromatic compound having a hydroxyl group is at least one selected from the group consisting of phenol, catechol, hydroquinone, resorcinol, pyrogallol, p-cresolsulfonic acid, sodium ascorbate, and sodium erythorbate. 4. The copper-tin alloy plating bath according to any one of 3 above.
Item 5. Item 5. The copper-tin alloy plating bath according to any one of Items 1 to 4, wherein the aqueous solution further contains a nonionic surfactant and an aromatic ketone or an aromatic aldehyde.
Item 6. 6. A copper-tin alloy plating method in which electrolysis is performed using the object to be plated as a cathode in the copper-tin alloy plating bath according to any one of items 1 to 5.
Item 7. An article in which a copper-tin alloy plating film is formed by the method according to item 6 above.

Since the copper-tin alloy plating bath of the present invention uses a specific sulfur-containing compound and an aromatic compound having a specific hydroxyl group, an alloy containing copper and tin at an arbitrary ratio can be obtained. Further, the copper-tin alloy plating bath of the present invention is less susceptible to cracking than the conventional pyrophosphoric acid bath by using a specific sulfur-containing compound as a complexing agent, and a cyan bath is not used. Also, it is possible to increase the thickness of the plating film. Furthermore, since the copper-tin alloy plating bath of the present invention has less influence on the alloy ratio than the conventional acid bath, it can cope with barrel plating in which the current density varies greatly. Further, by adding a nonionic surfactant and an aromatic ketone or aromatic aldehyde to the copper-tin alloy plating bath, a plating film having an excellent gloss appearance can be obtained.

It is a figure which shows the relationship between the current density of a copper- tin alloy plating bath, and the copper content rate of a plating film.

Hereinafter, the copper-tin alloy plating bath of the present invention will be specifically described.

The copper-tin alloy plating bath of the present invention comprises a water-soluble copper compound and a water-soluble divalent tin compound as a metal source, and a general formula (1) as a complexing agent:
R— (CH ₂ ) ₁ —S— (CH ₂ ) _m —S— (CH ₂ ) _n —R (1)
(Wherein R is H, OH or SO ₃ Na, and l, m and n are each independently an integer of 0 to 3), and an aromatic compound having a hydroxyl group It consists of the aqueous solution containing.

The water-soluble copper compound which is a copper ion source can be used without particular limitation as long as it is a water-soluble compound containing divalent copper as a copper component. Specific examples of water-soluble copper compounds include copper chloride (II), copper sulfate (II), copper nitrate (II), copper carbonate (II), copper oxide (II), copper acetate (II), copper methanesulfonate ( II), copper (II) sulfamate, copper (II) fluoride, copper (II) 2-hydroxyethanesulfonate, copper (II) 2-hydroxypropanesulfonate, copper (II) pyrophosphate and the like. Of these copper compounds, copper (II) sulfate is preferred. These water-soluble copper compounds can usually be used singly or in combination of two or more. The concentration of the water-soluble copper compound is, for example, about 1 to 60 g / L, preferably about 10 to 40 g / L as the copper ion concentration.

The water-soluble divalent tin compound that is a tin ion source can be used without particular limitation as long as it is a water-soluble compound containing divalent tin as a tin component. Specific examples of water-soluble divalent tin compounds include stannous chloride, stannous sulfate, stannous acetate, stannous pyrophosphate, stannous methanesulfonate, stannous sulfamate, stannous gluconate, tartaric acid Examples thereof include stannous oxide, stannous oxide, stannous borofluoride, tin 2-hydroxyethane sulfonate, tin 2-hydroxypropane sulfonate, and the like. Of these tin compounds, stannous sulfate is preferred. These water-soluble divalent tin compounds can be used singly or in combination of two or more. The concentration of the water-soluble divalent tin compound is, for example, about 5 to 40 g / L, preferably about 5 to 25 g / L as the divalent tin ion concentration.

The mixing ratio of the water-soluble copper compound and the water-soluble divalent tin compound is preferably copper: tin (molar ratio of metal) = 1: 0.1 to 0.6. In particular, copper: tin (molar ratio of metal) = 1: 0.1 to 0.3 is preferable.

In the present invention, the general formula (1):
R— (CH ₂ ) ₁ —S— (CH ₂ ) _m —S— (CH ₂ ) _n —R (1)
(Wherein R is H, OH or SO ₃ Na, and l, m and n are each independently an integer of 0 to 3). is there. Specific examples of the sulfur-containing compound represented by the general formula (1) include methanedithiol, 1,2-ethanedithiol, 1,3-propanedithiol, 3,6-dithia-1,8-octanediol, 3 , 3′-dithiobis (sodium 1-propanesulfonate) and the like. Among these compounds, 3,6-dithia-1,8-octanediol, 3,3′-dithiobis (1-propanesulfonic acid sodium salt) and the like having low odor are preferable from the viewpoint of the working environment, and 3,6- Dithia-1,8-octanediol is more preferred. These sulfur-containing compounds can usually be used alone or in combination of two or more. The concentration of the complexing agent is, for example, about 5 to 500 g / L, and preferably about 80 to 320 g / L.

In the present invention, an aromatic compound having a hydroxyl group is used. Examples of the aromatic compound having a hydroxyl group include a compound in which one or more hydroxyl groups are substituted on a benzene ring or furan ring, and a compound having a benzene ring is preferable from the viewpoint of working environment and liquid stability. Specific examples of the aromatic compound having a hydroxyl group include phenol, catechol, hydroquinone, resorcinol, pyrogallol, p-cresolsulfonic acid, ascorbic acid, erythorbic acid, and alkali metal salts thereof. Examples of the alkali metal include sodium and potassium. As the aromatic compound having a hydroxyl group, phenol, catechol, hydroquinone, resorcinol, pyrogallol, p-cresolsulfonic acid, sodium ascorbate, and sodium erythorbate are preferable. The aromatic compound having a hydroxyl group has an action of reducing divalent copper ion (Cu ²⁺ ) to monovalent copper ion (Cu ¹⁺ ), and assists in forming a complex between the copper ion and the complexing agent. it seems to do. These aromatic compounds having a hydroxyl group can be used singly or in combination of two or more. The concentration of the aromatic compound having a hydroxyl group is, for example, about 1 to 50 g / L, and preferably about 5 to 30 g / L.

The compounding amount of the complexing agent and the aromatic compound having a hydroxyl group is preferably 2 mol / L or more for the complexing agent and 1 mol / L or more for the aromatic compound having a hydroxyl group with respect to 1 mol / L of copper.

As the acid constituting the base of the copper-tin alloy plating bath, known organic acids and inorganic acids can be widely used. Specific examples of the organic acid include methanesulfonic acid, ethanesulfonic acid, 2-propanolsulfonic acid, 2-sulfoacetic acid, 2-sulfopropionic acid, 3-sulfopropionic acid, sulfosuccinic acid, sulfomethylsuccinic acid, and sulfofumaric acid. , Sulfomaleic acid, 2-sulfobenzoic acid, 3-sulfobenzoic acid, 4-sulfobenzoic acid, 5-sulfosalicylic acid, 4-sulfophthalic acid, 5-sulfoisophthalic acid, 2-sulfoterephthalic acid, phenolsulfonic acid Etc. Specific examples of the inorganic acid include sulfuric acid, hydrochloric acid, sulfamic acid and the like. Of these, sulfuric acid, methanesulfonic acid, sulfosuccinic acid and the like are preferable. The said acid can be normally used individually by 1 type or in mixture of 2 or more types. The acid concentration is about 10 to 400 g / L, preferably about 150 to 200 g / L.

The pH range of the copper-tin alloy plating bath is usually a weakly acidic to strongly acidic range, and specifically, the pH of the plating bath solution is adjusted to 4.5 or less. If the pH is too high, the plating film lacks smoothness, which is not preferable. Moreover, various bases, such as various acids, such as hydrochloric acid and a sulfuric acid, ammonium hydroxide, sodium hydroxide, potassium hydroxide, etc. can be used as a pH adjuster. Further, a pH buffering agent can be added in order to reduce the fluctuation of the pH of the plating bath. Known pH buffering agents can be used. Examples of pH buffering agents include sodium or potassium acetate, sodium borate, potassium or ammonium, sodium or potassium formate, sodium or potassium tartrate, sodium dihydrogen phosphate, potassium or ammonium. These pH adjusting agents and pH buffering agents can be used singly or in combination of two or more.

In the plating bath, additives such as a polymer compound, a surfactant, and a leveler can be added as necessary.

Examples of the polymer compound include polyethylene glycol.

As the surfactant, any of known nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants can be used. These surfactants can be used alone or in combination of two or more, and preferably contain at least one nonionic surfactant.

Nonionic surfactants include, for example, polyoxyalkylene alkyl ether, polyoxyalkylene phenyl ether, polyoxyalkylene naphthyl ether, polyoxyalkylene alkyl ester, polyoxyalkylene sorbitan fatty acid ester, polyoxyalkylene sorbit fatty acid ester, polyethylene glycol Examples include fatty acid esters, polyoxyalkylene glycerin fatty acid esters, and polyoxyalkylene alkylamines. Among these, polyoxyalkylene alkylamine is preferable, and polyoxyethylene alkylamine is more preferable. Examples of the cationic surfactant include tetra-lower alkyl ammonium halide, alkyl trimethyl ammonium halide, alkylamine hydrochloride, alkylamine oleate, and alkylaminoethylglycine. Examples of the anionic surfactant include alkyl-β-naphthalene sulfonic acid, fatty acid soap surfactant, alkyl sulfonate, alkyl sulfate ester salt, polyoxyethylene alkylphenol ether sulfate ester salt and the like. Examples of the amphoteric surfactant include 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, dimethylalkylbetaine, sulfobetaine, N-alkyl-β-aminopropionic acid and the like.

When the polymer compound or surfactant is added to the plating bath, the concentration of the polymer compound or surfactant can be used in the range of about 0.01 to 100 g / L, preferably 0.1 to It is about 40 g / L.

Leveler is an additive that improves smoothness and gloss. As such a leveler, a ketone compound or an aldehyde compound can be used. Known aromatic ketones and aliphatic ketones can be widely used as the ketone compound. Examples of the aromatic ketone include acetophenone, benzophenone, benzalacetone, and the like, and examples of the aliphatic ketone include acetone and diethyl ketone. As the aldehyde compound, known aromatic aldehydes and aliphatic aldehydes can be widely used. Examples of aromatic aldehydes include cinnamaldehyde, α-methylcinnamaldehyde, α-amylcinnamaldehyde, α-hexylcinnamaldehyde, cuminaldehyde, benzaldehyde, anisaldehyde, and aliphatic aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, and the like. Is mentioned. Of these, aromatic ketones and aromatic aldehydes are preferred. These levelers can be used individually by 1 type or in mixture of 2 or more types.

When the leveler is added to the plating bath, the leveler concentration can be used in the range of about 0.01 to 30 g / L, preferably about 0.01 to 10 g / L.

It is preferable to use a surfactant and a leveler in combination as an additive. By using a surfactant and a leveler in combination, the current density region where bright plating can be obtained can be expanded. Thereby, the plating film obtained from the present plating bath can be further smoothed and glossed. As a combination of the surfactant and the leveler, a combination of a nonionic surfactant and an aromatic ketone or an aromatic aldehyde is preferable. As the nonionic surfactant, polyoxyethylene alkylamine is preferable. A plating film having an excellent gloss appearance can be obtained by further adding a nonionic surfactant and an aromatic ketone or aromatic aldehyde to the plating bath.

When a surfactant and a leveler are used in combination, the surfactant concentration is about 0.1 to 40 g / L, the leveler concentration is about 0.01 to 10 g / L, and the ratio of surfactant to leveler is set. Is preferably about 1: 1 to 100: 1.

If necessary, additives other than those described above, for example, a stress reducing agent, a conductive auxiliary agent, an antifoaming agent, a brightening agent, and the like can be appropriately selected and added to the plating bath.

Examples of the stress reducing agent include naphthol sulfonic acid, saccharin, sodium 1,5-naphthalenedisulfonate, and the like. These can be used individually by 1 type or in mixture of 2 or more types. Examples of the conductive auxiliary agent include acids such as hydrochloric acid, sulfuric acid, acetic acid, nitric acid, sulfamic acid, pyrophosphoric acid, and boric acid, and ammonium salts, sodium salts, potassium salts, and organic amine salts thereof. These can be used individually by 1 type or in mixture of 2 or more types. As the antifoaming agent and brightening agent, commercially available products for copper plating, tin plating, copper-tin alloy plating and general plating can be appropriately selected and used.

The method for constructing the plating bath of the present invention is not particularly limited. For example, a water-soluble copper compound and a water-soluble divalent tin compound are dissolved in an aqueous solution in which an acid such as sulfuric acid is dissolved, and then a complexing agent and a reducing agent are blended, and other additives are blended as necessary. Finally, the intended plating solution can be obtained by adjusting to a predetermined pH.

The plating bath of the present invention is not particularly limited in plating method, can be used in a known plating method, and can cope with barrel plating in which the current density varies greatly.

When the bath temperature during plating is low, the throwing power improves, but the film-forming speed tends to decrease. Conversely, when the bath temperature is high, the film-forming speed increases, but the low current density. Since the throwing power to the region tends to decrease, an appropriate bath temperature can be determined in consideration of this point. The bath temperature is preferably in the range of about 5 to 40 ° C.

The cathode current density can also be appropriately determined according to the plating solution used, the type of the object to be plated, and the like, and is preferably about 0.1 to 3 A / dm ² .

Anodes include soluble anodes (eg, tin anodes, phosphorous copper anodes, oxygen-free copper anodes, copper-tin alloy anodes), insoluble anodes (eg, stainless steel anodes, carbon anodes, lead anodes, lead-tin alloy anodes, Use a known anode that can be used for copper-tin alloy plating such as lead-antimony alloy anode, platinum anode, titanium anode, titanium-platinum anode, oxide-coated anode such as iridium oxide-coated titanium electrode) Can do. An object to be plated, which will be described later, is used for the cathode. Therefore, it can be said that the copper-tin alloy plating method of the present invention is an electrolysis method using the object to be plated as a cathode in the above-described copper-tin alloy plating bath.

The above-described copper-tin plating film is formed on the surface of the article to be plated by the plating method described above. The alloy composition of the obtained film is Cu: Sn = 95: 5 to 5:95 by weight, and the alloy composition can be easily changed by changing the Cu concentration or the Sn concentration in the plating solution. The article to be plated can be used without particular limitation as long as the surface has conductivity and is smooth. For example, various articles | goods, such as household appliances, faucet metal fittings, miscellaneous goods, decorations, and accessories, are mentioned.

The copper-tin alloy plating bath of the present invention can be suitably used for plating for clothing or ornaments, plating of electronic or electrical parts, etc., but is not limited to any other use. .

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples.

Using the plating baths having the compositions shown in Tables 1 to 6 below, plating was performed under the following conditions to form a plating film on the object to be plated.
Object to be plated: Iron plate (5cm x 5cm)
Plating method: Anode Pure tin plate (2 x 10cm x 5cm)
Liquid volume 1.5L (using 14cm x 8cm x 18cm plastic container)
Stirring Oscillating plating condition with cathode rocker: Temperature 18 ~ 20 ℃
Current density 1A / dm ²
Electrolysis time 25 minutes

Tables 1 to 6 show the state of the plating solution and the characteristics of the plating film formed as described above. The evaluation method of each characteristic is as follows.
Solution state: visually confirmed Solution stability: visually confirmed plating solution after standing for 24 hours Plated appearance and crack generation: observed with digital microscope Cu: Sn ratio: with fluorescent X-ray film thickness measuring instrument Evaluation

In addition, for the plating baths of Example 3 and Comparative Examples 11 and 12, plating was performed by performing plating treatment with current densities of 0.01, 0.1, 0.5, 1, ² and 3 A / dm ^2. The copper content of the film was determined. The result is shown in FIG.

From the results in Tables 1 to 5, precipitation does not occur in the plating baths of Examples 1 to 50, and in particular, the plating baths of Examples 1 to 5, 10 to 31, 34 to 42, and 45 to 50 have a stable liquid state. It can be seen that a plating film without cracks can be obtained by plating. From the results of Examples 1 to 5 in Table 1, it can be seen that copper-tin alloy plating at an arbitrary ratio can be obtained by adjusting the metal concentration in the plating solution. From the results in Tables 3 to 5, it can be seen that the addition of a surfactant or leveler to the plating solution increases the gloss of the plating appearance, and when both are added, a plating appearance having an excellent gloss can be obtained. Further, FIG. 1 shows that the plating bath of the present invention has less influence on the alloy ratio of the current density than the conventional acidic bath (Comparative Example 12).

Claims

Water-soluble copper compound, water-soluble divalent tin compound, general formula (1):
R— (CH 2 ) 1 —S— (CH 2 ) m —S— (CH 2 ) n —R (1)
(Wherein R is H, OH or SO 3 Na, and l, m and n are each independently an integer of 0 to 3), and an aromatic compound having a hydroxyl group A copper-tin alloy plating bath comprising an aqueous solution containing
The water-soluble copper compound is 1 to 60 g / L in terms of copper ion, the water-soluble divalent tin compound is 5 to 40 g / L in terms of divalent tin ion, the sulfur-containing compound is 5 to 500 g / L, and the hydroxyl group is The copper-tin alloy plating bath according to claim 1, which contains 1 to 50 g / L of an aromatic compound having the same.
The sulfur-containing compound is methanedithiol, 1,2-ethanedithiol, 1,3-propanedithiol, 3,6-dithia-1,8-octanediol, and 3,3′-dithiobis (sodium 1-propanesulfonate) The copper-tin alloy plating bath according to claim 1 or 2, which is at least one selected from the group consisting of:
The aromatic compound having a hydroxyl group is at least one selected from the group consisting of phenol, catechol, hydroquinone, resorcinol, pyrogallol, p-cresolsulfonic acid, sodium ascorbate, and sodium erythorbate. 4. The copper-tin alloy plating bath according to any one of 3 above.
5. The copper-tin alloy plating bath according to claim 1, wherein the aqueous solution further contains a nonionic surfactant and an aromatic ketone or an aromatic aldehyde.
A copper-tin alloy plating method in which electrolysis is carried out using the object to be plated as a cathode in the copper-tin alloy plating bath according to any one of claims 1 to 5.
An article in which a copper-tin alloy plating film is formed by the method according to claim 6.