JP3365866B2 - Non-cyanide precious metal plating bath - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a noble metal plating bath such as a gold plating bath and a silver plating bath, and more particularly to a non-cyanide noble metal plating bath that does not use a cyan compound.

[0002]

2. Description of the Related Art Cyan-based baths have long been known as precious metal plating baths such as gold and silver plating baths. This cyan-based noble metal plating bath is excellent in terms of the density of deposited metal crystals, uniform electrodeposition, and ease of bath management.
In addition to ornaments, it is also widely used in precious metal plating for semiconductor components and printed circuit boards.

However, since these plating baths use cyanide, which is highly toxic, the working environment,
There were many problems in terms of environmental protection and wastewater treatment.

[0004]

Therefore, it is required to provide a noble metal plating bath which is equivalent to a conventional cyanide-based plating bath in terms of deposition film and bath management without using a cyanide-based compound. It was

[0005]

Means for Solving the Problems The inventors of the present invention have made extensive studies on a noble metal plating bath that does not use a cyanide compound, and found that a nonionic surfactant was added to an acidic noble metal plating bath that utilizes alkanesulfonic acid. It was discovered that a noble metal film equivalent to a cyan-based noble metal can be obtained by adding the above.

That is, the present invention relates to the following three components (a)-
(C) (a) One or more precious metal ions selected from the group consisting of Au ⁺ and Ag ⁺ (b) At least one or more alkane sulfonate ions or alkanol sulfonate ions (c) Nonionic surfactant Contains succinimide or
Provides a non-cyanic noble metal plating bath free of its derivatives and potassium iodide.

The monovalent gold ion and the monovalent silver ion as the component (a) of the present invention can be obtained by dissolving a water-soluble gold salt or a water-soluble silver salt in water. Preferred water-soluble gold salts include gold methane sulfonate, gold ethane sulfonate, gold isopropanol sulfonate, gold chloride, and the like.
Examples of the water-soluble silver salt include silver methanesulfonate, silver ethanesulfonate, silver isopropanolsulfonate, silver oxide, silver chloride, silver nitrate and the like. The concentration of the component (a) in the bath is preferably 0.5 to 30 g / l.

The alkane sulfonic acid or alkanol sulfonate ion, which is the component (b) of the present invention, has the action of making the bath acidic and keeping the metal ions in the bath stable. As the alkane sulfonic acid and alkanol sulfonic acid used for preparing the component (b), methane sulfonic acid, ethane sulfonic acid and the like and isopropanol sulfonic acid are preferable.

When the water-soluble gold salt or the water-soluble silver salt is an alkane sulfonate or an alkanol sulfonate, these acid ions may be the same as or different from the acid group of those salts. It may exist, or two or more kinds may be used in combination. The concentration of component (b) in the bath is about 5 to 3
00 g / l is suitable.

Further, the nonionic surfactant which is the component (c) of the present invention is used for obtaining a dense and smooth plated surface with good adhesion.

Specific preferred examples of the component (c) include those containing a compound represented by any one of the following general formulas (1) to (4) as a main component.

[Chemical 2]

[Wherein R ₁ is an aliphatic alcohol having 8 to 22 carbon atoms, phenol substituted with an alkyl group having 1 to 25 carbon atoms, β substituted with alkyl having 1 to 25 carbon atoms]
-Naphthol, alkoxylated phosphoric acid having 1 to 25 carbon atoms, sorbitan esterified with fatty acid having 8 to 22 carbon atoms or styrenated phenol (the hydrogen of the phenol nucleus is substituted with an alkyl group having 1 to 4 carbon atoms or a phenyl group) R ₂ is a carbon atom having a carbon number of 8 or less.
To 18 alkyl groups, R ₃ and R _{4 each} represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and A represents —CH ₂ CH ₂ O.
- a, B represents a _{-CH 2 CH (CH 3) O-} , m 1 and n ₁ is 0 to 30 _{integer, m 2, n 2, m} 3 and n ₃ 0
40 integers, m ₄ and n ₄ is 0-20 of integer respectively. However, m ₁ and n ₁ , m ₂ and n ₂ , m ₃ and n _3, and m ₄ and n ₄ do not become 0 at the same time, and m ₁ ~
m ₄ and n _{1 to} n ₄ mean the total number of substituents,
The positions where A and B are present are not limited]

These nonionic surfactants are all corresponding aliphatic alcohols, substituted phenols, alkyl-substituted β-naphthols, alkoxylated phosphoric acids, esterified sorbitans, styrenated phenols, ethylenediamines, monoalkylamines, It can be prepared by adding a predetermined number of moles of ethylene oxide and / or propylene oxide to an alkyl-substituted diphenol, but it is also easily available as a commercial product.

As an example of a commercially available product, the one represented by the above formula (1) is pull lafac LF401 (BASF
(Manufactured by Asahi Denka Kogyo Co., Ltd.) and the like, and those represented by formula (3) are those represented by formula (2).
Examples of the compound represented by the formula (4) such as 207 (manufactured by NOF Corporation) include Liponox NC-100 (manufactured by Lion Corporation).

The surfactant as the component (c) may be used in combination of two or more kinds of the above (1) to (4), and the concentration in the plating bath becomes about 0.1 to 50 g / l. It is desirable to use A particularly preferred concentration is about 0.5-20 g / l.

In the non-cyanide noble metal plating bath of the present invention, after the components (a) and (b) in the bath are adjusted to a predetermined concentration,
It is prepared by adding the component (c). More specifically, in an aqueous solution acidified with alkanesulfonic acid, alkanolsulfonic acid or the like, the above water-soluble gold salt or water-soluble silver salt is added and sufficiently dissolved to a predetermined concentration,
It is prepared by adding a nonionic surfactant which is the component (c).

To perform precious metal plating using the thus obtained non-cyanide precious metal plating bath of the present invention, for example,
The cathode electric density is about 0.01 to 100 A / dm ² (preferably about 0.1 to 60 A / dm ² ), and the bath temperature is about 10 to 80 ° C.
It is suitable to set the conditions at about (preferably about 15 to 70 ° C.). In addition, an insoluble electrode or the like can be used as the anode.

The gold plating or silver plating film obtained from the above non-cyanide noble metal plating bath has the same degree of compactness as the gold plating or silver plating film obtained by the conventional cyan-based noble metal plating bath. Parts terminals,
It can be used as a plating bath for decorative wiring as well as a plating bath for printed wiring boards.

[0019]

EXAMPLES Examples, comparative examples and test examples will be shown below.
The present invention will be described. Example 1 A non-cyanide gold plating bath was prepared with the following composition. (Composition) Gold ethanesulfonic acid (I) 10 g / l Ethanesulfonic acid (free acid) 100 g / l Nonylphenol ethoxylate 5 g / l Ethylene oxide 16 mol adduct

Example 2 A non-cyanide gold plating bath was prepared with the following composition.    (Composition)   Gold (I) methanesulfonate 20 g / l   Methanesulfonic acid (free acid) 80 g / l   Ethylene diamine ethylene oxide 10 g / l     48 mol, propylene oxide 44     Molar adduct

Example 3 A non-cyanate silver plating bath was prepared according to the following composition. (Composition) Silver (I) methanesulfonate 19 g / l Methanesulfonic acid (free acid) 120 g / l Octylphenol ethoxylate 5 g / l Ethylene oxide 10 mol adduct A plating bath having the above composition was prepared, Plating was performed in the same manner as in Example 1.

Example 4 A non-cyanic silver plating bath was prepared with the following composition. (Composition) Silver (I) ethanesulfonate 5 g / l Ethanesulfonic acid (free acid) 200 g / l Ethylene oxide 2 g / l 8 mol adduct of dodecylamine A plating bath having the above composition was prepared and used in Examples. Plating was performed in the same manner as 1.

Comparative Example 1 A non-cyanide gold plating bath was prepared in the same manner as in Example 1 except that no surfactant was added to the plating bath.

Comparative Example 4 Example 4 except that ethanesulfonic acid was not added to the plating bath.
A non-cyanic silver plating bath was prepared in the same manner as in.

Test Example Using the plating baths of Examples 1 to 4 and Comparative Examples 1 and 2 described above, a 30 mm × 10 mm copper plate was plated under the following conditions. With respect to the obtained plated copper plate, the denseness of the crystal was visually inspected. The results are shown in Table 1.

(Plating conditions) Cathode current density 2 A / dm ² bath temperature 50 ° C. stirring stirring stirrer stirring film thickness 3 μm

(Result)

* Evaluation criteria ◎: Fine crystals ○: Slightly fine crystal ×: Coarse deposition and almost no plating film

[0029]

The noble metal coating obtained by the non-cyanide noble metal plating bath of the present invention exhibits the same crystal compactness as conventional cyan-based noble metal coatings. Since the non-cyanide noble metal plating bath of the present invention does not contain cyanide, which adversely affects the human body, it is more advantageous than the conventional non-cyanide bath in terms of work environment, environmental protection, wastewater treatment and the like. that's all

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-2-290993 (JP, A) JP-A-52-150745 (JP, A) JP-A-7-166391 (JP, A) JP-B-45- 31367 (JP, B1) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C25D 3/48 C25D 3/46

Claims (2)

(57) [Claims] 1. At least one of the following three components (a) to (c) (a) a precious metal ion selected from the group consisting of Au ⁺ and Ag ⁺ (b) at least an alkane sulfonate ion or an alkanol sulfonate ion. Also, a non-cyanic noble metal plating bath containing at least one (c) nonionic surfactant and containing no succinimide or its derivative and potassium iodide. 2. The nonionic surfactant comprises the following (1) to
(4) [Chemical formula 1] [In the formula, R ₁ represents an aliphatic alcohol having 8 to 22 carbon atoms,
A phenol substituted with an alkyl group having 1 to 25 carbon atoms,
Β-naphthol substituted with alkyl having 1 to 25 carbons, alkoxylated phosphoric acid having 1 to 25 carbons, 8 carbons
Obtained by removing hydrogen atoms of hydroxyl groups from sorbitan or styrenated phenol esterified with ~ 22 fatty acid (the hydrogen of the phenol nucleus may be substituted with an alkyl group having 1 to 4 carbon atoms or a phenyl group) Represents a residue or a hydrogen atom, R ₂ represents an alkyl group having 8 to 18 carbon atoms, and R ₃ and R ₄ represent a hydrogen atom or 1 to 1 carbon atom.
Indicates 5 alkyl group, A is a _-CH 2 _CH 2 O-, B
Represents —CH ₂ CH (CH ₃ ) O—, m ₁ and n ₁
Is an integer of 0 to 30, m ₂ , n ₂ , m ₃ and n ₃ are 0
40 integers, _{m 4} and _{n 4} are respectively an integer of 0 to 20. However, m ₁ and n ₁ , m ₂ and n ₂ , m ₃ and n ₃
And m ₄ and n ₄ are not 0 at the same time, m _{1 to} m ₄ and n _{1 to} n ₄ mean the total number in the substituents, and the positions where A and B are present are not limited]. The non-cyanide precious metal plating bath according to claim 1, which is selected from the group consisting of: