JP5366076B2 - Electroplating bath for porous plating film containing additive for forming porous plating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a homogeneous and excellent porous coating film by carrying out an inexpensive process applied to various base materials without using a specific apparatus. <P>SOLUTION: The additive for an electroplating bath for forming the porous plating film comprises a water soluble quaternary ammonium compound having hydrophobic group. The method of forming the porous plating film is carried out by electroplating in the electroplating bath containing the additive. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an additive for forming a porous plating film and a method for forming a porous plating film.

  The metal porous body has high utility value as a functional material because of its large specific surface area and excellent substance retention, and many reports have been made on its production method.

  For example, as a method for producing a metal porous body, a general method is a method of sintering fine metal, a method of conducting electroplating after making a porous resin conductive, and the like.

  However, these methods all require special equipment, and the form of the metal porous body to be obtained is limited.

In addition, as another method for forming a metal porous film, a method of electrodepositing a metal using an electrolytic solution to which an additive composed of an electrolyte combining a cation and an anion having high ion mobility is added (Patent Document 1). And a method of forming a metallic copper film by an electroless plating method using an electroless plating solution containing an acetylene group-containing compound (see Patent Document 2) and the like.
JP-A-6-65779 JP-A-10-237664

  The present invention has been made in view of the current state of the prior art described above, and its main purpose is applicable to various materials and can be implemented at low cost without using a special device. It is an object of the present invention to provide a method capable of forming a uniform and good porous film by such a method.

  The present inventor has intensively studied to achieve the above-described object. As a result, when forming a plating film on a conductive substrate using an electroplating method, a water-soluble quaternary ammonium compound having a hydrophobic group is added to the plating bath to obtain a homogeneous and good porous material. The present inventors have found that a plating film can be easily formed and completed the present invention.

That is, this invention provides the electroplating bath for porous plating film formation containing the following additive for porous plating film formation .
1. The following general formula

(In the formula, R ^{1 to} R ⁴ are the same or different and are a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, and X ⁻ is an anion. In addition, two of R ^{1 to} R ⁴ Or three of them may combine to form a heterocyclic ring with a nitrogen atom, provided that at least one of R ^{1 to} R ⁴ is an alkyl group having 6 or more carbon atoms, an aryl group, or an aralkyl group. An electroplating bath for forming a porous plating film containing 0.001 to 0.1 mol / L of an additive for forming a porous plating film made of a water-soluble quaternary ammonium compound having a hydrophobic group.

  In the present invention, a water-soluble quaternary ammonium compound having a hydrophobic group is used as an additive blended in the plating solution.

  By using such an electroplating bath to which a water-soluble quaternary ammonium compound is added to form a plating film by an electroplating method, a plating film having a homogeneous porous structure can be easily formed.

  The reason why the porous plating film can be formed by using the electroplating bath to which the above ammonium compound is added is not necessarily clear, but is presumed as follows.

  That is, the above-described ammonium compound forms a soluble ammonium cation in the plating solution, and is attracted to the cathode during electroplating and is reduced and decomposed at the cathode interface. At this time, the water-insoluble hydrophobic substituent is liberated, and the liberated substance is water-insoluble, so that it hardly diffuses in the plating solution and remains on the surface of the object to be plated. The remaining free substance acts like a kind of plating resist and hinders the growth of the plating film in that portion. As a result, it is considered that a plating film having many fine holes is formed.

  The water-soluble quaternary ammonium compound having a hydrophobic group used in the present invention is not particularly limited, and has a water-solubility quaternary ammonium compound in which at least one substituent bonded to a nitrogen atom is a hydrophobic group. If it is. Examples of the water-soluble ammonium compound include halides such as chlorides and bromides, hydroxides, sulfates, nitrates, and the like. In addition, a compound having a heterocyclic structure such as a water-soluble pyridinium salt is also included in the quaternary ammonium compound.

  As a preferable example of the water-soluble quaternary ammonium compound having a hydrophobic group used in the present invention, the following general formula

(In the formula, R ^{1 to} R ⁴ are the same or different and are a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, and X ⁻ is an anion. In addition, 2 in R ^{1 to} R ⁴ Or 3 or 3 may combine to form a heterocyclic ring with a nitrogen atom, provided that at least one of R ^{1 to} R ⁴ is an alkyl group having 6 or more carbon atoms, an aryl group, or an aralkyl group. The quaternary ammonium compound represented can be mentioned.

In the above ammonium compound, examples of the alkyl group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl. , Dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl and the like C ₁ -C ₂₀ alkyl group having a straight chain or a branch. Among these, examples of the alkyl group having 6 or more carbon atoms include hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl and the like.

  Examples of the aryl group include a phenyl group and a naphthyl group. Aryl groups such as fluorine and chlorine atoms; alkyl groups such as methyl and ethyl; haloalkyl groups such as trifluoromethyl; alkoxy groups such as methoxy and ethoxy; and substituents such as aryl groups such as phenyl are bonded to the aryl group. You may do it. The number of substituents and the substitution position are not particularly limited, and may be in a range that does not hinder the effects of the present invention.

Examples of the aralkyl group include C _{7 to} C ₁₀ aralkyl groups such as 2-phenylethyl, benzyl, 1-phenylethyl, 3-phenylpropyl, 4-phenylbutyl, and the like. The same substituent as the aryl group may be bonded to the aralkyl group.

Examples of the compound in which two or three of R ^{1 to} R ⁴ are bonded to form a heterocyclic ring with a nitrogen atom include compounds having a biridinium ring.

The anion represented by X ⁻ may be any anion that can form a water-soluble ammonium compound. For example, Cl ⁻ , Br ⁻ , (SO ₄ ²⁻ ) _1/2 , OH ⁻ , NO ₃ ⁻ Etc. can be illustrated.

In the above-described ammonium compound, at least one of R ^{1 to} R ⁴ needs to be an alkyl group having 6 or more carbon atoms, an aryl group, or an aralkyl group.

  Specific examples of ammonium compounds that can be used in the present invention include dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, octadecyltrimethylammonium chloride, phenyltrimethylammonium chloride, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, Benzyltributylammonium chloride, didecyldimethylammonium chloride, dodecyldimethylbenzylammonium chloride, tetradecyldimethylbenzylammonium chloride, octadecyldimethylbenzylammonium chloride, trioctylmethylammonium chloride, dodecylpyridinium chloride Benzyl pyridinium chloride, these bromides, etc. sulfates can be exemplified. These ammonium compounds can be used singly or in combination of two or more.

  In the present invention, the addition amount of the ammonium compound in the plating solution is not particularly limited, but if the addition amount is small, a sufficient number of pores cannot be obtained, so a good porous film cannot be formed, On the other hand, when the addition amount is too large, precipitation unevenness occurs and it becomes difficult to obtain a uniform film. For this reason, the addition amount of the ammonium compound in the plating solution is preferably about 0.001 to 0.1 mol / L, and more preferably about 0.005 to 0.05 mol / L.

  There are no particular limitations on the type of plating bath that can be used in the present invention. By adding the quaternary ammonium compound described above to various known electroplating baths, a uniform and good porous plating film can be formed. . Such plating solutions include electroplating nickel baths such as watt bath, wood bath, nickel sulfamate bath, organic acid nickel bath, copper sulfate bath, copper pyrophosphate bath, tin sulfate bath, tin methanesulfonate Examples thereof include a bath, a zinc chloride bath, a zinc sulfate bath, and various alloy plating baths.

  The composition of these electroplating baths is not particularly limited and may be the same as that of known plating baths.

  Hereinafter, a preferable composition range and plating conditions of a nickel plating bath applicable to the method for forming a porous plating film of the present invention will be described.

1. Watt bath composition and plating conditions
Nickel sulfate (NiSO ₄・ 6H ₂ O) 200 ~ 380g / L
Nickel chloride [NiCl ₂・ 6H ₂ O] 30 ~ 70g / L
Boric acid [H ₃ BO ₃ ] 30-45 g / L
pH 3.0-4.8
Bath temperature 40-70 ° C
Cathode current density 0.5-10A / dm ²
2. Composition and plating conditions of sulfamic acid bath
Nickel sulfamate [Ni (NH ₂ SO ₃ ) ₂ / 4H ₂ O] 300 to 500 g / L
Nickel chloride [NiCl ₂・ 6H ₂ O] 0 ~ 30g / L
Nickel bromide [NiBr ₂・ 3H ₂ 0] 10-12g / L
Boric acid [H ₃ BO ₃ ] 30-50g / L
pH 3.5-4.5
Bath temperature 25-70 ° C
Cathode current density ² ~ 40A / dm ²
3. Citric acid bath composition and plating conditions
Nickel sulfate (NiSO ₄・ 6H ₂ O) 200 ~ 380g / L
Nickel chloride [NiCl ₂・ 6H ₂ O] 30 ~ 70g / L
Citric acid 12-21g / L
Or Trisodium citrate 24-30g / L
pH 3.0-5.0
Bath temperature 40-70 ° C
Cathode current density 0.5-10A / dm ²
4). Wood bath composition and plating conditions
Nickel chloride (NiCl ₂・ 6H ₂ O) 200 ~ 300g / L
35% hydrochloric acid 50-150ml / L
Bath temperature 20-30 ℃
Cathode current density 5 ~ 10A / dm ²
Moreover, the preferable composition range and plating conditions of a copper pyrophosphate bath are described as an example of a copper plating bath.
5. Plating conditions for copper pyrophosphate bath Range
Copper pyrophosphate [Cu ₂ P ₂ 0 ₇・ 3H ₂ O] 70 to 110 g / L
Potassium pyrophosphate [K ₄ P ₂ 0 ₇ ] 260-400 g / L
28% ammonia water [NH ₄ OH] 2-4ml / L
P ratio (P ₂ 0 ₇ / Cu) 6.5 to 8.0
pH 8.2-8.9
Bath temperature 50-60 ℃
Cathode current density 0.5-5A / dm ²

  According to the present invention, a uniform and good porous film can be formed using various electroplating baths by a relatively simple method called electroplating without requiring special equipment.

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

Example 1
For the formation of a porous plating film by adding 0.02 mol / L of dodecyltrimethylammonium chloride to a watt bath composed of an aqueous solution of pH 4.2 containing nickel sulfate 280 g / L, nickel chloride 45 g / L, and boric acid 40 g / L A nickel plating bath was prepared.

As the object to be plated, a steel plate on which a strike nickel film having a thickness of 3 μm was formed using a Watt bath was immersed in the above-described nickel plating bath for forming a porous plating film. Plating was performed at 50 ° C. and a cathode current density of 5 A / dm ² for 1 minute.

  The test piece after plating showed water repellency, and it was confirmed that a water-insoluble substance released from dodecyltrimethylammonium chloride remained. FIG. 1 shows a scanning electron micrograph of the surface of the plating film that has been thoroughly washed with pure water and then dried by heating. As is clear from FIG. 1, a large number of micropores were observed on the surface of the plating film, and it was confirmed that a porous nickel plating film was formed.

Example 2
A nickel plating bath for forming a porous plating film was prepared by adding 0.03 mol / L of dodecyldimethylbenzylammonium chloride to the same Watt bath as in Example 1.

As the object to be plated, a steel plate on which a 3 μm strike nickel film similar to that in Example 1 was formed was immersed in the above-described nickel plating bath for forming a porous plating film, and the liquid temperature was 55 without stirring. Plating was carried out at a cathode current density of 2 A / dm ² for 3 minutes.

  The test piece after plating showed water repellency, and it was confirmed that a water-insoluble substance remained free from dodecyldimethylbenzylammonium chloride. FIG. 2 shows a scanning electron micrograph of the surface of the plating film that has been thoroughly washed with pure water and then dried by heating. As is clear from FIG. 2, a large number of micropores were observed on the surface of the plating film, and it was confirmed that a porous nickel plating film was formed.

Example 3
Porous plating film by adding 0.05 mol / L of benzyltriethylammonium chloride to nickel sulfamate bath consisting of aqueous solution of pH 4.0 containing nickel sulfamate 450g / L, nickel bromide 10g / L and boric acid 30g / L A forming nickel plating bath was prepared.

As the object to be plated, a steel plate on which a strike nickel film of 3 μm similar to that in Example 1 was used was immersed in the above-described nickel plating bath for forming a porous plating film, and the liquid temperature was kept under air agitation. Plating was performed at 45 ° C. and a cathode current density of 3 A / dm ² for 2 minutes.

  The test piece after plating showed water repellency, and it was confirmed that a water-insoluble substance was released from benzyltriethylammonium chloride. FIG. 3 shows a scanning electron micrograph of the surface of the plating film that has been thoroughly washed with pure water and then dried by heating. As is clear from FIG. 3, a large number of micropores were observed on the surface of the plating film, and it was confirmed that a porous nickel plating film was formed.

Example 4
For forming a porous plating film by adding 0.1 mol / L of benzylpyridinium chloride to a citrate bath consisting of an aqueous solution of pH 4.0 containing 280 g / L of nickel sulfate, 45 g / L of nickel chloride, and 21 g / L of citric acid A nickel plating bath was prepared.

As the object to be plated, a steel plate with a 3 μm strike nickel film similar to that used in Example 1 was used. The steel sheet was immersed in the above-described nickel plating bath for forming a porous plating film. Plating was carried out for 5 minutes at a cathode current density of 3 A / dm ² at ° C.

  The test piece after plating showed water repellency, and it was confirmed that water-insoluble substances released from benzylpyridinium chloride remained. FIG. 4 shows a scanning electron micrograph of the surface of the plating film that has been thoroughly washed with pure water and then dried by heating. As is clear from FIG. 4, a large number of micropores were observed on the surface of the plating film, and it was confirmed that a porous nickel plating film was formed.

Example 5
A nickel plating bath for forming a porous plating film was prepared by adding 0.01 mol / L of phenyltrimethylammonium chloride to the same Watt bath as in Example 1.

As the object to be plated, a steel plate on which a 3 μm strike nickel film similar to that in Example 1 was formed was immersed in the above-described nickel plating bath for forming a porous plating film, and the liquid temperature was 55 without stirring. Plating was performed for 1 minute at a cathode current density of 5 A / dm ² at ° C.

  The test piece after plating showed water repellency, and it was confirmed that water-insoluble substances remaining from phenyltrimethylammonium chloride remained. FIG. 5 shows a scanning electron micrograph of the surface of the plating film that has been thoroughly washed with pure water and then dried by heating. As is clear from FIG. 5, a large number of micropores were observed on the surface of the plating film, and it was confirmed that a porous nickel plating film was formed.

Example 6
Benzyltrimethylammonium hydroxide 0.05 mol / neutralized with polyphosphoric acid in a copper pyrophosphate bath consisting of an aqueous solution of pH 8.8 containing copper pyrophosphate 94 g / L, potassium pyrophosphate 340 g / L and 28% aqueous ammonia 3 ml / L L was added to prepare a copper plating bath for forming a porous plating film. As the object to be plated, a rolled copper plate is used, which is immersed in the copper plating bath for forming the above-mentioned porous plating film and plated for 1 minute at a liquid temperature of 55 ° C. and a cathode current density of 3 A / dm ² without stirring. went.

  The test piece after plating showed water repellency, and it was confirmed that a water-insoluble substance was released from benzyltrimethylammonium hydroxide. FIG. 6 shows a scanning electron micrograph of the surface of the plating film that has been thoroughly washed with pure water and then dried by heating. As is apparent from FIG. 6, a large number of micropores were observed on the surface of the plating film, and it was confirmed that a porous copper plating film was formed.

The scanning electron micrograph of the surface of the porous nickel plating film obtained in Example 1. 3 is a scanning electron micrograph of the surface of the porous nickel plating film obtained in Example 2. FIG. 4 is a scanning electron micrograph of the surface of the porous nickel plating film obtained in Example 3. FIG. A scanning electron micrograph of the surface of the porous nickel plating film obtained in Example 4. 4 is a scanning electron micrograph of the surface of the porous nickel plating film obtained in Example 5. FIG. The scanning electron micrograph of the surface of the porous nickel plating film obtained in Example 6.

Claims (1)

The following general formula

(In the formula, R ^{1 to} R ⁴ are the same or different and are a hydrogen atom, an alkyl group, an aryl group or an aralkyl group, and X ⁻ is an anion. In addition, two of R ^{1 to} R ⁴ Or three of them may combine to form a heterocyclic ring with a nitrogen atom, provided that at least one of R ^{1 to} R ⁴ is an alkyl group having 6 or more carbon atoms, an aryl group, or an aralkyl group. An electroplating bath for forming a porous plating film containing 0.001 to 0.1 mol / L of an additive for forming a porous plating film made of a water-soluble quaternary ammonium compound having a hydrophobic group.

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