WO2020013188A1

WO2020013188A1 - Base metal plating film

Info

Publication number: WO2020013188A1
Application number: PCT/JP2019/027165
Authority: WO
Inventors: 智明間彦; 浩一梅本; 晃人吉田
Original assignee: 株式会社ダイセル
Priority date: 2018-07-12
Filing date: 2019-07-09
Publication date: 2020-01-16
Also published as: JP2024051133A; JPWO2020013188A1

Abstract

The present invention provides a base metal plating film which comprises a base metal matrix and hydrophilic diamond nanoparticles that are dispersed in the base metal matrix.

Description

Base metal plating film

The present invention relates to a base metal plating film, a base metal plating bath, a method for producing the base metal plating film, an electronic component having the base metal plating film, a brightening agent for the base metal plating film, and an antioxidant for the base metal plating film.

において In this specification, “nano diamond” may be described as “ND”.

Among the connecting parts such as low-current (signal-related) switches and connectors used in electric and electronic equipment, connecting parts that are repeatedly used with low contact load require high connection reliability. A connection component in which the surface of a conductive metal member is plated with a metal such as a noble metal is used. In some cases, the plating film is required to have appropriate gloss in addition to conductivity.

Patent Document 1 discloses that a carbon-based fine particle such as a carbon nanotube is dispersed in a water-insoluble solvent and then a copper ion or the like is obtained in order to obtain a high-quality and highly reliable plating film composited with the carbon-based fine particle. There is disclosed a method for producing a plating bath in which a water-insoluble solvent is added to a metal salt aqueous solution containing a base metal ion and stirred to disperse the carbon-based fine particles in the base metal salt aqueous solution. It is said that by using a plating bath produced by this method, an electronic component in which contamination of impurities is suppressed can be obtained. However, this method cannot impart high gloss to the plating film. Base metals are also susceptible to air oxidation.

As a method of imparting gloss to the plating film, a brightener having an action of refining crystals by adsorbing on crystal nuclei and inhibiting crystal growth is added to the plating bath, so that the surface of the deposited noble metal is removed. 2. Description of the Related Art Smoothing to give gloss is performed (for example, see Patent Document 2).

Non-Patent Document 1 proposes adding nanodiamond particles to a plating bath to incorporate the nanodiamond particles into a plating film. However, since the nanodiamond particles are not sufficiently dispersed in a plating solution, the nanodiamond particles are not sufficiently dispersed in a plating solution. It is described that the nano diamond particles are aggregated to the order of μm.

Patent Literature 3 describes a configuration in which diamond fine particles having a hydrophilic polymer or an ionic functional group introduced therein are added to a metal plating solution together with a surfactant. In Example 1, 1 g / L of anionic functional group-introduced diamond fine particles was added. Example 2 describes a configuration in which a dispersion containing 2 g / L is added and a dispersion containing 1 g / L of PEG-introduced diamond microparticles is added at a rate of 0.1 g / L in Example 2. With the amount, improvement in the glossiness and oxidation resistance of the plating film cannot be expected.

Patent Document 4 discloses a configuration in which a hydrophilic polymer or an ionic functional group is introduced, diamond fine particles having an average particle diameter of 10 nm to 300 nm, fluorine resin fine particles having an average particle diameter of 100 nm to 300 nm, and a surfactant are added to the metal plating solution. The electroless composite plating solution containing 2.0 g / L of the grafted diamond particles is described in Examples 1 and 2. However, the plating solution containing such a high concentration of the diamond particles has a gloss of the plating film. No improvement in oxidation resistance can be expected.

WO2011 / 048984 JP 2015-117424 A JP 2011-149071 A JP 2012-092416 A

An object of the present invention is to provide a base metal plating film having high glossiness and oxidation resistance and a method for producing the same.

Another object of the present invention is to provide a base metal plating bath useful for producing a base metal plating film having high gloss and oxidation resistance.

Another object of the present invention is to provide an electronic component provided with a base metal plating film having high gloss, surface hardness, conductivity and oxidation resistance.

Another object of the present invention is to provide a novel brightening agent that imparts high gloss to a base metal plating film.

Another object of the present invention is to provide a novel antioxidant that imparts oxidation resistance to a base metal plating film.

The present inventors have conducted intensive studies to solve the above-described problems. As a result, when the base metal plating is performed using a plating bath containing a base metal ion and to which hydrophilic nanodiamond particles are added, a high glossiness and oxidation resistance are obtained. It has been found that a base metal plating film having excellent properties can be obtained.

The present invention provides a base metal plating film, a base metal plating bath, a method for producing the base metal plating film, an electronic component having the base metal plating film, a brightener for the base metal plating film, and an antioxidant for the base metal plating film. It is.
[1]
A base metal plating film including a base metal matrix and hydrophilic nanodiamond particles dispersed in the base metal matrix.
[2]
The base metal plating film according to [1], wherein glossiness at an incident angle of 60 ° is 10 or more higher than that of the same base metal plating film as above except that the hydrophilic nano diamond particles are not included.
[3]
Immediately after the production, the base metal oxide film has an increase of less than 1%, preferably less than 0.5%, more preferably less than 0.5% after storage for 7 days at 25 ° C. and 50% humidity in a room not exposed to direct sunlight. Is less than 0.3%, most preferably less than 0.1%, the base metal plating film according to [1] or [2].
[4]
The base metal plating film according to any one of [1] to [3], which is free of a surfactant.
[5]
The base metal plating film according to any one of [1] to [4], wherein the hydrophilic nanodiamond particles are the following (i) or (ii) nanodiamond particles:
(i) nano-diamond particles coated with a hydrophilic polymer;
(ii) Nanodiamond particles modified with a hydrophilic polymer.
[6]
Base metals are iron, nickel, zinc, copper, tin, aluminum, tungsten, molybdenum, tantalum, magnesium, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, The plating film according to any one of [1] to [5], which is at least one selected from the group consisting of niobium, permalloy, rhenium, and thallium.
[7]
The base metal plating film according to any one of [1] to [6], wherein the hydrophilic nanodiamond particles dispersed in the base metal matrix have an average particle diameter (D50) by SEM of 4 to 95 nm. .
[8]
When the hydrophilic polymer is polyglycerin, polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, poly (meth) acrylic acid, polyacrylamide, polyethyleneimine, vinyl ether polymer, cellulose derivative, water-soluble polyester, water-soluble phenol resin, The base metal plating film according to [5], which is selected from the group consisting of molecular polysaccharides.
[9]
The base metal is copper, the crystallite size (A) of the 111 face is 100 nm or less, the crystallite size (B) of the 220 face is 80 nm or less, and the crystallite size ratio (A / B) of the 111 face and the 220 face. ) Is 1.3 or more, the base metal plating film according to any one of [1] to [8].
[10]
The base metal is copper, and the peak intensity ratio (111/220) of the 111 and 220 planes of the X-ray diffraction pattern is 3.0 or less, according to any one of [1] to [8]. Base metal plating film.
[11]
The base metal is nickel, the crystallite size (A) of the 111 face is 25 nm or less, the crystallite size (C) of the 200 face is 23 nm or less, and the crystallite size ratio (A / C) of the 111 face and the 200 face. ) Is 1.1 or more, the base metal plating film according to any one of [1] to [8].
[12]
A base metal plating bath containing a base metal ion and hydrophilic nanodiamond particles, wherein the concentration of the hydrophilic nanodiamond particles is 0.001 to 1 g / L.
[13]
The base metal plating bath according to [12], wherein the haze is 0 to 0.5.
[14]
The base metal plating bath according to [12] or [13], wherein the particle diameter (D10) of the hydrophilic nanodiamond particles in the base metal plating bath is 10 to 60 nm.
[15]
The base metal plating bath according to [12] or [13], wherein the particle diameter (D50) of the hydrophilic nanodiamond particles in the base metal plating bath is 10 to 70 nm.
[16]
The base metal plating bath according to [12] or [13], wherein the particle diameter (D90) of the hydrophilic nanodiamond particles in the base metal plating bath is 10 to 90 nm.
[17]
The method according to [1], wherein the subject is immersed in a base metal plating bath containing base metal ions and hydrophilic nanodiamond particles, and the concentration of the nanodiamond particles is 0.001 to 1 g / L, and electrolytic plating is performed. [11] A method for producing the plating film according to any one of [11].
[18]
The method according to [17], wherein the base metal plating bath has a haze of 0 to 0.5.
[19]
An electronic component comprising the plating film according to any one of [1] to [11].
[20]
Brightener for base metal plating film containing hydrophilic nano diamond particles.
[21]
Antioxidant for base metal plating film containing hydrophilic nano diamond particles.

The base metal plating film of the present invention has a configuration in which nanodiamond particles are highly dispersed in a matrix of the base metal, and the growth of the base metal crystal is inhibited by the nanodiamond particles to make the crystal grains fine, It is smooth and has high gloss and excellent oxidation resistance. Further, the base metal plating film of the present invention has excellent heat resistance, surface hardness, and electrical conductivity. Therefore, the base metal plating film of the present invention is suitably used for connecting parts for electronic equipment, decorative articles and the like.

In addition, since the base metal plating film of the present invention has a smooth surface, the coefficient of friction decreases and the contact resistance value decreases. Therefore, it is suitably used as a connecting part repeatedly used with a low contact load among connecting parts (or electric contacts) such as low current (signal) switches and connectors used for electric / electronic devices.

The plating bath of the present invention is useful for producing a base metal plating film having high gloss and excellent oxidation resistance.

According to the method for producing a base metal plating film of the present invention, a base metal plating film having high glossiness and excellent oxidation resistance can be efficiently produced by a simple operation.

電子 The electronic component of the present invention has a base metal plating film having high gloss and excellent oxidation resistance.

光沢 The brightener of the present invention is useful for forming a base metal plating film having high glossiness.

The antioxidant of the present invention is useful for forming a base metal plating film having excellent oxidation resistance.

FIG. 2 is an enlarged schematic view illustrating an example of hydrophilic ND particles according to the present invention. 7 shows an X-ray diffraction result of a plating film formed on a brass plate in Comparative Example 1. 13 shows an X-ray diffraction result of a plating film formed on a brass plate in Example 4. The X-ray diffraction results immediately after and 5 days after the production of the plating film formed on the brass plate in Comparative Example 2 are shown. 9 shows an XRD pattern of a copper plating film measured in Test Example 7. 13 shows an SEM photograph of a plating film of Test Example 8. (a) Without ND, (b) With ND. C1s (XPS) in the copper plating film obtained in Example 1.

[Hydrophilic ND particles]
The ND particles used in the present invention are hydrophilic ND particles.
(i) ND particles coated with a hydrophilic polymer, and
(ii) ND particles modified with a hydrophilic polymer are included. Preferred hydrophilic ND particles are the ND particles of (ii).

ND particles into which a hydrophilic functional group (OH, COOH, NH ₂ ) has been introduced are known (for example, JP-A-2018-30741). For example, ND generated by a detonation method can be preferably used. The detonation method includes an air-cooled detonation method and a water-cooled detonation method. In the present invention, among others, the air-cooled detonation method is preferable because it is possible to obtain an ND having smaller primary particles than the water-cooled detonation method. By performing the detonation in an air atmosphere or a nitrogen atmosphere, hydrophilic ND particles having a plurality of hydrophilic functional groups (OH, COOH, NH ₂ ) formed on the surface can be obtained. The coating or modification of the hydrophilic polymer is performed via a hydrophilic functional group.

Examples of hydrophilic polymers include polyglycerin (PG), polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, poly (meth) acrylic acid, polyacrylamide, polyethyleneimine, vinyl ether polymers, cellulose derivatives, water-soluble polyesters, and natural polymers And polysaccharides. Examples of the vinyl ether-based polymer include homopolymers or copolymers of alkyl vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl isopropyl ether, vinyl butyl ether and vinyl isobutyl ether (for example, polyvinyl methyl ether, polyvinyl ethyl ether, Vinyl ether-maleic anhydride copolymer). Examples of the cellulose derivative include methyl cellulose, ethyl cellulose, propyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, and the like. Examples of the water-soluble polyester include polydimethylol propionate. Examples of the natural high molecular polysaccharide include alginic acid or a salt thereof, pectin, starch, agar, acacia, dextrin, carrageenan, and the like. Preferred hydrophilic polymers are polyglycerin, polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol and poly (meth) acrylic acid, with polyglycerin being particularly preferred.

Ｎ The ND particles modified with a surface modifying group containing a polyglycerin chain have, for example, a configuration in which polyglycerin represented by the following formula (1) is bonded to a surface functional group of the ND particles. In the following formula, n represents the number of glycerin units constituting the polyglycerin chain, and is an integer of 1 or more.

HO- (C ₃ H ₆ O ₂ ) _n -H (1)
C ₃ H ₆ O ₂ in parentheses in the formula (1) has a structure represented by the following formulas (2) and / or (3).

—CH ₂ —CHOH—CH ₂ O— (2)
—CH (CH ₂ OH) CH ₂ O— (3)
The polyglycerin chains include linear, branched, and cyclic polyglycerin chains.

The amount of the hydrophilic polymer introduced by modification or coating is, for example, about 0.05 to 1.0 part by mass, preferably about 0.4 to 1.0 part by mass, per part by mass of the ND particles. It is preferably from 0.5 to 0.9 part by mass, particularly preferably from 0.6 to 0.8 part by mass. When the amount of the hydrophilic polymer introduced is within the above range, ND particle aggregation can be prevented. The mass ratio between the hydrophilic polymer portion and the ND particle portion can be determined by measuring the change in mass during heat treatment or the composition ratio by elemental analysis using a differential thermal balance analyzer (TG-DTA).

The coating of ND particles with a hydrophilic polymer involves contacting nanodiamond particles in a hydrophilic polymer solution and centrifuging to separate hydrophilic polymers that are not involved in the coating. The coated nanodiamond particles can be collected.

Modification of ND particles with a hydrophilic polymer uses the ND particles having a hydrophilic functional group (OH, COOH, NH _2, etc.) introduced on the surface as a raw material, and adds a hydrophilic polymer group to the hydrophilic functional group. It can be carried out by bonding via a linker group such as an ester bond, an amide bond, an imide bond, an ether bond, a urethane bond, and a urea bond. The linker group is formed by a method of forming an ester or amide bond using a condensing agent such as dicyclohexylcarbodiimide, water-soluble carbodiimide, carbonyldiimidazole, or a hydrophilic compound having an isocyanate group (N = C = O). A method for forming a urethane bond or a urea bond using a polymer, when the hydrophilic polymer has a COOH group, converting the COOH group into an acid halide (particularly an acid chloride) or an acid anhydride, Alternatively, it can be performed by a method of reacting with ND particles having an NH ₂ group to form an ester bond or an amide bond.

ND particles into which a hydrophilic functional group (OH, COOH, NH ₂ ) used as a raw material for coating with a hydrophilic polymer or modifying with a hydrophilic polymer have an average primary particle diameter of 10 nm or less, for example, Fine particles of 1 to 10 nm are preferred.

微粒子 Fine particles having an average particle diameter of primary particles of the hydrophilic ND particles of the present invention of 12 nm or less, for example, 1 to 12 nm, preferably 3 to 12 nm are preferable.

The average particle size of the ND particles having a hydrophilic functional group and the primary particles of the ND particles coated or modified with a hydrophilic polymer is measured using an X-ray diffractometer (trade name: "Smart Lab", manufactured by Rigaku Corporation). Small-angle X-ray scattering measurement (SAXS method), and using a particle size distribution analysis software (trade name “NANO-Solver”, manufactured by Rigaku Corporation), the nanodiamond primary particles are spherical and the particle density is 3 It can be determined by estimating the primary particle size of the nanodiamond in the range of the scattering angle of 1 ° to 3 ° on the assumption that it is .51 g / cm ³ .

The hydrophilic ND particles are preferably fine particles having an average primary particle diameter of 10 nm or less, for example, 1 to 10 nm.

The ND particles are prevented from agglomerating by making the surface hydrophilic, and can simultaneously improve glossiness and oxidation resistance. On the other hand, ND particles having no hydrophilic functional group or hydrophilic polymer as described in Non-Patent Document 1 have improved glossiness and oxidation resistance even when introduced into a base metal plating film. Does not occur. As described in Test Example 2 of the present specification, the average particle size of ND primary particles obtained by the detonation method is 10 nm or less, but the particle size of ND primary particles obtained by the impact compression method. Since ND greatly exceeds 10 nm, it is preferable that the ND particles are produced by the detonation method. In the present invention, it is not necessary to add a surfactant to the base metal plating bath. If a surfactant is contained in the plating bath, even a small amount may be taken into the base metal plating film, so it is preferable not to use a surfactant. Further, the base metal plating film is preferably free of a surfactant.

[Base metal plating film]
The base metal plating film of the present invention is a base metal plating film including a base metal matrix and hydrophilic ND particles dispersed in the base metal matrix. In a preferred embodiment of the present invention, the hydrophilic ND particles may be uniformly dispersed in the base metal matrix, or may be densely dispersed near the surface of the base metal matrix.

Base metals include iron, nickel, zinc, copper, tin, aluminum, tungsten, molybdenum, tantalum, magnesium, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, Indium, niobium, at least one selected from the group consisting of rhenium and thallium is mentioned, preferably copper, nickel, zinc, tin, chromium, at least one selected from the group consisting of permalloy, more preferably copper, It is at least one selected from the group consisting of nickel, zinc, and tin.

The base metal plating film of one preferred embodiment of the present invention is a base metal plating film including a base metal matrix and hydrophilic ND particles dispersed in the base metal matrix, and has a glossiness of 770 or more at an incident angle of 60 °. It is characterized by the following. In the case of 100% reflection, the glossiness is 1,000.

光沢 The glossiness of the base metal plating film of the present invention at an incident angle of 60 ° is 770 or more, preferably 780 or more, more preferably 800 or more, and further preferably 850 or more when the base metal is copper.

The glossiness of the base metal plating film of the present invention at an incident angle of 60 ° is 560 or more when the base metal is nickel, 785 or more when the base metal is tin, 575 or more when the base metal is permalloy, and 410 or more when the base metal is zinc.

Also, compared to a base metal plating film having the same composition as the present invention except that it does not contain hydrophilic ND particles, the base metal plating film of the present invention has a glossiness at an incident angle of 60 ° of, for example, 10 or more (for example, 10 to 200). ) High, preferably 15 or higher, more preferably 35 or higher, particularly preferably 55 or higher, most preferably 85 or higher.

The base metal plating film of the present invention preferably has an increased base metal oxide after storage for 7 days at room temperature (around 25 ° C., humidity of about 50%) in a room not exposed to direct sunlight with respect to the base metal plating film immediately after production. It is less than 1%, more preferably less than 0.5%, even more preferably less than 0.3%, and most preferably less than 0.1%.

The surface roughness (Ra) of the base metal plating film of the present invention is, for example, 0.5 μm or less, preferably 0.4 μm or less, more preferably 0.3 μm or less, particularly preferably 0.15 μm or less, and most preferably 0.1 μm or less. It is as follows.

In the base metal plating film of the present invention, the particle size of the hydrophilic ND particles dispersed in the base metal matrix by SEM is, for example, in the range of 4 to 95 nm, preferably 10 to 80 nm, particularly preferably 20 to 60 nm, and most preferably. Is 30 to 50 nm.

In one preferred embodiment of the present invention, when the base metal is copper, the crystallite size (A) on the 111 plane is 100 nm or less, preferably 80 nm or less, more preferably 70 nm or less, still more preferably 60 nm or less, particularly preferably 50 nm or less. Or less, most preferably 45 nm or less, and the crystallite size (B) of the 220 plane is 80 nm or less, preferably 60 nm or less, more preferably 50 nm or less, still more preferably 40 nm or less, particularly preferably 35 nm or less, and most preferably 30 nm or less. It is as follows. The crystallite size ratio (A / B) between the 111 plane and the 220 plane is preferably 1.3 or more, and more preferably 1.3 to 1.6.

In one preferred embodiment of the present invention, when the base metal is nickel, the crystallite size (A) of the 111 plane is 25 nm or less, preferably 24 nm or less, more preferably 23 nm or less, even more preferably 22 nm or less, and 200 planes. Has a crystallite size (C) of 23 nm or less, preferably 20 nm or less, more preferably 18 nm or less, still more preferably 16 nm or less, and particularly preferably 14 nm or less. The crystallite size ratio (A / C) of the 111 plane and the 200 plane is preferably 1.1 or more, more preferably 1.1 to 1.6.

In one preferred embodiment of the present invention, when the base metal is copper, the peak intensity ratio between the 111 plane and the 220 plane in the X-ray diffraction (XRD) pattern (111 plane / 220 plane) is preferably 3.0 or less, and more preferably 3.0 or less. Preferably it is 1.4 to 3.0.

The conductivity when the conductivity of the annealed standard soft copper of the copper plating film of the present invention is 100% IACS, is preferably 80% IACS or more, more preferably 85% IACS or more, still more preferably 90% IACS or more, and particularly preferably. Is at least 92% IACS, most preferably at least 94% IACS. The electrical conductivity is obtained by calculating the volume resistivity from the value of the surface resistivity by the four-point terminal method and the thickness of the plating film by the micrometer, and converting it to IACS% and converting it into conductivity. The volume resistivity can be obtained as an average value of a plurality of points (for example, five points in the upper, lower, left, and right directions) of the plating film sample. In addition, IACS (international annealed copper standard)% is defined as a standard of electric resistance, in which conductivity of annealed standard copper (volume resistivity: 1.7241 × 10 ⁻² μΩm) is defined as 100% IACS.

In the base metal plating film of the present invention, the hydrophilic ND particle content is 0.5 to 25 area%, preferably 2 to 20 area%, particularly preferably 5 to 15 area% of the area of the base metal plating film. is there. The content (area%) of the hydrophilic ND particles can be measured by SEM observation on the cross section of the plating phase. In Comparative Example 2 and FIG. 4 of the specification of the present application, the base metal plating film containing the non-hydrophilic ND did not show any increase in gloss and no antioxidant effect. The inventors have found that "hydrophilicity" is important.

The hydrophilic ND particles used in the present invention preferably have a plurality or a large number of hydrophilic functional groups, or more preferably are coated or modified with at least one hydrophilic polymer, so that aggregation can be prevented. Thus, a plating film having high gloss and excellent oxidation resistance can be obtained. FIG. 1 is an enlarged schematic view showing an example of ND particles having a surface modifying group in the present invention. 1 is an ND particle having a surface modifying group, 2 is an ND particle (part), and 3 is a surface modifying group.

[Production method of base metal plating film]
The base metal plating film of the present invention can be produced by using a known electrolytic plating method (preferably, electrolytic composite plating method) or an electroless plating method. More specifically, a base member for forming a plating film (for example, a conductive substrate such as a brass substrate) is immersed in a plating bath containing base metal ions and hydrophilic ND particles, and electrolytic plating or electroless plating is performed. Can be precipitated on the surface of the member together with the hydrophilic ND particles, and the hydrophilic ND particles can be incorporated into the base metal film. By continuing this until the desired thickness is reached, the hydrophilic ND particles can be contained in the base metal matrix. A base metal plating film (or a plating film composed of a base metal-hydrophilic ND particle composite material) having a structure in which is dispersed can be produced.

The thickness of the base metal plating film can be appropriately set according to the use, for example, about 0.1 to 1000 μm. In the case of coating the surface of a conductive metal member as a connection component such as a switch or a connector, the base metal plating film is used. The thickness of the film is, for example, about 0.1 to 50 μm.

(Base metal plating bath)
The base metal plating bath in the present invention contains a plating solution and hydrophilic ND particles. The content of the hydrophilic ND particles in the base metal plating bath is, for example, 0.001 to 1.0 g / L (the lower limit is preferably 0.003 g / L, more preferably 0.006 g / L, and further preferably 0. 0.01 g / L, particularly preferably 0.03 g / L. The upper limit is preferably 0.8 g / L, more preferably 0.6 g / L, and particularly preferably 0.5 g / L. And preferably 0.01 to 0.5 g / L. When the content of the hydrophilic ND particles is within the above range, high glossiness and oxidation resistance of the base metal plating film and good adhesion to the substrate can be obtained.

The base metal plating bath is excellent in transparency because it contains hydrophilic ND particles in a highly dispersed (or colloidally dispersed) state, and the haze is preferably about 0 to 5, more preferably about 0 to 2, It is more preferably about 0 to 1, particularly preferably about 0 to 0.5, and most preferably 0 to 0.4. Haze can be measured in accordance with JIS K7136.

The particle diameter (D10) of the hydrophilic ND particles in the base metal plating bath is, for example, 95 nm or less, preferably 60 nm or less, particularly preferably 50 nm or less, and most preferably 40 nm or less. The lower limit of the particle diameter (D10) of the hydrophilic ND particles is, for example, 10 nm.

粒径 The particle diameter (D50) of the hydrophilic ND particles in the base metal plating bath is, for example, 95 nm or less, preferably 70 nm or less, particularly preferably 60 nm or less, and most preferably 50 nm or less. The lower limit of the particle size (D50) of the hydrophilic ND particles is, for example, 20 nm.

粒径 The particle diameter (D90) of the hydrophilic ND particles in the base metal plating bath is, for example, 95 nm or less, preferably 90 nm or less, and particularly preferably 80 nm or less. The lower limit of the particle size (D90) of the hydrophilic ND particles is, for example, 50 nm. In addition, the particle size of the hydrophilic ND particles in the base metal plating bath can be measured by a dynamic light scattering method.

The base metal plating bath can be prepared, for example, by adding a hydrophilic ND particle dispersion to a plating solution described below. The electroless base metal plating bath may contain a water-soluble base metal salt, hydrophilic ND particles, a phosphorus source (in the case of electroless nickel-phosphorus alloy plating), a reducing agent, a complexing agent, and the like. As the electroless base metal plating bath, an electroless nickel-phosphorus alloy base metal plating bath is preferable.

The concentration of the water-soluble base metal salt in the electrolytic and electroless base metal plating bath is, for example, 0.01 to 0.5 mol / L, preferably 0.05 to 0.5 mol / L, in terms of the concentration of the base metal ion supplied to the base metal plating bath. 2 mol / L.

還元 Examples of the reducing agent and the phosphorus supply source contained in the electroless base metal plating bath include phosphinates such as sodium phosphinate. When a phosphinate is employed, the concentration of the phosphinate in the base metal plating bath is, for example, 0.02 to 0.5 mol / L, and preferably 0.1 to 0.2 mol / L.

錯 Examples of the complexing agent contained in the electrolytic and electroless base metal plating baths include citric acid, lactic acid, malic acid, glycolic acid, and salts thereof. Examples of citric acid include sodium citrate and potassium citrate. When citric acid and / or its salt is employed, the concentration of citric acid and / or its salt in the electrolytic and electroless base metal plating bath is, for example, 0.02 to 1.0 mol / L, preferably 0.1 to 1.0 mol / L. 0.5 mol / L.

The electrolytic and electroless base metal plating baths may contain other components in addition to the above components. Examples of such components include a pH buffer and a stabilizer for suppressing self-decomposition of the base metal plating bath.

ＰＨ The pH of the base metal plating bath is, for example, 5 to 11.

(Plating solution)
The plating solution in the present invention contains components essential for preparing a plating film and does not contain the above-mentioned hydrophilic ND particles. The plating solution contains at least base metal ions.

The plating solution can be prepared by, for example, compounding a water-soluble base metal salt, a conductive salt, a complexing agent, an additive for adjusting the appearance and physical properties of the film, and the like. The water-soluble base metal salt exists as a base metal ion in the base metal plating bath. In addition, it may be present as a base metal oxyacid ion or a base metal complex ion combined with a complexing agent.

Examples of the plating solution for base metal plating include: a base metal sulfate solution comprising base metal sulfate, sulfuric acid, and chloride ions; a base metal cyanide plating solution comprising base metal cyanide, sodium cyanide, alkali carbonate, Rochelle salt; Examples include a pyrophosphate base metal plating solution composed of pyrophosphate, potassium pyrophosphate, aqueous ammonia, potassium nitrate, and the like.

(Hydrophilic ND particle dispersion liquid and its preparation method)
The hydrophilic ND particle dispersion liquid is obtained by dispersing hydrophilic ND particles in a dispersion medium (preferably water). The hydrophilic ND particle concentration in the hydrophilic ND particle dispersion is, for example, about 1 to 100 g / L.

As the hydrophilic ND particles, in terms of excellent dispersibility, hydrophilic ND particles in which the hydrophilic functional group of the ND particles is coated or modified with a hydrophilic polymer are preferable, and particularly preferably a water-soluble ND particle containing a polyglycerin chain. It is a hydrophilic ND particle having a polymer.

粒径 The particle diameter (D50) of the hydrophilic ND particles in the hydrophilic ND particle dispersion is, for example, 95 nm or less, preferably 70 nm or less, particularly preferably 60 nm or less, and most preferably 50 nm or less. The lower limit of the particle diameter (D50) of the hydrophilic ND particles is, for example, 10 nm. In addition, the particle diameter of the hydrophilic ND particles in the hydrophilic ND particle dispersion can be measured by a dynamic light scattering method (DLS).

光沢 By adding the hydrophilic ND particle dispersion to the base metal plating bath, it is possible to impart gloss to the obtained base metal plating film. Therefore, for example, it can be used as a brightener for base metal plating films.

(Method of preparing hydrophilic ND particle dispersion)
Hereinafter, an example of a method for producing a dispersion of hydrophilic ND particles modified with a polyglycerin chain will be described. Hydrophilic ND particles other than polyglycerin can be easily prepared by those skilled in the art with reference to the above general production method and the method for producing a hydrophilic ND particle dispersion modified with a polyglycerin chain described below. .

(Generation process)
First, an explosive equipped with an electric detonator is installed inside a pressure-resistant container for detonation, and the container is hermetically sealed in a state in which a normal-pressure gas having an atmospheric composition and an explosive to be used coexist in the container. The container is made of, for example, iron, and the volume of the container is, for example, 0.5 to 40 m ³ . A mixture of trinitrotoluene (TNT) and cyclotrimethylenetrinitroamine or hexogen (RDX) can be used as explosive. The mass ratio between TNT and RDX (TNT / RDX) is, for example, in the range of 40/60 to 60/40.

In the generation process, the electric detonator is then detonated, and the explosive is detonated in the container. At the time of detonation, ND particles are generated by the action of the pressure and energy of the shock wave generated by the explosion, using carbon released as a result of partial incomplete combustion of the explosive used as a raw material. In the generated ND particles, adjacent primary particles or crystallites are aggregated very strongly due to the Coulomb interaction between crystal planes in addition to the action of van der Waals force, thereby forming an aggregate.

(4) In the production step, the container and the inside thereof are allowed to cool by being left at room temperature for about 24 hours to lower the temperature. After the cooling, the ND particles are adhered to the inner wall of the container by using a spatula to scrape the crude product of ND particles (including the ND particle aggregate and soot generated as described above) with a spatula. A crude product is obtained.

(Acid treatment step)
The acid treatment step is a step of treating a crude ND particle product as a raw material with a strong acid in, for example, an aqueous solvent to remove a metal oxide. The crude product of ND particles obtained by the detonation method easily contains a metal oxide, and this metal oxide is an oxide of Fe, Co, Ni or the like derived from a container or the like used in the detonation method. For example, a metal oxide can be dissolved and removed from a crude product of ND particles by applying a predetermined strong acid in an aqueous solvent. As the strong acid used in the acid treatment, a mineral acid is preferable, and examples thereof include hydrochloric acid, hydrofluoric acid, sulfuric acid, nitric acid, and a mixture thereof. The concentration of the strong acid used in the acid treatment is, for example, 1 to 50% by mass. The acid treatment temperature is, for example, 70 to 150 ° C. The acid treatment time is, for example, 0.1 to 24 hours. Further, the acid treatment can be performed under reduced pressure, normal pressure, or increased pressure. After such an acid treatment, it is preferable to wash the solid content (including ND aggregates) with water, for example, by decantation until the pH of the precipitation liquid reaches, for example, 2 to 3. When the content of the metal oxide in the crude ND particle product obtained by the detonation method is small, the above acid treatment may be omitted.

(Oxidation treatment step)
The oxidation treatment step is a step of removing graphite from the crude ND particle product using an oxidizing agent. The crude product of ND particles obtained by the detonation method contains graphite (graphite), but this graphite did not form ND crystals among the released carbon due to partial incomplete combustion of the explosive used. Derived from carbon. For example, graphite can be removed from the crude ND particle product by allowing a predetermined oxidizing agent to act in a water solvent after the above-mentioned acid treatment.

Examples of the oxidizing agent used in the oxidation treatment include chromic acid, chromic anhydride, dichromic acid, permanganic acid, perchloric acid, nitric acid, and mixtures thereof, and at least one acid selected from these. And other acids (for example, sulfuric acid and the like), and salts thereof. In the present invention, among them, it is preferable to use a mixed acid (particularly, a mixed acid of sulfuric acid and nitric acid) because it is environmentally friendly and has excellent action of oxidizing and removing graphite.

The mixing ratio of sulfuric acid and nitric acid in the mixed acid (former / latter; mass ratio) may be, for example, 60/40 to 95/5 even under a pressure near normal pressure (for example, 0.5 to 2 atm). For example, at a temperature of 130 ° C. or higher (especially preferably 150 ° C. or higher; the upper limit is, for example, 200 ° C.), it is preferable because graphite can be efficiently oxidized and removed. The lower limit is preferably 65/35, particularly preferably 70/30. The upper limit is preferably 90/10, particularly preferably 85/15, and most preferably 80/20.

When the ratio of nitric acid in the mixed acid exceeds the above range, the content of sulfuric acid having a high boiling point is reduced. Therefore, under a pressure near normal pressure, the reaction temperature becomes, for example, 120 ° C. or lower, and the efficiency of removing graphite tends to decrease. There is. On the other hand, if the ratio of nitric acid in the mixed acid falls below the above range, the content of nitric acid that greatly contributes to the oxidation of graphite decreases, and the efficiency of graphite removal tends to decrease.

The amount of the oxidizing agent (particularly, the mixed acid) is, for example, 10 to 50 parts by mass, preferably 15 to 40 parts by mass, and particularly preferably 20 to 40 parts by mass with respect to 1 part by mass of the crude ND particle product. The amount of sulfuric acid used in the mixed acid is, for example, 5 to 48 parts by mass, preferably 10 to 35 parts by mass, particularly preferably 15 to 30 parts by mass with respect to 1 part by mass of the crude product of ND particles. The amount of nitric acid used in the mixed acid is, for example, 2 to 20 parts by mass, preferably 4 to 10 parts by mass, and particularly preferably 5 to 8 parts by mass with respect to 1 part by mass of the crude ND particle product.

場合 When the mixed acid is used as the oxidizing agent, a catalyst may be used together with the mixed acid. By using a catalyst, the efficiency of removing graphite can be further improved. Examples of the catalyst include copper (II) carbonate. The amount of the catalyst to be used is, for example, about 0.01 to 10 parts by mass based on 100 parts by mass of the crude ND particle product.

The oxidation treatment temperature is, for example, 100 to 200 ° C. The oxidation treatment time is, for example, 1 to 24 hours. The oxidation treatment can be performed under reduced pressure, normal pressure, or increased pressure.

(Drying process)
In the present method, it is preferable to provide a drying step, for example, using a spray drying device or an evaporator, etc., from the solution containing hydrophilic ND particles having a hydrophilic functional group obtained through the above steps, After evaporation, the resulting residual solids are dried by heating in a drying oven. The heating and drying temperature is, for example, 40 to 150 ° C. Through such a drying step, ND powder is obtained.

(Oxygen oxidation step)
In the oxygen oxidation step, the ND powder is heated in a gas atmosphere having a predetermined composition containing oxygen using a gas atmosphere furnace. Specifically, ND powder is placed in a gas atmosphere furnace, an oxygen-containing gas is supplied to or passed through the furnace, and the inside of the furnace is heated to a temperature condition set as a heating temperature, and oxygen is supplied. An oxidation treatment is performed.

温度 The temperature condition of the oxygen oxidation treatment is, for example, 250 to 500 ° C. In order to obtain hydrophilic ND particles having a negative zeta potential, the temperature condition of the oxygen oxidation treatment is preferably relatively high, for example, 400 to 450 ° C. The oxygen-containing gas is a mixed gas containing an inert gas in addition to oxygen. Inert gases include, for example, nitrogen, argon, carbon dioxide, and helium. The oxygen concentration of the mixed gas is, for example, 1 to 35% by volume.

(Hydrogenation process)
When hydrophilic ND particles having a positive zeta potential are desired, a hydrogenation step is performed after the above-described oxygen oxidation step. In the hydrogenation step, the ND powder that has undergone the oxygen oxidation step is heated using a gas atmosphere furnace under a gas atmosphere having a predetermined composition containing hydrogen. Specifically, a hydrogen-containing gas is supplied to or passed through a gas atmosphere furnace in which the ND powder is disposed, and the inside of the furnace is heated to a temperature condition set as a heating temperature to cause hydrogenation. Processing is performed. Temperature conditions for this hydrogenation treatment are, for example, 400 to 800 ° C. The hydrogen-containing gas used in the present embodiment is a mixed gas containing an inert gas in addition to hydrogen. Inert gases include, for example, nitrogen, argon, carbon dioxide, and helium. The hydrogen concentration of the mixed gas is, for example, 1 to 50% by volume.

(Crushing process)
Even after purification through a series of processes as described above, the hydrophilic ND particles are in the form of aggregates (secondary particles) in which primary particles have very strong interaction and are aggregated. Often taken. Therefore, it is preferable to perform a crushing step to separate the primary particles from the adherend. Specifically, first, ND powder having undergone the oxygen oxidation step or the subsequent hydrogenation step is suspended in pure water, and a slurry containing ND particles having a hydrophilic functional group (OH, COOH, NH _2, etc.) is prepared. Prepare. In preparing the slurry, centrifugation may be performed to remove relatively large aggregates from the hydrophilic ND particle suspension, or ultrasonic treatment may be performed on the ND particle suspension having a hydrophilic functional group. May be applied. Then, the slurry is subjected to a wet crushing treatment. The crushing treatment can be performed using, for example, a high shear mixer, a high shear mixer, a homomixer, a ball mill, a bead mill, a high-pressure homogenizer, an ultrasonic homogenizer, or a colloid mill. The disintegration treatment may be performed by combining these. It is preferable to use a bead mill from the viewpoint of efficiency.

によって Through such a disintegration step, an ND particle aqueous dispersion containing ND primary particles having a hydrophilic functional group can be obtained. The dispersion obtained through the pulverizing step may be subjected to a classification operation in order to remove coarse particles. For example, coarse particles can be removed from the dispersion by a classification operation using centrifugation using a classification device.

(Drying process)
In the present method, it is preferable to provide a drying step, for example, evaporating the liquid component from the aqueous dispersion of ND particles having a hydrophilic functional group obtained through the above step using a spray dryer or an evaporator. After drying, the resulting residual solids are dried by heating and drying in a drying oven. The heating and drying temperature is, for example, 40 to 150 ° C. Through such a drying step, ND particles containing a hydrophilic functional group are obtained as a powder.

(Modification process)
The hydrophilic ND particles modified with a polyglycerin chain can be obtained, for example, by directly performing ring-opening polymerization of glycidol on ND particles having a hydrophilic functional group obtained through the above steps. The ND particles have a carboxyl group or a hydroxyl group generated during the manufacturing process on the surface thereof, and the surface of the ND can be modified with a hydrophilic polymer by reacting these functional groups with glycidol.

The reaction (ring-opening polymerization) between ND particles having a hydrophilic functional group and glycidol is performed, for example, by adding glycidol and a catalyst to ND particles having a hydrophilic functional group under an inert gas atmosphere and heating to 50 to 100 ° C. Can be done by doing As the catalyst, an acidic catalyst or a basic catalyst can be used. Examples of the acidic catalyst include trifluoroboron etherate, acetic acid, and phosphoric acid, and examples of the basic catalyst include triethylamine, pyridine, dimethylaminopyridine, and triphenylphosphine.

グリ The amount of glycidol used for ring-opening polymerization is, for example, 20 parts by mass or more, and preferably 20 to 150 parts by mass, per 1 part by mass of ND particles having a hydrophilic functional group. If the amount of glycidol is less than the above range, sufficient dispersibility tends to be hardly obtained.

後 After completion of the reaction, the obtained reaction product is preferably subjected to a purification treatment by, for example, filtration, centrifugation, extraction, washing with water, neutralization, or a combination thereof. Thereby, a hydrophilic ND particle dispersion liquid (preferably, a hydrophilic ND particle aqueous dispersion liquid) in the present invention is obtained. Glycidol is used for the production of ND particles modified with polyglycerin. However, ND particles modified with a hydrophilic polymer other than polyglycerin, or ND particles modified with a hydrophilic polymer are described in the above description and in the known art. Can be easily manufactured by those skilled in the art by referring to.

[Electronic components]
An electronic component according to the present invention includes the base metal plating film. The electronic component of the present invention may have another plating film other than the base metal plating film. For example, the electronic component may have one or more base plating films. The electronic component of the present invention includes, for example, a connection component (for example, a connector or the like) for an electronic device such as a personal digital assistant (PDA) or a mobile phone.

[Brightener]
The brightener of the base metal plating film according to the present invention is characterized by containing the hydrophilic ND particles.

The brightener may contain other components in addition to the hydrophilic ND particles, but the proportion of the content of the hydrophilic ND particles in the total amount of the brightener is, for example, 50% by mass or more, preferably It is at least 60% by mass, particularly preferably at least 70% by mass, most preferably at least 80% by mass, particularly preferably at least 90% by mass.

[Antioxidant]
The antioxidant for the base metal plating film of the present invention is characterized by containing the hydrophilic ND particles.

The antioxidant may contain other components in addition to the hydrophilic ND particles, but the proportion of the content of the hydrophilic ND particles in the total amount of the antioxidant is, for example, 50% by mass or more, It is preferably at least 60% by mass, particularly preferably at least 70% by mass, most preferably at least 80% by mass, particularly preferably at least 90% by mass.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The ND particle concentration, particle size, and zeta potential were measured by the following methods.

<ND particle concentration>
The ND particle concentration of the aqueous ND particle dispersion is determined by a precision balance with respect to the weighed values of 3 to 5 g of the weighed dispersion and the dried matter (powder) remaining after the water is evaporated from the weighed dispersion by heating. Calculated based on the calculated values.

<Particle size>
The particle size (median diameter, D10, D50, and D90) of the ND particles contained in the ND particle aqueous dispersion or the base metal plating bath is determined by using an apparatus manufactured by Malvern (trade name “Zetasizer Nano ZS”). Was measured by a dynamic light scattering method (non-contact back scattering method).

<Zeta potential>
The zeta potential of the ND particles contained in the ND particle aqueous dispersion was measured by a laser Doppler electrophoresis using an apparatus manufactured by Malvern (trade name “Zetasizer Nano ZS”). The aqueous dispersion of ND particles subjected to the measurement was diluted with ultrapure water so that the ND particle concentration became 0.2% by mass, and then subjected to ultrasonic irradiation by an ultrasonic cleaner, and the zeta potential measurement was performed. The temperature is 25 ° C.

Preparation Example 1
Through the following steps, an aqueous dispersion of hydrophilic ND particles was prepared.

(Generation process)
First, a molded explosive equipped with an electric detonator was placed inside a pressure-resistant container for detonation (iron, volume: 15 m ³ ), and the container was sealed. As an explosive, 0.50 kg of a mixture of TNT and RDX (TNT / RDX (mass ratio) = 50/50) was used. Next, the electric detonator was detonated, and the explosive was detonated in the container. Next, it was left at room temperature for 24 hours to lower the temperature of the container and the inside thereof. After the cooling, the crude ND particle product (including the ND particle aggregate and soot generated by the detonation method) attached to the inner wall of the container was recovered to obtain a crude ND particle product. .

(Acid treatment step)
Next, an acid treatment was performed on the crude ND particle product obtained in the above step. Specifically, a slurry obtained by adding 6 L of 10% by mass hydrochloric acid to 200 g of the crude ND particle product is subjected to a heat treatment under reflux under normal pressure conditions for 1 hour (heating temperature: 85 to 100 ° C.). ) Was done. Next, after cooling, the solid content (including the ND cohesion and soot) was washed with water by decantation. The washing of the solid by decantation was repeatedly performed until the pH of the precipitation solution reached 2 from the low pH side.

(Oxidation treatment step)
Next, a mixed acid treatment was performed. Specifically, 6 L of a 98% by mass aqueous sulfuric acid solution and 1 L of a 69% by mass aqueous solution of nitric acid are added to a precipitation liquid (including ND cohesive bodies) obtained through decantation after acid treatment to form a slurry. The slurry was subjected to a heat treatment (heating temperature: 140 to 160 ° C.) for 48 hours under normal pressure and under reflux. Next, after cooling, the solid content (including the ND cohesion) was washed with water by decantation. Although the supernatant at the beginning of the washing was colored, the washing of the solid by decantation was repeated until the supernatant became visually transparent.

(Drying process)
Next, 1000 mL of the ND particle-containing liquid having a hydrophilic functional group obtained through the above-mentioned water washing treatment was applied using a spray drying apparatus (trade name “Spray Dryer B-290”, manufactured by Nippon Buch Co., Ltd.). Spray dried. Thereby, 50 g of ND powder was obtained.

(Oxygen oxidation step)
Next, 4.5 g of the ND powder obtained as described above was allowed to stand still in a furnace tube of a gas atmosphere furnace (trade name: “Gas atmosphere tube furnace KTF045N1”, manufactured by Koyo Thermo System Co., Ltd.). After flowing nitrogen gas at a flow rate of 1 L / min for 30 minutes, the flowing gas is switched from nitrogen to a mixed gas of oxygen and nitrogen, and the mixed gas is passed through the reactor core tube at a flow rate of 1 L / min. Continued. The oxygen concentration in the mixed gas is 4% by volume. After switching to the mixed gas, the inside of the furnace was heated up to a heating set temperature of 400 ° C. The heating rate was 10 ° C./min up to 380 ° C., which is 20 ° C. lower than the set heating temperature, and 1 ° C./min from 380 ° C. to 400 ° C. thereafter. Then, while maintaining the temperature condition in the furnace at 400 ° C., the ND powder in the furnace was subjected to oxygen oxidation treatment. The processing time was 3 hours.

After the oxygen oxidation treatment, oxygen-containing functional groups such as carboxy groups in the ND particles were evaluated by FT-IR analysis described below. From the spectrum obtained by this analysis, an absorption near 1780 cm ⁻¹ attributed to C ＝ O stretching vibration was detected as a main peak. From this, it was confirmed that the ND powder mainly contained ND particles (ND-COOH) having a plurality of carboxyl groups as surface functional groups.

<FT-IR analysis conditions>
Fourier transform infrared spectroscopy (FT-IR) was performed using an FT-IR apparatus (trade name “Spectrum400 type FT-IR”, manufactured by Perkin Elmer Japan Co., Ltd.). In this measurement, the infrared absorption spectrum was measured while heating the sample to 150 ° C. in a vacuum atmosphere. For heating in a vacuum atmosphere, Model-HC900 Heat Chamber and TC-100WA Thermo Controller manufactured by ST Japan Co., Ltd. were used in combination.

(Crushing process)
First, 0.3 g of the ND powder having undergone the oxygen oxidation step and 29.7 mL of pure water were mixed in a 50 mL sample bottle to obtain about 30 mL of a slurry. Next, after adjusting the pH of the slurry by adding a 1N aqueous solution of sodium hydroxide, an ultrasonic irradiator (trade name “Ultrasonic cleaner AS-3”, manufactured by AS ONE) is used. For 2 hours. Thereafter, bead milling was performed using a bead milling device (trade name: "parallel four-cylinder sand grinder LSG-4U-2L", manufactured by Imex Co., Ltd.). Specifically, 30 mL of the slurry after the ultrasonic irradiation and zirconia beads having a diameter of 30 μm were sealed in a vessel (manufactured by Imex Co., Ltd.), which is a 100 mL mill container, and the apparatus was driven to perform bead milling. In this bead milling, the input amount of zirconia beads is about 33% based on the volume of the mill container, the rotation speed of the mill container is 2570 rpm, and the milling time is 2 hours.

Next, the slurry that had undergone the crushing step was subjected to centrifugation using a centrifugal separator (classification operation). The centrifugal force in this centrifugation treatment was 20,000 × g, and the centrifugation time was 10 minutes.

Next, 25 mL of the supernatant of the ND particle-containing solution that had undergone the centrifugation treatment was collected to obtain an ND particle aqueous dispersion (ND-COOH). The ND particle concentration in the ND particle aqueous dispersion was 11.8 g / L. Further, the pH was measured using pH test paper (trade name “Three Band pH Test Paper”, manufactured by AS ONE Corporation) and found to be 9.33. The particle size D50 was 3.97 nm, the particle size D90 was 7.20 nm, and the zeta potential was -42 mV.

(Modification process)
The aqueous dispersion of ND particles obtained above was dried using an evaporator to obtain a black dry powder. The obtained dry powder (100 mg) was added to 12 mL of glycidol in a glass reactor, and was added at room temperature with an ultrasonic cleaner (trade name “BRANSON2510”, manufactured by Marshall Scientific). Dissolved by sonication for hours. This was reacted at 140 ° C. for 20 hours while stirring under a nitrogen atmosphere. After cooling the reaction mixture, 120 mL of methanol was added thereto, followed by sonication, followed by centrifugation at 50,400 G for 2 hours to obtain a precipitate. 120 mL of methanol was added to the precipitate, and the washing-centrifugation step was repeated 5 times in the same manner. Finally, the precipitate was subjected to a dialysis membrane (Spectra / Prodialysis membrane, MWCO: 12-14 kDa). Pure water dialysis was performed, the residual methanol was replaced with water, and the resultant was freeze-dried to obtain a gray powder of hydrophilic ND particles (PG-ND particles) modified with polyglycerin.

比率 The ratio of ND particles to surface modifying groups was measured by TG-DTA thermal analysis. As a result, ND particles: surface modifying groups = 1: 0.7.

PG-ND gray powder and water were added, and the concentration was adjusted to 10 g / L based on the mass of the ND particles to obtain an aqueous dispersion of PG-ND particles.

[Example 1]
The aqueous dispersion of PG-ND particles obtained in Preparation Example 1 was added to a copper plating solution (trade name "electrolytic plating solution", manufactured by Kiyokawa Plating Industry Co., Ltd.), and plating bath (1) (in the plating bath) PG-ND particle concentration: was obtained 1 g / L, the CuSO ₄ · 5H ₂ O concentration of 5 wt%).

When the particle diameter of the PG-ND particles in the plating bath (1) was measured, the particle diameter (D10) was 30 nm, the particle diameter (D50) was 44 nm, and the particle diameter (D90) was 76 nm.

Plating bath (1) was transparent and free from turbidity.

真 A brass plate (20 mm long × 20 mm wide × 1 mm thick) [manufactured by Kiyokawa Plating Industry Co., Ltd.] as a plating film forming target member was degreased and washed.

This brass plate was plated in a plating bath (1) under the conditions of pH 0.1, a liquid temperature of 28 ° C. and a current density of 2 A / dm ² for 20 minutes with stirring, and copper-ND was placed on the brass plate. A plating film (copper plating film) made of a particle composite material was formed (cathode: brass plate, anode: copper plate). In the brass plate having the obtained copper plating film, ND particles were uniformly and highly dispersed, and the surface was smooth.

[Example 2]
Plating bath (2) (concentration of PG-ND particles in plating bath: 0.5 g / L) in the same manner as in Example 1 except that the amount of the aqueous dispersion of PG-ND particles obtained in Preparation Example 1 was changed. ), And a brass plate having a copper plating film was obtained in the same manner as in Example 1 except that the obtained plating bath (2) was used.

[Example 3]
Plating bath (3) (concentration of PG-ND particles in plating bath: 0.2 g / L) in the same manner as in Example 1 except that the amount of the aqueous dispersion of PG-ND particles obtained in Preparation Example 1 was changed. ), And a brass plate having a copper plating film was obtained in the same manner as in Example 1 except that the obtained plating bath (3) was used.

[Example 4]
Plating bath (4) (concentration of PG-ND particles in plating bath: 0.1 g / L) in the same manner as in Example 1 except that the amount of the aqueous dispersion of PG-ND particles obtained in Preparation Example 1 was changed. ), And a brass plate having a copper plating film was obtained in the same manner as in Example 1 except that the obtained plating bath (4) was used.

[Example 5]
Plating bath (5) (concentration of PG-ND particles in plating bath: 0.05 g / L) in the same manner as in Example 1 except that the amount of the aqueous dispersion of PG-ND particles obtained in Preparation Example 1 was changed. ), And a brass plate having a copper plating film was obtained in the same manner as in Example 1 except that the obtained plating bath (5) was used.

[Example 6]
Plating bath (6) (concentration of PG-ND particles in plating bath: 0.01 g / L) in the same manner as in Example 1 except that the amount of the aqueous dispersion of PG-ND particles obtained in Preparation Example 1 was changed. ) And a brass plate having a copper plating film was obtained in the same manner as in Example 1 except that the obtained plating bath (6) was used.

[Example 7]
Plating bath (7) (the concentration of PG-ND particles in the plating bath: 0.001 g / L) in the same manner as in Example 1 except that the amount of the aqueous dispersion of PG-ND particles obtained in Preparation Example 1 was changed. ), And a brass plate having a copper plating film was obtained in the same manner as in Example 1 except that the obtained plating bath (7) was used.

[Comparative Example 1]
Example except that the plating bath (1) was replaced with a copper plating solution (trade name "electrolytic plating solution", manufactured by Kiyokawa Plating Industry Co., Ltd.) plating bath (6) (excluding the ND particle dispersion). A brass plate having a copper plating film was obtained in the same manner as in Example 1. The plating film formed on the brass plate had irregularities on the surface and lacked smoothness.

<Gloss measurement>
The glossiness of the plating films obtained in Examples 1 to 7 and Comparative Example 1 was measured using a gloss meter “High Gloss Gloss Checker IG-410” (manufactured by Horiba, Ltd.) under the following conditions under the following conditions: (Reflectance 100%) was measured.

Light source: LED (wavelength: 890 nm)
Incident angle: 60 ° (in case of 100% reflection, the gloss is 1000 (no unit))
The results are summarized in Table 1 below.

より From Table 1 below, it was found that the glossiness of the surface of the copper plating film such as copper was increased by the addition of ND particles.

Ｘ Moreover, the X-ray diffraction results immediately after and 7 days after the production of the plating films formed on the brass plate in Example 4 and Comparative Example 1 are shown in FIG. 2 (Comparative Example 1) and FIG. 3 (Example 4). The copper plating film of Comparative Example 1 had a peak of copper oxide (CuO) after one week and was colored reddish brown, whereas the copper plating film of Example 4 had a peak of copper oxide (CuO) even after one week. Was not observed, and no difference was observed by visual observation immediately after the production and after 7 days.

(4) From these results, it became clear that the hydrophilic ND particles can suppress the oxidation of the base metal plating film.

Comparative Example 2
200 ppm of non-hydrophilic PG unmodified ND was added to a copper plating bath (manufactured by Kiyokawa Plating). The addition concentration of ND (manufactured by Daicel, before PG modification) was the same as that with PG. While stirring, plating was performed under the same conditions as in Example 1 using PG-modified ND. The same sample was used for confirming the gloss and the antioxidant effect. Table 2 shows the results of measuring the glossiness of the obtained plating films (Comparative Example 2, Examples 3 and 4) immediately after production. As a result of the copper plating with PG-unmodified ND, the gloss was almost the same as the gloss without ND, and clearly different from the gloss with PG-modified ND added. Further, XRD measurement was performed on the copper plating film of Comparative Example 2 immediately after plating and 5 days after plating. FIG. 4 shows the results. Five days after the preparation of the plating film, copper oxide was confirmed, and the antioxidant effect as confirmed by the PG-ND particles was not recognized.

[Test Example 1]
Example 1 was the same as Example 1 except that the concentration of the PG-ND particles in the copper plating bath was 0 ppm, 200 ppm (0.02%), 400 ppm (0.04%), 600 ppm (0.06%), and 1000 ppm (0.1%). Similarly, a copper plating bath was prepared, and the haze was measured. Table 3 shows the results.

[Test Example 2]
In Preparation Example 1, the crystal structure analysis of the PG unmodified ND particles obtained by the detonation method was performed using an X-ray diffractometer (trade name “Smart Lab”, manufactured by Rigaku Corporation). As a result, a strong diffraction peak was observed at the diffraction peak position of diamond, that is, at the diffraction peak position from the (111) plane of the diamond crystal, and it was confirmed that ND particles without PG modification were diamond.

Next, the PG unmodified ND particles and PG-ND particles obtained in Preparation Example 1 and the ND particles (PG unmodified and PG modified) obtained by the impact compression method were subjected to an X-ray diffraction apparatus (product). Small-angle X-ray scattering measurement (SAXS method) using the name “Smart Lab” (Rigaku) and scattering using particle size distribution analysis software (trade name “NANO-Solver”, Rigaku) The primary particle size of the nanodiamond was estimated for the range of 1 ° to 3 °. In this estimate, nanodiamond primary particles and particle density is spherical put the assumption that it is 3.51 g / cm ^3. The ND particles obtained by the impact compression method were manufactured by SCM Nano Diamond, manufactured by Sumiishi Material Co., Ltd. The PG-modified ND particles obtained by the impact compression method were obtained by preparing the ND particles in the same manner as in Preparation Example 1. PG modification. Table 4 shows the measurement results of the particle size by the SAXS method.

[Test Example 3]
For the plating films obtained in Example 1 (a copper plating solution containing 200 ppm of PG-ND), Comparative Example 1 (a plating solution containing no ND), and Comparative Example 2 (a plating solution containing PG unmodified ND), a fine angle By the incident X-ray diffraction method, diffraction peaks of the 111 plane of the copper oxide immediately after plating, 5 days after plating, and 7 days after plating were measured as follows.

(1) Grazing incidence X-ray diffraction method Grazing incidence X-ray diffraction (GIXD) method was used to analyze the structure of the surface of the copper plating table.
This method makes use of the fact that when X-rays are incident on a very flat surface of a substance, it causes total reflection, and measures reflection, refraction, and diffraction before and after the angle at which total reflection occurs, while slightly changing the angle. Is the way. This time, the measurement was performed using SmartLab (manufactured by Rigaku Corporation) with an incident angle of about 0.7 ° and a measurement angle of 30 ° to 100 °.

(2) Storage condition of plating film The brass plate having the copper plating film obtained in Example 1 and Comparative Examples 1 and 2 was stored in a room protected from direct sunlight for 5 days or 1 week (normal temperature: about 25 ° C, humidity: 50%).

(3) Measurement results Table 5 shows the results.

After 7 days, the peak intensity of the 111 plane of copper oxide was 2.5% of the peak intensity of the 111 plane of copper without ND (Comparative Example 1), whereas the peak of copper oxide was lower in the PG-modified ND (Example 3). 0.1%.

[Example 8 and Comparative Example 3]
Using the following tin (Sn) plating solution, Sn plating of the brass plate was performed in the same manner as in Example 1 (PG-ND particle concentration in the Sn plating bath: 0.2 g / L (Example 8) or 0 g / L). L (Comparative Example 3)), a brass plate having a Sn plating film was obtained. Table 6 shows the results of measuring the glossiness and the surface roughness (Ra) of the brass plate having the obtained Sn plating film.
・ Sn plating solution composition: stannous sulfate 30g / L, sulfuric acid 130g / L
Plating temperature: 10 ℃
Current density: 2A / dm ²
Plating time: 10 minutes

[Example 9 and Comparative Example 4]
Using the following nickel (Ni) plating solution and plating conditions, Ni plating of the brass plate was performed in the same manner as in Example 1 (PG-ND particle concentration in the Ni plating bath: 0.2 g / L (Example 9)). Alternatively, a brass plate having a Ni plating film of 0 g / L (Comparative Example 4) was obtained. Table 6 shows the results of measuring the glossiness and the surface roughness (Ra) of the brass plate having the obtained Ni plating film.
・ Nickel plating solution composition: nickel sulfate 250g / L, nickel chloride 40g / L, boric acid 30g / L
Plating temperature: 50 ° C
Current density: 2A / dm ²
Plating time: 25 minutes

[Example 10 and Comparative Example 5]
Using the following zinc (Zn) plating solution and plating conditions, Zn plating of the brass plate was performed in the same manner as in Example 1 (PG-ND particle concentration in the Zn plating bath: 0.2 g / L (Example 10)). Alternatively, a brass plate having a Zn plating film of 0 g / L (Comparative Example 5) was obtained. Table 6 shows the results of measuring the glossiness and the surface roughness (Ra) of the obtained brass plate having a Zn plating film.
・ Zinc plating solution composition: zinc oxide 10g / L, sodium hydroxide 100g / L
Plating temperature: Room temperature Current density: 2A / dm ²
Plating time: 18 minutes

[Example 11 and Comparative Example 6]
Using the following permalloy (alloy of Ni and Fe) plating solution and plating conditions, permalloy plating of a brass plate was performed in the same manner as in Example 1 and Comparative Example 1 (the concentration of PG-ND particles in the permalloy plating bath: 0.1%). 2 g / L (Example 11) or 0 g / L (Comparative Example 6), a brass plate having a permalloy plating film was obtained. Table 6 shows the results of measuring the glossiness and the surface roughness (Ra) of the obtained brass plate having a permalloy plating film.
・ Permalloy plating solution composition: nickel sulfate 250g / L, nickel chloride 40g / L, boric acid 30g / L, ferrous sulfate 24g / L, malonic acid 5g / L,
Plating temperature: 50 ° C
Current density: 2A / dm ²
Plating time: 25 minutes

<Surface roughness (Ra) measurement>
The surface roughness (Ra) of the plating films obtained in Examples 8 to 11 and Comparative Examples 3 to 6 was measured using a high-precision shape measuring system KS-1100 (manufactured by KEYENCE).

(4) It became clear that the glossiness, surface smoothness and indentation hardness (surface hardness) of the plating film can be improved by adding PG-ND particles to various plating solutions. It is considered that the low surface roughness (Ra) is related to the improvement in glossiness.

[Test Example 4]
Using the plating films obtained in Examples 3, 9 and 11, and Comparative Examples 1, 4 and 6, using a micro indentation hardness tester (trade name “ENT-2100”, manufactured by Elionix Inc.), The indentation hardness (surface hardness) was measured under the following conditions.
Indenter: Birkovich indenter Load condition: (i) Starting load_0mN → Load_20mN, 10s
(ii) Starting load_20mN → Load_20mN, 10s
(iii) Start load_20mN → End load_0mN, 10s The results of a 10s microhardness tester are shown in Table 7.

[Example 12]
Plating bath (12) (concentration of PG-ND particles in plating bath: 0.02 g / L) in the same manner as in Example 1 except that the amount of the aqueous dispersion of PG-ND particles obtained in Preparation Example 1 was changed. ) Was obtained, and a stainless steel plate having a copper plating film was obtained in the same manner as in Example 1 except that the obtained plating bath (12) was used and the brass plate was changed to a stainless steel plate.

[Comparative Example 7]
A stainless steel plate having a copper plating film was obtained in the same manner as in Comparative Example 1 except that the plating bath (6) of Comparative Example 1 was used and the brass plate was changed to a stainless steel plate.

[Test Example 5]
The copper plating film of the stainless steel plate obtained in Example 12 (using a copper plating solution containing 20 ppm of PG-ND) and Comparative Example 7 (a plating solution containing no ND) was peeled off, and a plating film was placed on a glass plate. Then, the thickness of the plating film was measured with a micrometer, and the conductivity was measured under the following conditions.
Conductivity measuring device: Loresta GX, manufactured by Mitsubishi Chemical Analytech Sample size: 1 cm ²
Measuring point ： In the middle of top, bottom, left and right (5 points)
Measurement method: The plating film was peeled from the stainless steel plate and measured on a separately prepared glass plate.

Specifically, the thickness of the plating film measured by a micrometer was input to Loresta GX, and the volume resistivity was measured (four-point terminal method). The volume resistivity was converted into conductivity by setting the conductivity of annealed standard annealed copper (volume resistivity: 1.7241 × 10 ^-2 μΩm) as 100% IACS. Table 8 shows the results.

It was revealed that the conductivity of the copper plating prepared from the plating bath to which the hydrophilic nanodiamond (PG-ND) of the present invention was added was improved as compared with the copper plating without the addition.
The base metal plating film of the present invention to which the hydrophilic nanodiamond (PG-ND) is added has an unexpected effect of preventing the increase in the crystallite size, maintaining the hardness, and improving the conductivity.

[Test Example 6]
With respect to the copper plating films obtained in Example 3 (a copper plating solution containing 200 ppm of PG-ND) and Comparative Example 1 (a copper plating solution containing no ND), crystallite sizes on the 111 plane and the 220 plane were measured. The crystallite size was measured by the X-ray diffraction method (XRD) using CuKα radiation as an X-ray source, using the Scherrer equation from the half width of the diffraction peak and the diffraction angle. The measuring device used was Rigaku's [SmartLab], and the optical system used a centralized method. Table 9 shows the results. FIG. 5 shows an XRD pattern of the copper plating film, and Table 10 shows a peak intensity ratio between the 111 plane and the 220 plane.

(4) It was revealed that the copper plating film containing PG-ND obtained in Example 3 had small crystallite sizes on both the 111 plane and the 220 plane, and was excellent in indentation hardness (surface hardness).

[Test Example 7]
Regarding the plating films obtained in Example 9 (nickel plating solution containing 200 ppm of PG-ND) and Comparative Example 4 (nickel plating solution containing no ND), the crystals of the 111 and 200 planes of the nickel plating 3 months after plating The child size was measured. The crystallite size was measured by the X-ray diffraction method (XRD) using CuKα radiation as an X-ray source, using the Scherrer equation from the half width of the diffraction peak and the diffraction angle. The measuring device used was Rigaku's [SmartLab], and the optical system used a centralized method. Table 11 shows the results.

ニッケル It was revealed that the nickel plating film containing PG-ND obtained in Example 9 had small crystallite sizes on both the 111 plane and the 200 plane, and was excellent in indentation hardness (surface hardness).

[Test Example 8]
For the plating films obtained in Example 9 (nickel plating solution containing 200 ppm of PG-ND) and Comparative Example 4 (nickel plating solution not containing ND), cross sections were prepared using a focused ion beam processing apparatus, and reflected electron images were obtained. Observations were made.
Apparatus name: FIB-SEM apparatus (Versa3D DualBeam manufactured by FEI). FIG. 6A shows a plating film containing no ND particles of Comparative Example 1 and has a large surface roughness (Ra). FIG. 6B shows a plating film including ND particles of Example 1, and small black dots indicated by arrows are ND particles.

[Test Example 9]
Regarding the plating film obtained in Example 1 (copper plating solution containing 200 ppm of PG-ND), the apparatus used in the Cu plating film by X-ray photoelectric spectroscopy (XPS) using ULVAC-PHI (PHI5800 ESCA system). Was measured for carbon content (C1s). FIG. 7 shows the results. Carbon content was detected in the Cu film.

1 ND particle having surface modification group 2 ND particle (part)
3 Surface modifying groups

Claims

(4) A base metal plating film including a base metal matrix and hydrophilic nanodiamond particles dispersed in the base metal matrix.
The base metal plating film according to claim 1, wherein the glossiness at an incident angle of 60 ° is higher by 10 or more than that of the same base metal plating film except that the hydrophilic nano diamond particles are not included.
Immediately after the production, the base metal oxide film has an increase of less than 1%, preferably less than 0.5%, more preferably less than 0.5% after storage for 7 days at 25 ° C. and 50% humidity in a room not exposed to direct sunlight. The base metal plating film according to claim 1 or 2, wherein is less than 0.3%, most preferably less than 0.1%.
(4) The base metal plating film according to any one of (1) to (3), which is free of a surfactant.
The base metal plating film according to any one of claims 1 to 4, wherein the hydrophilic nanodiamond particles are the following (i) or (ii) nanodiamond particles:
(i) nano-diamond particles coated with a hydrophilic polymer;
(ii) Nanodiamond particles modified with a hydrophilic polymer.
Base metals are iron, nickel, zinc, copper, tin, aluminum, tungsten, molybdenum, tantalum, magnesium, cobalt, bismuth, cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium, germanium, vanadium, gallium, hafnium, indium, The plating film according to any one of claims 1 to 5, wherein the plating film is at least one selected from the group consisting of niobium, permalloy, rhenium, and thallium.
The base metal plating film according to any one of claims 1 to 6, wherein the hydrophilic nanodiamond particles dispersed in the base metal matrix have an average particle diameter (D50) by SEM of 4 to 95 nm.
When the hydrophilic polymer is polyglycerin, polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, poly (meth) acrylic acid, polyacrylamide, polyethyleneimine, vinyl ether polymer, cellulose derivative, water-soluble polyester, water-soluble phenol resin, The base metal plating film according to claim 5, which is selected from the group consisting of molecular polysaccharides.
The base metal is copper, the crystallite size (A) of the 111 face is 100 nm or less, the crystallite size (B) of the 220 face is 80 nm or less, and the crystallite size ratio (A / B) of the 111 face and the 220 face. The base metal plating film according to any one of claims 1 to 8, wherein (1) is not less than 1.3.
The base metal plating according to any one of claims 1 to 8, wherein the base metal is copper, and the peak intensity ratio (111/220) of the X-ray diffraction pattern between the 111 and 220 planes is 3.0 or less. film.
The base metal is nickel, the crystallite size (A) of the 111 face is 25 nm or less, the crystallite size (C) of the 200 face is 23 nm or less, and the crystallite size ratio (A / C) of the 111 face and the 200 face. The base metal plating film according to any one of claims 1 to 8, wherein (1) is 1.1 or more.
(4) A base metal plating bath containing base metal ions and hydrophilic nanodiamond particles, wherein the concentration of the hydrophilic nanodiamond particles is 0.001 to 1 g / L.
The base metal plating bath according to claim 12, wherein the haze is from 0 to 0.5.
The base metal plating bath according to claim 12, wherein the hydrophilic nano diamond particles in the base metal plating bath have a particle size (D10) of 10 to 60 nm.
14. The base metal plating bath according to claim 12, wherein the particle diameter (D50) of the hydrophilic nanodiamond particles in the base metal plating bath is 10 to 70 nm.
The base metal plating bath according to claim 12, wherein the particle diameter (D90) of the hydrophilic nanodiamond particles in the base metal plating bath is 10 to 90 nm.
The method according to claim 1, wherein the subject is immersed in a base metal plating bath containing a base metal ion and hydrophilic nanodiamond particles, and the concentration of the nanodiamond particles is 0.001 to 1 g / L, and electrolytic plating is performed. 12. A method for producing the plating film according to any one of items 11 to 11.
18. The method for producing a plating film according to claim 17, wherein the haze of the base metal plating bath is 0 to 0.5.
An electronic component comprising the plating film according to any one of claims 1 to 11.
光沢 Brightener for base metal plating film containing hydrophilic nano diamond particles.
酸化 Antioxidant for base metal plating film containing hydrophilic nano diamond particles.