JPWO2020013188A1 - Base metal plating film - Google Patents

Abstract

The present invention provides a base metal matrix and a base metal plating film containing hydrophilic nanodiamond particles dispersed in the base metal matrix.

Description

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 provided with the base metal plating film, a brightener for the base metal plating film, and an antioxidant for the base metal plating film.

In the present specification, "nanodiamond" may be referred to as "ND".

Among the connecting parts such as low-current (signal system) switches and connectors used in electrical and electronic equipment, the connecting parts that are repeatedly used with a low contact load are required to have high connection reliability, so they are used as such connecting parts. Connection parts in which the surface of a conductive metal member is plated with a metal such as a noble metal are used. Then, the plating film may be required to have an appropriate luster in addition to conductivity.

In Patent Document 1, for the purpose of obtaining a high-quality and highly reliable plating film composited with carbon-based fine particles, carbon-based fine particles such as carbon nanotubes are dispersed in a water-insoluble solvent, and then copper ions and the like are described. A method for producing a plating bath in which a water-insoluble solvent is added to an aqueous metal salt solution containing a base metal ion and the mixture is stirred to disperse the carbon-based fine particles in the aqueous base metal salt solution is disclosed. By using the plating bath produced by this method, it is said that electronic components in which impurities are suppressed from being mixed can be obtained. However, this method cannot impart high gloss to the plating film. In addition, base metals are susceptible to air oxidation.

As a method of imparting luster to the plating film, the surface of the precipitated noble metal is formed by adding a brightener having the effect of adsorbing to the crystal nucleus and inhibiting the growth of the crystal to make the crystal finer. It is smoothed to give a gloss (see, for example, Patent Document 2).

Non-Patent Document 1 proposes that nanodiamond particles are added to the plating bath to incorporate the nanodiamond particles into the plating film, but since the nanodiamond particles are not sufficiently dispersed in the plating solution, they are in the plating bath. It is described that the nanodiamond particles of No. 1 are aggregated to the order of μm.

Patent Document 3 describes a configuration in which diamond fine particles into which a hydrophilic polymer or an ionic functional group has been introduced are added to a metal plating solution together with a surfactant, and 1 g / L of anionic functional group-introduced diamond fine particles is used in Example 1. A configuration is described in which the dispersion liquid containing 1 g / L is added at a ratio of 2 g / L, and the dispersion liquid containing 1 g / L of PEG-introduced diamond fine particles is added at a ratio of 0.1 g / L in Example 2. The amount cannot be expected to improve the glossiness and oxidation resistance of the plating film.

Patent Document 4 has a configuration in which a hydrophilic polymer or ionic functional group-introduced diamond fine particles having an average particle size of 10 nm to 300 nm, fluororesin fine particles having an average particle size of 100 nm to 300 nm, and a surfactant are added to the metal plating solution. Although the electroless composite plating solution containing 2.0 g / L of grafted diamond fine particles is described in Examples 1 and 2, the glossiness of the plating film is described in the plating solution containing such high concentration diamond fine particles. , Improvement of oxidation resistance cannot be expected.

WO2011 / 048884 Japanese Unexamined Patent Publication No. 2015-117424 Japanese Unexamined Patent Publication No. 2011-149071 Japanese Unexamined Patent Publication No. 2012-0292416

Hiroshi Matsubara "Surface Technology" Vol.65, No.2, (2014), pp. 88-93

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 glossiness and oxidation resistance.

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

Another object of the present invention is to provide a novel brightener 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.

As a result of diligent studies to solve the above problems, the present inventor has high glossiness and oxidation resistance when base metal plating is performed using a plating bath containing base metal ions and to which hydrophilic nanodiamond particles are added. It has been found that a base metal plating film having excellent properties can be obtained.

The present invention provides the following base metal plating film, base metal plating bath, method for producing the base metal plating film, electronic parts provided with the base metal plating film, brightener for the base metal plating film, and antioxidant for the base metal plating film. Is.
[1]
A base metal plating film containing a base metal matrix and hydrophilic nanodiamond particles dispersed in the base metal matrix.
[2]
The base metal plating film according to [1], which has a glossiness of 10 or more at an incident angle of 60 ° as compared with the same base metal plating film as described above except that it does not contain the hydrophilic nanodiamond particles.
[3]
With respect to the base metal plating film immediately after production, the increase in base metal oxide after storage in a room not exposed to direct sunlight at 25 ° C. and humidity of 50% for 7 days is less than 1%, preferably less than 0.5%, more preferably. The base metal plating film according to [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 surfactant-free.
[5]
The base metal plating film according to any one of [1] to [4], wherein the hydrophilic nanodiamond particles are the nanodiamond particles of (i) or (ii) below:
(i) Nanodiamond 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, renium and tantalum.
[7]
The base metal plating film according to any one of [1] to [6], wherein the average particle diameter (D50) of the hydrophilic nanodiamond particles dispersed in the base metal matrix is in the range of 4 to 95 nm by the SEM method. ..
[8]
Hydrophilic polymers are polyglycerin, polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, poly (meth) acrylic acid, polyacrylamide, polyethyleneimine, vinyl ether-based polymers, cellulose derivatives, water-soluble polyesters, water-soluble phenol resins, natural highs. 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) on the 111th surface is 100 nm or less, the crystallite size (B) on the 220th surface is 80 nm or less, and the crystallite size ratio between the 111th surface and the 220th surface (A / B). ) Is 1.3 or more, the base metal plating film according to any one of [1] to [8].
[10]
The item according to any one of [1] to [8], wherein the base metal is copper and the peak intensity ratio (111 planes / 220 planes) of the 111 planes and 220 planes of the X-ray diffraction pattern is 3.0 or less. Base metal plating film.
[11]
The base metal is nickel, the crystallite size (A) on the 111-plane is 25 nm or less, the crystallite size (C) on the 200-plane is 23 nm or less, and the crystallite size ratio between the 111-plane and the 200-plane (A / C). ) 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 base metal ions and hydrophilic nanodiamond particles and having a concentration of hydrophilic nanodiamond particles of 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 hydrophilic nanodiamond particles in the base metal plating bath have a particle size (D10) of 10 to 60 nm.
[15]
The base metal plating bath according to [12] or [13], wherein the hydrophilic nanodiamond particles in the base metal plating bath have a particle size (D50) of 10 to 70 nm.
[16]
The base metal plating bath according to [12] or [13], wherein the hydrophilic nanodiamond particles in the base metal plating bath have a particle size (D90) of 10 to 90 nm.
[17]
The subject is immersed in a base metal plating bath containing base metal ions and hydrophilic nanodiamond particles and having a concentration of nanodiamond particles of 0.001 to 1 g / L, and electrolytic plating is performed. [1] to The method for producing a plating film according to any one of [11].
[18]
The method for producing a plating film according to [17], wherein the base metal plating bath has a haze of 0 to 0.5.
[19]
An electronic component provided with the plating film according to any one of [1] to [11].
[20]
A brightener for base metal plating films containing hydrophilic nanodiamond particles.
[21]
Antioxidant for base metal plating films containing hydrophilic nanodiamond particles.

The base metal plating film of the present invention has a structure in which nanodiamond particles are highly dispersed in a matrix of base metals, and the surface of the base metal plating film is probably because the growth of base metal crystals is inhibited by the nanodiamond particles and the crystal grains become finer. It is smoothed and has high gloss and excellent oxidation resistance. In addition, the base metal plating film of the present invention has excellent heat resistance, surface hardness, and conductivity. Therefore, the base metal plating film of the present invention is suitably used for connection parts for electronic devices, ornaments, and the like.

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

The plating bath of the present invention is useful for producing a base metal plating film having high glossiness 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.

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

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

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

It is an enlarged schematic diagram which shows an example of hydrophilic ND particles in this invention. The X-ray diffraction result of the plating film formed on the brass plate in Comparative Example 1 is shown. The X-ray diffraction result of the plating film formed on the brass plate in Example 4 is shown. Comparative Example 2 shows the X-ray diffraction results immediately after the production of the plating film formed on the brass plate and after 5 days. The XRD pattern of the copper plating film measured in Test Example 7 is shown. The SEM photograph of the plating film of Test Example 8 is shown. (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, and these particles are:
(i) ND particles coated with hydrophilic polymer and
(ii) Includes ND particles modified with hydrophilic polymers. The preferred hydrophilic ND particles are the ND particles of (ii).

ND particles into which hydrophilic functional groups (OH, COOH, NH ₂ ) have been introduced are known (for example, Japanese Patent Application Laid-Open No. 2018-30741), and for example, ND produced by the detonation method can be preferably used. Detonation methods include air-cooled detonation and water-cooled detonation. In the present invention, the air-cooled detonation method is particularly preferable because it can 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 in which a plurality of hydrophilic functional groups (OH, COOH, NH 2} ) are formed on the surface can be obtained. Coating or modification of hydrophilic polymers is done via hydrophilic functional groups.

Examples of hydrophilic polymers include polyglycerin (PG), polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, poly (meth) acrylic acid, polyacrylamide, polyethyleneimine, vinyl ether-based polymers, cellulose derivatives, water-soluble polyesters, and natural polymers. Examples include polysaccharides. Examples of the vinyl ether-based polymer include homopolymers or copolymers such as 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 and polyvinyl ethyl ether, etc.). Vinyl ether-maleic anhydride copolymer, etc.). 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 polydimethylolpropionic acid ester. Examples of the natural high molecular weight polysaccharide include alginic acid or a salt thereof, pectin, starch, agar, gum arabic, 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.

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 the surface functional group of the ND particles. In the following formula, n indicates 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 of 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 chain includes a linear structure, a branched chain structure, and a cyclic structure polyglycerin chain.

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, and more, per 1 part by mass of the ND particle portion. It is preferably 0.5 to 0.9 parts by mass, and particularly preferably 0.6 to 0.8 parts by mass. If the amount of the hydrophilic polymer introduced is within the above range, aggregation of ND particles can be prevented. The mass ratio of the hydrophilic polymer portion and the ND particle portion can be determined by measuring the mass change 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 is performed by contacting nanodiamond particles in a hydrophilic polymer solution and performing centrifugation to separate the hydrophilic polymer that is not involved in the coating, and then using the hydrophilic polymer. Coated nanodiamond particles can be collected.

To modify the ND particles with a hydrophilic polymer, the ND particles having a hydrophilic functional group (OH, COOH, NH _2, etc.) introduced on the surface are used as a raw material, and the hydrophilic polymer group is used as 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, or a urea bond. The formation of the linker group is a method of forming an ester or amide bond using a condensing agent such as dicyclohexylcarbodiimide, water-soluble carbodiimide, or carbonyldiimidazole, and hydrophilicity having an isocyanato group (N = C = O). A method of forming a urethane bond or a urea bond using a polymer. When the hydrophilic polymer has a COOH group, the COOH group is converted into an acid halide (particularly an esterified product) or an acid anhydride to OH. Alternatively, it can be carried out by a method of reacting with ND particles having _{two NH groups to form an ester bond or an amide bond.}

_{ND particles into which hydrophilic functional groups (OH, COOH, NH 2} ) used as raw materials for coating with a hydrophilic polymer or modification with a hydrophilic polymer have been introduced have an average particle diameter of primary particles of 10 nm or less, for example. Fine particles of 1 to 10 nm are preferable.

The average particle size of the primary particles of the hydrophilic ND particles of the present invention is 12 nm or less, for example, fine particles of 1 to 12 nm, preferably 3 to 12 nm.

For 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, an X-ray diffractometer (trade name "Smart Lab", manufactured by Rigaku Co., Ltd.) is used. Then, small-angle X-ray scattering measurement (SAXS method) is performed, and using particle size distribution analysis software (trade name "NANO-Solver", manufactured by Rigaku Co., Ltd.), the nanodiamond primary particles are spherical and the particle density is 3. It can be determined by estimating the primary particle size of nanodiamonds in the region of scattering angle 1 ° to 3 °, assuming that it is .51 g / cm ^3.

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

By making the surface of the ND particles hydrophilic, aggregation is prevented, and glossiness and oxidation resistance can be improved at the same time. On the other hand, ND particles as described in Non-Patent Document 1 in which a hydrophilic functional group or a hydrophilic polymer is not introduced are improved in 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 the ND primary particles obtained by the explosive method is 10 nm or less, but the particle size of the ND primary particles obtained by the impact compression method. Is much larger than 10 nm, so the ND particles are preferably produced by the explosive method. In the present invention, it is not necessary to add a surfactant to the base metal plating bath. If the plating bath contains a surfactant, even a small amount may be incorporated into the base metal plating film, so it is preferable not to use the surfactant. Further, the base metal plating film is preferably surfactant-free.

[Base metal plating film]
The base metal plating film of the present invention is a base metal plating film containing 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 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, berylium, chromium, germanium, vanadium, gallium, hafnium, At least one selected from the group consisting of indium, niobium, renium and tallium is mentioned, preferably at least one selected from the group consisting of copper, nickel, zinc, tin, chromium and permalloy, more preferably copper. 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 containing 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 that. In the case of 100% reflection, the glossiness is 1000.

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 770 or more, preferably 780 or more, more preferably 800 or more, and further preferably 850 or more.

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.

Further, as compared with the 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 of, for example, 10 or more (for example, 10 to 200) at an incident angle of 60 °. ) High, preferably 15 or more higher, more preferably 35 or more higher, particularly preferably 55 or more higher, most preferably 85 or more higher.

The base metal plating film of the present invention preferably has an increase in 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, as compared with 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. 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 the SEM method 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 111th surface is 100 nm or less, preferably 80 nm or less, more preferably 70 nm or less, still more preferably 60 nm or less, and particularly preferably 50 nm. Below, it is most preferably 45 nm or less, and the crystallite size (B) of 220 faces 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. It is as follows. The crystallite size ratio (A / B) of the 111th plane and the 220th 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) on the 111th surface is 25 nm or less, preferably 24 nm or less, more preferably 23 nm or less, still more preferably 22 nm or less, and 200 surfaces. The crystallite size (C) of is 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) between the 111-plane and the 200-plane is preferably 1.1 or more, and 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 (111 planes / 220 planes) of the 111 planes and 220 planes of the X-ray diffraction (XRD) pattern is preferably 3.0 or less. It is preferably 1.4 to 3.0.

When the conductivity of the annealed standard annealed copper of the copper plating film of the present invention is 100% IACS, the conductivity is preferably 80% IACS or more, more preferably 85% IACS or more, still more preferably 90% IACS or more, particularly preferably. Is 92% IACS or higher, most preferably 94% IACS or higher. The conductivity is obtained by obtaining the volume resistivity from the value of the surface resistivity by the four-point terminal method and the thickness of the plating film by a micrometer, and converting it into conductivity as IACS%. Further, the volume resistivity can be obtained as an average value of a plurality of points (for example, 5 points in the vertical and horizontal directions) of the plating film sample. IACS (international annealed copper standard)% defines the conductivity of annealed standard annealed copper (volume resistivity: 1.7241 × 10 ^-2 μΩm) as 100% IACS as the standard of electrical resistance.

Further, in the base metal plating film of the present invention, the hydrophilic ND particle content is, for example, 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 hydrophilic ND particle content (area%) can be measured by SEM observation in the cross section of the plating phase. In Comparative Examples 2 and 4 of the specification of the present application, neither the increase in glossiness nor the antioxidant effect was observed in the base metal plating film containing the non-hydrophilic ND. It has been clarified by the present inventors 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 to prevent aggregation. It is possible to obtain a plating film having high glossiness and excellent oxidation resistance. 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.

[Manufacturing method of base metal plating film]
The base metal plating film of the present invention can be produced by using an electrolytic plating method (preferably an electrolytic composite plating method) or a electroless plating method known per se. More specifically, base metal ions are formed by immersing a member to be plated film (for example, a conductive substrate such as a brass substrate) in a plating bath containing base metal ions and hydrophilic ND particles to perform electrolytic plating or electroless plating. Can be incorporated into the base metal film by precipitating the hydrophilic ND particles together with the hydrophilic ND particles on the surface of the member, and by continuing this until the desired thickness is obtained, the hydrophilic ND particles are contained in the base metal matrix. It is possible to produce 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.

The thickness of the base metal plating film can be appropriately set according to the application. For example, it is about 0.1 to 1000 μm. In the case of an application for covering the surface of a conductive metal member as a connecting 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 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, still more 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, particularly preferably 0.5 g / L). Yes, preferably 0.01-0.5 g / L. When the content of 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 state (or colloidally dispersed), 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 about 0 to 0.4. The haze can be measured according to the JIS K7136 method.

The particle size (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 size (D10) of the hydrophilic ND particles is, for example, 10 nm.

The particle size (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.

The particle size (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. 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 liquid to the plating liquid described later. 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 baths is, for example, 0.01 to 0.5 mol / L, preferably 0.05 to 0, in terms of the base metal ion concentration supplied to the base metal plating bath. It is 2 mol / L.

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

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 a salt thereof is adopted, the concentration of citric acid and / or a salt thereof in the electrolytic and electroless base metal plating bath is, for example, 0.02 to 1.0 mol / L, preferably 0.1 to 0.1. It is 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 a component include a pH buffer and a stabilizer for suppressing autolysis of the base metal plating bath.

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

(Plating liquid)
The plating solution in the present invention contains essential components for the preparation of the 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 blending, for example, a water-soluble base metal salt, a conductivity salt, a complexing agent, an additive for adjusting the appearance and physical characteristics 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 exist as a base metal oxygenate ion or a base metal complex ion bonded to a complexing agent.

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

(Hydrophilic ND particle dispersion and its preparation method)
The hydrophilic ND particle dispersion liquid is formed 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.

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

The particle size (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 size (D50) of the hydrophilic ND particles is, for example, 10 nm. The particle size of the hydrophilic ND particles in the hydrophilic ND particle dispersion can be measured by a dynamic light scattering method (DLS).

By adding the hydrophilic ND particle dispersion liquid to the base metal plating bath, gloss can be imparted to the obtained base metal plating film. Therefore, for example, it can be used as a brightener for a base metal plating film.

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

(Generation process)
First, an explosive equipped with an electric detonator is installed inside a pressure-resistant container for detonation, and the container is sealed in a state where a normal-pressure gas having an atmospheric composition and the explosive used coexist in the container. The container is made of iron, for example, and the volume of the container is, for example, 0.5 to 40 m ³ . As the explosive, a mixture of trinitrotoluene (TNT) and cyclotrimethylene trinitroamine or hexogen (RDX) can be used. The mass ratio of TNT to 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 to detonate the explosive 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 the carbon released by the explosive used as a partial incomplete combustion as a raw material. The generated ND particles are assembled very strongly between adjacent primary particles or crystallites due to the Coulomb interaction between crystal planes in addition to the action of van der Waals force to form an adhered body.

In the production step, the container and its inside are then cooled by allowing it to cool at room temperature for about 24 hours. After this cooling, ND particles are scraped off with a spatula to scrape the crude ND particle products (including the adherents and soot of the ND particles produced as described above) adhering to the inner wall of the container. A crude product is obtained.

(Acid treatment process)
The acid treatment step is a step of removing metal oxides by allowing a strong acid to act on the crude ND particle product as a raw material, for example, in an aqueous solvent. The crude ND particle product obtained by the detonation method tends to contain 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, by allowing a predetermined strong acid to act in an aqueous solvent, the metal oxide can be dissolved and removed from the crude ND particle product. The strong acid used for this acid treatment is preferably a mineral acid, 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 pressure. After such acid treatment, it is preferable to wash the solid content (including the ND adherent) with water until the pH of the precipitate reaches, for example, 2 to 3 by decantation. 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 process)
The oxidation treatment step is a step of removing graphite from the crude ND particle product using an oxidizing agent. The crude ND particle product obtained by the detonation method contains graphite (graphite), which did not form ND crystals of the carbon liberated due to partial incomplete combustion of the explosive used. Derived from carbon. For example, after undergoing the above acid treatment, graphite can be removed from the crude ND particle product by allowing a predetermined oxidizing agent to act in an aqueous solvent.

Examples of the oxidizing agent used in this 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. Examples thereof include mixed acids of and other acids (such as sulfuric acid), and salts thereof. In the present invention, it is particularly preferable to use a mixed acid (particularly, a mixed acid of sulfuric acid and nitric acid) because it is environmentally friendly and has an excellent action of oxidizing and removing graphite.

The mixing ratio (former / latter; mass ratio) of sulfuric acid and nitric acid in the mixed acid is, for example, 60/40 to 95/5, even under pressure near normal pressure (for example, 0.5 to 2 atm). For example, it is preferable that graphite can be efficiently oxidized and removed at a temperature of 130 ° C. or higher (particularly preferably 150 ° C. or higher; the upper limit is, for example, 200 ° C.). 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 decreases, so that the reaction temperature becomes, for example, 120 ° C. or less under pressure near normal pressure, and the graphite removal efficiency tends to decrease. There is. On the other hand, when the ratio of nitric acid in the mixed acid is less than the above range, the content of nitric acid that greatly contributes to the oxidation of graphite decreases, so that the efficiency of removing graphite tends to decrease.

The amount of the oxidizing agent (particularly the mixed acid) used 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, and particularly preferably 15 to 30 parts by mass with respect to 1 part by mass of the crude ND particle product. 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.

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 and the like. The amount of the catalyst used is, for example, about 0.01 to 10 parts by mass with respect to 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 pressure.

(Drying process)
In this method, it is preferable to next provide a drying step. For example, the liquid content is separated from the hydrophilic ND particle-containing solution having a hydrophilic functional group obtained through the above step by using a spray drying device, an evaporator or the like. After evaporation, the residual solids produced thereby are dried by heating and drying in a drying oven. The heating and drying temperature is, for example, 40 to 150 ° C. By going through such a drying step, ND powder can be obtained.

(Oxygen oxidation process)
In the oxygen oxidation step, a gas atmosphere furnace is used to heat the ND powder in a gas atmosphere having a predetermined composition containing oxygen. Specifically, ND powder is arranged in a gas atmosphere furnace, oxygen-containing gas is supplied or passed through the furnace, and the temperature inside the furnace is raised to the temperature condition set as the heating temperature to obtain oxygen. Oxidation treatment is carried out.

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 this oxygen oxidation treatment is preferably relatively high temperature, for example, 400 to 450 ° C. The oxygen-containing gas is a mixed gas containing an inert gas in addition to oxygen. Examples of the inert gas include nitrogen, argon, carbon dioxide, and helium. The oxygen concentration of the mixed gas is, for example, 1 to 35% by volume.

(Hydrogenation process)
If hydrophilic ND particles having a positive zeta potential are desired, a hydrogenation step is performed after the oxygen oxidation step described above. In the hydrogenation step, the ND powder that has undergone the oxygen oxidation step is heated in a gas atmosphere having a predetermined composition containing hydrogen by using a gas atmosphere furnace. Specifically, hydrogen-containing gas is supplied or passed through a gas atmosphere furnace in which ND powder is arranged, and the temperature inside the furnace is raised to the temperature condition set as the heating temperature for hydrogenation. The process is carried out. The temperature condition of this hydrogenation treatment is, 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. Examples of the inert gas include 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 being purified through the above series of processes, the hydrophilic ND particles have the morphology of cohesive particles (secondary particles) in which the primary particles interact very strongly and are assembled. Often taken. Therefore, it is preferable to perform a crushing step to separate the primary particles from the adherent. Specifically, first, the ND powder that has undergone the oxygen oxidation step or the subsequent hydrogenation step is suspended in pure water, and a slurry containing ND particles having _{hydrophilic functional groups (OH, COOH, NH 2, etc.) is prepared.} Prepare. In the preparation of the slurry, a centrifugation treatment may be performed to remove a relatively large aggregate from the hydrophilic ND particle suspension, or an ND particle suspension having a hydrophilic functional group may be subjected to sonication treatment. 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. A crushing treatment may be carried out by combining these. From the viewpoint of efficiency, it is preferable to use a bead mill.

By going through such a crushing step, an aqueous dispersion of ND particles containing ND primary particles having a hydrophilic functional group can be obtained. The dispersion obtained through the crushing step may be classified in order to remove coarse particles. For example, a classification device can be used to remove coarse particles from the dispersion by a classification operation utilizing centrifugation.

(Drying process)
In this method, it is preferable to next provide a drying step. For example, the liquid content is evaporated from the ND particle aqueous dispersion having a hydrophilic functional group obtained through the above step using a spray drying device, an evaporator or the like. After that, the residual solid content generated thereby is dried by heating and drying in a drying oven. The heating and drying temperature is, for example, 40 to 150 ° C. By undergoing such a drying step, ND particles containing a hydrophilic functional group can be obtained as a powder.

(Modification process)
The hydrophilic ND particles modified with a polyglycerin chain can be obtained, for example, by ring-opening polymerization of glycidol directly on the ND particles having a hydrophilic functional group obtained through the above steps. The ND particles have a carboxyl group or a hydroxyl group generated in 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.

In the reaction between ND particles having a hydrophilic functional group and glycidol (ring-opening polymerization), for example, glycidol and a catalyst are added to the ND particles having a hydrophilic functional group in an inert gas atmosphere and heated 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, phosphoric acid and the like, and examples of the basic catalyst include triethylamine, pyridine, dimethylaminopyridine, triphenylphosphine and the like.

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

After completion of the reaction, the obtained reaction product is preferably purified by, for example, filtration, centrifugation, extraction, washing with water, neutralization, or a combination thereof. As a result, the hydrophilic ND particle dispersion liquid (preferably, hydrophilic ND particle water dispersion liquid) in the present invention can be obtained. Glycidol is used for producing ND particles modified with polyglycerin, and 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 known techniques. Can be easily manufactured by a person skilled in the art by referring to.

[Electronic components]
The electronic component of the present invention is characterized by including the above-mentioned base metal plating film. The electronic component of the present invention may have another plating film other than the above-mentioned base metal plating film, and may have, for example, one layer or two or more undercoat plating films. The electronic components of the present invention include, for example, connection components for electronic devices such as personal digital assistants (PDAs) and mobile phones (for example, connectors).

[Glazed agent]
The brightener of the base metal plating film of the present invention is characterized by containing the above-mentioned 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 50% by mass or more. It is 60% by mass or more, particularly preferably 70% by mass or more, most preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[Antioxidant]
The antioxidant of the base metal plating film of the present invention is characterized by containing the above-mentioned 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 60% by mass or more, particularly preferably 70% by mass or more, most preferably 80% by mass or more, and particularly preferably 90% by mass or more.

Hereinafter, the present invention will be described in more detail 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 ND particle aqueous dispersion is measured by a precision balance with respect to the weighed value of 3 to 5 g of the weighed dispersion and the dry matter (powder) remaining after evaporating water from the weighed dispersion by heating. It was calculated based on the calculated value.

<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 a device manufactured by Malvern (trade name "Zetasizer Nano ZS"). , Measured by dynamic light scattering (non-contact backscattering method).

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

Preparation Example 1
A hydrophilic ND particle aqueous dispersion was prepared through the following steps.

(Generation process)
First, a molded explosive equipped with an electric detonator was installed inside a pressure-resistant container (made of iron, volume: 15 m ³ ) for detonation, and the container was sealed. As the 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, the container and its inside were cooled by leaving it at room temperature for 24 hours. After this cooling, the ND particle crude product adhering to the inner wall of the container (including the ND particle coagulant and soot produced by the detonation method) was recovered to obtain the ND particle crude product. ..

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

(Oxidation process)
Next, a mixed acid treatment was performed. Specifically, 6 L of a 98 mass% sulfuric acid aqueous solution and 1 L of a 69 mass% nitric acid aqueous solution are added to a precipitate (including an ND adhering body) obtained through decantation after acid treatment to form a slurry. , This slurry was heat-treated (heating temperature: 140 to 160 ° C.) for 48 hours under normal pressure conditions and reflux. Next, after cooling, the solid content (including the ND adherent) was washed with water by decantation. The supernatant liquid at the beginning of washing with water was colored, but the solid content was repeatedly washed with water by decantation until the supernatant liquid 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 spray-dried using a spray dryer (trade name "Spray Dryer B-290", manufactured by Nippon Buch Co., Ltd.). It was spray-dried. As a result, 50 g of ND powder was obtained.

(Oxygen oxidation process)
Next, 4.5 g of the ND powder obtained as described above was allowed to stand in the core tube of a gas atmosphere furnace (trade name "gas atmosphere tube furnace KTF045N1", manufactured by Koyo Thermo System Co., Ltd.), and the core tube was placed. After continuing to pass 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 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 temperature inside the furnace was raised to 400 ° C., which is the set heating temperature. 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, the oxygen-containing functional groups such as the carboxy group in the ND particles were evaluated by the following FT-IR analysis. ^{From the spectrum obtained by this analysis, absorption near 1780 cm -1} attributable to C = O expansion and contraction vibration was detected as the 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 "Spectrum 400 type FT-IR", manufactured by PerkinElmer 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, a Model-HC900 type Heat Chamber manufactured by ST Japan and a TC-100WA type Thermo Controller were used in combination.

(Crushing process)
First, 0.3 g of ND powder that had 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 slurry. Next, after adjusting the pH of the slurry by adding a 1N aqueous sodium hydroxide solution, an ultrasonic irradiator (trade name "ultrasonic cleaner AS-3", manufactured by AS ONE) was used. The ultrasonic irradiation was carried out for 2 hours. After that, bead milling was performed using a bead milling device (trade name "parallel four-cylinder sand grinder LSG-4U-2L type", manufactured by IMEX Co., Ltd.). Specifically, 30 mL of the slurry after ultrasonic irradiation and zirconia beads having a diameter of 30 μm were sealed in a 100 mL mill container, Vessel (manufactured by Imex Co., Ltd.), and the apparatus was driven to perform bead milling. In this bead milling, the input amount of zirconia beads is about 33% with respect to 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 centrifuged using a centrifuge device (classification operation). The centrifugal force in this centrifugation treatment was 20000 × 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 recovered 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, when measured using a pH test paper (trade name "Three Band pH Test Paper", manufactured by AS ONE Corporation), the pH was 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 ND particle aqueous dispersion 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 placed in a glass reactor, and used in an ultrasonic cleaner (trade name "BRANSON2510", manufactured by Marshall Scientific Co., Ltd.) at room temperature. It was sonicated for hours to dissolve. This was reacted at 140 ° C. for 20 hours while stirring in a nitrogen atmosphere. After cooling the reaction mixture, 120 mL of methanol was added, the mixture was sonicated, and then centrifuged at 50400 G for 2 hours to obtain a precipitate. To this precipitate, add 120 mL of methanol, repeat the washing-centrifugation step 5 times in the same manner, and finally use a dialysis membrane (Spectra / Prodialysis membrane, MWCO: 12-14 kDa) for the precipitate. Pure water dialysis was performed, the residual methanol was replaced with water, and the mixture was freeze-dried to obtain a gray powder of hydrophilic ND particles (PG-ND particles) modified with polyglycerin.

As a result of measuring the ratio of ND particles and surface modifying groups by TG-DTA thermal analysis, it was found that 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 a PG-ND particle aqueous dispersion.

[Example 1]
The PG-ND particle aqueous dispersion obtained in Preparation Example 1 was added to a copper plating solution (trade name "electroplating solution", manufactured by Kiyokawa Plating Industry Co., Ltd.) and plated 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 size of the PG-ND particles in the plating bath (1) was measured, the particle size (D10) was 30 nm, the particle size (D50) was 44 nm, and the particle size (D90) was 76 nm.

The plating bath (1) was transparent and had no turbidity.

A brass plate (length 20 mm × width 20 mm × thickness 1 mm) [manufactured by Kiyokawa Plating Industry Co., Ltd.] as a member to be formed with a plating film was degreased and washed.

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

[Example 2]
Plating bath (2) (PG-ND particle concentration in plating bath: 0.5 g / L) in the same manner as in Example 1 except that the amount of the PG-ND particle aqueous dispersion obtained in Preparation Example 1 was changed. ) Was obtained, 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) (PG-ND particle concentration in plating bath: 0.2 g / L) in the same manner as in Example 1 except that the amount of the PG-ND particle aqueous dispersion obtained in Preparation Example 1 was changed. ) Was obtained, 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) (PG-ND particle concentration in plating bath: 0.1 g / L) in the same manner as in Example 1 except that the amount of the PG-ND particle aqueous dispersion obtained in Preparation Example 1 was changed. ) Was obtained, 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) (PG-ND particle concentration in plating bath: 0.05 g / L) in the same manner as in Example 1 except that the amount of the PG-ND particle aqueous dispersion obtained in Preparation Example 1 was changed. ) Was obtained, 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) (PG-ND particle concentration in plating bath: 0.01 g / L) in the same manner as in Example 1 except that the amount of the PG-ND particle aqueous dispersion obtained in Preparation Example 1 was changed. ) Was obtained, 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) (PG-ND particle concentration in plating bath: 0.001 g / L) in the same manner as in Example 1 except that the amount of the PG-ND particle aqueous dispersion obtained in Preparation Example 1 was changed. ) Was obtained, 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]
Examples except that a copper plating solution (trade name "electrolytic plating solution", manufactured by Kiyokawa Plating Industry Co., Ltd.) plating bath (6) (excluding ND particle dispersion) was used instead of the plating bath (1). A brass plate having a copper plating film was obtained in the same manner as in 1. The plating film formed on the brass plate had irregularities on the surface and lacked smoothness.

<Gloss measurement>
Regarding the glossiness of the plating films obtained in Examples 1 to 7 and Comparative Example 1, a gloss meter "High gloss gloss checker IG-410" (manufactured by HORIBA, Ltd.) was used, and the glossiness m0 (mirror surface) under the following conditions. (Reflectance 100%) was measured.

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

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

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

From these results, it was clarified 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 concentration of ND (manufactured by Daicel, before PG modification) was adjusted to that with PG. Plating was carried out under the same conditions as in Example 1 using PG-modified ND while stirring. The same sample was used to confirm the glossiness and the antioxidant effect. Table 2 shows the results of measuring the glossiness of the obtained plating film (Comparative Example 2, Examples 3 and 4) immediately after production. As a result of copper plating with PG unmodified ND, the glossiness was similar to the glossiness without ND, and a clear difference was observed from the glossiness with the addition of PG modified ND. Further, XRD measurement of the copper plating film of Comparative Example 2 was carried out immediately after plating and 5 days later. The results are shown in FIG. Copper oxide was confirmed 5 days after the preparation of the plating film, and the antioxidant effect as confirmed by the PG-ND particles was not observed.

[Test Example 1]
In Example 1, the concentrations of PG-ND particles in the copper plating bath were 0 ppm, 200 ppm (0.02%), 400 ppm (0.04%), 600 ppm (0.06%), and 1000 ppm (0.1%). A copper plating bath was prepared in the same manner, and the haze was measured. The results are shown in Table 3.

[Test Example 2]
In Preparation Example 1, PG-unmodified ND particles obtained by the explosive method were subjected to crystal structure analysis using an X-ray diffractometer (trade name "Smart Lab", manufactured by Rigaku Co., Ltd.). As a result, a strong diffraction peak was observed at the diffraction peak position of diamond, that is, the diffraction peak position from the (111) plane of the diamond crystal, and it was confirmed that the PG unmodified ND particles 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 diffractometer (commodity). Small-angle X-ray scattering measurement (SAXS method) is performed using the name "Smart Lab" (manufactured by Rigaku), and scattering is performed using particle size distribution analysis software (trade name "NANO-Solver", manufactured by Rigaku). The primary particle size of nanodiamonds was estimated for the region with an angle of 1 ° to 3 °. In this estimation, it is assumed that the nanodiamond primary particles are spherical and the particle density is 3.51 g / cm ³ . The ND particles obtained by the impact compression method used trade names: SCM NanoDia, manufactured by Sumiseki Materials Co., Ltd., and the PG-modified ND particles obtained by the impact compression method were prepared in the same manner as in Preparation Example 1. It was PG-modified. Table 4 shows the measurement results of the particle size by the SAXS method.

[Test Example 3]
Micro angles of the plating films obtained in Example 1 (copper plating solution containing PG-ND 200ppm), Comparative Example 1 (plating solution not containing ND), and Comparative Example 2 (plating solution containing PG unmodified ND). Immediately after plating, 5 days after plating, and 7 days after plating, the diffraction peaks on the 111th surface of copper oxide were measured by the incident X-ray diffraction method as follows.

(1) Micro-angle incident X-ray diffraction method In order to analyze the surface structure of the copper plating table, the micro-angle incident X-ray diffraction (GIXD) method was used.
This method utilizes the fact that total reflection occurs when X-rays are incident on the flat surface of a substance, and measures reflection, refraction, and diffraction while slightly changing the angle before and after the angle at which total reflection occurs. The method. This time, using SmartLab (manufactured by Rigaku), the measurement was performed with an incident angle of about 0.7 ° and a measurement angle of 30 ° to 100 °.

(2) Storage conditions of plating film The brass plate having the copper plating film obtained in Example 1 and Comparative Examples 1 and 2 is stored in a room not exposed to direct sunlight for 5 days or 1 week (normal temperature of about 25 ° C, humidity). About 50%).

(3) Measurement results The results are shown in Table 5.

After 7 days, the peak intensity of the 111 surface of copper oxide was 2.5% with respect to the peak intensity of the 111 surface of copper in no ND (Comparative Example 1), whereas the peak of copper oxide was found in the PG-modified ND (Example 3). It was 0.1%.

[Example 8 and Comparative Example 3]
Using the following tin (Sn) plating solution, Sn plating the brass plate in the same manner as in Example 1 (PG-ND particle concentration in Sn plating bath: 0.2 g / L (Example 8) or 0 g / L (Comparative Example 3)), a brass plate having a Sn plating film was obtained. Table 6 shows the results of measuring the glossiness and surface roughness (Ra) of the obtained brass plate having the Sn plating film.
-Sn plating solution composition: stannous sulfate 30 g / L, sulfuric acid 130 g / 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 Ni plating bath: 0.2 g / L (Example 9). Alternatively, a brass plate having a Ni plating film at 0 g / L (Comparative Example 4) was obtained. Table 6 shows the results of measuring the glossiness and surface roughness (Ra) of the obtained brass plate having the Ni plating film.
-Nickel plating solution composition: nickel sulfate 250 g / L, nickel chloride 40 g / L, boric acid 30 g / 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 Zn plating bath: 0.2 g / L (Example 10). Alternatively, a brass plate having a Zn plating film at 0 g / L (Comparative Example 5) was obtained. Table 6 shows the results of measuring the glossiness and surface roughness (Ra) of the obtained brass plate having the Zn plating film.
-Zinc plating solution composition: Zinc oxide 10 g / L, sodium hydroxide 100 g / 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 the brass plate was performed in the same manner as in Example 1 and Comparative Example 1 (PG-ND particle concentration in the permalloy plating bath: 0. A brass plate having a permalloy plating film at 2 g / L (Example 11) or 0 g / L (Comparative Example 6) was obtained. Table 6 shows the results of measuring the glossiness and surface roughness (Ra) of the obtained brass plate having the permalloy plating film.
-Permalloy plating solution composition: nickel sulfate 250 g / L, nickel chloride 40 g / L, boric acid 30 g / L, ferrous sulfate 24 g / L, malonic acid 5 g / 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 measurement system KS-1100 (manufactured by KEYENCE).

It has been clarified 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 of glossiness.

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

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

[Comparative Example 7]
Using the plating bath (6) of Comparative Example 1, a stainless steel plate having a copper plating film was obtained in the same manner as in Comparative Example 1 except that 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 PG-ND 20 ppm) and Comparative Example 7 (plating solution not containing ND) was peeled off, and the plating film was placed on the 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
Measurement point: Up, down, left, right, middle (5 points)
Measurement method: The plating film is peeled off from the stainless steel plate and measured on a separately prepared glass plate.

Specifically, the thickness of the plating film measured with a micrometer was input to Loresta GX, and the volume resistivity was measured (4-point terminal method). For the volume resistivity, the conductivity of annealed standard annealed copper (volume resistivity: 1.7241 × 10 ^-2 μΩm) was converted into conductivity with 100% IACS. The results are shown in Table 8.

It was clarified 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 to which the hydrophilic nanodiamond (PG-ND) was not added.
The base metal plating film of the present invention to which hydrophilic nanodiamond (PG-ND) is added has an unexpected effect of preventing an increase in crystallite size, maintaining hardness, and improving conductivity.

[Test Example 6]
With respect to the copper plating films obtained in Example 3 (copper plating solution containing PG-ND 200 ppm) and Comparative Example 1 (copper plating solution not containing ND), the crystallite sizes of 111 faces and 220 faces were measured. The crystallite size was measured by the X-ray diffraction method (XRD) using CuKα ray as an X-ray source from the half width of the diffraction peak and the diffraction angle using Scherrer's equation. The measuring device was made by Rigaku [SmartLab], and the optical system used the centralized method. The results are shown in Table 9. Further, the XRD pattern of the copper plating film is shown in FIG. 5, and the peak intensity ratio between the 111th surface and the 220th surface is shown in Table 10.

It was clarified that the copper-plated film containing PG-ND obtained in Example 3 had small crystallite sizes on both 111 and 220 surfaces and was excellent in indentation hardness (surface hardness).

[Test Example 7]
Crystals of 111 and 200 surfaces of nickel plating 3 months after plating of the plating films obtained in Example 9 (nickel plating solution containing PG-ND 200 ppm) and Comparative Example 4 (nickel plating solution not containing ND). The child size was measured. The crystallite size was measured by the X-ray diffraction method (XRD) using CuKα ray as an X-ray source from the half width of the diffraction peak and the diffraction angle using Scherrer's equation. The measuring device was made by Rigaku [SmartLab], and the optical system used the centralized method. The results are shown in Table 11.

It was clarified that the nickel-plated film containing PG-ND obtained in Example 9 had small crystallite sizes on both 111 and 200 surfaces and was excellent in indentation hardness (surface hardness).

[Test Example 8]
For the plating films obtained in Example 9 (nickel plating solution containing PG-ND 200ppm) and Comparative Example 4 (nickel plating solution not containing ND), cross sections were prepared with a focused ion beam processing device, and a backscattered electron image was obtained. Observation was carried out.
Device name: FIB-SEM device (FEI Versa3D Dual Beam). FIG. 6A shows the plating film containing no ND particles of Comparative Example 1, and it can be seen that the surface roughness (Ra) is large. FIG. 6B shows the plating film containing the ND particles of Example 1, and the small black dots indicated by the arrows are the ND particles.

[Test Example 9]
For the plating film obtained in Example 1 (copper plating solution containing PG-ND 200ppm), the apparatus was in a Cu plating film by X-ray photoelectron spectroscopy (XPS) using ULVAC-PHI (PHI5800 ESCA system). Carbon content (C1s) was measured. The results are shown in FIG. Carbon content was detected in the Cu film.

1 ND particles with surface modifying groups 2 ND particles (partial)
3 Surface modifying group

Claims (21)

A base metal plating film containing a base metal matrix and hydrophilic nanodiamond particles dispersed in the base metal matrix. The base metal plating film according to claim 1, which has a glossiness of 10 or more at an incident angle of 60 ° as compared with the same base metal plating film as described above except that it does not contain the hydrophilic nanodiamond particles. With respect to the base metal plating film immediately after production, the increase in base metal oxide after storage in a room not exposed to direct sunlight at 25 ° C. and humidity of 50% for 7 days is less than 1%, preferably less than 0.5%, more preferably. The base metal plating film according to claim 1 or 2, wherein is less than 0.3%, most preferably less than 0.1%. The base metal plating film according to any one of claims 1 to 3, which is surfactant-free. The base metal plating film according to any one of claims 1 to 4, wherein the hydrophilic nanodiamond particles are the nanodiamond particles of (i) or (ii) below.
(i) Nanodiamond 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, berylium, chromium, germanium, vanadium, gallium, hafnium, indium, The plating film according to any one of claims 1 to 5, which is at least one selected from the group consisting of niobium, permalloy, renium and tirconium. The base metal plating film according to any one of claims 1 to 6, wherein the average particle diameter (D50) of the hydrophilic nanodiamond particles dispersed in the base metal matrix is in the range of 4 to 95 nm by the SEM method. Hydrophilic polymers are polyglycerin, polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, poly (meth) acrylic acid, polyacrylamide, polyethyleneimine, vinyl ether-based polymers, cellulose derivatives, water-soluble polyesters, water-soluble phenol resins, natural highs. 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) on the 111th surface is 100 nm or less, the crystallite size (B) on the 220th surface is 80 nm or less, and the crystallite size ratio between the 111th surface and the 220th surface (A / B). ) Is 1.3 or more, the base metal plating film according to any one of claims 1 to 8. 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 planes / 220 planes) of the 111 planes and 220 planes of the X-ray diffraction pattern is 3.0 or less. film. The base metal is nickel, the crystallite size (A) on the 111-plane is 25 nm or less, the crystallite size (C) on the 200-plane is 23 nm or less, and the crystallite size ratio between the 111-plane and the 200-plane (A / C). ) Is 1.1 or more, the base metal plating film according to any one of claims 1 to 8. A base metal plating bath containing base metal ions and hydrophilic nanodiamond particles and having a concentration of hydrophilic nanodiamond particles of 0.001 to 1 g / L. The base metal plating bath according to claim 12, wherein the haze is 0 to 0.5. The base metal plating bath according to claim 12 or 13, wherein the hydrophilic nanodiamond particles (D10) in the base metal plating bath have a particle size (D10) of 10 to 60 nm. The base metal plating bath according to claim 12 or 13, wherein the hydrophilic nanodiamond particles (D50) in the base metal plating bath have a particle size (D50) of 10 to 70 nm. The base metal plating bath according to claim 12 or 13, wherein the hydrophilic nanodiamond particles (D90) in the base metal plating bath have a particle size (D90) of 10 to 90 nm. Claims 1 to 1, wherein the subject is immersed in a base metal plating bath containing base metal ions and hydrophilic nanodiamond particles and having a concentration of nanodiamond particles of 0.001 to 1 g / L to perform electrolytic plating. The method for producing the plating film according to any one of 11. The method for producing a plating film according to claim 17, wherein the base metal plating bath has a haze of 0 to 0.5. An electronic component provided with the plating film according to any one of claims 1 to 11. A brightener for base metal plating films containing hydrophilic nanodiamond particles. Antioxidant for base metal plating films containing hydrophilic nanodiamond particles.

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