US20160032478A1

US20160032478A1 - Plating film, method of manufacturing plating film, and plated product

Info

Publication number: US20160032478A1
Application number: US14/776,539
Authority: US
Inventors: Noriyuki Saito
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2013-03-19
Filing date: 2014-02-28
Publication date: 2016-02-04
Also published as: JPWO2014148227A1; WO2014148227A1; JP6471688B2

Abstract

There are provided a plating film having high durability and high reliability, a method of manufacturing the plating film, and a plated product using the plating film. The plating film according to the disclosure is formed with use of a solvent in which a metallic salt is dissolved and a compound having functionality is dissolved or colloidally dispersed, and the metal and the compound having the functionality are homogenously dispersed and joined.

Description

TECHNICAL FIELD

The present disclosure relates to a plating film formed by electrolytic plating, to a method of manufacturing the plating film, and to a plated product using the plating film.

BACKGROUND ART

In a component, a mechanical component, and the like of an electronic apparatus and a communication apparatus, metal plating is used as surface treatment in order to improve abrasion resistance and to reduce contact electric resistance. In recent years, a so-called functional plating film has been developed in which functionality such as water repellency, oil repellency, and lubricity is provided to a plating film formed by the metal plating.
A method of providing the above-described functionality to a plating film has been in practical use in surface treatment for a heating part of an electric iron, scissors for mowing. The method is called composite plating in which microparticles (normally, each having a particle diameter of 0.03 to 5 μm) having functionality that is to be provided to the plating film, specifically, for example, diamond, molybdenum sulfide, a fluorine resin, a nitride, or a metal oxide may be dissolved together with a surfactant in a plating solution, and a plating metal and the above-described microparticles are precipitated (coprecipitated) by electroless plating on an object to be plated (for example, see PTLs 1 and 2). As a result, it is possible to provide a function of hardness, abrasion resistance, heat resistance, water repellency, lubricity, and the like, to an object to be plated.

CITATION LIST

Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No. 2012-92416
PTL 2: Japanese Unexamined Patent Application Publication No. 2009-288463

SUMMARY OF INVENTION

However, in the plating film formed by any of the methods in the PTLs 1 and 2, distribution of particles in the plating film is easily biased due to difference in specific gravity between the plating film and the microparticles having functionality. Accordingly, there are issues of occurrence of film peeling and a crack due to temperature change, and occurrence of unevenness in expression of the functionality in the plating film.
Accordingly, it is desirable to provide a plating film having high durability and high reliability, a method of manufacturing the plating film, and a plated product using the plating film.
A plating film according to an embodiment of the technology includes a metal and a compound having functionality, and the metal and the compound are homogeneously dispersed and joined.
A method of manufacturing a plating film according to an embodiment of the technology uses a solution in which a metal is dissolved and a compound having functionality is dissolved or colloidally dispersed.
A plated product according to an embodiment of the technology includes the above-described plating film.
In the plating film, the method of manufacturing the plating film, and the plated product according to the respective embodiments of the technology, the plating film is formed with use of the solution in which the metallic salt of the metal configuring the plating film is dissolved and the compound having the functionality is dissolved or colloidally dispersed. Accordingly, the metal configuring the plating film and the compound having the functionality (functional compound) are homogenously dispersed and joined.
According to the plating film, the method of manufacturing the plating film, and the plated product of the respective embodiments of the technology, the metal configuring the plating film and the compound having the functionality (the functional compound) are homogenously dispersed and joined. Therefore, distribution of the compound having the functionality is homogenized, which improves durability of the plating film. In addition, it becomes possible to improve homogeneity and reliability of characteristics provided to the plated product.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a sectional structure of a plating film according to an embodiment of the disclosure.

FIG. 2 is a flowchart of steps of manufacturing the plating film illustrated in FIG. 1.

FIG. 3A is a schematic diagram before conduction of a plating bath in the steps of manufacturing the plating film illustrated in FIG. 1.

FIG. 3B is a schematic diagram during the conduction of the plating bath illustrated in FIG. 3A.

FIG. 4 is a waveform diagram of an applied voltage (AC).

FIG. 5 is a schematic diagram of a sectional structure of a plating film in a related art.

DESCRIPTION OF EMBODIMENTS

An embodiment of the disclosure will be described in detail below with reference to drawings. Note that description will be given in the following order.

1. Embodiment

1-1. Structure of plating film
1-2. Method of manufacturing plating film

2. Application Examples

3. Examples

1. Embodiment

1-1. Structure of Plating Film

FIG. 1 schematically illustrates a sectional structure of a plating film (a plating film 10) according to an embodiment of the disclosure. The plating film 10 is formed of a metal (a plating metal 11) and a compound having functionality (a functional compound 12), and provides a function of water repellency, oil repellency, lubricity, or the like to an object to be plated such as a metal product and a metal component. In the present embodiment, for example, the plating film 10 may be formed, by non-aqueous plating, in a state where the plating metal 11 and the functional compound 12 are homogeneously dispersed as illustrated in FIG. 1. Here, homogeneous indicates a state in which the functional compound 12 is uniformly distributed without deviation in an in-plane direction and a film thickness direction of the plating film 10, as illustrated in FIG. 1. Specifically, for example, the homogeneous indicates a state in which the plating metal 11 and the functional compound 12 is coprecipitated at a molecular level at the time of forming the plating film 10 by plating operation, and the functional compound 12 is directly joined with the plating metal 11. Alternatively, the homogeneous indicates a state in which one or more functional compounds are coupled with a metal grain (metal crystal grain boundary of the plating metal 11). Alternatively, the homogeneous indicates a state in which the plating metal 11 and the functional compound 12 are in a so-called solid solution state.
The plating metal 11 is not particularly limited as long as the plating metal is dissolved in a plating solvent of non-aqueous plating described later. Specific examples of the plating metal may include lithium (Li), beryllium (Be), boron (B), sodium (Na), magnesium (Mg), aluminum (Al), silicon (Si), potassium (K), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), arsenic (As), rubidium (Rb), strontium (Sr), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), tin (Sn), antimony (Sb), cesium (Cs), barium (Ba), hafnium (Hf), tantalum (Ta), tungsten (W), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), lead (Pb), and bismuth (Bi).
The functional compound 12 has a function of water repellency, oil repellency, lubricity, or the like as described above. Examples of the compound having these functions may include fluorine-based compound, silicon-based compound, hybrid compound of fluorine and silicon, and fatty oils. Among them, the fluorine-based compound is most suitable for the method in the present embodiment because the fluorine-based compound exhibits high effect by a small amount.
In the present embodiment, the functional compound that is dissolved in the plating solvent or maintains colloidal state in plating is used. In addition, one or two or more kinds of the functional compound 12 described below may be combined and used.
Examples of the fluorine-based compound may include a compound (fluoroalkyl compound) having a functional group in which a part or all of hydrogen atoms of an alkyl group are substituted with fluorine atoms. Specifically, out of fluoroalkyl compounds, a compound having a hydroxyl group, a carboxyl group, a phosphate group, or the like as an end group may be used singly, or may be coupled with other compound having reactivity with these compounds (alternatively, a compound subjected to structure modification appropriately in order to prepare reflectivity) and used. In other words, fluoroalkyl ether, fluoroclkyl ester, or the like may be used. Note that the number of ether bonds or ester bonds in one molecule is not particularly limited as long as the compound is dissolved in a solvent or maintains the colloidal state. An amount of the compound with respect to the plating solution may be appropriately adjusted within a range where phase separation of the compound does not occur in the plating solution. It is desirable to avoid the phase separation because unevenness occurs on the plated surface when the phase separation occurs.
Examples of the commercially-available fluorine-based compound may include Braycoat (trademark; Castrol Limited), Fomblin (trademark; Solvay), Krytox (trademark; Du Pont), Demnum (trademark; Daikin Industries, Ltd.), Barrierta (trademark; NOK Klüber Co., Ltd.), Sumitec (trademark; Sumico Lubricant Co., Ltd), Multemp (trademark; Kyodo Yushi Co., Ltd.), and Surflon (trademark; AGC Seimi Chemical Co., Ltd.).
As the solvent of the plating metal 11 and the functional compound 12 (a plating solvent), a solvent dissolving the metallic salt of the plating metal 11 that is a supply source of plating metal and dissolving or colloidally dispersing the functional compound 12 may be used. As the solvent dissolving the metallic salt, a highly-polar organic solvent is suitable, and a highly-polar organic solvent containing a heteroatom of nitrogen (N), sulfur (S), oxygen (O), or the like in a molecule may be preferable. The highly-polar organic solvent is mixed with a low-polar solvent to obtain a mixed solvent with appropriate polarity. According to combination of the metallic salt of the plating metal 11 and the functional compound 12, for example, the organic solvents described below may be used singly or as a mixture of two or more solvents.
Examples of the nitrogen-containing organic solvent may include acetonitrile, N-methylpyrrolidone, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethyl propylenediamine, formamide, N,N-dimethylformamide, N,N-dimethylacetamide, β-lactam, γ-lactam, δ-lactam, 2-pyrrolidinone, N-methyl-2-pyrrolidinone, N-vinyl-2-pyrrolidinone, 2-oxazolidone, and 1,3-dimethyl-2-imidazolidinone.
Examples of the sulfur-containing organic solvent may include sulfolane, dimethyl sulfoxide, dimethyl sulfone, 2-mercaptoethanol, 3-mercapto-1-propanol, 3-mercapto-1-propanol, 2,3-dimercapto-1-propanol, 3-mercapto-1,2-propanediol, 1,3-propanedithiol, and thiodiglycol.
Examples of the oxygen-containing organic solvent may include propylene carbonate, dimethylcarbonate, ethylenecarbonate, methyl acetate, ethyl acetate, γ-butyrolactone, dimethoxyethane, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, hexanetriol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,2-propanediol, 1,4-butanediol, 2-methyl-1,4-butanediol, 1,3-butanediol, 1,2-butanediol, glycerol, 2,3-butanediol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobuthyl ether, triethylene glycol monomethyl ether, triethylene glycol monobuthyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, tripropylene glycol monomethyl ether, diethylether, tetrahydrofuran, acetone, and methyl ethyl ketone. Note that an acidic solvent easily isolating proton causes generation of hydrogen on a cathode, and therefore it is desirable to avoid the use of the acidic solvent.
Also, when the polarity of the functional compound 12 to be coprecipitated with the plating metal 11 is small, it is possible to enhance compatibility by using a low-polar organic solvent; however, typically, the plating metal 11 is easily dissolved in a highly-polar organic solvent. In such a case, as the plating solvent, the highly-polar solvent to dissolve the metallic salt and the low-polar solvent to dissolve the functional compound 12 may be mixed at an appropriate ratio and the mixed solvent may be used. Alternatively, the metallic salt is dissolved in the highly-polar solvent, and the low-polar functional compound 12 may be colloidally dispersed in this highly-polar solvent, and the resultant may be used.
Examples of the low-polar organic solvent may include a halide such as dichloromethane, dichloroethane, chloroform, and dichlorobenzene, an aromatic compound such as benzene, toluene, and xylene, and an aliphatic compound such as hexane, heptane, and octane.
Also, as the plating solvent, molecular weight may be adjusted by polymerization of polymerizable monomer having large polarity with use of the fact that the polarity of the entire molecule decreases as the molecular weight increases, and a plating solvent whose polarity is controlled may be used. Note that it is desirable to avoid a plating solvent that causes resolution and polymerization by plating operation such as heating and voltage application. Accordingly, examples of the preferable polymerizable monomer may include glycols such as ethylene glycol, propylene glycol, and butylene glycol. As described above, the plating solvent may include one of a monomer and a polymer of a polymerizable compound, or non-polymerizable compound.
As described above, although the organic solvent is described as the plating solvent, the above-described organic solvent added with water may be used depending on solubility of the functional compound.
Moreover, the plating film 10 may control the precipitation form of the plating metal 11 by selecting a kind of the plating solvent. Typically, degree of ionization of the compound (for example, the metallic salt of the plating metal 11) dissolving in the solvent becomes higher as the polarity of the plating solvent becomes higher. Therefore, ionic conductance of the solvent becomes higher and precipitation rate of the plating metal 11 also increases. At this time, whisker-like metallic crystal called whisker easily grows depending on the kind of the metal to be precipitated. The whisker causes short circuit between electrodes. Moreover, even in the case of a metal difficult to cause whisker, the metallic crystal precipitated easily increases in size, which influences hardness, peeling strength, color, gloss, etc. of the plating film 10. Therefore, the precipitation form of the plating metal 11 is first observed, and a solution in which ion conductivity is decreased to a level where a glossy metallic film with suppressed whisker is obtained, by combining the metallic salt to be used for plating, temperature of the plating solution, or application voltage and the waveform thereof, based on the result of the observation, may be preferably used as the plating solvent in the present embodiment.
An additive such as a brightener and a supporting electrolyte may be added to a plating solution R. Properties of the brightener and the supporting electrolyte may be considered similarly to those of aqueous plating typically used.
The brightener caps a projection generated on a surface of the plating film 10 to prevent electric field concentration, thereby planarizing the plating film 10. Examples of the brightener may include typically an organic compound having high absorptive property, namely, having large polarization in a molecule, for example, an organic compound containing a functional group such as a carboxyl group, an aldehyde group, an ester group, a hydroxy group, a thiol group, a cyano group, a sulfonic group, an amide group, and an imide group. Specific examples thereof may include thiourea, coumarin, ethylene cyanohydrin, and saccharin. Note that there is a case where a compound added as the functional compound 12 or an organic solvent as a plating solvent itself expresses a function of the brightener.
The supporting electrolyte is to enhance the conductivity of the electrolytic solution (the plating solution R). The supporting electrolyte is selected from salts easily ionized at the time of being dissolved in the plating solvent. When the plating solvent is the organic solvent, the perchlorate of tetraalkylammonium, tetrafluoroborate, or the like is often used. Specific examples thereof may include ammonium perchlorate, tetramethylammonium perchlorate, tetraethylammonium perchlorate, tetramethylammonium tetrafluoroborate, and tetraethylammonium tetrafluoroborate. When the plating solvent contains water, metal halide, metal nitrate, or the like is often used. Specific examples thereof may include sodium chloride, lithium chloride, sodium nitrate, lithium nitrate, sodium perchlorate, and lithium perchlorate.
Hereinafter, a method of manufacturing the plating film 10 according to the present embodiment is described.

1-2. Manufacturing Method

In the method of manufacturing the plating film 10 according to the present embodiment, non-aqueous plating is used. In the non-aqueous plating, an organic solvent is used as a main plating solvent.
FIG. 2 illustrates a flow of steps of manufacturing the plating film 10 with use of electrolytic plating according to the present embodiment. The metallic salt of the plating metal 11 is dissolved in an appropriate solvent. The functional compound 12 is added thereto, and dissolved or colloidally dispersed. At this time, the solvent may be used singly or as a mixture of two or more solvents (step S101).
Subsequently, the plating solution R is placed in a plating bath 31 (FIG. 3A) that has an anode electrode 32 provided with a supply source (a metal plate 32A) of the plating metal 11 and a cathode electrode 33 provided with an object to be plated, and the plating solution R is adjusted to predetermined temperature while being stirred (step S102). Here, the temperature of the plating solution R may be arbitrarily set within a range where the plating solution R exhibits suitable fluidity and is free from deposition and precipitation of electrolyte. Since the ion conductivity of the plating solution R is increased as the temperature is set higher, the precipitation rate of the plating metal on the cathode electrode 33 also increases. In the case of the non-aqueous plating, it is possible to set the temperature of the plating solution R to be higher with use of a high-boiling organic solvent, a molten salt, an ionic liquid, or the like, as the plating solvent. Incidentally, there is a case where oxidation reduction reaction or the like between the organic solvent and the electrode is accelerated by high temperature, which may cause deterioration of the electrode. In addition, there is a case where the metal used for the electrode functions as a catalyst and accelerates resolution and polymerization of the organic solvent. Therefore, the organic solvent corresponding to the material of the electrode to be used may be desirably selected, and plating operation may be desirably carried out at appropriate temperature.
Next, a predetermined voltage is applied to the anode electrode 32 and the cathode electrode 33 to cause coprecipitation of the plating metal 11 and the functional compound 12 on the object to be plated 20 that is disposed on the cathode electrode 33, as illustrated in FIG. 3B (step S103). Here, there is a case where whisker occurs on the surface of the plating layer 11 as described above or a diameter of crystal grain of the precipitated metal is changed by the voltage or the temperature. For example, these appear as fine irregularity on the surface of the plating layer 11 or as difference in color. These changes depend on a kind of a metal to be plated; however, controlling the waveform of the application voltage makes it possible to homogenize the grain diameter to some extent. Both of a DC voltage and an AC voltage may be used as the application voltage; however, for the above-described reason, an AC voltage including a large number of controllable parameters may be preferably used.
It is possible to set an arbitrary voltage waveform and then apply the AC voltage. The voltage waveform may be, for example, a rectangular wave, a sine wave, or a triangle wave. FIG. 4 illustrates the waveform of the application voltage used in Examples described later. It is unnecessary for the cathode electrode 33 to be a minus (−) voltage constantly, and the voltage of the cathode electrode 33 may be switched over to a plus (+) voltage within a range where the precipitated metal remains. It is possible to dissolve generated whisker and a part where electric field concentration easily occurs such as a projection, by this operation. It becomes possible to improve flatness (specularity and gloss level) of the surface of the plating film 10 and to increase the thickness of the plating film 10 by using the property.
Note that it is considered that, by the AC voltage, the thickness of a diffusion layer of the plating solution R formed on the surface of the plating film 10 is decreased to about one-tenth of that by the DC voltage. Therefore, it is considered that the plating film 10 is formed at high current density of several hundred times or several thousand times of that by the DC voltage, the generation rate of the crystalline nucleus often exceeds the growth rate, and thus it is possible to form fine metallic crystal.
In this way, the plating film 10 illustrated in FIG. 1 is formed.
Incidentally, water is not necessarily eliminated entirely as the plating solvent, and water may be added to the organic solvent depending on a case. There is a case where moisture contained in the organic solvent as the plating solvent or crystalline water contained in the metallic salt exhibits an effect similar to that in the case where water is added to the organic solvent. Incidentally, in a case where a highly hydrophobic compound is used as the functional compound 12 to be coprecipitated with the plating metal 11 on the object to be plated 20 and the plating operation is carried out with use of the plating solution R in which the highly hydrophobic compound is sufficiently compatible with the organic solvent and adjusted, an amount of moisture in the plating solution 11 may be desirably managed. The amount of moisture contained in the state of the plating solution R may be preferably equal to or lower than a volume of the organic solvent. More preferably, the amount of moisture may be equal to or lower than 10%. In the case where the highly hydrophobic compound is used, a solvent dehydrated by dehydration treatment is used. In this case, the plating operation may also be preferably carried out in a dry box in which the inner air is substituted with nitrogen or argon.
FIG. 5 illustrates a sectional structure of a plating film 110 formed with use of a typical composite plating. A functional plating film provides a function of, for example, water repellency, oil repellency, or lubricity to an object to be plated, by combining a plating metal and a material having any functionality as described above. When the plating film 110 is formed with use of the composite plating, functional particles 112 are often different in specific gravity from the plating solution in which a plating metal 111 is dissolved, and the surface thereof often have no affinity with the plating solution. Accordingly, if both are simply mixed and stirred, it is difficult to disperse the functional particles 112 homogenously in the plating solution. Thus, an attempt has been made to enhance affinity of the particle surface to the plating solution by performing surface treatment, for example, irradiation of an active energy ray such as an ultraviolet ray to the functional particles 112, adding a surfactant to the plating solution, or performing surface treatment on the functional particles 112 with use of silane coupling agent. However, it is difficult to sufficiently resolve the distribution issue of the functional particles 112 in the formed plating film 110 even by performing such operation.
In such a plating film 110, the functional particles are dispersed inhomogeneously in the plating metal 111. Accordingly, when the coefficient of thermal expansion of the plating metal 111 is different from that of the functional particles 112, the metal and the particles of the functional particles 112 are peeled off in the plating film 10, and the peeled-off metal and the peeled-off particles are coupled, which may cause crack. Alternatively, the particles of the functional particles 112 on the surface of the plating film 110 may fall off, which may cause pinhole. Moreover, when the content percentage of the functional particles 112 to the plating film 110 is large, the plating film 110 becomes fragile. Further, since a size of each of the functional particles 112 typically used is about 0.03 to 5 μm normally, it is difficult to use the plating film 110 for a component demanding accuracy at nano level, such as micro electro mechanical systems (MEMS).
In contrast, in the method of manufacturing the plating film 10 according to the present embodiment, non-aqueous plating is used. It is possible for the non-aqueous plating to coprecipitate wide variety of metals as compared with plating using water as a solvent (aqueous plating). This is because hydrogen gas derived from water or proton is difficult to be generated in the non-aqueous plating, and thus it is possible to precipitate a metal whose oxidation-reduction potential is significantly low (for example, an alkali metal and alkaline earth metal). Further, in the non-aqueous plating, it is possible to precipitate a metal having high affinity for oxygen, such as Al, Ti, Tl, Nb, and V that are not precipitated by aqueous plating due to oxygen and dissolved oxygen derived from water.
Moreover, in the non-aqueous plating, selecting a low protic solvent as the plating solvent makes it possible to suppress generation of hydrogen on the cathode electrode even when a high voltage (for example, 10 V or higher) is applied. Therefore, it is possible to suppress generation of pinhole on the plated surface caused by generation of bubbles. Further, it is possible to control the property of the plating solvent by mixing a plurality of organic solvents. This makes it possible to widen a control range of the characteristics of the plating film 10.
In the present embodiment, the plating metal 11 is dissolved in the plating solvent with use of the above-described non-aqueous plating, and the plating film 10 is formed in a state where the functional compound 12 is dissolved or colloidally dispersed in the plating solvent. As a result, it is possible to form the plating film 10 in which a metal configuring the plating film and a compound having functionality (a functional compound) are homogeneously dispersed and joined, that is, are homogeneously mixed at molecular level.
The plating film 10 formed in this way maintains the functionality if the plating film 10 is worn away. In other words, as compared with the above-described plating film 110 formed by the composite plating, crack is difficult to occur in the plating film 10, and resistance to bending, batting, and the like is enhanced. In addition, a factor causing a pinhole, such as falling off of the functional particles 112 in the plating film 110 is eliminated. Accordingly, it is possible to provide the plating film 10 that has improved durability, functionality expressed with high uniformity, and improved reliability, and to provide a plated product including the plating film 10.

2. Application Examples

The plating film 10 described in the above-described embodiment is applicable to various kinds of plated products. Specifically, the plating film 10 may be applicable to, for example, a metal product, a metal component, a gear, a bearing, an edge of a skate, a ski board, a snowboard, and the like. As a result, rust-proof function, lubricity, and the like are imparted to the above-described products. In addition, it is possible to impart corrosion resistance and acid resistance of metal against corrosive gas, etc.
Further, for example, it is possible to prevent adhesion of barnacles to seawater suction port of an electric generation plant, ship bottom, or the like, to facilitate demolding of a resin molded product from a mold, and to make adhered substance hard to remain to a blade. Alternatively, it becomes possible to use the plating film 10 in prevention of residue in a nozzle that discharges viscous liquid such as an adhesive, in control of fluid resistance in a pipe, in reduction of resistance of an injection needle, etc.
Furthermore, it is possible to maintain lubricity under ultimate condition of outer space, or the like. In the outer space, machinery is exposed to severe conditions such as non-gravity, high vacuum, high temperature, low temperature, and radiation exposure. Therefore, it is desirable to maintain the operation function in the outer space. At present, high-boiling grease is used for the purpose. However, since optical equipment such as various kinds of sensors and a spectroscope are vulnerable to contamination by evaporant, a non-volatile lubricating material is strongly demanded. The plating film according to the present technology may fulfill such demand.

3. Examples

Hereinafter, Examples of the disclosure are specifically described. However, the technology is not limited to these Examples.

Example 1

For example, 100 g of tin chloride (the metallic salt of the plating metal 11) was dissolved in 300 ml of 4-butyrolactone (the plating solvent) to prepare the plating solution R. The plating solution was placed in Hull cell tester (trademark; Yamamoto-MS Co., Ltd.) that was made of glass and was attached with the anode electrode 32 and the cathode electrode 33 as illustrated in FIG. 3A, and the plating solution was maintained at temperature of 70° C. while being stirred with a rotor. Here, the plating metal and the metal to be plated were used as is as the anode electrode and the cathode electrode, respectively. In this state, the AC voltage that had the AC waveform illustrated in FIG. 4 and whose parameters were set to those in voltage condition 1 was applied to perform the plating operation. As a result, the plating film 10 (Example 1-1) was obtained. Besides, the plating films 10 in respective Examples 1-2, 1-3, and 1-4 were obtained with use of similar procedure. Conditions in the respective Examples were as follows.

Example 1-1

[Solvent] 4-butyrolactone (molecular weight 86)
[Plating Metal] tin
[Functional Compound] none
[Voltage Condition 1] Vp=15 [volt]

- Vb=−4 [volt]
- Tp=50 [msec]
- Tw=4 [msec]

[Cathode] copper plate (100 m in width×67 mm in length)
[Anode] tin plate (64 mm in width×64 mm in length)

Example 1-2

[Solvent] ethylene glycol (molecular weight 62)
[Plating Metal] tin
[Functional Compound] none
[Voltage Condition 1]
[Cathode] copper plate (100 mm in width×67 mm in length)
[Anode] tin plate (64 mm in width×64 mm in length)

Example 1-3

[Solvent] polyethylene glycol (average molecular weight 200)
[Plating Metal] tin
[Functional Compound] none
[Voltage Condition 1]
[Cathode] copper plate (100 mm in width×67 mm in length)
[Anode] tin plate (64 mm in width×64 mm in length)

Example 1-4

[Solvent] polyethylene glycol 400 (average molecular weight 400)
[Plating Metal] tin
[Functional Compound] none
[Voltage Condition 1]
[Cathode] copper plate (100 mm in width×67 mm in length)
[Anode] tin plate (64 mm in width×64 mm in length)
In the Example 1-1, a contact angle of water in a glossy part was measured by a sessile drop method. As a result, the contact angle was 66° in a tangent method. In addition, conductivities of the plating solutions in the respective Examples were 2.40 (mS, Example 1-1), 1.13 (mS, Example 1-2), 0.17 (mS, Example 1-3), and 0.08 (mS, Example 1-4) at the temperature of 25° C.
The conductivity in the Example 1-1 was higher than that in the Example 1-2, and therefore, lot of whisker occurred. In the Examples 1-2 to 1-4, polymerizable monomers varied in polymerization degree were used as the plating solvent, and the conductivity decreased as the molecular weight increased. When plating was carried out until the plating film 10 had a certain film thickness, it was confirmed that whisker occurrence amount at the edge part of the copper plate on a side where a distance between electrodes was short decreased in proportion to the conductivity. This indicated that the metallic salt (tin chloride) was dissolved in the electrolytic solution (the plating solution R) in a state where the metallic salt was not sufficiently ionized. In other words, it was estimated that this was because when the metallic salt existed as ions, metallic cation was easily precipitated on the anode electrode 32, and therefore, whisker easily grew depending on slight irregularity on the metal plate and difference in activation, whereas when the ionization was insufficient and the metal was precipitated as the metal after ionized on the surface of the electrode, whisker was difficult to grow. An area occupied by a mirror part in the plating film 10 also increased as the molecular weight of the plating solvent increased, and rough surface (nonglossy plating) occurred on the side where the distance between electrodes was short decreased.
As described above, it was possible to increase the thickness of the plating film 10 while maintaining gloss on the surface of the plating film 10 by mixing a monomer and a polymer (oligomer or polymer) of polymerizable monomer as the plating solvent or increasing the average molecular weight of the solvent of the electrolytic solution with use of only the polymer.

Example 2

3.0 g of pentadecafluorooctanoic acid and 0.3 g of glycerin were dehydrated and condensed. As a result, 3.1 g of fluoroalkyl ester serving as the functional compound 12 was obtained as an oily matter. This was dissolved in 50 ml of propylene carbonate (plating solvent B) (plating solution B). 100 g of tin chloride (the metallic salt of the plating metal 11) was dissolved in 250 ml of ethylene glycol (plating solvent A) (plating solution A). After that, the plating solution A and the plating solution B were mixed to prepare the plating solution R. Subsequently, the plating solution R was placed in Hull cell tester (trademark; Yamamoto-MS Co., Ltd.) that was made of glass and was attached with the anode electrode 32 (the tin plate) and the cathode electrode 33 (the copper plate) similarly to the above-described Example 1, and the plating solution was maintained at temperature of 70° C. while being stirred with a rotor. In this state, the AC voltage that had the AC waveform illustrated in FIG. 4 and whose parameters were set to those in voltage condition 1 was applied to perform plating. As a result, the plating film 10 (Example 2-1) was obtained.
Also, plating with use of a commercially-available fluoroalkyl compound was carried out. 100 g of tin chloride was dissolved in 300 ml of ethylene glycol. 16 g of Surflon (manufactured by AGC Seimi Chemical Co., Ltd.) was mixed thereto and sufficiently stirred and dissolved to prepare the plating solution. The plating solution was placed in Hull cell tester (Yamamoto-MS Co., Ltd.) that was made of glass and was attached with the anode electrode 32 (the tin plate) and the cathode electrode 33 (the copper plate), and the plating solution was maintained at temperature of 70° C. while being sufficiently stirred with a rotor. In this state, the AC voltage that had the AC waveform illustrated in FIG. 4 and whose parameters were set to those in voltage condition 1 was applied to perform plating. As a result, the plating film 10 (Example 2-2) was obtained. The conditions in the respective Examples were as follows.

Example 2-1

[Solvent] ethylene glycol/propylene carbonate=5/1
[Plating Metal] tin
[Functional Compound] fluoroalkyl ester
[Voltage Condition 1]
[Cathode] copper plate (100 mm in width×67 mm in length)
[Anode] tin plate (64 mm in width×64 mm in length)

Example 2-2

[Solvent] ethylene glycol (molecular weight 62)
[Plating Metal] tin
[Functional Compound] Surflon S-242 (manufactured by AGC Seimi Chemical Co., Ltd.)
[Voltage Condition 1]
[Cathode] copper plate (100 mm in width×67 mm in length)
[Anode] tin plate (64 mm in width×64 mm in length)
In the Examples 2-1 and 2-2, the contact angles of water in the glossy part of the plating film 10 were measured by the sessile drop method. As a result, the contact angles were 134° and 102° in the tangent method. In addition, the contact angle of water was measured after the plated surface was scraped by about 2 μm with use of a polishing sheet (3M lapping film sheet), and it was confirmed that water repellency was maintained.

Example 3

The plated samples of the above-described Examples 1-1 and 2-1 were immersed in pure water and left at room temperature. Note that the plating film 10 before immersion had a silvery luster smooth surface in both of the Examples 1-1 and 2-1. Two weeks later, the plated samples of the Examples 1-1 and 2-1 were taken out, and water was then sufficiently removed with air blow. The plating film 10 in the Example 1-1 was changed in color to mat gray and a part thereof was peeled off and detached, whereas the plating film 10 in the Example 2-1 maintained silver gloss. The surface roughness of the plating films 10 were measured by a surface roughness meter (manufactured by KLA-Tencor Corporation, P-15 surface profiler). As a result, the surface roughness Ra were 0.49 μm (the Example 1-1) and 3.41 pm (the Example 2-1).

Example 4

Next, the plating films 10 of Examples 4-1 and 4-2 were obtained through the procedure similar to that in each of the above-described Examples 1 and 2. Conditions in the respective Examples were as follows.

Example 4-1

[Solvent] 4-butyrolactone/ethylene glycol=3/1
[Plating Metal] nickel
[Functional Compound] none
[Voltage Condition 2] Vp=0 [volt]

- Vb=10 [volt]
- Tp=50 [msec]
- Tw=25 [msec]

[Cathode] copper plate (100 mm in width×67 mm in length)
[Anode] nickel plate (64 mm in width×64 mm in length)

Example 4-2

[Solvent] 4-butyrolactone/ethylene glycol=3/1
[Plating Metal] nickel
[Functional Compound] Surflon S-611 (manufactured by AGC Seimi Chemical Co., Ltd.)
[Voltage Condition 2]
[Cathode] copper plate (100 mm in width×67 mm in length)
[Anode] nickel plate (64 mm in width×64 mm in length)
In the Examples 4-1 and 4-2, the contact angles of water in the glossy part of the plating film 10 were measured by the sessile drop method. As a result, the contact angles were 73° and 104° in the tangent method. In addition, as Example 4-3, the contact angles of water were measured after the respective plated surfaces were scraped by about 2 μm with use of a polishing sheet (3M lapping film sheet). As a result, it was confirmed that water repellency was maintained.

Example 5

The plated samples of the above-described Examples 4-1 and 4-1 were immersed in pure water and left at room temperature. Note that the plating film 10 before immersion had a silvery luster smooth surface in both of the Examples 4-1 and 4-2. Two weeks later, the plated samples of the Examples 4-1 and 4-2 were taken out, and water was then sufficiently removed with air blow. The plating film 10 in the Example 4-1 was changed in color to mat gray, whereas the plating film 10 in the Example 4-2 maintained silver gloss. Average values of the surface roughness of the respective plating films 10 were measured by a surface roughness meter (manufactured by KLA-Tencor Corporation, P-15 surface profiler). As a result, the average values of the surface roughness Ra were 5.25 μm (the Example 4-1) and 0.52 μm (the Example 4-2).
Hereinbefore, although the disclosure has been described with referring to the embodiment and the Examples, the disclosure is not limited to the above-described embodiment and the like, and various modifications may be made. For example, the metal source attached on the anode electrode does not necessarily have a plate shape, and for example, may be a bead or a sphere housed in a porous container, a basket, etc. Alternatively, the metal source may not be attached to the anode electrode, and plating may be carried out only with use of electrolyte dissolved in the plating solution. The shape of an object to be plated attached on the cathode electrode is also arbitrary. In addition, to homogenize the film formation, operation of rotating or oscillating the object to be plated, etc. may be added. Hull cell tester is used as the plating bath in this case; however, the shape of the plating bath is also arbitrary, and the plating operation may be desirably carried out while keeping an appropriate distance between the anode electrode and the cathode electrode in order to obtain the highest homogeneity. The method of stirring the plating solution is not limited to a rotor, and various methods such as a rotor blade, pump circulation, and bubbling.
Further, according to the technology, alloy plating may be carried out by using two or more kinds of plating metals. In this case, a plurality of metallic salts is used as the metallic salt to be dissolved in the plating solution. Accordingly, two or more kinds of metals may be used as the metal source attached to the anode electrode, and an alloy formed of two or more kinds of metals may be also used. Alternatively, the metal source may not be attached to the anode electrode, and the plating may be carried out only with use of electrolyte dissolved in the plating solution. Note that, in the case of the alloy plating, it is necessary to pay attention to the fact that the ratio of metals to be precipitated may be varied depending on the waveform of the application voltage.
Note that the technology may be configured as follows.
(1) A plating film including a metal and a compound having functionality, the metal and the compound being homogenously dispersed and joined.
(2) The plating film according to (1), wherein the metal and the compound having the functionality are joined at a molecular level.
(3) The plating film according to (1) or (2), wherein the compound having the functionality includes one or more of water repellency, oil repellency, and surface lubricity.
(4) The plating film according to any one of (1) to (3), wherein the metal and the compound having the functionality are coprecipitated by electrolytic plating.
(5) A method of manufacturing a plating film, the method using a solution in which a metal is dissolved and a compound having functionality is dissolved or colloidally dispersed.
(6) The method of manufacturing the plating film according to (5), including:
preparing a plating solution by dissolving a metallic salt of the metal in a solvent and then adding the compound having the functionality in the solvent to dissolve or colloidally disperse the compound; and
immersing an object to be plated in the plating solution to make a cathode, and applying a voltage between the cathode and an anode.
(7) The method of manufacturing the plating film according to (6), wherein
the object to be plated is immersed in the plating solution to make the cathode, and the voltage is applied between the cathode and the anode to coprecipitate the metal and the compound having the functionality, thereby forming a plating film added with a function of the compound having the functionality.
(8) The method of manufacturing the plating film according to (6) or (7), wherein

- the solvent in which the metallic salt is dissolved is an organic solvent or mixed solution of the organic solvent and water.

(9) The method of manufacturing the plating film according to (8), wherein
the organic solvent contains a non-polymerizable compound, or one of a monomer and a polymer of a polymerizable compound.
(10) The method of manufacturing the plating film according to (8) or (9), wherein
the organic solvent contains one or more kinds of polymerizable compounds, and each of the polymerizable compounds includes two or more kinds of compounds having respective polymerization degrees different from one another.
(11) The method of manufacturing the plating film according to any one of (7) to (10), wherein
the plating film is formed by electrolytic plating.
(12) The method of manufacturing the plating film according to (11), wherein
the electrolytic plating is carried out by application of one of a DC voltage and an AC voltage.
(13) A plated product including
a plating film on a surface, wherein
the plating film includes a metal and a compound having functionality, the metal and the compound being homogenously dispersed and joined.
This application is based upon and claims the benefit of priority of the Japanese Patent Application No. 2013-56936 filed in the Japan Patent Office on Mar. 19, 2013, the entire contents of this application are incorporated herein by reference.
It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.

Claims

1. A plating film including a metal and a compound having functionality, the metal and the compound being homogenously dispersed and joined.

2. The plating film according to claim 1, wherein the metal and the compound having the functionality are joined at a molecular level.

3. The plating film according to claim 1, wherein the compound having the functionality includes one or more of water repellency, oil repellency, and surface lubricity.

4. The plating film according to claim 1, wherein the metal and the compound having the functionality are coprecipitated by electrolytic plating.

5. A method of manufacturing a plating film, the method using a solution in which a metal is dissolved and a compound having functionality is dissolved or colloidally dispersed.

6. The method of manufacturing the plating film according to claim 5, comprising:

preparing a plating solution by dissolving a metallic salt of the metal in a solvent and then adding the compound having the functionality in the solvent to dissolve or colloidally disperse the compound; and

immersing an object to be plated in the plating solution to make a cathode, and applying a voltage between the cathode and an anode.

7. The method of manufacturing the plating film according to claim 6, wherein

the object to be plated is immersed in the plating solution to make the cathode, and the voltage is applied between the cathode and the anode to coprecipitate the metal and the compound having the functionality, thereby forming a plating film added with a function of the compound having the functionality.

8. The method of manufacturing the plating film according to claim 6, wherein

the solvent in which the metallic salt is dissolved is an organic solvent or mixed solution of the organic solvent and water.

9. The method of manufacturing the plating film according to claim 8, wherein

the organic solvent contains a non-polymerizable compound, or one of a monomer and a polymer of a polymerizable compound.

10. The method of manufacturing the plating film according to claim 8, wherein

the organic solvent contains one or more kinds of polymerizable compounds, and each of the polymerizable compounds includes two or more kinds of compounds having respective polymerization degrees different from one another.

11. The method of manufacturing the plating film according to claim 7, wherein

the plating film is formed by electrolytic plating.

12. The method of manufacturing the plating film according to claim 11, wherein

the electrolytic plating is carried out by application of one of a DC voltage and an AC voltage.

13. A plated product comprising

a plating film on a surface, wherein

the plating film includes a metal and a compound having functionality, the metal and the compound being homogenously dispersed and joined.