JP7128009B2 - Ag-plated material, its manufacturing method, and contact or terminal part - Google Patents

Description

The present invention relates to an Ag-plated material, a method for producing the same, and contact or terminal components using the Ag-plated material, particularly contacts and terminals of connectors, switches, relays, etc. used in electrical wiring for vehicles and households. The present invention relates to an Ag-plated material used as a material for parts, a method for manufacturing the same, and contact or terminal parts.

Electrical devices are provided with electronic members having sliding portions such as contacts and terminal parts. In the sliding portion, a conductor material such as Cu or a Cu alloy that constitutes the sliding portion is used as a base material that is relatively inexpensive and has excellent corrosion resistance, mechanical properties, and the like. A plated material obtained by plating the base material with Sn, Au, Ag, or the like is used according to the required properties such as electrical properties and solderability.

A Sn-plated material obtained by plating a base material such as Cu or a Cu alloy with Sn is inexpensive, but has poor corrosion resistance in a high-temperature environment. In addition, Au-plated materials obtained by plating these substrates with Au have excellent corrosion resistance and high reliability, but the cost is high. On the other hand, Ag-plated materials obtained by applying Ag-plating to these base materials are superior in corrosion resistance to Sn-plated materials and less expensive than Au-plated materials.

On the other hand, contacts and terminal parts used in connectors, switches, and the like are required to have resistance to wear associated with inserting/removing connectors and sliding of switches.
However, since Ag-plated materials are soft and wear easily, when they are used as contact points or terminal parts, the Ag-plated material adheres to them when they are inserted, removed, or slid. There is a problem that the surface is scraped and the friction coefficient increases, resulting in an increase in the insertion force. In particular, when an Ag-plated material is used as a pluggable connector material such as a wire harness, the Ag-plated layer may be scraped off by repeated plugging and unplugging, exposing the underlying plating layer and the substrate. Then, when the underlying plating layer and the base material are exposed, the contact resistance increases, which may lead to heat generation and ignition.
In order to avoid such problems, a method of increasing the film thickness of the Ag plating layer, a method of applying a lubricant to the surface of the Ag plating material, and the like are known.

For example, Patent Literature 1 describes an electrical contact material in which an organic film of an organic compound containing a fatty acid is provided on an Ag plating layer and is said to be excellent in corrosion resistance and sliding resistance.
Further, in Patent Document 2, an Ag plating layer is applied to the surface of the sliding portion of the conductor, and a grease-like lubricant composed of graphite and perfluoropolyether is applied to a film thickness of 10 μm or more to improve lubricity. A sliding current-carrying body, which is said to be excellent, is described.
Furthermore, in Patent Document 3, an Ag plating layer is formed on the surface of the sliding contact portion, and a graphite or molybdenum disulfide layer is fixed on the Ag plating layer, and abrasion resistance, sliding resistance, and heat resistance are provided. A preferred moveable contact device is described.

JP 2008-273189 A JP-A-2002-343168 JP-A-9-306326

If the thickness of the Ag plating layer is increased, the raw material cost increases.
For example, the above-mentioned Patent Literature 1 proposes to provide an organic film on the Ag plating layer and to reduce the amount of wear by its lubricating action. However, according to the studies of the present inventors, the Ag plating according to Patent Document 1 generates organic deposits on the Ag plating as wear progresses due to sliding or the like, and there is concern that the contact resistance at the electrical contact will increase. It was something. In addition, as the wear advances, Cu or a Cu alloy of the base material (base metal), for example, is exposed and oxidized to increase the contact resistance, thereby reducing the reliability.
On the other hand, Patent Documents 2 and 3 propose adding graphite to the lubricant provided on the Ag plating layer in order to suppress the increase in contact resistance in the electrical contact. However, according to the studies of the present inventors, the lubricants (greases) described in Patent Documents 2 and 3 use a halogen compound such as perfluoropolyether as a binder. For this reason, the Ag plating layers according to Patent Documents 2 and 3 have a relatively high coefficient of friction on the surface of the plating layer, and there is a concern that the contact may be worn. However, if the film thickness of the lubricant is increased, there is a concern that the cost will increase and the contact resistance will also increase.

The present invention has been made under the above circumstances, and the problem to be solved is to provide an Ag plating with improved abrasion resistance, which is used for electronic members such as terminals (connectors) and contacts (switches). The object is to provide a material, a method for manufacturing the same, and a contact or terminal component.

Here, the present inventors continued their research, immersed a base material having an Ag plating layer on the surface layer in a water emulsion containing carbon particles, fatty acids and water, The inventors have come up with a configuration in which an inclusion film is provided.
Then, the present inventors have found that this structure can produce an Ag-plated product that has high wear resistance and can avoid an increase in contact resistance, thereby completing the present invention. And, by using the Ag-plated material provided with the fatty acid-containing film for the sliding parts of electronic members such as contacts (switches) and terminals (connectors), the wear resistance of the sliding parts is improved, The inventors have found that the increase in contact resistance can be avoided, and completed the present invention.

That is, the first invention for solving the above problems is
A base material having an Ag plating layer formed on its surface is immersed in a water emulsion containing carbon particles, fatty acids and water to form a fatty acid-containing film containing carbon particles on the surface of the Ag plating layer. , a method for producing an Ag-plated material.
The second invention is
The method for producing an Ag-plated material according to the first invention, wherein the carbon particles are subjected to oxidation treatment by wet treatment.
The third invention is
The method for producing an Ag-plated material according to the first or second invention, characterized in that scale-like graphite particles are used as the carbon particles.
The fourth invention is
The method for producing an Ag-plated material according to any one of the first to third inventions, wherein the amount of the carbon particles in the water emulsion is 1 g/L or more and 10 g/L or less.
The fifth invention is
The method for producing an Ag-plated product according to any one of the first to fourth inventions, wherein stearic acid is used as the fatty acid.
The sixth invention is
The method for producing an Ag-plated product according to any one of the first to fifth inventions, wherein Cu or a Cu alloy is used as the base material.
The seventh invention is
The method for producing an Ag-plated product according to any one of the first to sixth inventions, wherein the Ag-plated layer is formed after forming a base layer made of Cu or Ni on the base material. be.
The eighth invention is
The method for producing an Ag-plated product according to any one of the first to seventh inventions, wherein the Ag-plated layer is formed by electroplating.
The ninth invention is
An Ag-plated material, comprising: a surface layer made of Ag plating is formed on a substrate; and a fatty acid-containing film containing carbon particles is formed on the surface layer.
A tenth invention is
The Ag-plated product according to the ninth invention, wherein the carbon particles are scale-like graphite particles.
The eleventh invention is
The Ag-plated product according to the ninth or tenth invention, wherein the fatty acid is stearic acid.
A twelfth invention is
The Ag-plated product according to any one of the ninth to eleventh inventions, wherein the base material is made of Cu or a Cu alloy.
A thirteenth invention is
The Ag-plated material according to any one of the ninth to twelfth inventions, characterized in that an underlying layer made of Cu or Ni is formed between the base material and the Ag-plated layer.
A fourteenth invention is
A contact or terminal component, characterized by using the Ag-plated material according to any one of the ninth to thirteenth inventions.

According to the present invention, the Ag-plated material used for electronic members such as contacts (switches) and terminals (connectors) having a fatty acid-containing film containing carbon particles on the Ag-plated layer has high wear resistance Ag-plated material and A manufacturing method thereof can be provided.

FIG. 10 is an appearance photograph taken with a digital microscope of the Ag-plated surface according to Example 3 after a reciprocating sliding test; FIG. FIG. 10 is an appearance photograph taken with a digital microscope of the Ag-plated surface according to Comparative Example 3 after a reciprocating sliding test; FIG.

The method for producing an Ag-plated product according to the present invention includes immersing a substrate having an Ag-plated layer on its surface in a water emulsion containing carbon particles, fatty acids, and water, and including carbon particles on the surface of the Ag-plated layer. It forms a fatty acid-containing film.
That is, the Ag-plated material according to the present invention has a surface layer made of Ag plating formed on a substrate, and a fatty acid-containing film containing carbon particles is provided on the surface of this surface layer.
With this configuration, it was possible to obtain an Ag-plated material having both excellent wear resistance and avoidance of an increase in contact resistance.

Hereinafter, the present invention will be described in terms of (1) carbon particles, (2) fatty acids, (3) a method for preparing a water emulsion, (4) base materials and Ag plating used for Ag-plated products, and (5) fatty acid content on Ag-plated surfaces. The method of forming the film and (6) evaluation will be described in this order.

(1) Carbon Particles In the present invention, flaky or earthy graphite (synonymous with graphite) particles having an average particle size of 1 to 10 μm can be preferably used. More preferred.
This is because when the average particle size of the graphite particles is larger than 1 μm, a sufficient effect of improving the wear resistance can be obtained. On the other hand, if the average particle size of the graphite particles is 10 μm or less, the surface layer of the Ag plating layer is not attacked, and there is no risk of deterioration in wear resistance or increase in contact resistance. From this point of view, it is more preferable that the graphite particles have an average particle size of 3 to 8 μm. Further, when the graphite particles are scaly, they are easily cleaved and the coefficient of friction can be reduced, which is preferable.

In the present invention, the average particle size of the carbon particles is determined by dispersing 0.5 g of the carbon particles in 50 g of a 0.2% by weight sodium hexametaphosphate solution, further dispersing the particles with ultrasonic waves, and then using a laser light scattering particle size distribution measuring device. was used to measure the particle size of the carbon particles in the volume-based distribution, and the particle size of 50% of the cumulative distribution was taken as the average particle size.

In addition, when the present inventors added carbon particles to a water-fatty acid emulsion to be described later, the carbon particles aggregated and were not well dispersed (emulsified or suspended) in the water-fatty acid emulsion. It has been found.
The present inventors believe that this phenomenon is not due to poor dispersion due to the adsorption of organic substances having strong lipophilicity on the surface of the carbon particles and the aggregation of the carbon particles in the water-fatty acid emulsion. I inferred.
Therefore, based on this inference, the present inventors conducted various studies, and as a result, fatty acid hydrocarbons such as alkanes and alkenes, and aromatic hydrocarbons such as alkylbenzene are contained in carbon particles as organic substances having strong lipophilicity. I found it included. Furthermore, the present inventors have found that the dispersibility of the carbon particles is improved by adding the carbon particles to the water-fatty acid emulsion after removing the lipophilic organic substances adsorbed on the surface of the carbon particles by oxidation treatment. got

As the oxidation treatment method for the carbon particles described above, it is preferable to use a wet oxidation treatment from the viewpoint of mass production, and the wet oxidation treatment can uniformly oxidize the carbon particles having a large surface area.

As a method of wet oxidation treatment, after suspending carbon particles in water containing a conductive salt, electrolysis is performed by inserting a platinum electrode or the like as a cathode or anode into the water, or carbon particles are placed in water. A method of adding an appropriate amount of oxidizing agent after suspending can be used. However, considering the productivity, it is preferable to use the latter method, and the amount of carbon particles added to water is preferably 1 to 20% by weight.
When the latter method is applied, oxidizing agents such as nitric acid, hydrogen peroxide, potassium permanganate, potassium persulfate, and sodium perchlorate can be used, and potassium persulfate is more preferable. .
It is believed that the lipophilic organic matter adhering to the carbon particles is oxidized by the added oxidizing agent into a water-soluble form, and is appropriately removed from the surface of the carbon particles. After the wet oxidation treatment, the carbon particles are filtered and then washed with water to further enhance the effect of removing lipophilic organic substances from the surfaces of the carbon particles.

Specifically, the carbon particles described above were put into pure water, and an oxidizing agent was added to the mixed liquid stirred by a stirrer to perform oxidation treatment by wet oxidation. Thereafter, the mixed solution was filtered with filter paper and washed with water to obtain oxidized carbon particles.

By the oxidation treatment described above, lipophilic organic substances such as aliphatic hydrocarbons and aromatic hydrocarbons can be removed from the surface of the carbon particles. Here, when the gas generated by heating the carbon particles after the above oxidation treatment to 300° C. was analyzed, it was found that the gas contained strongly oleophilic aliphatic hydrocarbons such as alkanes and alkenes, and hydrophilic compounds such as alkylbenzene. It was also found that almost no oily aromatic hydrocarbons were contained.

(2) Fatty Acid Fatty acids used in the water emulsion according to the present invention include saturated fatty acids such as stearic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, behenic acid, cerotic acid and melissic acid, and myristoleic acid. , palmitoleic acid, oleic acid, nervonic acid, linoleic acid, α-linolenic acid and the like can be used, but it is preferred to use stearic acid.

(3) Method for preparing a water emulsion The water emulsion of the present invention is prepared by adding and stirring the above-described carbon particles and fatty acid (with a surfactant if necessary) according to the present invention to pure water, and mixing the carbon particles and fatty acid. It can be obtained by dispersing (emulsifying or suspending) in pure water.

The (added) amount of carbon particles in the water emulsion is preferably 1 to 10 g/L.
This is because if the amount of carbon particles is 1 g/L or more, a sufficient amount of carbon particles can be formed on the surface layer when a fatty acid-containing film containing carbon particles is formed on the surface layer made of Ag plating. , the wear resistance of the Ag-plated material is ensured. On the other hand, if the amount of carbon particles is 10 g/L or less, the fatty acid-containing film containing carbon particles does not contain too many carbon particles, and the contact resistance does not increase (exceeds 1 mΩ).

The fatty acid concentration in the water emulsion is preferably 10-50 g/L. This is because a fatty acid-containing film having a sufficient thickness (5 nm or more, preferably 10 nm or more) is formed when the concentration of the fatty acid is 10 g/L or more. On the other hand, if the fatty acid concentration is 50 g/L or less, the fatty acid-containing film will not become too thick (for example, greater than 500 nm), and an increase in contact resistance can be avoided.

Further, when dispersing each of the above components in pure water to form a water emulsion, it is preferable to use a stirrer and stir for, for example, 10 minutes or more.

(4) Base material and Ag plating used for Ag-plated material In the Ag-plated material, it is preferable to appropriately select Cu or a Cu alloy having excellent electrical conductivity and mechanical strength as the base material according to the application.
Then, before forming the Ag plating layer on the base material, the base material is preferably pretreated by alkali degreasing, electrolytic degreasing, or the like, and the surface of the base material is acid-activated by pickling.
In addition, before forming the Ag plating layer on the base material, in order to improve the adhesion between the base material and the Ag plating layer, and to prevent the diffusion of the components of the base material into the Ag plating layer, a Cu plating layer Alternatively, it is preferable to form an underlying layer made of a Ni plating layer.

As a specific example, first, a base layer consisting of a Cu plating layer or a Ni plating layer is formed on the surface of the base material, and then an intermediate layer is formed by Ag strike plating using a cyan bath or the like. It is preferable to form a surface Ag plating layer by Ag plating.
These platings may be electroplating or electroless plating, but electroplating is preferable from the viewpoint of production efficiency.

The surface layer composed of the Ag plating layer may contain a trace amount of additives such as Se and Sb that are added to the Ag plating solution when forming the Ag plating.
The thickness of the Ag-plated surface layer is preferably 0.1-20 μm, more preferably 0.3-10 μm, and most preferably 0.5-8 μm.
This is because if the thickness of the surface layer is not too large, the amount of Ag used is not too large, and productivity is ensured, so that manufacturing costs and raw material costs do not increase. On the other hand, if the thickness of the surface layer is not too thin, there is no risk of deterioration in wear resistance or increase in contact resistance due to diffusion of base material (or base) components.

The thickness of the underlying layer made of Cu or Ni is preferably 0.05 to 3 μm, more preferably 0.1 to 2 μm.
This is because the bending workability of the Ag-plated material is ensured if the thickness of the base layer made of Cu or Ni is 3 μm or less. On the other hand, if the thickness of the underlayer is 0.05 μm or more, the adhesiveness between the substrate and the surface layer is ensured, and the effect of preventing diffusion of the components of the substrate is also ensured.

(5) Method for forming a fatty acid-containing film on an Ag-plated product As a method for forming a fatty acid-containing film on the Ag-plated product according to the present invention, the above-mentioned Ag-plated product is immersed in the water emulsion of the present invention, and then dried. It is preferable to remove moisture by drying to form a fatty acid-containing film containing carbon particles. Furthermore, it is preferable to stir the water emulsion during the immersion.

Specifically, it is preferable to immerse the Ag-plated material provided with the Ag-plated layer for 5 seconds or longer while stirring the water emulsion using a stirrer.
After the immersion, the Ag-plated material provided with the Ag-plated layer immersed in the water emulsion is dried, for example, by hot air of about 30 to 60° C. to remove moisture on the surface. After that, it is preferable to place the Ag-plated material under a high temperature of about 70 to 130° C. to remove moisture on the surface.

Regarding the adhesion state of the carbon particles on the Ag plating layer, when the surface of the Ag plating layer was observed with a laser microscope, the carbon particles adhered at an area ratio of about 10 to 80% of the total area of the observation area. It is preferable to allow This is because if the area ratio is not too small, the wear resistance is sufficiently improved, and if it is not too large, there is no risk of an increase in contact resistance.

In the Ag-plated product after drying, the thickness of the fatty acid-containing film described above is preferably 5 to 500 nm.
This is because if the thickness of the fatty acid-containing film is 5 nm or more, friction is reduced and wear resistance is ensured. On the other hand, if the thickness of the fatty acid-containing film is 500 nm or less, it is preferable because an increase in contact resistance can be avoided.

(6) Evaluation Two test pieces are cut out from the Ag-plated material according to the present invention, one test piece is a flat test piece (test piece as a male terminal), and the other test piece is indented ( R = 1.5 mm hemispherical stamping) to obtain an indented test piece (test piece as a female terminal).
After the sliding test in which the indented test piece is pressed against the surface of the flat test piece with a load of 3 N, the sliding speed is 100 mm / min, and the sliding distance is 5 mm, 300 reciprocations and 500 reciprocations are performed. It was evaluated whether or not it was exposed to
As a result, it was found that the base material of the Ag-plated material according to the present invention was not exposed on the surface, and the wear resistance of the Ag-plated material was high.
In other words, the Ag-plated material according to the present invention has a sufficiently low contact resistance for practical use, and the base material is not exposed on the surface even after sliding. Degeneration can be avoided.
From the above, it can be said that the Ag-plated material according to the present invention is suitable for electronic members such as contacts and terminal parts.

Hereinafter, the present invention will be described more specifically with reference to examples.
In Examples 1 to 3, (1) a step of oxidizing the surface of carbon particles, (2) a step of preparing a water emulsion, (3) a step of pretreatment of a base material, (4) a Ni Plating process, (5) Ag strike plating process on the material to be plated, (6) Ag plating process on the material to be plated, (7) Ag plating material immersion process in water emulsion, (8) Sliding wear test and Each step of evaluation was performed. On the other hand, in Comparative Example 1, (7) the step of immersing the Ag-plated material in a water emulsion was not performed. In Comparative Examples 2 and 3, a water emulsion containing no carbon particles was used as the water emulsion.

[Example 1]
(1) Step of Oxidizing the Surface of Carbon Particles As carbon particles, scaly graphite particles (Carbon SN-5 manufactured by SEC Co., Ltd.) having an average particle size of 5 μm were prepared.

Next, 180 g of graphite particles were put into 3 L of pure water, and the mixture was heated to 50° C. while being stirred. Then, 1.2 L of a 0.1 mol potassium persulfate aqueous solution was gradually added dropwise as an oxidizing agent, and the mixture was further stirred for 2 hours to carry out oxidation treatment by wet oxidation. Thereafter, filtration was performed with filter paper, and the filtered graphite particles were washed with water to obtain oxidation-treated graphite particles according to Example 1.
The average particle size of the graphite particles was determined by dispersing 0.5 g of graphite particles in 50 g of a 0.2% by weight sodium hexametaphosphate solution, dispersing the particles with ultrasonic waves, and measuring the particle size using a laser light scattering particle size distribution analyzer. The particle size of the volume-based distribution was measured, and the particle size of 50% of the cumulative distribution was taken as the average particle size.

(2) Water emulsion preparation process 2 g of oxidized graphite particles were added to 1 L of water emulsion bath containing 31 g of stearic acid (fatty acid). Then, the water emulsion bath was dispersed by stirring at 500 rpm with a stirrer to prepare a water emulsion containing oxidized graphite particles, and a water emulsion (lubricant) according to Example 1 was obtained.
Table 2 shows the amount of graphite particles in the water emulsion according to Example 1.

(3) Pretreatment process for substrate A pure copper metal substrate of 70 mm x 50 mm x 0.6 mm was prepared as a substrate (material to be plated).
The material to be plated and the SUS plate were placed in an alkaline degreasing solution, and electrolytic degreasing was performed for 30 seconds by applying a voltage of 5 V using the material to be plated as a cathode and the SUS plate as an anode.
After the electrolytic degreasing, the material to be plated was washed with water and then pickled in a 3% sulfuric acid aqueous solution for 15 seconds to obtain a material to be plated that had been subjected to electrolytic degreasing and pickling.

(4) Ni-plating process on the material to be plated A Ni-plating aqueous solution containing nickel sulfamate tetrahydrate with a concentration of 504 g/L, nickel chloride with a concentration of 25 g/L, and boric acid with a concentration of 35 g/L was prepared. did.
In the Ni plating aqueous solution, the material to be plated which had been electrolytically degreased and pickled was used as a cathode, and the SK nickel electrode plate was used as an anode. Then, while stirring the Ni plating aqueous solution at 500 rpm using a stirrer, Ni plating is performed on the material to be plated at a current density of 5 A / dm ² and a solution temperature of 55 ° C., and the Ni plating with a film thickness of 1 μm is applied. A plated material was obtained.

(5) Ag Strike Plating Process for Plating Material An Ag strike plating aqueous solution containing potassium silver cyanide with a concentration of 3 g/L and potassium cyanide with a concentration of 90 g/L was prepared.
The Ni-plated material to be plated was used as a cathode, and the titanium electrode plate coated with platinum was used as an anode. Then, while stirring the Ag strike plating aqueous solution at 500 rpm using a stirrer, Ag strike plating is performed on the Ni-plated material to be plated at a current density of 2 A / dm ² and a liquid temperature of 18 ° C. for 10 seconds. A material to be plated with strike plating was obtained.

(6) Ag plating process on the material to be plated Containing potassium silver cyanide with a concentration of 175 g / L, potassium cyanide with a concentration of 95 g / L, and potassium selenocyanate with a concentration of 100 mg / L (containing 55 mg / L of selenium), An aqueous Ag plating solution was prepared.
Using the material to be plated subjected to the Ag strike plating described above as a cathode and the silver electrode plate as an anode, the material was immersed in the Ag plating aqueous solution. Then, while stirring the Ag plating aqueous solution at 500 rpm using a stirrer, Ag plating is performed on the material to be plated that has been subjected to the Ag strike plating at a current density of 5 A / dm ² and a liquid temperature of 18 ° C., Ag with a film thickness of 5 μm A plated Ag-plated material was obtained.

(7) Immersion step of Ag-plated material in water emulsion The Ag-plated material was immersed for 120 seconds in a bath in which the water emulsion (lubricant) of Example 1 was stirred at 500 rpm with a stirrer. Table 2 shows the post-treatment time.
After the immersion, the Ag-plated material was pulled out of the bath, and hot air was applied to the surface of the Ag-plated material using a dryer to completely remove moisture on the surface. After that, the Ag-plated material is dried by heating at 110 ° C. for 45 seconds in the atmosphere with a heat dryer (Steel forced convection dryer manufactured by AS ONE Co., Ltd.), and graphite particles and stearic acid are included on the surface of the Ag-plated material. An Ag-plated material sample according to Example 1 was obtained by forming a fatty acid-containing film.

(8) Sliding wear test and evaluation Cut out two test pieces from the Ag-plated material sample according to Example 1 described above, and use one test piece as a flat test piece (test piece as a male terminal), and the other The test piece was indented (r=1.5 mm hemispherical punching) to obtain an indented test piece (test piece as a female terminal).
A flat test piece is fixed to the stage of a precision sliding tester (CRS-G2050-DWA type manufactured by Yamazaki Seiki Laboratory Co., Ltd.), which is a sliding test device, and the indented test piece is brought into contact with the flat test piece. let me Then, while pressing the indented test piece against the surface of the flat test piece with a load of 3 N, the stage on which the flat test piece was fixed was slid horizontally at a sliding speed of 100 mm / min and a sliding distance of 5 mm, 300 and 500 reciprocations. A sliding test was performed. Table 1 shows the sliding test conditions.

After the sliding test, the surface of the flat test piece of the Ag-plated material sample according to Example 1 was observed at a magnification of (×400) using a digital microscope (manufactured by Keyence Corporation: VHX-1000). Then, the presence or absence of exposure of the copper substrate was observed during the observation, and the wear resistance was evaluated.
Then, when there was no exposure of the copper base, the wear resistance was evaluated as ◯, and when there was exposure of the copper base, the wear resistance was evaluated as x. was 0. The evaluation results are shown in Table 2.

On the other hand, during the sliding wear test described above, the contact resistance of the Ag-plated material sample according to Example 1 was measured. The contact resistance of the Ag-plated material sample according to Example 1 was defined as the maximum value of the contact resistance during the sliding period. As a result, the contact resistance after 300 reciprocations and 500 reciprocations was 0.91 mΩ (300 reciprocations) and 0.89 mΩ (500 reciprocations), which were good. The measurement results are shown in Table 2.
In addition, regarding the state of adhesion of carbon particles on the Ag plating layer, the surface of the Ag plating layer was observed with a laser microscope. The rate was 70%.

[Example 2]
Ag plating according to Example 2 was performed in the same manner as in Example 1 except that the immersion time of the Ag plating material in the above "(7) Ag plating material immersion step in water emulsion" was set to 10 seconds. A wood sample was obtained.
Then, the Ag-plated material sample according to Example 2 was subjected to the sliding test in the same manner as in Example 1, and the contact resistance was measured after the sliding wear test.

As a result, even after 300 reciprocations and 500 reciprocations, the surface of the substrate was not exposed and the abrasion resistance was ◯. The contact resistance was 0.66 mΩ (300 reciprocations) and 0.66 mΩ (500 reciprocations), which were good. Further, as a result of observing the surface of the Ag plating layer in the same manner as in Example 1, the area ratio of the area where carbon particles were observed to adhere to the entire area of the observed area was 20%. Table 2 shows the production conditions and evaluation/measurement results.

In addition, when the surface of the Ag plating film was qualitatively analyzed using a pyrolysis gas chromatograph mass spectrometer, fatty acids including stearic acid were found to be present on the surface of the Ag plating film.
In addition, as a measurement of the film thickness of the fatty acid-containing film of the present invention, the surface of the Ag plating film (analysis area with a diameter of 100 μm, a portion where no graphite particles are present) was sputtered by irradiating with argon ions, and Auger electron spectroscopic analysis was performed. Depth profile analysis by Auger electron spectroscopy (AES) was performed using an apparatus (JAMP-7800 manufactured by JEOL Ltd.). Then, it was confirmed that a fatty acid-containing film adhered to the surface of the Ag plating film. The thickness of the fatty acid-containing film was found to be 12 nm by converting the sputtering time described above into the sputtering rate (5 nm/min) of a standard sample of SiO ₂ .

[Example 3]
The amount of graphite particles added to the water emulsion containing oxidized graphite particles in the above-described “(1) step of oxidizing the surface of carbon particles” is set to 5 g, and the Ag-plated material is added to the water emulsion in the post-treatment step. An Ag-plated material sample according to Example 3 was obtained by performing the same operation as in Example 1, except that the immersion time was set to 10 seconds.

Then, the Ag-plated material sample according to Example 3 was subjected to the sliding test in the same manner as in Example 1, and the contact resistance was measured after the sliding wear test.
As a result, the surface of the substrate was not exposed even after 300 reciprocations and 500 reciprocations, and the abrasion resistance was ◯. The contact resistance was 0.58 mΩ (300 reciprocations) and 0.73 mΩ (500 reciprocations), which were good. Further, as a result of observing the surface of the Ag plating layer in the same manner as in Example 1, the area ratio of the area where carbon particles were observed to adhere to the entire area of the observed area was 50%. Table 2 shows the production conditions and evaluation/measurement results.

Moreover, when the thickness of the fatty acid-containing film according to Example 3 was measured in the same manner as in Example 2, it was 12 nm.
FIG. 1 shows a photograph of the appearance of the plated surface according to Example 3 after 500 times of reciprocating sliding at (×400) magnification. From FIG. 1, it was confirmed that the base material (copper) was not exposed on the Ag-plated surface after 500 reciprocating slides.

[Comparative Example 1]
An Ag-plated material sample according to Comparative Example 1 was obtained in the same manner as in Example 1, except that the above-described "(7) step of immersing Ag-plated material in water emulsion" was not performed.
Then, the Ag-plated material sample according to Comparative Example 1 was subjected to the sliding test in the same manner as in Example 1, and the contact resistance was measured after the sliding wear test.
As a result, both after 300 reciprocations and 500 reciprocations, the surface of the substrate (Cu) was exposed and the wear resistance was x. The contact resistance was 0.35 mΩ (300 reciprocations) and 0.40 mΩ (500 reciprocations), which were good. Table 2 shows the production conditions and evaluation/measurement results.

[Comparative Example 2]
The same operation as in Example 1, except that the Ag-plated material was immersed for 120 seconds in the emulsion containing no oxidized graphite particles in the above-described "(7) step of immersing the Ag-plated material in the water emulsion". was performed to obtain an Ag-plated material sample according to Comparative Example 2.
Then, the Ag-plated material sample according to Comparative Example 2 was subjected to the sliding test in the same manner as in Example 1, and the contact resistance was measured after the sliding wear test.
As a result, after 300 reciprocations, there was no exposure of the surface of the substrate and the wear resistance was ◯, but after 500 reciprocations, exposure of the surface of the substrate was observed and the wear resistance was x. The contact resistance was high at 1.37 mΩ (300 round trips) and 1.98 mΩ (500 round trips). Table 2 shows the production conditions and evaluation/measurement results.

[Comparative Example 3]
The same operation as in Example 1, except that the Ag-plated material was immersed for 10 seconds in the emulsion containing no oxidized graphite particles in the above-described "(7) step of immersing the Ag-plated material in the water emulsion". was performed to obtain an Ag-plated material sample according to Comparative Example 3.
Then, the Ag-plated material sample according to Comparative Example 3 was subjected to the sliding test in the same manner as in Example 1, and the contact resistance was measured after the sliding wear test.
As a result, exposure of the substrate surface was observed after 300 reciprocations and after 500 reciprocations, and the abrasion resistance was evaluated as x. The contact resistance was high at 1.17 mΩ (300 reciprocations) and 1.50 mΩ (500 reciprocations). Table 2 shows the production conditions and evaluation/measurement results.

Further, when the thickness of the fatty acid-containing film was measured in the same manner as in Example 2, it was 12 nm.
FIG. 2 shows an appearance photograph of the plated surface according to Comparative Example 3 at (×400) magnification after 500 times of reciprocating sliding. From FIG. 2, on the plated surface after 500 times of reciprocating sliding, the plating was completely worn away, and the underlying base material (copper) was exposed.

[summary]
From Examples 1 to 3, Table 2, and FIG. 1, in the Ag-plated material in which a fatty acid-containing film containing carbon particles was formed on the Ag-plated material according to the present invention, after 300 times and 500 times the sliding wear test Also in , there was no exposure of the copper substrate, and the wear resistance was good. In addition, the contact resistance did not increase during the sliding wear test of 300 times and 500 times, which was good.

Claims (10)

A base material having an Ag plating layer formed on the surface layer is immersed in a water emulsion containing scale-like graphite particles that have been subjected to oxidation treatment by a wet treatment , stearic acid , and water, and the surface of the Ag plating layer is 3. A method for producing an Ag-plated material for use in contacts or terminal components, characterized by forming a film having a thickness of 5 nm or more and 500 nm or less , comprising said scale-like graphite particles and stearic acid . 2. The method for producing an Ag-plated product according to claim 1, wherein the amount of said scale-like graphite particles in said water emulsion is 1 g/L or more and 10 g/L or less. 3. The method for producing an Ag-plated material according to claim 1 , wherein Cu or a Cu alloy is used as said base material. The method for producing an Ag-plated product according to any one of claims 1 to 3 , wherein the Ag-plated layer is formed after forming a base layer made of Cu or Ni on the base material. The method for producing an Ag-plated product according to any one of claims 1 to 4, wherein the Ag-plated layer is formed by electroplating. The method for producing an Ag-plated product according to any one of claims 1 to 5, wherein the concentration of stearic acid in the water emulsion is 10 g/L or more and 50 g/L or less. The method for producing an Ag-plated material according to any one of claims 1 to 6, wherein the Ag-plated layer has a thickness of 0.5 µm or more and 8 µm or less. A surface layer made of Ag plating is formed on a base material, and a film made of scale-like graphite particles and stearic acid and having a thickness of 5 nm or more and 500 nm or less is formed on the surface layer. Ag plating material used for terminal parts. 9. The Ag-plated product according to claim 8, wherein said substrate is made of Cu or a Cu alloy. 10. The Ag-plated product according to claim 8 , further comprising a base layer made of Cu or Ni formed between said base material and said Ag-plated layer.

Images