JP7458800B2 - Composite plating material and its manufacturing method - Google Patents

Description

The present invention relates to a composite plating material and a method for manufacturing the same.

Traditionally, conductor materials such as copper and copper alloys have been plated with silver to prevent them from oxidizing due to heating during the sliding process, as materials for sliding contact parts such as switches, connectors, and terminals used in automobiles. A silver-plated material is used.

However, silver plating is soft and easily abraded, and generally has a high coefficient of friction, so there is a problem that the material (base material) is easily exposed due to abrasion due to sliding. To solve this problem, a method has been proposed in which a composite silver plating film in which silver alloy plating film or graphite particles are dispersed in a silver matrix is formed on the conductor material by electroplating to improve wear resistance. ing.

[0034] of Patent Document 1 discloses that 80 g/L of oxidized carbon particles are added to a cyan silver plating solution consisting of 120 g/L potassium silver cyanide and 100 g/L potassium cyanide, and then dispersed and suspended. It is described that a composite plating solution of silver and carbon particles is prepared by adding potassium selenocyanate (KSeCN) as a silver matrix alignment agent after making the solution cloudy.

Using these composite plating solutions, electroplating was carried out at a solution temperature of 25°C and a current density of 1A/ ^dm2 to form a film of silver and carbon particles with a thickness of 5μm on a copper plate with a thickness of 0.3mm as a material. It is described that a composite plating material having a composite plating film formed thereon is produced.

In addition, in order to improve the adhesion of the plating film, before forming the composite plating film, the liquid temperature was 25°C in an Ag strike plating bath with a composition of 3 g/L cyanide silver potassium and 100 g/L potassium cyanide. , it is described that Ag strike plating is performed at a current density of 3 A/dm ² .

In [0011] of Patent Document 2, silver, potassium cyanide, potassium hydroxide, graphite powder, and a dispersion aid for graphite powder in the plating solution are contained in the plating solution, the silver plate is used as an anode, and the bath temperature is 20°C. It is described that plating is formed by stirring at a current density of 1 A/dm ² .

Japanese Patent Application Publication No. 2011-74499 Japanese Patent Application Publication No. 9-7445

The inventors' research has revealed that there is room for improvement in bending workability when forming contact parts such as switches, connectors, and terminals by press working using the plated materials obtained by the methods described in Patent Documents 1 and 2.

Further, the methods described in Patent Documents 1 and 2 use a cyanide bath, which increases the cost for rendering cyanide harmless during wastewater treatment of the plating bath.

An object of the present invention is to provide a composite plated material having excellent wear resistance and excellent bending workability.
An object of the present invention is to provide a method for manufacturing a composite plated material having excellent wear resistance and excellent bending workability while using a non-cyanide bath.

The first aspect of the present invention is
In a composite plating material in which a composite plating film made of a composite material containing carbon particles in a silver layer is formed on a base material,
The carbon content of the composite plating film is 0.2 to 10.0% by mass,
This is a composite plating material in which the ratio of the number of silver particle structures having a ratio of the major axis to the minor axis of 2 or more among the silver particle structures on the surface of the composite plating film is 30% or more.

A second aspect of the present invention is the aspect described in the first aspect, comprising:
The proportion of carbon particles on the surface of the composite plating film is 5 to 85% by area.

A third aspect of the present invention is the aspect described in the first or second aspect,
The thickness of the composite plating film is 0.5 to 25 μm.

A fourth aspect of the present invention is the aspect according to any one of the first to third aspects,
The base material is copper or a copper alloy.

A fifth aspect of the present invention is the aspect according to any one of the first to fourth aspects,
A base plating layer is formed between the base material and the composite plating film.

A sixth aspect of the present invention is the aspect described in the fifth aspect, comprising:
The base plating layer consists of at least one selected from a nickel plating layer and a copper plating layer.

A seventh aspect of the present invention is the aspect according to any one of the first to sixth aspects,
The silver particle structure is an electrodeposited structure.

The eighth aspect of the present invention is
A composite plating material that forms a composite plating film made of a composite material containing carbon particles in the silver layer on a base material by electroplating using a non-cyanide silver plating solution containing carbon particles and iron. A method for producing a composite plating film in which the carbon content of the composite plating film is 0.2 to 10.0% by mass, and the ratio of the major axis to the short axis of the silver particle structure on the surface of the composite plating film is 2 or more. This is a method for manufacturing a composite plating material in which the ratio of the number of particulate structures is 30% or more.

A ninth aspect of the present invention is the aspect described in the eighth aspect, comprising:
The silver plating solution is a sulfonic acid silver plating solution.

A tenth aspect of the present invention is the eighth or ninth aspect of the present invention,
The silver plating solution has an iron concentration of 5 ppm by mass or more.

An eleventh aspect of the present invention is the aspect according to any one of the eighth to tenth aspects,
The current density of the electroplating is 8 A/ ^dm2 or less.

A twelfth aspect of the present invention is the aspect according to any one of the eighth to eleventh aspects,
The carbon particles are carbon particles that have been subjected to an oxidation treatment.

A thirteenth aspect of the present invention is the aspect according to any one of the eighth to twelfth aspects,
After a base plating layer is formed on the substrate, the composite plating film is formed.

A fourteenth aspect of the present invention is the aspect described in the thirteenth aspect,
The base plating layer consists of at least one selected from a nickel plating layer and a copper plating layer.

A fifteenth aspect of the present invention is a contact component using the composite plating material according to any one of the first to seventh aspects as a material.

According to the present invention, a composite plated material having excellent abrasion resistance and excellent bending workability can be provided. According to the present invention, a method for manufacturing a composite plated material having excellent abrasion resistance and excellent bending workability while using a non-cyanide bath can be provided.

FIG. 1(a) is a photograph showing a BSE image (1000x) of the surface of the composite plating film of Example 1, and FIG. 1(b) is a photograph showing a BSE image (5000x) of the surface of the composite plating film of Example 1. FIG. 2(a) is a photograph showing a BSE image (1000 times magnification) of the surface of the composite plating film of Example 2, and FIG. 2(b) is a photograph showing a BSE image (5000 times magnification) of the surface of the composite plating film of Example 2. This is a photograph showing the FIG. 3(a) is a photograph showing a BSE image (1000 times magnification) of the surface of the composite plating film of Example 3, and FIG. 3(b) is a photograph showing a BSE image (5000 times magnification) of the surface of the composite plating film of Example 3. This is a photograph showing the FIG. 4(a) is a photograph showing a BSE image (1000 times magnification) of the surface of the composite plating film of Example 4, and FIG. 4(b) is a photograph showing a BSE image (5000 times magnification) of the surface of the composite plating film of Example 4. This is a photograph showing the FIG. 5(a) is a photograph showing a BSE image (1000x) of the surface of the composite plating film of Example 5, and FIG. 5(b) is a photograph showing a BSE image (5000x) of the surface of the composite plating film of Example 5. FIG. 6(a) is a photograph showing a BSE image (1000 times magnification) of the surface of the composite plating film of Example 6, and FIG. 6(b) is a photograph showing a BSE image (5000 times magnification) of the surface of the composite plating film of Example 6. This is a photograph showing the FIG. 7(a) is a photograph showing a BSE image (1000 times magnification) of the surface of the composite plating film of Comparative Example 2, and FIG. 7(b) is a photograph showing a BSE image (5000 times magnification) of the surface of the composite plating film of Comparative Example 2. This is a photograph showing the FIG. 8 is a photograph showing a BSE image (10,000 times magnification) of a cross section of the composite plating film of Example 2. FIG. 9 is a photograph showing a BSE image (10,000 times) of a cross section of the composite plating film of Comparative Example 2. FIG. 10 is a photograph showing a laser microscope image (100x magnification) including a mountain fold in the middle of the W-shape on the surface of the composite plating film of Example 5 after the bending process test. FIG. 11 is a photograph showing a laser microscope image (100x) including the central folded portion of the W shape on the surface of the composite plating film of Comparative Example 3 after the bending workability test.

This embodiment will be described below. In this specification, "~" refers to a value greater than or equal to a predetermined value and less than or equal to a predetermined value.

(composite plating film)
A composite plating material according to an embodiment of the present invention is a composite plating material in which a composite plating film made of a composite material containing carbon particles in a silver (Ag) layer is formed on a base material. The content is 0.2 to 10.0% by mass, and the number of silver (Ag) particulate structures in which the ratio of the major axis to the minor axis is 2 or more among the silver (Ag) particle structures on the surface of the composite plating film. It is characterized by a ratio of 30% or more.
In the present invention, the term "silver particle structure" refers to a structure in which silver particles appear to be attached to the surface of a composite plating film when observed using a BSE image (backscattered electron image). The major axis and minor axis of each silver particle that appears to be attached to the surface are referred to as the major axis and minor axis of the "silver particle structure."

With this configuration, the composite plated material of the present invention has excellent wear resistance and excellent bending workability.

The carbon content (mass%) in the composite plating film of the present invention was determined by the following method. First, samples cut from the composite plating material (including the base material) were prepared for analysis of silver (Ag) and carbon (C), and one sample was dissolved to determine the Ag content (X mass %) in the sample. ) was determined by inductively coupled plasma emission spectroscopy, and the C content (Y mass %) in the other sample was determined by infrared absorption using a trace carbon/sulfur analyzer, and the C content in the composite plating film was determined by infrared absorption method using a trace carbon/sulfur analyzer. Calculate the amount as Y/(X+Y).

The carbon content in the composite plating film of the composite plating material is 0.2 to 10.0 mass% (the lower limit is preferably 0.3 mass%, more preferably 0.4 mass%; the upper limit is preferably 5.0 mass%, more preferably 3.0 mass%). This is believed to improve the wear resistance of the composite plating material and to provide a low coefficient of friction.

Furthermore, a method for determining the ratio of the number of silver (Ag) particulate structures in which the ratio of the major axis to the minor axis of the silver particulate structure on the surface of the composite plating film of the composite plating material of the present invention is 2 or more will be explained.
First, for all silver particle structures observed in a 5000x BSE image (backscattered electron image) of the surface of the composite plating film using an electron microscope, the long axis (the area of the rectangle circumscribing the outline of the silver particle structure is the smallest) The length of the long side of the rectangle) and the short axis (the length of the short side of the rectangle) are measured, and the ratio of the long axis to the short axis (long axis/breadth axis (aspect ratio)) is calculated.

At that time, silver particle-like structures whose particle diameters (length and breadth) cannot be confirmed at the edges of the BSE image (photograph) are not included. In addition, those that do not have an Ag particulate structure (for example, carbon particles (observed as gray to black coarse particles) in FIG. 1(b) according to Example 1) are not included.

The number of silver particle structures with an aspect ratio of 2 or more is divided by the total number of silver particle structures to calculate the number ratio, and the ratio of the major axis to the short axis (aspect ratio) of the silver particle structure is 2 or more. The ratio of the number of silver particle structures was determined.

In the composite plating material of the present invention, the ratio of the number of silver particle structures having an aspect ratio of 2 or more is 30% or more, more preferably 35% or more, and still more preferably 40% or more. preferable. Although the upper limit is not particularly specified, it may be 90% or less or 80% or less.

It is presumed that the bending workability of the composite plated material is improved by having many silver particle structures with such a large aspect ratio.

The ratio (area ratio) occupied by carbon particles on the surface of the composite plating film is preferably 5 to 85 area % (more preferably 7 to 80 area %, still more preferably 10 to 75 area %).

The thickness of the composite plating film is preferably 0.5 to 25 μm. Within this range, sufficient wear resistance can be ensured and production efficiency is also good. If it is thinner than this, the abrasion resistance may decrease, and if it is thicker, the cost of silver plating will increase. More preferably, the thickness of the composite plating is 1 to 22 μm.

The base material is not limited, but may be copper or a copper alloy.
Moreover, a base plating layer may be formed between the base material and the composite plating film. When forming the base plating layer, it is preferably made of at least one selected from a nickel plating layer and a copper plating layer.

Further, it is preferable that the silver particle structure is an electrodeposited structure.

When observing the surface of the composite plating film according to an embodiment of the present invention, it is recognized that the Ag particulate structures are plate-like (or needle-like). It is presumed that the presence of many such plate-like silver particulate structures with a large aspect ratio improves the bending workability of the composite plating material.

Although there is no limitation on the content of Ag in the composite plating film, it is set to, for example, 90% by mass or more (the remainder excluding carbon is substantially composed of Ag).

(Manufacturing method of composite plating material)
In an embodiment of the method for producing a composite plated material of the present invention, a composite plate containing carbon particles in the silver layer is electroplated using a non-cyanide silver plating solution containing carbon particles and iron. A method for manufacturing a composite plating material in which a composite plating film made of a composite plating film is formed on a base material, the carbon content of the composite plating film being 0.2 to 10.0% by mass, and silver particles on the surface of the composite plating film being It is characterized in that the ratio of the number of silver particle-like structures in which the ratio of the major axis to the minor axis is 2 or more among the silver particle-like structures is 30% or more.

In the present invention, a non-cyanide silver plating solution (bath) is used. "Cyanide" in this specification is a general term for substances containing cyanide ions. In other words, the term "non-cyanide bath" as used herein refers to a bath that does not contain cyanide, or even if it does contain cyanide, the amount is 1 mg/L or less of the entire silver plating solution.

Although there are no limitations on the non-cyanide silver plating solution, for example, a sulfonic acid silver plating solution may be used. The sulfonic acid-based silver plating solution contains silver sulfonate as an Ag ion source, sulfonic acid as a complexing agent, and may also contain additives such as brighteners. The Ag concentration in this silver plating solution is preferably 5 to 150 g/L, more preferably 10 to 120 g/L, and most preferably 20 to 100 g/L. As the silver sulfonate contained in this sulfonic acid silver plating solution, silver methanesulfonate, silver alkanolsulfonate, silver phenolsulfonate, etc. can be used. Other than sulfonic acid silver plating solutions, silver chloride-potassium iodide baths, silver chloride-sodium thiosulfate baths, etc. may be used.

The silver plating solution in this embodiment contains Fe (iron).

There is no limitation on the form of Fe, and it may be an ion (divalent iron, trivalent iron). The Fe concentration in the silver plating solution (mass ppm=mg/L, hereinafter simply referred to as ppm) refers to the total concentration of Fe ions in the silver plating solution. Further, there is no limitation on the timing at which Fe is added to the silver plating solution, and it may be before, during, or after the addition of carbon particles.

The concentration of Fe in the silver plating solution is preferably 5 ppm or more, more preferably 10 ppm or more, and even more preferably 20 ppm or more. It is considered that by incorporating Fe into the silver plating solution, the aspect ratio of the silver particle structure can be increased and the ratio of the number thereof can also be made sufficient. As for the upper limit, there is no limitation as long as a composite plating film can be appropriately produced, but examples include 10,000 ppm (i.e., 1% by mass) or less.

By specifying the concentration of Fe in the Ag plating solution, the ratio of the number of silver particle structures on the surface of the composite plating film, in which the ratio of the major axis to the minor axis is 2 or more, is set to 30% or more (preferably (35% or more, more preferably 40% or more).

The silver plating solution in this embodiment contains carbon particles as well as Fe. The content of carbon particles in the silver plating solution is preferably 10 to 200 g/L, more preferably 20 to 100 g/L. When the amount is 10 g/L or more, the carbon content in the composite plating film can be maintained at a moderate level, and even if the amount exceeds 200 g/L, the carbon content in the composite plating film cannot be increased. .

The electroplating solution temperature when forming a composite plating film on a substrate is preferably 10 to 60°C, more preferably 15 to 55°C.

The carbon content of the composite silver plating film is 0.2 to 10.0% by mass (the lower limit is preferably 0.3% by mass, more preferably 0.4% by mass; the upper limit is preferably 5.0% by mass) %, 4.0% by mass, more preferably 3.0% by mass).

In addition, the carbon particles on the surface of the composite silver plating film may account for 5 to 85% (area ratio) of 5% to 85% (preferably 7% to 80%, more preferably 10% to 75%). It is preferable to form a plating material.

The current density during electroplating is preferably 8 A/dm ² or less, more preferably 7 A/dm ² , and further preferably 0.5 to 7 A/dm ^2. This regulation is believed to facilitate the inclusion of carbon particles in the composite plating film.

It is preferable to oxidize the carbon particles (remove organic substances) before adding the carbon particles.

By incorporating (adding) the carbon particles that have been oxidized into the silver plating solution, we have created a silver plating solution that allows the carbon particles to be well dispersed in the silver plating without using additives such as dispersants. is obtained. By performing electroplating using this silver plating solution, a composite plating film containing carbon particles in the silver plating film is formed on the base material.

The composite plating film may be formed after forming an undercoat plating film on the substrate. There are no limitations on the undercoat plating film, but it may be, for example, an undercoat plating film consisting of at least one selected from a Ni plating film and a Cu plating film. The undercoat Ni plating film and the Cu plating film may be laminated to form multiple layers. A known method may be used as a specific method for forming the Ni plating film and the Cu plating film.

As shown in the Examples section below, in the present embodiment, good test results for wear resistance can be obtained without adding the silver matrix orientation adjuster described in [0022] of Patent Document 1 (i.e., even if selenium is not substantially present in the composite plating film (Se≦10 ppm)), which is one of the technical features of the present invention. The addition of a silver matrix orientation adjuster can be determined according to the type of silver plating solution.

Through the above operations, it becomes possible to manufacture a composite plating film, that is, a composite plating material, which has excellent wear resistance and excellent bending workability while using a non-cyanide bath.

The technical scope of the present invention is not limited to the embodiments described above, but also includes various modifications and improvements within the scope of deriving specific effects obtained by the constituent elements of the invention and their combinations.

For example, in order to improve the adhesion between the base material and the composite plating film, Ag strike plating may be applied to the base material before forming the composite plating film, as in each of the Examples below. . Note that, for this Ag strike plating, the method related to Ag strike plating described in [0034] of Patent Document 1 and [0024] of JP-A No. 2007-16250 may be adopted. Note that, in order to distinguish it from Ag strike plating, the composite plating film described in this embodiment is also referred to as a "main plating film (layer)."

Further, when the composite plating material is used as a material to make contact parts such as switches, connectors, terminals, etc., products with excellent wear resistance and bending workability can be obtained.

Next, the present invention will be specifically explained with reference to Examples. The present invention is not limited to the following examples. Note that contents not described below are the same as those described in this embodiment.

[Example 1]
80 g of scaly graphite particles (natural graphite J-CPB manufactured by Nippon Graphite Industries Co., Ltd.) with a major diameter of 5 μm as carbon particles were added to 1.4 L of pure water, and the mixed solution was heated to 50 ° C. while stirring. Ta. To this mixed solution, 25 mL of an aqueous solution containing 2.6 g of potassium hydroxide was added and stirred for 5 minutes. Next, 0.6 L of an aqueous solution containing 27 g of potassium persulfate as an oxidizing agent was gradually added dropwise to this mixed solution, and the mixture was stirred for 2 hours for oxidation treatment. After that, it was filtered through filter paper and washed with water. I did it. Carbon particles were prepared from which hydrophobic substances such as hydrocarbons attached to the carbon particles were removed by the above oxidation treatment.

In addition, a copper alloy plate (a copper alloy plate material containing 1.0 mass% Ni, 0.9 mass% Sn, 0.05 mass% P, and the balance Cu) (NB109 EH manufactured by Dowa Metaltech Co., Ltd.) having a thickness of 0.2 mm was prepared as a substrate, and the substrate was immersed in a non-cyanide Ag plating bath (sulfonic acid bath) made of Dynesilver GPE-ST manufactured by Daiwa Kasei Co., Ltd., and electroplating (Ag strike plating) was performed with the substrate as the cathode and a titanium platinum mesh electrode plate (platinized titanium mesh material) as the anode at a solution temperature of 25°C, a current density of 5 A/ ^dm2 , and a plating time of 30 seconds.

Next, the carbon particles subjected to the above oxidation treatment were added to a non-cyanide bath consisting of Dyne Silver GPE-PL manufactured by Daiwa Kasei Co., Ltd. to disperse and suspend them, and further iron oxide (Fe ₂ O ₃ ) was added. A silver plating solution containing Fe and carbon particles was prepared by adding 0.04 g/L. This non-cyanide bath is a sulfonic acid silver plating solution (sulfonic acid bath), and contains Ag as silver sulfonate and sulfonic acid as a complexing agent. Note that the Fe concentration in the silver plating solution was 27 ppm, the Ag concentration was 30 g/L, and the carbon particle concentration (carbon particle content) was 80 g/L.

The base material on which Ag strike plating was formed was used as a cathode, and the Ag electrode plate was used as an anode, and was immersed in the above silver plating solution at a solution temperature of 25° C., a stirring speed of 400 rpm, a current density of 3 A/dm ² , and a plating time of 100 seconds. Electroplating (main plating) was performed on the base material, and a composite plating film consisting of a composite material containing carbon particles in a 2 μm thick silver layer was formed on the base material via an Ag strike plating layer. A composite plated material was produced. In addition, 1 L of the silver plating solution was prepared in a beaker with a capacity of 1 L and a diameter of 110 mm, and for stirring, a magnetic stirrer REXIM RS-1DN (cross stirrer, width 38.1 mm, height 15.8 mm) manufactured by As One was used. there was.

The "thickness of the composite plating film" was obtained by measuring a 1.0 mm diameter range at the center of the sample using a fluorescent X-ray film thickness meter (FT9450, manufactured by Hitachi High-Tech Science Co., Ltd.).

The "proportion (%) of the number of silver particulate structures on the surface of the composite plating film having a ratio of the long diameter to the short diameter of 2 or more" was calculated by first observing the surface of the composite silver plating film at 5000 times magnification with a tabletop microscope TM4000 Plus (manufactured by Hitachi High-Technologies Corporation) at an accelerating voltage of 15 kV and measuring the long diameter (the length of the long side of the rectangle that circumscribes the outline of the silver particulate structure) and the short diameter (the length of the short side of the rectangle) observed on the photograph for all Ag particulate structures, and calculating the ratio of the long diameter to the short diameter (long diameter/short diameter (aspect ratio)). In this case, silver particulate structures whose particle diameter cannot be confirmed at the end of the image (photograph) of the BSE image are not included, and those that are not Ag particulate structures (carbon particles, etc.) and Ag particulate structures whose particle diameter cannot be confirmed because they are partially hidden by carbon particles are not included. From the results of the measurements and calculations, the number of silver particulate structures with an aspect ratio of 2 or more was divided by the total number of silver particulate structures to calculate the percentage of the number, and the percentage of the number of silver particulate structures with a ratio of the major axis to the minor axis (aspect ratio) of 2 or more was determined.

The "carbon content (mass%) in the composite plating film" was determined by the following method.
First, samples cut from the composite plating material (including the base material) were prepared for silver (Ag) and carbon (C) analysis, and one sample was dissolved to determine the Ag content (X mass) in the sample. %) using ICP-OES (SPS 5100 manufactured by Hitachi High-Tech Science Co., Ltd.) (plasma spectrometry), and the C content (Y mass %) in the other sample was determined using a trace carbon and sulfur analyzer (Co., Ltd.). It was determined using EMIA-810W (manufactured by Horiba, Ltd.) (infrared absorption method).
Then, the carbon content in the composite plating film was calculated as Y/(X+Y).

The "Fe concentration (ppm)" in the silver plating solution was determined by the above-mentioned ICP-OES (SPS 5100 manufactured by Hitachi High-Tech Science) (plasma spectrometry).
"Ag concentration (g/L)" in the silver plating solution was determined by Ag titration method (Volhard method). At that time, sodium sulfide, concentrated nitric acid, iron alum indicator, and ammonium thiocyanate were used.

The "proportion (area ratio) occupied by carbon particles on the surface of the composite plating film" was obtained by observing the surface of the composite plating film. Specifically, a backscattered electron composition (BSE) image magnified 1000 times at an accelerating voltage of 5 kV from the tabletop microscope TM4000 Plus (manufactured by Hitachi High-Technologies Corporation) mentioned above was converted into GIMP 2.10.10 (image analysis software). The area ratio occupied by carbon was calculated. More specifically, when the highest brightness of all pixels is 255 and the lowest brightness is 0, the gradation is divided so that pixels with a brightness of 127 or less are black and pixels with a brightness over 127 are white. The ratio Y/X of the number of pixels Y in the carbon particle portion to the number It was calculated as the percentage occupied by the area (area ratio (%)).

"Abrasion resistance" was measured using a sliding tester (CRS-G2050-DWA) manufactured by Yamazaki Seiki Institute.

The indentation to be slid on the flat plated composite plated material (evaluation sample) according to Example 1 was performed by pressing the copper alloy plate with an inner diameter of 1.0 mm (so-called indentation processing), and then adding 10% by mass of Ag-Sb alloy plating containing sodium silver cyanide, 30% by mass of sodium cyanide, and 50mL/L of Nissin Bright N (brightening agent, including 6% by mass of diantimony trioxide) (manufactured by Nichijo Seijin Co., Ltd.) An AgSb plating layer containing 2% by mass of Sb, having a Vickers hardness (HV) of 180, and a thickness of 20 μm was formed using a cyan bath as a convex indenter. This indentation was subjected to the above-mentioned sliding test machine, and the composite plated material according to Example 1 was tested 3000 times back and forth (or until the substrate was exposed) at a contact load of 2N, a sliding speed of 3mm/s, and a sliding distance of 10mm. At that point, sliding continued.

The "average friction coefficient" was calculated by measuring the force (F) applied in the horizontal direction when the material had moved half the sliding distance of the outward movement during one reciprocating slide, and calculating the friction coefficient from μ (friction coefficient) = F/N (N is the normal force of 2N). This reciprocating slide was performed 3,000 times (or until the base material was exposed), and the friction coefficient for each slide was calculated and the average value was taken as the average friction coefficient. An average friction coefficient of 0.8 or less was considered to be good. It is more preferable that it is 0.6 or less.

"Average contact resistance (contact reliability)" is the resistance value measured when moving to half of the sliding distance on the outward path during reciprocating sliding, and is the measured value of the number of sliding movements, and the reciprocating sliding is repeated 3000 times ( The average contact resistance was taken as the average contact resistance. If the contact resistance is 3 mΩ or less, the contact reliability is considered to be good. More preferably, it is 1.2 mΩ or less.

"Bending workability" was examined in accordance with JIS H 3130. Specifically, the composite plated material was bent into a W shape. The load was 15 kN, the loading time was 5 seconds, and the width at the time of bending (width in the depth direction of the W-shape) was 10 mm. The bent skin surface was confirmed using a laser microscope (manufactured by Keyence Corporation, VK-X100, magnification: 100x) to ensure that the mountain fold in the middle of the W-shape was included. If the wrinkle width at the mountain fold portion is 30 μm or less, it is considered that the bending workability is good.

The following tables summarize the various contents mentioned above.
Table 1 is a table showing manufacturing conditions of composite plating materials in each example and each comparative example.
Table 2 is a table showing the thickness, composition, etc. of the composite plating materials in each Example and each Comparative Example.
Table 3 is a table showing the characteristics of the composite plating materials in each Example and each Comparative Example.

[Example 2]
A composite plating material was prepared in the same manner as in Example 1, except that the Ag concentration in the Ag plating solution was 20 g/L and the main plating time was 250 seconds. A composite plated material formed on the material was obtained.
The manufacturing conditions and evaluation results are as shown in Tables 1 to 3 (the same applies to the following examples).

[Example 3]
A composite plated material was prepared in the same manner as in Example 1, except that the Ag concentration in the Ag plating solution was 50 g/L, the current density was 7 A/dm ² , and the main plating time was 220 seconds. A composite plating material was obtained in which a 10 μm composite plating film was formed on a base material.

[Example 4]
Before forming the Ag strike plating, a Ni undercoat plating film (layer) was formed. Specifically, Ni undercoat plating was performed in a Ni sulfamate plating bath with a Ni concentration of 78 g/L and a boric acid concentration of 40 g/L at a liquid temperature of 55° C., a current density of 6 A/dm ² , and a plating time of 43 seconds to form a Ni undercoat plating film (layer) with a thickness of 0.5 μm on the copper substrate. Then, Ag strike plating was formed on the Ni undercoat plating layer in the same manner as in Example 1. Thereafter, a composite plating material was produced in the same manner as in Example 1, except that the current density of the main plating was 5 A/dm ² and the plating time was 450 seconds, and a composite plating material in which a composite plating film with a thickness of 15 μm was formed on the substrate via the Ni undercoat plating layer was obtained.

[Example 5]
The same method as in Example 1 except that 0.06 g/L of iron oxide (Fe ₂ O ₃ ) was added to the Ag plating solution to make the Fe concentration 40 ppm, and the plating time of the main plating was 1000 seconds. A composite plated material was produced in which a composite plated film with a thickness of 20 μm was formed on the base material.

[Example 6]
0.03 g/L of iron oxide (Fe ₂ O ₃ ) was added to the Ag plating solution to make the Fe concentration 20 ppm, the carbon particle concentration was 30 g/L, the current density for main plating was 2 A/dm ² , and the plating A composite plated material was produced in the same manner as in Example 1, except that the time was changed to 350 seconds, and a composite plated material was obtained in which a composite plated film with a thickness of 5 μm was formed on the base material.

[Comparative example 1]
Composite was prepared in the same manner as in Example 1, except that 0.006 g/L of iron oxide (Fe ₂ O ₃ ) was added to the Ag plating solution to make the Fe concentration 4 ppm, and the Ag concentration was 15 g/L. A plating material was produced, and a composite plating material in which a 2 μm thick composite plating film was formed on a base material was obtained.

[Comparative example 2]
Except that 0.03 g/L of iron oxide (Fe ₂ O ₃ ) was added to the Ag plating solution to make the Fe concentration 20 ppm, the current density of the main plating was 9 A/dm ² , and the plating time was 85 seconds. A composite plated material was produced in the same manner as in Example 1, and a composite plated material in which a 5 μm thick composite plating film was formed on the base material was obtained.

[Comparative example 3]
The same method as in Example 1 was used except that 0.006 g/L of iron oxide (Fe ₂ O ₃ ) was added to the Ag plating solution to make the Fe concentration 4 ppm, and the Ag plating time was 1000 seconds. A composite plated material was produced, and a composite plated material in which a composite plated film with a thickness of 20 μm was formed on a base material was obtained.

[Comparative example 4]
In Comparative Example 4, the plating bath was a cyan bath (similar to the conventional one). The specific contents are as follows.
In Comparative Example 4, a cyan plating solution for Ag strike consisting of 3 g/L potassium silver cyanide and 100 g/L potassium cyanide was used, and the Ag strike was achieved at a current density of 5 A/dm ² and a plating time of 30 seconds. Plating was performed.
After that, a cyanide-based silver plating solution consisting of 150 g/L potassium cyanide, 90 g/L potassium cyanide, and 3.6 mg/L (ppm) potassium selenocyanate was prepared, and in this silver plating solution, The oxidized carbon particles described in Example 1 were added, and 0.045 g/L of iron oxide (Fe ₂ O ₃ ) was further added. The Fe concentration in the silver plating solution is 30 ppm, the Ag concentration is 80 g/L, and the carbon particle concentration (carbon particle content) is 80 g/L. Main plating was performed using this cyan silver plating solution. In this plating, the current density was 3 A/dm ² and the plating time was 250 seconds. A composite plated material was produced in the same manner as in Example 1 except for the above, and a composite plated material was obtained in which a 5 μm thick composite plating film was formed on the base material.

[Consider]
FIG. 1(a) is a photograph showing a BSE image (1000 times magnification) of the surface of the composite plating film of Example 1, and FIG. 1(b) is a photograph showing a BSE image (5000 times magnification) of the surface of the composite plating film of Example 1. This is a photograph showing the Similarly, FIGS. 2 to 6 are photographs showing BSE images of the surfaces of the composite plating films of Examples 2 to 6.
Similarly, FIG. 7 is a photograph showing a BSE image of the surface of the composite plating film of Comparative Example 2.
FIG. 8 is a photograph showing a BSE image (10,000 times magnification) of a cross section of the composite plating film of Example 2.
FIG. 9 is a photograph showing a BSE image (10,000 times) of a cross section of the composite plating film of Comparative Example 2.
FIG. 10 is a photograph showing a laser microscope image (100x magnification) including a mountain fold in the middle of the W-shape on the surface of the composite plating film of Example 5 after the bending process test.
FIG. 11 is a photograph showing a laser microscope image (100x magnification) including a mountain-folded portion in the middle of the W-shape on the surface of the composite plating film of Comparative Example 3 after the bending workability test.

As shown in FIGS. 1 to 6, in each example, a plate-like (or needle-like) Ag particle structure was observed as the electrodeposition structure of Ag in the composite plating film, and as shown in Table 3, the composite plating film Among the silver particle structures on the surface, the ratio of the number of silver particle structures having a ratio of the major axis to the minor axis (aspect ratio) of 2 or more was 30% or more.

On the other hand, in the composite plating film of the comparative example, as shown in Figure 7 (Comparative Example 2) and Table 3, the proportion of silver particle structures with the aspect ratio of 2 or more was less than 30%.

As shown in Table 3, each Example showed good results in all test items. According to each Example, a composite plating film and a composite plating material having excellent bending workability were obtained. At the same time, it had excellent wear resistance, a low coefficient of friction, and excellent contact reliability.

On the other hand, Comparative Examples 2 to 4 did not have good bending workability.

Regarding bending workability, when comparing FIG. 10 (Example 5) and FIG. 11 (Comparative Example 3), it can be seen that the width of the wrinkles is clearly smaller in Example 5.

In addition, in Comparative Example 1, although the bending workability was relatively good, there were problems in terms of wear resistance and friction coefficient.
On the other hand, Example 1, in which the composite plating film has the same thickness of 2 μm (relatively thin film), has high wear resistance and excellent bending workability. This is because the composite plating film has a structure in which the ratio of the number of silver particle structures with a ratio of the major axis to the minor axis (aspect ratio) of 2 or more among the silver particle structures on the surface of the composite plating film is 30% or more. It is assumed that both of these characteristics will be achieved.

Claims (13)

In a composite plating material in which a composite plating film made of a composite material containing carbon particles in a silver layer is formed on a base material,
The carbon content of the composite plating film is 0.2 to 10.0% by mass,
A composite plating material, wherein the ratio of the number of silver particle structures having a ratio of the major axis to the minor axis of 2 or more among the silver particle structures on the surface of the composite plating film is 30% or more. The composite plating material according to claim 1, wherein the proportion of carbon particles on the surface of the composite plating film is 5 to 85% by area. The composite plating material according to claim 1 or 2, wherein the composite plating film has a thickness of 0.5 to 25 μm. The composite plating material according to any one of claims 1 to 3, wherein the base material is copper or a copper alloy. The composite plating material according to any one of claims 1 to 4, wherein a base plating layer is formed between the base material and the composite plating film. The composite plating material according to claim 5, wherein the base plating layer consists of at least one selected from a nickel plating layer and a copper plating layer. The composite plating material according to any one of claims 1 to 6, wherein the silver particle structure is an electrodeposited structure. A composite plating material that forms a composite plating film made of a composite material containing carbon particles in the silver layer on a base material by electroplating using a non-cyanide silver plating solution containing carbon particles and iron. A method for producing a composite plating film in which the carbon content of the composite plating film is 0.2 to 10.0% by mass, and the ratio of the major axis to the short axis of the silver particle structure on the surface of the composite plating film is 2 or more. The proportion of the number of particulate structures is 30% or more ,
The concentration of iron in the silver plating solution is 5 mass ppm or more,
A method for producing a composite plated material, wherein the current density of the electroplating is 8 A/dm ² or less. The method for producing a composite plated product according to claim 8, wherein the silver plating solution is a sulfonic acid-based silver plating solution. The method for manufacturing a composite plating material according to claim 8 or 9 , wherein the carbon particles are carbon particles subjected to an oxidation treatment. The method for producing a composite plating material according to any one of claims 8 to 10 , wherein the composite plating film is formed after forming a base plating layer on the base material. 12. The method for manufacturing a composite plated material according to claim 11 , wherein the base plating layer consists of at least one selected from a nickel plating layer and a copper plating layer. A contact component using the composite plating material according to any one of claims 1 to 7 as a material.