KR102102583B1 - Electrical contact material and manufacturing method thereof - Google Patents

Abstract

It exhibits excellent wear resistance even when the sliding load is 50 gf or more, for example, 100 gf, and can be used even in harsh environments exposed to the atmosphere for a long time. For example, under H ₂ S gas or SO ₂ gas atmosphere, etc. It is possible to significantly suppress the increase in the contact resistance of the electrical contact material even after the accelerated test in the corrosive environment of the present invention to provide an electrical contact material having high long-term reliability and a method for manufacturing the same.
An electrical contact material having a first noble metal layer (2) on the surface of the conductive base (1) and a second noble metal layer (3) on the surface of the first noble metal layer (2), wherein the first noble metal layer The arithmetic mean roughness (Ra) of the surface = A µm is A <1, the hardness (Hv) of the first noble metal layer is 150 or more, and the thickness of the second noble metal layer exceeds A µm and is 1 µm or less. In addition, the arithmetic mean roughness (Ra) = B㎛ of the surface of the second noble metal layer is B≤0.1, and an electrical contact material.

Description

ELECTRICAL CONTACT MATERIAL AND MANUFACTURING METHOD THEREOF}

The present invention relates to an electrical contact material and a method for manufacturing the same. In particular, it relates to an electrical contact material coated with two noble metal layers made of different noble metals or alloys thereof, and a method for manufacturing the same.

As the electrical contact part, copper or copper alloys having excellent electrical conductivity have been used in the past, but in recent years, contact characteristics have improved, and cases using bare copper or copper alloys are reduced, and copper or copper alloys are used. Various surface-treated materials are used. In particular, as a material that is widely used as an electrical contact material, there is an electrical contact material plated with a noble metal on the electrical contact portion. Among them, precious metals such as gold, silver, palladium, platinum, iridium, rhodium, and ruthenium are used for various electrical contact materials, such as exhibiting stability and excellent electrical conductivity.

As recent electrical contact materials, such as indoor and outdoor sliding contacts for automobiles, reed switches, and switches for camera-mounted contacts, for example, abrasion resistance as an electrical contact material that involves repeated sliding in addition to a normal contact type by pressing. This good electrical contact material is used. Regarding the improvement of abrasion resistance, general-purpose electrical contact materials using hard silver or hard gold are generally used. In addition, plating and clad materials in which microparticles are dispersed are also researched and developed, and electrical contact materials having various surface treatments have been developed in order to improve the sliding characteristics of the electrical contact materials.

For example, in the present inventors, in Patent Document 1, on a conductive substrate, arithmetic mean roughness (Ra) = (A) µm of the surface, and (A) is a 0.05 to 0.5 precious metal or a precious metal as a main component. A first noble metal layer made of an alloy and a second noble metal layer made of an alloy containing a noble metal or a noble metal as a main component having a thickness of 0.001 x (A) µm or more and (A) µm or less are formed on an upper layer of the first noble metal layer. As an electrical contact material, the noble metal forming the first noble metal layer is selected from gold, silver, palladium, and platinum, and the noble metal forming the first noble metal layer or the noble metal which is a main component of the alloy forming the first noble metal layer On the other hand, there is provided an electrical contact material in which the noble metal, which is the main component of the noble metal forming the second noble metal layer or the alloy forming the second noble metal layer, is another element. This electrical contact material is an electrical contact material that is excellent in sliding characteristics and abrasion resistance, has a long service life and can be manufactured at low cost.

Japanese Patent Publication No. 5128153

By the way, when the electrical contact material was prepared and evaluated in the configuration of Patent Document 1, the sliding characteristics at light loads were very excellent, but for example, when the load was 50 gf or more, the sliding characteristics were deteriorated. In addition, it was found that corrosion resistance after the environmental test may be deteriorated. When the test is performed in a high load environment such as hydrogen sulfide (H ₂ S) gas or sulfur dioxide (SO ₂ ) gas, the pinholes of the first precious metal layer and the second precious metal layer of the second precious metal layer are tested. From the pinholes of the base metal layer formed between the first noble metal layer and the conductive gas, it was found that corrosion products derived from the base metal or substrate component may be formed, resulting in poor contact resistance.

The present invention solves the above problems, and exhibits excellent wear resistance even when the sliding load is 50 gf or more, for example, 100 gf, and can be used even in a harsh environment exposed to the atmosphere for a long time. For example, even after an accelerated test in a corrosive environment such as H ₂ S gas or SO ₂ gas atmosphere, it is possible to significantly suppress the increase in the contact resistance of the electrical contact material, thereby providing a highly reliable electrical contact material and a method for manufacturing the same. The task is to do it.

As a result of conducting earnest research and development on the above-mentioned problems, the present inventors determined the surface roughness, layer thickness, layer hardness, and the like of each metal layer of the first precious metal layer and the second precious metal layer formed on the conductive substrate. It has been found that, by appropriate adjustment, it is possible to provide an electrical contact material having excellent wear resistance and sliding characteristics at high loads as well as excellent corrosion resistance. This invention came to what was made based on this knowledge.

That is, according to the present invention, the following means are provided.

(1) An electrical contact material having a first noble metal layer on the surface of a conductive base and a second noble metal layer on the surface of the first noble metal layer,

The arithmetic mean roughness (Ra) = A μm of the surface of the first noble metal layer is A <1, and the hardness (Hv) of the first noble metal layer is 150 or more,

An electrical contact material, wherein the thickness of the second noble metal layer exceeds 1 μm and is 1 μm or less, and the arithmetic mean roughness (Ra) = B μm of the surface of the second noble metal layer is B ≦ 0.1.

(2) The electrical contact material according to (1), wherein the value of A is 0.001 or more and less than 0.500.

(3) The first precious metal layer and the second precious metal layer are gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, tin alloy, palladium, palladium alloy, ruthenium, ruthenium alloy, respectively. The electrical contact material according to (1) or (2), consisting of any of rhodium, rhodium alloy, osmium, osmium alloy, iridium, and iridium alloy.

 (4) The first precious metal layer according to any one of (1) to (3), wherein the first precious metal layer is made of any one of palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, and iridium alloy. Electrical contact material.

 (5) The electricity according to any one of (1) to (4), wherein the second precious metal layer is made of any one of gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, and tin alloy. Contact material.

(6) The electrical contact material according to any one of (1) to (5), having at least one base metal layer between the conductive base and the first noble metal layer.

(7) The electrical contact material according to (6), wherein the base metal layer is made of any one of nickel, nickel alloy, cobalt, and cobalt alloy.

(8) The electrical contact material according to (6) or (7), wherein the underlying metal layer has a thickness of 0.05 to 3.00 µm.

(9) The electrical contact material according to any one of (1) to (8), wherein the conductive base is any one of copper, copper alloy, iron, iron alloy, aluminum, and aluminum alloy.

(10) The electrical contact material according to any one of (1) to (9), wherein the average grain size of the matrix of the conductive base is 5 µm or less.

(11) A method for producing the electrical contact material according to any one of (1) to (10), wherein at least one layer of the first noble metal layer and the second noble metal layer is formed by an electroplating method.

Here, in the present invention, the "noble metal" in the first noble metal layer or the second noble metal layer means a metal that is more precious than the material of the conductive base.

ADVANTAGE OF THE INVENTION According to this invention, the electrical contact material which exhibits abrasion resistance, sliding characteristics, and corrosion resistance under high load, and also has small contact resistance can be provided. Moreover, although the electrical contact material of this invention is plating thicker than what was described in patent document 1, etc., the color tone of the outermost surface is hard to deteriorate, and there is also an effect that the appearance is good in the long term.

The above and other features and advantages of the present invention will become more apparent from the following description with reference to the accompanying drawings as appropriate.

1 is a cross-sectional view schematically showing one embodiment of the present invention.
2 is a cross-sectional view schematically showing another embodiment of the present invention.
3 is a cross-sectional view schematically showing still another embodiment of the present invention.
4 is a partially enlarged cross-sectional view schematically showing a boundary between a first noble metal layer and a second noble metal layer in one embodiment of the present invention.
5 is a partially enlarged cross-sectional view schematically showing a boundary between a first noble metal layer and a second noble metal layer according to another embodiment of the present invention.

The present invention is an electrical contact material having a first noble metal layer on the surface of a conductive base and a second noble metal layer on the surface of the first noble metal layer, the arithmetic mean roughness (Ra) of the surface of the first noble metal layer = (A) ㎛ is (A) <1, and the hardness (Hv) of the first precious metal layer is 150 or more, and the thickness of the second precious metal layer is more than (A) ㎛ and is 1㎛ or less, and It is an electrical contact material having an arithmetic mean roughness (Ra) = (B) μm on the surface of the second noble metal layer (B) ≤ 0.1. Here, the arithmetic mean roughness (Ra) means arithmetic mean roughness (Ra) according to JIS B 0601: 2013.

On the other hand, in the present invention, each of the first noble metal layer and the second noble metal layer is a layer having a different component (that is, the type of the noble metal element). Each of the first noble metal layer and the second noble metal layer may be composed of a single noble metal species or may be made of an alloy containing a noble metal. When made of an alloy containing a noble metal, it is necessary that the elemental species having the largest mass ratio in the layer is a noble metal. If one noble metal layer is made of an alloy containing a plurality of noble metals, it is necessary that the mass ratio of the total of all noble metals in the layer is the largest ratio among the layers. However, even when the proportion of the noble metal alloy is exactly 50%, this is used as the noble metal layer.

Here, when the first noble metal layer and the second noble metal layer are each composed of a single noble metal species, the noble metal element species are required to be different. On the other hand, when the first noble metal layer and the second noble metal layer are each made of an alloy containing a noble metal, it is required that the noble metal element species having the highest mass ratio among the layers constituting the alloy layer are different. do.

The electrical contact material of the present invention will be described with reference to the drawings.

1 is a cross-sectional view schematically showing one embodiment of the present invention. In this embodiment, the first precious metal layer 2 is formed on the surface of the conductive base 1, and the second precious metal layer 3 is further formed on the surface.

2 is a cross-sectional view schematically showing another embodiment of the present invention. Here, on the surface of the conductive base 1, a base metal layer 4 of a coating layer composed of the first noble metal layer 2 and the second noble metal layer 3 is formed.

3 is a cross-sectional view schematically showing still another embodiment of the present invention. Here, a base metal layer 4 is formed on the surface of the conductive base 1, and a coating layer composed of a first noble metal layer 2 and a second noble metal layer 3 is partially formed on the base metal metal layer 4 It is formed, and cost reduction in saving precious metallization is achieved. Meanwhile, with reference to FIG. 3, the base metal layer 4 on the conductive base 1 may be partially formed, for example, a coating layer formed of the first noble metal layer 2 and the second noble metal layer 3 is formed. It may be formed only at a desired location (according to the shape of the coating layer).

1 to 3, for simplicity, the boundary between the first noble metal layer 2 and the second noble metal layer 3 is shown by a straight line, but in reality, as schematically shown in the partially enlarged cross-sectional view of FIG. , The surface of the first noble metal layer 2 on the surface of the conductive base 1 has irregularities such that the arithmetic average roughness (Ra) = (A) µm, and the film thickness of the second noble metal layer 3 is ( A) It is formed to be more than 1 μm and less than 1 μm.

On the other hand, as schematically shown in the partially enlarged cross-sectional view of Fig. 5, for example, when a glossy plating is used for the second precious metal layer 3, the convex portion on the surface side of the first metal layer 2 is thickly convex. It is also possible to form the second precious metal layer 3 in a thin portion. In addition, at this time, for example, after plating, the surface may be lightly wrapped and cut to cover the second precious metal layer 3 only in the concave portion on the surface side of the first precious metal layer 2. Here, the film thickness of the second precious metal layer 3 in the case where the second precious metal layer 3 is formed thickly in the concave portion on the surface side of the first precious metal layer 2 and thinned in the convex portion is defined by an arithmetic mean. do.

Further, as the conductive base to be used, a conductive base made of copper or copper alloy, iron or iron alloy, aluminum or aluminum alloy is preferable, and among them, a conductive base made of copper or copper alloy having good conductivity is preferable.

For example, as an example of a copper alloy, "C14410 (Cu-0.15Sn, manufactured by Furukawa Denki Kogyo Co., Ltd., trade name: EFTEC-3)" which is a CDA (Copper Development 인 Association) published alloy, “C19400 (Cu-Fe alloy) Materials, Cu-2.3Fe-0.03P-0.15Zn), `` C18045 (Cu-0.3Cr-0.25Sn-0.5Zn, manufactured by Furukawa Denki High School Co., Ltd., product name: EFTEC-64T) '', `` C26800 (Cu- 35% Zn) ”,“ C71500 (Cu-30% Ni) ”, and the like. On the other hand, the unit of the number in front of each element is mass%. Since the conductive bases made of these copper alloys have different conductivity and strength, they are selected and used according to the required characteristics. However, from the viewpoint of improving conductivity and heat dissipation, the conductivity is a bar of copper alloy with 5% IACS or higher. It is desirable to do. On the other hand, the term "gas component" when using copper or a copper alloy as a conductive base is intended to indicate copper.

Moreover, as iron or an iron alloy, for example, 42 alloy (Fe-42mass% Ni), stainless steel, or the like is used. It is assumed that the gas component at this time represents iron.

Although the thickness of the conductive base is not particularly limited, it is usually 0.05 to 2.00 mm, and preferably 0.10 to 1.00 mm.

In addition, as the conductive base material of the present invention, by employing those having an average grain size of 5 µm or less of the conductive base material matrix, the plating deposited on the upper layer can be made dense, and as a result, plating having a large number of crystal grains By dispersing the intergranular diffusion by forming, it is possible to significantly delay the time for diffusion of gas components to reach the surface layer. As a result, corrosion of the diffused gas component in the surface layer of the second noble metal layer can be suppressed, and an increase in contact resistance can be suppressed to provide a highly reliable electrical contact material. Moreover, the smaller the average grain size of the conductive base material, the better the bending workability of the conductive base is obtained as a synergistic effect.

The average grain size of the conductive base material is preferably 5 µm or less, but more preferably 3 µm or less, and more preferably 1 µm or less in order to further improve the density of plating. Although there is no restriction | limiting in particular in this lower limit, Usually, it is 0.001 micrometer or more.

In the present invention, examples of metals or alloys forming the first noble metal layer and the second noble metal layer include gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, tin alloy, palladium, And palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, and iridium alloy.

Here, the role of the first noble metal layer is to improve the wear resistance of the second noble metal layer formed on the outermost surface, and to further enhance corrosion resistance. This improves the abrasion resistance by setting the arithmetic average roughness (Ra) = (A) µm of the surface of the first noble metal layer to (A) &lt; 1, and by setting the hardness (Hv) to 150 or more, preferably 200 or more. This is because the abrasion resistance can be further improved.

Moreover, it is preferable that the value of said (A) is 0.001 or more and less than 0.500, and by this, the electrical contact material excellent in corrosion resistance can be obtained.

In particular, in order to easily achieve such improvement in abrasion resistance and corrosion resistance, it is preferable that the first precious metal layer is made of any one of palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, and iridium alloy In addition, it is more preferable that the first noble metal layer is made of any one of palladium, palladium alloy, rhodium, and rhodium alloy because it can further reduce wear resistance and contact resistance. The value of (A) is preferably 0.001 or more and less than 0.5, more preferably 0.005 to 0.1. By setting the value of (A) in this range, the surface of the second noble metal layer formed on the first noble metal layer can be easily smoothed.

On the other hand, the coating thickness of the first noble metal layer is not particularly limited, but in consideration of cost and bending workability, it is preferably 0.001 to 3 µm, and more preferably 0.05 to 1 µm.

The second precious metal layer is made of a precious metal different from the precious metal constituting the first precious metal layer. The second noble metal layer is the outermost coating layer of the electrical contact material of the present invention, and the film thickness of the second noble metal layer exceeds (A) μm, which is the arithmetic average roughness (Ra) of the first noble metal layer surface, and is 1 μm or less. And, the arithmetic average roughness (Ra) = (B) µm of the surface of the second noble metal layer is B ≤ 0.1. This second precious metal layer protects the first precious metal layer and is provided as a layer of a precious metal different from the first precious metal layer having good conductive properties. The surface of the second noble metal layer becomes an initial sliding surface, but the second noble metal layer is buried in the unevenness of (A) µm, which is the arithmetic mean roughness (Ra) of the first noble metal layer surface. It functions as a coating layer having both surface lubricity and wear resistance, which is a function required for resistance characteristics and sliding contacts. The second noble metal layer not only exists to fill the unevenness of the first noble metal layer, but also makes the film more improved in corrosion resistance by making the thickness more than (A) µm to 1 µm or less. In addition, by setting the arithmetic average roughness (Ra) = (B) µm of the surface of the second precious metal layer to (B) ≤ 0.1, it exhibits an effect of suppressing wear due to unevenness and preventing exposure of the first precious metal layer or conductive gas. . In the electrical contact material of the present invention in which the second noble metal layer is formed thicker than the arithmetic mean roughness (Ra) = (A) µm of the first noble metal layer, the amount of noble metal constituting the coating layer is greater than that of Patent Document 1 Therefore, it becomes a high cost, but since it is excellent from a viewpoint of improving corrosion resistance, it can lead to reduction as a total cost in a long-term use environment.

As the material of the second noble metal layer, gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, tin alloy, etc. are suitably used, and gold, gold alloy, etc. Platinum and platinum alloys are preferred. On the other hand, if the electrical contact is a resin molded electrical contact material that is less likely to be exposed to the atmosphere, it is also possible to use silver, silver alloy, indium, indium alloy, tin, and tin alloy as a material for the second precious metal layer. Since these metals and their alloys exhibit excellent solder wetting properties and contact resistance properties, they can be appropriately selected depending on the application and case.

In the electrical contact material (for example, sliding contact material) of the present invention, a base metal layer may or may not be formed between the conductive base and the first noble metal layer. For example, by forming a base metal layer made of any one of nickel, nickel alloy, cobalt, and cobalt alloy, it is preferable because the diffusion barrier and adhesion of the first noble metal layer and the gas component can be improved. In particular, in the present invention in which a metal more precious than a conductive base is formed as the first noble metal layer or the second noble metal layer by plating treatment, it is necessary to form a base metal layer by a base treatment such as flash plating or strike plating before the plating treatment. , It is effective for improving adhesion and preventing substitution. Further, the base metal layer may be a plurality of layers, and can be provided in various configurations by a conventional method, depending on the specifications and uses of the first precious metal layer or the second precious metal layer. The total thickness of the underlying metal layer as a single layer or multiple layers is preferably 0.05 to 3 µm, more preferably 0.5 to 1 µm.

In order to manufacture the electrical contact material of the present invention, various film forming methods such as plating, clad, vapor deposition, sputtering, etc. can be used, but as a method for easily forming a thin film, at least one of the first precious metal layer and the second precious metal layer is particularly useful. It is preferable to form the layer by electroplating, and it is more preferable to form two layers of the first noble metal layer and the second noble metal layer by electroplating. The composition and plating conditions of the electroplating solution can be appropriately determined according to a conventional method. It is also useful to partially form the first noble metal layer, the second noble metal layer, or both of the noble metal coating layers in a stripe shape or a spot shape in order to suppress the amount of required metal.

The coating layer composed of the first noble metal layer and the second noble metal layer in the electrical contact material of the present invention is adaptable, regardless of the kind of appearance of gloss, semi-gloss, or matte. In addition, the effect of the present invention is sufficient even if it is configured, but in order to further improve the effect, a coating layer composed of the first noble metal layer and the second noble metal layer with various commonly used additives, dispersants, and dispersion particles, etc. It is also preferable to use a composite coating contained in one or more of the intermediate layers.

Example

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited to this.

(Example 1)

The conductive substrate shown in Table 1 having a thickness of 0.3 mm and a width of 50 mm was subjected to the pretreatment shown below, and then the base metal layer, the first noble metal layer, and the second noble metal layer shown in Table 1 were electrically conductive in accordance with the electroplating method in this order. It formed on the image, and obtained the electrical contact materials of the invention examples, comparative examples, and conventional examples shown in Table 1.

On the other hand, the coating thickness of each layer was measured by using a fluorescent X-ray film thickness measuring device (SFT-9400, product name, manufactured by SII), and measuring 10 points at arbitrary points with a collimator diameter of 0.5 mm, and calculating the average value. It was made thick.

(Pre-treatment conditions)

[Cathodic electrolytic degreasing]

Degreasing solution: NaOH 60g / ℓ

Degreasing condition: 2.5A / d㎡, temperature 60 ℃, degreasing time 60 seconds

[Pickling]

Pickling liquid: 10% sulfuric acid

Pickling conditions: 30 seconds immersion, room temperature

(Under the metal layer plating conditions)

[Ni plating]

Plating solution: Ni (SO ₃ NH ₂ ) ₂ · 4 H ₂ O 500 g / ℓ, NiCl ₂ 30 g / ℓ, H ₃ BO ₃ 30 g / ℓ

Plating condition: Temperature: 50 ℃

[Co plating]

Plating solution: Co (SO ₃ NH ₂ ) ₂ · 4 H ₂ O 500 g / ℓ, CoCl ₂ 30 g / ℓ, H ₃ BO ₃ 30 g / ℓ

Plating condition: Temperature: 50 ℃

(First precious metal layer plating conditions)

[Pd plating 1 (Pd1)]

Plating solution: Pd (NH ₃ ) ₂ Cl ₂ 45g / ℓ, NH ₄ OH 90ml / ℓ, (NH ₄ ) ₂ SO ₄ 50g / ℓ, Parasigma brightener (trade name, manufactured by Matsuda Sangyo Co., Ltd.) 10ml / ℓ

Plating conditions: Current density: 5A / d㎡, temperature: 60 ℃

[Pd plating 2 (Pd2)] additive free bath: used in Comparative Example 2

Plating solution: Pd (NH ₃ ) ₂ Cl ₂ 45g / ℓ, NH ₄ OH 90ml / ℓ, (NH ₄ ) ₂ SO ₄ 50g / ℓ

Plating conditions: Current density: 3A / d㎡, temperature: 60 ℃

[Rh plating]

Plating amount: RHODEX (brand name, made by Japan Electroplating Engineers Co., Ltd.)

Plating conditions: 1.3A / d㎡, temperature: 50 ℃

[Ru plating]

Plating amount: RUTHENEX100 (brand name, made by Japan Electroplating Engineers Co., Ltd.)

Plating conditions: Current density: 1A / d㎡, temperature: 65 ℃

[Ir plating]

Plating amount: IRIDEX100 (brand name, made by Japan Electroplating Engineers Co., Ltd.)

Plating conditions: 0.2A / d㎡, temperature 85 ℃

(2nd noble metal layer plating condition)

[Au plating]

Plating solution: KAu (CN) ₂ 14.6 g / ℓ, C ₆ H ₈ O ₇ 150 g / ℓ, K ₂ C ₆ H ₄ O ₇ 180 g / ℓ

Plating condition: Temperature: 40 ℃

[Pt plating]

Plating solution: Pt (NO ₂ ) (NH ₃ ) ₂ 10g / ℓ, NaNO ₂ 10g / ℓ, NH ₄ NO ₃ 100g / ℓ, NH ₃ 50ml / ℓ

Plating condition: Temperature: 80 ℃

[Ag plating]

Plating solution: AgCN 50g / ℓ, KCN 100g / ℓ, K ₂ CO ₃ 30g / ℓ

Plating conditions: Current density: 1A / d㎡, temperature: 30 ℃

[Ag-Se alloy plating]

Plating solution: KCN 150g / ℓ, K ₂ CO ₃ 15g / ℓ, KAg [CN] ₂ 75g / ℓ, Na ₂ O ₃ Se · 5H ₂ O 5g / ℓ

Plating conditions: Current density: 2A / d㎡, temperature: 50 ℃

[Sn plating]

Plating solution: SnSO ₄ 80g / ℓ, H ₂ SO ₄ 80g / ℓ

Plating conditions: Current density: 2A / d㎡, temperature: 30 ℃

About each obtained electrical contact material, various characteristics were tested and evaluated on the following test conditions. Table 2 shows the results.

(1A) Average grain size (GS) of conductive gas:

After the cross-sectional sample of the conductive gas was produced at 3 o'clock by FIB, SIM images were observed, particle sizes were measured at 3 locations per field, and the average values thereof are shown in Table 1.

(1B) Thickness measurement: The thickness of the first precious metal layer, the second precious metal layer, and the underlying metal layer was measured by a fluorescent X-ray film thickness meter (trade name: SFT9400) manufactured by SII Nanotechnology. Ten points at arbitrary points were measured using a collimator diameter of 0.5 mm, and the average value was calculated to obtain a coating thickness. Table 1 shows the results.

(1C) Hardness measurement: According to JIS 경도 Z 2244: 2009, the Vickers hardness (Hv) of the first noble metal layer when the measurement load was 0.005N was measured. Again, it is the hardness before coating the second noble metal layer. Table 1 shows the results.

(1D) Arithmetic mean roughness (Ra): The arithmetic mean roughness (Ra) was measured with a surface roughness meter (trade name: Sappcoda SE3500) manufactured by Kosaka Chemical Industries, Ltd. Under the measurement conditions of the probe tip radius of 2 µm and the measurement force of 0.75 N or less, the arithmetic average roughness (Ra) = (A) µm of the first noble metal layer and the arithmetic average roughness (Ra) = (B) µm of the second precious metal layer Was measured. Table 1 shows the results.

(2A) Measurement of kinetic friction coefficient: The coefficient of dynamic friction was measured using a sliding test apparatus (HEIDON: Type: 14FW, manufactured by Shinto Chemical Co., Ltd.). Measurement conditions are as follows.

R = 2.0㎜ steel ball probe, sliding distance 10㎜, sliding speed 100㎜ / min, sliding number of reciprocations 100 times, load 100gf

In the sliding test, the coefficients of dynamic friction after the number of reciprocating sliding times of 1, 50, and 100 were measured and are shown in Table 2.

(2B) Wear depth: About the wear depth after the sliding test was finished, the depth (µm) of the central cross section of the sliding track was measured using a microscope (VH8000, product name, manufactured by Keyence). Table 2 shows the deepest depth as the wear depth.

(2C) Measurement of contact resistance: As an index of corrosion resistance, contact resistance was measured and evaluated as follows. The contact resistance was measured after the outermost layer (the second noble metal layer) was formed by the 4-terminal method. Measurements were taken immediately after the formation of the outermost layer (initial), after the sulfur dioxide test (SO ₂ 10ppm, 40 ° C, 80% RH, 168 hours), and after the hydrogen sulfide test (H ₂ S 3ppm, 40 ° C, 80% RH, 168 hours). It was done at 3 levels. For the evaluation, an Ag probe having a radius of 2 mm was used, the contact resistance at 10 measuring points was measured at 10 kPa conduction and a load of 10 gf was measured, and the average value was calculated to obtain contact resistance. As the evaluation, 10 mΩ or less is “A” as “excellent”, 50 mΩ or less is exceeded 10 mΩ, “B” is “good”, 50 m 50 or more is 100 mΩ or less, is “C” as “possible”, and 100 mΩ or more Table 1 shows "D" as "impossible". The practical level is determined as "C" or "B" or "A".

(2D) Bending workability: For each sample, a V-bending test was performed at a bending work radius of 0.9 mm (R / t = 3) in a direction perpendicular to the rolling streak, and then the top of the specimen was observed under a microscope (VH8000, product name). , Manufactured by Keyence Co., Ltd.). Table 2 shows that the crack was not recognized as "excellent" as "A", slight cracked as "possible" and "B", and relatively large cracked as "impossible" as "C". The practical level is judged as "B" or "A".

(2E) Solderability Wetting: Each test piece obtained by the above plating treatment was immersed in a Sn-3Ag-0.5Cu solder bath using MODEL SAT-5100 (trade name, manufactured by LeSca), with a bath temperature of 245 ° C., an immersion distance of 10 mm, and immersion. Under the conditions of a speed of 25 mm / sec, it was immersed using isopropyl alcohol-25 mass% rosin flux. The time from the immersion of the test specimen until the wet force passed zero (zero cross time) was measured. Table 2 shows the result of the zero cross time (seconds). Solder wettability is evaluated as "excellent" that the zero cross time is less than 1 second, "possible" when it is 1 second or more and less than 3 seconds, and "impossible" when it is more than 3 seconds.

From the above results, each example of the invention exhibits a stable dynamic friction coefficient even under a high sliding load of 100 gf, so that it has good sliding properties, excellent abrasion resistance represented by large wear depth, excellent corrosion resistance represented by contact resistance, bending workability and solderability. It can be seen that the wettability is also good.

On the other hand, each comparative example and the conventional example were inferior to several characteristics.

In Comparative Example 1, since the surface roughness Ra (B) of the second noble metal layer is too high, the contact resistance increases when the number of times of sliding from 50 to 100 times under a high sliding load of 100gf increases, and bending workability It was bad. In Comparative Example 2, since the hardness of the first noble metal layer was too low, the contact resistance increased when the number of times of sliding from 50 to 100 times under a high sliding load of 100gf increased, and the wear resistance was poor. In the conventional example 1, since the coating thickness of the second noble metal layer was thinner than the arithmetic mean roughness (Ra) = (A) μm of the surface of the first noble metal layer, the number of times of sliding was 50 to 100 times under a high sliding load of 100 gf. When the contact resistance increased. Both of these comparative examples and conventional examples did not satisfy the practical level.

Industrial availability

The electrical contact material of the present invention can be suitably used in any type as long as it is a normal contact type electrical contact. In particular, since it has excellent wear resistance and corrosion resistance, it is particularly suitable for use as a material for electrical contacts, such as indoor and outdoor sliding contacts for automobiles, commutator contacts and brush materials for motors, and switches for camera-mounted contacts. You can.

Although the present invention has been described together with its embodiments, we do not intend to limit our invention in any detail of the description, unless specifically specified, and interpret it broadly without contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be.

1: conductive gas
2: First precious metal layer
3: Second precious metal layer
4: base metal layer

Claims (11)

An electrical contact material having a first noble metal layer on the surface of a conductive base and a second noble metal layer on the surface of the first noble metal layer,
The arithmetic mean roughness (Ra) = A μm of the surface of the first noble metal layer is A <1, and the hardness (Hv) of the first noble metal layer is 150 or more,
The thickness of the second noble metal layer exceeds 1 μm and is 1 μm or less, and the arithmetic mean roughness (Ra) = B μm of the surface of the second noble metal layer is B ≦ 0.1,
The first precious metal layer and the second precious metal layer, respectively, gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, tin alloy, palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium Made of any one of alloy, osmium, osmium alloy, iridium, and iridium alloy,
The electrical contact material, characterized in that the average grain size of the matrix of the conductive gas is 5 µm or less. According to claim 1,
An electrical contact material having a value of A of 0.001 or more and less than 0.500. The method of claim 1 or 2,
The first precious metal layer is an electrical contact material made of any one of palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, iridium alloy. The method of claim 1 or 2,
The second precious metal layer is an electrical contact material made of any one of gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, and tin alloy. The method of claim 1 or 2,
An electrical contact material having at least one base metal layer between the conductive base and the first noble metal layer. The method of claim 5,
The base metal layer is an electrical contact material made of any one of nickel, nickel alloy, cobalt, and cobalt alloy. The method of claim 5,
An electrical contact material having a thickness of the underlying metal layer of 0.05 to 3.00 μm. The method of claim 5,
The conductive base material is an electrical contact material made of any one of copper, copper alloy, iron, iron alloy, aluminum, and aluminum alloy. A method for manufacturing the electrical contact material according to claim 1 or 2, wherein at least one layer of the first precious metal layer and the second precious metal layer is formed by an electroplating method. delete delete

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