JPWO2015118627A1 - Electrical contact material and manufacturing method thereof - Google Patents

Abstract

The present invention provides excellent wear resistance even when the sliding load is 50 gf or higher, for example, about 100 gf, and can be used even in a severe environment such as being exposed to the atmosphere for a long time. To provide an electrical contact material having a long-term reliability and a method for manufacturing the electrical contact material that can greatly suppress an increase in contact resistance of the electrical contact material even after an accelerated test in a corrosive environment such as an SO2 gas atmosphere. An electrical contact material having a first noble metal layer 2 on a surface of a conductive substrate 1 and a second noble metal layer 3 on the surface of the first noble metal layer 2, the first noble metal layer. The surface average arithmetic roughness Ra = A μm is A <1, and the hardness Hv of the first noble metal layer is 150 or more, and the thickness of the second noble metal layer is more than A μm and 1 μm or less, And the electrical contact material whose arithmetic mean roughness Ra = Bmicrometer of the surface of this 2nd noble metal layer is B <= 0.1, and its manufacturing method. [Selection] Figure 1

Description

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

  In the past, copper or copper alloys with excellent electrical conductivity have been used for electrical contact parts, but in recent years, contact characteristics have improved, and the number of cases using bare copper or copper alloys has decreased. Various surface-treated materials are used on alloys. In particular, an electrical contact material in which noble metal plating is applied to an electrical contact portion is widely used as an electrical contact material. Among them, noble metals such as gold, silver, palladium, platinum, iridium, rhodium, and ruthenium are used in various electrical contact materials because they exhibit stability and excellent electrical conductivity.

  As a recent electrical contact material, for indoor and outdoor sliding contacts for automobile mounting, reed switches, camera mount contact switches, etc., for example, as an electrical contact material with repeated sliding in addition to the normal contact type by pressing Electrical contact materials with good wear resistance are used. Regarding improvement of wear resistance, electrical contact materials using hard silver or hard gold are generally used for general purposes. Furthermore, research and development has been conducted on plating and cladding materials in which microparticles are dispersed, and electrical contact materials that have been subjected to various surface treatments to improve the sliding characteristics of the electrical contact materials have been developed.

  For example, in the patent document 1, the present inventors mainly used a noble metal or noble metal having a surface arithmetic mean roughness Ra = (A) μm and (A) of 0.05 to 0.5 on a conductive substrate. A first noble metal layer made of an alloy as a component, and a noble metal having a film thickness of 0.001 × (A) μm or more and (A) μm or less on the first noble metal layer or an alloy containing a noble metal as a main component. An electrical contact material provided with a second noble metal layer, wherein the noble metal that forms the first noble metal layer is selected from gold, silver, palladium, and platinum, and the noble metal that forms the first noble metal layer or the first An electrical contact material in which the noble metal that forms the second noble metal layer or the noble metal that is the main component of the alloy that forms the second noble metal layer is an element different from the noble metal that is the main component of the alloy that forms the noble metal layer. providing. This electrical contact material is an electrical contact material that is excellent in sliding characteristics and wear resistance, has a long life, and can be manufactured at low cost.

Japanese Patent No. 5128153

However, when the electrical contact material was created and evaluated with the configuration of Patent Document 1, the sliding characteristics under light load were very excellent, but the sliding characteristics deteriorated when the load was 50 gf or more, for example. It has been found that there is a tendency, and the corrosion resistance after the environmental test may deteriorate. This is because when a test is performed in a high load environment such as hydrogen sulfide (H ₂ S) gas or sulfur dioxide (SO ₂ ) gas, pinholes in the two noble metal layers of the first noble metal layer and the second noble metal layer are used. It can be seen that corrosion resistance derived from the base metal or the component of the base may be formed from the pinhole of the base metal layer provided between the first noble metal layer and the conductive base, resulting in poor contact resistance. It was.

The present invention solves the above-described problems, and exhibits excellent wear resistance even when the sliding load is as high as 50 gf or more, for example, about 100 gf, and is particularly exposed to the atmosphere for a long time. It can be used even in harsh environments, for example, it can greatly suppress the increase in contact resistance of electrical contact materials even after accelerated tests in corrosive environments such as H ₂ S gas and SO ₂ gas atmosphere, and long-term reliability It is an object to provide a high electrical contact material and a method for manufacturing the same.

  As a result of diligent research and development on the above problems, the present inventors have found that each of the first and second noble metal layers provided on the conductive substrate has a surface roughness and a layer thickness. In addition, it has been found that by appropriately adjusting the hardness of the layer and the like, it is possible to provide an electrical contact material that is not only excellent in wear resistance and sliding characteristics under high load but also excellent in corrosion resistance. The present invention has been made based on this finding.

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 substrate and a second noble metal layer on the surface of the first noble metal layer,
The arithmetic average 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 is more than A μm and not more than 1 μm, and the arithmetic average 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 noble metal layer and the second noble 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. , Rhodium, rhodium alloy, osmium, osmium alloy, iridium, an iridium alloy, the electrical contact material according to (1) or (2).
(4) Any one of (1) to (3), wherein the first noble metal layer is made of any one of palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, and iridium alloy. The electrical contact material according to Item.
(5) Any one of (1) to (4), wherein the second noble metal layer is made of any one of gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, and tin alloy. The electrical contact material according to Item.
(6) The electrical contact material according to any one of (1) to (5), wherein the electrical contact material has 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 nickel, nickel alloy, cobalt, or cobalt alloy.
(8) The electrical contact material according to (6) or (7), wherein the base 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 substrate is made of 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 an average crystal grain size of a parent phase of the conductive substrate is 5 μm or less.
(11) The method for producing an electrical contact material according to any one of (1) to (10), wherein at least one of the first noble metal layer and the second noble metal layer is provided by electroplating.
Here, in the present invention, the “noble metal” in the first noble metal layer and the second noble metal layer means a metal noble than the material of the conductive substrate.

  ADVANTAGE OF THE INVENTION According to this invention, while showing the abrasion resistance in a high load, sliding characteristics, and corrosion resistance, furthermore, an electrical contact material with small contact resistance can be provided. Moreover, although the electrical contact material of the present invention is thicker than that described in, for example, Patent Document 1, the color tone of the outermost surface is hardly deteriorated, and there is 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 where appropriate to the accompanying drawings.

It is sectional drawing which showed one embodiment of this invention typically. It is sectional drawing which showed another embodiment of this invention typically. It is sectional drawing which showed further another embodiment of this invention typically. It is a partial expanded sectional view which shows typically the boundary of the 1st noble metal layer and 2nd noble metal layer of one embodiment of this invention. It is a partial expanded sectional view which shows typically the boundary of the 1st noble metal layer and 2nd noble metal layer of another embodiment of this invention.

  The present invention is an electrical contact material having a first noble metal layer on the surface of a conductive substrate and a second noble metal layer on the surface of the first noble metal layer, the arithmetic of the surface of the first noble metal layer Average roughness Ra = (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 1 μm (A) μm. It is an electrical contact material which is the following, and the arithmetic mean roughness Ra = (B) μm of the surface of the second noble metal layer is (B) ≦ 0.1. Here, the arithmetic average roughness Ra means the arithmetic average roughness Ra according to JIS B 0601: 2013.

  In the present invention, each of the first noble metal layer and the second noble metal layer is a layer having different components (that is, types of noble metal elements). Each of the first noble metal layer and the second noble metal layer may be composed of a single noble metal species or an alloy containing a noble metal. In the case of an alloy containing a noble metal, the element species having the largest mass ratio in the layer needs to be a noble metal. If one noble metal layer is made of an alloy containing a plurality of noble metals, the total mass ratio of all the noble metals in the layer needs to be the largest ratio in the layer. However, even when the ratio of the precious metal alloy is just 50%, this is used as the precious 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 need to be different from each other. On the other hand, when the first noble metal layer and the second noble metal layer are each composed of an alloy containing a noble metal, the noble metal element species having the largest mass ratio in the layer constituting the alloy layer are mutually It needs to be different.

The electrical contact material of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view schematically showing one embodiment of the present invention. In this embodiment, the first noble metal layer 2 is provided on the surface of the conductive substrate 1, and the second noble metal layer 3 is further provided on the surface.
FIG. 2 is a sectional view schematically showing another embodiment of the present invention. Here, on the surface of the conductive substrate 1, a base metal layer 4 of a covering layer composed of the first noble metal layer 2 and the second noble metal layer 3 is provided.
FIG. 3 is a cross-sectional view schematically showing still another embodiment of the present invention. Here, a base metal layer 4 is provided on the surface of the conductive substrate 1, and a coating layer composed of the first noble metal layer 2 and the second noble metal layer 3 is partially provided on the base metal layer 4. Yes, cost reduction in saving precious metals can be achieved. In relation to FIG. 3, the base metal layer 4 on the conductive substrate 1 may be partially provided, for example, a place where a covering layer comprising the first noble metal layer 2 and the second noble metal layer 3 is provided. Only (in accordance with the shape of the coating layer).

In FIG. 1 to FIG. 3, the boundary between the first noble metal layer 2 and the second noble metal layer 3 is indicated by a straight line, but actually, it is schematically shown in the partially enlarged sectional view of FIG. 4. Furthermore, the surface of the first noble metal layer 2 on the surface of the conductive substrate 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 with a thickness exceeding 1 μm and not exceeding 1 μm.
As schematically shown in the partial enlarged cross-sectional view of FIG. 5, for example, when bright plating is used for the second noble metal layer 3, the first noble metal layer 2 is thicker in the concave portion on the surface side and thinner in the convex portion. It is also possible to provide two noble metal layers 3. At this time, for example, the surface may be lightly lapped and scraped after plating, and the second noble metal layer 3 may be covered only on the concave portion on the surface side of the first noble metal layer 2. Here, the film thickness of the second noble metal layer 3 when the second noble metal layer 3 is thick in the concave portion on the surface side of the first noble metal layer 2 and thin in the convex portion is defined by an arithmetic average.

Further, as the conductive substrate used, a conductive substrate made of copper or copper alloy, iron or iron alloy, aluminum or aluminum alloy is preferable, and a conductive substrate made of copper or copper alloy having good conductivity is particularly preferable.
For example, as an example of a copper alloy, “C14410 (Cu-0.15Sn, manufactured by Furukawa Electric Co., Ltd., trade name: EFTEC-3)” which is a CDA (Copper Development Association) listed alloy, “C19400 (Cu-Fe series) Alloy material, Cu-2.3Fe-0.03P-0.15Zn "", "C18045 (Cu-0.3Cr-0.25Sn-0.5Zn, manufactured by Furukawa Electric Co., Ltd., trade name: EFTEC-64T ) "," C26800 (Cu-35% Zn) "," C71500 (Cu-30% Ni) ", and the like. In addition, the unit of the number before each element is mass%. Since these copper alloy conductive substrate bases have different electrical conductivity and strength, they are appropriately selected according to required characteristics. From the viewpoint of improving the electrical conductivity and heat dissipation, the electrical conductivity is 5% IACS. It is preferable to use the above copper alloy strip. The “substrate component” in the case of using copper or a copper alloy as the conductive substrate indicates copper.
Further, as the iron or iron alloy, for example, 42 alloy (Fe-42 mass% Ni), stainless steel, or the like is used. In this case, the base component indicates iron.
Although there is no restriction | limiting in particular in the thickness of an electroconductive base | substrate, Usually, it is 0.05-2.00 mm, Preferably, it is 0.10-1.00 mm.

Furthermore, as the conductive substrate in the present invention, by adopting a conductive substrate matrix (matrix) having an average crystal grain size of 5 μm or less, the plating deposited on the upper layer can be densely deposited. As a result, a plating having a large number of crystal grains can be formed to disperse the grain boundary diffusion, and the time for the diffusion of the base component to reach the surface layer can be greatly delayed. As a result, corrosion of the diffused base component in the surface layer of the second noble metal layer can be suppressed, and an increase in contact resistance can be suppressed and a highly reliable electrical contact material can be provided. Further, as the average crystal grain size of the conductive base material is smaller, the bending workability of the conductive base is more excellent as a synergistic effect.
The average crystal grain size of the conductive base material is preferably 5 μm or less, but is preferably 3 μm or less, and more preferably 1 μm or less in order to further improve the denseness 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 a metal or an alloy thereof 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, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, iridium alloy, and the like can be given.
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 improve the corrosion resistance. This is because the arithmetic average roughness Ra = (A) μm of the surface of the first noble metal layer is set to (A) <1, so that the wear resistance is improved and the hardness Hv is 150 or more, preferably 200 or more. This is because the wear resistance can be further improved.
Moreover, it is preferable that the value of (A) is 0.001 or more and less than 0.500, whereby an electrical contact material having more excellent corrosion resistance can be obtained.

In particular, in order to easily achieve such improvements in wear resistance and corrosion resistance, palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, iridium alloy are used as the first noble metal layer. It is preferable that the first noble metal layer is made of any one of palladium, palladium alloy, rhodium, and rhodium alloy because the wear resistance and the contact resistance can be further reduced. The value of (A) is preferably 0.001 or more and less than 0.5, and more preferably 0.005 to 0.1. By setting the value of (A) within this range, the surface of the second noble metal layer subsequently formed on the first noble metal layer can be made smooth easily.
In addition, about the coating thickness of this 1st noble metal layer, it is although it does not restrict | limit in particular, In consideration of cost and bending workability, it is preferable that it is 0.001-3 micrometers, and it is 0.05-1 micrometers. Is more preferable.

  The second noble metal layer is made of a noble metal different from the noble metal constituting the first noble metal layer. The second noble metal layer is the outermost surface coating layer of the electrical contact material of the present invention, and the film thickness of the second noble metal layer is the arithmetic average roughness (Ra) of the surface of the first noble metal layer (A). The arithmetic average roughness Ra = (B) μm of the surface of the second noble metal layer is greater than or equal to 1 μm and B ≦ 0.1. This second noble metal layer is provided as a layer of a noble metal that protects the first noble metal layer and is different from the first noble 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 irregularities of (A) μm, which is the arithmetic average roughness (Ra) of the surface of the first noble metal layer. It functions as a coating layer that has both low contact resistance characteristics required as a contact material and surface lubricity and wear resistance, which are functions required as a sliding contact. The second noble metal layer not only exists to fill the unevenness of the first noble metal layer, but also has a thickness of more than (A) μm and not more than 1 μm, thereby further improving the corrosion resistance. . Furthermore, by setting the arithmetic average roughness Ra = (B) μm on the surface of the second noble metal layer to (B) ≦ 0.1, wear due to unevenness is suppressed and the exposure of the first noble metal layer or the conductive substrate is prevented. Demonstrate the effect. As described above, in the electrical contact material of the present invention in which the second noble metal layer is provided thicker than the arithmetic average roughness (Ra) = (A) μm of the first noble metal layer, the amount of the noble metal constituting the coating layer is the patent document. The cost is increased because it is more than 1, but it is excellent from the viewpoint of improving the corrosion resistance. Therefore, the total cost in a long-term use environment can be reduced.

  As the material of the second noble metal layer, gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, tin alloy, or the like is preferably used, particularly for applications that require corrosion resistance. Gold, gold alloy, platinum, and platinum alloy are preferable. On the other hand, silver, silver alloy, indium, indium alloy, tin, and tin alloy can be used as the material for the second noble metal layer as long as the electrical contact material is less likely to be exposed to the atmosphere after being molded with resin. is there. Since these metals and their alloys exhibit excellent solder wettability and contact resistance characteristics, 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 provided between the conductive substrate and the first noble metal layer. For example, it is preferable to provide a base metal layer made of nickel, nickel alloy, cobalt, or cobalt alloy because the diffusion barrier and adhesion between the first noble metal layer and the base component can be improved. In particular, in the present invention in which a noble metal than the conductive substrate is formed as the first noble metal layer or the second noble metal layer by plating, the base metal layer is formed by ground treatment such as flash plating or strike plating before the plating treatment. It is effective to improve the adhesion and prevent replacement. Further, the base metal layer may be a plurality of layers, and can be provided in various configurations according to a conventional method according to the specifications and applications of the coating of the first noble metal layer and the second noble metal layer. The total thickness of the base metal layer as a single layer or a plurality of layers is preferably 0.05 to 3 μm, and more preferably 0.5 to 1 μm.

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

  The covering layer composed of the first noble metal layer and the second noble metal layer in the electrical contact material of the present invention can be applied to any kind of appearance, particularly glossy, semi-glossy and matte. In addition, the effect of the present invention is sufficient, but in order to further improve the effect, various commonly used additives, dispersants, dispersed particles, and the like are used in the first noble metal layer and the second noble metal layer. It is also preferable to use a composite coating contained in one or more of the coating layer and the intermediate layer.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to this.

Example 1
After conducting the following pretreatment on the conductive substrate shown in Table 1 having a thickness of 0.3 mm and a width of 50 mm, the base metal layer, the first noble metal layer, and the second noble metal layer shown in Table 1 are electroplated in this order. It was provided on a conductive substrate by the method, and electrical contact materials of invention examples, comparative examples, and conventional examples shown in Table 1 were obtained.
In addition, the coating thickness of each layer uses a fluorescent X-ray film thickness measuring apparatus (SFT-9400, trade name, manufactured by SII), measures 10 points at an arbitrary location with a collimator diameter of 0.5 mm, and calculates the average value. Thus, the coating thickness was obtained.

(Pretreatment conditions)
[Cathode electrolytic degreasing]
Degreasing solution: NaOH 60 g / l
Degreasing conditions: 2.5 A / dm ² , temperature 60 ° C., degreasing time 60 seconds [pickling]
Pickling solution: 10% sulfuric acid pickling condition: 30 seconds immersion, room temperature

(Under metal layer plating conditions)
[Ni plating]
Plating _{solution: Ni (SO 3 NH 2)} 2 · 4H 2 O 500g / l, NiCl 2 30g / l, H 3 BO 3 30g / l
Plating conditions: temperature 50 ° C
[Co plating]
Plating solution: Co (SO ₃ NH ₂ ) ₂ · 4H ₂ O 500 g / l, CoCl ₂ 30 g / l, H ₃ BO ₃ 30 g / l
Plating conditions: temperature 50 ° C

(First precious metal layer plating conditions)
[Pd plating 1 (Pd1)]
Plating solution: Pd (NH ₃ ) ₂ Cl ₂ 45 g / l, NH ₄ OH 90 ml / l, (NH ₄ ) ₂ SO ₄ 50 g / l, Parasigma brightener (trade name, manufactured by Matsuda Sangyo Co., Ltd.) 10 ml / l
Plating conditions: current density 5 A / dm ² , temperature 60 ° C.
[Pd plating 2 (Pd2)] additive-free bath: used in Comparative Example 2 Plating solution: Pd (NH ₃ ) ₂ Cl ₂ 45 g / l, NH ₄ OH 90 ml / l, (NH ₄ ) ₂ SO ₄ 50 g / l
Plating conditions: current density 3 A / dm ² , temperature 60 ° C.
[Rh plating]
Plating solution: RHODEX (trade name, manufactured by Nippon Electroplating Engineers Co., Ltd.)
Plating conditions: 1.3 A / dm ² , temperature 50 ° C.
[Ru plating]
Plating solution: RUTHENEX100 (trade name, manufactured by Nippon Electroplating Engineers Co., Ltd.)
Plating conditions: current density 1 A / dm ² , temperature 65 ° C.
[Ir plating]
Plating solution: IRIDEX100 (trade name, manufactured by Nippon Electroplating Engineers Co., Ltd.)
Plating conditions: 0.2 A / dm ² , temperature 85 ° C.

(Second noble metal layer plating conditions)
[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 conditions: Temperature 40 ° C
[Pt plating]
Plating solution: Pt (NO ₂ ) (NH ₃ ) ₂ 10 g / l, NaNO ₂ 10 g / l, NH ₄ NO ₃ 100 g / l, NH ₃ 50 ml / l
Plating conditions: Temperature 80 ° C
[Ag plating]
Plating solution: AgCN 50 g / l, KCN 100 g / l, K ₂ CO ₃ 30 g / l
Plating conditions: current density 1 A / dm ² , temperature 30 ° C.
[Ag-Se alloy plating]
Plating solution: KCN 150 g / l, K ₂ CO ₃ 15 g / l, KAg [CN] ₂ 75 g / l, Na ₂ O ₃ Se · 5H ₂ O 5 g / l
Plating conditions: current density 2 A / dm ² , temperature 50 ° C.
[Sn plating]
Plating solution: SnSO ₄ 80 g / l, H ₂ SO ₄ 80 g / l
Plating conditions: current density 2 A / dm ² , temperature 30 ° C.

  With respect to each obtained electrical contact material, various characteristics were tested and evaluated under the following test conditions. The results are shown in Table 2.

(1A) Average crystal grain size (GS) of conductive substrate:
Three field views of the cross-sectional sample of the conductive substrate were prepared by FIB, and SIM image observation was performed to measure the particle diameters at three locations per field, and the average values are shown in Table 1.

(1B) Thickness measurement: The thicknesses of the first noble metal layer, the second noble metal layer, and the base metal layer were measured by a fluorescent X-ray film thickness meter (trade name: SFT9400) manufactured by SII Nano Technology. Ten arbitrary points were measured using a collimator diameter of 0.5 mm, and the average value was calculated to obtain the coating thickness. The results are shown in Table 1.

(1C) Hardness measurement: According to JIS Z 2244: 2009, the Vickers hardness (Hv) of the first noble metal layer when the measurement load was 0.005 N was measured. The hardness before coating the second noble metal layer. The results are shown in Table 1.

(1D) Arithmetic average roughness Ra: The arithmetic average roughness Ra was measured by a surface roughness meter (trade name: Surfcorder SE3500) manufactured by Kosaka Laboratory. Arithmetic average roughness Ra of the first noble metal layer Ra = (A) μm and arithmetic average roughness Ra of the second noble metal layer Ra = (B) μm under measurement conditions of a stylus tip radius of 2 μm and a measuring force of 0.75 N or less. It was measured. The results are shown in Table 1.

(2A) Dynamic friction coefficient measurement: The dynamic friction coefficient was measured using a sliding test apparatus (HEIDON Type: 14FW, trade name, manufactured by Shinto Kagaku Co., Ltd.). The measurement conditions are as follows.
R = 2.0 mm Steel ball probe, sliding distance 10 mm, sliding speed 100 mm / min, number of sliding times 100 reciprocations, load 100 gf
In the sliding test, the dynamic friction coefficients after the reciprocating sliding times of 1, 50 and 100 times were measured and shown in Table 2.

(2B) Wear depth: About the wear depth after the end of the sliding test, the depth (μm) of the central section of the sliding mark was measured using a microscope (VH8000, trade name, manufactured by Keyence Corporation). The deepest part is shown in Table 2 as the wear depth.

(2C) Contact resistance measurement: As an index of corrosion resistance, the contact resistance was measured and evaluated as follows. The contact resistance was measured after forming the outermost layer (the second noble metal layer) by the four-terminal method. Measurement is immediately after the formation of the outermost layer (initial stage), after sulfur dioxide test (SO ₂ 10 ppm, 40 ° C., 80% RH, 168 hours), hydrogen sulfide test (H ₂ S 3 ppm, 40 ° C., 80% RH, 168 hours) The latter three levels were used. For the evaluation, an Ag probe with a radius of 2 mm was used, and the contact resistance at 10 measurement points was measured with a current of 10 mA and a load of 10 gf, and the average value was calculated as the contact resistance. As an evaluation, 10 mΩ or less as “excellent” is “A”, 10 mΩ is exceeded as 50 mΩ or less as “good” as “B”, 50 mΩ is exceeded as 100 mΩ as “possible” and “C” is set as 100 mΩ. The excess was indicated as “impossible” as “D” in Table 2. The practical level is determined as “C”, “B”, or “A”.

(2D) Bending workability: For each sample, a V-bending test was carried out at a bending radius of 0.9 mm (R / t = 3) in a direction perpendicular to the rolling rebar, and then the top of the sample was subjected to a microscope (VH8000, (Trade name, manufactured by Keyence Corporation) was observed at an observation magnification of 200 times. Those with no cracks are indicated as “Excellent” with “A”, those with minor cracks are indicated as “Yes” with “B”, and those with relatively large cracks are indicated as “No”. As “C” in Table 2. The practical level is determined as “B” or “A”.

(2E) Solder wettability: Each test piece obtained by the above plating treatment was immersed in a Sn-3Ag-0.5Cu solder bath at a bath temperature of 245 ° C. using MODEL SAT-5100 (trade name, manufactured by Reska). Immersion was performed using isopropyl alcohol-25 mass% rosin flux under conditions of a distance of 10 mm and an immersion speed of 25 mm / sec. The time from when the test piece was immersed until the wetting force crossed zero (zero cross time) was measured. The resulting zero cross time (seconds) is shown in Table 2. Solder wettability is evaluated by assuming that the zero cross time is less than 1 second as “excellent”, 1 second or more within 3 seconds as “good”, and 3 seconds over as “impossible”.

From the above results, each example of the invention shows a stable dynamic friction coefficient even under a high sliding load of 100 gf, good sliding characteristics, excellent wear resistance indicated by the wear depth, and indicated by contact resistance. It can be seen that it has excellent corrosion resistance, and has good bending workability and solder wettability.
In contrast, each of the comparative examples and the conventional example was inferior to any of the characteristics.
In Comparative Example 1, since the surface roughness Ra (B) of the second noble metal layer was too high, the contact resistance was increased when the number of sliding times was 50 to 100 under a high sliding load of 100 gf. Moreover, bending workability 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 sliding times increased from 50 to 100 under a high sliding load of 100 gf, and the wear resistance was increased. It was bad. In Conventional Example 1, since the coating thickness of the second noble metal layer was thinner than the arithmetic average roughness Ra = (A) μm of the surface of the first noble metal layer, the number of slides was 50 times under a high sliding load of 100 gf. The contact resistance increased from 100 times. None of these comparative examples and conventional examples satisfied the practical level.

  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. Especially because of its excellent wear resistance and corrosion resistance, it is particularly useful as a material for electrical contacts such as indoor and outdoor sliding contacts for automobiles, reed switches, motor commutator contacts and brush materials, and camera mount contact switches. It can be used suitably.

  While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

DESCRIPTION OF SYMBOLS 1 Conductive base | substrate 2 1st noble metal layer 3 2nd noble metal layer 4 Base metal layer

As a result of diligent research and development on the above problems, the present inventors have found that each of the first and second noble metal layers provided on the conductive substrate has a surface roughness and a layer thickness. is the hardness of the layer, by appropriately adjusting the average crystal grain size and the like of the matrix of the conductive substrate, not only excellent wear resistance and sliding characteristics in high load, the electrical contacts also excellent in corrosion resistance We have found that we can provide materials. The present invention has been made based on this finding.

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 substrate and a second noble metal layer on the surface of the first noble metal layer,
The arithmetic average 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 is at 1μm or less beyond Eimyuemu, and Ri arithmetic mean roughness Ra = Bμm is B ≦ 0.1 Der surface of the second noble metal layer,
An electrical contact material, wherein an average crystal grain size of a matrix of the conductive substrate is 5 μm or less .
(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 noble metal layer and the second noble 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. , Rhodium, rhodium alloy, osmium, osmium alloy, iridium, an iridium alloy, the electrical contact material according to (1) or (2).
(4) Any one of (1) to (3), wherein the first noble metal layer is made of any one of palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, and iridium alloy. The electrical contact material according to Item.
(5) Any one of (1) to (4), wherein the second noble metal layer is made of any one of gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, and tin alloy. The electrical contact material according to Item.
(6) The electrical contact material according to any one of (1) to (5), wherein the electrical contact material has 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 nickel, nickel alloy, cobalt, or cobalt alloy.
(8) The electrical contact material according to (6) or (7), wherein the base 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 substrate is made of any one of copper, copper alloy, iron, iron alloy, aluminum, and aluminum alloy .
(10 ) The method for producing an electrical contact material according to any one of (1) to ( 9 ), wherein at least one of the first noble metal layer and the second noble metal layer is provided by electroplating.
Here, in the present invention, the “noble metal” in the first noble metal layer and the second noble metal layer means a metal noble than the material of the conductive substrate.

The present invention is an electrical contact material having a first noble metal layer on the surface of a conductive substrate and a second noble metal layer on the surface of the first noble metal layer, the arithmetic of the surface of the first noble metal layer Average roughness Ra = (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 1 μm (A) μm. or less and Ri arithmetical mean roughness Ra = (B) μm (B ) ≦ 0.1 der surface of the second noble metal layer, the average crystal grain size of the matrix of the conductive substrate is 5μm or less der Ru is an electrical contact material. Here, the arithmetic average roughness Ra means the arithmetic average roughness Ra according to JIS B 0601: 2013.

Furthermore, as the conductive substrate in the present invention, by adopting a conductive substrate matrix (matrix) having an average crystal grain size of 5 μm or less, the plating deposited on the upper layer can be densely deposited. As a result, a plating having a large number of crystal grains can be formed to disperse the grain boundary diffusion, and the time for the diffusion of the base component to reach the surface layer can be greatly delayed. As a result, corrosion of the diffused base component in the surface layer of the second noble metal layer can be suppressed, and an increase in contact resistance can be suppressed and a highly reliable electrical contact material can be provided. Further, as the average crystal grain size of the conductive base material is smaller, the bending workability of the conductive base is more excellent as a synergistic effect.
The average crystal grain size of the conductive substrate base material, 5 [mu] m Ri der less, 3 [mu] m or less good Mashiku to enhance the denseness of plating more, and more preferably not more than 1 [mu] m. Although there is no restriction | limiting in particular in this lower limit, Usually, it is 0.001 micrometer or more.

Example 1
After conducting the following pretreatment on the conductive substrate shown in Table 1 having a thickness of 0.3 mm and a width of 50 mm, the base metal layer, the first noble metal layer, and the second noble metal layer shown in Table 1 are electroplated in this order. It was provided on a conductive substrate by the method, and electrical contact materials of invention examples, reference examples, comparative examples, and conventional examples shown in Table 1 were obtained.
In addition, the coating thickness of each layer uses a fluorescent X-ray film thickness measuring apparatus (SFT-9400, trade name, manufactured by SII), measures 10 points at an arbitrary location with a collimator diameter of 0.5 mm, and calculates the average value. Thus, the coating thickness was obtained.

From the above results, each example of the invention shows a stable dynamic friction coefficient even under a high sliding load of 100 gf, good sliding characteristics, excellent wear resistance indicated by the wear depth, and indicated by contact resistance. It can be seen that it has excellent corrosion resistance, and has good bending workability and solder wettability.
In contrast, each of the comparative examples and the conventional example was inferior to any of the characteristics.
In Comparative Example 1 , the average crystal grain size of the parent phase of the conductive substrate was too large, and the surface roughness Ra (B) of the second noble metal layer was too high. When the number of movements was 50 to 100, the contact resistance increased, and the bending workability was poor. In Comparative Example 2 , the average crystal grain size of the parent phase of the conductive substrate was too large, and the hardness of the first noble metal layer was too low, so the number of sliding times was 50 times under a high sliding load of 100 gf. When it reached 100 times, the contact resistance increased and the wear resistance was poor. In Conventional Example 1, since the coating thickness of the second noble metal layer was thinner than the arithmetic average roughness Ra = (A) μm of the surface of the first noble metal layer, the number of slides was 50 times under a high sliding load of 100 gf. The contact resistance increased from 100 times. None of these comparative examples and conventional examples satisfied the practical level.

As a result of advancing earnest research and development on the above problems, the present inventors have found that each of the first noble metal layer and the second noble metal layer made of a specific metal or an alloy thereof provided on the conductive substrate. By appropriately adjusting the surface roughness, layer thickness, layer hardness, average crystal grain size of the base phase of the conductive substrate, etc., it is only excellent in wear resistance and sliding characteristics at high loads. And found that an electrical contact material having excellent corrosion resistance can be provided. The present invention has been made based on this finding.

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 substrate and a second noble metal layer on the surface of the first noble metal layer,
The arithmetic average 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 is more than A μm and not more than 1 μm, and the arithmetic average roughness Ra = B μm of the surface of the second noble metal layer is B ≦ 0.1;
The first noble metal layer and the second noble metal layer are gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, tin alloy, palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, respectively. Made of either rhodium alloy, osmium, osmium alloy, iridium, iridium alloy,
An electrical contact material, wherein an average crystal grain size of a matrix of the conductive substrate is 5 μm or less.
(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 noble metal layer is a palladium, palladium alloys, ruthenium, ruthenium alloys, rhodium, rhodium alloys, osmium, osmium alloy, iridium, among iridium alloy consists of either (1) or (2) according to claim Electrical contact material.
( 4 ) Any one of (1) to ( 3 ), wherein the second noble metal layer is made of any one of gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, and tin alloy. The electrical contact material according to Item.
( 5 ) The electrical contact material according to any one of (1) to ( 4 ), wherein at least one base metal layer is provided between the conductive substrate and the first noble metal layer.
( 6 ) The electrical contact material according to ( 5 ), wherein the base metal layer is made of any one of nickel, a nickel alloy, cobalt, and a cobalt alloy.
( 7 ) The electrical contact material according to ( 5 ) or ( 6 ), wherein the thickness of the base metal layer is 0.05 to 3.00 μm.
( 8 ) The electrical contact material according to any one of (1) to ( 7 ), wherein the conductive substrate is made of any one of copper, copper alloy, iron, iron alloy, aluminum, and aluminum alloy.
( 9 ) The method for producing an electrical contact material according to any one of (1) to ( 8 ), wherein at least one of the first noble metal layer and the second noble metal layer is provided by an electroplating method.
Here, in the present invention, the “noble metal” in the first noble metal layer and the second noble metal layer means a metal noble than the material of the conductive substrate.

The present invention is an electrical contact material having a first noble metal layer on the surface of a conductive substrate and a second noble metal layer on the surface of the first noble metal layer, the first noble metal layer and the second noble metal Each layer is made of a specific metal or an alloy thereof, the arithmetic average 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 The thickness of the second noble metal layer is more than (A) μm and not more than 1 μm, and the arithmetic average roughness Ra = (B) μm of the surface of the second noble metal layer is (B) ≦ 0. The electrical contact material has an average crystal grain size of 5 μm or less. Here, the arithmetic average roughness Ra means the arithmetic average roughness Ra according to JIS B 0601: 2013.

In the present invention, a metal or alloy forming the first noble metal layer and the second noble metal layer is gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, tin alloy, palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloys, osmium, osmium alloy, iridium, Ru iridium alloy der.
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 improve the corrosion resistance. This is because the arithmetic average roughness Ra = (A) μm of the surface of the first noble metal layer is set to (A) <1, so that the wear resistance is improved and the hardness Hv is 150 or more, preferably 200 or more. This is because the wear resistance can be further improved.
Moreover, it is preferable that the value of (A) is 0.001 or more and less than 0.500, whereby an electrical contact material having more excellent corrosion resistance can be obtained.

The material of the second noble metal layer, a gold, a gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, Suzugo gold is preferably used in applications that are particularly required corrosion resistance Gold, gold alloy, platinum, and platinum alloy are preferable. On the other hand, silver, silver alloy, indium, indium alloy, tin, and tin alloy can be used as the material for the second noble metal layer as long as the electrical contact material is less likely to be exposed to the atmosphere after being molded with resin. is there. Since these metals and their alloys exhibit excellent solder wettability and contact resistance characteristics, they can be appropriately selected depending on the application and case.

From the above results, in each invention example has good sliding properties indicate a stable dynamic friction coefficient even under high sliding load of 100 gf, excellent wear resistance represented by milling耗深is, represented by the contact resistance It can be seen that it has excellent corrosion resistance, and has good bending workability and solder wettability.
In contrast, each of the comparative examples and the conventional example was inferior to any of the characteristics.
In Comparative Example 1, the average crystal grain size of the parent phase of the conductive substrate was too large, and the surface roughness Ra (B) of the second noble metal layer was too high. When the number of movements was 50 to 100, the contact resistance increased, and the bending workability was poor. In Comparative Example 2, the average crystal grain size of the parent phase of the conductive substrate was too large, and the hardness of the first noble metal layer was too low, so the number of sliding times was 50 times under a high sliding load of 100 gf. When it reached 100 times, the contact resistance increased and the wear resistance was poor. In Conventional Example 1, since the coating thickness of the second noble metal layer was thinner than the arithmetic average roughness Ra = (A) μm of the surface of the first noble metal layer, the number of slides was 50 times under a high sliding load of 100 gf. The contact resistance increased from 100 times. None of these comparative examples and conventional examples satisfied the practical level.

Claims (11)

An electrical contact material having a first noble metal layer on a surface of a conductive substrate and a second noble metal layer on the surface of the first noble metal layer,
The arithmetic average 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 is more than A μm and not more than 1 μm, and the arithmetic average roughness Ra = B μm of the surface of the second noble metal layer is B ≦ 0.1 .   The electrical contact material according to claim 1, wherein the value of A is 0.001 or more and less than 0.500.   The first noble metal layer and the second noble metal layer are gold, gold alloy, silver, silver alloy, platinum, platinum alloy, indium, indium alloy, tin, tin alloy, palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, respectively. The electrical contact material according to claim 1 or 2, comprising any one of rhodium alloy, osmium, osmium alloy, iridium, and iridium alloy.   The electricity according to any one of claims 1 to 3, wherein the first noble metal layer is made of any one of palladium, palladium alloy, ruthenium, ruthenium alloy, rhodium, rhodium alloy, osmium, osmium alloy, iridium, and iridium alloy. Contact material.   The electricity according to any one of claims 1 to 4, wherein the second noble 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.   The electrical contact material according to claim 1, wherein the electrical contact material has at least one base metal layer between the conductive base and the first noble metal layer.   The electrical contact material according to claim 6, wherein the base metal layer is made of any one of nickel, a nickel alloy, cobalt, and a cobalt alloy.   The electrical contact material according to claim 6 or 7, wherein the base metal layer has a thickness of 0.05 to 3.00 µm.   The electrical contact material according to any one of claims 1 to 8, wherein the conductive substrate is made of any one of copper, copper alloy, iron, iron alloy, aluminum, and aluminum alloy.   The electrical contact material according to any one of claims 1 to 9, wherein an average crystal grain size of a parent phase of the conductive substrate is 5 µm or less.   The method for producing an electrical contact material according to claim 1, wherein at least one of the first noble metal layer and the second noble metal layer is provided by an electroplating method.

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