WO2023234015A1 - Surface-coated material for electrical contacts, and electrical contact, switch and connector terminal each using same - Google Patents

Abstract

The present invention provides: a surface-coated material for electrical contacts, the surface-coated material exhibiting excellent bending workability, while having a surface that is provided with a silver-containing layer which is capable of suppressing adhesion and thereby enhancing the wear resistance under the conditions that are in line with the actual usage environment; and an electrical contact, a switch and a connector terminal, each of which uses this surface-coated material for electrical contacts.　A surface-coated material 1 for electrical contacts according to the present invention comprises a conductive base material 2 and a silver-containing layer 3 that covers at least one surface of the conductive base material 2. With respect to the silver-containing layer 3, if h₁ is a first total peak intensity which is the sum of the peak intensity assigned to the Ag (111) plane and the peak intensity assigned to a plane that is parallel to the Ag (111) plane as determined from the X-ray diffraction chart, and h₂ is a second total peak intensity which is the sum of the other peak intensities, that is the value obtained by subtracting the first total peak intensity h₁ from the sum of all detected peak intensities, the ratio (h₁/h₂) of the first total peak intensity (h₁) to the second total peak intensity (h₂) is within the range of 1.0 to 3.0.

Description

Surface coating materials for electrical contacts, and electrical contacts, switches and connector terminals using the same

The present invention relates to a surface coating material for electrical contacts, and electrical contacts, switches, and connector terminals using the same.

In recent years, electronic control of consumer electronic devices and in-vehicle connection parts has progressed rapidly, and the conventional direct-cutting contacts that directly cut off the power current have been replaced by signal-cutting contacts that cut off electrical signals. is increasing. The contacts of switches and connectors installed in these consumer electronic devices and automotive connection parts are required to have durability against sliding due to repeated on/off operations of switches and sliding of connectors. The durability of is evaluated by a keystroke test. This keystroke test also requires that the electrical resistance of the contacts be low, so these contacts are made of a conductive base material containing copper (Cu), iron (Fe), or aluminum (Al) as the main components. Surface coating materials for electrical contacts are used, in which the surface is plated with a base plate of nickel (Ni) or the like, and further plated with silver (Ag) or a silver alloy.

For example, Patent Document 1 describes a copper alloy composite foil in which a smooth layer of silver is provided on at least one surface of a copper alloy plate, and (200) crystals on the surface of the smooth layer of silver are measured by X-ray diffraction. The strength of the orientation is in the range of 34 or more and 100 or less when the sum of the strength of the (220) crystal orientation and the strength of the (111) crystal orientation is 100, and the strength of the (220) crystal orientation is in the range of (111). A copper alloy composite foil is described that has a crystal orientation strength in a range of 18 or more and 120 or less when the strength of crystal orientation is 100.

JP2020-26566A

However, silver has the property of being easily abraded due to adhesion, so the silver (Ag) or silver alloy plating applied to the surface is abraded due to sliding due to switching on/off operations or sliding of connectors. This has the drawback of increasing contact resistance. Regarding this, in the copper alloy composite foil described in Patent Document 1, even if the hardness is increased by increasing the peak intensity derived from the Ag (220) plane obtained from the X-ray diffraction chart of the silver smooth layer, the silver Since the adhesion is not suppressed, the durability as evaluated by the keystroke test has not yet been improved. In addition, in the copper alloy composite foil described in Patent Document 1, peak intensities derived from the Ag (200) plane, Ag (220) plane, and Ag (111) plane obtained from the X-ray diffraction chart of the silver smooth layer It focuses only on the relationship between peak intensities derived from , and does not focus on the influence of other peak intensities.

Furthermore, the copper alloy composite foil described in Patent Document 1 was subjected to a sliding wear test using a steel ball as a mating material, but in the actual usage environment, adhesion with silver is more likely to occur than with steel balls. Since wear caused by sliding becomes a problem, there is a need to improve the wear resistance, which is evaluated by a keystroke test that matches the actual usage environment.

Furthermore, the copper alloy composite foil described in Patent Document 1 has poor bending workability, and its shape is unstable when molded into the shape of a terminal or connector.

The present invention is a surface coating material for electrical contacts that has a silver-containing layer on the surface that has excellent bending workability and can suppress adhesion and increase wear resistance under conditions suitable for actual usage environments. and to provide electrical contacts, switches, and connector terminals using the same.

The present inventors took into account all the peak intensities obtained from the X-ray diffraction chart of the silver-containing layer, and determined that the peak intensities originate from the Ag (111) plane and the peak intensities originate from the plane parallel to the Ag (111) plane. The first total peak intensity, which is the total value with the peak intensity, is set as _h1 , and the sum of the remaining peak intensities obtained by subtracting the first total peak intensity ( _h1 ) from the total value of all detected peak intensities. When the value of the second total peak intensity is _h2 , the ratio ( _h1 / _h2 ) of the first total peak intensity (h1) to _the second total peak intensity ( _h2 ) is 1.0 or more 3 It has been discovered that by setting the silver-containing layer to a range of .0 or less, it is possible to improve the bending workability of the surface coating material for electrical contacts, as well as the wear resistance of the silver-containing layer under conditions that match the actual usage environment. , we have completed the present invention.

That is, the gist of the present invention is as follows.
(1) A surface coating material for electrical contacts comprising a conductive base material and a silver-containing layer covering at least one side of the conductive base material, the silver-containing layer being obtained from an X-ray diffraction chart. , the first total peak intensity, which is the sum of the peak intensity originating from the Ag (111) plane and the peak intensity originating from the plane parallel to the Ag (111) plane, is _h1 , and all detected When the second total peak intensity, which is the total value of the remaining peak intensities after subtracting the first total peak intensity (h ₁ ) from the total value of peak intensities, is h ₂ , the second total peak intensity (h ₂ ), wherein the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to ) is in the range of 1.0 or more and 3.0 or less.
(2) The silver-containing layer is the surface coating material for electrical contacts according to (1) above, wherein the half width of the peak derived from the Ag (111) plane is in the range of 0.15° or more and 0.30° or less. .
(3) The surface coating material for electrical contacts according to (1) or (2) above, wherein the silver-containing layer contains 99% by mass or more of silver.
(4) The electrical contact surface coating according to any one of (1) to (3) above, wherein the conductive base material is made of pure copper, copper alloy, pure iron, iron alloy, pure aluminum, or aluminum alloy. material.
(5) Any one of (1) to (4) above, further comprising at least one intermediate layer made of pure copper, copper alloy, pure nickel, or nickel alloy between the conductive base material and the silver-containing layer. The surface coating material for electrical contacts according to item 1.
(6) The surface coating material for electrical contacts according to any one of (1) to (5) above, wherein the conductive base material has a thickness in a range of 0.03 mm or more and 0.30 mm or less.
(7) An electrical contact produced using the surface coating material for electrical contacts according to any one of (1) to (6) above.
(8) A switch having the electrical contact described in (7) above.
(9) A connector terminal having the electrical contact described in (7) above.

According to the present invention, a surface for electrical contacts is provided with a silver-containing layer on the surface that has excellent bending workability and is capable of suppressing adhesion and increasing wear resistance under conditions consistent with the actual usage environment. A coating material and electrical contacts, switches, and connector terminals using the same can be provided.

FIG. 1 is a schematic cross-sectional view including the thickness direction, showing an example of the surface coating material for electrical contacts of the present invention. FIG. 7 is a schematic cross-sectional view including the thickness direction, showing a modification of the surface coating material for electrical contacts of the present invention including an intermediate layer.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the following embodiments, and various changes can be made without changing the gist of the present invention.

1. Surface Coating Material for Electrical Contacts The surface coating material 1 for electrical contacts of the present invention includes a conductive base material 2 and a silver-containing layer 3 covering at least one side of the conductive base material 2, and the silver-containing layer 3 includes: The first total peak intensity, which is the sum of the peak intensity derived from the Ag (111) plane and the peak intensity derived from the plane parallel to the Ag (111) plane, obtained from the X-ray diffraction chart, is defined as _h1 . In addition, when the second total peak intensity, which is the total value of the remaining peak intensities after subtracting the first total peak intensity (h ₁ ) from the total value of all detected peak intensities, is h ₂ , the second total The ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to _the peak intensity (h 2 ) is in the range of 1.0 or more and 3.0 or less.

As a result, the ratio of the orientation of silver contained in the silver-containing layer 3 that is non-parallel to the Ag (111) plane, which is an orientation that provides excellent keying performance, is moderately increased compared to all orientations, so that in practice Even when silver, which tends to adhere, is used as a mating material in accordance with the usage environment, it is possible to suppress adhesion of silver during a keystroke test and thereby suppress wear of the silver-containing layer 3. In addition, in the silver-containing layer 3, the proportion of the orientation parallel to the Ag (111) plane is relatively decreased, and the proportion of silver oriented in other directions is relatively increased, so that the electrical contact surface coating material 1 The bending workability of the material is improved. As a result, the surface coating material for electrical contacts has a silver-containing layer 3 on its surface that has excellent bending workability and can suppress adhesion and increase wear resistance under conditions suitable for the actual usage environment. 1 can be provided.

(1) Surface coating material for electrical contacts according to one embodiment FIG. 1 is a schematic cross-sectional view including the thickness direction, showing an example of the surface coating material for electrical contacts of the present invention. The surface coating material 1 for electrical contacts includes a conductive base material 2 and a silver-containing layer 3 covering at least one side of the conductive base material 2. In addition, although the surface coating material 1 for electrical contacts in FIG. may be coated on both sides.

Hereinafter, each part of the surface coating material 1 for electrical contacts will be explained in detail.

(Conductive base material)
The conductive base material 2 is made of pure copper, copper alloy, pure iron, iron alloy, pure aluminum, or aluminum alloy.

Among these, copper alloys include Cu-Sn-P, Cu-Zn, Cu-Ni-Si, Cu-Sn-Ni, Cu-Cr-Mg, and Cu-Ni-Si-Zn-Sn. -Mg type etc. can be mentioned. Further, examples of iron alloys include Fe-Cr-Ni series, Fe-Cr series, and the like. Further, examples of the aluminum alloy include Al--Mg type, Al--Mg--Si type, and the like.

The shape of the conductive base material 2 is not particularly limited and may be appropriately selected depending on the application, but it is preferably a strip or a plate, and can also be a bar or wire. Moreover, it is preferable that the conductive base material 2 is manufactured by rolling.

The conductivity of the conductive base material 2 is not particularly limited, but it is preferably 20% IACS or more, and more preferably 25% IACS or more. Thereby, the entire electrical contact surface coating material 1 can have excellent electrical conductivity. Here, the electrical conductivity (IACS; International Annealed Copper Standard) can be determined by measuring in a constant temperature bath controlled at 20° C. (±1° C.) using a four-terminal method.

The conductive base material 2 preferably has a thickness in the range of 0.03 mm or more and 0.30 mm or less. Here, by setting the thickness of the conductive base material 2 to 0.30 mm or less, the electrical contact surface coating material 1 having the conductive base material 2 can be easily used as a contact material for a switch. On the other hand, by setting the thickness of the conductive base material 2 to 0.03 mm or more, the mechanical strength of the conductive base material 2 can be increased. Note that a method for measuring the thickness of the conductive base material 2 will be described later.

(Silver-containing layer)
The silver-containing layer 3 is provided to cover at least one side of the conductive base material 2 and contains silver (Ag). Here, the silver-containing layer 3 is preferably made of pure silver or a silver alloy containing 95% by mass or more of silver, and more preferably made of pure silver containing 99% by mass or more of silver. Among these, it is particularly preferable that the silver-containing layer 3 is made of pure silver made of silver and unavoidable impurities. When the silver-containing layer 3 contains a large amount of silver, the contact resistance value of the surface on which the silver-containing layer 3 is formed becomes small, so when the surface coating material 1 for electrical contacts is used as an electrical contact such as a switch or a connector. can improve electrical connectivity.

On the other hand, the silver-containing layer 3 contains one or more elements selected from the group consisting of zinc (Zn), copper (Cu), nickel (Ni), selenium (Se), antimony (Sb), and cobalt (Co). It may also contain a second element consisting of. When the silver-containing layer 3 contains such a second element, the keying performance and wear resistance of the electrical contact surface coating material 1 can be further improved. On the other hand, from the viewpoint of improving the electrical connectivity of the surface coating material 1 for electrical contacts, the silver-containing layer 3 contains zinc (Zn), copper (Cu), nickel (Ni), selenium (Se), and antimony (Sb). and cobalt (Co) in a total amount of 5% by mass or less.

The silver-containing layer 3 has a first total peak obtained from an X-ray diffraction chart, which is the sum of the peak intensity derived from the Ag (111) plane and the peak intensity derived from the plane parallel to the Ag (111) plane. Let h ₁ be the intensity, and let h ₂ be the second total peak intensity, which is the total value of the remaining peak intensities after subtracting the first total peak intensity (h ₁ ) from the total value of all detected peak intensities. In this case, the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to _the second total peak intensity (h 2 ) is in the range of 1.0 or more and 3.0 or less. In the surface coating material 1 for electrical contacts of the present invention, the orientation of the silver contained in the silver-containing layer 3 is important, and the Ag(111) plane and the plane parallel to the Ag(111) plane are on the surface of the silver-containing layer 3. The exposed crystal orientation has the property of reducing the keying performance of the surface coating material 1 for electrical contacts, while the crystal orientation in which the plane that is not parallel to the Ag (111) plane is exposed on the surface of the silver-containing layer 3 is difficult for electrical contacts. It has the property of improving the keying performance of the surface coating material 1. Therefore, in particular, by setting the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ) in the range of 1.0 to 3.0, Ag(111 ) The proportion of peak intensities originating from planes that are not parallel to the plane is moderately increased. As a result, even when the mating material is pure silver, adhesion of the silver-containing layer 3 can be suppressed and wear resistance can be increased, and in particular, the keying performance of the surface coating material 1 for electrical contacts can be improved. can.

Here, by setting the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ) to 1.0 or more, the crystals contained in the silver-containing layer 3 are It is possible to suppress a decrease in the bending workability of the surface coating material 1 for electrical contacts due to an excessive amount of strain, and in particular, it is possible to suppress cracking of the silver-containing layer 3 during bending. In addition, by setting the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ) to 3.0 or less, the surface that is not parallel to the Ag (111) surface can be Since the ratio of the derived peak intensity is relatively increased, adhesion of the silver-containing layer 3 can be suppressed and wear resistance can be improved.

Examples of planes parallel to the Ag (111) plane include the Ag (222) plane and the Ag (333) plane, but the peak intensity of planes other than the Ag (222) plane that appears in the X-ray diffraction chart is weak. Therefore, only the Ag (222) plane may be a plane parallel to the Ag (111) plane.

In the silver-containing layer 3, the half width of the peak derived from the Ag (111) plane obtained from the X-ray diffraction chart is preferably in the range of 0.15° or more and 0.30° or less. In particular, by setting the half-value width of the peak originating from the Ag (111) plane to 0.30° or less, the amount of strain in the crystal contained in the silver-containing layer 3 becomes excessive. It is possible to suppress a decrease in bending workability. In addition, by setting the half width of the peak derived from the Ag (111) plane to 0.15° or more, it is possible to maintain a high amount of strain remaining in the crystals included in the silver-containing layer 3, and to increase the hardness of the silver-containing layer 3. Since this increases, the keying performance and abrasion resistance of the silver-containing layer 3 can be improved.

The thickness of the silver-containing layer 3 is not particularly limited, but is preferably in the range of, for example, 0.05 μm or more and 10 μm or less. In particular, by setting the thickness of the silver-containing layer 3 to 0.05 μm or more, the excellent keying performance of the electrical contact surface coating material 1 can be maintained for a longer period of time. Therefore, the thickness of the silver-containing layer 3 is preferably 0.05 μm or more, more preferably 0.10 μm or more, and even more preferably 0.15 μm or more. On the other hand, by setting the thickness of the silver-containing layer 3 to 10 μm or less, the material cost of the surface coating material 1 for electrical contacts can be suppressed. Therefore, the thickness of the silver-containing layer 3 is preferably 10 μm or less, more preferably 2.0 μm or less, and even more preferably 1.0 μm or less. Note that a method for measuring the thickness of the silver-containing layer 3 will be described later.

(2) Surface coating material for electrical contacts according to other embodiments FIG. 2 is a schematic cross-sectional view including the thickness direction, showing a modification of the surface coating material for electrical contacts of the present invention including an intermediate layer. The surface coating material 1A for electrical contacts shown in FIG. 2 further includes at least one intermediate layer 4 made of pure copper, copper alloy, pure nickel, or nickel alloy between the conductive base material 2 and the silver-containing layer 3. That is, the silver-containing layer 3 of the electrical contact surface coating material 1A covers at least one side of the conductive base material 2 with the intermediate layer 4 interposed therebetween. Since the surface coating material 1A for electrical contacts includes the intermediate layer 4, thermal diffusion of elements constituting the conductive base material 2 into the silver-containing layer 3 can be suppressed, and the conductive base material 2 and Adhesion with the silver-containing layer 3 can be improved.

Among these, examples of the nickel alloy include Ni--P type. Further, examples of the copper alloy include Cu--Sn type, Cu--Co type, etc.

The thickness of the intermediate layer 4 is not particularly limited, but is preferably in the range of 0.01 μm or more and 1.00 μm or less, for example. In particular, by setting the thickness of the intermediate layer 4 to 0.01 μm or more, thermal diffusion of elements constituting the conductive base material 2 to the silver-containing layer 3 can be easily suppressed, and the conductive base material 2 and the silver Adhesion with the containing layer 3 can be easily improved. On the other hand, by setting the thickness of the intermediate layer 4 to 1.00 μm or less, the bending workability of the surface coating material 1A for electrical contacts can be improved, and in particular, the ratio of the bending radius to the thickness (R/t) can be improved. Even when bending is performed as shown in FIG. 1, damage to the electrical contact surface coating material 1A can be made less likely to occur.

Since the surface coating materials 1 and 1A for electrical contacts configured as described above have the property that the silver-containing layer 3 is not easily worn out due to adhesion, electrical contacts are manufactured using the surface coating materials 1 and 1A for electrical contacts. It is particularly preferable that the silver-containing layer 3 is configured to be in electrical contact with the mating material. At this time, even if the mating material is silver, which tends to adhere, it is difficult to wear out due to sliding due to repeated on/off operations of a switch or sliding of a connector terminal, so it is difficult to increase the contact resistance of the electrical contact. can do. In addition, the electrical contact surface coating materials 1 and 1A have excellent bending properties, so that when molded into the shape of a terminal or connector, the shape can be easily stabilized. Therefore, the surface coating materials 1 and 1A for electrical contacts of the present invention can be suitably used for switches and connector terminals having electrical contacts. Furthermore, such switches and connector terminals can be used in various consumer electronic devices and in-vehicle connection parts.

In addition, in the surface coating materials 1 and 1A for electrical contacts of the present invention, the silver-containing layer 3 and intermediate layer 4 coated on the conductive base material 2 only need to be formed on at least one side of the conductive base material 2. , may be formed on both sides of the conductive base material 2.

3. Method for manufacturing surface coating material for electrical contacts As an example of a method for manufacturing surface coating material 1 for electrical contacts, a silver-containing layer 3 is formed on at least one side of a conductive base material 2 that has been electrolytically degreased, and then the silver-containing layer 3 is A method of rolling the conductive base material 2 having a surface formed thereon can be mentioned. In particular, the method for producing the surface coating material 1 for electrical contacts including the intermediate layer 4 includes sequentially forming the intermediate layer 4 and the silver-containing layer 3 on at least one side of the conductive base material 2 that has been subjected to electrolytic degreasing and acid cleaning. After that, the conductive base material 2 on which these are formed is subjected to a rolling process.

An example of pre-treatment of the conductive base material 2 includes a method of electrolytically degreasing and acid cleaning the conductive base material 2. Here, when the conductive base material 2 is made of pure iron or an iron alloy, as a pretreatment of the conductive base material 2, the oxide film on the surface is removed by performing acid electrolysis after electrolytic degreasing, and then nickel strike is performed. Plating may be applied. Further, when the conductive base material 2 is made of pure aluminum or an aluminum alloy, alkali etching may be performed as a pretreatment of the conductive base material 2.

Further, as a method for forming the silver-containing layer 3 and the intermediate layer 4, plating methods can be used, such as wet plating methods such as electrolytic plating and electroless plating, and dry plating methods such as vapor deposition and sputtering. can be used. Among these, from the viewpoint of efficiently forming a layer having a desired thickness, it is preferable to use a wet plating method, and it is more preferable to use electrolytic plating. For example, electrolytic plating when forming the silver-containing layer 3 is performed in an alkali cyan silver bath with a bath temperature (liquid temperature) of 20° C. or more and 25° C. or less, and a current density of 5 A/dm ² or more and 10 A/dm ² or less. be able to. Furthermore, when forming a layer made of pure copper or copper alloy as the intermediate layer 4, electrolytic plating is performed in a copper plating bath with a bath temperature (liquid temperature) of 40°C or higher and 55°C or lower, at a rate of 5 A/dm ² or higher and 10 A/dm or higher. It can be carried out at a current density of ² or less. Furthermore, when forming a layer made of pure nickel or a nickel alloy as the intermediate layer 4, electrolytic plating is performed using a nickel plating bath with a bath temperature (liquid temperature) of 45°C or higher and 60°C or lower at a rate of 5 A/dm ² or higher and 15 A/dm or higher. It can be carried out at current densities below ^dm2 . In particular, by adjusting the current density in electrolytic plating when forming the silver-containing layer 3, the orientation of silver contained in the silver-containing layer 3 can be controlled. Note that the values of bath temperature and current density in the plating method can also be adjusted in combination as appropriate.

Next, the conductive base material 2 on which at least the silver-containing layer 3 is formed is cold-rolled using a work roll. By cold rolling the conductive base material 2 on which the silver-containing layer 3 is formed under appropriate conditions, the amount of strain in the crystals contained in the silver-containing layer 3 can be increased appropriately. , the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ) described above can be adjusted to a desired magnitude. As a result, the keying performance and wear resistance of the electrical contact surface coating material 1 can be improved. At this time, cold rolling and heat treatment may be performed in an appropriate combination.

The processing rate in cold rolling is preferably in the range of 20% or more and 50% or less. In particular, by setting the processing rate in cold rolling to 20% or more, the amount of strain in the crystals contained in the silver-containing layer 3 increases, and the half-width of the peak originating from the Ag (111) plane increases, for example. Keying performance and abrasion resistance of the electrical contact surface coating material 1 can be improved. Therefore, the processing rate in cold rolling is preferably 20% or more, more preferably 30% or more. On the other hand, if the processing rate in cold rolling is greater than 50%, the amount of crystal strain in the silver-containing layer 3 will be excessive, and for example, the half width of the peak derived from the Ag (111) plane will become larger than necessary. , the bending workability of the surface coating material 1 for electrical contacts is reduced. Therefore, the processing rate in cold rolling is preferably 50% or less, more preferably 40% or less.

Here, "processing rate" (reduction rate) is the value obtained by subtracting the cross-sectional area after rolling from the cross-sectional area before rolling, divided by the cross-sectional area before rolling, multiplied by 100, and expressed as a percentage. It is expressed by the following formula.
[Working rate] = {([Cross-sectional area before rolling] - [Cross-sectional area after rolling]) / [Cross-sectional area before rolling]} x 100 (%)

Further, in cold rolling, the diameter (roll diameter) of the rolling work roll in contact with the conductive base material 2 on which the silver-containing layer 3 is formed is the first total peak intensity (h ₂ ) relative to the second total peak intensity (h 2 ). From the viewpoint of adjusting the ratio (h ₁ /h ₂ ) of ₁ ) to a desired range, it can be set, for example, to a range of 70 mm or more and 90 mm or less. Here, when the diameter of the rolling work roll is small, the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ) tends to be large.

After performing a rolling process such as cold rolling, the conductive base material 2 on which the silver-containing layer 3 is formed may be heat-treated. The orientation of the silver contained in the silver-containing layer 3 can also be controlled by performing a combination of rolling and heat treatment on the conductive base material 2 on which the silver-containing layer 3 is formed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and includes all aspects included in the concept of the present invention and the scope of the claims. It can be modified to .

Next, in order to further clarify the effects of the present invention, examples of the present invention and comparative examples will be described, but the present invention is not limited to these examples of the present invention.

Surface coating materials for electrical contacts of Examples 1 to 57 and Comparative Examples 1 to 54 were produced using any of the production methods A to I shown below. The structures and properties of the prepared samples were evaluated and are shown in Tables 1 to 4 along with the manufacturing conditions.

(Measurement of thickness of silver-containing layer 3 and intermediate layer 4)
Using a cross-section polisher (manufactured by JEOL Ltd.), the obtained electrical contact surface coating materials 1 and 1A are cut in a plane parallel to the rolling direction of the conductive base material 2 and along the thickness direction. Then, the thicknesses of the silver-containing layer 3 and the intermediate layer 4 appearing on the cut surface were measured using a scanning electron microscope (SEM).

(Measurement of silver content in silver-containing layer 3)
Using an electron probe microanalyzer (EPMA), the silver content (mass %) on the surface of the silver-containing layer 3 of the obtained electrical contact surface coating material 1 was measured.

(Method of measuring the ratio of the first total peak intensity to the second total peak intensity)
The surface of the silver-containing layer 3 of the obtained surface coating material 1 for electrical contacts was analyzed using an X-ray diffraction method, and analyzed using an X-ray diffraction device (manufactured by PANalytical, model: X'Pert PRO). From the X-ray diffraction chart of the obtained diffraction angle (2θ) and diffraction peak intensity, the sum of the peak intensity originating from the Ag (111) plane and the peak intensity originating from the plane parallel to the Ag (111) plane is calculated as the first _{The second} total peak intensity ( _2nd total peak intensity ( The ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to h ₂ ) was calculated.

(Method for measuring half width of peak derived from Ag (111) plane)
The surface of the silver-containing layer 3 of the obtained surface coating material 1 for electrical contacts was analyzed using an X-ray diffraction method, and analyzed using an X-ray diffraction device (manufactured by PANalytical, model: X'Pert PRO). From the X-ray diffraction chart of the obtained diffraction angle (2θ) and diffraction peak intensity, the half-value width of the peak intensity derived from the Ag (111) plane was calculated.

(Evaluation of wear resistance against steel balls)
The surface on which the silver-containing layer 3 of the obtained surface coating material 1 for electrical contacts is formed is brought into contact with a steel ball as a mating material, Co., Ltd.), reciprocating sliding was performed 1000 times at the same location at a contact load of 1 N, a sliding distance of 50 mm, and a sliding speed of 100 mm/min. Next, using a laser roughness meter, measure the depth of the sliding portion of the mating material from the reference surface (the surface that is not sliding back and forth), and calculate the depth of the sliding portion relative to the thickness of the silver-containing layer 3. The percentage of Based on the calculated ratio, the wear resistance of steel balls was evaluated according to the following criteria.
◎: The ratio of the depth of the sliding part to the thickness of the silver-containing layer 3 is less than 1/10. ○: The ratio of the depth of the sliding part to the thickness of the silver-containing layer 3 is 1/10 or more and less than 1/5. ×: The ratio of the depth of the sliding part to the thickness of the silver-containing layer 3 is 1/5 or more

(Evaluation of wear resistance for pure silver balls)
The surface on which the silver-containing layer 3 of the obtained surface coating material 1 for electrical contacts is formed is brought into contact with a pure silver ball as a mating material. Co., Ltd.), reciprocating sliding was performed 50 times at the same location at a contact load of 4 N, a sliding distance of 50 mm, and a sliding speed of 100 mm/min. Next, using a laser roughness meter, measure the depth of the sliding portion of the mating material from the reference surface (the surface that is not sliding back and forth), and calculate the depth of the sliding portion relative to the thickness of the silver-containing layer 3. The percentage of Based on the calculated ratio, the wear resistance of steel balls was evaluated according to the following criteria.
◎: The ratio of the depth of the sliding part to the thickness of the silver-containing layer 3 is less than 1/10. ○: The ratio of the depth of the sliding part to the thickness of the silver-containing layer 3 is 1/10 or more and less than 1/5. ×: The ratio of the depth of the sliding part to the thickness of the silver-containing layer 3 is 1/5 or more

(Key typing test)
The obtained surface coating material 1 for electrical contacts was processed into a fixed contact, and on the surface on which the silver-containing layer 3 was formed, a dome-shaped movable contact with a diameter of 4 mm made of a silver-coated stainless steel strip was used as a movable contact, and a key was pressed. The test was conducted. The test conditions were as follows: 1 million keystrokes were performed at a contact pressure of 9.8 N/mm ² and a keystroke speed of 5Hz, and the contact resistance before and after each keystroke was measured at a current of 10 mA. The amount of change in contact resistance value was evaluated based on the following criteria. In addition, if a contact failure occurs and the contact resistance cannot be measured before the number of keystrokes reaches 1 million times, the keystrokes and the measurement of the contact resistance are terminated at that point and evaluated as "x".
◎: The amount of change in contact resistance value is less than 15 mΩ. ○: The amount of change in contact resistance value is 15 mΩ or more and less than 30 mΩ. If it becomes impossible to measure

(Evaluation of bending workability)
The obtained surface coating material 1 for electrical contacts was subjected to a bending test based on the Japan Copper & Brass Association technical standard T307:2007 (method for evaluating bending workability of copper and copper alloy thin plate strips), and the bent portion was examined using an optical microscope. The bending workability of the obtained observation results was evaluated based on the following criteria with reference to the Japan Copper & Brass Association Technical Standard T307:2007. More specifically, the bending workability of the surface coating material 1 for electrical contacts was determined by taking five test pieces with a length of 30 mm and a width of 10 mm from the surface coating material 1 for electrical contacts so that the rolling direction was the longitudinal direction. For each test piece, the ratio of the bending radius to the thickness (R/t) is 1 and the bending angle is 90 degrees. The bending workability was evaluated based on the presence or absence of wrinkles formed on the surface of the electrical contact surface coating material 1.
◎: No cracks or wrinkles occur on all 5 test pieces ○: Wrinkles appear on the surface of one or more test pieces, but no cracks occur on all 5 test pieces ×: 1 or more Cracks occur in the test piece of

(Evaluation of contact resistance value)
The surface on which the silver-containing layer 3 of the obtained surface coating material 1 for electrical contacts is formed was subjected to a current value of 20 mA while applying a load of 1 N using an electrical contact simulator (manufactured by Yamazaki Seiki Laboratory Co., Ltd.). The contact resistance values at ten arbitrary locations were measured, and the average value (n=10) of the obtained measured values was used as the contact resistance value of the metal material for contacts, and evaluated according to the following criteria.
◎: Contact resistance value is less than 0.5 mΩ ○: Contact resistance value is 0.5 mΩ or more and less than 1.0 mΩ ×: Contact resistance value is 1.0 mΩ or more

(Evaluation of heat resistance)
The obtained surface coating material 1 for electrical contacts was heated at 150° C. for 1000 hours in an air atmosphere. After heating, the surface on which the silver-containing layer 3 of the surface coating material 1 for electrical contacts is formed is heated to a current value of 20 mA while applying a load of 1 N using an electrical contact simulator (manufactured by Yamazaki Seiki Laboratory Co., Ltd.). The contact resistance values at ten arbitrary locations were measured, and the average value (n=10) of the obtained measured values was used as the contact resistance value of the contact metal material, and the heat resistance was evaluated according to the following criteria.
◎: Contact resistance value is less than 1.0 mΩ ○: Contact resistance value is 1.0 mΩ or more and less than 5.0 mΩ ×: Contact resistance value is 5.0 mΩ or more

[Invention Examples 1 to 11, 18, 19, Comparative Examples 13 to 18: Production Method A]
As the conductive base material 2, in Examples 1 to 7 of the present invention, C2680, which is a copper alloy (Cu--Zn type) and has the thickness shown in Table 1, was used. Further, in Examples 8 to 11 of the present invention, C5212, which is a copper alloy (Cu-Sn-P system), having the thickness listed in Table 1 was used as the conductive base material 2. In addition, in Inventive Example 18, SUS301, which is an iron alloy (Fe-Cr-Ni system) and has the thickness listed in Table 1, was used as the conductive base material 2. In addition, in Inventive Example 19, SUS304, which is an iron alloy (Fe-Cr-Ni type) and has the thickness listed in Table 1, was used as the conductive base material 2. Furthermore, in Comparative Examples 13 to 18, pure copper C1100 having the thickness listed in Table 2 was used as the conductive base material 2.

As a pretreatment for the conductive base material 2, in Inventive Examples 1 to 11 and Comparative Examples 13 to 18, the conductive base material 2 was subjected to electrolytic degreasing and acid cleaning. Further, as a pretreatment of the conductive substrate 2 in Examples 18 and 19 of the present invention, after removing the oxide film on the surface by performing acid electrolysis after electrolytic degreasing, 500 g/L of nickel sulfate hexahydrate and 30 g of nickel sulfate hexahydrate were added. Nickel strike plating was performed using a nickel plating bath containing /L of nickel chloride and 30g/L of sulfuric acid.

Thereafter, an aqueous solution containing 50 g/L of silver cyanide and 100 g/L of potassium cyanide was prepared as an electrolytic plating solution. Next, 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive substrate 2 after acid washing was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25°C, 10A/ By applying current at a current density of dm ² , a silver-containing layer 3 was formed on the surface of the conductive base material 2 by electrolytic plating. Subsequently, by performing cold rolling at the processing rates shown in Tables 3 and 4 using rolling work rolls having the diameters shown in Tables 3 and 4, the silver-containing layer 3 covering the conductive substrate 2 is formed. Surface coating material 1 for electrical contacts was prepared.

[Invention Examples 12 to 14, Comparative Examples 1 to 6: Production Method B]
As the conductive base material 2, in Examples 12 to 14 of the present invention, pure copper C1100 having the thickness listed in Table 1 was used. Further, in Comparative Examples 1 to 6, C2680, which is a copper alloy (Cu--Zn type), having the thickness shown in Table 2 was used as the conductive base material 2. Electrolytic degreasing and acid cleaning were performed on each conductive base material 2.

Regarding Inventive Example 12 and Comparative Examples 1 and 2, in order to contain zinc (Zn) as a second element in the electrolytic plating solution, 50 g/L of silver cyanide, 100 g/L of potassium cyanide, and 10 g/L of potassium cyanide were used. An aqueous solution containing zinc chloride was prepared. In addition, in Inventive Example 13 and Comparative Examples 3 and 4, in order to contain copper (Cu) as a second element in the electrolytic plating solution, 50 g/L of silver cyanide, 100 g/L of potassium cyanide, and 12 g of potassium cyanide were used. /L of copper chloride dihydrate was prepared. In addition, in Inventive Example 14 and Comparative Examples 5 and 6, in order to contain nickel (Ni) as a second element in the electrolytic plating solution, 50 g/L of silver cyanide, 100 g/L of potassium cyanide, and 12 g of potassium cyanide were used. /L of nickel chloride was prepared.

3L of electrolytic plating solution was put into a cylindrical plating electrolytic tank with an inner diameter of 120 mm, and the conductive base material 2 after acid washing was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25° C., 10 A/dm ² By applying current at a current density of , a silver-containing layer 3 was formed on the surface of the conductive base material 2 by electrolytic plating. Subsequently, by performing cold rolling at the processing rates shown in Tables 3 and 4 using rolling work rolls having the diameters shown in Tables 3 and 4, the silver-containing layer 3 covering the conductive substrate 2 is formed. Surface coating material 1 for electrical contacts was prepared.

[Invention Examples 15 to 17, Comparative Examples 7 to 12: Production Method C]
As the conductive base material 2, in Examples 15 to 17 of the present invention, pure copper C1100 having the thickness listed in Table 1 was used. Further, in Comparative Examples 7 to 12, C2680, which is a copper alloy (Cu--Zn type), having the thickness listed in Table 2 was used as the conductive base material 2. Electrolytic degreasing and acid cleaning were performed on each conductive base material 2.

Regarding Invention Example 15 and Comparative Examples 7 and 8, in order to contain selenium (Se) as a second element, 50 g/L of silver cyanide, 100 g/L of potassium cyanide, and 2.2 mg of electrolytic plating solution were used. /L of potassium selenocyanate was prepared. In addition, in Invention Example 16 and Comparative Examples 9 and 10, in order to contain antimony (Sb) as a second element, 50 g/L of silver cyanide, 100 g/L of potassium cyanide, and 12 g of potassium cyanide were used as the electrolytic plating solution. /L of antimony trichloride was prepared. In addition, in Inventive Example 17 and Comparative Examples 11 and 12, in order to contain cobalt (Co) as a second element, 50 g/L of silver cyanide, 100 g/L of potassium cyanide, and 10 g of potassium cyanide were used as the electrolytic plating solution. /L of cobalt chloride was prepared.

3L of electrolytic plating solution was put into a cylindrical plating electrolytic tank with an inner diameter of 120 mm, and the conductive base material 2 after acid washing was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25° C., 10 A/dm ² By applying current at a current density of , a silver-containing layer 3 was formed on the surface of the conductive base material 2 by electrolytic plating. Subsequently, by performing cold rolling at the processing rates shown in Tables 3 and 4 using rolling work rolls having the diameters shown in Tables 3 and 4, the silver-containing layer 3 covering the conductive substrate 2 is formed. Surface coating material 1 for electrical contacts was prepared.

[Invention Examples 20 to 30, 37, 38, Comparative Examples 31 to 36: Production Method D]
As the conductive base material 2, in Examples 20 to 26 of the present invention, C2680, which is a copper alloy (Cu--Zn type) and has the thickness shown in Table 1, was used. Further, in Examples 27 to 30 of the present invention, C5212, which is a copper alloy (Cu-Sn-P system), having the thickness listed in Table 1 was used as the conductive base material 2. In addition, in Inventive Example 37, SUS301, which is an iron alloy (Fe-Cr-Ni type) and has the thickness listed in Table 1, was used as the conductive base material 2. Further, in Inventive Example 38, pure aluminum A1050 having the thickness listed in Table 1 was used as the conductive base material 2. Furthermore, in Comparative Examples 31 to 36, pure copper C1100 having the thickness listed in Table 2 was used as the conductive base material 2.

In Invention Examples 20 to 30 and Comparative Examples 31 to 36, the conductive substrate 2 was subjected to electrolytic degreasing and acid cleaning as pretreatment for the conductive substrate 2. Further, as a pretreatment of the conductive substrate 2 in Inventive Example 37, after removing the oxide film on the surface by performing acid electrolysis after electrolytic degreasing, 500 g/L of nickel sulfate hexahydrate and 30 g/L of nickel sulfate hexahydrate were added. Nickel strike plating was performed using a nickel plating bath containing 30 g/L of nickel chloride and 30 g/L of sulfuric acid. Furthermore, as a pretreatment for the conductive substrate 2 in Inventive Example 38, alkaline etching was performed using an aqueous solution containing 100 g/L of sodium hydroxide and 10 g/L of sodium gluconate.

Thereafter, as an electrolytic plating solution for forming the intermediate layer 4, an aqueous solution containing 23 g/L of copper cyanide, 34 g/L of sodium cyanide, and 15 g/L of sodium carbonate was prepared. 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 after acid washing was immersed in the resulting copper plating bath, and at a bath temperature of 40°C, 5A/dm ² was applied. By applying electricity at a current density, an intermediate layer 4 made of pure copper was formed on the surface of the conductive base material 2 by electrolytic plating.

Next, as an electrolytic plating solution for forming the silver-containing layer 3, an aqueous solution containing 50 g/L of silver cyanide and 100 g/L of potassium cyanide was prepared. 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 having the intermediate layer 4 was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25° C., the conductive substrate 2 was heated at 10 A/d. By applying current at a current density of ² , the silver-containing layer 3 was formed on the surface of the intermediate layer 4 by electrolytic plating. Subsequently, cold rolling is performed using rolling work rolls having diameters shown in Tables 3 and 4 at processing rates shown in Tables 3 and 4, thereby forming a silver-containing material that coats the surface of the conductive substrate 2. A surface coating material 1A for electrical contacts was prepared, which was provided with layer 3 and further provided with intermediate layer 4 between conductive base material 2 and silver-containing layer 3.

[Invention Examples 31 to 33, Comparative Examples 19 to 24: Production Method E]
In Examples 31 to 33 of the present invention, pure copper C1100 having the thickness listed in Table 1 was used as the conductive base material 2. Furthermore, in Comparative Examples 19 to 24, C2680, which is a copper alloy (Cu--Zn type), having the thickness listed in Table 2 was used as the conductive base material 2.

After performing electrolytic degreasing and acid cleaning on the conductive base material 2, 23 g/L of copper cyanide, 34 g/L of sodium cyanide, and 15 g/L were used as an electrolytic plating solution for forming the intermediate layer 4. An aqueous solution containing sodium carbonate was prepared. 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 after acid washing was immersed in the resulting copper plating bath, and at a bath temperature of 40°C, 5A/dm ² was applied. By applying electricity at a current density, an intermediate layer 4 made of pure copper was formed on the surface of the conductive base material 2 by electrolytic plating.

Next, for Invention Example 31 and Comparative Examples 19 and 20, 50 g/L was used as the electrolytic plating solution for forming the silver-containing layer 3 in order to include zinc (Zn) as a second element in the silver-containing layer 3. An aqueous solution containing silver cyanide, 100 g/L potassium cyanide, and 10 g/L zinc chloride was prepared. In addition, in Inventive Example 32 and Comparative Examples 21 and 22, the electrolytic plating solution for forming the silver-containing layer 3 contained copper (Cu) as a second element in the silver-containing layer 3 at 50 g/L. An aqueous solution containing silver cyanide, 100 g/L potassium cyanide, and 12 g/L copper chloride dihydrate was prepared. In addition, in Inventive Example 33 and Comparative Examples 23 and 24, the electrolytic plating solution for forming the silver-containing layer 3 contained nickel (Ni) as a second element in the silver-containing layer 3, so that 50 g/L was used. An aqueous solution containing silver cyanide of 100 g/L, potassium cyanide of 100 g/L, and nickel chloride of 12 g/L was prepared.

3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 having the intermediate layer 4 was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25° C., the conductive substrate 2 was heated at 10 A/d. By applying current at a current density of ² , the silver-containing layer 3 was formed on the surface of the intermediate layer 4 by electrolytic plating. Subsequently, cold rolling is performed using rolling work rolls having diameters shown in Tables 3 and 4 at processing rates shown in Tables 3 and 4, thereby forming a silver-containing material that coats the surface of the conductive substrate 2. A surface coating material 1A for electrical contacts was prepared, which was provided with layer 3 and further provided with intermediate layer 4 between conductive base material 2 and silver-containing layer 3.

[Invention Examples 34 to 36, Comparative Examples 25 to 30: Production Method F]
As the conductive base material 2, in Examples 34 to 36 of the present invention, pure copper C1100 having the thickness listed in Table 1 was used. Furthermore, in Comparative Examples 25 to 30, C2680, which is a copper alloy (Cu--Zn type), having the thickness listed in Table 2 was used as the conductive base material 2.

After performing electrolytic degreasing and acid cleaning on the conductive base material 2, 23 g/L of copper cyanide, 34 g/L of sodium cyanide, and 15 g/L were used as an electrolytic plating solution for forming the intermediate layer 4. An aqueous solution containing sodium carbonate was prepared. 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 after acid washing was immersed in the resulting copper plating bath, and at a bath temperature of 40°C, 5A/dm ² was applied. By applying electricity at a current density, an intermediate layer 4 made of pure copper was formed on the surface of the conductive base material 2 by electrolytic plating.

Next, in Invention Example 34 and Comparative Examples 25 and 26, 50 g/L was used as the electrolytic plating solution for forming the silver-containing layer 3 in order to include selenium (Se) as a second element in the silver-containing layer 3. An aqueous solution containing silver cyanide of 100 g/L, potassium cyanide of 100 g/L, and potassium selenocyanate of 2.2 mg/L was prepared. In addition, in Inventive Example 35 and Comparative Examples 27 and 28, the electrolytic plating solution for forming the silver-containing layer 3 contained antimony (Sb) as a second element in the silver-containing layer 3 at 50 g/L. An aqueous solution containing silver cyanide of 100 g/L, potassium cyanide of 100 g/L, and antimony trichloride of 12 g/L was prepared. In addition, in Inventive Example 36 and Comparative Examples 29 and 30, the electrolytic plating solution for forming the silver-containing layer 3 contained cobalt (Co) as a second element in the silver-containing layer 3 at 50 g/L. An aqueous solution containing silver cyanide, 100 g/L potassium cyanide, and 10 g/L cobalt chloride was prepared.

3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 having the intermediate layer 4 was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25° C., the conductive substrate 2 was heated at 10 A/d. By applying current at a current density of ² , the silver-containing layer 3 was formed on the surface of the intermediate layer 4 by electrolytic plating. Subsequently, cold rolling is performed using rolling work rolls having diameters shown in Tables 3 and 4 at processing rates shown in Tables 3 and 4, thereby forming a silver-containing material that coats the surface of the conductive substrate 2. A surface coating material 1A for electrical contacts was prepared, which was provided with layer 3 and further provided with intermediate layer 4 between conductive base material 2 and silver-containing layer 3.

[Invention Examples 39-49, 56, 57, Comparative Examples 49-54: Production Method G]
As the conductive base material 2, in Examples 39 to 45 of the present invention, C2680, which is a copper alloy (Cu--Zn type) and has the thickness shown in Table 1, was used. Further, in Examples 46 to 49 of the present invention, C5212, which is a copper alloy (Cu-Sn-P system), having the thickness listed in Table 1 was used as the conductive base material 2. Further, in Inventive Example 56, SUS301, which is an iron alloy (Fe-Cr-Ni system), having the thickness listed in Table 1 was used as the conductive base material 2. Furthermore, in Inventive Example 57, pure aluminum A1050 having the thickness listed in Table 1 was used as the conductive base material 2. Furthermore, in Comparative Examples 49 to 54, pure copper C1100 having the thickness listed in Table 2 was used as the conductive base material 2.

In Inventive Examples 39 to 49 and Comparative Examples 49 to 54, the conductive substrate 2 was subjected to electrolytic degreasing and acid cleaning as pretreatment for the conductive substrate 2. Further, as a pretreatment of the conductive substrate 2 in Invention Example 56, after removing the oxide film on the surface by performing acid electrolysis after electrolytic degreasing, 500 g/L of nickel sulfate hexahydrate and 30 g/L of nickel sulfate hexahydrate were added. Nickel strike plating was performed using a nickel plating bath containing 30 g/L of nickel chloride and 30 g/L of sulfuric acid. Furthermore, as a pretreatment for the conductive substrate 2 in Inventive Example 57, alkaline etching was performed using an aqueous solution containing 100 g/L of sodium hydroxide and 10 g/L of sodium gluconate.

Thereafter, as an electrolytic plating solution for forming the intermediate layer 4, an aqueous solution containing 500 g/L of nickel sulfate hexahydrate, 30 g/L of nickel chloride, and 30 g/L of sulfuric acid was prepared. 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 after acid washing was immersed in the resulting nickel plating bath, and at a bath temperature of 55°C, a plating solution of 15 A/dm ² was applied. By applying electricity at a current density, an intermediate layer 4 made of pure nickel was formed on the surface of the conductive base material 2 by electrolytic plating.

Next, as an electrolytic plating solution for forming the silver-containing layer 3, an aqueous solution containing 50 g/L of silver cyanide and 100 g/L of potassium cyanide was prepared. 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 having the intermediate layer 4 was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25° C., the conductive substrate 2 was heated at 10 A/d. By applying current at a current density of ² , the silver-containing layer 3 was formed on the surface of the intermediate layer 4 by electrolytic plating. Subsequently, cold rolling is performed using rolling work rolls having diameters shown in Tables 3 and 4 at processing rates shown in Tables 3 and 4, thereby forming a silver-containing material that coats the surface of the conductive substrate 2. A surface coating material 1A for electrical contacts was prepared, which was provided with layer 3 and further provided with intermediate layer 4 between conductive base material 2 and silver-containing layer 3.

[Invention Examples 50 to 52, Comparative Examples 37 to 42: Production Method H]
As the conductive base material 2, in Examples 50 to 52 of the present invention, pure copper C1100 having the thickness listed in Table 1 was used. Furthermore, in Comparative Examples 37 to 42, C2680, which is a copper alloy (Cu--Zn type), having the thickness listed in Table 2 was used as the conductive base material 2.

After performing electrolytic degreasing and acid cleaning on the conductive base material 2, 500 g/L of nickel sulfate hexahydrate, 30 g/L of nickel chloride, and 30 g of electrolytic plating solution for forming the intermediate layer 4 were applied. /L of sulfuric acid was prepared. 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 after acid washing was immersed in the resulting nickel plating bath, and at a bath temperature of 55°C, a plating solution of 15 A/dm ² was applied. By applying electricity at a current density, an intermediate layer 4 made of pure nickel was formed on the surface of the conductive base material 2 by electrolytic plating.

Next, in Invention Example 50 and Comparative Examples 37 and 38, the electrolytic plating solution for forming the silver-containing layer 3 was 50 g/L in order to include zinc (Zn) as a second element in the silver-containing layer 3. An aqueous solution containing silver cyanide, 100 g/L potassium cyanide, and 10 g/L zinc chloride was prepared. In addition, in Inventive Example 51 and Comparative Examples 39 and 40, the electrolytic plating solution for forming the silver-containing layer 3 contained copper (Cu) as a second element in the silver-containing layer 3 at 50 g/L. An aqueous solution containing silver cyanide, 100 g/L potassium cyanide, and 12 g/L copper chloride dihydrate was prepared. In addition, in Inventive Example 52 and Comparative Examples 41 and 42, the electrolytic plating solution for forming the silver-containing layer 3 contained nickel (Ni) as a second element in the silver-containing layer 3, so that 50 g/L was used. An aqueous solution containing silver cyanide of 100 g/L, potassium cyanide of 100 g/L, and nickel chloride of 12 g/L was prepared.

3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 having the intermediate layer 4 was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25° C., the conductive substrate 2 was heated at 10 A/d. By applying current at a current density of ² , the silver-containing layer 3 was formed on the surface of the intermediate layer 4 by electrolytic plating. Subsequently, cold rolling is performed using rolling work rolls having diameters shown in Tables 3 and 4 at processing rates shown in Tables 3 and 4, thereby forming a silver-containing material that coats the surface of the conductive substrate 2. A surface coating material 1A for electrical contacts was prepared, which was provided with layer 3 and further provided with intermediate layer 4 between conductive base material 2 and silver-containing layer 3.

[Invention Examples 53 to 55, Comparative Examples 43 to 48: Production Method I]
As the conductive base material 2, in Examples 53 to 55 of the present invention, pure copper C1100 having the thickness listed in Table 1 was used. Further, in Comparative Examples 43 to 48, C2680, which is a copper alloy (Cu--Zn type), having the thickness listed in Table 2 was used as the conductive base material 2. Electrolytic degreasing and acid cleaning were performed on each conductive base material 2.

After performing electrolytic degreasing and acid cleaning on the conductive base material 2, 500 g/L of nickel sulfate hexahydrate, 30 g/L of nickel chloride, and 30 g of electrolytic plating solution for forming the intermediate layer 4 were applied. /L of sulfuric acid was prepared. 3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 after acid washing was immersed in the resulting nickel plating bath, and at a bath temperature of 55°C, a plating solution of 15 A/dm ² was applied. By applying electricity at a current density, an intermediate layer 4 made of pure nickel was formed on the surface of the conductive base material 2 by electrolytic plating.

Next, for Inventive Example 53 and Comparative Examples 43 and 44, 50 g/L was used as the electrolytic plating solution for forming the silver-containing layer 3 in order to include selenium (Se) as a second element in the silver-containing layer 3. An aqueous solution containing silver cyanide, 100 g/L potassium cyanide, and 2.2 mg/L potassium selenocyanate was prepared. In addition, in Inventive Example 54 and Comparative Examples 45 and 46, antimony (Sb) was included as a second element in the silver-containing layer 3 as an electrolytic plating solution for forming the silver-containing layer 3, so that 50 g/L was used. An aqueous solution containing silver cyanide of 100 g/L, potassium cyanide of 100 g/L, and antimony trichloride of 12 g/L was prepared. In addition, in Inventive Example 55 and Comparative Examples 47 and 48, the electrolytic plating solution for forming the silver-containing layer 3 contained cobalt (Co) as a second element in the silver-containing layer 3 at 50 g/L. An aqueous solution containing silver cyanide, 100 g/L potassium cyanide, and 10 g/L cobalt chloride was prepared.

3L of electrolytic plating solution was put into a cylindrical plating electrolytic bath with an inner diameter of 120 mm, and the conductive base material 2 having the intermediate layer 4 was immersed in the resulting alkaline cyan silver bath, and at a bath temperature of 25° C., the conductive substrate 2 was heated at 10 A/d. By applying current at a current density of ² , the silver-containing layer 3 was formed on the surface of the intermediate layer 4 by electrolytic plating. Subsequently, cold rolling is performed using rolling work rolls having diameters shown in Tables 3 and 4 at processing rates shown in Tables 3 and 4, thereby forming a silver-containing material that coats the surface of the conductive substrate 2. A surface coating material 1A for electrical contacts was prepared, which was provided with layer 3 and further provided with intermediate layer 4 between conductive base material 2 and silver-containing layer 3.

As can be seen from Tables 1 to 4 above, the surface coating materials for electrical contacts obtained in Examples 1 to 57 of the present invention have a ratio of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ). When (h ₁ /h ₂ ) is in the range of 1.0 or more and 3.0 or less, the bending workability is evaluated as “◎” or “○”, and the silver content when silver is used as the counterpart material. The abrasion resistance of the layer was also evaluated as "◎" or "○". Furthermore, the surface coating materials for electrical contacts of Examples 1 to 57 of the present invention were evaluated as "◎" or "○" in the keystroke test results. In addition, the surface coating materials for electrical contacts of Examples 1 to 57 of the present invention have low contact resistance of the silver-containing layer and are evaluated as "◎" or "○", and the contact resistance of the silver-containing layer after heating is low. The resistance was also low, and the heat resistance was rated as "◎" or "○".

Therefore, the surface coating materials for electrical contacts obtained in Examples 1 to 57 of the present invention had excellent bending workability and also had high wear resistance of the silver-containing layer.

On the other hand, the surface coating materials for electrical contacts obtained in Comparative Examples 1 to 54 have a ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ). The range of 1.0 to 3.0 was not satisfied, and at least one of the bending workability and the wear resistance of the silver-containing layer when silver was used as a counterpart material was evaluated as "x". .

In particular, in comparative examples (Comparative Examples 1, 3, 5, etc.) where the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ) was 4.0. In the obtained surface coating material for electrical contacts, at least the abrasion resistance of the silver-containing layer when using silver as a mating material was evaluated as "x", and the result of the keying test was also evaluated as "x". Ta.

Furthermore, in comparative examples (Comparative Examples 2, 4, 6, etc.) where the ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to the second total peak intensity (h ₂ ) was 0.5, The obtained surface covering material for electrical contacts was evaluated as "poor" at least in terms of bending workability.

Further, among the present invention examples, the half width of the peak derived from the Ag (111) plane was 0.15° or more (present invention examples 1 to 14, 16, 18 to 33, 35, 37 to 52, 54, 56), the abrasion resistance of the silver-containing layer when silver was used as the counterpart material and the results of the keystroke test were evaluated as "◎". The surface coating materials for electrical contacts obtained in the examples in which the half width of the peak derived from the Ag (111) plane was less than 0.15° (Invention Examples 15, 17, 34, 36, 53, 55) were as follows: The abrasion resistance of the silver-containing layer when using silver as a mating material and the results of the keystroke test were rated as "○".

Furthermore, among the present invention examples, examples in which the half width of the peak derived from the Ag (111) plane was 0.30° or less (present invention examples 1 to 13, 15, 17 to 32, 34, 36 to 51, Although the surface coating material for electrical contacts obtained in 53, 55) was evaluated as "◎" in bending workability, the half width of the peak derived from the Ag (111) plane was 0.30°. The surface covering materials for electrical contacts obtained in the examples (inventive examples 14, 16, 33, 35, 52, and 54) that exceeded the standard were evaluated as "Good" in bending workability.

In addition, among the examples of the present invention, the electrical contacts obtained in the examples in which the content of the silver-containing layer was 99% by mass or more (Examples 1 to 11, 18 to 30, 37 to 49, 56, 57) The surface coating material was evaluated as "◎" for the contact resistance value, but the silver-containing layer content was less than 99% by mass (invention examples 12 to 17, 31 to 36, 50 to The surface coating material for electrical contacts obtained in 55) was evaluated as "Good" in terms of contact resistance value.

Further, among the present invention examples, the surface coating materials for electrical contacts obtained in the examples (present invention examples 20 to 57) in which the intermediate layer 4 was provided between the conductive base material 2 and the silver-containing layer 3 had heat resistance. In contrast, the surfaces for electrical contacts obtained in the examples (inventive examples 1 to 19) that did not have the intermediate layer 4 between the conductive base material 2 and the silver-containing layer 3 The coating material was rated "Good" in terms of heat resistance.

1, 1A Surface coating material for electrical contacts 2 Conductive base material 3 Silver-containing layer 4 Intermediate layer

Claims (9)

a conductive base material;
A surface coating material for electrical contacts, comprising a silver-containing layer covering at least one side of the conductive base material,
The silver-containing layer is
The first total peak intensity, which is the sum of the peak intensity derived from the Ag (111) plane and the peak intensity derived from the plane parallel to the Ag (111) plane, obtained from the X-ray diffraction chart, is defined as _h1 . With,
When the second total peak intensity, which is the total value of the remaining peak intensities after subtracting the first total peak intensity (h ₁ ) from the total value of all detected peak intensities, is h ₂ ,
A ratio (h ₁ /h ₂ ) of the first total peak intensity (h ₁ ) to _the second total peak intensity (h 2 ) is in a range of 1.0 or more and 3.0 or less, Surface coating material for electrical contacts. The surface coating material for electrical contacts according to claim 1, wherein the silver-containing layer has a peak width at half maximum derived from the Ag (111) plane in a range of 0.15° or more and 0.30° or less. The surface coating material for electrical contacts according to claim 1, wherein the silver-containing layer contains 99% by mass or more of silver. The surface coating material for electrical contacts according to claim 1, wherein the conductive base material is made of pure copper, copper alloy, pure iron, iron alloy, pure aluminum, or aluminum alloy. The surface coating material for electrical contacts according to claim 1, further comprising at least one intermediate layer made of pure copper, copper alloy, pure nickel, or nickel alloy between the conductive base material and the silver-containing layer. The surface coating material for electrical contacts according to claim 1, wherein the conductive base material has a thickness in a range of 0.03 mm or more and 0.30 mm or less. An electrical contact produced using the surface coating material for electrical contacts according to any one of claims 1 to 6. A switch having the electrical contact according to claim 7. A connector terminal having the electrical contact according to claim 7.

Images