JP7281971B2 - Electrical contact material and its manufacturing method, connector terminal, connector and electronic component - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrical contact material and its manufacturing method, a connector terminal, a connector and an electronic component.

Electronic parts for consumer and vehicle use, for example, connector terminals that constitute electrical contact parts of connectors, contain copper (Cu) as a main component, such as brass, phosphor bronze, and Corson alloy, on the surface of a conductive base material. Electrical contact materials are used which are plated with nickel (Ni) or copper (Cu) and then plated with tin (Sn) or Sn alloy.

In recent years, the electrification of vehicle drive systems has progressed in order to achieve fuel efficiency. For example, the connection parts between batteries, inverters, and motors are required to withstand high voltages and large currents. Examples of using silver (Ag) or Ag alloy plating in place of plating are increasing.

On the other hand, in such applications, for the purpose of improving the ease of assembly of vehicles, the conventional bolt-tightening connections are being replaced by mating-type connectors. Therefore, the plating formed on the surface of the connector, particularly the connector terminal, is required to have a low contact resistance value and a low insertion force when the connector is fitted (connected). However, Ag plating has good compatibility with metals and tends to cause agglomeration, which tends to increase the coefficient of dynamic friction and increase the insertion force.

For example, in Patent Document 1, a Ni layer (lower layer), an Ag layer (middle layer), an ε-Ag ₃ Sn layer (upper layer) and a Sn layer (outermost layer) are formed on a copper alloy base material to obtain a low whisker property. , a metallic material for electronic components having low adhesion wear and high durability is disclosed.

JP 2014-29007 A

However, the metal material for electronic parts described in Patent Document 1 has an Sn layer as the outermost layer and has a higher contact resistance value than the Ag layer. is not applicable.

The present invention has been made in view of the above circumstances. To provide an electrical contact material that has a low contact resistance value with a sufficient resistance level even when a high voltage and large current is applied, and a low dynamic friction coefficient, a method for manufacturing the same, a connector terminal, a connector, and an electronic component. intended to

In order to achieve the above-described object, the present inventors have made intensive studies and found that the electrical contact material contains nickel (Ni) on at least one side of a conductive substrate containing copper (Cu) as a main component. and a surface layer containing silver (Ag) and tin (Sn) as main components. The ratio of the area of the X-ray intensity of the peak appearing in the range of 2θ = 39.7 to 40.3° to the total area of the X-ray intensity of all the peaks appearing in the range of 41° is 50% or more, It is possible to provide an electrical contact material that has a low contact resistance value with a sufficient resistance level even when a high voltage and large current is applied, and also has a low dynamic friction coefficient, and such an electrical contact material is Cu A base layer containing Ni as a main component is laminated on at least one side of a conductive substrate containing as a main component, and then a layer containing Ag as a main component and Sn as a main component are laminated on the base layer. Lamination of layers containing as in random order, or lamination of layers containing Ag and Sn as main components, and then heat treatment at a heating temperature of 231 to 900 ° C. I have completed my invention.

That is, the gist and configuration of the present invention are as follows.
(1) A base layer containing nickel (Ni) as a main component and silver (Ag) and tin (Sn) as main components on at least one side of a conductive substrate containing copper (Cu) as a main component. When the surface layer is laminated in this order and the surface layer is measured by the X-ray diffraction method, the total area of the X-ray intensities of all peaks appearing in the range of 2θ = 38 to 41 ° is 2θ = 39.7 to An electrical contact material, wherein the ratio of the area of the peak X-ray intensity appearing in the range of 40.3° is 50% or more.
(2) The electrical contact material according to (1) above, wherein a NiSn-based compound is present between the underlying layer and the surface layer.
(3) The surface layer has a large number of granular precipitates, and the average particle size of the granular precipitates present on the surface of the surface layer is in the range of 0.01 to 10 μm. ) or the electrical contact material according to (2).
(4) A connector terminal using the electrical contact material according to any one of (1) to (3) above.
(5) A connector having the connector terminal according to (4) above.
(6) An electronic component having the connector according to (5) above.
(7) A method for producing an electrical contact material according to any one of the above (1) to (3), wherein a An underlayer containing A method for producing an electrical contact material, comprising laminating a layer containing as and then heat-treating at a heating temperature of 231 to 900°C.

According to the present invention, even when a high voltage and large current is applied, it has a low contact resistance value with a sufficient resistance level, a low coefficient of dynamic friction, and furthermore, lamination of each layer on a copper alloy substrate It is possible to provide an electrical contact material, a method for producing the same, a connector terminal, a connector, and an electronic component that are also excellent in heat-resistant adhesion after heating in heat treatment that is performed after formation.

BRIEF DESCRIPTION OF THE DRAWINGS It is a cross-sectional schematic diagram of the material for electrical contacts of this invention. It is a modification of the cross-sectional schematic diagram of the material for electrical contacts of this invention. It is an example of the X-ray diffraction pattern of the surface layer of the material for electrical contacts of the present invention. It is an example of a SEM photograph of the surface layer (the surface of) of the electrical contact material of the present invention. It is an example of the SEM photograph of the surface of the electrical contact material formed by the conventional plating.

Preferred embodiments of the present invention will be described in detail below, but the present invention is not limited to the following embodiments.

In the present invention, "containing M as a main component" (where M is one type of metal element) means that the content of the metal element M in the total metal elements contained in the substrate or each layer is 50 at% or more. It means that

1. Electrical contact material The electrical contact material of the present invention comprises a conductive base material containing copper (Cu) as a main component, a base layer containing nickel (Ni) as a main component, silver (Ag) and A surface layer containing tin (Sn) as a main component is laminated in this order, and when the surface layer is measured by X-ray diffraction, the total area of X-ray intensities of all peaks appearing in the range of 2θ = 38 to 41 ° The ratio of the area of the X-ray intensity of the peak appearing in the range of 2θ=39.7 to 40.3° is 50% or more.

FIG. 1 schematically shows a cross section of an electrical contact material of one embodiment. The electrical contact material 1A shown in FIG. and a surface layer 13 containing tin (Sn) as a main component are laminated in this order, and when the surface layer 13 is measured by an X-ray diffraction method, X-rays of all peaks appearing in the range of 2θ = 38 to 41 ° The ratio of the area of the X-ray intensity of the peak appearing in the range of 2θ=39.7 to 40.3° to the total area of intensity is 50% or more.

Each part of the electrical contact material of the present invention will be described in detail below.

(Conductive substrate)
The conductive base material 11 contains copper as a main component.

Specifically, the conductive substrate 11 is made of a copper-based material such as (pure) copper or a copper alloy. The copper alloy is not particularly limited, but for example Cu--Zn system, Cu--Ni--Si system, Cu--Sn--Ni system, Cu--Cr--Mg system, Cu--Ni--Si--Zn--Sn--Mg system, etc. is mentioned.

The shape of the conductive base material 11 is not particularly limited, and may be appropriately selected according to the application.

The conductivity of the conductive base material 11 is not particularly limited, but is preferably 20%IACS or higher, more preferably 40%IACS or higher. As a result, the conductive material as a whole can have excellent conductivity. Here, the conductivity (IACS: International Annealed Copper Standard) can be obtained by measuring in a constant temperature bath controlled at 20° C. (±1° C.) using a four-probe method.

(Underlayer)
The underlayer 12 contains nickel (Ni) as a main component. This base layer can prevent deterioration of conductivity of the electrical contact material 1A caused by diffusion of Cu in the conductive base material 11 to the surface layer 13, which will be described later.

Specifically, the underlying layer 12 is made of a nickel-based material such as metallic nickel or a nickel alloy. Examples of the nickel alloy include, but are not particularly limited to, Ni--P system, Ni--Fe system, and the like.

Although the thickness of the underlayer 12 is not particularly limited, it is preferably 0.1 to 3.0 μm, more preferably 0.3 to 2.0 μm. A method for calculating the thickness of the underlying layer will be described later.

It should be noted that even if a cobalt (Co)-containing layer or an iron (Fe)-containing layer is used for the underlying layer 12 instead of the Ni-containing layer made of a nickel-based material, the same effect as the Ni-containing layer can be obtained. .

(surface)
The surface layer 13 contains silver (Ag) and tin (Sn) as main components. Note that "containing silver (Ag) and tin (Sn) as main components" means that the content of silver in the total metal elements contained in the surface layer 13 is 40 at% or more and the content of tin is 10 at%. It means that the total content of silver and tin is 50 atomic % or more.

Such a surface layer 13 has a value of 2θ=39.7 to 40.3° with respect to the total area of X-ray intensities of all peaks appearing in the range of 2θ=38 to 41° when measured by an X-ray diffraction method. The area ratio of the X-ray intensity of the peak appearing in the range is 50% or more.

FIG. 2 is an example of an X-ray diffraction pattern of the surface layer (surface of) of the electrical contact material of this embodiment. Among compounds containing silver (Ag) and tin (Sn) as main components, the compound showing a peak in the range of 2θ=39.7 to 40.3° is ζ-AgSn. On the other hand, peaks of other compounds such as Ag ₃ Sn (ε-AgSn) also appear in the range of 2θ=38 to 41°. Therefore, when the surface layer 13 is measured by the X-ray diffraction method, it appears in the range of 2θ = 39.7 to 40.3° with respect to the total area of the X-ray intensities of all the peaks that appear in the range of 2θ = 38 to 41°. The fact that the area ratio of the peak X-ray intensity is 50% or more means that the surface layer 13 has a ζ-AgSn phase of a specific amount or more. Here, ζ-AgSn is an intermetallic compound of Ag and Sn having an atomic number ratio of Sn to Ag (Sn/Ag) in the range of 0.13 to 0.30 and having Ag ₄ Sn as a main component. means the phase of Since .zeta.-AgSn has a high hardness, the dynamic friction coefficient can be reduced by forming the surface of the surface layer 13 with .zeta.-AgSn. In addition, since ζ-AgSn has excellent conductivity, it can also reduce the contact resistance. Furthermore, even if ζ-AgSn is heated, the Ni present in the underlying layer is difficult to diffuse into its interior, so the Ni diffuses to the surface of the surface layer, and the decrease in conductivity caused by oxidation due to contact with the outside air is prevented. can be suppressed.

The ratio of the area of the X-ray intensity of the peak appearing in the range of 2θ = 39.7 to 40.3° to the total area of the X-ray intensity of all the peaks appearing in the range of 2θ = 38 to 41° is 50%. Although it is not particularly limited as long as it is at least 60%, it is preferably 60% or more, more preferably 70% or more, and even more preferably 75% or more.

Further, in the surface layer 13, the atomic number ratio of Sn to Ag (Sn/Ag) of the compound showing a peak in the range of 2θ=39.7 to 40.3° is not particularly limited, but is 0.15 to 0.15. 28 is preferred, 0.20 to 0.27 is more preferred, 0.22 to 0.26 is even more preferred, and 0.245 to 0.255 is particularly preferred.

In one embodiment, the compound showing a peak in the range of 2θ=39.7 to 40.3° is preferably Ag ₄ Sn. As the content of Ag ₄ Sn increases, it exhibits lower contact resistance and dynamic friction coefficient, and is useful as an electrical contact material.

The thickness of the surface layer 13 is not particularly limited. is more preferred. When the surface layer 13 has such a thickness, the surface layer 13 has more excellent conductivity and exhibits excellent bending workability.

The surface layer 13 has a large number of granular precipitates, and the average particle size of the granular precipitates existing on the surface of the surface layer 13 is preferably in the range of 0.01 to 10 μm. As a result, the electrical contact material 1A exhibits a low coefficient of dynamic friction and excellent bending workability. In addition, when "a large number of granular precipitates" are observed with a scanning electron microscope, an image as shown in FIG. 4, for example, is obtained. FIG. 4 shows an example of a SEM photograph of the surface layer (surface) of the electrical contact material of the present invention. On the other hand, FIG. 5 is an example of a scanning electron micrograph of the surface of an electrical contact material formed by conventional plating. Thus, the granular deposits are different from plating formed by normal plating. The average particle size of the granular precipitates can be obtained by observing the surface of the sample with a scanning electron microscope and using the intercept method. Specifically, a rectangular visual field range is set so that 20 or more (400 or more in total) granular precipitates are included in each of the vertical and horizontal sides, and a diagonal line is drawn in this state. The average grain size of the granular precipitates is calculated by measuring the number of precipitates and dividing the diagonal length by the measured number of granular precipitates.

(NiSn-based compound)
Moreover, FIG. 2 schematically shows a cross section of an electrical contact material of another embodiment. The electrical contact material 1B may have a NiSn compound 14 between the underlayer 12 and the surface layer 13, as shown in FIG. By forming such a NiSn-based compound 14 between the underlying layer 12 and the surface layer 13, Ni existing in the underlying layer 12 is more likely to be absorbed into the surface layer 12 even when subjected to heating in the usage environment than when it is not formed. 13 can be prevented. Although FIG. 2 shows an example in which the NiSn-based compound 14 is partially substituted by the underlying layer 12 , the NiSn-based compound 14 is not limited to such a form, and the surface layer 13 , or a layer may be formed between the underlying layer 12 and the surface layer 13 .

Specifically, the NiSn-based compound 14 is not _particularly limited as long as _{it is} an intermetallic compound composed of Ni _{and Sn} . you can

The NiSn-based compound is preferably present in an amount of 0.1 at % or more with respect to all metal elements forming the underlying layer 12 and the surface layer 13 . The NiSn-based compound 14 can be confirmed using cross-sectional X-ray photoelectron spectroscopy (XPS), SEM-EDX analysis, or both. Specifically, it is possible to determine and quantitatively evaluate Ni ₃ Sn, Ni ₃ Sn ₂ and Ni ₃ Sn ₄ from the bonding state of Ni and Sn by XPS. In addition, particles or layers containing Ni and Sn can be detected by SEM-EDX component analysis of the cross section.

The electrical contact materials 1A and 1B constructed as described above have a low contact resistance value with a sufficient resistance level and a low coefficient of dynamic friction even when a high voltage and a large current are applied. Such an electrical contact material can be used for connector terminals. Since such a connector terminal has a low coefficient of dynamic friction on the surface and a low insertion force, it can be used as a connector for improving assembly of vehicles and the like. Furthermore, such a connector can be used for various electronic components. In addition, in the present invention, each layer laminated on the conductive substrate may be formed on at least one side of the conductive substrate. For example, each layer laminated on a conductive base material may be formed in an electrical contact portion that is electrically connected by sliding contact with a terminal of a mating connector when the connector is connected (fitted). Often, it can be formed on one or both sides of the conductive substrate.

2. Method for producing an electrical contact material The method for producing an electrical contact material of the present invention is a method for producing the above-described electrical contact material, wherein Ni is laminated as a main component, and then a layer containing Ag as a main component and a layer containing Sn as a main component are laminated in random order on the base layer, or Ag and It is characterized in that layers containing Sn as a main component are laminated and then heat-treated at a heating temperature of 231 to 900.degree.

More specifically, the method for producing the electrical contact material will be described. First, a base layer containing Ni as a main component is laminated on a conductive base material by plating. After that, a layer containing Ag as a main component and a layer containing Sn as a main component are laminated in random order on the underlying layer by plating (that is, after forming a layer containing Ag as a main component, Sn is formed). Forming a layer containing Sn as a main component, or forming a layer containing Sn as a main component and then forming a layer containing Ag as a main component), or containing Ag and Sn as main components A layer (for example, Ag—Sn eutectoid layer) is laminated. Then, heat treatment is performed at 231°C (the melting point of Sn) to 900°C. After that, it is cooled to obtain an electrical contact material. During the heat treatment, the Sn in the layer containing Sn as a main component and the Ag in the layer containing Ag as a main component formed by plating diffuse into each other, so that Ag and Sn as a main component are diffused into each other. and appears in the range of 2θ = 39.7 to 40.3 ° with respect to the total area of the X-ray intensity of all the peaks appearing in the range of 2θ = 38 to 41 ° when measured by the X-ray diffraction method A surface layer having an area ratio of peak X-ray intensity of 50% or more is obtained.

The plating method for forming each layer is not particularly limited, but wet plating such as electrolytic plating and electroless plating, dry plating such as vapor deposition and sputtering, and the like can be used. Among these, wet plating is preferably used, and electrolytic plating is more preferably used. At this time, the plating conditions may be appropriately adjusted according to the plating method, the type and thickness of the plating layer, the temperature and holding time of the subsequent heat treatment, and the like.

When the layer containing Ag as a main component and the layer containing Sn as a main component are formed as different layers, the thickness of the layer containing Ag as a main component is larger than the thickness of the layer containing Sn as a main component. (Ag/Sn ratio) is preferably 2.1 to 7.0, more preferably 2.8 to 5.0. When such a ratio is 2.1 to 7.0, all peaks containing Ag and Sn as main components and appearing in the range of 2θ = 38 to 41 ° when measured by X-ray diffraction method It becomes easy to obtain a surface layer in which the ratio of the area of the X-ray intensity of the peak appearing in the range of 2θ = 39.7 to 40.3 ° to the total area of the X-ray intensity of 50% or more, and such an electrical contact The material is excellent with low contact resistance and dynamic friction coefficient.

The heat treatment applied after lamination of the above layers on the conductive substrate may be performed at a heating temperature of 231°C (melting point of tin) to 900°C, preferably 250 to 700°C.

The heat treatment is preferably carried out for a heating time of 5 seconds or more and 8 hours or less. In addition, in the heat treatment, it is preferable to change the heating time within the above range depending on the heating temperature. Specifically, for example, at 250° C., the time is preferably 10 minutes or more and 3 hours or less, and at 700° C., it is preferably 5 seconds or more and 10 minutes or less.

The heat treatment is preferably performed in an inert gas atmosphere or a reducing gas atmosphere. Specifically, N ₂ , Ar, He, or the like can be used as the inert gas. Further, H ₂ , CO, CH ₄ , H ₂ +CO, or the like can be used as the reducing gas. By performing heat treatment in an inert gas atmosphere or a reducing gas atmosphere, oxidation of the metal in each layer can be prevented.

In the case of forming a NiSn-based compound between the underlayer and the surface layer, two layers of a layer containing Ag as a main component and a layer containing Sn as a main component, which are laminated on the underlayer, Alternatively, the Ag content relative to the Sn content in the entire single layer containing Ag and Sn as main components (for example, in the former, the thickness of the layer containing Sn as the main component The layer thickness ratio (Ag thickness/Sn thickness ratio) is decreased, the heating temperature is increased, or the heating time is increased. This makes it easier for Sn to diffuse, and the diffused Sn reacts with Ni to form a NiSn-based compound.

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

Samples of Examples 1 to 24 were produced by any of the manufacturing methods A to F shown below. Further, samples of Comparative Examples 1 to 6 were produced by any of the manufacturing methods G to K shown below. The structures and properties of the produced samples were evaluated, and the results are shown in Table 1 together with the production conditions.

(Ag layer before heating, Sn layer before heating, thickness measurement of underlayer)
According to the fluorescent X-ray test method of JIS H8501:1999, the surface of each sample prepared was subjected to fluorescent X-ray analysis and measured. In addition, in order to confirm the thickness of each layer, the thickness of the cross section was also measured by an image analysis method. The image analysis method was performed according to the scanning electron microscope test method of JIS H8501:1999.

(Ag-Sn eutectoid layer before heating, measurement of surface layer thickness)
Measured by the electrolytic test method of JIS H8501:1999. In addition, the thickness was also measured by the image analysis method in the same manner as the measurement of the thickness of the underlayer.

(Confirmation of existence of NiSn-based compound)
Cross-sectional X-ray photoelectron spectroscopy (XPS) was used on the cross-section of each sample to confirm the presence of NiSn-based compounds. Specifically, Ni ₃ Sn, Ni ₃ Sn ₂ and Ni ₃ Sn ₄ were discriminated from the bonding state of Ni and Sn.

(Method for measuring ratio of peak X-ray intensity area)
The surface of the surface layer of each sample was analyzed using the X-ray diffraction method, and the total area of the X-ray intensity of all peaks appearing in the range of 2θ = 38 to 41 ° 2θ = 39.7 to 40.3 ° The area ratio of the X-ray intensity of the peak appearing in the range of was calculated. X-ray diffraction measurement was performed under the following conditions.
Sample size: 15 mm x 15 mm
Measuring device: Rigaku Co., Ltd. Geigerflex RAD-A
Number of N: n=10

(Method for measuring average particle diameter of granular precipitates)
The surface of the sample was observed with a scanning electron microscope, and the average particle size was determined by the intercept method. Specifically, a rectangular visual field range is set so that 20 or more (400 or more in total) granular precipitates are included in each of the vertical and horizontal sides, and a diagonal line is drawn in this state. The average grain size of the granular precipitates was calculated by measuring the number of precipitates and dividing the diagonal length by the number of granular precipitates measured.

(Measurement of contact resistance value)
The contact resistance between the conductive material (each k material) and the Ag surface-coated overhanging material (oxygen-free copper C1020 with a 3 μm thick Ag layer on the surface, the radius of curvature of the overhanging part is 5 mm) is measured by four terminals. It was obtained by measuring according to the law. A 6220 type DC current source manufactured by TFF Keithley Instruments Co., Ltd. was used as a DC current source, and a current measuring device (2182A nanovoltmeter manufactured by the same company) was used for measuring electrical resistance. The contact resistance values were measured at five arbitrary points, the average value (n=5) was calculated for each, and the values were evaluated according to the following criteria.
◎: Less than 10 mΩ ○: 10 mΩ or more and less than 20 mΩ ×: 20 mΩ or more

(Measurement of dynamic friction coefficient)
Using a surface property measuring machine (manufactured by Shinto Kagaku Co., Ltd., TYPE: 14), the surface on which the surface layer of each sample is formed is covered with an Ag surface-coated overhanging material (oxygen-free copper C1020 having an Ag layer with a thickness of 3 μm on the surface layer. , the curvature radius of the overhanging portion is 5 mm), the moving speed is 100 mm / min, the sliding distance is 5 mm, the contact load is 5 N, and the conductive material is slid back and forth 15 times. It was measured as a coefficient and evaluated according to the following criteria.
◎: less than 0.5 ○: 0.5 or more and less than 0.8 ×: 0.8 or more

(Heat resistance test)
Each sample was heated at 150° C. for 1000 hours in an air atmosphere. After heating, the contact resistance value after heating was obtained according to the method for measuring the contact resistance value described above. The evaluation criteria were also the same.

[Examples 1 to 4: Production method A]
After the oxygen-free copper C1020 was electrolytically degreased and washed with acid, it was plated with nickel in a sulfamic acid bath, silver plated in an alkaline cyanide silver bath, and tin plated in a tin sulfate bath in this order to a predetermined thickness. Next, in an inert or reducing atmosphere, heat in a heat treatment furnace at a set temperature of 250 to 300 ° C. for 10 minutes to 6 hours to alloy the silver plating and the tin plating, and then cool to form a surface layer. of Ag—Sn alloy layer was formed.

[Examples 5 to 8: Manufacturing method B]
After the oxygen-free copper C1020 was electrolytically degreased and washed with acid, it was plated with nickel in a sulfamic acid bath, silver plated in an alkaline cyanide silver bath, and tin plated in a tin sulfate bath in this order to a predetermined thickness. Next, in an inert or reducing atmosphere, in a heat treatment furnace with a set temperature of 400 to 700 ° C., heating is performed for 5 to 300 seconds to alloy the silver plating and the tin plating, and then cooled to form a surface layer. of Ag—Sn alloy layer was formed.

[Examples 9 to 12: Production method C]
After the oxygen-free copper C1020 was electrolytically degreased and washed with an acid, it was plated with nickel in a sulfamic acid bath, silver plated in an alkaline cyanide silver bath, and tin plated in a tin sulfate bath in this order to a predetermined thickness. Next, in an inert or reducing atmosphere, heat in a heat treatment furnace at a set temperature of 250 to 300 ° C. for 10 minutes to 6 hours to alloy the silver plating and the tin plating, and then cool to form a surface layer. of Ag—Sn alloy layer was formed.

[Examples 13 to 16: Production method D]
After the oxygen-free copper C1020 was electrolytically degreased and washed with acid, it was plated with nickel in a sulfamic acid bath, silver plated in an alkaline cyanide silver bath, and tin plated in a tin sulfate bath in this order to a predetermined thickness. Next, in an inert or reducing atmosphere, in a heat treatment furnace with a set temperature of 400 to 700 ° C., heating is performed for 5 to 300 seconds to alloy the silver plating and the tin plating, and then cooled to form a surface layer. of Ag—Sn alloy layer was formed.

[Examples 17 to 20: Production method E]
After the oxygen-free copper C1020 was electrolytically degreased and washed with an acid, nickel-phosphorus alloy plating, silver plating in an alkaline cyanide silver bath, and tin plating in a tin sulfate bath were applied in this order to a predetermined thickness. Next, in an inert or reducing atmosphere, in a heat treatment furnace with a set temperature of 400 to 700 ° C., heating is performed for 5 to 300 seconds to alloy the silver plating and the tin plating, and then cooled to form a surface layer. of Ag—Sn alloy layer was formed.

[Examples 21 to 24: Production method F]
After the oxygen-free copper C1020 was electrolytically degreased and washed with an acid, it was plated with nickel in a sulfamic acid bath and then plated with silver and tin eutectoid in this order to a predetermined thickness. No heat treatment was performed.

[Comparative Example 1: Manufacturing Method G]
After the oxygen-free copper C1020 was electrolytically degreased and washed with an acid, it was plated with silver in an alkaline cyanide silver bath and then plated with tin in a tin sulfate bath in this order to a predetermined thickness. Then, in a reducing atmosphere, it was heated in a heat treatment furnace with a set temperature of 250° C. for 60 minutes and then cooled. Nickel plating (underlayer) is not formed.

[Comparative Example 2: Manufacturing Method H]
After the oxygen-free copper C1020 was electrolytically degreased and washed with acid, it was plated with nickel in a sulfamic acid bath and then tin-plated in a tin sulfate bath in this order to a predetermined thickness. After heating for 20 seconds in a heat treatment furnace of No. 1, it was cooled. Ag plating is not formed.

[Comparative Example 3: Manufacturing Method I]
After the oxygen-free copper C1020 was electrolytically degreased and washed with an acid, it was plated with nickel in a sulfamic acid bath and then plated with silver in an alkaline cyanide silver bath in this order to a predetermined thickness. No Sn plating was formed, and no heat treatment was performed.

[Comparative Examples 4-5: Manufacturing Method J]
After electrolytically degreasing and acid-cleaning the oxygen-free copper C1020, it is plated with nickel in a sulfamic acid bath, silver-plated in an alkaline cyanide silver bath, and tin-plated in a tin sulfate bath in this order to a predetermined thickness. was heated for 60 seconds in a heat treatment furnace set at a low temperature of 200° C. in an inert atmosphere, and then cooled.

As can be seen from Table 1 above, on at least one side of the conductive substrate containing copper (Cu) as the main component, an underlayer containing nickel (Ni) as the main component, and silver (Ag) and tin (Sn) A surface layer containing as a main component is laminated in this order, and the surface layer is measured by X-ray diffraction method. The samples of Examples 1 to 24, in which the ratio of the area of the peak X-ray intensity appearing in the range of =39.7 to 40.3° was 50% or more, had low contact resistance values and dynamic friction coefficients. In addition, the samples of Examples 1 to 24 had a low contact resistance after heating, which was the same as the contact resistance before heating.

On the other hand, the sample of Comparative Example 1 without the Ni layer (base layer) had a high contact resistance after heating.

The sample of Comparative Example 2, in which the surface layer was formed only with tin (Sn), had high contact resistance both before and after the heat treatment.

The sample of Comparative Example 3, in which the surface layer was formed only with silver (Ag) and was not subjected to heat treatment in the manufacturing process, had a high coefficient of dynamic friction and a high contact resistance after heating.

When the heating temperature in the heat treatment is low and the surface layer is measured by X-ray diffraction, 2θ = 39.7 to 40.3 for the total area of the X-ray intensity of all peaks appearing in the range of 2θ = 38 to 41 °. It was found that the samples of Comparative Examples 4 and 5 in which the ratio of the area of the X-ray intensity of the peak appearing in the ° range was less than 50% had high contact resistance both before and after the heat treatment. In addition, the sample of Comparative Example 5 also had a high coefficient of dynamic friction.

1A, 1B Electrical contact material 11 Conductive base material 12 Base layer 13 Surface layer 14 NiSn compound

Claims (7)

On at least one side of a conductive substrate containing copper (Cu) as a main component,
A base layer containing nickel (Ni) as a main component and a surface layer containing silver (Ag) and tin (Sn) as main components are laminated in this order,
When the surface layer is measured by the X-ray diffraction method, the number of peaks appearing in the range of 2θ = 39.7 to 40.3° with respect to the total area of X-ray intensities of all peaks appearing in the range of 2θ = 38 to 41° An electrical contact material having an area ratio of X-ray intensity of 50% or more and 90% or less (excluding cases where a compound is attached to the surface of the electrical contact material.) . 2. The electrical contact material according to claim 1, wherein a NiSn compound is present between said base layer and said surface layer. 3. The surface layer has a large number of granular precipitates, and the average particle size of the granular precipitates present on the surface of the surface layer is in the range of 0.01 to 10 μm. A material for electrical contacts as described. A connector terminal using the electrical contact material according to any one of claims 1 to 3. A connector having the connector terminal according to claim 4 . An electronic component comprising the connector according to claim 5. A method for producing the electrical contact material according to any one of claims 1 to 3,
A base layer containing Ni as a main component is laminated on at least one side of a conductive substrate containing Cu as a main component, and then a layer containing Ag as a main component and a layer containing Sn as a main component are formed on the base layer. A method for producing an electrical contact material , comprising: laminating layers containing the components in random order;

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