Conductive material for electrical connection parts, and contacts, terminals and connectors using the same

Abstract

To provide a conductive material for electrical connection components that can suppress the increase in contact resistance over a long period of time even if a silver layer is worn, and contacts, terminals and connectors using the same.SOLUTION: A conductive material for electrical connection components includes a substrate composed of copper or a copper alloy and being a rolling material, and a nickel layer composed of nickel or a nickel alloy and a silver layer composed of silver or a silver alloy on at least one side of the substrate in this order from the substrate side. In a cross section parallel to the rolling direction of the substrate, skewness Rsk obtained from the roughness curve of the surface on the side with the nickel layer in the substrate is negative.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a conductive material for electrical connection parts, and to a contact, a terminal, and a connector using the same. [Background technology]

[0002] In recent years, the electrification of vehicle drive systems has progressed in order to achieve fuel economy. Accordingly, the amount of current passing through the electrical wires between the battery, inverter, and motor has increased dramatically. Meanwhile, heat generation during current flow has become a problem for electrical connection parts such as contacts and connectors. For this reason, materials are being used that have a nickel underplating on the surface of highly conductive pure copper, dilute copper alloys, or Corson alloys, and then a silver or silver alloy plating on top of the underplating.

[0003] For example, Patent Document 1 describes a silver-plated product in which a base layer made of nickel is formed on a base material made of copper or a copper alloy, and a surface layer made of silver is formed on the surface of this base layer. In the silver-plated product of Patent Document 1, the surface of the base material is roughened, and the skewness Rsk of the roughness curve of the surface of the base layer is 0.1 or more, the arithmetic mean roughness Ra is 0.05 μm or more, and the maximum height Rz is 0.5 μm or more.

[0004] However, in the prior art such as Patent Document 1, silver is a metal that is prone to adhesive wear and is therefore easily scraped off during sliding, which has the drawback of increasing the contact resistance of the silver-plated product due to wear of the silver layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6532322 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a conductive material for electrical connection parts that can suppress an increase in contact resistance over a long period of time even if the silver layer wears, and to provide a contact, a terminal, and a connector using the same. [Means for solving the problem]

[0007] [1] A conductive material for electrical connection parts comprising a substrate made of copper or a copper alloy and being a rolled material, and a nickel layer made of nickel or a nickel alloy and a silver layer made of silver or a silver alloy, which are formed on at least one side of the substrate in this order from the substrate side, wherein, in a cross section parallel to the rolling direction of the substrate, the skewness Rsk obtained from the roughness curve of the surface of the substrate on the side having the nickel layer is a negative value. [2] The conductive material for electrical connection parts according to [1] above, wherein the skewness Rsk obtained from the surface roughness curve is −1.00 or more and −0.10 or less. [3] The conductive material for electrical connection parts according to [1] or [2] above, wherein there are 5 to 30 recesses having a depth of 0.1 μm or more along a 1.0 mm long line segment on the reference line of the surface roughness curve. [4] The conductive material for electrical connection parts according to any one of the above [1] to [3], wherein the nickel layer has an average thickness of 0.05 μm or more and 3.00 μm or less. [5] The conductive material for electrical connection parts according to any one of the above [1] to [4], wherein the average thickness of the silver layer is 0.10 μm or more and 10.00 μm or less. [6] The conductive material for electrical connection parts according to any one of the above [1] to [5], further comprising a copper layer made of copper or a copper alloy between the nickel layer and the silver layer. [7] The conductive material for electrical connection parts according to [6] above, wherein the copper layer has an average thickness of 0.01 μm or more and 0.30 μm or less. [8] The conductive material for electrical connection parts according to any one of the above [1] to [7], wherein after the conductive material for electrical connection parts is subjected to repeated sliding 500 times at a load of 1 N, a sliding distance of 10 mm, and a sliding speed of 100 mm / min, at least a part of the silver layer remains on the conductive material for electrical connection parts after the sliding. [9] A contact point using the conductive material for an electrical connection part according to any one of the above [1] to [8].

[10] A terminal using the conductive material for an electrical connection part according to any one of the above [1] to [8].

[11] A connector using the conductive material for electrical connection parts according to any one of the above [1] to [8]. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to provide a conductive material for electrical connection components that can suppress an increase in contact resistance over a long period of time even if the silver layer wears, as well as contacts, terminals, and connectors that use the same. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a conductive material for an electrical connection component according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing another example of the conductive material for an electrical connection component according to the embodiment. [Figure 3] FIG. 3 is an enlarged cross-sectional view showing an example of the surface state of a substrate in which the skewness Rsk obtained from the surface roughness curve is a negative value. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing an example of the surface state of a substrate in which the skewness Rsk obtained from the surface roughness curve is a positive value. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a detailed description will be given based on an embodiment.

[0011] As a result of extensive research, the inventors have discovered that by controlling the surface etching of a substrate obtained by rolling, fine recesses can be formed on the surface of the substrate, and that by controlling the surface condition of a substrate having fine recesses, an increase in the contact resistance of a conductive material for electrical connection components can be suppressed for a long period of time even if the silver layer wears away. Based on these findings, the present disclosure has been completed.

[0012] The conductive material for electrical connection parts of the embodiment comprises a substrate made of copper or a copper alloy and which is a rolled material, and a nickel layer made of nickel or a nickel alloy and a silver layer made of silver or a silver alloy, which are provided on at least one side of the substrate in this order from the substrate side, and in a cross section parallel to the rolling direction of the substrate, the skewness Rsk obtained from the roughness curve of the surface of the substrate on the side having the nickel layer is a negative value.

[0013] Fig. 1 is a cross-sectional view showing an example of a conductive material for electrical connection parts according to an embodiment. As shown in Fig. 1, the conductive material for electrical connection parts 1 includes a substrate 10, a nickel layer 20, and a silver layer 30. For convenience, Fig. 1 shows a simplified roughness state of a surface 10a of the substrate 10.

[0014] The substrate 10 constituting the conductive material for electrical connection parts 1 is made of copper (Cu) or a copper alloy. The substrate 10 is a rolled material obtained by rolling processing.

[0015] From the viewpoint of suppressing an increase in contact resistance of the conductive material 1 for electrical connection parts due to wear of the silver layer, the substrate 10 is preferably pure copper or a Cu-Zn, Cu-Ni-Si, Cu-Sn-Ni, Cu-Cr-Mg, or Cu-Ni-Si-Sn-Zn-Mg copper alloy.

[0016] From the viewpoint of suppressing an increase in contact resistance of the conductive material for electrical connection components 1 due to wear of the silver layer, the substrate 10 preferably has a plate-like or strip-like shape.

[0017] The nickel layer 20 constituting the conductive material 1 for electrical connection components is provided on a portion of at least one surface of the substrate 10. The nickel layer 20 is made of nickel (Ni) or a nickel alloy.

[0018] From the viewpoint of suppressing an increase in contact resistance of the conductive material for electrical connection parts 1 due to wear of the silver layer, the nickel layer 20 is preferably made of pure nickel or a Ni-P or Ni-Fe nickel alloy. Also, from the viewpoint of improving the adhesion of the nickel layer 20, the nickel layer 20 is preferably formed by plating, i.e., the nickel layer 20 is preferably a plated layer.

[0019] The lower limit of the average thickness of the nickel layer 20 is preferably 0.05 μm or more, more preferably 0.10 μm or more, and even more preferably 0.30 μm or more. The upper limit of the average thickness of the nickel layer 20 is preferably 3.00 μm or less, more preferably 2.00 μm or less, and even more preferably 1.00 μm or less. When the lower limit of the average thickness of the nickel layer 20 is 0.05 μm or more, the wear resistance of the conductive material 1 for electrical connection parts can be improved. When the upper limit of the average thickness of the nickel layer 20 is 3.00 μm or less, the bending workability of the conductive material 1 for electrical connection parts can be maintained good. Furthermore, an increase in the contact resistance of the conductive material 1 for electrical connection parts due to wear of the silver layer can be further suppressed.

[0020] The silver layer 30 constituting the conductive material 1 for electrical connection parts is provided on the nickel layer 20. The conductive material 1 for electrical connection parts comprises a nickel layer 20 and a silver layer 30, in this order, on a portion of at least one surface of the substrate 10. In the conductive material 1 for electrical connection parts shown in FIG. 1, the nickel layer 20 is provided on one surface of the substrate 10, and the silver layer 30 is provided on the surface of the nickel layer 20. The silver layer 30 is made of silver (Ag) or a silver alloy.

[0021] From the viewpoint of suppressing an increase in contact resistance of the conductive material for electrical connection components 1 due to wear of the silver layer, the silver layer 30 is preferably made of pure silver or an Ag-Se or Ag-Sb based silver alloy. Furthermore, from the viewpoint of improving the adhesion of the silver layer 30, the silver layer 30 is preferably formed by plating, i.e., the silver layer 30 is preferably a plated layer.

[0022] The lower limit of the average thickness of the silver layer 30 is preferably 0.10 μm or more, more preferably 0.30 μm or more, and even more preferably 1.00 μm or more. The upper limit of the average thickness of the silver layer 30 is preferably 10.00 μm or less, more preferably 5.00 μm or less, and even more preferably 3.00 μm or less. When the lower limit of the average thickness of the silver layer 30 is 0.10 μm or more, at least a portion of the silver layer 30 remains sufficiently in the multiple fine recesses 12, as described below. Therefore, even if the silver layer 30 wears, an increase in the contact resistance of the conductive material for electrical connection components 1 can be sufficiently suppressed over a long period of time. When the upper limit of the average thickness of the silver layer 30 is 10.00 μm or less, the wear resistance of the conductive material for electrical connection components 1 can be improved.

[0023] Fig. 2 is a cross-sectional view showing another example of a conductive material for electrical connection parts according to an embodiment. In Fig. 2, the roughness state of the surface 10a of the substrate 10 is simplified, as in Fig. 1. The conductive material 2 for electrical connection parts has basically the same configuration as the conductive material 1 for electrical connection parts, except that a copper layer 40 is added.

[0024] 2, the conductive material 2 for electrical connection components further includes a copper layer 40 made of copper or a copper alloy between the nickel layer 20 and the silver layer 30. When the conductive material 2 for electrical connection components includes the copper layer 40, the adhesive strength between the nickel layer 20 and the silver layer 30 is improved.

[0025] From the viewpoint of improving the adhesive strength between the nickel layer 20 and the silver layer 30, the copper layer 40 is preferably made of pure copper or a Cu-Ni-based or Cu-Sn-based copper alloy.

[0026] The lower limit of the average thickness of the copper layer 40 is preferably 0.01 μm or more, more preferably 0.05 μm or more, and even more preferably 0.10 μm or more. The upper limit of the average thickness of the copper layer 40 is preferably 0.30 μm or less, and more preferably 0.20 μm or less. When the lower limit of the average thickness of the copper layer 40 is 0.01 μm or more, the adhesion strength between the nickel layer 20 and the silver layer 30 is further improved. When the upper limit of the average thickness of the copper layer 40 is 0.30 μm or less, an increase in the contact resistance of the conductive material for electrical connection components 2 due to wear of the silver layer can be further suppressed.

[0027] 3 is an enlarged cross-sectional view showing an example of the surface state of the substrate 10 in which the skewness Rsk obtained from the roughness curve of the surface 10a is a negative value. As shown in FIGS. 1 to 3, in the cross section of the conductive materials 1, 2 for electrical connection components parallel to the rolling direction of the substrate 10, which is a rolled material, the skewness Rsk obtained from the roughness curve of the surface 10a (hereinafter simply referred to as the surface 10a) of the substrate 10 on the side having the nickel layer 20 is a negative value.

[0028] 4 is an enlarged cross-sectional view showing an example of the surface state of a substrate in which the skewness Rsk obtained from the surface roughness curve is a positive value, and is outside the scope of the embodiment. As shown in FIG. 4, when the skewness Rsk obtained from the roughness curve of the surface 100a of the substrate is positive, multiple recesses 110 are preferentially present on the surface 100a.

[0029] On the other hand, as shown in Fig. 3, when the skewness Rsk obtained from the roughness curve of the surface 10a of the substrate 10 is negative, multiple convex portions 11 are preferentially present on the surface 10a. Furthermore, multiple fine concave portions 12 are formed between the multiple convex portions 11.

[0030] As shown in FIGS. 1 to 3 , in the conductive materials 1 and 2 for electrical connection parts, the nickel layer 20 and the silver layer 30 are formed by filling many fine recesses 12 provided on the surface 10a of the substrate 10. Even if the silver layer 30 provided on the surface of the conductive materials 1 and 2 for electrical connection parts is worn away from the surface due to sliding of the conductive materials 1 and 2 for electrical connection parts, at least a portion of the silver layer 30 remains in the multiple fine recesses 12 present in the substrate 10. Electrical conductivity can be maintained by at least a portion of the silver layer 30 remaining in the fine recesses 12 of the substrate 10. Therefore, even if the silver layer 30 is worn away, an increase in the contact resistance of the conductive materials 1 and 2 for electrical connection parts can be suppressed for a long period of time.

[0031] Furthermore, the upper limit of the skewness Rsk obtained from the roughness curve of the surface 10a of the substrate 10 is preferably −0.10 or less, more preferably −0.20 or less, and even more preferably −0.30 or less. The lower limit of the skewness Rsk obtained from the roughness curve of the surface 10a of the substrate 10 is preferably −1.00 or more, more preferably −0.80 or more, and even more preferably −0.60 or more. When the skewness Rsk obtained from the roughness curve of the surface 10a is −0.10 or less, an increase in the contact resistance of the conductive materials 1 and 2 for electrical connection components can be further suppressed even if the silver layer 30 is worn. When the skewness Rsk obtained from the roughness curve of the surface 10a is −1.00 or more, a surface 10a having a desired roughness curve can be easily formed.

[0032] Additionally, along a 1.0 mm long line segment on the reference line of the roughness curve of surface 10a, there are preferably 5 or more, more preferably 10 or more recesses with a depth of 0.1 μm or more. Additionally, along a 1.0 mm long line segment on the reference line of the roughness curve of surface 10a, there are preferably 30 or less, more preferably 25 or less recesses with a depth of 0.1 μm or more.

[0033] When recesses having a depth of 0.1 μm or more are present on the roughness curve of the surface 10a, even when the silver layer 30 is worn, at least a portion of the silver layer 30 remains sufficiently in the minute recesses 12 on the surface 10a shown in FIG. 3. When five or more recesses having a depth of 0.1 μm or more are present in any 1.0 mm long line segment on the reference line of the roughness curve of the surface 10a, a sufficient number of minute recesses 12 containing at least a portion of the silver layer 30 are present, thereby suppressing an increase in the contact resistance of the conductive materials 1 and 2 for electrical connection components over a long period of time. Furthermore, when 30 or fewer recesses having a depth of 0.1 μm or more are present in any 1.0 mm long line segment on the reference line of the roughness curve of the surface 10a, the wear resistance of the conductive materials 1 and 2 for electrical connection components can be improved.

[0034] It is also preferable that 30 or less recesses with a depth of 0.2 μm or more exist in a line segment with a length of 1.0 mm on the reference line of the roughness curve of surface 10 a. If 30 or less recesses with a depth of 0.2 μm or more exist in a line segment with a length of 1.0 mm at any portion on the reference line of the roughness curve of surface 10 a, an increase in the contact resistance of conductive materials 1 and 2 for electrical connection parts due to wear of the silver layer can be sufficiently suppressed, and the wear resistance of conductive materials 1 and 2 for electrical connection parts can be sufficiently improved.

[0035] Furthermore, after repeated sliding 500 times at a load of 1 N, a sliding distance of 10 mm, and a sliding speed of 100 mm / min against conductive materials 1 and 2 for electrical connection parts, at least a portion of the silver layer 30 remains on conductive materials 1 and 2 for electrical connection parts after sliding. Thus, even when the silver layer 30 provided on the surface of conductive materials 1 and 2 for electrical connection parts is slid under predetermined conditions, at least a portion of the silver layer 30 remains on conductive materials 1 and 2 for electrical connection parts after sliding, and therefore an increase in contact resistance can be suppressed for a long period of time.

[0036] The roughness curve of the surface 10a of the substrate 10 in a cross section of the conductive materials 1, 2 for electrical connection parts parallel to the rolling direction of the substrate 10 is measured as follows. The nickel layer 20, silver layer 30, and in some cases the copper layer 40 provided on the conductive materials 1, 2 for electrical connection parts are removed from the substrate 10 to expose the surface 10a of the substrate 10. The substrate 10 with the exposed surface 10a is observed using a laser microscope, and the roughness curve of the surface 10a in a cross section parallel to the rolling direction of the substrate 10 is measured. From the obtained roughness curve of the surface 10a, the skewness Rsk is calculated, and the number of recesses with a depth of 0.1 μm or more present along a 1.0 mm long line segment on the reference line is counted.

[0037] As described above, the conductive materials 1 and 2 for electrical connection parts can suppress an increase in contact resistance for a long period of time even when worn down by sliding on the silver layer 30. Therefore, the conductive materials 1 and 2 for electrical connection parts can be suitably used for contacts, terminals, and connectors.

[0038] Next, a method for producing the conductive materials 1 and 2 for electrical connection parts will be described.

[0039] The surface of substrate 10, which is a rolled material processed to a desired thickness by rolling, has irregularities such as oil pits and rolling lines. For substrate 10 having oil pits and rolling lines, the surface is cleaned using a surfactant or alkaline solution as a pretreatment for plating to form nickel layer 20, silver layer 30, and copper layer 40. During this cleaning, the lubricating oil remaining in the oil pits and rolling lines on the surface of the substrate is thoroughly removed, and then the surface of the substrate is etched using an acid solution. This preferentially dissolves the oil pits and rolling lines, and by adjusting the etching conditions, it is possible to form surface 10a in which the skewness Rsk obtained from the roughness curve is a negative value in a cross section parallel to the rolling direction.

[0040] Specifically, first, the lubricating oil remaining in the oil pits and rolling lines on the surface of the substrate 10 is thoroughly removed. Next, an etching solution is used, which is obtained by adding 1% to 10% by mass of hydrogen peroxide and 0.1% to 1.0% by mass of a nonionic surfactant (linear type: carbon number 12 to 18) to 10% sulfuric acid. The substrate 10 is immersed in the etching solution at a bath temperature of 30°C for 5 to 100 seconds, thereby etching the surface of the substrate 10. In this way, a substrate 10 can be obtained having a surface 10a in which the skewness Rsk obtained from the roughness curve in a cross section parallel to the rolling direction is a negative value.

[0041] Next, nickel plating is performed to form a nickel layer 20 on the surface 10a of the base material 10. In nickel plating, by controlling the conditions of the plating solution and current density, it is possible to form a nickel layer 20 having a shape that follows the shape of the surface 10a.

[0042] When manufacturing the conductive material 1 for electrical connection parts, nickel plating is followed by silver plating to form the silver layer 30 on the nickel layer 20. In this way, the conductive material 1 for electrical connection parts can be manufactured.

[0043] When manufacturing the conductive material 2 for electrical connection parts, nickel plating is followed by copper plating to form a copper layer 40 on the nickel layer 20. In copper plating, as with nickel plating, by controlling the plating solution and current density conditions, it is possible to form a copper layer 40 having a shape that conforms to the shape of the surface 10a. Thereafter, silver plating is performed to form a silver layer 30 on the copper layer 40. In this way, the conductive material 2 for electrical connection parts can be manufactured.

[0044] According to the embodiment described above, by controlling the amount of surface etching of the substrate obtained by rolling processing and controlling the state of the substrate surface having fine recesses, it is possible to suppress an increase in the contact resistance of the conductive material for electrical connection components over a long period of time even if the silver layer wears.

[0045] Although the embodiments have been described above, the present invention is not limited to the above embodiments, but includes all aspects encompassed by the concept and scope of the claims of the present disclosure, and can be modified in various ways within the scope of the present disclosure. [Example]

[0046] Next, examples and comparative examples will be described, but the present disclosure is not limited to these examples.

[0047] Examples 1 to 6 First, the lubricating oil remaining in the oil pits and rolling streaks on the surface of the rolled pure copper substrate obtained by rolling treatment was thoroughly removed. Next, the surface of the substrate was etched by immersing the substrate in an etching solution obtained by adding 1% to 10% by mass of hydrogen peroxide and 0.1% to 1.0% by mass of a nonionic surfactant (polyoxyethylene dodecyl ether) to 10% sulfuric acid at a bath temperature of 30°C for 5 to 100 seconds, so that the skewness Rsk obtained from the roughness curve of the substrate surface in a cross section parallel to the rolling direction and the depressions with a depth of 0.1 μm or more present in a 1.0 mm long line segment on the reference line of the roughness curve were the values ​​shown in Table 1.

[0048] Next, nickel plating was performed to form a nickel layer on the etched surface of the substrate to the average thickness shown in Table 1. Next, silver plating was performed to form a silver layer on the nickel layer to the average thickness shown in Table 1. In this way, a conductive material for an electrical connection component was produced.

[0049] (Examples 7 to 14) The surface of the substrate was etched in the same manner as in Example 1. Subsequently, nickel plating was performed to form a nickel layer on the etched surface of the substrate to the average thickness shown in Table 1. Subsequently, copper plating was performed to form a copper layer on the nickel layer to the average thickness shown in Table 1. Subsequently, silver plating was performed to form a silver layer on the copper layer to the average thickness shown in Table 1. In this manner, a conductive material for an electrical connection component was produced.

[0050] (Comparative Examples 1 to 2, 6) A conductive material for electrical connection parts was produced in the same manner as in Example 1, except that the surface of the substrate was etched without removing the lubricating oil remaining in the oil pits and rolling lines on the surface of the substrate.

[0051] (Comparative Example 5) A conductive material for electrical connection parts was produced in the same manner as in Example 1, except that the surface of the substrate was etched without removing the lubricating oil remaining in the oil pits and rolling lines on the surface of the substrate, and silver plating was not performed.

[0052] (Comparative Examples 3 to 4, 7 to 9) In Example 7, a conductive material for electrical connection parts was produced in the same manner as in Example 7, except that the surface of the substrate was etched without removing the lubricating oil remaining in the oil pits and rolling lines on the surface of the substrate.

[0053] [Measurement and Evaluation] The conductive materials for electrical connection parts obtained in the above examples and comparative examples were subjected to the following measurements and evaluations. The results are shown in Table 1.

[0054] [1] Skewness Rsk on the substrate surface and recesses with a depth of 0.1 μm or more The conductive material for electrical connection parts and the platinum wire were immersed in a silver solution prepared by dissolving 100 g of potassium fluoride in pure water to a volume of 1000 ml. Then, the conductive material for electrical connection parts was used as the anode and the platinum wire as the cathode, and a current density of 20 mA / cm was applied. 2 The silver layer was removed by constant current electrolysis at 1000 kJ / min.

[0055] Next, in Examples 7 to 14 and Comparative Examples 3 to 4 and 7 to 9, the conductive material for electrical connection parts and the platinum wire were immersed in a copper solution prepared by dissolving 10 g of ferric chloride and 2 ml of hydrochloric acid with a specific gravity of 1.19 in 95 ml of pure water. Then, the conductive material for electrical connection parts was used as the anode and the platinum wire as the cathode, and a current density of 20 mA / cm was applied. 2 The copper layer was removed by constant current electrolysis at 1000 kJ / min.

[0056] Next, the conductive material for electrical connection parts and the platinum wire were immersed in a nickel solution prepared by diluting 100 ml of hydrochloric acid (specific gravity 1.18) with 1000 ml of pure water. Then, the conductive material for electrical connection parts was used as the anode and the platinum wire as the cathode, and a current density of 20 mA / cm was applied. 2 The nickel layer was removed by constant current electrolysis at 1000 kJ / min, thereby exposing the surface of the substrate.

[0057] The exposed substrate surface was observed at a magnification of 50x using a laser microscope (shape analysis laser microscope Vk-X1000, manufactured by Keyence Corporation), and the surface roughness curve of the cross section parallel to the rolling direction of the substrate was measured. From the obtained roughness curve of the substrate surface, the skewness Rsk was calculated, and the number of recesses with a depth of 0.1 μm or more present within a line segment 1.0 mm long on the reference line was counted.

[0058] [2] Contact resistance Using an electrical contact simulator (manufactured by Yamazaki Seiki Kenkyusho Co., Ltd.), the contact resistance of the conductive material for electrical connection parts was measured 10 times at a current value of 20 mA and a load of 1 N, and the average of the measured values ​​was taken as the contact resistance value. The contact resistance values ​​were ranked as follows:

[0059] ◎: Contact resistance is less than 2mΩ ○: Contact resistance is 2mΩ or more and less than 10mΩ ×: Contact resistance is 10mΩ or more

[0060] [3] Contact resistance after sliding Using a friction and wear tester Tribogear (surface property measuring instrument TYPE: 14FW, manufactured by Shinto Scientific Co., Ltd.), the conductive material for electrical connection parts was repeatedly slid 500 times at a load of 1N, a sliding distance of 10mm, and a sliding speed of 100mm / min, and the contact resistance of the contact area after sliding was measured 10 times using the four-terminal method with a current of 20mA and a load of 1N, and the average of the obtained measurements was taken as the contact resistance after sliding. The contact resistance after sliding was ranked as follows.

[0061] ◎: Contact resistance after sliding is less than 2mΩ ○: Contact resistance after sliding is 2mΩ or more and less than 10mΩ ×: Contact resistance after sliding is 10 mΩ or more

[0062] [4] Coefficient of friction Using a friction and wear tester, Tribogear (surface property measuring instrument TYPE: 14FW, manufactured by Shinto Scientific Co., Ltd.), the conductive material for electrical connection parts was repeatedly slid at a load of 1 N, a sliding distance of 10 mm, and a sliding speed of 100 mm / min. The average value of the friction coefficients obtained after 30 repeated sliding cycles was taken as the dynamic friction coefficient. In addition, after 500 repeated sliding cycles, a backscattered electron image of the surface of the conductive material for electrical connection parts was taken at 500x magnification using a scanning electron microscope (SEM, manufactured by Hitachi High-Tech Corporation). The friction coefficients were ranked as follows:

[0063] ○: Friction coefficient less than 0.8 ×: Friction coefficient is 0.8 or more

[0064] [5] Bending workability In accordance with the Japan Copper and Brass Association technical standard JCBA T307 (2007), a bending workability evaluation method for copper and copper alloy thin sheet strips, a conductive material for electrical connection parts with a width of 10 mm and a length of 30 mm was bent in the LD direction at r / t = 1.0, where the bending radius and sheet thickness are the same, and observed at 50x magnification to evaluate workability.

[0065] 〇: No cracks can be seen ×: Cracks can be seen

[0066] [Table 1]

[0067] As shown in Table 1, in Examples 1 to 14, the skewness Rsk value obtained from the roughness curve of the substrate surface in a cross section parallel to the rolling direction of the substrate was negative, and therefore the contact resistance, contact resistance after sliding, friction coefficient, and bending workability were good, with the contact resistance and friction coefficient after sliding being particularly excellent. Furthermore, in Examples 1 to 14, after 500 repeated sliding cycles, the surface of the conductive material for electrical connection components was observed using an SEM, and it was confirmed that at least a portion of the silver layer remained. Therefore, it was found that the conductive material for electrical connection components of Examples 1 to 14 could suppress an increase in contact resistance over a long period of time, even if the silver layer wore away.

[0068] On the other hand, in Comparative Examples 1 to 9, the skewness Rsk value obtained from the roughness curve of the substrate surface in a cross section parallel to the rolling direction of the substrate was not negative, so at least one of the contact resistance, contact resistance after sliding, friction coefficient, and bending workability was poor, and the contact resistance after sliding and friction coefficient were particularly poor. Furthermore, in Comparative Examples 1 to 9, after 500 repeated sliding cycles, the surface of the conductive material for electrical connection parts was observed using an SEM, and it was confirmed that no part of the silver layer remained. Therefore, it was found that the contact resistance of the conductive materials for electrical connection parts of Comparative Examples 1 to 9 increased when the silver layer wore away. [Explanation of symbols]

[0069] 1, 2 Conductive materials for electrical connection parts 10 Base material 10a Surface of substrate 11 Convex part 12 Microscopic recesses 20 nickel layer 30 silver layer 40 copper layers 100a Surface of the substrate 110 recess

Claims

1. a substrate made of copper or a copper alloy and being a rolled material; A conductive material for an electrical connection part, comprising a nickel layer made of nickel or a nickel alloy and a silver layer made of silver or a silver alloy, in this order from the substrate side, on a part of at least one surface of the substrate, In a cross section of the substrate parallel to the rolling direction, a skewness Rsk obtained from a roughness curve of a surface of the substrate on the side having the nickel layer is a negative value, A conductive material for electrical connection parts, characterized in that there are 5 to 30 recesses having a depth of 0.1 μm or more within a 1.0 mm long line segment on the reference line of the surface roughness curve.

2. 2. The conductive material for electrical connection parts according to claim 1, wherein the skewness Rsk obtained from the surface roughness curve is −1.00 or more and −0.10 or less.

3. 3. The conductive material for electrical connection parts according to claim 1, wherein the average thickness of the nickel layer is 0.05 μm or more and 3.00 μm or less.

4. The conductive material for electrical connection parts according to any one of claims 1 to 3, wherein the average thickness of the silver layer is 0.10 µm or more and 10.00 µm or less.

5. The conductive material for an electrical connection part according to any one of claims 1 to 4, further comprising a copper layer made of copper or a copper alloy between the nickel layer and the silver layer.

6. 6. The conductive material for electrical connection parts according to claim 5, wherein the average thickness of the copper layer is 0.01 μm or more and 0.30 μm or less.

7. The conductive material for electrical connection parts according to any one of claims 1 to 6, wherein after the conductive material for electrical connection parts is subjected to repeated sliding 500 times at a load of 1 N, a sliding distance of 10 mm, and a sliding speed of 100 mm / min, at least a part of the silver layer remains on the conductive material for electrical connection parts after the sliding.

8. A contact point using the conductive material for electrical connection parts according to any one of claims 1 to 7.

9. A terminal using the conductive material for electrical connection parts according to any one of claims 1 to 7.

10. A connector using the conductive material for electrical connection parts according to any one of claims 1 to 7.

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