Plating material

Abstract

The present invention provides a plating material that can suppress the increase in contact resistance when used in a micro-sliding state. [Solution] The plating material 1 comprises a base material 10 mainly composed of copper, and a Sn-Ni plating layer 20 formed on the surface of the base material 10 and composed of a plurality of crystal grains. The average particle size of the plurality of crystal grains is 1 μm or more and 10 μm or less. The Sn-Ni plating layer 20 contains a Sn phase, a Ni3Sn4 phase, and a NiSn phase. The Ni content in the Sn-Ni plating layer 20 is 2% by mass or more and 15% by mass or less.

Description

Technical Field

[0001] The present invention relates to a plating material, and more particularly to a plating material mainly used for electrical and electronic components such as terminals, connectors, junction blocks, and circuit boards for automobiles and consumer use.

Background Art

[0002] With the recent hybridization of automobiles and the spread of electric vehicles, the electrical and electronic devices mounted on automobiles have been increasing, their control has been progressing electronically, and electricity is also being used for power. For their connection, electrical wiring and connector parts are required, and the number of connectors is increasing not only for automobiles but also for consumer use. Generally, copper alloy materials with surface treatments such as Sn plating, Ag plating, and Au plating are used for connectors. In ensuring the reliability of automobiles, the connection reliability of connectors has become increasingly important, and the required performance of the plating material as its material has been increasing.

[0003] Patent Document 1 discloses a metal member having a solder connection portion that is connected to an attachment object by soldering. This metal member has a metal base material and a Sn-Ni alloy plating layer that covers the metal base material of the solder connection portion and is provided as the outermost layer of the metal plating layer that covers the metal base material of the solder connection portion. The Sn-Ni alloy plating layer has a Sn content of 75 to 93% by mass, and the balance consists of Ni and impurities. This metal member has good soldering properties in the solder connection portion that is connected to an attachment object by soldering, and moreover, is difficult to generate acicular crystals (whiskers) and is said to be inexpensive.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Connectors used for connecting electrical wires in automobiles and other vehicles typically consist of mating terminals, which are a combination of male and female terminals. Such mating terminals are required to have low insertion force. Furthermore, due to the need to conserve space in the vehicle's interior, the location of connectors is shifting from the interior to the engine compartment. In the engine compartment, slight friction occurs due to engine vibrations.

[0006] Given this background, the plating material used as a terminal is required to have not only low normal contact resistance, but also low contact resistance during fine sliding, and furthermore, the ability to suppress the increase of these contact resistances over time.

[0007] The object of the present invention is to provide a plating material that can suppress the increase in contact resistance when used in a micro-sliding state. [Means for solving the problem]

[0008] A plating material according to one aspect of the present invention comprises a base material mainly composed of copper, and a Sn-Ni plating layer formed on the surface of the base material and composed of a plurality of crystal grains, wherein the average particle size of the plurality of crystal grains is 1 μm or more and 10 μm or less, the Sn-Ni plating layer contains a Sn phase, a Ni3Sn4 phase, and a NiSn phase, and the Ni content in the Sn-Ni plating layer is 2% by mass or more and 15% by mass or less. [Effects of the Invention]

[0009] The plated material of the present invention can suppress the increase in contact resistance when used in a micro-sliding state. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic cross-sectional view showing a plated material according to the first embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing a plating material according to a third embodiment of the present invention. [Figure 3]Figure 3 is a scanning electron microscope image of the crystal grains of the Sn-Ni plated layer in the present invention. [Figure 4] Figure 4 shows the distribution of each element in a cross-section of the Sn-Ni plated layer according to the present invention. [Figure 5] Figure 5 is a graph showing the change in contact resistance over time during micro-sliding in Example 1-2. [Figure 6] Figure 6 is a graph showing the change in contact resistance over time during micro-sliding in Comparative Example 2. [Modes for carrying out the invention]

[0011] 1. Overview The outline of the plating material 1 of the present invention will be described below with reference to the drawings. Note that the drawings are schematic, and the ratios of the size and thickness of each component in the drawings do not necessarily reflect the actual dimensional ratios.

[0012] In order to solve the aforementioned problems, the inventors diligently conducted research and focused on the grain size of the crystal grains, the types of phases present, and the Ni content in the Sn-Ni plating layer 20. They found that there is a relationship between these factors and the properties during micro-sliding, and thus completed the present invention.

[0013] As shown in Figure 1, the plating material 1 of the present invention comprises a base material 10 mainly composed of copper and a Sn-Ni plating layer 20 formed on the surface of the base material 10. The plating material 1 may also include other plating layers besides the Sn-Ni plating layer 20. The Sn-Ni plating layer 20 is composed of a plurality of crystal grains.

[0014] The plating material 1 of the present invention has the following characteristic configuration in particular. The average particle size of the multiple crystal grains (hereinafter also referred to as crystal grain (X)) constituting the Sn-Ni plating layer 20 is 1 μm or more and 10 μm or less. The Sn-Ni plating layer 20 contains a Sn phase, a Ni3Sn4 phase, and a NiSn phase. The Ni content in the Sn-Ni plating layer 20 is 2% by mass or more and 15% by mass or less.

[0015] The plating material 1 of the present invention can suppress an increase in contact resistance (hereinafter also referred to as contact resistance during micro-sliding) when used in a micro-sliding state. Although the reason for achieving the above effect when the plating material 1 of the present invention has the above configuration is not necessarily clear, it can be speculated as follows, for example. In the plating material 1, by setting the average grain size of the crystal grains (X) constituting the Sn-Ni plating layer 20 within the specific range, the surface contact between the plating material 1 and the terminal becomes good. Also, in the Sn-Ni plating layer 20, the Ni3Sn4 phase, which is a phase composed of the Sn phase and a specific intermetallic compound, and the NiSn phase are mixed, and by setting the Ni content in the Sn-Ni plating layer 20 containing these phases within the specific range, it is presumed that the microstructure composed of the Sn phase and the phase of the specific intermetallic compound is appropriately distributed, whereby it is considered that the contact resistance during micro-sliding is kept low for a long time. As a result of these, the plating material 1 can suppress an increase in contact resistance during micro-sliding over time.

[0016] The plating material 1 of the present invention further has excellent soldering properties and whisker resistance, and can also exhibit the effect of being excellent in cost performance at a low cost.

[0017] 2. Details <Plating Material> (First Embodiment) As shown in FIG. 1, the plating material 1 of the first embodiment includes a base material 10 and a Sn-Ni plating layer 20. In the plating material 1 of the first embodiment, the Sn-Ni plating layer 20 is formed directly on the surface of the base material 10. The Sn-Ni plating layer 20 may be formed on one side of the base material 10 or on both sides of the base material 10.

[0018] The plating material 1 can be suitably used, for example, for terminals, connectors, etc. for automobiles and consumer products. Hereinafter, each component of the plating material 1 will be described.

[0019] [Base Material] The base material 10 is the base material to be plated. The base material 10 mainly contains copper. The "main component" refers to the component with the largest content rate, for example, a component with a content rate of 30% by mass or more, preferably 50% by mass or more, and more preferably 70% by mass or more. Examples of the base material 10 mainly containing copper include copper materials, copper alloy materials, etc.

[0020] The base material 10 is usually composed of a plurality of crystal grains. The average grain diameter of the crystal grains constituting the base material 10 is, for example, 0.3 μm or more, preferably 1 μm or more, and more preferably 5 μm or more. This average grain diameter is, for example, 30 μm or less. By setting the average grain diameter of the crystal grains in the base material 10 within the above range, an increase in contact resistance when the plating material 1 is used in a sliding state can be more effectively suppressed. The average grain diameter of the crystal grains in the base material 10 can be determined by the same method as the average grain diameter of the crystal grains X in the Sn-Ni plating layer 20 described later.

[0021] The base material 10 may be any material that mainly contains copper and can be plated, and examples include copper connectors and the like that are the objects to be plated. Also, the shape of the base material 10 may be, for example, plate-shaped, and its thickness is, for example, 0.1 mm or more and 10 mm or less.

[0022] [Sn-Ni plating layer] The "Sn-Ni plating layer" is a layer formed by plating that contains Sn as the main component and Ni as the sub-component. In the plating material 1 of the first embodiment, the Sn-Ni plating layer 20 is a layer directly formed on the surface of the base material 10.

[0023] The average thickness of the Sn-Ni plating layer 20 is, for example, 0.1 μm or more and 10 μm or less, and preferably 1 μm or more and 7 μm or less. The "average thickness" means the arithmetic average value of the measured thickness values at a plurality of points (for example, any 10 points) in the Sn-Ni plating layer 20. The thickness of the Sn-Ni plating layer 20 can be measured, for example, by X-ray fluorescence analysis (XRF).

[0024] Figure 3 is a scanning electron microscope (SEM) image of the Sn-Ni plating layer 20. As shown in Figure 3, the Sn-Ni plating layer 20 is composed of multiple crystal grains X. A "crystal grain" refers to the largest region in which atoms are arranged in a regular, repeating pattern.

[0025] Examples of crystal grain shapes for X include approximately spherical, approximately elongated spherical, rod-shaped, pyramidal, conical, rectangular parallelepiped, and cubic. Among these, approximately spherical is preferred, as shown in Figure 3. When crystal grains X are approximately spherical, the sliding resistance of the surface of the Sn-Ni plating layer 20 is reduced, thereby further suppressing the increase in contact resistance during micro-sliding.

[0026] The aspect ratio of crystal grain X is preferably 3 or less. The "aspect ratio" of a crystal grain refers to the ratio of the major axis to the minor axis of crystal grain X. This aspect ratio is more preferably 2.5 or less, even more preferably 2.0 or less, and particularly preferably 1.5 or less. This aspect ratio is usually 1 or more, and may also be 1.1 or more.

[0027] It is important that the average grain size of crystal grain X is between 1 μm and 10 μm. The "average grain size" of a crystal grain refers to the arithmetic mean of the maximum diameter of each crystal grain X measured for multiple (for example, any 30) crystal grains X using SEM images of crystal grain X as shown in Figure 3.

[0028] The average grain size of the crystal grains X is preferably 2 μm or more, and more preferably 3 μm or more. The average grain size of the crystal grains X is preferably 9 μm or less, and more preferably 8 μm or less. By setting the average grain size of the crystal grains X within the above range, the increase in contact resistance during micro-sliding can be further suppressed. The average grain size of the formed crystal grains X can be changed, for example, by changing the composition of the Sn-Ni plating bath or the current density.

[0029] It is important that the Sn-Ni plating layer 20 contains a Sn phase, a Ni3Sn4 phase, and a NiSn phase. A "phase" refers to a region with a uniform composition. That is, a crystal grain X contains a region consisting of Sn as a metal, a region consisting of Ni3Sn4 as an intermetallic compound, and a region consisting of NiSn as an intermetallic compound.

[0030] The presence of the Sn phase, Ni3Sn4 phase, and NiSn phase can be confirmed by the diffraction angle 2θ of the peaks in the X-ray diffraction pattern. Specifically, by measuring the X-ray diffraction pattern using the characteristic X-ray CuKα, the presence of the Sn phase can be confirmed by a group of peaks including a peak around 2θ=45°, the Ni3Sn4 phase by a group of peaks including a peak around 2θ=39°, and the NiSn phase by a group of peaks including a peak around 2θ=41°.

[0031] The Sn phase, Ni3Sn4 phase, and NiSn phase in the Sn-Ni plating layer 20 can be formed, for example, by controlling the composition and current density of the Sn-Ni plating bath.

[0032] In the Sn-Ni plating layer 20, the sum of the peak intensities of the Sn phase, Ni3Sn4 phase, and NiSn phase is 100%. The proportion of peak intensity in the Sn phase is, for example, 10% to 90%, and preferably 20% to 70%. The percentage of peak intensity of the Ni3Sn4 phase is, for example, 10% to 50%, and preferably 20% to 30%. The proportion of peak intensity of the NiSn phase is, for example, 20% to 50%, and preferably 30% to 40%.

[0033] By setting the ratio of peak intensities of the Sn phase, Ni3Sn4 phase, and NiSn phase in the Sn-Ni plating layer 20 to the aforementioned range, the distribution of the microstructure consisting of the Sn phase and the intermetallic compound phase becomes more appropriate, and the increase in contact resistance during micro-sliding can be further suppressed. The ratio of peak intensities for the Sn phase, Ni3Sn4 phase, and NiSn phase in the Sn-Ni plating layer 20 is calculated using the area of ​​the peak around 2θ=45° for the Sn phase, the area of ​​the peak around 2θ=39° for the Ni3Sn4 phase, and the area of ​​the peak around 2θ=41° for the NiSn phase.

[0034] The Sn-Ni plating layer 20 may contain other phases besides the Sn phase, Ni3Sn4 phase, and NiSn phase, such as Ni3Sn2 phase and NiSn3 phase, to the extent that it does not impair the effects of the present invention.

[0035] It is important that the Ni content in the Sn-Ni plating layer 20 is between 2% by mass and 15% by mass. When the Ni content is within the specified range, the increase in contact resistance during micro-sliding can be suppressed. If the Ni content is below the lower limit, the Sn-Ni plating layer 20 becomes too soft, the sliding resistance increases, and the Sn-Ni plating layer 20 becomes prone to peeling, making it impossible to suppress the increase in contact resistance during micro-sliding. If the Ni content exceeds the upper limit, the Sn-Ni plating layer 20 becomes too hard, and the adhesion to the substrate 10 also decreases, making it impossible to suppress the increase in contact resistance during micro-sliding.

[0036] The Ni content is preferably 4% by mass or more, more preferably 5% by mass or more, even more preferably 8% by mass or more, and particularly preferably 9% by mass or more. The Ni content is preferably 14% by mass or less, more preferably 13% by mass or less, even more preferably 12% by mass or less, and particularly preferably 11% by mass or less. By setting the Ni content in the Sn-Ni plating layer 20 within the above range, the increase in contact resistance during micro-sliding can be further suppressed.

[0037] The "Ni content" in the Sn-Ni plating layer 20 refers to the ratio (mass%) of the mass of Ni contained in the Sn-Ni plating layer 20 to the total mass of the Sn-Ni plating layer 20. If the Sn-Ni plating layer 20 consists only of Sn and Ni, the Ni content refers to the ratio (mass%) of the mass of Ni to the total mass of Sn and Ni. The Ni content can be determined, for example, by X-ray fluorescence analysis (XRF), specifically by using an X-ray fluorescence analyzer (e.g., Fischer Instruments), and creating calibration curves for the X-ray fluorescence intensity of Ni and Sn in advance using multiple samples with different thicknesses of each plating layer (Ni plating layer / copper plate and Sn plating layer / copper plate) as standard samples. Based on these calibration curves, the mass ratio of each element constituting the Sn-Ni plating layer 20 can be calculated to determine the Ni content.

[0038] The Ni content in the Sn-Ni plating layer 20 can be changed, for example, by changing the ratio of Ni ion concentration to total ion concentration in the Sn-Ni plating bath.

[0039] In the Sn-Ni plating layer 20, it is preferable that Ni is unevenly distributed in the region on the substrate 10 side, as shown in the elemental distribution of Ni in Figure 4. That is, if the Sn-Ni plating layer 20 has a first region located on the substrate 10 side of the center in the thickness direction and a second region located on the opposite side of the first region from the center in the thickness direction, it is preferable that the Ni content in the first region is greater than the Ni content in the second region. It is thought that by unevenly distributing Ni in the region on the substrate 10 side in this way, the sliding resistance becomes smaller, that is, the sliding properties become better, and the increase in contact resistance during micro-sliding can be further suppressed.

[0040] Furthermore, in the Sn-Ni plating layer 20, it is preferable that the Ni content gradually decreases as it moves away from the interface with the substrate 10. In this case, it is preferable that the surface layer of the Sn-Ni plating layer 20, that is, the region near the surface of the Sn-Ni plating layer 20 opposite to the substrate 10, consists only of the Sn phase. In the cross-sectional direction, if the Sn-Ni plating layer 20 contains more Ni3Sn4 phase and NiSn phase with a higher Ni content on the substrate 10 side, and has the Sn phase on the surface side, it is thought that the sliding properties are maintained by the hardness of the intermetallic compound on the substrate 10 side, while the surface layer's Sn phase provides contact resistance equivalent to that of the Sn layer. With such a distribution of Ni, the contact resistance due to the surface layer's Sn phase and the sliding resistance due to the intermetallic compound phase with a high Ni content on the substrate 10 side are balanced, and the increase in contact resistance during micro-sliding can be further suppressed.

[0041] The Sn-Ni plating layer 20 in the plating material 1 of the first embodiment can be formed, for example, by electroalloy plating. Specifically, the Sn-Ni plating layer 20 can be formed by using a plating solution mainly composed of tin chloride and nickel chloride and performing DC electrolysis.

[0042] (Second Embodiment) The plating material 1 of the second embodiment comprises a base material 10, a Sn-Ni plating layer 20, and a Sn plating layer 30 formed on the Sn-Ni plating layer 20. In other words, the plating material 1 of the second embodiment comprises the base material 10, the Sn-Ni plating layer 20, and the Sn plating layer 30 in this order. The plating material 1 of the second embodiment differs from the plating material 1 of the first embodiment in that it further comprises a Sn plating layer 30 on top of the Sn-Ni plating layer 20. In the following description, components that overlap with the first embodiment may be denoted by the same reference numerals in the drawings, and their specific descriptions may be omitted.

[0043] [Substrate and Sn-Ni plating layer] The base material 10 and Sn-Ni plating layer 20 in the second embodiment of the plating material 1 are the same as the base material 10 and Sn-Ni plating layer 20 in the first embodiment of the plating material 1 described above.

[0044] [Sn plating layer] The Sn plating layer 30 is formed on the Sn-Ni plating layer 20. In other words, the Sn plating layer 30 is laminated on the Sn-Ni plating layer 20. The Sn plating layer 30 may be laminated on the Sn-Ni plating layer 20 via other layers, but it is preferable that it is laminated directly on the Sn-Ni plating layer 20.

[0045] The Sn plating layer 30 is a layer formed by plating and contains Sn as its main component. Preferably, the Sn plating layer 30 is a layer consisting only of Sn.

[0046] The plated material 1 of the second embodiment has a Sn plating layer 30 on its outermost surface, which provides excellent solder wettability.

[0047] The average thickness of the Sn plating layer is, for example, 0.1 μm to 5 μm, and preferably 1 μm to 3 μm.

[0048] The plated material 1 of the second embodiment can be manufactured, for example, by applying Sn plating to the surface of the Sn-Ni plated layer 20 of the plated material 1 of the first embodiment to form a Sn plated layer 30.

[0049] (Third embodiment) As shown in Figure 2, the plating material 1 of the third embodiment comprises a base material 10, a Sn-Ni plating layer 20, a Sn plating layer 30, and a Ni plating layer 40 formed between the base material 10 and the Sn-Ni plating layer 20. In other words, the plating material 1 of the third embodiment comprises the base material 10, the Ni plating layer 40, the Sn-Ni plating layer 20, and the Sn plating layer 30 in this order. The plating material 1 of the third embodiment differs from the plating material 1 of the first embodiment in that it further comprises the Sn plating layer 30 and the Ni plating layer 40, and differs from the plating material 1 of the second embodiment in that it further comprises the Ni plating layer 40. In the following description, components that overlap with the first and second embodiments are denoted by the same reference numerals in the drawings, and their specific descriptions may be omitted.

[0050] [Substrate, Sn-Ni plating layer, and Sn plating layer] The base material 10, Sn-Ni plating layer 20, and Sn plating layer 30 in the third embodiment of the plating material 1 are the same as the base material 10 and Sn-Ni plating layer 20 in the first and second embodiments of the plating material 1 described above, and the Sn plating layer 30 in the second embodiment of the plating material 1.

[0051] [Ni plating layer] The Ni plating layer 40 is formed between the substrate 10 and the Sn-Ni plating layer 20. In other words, the Ni plating layer 40 is laminated on both the substrate 10 and the Sn-Ni plating layer 20. The Ni plating layer 40 may be laminated on the substrate 10 or the Sn-Ni plating layer 20 via other layers, but it is preferable that it is directly laminated on both the substrate 10 and the Sn-Ni plating layer 20.

[0052] The Ni plating layer is a layer formed by plating, with Ni as its main component. Preferably, the Ni plating layer 40 is a layer consisting only of Ni.

[0053] In the third embodiment, the plated material 1 has a Ni plating layer 40 between the substrate 10 and the Sn-Ni plating layer 20, which helps to suppress the increase in contact resistance when used at high temperatures.

[0054] The average thickness of the Ni plating layer 40 is, for example, 0.1 μm or more and 5 μm or less, and preferably 1 μm or more and 2 μm or less.

[0055] The plated material 1 of the third embodiment can be manufactured, for example, by applying Ni plating to the surface of a substrate 10 to form a Ni plating layer 40, applying Sn-Ni plating to the surface of the Ni plating layer 40 to form a Sn-Ni plating layer 20, and applying Sn plating to the surface of the Sn-Ni plating layer 20 to form a Sn plating layer 30.

[0056] (modified version) The above embodiment is not one of many embodiments of the present invention. The above embodiment can be modified in various ways depending on the design, etc., as long as the objective of the present invention is achieved. The following lists some modifications of the above embodiment. The modifications described below can be combined and applied as appropriate.

[0057] In the first embodiment, the plated material 1 was a substrate 10 with a Sn-Ni plating layer 20 laminated on top, but it is not limited to this, and may further include an Ag plating layer or an Au plating layer on top of the Sn-Ni plating layer 20.

[0058] In the second embodiment, the plated material 1 was a substrate 10 with a Sn-Ni plated layer 20 and a Sn plated layer 30 laminated on it, but it is not limited to this, and an Ag plated layer may be further provided on top of the Sn plated layer 30.

[0059] In the third embodiment, the plated material 1 was a substrate 10 with a Ni plating layer 40, a Sn-Ni plating layer 20, and a Sn plating layer 30 laminated on it, but it is not limited to this, and an Ag plating layer may be provided instead of the Sn plating layer 30. Also, an Ag plating layer may be provided on top of the Sn plating layer 30, and a Zn plating layer may be provided between the Sn-Ni plating layer 20 and the Sn plating layer 30. An Ag plating layer, a Zn plating layer, etc. may be provided instead of the Ni plating layer 40.

[0060] In the first to third embodiments, the plated material 1 was obtained by forming each plating layer on a base material 10, but it is not limited to this, and the plated material 1 may also be obtained by heat treatment such as reflow treatment to dissipate the copper contained in the base material 10 through heat. Examples of heat diffusion treatment methods include heating in a hot air furnace and induction heating.

[0061] The plating material 1 of the present invention can be manufactured by electroplating, such as electroalloy plating or electromultilayer plating, or by electroless plating. [Examples]

[0062] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to these examples.

[0063] <Manufacturing of plated materials> [Examples and Comparative Examples] In electroplating, a plated material having the following plating layer structure was obtained by forming various Sn-Ni plating layers on the surface of a copper plate (dimensions: 30 mm x 30 mm, thickness: 0.8 mm) using a plating solution mainly composed of tin chloride and nickel chloride, and by DC electrolysis. The Ni content (mass%) of the formed Sn-Ni plating layer was changed by altering the ratio of Ni ion concentration to total ion concentration. Examples: Example 1-1: Sn-Ni plating layer (Ni: 5% by mass) / copper plate • Example 1-2: Sn-Ni plating layer (Ni: 10% by mass) / copper plate • Examples 1-3: Sn-Ni plating layer (Ni: 15% by mass) / copper plate Example 2: Sn plating layer / Sn-Ni plating layer (Ni: 10% by mass) / Ni plating layer / copper plate Comparative example: Comparative Example 1-1: Sn-Ni plating layer (Ni: 25% by mass) / copper plate • Comparative Example 2: Sn plating layer / copper plate • Comparative Example 3: Ag plating layer / copper plate

[0064] <Rating> Each of the plated materials obtained was evaluated for the following items using the method described below.

[0065] [Distribution of each element in plated materials] For the plated material of Example 1-1 (Sn-Ni plated layer (Ni: 5 mass%)), a cross-sectional analysis sample was prepared by ion milling (dry), and this cross-section was observed with FE (field emission)-SEM. The distribution of each element, Sn, Ni, and Cu, was measured by energy-dispersive X-ray spectroscopy (EDX). The measurement results are shown in Figure 4. In Figure 4, (SEM) is an electron microscope image of the cross-section of the plated material having a Sn-Ni plated layer on a copper plate, and (Sn), (Ni), and (Cu) show the distribution of each element, Sn, Ni, and Cu, in the cross-section of the plated material, respectively.

[0066] [Contact resistance during slight sliding] Using a micro-sliding abrasion testing apparatus, a plated test piece with a flat surface was brought into contact with a plated test piece having hemispherical protrusions with a radius of curvature of 1.5 mm. At room temperature, under the conditions of load: 1 N, sliding distance: 50 μm, and period: 1 Hz, the change in contact resistance (unit: mΩ) during micro-sliding over time was measured. Table 1 shows the values ​​of the contact resistance during micro-sliding after 150 cycles. Furthermore, the change in contact resistance during micro-sliding over time (at room temperature, up to 500 sliding cycles) is shown in Figure 5 for the plating material of Example 1-2 (Sn-Ni plating layer (Ni: 10 mass%) / substrate) and in Figure 6 for the plating material of Comparative Example 2 (Sn plating layer / substrate).

[0067] [Table 1]

[0068] [Vickers hardness scale] The Vickers hardness (HV) was measured on the surface of the outermost plating layer of the plated material using a micro-Vickers hardness tester (MVK-H300A2 manufactured by Akashi Corporation). Table 2 shows the Vickers hardness values ​​for the plated materials in each example and comparative example.

[0069] [Table 2]

[0070] As is clear from the results in Table 1 and Figures 5 and 6, the plated material of the example is able to suppress the increase in contact resistance when used in a micro-sliding state.

[0071] Furthermore, as is clear from the results in Table 2, the hardness of the plating layer in the plating material of the present invention is considerably greater than that of the Sn plating layer in the plating material of Comparative Example 2, and is almost the same as that of the Ag plating layer in the plating material of Comparative Example 3. This means that the sliding resistance is high, which is considered to be one of the reasons why the plating material of the present invention maintains contact resistance during micro-sliding for a long time. In contrast, in the case of Comparative Example 1-1, where the Ni content in the Sn-Ni plating layer of the plating material of the present invention exceeds the specified value, the plating layer is too hard, and the adhesion to the substrate is also reduced.

[0072] (summary) As is clear from the above embodiments and modifications, the present invention includes the following aspects. In the following, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments.

[0073] The first embodiment of the plating material (1) comprises a base material (10) mainly composed of copper, and a Sn-Ni plating layer (20) formed on the surface of the base material (10) and composed of a plurality of crystal grains (X). The average particle size of the plurality of crystal grains (X) is 1 μm or more and 10 μm or less. The Sn-Ni plating layer (20) contains a Sn phase, a Ni3Sn4 phase, and a NiSn phase. The Ni content in the Sn-Ni plating layer (20) is 2% by mass or more and 15% by mass or less.

[0074] According to the first embodiment, the plated material (1) can suppress an increase in contact resistance when used in a micro-sliding state.

[0075] In the second embodiment of the plated material (1), a Sn plated layer (30) is further formed on the Sn-Ni plated layer (20) in the first embodiment.

[0076] According to the second embodiment, the plated material (1) can improve solder wettability in addition to suppressing an increase in contact resistance during micro-sliding.

[0077] In the third embodiment of the plated material (1), a Ni plating layer (40) is further formed between the substrate (10) and the Sn-Ni plating layer (20) in the first or second embodiment.

[0078] According to the third embodiment, the plated material (1) can suppress not only the increase in contact resistance during fine sliding, but also the increase in contact resistance during high-temperature use.

[0079] In the fourth embodiment of the plated material (1), in any one of the first to third embodiments, the Sn-Ni plated layer (20) has a first region located closer to the substrate (10) than the center in the thickness direction, and a second region located on the opposite side from the first region than the center in the thickness direction. The Ni content in the first region is greater than the Ni content in the second region.

[0080] According to the fourth embodiment, the plated material (1) can further suppress the increase in contact resistance during micro-sliding.

[0081] In the fifth embodiment of the plating material (1), in any one of the first to fourth embodiments, the substrate (10) is composed of a plurality of crystal grains. The average grain size of the plurality of crystal grains is 0.3 μm or larger.

[0082] According to the fifth embodiment, the plated material (1) can further suppress the increase in contact resistance during micro-sliding. [Explanation of Symbols]

[0083] 1. Plating material 10 Base material 20 Sn-Ni plating layer 30 Sn plating layer 40 Ni plating layer

Claims

1. A base material mainly composed of copper, A Sn-Ni plating layer formed on the surface of the substrate and composed of multiple crystal grains Equipped with, The average grain size of the plurality of crystal grains is 1 μm or more and 10 μm or less. The Sn-Ni plating layer consists of a Sn phase and Ni ３ Sn ４ Including the NiSn phase, The Ni content in the Sn-Ni plating layer is 2% by mass or more and 15% by mass or less. Plating material.

2. The Sn-Ni plating layer is further comprising a Sn plating layer formed on the Sn-Ni plating layer. The plating material according to claim 1.

3. The substrate and the Sn-Ni plating layer are further comprising a Ni plating layer formed between them. The plating material according to claim 1 or 2.

4. The Sn-Ni plating layer has a first region located closer to the substrate than the center in the thickness direction, and a second region located on the opposite side from the first region than the center in the thickness direction. The Ni content in the first region is greater than the Ni content in the second region. The plating material according to claim 1 or 2.

5. The substrate is composed of a plurality of crystal grains, The average grain size of the plurality of crystal grains is 0.3 μm or larger. The plating material according to claim 1 or 2.

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