PLATED MATERIAL AND TERMINAL USING THIS PLATED MATERIAL

Abstract

A plated material includes a base metal made from Cu or an alloy containing Cu as a main raw material, an underlayer made from Ni formed on the base metal, and an Ag plated layer formed on the underlayer. A thickness of the underlayer is 0.1 μm to 1.0 μm. A thickness of the Ag plated layer is 1.0 μm or less.

Claims

1. A plated material comprising; a base metal made from Cu or an alloy containing Cu as a main raw material; an underlayer made from Ni forming on the base metal; and an Ag plated layer formed on the underlayer, wherein a thickness of the underlayer is 0.1 μm to 1.0 μm, and a thickness of the Ag plated layer is 1.0 μm or less.

2. The plated material according to claim 1, wherein the Ag plated layer has a surface Vickers hardness Hv of 65 or more, and has a contact resistance of 1 mΩ or less when a contact load of 1 N is applied after the plated material is left to stand about for a few days under a SO.sub.2 atmosphere.

3. A terminal, wherein the plated material according to claim 1 is used at least in a sliding portion.

4. The terminal according to claim 3, wherein a thickness of the base metal made from Cu or an alloy containing Cu as a main raw material is 0.15 mm to 0.8 mm.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0022] FIG. 1 is a schematic cross section showing a structure of a plated material according to an embodiment;

[0023] FIG. 2 is a schematic cross section showing the state of deposition of a corrosion product in a plated material according to an embodiment;

[0024] FIG. 3 is a table showing electric potential difference in the combinations of Ni, Cu and Ag;

[0025] FIG. 4 is a table showing the evaluation results and appearance of a plated material according to First Example;

[0026] FIG. 5 is a table showing the evaluation results and appearance of a plated material according to Second Example;

[0027] FIG. 6 is a table showing the evaluation results and appearance of a plated material according to Third Example;

[0028] FIG. 7 is a table showing the evaluation results and appearance of a plated material according to Comparative Example;

[0029] FIG. 8 is a table showing the ionization tendency of elements; and

[0030] FIGS. 9A to 9C are schematic cross sections showing the structures of plated materials according to conventional techniques.

DETAILED DESCRIPTION

Embodiment

[0031] By reference to FIGS. 1 to 3, the embodiment of the present invention will be described.

[Schematic Structure of Plated Material]

[0032] FIG. 1 is a schematic cross section showing a structure of a plated material 1 according to an embodiment, and FIG. 2 is a schematic cross section showing the state of deposition of a corrosion product 50 in a plated material 1.

[0033] FIG. 3 is a table showing electric potential difference in the combinations of Ni, Cu and Ag.

[0034] As shown in FIG. 1, in the plated material 1 according to the embodiment, a underlayer 11 made from Ni (nickel) and an Ag plated layer 12 are successively formed on a base metal 10 made from Cu (copper) or an alloy containing Cu as a main raw material.

[0035] The thickness (H1) of the underlayer 11 is 0.1 μm to 1.0 μm, and the thickness (H2) of the Ag plated layer 12 is 1.0 μm or less.

[0036] It is desired that the Ag plated layer 12 have a surface Vickers hardness Hv of 65 or more, and a contact resistance of 1 mΩ or less when a contact load of 1 N is applied after the plated material is left to stand about for a few days under a SO.sub.2 atmosphere. The specific evaluation results of examples will be described below.

[0037] By reference to the table showing electric potential difference in the combinations of Ni, Cu and Ag in FIG. 3, it is found that the electric potential difference of Ag—Ni is the largest, 1.057 V, in the combinations of other elements.

[0038] Therefore, a corrosion product of Ni (NiO.sub.3S) is generated first between the Ag plated layer 12 and the Ni underlayer 11 corresponding to the combination of Ag—Ni.

[0039] In the plated material 1 according to the embodiment, the thickness (H1) of the underlayer 11 is purposely made thin, 0.1 μm to 1.0 μm, and thus the amount of Ni used for the generation of the corrosion product (NiO.sub.3S) can be kept low.

[0040] In the plated material 1 according to the embodiment, the deposition of the corrosion product can be suppressed by such mechanism. Therefore, as shown in FIG. 2, even when the corrosion product (NiO.sub.3S) 50 is generated, the amount thereof reaching the surface 12a of the Ag plated layer 12 can be reduced.

[0041] Because of this, when the plated material 1 according to the embodiment is applied to a terminal, a situation in which the contact surface made of the surface 12a of the Ag plated layer 12 is covered with the corrosion product 50 and reduced can be suppressed, and good contact resistance can be maintained.

[0042] In addition, in the plated material 1 according to the embodiment, the Ag plated layer is not required to be thick, 5 μm or more, unlike conventional ones, and the amount of Ag (silver) used for plating can be reduced, and production costs can be lowered.

[0043] In addition, in the plated material 1 according to the embodiment, it is not required that a corrosion inhibitor with viscosity and an antitarnish agent be applied to surfaces, and thus the insertion-extraction force can be reduced, and the plated material can be also applied to a small terminal.

[Examples of Plated Material]

[0044] By reference to FIG. 4 to FIG. 6, examples (First Example to Third Example) of a plated material 1 according to the embodiment will be described.

[0045] FIG. 4 to FIG. 6 are tables showing the evaluation results and appearance of the plated materials according to First Example to Third Example, respectively.

[0046] As common evaluation conditions, a contact load of 1 N was applied after the plated material was left to stand about for a few days under a SO.sub.2 atmosphere.

[0047] The evaluation items are contact resistance (mΩ) in the initial state (the plot line B in graphs in each table) and in the final state (the plot line A in graphs in each table), and the observation of the state of the corrosion product by appearance.

[0048] The graphs in each table are about load-resistance characteristics, and show a relationship between contact resistance (mΩ) and contact load (N) on a log scale and a linear scale.

[0049] The surface Vickers hardness Hv of the Ag plated layer (outer plating) 12, which shows Ag purity, is 65, and the thickness of the Ag plated layer 12 (H2) is 1 μm.

First Example

[0050] First example shown in FIG. 4 is a case where the thickness of the Ni underlayer is 0.1 μm.

[0051] As can be seen from the log scale and the linear scale, the contact resistance is 1 mΩ or less when the contact load is 1 N.

[0052] As can be seen from the image showing its appearance, a corrosion product which can be confirmed visually cannot be observed.

[0053] An object which can be seen at almost center of the image is a projection made by embossing (the same applies to other examples). In addition, other objects in the image are impurities.

Second Example

[0054] Second example shown in FIG. 5 is a case where the thickness of the Ni underlayer 11 is 0.5 μm.

[0055] As can be seen from the log scale and the linear scale, the contact resistance is 1 mΩ or less when the contact load is 1 N.

[0056] As can be seen from the image showing its appearance, relatively small corrosion products (NiO.sub.3S) are observed; however, it can be said that the amount is extremely small compared to that in Comparative Example (FIG. 7) described below.

Third Example

[0057] Third example shown in FIG. 6 is a case where the thickness of the Ni underlayer 11 is 1 μm.

[0058] As can be seen from the log scale and the linear scale, the contact resistance is 1 mΩ or less when the contact load is 1 N.

[0059] As can be seen from the image showing its appearance, several corrosion products (NiO.sub.3S) are observed; however, similar to Second Example, it can be said that the amount thereof is extremely small compared to that in Comparative Example (FIG. 7) described below.

[Comparative Example of Plated Material]

[0060] By reference to FIG. 7, the plated material according to Comparative Example will be briefly described.

[0061] The evaluation conditions and the like are the same as in examples described above.

[0062] Comparative Example shown in FIG. 7 is a case where the thickness of the Ni underlayer 11 is 3 μm.

[0063] As shown in the graphs in FIG. 7, contact resistance cannot be maintained to 1 mΩ or less when the contact load is IN.

[0064] As can be seen from the image showing its appearance, a large number of big and small corrosion products (NiO.sub.3S) are observed in the plated material according to Comparative Example. Therefore, when the plated material according to Comparative Example is used for a terminal, there is a risk that a part of the terminal surface is covered with the corrosion products, and in this case, there is a difficulty in that the contact resistance of the terminal increases.

[0065] As described above, the plated materials according to First Example to Third Example show a contact resistance of 1 mΩ or less when a contact load of 1 N is applied after the plated materials are left to stand about for a few days under a SO.sub.2 atmosphere, and when applied to a terminal, good contact resistance can be secured.

[0066] Furthermore, in the plated materials according to First Example to Third Example, the deposition of the corrosion product (NiO.sub.3S) can be also kept to a relatively small amount.

[0067] Therefore, in the case where the plated materials according to First Example to Third Example are applied to a terminal, even when the corrosion product (NiO.sub.3S) 50 is generated as shown in FIG. 2 above, the amount thereof reaching the surface 12a of the Ag plated layer 12 can be reduced.

[0068] Because of this, a situation in which the contact surface made of the surface 12a of the Ag plated layer 12 is covered with the corrosion product 50 and reduced can be suppressed, and good contact resistance can be maintained in the terminal.

[Application to Terminals]

[0069] The plated material 1 according to the embodiment shown in First Example to Third Example can be widely applied to, for example, terminals for vehicles.

[0070] At this time, the plated material 1 according to the embodiment can be used at least in the sliding portion of the terminals. Because of this, good contact resistance can be maintained in the terminals.

[0071] When producing a terminal, the thickness of the base metal 10 made from Cu or an alloy containing Cu as a main raw material can be 0.15 mm to 0.8 mm.

[0072] The plated material of the present invention was described based on the embodiment shown in figures. It should be noted however that the present invention is not limited thereto, and the structure of each part can be substituted with an optional structure having the same function.