Metal material, connection terminal, and method for manufacturing metal material

Abstract

Provided are a metal material and a connection terminal capable of exerting the characteristics of In on a surface even when subjected to a high-temperature environment, and a method capable of producing such a metal material. A metal material 1 is provided, which has: a base material 2; an intermediate layer 3 containing at least Ni and covering a surface of the base material 2; and an In cover layer 4 composed of In or an In alloy not containing Ni other than inevitable impurities, which covers a surface of the intermediate layer 3 and is exposed on an outermost surface, and in which the content of In is greater than 7 / 3 times the content of Ni in terms of atomic number ratio in the total of the intermediate layer 3 and the In cover layer 4. In addition, a connection terminal is provided, which is configured to include the metal material 1, and in which the intermediate layer 3 and the In cover layer 4 are formed on a surface of the base material 1 at least at a contact portion that electrically contacts a counterpart conductive member.

Description

Technical Field

[0001] This disclosure relates to metallic materials, connecting terminals, and methods for manufacturing metallic materials. Background Technology

[0002] In electrical connection components such as connectors, a layer of In or an In alloy is sometimes formed on the surface of a substrate made of Cu or a Cu alloy. In is a very soft metal that exhibits solid lubricity. Therefore, by forming a metal layer containing In on the surface of the connector, the coefficient of friction of the surface is reduced, thereby reducing the force (insertion force) required for the connector to be inserted and engaged.

[0003] For example, Patent Document 1 discloses a terminal pair consisting of a male connector terminal and a female connector terminal, each having an indium layer on the outermost surface of a contact portion that is electrically in contact with each other, and the load applied to the contact portion is set to a predetermined value. Here, it is also disclosed that an intermediate layer made of nickel is provided between the indium layer and the surface of a copper or copper alloy substrate to suppress the diffusion of copper atoms from the substrate to the indium layer. As for the thickness of the indium layer, a range of 0.5 μm to 3 μm is cited, and as for the thickness of the Ni layer, a region of 2 μm or more is cited as a preferred region.

[0004] Patent Document 2 discloses a connector terminal in which a surface plating layer composed of In or an In-based alloy is formed on the surface of a base material made of Cu or a Cu alloy, and a hard plating layer harder than the surface plating layer is formed on the substrate of the surface plating layer. The hard plating layer is composed of an intermetallic compound of Cu and In, or an intermetallic compound containing elements such as Ni in addition to Cu and In. Furthermore, a base plating layer composed of Ni or a Ni alloy is also described on the substrate of the hard plating layer. Preferably, the thickness of the surface plating layer is in the range of 0.45 μm to 10 μm; the thickness of the hard plating layer is preferably in the range of 0.05 μm to 10 μm; and the thickness of the base plating layer is preferably in the range of 0.05 μm to 10 μm.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-35873

[0008] Patent Document 2: Japanese Patent Application Publication No. 2012-28139 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In recent years, there has been a greater demand for reduced insertion force in connector terminals compared to the past. For example, in the field of automotive connector terminals, with the electrification and increasing functionality of automobiles, connectors are becoming more multi-polarized, meaning the number of connector terminals in a single connector is constantly increasing. From this perspective, reducing the insertion force of each connector terminal, and thus the overall insertion force of the connector, is required to be lower than ever before. On the other hand, there is a demand for connector terminals that can withstand harsh operating conditions, even at high temperatures.

[0011] As disclosed in Patent Documents 1 and 2, if a metal material with an In layer on its surface is used to construct the connection terminal, low insertion force can be achieved through the solid lubricity of In. Furthermore, since In exhibits low contact resistance on its surface, the connection reliability of the connection terminal with an In layer on its surface is also excellent. However, even with a connection terminal having an In layer on its surface, the inherent characteristics of In, such as low insertion force and high connection reliability, may not be consistently maintained when used in high-temperature environments. For example, when the In contained in the In layer alloys with the base material and the underlying metal, the inherent characteristics of In may be compromised. Patent Documents 1 and 2, which disclose connection terminals with an In layer on their surface, do not mention placing the connection terminal in a high-temperature environment; therefore, it is unclear from the descriptions in these documents whether the characteristics of the In layer are fully utilized even when subjected to high temperatures.

[0012] Therefore, the objective is to provide a metallic material and a connecting terminal that can exhibit the properties of In even when subjected to high-temperature environments, as well as a method for manufacturing such a metallic material.

[0013] Methods for solving problems

[0014] The metallic material disclosed herein comprises: a substrate; an intermediate layer comprising at least Ni and covering the surface of the substrate; and an In capping layer composed of In or an In alloy, the In alloy being free of Ni other than unavoidable impurities, the In capping layer covering the surface of the intermediate layer and exposed on the outermost surface, wherein the In content, in atomic ratio, of the intermediate layer and the In capping layer is greater than 7 / 3 times that of Ni.

[0015] The connection terminals of this disclosure are configured to include the metal material, and at least at the contact portion that is in electrical contact with the mating conductive member, the intermediate layer and the In cover layer are formed on the surface of the substrate.

[0016] In the method for manufacturing the metallic material disclosed herein, a Ni raw material layer composed of Ni or a Ni alloy is formed on the surface of a substrate, wherein the Ni alloy does not contain In except for unavoidable impurities. Furthermore, an In raw material layer is formed with a thickness of 5.6 times or more of the Ni raw material layer, wherein the In raw material layer is composed of In or an In alloy, wherein the In alloy does not contain Ni except for unavoidable impurities.

[0017] Invention Effects

[0018] The metallic materials and connecting terminals disclosed herein are those that can exhibit the properties of In on their surface even when subjected to high-temperature environments. Furthermore, such metallic materials can be manufactured according to the manufacturing method disclosed herein. Attached Figure Description

[0019] [ Figure 1 ] Figure 1 A, B, and C are schematic diagrams representing the cross-sections of the metallic materials involved in the first, second, and third embodiments of this disclosure, respectively.

[0020] [ Figure 2 ] Figure 2 This is a cross-sectional view illustrating a connection terminal involved in one embodiment of the present disclosure.

[0021] [ Figure 3 ] Figure 3 This is a graph showing the relationship between the heating time at 150°C and the thickness of the In capping layer formed by heating for a metallic material obtained by stacking Ni and In raw material layers.

[0022] [ Figure 4 ] Figure 4 This is a graph showing the X-ray diffraction results of a metallic material obtained by stacking Ni and In raw material layers. The upper section shows the state of sample 1, with a thick In raw material layer, after heating; the middle section shows the state of sample 2, with a thin In raw material layer, after heating; and the lower section shows the unheated state of the reference sample. Detailed Implementation

[0023] [Description of the implementation of this disclosure]

[0024] First, the implementation methods of this disclosure will be described and illustrated.

[0025] The metallic material disclosed herein comprises: a substrate; an intermediate layer comprising at least Ni and covering the surface of the substrate; and an In capping layer composed of In or an In alloy, the In alloy being free of Ni except for unavoidable impurities, the In capping layer covering the surface of the intermediate layer and exposed on the outermost surface, wherein the In content, in atomic ratio, of the intermediate layer and the In capping layer is greater than 7 / 3 times that of Ni.

[0026] In the aforementioned metallic materials, by exposing an In coating layer on the outermost surface, the properties of In, such as reduced coefficient of friction and reduced contact resistance, can be utilized on the surface. The intermediate layer contains Ni, a metal that readily alloys with In at high temperatures. However, in the combined intermediate layer and In coating layer, the In content, in terms of atomic ratio, is greater than 7 / 3 times that of Ni. In and Ni readily form an intermetallic compound with a composition of Ni3In7. Because the region containing more In than the composition of this intermetallic compound is higher than that of Ni, even if alloying of In and Ni occurs at high temperatures, an In coating layer containing In that does not alloy with Ni remains on the surface of the metallic material. Even when the metallic material is subjected to high-temperature environments, the remaining In coating layer on the surface allows it to maintain the properties of In, resulting in a highly heat-resistant metallic material.

[0027] Here, a layer composed of Ni or a Ni alloy is defined as a Ni capping layer, wherein the Ni alloy does not contain In except for unavoidable impurities, and a layer composed of an alloy containing Ni and In is defined as an alloy layer. The intermediate layer can then have any of the following first, second, and third structures. In the first structure, the intermediate layer is composed of the Ni capping layer; in the second structure, the intermediate layer is composed of the Ni capping layer and the alloy layer covering the surface of the Ni capping layer; and in the third structure, the intermediate layer is composed of the alloy layer. When a metal material with an intermediate layer having the first structure is placed in a high-temperature environment, alloying between Ni and In occurs, forming a metal material with an intermediate layer having the second, and subsequently the third, structure. However, in the stage where the intermediate layer adopts any of the above three structures, if the In content, in terms of atomic ratio, is greater than 7 / 3 times that of Ni in the total of the intermediate layer and the In capping layer, an In capping layer containing In that has not formed an alloy with Ni remains on the surface of the metal material during this stage and further alloying stages.

[0028] In this case, the intermediate layer can have either the first structure or the second structure, and the thickness of the In capping layer can be more than 5.6 times the thickness of the Ni capping layer. The ratio of the thicknesses of the In capping layer and the Ni capping layer corresponds to a state where In is greater than 7 / 3 times the atomic number of Ni. Therefore, even when the metal material is placed in a high-temperature environment, alloying can be formed between the In constituting the In capping layer and the Ni constituting the Ni capping layer to form Ni3In7, an In capping layer containing In that has not formed an alloy with Ni can remain on the outermost surface of the metal material.

[0029] Furthermore, the intermediate layer may have either the first structure or the second structure, and the thickness of the Ni capping layer may be less than 1 μm. If the thickness of the Ni capping layer is about 1 μm, the diffusion of metal atoms from the substrate can be sufficiently suppressed. If feasible, the thickness of the Ni capping layer is preferably 0.5 μm or more. When the thickness of the Ni capping layer is 1 μm, if the thickness of the In capping layer is 6 μm or more, the atomic ratio of In to Ni becomes 7 / 3 times that of Ni. Therefore, without forming the capping layer too thick, when the metal material is placed in a high-temperature environment, an In capping layer containing In that has not alloyed with Ni can remain on the outermost surface of the metal material with a thickness sufficient to fully utilize the properties of In.

[0030] In these cases, the intermediate layer may have the first structure. In the first structure, the intermediate layer consists only of a Ni capping layer, and an In capping layer is formed by directly covering the surface of the Ni capping layer. Therefore, the In constituting the In capping layer is particularly prone to alloying with the Ni constituting the Ni capping layer, but because the In capping layer has a sufficiently large thickness relative to the Ni capping layer, even when the metal material is placed in a high-temperature environment, the In capping layer containing the unalloyed In can remain on the outermost surface.

[0031] Alternatively, the intermediate layer may have the second or third structure, and the alloy layer may contain an intermetallic compound called Ni3In7. By forming an intermediate layer containing Ni3In7 beneath the In capping layer, a high coefficient of friction reduction can be achieved on the surface of the In capping layer. Ni3In7 is an easily formed intermetallic compound as an alloy of Ni and In, and has a high In content ratio. However, as described above, by containing In in a sufficient number of atoms relative to Ni in the combined region of the intermediate layer and the In capping layer, even after the formation of the Ni3In7-containing alloy layer, the In capping layer containing unalloyed In remains exposed on the outermost surface of the metallic material.

[0032] Based on the total content per unit area of ​​the intermediate layer and the In capping layer, the Ni content can be 0.89 mg / cm³. 2 The following is an example of an In content of 4.3 mg / cm³. 2 The above. In terms of atomic ratio, the content of In and Ni corresponds to a state where In is greater than 7 / 3 times that of Ni.

[0033] The substrate can be made of Cu or a Cu alloy. Cu and Cu alloys are widely used as substrates for electrical connection components such as connectors due to their high machinability and mechanical properties. By exposing an In capping layer on its surface, it becomes suitable as a constituent material for electrical connection components. As an intermediate layer below the In capping layer, the diffusion of Cu atoms from the substrate into the In capping layer can be suppressed by providing a Ni capping layer and / or an alloy layer containing Ni and In.

[0034] The connection terminals involved in this disclosure are configured to include the metal material, and at least at the contact portion that is in electrical contact with the mating conductive member, the intermediate layer and the In cover layer are formed on the surface of the substrate.

[0035] In the aforementioned connection terminal, an intermediate layer and an In capping layer are formed on the surface of the contact portion, and the In content, in terms of atomic ratio, is greater than 7 / 3 times that of Ni in the total intermediate layer and In capping layer. Therefore, by utilizing the characteristics of In, such as low coefficient of friction and low contact resistance, the contact portion surface can be made into a connection terminal that excels in low insertion force and high connection reliability. Furthermore, even when subjected to high-temperature environments, the In capping layer, including In that is not alloyed with Ni, remains on the contact portion surface, thus stably maintaining these properties provided by In, resulting in a connection terminal with excellent heat resistance.

[0036] In the method for manufacturing the metallic material disclosed herein, a Ni raw material layer composed of Ni or a Ni alloy is formed on the surface of a substrate, wherein the Ni alloy does not contain In except for unavoidable impurities. Further, an In raw material layer is formed with a thickness of 5.6 times or more of the Ni raw material layer, wherein the In raw material layer is composed of In or an In alloy, wherein the In alloy does not contain Ni except for unavoidable impurities.

[0037] In the above-described method for manufacturing the metallic material, the thickness of the In material layer formed on the surface of the Ni material layer is set to be at least 5.6 times the thickness of the Ni material layer. This thickness ratio means that the In content in the In material layer is greater than 7 / 3 times the Ni content in the Ni material layer in terms of atomic number. Ni and In are metals that readily alloy when heated, forming an intermetallic compound called Ni3In7. However, by forming the In material layer at the aforementioned thickness ratio relative to the Ni material layer, even when the metallic material with the Ni and In material layers stacked is placed in a high-temperature environment, an In coating layer containing In that is not alloyed with Ni remains on the outermost surface of the metallic material. As a result, a metallic material is produced that can exhibit the properties of In on its surface even when subjected to high-temperature environments.

[0038] Here, the thickness of the Ni raw material layer can be set to 1 μm or less. If the thickness of the Ni raw material layer is about 1 μm, the diffusion of metal atoms from the substrate can be sufficiently suppressed. If feasible, the thickness of the Ni raw material layer is preferably 0.5 μm or more. When the thickness of the Ni raw material layer is 1 μm, if the thickness of the In raw material layer is 6 μm or more, it corresponds to a state where In is greater than 7 / 3 times Ni in terms of the atomic ratio of In to Ni. Therefore, when the capping layer is formed without being too thick, when the metal material is placed in a high-temperature environment, an In capping layer containing In that has not alloyed with Ni can remain on the outermost surface of the metal material with a thickness that can fully utilize the properties of In.

[0039] [Details of the implementation of this disclosure]

[0040] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. In this specification, unless otherwise specified, the content (concentration) of each element is expressed on a atomic basis, for example, atomic %. Furthermore, elemental metals may contain unavoidable impurities. Unless otherwise specified, alloys include both solid solutions and intermetallic compounds. An alloy with a certain metal as its main component refers to an alloy in which the content of that metal element in its composition is 50 atomic % or more.

[0041] <Metallic Materials>

[0042] The following describes the metal materials involved in the embodiments of this disclosure. The metal materials involved in the embodiments of this disclosure can be used to construct the connection terminals involved in the embodiments of this disclosure described later. Furthermore, the metal materials involved in the embodiments of this disclosure can be manufactured using the manufacturing method of the metal materials involved in the embodiments of this disclosure.

[0043] (An overview of the composition of metallic materials)

[0044] First, an overview of the metallic materials involved in the embodiments of this disclosure will be described. For example, a structural example will be shown later. Figure 1 As shown in A to 1C, the metal material 1 according to the embodiments of this disclosure has an intermediate layer 3 and an In capping layer 4 on the surface of a substrate 2. The intermediate layer 3 is provided such that it covers the surface of the substrate 2, and the In capping layer 4 is provided such that it covers the intermediate layer 3 and is exposed on the outermost surface.

[0045] The In capping layer 4 is composed of In or an In alloy that does not contain Ni other than unavoidable impurities. Here, an In alloy that does not contain Ni other than unavoidable impurities refers to an alloy that contains other metals besides In, but does not contain more than a certain amount of Ni that can be considered unavoidable impurities. Preferably, from the viewpoint of strongly expressing the characteristics of In, the In capping layer 4 can be composed of In. When the In layer is composed of an In alloy, it can also be an alloy with In as the main component.

[0046] Intermediate layer 3 is a metal layer containing at least Ni. There are no particular restrictions on the specific structure and composition of intermediate layer 3, but in the total of intermediate layer 3 and the aforementioned In capping layer 4, the In content, in terms of atomic ratio, is greater than 7 / 3 times that of Ni ([In] / [Ni] > 7 / 3). As in the first embodiment listed below, intermediate layer 3 may substantially contain no In, or as in the second and third embodiments, it may contain In in addition to Ni. Furthermore, intermediate layer 3 may contain metal elements other than Ni and In, but the combined content of Ni and In is preferably 50 atomic percent or more. In particular, intermediate layer 3 may not contain any metal elements other than Ni that can form alloys with In, and it is further preferred that it does not contain any metal elements other than Ni and In except for unavoidable impurities.

[0047] The intermediate layer 3 can consist of a single layer or a stacked structure consisting of two or more layers. Furthermore, multiple phases can be spatially and non-uniformly mixed within the layers of the intermediate layer 3. As preferred embodiments of the intermediate layer 3, three structures, namely the first, second, and third embodiments, are illustrated below.

[0048] In the metal material 1, other metal layers can be provided between the substrate 2 and the intermediate layer 3, between the multiple layers constituting the intermediate layer 3, and between the intermediate layer 3 and the In capping layer 4. However, from the viewpoint of simplicity in the composition and manufacturing process of the metal material 1, it is preferable not to provide these other metal layers and instead provide the substrate 2 and the intermediate layer 3, the multiple layers constituting the intermediate layer 3, and the intermediate layer 3 and the In capping layer 4 in direct contact. As long as it does not significantly affect the characteristics of the In capping layer 4, a thin film such as an organic layer (not shown) can be provided on the surface of the In capping layer 4.

[0049] There are no particular restrictions on the material constituting the substrate 2. Preferably, Cu or Cu alloys, Al or Al alloys, or Fe or Fe alloys, which are commonly used as constituent materials for electrical connection components, can be used as the substrate 2. Among these, Cu or Cu alloys with excellent processability and mechanical properties are preferred. At the interface between the substrate 2 and the intermediate layer 3, the metal constituting the substrate 2 and the metal constituting the intermediate layer 3 can form an alloy.

[0050] (First method)

[0051] exist Figure 1 Figure A shows the layer structure of the metal material 1A involved in the first embodiment. In this metal material 1A, the intermediate layer 3 has a single-layer structure composed of a Ni capping layer 3a. That is, the Ni capping layer 3a is formed to directly cover the surface of the substrate 2, and the In capping layer 4 is formed to directly cover the surface of the Ni capping layer 3a.

[0052] The Ni capping layer 3a is composed of Ni or a Ni alloy, wherein the Ni alloy does not contain In other than unavoidable impurities. Here, a Ni alloy not containing In other than unavoidable impurities refers to an alloy that contains other metals besides Ni, but does not contain more than an amount of In that can be considered an unavoidable impurity. Preferably, the Ni capping layer 3a may be composed of Ni.

[0053] (Second method)

[0054] exist Figure 1 Figure B shows the layer structure of the metal material 1B involved in the second embodiment. In this metal material 1B, the intermediate layer 3 has a two-layer structure consisting of a Ni capping layer 3a and an alloy layer 3b. That is, the Ni capping layer 3a is formed to cover the surface of the substrate 2, and the alloy layer 3b is formed to cover the surface of the Ni capping layer 3a. In addition, an In capping layer 4 is formed to cover the surface of the alloy layer 3b.

[0055] The Ni capping layer 3a has the same composition as the Ni capping layer 3a contained in the metallic material 1A described in the first aspect above. The alloy layer 3b is composed of an alloy containing Ni and In. Preferably, the alloy layer 3b can be formed as a layer in which a Ni-In alloy is the main component, and further as a layer composed only of Ni-In alloy except for unavoidable impurities.

[0056] There are no particular limitations on the composition of the Ni-In alloy contained in the alloy layer 3b. As an alloy of Ni and In, intermetallic compounds with a composition of Ni3In7 are easily formed, and the alloy layer 3b in this embodiment preferably contains Ni3In7. Furthermore, the Ni-In alloy contained in the intermediate layer 3 may have Ni3In7 as the main component, and more preferably, except for unavoidable components, the entire Ni-In alloy contained in the alloy layer 3b is composed of Ni3In7.

[0057] Ni and In are metals that readily form alloys, especially when heated. Therefore, when the metal material 1A described above, which has a Ni capping layer 3a and an In capping layer 4 stacked together, is placed in a high-temperature environment, alloying occurs at the interface between the Ni capping layer 3a and the In capping layer 4, easily forming the metal material 1B described in the second embodiment.

[0058] (Third method)

[0059] exist Figure 1 Figure C shows the layer structure of the metal material 1C involved in the third embodiment. In this metal material 1C, the intermediate layer 3 has a single-layer structure composed of an alloy layer 3b. That is, the alloy layer 3b is formed to directly cover the surface of the substrate 2, and the In cover layer 4 is formed to directly cover the surface of the alloy layer 3b. The alloy layer 3b has the same composition as the alloy layer 3b contained in the metal material 1B involved in the second embodiment described above.

[0060] When the metal material 1A described above, which has a Ni capping layer 3a and an In capping layer 4, is placed in a high-temperature environment, portions of Ni and In are alloyed to form the metal material 1B described in the second embodiment, in which an alloy layer 3b is formed between the Ni capping layer 3a and the In capping layer 4. When the metal material 1B of the second embodiment is placed in a high-temperature environment for a longer period of time, alloying is further carried out, and all the Ni constituting the Ni capping layer 3a is alloyed with In, easily forming the metal material 1C described in the third embodiment.

[0061] (Properties of metallic materials)

[0062] Represented by the metal materials 1A, 1B, and 1C described above in the first, second, and third embodiments, the metal material 1 in the embodiments of this disclosure has an In coating layer 4 on its outermost surface. Therefore, the properties of In can be utilized on the outermost surface of the metal material 1. In is a very soft metal and has solid lubricity. Therefore, the surface of the In coating layer 4 exhibits a low coefficient of friction. Therefore, when the metal material 1 in the embodiments of this disclosure is used as a constituent material for components that slide with other components, such as connecting terminals, the force required for sliding can be minimized. In the case of connecting terminals, the force required for insertion and engagement of the connecting terminals, i.e., the insertion force, can be minimized. Furthermore, In is a highly conductive metal, and even if the outermost surface is oxidized, the oxide film is easily destroyed by applying loads, etc. Therefore, when the metal material 1 in the embodiments of this disclosure is used as a constituent material for electrical connection components such as connecting terminals, the contact resistance on the surface of the In coating layer 4 can be minimized, and high connection reliability can be obtained.

[0063] The Ni capping layer 3a, composed of Ni or a Ni alloy, and the alloy layer 3b, composed of an alloy containing Ni and In, are sandwiched between the In capping layer 4 and the substrate 2, acting as diffusion inhibition layers to suppress the diffusion of metals constituting the substrate 2, such as Cu, into the In capping layer 4. Thus, the formation of an alloy between the metal constituting the substrate 2 and In within the In capping layer 4 is suppressed, and the diffusion of the metal constituting the substrate 2 to the outermost surface and the formation of oxides is also suppressed, thereby reducing the contact resistance.

[0064] In the metallic material 1 described in the embodiments of this disclosure, the In content, in the total of the intermediate layer 3 and the In capping layer 4, is greater than 7 / 3 times, or 2.33 times, of Ni in terms of atomic ratio. In is a metal that readily alloys with Ni, especially at high temperatures. Therefore, when the metallic material 1 is placed in a high-temperature environment, the In contained in the In capping layer 4 may alloy with the Ni contained in the underlying intermediate layer 3. As an alloy of In and Ni, an intermetallic compound Ni3In7 is readily formed, and the amount of In that is neither excessive nor insufficient when alloying with Ni is 7 / 3 times that of Ni in terms of atomic ratio. However, in the metal material 1 according to the embodiments of this disclosure, since the total In atom content of the intermediate layer 3 and the In capping layer 4 is greater than 7 / 3 times that of Ni atom content, even assuming that all the Ni contained in the intermediate layer 3 alloys with the In constituting the In capping layer 4 and / or the In contained in the intermediate layer 3 (alloy layer 3b) to form Ni3In7, the remaining In that is not alloyed with Ni will remain in the form of the In capping layer 4. That is, in the metal material 1 according to the embodiments of this disclosure, even if In and Ni are alloyed under high temperature conditions, an In capping layer 4 remains on the outermost surface.

[0065] As a result, even when the metal material 1 is subjected to a high-temperature environment, it can still enjoy the properties exerted by In on its surface, namely, low coefficient of friction, low contact resistance, and low insertion force and high connection reliability when used as a connection terminal. That is, the metal material 1 becomes highly heat-resistant. If, when subjected to a high-temperature environment, the In coating layer 4 does not remain on the outermost surface of the metal material and the alloy layer 3b is exposed, then because the alloy containing Ni and In is hard, it will not exhibit the excellent solid lubricity and low contact resistance of In. Therefore, compared with before being subjected to a high-temperature environment, the applicability of the surface of the metal material as an electrical connection component such as a connection terminal is reduced.

[0066] It should be noted that, as an alloy of In and Ni, besides Ni3In7, intermetallic compounds composed of NiIn, Ni2In, and Ni3In are also known. However, among these intermetallic compounds, Ni3In7 has the highest proportion of In relative to Ni. Therefore, in metallic material 1, by ensuring that the total In atom content of the intermediate layer 3 and the In capping layer 4 is greater than 7 / 3 times that of Ni atoms, even if intermetallic compounds other than Ni3In7 are formed during high-temperature environments, an In capping layer 4 can remain on the outermost surface of metallic material 1.

[0067] From the perspective of ensuring a sufficiently thick In capping layer 4 remains when subjected to high-temperature environments, it is further preferred that the In content, in terms of atomic ratio, is 2.4 times or more than 3.0 times that of Ni in the total of the intermediate layer 3 and the In capping layer 4. There is no particular upper limit on the In content based on Ni, but from the perspective of avoiding the use of excessive In, for example, the In content, in terms of atomic ratio, in the total of the intermediate layer 3 and the In capping layer 4 can be set to less than 4 times that of Ni.

[0068] Especially in the metal material 1A involved in the first method, since the Ni capping layer 3a and the In capping layer 4 are formed adjacent to each other, alloying of Ni and In is easy to carry out at high temperatures. When the alloying of Ni and In reaches a certain extent, as in the metal material 1B involved in the second method, a portion of the Ni constituting the Ni capping layer 3a forms a Ni-In alloy, and an alloy layer 3b is formed between the Ni capping layer 3a and the In capping layer 4. When the alloying proceeds further, as in the metal material 1C involved in the third method, all the Ni constituting the Ni capping layer 3a forms a Ni-In alloy, causing the alloy layer 3b to grow. However, in the metal material 1A involved in the first method, since the In atoms constituting the In capping layer 4 are 7 / 3 times more numerous than the Ni atoms constituting the Ni capping layer 3a, even if alloying is carried out, it will be in the form of the metal materials 1B and 1C involved in the second and third methods, such as... Figure 1 As shown in B and 1C, an In capping layer 4 containing In that has not formed an alloy with Ni remains on the outermost surface.

[0069] In the metal material 1B involved in the second method, alloying of Ni and In may further proceed under high-temperature conditions. In this case, as with the metal material 1C involved in the third method, all the Ni constituting the Ni capping layer 3a forms a Ni-In alloy, constituting the alloy layer 3b. However, in the metal material 1B involved in the second method, the total number of In atoms contained in the In capping layer 4 and the alloy layer 3b is more than 7 / 3 times the number of Ni atoms constituting the Ni capping layer 3a and the alloy layer 3b. Therefore, even if further alloying is carried out, it will still take the form of the metal material 1C involved in the third method, such as... Figure 1 As shown in Figure C, an In capping layer 4 containing In that has not formed an alloy with Ni remains on the outermost surface.

[0070] In the third approach, since the intermediate layer 3 of the metal material 1C does not contain a Ni capping layer 3a, further alloying is essentially not carried out, and the In capping layer 4 formed on the outermost surface remains unchanged even after exposure to high-temperature environments. Alternatively, in the already formed alloy layer 3b, even if a conversion occurs from intermetallic compounds with a low In-to-Ni ratio, such as NiIn, Ni2In, and Ni3In, to intermetallic compounds with a high In ratio, such as Ni3In7, the outermost surface will still have an In capping layer 4.

[0071] When the metal materials 1B and 1C involved in the second and third embodiments are formed by alloying the metal material 1A involved in the first embodiment, the alloy layer 3b is not actively formed. However, in the metal material 1 involved in the embodiments of this disclosure, as at least part of the intermediate layer 3, an alloy layer 3b composed of an alloy containing Ni and In can be actively formed. As an effect of setting the intermediate layer 3, the presence of a hard alloy layer 3b under the soft In capping layer 4 can be cited as an example of improving the coefficient of friction reduction of the surface of the In capping layer 4.

[0072] When the density based on In is 7.31 g / cm³ 3 The density of Ni is 8.91 g / cm³. 3 When the atomic ratio of In being greater than 7 / 3 times that of Ni is converted into the thickness ratio of the elemental In layer to the elemental Ni layer, the thickness of the In layer is greater than 5.55 times the thickness of the Ni layer. Therefore, in the first and second embodiments involving metal materials 1A and 1B with the intermediate layer 3 containing the Ni capping layer 3a, when the thickness of the In capping layer 4 is pre-set to be 5.6 times, 6.0 times, or 7.0 times the thickness of the Ni capping layer 3a, even under high-temperature conditions, the In capping layer 4, containing In that which is not alloyed with Ni, can reliably remain on the outermost surface of the metal materials 1A and 1B. In particular, in the case of the first embodiment involving metal material 1A where there is no alloying between the In capping layer 4 and the Ni capping layer 3a, the Ni capping layer 3a and the In capping layer 4 are adjacent, and alloying is easily performed under high-temperature conditions. If the above-mentioned thickness ratio is used, even after alloying, the In capping layer 4 can remain on the surface of the metal material 1A.

[0073] In the metal materials 1A and 1B involved in the first and second embodiments, there is no particular limitation on the specific thickness of the In capping layer 4 and the Ni capping layer 3a. However, from the viewpoint of suppressing the diffusion of the substrate metal and improving the effect of forming the Ni capping layer 3a on the surface of the substrate 2, the thickness of the Ni capping layer 3a is preferably set to 0.5 μm or more, for example. Furthermore, even if the thickness of the Ni capping layer 3a is 1 μm or less, it will still have a high effect on suppressing the diffusion of the substrate metal. For example, it is possible to set the thickness of the Ni capping layer 3a to 1 μm or less and the thickness of the In capping layer 4 to 6 μm or more. When the thickness of the Ni capping layer 3a is 1 μm or less, the properties of In can be effectively utilized on the surface of the metal materials 1A and 1B by having the In capping layer 4 to a thickness of 6 μm or more. These thicknesses are particularly preferred in the metal material 1A involved in the first embodiment, where no alloying occurs between the In capping layer and the Ni capping layer 3a. Therefore, even when the metal material 1A is placed in a high-temperature environment for alloying between In and Ni, the In capping layer 4 can easily remain on the outermost surface with a thickness sufficient to effectively utilize the properties of In. No specific upper limit is specified for the thickness of the In capping layer 4, but from the viewpoint of avoiding excessive thickness, it is preferably set to 10 μm or less, for example.

[0074] Based on the aforementioned Ni and In densities, when the thicknesses of the exemplified Ni capping layer 3a (less than 1 μm) and In capping layer 4 (more than 6 μm) are converted to the Ni and In content per unit area in the combined area of ​​the intermediate layer 3 and In capping layer 4, the Ni content is 0.89 mg / cm³. 2 The following is an example of an In content of 4.3 mg / cm³. 2 The above. In the metal materials 1A, 1B, and 1C involved in the first, second, and third methods, if the thickness of the intermediate layer 3 and the In capping layer 4 is set in a manner that satisfies these ranges, then even when subjected to high-temperature environments, the In capping layer 4, which contains In that has not formed an alloy with Ni, can be reliably retained on the outermost surface of the metal materials 1A, 1B, and 1C.

[0075] <Methods for Manufacturing Metallic Materials>

[0076] There are no particular limitations on the manufacturing method of the metal material 1 involved in the embodiments of this disclosure, and a manufacturing method corresponding to the specific structure of the intermediate layer 3 can be applied.

[0077] For example, the metal material 1A described in the first method above can be manufactured by sequentially forming a Ni raw material layer and an In raw material layer on the surface of a substrate 2. The Ni raw material layer is a layer composed of Ni or a Ni alloy that does not contain In other than unavoidable impurities, and in the manufactured metal material 1A, it directly becomes the Ni capping layer 3a. The In raw material layer is a layer composed of In or an In alloy that does not contain Ni other than unavoidable impurities, and in the manufactured metal material 1A, it directly becomes the In capping layer 4. There are no particular limitations on the method of forming the Ni raw material layer and the In raw material layer, and plating is preferred.

[0078] In this manufacturing process, the thickness of the In raw material layer is preset to be at least 5.6 times the thickness of the Ni raw material layer. Therefore, the In used as a raw material is more than 7 / 3 times the atomic number of Ni. Consequently, when the metal material 1A manufactured according to the first method is placed in a high-temperature environment, even if alloying occurs between Ni and In, the In capping layer 4, including In not alloyed with Ni, remains on the outermost surface. Specifically, the thickness of the Ni raw material layer can be set to 1 μm or less, or, if feasible, 0.5 μm or more, and the thickness of the In raw material layer can be set to 6 μm or less.

[0079] The metal material 1B involved in the second method is manufactured using the metal material 1A involved in the first method as raw material. That is, by placing the metal material 1A involved in the first method in a high-temperature environment such as above 150°C during storage and use, alloying is performed between the Ni constituting the Ni capping layer 3a and the In constituting the In capping layer 4, forming an alloy layer 3b containing a Ni-In alloy between the Ni capping layer 3a and the In capping layer 4. The metal material 1B involved in the second method is generated through the formation of this alloy layer 3b.

[0080] The metal material 1C involved in the third method is manufactured using either the metal material 1A involved in the first method or the metal material 1B involved in the second method as raw materials. As described above, by placing the metal material 1A involved in the first method in a high-temperature environment such as above 150°C during storage and use, the alloying of Ni and In is carried out, resulting in the metal material 1B involved in the second method, which has an alloy layer 3b between the Ni capping layer 3a and the In capping layer 4. However, when the metal material 1B involved in the second method is placed for a longer period of time or in a higher-temperature environment, the alloying between Ni and In is further carried out, and all the Ni constituting the Ni capping layer 3a is consumed in the alloying with In. As this alloying proceeds, the alloy layer 3b grows, and the Ni capping layer 3a disappears, resulting in the metal material 1C involved in the third method, where the intermediate layer 3 is composed only of the alloy layer 3b.

[0081] In this way, the alloy layer 3b contained in the metal materials 1B and 1C involved in the second and third methods is not intentionally formed. In the metal material 1A involved in the first method, it is formed naturally by alloying from the interface between the Ni capping layer 3a and the In capping layer 4. However, as mentioned above, considering that the presence of a hard alloy layer 3b can help reduce the coefficient of friction of the surface of the In capping layer 4, and also from the viewpoint of avoiding changes in the state of the metal material 1 over time due to the alloying process during its use, the alloy layer 3b can be intentionally formed. For example, after forming the metal material 1A involved in the first method as a raw material, the metal material 1B involved in the second method or the metal material 1C involved in the third method can be manufactured by intentionally heating it to promote the formation of the alloy layer 3b. Alternatively, the alloy layer 3b can be formed separately on the surface of the Ni capping layer 3a by alloy plating or the like, and then the In capping layer 4 can be formed.

[0082] <Connecting Terminals>

[0083] Next, the connection terminal according to the embodiments of this disclosure will be described. The connection terminal according to this embodiment is configured to include the metal material 1 according to the embodiments of this disclosure described above, such as any one of the metal materials 1A, 1B, and 1C according to the first, second, and third embodiments. The area including at least the contact portion that makes electrical contact with the mating conductive member can be made of the metal material 1 according to the embodiments of this disclosure. Moreover, at least at the contact portion, an intermediate layer 3 and an In cover layer 4 are formed on the surface of the substrate 2. On the surface of the connection terminal, as long as the intermediate layer 3 and the In cover layer 4 are formed in this stacking order at least at the contact portion, the intermediate layer 3 and the In cover layer 4 can each cover the entire surface of the connection terminal, or they can cover only a portion of the area.

[0084] There are no particular restrictions on the specific type or shape of the connection terminals. Figure 2In this embodiment of the present disclosure, an example of a connector terminal is shown: a female connector terminal 20. The female connector terminal 20 has the same shape as a known mating female connector terminal. Specifically, a clamping portion 23 is formed in a cylindrical shape with an opening at the front, and an elastic contact piece 21 with a shape that folds inward and backward is provided on the inner side of the bottom surface of the clamping portion 23. When a tab-shaped male connector terminal 30 is inserted into the clamping portion 23 of the female connector terminal 20 as a mating conductive member, the elastic contact piece 21 of the female connector terminal 20 contacts the male connector terminal 30 at a protrusion 21a that bulges inward toward the clamping portion 23, applying an upward force to the male connector terminal 30. The surface of the top plate of the clamping portion 23 opposite to the elastic contact piece 21 becomes the inner opposing contact surface 22. The male connector terminal 30 is pressed against the inner opposing contact surface 22 by the elastic contact piece 21, thereby clamping and holding the male connector terminal 30 within the clamping portion 23.

[0085] The female connector terminal 20 is entirely constructed of a metal material 1 having an intermediate layer 3 and an In cover layer 4 as described in the above embodiment. Here, the surfaces of the metal material 1 with the intermediate layer 3 and the In cover layer 4 are arranged facing the inside of the clamping portion 23, forming opposing surfaces of the elastic contact piece 21 and the inner opposing contact surface 22, with the In cover layer 4 exposed on the outermost surface of these surfaces. As a result, when the male connector terminal 30 is inserted into the clamping portion 23 of the female connector terminal 20 and slid to form an electrical connection, the contact portion between the female connector terminal 20 and the male connector terminal 30 exhibits the effect of reduced insertion force and high connection reliability due to the In cover layer 4. Furthermore, even when the female connector terminal 20 is placed in a high-temperature environment, the In cover layer 4 remains on the outermost surface, maintaining these characteristics provided by the In cover layer 4.

[0086] The above description describes the female connector terminal 20 as being entirely composed of a metal material 1 having an intermediate layer 3 and an In cover layer 4. The intermediate layer 3 and the In cover layer 4 can be formed in any range, as long as they are formed at least on the surfaces of the contact portions that contact the mating conductive members, i.e., the protrusions 21a of the elastic contact piece 21 and the surfaces of the inner opposing contact surfaces 22. In addition to the mating female connector terminals or male connector terminals described above, the connection terminals involved in the embodiments of this disclosure can also be various forms such as press-fit terminals that are press-fitted to through-holes formed on a printed circuit board. The various connection terminals involved in the embodiments of this disclosure can, for example, be housed in a connector housing made of insulating material and used as a connector. Alternatively, the connector can be connected to the end of a wire and used as a wire harness. Preferably, it can be manufactured as a multi-pole connector in which multiple connection terminals involved in the embodiments of this disclosure are housed in a common connector housing.

[0087] The connectors described in this disclosure are suitable for high-temperature environments, such as those inside automobiles. In recent years, the automotive industry has seen a trend towards multi-polar connectors, and from the viewpoint of minimizing the insertion force of the connector as a whole, low insertion force is required for each of the multiple connectors included in the connector. Furthermore, many areas inside automobiles experience high temperatures, necessitating high heat resistance for the connectors. Therefore, the connectors described in this disclosure can be appropriately used in automobiles, where the In cover layer 4 provides low insertion force and high connection reliability, and these In-derived characteristics are maintained even at high temperatures.

[0088] Example

[0089] The following describes embodiments. It should be noted that the present invention is not limited to these embodiments. Here, the metal material involved in the first embodiment described above, having a Ni capping layer and an In capping layer on the surface of a substrate, was used to verify changes when placed in a high-temperature environment. Hereinafter, unless otherwise stated, the preparation and evaluation of samples were carried out in the atmosphere at room temperature.

[0090] <Sample Preparation>

[0091] A Ni layer and an In layer were sequentially formed on the surface of a copper alloy substrate by electroplating. As a test sample, the thickness of the Ni layer was set to 1 μm and the thickness of the In layer to 1.5 μm, and a verification sample for verifying the alloying speed was prepared as described below. Furthermore, for the separate identification of the crystal layer after heating, three different samples were prepared with varying thicknesses of the Ni and In layers.

[0092] ■ Sample 1 - Ni layer thickness: 1.16 μm, In layer thickness: 9.20 μm (atomic ratio [In] / [Ni] = 3.30)

[0093] ■ Sample 2-Ni layer thickness: 1.01 μm, In layer thickness: 1.25 μm (atomic ratio [In] / [Ni] = 0.519)

[0094] ■ Reference sample - Ni layer thickness: 1.0 μm, In layer thickness: 0.5 μm (atomic ratio [In] / [Ni] = 0.21)

[0095] <Evaluation Methods>

[0096] (1) Alloying speed

[0097] The verification sample prepared above was placed in a constant temperature bath at 150°C. After a predetermined time, it was removed from the constant temperature bath, and only the In layer was peeled off. The In content in the alloy was then measured using a fluorescence X-ray film thickness gauge to estimate the thickness of the In layer that forms the alloy with Ni (the thickness of the In layer consumed in alloy formation). The heating time in the constant temperature bath was varied, and the relationship between the heating time and the thickness of the In layer formed in the alloy was evaluated.

[0098] (2) Identification of the crystal layer after heating

[0099] Samples 1 and 2, prepared as described above, were heated in a constant temperature bath at 150°C for 210 hours. X-ray diffraction (XRD) measurements were then performed on the heated samples 1 and 2, as well as on the unheated reference sample. CuKα rays were used as the XRD source, and the θ-2θ method was employed. The incident angle was set to 1°, and the measurement range was set to 5°–80°.

[0100] <Evaluation Results>

[0101] (1) Alloying speed

[0102] exist Figure 3 The figure shows the relationship between heating time (horizontal axis) at 150°C and the thickness of the In layer forming the alloy (vertical axis). According to the figure, the thickness of the In layer forming the alloy increases linearly with increasing heating time. An approximate linear relationship is also shown in the figure, but it is very close to the data points. This indicates that in the Ni and In layer stack structure, the alloying of Ni and In proceeds at a rate that can be considered constant. In the initial state without heating (heating time is zero), the thickness of the In layer forming the alloy is almost zero, and almost no alloying of Ni and In occurs.

[0103] With the heating time set to t hours and the thickness of the In layer forming the alloy set to L μm, the approximate straight line in the figure is represented by the approximate formula L = 0.0492t + 0.0814. Next, in the experiment representing result (2), samples 1 and 2 were heated at 150°C for 210 hours. When this 210-hour heating time was applied to t in the above approximate formula, the thickness L of the In layer forming the alloy was 10.33 μm. This result was confirmed to be larger than the thickness of the In layer in samples 1 and 2, and the 210-hour heating time was sufficiently long as the time for alloying all Ni in samples 1 and 2.

[0104] (2) Identification of the crystal layer after heating

[0105] exist Figure 4The figure shows the XRD results obtained from the conditions of samples 1 and 2 after heating at 150°C for 210 hours, and from the reference sample which was kept at room temperature without heating. The horizontal axis represents 2θ (unit: degrees), and the vertical axis represents the intensity of diffracted X-rays (arbitrary units). The upper section represents sample 1 after heating, the middle section represents sample 2 after heating, and the lower section represents the unheated reference sample. For the reference sample, since a thinner In layer is formed than that of samples 1 and 2, the peak from Ni is stronger, so the scale of the vertical axis is set to 0.5 times. In the figure, the peak positions corresponding to the crystals of various metals are represented by symbols according to information from the database. Hollow circles (〇) represent In, black circles (●) represent Ni3In7, triangles (△) represent Ni, and squares (□) represent Cu.

[0106] exist Figure 4 First, the measurement results of the reference sample that has not undergone heating are observed (below). In the reference sample, in addition to the Cu peak of the substrate, the In and Ni peaks appear with high intensity. The Ni3In7 peak appears, but its overall intensity is smaller compared to the In and Ni peaks. Thus, in the unheated Ni and In layer stacked structure, as shown by the data point where the heating time in the above (1) test is zero, only a small amount of alloying between Ni and In has occurred. Moreover, it can be confirmed that most of the Ni layer stacked as Ni is in the state of elemental Ni, and most of the In layer stacked as In is in the state of elemental In.

[0107] Next, the measurement results of sample 2 after heating were observed. In the heated sample 2 (middle section), no peaks belonging to elemental In crystals (○) were observed. Although peaks belonging to elemental Ni crystals (△) were observed, their intensity was low. On the other hand, compared to the Ni peaks, peaks belonging to Ni3In7 were observed with a large overall intensity (●). From this result, it can be concluded that in sample 2, alloying occurred between the stacked In and Ni layers, forming Ni3In7, and the elemental In layer disappeared. In sample 2, the atomic ratio of In to Ni was [In] / [Ni] = 0.519, which is much smaller than the atomic ratio of 2.33 corresponding to the composition of Ni3In7 (In is less than Ni). Therefore, it is considered that all the In constituting the In layer was alloyed with Ni, forming Ni3In7.

[0108] On the other hand, in the measurement results of sample 1 after heating (upper section), peaks belonging to elemental In (○) and Ni3In7 (●) were observed. The peak belonging to elemental Ni (△) did not appear at intensities above the detection limit. This result indicates that in sample 1, alloying occurred between the stacked In and Ni layers to form Ni3In7, but even after this alloying, unconsumed elemental In remained during alloy formation. It can be assumed that Ni was completely consumed during alloying. In sample 1, the atomic ratio of In to Ni [In] / [Ni] = 3.30, which is larger than the atomic ratio of 2.33 corresponding to the composition of Ni3In7 (In is more than Ni). Therefore, it can be interpreted that even after alloying between In and Ni, the remaining In that was not consumed during alloying remained on the sample surface as elemental In. No diffraction peaks corresponding to intermetallic compounds of Ni and In with compositions other than Ni3In7 were observed in the entire 2θ region measured for samples 1 and 2, suggesting that the In-Ni alloy is predominantly formed in the form of Ni3In7. It should be noted that the peak intensity of Ni3In7 in sample 1 is lower than that in sample 2. This is attributed to the presence of an In layer on the surface of Ni3In7 in sample 1, which attenuates the X-ray transmission intensity. The absence of Cu peaks in the substrate in sample 1 is also attributed to the attenuation of X-ray transmission intensity caused by the In and Ni3In7 layers.

[0109] Summarizing the XRD results of heated samples 1 and 2, it can be seen that in sample 2, where the In layer is thinner than the Ni layer and the atomic ratio [In] / [Ni] is less than 7 / 3 (=2.33) corresponding to the Ni3In7 composition ratio, no elemental In layer remains due to alloying between In and Ni. Conversely, in sample 1, where the In layer is thicker than the Ni layer and the atomic ratio [In] / [Ni] is greater than 7 / 3, even after alloying between In and Ni, an unalloyed elemental In layer remains on the sample surface. Therefore, it can be concluded that in a laminated structure containing Ni and In layers, by making the atomic ratio [In] / [Ni] greater than 7 / 3, even after alloying of Ni and In under high-temperature conditions, an unalloyed In layer can remain.

[0110] Furthermore, for sample 1, the surface contact resistance was measured before and after heating. The results showed that the contact resistance under a 3N contact load was approximately 0.8 mΩ before heating and approximately 1 mΩ after heating. That is, even after heating, the contact resistance increased only slightly, and the absolute value was suppressed to a small extent. This corresponds to the formation of an unalloyed In layer on the surface of sample 1 after heating. It is believed that due to the residual unalloyed In layer, the contact resistance-reducing effect of In is maintained even after heating.

[0111] The embodiments of the present disclosure have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention.

[0112] Symbol Explanation

[0113] 1. Metallic materials

[0114] Metallic materials involved in Method 1A

[0115] 1B Metallic materials involved in the second method

[0116] 1C Metallic materials involved in the third method

[0117] 2. Substrate

[0118] 3. Intermediate layer

[0119] 3a Ni capping layer

[0120] 3b alloy layer

[0121] 4 In overlay

[0122] 20 Female connector terminals

[0123] 21 Flexible contact sheet

[0124] 21a protrusion

[0125] 22 Internal opposing contact surfaces

[0126] 23 Clamping section

[0127] 30 male connector terminals

Claims

1. A connecting terminal, said connecting terminal being configured to include a metallic material, The metallic material has the following characteristics: Substrate; An intermediate layer comprising at least Ni and covering the surface of the substrate; and An In overlay layer, the In overlay layer being composed of In, covers the surface of the intermediate layer and is exposed on the outermost surface. In the combined total of the intermediate layer and the In capping layer, the In content, in terms of atomic ratio, is greater than 7 / 3 times that of Ni, and At least at the contact portion that is in electrical contact with the mating conductive member, the intermediate layer and the In cover layer are formed on the surface of the substrate.

2. The connection terminal as claimed in claim 1, wherein, The layer composed of Ni is defined as the Ni capping layer, and If we define the layer as an alloy layer composed of an alloy containing Ni and In, then... The intermediate layer has any one of the following first, second, and third structures. In the first structure, the intermediate layer is composed of the Ni capping layer. In the second structure, the intermediate layer consists of the Ni capping layer and the alloy layer covering the surface of the Ni capping layer. In the third structure, the intermediate layer is composed of the alloy layer.

3. The connection terminal as described in claim 2, wherein, The intermediate layer has either the first structure or the second structure. The thickness of the In capping layer is more than 5.6 times the thickness of the Ni capping layer.

4. The connection terminal as claimed in claim 2 or claim 3, wherein, The intermediate layer has either the first structure or the second structure. The thickness of the Ni capping layer is less than 1 μm.

5. The connection terminal as claimed in claim 3, wherein, The intermediate layer has the first structure.

6. The connection terminal as claimed in claim 2 or claim 3, wherein, The intermediate layer has either the second structure or the third structure. The alloy layer contains an intermetallic compound with the composition Ni3In7.

7. The connection terminal as claimed in claim 1 or claim 3, wherein, Based on the total content per unit area of ​​the intermediate layer and the In capping layer, The Ni content is 0.89 mg / cm³. 2 the following, The In content was 4.3 mg / cm³. 2 above.

8. The connection terminal as claimed in claim 1 or claim 3, wherein, The substrate is made of Cu or a Cu alloy.

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