Conductive terminal and electric connector

Abstract

The invention provides a conductive terminal and an electric connector, the conductive terminal comprises a conductive substrate and an electroplated layer structure plated on the conductive substrate, the electroplated layer structure comprises a nickel plating layer located at the outer side of the conductive substrate; the silver plating layer is positioned on the outer side of the nickel plating layer; and the noble metal plating layer is positioned on the outer side of the silver plating layer.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electroplating, and in particular to an electrically conductive terminal and an electrical connector. BACKGROUND

[0002] Electrical connectors can be used to transmit data signals and / or electrical power. Electrical connectors include electrically conductive terminals that mate with each other and apply a positive pressure to each other to maintain good contact. During use, the electrically conductive terminals can have relative micro-movements at their contact points due to thermal expansion and vibration, which can cause localized wear. In addition, when electrical connectors are subjected to a large number of repeated plugging and unplugging, wear can occur at the electrical contact points of the electrically conductive terminals due to friction.

[0003] Due to market demand for large current and multiple plugging applications, gold and silver are increasingly used in the electrical contact points of electrically conductive terminals. Gold is resistant to high temperature and humidity and is not corroded by any acid or base except aqua regia. Silver is less expensive than gold, and the thermal and electrical conductivity of silver is more suitable for coating or pure chemical or electrochemical deposition on the electrical contact points. However, the hardness of silver is 100 Hv, which is significantly lower than the hardness of gold, which is 180 Hv, so the wear resistance of silver-plated electrically conductive terminals is lower. Moreover, since silver is not resistant to any acid or base, it is easily oxidized and sulfided in environments such as warm and humid, coastal, and industrial waste gas, which can degrade or even fail the electrical performance of the electrically conductive terminals. SUMMARY

[0004] One object of the present application is to solve at least one of the above problems and defects in the prior art.

[0005] To solve the above problems, a first aspect of the present application discloses an electrically conductive terminal, comprising: an electrically conductive base and an electroplated layer structure plated on the electrically conductive base, the electroplated layer structure comprising: a nickel plating layer located on the outer side of the electrically conductive base; a silver plating layer located on the outer side of the nickel plating layer; and a noble metal plating layer located on the outer side of the silver plating layer.

[0006] According to an exemplary embodiment of the present application, the silver plating layer has a friction coefficient less than 1.

[0007] According to an exemplary embodiment of the present application, further comprising a nanocrystalline nickel plating layer located between the nickel plating layer and the silver plating layer.

[0008] According to an exemplary embodiment of the present application, further comprising a lubricating layer covering the outermost side of the electroplated layer structure.

[0009] According to an exemplary embodiment of the present application, the silver plating layer is a first silver plating layer, and the electroplated layer structure further comprises a second silver plating layer, wherein the second silver plating layer is located between the nickel plating layer and the first silver plating layer.

[0010] According to an exemplary embodiment of the present application, the silver plating layer has a coefficient of friction of 0.25-0.5.

[0011] According to an exemplary embodiment of the present application, the silver plating layer has a thickness of 2.5-5 μm.

[0012] According to an exemplary embodiment of the present application, the silver plating layer is electroplated from a silver electroplating bath having a pH of less than 7.

[0013] According to an exemplary embodiment of the present application, the silver electroplating bath does not include cyanide.

[0014] According to an exemplary embodiment of the present application, the silver plating layer does not include carbon particles having a grain size of greater than 100 nm in diameter, and the silver plating layer has a carbon content of 1-3% by mass.

[0015] According to an exemplary embodiment of the present application, the noble metal plating layer includes metal gold, platinum, ruthenium, or a combination thereof.

[0016] According to an exemplary embodiment of the present application, the noble metal plating layer has a thickness of 0.1 μm.

[0017] According to an exemplary embodiment of the present application, the nickel plating layer has a thickness of 1.27-3 μm.

[0018] A second aspect of the present application discloses an electrical connector including the conductive terminal of the first aspect of the present application.

[0019] In the foregoing exemplary embodiments of the present application, the silver plating layer structure having a low coefficient of friction can replace the hard silver alloy in the prior art, thereby significantly improving the wear resistance of the conductive terminal. In addition, the silver plating layer structure can replace the expensive gold, thereby reducing the cost. Furthermore, the noble metal plating layer outside the silver plating layer can reduce the corrosion and discoloration of the silver plating layer, thereby improving the stability of the conductive terminal. BRIEF DESCRIPTION OF DRAWINGS

[0020] The features, advantages, and other aspects of the embodiments of the present application will become more apparent from the following detailed description in conjunction with the accompanying drawings, in which a number of embodiments of the present application are illustrated, by way of example, not limitation, as follows:

[0021] Figure 1 A schematic view of a structure of a conductive terminal of an embodiment of the present application;

[0022] Figure 2 A schematic view of a structure of a conductive terminal of an embodiment of the present application;

[0023] Figure 3A schematic view of a structure of a conductive terminal according to an embodiment of the present application;

[0024] Figure 4 A schematic view of a structure of a conductive terminal according to an embodiment of the present application;

[0025] Figure 5 A schematic view of a structure of a conductive terminal according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be further described below in conjunction with the accompanying drawings. In the description, identical or similar reference signs indicate identical or similar components. The following description of the embodiments of the present application with reference to the accompanying drawings is intended to explain the general inventive concept of the present application, and should not be construed as a limitation of the present application.

[0027] The terms "comprise", "contain", and similar terms used herein should be understood as open terms, i.e. "comprising / containing but not limited to", meaning that other content can also be included. The term "based on" is "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment", and so on.

[0028] The present application mainly focuses on the following technical problem: how to provide a conductive terminal with high wear resistance and high stability.

[0029] In order to solve the above problems, according to one general concept of the present application, a conductive terminal is provided, comprising: a conductive base and a plating layer structure plated on the conductive base, the plating layer structure comprising: a nickel plating layer located on the outside of the conductive base; a silver plating layer located on the outside of the nickel plating layer; and a noble metal plating layer located on the outside of the silver plating layer.

[0030] Figure 1 A schematic view of a structure of a conductive terminal according to an embodiment of the present application is shown. The conductive terminal 100 comprises a conductive base 101 and a plating layer structure plated on the conductive base, the plating layer structure comprising: a nickel plating layer 102 located on the outside of the conductive base 101; a silver plating layer 103 located on the outside of the nickel plating layer 102, in some examples, the friction coefficient of the silver plating layer 103 is less than 1; and a noble metal plating layer 104 located on the outside of the silver plating layer 103.

[0031] In some examples, the conductive substrate 101 is copper or a copper alloy, including but not limited to brass and bronze. A nickel plating 102 is located between the conductive substrate 101 and the silver plating 103. The nickel plating 102 acts as a barrier layer to prevent copper from diffusing into the silver plating at high temperatures. Additionally, the nickel plating 102 retains the electrical properties of silver. The thickness of the nickel plating 102 is at least 0.5 μm, or, for example, from 1 μm to 10 μm, or, for example, from 1.27 μm to 3 μm. The nickel plating 102 can be prepared by various methods, including but not limited to PVD, CVD, and electrolysis.

[0032] The coefficient of friction is calculated by dividing the frictional force by the perpendicular or normal force. During the friction coefficient test, a force perpendicular to the direction of relative motion between two samples is applied, and the coefficient of friction is obtained by measuring the frictional force between the two samples. The coefficient of friction for silver plating 103 can be less than 1.

[0033] In some implementations, to improve the hardness of silver, a "hard silver alloy," such as a silver-antimony alloy, a silver-tin alloy, or a silver-palladium alloy, can be used. Hard silver alloys can achieve a hardness of up to 150 Hv. Under test conditions of 100 linear cycles under a 1 N load, the coefficient of friction of hard silver alloys is approximately 1.2-1.6. Furthermore, wear marks are observed on the surface of hard silver alloys, with a wear depth of approximately 2-4 μm.

[0034] The silver plating 103 in this application exhibits a coefficient of friction less than 1, more preferably between 0.25 and 0.5, under test conditions of 1-5 N load and 500-10000 linear cycles. For example, under test conditions of 1000 linear cycles under a 2 N load, the coefficient of friction of the silver plating 103 can be 0.4. Furthermore, the surface of the silver plating 103 is substantially flat, i.e., almost free of wear marks. The performance of a silver plating with a coefficient of friction less than 1 is far superior to that of a hard silver alloy.

[0035] In comparison, the coefficient of friction of hard gold under test conditions of 500-10000 linear cycles under a 1N load is approximately 0.5-1.

[0036] It is worth noting that the above-mentioned friction coefficient measurements were all conducted without lubricant on the metal layer surface. Since the silver plating layer of this application is self-lubricating, it is not necessary to add a surface organic transparent film or lubricant after electroplating. Therefore, the production process is simple and controllable, the performance is stable, and the relative cost is lower.

[0037] The silver plating layer 103 is formed by electroplating a substrate in a silver plating bath. In some examples, the silver plating bath includes a silver ion source, thiodiethanol, and a sulfonated anionic polymer. In some examples, the pH of the silver plating bath is less than 7. Preferably, the pH is 0–3.

[0038] In some examples, the silver plating bath does not include cyanide. Silver ions can be provided by silver salts composed of one or more of silver halides, silver gluconate, silver citrate, silver lactate, silver nitrate, silver sulfate, silver alkylsulfonate, and silver alkylolsulfonate. The preparation of the silver plating layer does not require cyanide solvents, thus eliminating the need for specific controls on highly toxic materials and reducing environmental harm. The silver plating bath can be from DuPont's Silveron... TM GT-101, Silveron TM GT-210, Silveron TM GT-820.

[0039] In some examples, the thickness of the silver plating 103 is at least 2 μm, or, for example, from 2 μm to 10 μm, or, for example, from 2.5 μm to 5 μm.

[0040] A noble metal plating 104 covering the silver plating can improve the corrosion resistance of the conductive terminals. In some examples, the noble metal plating may include gold, platinum, ruthenium, or combinations thereof. For example, the noble metal layer 104 may be hard gold, platinum, or a platinum-ruthenium alloy. In some examples, the thickness of the noble metal plating is in the nanometer range, preferably 0.1 μm.

[0041] When the precious metal plating 104 includes platinum, it is beneficial to improve the wear resistance and stability of the terminals. First, platinum (min 450 Hv) has a higher hardness than gold (180 Hv), which is beneficial to improving the wear resistance of the terminals. Furthermore, platinum costs approximately 50% of gold, significantly reducing the production cost of electrical connectors. Second, platinum's color and luster are similar to silver, which helps to improve the surface gloss of the terminals and reduce discoloration. In addition, platinum's density (21.45) is higher than gold's (19.3), making it easier to obtain a dense nanocrystalline structure through electroplating. Even with the same nanometer-thickness plating, platinum's density and coverage are superior to gold, improving the corrosion resistance of the silver plating.

[0042] Figure 1 The conductive terminal 100 utilizes a silver plating structure with a low coefficient of friction, which can replace the hard silver alloy used in existing technologies, significantly improving the wear resistance of the conductive terminal. Furthermore, the silver plating structure can replace expensive gold, thereby reducing costs. Additionally, the precious metal plating layer outside the silver plating can reduce corrosion and discoloration of the silver plating, thus improving the stability of the conductive terminal.

[0043] Typically, to improve the wear resistance of silver plating, carbon particles, such as graphite or other carbon allotropes or mixtures thereof, are uniformly incorporated into the silver. In some examples, the silver plating layer 103 of this application does not include carbon particles with a grain size larger than 100 nm, and the mass percentage of carbon in the silver plating layer is 1-3%. This avoids problems such as poor contact stability between silver and carbon particles and uneven silver plating thickness.

[0044] Figure 2 A schematic diagram of the structure of a conductive terminal according to an embodiment of this application is shown. The conductive terminal 100 includes: a conductive substrate 101 and an electroplated layer structure plated on the conductive substrate. The electroplated layer structure includes: a nickel plating layer 102 located outside the conductive substrate 101; a silver plating layer 103 located outside the nickel plating layer 102, and the coefficient of friction of the silver plating layer 103 is less than 1; a nanocrystalline nickel plating layer 112 located between the nickel plating layer 102 and the silver plating layer 103; and a noble metal plating layer 104 located outside the silver plating layer 103.

[0045] The addition of a nanocrystalline nickel plating layer 112 between the nickel plating layer 102 and the silver plating layer 103 can increase the density and adhesion between the plating layers.

[0046] Figure 3 A schematic diagram of the structure of a conductive terminal according to an embodiment of this application is shown. The conductive terminal 100 includes: a conductive substrate 101 and an electroplated layer structure plated on the conductive substrate. The electroplated layer structure includes: a nickel plating layer 102 located outside the conductive substrate 101; a silver plating layer 103 located outside the nickel plating layer 102, and the coefficient of friction of the silver plating layer 103 is less than 1; a noble metal plating layer 104 located outside the silver plating layer 103; and an organic layer 105 located outside the noble metal plating layer 104.

[0047] The organic layer 105 is applied to the outermost side of the electroplated layer structure, serving as a lubricant and sealing agent to reduce the chances of corrosion, wear, and discoloration of the silver plating layer. The organic layer 105 can be a lubricant containing organic materials such as thiols, perfluorinated compounds, olefins, or polyethers.

[0048] Figure 4 A schematic diagram of the structure of a conductive terminal according to an embodiment of this application is shown. Figure 4 The examples in the text combine Figure 2 and Figure 3The structure of the conductive terminal is described. Specifically, the conductive terminal 100 includes: a conductive substrate 101 and an electroplated layer structure plated on the conductive substrate. The electroplated layer structure includes: a nickel plating layer 102 located outside the conductive substrate 101; a silver plating layer 103 located outside the nickel plating layer 102, and the coefficient of friction of the silver plating layer 103 is less than 1; a nanocrystalline nickel plating layer 112 located between the nickel plating layer 102 and the silver plating layer 103; a noble metal plating layer 104 located outside the silver plating layer 103; and an organic layer 105 located outside the electroplated layer structure.

[0049] Figure 5 A schematic diagram of the structure of a conductive terminal according to an embodiment of this application is shown. Figure 1 Compared to the structure, Figure 5 A second silver plating layer 123 is provided between the nickel plating layer 102 and the silver plating layer 103. Specifically, the conductive terminal 100 includes a conductive substrate 101 and an electroplated layer structure plated on the conductive substrate. The electroplated layer structure includes: a nickel plating layer 102 located outside the conductive substrate 101; a second silver plating layer 123 located outside the nickel plating layer 102; a first silver plating layer 103 located outside the second silver plating layer and having a coefficient of friction of less than 1; and a noble metal plating layer 104 located outside the first silver plating layer 103.

[0050] In some examples, the second silver plating 123 can be a nanocrystalline structure. The second silver plating located between the nickel plating 102 and the first silver plating 103 can increase the density and adhesion between the plating layers, and reduce the effects of metal thermal diffusion and thermal expansion due to temperature rise when the connector is powered on for a long time.

[0051] Another embodiment of this application provides an electrical connector that uses the conductive terminals described above. The electrical connector of this embodiment has the same or similar structure as the aforementioned embodiments, and therefore will not be described again.

[0052] The above descriptions are merely optional embodiments of this application and are not intended to limit the embodiments of this application. For those skilled in the art, the embodiments of this application can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included in the protection of the embodiments of this application.

[0053] While embodiments of this application have been described with reference to several specific examples, it should be understood that the embodiments of this application are not limited to the specific embodiments disclosed. The embodiments of this application are intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. The scope of the appended claims is to be interpreted in the broadest possible sense, thereby encompassing all such modifications and equivalent structures and functions.

Claims

1. A conductive terminal, characterized in that, include: A conductive substrate and an electroplated layer structure deposited on the conductive substrate, the electroplated layer structure comprising: A nickel plating layer is located on the outside of the conductive substrate; A silver plating layer is located outside the nickel plating layer; and A precious metal plating layer is located on the outside of the silver plating layer.

2. The conductive terminal according to claim 1, characterized in that, The coefficient of friction of the silver plating is less than 1.

3. The conductive terminal according to claim 1, characterized in that, It also includes a nanocrystalline nickel plating layer, which is located between the nickel plating layer and the silver plating layer.

4. The conductive terminal according to any one of claims 1 to 3, characterized in that, Also includes: A lubricating layer is applied to the outermost side of the electroplated layer structure.

5. The conductive terminal according to claim 1, characterized in that, The silver plating layer is a first silver plating layer, and the electroplating layer structure further includes a second silver plating layer, wherein the second silver plating layer is located between the nickel plating layer and the first silver plating layer.

6. The conductive terminal according to claim 2, characterized in that, The coefficient of friction of the silver plating is 0.25-0.

5.

7. The conductive terminal according to claim 1, characterized in that, The thickness of the silver plating layer is 2.5 μm to 5 μm.

8. The conductive terminal according to claim 1, characterized in that, The silver plating layer is formed by electroplating in a silver plating bath with a pH value less than 7.

9. The conductive terminal according to claim 8, characterized in that, The silver plating bath does not contain cyanide.

10. The conductive terminal according to claim 8, characterized in that, The silver coating does not include carbon particles with a diameter greater than 100 nm, and the mass percentage of carbon in the silver coating is 1-3%.

11. The conductive terminal according to claim 1, characterized in that, The precious metal coating includes gold, platinum, ruthenium, or a combination thereof.

12. The conductive terminal according to claim 1, characterized in that, The thickness of the noble metal coating is 0.1 μm.

13. The conductive terminal according to claim 1, characterized in that, The thickness of the nickel plating is from 1.27 μm to 3 μm.

14. An electrical connector, characterized in that, Includes the conductive terminal as described in any one of claims 1 to 13.

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