JP2017166038A - Energizing contact member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energizing contact member having relatively low price and excellent in fretting resistance and withdrawal properties.SOLUTION: There are provided an energizing contact member by laminating a CuSn alloy plating layer 2 with a thickness of 3 to 10 μm and a Sn plating layer 1 with a thickness of 0.1 o 0.5 μm on a substrate 3 in this order, and a manufacturing method of the energizing contact member including a process for forming and the CuSn alloy plating layer 2 with thickness of 3 to 10 μ on the substrate 3 and a process for forming the Sn plating layer 1 with thickness of 0.1 to 0.5 μm on the CuSn alloy plating layer.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an energizing contact member and a manufacturing method thereof. The present invention particularly relates to a current-carrying contact member that is relatively inexpensive and excellent in fretting resistance.

  In the connection between the energizing members, the energizing contact member is not fastened with bolts or the like, but is sandwiched by a clip structure using the spring property of the member itself or the energizing contact partner material, and energization is ensured by contact between metals. . Since this structure can be removed more easily than bolt fastening at the time of assembly, maintenance, and parts replacement, it is often used for a current-carrying part.

  However, in this structure, fretting wear, in which the current-carrying contact portion wears, is likely to occur when a slight sliding occurs due to a fine vibration of the entire product or a temperature cycle accompanying ON / OFF of current supply. In particular, since Sn plating is soft, it is easily worn. The wear powder of Sn generated by this fretting wear is exposed to the atmosphere for sliding, and is easily oxidized in a high temperature environment due to energization. In addition, the wear powder, which is an oxide of Sn, is deposited on the energized contact surface, so that the contact resistance increases, which may cause problems such as excessive heat generation and ignition.

  Therefore, normally, a material that is not easily oxidized, such as Ag plating, is used for the current-carrying contact portion. However, since Ag is expensive, a cheaper material has been demanded. As a candidate for this, a CuSn alloy is expected as a hard material that is inexpensive, has low resistance, and does not easily cause fretting wear. The CuSn alloy layer is excellent in fretting wear resistance due to its high hardness, but there are cases where the frictional force is large and there is a problem in workability in insertion / extraction with the clip.

  For this reason, a technique has been developed that improves slidability and improves insertion / extraction by forming an oxide film on the outermost surface layer of CuSn (see Patent Documents 1, 2, and 3). In addition, Sn plating is formed on the surface of the copper base material, and this is subjected to heat treatment under a temperature condition of 150 ° C. or more and 170 ° C. or less, thereby forming a CuSn alloy on the copper base material and thinning the Sn plating layer on the surface. A manufacturing method of a fitting type connection terminal which is left is known (Patent Document 4).

JP 2000-212720 A JP 2000-226645 A Japanese Unexamined Patent Publication No. 2007-247060 Japanese Patent Laid-Open No. 10-302867

  In the methods disclosed in Patent Documents 1 to 3, control of the thickness of the oxide film is required. When the oxide film becomes thick, there is a concern about the problem of heat generation accompanying an increase in contact resistance. In particular, when an oxide film having a thickness of more than 500 nm is formed on the surface of the member, the oxide film grows excessively due to the heat generated by energization, causing problems of heat generation and ignition. Furthermore, this oxide film thickness is difficult to measure and is not suitable for mass production. On the other hand, in the method disclosed in Patent Document 4, the alloy layer is grown by heat treatment, and the Sn layer remains. However, at present, it has been shown that it is impossible to produce a uniform layer structure as shown in the representative diagram by heating control.

  As a result of intensive studies, the inventor considered that the outermost layer is made of Sn capable of ensuring insertion / extraction, and that this layer is formed to a thickness that does not cause a problem even when oxidation occurs. I came up with the invention. That is, the present invention, according to one embodiment, is an energizing contact member, on a substrate, a CuSn alloy plating layer having a thickness of 3 to 10 μm and an Sn plating layer having a thickness of 0.1 to 0.5 μm. Are laminated in order.

In the current-carrying contact member, the composition of the CuSn alloy plating layer is preferably Cu ₆ Sn ₅ .

  In the energization contact member, the base material is preferably Cu, Al, or an alloy or composite material containing these.

  According to another embodiment of the present invention, there is a current-carrying contact structure, which is a combination of the current-carrying contact member described above and a current-carrying contact material, and the outermost surface layer of the current-carrying contact material is In the case of an oxide layer or an oxide generation layer, the total thickness of the Sn plating layer of the current-carrying contact member and the outermost surface layer of the current-carrying contact material is 0.5 μm or less, When the outermost surface layer of the energization contact partner material is a non-oxide generation layer, the thickness of the Sn plating layer of the energization contact member is 0.5 μm or less.

  According to another aspect of the present invention, there is provided a method for producing a current-carrying contact member, the step of forming a CuSn alloy plating layer having a thickness of 3 to 10 μm on a substrate, and 0 on the CuSn alloy plating layer. Forming a Sn plating layer having a thickness of 1 to 0.5 μm.

In the method for manufacturing the energizing contact member, it is preferable that the step of forming the CuSn alloy plating layer is a step of forming a Cu ₆ Sn ₅ alloy plating layer by electrolytic plating.

  According to the energizing contact member and the manufacturing method thereof according to the present invention, it is possible to provide an energizing contact member that is relatively inexpensive and excellent in fretting resistance and insertion / extraction. According to the present invention, in particular, a substantially uniform and smooth CuSn alloy plating layer and Sn layer can be laminated on a substrate, and the film thickness can also be accurately controlled at the manufacturing stage. Therefore, it is possible to provide an energizing contact member and an energizing contact structure that do not cause an electrical failure even if the state of the metal surface changes with time after manufacturing.

FIG. 1 is a schematic cross-sectional view of an energizing contact member according to an embodiment of the present invention. FIG. 2 is a graph showing the relationship between the oxide film thickness and the contact resistance in the energized contact member according to the present invention.

  Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiments described below.

[First Embodiment: Energizing Contact Member and Manufacturing Method Thereof]
The present invention relates to an energizing contact member according to an embodiment. FIG. 1 is a conceptual cross-sectional view showing an example of an energizing contact member according to the present embodiment. The current-carrying contact member shown in FIG. 1 includes a base material 3, a CuSn alloy plating layer 2, and a Sn plating layer 1.

  The base material 3 may be a general conductive material, and may be, for example, Cu, Al, an alloy including at least one of these, and a composite material including at least one of these. For example, an alloy of Cu or Al and Cr, Mg, Fe, P, Ni, Zn, Ti, Si, Mn, or the like can be given, but is not limited thereto. The base material 3 may be in any shape suitable for the purpose and application of the energizing contact member, and the thickness and dimensions thereof are not limited.

The CuSn alloy plating layer 2 is formed on the base material 3 in contact with the base material 3. Although not shown, another layer may be interposed between the base material 3 and the CuSn alloy plating layer 2. Examples of the composition of other layers that can intervene include Cu, Ni, Sn, Ag, Zn, Co, and alloys and composite layers containing these, and the thickness of the layer is not particularly limited, and its function For example, the thickness may be 1 to 15 μm. In this specification, the CuSn alloy is a generic term for an alloy having an arbitrary composition ratio of Cu and Sn. Since the CuSn alloy plating layer 2 is excellent in corrosion resistance and hardly fretting wear, it is possible to impart a flooding resistance to the energizing contact member. Examples of the CuSn alloy include, but are not limited to, Cu ₆ Sn ₅ , Cu ₃ Sn, Cu ₆ Sn, and the like. Among them, a preferable CuSn alloy is Cu ₆ Sn ₅ . This is because plating can be stably deposited in an intermetallic compound of CuSn and productivity is high.

The CuSn alloy plating layer 2 is provided on the substrate 3 with a thickness of 3 to 10 μm. If the thickness is less than 3 μm, especially when the substrate is Cu, diffusion proceeds between Cu and Cu ₆ Sn ₅ with energization, and a brittle Cu ₃ Sn composition becomes dominant in the CuSn alloy plating layer. As a result, there is a concern that mechanical troubles such as cracks may occur, so a thickness of at least about 3 μm is required. On the other hand, if it is thicker than 10 μm, the residual stress of the CuSn alloy plating film becomes large and there is a concern about peeling.

  The CuSn alloy plating layer 2 is preferably formed on the substrate 3 as a smooth plating film having a substantially uniform thickness. Such a CuSn alloy plating layer 2 can be manufactured by an electrolytic plating method to be described later.

  The Sn plating layer 1 is in contact with the CuSn alloy plating layer 2 and is formed on the CuSn alloy plating layer 2 to constitute the outermost surface of the energizing contact member. The Sn plating layer 1 is preferably composed only of Sn and inevitable impurities.

  The thickness of the Sn plating layer 1 is 0.1 to 0.5 μm. If the film thickness is less than 0.1 μm, the slidability at the time of insertion / extraction cannot be ensured, and there is a concern about corrosion of the base material in the unplated portion. On the other hand, if the thickness is too thick, a Sn single layer remains on the current-carrying contact surface even if diffusion between Sn and the CuSn alloy occurs. For this reason, there is a concern about the problem of heat generation due to increased contact resistance due to the thick accumulation of oxidized wear powder due to fretting wear. Even if fretting wear has progressed prior to the formation of CuSn intermetallic compound by diffusion, if the Sn layer has a thickness of about 0.5 μm, the effect on the increase in contact resistance is negligible. preferable. In addition, the thickness of Sn plating layer 1 can be determined in the range of 0.1-0.5 micrometer, and also by the relationship with the energization contact partner material used as the partner material of an energization contact member. This will be described later.

  Since the outermost layer Sn plating is soft and has high slidability, it is excellent in insertability during assembly. In addition, this outermost layer Sn plating causes mutual diffusion with the underlying Cu—Sn layer during actual use, whereby a CuSn intermetallic compound layer is formed on the outermost surface. Thereby, a high-strength energizing contact surface is formed, and the fretting resistance is improved. In addition, Sn remains in part of the outermost layer, but since the film thickness is thin, an oxide layer that affects the contact resistance is not formed even if fretting wear progresses. Further, the remaining Sn can secure the insertion / removability again at the time of parts replacement such as maintenance of the energizing contact member.

  Next, the energizing contact member according to the present invention will be described from the viewpoint of the manufacturing method. The method for manufacturing the current-carrying contact member includes a step of forming a CuSn alloy plating layer 2 having a thickness of 3 to 10 μm on the substrate 3, and a Sn plating having a thickness of 0.1 to 0.5 μm on the CuSn alloy plating layer 3. Forming the layer 1.

  As described above, the base material 3 may be Cu or Al, an alloy thereof, or a composite material. Before the step of forming the CuSn alloy plating layer 2 is performed, the surface of the base material 3 may be Alternatively, the CuSn alloy plating layer 2 may be formed on another plating layer. The other plating layers in this case are as described above as the composition of other layers that can be interposed, and the production method is a method suitable for forming a plating layer of each composition, such as an electrolytic plating method or an electroless plating method. It can be.

In the step of forming the CuSn alloy plating layer 2, the CuSn alloy plating layer 2 having a thickness of 3 to 10 μm is preferably formed on the base material 3 by an electrolytic plating method. The composition of the plating bath used at this time can be determined by the composition of the target CuSn alloy. In a preferred embodiment, when a Cu ₆ Sn ₅ alloy plating layer is deposited, a known or commercially available plating bath can be used. Moreover, the thickness of the CuSn alloy plating layer 2 can also be controlled by a normal method, and the CuSn alloy plating layer 2 having a substantially uniform and smooth thickness can be obtained.

  Next, a step of forming the Sn plating layer 1 having a thickness of 0.1 to 0.5 μm on the CuSn alloy plating layer 3 is performed. The Sn plating layer 1 can be formed by using either an electroplating method or an electroless plating method, and a known or commercially available plating bath can be used. Moreover, the thickness of the Sn plating layer 1 can also be controlled by a normal method. And the electricity supply contact member which has a substantially uniform and smooth outermost surface layer can be obtained.

  In the manufacturing method according to the present embodiment, it is preferable not to include a heat treatment step at a high temperature such as 150 ° C. or higher. This is because when the heat treatment step at a high temperature is performed, the thickness and composition of the CuSn alloy plating layer are substantially impossible to control, and there is a high possibility that a non-uniform and extremely low corrosion resistance layer is generated.

  According to the current-carrying contact member and the manufacturing method thereof according to the present embodiment, a current-carrying contact member formed by laminating a substantially uniform and smooth CuSn alloy plating layer and Sn layer on a base material can be obtained. As a result, no problems occur over time. It is possible to obtain a current-carrying contact member that is relatively inexpensive and excellent in insertion / extraction properties and anti-fredding properties.

[Second Embodiment: Energizing Contact Structure]
The present invention, according to yet another embodiment, is an energizing contact structure. The energization contact structure includes an energization contact member and an energization contact partner material. The energizing contact structure is a clip structure using the energizing contact member itself or the spring property of the energizing contact partner material, one of which sandwiches the other, and ensures energization by contact between the energizing contact member and the energized contact partner material. The clip structure may be any known structure, such as the structure disclosed in Patent Document 4, but is not limited thereto.

  In the present embodiment, the energizing contact member is configured according to the first embodiment. The energizing contact partner material may be made of any material that can be normally used as an energizing member. However, at least at the contact point between the energizing contact member and the energizing contact partner material, the thickness of the Sn plating layer 1 of the outermost surface layer of the energizing contact member is determined in relation to the material of the outermost layer of the energizing contact partner material. The

  Specifically, when the outermost surface layer of the energization contact partner material is an oxide layer or an oxide generation layer, the Sn plating layer 1 of the energization contact member, and the outermost surface layer of the energization contact partner material The total thickness is 0.5 μm or less. This is because the occurrence of the trouble due to the oxide wear powder is caused by the total amount of oxide that can be generated by both the energizing contact member and the energizing contact partner material. The oxide generation layer referred to here is a layer of a conductive member capable of generating an oxide under normal use conditions of the energizing contact member, and mainly includes Sn, but is not limited thereto. . Therefore, for example, when the current-carrying contact member and the current-carrying contact partner material have the same configuration, the thickness of the Sn plating layer 1 of the current-carrying contact member is 0.1 μm or more and 0.25 μm or less. It may be. The reason why the lower limit is 0.1 μm or more is that, as with the Sn layer in the first embodiment, there is a possibility that the characteristics of the Sn layer may not be exhibited even if it is too thin.

On the other hand, when the outermost surface layer of the current-carrying contact partner is a non-oxide generation layer, the thickness of the Sn plating layer 1 of the current-carrying contact member is 0.1 μm or more and 0.5 μm or less. It's okay. Here, the non-oxide generation layer is a metal or alloy layer that generates little oxidized wear powder and does not substantially affect the contact resistance due to the use over time or insertion / extraction of the current contact member and the current contact material. However, Cu ₆ Sn ₅ layer, Cu ₃ Sn layer, Cu ₆ Sn layer, Ag, Ni and the like can be mentioned, but not limited thereto. The reason why the thickness of the Sn plating layer 1 is in the above range is that there is no need to consider oxide wear powder derived from the energized contact partner material.

  According to the current-carrying contact structure according to this embodiment, even if oxide wear powder is generated at the contact point between the current-carrying contact member and the current-carrying contact partner material, the contact resistance is not excessively increased, and stable current conduction is performed. Can be possible.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

[1. Production of energized contact member]
By the method described in the embodiment of the present invention, an energizing contact member formed by laminating a plating layer on a base material was produced. A 5 μm-thick Cu ₆ Sn ₅ layer was formed on a base material made of Cu having a thickness of 3 mm by electrolytic plating. A commercially available plating bath was used, and the electrolysis conditions were 1 A / dm ² . Next, a 0.5 μm Sn layer was formed on the Cu ₆ Sn ₅ layer by electrolytic plating. It can be visually recognized that the obtained laminate is a uniform and smooth layer in both the Cu ₆ Sn ₅ layer and the Sn layer.

[2. Relationship between oxide film thickness and contact resistance]
In the same manner as described above, a Cu base material and a Cu ₆ Sn ₅ layer were formed. The thickness was also the same. On the other hand, the Sn layer was formed by electrolytic plating while changing the film thickness from 0.15 μm, 0.3 μm, 0.4 μm, 0.55 μm, 0.8 μm, and 1.3 μm. This Sn layer was oxidized by atmospheric heating to prepare a sample for contact resistance measurement. Next, the contact resistance of the sample was measured. FIG. 2 is a graph showing the relationship between the oxide film thickness and the contact resistance. As can be seen from FIG. 2, when the oxide film thickness is 0.5 μm or less, an excessive increase in contact resistance is not observed, and a contact resistance equivalent to the natural oxide film thickness on Sn can be secured when used in general. It was.

1 Sn plating layer 2 CnSn alloy plating layer 3 Base material

Claims (6)

  An energizing contact member formed by sequentially laminating a CuSn alloy plating layer having a thickness of 3 to 10 μm and an Sn plating layer having a thickness of 0.1 to 0.5 μm on a base material. The composition of the CuSn alloy plating layer is a _Cu 6 Sn _5, energization contact member according to claim 1.   The energizing contact member according to claim 1, wherein the base material is Cu, Al, or an alloy or composite material containing these. An energization contact structure comprising a combination of the energization contact member according to any one of claims 1 to 3 and an energization contact partner material,
When the outermost surface layer of the energization contact partner material is an oxide layer or an oxide generation layer, the total thickness of the Sn plating layer of the energization contact member and the outermost surface layer of the energization contact partner material Is 0.5 μm or less,
When the outermost surface layer of the current-carrying contact material is a non-oxide generation layer, the current-carrying contact structure is such that the thickness of the Sn plating layer of the current-carrying contact member is 0.5 μm or less. Forming a CuSn alloy plating layer having a thickness of 3 to 10 μm on the substrate;
Forming a Sn plating layer having a thickness of 0.1 to 0.5 μm on the CuSn alloy plating layer. The method according to claim 5, wherein the step of forming the CuSn alloy plating layer is a step of forming a Cu ₆ Sn ₅ alloy plating layer by electrolytic plating.

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