JPS5937534B2 - electric sliding contact - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric sliding contact used for mechanical parts such as connectors and switches that involve sliding contact.

Generally, electrical sliding contacts such as connectors and switches are required to have low contact resistance, low coefficient of friction, and high corrosion resistance.

Conventionally, materials using Au have been mainstream as materials satisfying these performances.

However, these electrical sliding contacts using Au have become extremely expensive due to the rising price of Au.

Therefore, there is currently a need for an electric sliding contact that can limit the amount of Au used or replace it with a low-cost material while also satisfying the above-mentioned performance. Conventionally, the following electric sliding contacts that do not use Au are known, but none of them can be said to have high performance as electric sliding contacts.

In other words, as an electric sliding contact that does not use Au,
(1) Ni is sequentially added to the base metal (for example, Cu alloy spring material).
It has undergone plating and Ag plating.

(2) Sn plating is applied to the base metal (for example, Cu alloy spring material).

(3) Sn-based metal (for example, Cu alloy spring material)
Pb alloy plated.

However, (1) has the disadvantage of poor sulfidation resistance and increases contact resistance after long-term use, causing poor contact, while (2) and (3) have poor contact resistance. It had the drawbacks of being expensive and having a high coefficient of friction.

Therefore, these electric sliding contacts have never been used where high reliability is required. In addition, electrical sliding contacts using Au that are sequentially plated with Ni and Au on the base metal are used, but as mentioned above, these electrical sliding contacts have no performance characteristics. Although high reliability can be obtained without any problems, it has the drawback of being extremely expensive.

In addition, recently, electric sliding contacts plated with Pd have been proposed, and are expected to replace Au.
Although the sulfidation resistance and contact resistance were good, the coefficient of friction was about twice as high as that of conventional connectors using Au, making it difficult to insert and remove the connector.

Furthermore, the Au of the electric sliding contact using conventional Au
In order to reduce the amount of Au plating layer used, the thickness of the Au plating layer was set to 0.
It is possible to reduce the thickness to 5 μm or less, but since the plating itself is porous, many pinholes will occur in the Au plating layer, and the metal under the Au plating layer will corrode through the pinholes. However, the corrosion film becomes Au due to creep.
Since the entire surface of the Au plating layer is covered, it is virtually impossible to reduce the thickness of the Au plating layer.

As described above, conventional electric sliding contacts have the disadvantage that high reliability cannot be obtained unless a large amount of Au is used. An object of the present invention is to provide a novel electric sliding contact that eliminates the drawbacks mentioned in the previous section. This can be achieved by providing a second layer made of In on the first layer, and furthermore, it can be achieved by providing a layer made of Ni between the first layer and the base metal. .

In other words, the present invention solves the drawback of the Pd-plated layer having a large friction coefficient by providing an In-plated layer on the Pd-plated layer, thereby reducing the friction coefficient, thereby reducing the friction coefficient of the Pd-plated layer. It is designed to achieve almost the same performance as a sliding contact.

The reason for providing an In plating layer is that In has a low melting point and is soft, so if a thin layer is provided between the contacts,
This is due to accelerated alloying with Pd due to diffusion of Pd into the plated layer due to frictional heat, or because the alloying is different between both contacts, resulting in a contact phenomenon of dissimilar materials occurring on the outermost surface. I'll vine it up. In order to put the contactor of the present invention into practical use, for example, taking the plug and jack of a connector as an example, the characteristics of the present invention will not be exhibited even if the plug and jack are made of the same type of materials and brought into contact with each other.

That is, in a plug and jack combination, the plug has a substantially larger sliding track than the jack, and the jack has a smaller sliding track.

Considering the temperature rise on the surface due to sliding contact, the temperature rise is larger for the contact Y with a small sliding track, and the temperature rise is smaller for the contact x with a large sliding track.

When the contact of the present invention is used for this X contact with a small temperature rise, the In plating layer on the surface is slightly oxidized, and this In
Since oxide is harder than metal 1n, it acts like an abrasive during sliding contact, increasing the coefficient of friction and therefore increasing wear.

On the other hand, when the contact of the present invention is used for a Y contact with a small sliding track, interdiffusion with Pd in the underlying layer occurs relatively quickly after the start of sliding due to the large temperature rise.
The surface is InPd alloyed. Therefore, this alloy layer essentially comes into contact with other materials of the X contact, such as the Au plating layer or the Pd plating layer, and exhibits an excellent contact phenomenon.

Next, the present invention will be explained with reference to examples.

(1) Phosphor bronze as the base metal (PBW3-H1 diameter 0
．． 9mm), this PBW wire was plated with Ni to a thickness of 1.5μm, and then plated with Pd to a thickness of 0.5μm.
An electric sliding contact was fabricated.

→Au on the contact made in the same way as sample a(2)(1)
Plating was performed to a thickness of 0.1 μm to produce an electric sliding contact.

→Sample b (3) PBW is used as the base metal, and this P
Ni plating with a thickness of 1.5 μm was sequentially provided on the BW line, and Au plating was further provided with a thickness of 0.75 μm on this Ni plating.
An electric sliding contact was fabricated.

→In on the contact made in the same way as sample C(4)(1)
Plating was performed to a thickness of 0.5 μm to produce an electric sliding contact.

This configuration is the configuration according to the present invention. → Figure 1 shows the cross-sectional structure of the samples obtained from sample d and above.

The friction coefficient of the thus obtained contactor was measured using a friction coefficient measuring device as shown in FIG.

This measuring device is designed so that the contacts 11 and 12 to be measured are each attached to an acrylic holder so that they are in perpendicular cross contact, and a predetermined load 13 can be applied to the contact points. The measurement is performed by moving the contactor 11 and detecting the force with which the contactor 12 tries to move using the strain gauge 15 attached to the fixed holder 14.

The friction coefficient is calculated from the applied load Wl3 and the force F detected by the strain gauge 15 using the formula F/W. In this measurement, the load was 300V, and the sliding distance was 6m77! /times, and the number of sliding movements on the horizontal axis in FIG. 3 is shown assuming that one reciprocating sliding movement is two times. The sliding speed of the movable contact after 200 sliding operations according to the example was 12 mm/Mm, and the sliding operation was performed up to 100 times.

Sliding contact was performed using the combinations of contacts shown in Table 1, and the results shown in FIG. 3 were obtained. In FIG. 3, the coefficient of friction (F/W) is plotted on the vertical axis and the number of sliding movements is plotted on the horizontal axis.

From the results shown in Figure 3, it can be roughly divided into three groups.

Namely, Test 7I6.1; Tests A6.3, 6, 7; and Test S). There are three groups: 2, 4, 5, and 8. Table 2 shows that the larger the diameter of the wear scar (C), the greater the wear.

As is clear from the above examples, the contactor of the present invention is
Contact with the same kind of material in d does not show very good properties, but depending on how the contacts are combined (always shows excellent properties, contact with the same kind of material in the contactor d, or contact with the same kind of material in the contactor a) It is clear that Kei has similar characteristics.

Also, in any of the combinations in Table 2, the saliva contact resistance is 25
It was less than mΩ, indicating stable contact.

According to the present invention, it is possible to use relatively inexpensive P instead of using expensive Au.
d. Since In provides superior properties, material costs can be significantly reduced.

[Brief explanation of the drawing]

Figure 1 shows the cross-section of the contactor used in the example (d is the contactor of the present invention), Figure 2 shows an example showing the principle of the arithmetical measuring device, and Figure 3 shows the number of times and the coefficient of friction. FIG.

Claims (1)

[Claims] 1. An electric sliding contact characterized by providing a first layer mainly composed of Pd on a base metal, and providing a second layer made of In on this first layer. Child. 2. The electric sliding contact according to claim 1, further comprising a layer containing Ni as a main component between the base metal and the first layer.