JPS5937533B2 - electric sliding contact - Google Patents

Description

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

Electric sliding contacts such as conventional connectors generally use a Cu alloy spring material as the base metal, and contacts plated with NLAu (or Ni
, Ag, etc.) are used.

As a method for electrically coupling these contacts, for example, a contact pair consisting of a plug and a jack has the same plating surface. Recently, Pd, which is cheaper than Au, has been used for such contact pairs, and N is deposited on the base metal.
A contact plated with i, Pd, and Au in this order is used.

However, since it uses Au, it has the disadvantage of being expensive. To eliminate this drawback, N
There is an i-Pd-In multilayer plated contact, but when this contact is used in combination as a sliding contact in a connector or the like, it has a drawback that the coefficient of friction is high and therefore the wear is large. The present invention aims to solve the drawbacks of the Ni-Pd-Au or Ni-Pd-In plated electrical contacts described in the previous section, and when combining the contact pairs, one of the surfaces of the contacts is made of Au. The object of the present invention is to provide a new electric sliding contact which has excellent contact performance (friction coefficient, wear) due to a combination in which the other is made of In. The present invention aims to improve wear resistance by bringing different materials into sliding contact.

In general, contact between different materials often causes less wear than contact between similar materials.

It is influenced by whether the materials on the surface of the contact point are likely to be alloyed with each other or the state of formation of the surface film. The structure of the present invention is such that contact performance equivalent to the same type of Au-to-Au contact is obtained by a combination of a contact A whose outermost surface is plated with Au and a contact I whose outermost surface is plated with In. It is. That is, to explain the plug and jack of the connector as an example, the present invention is a combination in which A is used as the plug and I is used as the jack. In other words, the surface of the contact X whose sliding track is substantially larger than that of a jack, such as a plug, is plated with Au, while the surface of the contact Y, whose sliding track is relatively small, is plated with Au. The present invention is a dissimilar contact method consisting of n plating. The reason why the combined contact of the present invention is superior to other combinations, such as the reverse combined contact of the present invention, can be explained as follows. Since contact Y has a smaller sliding track than contact X, Y has a larger temperature rise than X.

For this reason, In, which has a low melting point, interdiffuses with the underlying Pd at a relatively early stage after the start of sliding, and the surface becomes In-
Alloyed with Pd. Therefore, substantial contact is a contact phenomenon between the Au of the X contact and the In--Pd alloy of the Y contact, resulting in excellent contact performance. On the other hand, the combination of the present invention is reversed, that is, the surface of the contact X with the larger sliding track is plated with In, and the surface of the contact Y with the smaller sliding track is plated with In.
When the surface is plated with Au, the temperature rise of the X contact is relatively small, so the In on the outermost surface is slightly oxidized before diffusion with the lower layer occurs.

Since this In oxide is harder than metal 1n, it acts like an abrasive during sliding contact, increasing the coefficient of friction and therefore increasing wear. This combination has poor contact performance. In other words, in sliding contact made of different materials, the new electric sliding contact according to the present invention is a combination in which the surface of the contact with a larger sliding contact area is made of Au and the surface of the contact with a smaller sliding contact area is made of In.

Next, the present invention will be explained by examples.

FIG. 1 is a diagram showing an example of a cross-sectional configuration of a contactor used in an embodiment of the present invention.

In FIG. 1, a is given as the contact X of the present invention, and b is given as the contact Y.

In FIG. 1, reference numeral 1 denotes a base metal, and in all the examples, phosphor bronze wire PBW3-H is used.

2 is Ni plated and has a thickness of 1.5 μm.

3 is plated with Pd and has a thickness of 0.5 um.

4 is Au plated and has a thickness of 0.1 μm.

Further, 5 is indium plated and has a thickness of 0.5 μm. Figure 2 shows the number of times of sliding contact and the friction at that time for a total of four sliding contacts in which the contacts FIG. 3 is a diagram showing changes in coefficients.

In addition, in this sliding contact, the contact load is 300y1 and the sliding length is 3W! m is reciprocated, and one reciprocating slide is defined as two times. The curve numbers in the figure are based on the combinations in Table 1. A in Table 1. b correspond to the configuration shown in FIG. 1, respectively. From FIG. 2, it can be seen that, compared to combinations 3 and 4, friction coefficients 1 and 2 are much smaller and more stable, and combination 2, that is, the combination of the present invention, is the most excellent. Table 2 shows the results obtained by microscopic observation of the size of the wear marks on the contact part of the jack side contactor after 200 sliding operations according to the example shown in Fig. 2. The smaller the number, the greater the wear.

As is clear from the above examples, the second embodiment of the present invention exhibits the same contact performance as the conventional Pd-based Au-plated contact 1, and the superiority of the combined contact of the present invention can be understood.

Note that the contact resistance was 25 mΩ or less in any of the combinations 1, 2, 3, and 4 in Table 1, indicating stable contact resistance.

According to the present invention, since Au on the outermost surface can be replaced with In, which is cheaper than Au, material costs can be reduced. The contact X as a plug is a conventional Au socket 6.
- A contactor may be used.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the sample used in the example, and FIG. 2 is a diagram showing the relationship between the number of sliding movements and the coefficient of friction.

Claims (1)

[Claims] 1. In a pair of electrical sliding contacts that are combined so that the sliding distances are different from each other, the surface of the contact that has a large sliding distance during sliding contact is essentially made of Au, and on the other hand,
The surface of the contact with a relatively small sliding distance is essentially In
An electric sliding contact characterized by: