JPS5848969B2 - electrical contacts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to contacts of electrically opening/closing switches, and is particularly suitable for normal load conditions where arc discharge may occur between opposing contacts, and The present invention relates to electrical contacts for a wide range of applications that are suitable for low level load conditions where arcing does not occur.

Materials for electrical contacts are desired to be materials that are less susceptible to wear and transfer due to switch opening/closing operations, less susceptible to inability to open due to adhesion, and suitable for normal load conditions that can cause arc discharge between contacts. .

Conventionally, platinum group metals have been frequently used as materials for electrical contacts that can satisfy the above-mentioned requirements because of their high melting points and high hardness.

However, platinum group metals tend to adsorb organic substances that come into contact with them during the manufacturing process or in the enclosed atmosphere due to their catalytic effects, and when the contacts are opened and closed under low-level load conditions, platinum group metals Electrical contacts have a drawback in that organic substances with high specific resistance are deposited on the contact portions due to polymerization of the organic substances, resulting in an increase in contact resistance.

In addition, ruthenium contacts made by electrodeposition in platinum group metals can reduce the above-mentioned drawbacks under the limited properties of the pampering liquid and various processing conditions in the manufacturing process; There were drawbacks such as the stability of the material was inhibited by factors such as

The object of the present invention is to provide an electrical contact using ruthenium with a ruthenium oxide layer having a thickness of 5 to 25 thick on the surface of the ruthenium, thereby enhancing the catalytic action without impairing the performance of the electrical contact. The object of the present invention is to provide a high-performance contact by eliminating the contact resistance and further reducing the change in contact resistance due to the opening/closing operation of the contact.

In the present invention, in a contact using ruthenium, by forming a ruthenium oxide layer with a thickness of 5 to 25 mm on the contact surface, it can be applied to a practical switch and arc discharge can be prevented between opposing contacts. It is suitable for both load conditions that can cause arc discharge and low-level load conditions that do not cause arc discharge, and has achieved low contact resistance and stable contact resistance due to opening and closing operations.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing the layer structure of a contact portion of a reed when a contact according to the present invention is applied to a reed switch, for example.

In FIG. 1, l is a lead piece made of a magnetic metal such as Fe or Ni alloy.

Reference numeral 2 denotes a lower layer film, such as gold, that serves to prevent the lead piece material from diffusing onto the contact surface and to strengthen the adhesion between the contact metal and the lead piece material, and is provided as necessary. .

3 is a ruthenium layer, and 4 is a ruthenium oxide layer provided on the ruthenium layer 3 with a thickness of 5 to 25 layers.

Figure 2 shows data regarding an example for realizing a contact according to the present invention, and shows the relationship between the thickness of the ruthenium oxide layer and the treatment temperature obtained when heat treatment is performed for 10 minutes in an oxygen-containing atmosphere. It shows.

The thickness of the ruthenium oxide layer in FIG. 2 was obtained by Auger analysis.

According to FIG. 2, it is clear that the thickness of the ruthenium oxide layer has a relatively simple relationship with the processing temperature, making it easy to control the thickness in practical use.

After depositing the ruthenium layer by electroplating using a reed switch that is in practical use as an embodiment of the present invention, it is heat-treated at 390°C for 10 minutes in nitrogen containing oxygen occupying 20% of the volume. An electrical contact coated with a ruthenium oxide layer obtained by performing the above steps was prepared.

FIG. 3 shows data showing the relationship between contact resistance and the number of opening/closing operations when the switch is opened/closed; curve A is for the switch having the contacts according to the present invention, and curve B is for the switch according to the present invention. The case of a switch with contacts that are pure ruthenium surfaces is shown.

According to FIG. 3, it is clear that the switch having contacts based on the present invention has a more stable contact resistance and less variation between switches.

Next, FIG. 4 shows the relationship between the pressing force (contact force) between the contact points facing each other and the contact resistance.

In FIG. 4, curve A shows the case in which contacts coated with a ruthenium oxide layer with a thickness of 25λ are brought into contact with each other in accordance with the present invention, and curve B shows a case in which contacts coated with a ruthenium oxide layer with a thickness of 25λ are brought into contact with each other. The case of a contact covered with a layer is shown.

In FIG. 4, the contact resistance shown by curve A when a contact force of 3 grams or more is applied is sufficiently low, and the change in contact resistance that occurs when the contact force is changed is also small.

For example, in a normal reed switch, the contact force is 5 to 1
It is clear from FIG. 4 that contacts having a ruthenium oxide layer of thickness from 5 to 25 Å in accordance with the present invention are fully usable.

As explained above, the present invention uses ruthenium for the electrical contact and further forms a ruthenium oxide layer with a thickness of 5 to 25 people on the surface of the contact, resulting in low contact resistance and resistance to the opening/closing operation of the contact. This has the effect of providing a highly reliable electrical contact that is also stable.

[Brief explanation of the drawing]

Fig. 1 is a structural sectional view showing an embodiment of the present invention, and Fig. 2 is an embodiment of a concrete implementation method according to the present invention.
A graph showing the relationship between the temperature and the thickness of the generated oxide layer when heat-treated for JO in nitrogen containing oxygen, Fig. 3 is a graph showing the number of opening/closing operations of the switch and change in contact resistance, Fig. 4 is a graph showing the relationship between contact force and contact resistance between contact points facing each other. 1... Switch materials such as lead pieces, 2...
... Lower layer film, 3 ... Rudenium layer, 4 ...
...Ruthenium oxide layer.

Claims (1)

[Claims] 1. An electrical contact having a ruthenium oxide layer between 5 and 25 thick on the contact surface and a ruthenium layer below the ruthenium oxide layer.