JPH01301828A - Alloy for electrical contact - Google Patents

Abstract

PURPOSE:To prevent the decomposition and generation of carbon from an organic gas accumulated in a sealed container and to improve the contacting reliability of a relay by using an Au-Sb alloy having specific compsn. as an alloy for an electrical contact used in a sealed electro-magnetic relay, etc. CONSTITUTION:An Au alloy contg. 55.26wt.% Sb is used for an electrical contact in a sealed electro-magnetic relay sealed by incorporating inner constitutional parts into a housing. In the housing, a hydrocarbon-organic gas of low boiling point such as ethane, methane, benzene and xylene generated from parts made of resin is accumulated and is oxidized and decomposed by an arc, etc., at the time of opening and closing the contact to generate carbon, which adheres onto the surface of the electrical contact to cause the inferiority of contacting. At this time, Sb in the Au-Sb alloy as the electrical contact prevents the generation of carbon caused by the decomposition of the organic gas, prolongs the service life of the electrical contact without the generation of the contacting inferiority in the electrical contact caused by the adhesion of carbon and improves its reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an alloy for electrical contacts used in sealed electromagnetic relays and the like.

(Prior Art and Problems to be Solved by the Invention) In general, in sealed electromagnetic relays etc. in which internal components are assembled and sealed in a housing, low boiling point hydrocarbons generated from resin parts are stored in the sealed housing. Organic gases such as ethane, methane, benzene, xylene, etc. tend to accumulate, and these organic gases are oxidized and decomposed by arc energy and switching energy when opening and closing contacts, and adhere to the surface of electrical contacts as carbon, resulting in poor contact. There was a problem that caused This phenomenon is particularly significant as the ambient temperature becomes higher. For this reason, conventionally, the resin parts have been degassed before assembly.

However, since it is extremely difficult to remove all the organic gas contained in the resin parts by degassing, there is a problem in that poor contact due to adhesion of carbon to the contact surface cannot be prevented. Moreover, in sealed electromagnetic relays for switching minute signals, noble metals such as Au or Au-based alloys are used as contact materials to improve reliability, but even if a small amount of carphone adheres to the contact surface, Since contact failure occurs, there is a problem in that reliability is low.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an alloy for electrical contacts that can suppress the generation of carbon from organic gas accumulated in a sealed housing and improve contact reliability.

(Another Means to Solve the Problems) The present invention adds a predetermined amount of Sb to Au to prevent the decomposition of organic gases and, by extension, the generation of carbon and its adhesion to contacts.

That is, the gist of the present invention is to set Aui, :Sb at 55°2
An alloy for electrical contacts containing 6% by weight or less.

Sb has a non-catalytic effect that suppresses the generation of carbon from organic gas when opening and closing contacts, but when the amount added is 55
．． If it exceeds 26% by weight, Sb will precipitate and the contact resistance will increase, making it unsuitable as a contact material for minute signals.
It was set to 26ffi amount% or less.

Although Sb exhibits a non-catalytic effect even if the amount added is extremely small, it is usually preferable to add 0.1% by weight or more.

The alloy for electrical contacts can be manufactured by any conventionally known method. For example, there is a method in which Au and Sb are mixed and melted in a furnace according to the component ratio, and then cooled and solidified.

Example 1.2 of the composition shown below by the method of manufacturing
was obtained and used as a sample. For comparison, a comparative example having the composition shown below is used as a sample.

Composition (wt%) Au Sb Example 1 60 40 Example 2 96.3 3.7 Comparative example 100 - Changes in contact resistance with respect to the number of times the contact is opened/closed for the samples of Example 1.2 and Comparative example Measurements were made using the test equipment shown in the figure.

The test device has contacts 3.4 of the same composition arranged in a space 2 that is isolated from the outside air with a transparent glass case 1 so that they can be connected and separated. The contact resistance when energized is measured by the contact resistance measurement circuit and data collection circuit 6.

It is something to collect.

The contact point 3 is attached to the distal end surface of the shaft portion 8 of the Inbakutuff that can be taken in and out in the horizontal direction.
is attached to the distal end surface of a fixture 9 whose horizontal position can be finely adjusted. Further, a displacement sensor IO is disposed near the shaft portion 8, while a pressure sensor I+ is attached inside the fixing jig 9, so that the opening and closing of the contacts can be optimized.

Further, a mixed gas of organic gas and air is blown into the space 2 through a nozzle 12. Furthermore, a heater 13 provided in the space 2, and a vacuum pump 14 connected to the space 2. oil trap 15
This makes it possible to maintain the inside of the space 2 at a predetermined temperature and pressure.

In the experiment, a mixed gas of air and benzene (concentration of benzene of 5% by volume) was injected into the space 2, and the temperature in the space 2 was decreased to 5%.
By maintaining the temperature at 0°C and opening and closing the contact 3.4 at a frequency of 10 Hz, the change in contact resistance of each sample with respect to a load power supply of +3.3 V DC and 25 mA was measured. The measurement results are shown in the graph of FIG.

As is clear from the graph shown in Fig. 2, the comparative example is a practical example even before the contact opens/closes! , exhibiting a higher contact resistance than 2,
As the number of openings and closings increases, the contact resistance gradually increases,
In particular, it can be seen that when the number of openings and closings exceeds 1X103 times, the contact resistance becomes extremely unstable.

On the other hand, in both Examples 1 and 2, the contact resistance was lower than that in the comparative example even before the contact was opened and closed, and in particular, in Example 1 containing 40% by weight of Sb, even after the number of openings and closings exceeded 1 x 106 times. It can be seen that the contact resistance hardly changes, which indicates that the contact has an extremely long life.

Furthermore, even in Example 2, which contains only 3.7% by weight of Sb, the contact resistance increases only after the number of times of contact opening and closing exceeds 4 x 105 times, and even in this case, it is better than the comparative example. It can be seen that the contact resistance is also low.

Furthermore, when the surface of contact 3.4 was observed after the experiment was completed, it was confirmed that carbon was attached to the contact surface in the case of the comparative example, but in the case of example 1. No adhesion was observed.

This is considered to be because the Sb added to Au suppresses the generation of carphone from the gas in the space 2.

(Effect of the invention) As is clear from the above explanation, according to the present invention, Au
Since the Sb added to the housing has a non-catalytic effect of suppressing the generation of carbon from the organic gas accumulated in the housing, even if the alloy for electrical contacts according to the present invention is assembled with resin parts and sealed, Since carbon is not generated from organic gas and contact failure does not occur, the contact life is extended and contact reliability is improved.

4. Brief Description of the Drawings FIGS. 1 and 2 are a schematic sectional view showing a testing device for an alloy for electrical contacts according to the present invention, and a graph showing measurement results.

Patent applicant: Tateishi Electric Co., Ltd. Agent: Patent attorney: 1 person (including the above) Figure 1

Claims (1)

[Claims] (1) An alloy for electrical contacts comprising Au containing 55.26% by weight or less of Sb.