JPH0249319A - Electric contact and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the contact adhering tendency and enhance the reliability by forming an electric contact consisting of Pd-Ni-Fe alloy with Pa as main component on a base consisting of a magnetic metal material. CONSTITUTION:A reed (base) 11 of a reed switch consists of a magnetic metal material (Fe-Ni alloy), and an electric contact 12 formed at the tip of the reed switch 11 is constructed by heat diffusion of Fe of the reed on Pd-Ni alloy, and Fe of the reed 11 is formed on an Ni layer 13 heat diffused. Oxidated iron 14 dispersed on the surface course of the contact 12 is obtained by oxidating Fe dispersed on the surface course of the contact 12.

Description

[Detailed Description of the Invention] [Summary] Regarding electrical contacts used in reed switches and the like and their manufacturing method, the electrical contacts formed on a base made of a magnetic metal material contain palladium as a main component for the purpose of improving the tendency to stick. A nickel layer is formed on a substrate made of a magnetic metal material, and then a palladium-nickel layer is formed on the nickel layer, and then a palladium-nickel layer is formed on the nickel layer. The structure is characterized by thermally diffusing the iron of the base into the palladium-nickel layer.

[Industrial application field]

The present invention relates to electrical contacts used in reed switches and the like, and particularly to electrical contacts that suppress the tendency to stick, and a method for manufacturing the same.

[Conventional technology]

Generally, noble metals such as rhodium, ruthenium, and gold are widely used for electrical contacts that open and close electric circuits.

Although these noble metals have excellent electrical properties as contact materials, they are expensive, so recently, electrical contacts using relatively inexpensive palladium have appeared.

Fig. 5 is a schematic cross-sectional view of a conventional palladium-nickel contact, and the electrical contact 2 formed on the lead piece (substrate) made of magnetic metal material (iron-nickel alloy) is plated with palladium-nickel alloy. , lead piece 1 and electrical contact 2
Nickel plating layer on the nickel layer formed during 3)
This is to improve the adhesion of the electrical contacts 2.

When such an electrical contact 2 is used in a reed switch or the like, it can be used as a substitute for a previous mating contact or the like in terms of contact resistance and corrosion resistance.

improvement of lubricity), etc.

Therefore, when contacts formed on a pair of lead pieces made of magnetic material face each other in an insulating tube, the surface hardening method applies a high-voltage alternating current to the lead pieces to cause a discharge between the contacts. , it is possible to utilize the discharge energy, and the oxide formation method described above is possible by carrying out the process in an atmosphere containing oxygen when sealing the lead piece in an insulating tube, and forming an oxide film on the surface of the contact. However, such surface treatment is insufficient in suppressing the tendency to stick as an electrical contact.

[Problem to be solved by the invention]

However, compared to reed switches and the like that have a small opening force, electrical contacts using palladium-nickel alloys have a problem in that they have a relatively large tendency to stick due to the characteristics of the material.

In addition, methods for suppressing the adhesive tendency include hardening the surface of the electrical contact (suppression of adhesive wear) and forming oxides on the surface of the electrical contact (surface moisture [Means for solving the problem]). According to the electrical contact according to the invention, as shown in FIG. 1, an electrical contact 12 formed on a base 11 made of a magnetic metal material is made of palladium and nickel whose main components are palladium.

According to FIG. 2, the method for producing an electrical contact according to the present invention, characterized by being made of an alloy of iron, includes forming a nickel layer 15 on a base 11 made of a magnetic metal material, and then depositing palladium on the nickel layer 15. - After forming the nickel layer 16, the iron of the base 11 is thermally diffused into the palladium-nickel [16].

[Effect]

According to the electrical contact and its manufacturing method of the above means, iron is thermally diffused into the palladium-nickel layer, and as a result, when applied to the contact of a reed switch, it is possible to reduce the tendency of contact adhesion to 175 or less compared to the conventional one. This greatly contributes to improving the reliability of electrical contacts such as reed switches.

〔Example〕

Below, the electrical contact according to the present invention will be explained using the drawings.

FIG. 1 is a schematic sectional view of an electrical contact according to an embodiment of the present invention, FIG. 2 is a schematic sectional view of the electrical contact before thermal diffusion treatment,
FIG. 3 is an explanatory diagram of the main manufacturing process of the reed switch equipped with the electrical contacts shown in FIG. 1, and FIG. 4 is an explanatory diagram of the magnetic adhesion tendency test method.

In Figure 1, reed switch reed piece (base) 1
1 is made of a magnetic metal material (iron-nickel alloy), and the electrical contact 12 formed at the tip of the lead piece 11 is made by thermally diffusing the iron of the lead piece 11 into the palladium-nickel alloy. It is formed on a nickel layer 13 in which iron is thermally diffused. The iron oxide 14 dispersed in the surface layer of the electrical contact 12 is obtained by oxidizing the iron diffused in the surface layer of the electrical contact 12.

In FIG. 2, the contact forming portion of the lead piece 11 is coated (plated) with nickel [15], and palladium-plated on top of it.
Nickel alloy (e.g. 80% palladium).

20% nickel alloy) layer 16 is deposited. This also improves the adhesion of the palladium-nickel alloy layer 16.

The nickel layer 15, which has the function of facilitating thermal diffusion of the iron of the lead piece 11, has a thickness of, for example, about 0.2 μm, and the thickness of the palladium-nickel alloy layer 16 has a thickness of about 2 μm.

Such nickel layer 15 and palladium-nickel alloy layer 1
6, when the lead piece 11 is heated to 600° C. to 800″C for about 15 minutes in a hydrogen atmosphere, the iron of the lead piece 11 diffuses into the nickel layer 15 and further into the palladium-nickel alloy layer 16 .

In FIG. 3(A), the pair of lead pieces 11 with iron diffused into the palladium-nickel alloy layer (16) after the thermal diffusion treatment of the contact portions 17 is completed are arranged so that the contact portions 17 are overlapped with an appropriate gap. so that they face each other at the center of the glass tube 18.

Next, as shown in FIG. 3(b), the ends of the glass tubes 18 are heated in an atmosphere 19 of nitrogen gas containing an appropriate amount of oxygen and fused to the middle part of each lead piece 11. ]
The contact portion 17 heated close to the glass melting temperature in
Iron diffused into the surface layer is oxidized and iron oxide (14) is formed.
The reed switch 20 is completed.

As described above, the adhesive tendency of the contact portion 17 of the Dosuisochi 20 was determined by the magnetic adhesive tendency test method shown in FIG.
This is less than 0%, which is significantly lower than the stickiness tendency (approximately -70%) measured using the same method for a conventional reed switch having palladium-nickel alloy contacts.

In Figure 4, which is used to explain the magnetic adhesion tendency test method for reed switches, the vertical axis represents the current (ampere-turn; AT) flowing through the drive coil, and the horizontal axis represents time (seconds), and the time in the figure. 1 is the initial contact open current value, D02
is the contact opening current value after magnetostrictive sliding.

The test procedure for adhesion tendency, which is completed in 60 seconds, is to apply a current of 75 AT to the drive coil to close the contacts, then lower the drive current to open the contacts, and calculate the open current value D1.
Measure 11. Next, set the drive current to the initial open value. , a sufficiently higher value (150AT) and the initial open value. 82 between a value slightly higher than I (Do++2AT)
After shaking the reed switch 00 times, the drive current was lowered and the open current [)oz of the reed switch was measured, and the adhesion tendency Δ was calculated by the following formula.

Δ(χ) = ((Do2-DOI) /Doi X1
00 indicates that there is a tendency to stick when it is negative, and the larger the absolute value, the stronger the tendency to stick <, -
At 100%, the contacts will not open.

The currently used reed switches with low opening force must have a tendency to stick at a practical level of 140% or less, but the one according to the present invention has a sticking tendency of 110% or less.

In the embodiment shown in FIG. 1, iron oxide 14 is formed on the surface of the electrical contact 12, and this iron oxide I4 acts as a lubricant for the contact between the mating contacts and further reduces the tendency to stick. Contributes to the reduction of

〔Effect of the invention〕

As explained above, according to the present invention, iron is thermally diffused into the palladium-nickel layer, and the adhesive tendency of the electrical contact is reduced to 175 or less compared to the conventional one, which greatly contributes to improving the reliability of electrical contacts such as reed switch and nochi. have an effect.

An explanatory diagram of the main manufacturing process of the switch. Figure 4 is an explanatory diagram of the magnetic adhesion tendency test method. Figure 5 is a schematic cross-sectional view of a conventional palladium-nickel contact. In the figure, 11 is a lead piece (substrate), 12 15 represents an electrical contact, 15 represents a nickel layer, and 16 represents a palladium-nickel layer.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of an electrical contact according to an embodiment of the present invention, FIG. 2 is a schematic sectional view of the electrical contact shown in FIG. 1 before thermal diffusion treatment, and FIG. 3 is a schematic sectional view of the electrical contact shown in FIG. 1. I prepared a leadon for the month of August. Samurai Seven,
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Claims (2)

[Claims] (1) An electrical contact characterized in that the electrical contact (12) formed on the base (11) made of a magnetic metal material is made of an alloy of palladium, nickel, and iron, the main component of which is palladium. (2) Forming a nickel layer (15) on the base (11) made of a magnetic metal material, then forming a palladium-nickel layer (16) on the nickel layer (15), and then forming the palladium-nickel layer (16) on the nickel layer (15). (16) A method for manufacturing an electrical contact, which comprises thermally diffusing the iron of the base.