JPH0480486B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] This is an electrical contact formed on the lead piece of a reed switch, etc. After depositing a nickel layer with a copper base layer,
The contact resistance is reduced and stabilized by applying a diffusion treatment in which the base layer diffuses into the nickel layer.

[Industrial application field]

The present invention relates to improvements in electrical contacts used in reed switches and the like, particularly in relation to contact resistance.

The reed switch has contact parts formed on each of at least a pair of reed pieces sealed in a glass tube together with an inert gas, and the contact parts facing each other so as to overlap at an appropriate interval.
Reed relays are highly reliable because they are not affected by humidity, etc. Reed relays, which combine a reed switch with a driving means such as a permanent magnet, have the advantage of being smaller, lighter, and faster operating than electromagnetic relays.

Generally, the contacts used in such reed switches and the like are mainly made of rhodium-gold, and although such electrical contacts have excellent electrical properties, they are expensive. Therefore,
Copper-nickel contacts, although having inferior electrical properties to rhodium-gold contacts, are used for applications requiring low cost contacts.

[Conventional technology]

FIG. 3 is a schematic cross-sectional view showing a conventional copper-nickel contact.

In FIG. 3A, an electrical contact (copper-nickel contact) 2 formed on a metal substrate 1 containing an iron component, such as permalloy, is made of nickel as a base layer 3, as shown in FIG. After depositing the copper layer 4 on the substrate, a diffusion treatment is performed by heating it at, for example, 900° C. for about 15 minutes, so that the nickel base layer 3 and the copper layer 4 become a solid solution.

[Problem that the invention seeks to solve]

However, the conventional electrical contact 2 has a metal base 1
When the material contains an iron component that is easily thermally diffused with nickel, the iron component that diffuses into the electrical contact 2 and appears on the surface of the electrical contact 2 will be oxidized by oxygen in the atmosphere.

In particular, when the metal base 1 is a reed piece of a reed switch, residual oxygen in the inert gas sealed in the glass tube of the reed switch oxidizes the iron component appearing on the surface of the contact, increasing the contact resistance. In addition, since the driving force of the reed switch operated by an external magnetic field is relatively weak, there is a problem in that the contact resistance value of the contact point becomes unstable and has large "variations".

[Means for solving problems]

The present invention aims to eliminate the above problems.
According to the figure, contacts 12 formed on a metal base 11
This is an electrical contact characterized in that a nickel layer 14 is deposited on a copper base layer 13, and then a diffusion process is performed to diffuse the base layer 13 and the nickel layer 14.

[Effect]

In the electrical contact of the above means, a base layer is made of copper, which contains an iron component but is difficult to thermally diffuse with the iron component, and a nickel layer is deposited on the base layer, and then the base layer and the nickel layer are bonded together. Since the metal substrate is subjected to a diffusion treatment, even though the metal substrate contains iron components, the iron components are hardly diffused into the contacts. Therefore, the iron component does not appear on the surface of the contact, and even when used in an oxygen-containing atmosphere, the contact resistance value of the contact is lower than that of conventional copper.
It is smaller and more stable than a nickel contact.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Electrical contacts according to embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an electrical contact according to an embodiment of the present invention.

In FIG. 1A, a metal base 11, which is a lead piece of a reed switch, is made of permalloy, and an electrical contact 12 is formed at the contact portion of the metal base 11.

As shown in FIG. 1B, the electrical contact 12 is made by forming a copper-plated base layer 13 in which iron is difficult to thermally diffuse, and then laminating a nickel plating layer 14 thereon. and the nickel layer 14 are diffused, for example, by heating at 900° C. for about 15 minutes to obtain a complete solid solution of copper and nickel.

Therefore, almost no iron component contained in the metal base 11 is thermally diffused to the electrical contact 12, and the thermally diffused iron component is not exposed on the surface of the electrical contact 12.
The contact resistance of the electrical contact 12 is smaller than that of the conventional electrical contact 2, and is stable over the number of operations.

Figure 2 shows a copper plating base layer 13 with a thickness of 1.8 μm.
The contact resistance characteristics of the electrical contact 12 in which a nickel plating layer 14 with a thickness of approximately 0.5 μm is laminated and then subjected to a diffusion treatment of heating at 900° C. for approximately 15 minutes, and the contact resistance characteristics of the conventional electrical contact 2. It is a diagram comparing actual measured values.

In FIG. 2, the vertical axis is the contact resistance value R (mΩ) between the electrical contacts, the horizontal axis is the number of times N (times) of opening and closing between the contacts, and the ○ mark in the figure is the electrical contact according to the present invention. 12, the solid line arrow extending vertically above the ○ mark indicates its variation width, the ● mark in the figure indicates the average measured value of electrical contact 2, which is the conventional technology, and the solid line arrow extending vertically with the ● mark indicates its variation. It is the width.

As is clear from FIG. 2, the electrical contact 12 according to the present invention has a lower contact resistance than the conventional electrical contact 2, and even though the number of operations increases,
It is almost constant at 0.05mΩ or less.

On the other hand, the contact resistance of the electrical contact 2 according to the prior art is
It is 0.06 mΩ to 0.12 mΩ, and as the number of operations increases, iron oxide is formed on the surface, and after the iron oxide is peeled off, iron oxide is thought to be formed again. The variation becomes extremely larger than that of the electrical contact 12 when the number of operations N is ²⁰⁶ times or more.

〔Effect of the invention〕

As explained above, an electrical contact in which a nickel layer is formed on a copper base layer according to the present invention and the base layer and nickel layer are diffused through a diffusion process has a higher contact resistance than a conventional copper-nickel contact. Furthermore, since the "variation" in contact resistance is small and it is stable over the number of operations, it has the effect of improving the performance of electrical components such as reed switches.

[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 comparison diagram of contact resistance characteristics between an electrical contact according to the present invention and an electrical contact according to the prior art, and FIG. 3 is a diagram of a conventional copper-nickel electrical contact. FIG. 3 is a schematic cross-sectional view showing a contact point. In the figure, 1 and 11 are metal bases, 2 and 12
is an electrical contact, 3 is a nickel base layer, 4 is a copper layer,
13 indicates a copper underlayer, and 14 indicates a nickel layer.

Claims (1)

[Claims] 1 A copper base layer 13 is formed on a metal substrate 11 containing iron, a nickel layer 14 is deposited on the base layer 13, and then a diffusion treatment is performed to diffuse the base layer 13 and the nickel layer 14. An electrical contact characterized by: