JPH04132122A - Electric contact - Google Patents

Abstract

PURPOSE:To obtain an inexpensive electrical contact durable for a long-term use even in a heavy load region by plating Cu and Ni on a contact base table made of Fe-Ni magnetic material, followed by diffusion treatment, and plating Rh. CONSTITUTION:A Cu-Ni diffusion layer 4, where plated Cu and Ni are diffused, is formed directly on a contact base table 1 made of a Fe-Ni magnetic material. A surface layer 3 made of Rh in thickness of 2mum or so is formed via a conductive contact layer 2 made of plated Au in thickness of 0.5mum or so. The obtained electrical contact is durable for switching up to about 5,000,000 times when a current of DC 10V and 0.5A applied to a load resistor is switched.

Description

[Detailed Description of the Invention] [Summary] The electrical contacts of a reed switch are sealed in a glass tube together with an inert gas, and can withstand long-term use not only in the wheel load area but also in the heavy load area. With the aim of providing an electrical contact that is cheaper than conventional standard electrical contacts, it consists of a contact base made of Fe-Ni magnetic material, a Cu-Ni diffusion layer, and a surface layer.
Diffusion treatment of Cu and Ni plated on the contact base
A u-Ni diffusion layer is formed, and a surface layer is formed by plating Rh on the diffusion layer.

[Industrial application field]

The present invention relates to an electrical contact for a reed switch sealed in a glass tube together with an inert gas.

A reed switch consists of a reed piece made of magnetic material and a glass tube, and is usually made of rhodium (Rh) or ruthenium (Ru).
A noble metal material such as silver or gold (Au) is plated near the tip of the lead piece to form an electrical contact.

However, such precious metal materials are valuable resources and expensive. Therefore, there is a need for the development of an electrical contact that can reduce the amount of precious metal materials used without degrading the operating characteristics of the reed switch.

[Conventional technology]

FIG. 4 is a side cross-sectional view showing the layer structure of a conventional standard electrical contact, and FIG. 5 is a side cross-sectional view showing the layer structure of a conventional low-cost electrical contact.

A conventional standard electrical contact is shown in Fig. 4 (the lead piece, or contact base l, is made of iron (Fe)-nickel (Ni) based magnetic material (permalloy), and a layer of about I μm is placed on the contact base l. The conductive adhesive layer 2 is formed by plating Au, and the surface layer 3 is formed by plating Rh with a thickness of about 3 μm on the conductive adhesive layer 2.

As described above, the electrical contact having the surface layer 3 made of Rh with a thickness of about 3 μm on the contact base 1 can withstand long-term use not only in the ring load area but also in the heavy load area.

On the other hand, in a conventional low-cost electrical contact that avoids the use of expensive Rh, as shown in FIG. 5, a Cu-Ni diffusion layer 4 is formed directly on a contact base l made of Fe-Ni magnetic material. There is. The Cu--Ni diffusion layer 4 is obtained by plating and diffusing Cu and Ni, but the Cu--Ni diffusion layer 4 can be used as it is as a surface layer, making the surface layer 3 made of Rh or the like unnecessary.

Furthermore, when Cu and Ni are directly plated and diffused on the contact base 1, the conductive adhesive layer 2 becomes unnecessary because the Cu and Ni diffuse into the interior of the contact base 1. In this way, surface layer 3
By eliminating the need for the conductive adhesive layer 2, the manufacturing cost of the electrical contact can be reduced to about 60% of that of a conventional standard electrical contact.

[Problem to be solved by the invention]

As mentioned above, conventional low-cost electrical contacts are less expensive than standard electrical contacts and last longer than standard electrical contacts in the mid-wheel load area.

However, Cu and Ni constituting the Cu-Ni diffusion layer are Rh
Since it has a lower melting point than that of , it has a problem that its life is extremely short in heavy load areas that involve electric discharge.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrical contact that can withstand long-term use not only in the wheel load range but also in the heavy load range, and that is less expensive than conventional standard electrical contacts.

[Means to solve the problem]

FIG. 1 is a side sectional view showing the principle of the electrical contact according to the present invention. The same objects are represented by the same symbols throughout the figures.

The above problem is a contact base l made of Fe-Ni magnetic material.
It consists of a Cu-Ni diffusion layer 4 and a surface layer 3, and the contact base l
Cu-Ni is formed by diffusion treatment of Cu and Ni plated on top.
This is achieved by the electrical contact of the present invention in which a diffusion layer 4 is formed and a surface layer 3 is formed by plating Rh on the diffusion layer 4.

[For production]

In FIG. 1, the electrical contact formed by forming a Cu--Ni diffusion layer on a contact base can be used for a long period of time and is inexpensive in the in-wheel load region even without a surface layer. In addition, the surface layer on the diffusion layer is intended to improve the characteristics in heavy load areas.
For example, even a very thin Rh layer of 2 μm or less can achieve the purpose.

In this way, the contact base made of Fe-Ni magnetic material and C
Consisting of a u-Ni diffusion layer and a surface layer, the Cu-Ni diffusion layer is formed by diffusion treatment of Cu and Ni plated on the contact base, and the surface layer is formed by plating Rh on the diffusion layer. The electrical contact of the present invention can reduce manufacturing costs to about 80% of conventional standard electrical contacts.

In other words, it is possible to realize an electrical contact that can withstand long-term use not only in the wheel load range but also in the heavy load range, and that is less expensive than conventional standard electrical contacts.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a side cross-sectional view showing the layer structure in one embodiment of the present invention, and FIG. 3 is a diagram showing the characteristics of a conventional standard electrical contact and one embodiment.

In FIG. 2, one embodiment of the present invention is such that a Cu-Ni diffusion layer 4 obtained by diffusion treatment of plated Cu and Ni is directly formed on a contact base l made of Fe-Ni magnetic material. A surface layer 3 made of Rh and having a thickness of about 2 μm is formed on the Cu--Ni diffusion layer 4 via a conductive adhesion layer 2 made of Au plated to a thickness of about 0.5 μm.

Figure 3 shows the life of an electrical contact when a DC 1OV O, 5A current applied to a load resistor is switched on and off, that is, in a heavy load region with discharge. , the vertical axis is the cumulative failure rate. Conventional standard electrical contacts open and close approximately 700,000 times, as shown by the broken line.
After that, the cumulative failure rate increases rapidly, and most of the contacts fail after about 5 million times of switching, whereas the electrical contacts shown in the above embodiment can withstand about 5 million times of switching, as shown by the solid line.

In this way, the contact base made of Fe-Ni magnetic material and C
Consisting of a u-Ni diffusion layer and a surface layer, the Cu-Ni diffusion layer is formed by diffusion treatment of Cu and Ni plated on the contact base, and the surface layer is formed by plating Rh on the diffusion layer. By means of the electrical contact of the present invention, it is possible to realize an electrical contact that can withstand long-term use not only in the wheel load range but also in the heavy load range, and that is cheaper than conventional standard electrical contacts.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide an electrical contact that can be used for a long period of time not only in a wheel load range but also in a heavy load range, and is moreover inexpensive compared to conventional standard electrical contacts.

[Brief explanation of drawings]

Fig. 1 is a side sectional view showing the principle of the electrical contact according to the present invention, Fig. 2 is a side sectional view showing the layer structure in an embodiment of the invention, and Fig. 3 is a conventional standard electrical contact and one implementation. FIG. 4 is a side sectional view showing the layer structure of a conventional standard electrical contact; FIG. 5 is a side sectional view showing the layer structure of a conventional low-cost electrical contact. In the figure, ■ is the contact base, 2 is the conductive adhesive layer, 3 is the surface layer,
4 represents a Cu--Ni diffusion layer, respectively. Concave Example 1 of the Inventive Fire Scaling Example 1 [Possible cross-sectional view of the layer structure in the country No. 2 Figure 7 type electric cherry shield of the past, and the characteristics of the history example and Tsumezuma No. 2
3 diagram

Claims (1)

[Claims] 1) Contact base (1) made of Fe-Ni magnetic material and C
Consisting of a u-Ni diffusion layer (4) and a surface layer (3), the Cu-Ni diffusion layer (4) is formed by diffusing Cu and Ni plated on the contact base (1), The diffusion layer (4)
An electrical contact characterized in that the surface layer (3) is formed by plating Rh on top. 2) A Cu-Ni diffusion layer (4) formed by diffusing Cu and Ni plated on the contact base (1), and a surface layer (3).
2. The electrical contact according to claim 1, wherein a conductive adhesive layer (2) is interposed between the conductive adhesive layer (2) and the conductive adhesive layer (2).