JPH06283082A - Reed switch - Google Patents

Abstract

PURPOSE:To improve productivity by maintaining low price quality and characteristics, regarding the constitution of a reed switch having a sealed reed piece. CONSTITUTION:The intermediate sections of two reed pieces 41-1 and 41-2, each having one end flattened and formed as a contact area covered with a contact material, are sealed and fixed at both ends of a glass tube filled with inert gas, so as to keep the contact areas faced to each other via the predetermined gap. Regarding the reed switch so constructed, the surface of the contact material having a copper-nickel diffused layer 21b as a substrate is covered with a diffused layer 41b composed of the layer 21b and another diffused layer 41b of a gold plated layer 41a of or silver plated layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reed switch having a reed piece enclosed therein, and more particularly to a reed switch which has improved productivity by ensuring low price and characteristics.

With the recent progress of electronic technology, various electronic parts are strongly required to be low in price and to be improved in characteristics. In the field of reed switches, however, customers are required to reduce the price. A major issue is how to provide a reed switch that is adaptable and excellent in characteristics.

[0003]

2. Description of the Related Art FIG. 3 which illustrates the technical background is a schematic cross-sectional view for explaining an example of the structure of a conventional general reed switch. A partially extracted enlarged view (a) shows a contact area of a reed piece. It is an enlarged view.

FIG. 4 is a sectional view showing an example of the structure of a lead terminal of a low cost reed switch, and FIG. 5 is a sectional view showing an example of the structure of a reed switch with improved characteristics shown in FIG. 4 and 5, a reed switch similar to the reed switch of FIG. 3 is taken as an example, and therefore, the same target members and parts as those in FIG. 3 are denoted by the same symbols.

In FIG. 3, the reed switch 1 has a flat end portion of the reed piece materials 11 _-1 ′ and 11 _-2 ′, and is made of rhodium (Rh) or ruthenium (Ru) at the tip region of the flattened end. Contact area 11 with plating layer 11a 'as contact material made of platinum group
The two lead pieces 11 _-1 , 11 _-2 made of 52 alloy alloy formed on a are faced with nitrogen (N) as an inert gas so that their contact areas 11a face each other with a predetermined contact gap δ. ₂ )
It is configured by sealing both ends of the glass tube 12 in a state of enclosing.

Therefore, the contact area 11 on the outer circumference of the glass tube 12
By arranging a permanent magnet or a coil (not shown) in a region corresponding to a and applying a magnetic field to the contact region 11a or removing the magnetic field, the two contact regions 11a facing each other can be attracted or separated. Therefore, the two lead pieces 11 _-1 , 11
It is possible to configure the reed switch 1 as a switching element that connects or disconnects _-2 .

In such a reed switch 1, since the contact area is located in a sealed inert gas atmosphere, the contact area itself is covered with a stable platinum group without being affected by the surrounding atmosphere. Therefore, a reed switch that can maintain stable contact characteristics for a long period of time without being oxidized can be configured.

However, since the plated metal as the contact material forming the contact area is of the platinum group as described above, the cost is high and it may not be possible to meet the customer's demand for price reduction.
Therefore, various reed switches for responding to this customer request have been put into practical use as shown in FIGS.

That is, in FIG. 4 showing an example thereof, (4-1) indicates the lead piece materials 11 _-1 ′ and 11 _-2 ′ described in FIG. Therefore, a copper (Cu) plating layer 21a 'having a thickness of about 2 μm and a thickness of 1.5 μm is provided in the contact area of the flattened end.
The nickel (Ni) plating layer 21a ″ of about m is laminated in order.
After the state of (4-2), for example, by heating at 850 ° C for about 15 minutes to diffuse both, the contact area is covered with the copper-nickel diffusion layer 21b as shown in (4-3). It is possible to obtain two lead pieces 21 _-1 , 21 _-2 made of the broken 52 alloy alloy.

Therefore, the reed switch 2 shown in (4-4) can be constructed by enclosing the two reed pieces 21 _-1 , 21 _-2 in the glass tube 12 described in FIG. In such a reed switch 2, since the contact area is covered with the copper-nickel diffusion layer 21b having excellent life characteristics, there is an advantage that the reed switch having a contact material made of rhodium or ruthenium described above in terms of life can be substituted. .

However, since the contact region is covered with the base metal diffusion layer, it is easily oxidized and the contact resistance between the lead pieces, in other words, the switching resistance of the reed switch becomes large.

FIG. 5 has been put into practical use in order to suppress such a drawback. That is, FIG. 5 shows an example of using rhodium as a contact material, and FIG.
The lead pieces 21 _-1 and 21 _-2 described in _1. are connected to the copper-nickel diffusion layer 21b that forms the contact area as shown in the partially enlarged view (a).
For example, a rhodium plating layer with a thickness of 0.2 to 1.0 μm on the surface of
The reed switch 3 is constructed by replacing the reed pieces 31 _-1 , 31 _{-2, which} are formed by using 1a as a contact material, and enclosing the reed switch 31 _-1 , _31-2 with a glass tube 12 similar to that shown in FIG.

In such a reed switch 3, since the thickness of the rhodium plating layer 31a can be set to a thickness sufficient to prevent the oxidation of the contact material surface, the lead layer material 11 _-1 ', 11 _-2 ' is directly plated with the plating layer. The thickness of the reed switch 1 can be made smaller than that of the reed switch 1.

Therefore, a reed switch which is cheaper in price than the reed switch 1 of FIG. 3 can be realized without deteriorating the characteristics.

[0015]

However, since platinum group rhodium or ruthenium is used as the contact material in order to secure the characteristics as a reed switch, the price reduction rate is restricted, and the customer's request for further price reduction is required. There was a problem that there were things we could not handle.

[0016]

SUMMARY OF THE INVENTION The above-mentioned problem is that the flattened end is formed in the contact area covered with the contact material.
A reed switch in which individual lead pieces are sealed and fixed at both ends of a glass tube filled with an inert gas at their intermediate portions so that the contact areas face each other with a required gap maintained. This is achieved by a reed switch in which the surface of the contact material having the copper-nickel diffusion layer as a base is covered with the diffusion layer of the copper-nickel diffusion layer and the gold plating layer or the silver plating layer.

[0017]

In general, gold (Au) and silver (Ag) have the property of easily diffusing with the copper-nickel diffusion layer and are cheaper than rhodium and ruthenium belonging to the platinum group.

Further, the thickness of the plating layer deposited on the underlayer for the purpose of forming a diffusion layer between the underlayer and the underlayer can be made smaller than that when the plating layer is used as it is. Therefore, in the present invention, the contact material formed at the end of the lead piece is composed of a copper-nickel diffusion layer and a diffusion layer of gold or silver.

This means that the contact material can be formed of a cheap base metal layer and a thin diffusion layer of gold or silver, so that the cost can be lower than that of the reed switch described with reference to FIG. The presence of chemically stable gold or silver on the surface of the material means that deterioration of characteristics as a reed switch can be suppressed.

Therefore, it is possible to construct a reed switch that can meet the customer's request for price reduction without deteriorating the characteristics, and it is possible to expect an improvement in productivity.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the construction of a reed switch according to the present invention step by step, and FIG. 2 is a diagram showing characteristics of the reed switch according to the present invention in comparison with a conventional product.

In the drawings, a reed switch similar to that shown in FIGS. 3 to 5 is taken as an example. Therefore, the same target members and parts as those shown in FIGS. Omit it.

In the example of FIG. 1 in which the surface of the contact material is a diffusion layer with gold, (1-1) is the lead piece material 11 described in FIG.
_-1 ', 11 _-2 '. Then, the copper-nickel diffusion layer 21b described in FIG. 4 is formed in the contact region of the flattened end portion to bring it to the state of (1-2), and then the copper-nickel diffusion layer 21b is formed.
A gold plating layer 41a having a thickness of 0.01 to 0.2 μm is adhered and formed on the surface of (1)-(3).

Then, the lead piece on which the gold plated layer 41a is formed is subjected to, for example, an ordinary heat treatment furnace, an infrared lamp, or the like.
When heated at 250 ° C for about 30 minutes, the gold plating layer 41a diffuses with the diffusion layer 21b at the surface layer of the copper-nickel diffusion layer 21b, so that the contact material is covered with the gold diffusion layer 41b as shown in (1-4). The broken lead pieces 41 _-1 , 41 _-2 can be obtained.

Therefore, the reed switch 4 shown in (1-5) can be constructed by enclosing the two reed pieces 41 _-1 , 41 _-2 in the glass tube 12 described in FIG. In such a reed switch 4, the contact material is made of copper-having excellent life characteristics.
Since it is composed of the nickel diffusion layer 21b and the chemically stable gold diffusion layer 41b, it is possible to easily form a reed switch that is inexpensive and excellent in characteristics.

The gold diffusion layer described above is the gold plating layer 41a.
It can also be formed by the heat transferred to the lead piece when the lead piece in the state of being formed, that is, the lead piece in the state shown in (1-3) above is sealed in the glass tube 12.

FIG. 2 is a graph showing an example of the measurement data of the contact resistance between the lead pieces, and by extension, the switching resistance as a reed switch. The resistance value distribution when the contact resistance value R is taken on the horizontal axis is logarithmic. It is represented by probability paper. (Number of samples = 100) That is, in the figure, indicates the resistance value distribution of the reed switch 1 described in FIG.
The reed switch 2 described in 1 is the resistance value distribution of the reed switch 3 described in FIG. 5 or the reed switch 4 according to the present invention described in FIG. 1, respectively.

In this case, as is clear from FIG. 2, the reed switch 4 of the present invention, that is, the reed switch 1 in which the material of the reed pieces is directly subjected to the rhodium plating treatment, that is, the resistance distribution is almost the same. From
A reed switch that is characteristically stable can be obtained.

The gold plating layer provided on the copper-nickel diffusion layer described in FIG. 1 is replaced with the copper-nickel diffusion layer and the silver plating layer which is easy to diffuse like gold, and the copper-nickel diffusion layer is thermally diffused. It has been experimentally confirmed that almost the same effect can be obtained by forming a silver diffusion layer on the nickel diffusion layer.

[0030]

As described above, according to the present invention, it is possible to provide a reed switch whose productivity is improved by ensuring the characteristics while maintaining the low price.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the configuration of a reed switch according to the present invention step by step.

FIG. 2 is a diagram showing the characteristics of the reed switch of the present invention in comparison with a conventional product.

FIG. 3 is a diagram illustrating a technical background.

FIG. 4 is a cross-sectional view showing a configuration example of lead terminals of a low price reed switch.

FIG. 5 is a cross-sectional view showing a configuration example of a reed switch for improving the characteristics shown in FIG.

[Explanation of symbols]

4 Reed switch 11 _-1 ', 11 _-2 ' Lead piece material 12 Glass tube 21b Copper-nickel diffusion layer 41 _-1 , 41 _-2 Lead piece 41a Gold plating layer 41b Gold diffusion layer

Claims (1)

[Claims] 1. A two lead piece having a flattened end formed in a contact area covered with a contact material, and an intermediate portion between the two lead pieces is opposed so that the contact areas face each other with a required gap. A reed switch that is sealed and fixed at both ends of a glass tube filled with an active gas, wherein the surface of the contact material laid on the copper-nickel diffusion layer (21b) in the contact area is the copper-nickel diffusion layer. A reed switch characterized by being constituted by being covered with a diffusion layer (41b) of a layer (21b) and a gold plating layer (41a) or a silver plating layer.