JP2004288557A - Reed switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable reed switch preventing cracks in a contact film layer and having a long contact life. <P>SOLUTION: The reed switch is formed by arranging a first contact film layer containing one kind of element out of iridium (Ir), ruthenium (Ru) and rhodium (Rh) as a main component on a contact surface of a reed piece, and arranging a second contact film layer composed of a plurality of layers including a single layer containing at least rhodium (Rh) as a main component, or a plurality of layers containing rhodium (Rh) as a main component, or a diffusion layer of a metallic magnetic material made of gold, silver, copper, nickel, etc., on the lower layer at a contact surface side of the first contact film layer for relaxing the stress. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a reed switch having a reed piece as a contact, and more particularly to a configuration of the contact.
[0002]
[Prior art]
Conventionally, as shown in FIG. 3, a reed switch has a pair of elongated lead pieces 1 and 2 each having one end as a contact portion, and having these contact portions 10 and 20 in a vacuum state or a state in which an inert gas is sealed. It has a structure sealed in a container 3 consisting of a tube. The lead pieces 1 and 2 are formed of a metal magnetic material such as an iron-nickel alloy, for example, and the respective contact portions 10 and 20 are arranged with a predetermined overlap and an interval therebetween. In addition, on the contact surfaces where the respective contact portions oppose each other, gold (Au) is disposed on the base coat layers 11 and 21, and then contact coat layers 12 and 22 containing iridium (Ir) as a main component are formed. It had been. (For example, see Patent Document 1)
[0003]
[Patent Document 1]
JP-A-5-186953 (paragraph 007, FIG. 1)
[0004]
[Problems to be solved by the invention]
However, in the contact configuration of the conventional reed switch as described above, thermal expansion occurs in the lead piece due to heat when the contact portion is sealed with glass, and the metal magnetic material and iridium (Ir) that constitute the lead piece are mainly used. The stress caused by the difference in the amount of thermal expansion between the contact coating layers as components causes cracks in the contact coating layer containing iridium (Ir) as a main component, thereby deteriorating the contact life. Therefore, it has been desired to develop a stable reed switch having a long contact life and preventing a contact coating layer from being cracked due to a difference in thermal expansion.
[0005]
[Means for Solving the Problems]
The reed switch of the present invention is a reed switch having a reed piece as a contact, wherein one of iridium (Ir), ruthenium (Ru) or rhodium (Rh) is mainly provided on the contact surface of the reed piece. A first contact coating layer as a component is disposed, and a single layer containing rhodium (Rh) as a main component or a layer containing rhodium (Rh) as a main component is provided below the first contact coating layer on the contact surface side. And a second contact coating layer for stress relaxation consisting of a plurality of layers.
[0006]
Further, a reed switch according to the present invention is a reed switch having a reed piece, and one of iridium (Ir), ruthenium (Ru), and rhodium (Rh) is mainly provided on a contact surface of the reed piece. A first contact coating layer, an undercoating layer made of at least one kind of transition metal or an alloy of each of them as a lower layer on the contact surface side of the first contact coating layer, and a metal magnetic material constituting a lead piece And a diffusion layer made of the same metal as that of the undercoat layer.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
[Embodiment 1]
FIG. 1 is an explanatory diagram illustrating a configuration according to the first embodiment of the present invention.
In the figures, reference numerals 1 and 2 denote lead pieces, 10 and 20 denote contact portions, 11 and 21 denote undercoat layers, 13 and 23 denote second contact coating layers, and 14 and 24 denote first contact coating layers.
On the contact surface where the contact portion 10 and the contact portion 20 face each other, on the surface of the metal magnetic material constituting the lead pieces 1 and 2, an undercoating layer 11 using a transition metal, particularly gold, silver, copper, nickel, or the like is provided. , 12 are formed. The thickness of the undercoat layers 11 and 12 is set to about 0.2 to 1.0 μm.
[0008]
The thickness of the undercoat layers 11 and 12 is preferably as thin as possible within a range having the underlayer characteristics of the coating of the second contact coating layers 13 and 23 on the metallic magnetic material. However, if the thickness is less than 0.2 μm, the underlayer characteristics may be partially uneven (mainly due to pinholes in the plating method), and even if the thickness is more than 1.0 μm, the underlayer characteristics (adhesion) change little. When the contact is damaged by opening / closing the load circuit, the diffusion density of the underlying metal in the damaged portion increases, which causes a sticking phenomenon or the like that deteriorates the contact life. Therefore, it is desirable to set the thickness to about 0.2 to 1.0 μm.
[0009]
After the above base treatment, the second contact coating layers 13 and 23 are formed on the contact portions 10 and 20 of the lead pieces 1 and 2 using rhodium (Rh). The thickness of the second contact coating layers 13 and 23 is about 0.5 to 5.0 μm.
Next, the first contact coating layers 14 and 24 are formed on the second contact coating layers 13 and 23 using one of iridium (Ir), ruthenium (Ru) and rhodium (Rh). The thickness of the first contact coating layers 14, 24 is about 0.5 to 2.0 μm.
[0010]
Glass sealing is performed using the lead piece having the above-described contact configuration. In this case, thermal expansion occurs in the reed contact portions 10 and 20 due to sealing heat.
At this time, the difference in the amount of thermal expansion causes a difference between the metal magnetic material and the base coat layers 11 and 12, between the base coat layers 11 and 12 and the second contact coat layers 13 and 23, and between the second contact coat layers 13 and 23-first. Although a stress corresponding to the amount of expansion is generated between the contact coating layers 14 and 24, the rhodium (Rh) of the second contact coating layers 13 and 23 is materially resistant to stress that can sufficiently withstand the sealing heat. And the expansion coefficient of iridium (Ir) is about 8 × 10 ⁻⁶ / ° C., and the expansion coefficient of ruthenium (Ru) is also about 6.7 × 10 ⁻⁶ / ° C. Since this is almost the same as the expansion coefficient of rhodium (Rh), the stress applied to the first contact coating layers 14 and 24 can be suppressed, and iridium (Ir) or ruthenium (Ru) having poor ductility can be used as a contact. Even when used for coating, it can prevent cracks due to heat .
[0011]
From the above, the thickness of the first contact coating layers 14 and 24 can be uniquely determined depending on the frequency of use and the required life, and should be appropriately selected in the range of 0.5 to 2.0 μm in a normal use state. Can be.
[0012]
Further, the thickness of the second contact coating layers 13 and 23 needs a thickness for relaxing the thermal stress, and the shear stress at the interface between the first contact coating layers 14 and 24 is within the allowable stress. Must be chosen. It is determined by the sealing temperature, the difference between the coefficients of expansion between the coating layers, the allowable shear stress of the first contact coating layers 14, 24, and the like. Under normal conditions, the thickness is selected to be thicker than the thickness of the first contact coating layers 14 and 24 and about 0.5 to 5.0 μm.
[0013]
As described above, as the lower layer of the first contact coating layers 14 and 24 having poor ductility such as iridium (Ir) and ruthenium (Ru), the second contact which is a preliminary contact coating for relaxing thermal stress of rhodium or the like. By forming the coating layers 13 and 23, generation of cracks in the contact coating due to sealing heat or the like is suppressed. For this reason, a reed switch suitable for a high load application or a long life application can be obtained by fully utilizing the physical properties of iridium (Ir) and ruthenium (Ru) such as high melting point and high hardness.
[0014]
[Embodiment 2]
FIG. 2 is an explanatory diagram showing a configuration according to the second embodiment of the present invention.
In the figure, 15 and 25 are diffusion layers. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.
[0015]
In the present embodiment, rhodium (Rh) is used for relaxing the stress in the first embodiment, which may increase the cost. On the other hand, rhodium (Rh) is not used. , At a low cost.
[0016]
In FIG. 2, transition metals or their alloys, particularly gold, silver, copper, nickel, etc., are formed on the surfaces of the contact portions 10, 20 of the lead pieces 1, 2 formed of a metal magnetic material such as an iron-nickel alloy. Using at least one of these alloys, a coating of 1.0 to 5.0 μm is formed, and then thermally diffused to the surface of the metal magnetic material in a high-temperature hydrogen atmosphere of about 800 to 1000 ° C. , Diffusion layers 15 and 25 are formed.
[0017]
Next, in order to enhance the adhesion of the first contact coating layers 12 and 22 to be performed later, a transition metal of the same material as the coating or an alloy thereof, particularly gold, silver, copper, nickel or the like, or each of them. The undercoat layers 11 and 21 are formed of at least one kind of alloy and having a thickness of about 0.2 to 0.5 μm. The purpose of the undercoat layers 11 and 21 is to enhance the adhesion of the first contact coat layers 12 and 22. The thickness of the undercoat layers 11 and 21 does not need to be large, and the limit of uniform coating in terms of cost is 0.2. About 0.5 μm is preferable.
Thereafter, a first contact coating layer mainly composed of one of iridium (Ir), ruthenium (Ru) and rhodium (Rh) having a thickness of about 0.5 to 2.0 μm is formed on the base coating layers 11 and 21. 12 and 22 are formed.
[0018]
As described above, when glass sealing is performed using the lead pieces 1 and 2, thermal expansion occurs in the lead piece contact portions 10 and 20 due to sealing heat. Here, a diffusion layer using at least one of transition metals or their alloys, particularly gold, silver, copper, nickel, or their alloys, is formed on the surfaces of the contact portions 10 and 20 in advance. This changes the amount of thermal expansion, thereby relaxing and absorbing the thermal stress generated between the metal magnetic body and the first contact coating.
[0019]
As described above, according to the second embodiment, a transition metal or each alloy thereof, particularly, a transition metal, is formed under the first contact coating layers 12 and 22 having poor ductility such as iridium (Ir) and ruthenium (Ru). By forming undercoating layers 11 and 21 made of at least one of gold, silver, copper, nickel and the like and their alloys and a diffusion layer of a metal magnetic material, cracks in the contact coating can be further reduced at low cost. Generation can be suppressed.
[0020]
[Embodiment 3]
In the first and second embodiments, the contact structure is such that one of iridium (Ir), ruthenium (Ru) or rhodium (Rh) is applied to the first contact coating layers 12 and 22 as a main component. Although described in detail, the present invention can be applied to a case where a contact material belonging to the same platinum-based metal is used instead of these for the same purpose.
[0021]
【The invention's effect】
According to the present invention, a first contact coating layer mainly composed of one of iridium (Ir), ruthenium (Ru) and rhodium (Rh) is provided on a contact surface of a lead piece, and the first contact coating layer is provided. A second contact coating layer for stress relaxation, comprising a single layer containing at least rhodium (Rh) as a main component or a plurality of layers including a layer containing rhodium (Rh) as a main component as the lower layer on the contact surface side. The arrangement prevents cracks in the contact coating layer and provides a stable reed switch with a long contact life.
[0022]
The present invention also provides a first coating layer containing one of iridium (Ir), ruthenium (Ru) and rhodium (Rh) as a main component on a contact surface of the lead piece. An undercoat layer made of at least one of a transition metal or an alloy thereof, in particular, gold, silver, copper, nickel or an alloy thereof, and a metal magnetic layer forming a lead piece. By arranging the diffusion layer by the base coat layer of the body in order, it is possible to prevent the occurrence of cracks in the contact coat layer, and to provide a stable and inexpensive reed switch having a long contact life.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating a configuration according to a first embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating a configuration according to a second embodiment of the present invention.
FIG. 3 is an explanatory diagram showing a configuration of a conventional reed switch.
[Explanation of symbols]
1, 2 lead pieces, 10, 20 contact portions, 11, 21 base coat layer, 13, 23 second contact coat layer, 14, 24 first contact coat layer, 15, 25 diffusion layer.

Claims (5)

A reed switch having a reed piece as a contact, wherein a first contact coating layer mainly composed of one of iridium (Ir), ruthenium (Ru) and rhodium (Rh) is provided on the contact surface of the reed piece. A stress layer consisting of at least a single layer containing rhodium (Rh) as a main component or a plurality of layers containing a layer containing rhodium (Rh) as a main component, as a lower layer on the contact surface side of the first contact coating layer. A reed switch comprising a second contact coating layer for relaxation. A reed switch having a reed piece as a contact, wherein a first coating layer containing one of iridium (Ir), ruthenium (Ru), and rhodium (Rh) as a main component is provided on a contact surface of the reed piece. An undercoat layer made of at least one of a transition metal or an alloy thereof, and an undercoat layer made of at least one kind of an alloy of the transition metal and each of their alloys, which are the same metal as the undercoat layer of the metal magnetic material constituting the lead piece. A reed switch characterized by sequentially disposing diffusion layers according to (1). The reed switch according to claim 2, wherein the transition metal is selected from gold, silver, copper, and nickel. The thickness of the said 1st contact coating layer is 0.5-2.0 micrometers, and the thickness of the said 2nd contact coating layer is 0.5-5.0 micrometers, The claim of Claim 1 characterized by the above-mentioned. Reed switch. The thickness of the first contact coating layer is 0.5 to 2.0 μm, the thickness of the diffusion layer is 0.5 to 2.0 μm, and the thickness of the base coating layer is 0.5 to 2.0 μm. The reed switch according to claim 2 or 3, wherein:

Images