JP2010092880A - Reed switch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable reed switch which prevents cracks of a contact coating layer and of which a contact life is long. <P>SOLUTION: A base coating layer formed of transition metal of which thicknesses are 0.2-1.0 μm (except for a thickness 0.5 μm or more) or at least one of alloys of them is formed on a contact surface of a reed piece by plating. Then, a second contact coating layer for stress relaxation, formed of a single layer mainly containing at least rhodium (Rh) and a plurality of layers including a layer mainly containing the rhodium (Rh), is arranged on an upper layer on a surface side of the base coating layer. In addition, a first contact coating layer, of which a thickness is 0.5-2.0 μm (except for a thickness of 1 μm or more) and which mainly contains iridium (Ir), is arranged on an upper layer on a surface side of the second contact coating layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reed switch having a lead piece as a contact, and more particularly to a configuration of the contact.

  Conventionally, as shown in FIG. 3, the reed switch is a glass in which one end of each of a pair of elongated lead pieces 1 and 2 is used as a contact portion, and the contact portions 10 and 20 are in a vacuum state or an inert gas is contained. It has a structure enclosed in a container 3 made of a tube. The lead pieces 1 and 2 are made of, for example, a metal magnetic material such as an iron-nickel alloy, and the contact portions 10 and 20 are arranged with a predetermined overlap and spacing therebetween. In addition, contact film layers 12 and 22 mainly composed of iridium (Ir) are formed after gold (Au) is disposed on the undercoat film layers 11 and 21 on the contact surfaces, which are contact surfaces of the respective contact portions. It had been. (For example, see Patent Document 1)

Japanese Patent Laid-Open No. 5-186533 (paragraph 007, FIG. 1)

  However, in the contact configuration of the conventional reed switch as described above, thermal expansion occurs in the lead piece due to heat generated when the contact portion is sealed with glass, and the metal magnetic material and iridium (Ir) constituting the lead piece are mainly used. The stress due to the difference in thermal expansion between the contact film layers as components causes cracks in the contact film layer containing iridium (Ir) as a main component, thereby deteriorating the contact life. Accordingly, there has been a demand for the development of a stable reed switch that prevents cracks in the contact coating layer due to a difference in thermal expansion and has a long contact life.

  The reed switch of the present invention is a reed switch having a reed piece as a contact, and the contact surface of the reed piece has a thickness of 0.2 μm or more and 1.0 μm or less (except 0.5 μm or more) by plating. An undercoating layer made of at least one of these transition metals or their alloys is provided, and the upper layer on the surface side of the undercoating layer is mainly composed of at least a single layer mainly composed of rhodium (Rh) or rhodium (Rh). A second contact coating layer for stress relaxation comprising a plurality of layers including a component layer is disposed, and the upper layer on the surface side of the second contact coating layer is mainly composed of iridium (Ir). A first contact coating layer having a thickness of 0.5 μm or more and 2.0 μm or less (excluding 1 μm or more) is provided.

  In the reed switch according to the present invention, the thickness of the second contact coating layer is 0.5 to 5.0 μm (excluding 2.5 μm or more).

  The present invention provides an undercoat layer comprising a transition metal having a thickness of 0.2 μm or more and 1.0 μm or less (excluding 0.5 μm or more) by plating or at least one of their alloys on the contact surface of a lead piece. Further, for the purpose of stress relaxation, the upper layer on the surface side of the undercoat layer is composed of 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. The thickness of the second contact coating layer is 0.5 μm or more and 2.0 μm or less (however, 1 μm or more) on the upper surface layer of the second contact coating layer. The first contact coating layer (except for the above) is provided, so that the contact coating layer can be prevented from cracking, and a stable reed switch having a long contact life can be provided.

It is explanatory drawing which shows the structure in Embodiment 1 of this invention. It is explanatory drawing which shows the structure in Embodiment 2 of this invention. It is explanatory drawing which shows the structure of the conventional reed switch.

[Embodiment 1]
FIG. 1 is an explanatory diagram showing a configuration according to Embodiment 1 of the present invention.
In the figure, 1 and 2 are lead pieces, 10 and 20 are contact portions, 11 and 21 are base coating layers, 13 and 23 are second contact coating layers, and 14 and 24 are first contact coating layers.
On the contact surface where the contact portion 10 and the contact portion 20 face each other, a base coating layer 11 using a transition metal, particularly gold, silver, copper, nickel, or the like is used on the surface of the metal magnetic body constituting the lead pieces 1 and 2. , 12 are formed. The thickness of the base coating layers 11 and 12 is about 0.2 to 1.0 μm.

  The thickness of the undercoat layers 11 and 12 is preferably as thin as possible as long as the second contact coat layers 13 and 23 have the undercoat characteristics of the coating on the metal magnetic material. However, if the thickness is 0.2 μm or less, the substrate characteristics may be partially uneven (mainly due to pinholes in the plating method). In addition, when contact damage progresses by opening and closing the load circuit, the base metal diffusion concentration in the damaged portion increases, which may cause an adhesive phenomenon that deteriorates the contact life. Therefore, it is desirable that the thickness is about 0.2 to 1.0 μm.

After the base treatment, 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 and 24 is about 0.5 to 2.0 μm.

Glass sealing is performed using the lead piece configured as described above. In this case, thermal expansion occurs in the lead piece contact portions 10 and 20 due to sealing heat.
At this time, due to the difference in thermal expansion amount, between the metal magnetic material and the base coating layer 11, 12, between the base coating layer 11, 12 -the second contact coating layer 13, 23, the second contact coating layer 13, 23-1 Although 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 stress resistant enough to withstand the sealing heat in terms of material. 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 approximately 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 contacted. Even if it uses for a film, generation | occurrence | production of the crack by a heat | fever can be prevented.

  From the above, the thickness of the first contact coating layers 14 and 24 can be uniquely determined by the use frequency and the required life, and should be appropriately selected in the range of 0.5 to 2.0 μm in the normal use state. Can do.

  Further, the thickness of the second contact film layers 13 and 23 requires a thickness for relaxing the thermal stress so that the shear stress at the interface between the first contact film layers 14 and 24 is within the allowable stress. Must be chosen. It is determined by the sealing temperature, the difference in expansion coefficient between the coating layers, the allowable shear stress of the first contact coating layers 14 and 24, and the like. Under normal conditions, the thickness is selected to be greater than the thickness of the first contact coating layers 14 and 24 and about 0.5 to 5.0 μm.

  As described above, as a lower layer of the first contact coating layers 14 and 24 having poor ductility such as iridium (Ir) and ruthenium (Ru), the second contact is a preliminary contact coating for relieving thermal stress such as rhodium. By forming the coating layers 13 and 23, occurrence of cracks in the contact coating due to sealing heat or the like is suppressed. For this reason, a reed switch suitable for high load applications and long life applications can be obtained by fully utilizing the physical properties of iridium (Ir) and ruthenium (Ru), which have a high melting point and high hardness.

[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. In addition, the same code | symbol is attached | subjected about the component same as FIG. 1, and description is abbreviate | omitted.

  In the present embodiment, rhodium (Rh) is used for stress relaxation in the above-described first embodiment, which may increase the cost, but without using rhodium (Rh). It is intended to achieve the same purpose at low cost.

  In FIG. 2, transition metal or their respective alloys, particularly gold, silver, copper, nickel, etc. Using at least one of these alloys, a film of 1.0 to 5.0 μm is formed, and then thermally diffused on the surface of the metal magnetic body in a high-temperature hydrogen atmosphere of about 800 to 1000 ° C. The diffusion layers 15 and 25 are formed.

Subsequently, in order to enhance the adhesion of the first contact coating layers 12 and 22 to be implemented later, the transition metal of the same material as the coating or their respective alloys, particularly gold, silver, copper, nickel, etc. or each of them Undercoat layers 11 and 21 having a thickness of about 0.2 to 0.5 μm and made of at least one kind of alloy are formed. The purpose of the underlying coating layers 11 and 21 is to improve the adhesion of the first contact coating layers 12 and 22, and the thickness does not need to be thick. About -0.5 micrometer is preferable.
Thereafter, a first contact coating layer mainly composed of one of iridium (Ir), ruthenium (Ru) and rhodium (Rh) of about 0.5 to 2.0 μm is formed on the base coating layers 11 and 21. 12 and 22 are formed.

  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 respective alloys, particularly gold, silver, copper, nickel, or their respective alloys is formed in advance on the surfaces of the contact portions 10 and 20. As a result, the amount of thermal expansion changes, so that the thermal stress generated between the metal magnetic body and the first contact film is relaxed and absorbed.

  As described above, according to the second embodiment, the transition metal or their respective alloys, in particular, under the first contact coating layers 12 and 22 having poor ductility such as iridium (Ir) and ruthenium (Ru). By forming the base coating layers 11 and 21 made of at least one of gold, silver, copper, nickel, etc., or their respective alloys, and the diffusion layer of the metal magnetic material, the cracks of the contact coating can be reduced at a lower cost. Occurrence can be suppressed.

[Embodiment 3]
In the first and second embodiments, the contact configuration is the case where one of iridium (Ir), ruthenium (Ru), and rhodium (Rh) is applied as the main component to the first contact coating layers 12 and 22. Although described in detail, the present invention can be applied to the case where contact materials belonging to the same platinum metal are used instead of these for the same purpose.

  1, 2 Lead piece, 10, 20 Contact part, 11, 21 Undercoat layer, 13, 23 Second contact layer, 14, 24 First contact layer, 15, 25 Diffusion layer.

Claims (2)

A lead switch having a lead piece as a contact, and on the contact surface of the lead piece,
An undercoat layer made of at least one transition metal or an alloy thereof having a thickness of 0.2 μm or more and 1.0 μm or less (excluding 0.5 μm or more) is provided by plating, and further, the undercoat layer surface side In the upper layer,
A second contact coating layer for stress relaxation comprising at least a single layer containing rhodium (Rh) as a main component or a plurality of layers including a layer containing rhodium (Rh) as a main component;
Furthermore, a first contact coating layer having a thickness of 0.5 μm or more and 2.0 μm or less (excluding 1 μm or more) having iridium (Ir) as a main component is disposed on the upper surface of the second contact coating layer. A reed switch characterized by being provided.   2. The reed switch according to claim 1, wherein the thickness of the second contact coating layer is 0.5 to 5.0 μm (excluding 2.5 μm or more).

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