JP2001043762A - Electrical contact, manufacture thereof, and reed switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent local concentration of wear of a contact surface and extend a contact switching service-life without causing various characteristics required as an electrical contact to deteriorate. SOLUTION: This electrical contact 10 comprises a multi-layer metal coating 14 placed on a contact base material 12. The multi-layer metal coating 14 comprises a substrate layer 16 plated on the surface 12a of the contact base material 12 and the outermost layer 18 plated on the surface 16a of the substrate layer 16. The surface 16a of the substrate layer 16 is actively worn out by electric discharge process to be roughed to a desired surface roughness. The surface 18a of the outermost layer 18 is applied with many micro recesses and projections, corresponding to a recess and projection shape of the surface 16a of the substrate layer 16. The surface 18a of the outermost layer 18 roughed in this manner prevents repeating of local contact between contacts and local concentration of wear following this, and therefore, acts so as to extend a contact switching service life. Since the surface 18a is not post-processed in making roughness, various characteristics are not deteriorated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrical contact and a method for manufacturing the same. Further, the invention relates to a reed switch having electrical contacts.

[0002]

2. Description of the Related Art In recent years, in order to further improve the reliability of electric / electronic devices, operable electric contacts provided in switches and relays are required to have higher performance. In particular, regarding the switching life of contacts, for example, DC
It is required to withstand hundreds of millions of switching operations in a load region of several mA at 3V or 5V DC, or AC100.
For example, it is required to be able to be used for a long period even in a load region of 100 W class at V or 200 V AC, and it is required to promote long life over a wide range of voltage and current.

For example, Japanese Patent Application Laid-Open No. 4-132122 discloses that
Disclosed are electrical contacts of a reed switch that can improve the switching life and can be manufactured relatively inexpensively. The electrical contact includes a copper nickel diffusion layer formed on a contact base and a rhodium plating layer formed on the copper nickel diffusion layer. The copper-nickel diffusion layer not only has good characteristics as an electrical contact, but also has the advantage that the material cost is lower than that of a noble metal such as gold or rhodium. The rhodium plating layer is a surface reinforcing film for improving the durability of the copper-nickel diffusion layer, and its thickness can be reduced as long as the reinforcing function can be exhibited, so that a rise in material costs can be avoided.

[0004]

Generally, electrical contacts tend to wear out due to electrolytic radiation or the like generated by switching operation under a load condition. Due to this wear, when the constituent material of the contact surface transfers between a pair of contacts,
Irregularities due to the transfer material are formed on the contact surfaces, and there is a concern that the switching life of the contacts may be affected. In particular, in a situation in which a pair of contacts repeats local contact due to, for example, relative inclination of the contact surface, the wear is concentrated on the contact portion, so that the unevenness of the contact surface due to the transfer material is generated at the contact portion. It may become excessively large, and in some cases, when the contacts are closed, the concave and convex surfaces may fit together, making it difficult to open the contacts thereafter.

As a countermeasure against such a problem, the inventors of the present invention have previously provided fine irregularities on the contact surface, that is, roughened the contact surface in advance to a desired degree, thereby repeating local contact between the contacts. It has been found that the local concentration of the resulting wear can be prevented as much as possible. However, in the method of roughening the contact surface by, for example, chemical treatment, it takes time to obtain a desired surface roughness, so that productivity is low,
Further, since the contact surface is directly treated, there is a concern that various characteristics required for the electric contact may be deteriorated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent local repetition of local contact between contacts and local concentration of wear associated with the contacts as much as possible without deteriorating various characteristics required as electrical contacts. An object of the present invention is to provide an electrical contact and a method for manufacturing the same, which can significantly improve the life. It is another object of the present invention to provide a reed switch having such a long-life electrical contact.

[0007]

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 comprises a contact base and a multilayer metal coating provided on the contact base, wherein the multilayer metal coating is provided. In an electrical contact comprising an underlayer applied to the contact base material and an outermost layer applied to the underlayer, the interface between the underlayer and the outermost layer is a rough surface. Provided is an electrical contact characterized in that the surface of the outermost layer is roughened. According to a second aspect of the present invention, there is provided a reed switch including at least a pair of reed pieces each having the electrical contact according to the first aspect.

According to a third aspect of the present invention, there is provided a contact base material, comprising: a multi-layer metal coating provided on the contact base; In a method for manufacturing an electrical contact comprising an outermost layer adhered to a ground layer, forming a base layer by applying metal plating to a contact base material,
A method for producing an electrical contact, characterized in that the surface of an underlayer is roughened by electric discharge treatment, and the outermost layer is formed by applying metal plating to the roughened surface of the underlayer.

According to a fourth aspect of the present invention, there is provided a method of manufacturing an electrical contact according to the third aspect, wherein the electric discharge is performed between an underlayer adhered to the contact base material and the electrolyte solution. provide. According to a fifth aspect of the present invention, in the method for producing an electrical contact according to the third aspect, the electric discharge is performed in a dry state between the electrode layer and the base layer adhered to the contact base material. provide.

According to a sixth aspect of the present invention, in the method for manufacturing an electrical contact according to any one of the third to fifth aspects, the electrical discharge is performed by applying an alternating current of 50 Hz to 400 Hz. provide. According to a seventh aspect of the present invention, there is provided the method of manufacturing an electrical contact according to any one of the third to sixth aspects, wherein the electric discharge is performed by applying an alternating current of 0.01 A to 1 A. I do.

According to an eighth aspect of the present invention, in the method for manufacturing an electric contact according to any one of the third to seventh aspects, the electric discharge is performed by applying an AC voltage of 10 V to 1000 V. provide. According to a ninth aspect of the present invention, there is provided a reed switch including at least a pair of reed pieces each having an electrical contact manufactured by the manufacturing method according to any one of the third to eighth aspects.

[0012]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by common reference numerals. FIG.
(A)-(c) show the electric contact 10 by one Embodiment of this invention in each stage of a manufacturing process.

The electrical contact 10 includes a contact substrate 12 and a multilayer metal film 14 provided on the contact substrate 12. The multilayer metal coating 14 is applied to the surface 12 of the contact substrate 12.
a and a surface 16a of the underlayer 16
And an outermost layer 18 attached to the outermost layer 18. The interface between the underlayer 16 and the outermost layer 18 (i.e., the surface 16a) is a rough surface having a large number of fine irregularities distributed substantially uniformly throughout.
The surface 18a (that is, the contact surface) of the outermost layer 18 is formed as a rough surface having a large number of minute unevenness corresponding to the uneven shape of the interface 16a.

The electric contact 10 having the above configuration is manufactured according to the following manufacturing method. First, an underlayer 16 made of a general metal material suitable for forming an electrical contact, such as gold or copper, is formed on the surface 12a of the contact base material 12 by, for example, an electroplating process (FIG. 1A). ). Next, the surface 16a of the underlayer 16 is subjected to an electric discharge process described later to
The surface is actively worn and roughened to a desired surface roughness (FIG. 1).
(B)). Finally, the roughened surface 16a of the underlayer 16
Next, an outermost layer 18 made of a metal material having excellent characteristics that can withstand a high load, such as rhodium, ruthenium, and iridium, is formed by, for example, an electroplating process. The surface 18a of the outermost layer 18 thus formed is provided with a large number of fine irregularities corresponding to the irregularities of the surface 16a of the underlayer 16 (FIG. 1C).

As described above, in the electrical contact 10, since the surface 18a of the outermost layer 18 constituting the contact surface is roughened in advance, it is possible to repeat local contact between the contacts and local concentration of the accompanying wear. As a result, the contact switching life can be significantly improved. This operational effect is achieved if at least one of a pair of electrical contacts provided in a switch, a relay, or the like is the electrical contact 10 according to the present invention. Moreover, the outermost layer 18
The fine irregularities on the surface 18a are formed following the irregularities on the surface 16a of the underlayer 16 during the plating process of the outermost layer 18, and are obtained by post-processing the outermost layer 18 itself. However, various characteristics of the outermost layer 18 required as an electrical contact are not deteriorated. Further, by adopting the electric discharge treatment, the surface 16
Since a can be roughened relatively quickly and the surface roughness can be controlled relatively easily, the productivity and yield of the electrical contacts 10 can be improved. In addition, during the electric discharge treatment, a material is diffused between the contact base material 12 and the base layer 16, whereby a secondary action and effect that the two firmly adhere to each other is also exerted.

FIG. 2 shows a reed switch 20 with an electrical contact 10 according to one embodiment of the present invention. The reed switch 20 includes a pair of reed pieces 22 each having the electrical contact 10 at the tip, and a glass tube 24 for sealing the tip area of the reed piece 22 with an inert gas. Each lead piece 22 is formed from a magnetic material such as permalloy, and the electric contact 10 is formed using the magnetic material as the contact base material 12. The reed switch 20 having such a configuration has a remarkably long contact opening / closing life, so that the reliability of electric / electronic devices including the reed switch 20 can be further improved.

FIG. 3 shows an electric discharge device 30 for roughening the surface 16 a of the underlayer 16 of the electric contact 10, for example, in connection with a discharge treatment operation on the reed piece 22 of the reed switch 20. The electric discharge device 30 includes a tank 34 in which an electrolyte solution 32 is stored, an electrode 36 immersed in the electrolyte solution 32 in the tank 34, and a large number of lead pieces 22 that carry the lead pieces 22 and have a blank end 10 ′ ( That is, a support 38 for positioning the electric contact 10) having no outermost layer 18 near the liquid surface of the electrolyte solution 32 and an AC power supply 40 for applying an AC voltage between the electrode 36 and each lead 22 are provided. Be composed. The electrolyte solution 32 can be composed of, for example, a 40% sodium hydroxide solution.

In the electric discharge device 30 having the above configuration,
When the AC power supply 40 is turned on, a large number of lead pieces 2
The electric discharge occurs alternately between the underlayer 16 (FIG. 1) at the blank end 10 'of FIG. 2 and the electrolyte solution 32, whereby the surface 16a of the underlayer 16 is worn and roughened to a desired roughness. Is done. According to such a configuration, a large number of lead pieces 2
After the above-described plating process of the underlayer 16 is performed on the lead pieces 2 collectively, the lead pieces 22 can be subjected to an electric discharge treatment without drying, and the subsequent outermost layer 1
8 can be immediately shifted to the plating step. Therefore, there is an advantage that a series of operation steps for forming the electric contact 10 at the tip of the lead piece 22 can be continuously performed, thereby shortening the operation time.

Alternatively, as shown in FIG. 4, after the plating step of the base layer 16 is performed on a large number of lead pieces 22 at once, the blank end 10 'of the lead pieces 22 is dried, and The electric discharge treatment can be performed between the electrode member 42 and the electrode member 42 in a dry state. In this case, a well-known carbon electrode plate or platinum electrode plate can be used as the electrode member 42.

According to experiments, the roughness R (FIG. 1C) of the surface 18a of the outermost layer 18 of the electrical contact 10 is, for example, about 1 μm to about 2 μm when indicated by the maximum height of the unevenness. At times, it has been found that such local concentration of wear can be effectively prevented. When the maximum height R is less than 1 μm, local contact between the contacts tends to easily occur, and when the maximum height R exceeds 2 μm, the fitting between the concave and convex surfaces tends to easily occur when the contacts are closed.

FIGS. 5 to 7 show experimental results of various electrical conditions for obtaining the target surface roughness R described above.
Basically, for example, in the electric discharge device 30 shown in FIG. 3, when the AC power supply 40 performs electric discharge under the conditions of a voltage of 200 V, a current of 0.1 A, a frequency of 60 Hz, and a discharge time of 30 seconds, The roughness R of the surface 18a could be optimized.

FIG. 5 shows the surface 18 of the outermost layer 18 obtained when the frequency value is variously changed under these basic conditions.
6 is a plot of roughness R of a. As can be seen from the figure, the target surface roughness R of about 1 μm to about 2 μm was obtained relatively stably when an alternating current of 50 Hz to 400 Hz was applied. If the frequency is less than 50 Hz, the uniformity of the unevenness is insufficient and the surface roughness R is too large. If the frequency is more than 400 Hz, the unevenness is too fine and close to a mirror surface.

FIG. 6 shows the surface 18a of the outermost layer 18 obtained when the current value is variously changed under the above basic conditions.
Is a plot of the roughness R of the sample. As can be seen from the figure, the target surface roughness R of about 1 μm to about 2 μm was obtained relatively stably when an alternating current of 0.01 A to 1 A was applied. When the current was less than 0.01 A, the discharge was weak and the irregularities were too small. When the current exceeded 1 A, the discharge was too strong and the surface roughness R was excessive.

FIG. 7 shows the surface 18a of the outermost layer 18 obtained when the voltage value is variously changed under the above basic conditions.
Is a plot of the roughness R of the sample. As can be seen from the figure, when an alternating current of 10 V to 1000 V is applied,
The target surface roughness R of about 1 μm to about 2 μm was obtained relatively stably. When the voltage was less than 10 V, the discharge was weak and the irregularities were too small. When the voltage exceeded 1000 V, the discharge was too strong and the surface roughness R was excessive.

[0025]

As is apparent from the above description, according to the electric contact of the present invention, the local contact between the contacts is repeated and the accompanying wear is caused without deteriorating various characteristics required for the electric contact. Can be prevented as much as possible, thereby significantly improving the switching life. The reed switch according to the present invention having such a long-life electrical contact can further improve the reliability of electric / electronic devices.

[Brief description of the drawings]

FIG. 1 is a partially enlarged cross-sectional view showing a manufacturing process of an electrical contact according to an embodiment of the present invention, in which (a) an underlayer is formed, (b) an electric discharge process is performed on the underlayer, and (c) an outermost layer is formed. Is shown.

FIG. 2 is a sectional view of a reed switch according to an embodiment of the present invention.

FIG. 3 schematically shows an electric discharge device that can be used in the manufacturing method of the present invention.

FIG. 4 schematically shows another electric discharge device that can be used in the manufacturing method of the present invention.

FIG. 5 shows experimental results of electric discharge treatment in the manufacturing method of the present invention in relation to frequency and surface roughness.

FIG. 6 shows an experimental result of an electric discharge process in a manufacturing method of the present invention in a relationship between frequency and current.

FIG. 7 shows an experimental result of an electric discharge process in the manufacturing method of the present invention in a relationship between frequency and voltage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Electric contact 12 ... Contact base material 14 ... Multilayer metal coating 16 ... Underlayer 18 ... Outermost layer 20 ... Reed switch 22 ... Lead piece 30 ... Electric discharge device 32 ... Electrolyte solution 40 ... AC power supply 42 ... Electrode member

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01H 11/04 H01H 11/04 R 36/00 302 36/00 302A F term (Reference) 5G023 AA02 AA04 BA11 BA34 CA24 CA26 5G046 CA03 CA06 5G050 AA03 AA13 AA20 AA38 AA39 BA06 DA07 EA05 EA09 FA01 5G051 AA07 AA12

Claims (9)

[Claims] 1. A contact substrate, comprising: a multi-layer metal coating provided on the contact substrate, wherein the multi-layer metal coating is provided on an underlayer to be applied to the contact substrate; An electrical contact comprising an outermost layer to be attached, wherein an interface between the underlayer and the outermost layer is a rough surface, and a surface of the outermost layer is roughened corresponding to the interface; Electrical contacts characterized by the following: 2. A reed switch comprising at least a pair of reed pieces each having the electric contact according to claim 1. 3. A semiconductor device comprising: a contact base; and a multi-layer metal coating provided on the contact base, wherein the multi-layer metal coating is provided on an underlying layer applied to the contact base, and on the underlying layer. A method of manufacturing an electrical contact comprising: an outermost layer to be attached; metal plating is applied to the contact base material to form the underlayer; and a surface of the underlayer is roughened by electric discharge treatment; A method for manufacturing an electrical contact, comprising: applying a metal plating to the roughened surface of the formation to form the outermost layer. 4. The method for manufacturing an electrical contact according to claim 3, wherein the electrical discharge is performed between the underlayer adhered to the contact substrate and an electrolyte solution. 5. The method for manufacturing an electrical contact according to claim 3, wherein the electrical discharge is performed in a dry state between the base layer adhered to the contact base material and the electrode member. 6. The electric discharge according to claim 5, wherein the electric discharge is 50 Hz to 400 Hz.
The method for manufacturing an electrical contact according to any one of claims 3 to 5, wherein the method is performed by applying an alternating current. 7. The method according to claim 3, wherein the electric discharge is performed by applying an alternating current of 0.01 A to 1 A.
Item 13. The method for producing an electrical contact according to item 1. 8. The method for manufacturing an electric contact according to claim 3, wherein the electric discharge is performed by applying an AC voltage of 10 V to 1000 V. 9. A reed switch comprising at least a pair of reed pieces each having an electric contact manufactured by the manufacturing method according to claim 3.