JP2001006469A - Manufacturing method of encapsulated contact material - Google Patents

Abstract

(57) Abstract: An encapsulated contact material capable of stabilizing a contact resistance at a low level in a low power load range where discharge does not occur is manufactured. SOLUTION: The method for producing an encapsulated contact material comprises forming a lower coating layer, a metal coating layer, and an oxide coating layer on a contact substrate in this order, wherein the lower coating layer is made of Mo, Zr, Nb, Hf, At least one of Ta and W is used as a matrix, and the matrix contains at least one of Zn, Cd, Hg, Al, Ga, In, Tl, Ge, Sn, Pb, As, Sb, and Bi. The metal coating layer is made of at least one of Fe, Co, Ni, Cu, Ag, Au, Ru, Rh, Pd, Os, Ir, and Pt, and the oxide coating layer is made of Ru, Rh,
It is made of at least one oxide of Pd, Os, Ir, and Pt, and a surface layer of at least one of the lower coating layer, the metal coating layer, and the oxide coating layer is removed by a predetermined thickness after forming the coating layer. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an encapsulated contact material used for an encapsulated contact such as a reed switch.

[0002]

2. Description of the Related Art An encapsulated contact material is a contact material that is used in a sealed state in an enclosure made of glass or the like. Many materials have been used in which a material is coated with Rh, Ru, or the like, which has excellent conductivity and abrasion resistance, and has high hardness and melting point. However, since Rh, Ru, and the like are expensive, an encapsulated contact material coated with Mo, W, or the like has been developed instead.

Further, the present inventors have previously made at least one member selected from the group consisting of Mo, Zr, Nb, Hf, Ta and W on a contact substrate as a matrix, and Zn, Cd, Hg, Al, Ga, In, Tl,
An encapsulated contact material having a coating layer containing at least one selected from the group consisting of Ge, Sn, Pb, As, Sb, and Bi; a coating layer on a contact substrate; and a metal or metal oxide thereon. Covered encapsulated contact material
-24462), the coating layer (lower coating layer) on a contact substrate, and Fe, Co, Ni, Cu, Ag, Au,
Forming a metal coating layer made of at least one selected from the group consisting of Ru, Rh, Pd, Os, Ir, and Pt, and forming thereon at least one metal selected from the group consisting of Ru, Rh, Pd, Os, Ir, and Pt; The present invention proposes an encapsulated contact material (Japanese Patent Application No. 10-12902) in which a coating layer made of an oxide is formed.

[0004]

SUMMARY OF THE INVENTION Among the above,
In particular, the encapsulated contact material has a long contact life and is excellent.However, when a large number of these contact materials were subjected to a switching operation test in a low power load range where discharge did not occur near the contact, the majority of the contact material showed contact resistance. However, some of them exhibited an increase in contact resistance during the switching operation test. The increase in the contact resistance induces a malfunction or a failure of the device, so it must be said that the contact material is a fatal defect. Then, the present inventors investigated in detail the cause of the increase in the contact resistance. As a result, elements such as Zn and Cd contained in the matrix element of the lower coating layer (hereinafter, referred to as contained elements) act as surface-active elements for the matrix element, and concentrate on the surface of the lower coating layer when the lower coating layer is formed. This element is concentrated on the outermost layer both when forming the metal coating layer and when forming the oxide coating layer, and this absorbs the carbon in the air when the encapsulated contact is made. It has been found that the agglomeration occurs during the opening and closing operation in the range, and that the agglomerate prevents the electrical contact of the contact and increases the contact resistance during the opening and closing operation test.

The increase in the contact resistance can be improved by forming a thick metal coating layer, but Au, Ag, Ru, Pt, etc. used for the metal coating layer are expensive, and it is costly to form the thick metal coating layer. The present inventors have examined other improvement measures. As a result, it has been found that the contact layer can be prevented from increasing by removing the surface layer portion of the lower coating layer, in which the contained elements such as Zn and Cd are concentrated, after the formation of the coating layer. Was completed. An object of the present invention is to manufacture a highly reliable encapsulated contact material that can stabilize a contact resistance at a low level in a low power load range where discharge does not occur and does not cause malfunction or failure of the device. .

[0006]

According to the first aspect of the present invention,
A step of forming a lower coating layer with a thickness of 0.1 μm or more on the contact substrate, a step of forming a metal coating layer thereon with a thickness of 1 nm or more, and a step of forming an oxide coating layer thereon with a thickness of 1 nm or more Wherein the lower coating layer is made of Mo, Zr, Nb, Hf, Ta,
At least one of W is a substantial matrix, and Zn, Cd, Hg, Al, G
a, In, Tl, Ge, Sn, Pb, As, Sb, Bi
Is made of a material containing 0.5 to 50 atomic% and an unavoidable impurity element in production, and the metal coating layer is made of Fe, Co, Ni, Cu, Ag, Au, R
u, Rh, Pd, Os, Ir, Pt, and a material containing an unavoidable impurity element in production, and the oxide coating layer is made of Ru, Rh, Pd, Os,
It comprises at least one of Ir and Pt and an oxide of an unavoidable impurity element in production, and in at least one of the three steps, after forming the coating layer, removing the coating layer surface layer by a predetermined thickness. This is a method for manufacturing a sealed contact material characterized by the following.

According to a second aspect of the present invention, the lower coating layer, the metal coating layer, and the oxide coating layer are formed by a sputtering method, and the surface layers of the respective coating layers are removed by a predetermined thickness by reverse sputtering. Item 2. A method for producing an encapsulated contact material according to Item 1.

According to a third aspect of the present invention, there is provided the method of manufacturing an encapsulated contact material according to the first or second aspect, wherein the thickness of the surface layer of the coating layer is 1 to 50% of the thickness of the coating layer. .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a conventional contact base material is used as a contact base material. For example, when the material cost is reduced, Fe, Ni, Co, Ni-Fe,
Co-Fe-Nb, Co-Fe-V, Fe-Ni-Al
-Ti, Fe-Co-Ni, carbon steel, phosphor bronze, nickel silver,
Metal materials such as brass, stainless steel, Cu-Ni-Sn, Cu-Ti are recommended.

In the present invention, the elements (Mo, Zr, Nb, Hf, Ta,
W) has a high melting point and a high hardness, and enhances the wear resistance of the entire contact coating layer (lower coating layer + metal coating layer + oxide coating layer). Elements contained in the matrix (Zn, Cd, Hg, Al, Ga, In, Tl, Ge,
Sn, Pb, As, Sb, and Bi) stabilize the contact resistance of the entire contact coating layer to a low level and improve the wear resistance and oxidation resistance of the encapsulated contact material. In addition, oxygen entering from the surface of the sealed contact is trapped to suppress oxidation of the matrix forming element. It is to be noted that oxygen may be contained in the entire lower coating layer up to about 20 atomic%.

In the present invention, Z constituting the lower coating layer
The reason why the concentration of the contained elements such as n and Cd is defined as 0.5 to 50 atomic% is that when the concentration is less than 0.5 atomic%, the effect cannot be sufficiently obtained, and when it exceeds 50 atomic%, the wear resistance is reduced. To do that. The preferred content of the contained element is 5 to 30.
Atomic%, especially 10 to 20 atomic%. The contained element may be dissolved in a matrix, or may be present as a compound or a simple substance. If a concentration gradient is provided in the contained element from the contact base material side toward the surface layer, the actions of the matrix and the contained element can be efficiently exhibited. In the present invention, the reason why the thickness of the lower coating layer is specified to be 0.1 μm or more is that if it is less than 0.1 μm, sufficient wear resistance cannot be obtained.

In the present invention, the metal coating layer secures the conductivity of the entire contact coating layer, and traps oxygen entering from the surface of the encapsulated contact to prevent oxidation of the lower coating layer to prevent the initial contact of the encapsulated contact. Reduce the variation in contact resistance. If the thickness of the metal coating layer is less than 1 nm (10 ⁻³ μm), the effect cannot be sufficiently obtained.

In the present invention, the oxide coating layer serving as the contact surface can weakly adsorb the carbonaceous substance in the atmosphere, and therefore, the adsorbed carbonaceous substance is removed by heating when sealing the contact portion. In addition, an increase in contact resistance due to the carbon-based material is suppressed. The thickness of the oxide coating layer is 1
If it is less than nm, the effect cannot be sufficiently obtained.

In the present invention, a step of forming a lower coating layer,
In at least one step of forming a metal coating layer or forming an oxide coating layer, after forming each coating layer, removing the contained elements such as Zn and Cd concentrated on the surface layer of the coating layer, Eliminates the adverse effects of the contained elements on contact resistance.

In the present invention, when each coating layer is formed by sputtering, a coating layer having a predetermined composition can be formed with a uniform thickness, and the internal stress of the metal coating layer can be easily adjusted by the gas pressure during sputtering.

In the present invention, any etching treatment can be applied to the removal of the surface layer of the coating layer in which the contained elements such as Zn and Cd are concentrated. However, when each coating layer is formed by a sputtering method, the reverse sputtering is effective. It is a target. Reverse sputtering can be performed only by reversing the polarity of the electrode in the sputtering method.

In the present invention, the thickness of the surface layer of the coating layer to be removed by the etching treatment is 1 to 5 times the original thickness of the coating layer.
0% is preferred. The reason is that if it is less than 1%, the contained elements are not sufficiently removed, and even if it exceeds 50%, the effect is saturated.

[0018]

The present invention will be described below in detail with reference to examples. (Example 1) Contact base material (52% Ni-F
e alloy plate) The surface is ultrasonically cleaned in acetone for 5 minutes,
Then, the substrate was subjected to electrolytic polishing and cleaning using a phosphoric acid bath, and further subjected to ion bombardment treatment with Ar ions for cleaning.
In the ion bombardment process, the contact substrate is set in a vacuum chamber, and the inside of the chamber is evacuated to 2 × 10 ⁻⁴ Pa or less. Inside is 1 ×
Ar gas was introduced until the pressure reached 10 ^-1 Pa, and then a voltage of -400 V was applied to the contact base material to generate a high frequency of 0.2 kW from a high frequency antenna in the chamber.

Next, a lower coating layer is formed on the cleaned contact substrate surface (without heating) at a rate of 1 nm / sec by a binary RF magnetron sputtering in a chamber (Ar gas atmosphere) at a rate of 1 nm / sec. Thereafter, the surface layer of the lower coating layer was removed by a predetermined thickness by reverse sputtering. Next, R on the lower coating layer in the same chamber (Ar gas atmosphere)
A metal coating layer is formed at a rate of 1 nm / sec by F magnetron sputtering, and an oxide coating layer is formed on the metal coating layer at a rate of 1 nm / sec by RF magnetron sputtering in the same chamber (oxygen gas atmosphere). Thus, an encapsulated contact material was manufactured. The Ar gas atmosphere was set to a gas pressure of 30 mTorr. The composition and thickness of the lower coating layer, the metal coating layer and the oxide coating layer, and the removal thickness (ratio) of the lower coating layer surface layer were variously changed within the specified values of the present invention.

Comparative Example 1 An encapsulated contact material was manufactured in the same manner as in Example 1, except that no etching treatment was performed after the formation of the lower cover layer.

Comparative Example 2 An encapsulated contact material was manufactured in the same manner as in Example 1 except that the metal coating layer and the oxide coating layer were not formed.

Using each of the encapsulated contact materials produced in Example 1 and Comparative Examples 1 and 2, a reed switch (enclosed contact) in which nitrogen gas was encapsulated was prepared and subjected to a life test. The life test was performed at room temperature under a load of DC 5 V, 100 μA, and a driving magnetic field of 100 AT (Ampere Turn).
Hz opening and closing operation was performed. The evaluation of each reed switch was evaluated by obtaining the maximum value of the contact resistance and the number of switching operations up to the point of occurrence of the failure. The number of tests was 10 each.
The fault occurrence point is a point in time when a switching failure occurs, or a point in time when the resistance value between both poles of the reed switch becomes 10Ω or more. Regarding the maximum value of the contact resistance, the contact resistance was measured every 5 × 10 ⁷ times of the opening / closing operation for each of ten reed switches, and the maximum value was displayed. Table 1 shows the results.
3 is shown.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

As is clear from Tables 1 to 3, all of the reed switches (Nos. 1 to 42) using the encapsulated contact material of the present invention had a long minimum life and a low maximum contact resistance.
In particular, No. 1 in which the removal rate of the lower coating layer surface layer is 1 to 50%.
In the case of ~ 41, the maximum value of the contact resistance was low. Even if the metal coating layer has a small thickness (Nos. 7 to 10), a sufficient effect is obtained. According to the present invention, it is possible to produce a high-quality encapsulated contact material having a low and stable contact resistance at a low cost. it is obvious. In contrast, Nos. 43 to 60 of the comparative examples did not remove the lower coating layer, and Nos. 61 and 62 did not have the metal coating layer and the oxide coating layer. Increased.

In the above embodiment, the method of removing the surface layer of the lower coating layer by reverse sputtering has been described.
According to the present invention, the same effect can be obtained even if the surface layer of the metal coating layer or the oxide coating layer is removed or removed by a method other than reverse sputtering.

[0028]

As described above, according to the present invention, a step of forming a lower coating layer to a thickness of 0.1 μm or more on a contact substrate and a step of forming a metal coating layer to a thickness of 1 nm or more thereon. A method of manufacturing an encapsulated contact material, comprising sequentially forming an oxide coating layer having a thickness of 1 nm or more thereon, wherein the lower coating layer comprises at least one of Mo, Zr, Nb, Hf, Ta, and W. The seed is a substantial matrix, and the matrix contains Zn, Cd, Hg, Al, Ga, In,
At least one of Tl, Ge, Sn, Pb, As, Sb, and Bi is made of a material containing 0.5 to 50 atomic% and an impurity element inevitable in manufacturing, and the metal coating layer is made of Fe, Co. , Ni, Cu, Ag, Au, Ru, Rh,
The oxide coating layer is made of a material containing at least one of Pd, Os, Ir, and Pt and an unavoidable impurity element in manufacturing, and the oxide coating layer is made of Ru, Rh, Pd, Os, Ir, Pt.
And at least one of the three steps removes a predetermined thickness of the surface layer of the coating layer after forming the coating layer in at least one of the three steps. The effects of elements such as Zn and Cd that increase the contact resistance by concentrating on the surface layer are eliminated, and the contact resistance is stabilized at a low level in a low power load range where discharge does not occur, and thus does not cause malfunction or failure of the device. A highly reliable encapsulated contact material can be obtained. The encapsulated contact material of the present invention can be manufactured efficiently by forming each coating layer by a sputtering method and removing the surface layer of the coating layer in which the contained elements are concentrated by reverse sputtering. Therefore, an industrially remarkable effect is achieved.

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Claims (3)

[Claims] 1. A method according to claim 1, wherein the lower coating layer has a thickness of 0.1 on the contact substrate.
forming a metal coating layer having a thickness of 1 μm or more.
A method for manufacturing an encapsulated contact material, comprising sequentially forming an oxide coating layer with a thickness of 1 nm or more thereon, wherein the lower coating layer is made of Mo, Zr, Nb,
At least one of Hf, Ta, and W is used as a substantial matrix, and Zn, Cd, Hg,
Al, Ga, In, Tl, Ge, Sn, Pb, As, S
b, at least one of Bi is 0.5 to 50 atomic%
And a material containing an unavoidable impurity element in manufacturing, and the metal coating layer is made of Fe, Co, Ni, Cu, Ag,
Au, Ru, Rh, Pd, Os, Ir, Pt, and a material containing at least one of unavoidable impurity elements in production, and the oxide coating layer is made of Ru, Rh, Pt.
at least one of d, Os, Ir, and Pt and an oxide of an unavoidable impurity element in the production;
A method for producing an encapsulated contact material, comprising removing a predetermined thickness of a surface layer of a coating layer after forming the coating layer in at least one of the steps. 2. The encapsulated contact according to claim 1, wherein the lower coating layer, the metal coating layer, and the oxide coating layer are formed by a sputtering method, and the surface layer of each of the coating layers is removed by a predetermined thickness by reverse sputtering. Material manufacturing method. 3. The method for producing an encapsulated contact material according to claim 1, wherein the removal thickness of the surface layer of the coating layer is 1 to 50% of the thickness of the coating layer.