JPH04289618A - Lead switch contact material and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide lead switch contact material with good adhesion between a contact material and a contact thin film and provide its manufacture. CONSTITUTION:A Ti or Zr intermediate layer is formed on Ni-Fe alloy base material, a contact thin film of periodic table IVa metal nitride, carbide, boride, silicide or alumide is formed thereon, and a Ti or Zr diffusion layer is formed on an interface between the Ni-Fe alloy base material and the intermediate layer, at the least. The diffusion layer is formed by heating the base material at 400 deg.C or higher. The formation of the diffusion layer allows the apparent interface to disappear between the contact base material and the intermediate layer and the entire organization to be continued, so that adhesion between the base material and the intermediate layer as well as between the intermediate layer and the contact thin film thereon is improved to restrain a contact from exhaustion.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a reed switch material and a method for manufacturing the same, and more specifically, the present invention relates to a reed switch material and a method for manufacturing the same, and more specifically, the adhesiveness between the contact base material and the contact thin film is excellent, and the contact thin film is difficult to peel off, thereby suppressing contact wear. The present invention relates to a reed switch contact material and a method of manufacturing the same.

0002

2. Description of the Related Art In the case of sealed contacts for reed switches, noble metals such as Au, Ag, Pd, Rh, Ru, and alloys thereof are mainly used as contact materials. This is based on the fact that the above-mentioned noble metals and alloys thereof have low resistivity and easy workability, and are generally materials that are difficult to corrode or oxidize.

[0003] However, these precious metals and their alloys are all expensive, and moreover, there is a problem in that the prices are not stable. For this reason, Cu, C as a contact base material.
Using inexpensive materials such as u alloy, Fe, Fe alloy, and Ni alloy, the surface of this base material has excellent corrosion and oxidation resistance.
In addition, a contact having a structure in which the contact thin film is coated with a conductive ceramic such as TiN or ZrN has been proposed (Japanese Patent Laid-Open Nos. 56-152115, 1983-1).
59017, JP-A-56-159028, etc.).

[0004] Ceramics constituting such a contact thin film are mainly ceramics from the periodic table IV, such as Ti and Zr.
Nitride, carbide, boride, silicide, aluminide, etc. of group a metals are known. However, with materials in which the contact thin film is formed by directly coating the surface of the contact base material with ceramics as described above, the adhesion between the contact thin film made of ceramic and the contact base material is not necessarily sufficient, and as a result, the contact thin film peels off. However, there is a problem in that the contacts are easily worn out, resulting in severe contact wear.

[0005] In order to solve such problems, an intermediate layer of a predetermined thickness is interposed between the contact base material and the contact thin film. For example, first, Zr or Ti is deposited on the surface of a NiFe alloy base material to form an intermediate layer, and then Zr or Ti is deposited on top of this intermediate layer.
Materials using rN as a contact thin film and TiN as a contact thin film for Ti have been proposed (see Japanese Patent Laid-Open No. 164115/1983).

[0006] In the case of this material, the adhesion between the contact thin film and the contact base material is slightly improved, but it cannot necessarily be said that the adhesion is satisfactory and good. The present invention solves the above-mentioned problems in a reed switch contact material composed of a contact base material, an intermediate layer, and a contact thin film made of ceramics, and has extremely good adhesion between the contact base material and the contact thin film, so that contact wear The purpose of the present invention is to provide a reed switch contact material and a method for manufacturing the same, which greatly suppresses this.

[0007]

[Means and effects for solving the problem] In order to achieve the above-mentioned object, the present invention includes a base material made of a NiFe alloy, and a base material formed on the surface of the base material containing Ti or Zr as a main component. In a reed switch contact material having an intermediate layer and a contact thin film formed on the surface of the intermediate layer and made of a ceramic of group IVa metal of the periodic table, at least the interface between the base material and the intermediate layer contains Ti or Zr. A reed switch contact material is provided, characterized in that a diffusion layer of 4 is formed, and the base material made of a NiFe alloy is
Ti is applied to the surface of the base material while heating to a temperature of 00°C or higher.
Alternatively, a method for producing a reed switch contact material, characterized in that an intermediate layer is formed by vapor-depositing Zr, and then a ceramic of a group IVa metal of the periodic table is formed as a contact thin film on the surface of the intermediate layer, and An intermediate layer is formed by vapor depositing Ti or Zr on the surface of a base material made of a NiFe alloy, and then the whole is heated to a temperature of 400° C. or higher, and a ceramic of a group IVa metal of the periodic table is coated on the surface of the intermediate layer. A method for manufacturing a reed switch contact material is provided, which comprises forming a contact thin film by vapor deposition.

The main feature of the contact material of the present invention is that a diffusion layer is formed at the interface between the NiFe alloy base material and the intermediate layer. This diffusion layer is composed of T, which is a constituent element of the intermediate layer.
i or Zr and Ni, Fe, which are the constituent elements of the contact base material
is a layer made of an alloy or an intermetallic compound formed by mutual thermal diffusion by the method described below, and the chemical composition at the bonding interface between the contact base material and the intermediate layer is continuously changed, thereby forming a contact point. It works to eliminate the sharp boundary between the base material and the intermediate layer and improve the adhesion between the two.

In the contact material of the present invention, the thickness of the intermediate layer is approximately 0.01 to 5 μm. If it is made too thick, the resistance and internal stress of the intermediate layer itself will become large, causing the problem that special consideration must be paid to the outermost contact layer coating.If it is made too thin, this intermediate layer will be coated when forming the diffusion layer (described later). This is because there is too little Ti and Zr located in the area to have any effect.

[0010] This intermediate layer is formed by depositing Ti or Zr on the surface of the contact base material. As the deposition method, conventional vacuum deposition, sputtering, ion plating, etc. are applied. The contact thin film formed by vapor deposition on the intermediate layer is made of a ceramic of at least one of nitrides, carbides, borides, silicides, and alumides of metals from Group IVa of the periodic table, such as Ti, Zr, and Hf. configured.

Among these, Zr ceramics are used when the intermediate layer is made of Zr, and Ti is used when the intermediate layer is made of Ti.
It is preferable to form the contact thin film using ceramics, since this improves the adhesion between the contact thin film and the intermediate layer. Also,
It is preferable to form a diffusion layer by diffusing nitrogen, carbon, boron, silicon, or aluminum at the interface between the contact thin film and the intermediate layer, depending on the type of contact thin film to be formed, as this will further improve adhesion. It is.

[0012] The thickness of this contact thin film is usually 0.05~
The thickness is preferably about 100 μm. As a method for depositing this contact thin film, conventional methods such as vacuum deposition, sputtering, ion plating, CVD, and synthesis by heat treatment of a multilayer film are applied.

Now, the diffusion layer in the contact material of the present invention is formed as follows. The first method is to first set a NiFe alloy base material in a commonly used film forming apparatus, heat it to a temperature of 400°C or higher, and then coat the surface with Ti.
Alternatively, there is a method of vapor depositing Zr. When Ti or Zr is deposited on the surface of the heated contact base material, in the initial stage of the deposition, Ti or Zr reacts with the NiFe alloy of the base material and diffuses from the base material surface to the inside, and Ti, Zr ，
This becomes a diffusion layer in which Ni and Fe are mixed. After the diffusion is saturated, Ti or Zr is deposited as a single metal layer on this diffusion layer to form an intermediate layer.

The state of diffusion and therefore the thickness of the diffusion layer is
It is defined by the temperature of the contact base material, and this temperature is 400℃
If it is less than that, the above-mentioned diffusion will not occur. However, if the temperature is too high, there will be problems such as deterioration of the contact base material or excessive diffusion, which will expose Ni and Fe to the contact surface layer, so the temperature of the contact base material should be set at 400
It is preferable to control the temperature to 700°C. At this time, the thickness of the diffusion layer is 0.1 to 1 μm, and good adhesion between the intermediate layer and the contact base material can be ensured.

[0015] The second method is to first form a deposited layer of Zr or Ti to a predetermined thickness on the surface of the contact base material in the same film forming apparatus, and then to heat the whole to a temperature of 400°C or higher. This method promotes the diffusion of Ti or Zr into the contact base material. When the contact material manufactured in this way is sealed in glass and used as a reed switch, in order to stabilize the contact resistance, the surface of the contact thin film is further coated with Pt, Au, Rh, Ru, etc. Noble metals such as or alloys thereof may be thinly deposited.

[0016]

[Example] Example 1 A reed switch contact base material made of 52% Ni-Fe alloy was set in a vacuum chamber, and the inside of the chamber was approximately 1.0×
The substrate was evacuated to 10 −6 Torr and heated to 650° C., and the surface of the substrate was cleaned by ion bombardment with Ar ions.

[0017] Next, an amount of Zr equivalent to 0.5 μm was deposited on the surface of the base material by ion plating, and the temperature of the base material was lowered to 6.
While maintaining the temperature at 50° C., ZrN with a thickness of 2 μm was further deposited thereon by ion plating. Example 2 The contact base material used in Example 1 was set in a vacuum chamber,
After evacuating the inside of the chamber to approximately 1.0 x 10-6 Torr, the surface was cleaned by ion bombardment with Ar ions, and then an amount of Zr equivalent to 0.5 μm was deposited on the base material surface by ion plating at room temperature. was deposited.

[0018] Thereafter, the base material was heated to 650°C, and in that state, a Z film with a thickness of 2 μm was formed by ion plating.
An rN layer was formed. Example 3 The contact base material of the reed switch used in Example 1 was set in a vacuum chamber, and the inside of the chamber was heated to approximately 1.0 x 10-6 To
The substrate was evacuated to rr and heated to 550° C., and ion bombardment was performed using Ar ions to clean the surface of the substrate.

Next, an amount of Ti equivalent to 0.5 μm was deposited on the surface of the base material using an ion plating method, and the temperature of the base material was lowered to 5 μm.
While maintaining the temperature at 50° C., TiN with a thickness of 2 μm was further deposited thereon by ion plating. Finally, a Rh layer with a thickness of 0.1 μm was formed on this TiN by vacuum evaporation. Example 4 The contact base material used in Example 1 was set in a vacuum chamber,
After evacuating the inside of the chamber to approximately 1.0 x 10-6 Torr, the surface was cleaned by ion bombardment with Ar ions, and then an amount of Ti equivalent to 0.5 μm was deposited on the substrate surface by ion plating at room temperature. was deposited.

[0020] Thereafter, the base material was heated to 550°C, and in that state, a T film with a thickness of 2 μm was formed by ion plating.
An iN layer was formed, and a Rh layer having a thickness of 0.1 μm was further formed thereon by vacuum evaporation. Comparative Example 1 A contact material was prepared in the same manner as in Example 1, except that a 2.5 μm thick ZrN layer was directly formed on the surface of the contact base material by ion plating without forming a Zr layer. Manufactured. Comparative Example 2 A contact material was formed in the same manner as in Example 3, except that a 2.5 μm thick TiN layer was directly formed on the surface of the contact base material by ion plating without forming a Ti layer. Manufactured. Comparative Example 3 A contact material was produced in the same manner as in Example 2, except that the heating temperature of the contact base material was 350°C.

The contact materials of Examples 1 to 4 and Comparative Examples 1 and 3 were subjected to a 180° bending test, and the surfaces thereof were observed with a scanning electron microscope to examine the adhesion of the deposited films. Table 1 shows the cases in which the deposited film did not peel off from the base material as ○, and the cases in which it peeled off as ×. In addition, a reed switch was manufactured by enclosing each of the above contact materials in glass, and the contact resistance was measured after aging treatment by repeating the contact opening and closing 300,000 times. Furthermore, a heat cycle of heating and cooling at room temperature←→500°C was repeated 100 times, and the presence or absence of external cracks in the contact thin film was observed using a scanning electron microscope. Furthermore, the number of operations at which the cumulative failure rate reached 50% was measured by repeating the opening and closing of the contacts. The above results are collectively shown in Table 1.

[0022]

[Table 1]

Element concentration analysis in the depth direction from the surface of the contact thin film was also performed on the contact material of Example 1 and the contact material of Comparative Example 3 by Auger electron spectroscopy. The results are shown in Figures 1 and 2 for Example 1 and Example 3.
Comparative Example 3 is shown in FIG. As is clear from these figures, in the contact material of the present invention, the Zr layer (intermediate layer)
, a diffusion layer is formed between the Ti layer (intermediate layer) and the contact base material (NiFe alloy). However, the existence of this diffusion layer is not observed in the contact material of the comparative example. This is because the substrate temperature was 350°C, lower than 400°C.

[0024]

[Effects of the Invention] As is clear from the above explanation, in the contact material of the present invention, the interface between the contact base material and the intermediate layer is not a sharp boundary surface, but a diffusion layer in which the component elements of each layer are mixed. Therefore, their adhesion to each other is extremely good. Therefore, since contact wear due to peeling of the contact thin film is suppressed, it is a reed switch contact material with high industrial value.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the results of Auger electron spectroscopy of the contact material of Example 1.

FIG. 2 is a graph showing the results of Auger electron spectroscopy of the contact material of Example 3.

FIG. 3 is a graph showing the results of Auger electron spectroscopy of the contact material of Comparative Example 3.

Claims (3)

[Claims] 1. A base material made of a NiFe alloy, an intermediate layer mainly composed of Ti or Zr formed on the surface of the base material, and a base material formed on the surface of the intermediate layer made of a metal of group IVa of the periodic table. 1. A reed switch contact material having a contact thin film made of ceramic, characterized in that a Ti or Zr diffusion layer is formed at least at the interface between the base material and the intermediate layer. [Claim 2] A base material made of NiFe alloy is heated at 400°C.
Forming an intermediate layer by vapor depositing Ti or Zr on the surface of the base material while heating to a temperature above, and then forming a ceramic of a group IVa metal of the periodic table as a contact thin film on the surface of the intermediate layer. A method for manufacturing a reed switch contact material characterized by: [Claim 3] T on the surface of the base material made of NiFe alloy.
Forming an intermediate layer by vapor depositing i or Zr, then heating the whole to a temperature of 400° C. or higher, and vapor depositing ceramics of a group IVa metal of the periodic table on the surface of the intermediate layer to form a contact thin film. A method for manufacturing a reed switch contact material characterized by: