JPH04322017A - Contact material - Google Patents

Abstract

PURPOSE:To offer a contact material having slight dispersion of its initial contact resistance and a long working life. CONSTITUTION:A contact material characterized in that a contact coating layer having its thickness in a range from 0.03 to 100mum and consisting of a conductive metal oxide mainly composed of at least one kind to be elected from a group of SnO2, In2O3 PbO, PbO2, CdO, Cd2SnO4, In-Sn oxide, V2O3, FeO, Fe3O4, RuO2, Rh2O3, RhO2, ReO2, IrO2, TiO, Ti2O3 is formed on the surface of the contact material. An intermediate layer having its thickness not less than 0.01mum and consisting of a soft metal is desirably formed between the contact base material and the contact coating layer. Further, a metal layer having the thickness not less than 0.01mum is desirably formed on the contact coating layer.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to contact materials, and more specifically, the present invention relates to contact materials that have high hardness, high melting point, and excellent wear resistance and environmental resistance. This article relates to contact materials useful for control relays, microswitches, keyboard switches, sliding contacts, etc.

0002

[Prior Art] Conventionally, the materials for electrical contacts with small shapes have been Au, Au alloy, Ag, and Al, which have excellent electrical conductivity because the contact force during operation is small.
g-alloy etc. have been used. However, the above material is a soft material with a hardness of about Hv100 to 200,
In addition, since the melting point is low at 900 to 1060°C, when the number of opening and closing operations increases, wear will progress to the underlying metal.
In many cases, the consumable powder scattered on the contact surface increases the contact resistance, making it impossible to ensure the initial stability of the contact resistance.

In addition, in the case of this contact material, the material softens due to the temperature rise during contact operation, resulting in sticking of the contact surface and delay in operation (recovery failure) due to locking, which significantly shortens the operating life of the contact. There is a problem with doing so. Furthermore, a problem arises in that the temperature rise during contact operation promotes oxidation of the material, causing an increase in contact resistance.

On the other hand, when the above-mentioned materials are used in reed switches, etc., the contact pressure is small and it is difficult to increase the thickness of the contact layer, so a high melting point material such as W or Mo is used for the contact layer. and an increase in contact resistance cannot be prevented. For this reason, noble metal plated contacts plated with a noble metal such as Rh or Ru are widely used as contact materials for the above-mentioned reed switches.

However, in the case of Rh-plated contacts, for example, during the storage period before actual use, the surface may be contaminated by organic gases contained in the atmosphere or organic gases that have been adsorbed on the surface of the underlying metal. Contact resistance often increases. In addition, when manufacturing these contacts, it is not possible to directly apply Rh plating to the underlying bullets or lead pieces made of Fe, Ni, etc., so once the Au
After forming a plating layer of , Ag, Cu, etc., R
It is necessary to apply H plating. Therefore, the effective thickness of the Rh plating layer becomes thinner, and the manufacturing process becomes complicated, leading to an increase in processing cost for the contact.

[0006]

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems with conventional contact materials, and has high hardness, high melting point, oxidation resistance, and is not subject to surface contamination by organic gases. The purpose is to provide a contact material that can be manufactured at low cost.

[0007]

[Means for Solving the Problems] In order to achieve the above-mentioned object, in the present invention, SnO
2, In2O3, PbO, PbO2, CdO,
Cd2 SnO4, In-Sn oxide, V2 O3
, FeO, Fe3 O4 , RuO2 , Rh2 O3
, RhO2 , ReO2 , IrO2 , TiO, T
A conductive metal oxide whose main component is at least one selected from the group of i2 O3 and has a thickness of 0.03 to 100.
A contact material (referred to as a first contact material) is provided, characterized in that a contact coating layer of μm thick is formed thereon, and a thickness of 0 μm made of a soft metal is provided between the contact base material and the contact coating layer. A contact material (referred to as a second contact material) characterized in that an intermediate layer of .01 μm or more is interposed is provided,
Furthermore, a contact material (referred to as a third contact material) characterized in that a metal layer having a thickness of 0.01 μm or more is formed as a surface layer on the entire surface of the first contact material or the second contact material described above. ) is provided.

First, in the contact material of the present invention, a relatively inexpensive material such as Cu, Cu alloy, Fe alloy, or Ni alloy is used for the contact base material. In the first contact material, a contact coating layer is formed directly on the surface of this contact base material. Here, the contact coating layer is SnO2, In2O3, PbO, PbO2
, CdO, Cd2 SnO4 , In-Sn oxide (I
TO), V2 O3, FeO, Fe3 O4, Ru
O2, Rh2 O3, RhO2, ReO2, I
The main component is one or more conductive metal oxides of rO2, TiO, and Ti2O3.

These contact coating layers are chemically stable and
It has excellent environmental resistance such as oxidation resistance and abrasion resistance, and has high hardness and melting point, so it does not cause transfer wear and tear and has little wear, so it works to extend the operating life of the contact and increase the reliability of the contact. The thickness is set to 0.03 to 100 μm. If the thickness of this contact coating layer is less than 0.03 μm, the good conductivity required for a contact material cannot be obtained, leading to an increase in contact resistance, and at the same time, the wear resistance is insufficient, so it cannot be used as a contact. A satisfactory operating life cannot be obtained. On the other hand, if the thickness exceeds 100 μm, the crystals of the conductive metal oxide will become coarse during the formation of this layer, which will be described later, and roughness will occur on the surface of the formed layer, resulting in a decrease in contact resistance. This causes an increase in temperature during operation, and at the same time, stable thermal conductivity cannot be obtained.

[0010] This contact coating layer is formed as follows. That is, first, the surface of the contact base material is polished to a smooth surface, then precision polished by electrolytic polishing, etc., and then,
After cleaning the polished surface by using ion bombardment, electronic shower, etc., plasma C
A layer of the conductive metal oxide having a desired composition and a desired thickness is formed by applying a commonly used film forming technique such as a VD method, a sputtering method, an ion-assisted vapor deposition method, or an ion plating method.

[0011] Note that this contact coating layer may be formed as a single layer on the surface of the contact base material, but if the above-mentioned conductive metal oxides of the same or different types are laminated to form a plurality of layers, the contact coating layer may be formed as a single layer on the surface of the contact base material. It is effective because the number of intralayer pinholes that occur can be reduced, and the characteristics of each layer complement each other in the entire coating layer. The second contact material is the first contact material described above, with an intermediate layer made of a soft metal interposed between the contact base material and the contact coating layer.

[0012] The soft metals used are Ag, Al, Au, and C.
o, Cu, Fe, Mg, Ni, Pd, Pt, Sr, Ti
, Zr, Hf, V, Nb, Ta, and Cr, or two or more thereof. This intermediate layer increases the adhesion between the contact base material and the contact coating layer, contributes to stress relief in the contact coating layer, and also alleviates the stress generated due to the difference in thermal expansion between the contact base material and the contact coating layer. This prevents separation between the two, and since the constituent material is a soft material, it reduces the actual hardness of the contact material and also reduces the contact resistance, alleviating the kinetic energy applied to the contact when the circuit is closed. This contributes to reducing chattering. As this chattering decreases, the number of occurrences of chattering arcs also decreases, so the operating life of the contact portion becomes longer. Furthermore, the occurrence of closing errors is significantly reduced, and the reliability of the contact is improved.

[0013] Furthermore, by forming this intermediate layer, the contact coating layer formed on this surface becomes smooth;
Contact resistance is low and stable, making it possible to improve contact characteristics. The thickness of this intermediate layer is set to 0.01 μm or more. If the thickness is less than 0.01 μm, pinholes occur frequently during film formation, corrosion progresses from the pinholes, and the contact resistance of the contact coating layer formed thereon increases. Further, the upper limit of the thickness of the intermediate layer may be determined as appropriate based on the manufacturing cost and the relationship between the intended size of the contacts and the distance between the contacts.

[0014] As in the case of the contact coating layer, this intermediate layer may be formed by plasma CVD, sputtering, ion-assisted vapor deposition, ion plating, etc., or may be formed by electrolytic plating. Good too. In addition, after the intermediate layer is formed by the method described above, if it is further heat-treated at a predetermined temperature and subjected to a diffusion treatment between it and the contact base material,
This is effective because the adhesion to the contact base material is further improved.

The third contact material of the present invention has a surface layer made of a metal, which will be described later, formed on the contact coating layer of the first contact material or the second contact material. This metal surface layer lowers the substantial hardness of the contact portion and contributes to stabilizing contact resistance. This allows the kinetic energy to be applied to the contact to be dissipated to some extent in this metal surface layer, reducing chattering caused by elastic flipping of the contact and improving the operating life of the contact. Moreover, introduction malfunctions due to chattering are significantly reduced, and the reliability of the contacts is increased. Furthermore, the contact area at the contact portion increases, and the contact resistance becomes lower and more stable.

Metals constituting such a metal surface layer include Ru, Rh, Pd, Re, Os, Ir, Pt, A
u, Ag, Al, Cu, Ni, Sn, Ti, Zr, V,
One or more of Hf, Nb, Ta, Cr, and Mo are used. The thickness of this metal surface layer is set to 0.01 μm or more. If this thickness is less than 0.01 μm,
This is because a large number of pinholes occur and the above-mentioned effects are hardly obtained.

Further, the upper limit of the thickness of the metal surface layer may be determined as appropriate from the manufacturing cost and the relationship between the intended size of the contacts and the distance between the contacts. This metal surface layer may be formed by a plasma CVD method, a sputtering method, an ion-assisted vapor deposition method, an ion plating method, etc., as in the case of the contact coating layer and the intermediate layer described above, or by an electrolytic plating method. may be formed.

[0018]

[Example] Example 1 A 52% Ni-Fe alloy contact base material was cleaned with an organic detergent,
After the surface was further cleaned by electrolytic polishing, it was set in a vacuum chamber, and one side thereof was cleaned by Ar ion bombardment. Then, a 1.0 μm thick PbO layer was formed on the surface of the contact base material by ion-assisted vapor deposition.

Example 2 A contact material was produced in the same manner as in Example 1, except that the thickness of the PbO layer was 10 μm. Example 3 A contact material was manufactured in the same manner as in Example 1, except that the thickness of the PbO layer was 80 μm.

Comparative Example 1 A contact material was produced in the same manner as in Example 1 except that the thickness of the PbO layer was 0.002 μm. Comparative Example 2 A contact material was manufactured in the same manner as in Example 1, except that the thickness of the PbO layer was 130 μm.

Example 4 A contact material was produced in the same manner as in Example 1, except that the ion bombardment treatment with Ar was not performed. Example 5 52% by Ar ion bombardment as in Example 1
After cleaning the surface of the Ni-Fe alloy base material, C
A V2 O3 layer with a thickness of 5 μm was formed by the VD method.

Example 6 52% by Ar ion bombardment as in Example 1
After cleaning the surface of the Ni--Fe alloy base material, a 3.0 μm thick ReO2 layer was formed thereon by sputtering. Example 7 52% by Ar ion bombardment as in Example 1
After cleaning the surface of the Ni-Fe alloy base material, a 1.0 μm thick SnO2 layer was formed thereon by reactive vapor deposition.

Example 8 52% by Ar ion bombardment as in Example 1.
After cleaning the surface of the Ni--Fe alloy base material, a 0.5 μm thick IrO2 layer and a 0.5 μm thick SnO2 layer were sequentially formed thereon by sputtering. Example 9 52% by Ar ion bombardment as in Example 1
After cleaning the surface of the Ni--Fe alloy base material, a 2.0 .mu.m thick RhO2 layer and a 3.0 .mu.m thick ITO layer were successively formed thereon by sputtering.

Conventional Example 1 A 300 μm thick Ag-30% Pd alloy plating layer was formed by chemical plating on one side of a 52% Ni-Fe alloy substrate whose surface had been cleaned by sequential organic cleaning and electrolytic polishing. was formed. Conventional Example 2 A 1.0 μm thick Au layer was formed on one side of a base material by chemical plating, and a 2.0 μm thick Rh layer was further formed thereon by the same chemical plating method.

[0025] Electrical contacts are cut out from the above 13 types of contact materials to make a reed switch S, and this reed switch S
As shown in Figure 1, cable C and resistor R (500
Ω), connect it to power supply E (50V) via ammeter A to form a circuit, run a current of 100mA through this circuit to open and close the switch, and reduce the contact resistance and switch temperature rise when closed. It was measured. In addition, the number of operations at which the cumulative failure rate due to welding or adhesion of the contacts was 50% or more was investigated.

Further, a heat cycle test was conducted in which each contact was subjected to a heat cycle of heating and cooling at room temperature←→400°C 100 times, and at that time, any cracks in the appearance of the contact surface layer were observed. No change in appearance: ◎; Cracks occurred: ○; Some cracks occurred: △. Furthermore, each contact point is 450
The oxidation resistance was examined by leaving it in the atmosphere at ℃ for 50 hours. Almost no surface oxidation was observed: ○; Some surface oxidation was observed: △.

In addition, each contact was left in a desiccator filled with saturated benzene vapor for 24 hours, and the degree of generation of organic polymer was observed from the surface condition. Those where no generation was observed were marked with a circle. △ Some occurrences were observed.
It was marked as a mark. The above results are collectively shown in Table 1. In addition,
For reference, the overall cost is also listed, taking into account the material cost, the time required for layer formation, and the cost required for processing.

[0028]

[Table 1]

Example 10 A 52% Ni-Fe alloy contact base material was cleaned with an organic detergent, and
After the surface was further cleaned by electrolytic polishing, it was set in a vacuum chamber, and one side thereof was cleaned by Ar ion bombardment. Next, an Ag layer with a thickness of 1.0 μm was formed on the surface of the contact base material using an ion-assisted vapor deposition method.
．． PbO layers with a thickness of 0 μm were sequentially formed.

Example 11 Example 1 except that the thickness of the Ag layer was 10 μm.
A contact material was manufactured in the same manner as in Example 0. Example 12 Example 1 except that the thickness of the Ag layer was 50 μm.
A contact material was manufactured in the same manner as in Example 0.

Example 13 A contact material was produced in the same manner as in Example 10, except that the thickness of the PbO layer was 10.0 μm. Example 14 A contact material was manufactured in the same manner as in Example 10, except that the thickness of the PbO layer was 80 μm.

Comparative Example 3 A contact material was produced in the same manner as in Example 10, except that the thickness of the Ag layer was 0.005 μm. Comparative Example 4 A contact material was produced in the same manner as in Example 10, except that the thickness of the PbO layer was 0.02 μm.

Comparative Example 5 A contact material was produced in the same manner as in Example 10, except that the thickness of the PbO layer was 130 μm. Example 15 A contact material was manufactured in the same manner as in Example 10, except that an Au layer with a thickness of 1.0 μm was formed by vacuum evaporation instead of the Ag layer.

Example 16 52% Ni-F whose surface was cleaned in the same manner as in Example 10
A with a thickness of 1.0 μm was deposited on the surface of the e-alloy by sputtering.
G layer and Cu layer with a thickness of 1.0 μm are sequentially formed as an intermediate layer, and then a layer with a thickness of 1.0 μm is formed using a reactive sputtering method.
A V2 O3 layer was formed on the Cu layer.

Example 17 52% Ni-F whose surface was cleaned in the same manner as in Example 10
N with a thickness of 1.0 μm was applied to the surface of the e-alloy by sputtering.
An I layer is formed, and then an I layer with a thickness of 1.0 μm is formed using the CVD method.
The rO2 layer and the 1.0 μm thick SnO2 layer are
Films were deposited sequentially on top of the layers. Example 18 52% Ni-F surface cleaned in the same manner as Example 10
On the surface of the e-alloy, a 0.5 μm thick Cu layer and a 1.0 μm thick Ni layer were sequentially formed as intermediate layers by vacuum evaporation,
Next, a 0.5 μm thick S
An nO2 layer was deposited on top of the Ni layer.

[0036] Regarding the above 12 types of contact materials, Example 1
The contact characteristics were investigated in the same manner as in cases 9 to 9. The above results are collectively shown in Table 2.

[0037]

[Table 2]

Example 19 A 52% Ni-Fe alloy contact base material was cleaned with an organic detergent,
After the surface was further cleaned by electrolytic polishing, it was set in a vacuum chamber, and one side thereof was cleaned by Ar ion bombardment. Next, a PbO layer with a thickness of 1.0 μm was formed on the surface of the base material by vacuum evaporation, and an Au layer with a thickness of 0.1 μm was further formed by sputtering.

Example 20 A contact material was produced in the same manner as in Example 19, except that the thickness of the PbO layer was 10.0 μm. Example 21 A contact material was produced in the same manner as in Example 19, except that the thickness of the PbO layer was 80 μm.

Comparative Example 6 A contact material was produced in the same manner as in Example 19, except that the thickness of the PbO layer was 0.002 μm. Comparative Example 7 A contact material was produced in the same manner as in Example 19, except that the thickness of the PbO layer was 130 μm.

Comparative Example 8 A contact material was produced in the same manner as in Example 19, except that the thickness of the Au layer was 0.0005 μm. Example 22 A 52% Ni-Fe alloy contact base material was cleaned with an organic detergent,
After cleaning the surface by electrolytic polishing, it was placed in a vacuum chamber, and one side was cleaned by Ar ion bombardment. Next, a PbO layer with a thickness of 1.0 μm was formed on the surface of the base material by reactive vacuum evaporation, and a Pt layer with a thickness of 0.1 μm was further formed by sputtering.

Example 23 A contact material was produced in the same manner as in Example 22, except that a 0.1 μm thick Pd layer was formed instead of the Pt layer. Example 24 ReO2 layer with a thickness of 5.0 μm, Pt instead of PbO layer
A contact material was manufactured in the same manner as in Example 22, except that an Au layer with a thickness of 0.1 μm was formed instead of the layer.

Example 25 A contact material was produced in the same manner as in Example 24, except that an IrO2 layer with a thickness of 1.0 μm was formed in place of the ReO2 layer. Example 26 A contact material was produced in the same manner as in Example 24, except that an ITO layer with a thickness of 1.0 μm was formed in place of the ReO2 layer.

Example 27 The surface of the base material was cleaned in the same manner as in Example 22, and then a 0.5 μm thick V2 O3 layer and a 0.5 μm thick SnO2 layer were sequentially formed by sputtering, and then a 0.5 μm thick SnO2 layer was deposited on top of that. An Au layer with a thickness of 0.1 μm was formed on the substrate. Example 28 A contact material was manufactured in the same manner as in Example 27, except that a 3.0 μm thick RhO2 layer and a 2.0 μm thick SnO2 layer were sequentially formed by sputtering.

Example 29 An IrO2 layer with a thickness of 0.2 μm was used instead of the RhO2 layer.
0.2μm thick Fe3O4 instead of SnO2 layer
A contact material was produced in the same manner as in Example 28, except that the layers were deposited sequentially. The contact characteristics of the above 14 types of contact materials were investigated in the same manner as in Examples 1 to 9. The above results are collectively shown in Table 3.

[0046]

[Table 3]

[0047]

[Effects of the Invention] As is clear from the above explanation, the contact material of the present invention has good oxidation resistance and organic gas corrosion resistance on the contact surface, low and stable initial contact resistance, and Since the rise is also low, the operating life as a contact is long.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a circuit used to measure contact resistance of a switch.

[Explanation of symbols]

S switch C Cable R resistance E Power supply A Ammeter

Claims (6)

[Claims] [Claim 1] On the surface of the contact base material, SnO2, In
2 O3 , PbO, PbO2 , CdO, Cd2 S
nO4, In-Sn oxide, V2 O3, FeO,
Fe3O4, RuO2, Rh2O3, RhO
2, ReO2, IrO2, TiO, Ti2 O3
1. A contact material comprising a contact coating layer having a thickness of 0.03 to 100 μm and made of a conductive metal oxide containing at least one member selected from the group consisting of: 2. The contact material of claim 1, wherein the contact coating layer is a plurality of layers. 3. The contact material according to claim 1, wherein an intermediate layer made of a soft metal and having a thickness of 0.01 μm or more is interposed between the contact base material and the contact coating layer. 4. The soft metal is Ag, Al, Au,
Co, Cu, Fe, Mg, Ni, Pd, Pt, Sr, T
4. The contact material according to claim 3, wherein the main component is at least one selected from the group consisting of i, Zr, Hf, V, Nb, Ta, Cr, Mo, and W. 5. The contact material according to claim 1, wherein a metal layer having a thickness of 0.01 μm or more is formed as a surface layer on the entire surface. 6. The metal layer is made of Ru, Rh, Pd, R
e, Os, Ir, Pt, Au, Ag, Al, Cu, Ni
, Sn, Ti, Zr, V, Hf, Nb, Ta, Cr, M
6. The contact material according to claim 5, the main component being at least one member selected from the group o.