JPS62150606A - Electric contact - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] This invention relates to the field of electrical contacts used in relays, switches, connectors, and the like.

[Background technology]

Tape contacts or rivet contacts used in relays, switches, connectors, etc. are made of Ag layer or C
Generally, materials containing metals or compounds such as u, Ni, and CdO were plated with Au.

However, in a contact having such a configuration, the Ag layer becomes AgzS under the influence of a trace amount of sulfur present in the atmosphere, and this AgzS wraps around the Au surface (creeping phenomenon) to form a film.

As a result, the performance of the contacts deteriorated. This is particularly likely to occur when a small piece is cut out from a long tape contact point that is welded to a spring material using a Cu-Ni alloy as the base of the Ag layer and the surface of the Ag layer is plated with Au. Ta. Even in the case of a stud contact in which the entire surface is plated with Au, a similar problem occurs through minute pinholes formed in the Au plating layer on the surface, resulting in a problem with the reliability of the contact.

On the other hand, since the prices of precious metals, particularly platinum group metals, have increased significantly, there remains a high demand for inexpensive electrical contacts. Therefore, it is preferable to reduce the thickness of the precious metal plating as much as possible.

[Purpose of the invention]

In view of the above points, it is an object of the present invention to provide an electrical contact that is resistant to the effects of a sulfiding atmosphere, has excellent environmental resistance, and is inexpensive.

[Disclosure of the invention]

In order to achieve the above object, the present invention provides an electrical contact in which the surface of an Ag layer is covered with a metal having excellent thermoelectric properties.
The gist of the present invention is an electrical contact characterized in that the Ag layer contains 5 to 30% Pd.

This will be explained in detail below.

In this invention, unlike the conventional Ag layer, Ag-5 to 30%
Pd alloy is used. Here, % means weight %. Pd
If the amount is less than 5%, the desired effect cannot be achieved. P
When the amount of dO exceeds 40%, it is effective in preventing Ag from sulfidation, but an increase in cost is unavoidable, making it difficult to obtain inexpensive electrical contacts. Moreover, considering the increase in cost, Ag
The creeping resistance of zS does not improve.

The creation of Ag-5~30%Pd alloy is done by using ordinary Ag-Pd
There is no difference from the case of alloys, and there are no particularly difficult problems.

The metal that covers the surface of the Ag layer may be any metal that has excellent thermoelectric properties and is selected depending on the intended use of the contact material. That is, for contacts where arc resistance and welding resistance are important, pt, Re, and Qs are used.

Ir, Rh or alloys thereof are preferred. On the other hand, for contacts where corrosion resistance and electrical conductivity are important, Au or Au-
Co, Au-Ni, Au-In, Au-Ag, Au
-Pd alloys are preferred.

In terms of cost and performance, the thickness of the metal to be coated is 0.1 to 5. O
A thickness in the range of ttm is sufficient.

As a method for coating the surface of the Ag layer with the above-mentioned metal, there are commonly used methods such as a plating method or a rolling method. In carrying out this invention,
No particular problem arises no matter which method is used.

(Example 1) A long tape contact having a three-layer structure was created, and then,
A contact 1 having a shape as shown in FIG. 1 was cut out. This contact 1 has a base 2 made of Cu-Ni alloy and an upper layer 3 made of Ag.
-7, 10, 25% Pd alloy is used, and the surface 4 is further plated with Au to a thickness of 0.2-. Au plating was performed using a conventional method.

As a comparative example, the base 2 is made of a Cu-Ni alloy, the upper layer 3 is made of Ag that does not contain Pd and Ag that contains 3% Pd, and the surface 4 is made of Au with a thickness of 0.2 μm.
A plated plate was prepared. These electrical contacts
The Agz S surface was exposed for a long time under conditions of 3±1 ppm H2S atmosphere, 40° C., and 95% relative humidity, and the presence or absence of creeping on the surface of Agz S was investigated over time.

(Example 2) As shown in FIG. 2, a stud contact 11 having a three-layer structure entirely covered with Au plating was prepared. An Ag-10% Pd alloy was used for the upper layer 3 of the base.

The rest is the same as in Example 1.

The results of Example 1.2 are shown in Table 1.

On: Creeping present -: Test stopped From the results shown in Table 1, it is clear that the electrical contact according to the present invention has much better performance than the comparative example.

〔Effect of the invention〕

Since the electrical contact according to the present invention has the above-described structure, it is resistant to the effects of sulfidation in the atmosphere, especially creeping properties, even though the contacts are mainly made of Ag, which is a relatively inexpensive noble metal. It has a strong resistance and therefore has excellent environmental resistance, resulting in a long life of the electrical contact and a highly reliable electrical contact. moreover,
Since the expensive Pdl can be kept as low as possible, it is possible to realize an inexpensive and highly practical electrical contact.

[Brief explanation of drawings]

FIG. 1 is a perspective view of one embodiment of the electrical contact according to the invention, and FIG. 2 is a sectional view of another embodiment of the electrical contact according to the invention. 1.11... Electrical contact 3... Ag layer 4... A
G-layer surface agent Patent attorney Takehiko Matsumoto B41 Figure 2 Hand □ City official letter (Spontaneous May 1, 1986 2, Title of invention Electrical contact 3, Relationship with the amended person case Patent application Address: 1048 Kadoma, Kadoma-shi, Osaka Name (583') Matsushita Electric Works Co., Ltd. Representative: Sadao Ugai, representative 4, agent 5, number of inventions to be increased due to amendment 6, subject of amendment Description 7, Contents of amendment (1) On page 3, lines 4 to 7 of the description, “On the other hand,
··preferable. ” will be deleted. (2) "40%" in the first line of page 4 of the specification should be replaced with "30%"
0%” is corrected. (3) On page 4, line 4 or line 5 of the specification, it should be stated that ``Moreover,...
··do not. ” will be deleted. (4) Insert rRu, J between rRe, J and "O3" on page 4, line 12 of the specification. (5) Between "preferable" and "and" on page 4, lines 16 to 17 of the specification, there is a statement that says, "The surface of the Ag layer is coated with at least one of the above metals in one or multiple layers. Insert "." (6) Table 1 on page 6 of the specification is corrected as shown in the attached sheet.

Claims (5)

[Claims] (1) An electrical contact in which the surface of an Ag layer is covered with a metal having excellent thermoelectric properties, wherein the Ag layer contains 5 to 30% Pd. (2) Metals with excellent thermoelectric properties include Au, Pt, and R.
2. The electrical contact according to claim 1, which is at least one selected from the group consisting of Ru, Ru, Pd, and alloys thereof. (3) The thickness of the metal covering the surface of the Ag layer is 0.1 to 5.0
The electrical contact according to claim 1 or 2, which has a diameter of μm. (4) The electrical contact according to any one of claims 1 to 3, wherein the metal covering the surface of the Ag layer is obtained by plating. (5) Claims 1 to 3, wherein the metal covering the surface of the Ag layer is obtained by a rolling method.
Electrical contacts described in any of paragraphs.