JPH04294009A - Electric contact material - Google Patents

Abstract

PURPOSE:To reduce a trouble such as a condition fault to the utmost by an electric contact material able to reduce local cell action caused by pin-holes and flaws of gold plating while making it hard to generate an insulator such as hydroxide and hydrate. CONSTITUTION:An electric contact material consists of a first layer 1 which is an electric contact substrate, a second layer 2 where by one of an amorphous alloy, chrome a chrome alloy, tungsten, a tungsten alloy, titanium, a titanium alloy, nickel, a nickel alloy cobalt, a cobalt alloy is selected, a third layer 3 consisting of nickel or a nickel alloy and a fourth layer 4 consisting gold or a gold alloy.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electrical contact materials for switches, connector terminals, electrodes, etc.

0002

2. Description of the Related Art Conventionally, the technology for this type of electrical contact material is disclosed in Japanese Patent Application Laid-Open No. 61-29021. This technology has a two-layer structure in which a highly corrosion-resistant amorphous alloy layer is provided on the base material, and gold plating is applied on top of that.

0003

[Problems to be Solved by the Invention] However, in this technology, the standard potential of gold on the outermost surface is approximately +1.5V, and the standard potential of amorphous alloys is lower than that of crystalline alloys. In the case of nickel and phosphorus, which are amorphous, the standard potential is -0.25V for the former, and -0.27 to -0.3V for the latter, and the potential difference with the outermost layer of gold is large (atmospheric pressure). (standard hydrogen electrode potential), makes it easy to create local batteries, accelerates corrosion, makes it easier to create hydroxides and hydrates in moisture than gold pinholes, and causes non-conductivity, etc. There is a high possibility that it will cause a malfunction. This technology does not take into account the problem of potential difference between the outermost surface plating and the underlying metal, and no matter how highly corrosion-resistant metal is used as the base for gold plating, hydroxides can form from pinholes and scratches in the gold plating. The problem is that it tends to form hydrates.

[0004] In other words, in each of the above layers,
There are always holes called minute pinholes, but when the base material is brass, zinc oxide in the base metal is prioritized from pinholes and scratches, which is a major cause of electrical contact failure. This means that it rises to the surface, leading to poor conduction.

The present invention solves the above-mentioned problems, and can reduce the local battery effect caused by pinholes and scratches in gold plating, and can reduce the local battery effect caused by pinholes and scratches in gold plating. The purpose of the present invention is to provide an electrical contact material that minimizes failures such as poor conduction.

[0006]

[Means for Solving the Problems] Technical means for achieving the above object include a first layer that is an electrical contact substrate, an amorphous alloy, chromium, chromium alloy, tungsten, tungsten alloy, titanium, titanium a second layer selected from one of alloy, nickel, nickel alloy, cobalt, and cobalt alloy; a third layer made of nickel or nickel alloy; and a fourth layer made of gold or gold alloy. Preferably, the third layer is made of a nickel alloy selected from a nickel-tin alloy or a nickel-palladium alloy.

[0007]

[Embodiment] An embodiment of the present invention will be described below with reference to FIG.

[0008] The first layer 1 is an electrical contact substrate, and usually copper or a copper alloy is often used, but either metal or non-metal can be used. The second layer 2 is made of amorphous alloy, chromium, chromium alloy, tungsten, tungsten alloy, titanium, titanium alloy, nickel, nickel alloy, cobalt,
Use a metal with corrosion resistance and wear resistance, such as a cobalt alloy. This second layer 2 has functions of preventing corrosion of the base material, preventing diffusion, and providing wear resistance. The third layer 3 preferably has a small standard potential difference with respect to the gold plating of the fourth layer 4 on the outermost surface, and is made of a nickel alloy, such as a nickel-tin alloy or a nickel-palladium alloy. The fourth layer 4 consists of a thin gold or gold alloy material of 0.01 μm to 2(3) μm. This layer is intended for corrosion resistance and low contact resistance. If sliding wear is severe,
It is possible to add cobalt to gold to give it sliding and abrasion resistance.

Methods for forming each layer include the sputtering method, vacuum evaporation method, ion plating method, CVD method, plating method, etc., but the plating method is preferable from the viewpoint of mass production and cost merit. Note that each of the 2 to 4 layers consists of a thin film having a thickness in the range of 0.01 μm to 5 μm.

[0010] As a result of using the electrical contact material of the present invention, the potential difference can be suppressed to a small level, so the local battery effect caused by pinholes and scratches in gold plating can be reduced, and hydroxide and water This makes it difficult to form insulators such as Japanese-style materials, making it possible to minimize failures such as poor continuity compared to conventional electrical contact materials.

[0011]

As described above, the present invention uses a nickel-tin or nickel-palladium alloy as the base plating in contact with the gold plating on the outermost layer, so that the potential difference can be suppressed to a small level. It is an electrical contact material that can reduce the local battery effect caused by scratches and prevent the formation of insulators such as hydroxides and hydrates, thereby minimizing failures such as poor continuity.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an electrical contact material consisting of each layer of the present invention.

[Explanation of symbols]

1 First layer 2 Second layer 3 3rd layer 4 4th layer

Claims (2)

[Claims] 1. A first layer that is an electrical contact substrate; and any one of amorphous alloy, chromium, chromium alloy, tungsten, tungsten alloy, titanium, titanium alloy, nickel, nickel alloy, cobalt, and cobalt alloy. An electrical contact material comprising a selected second layer, a third layer made of nickel or a nickel alloy, and a fourth layer made of gold or a gold alloy. 2. The third layer is a nickel-tin alloy,
The electrical contact material according to claim 1, characterized in that it is made of a nickel alloy selected from among nickel and palladium alloys.