JPH0244106B2 - DENKYOSETSUTEN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a contact that constitutes an electrical contact portion such as a connector terminal.

[Conventional technology]

Conventionally, connector terminals have been made of brass, phosphor bronze, etc., and a plating layer of precious metal has been provided on the surface to improve wear and contact resistance deterioration.

In such a conventional technique, for example, a layer of 1 to 100 ml thick is coated as a base on a copper alloy base as described above.
A nickel plating layer of 10μm is provided, and a thickness of
It is known to construct electrical contacts by applying a gold plating layer of 0.5 to 2 μm. However, if the thickness of the gold layer on the surface of such contacts is reduced, the corrosion resistance will be poor, and defects will increase especially when post-processing is performed, so attempts have been made to improve the corrosion resistance by increasing the thickness of the gold layer. This inevitably led to higher costs.

JP-A-58-218783 discloses a brush material for sliding contacts in which a copper alloy is coated with nickel as the first layer, platinum or palladium as the second layer, and gold or silver as the third layer. has been disclosed, but attempts are made to improve chemical stability and wear resistance during sliding and prevent electrical corrosion by providing a layer of platinum, palladium, etc. between the nickel layer and the gold layer. It is. However, if such an intermediate layer is thin, it is less effective; if it is thick, it increases cost, reduces hardness, and deteriorates wear resistance. In particular, palladium absorbs hydrogen and becomes brittle, shortening its service life. There are drawbacks.

Furthermore, H. Grossmann et al. (METALL 38 ,
Heft7 (1984), 631) discloses a technique in which palladium or palladium-nickel alloy is plated on a copper alloy substrate, and a gold-cobalt alloy is thinly plated thereon. However, it has been found that although such materials exhibit good performance, they tend to become brittle in adverse environments and have shortened lifespans due to peeling of the plating layer, etc.

[Problem to be solved]

Under the above circumstances, there is a need for electrical contacts that have a level of wear resistance that could not be achieved with conventional technology, and in particular can achieve a long life without peeling or other defects even under adverse environments. The object of the invention is to provide such an electrical contact.

[Means for problem solving]

As a result of intensive research to achieve the above objectives,
Excellent durability is achieved by sequentially plating a copper alloy substrate with a nickel layer as the first layer, a nickel-containing palladium alloy layer as the second layer, and a gold-based alloy or gold layer as the top layer. It has been discovered that electrical contacts that are resistant to wear and free from defects over long periods of time can be obtained, and that their excellent performance can be maintained even when the thickness of the middle and upper layers is made extremely thin to reduce manufacturing costs. be.

That is, the electrical contact of the present invention is formed by laminating, on a conductive substrate, a nickel layer as a lower layer, a nickel-containing palladium alloy layer as an intermediate layer, and an alloy containing gold as a main component or a gold layer as an upper layer.

The conductive substrate of the present invention may be made of any conductive material commonly used as a terminal, such as brass or phosphor bronze.

The lower nickel layer is obtained by plating nickel on the conductive substrate using a known plating method.
Suitably, the nickel layer has a thickness of 10 μm or less, preferably 5 μm or less.

The intermediate nickel-containing palladium alloy layer is obtained by plating the above-mentioned nickel layer using a known plating method. It has high wear resistance and improved environmental resistance, suppressing corrosion and peeling, and is effective in extending contact life. Further, a thickness of about 0.6 μm is sufficient for this alloy layer, and increasing the thickness is not economical even considering the degree of performance improvement.

The upper gold alloy or gold layer is obtained by plating the palladium alloy layer by known plating means. As the gold alloy, any alloy that has low contact resistance, is stable, and is hard and hard to wear, such as an alloy in which a small amount of platinum, silver, nickel, or cobalt is added to gold, can be used. Further, the thickness of the gold alloy or gold layer is approximately 0.3 μm, and it is not economical to make it thicker than that.

〔Example〕

Electrodeposit nickel to a thickness of 3 μm on a brass plate,
Palladium containing 20% nickel was electrodeposited thereon to a thickness of 0.6 μm, and gold was further electrodeposited thereon to a thickness of 0.1 μm to obtain a material for forming connector terminals.

The contact part of the connector terminal obtained in this way is
Compared to contact materials using conventional technology, corrosion was less likely to occur even in high humidity and corrosive atmospheres, stable contact resistance was exhibited, and the lifespan was long.

In addition, with conventional contacts in which gold plating was applied directly onto the nickel plating layer, in order to obtain the same corrosion resistance as in this example, it was necessary to use a gold plating layer with a thickness of 2 μm or more. On the other hand, in this example, the total thickness of the palladium alloy layer and the gold layer is 0.7 μm.
It is clear that a contact with good performance can be obtained at low cost.

〔Effect of the invention〕

As explained above, the electrical contacts of the present invention have a specific layered structure, and even when used under harsh environments, there is little corrosion or peeling, and the wear resistance is improved. It has the advantage of being able to create highly reliable terminals that exhibit stable contact resistance over a long period of time at low cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of the electrical contact of the present invention. DESCRIPTION OF SYMBOLS 1... Conductive base, 2... Nickel layer, 3... Nickel-containing palladium alloy layer, 4... Gold layer.

Claims (1)

[Claims] 1. An electrical contact formed by laminating a nickel layer as a lower layer, a nickel-containing palladium alloy layer as an intermediate layer, and an alloy containing gold as a main component or a gold layer as an upper layer on a conductive substrate.