JPH04169010A - Electric contact material - Google Patents

Abstract

PURPOSE:To provide excellent wear and corrosion resistance and make a gold- plated film thin by forming a nickel-phosphorus film containing 20-25A% phosphorus on base material made of metal and non-metal with non-electrolytic plating and forming a gold-plated film thereon. CONSTITUTION:A nickel-phosphorus film 2 containing 20-25A% phosphorus is formed on base material made of metal and non-metal with non-electrolytic plating, and a gold-plated film 3 is fornW thereon. In this case, forming with non-electrolytic plating allows extremely less exposition of a substrate pin hole, therefore to reduce corrosion through the substrate. Excellent wear and corrosion resistance is thus provided to permit thin surface gold plating because ground plating material is corrosion resistant.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The prior art related to the present invention is disclosed in Japanese Patent Application Laid-Open No. 61-29021.
There is a public notice of issue.

This product is a material for electrical contacts that requires low contact resistance, ease of soldering, and high corrosion resistance, and by applying an amorphous alloy on the electrical contact material and coating gold on top of it, high performance electrical contacts can be achieved. This is a manufacturing method for obtaining contacts.

Further, this electrical contact is an alloy electrical contact having a thickness of about 0.254 to 0.276 μm of gold coated on the amorphous alloy and a thin composite film on the amorphous alloy.

Further, the amorphous alloy is a nickel-phosphorus alloy manufactured by electroplating.

(Problem to be Solved by the Invention) However, the electrical contact material has low corrosion resistance and wear resistance because it forms an amorphous alloy layer using an electroplating method, and therefore, the gold plating film on the surface has low corrosion resistance and wear resistance. There is a problem in that it needs to be thicker, which increases the cost.

The technical object of the present invention is to provide an electrical contact material which has excellent corrosion resistance and wear resistance and which can have a thin gold plating film.

[Structure of the invention] (Means for solving the problem) The technical means taken to solve the problem are as follows.

An electrical contact material made by forming a nickel-phosphorus film containing 20 to 25 at% phosphorus on a base material made of metals and non-metals by electroless plating, and then forming a gold plating film on top of it. .

(Function) The nickel-phosphorus plating film containing 20 to 25 atom % of phosphorus has excellent wear resistance (10 times that of the conventional film) and also has corrosion resistance.

Further, since the base plating material has corrosion resistance, even if the gold plating on the surface is thinned, it has corrosion resistance and is optimal as an electrical contact material.

(Example) Examples will be described below.

FIG. 1 shows the material structure of this embodiment. Reference numeral 1 indicates an electrical contact material, which is usually made of copper or copper alloy, but may be made of either metal or non-metal.

2 is an electroless nickel plating film with a phosphorus content of 20 to 25 atom %, and 3 is a gold or gold alloy plating film.

In this example, high phosphorus (20 to 2
A nickel-phosphorus plating film containing 5 atom %) is provided.

The method for creating the plating film will be described below.

Metsuki chemical composition is Nickel chloride 20-30g/12 Trisodium citrate 40-50g#! N-2
Hydroxyethyl 2-3g/! Ethylenediamine trisodium saccharin sodium 1-2 g/l
Lithium sulfate: 20-25g/1 Sodium hypophosphite: 5-log/l, the pH is adjusted to 4.4-4.9 with dilute sulfuric acid, and the plating temperature is maintained at 90°C.

Brass is used as the base material here, and before plating, it is subjected to solvent degreasing, immersion degreasing, electrical degreasing, and activation treatment.

After the above pretreatment, the base material is washed with water, immersed in a plating solution, and electroless plating is started using an electric start. In this case, the base material can be used as a cathode, and the anode can be made of stainless steel, nickel, platinum, or gold; here, a stainless steel plate is used.

Electroplating is performed for 10 to 30 seconds by applying a voltage of 1 μ between the electrodes. Even after the current supply is stopped, the plating reaction occurs and electroless plating continues thereafter.

Normally, electroless nickel plating does not cause a plating reaction on copper-based materials (the general method for plating start-up is to use the above-mentioned electric start or a catalyst such as palladium chloride.

Once a thin nickel plating layer is formed on the material, the plating reaction can continue without any problem since the reaction occurs on the nickel layer.

A nickel-phosphorus plating film can be formed on brass using the above method, but the phosphorus concentration in this nickel-phosphorus is as high as 20 to 25 at%, and the phosphorus content was measured using EPMA. .

The following is a comparison of the chemical resistance and abrasion resistance of the nickel-phosphorus plating containing 23 at.% phosphorus prepared by this plating and the nickel-phosphorous plating containing 8 at.% phosphorus produced by electro-nickel plating and electroless method. Shown in the table.

Table 1 Table 1 shows the chemical resistance, and chloride as a corrosive liquid.
Iron solution (Fecl 100g/f) and dilute hydrochloric acid (IN
These are the results of crushing and observing test pieces of 5 am and 5 cm square each using Hci. All but the nickel-phosphorus plating containing 25 at.% phosphorus are attacked by the corrosive liquid.

Figure 2 shows the measurement of the corrosion current when the anode was corroded in 3% salt water, where 4 is the saturation force Romero electrode, 5 is the salt bridge, 6 is the walking electrode, 7 is the platinum electrode, and 8 is the 3% 9 is a salt water, 9 is a KCl solution, 10 is a magnet, and 11 is a magnetic stirrer.

Figure 3 is a schematic diagram of the measurement; the voltage sweep speed was 50 mv/30 s, and the sample size was 6 x 6 m.
The solution was constantly stirred using a magnetic stirrer.

In Fig. 3, (a) is a nickel-phosphorus plating film containing 23 at.% phosphorus made by electroless plating method, and (b) is a nickel-phosphorous plating film containing 8 at.% phosphorus (C
) is an electro-nickel plated film.

As the polarized electrode is raised to the positive side, a corrosion current flows in the solution, and the current value of the 23 atom % nickel-phosphorus plating film in (a) is the smallest, indicating that it is less likely to be corroded.

Figure 4 shows the results of the LFW friction test.

The rotation speed is 62 rpm and the load is 1/2 lb. 205
The amount of friction of the test piece after 0 rotation was measured.

(a), (b), and (c) in Fig. 4 correspond to those in Fig. 3, but the amount of friction of the nickel-phosphorus plating film containing 23 atom% phosphorus in (a) is the smallest and the wear resistance is It shows that you are sexually superior.

Next, FIG. 5 shows the results of a comparison of the number of pinholes in nickel-phosphorus plating films containing 20 to 25 atom % phosphorus obtained by the electrolytic method.

The thickness of each film was 1.3 μm, and the test solution was a solution of aqueous ammonia + ammonium sulfuric acid. The immersion time was 2.
0 minutes, and the number of pinholes in test piece 1 cTi is extremely small due to the electroless method.

1.3 nickel-phosphorus coating according to the present invention on a brass substrate
The results of a qualitative analysis using an X-ray microanalyzer of the parts that changed color and bulged up after being subjected to a salt spray test on which 0.1 μm of gold was applied on top of the 0.1 μm gold are shown. The accelerating voltage was 20 keV, and the analysis method was standardless (Na or higher).

This results in atomic percent of 72% zinc, 10% copper, and 7% nickel.
%, chlorine 8%, and gold 3%. In other words, this indicates that zinc in the base material is preferentially corroded through pinholes in the nickel-plated portion.

Furthermore, the electrical resistance of this portion is extremely high, leading to failure as an electrical contact. For this reason, it is important to reduce the number of pinholes in the plating layer underlying the gold plating. As described above, the base plating of gold plating used as an electrical contact must have excellent corrosion resistance, and if both the problems of corrosion and binho can be solved, high reliability can be obtained.

(effect) The present invention has the following effects.

That is, (1) Unlike the conventional electroplating method, the present invention uses an electroless method to create the material, so the exposed parts (pinholes) of the substrate are extremely reduced, and corrosion from the substrate is prevented. Reduce.

(2) Due to the use of an electroless method, plating films could only be obtained on metal substrates;
It is also possible to form a film on glass, etc.), eliminating the need to limit the substrate to metal.

[Brief explanation of drawings]

Figure 1 is a sectional view of the material structure of this example, Figure 2 is a schematic diagram of the anode polarization device, Figure 3 is an anode polarization curve diagram, and Figure 4 is a diagram of the anode polarization curve.
The figure is a wear characteristic diagram, and FIG. 5 is a relationship diagram between plating and pinholes. ■...Base material, 2...Nickel-phosphorus film containing 20 to 25 at.% of phosphorus.

Claims (1)

[Claims] An electrical contact material obtained by forming a nickel-phosphorous film containing 20 to 25 at % phosphorus on a base material made of a metal or a non-metal by electroless plating, and forming a gold plating film thereon.