JPH0773768A - Electric contact material and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Structure] A pure Au layer with a thickness of 0.01 to
An electrical contact material having a thickness of 0.5 μm and further having an organic coating layer formed thereon. [Effect] An electrical contact material having excellent corrosion resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric contact material made of an Au alloy having high hardness and excellent wear resistance, and to an electric contact material having improved corrosion resistance without impairing the wear resistance of the Au alloy.

[0002]

2. Description of the Related Art Conventionally, Au alloys are often used as electrical contact materials because of their high conductivity and good electrical connection and solder wettability. Pure Au is also often used as an electric contact material, but an electric contact material made of pure Au and an electric contact material made of an Au alloy have different applications. That is, A
Although u alloy is inferior in corrosion resistance to pure Au, it is suitable for sliding electric contact materials and electric contact materials to which heavy load is applied because of its high hardness and excellent abrasion resistance.

Although Au has an extremely small ionization tendency, the alloy components constituting the Au alloy usually have a larger ionization tendency than Au, and the Au alloy has a remarkably lower corrosion resistance than pure Au. Therefore, in the case of an electrical contact material made of Au alloy such as a sliding contact material, it is necessary to apply rustproofing treatment to the contact surface.

This rustproofing treatment is usually carried out by a method of forming an organic coating layer on the contact surface. As a method,
A general method is to form an organic coating layer on the surface of the Au alloy by immersing the electrical contact material before rustproofing in a solution containing a rustproofing agent. Such an electrical contact material that has been subjected to anticorrosion treatment has predetermined contact characteristics (electrical connectivity and wear resistance) because the Au alloy is exposed if the organic coating layer on the contact surface is broken at the very beginning of use of the contact. Sex) is realized,
That is.

[0005]

By the way, in the opening / closing operation and sliding when the contact is used, the part where the electric contact material actually contacts the mating material (the other contact material) is only a small part of the contact surface. Is normal. The organic coating layer in that portion (hereinafter referred to as the true contact portion) needs to be consumed and dropped at the initial stage of use of the contact. However, it is rather desirable that the organic coating layer remains in other portions.
This is because even if corrosion occurs at the true contact portion, it is removed at a very early stage of the corrosion due to repeated friction with the mating material, so that the corrosion is unlikely to proceed.

On the other hand, in the case of corrosion that occurs outside the true contact portion, it is difficult to remove it because there is no friction with the mating material. Corrosion that occurs outside the true contact portion grows over time and eventually progresses to the true contact portion (called a creep phenomenon). As described above, when the portion where the organic coating layer has fallen off other than the true contact portion is increased, as a result, the corrosion of the true contact portion is likely to proceed.

By the way, the anticorrosive agent has poor adsorptivity to the Au alloy. Therefore, the organic coating layer formed on the Au alloy often does not sufficiently cover the surface of the Au alloy.
In addition, the organic coating layer often comes off from the Au alloy due to vibration during transportation of the electrical contact material or attachment to electrical equipment. Furthermore, the organic coating layer other than the true contact portion with the mating material often fell off due to vibration or the like during use of the contact. In the case of the conventional electrical contact material that has been subjected to rust prevention treatment in this way, A
The exposed portion of the u alloy was increased, and this was a cause of deterioration in corrosion resistance.

[0008]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies in view of such a situation, and its purpose is to provide an electrical contact having improved corrosion resistance without impairing the wear resistance of the Au alloy. It is intended to provide a material and a manufacturing method thereof. That is, the invention according to claim 1 is a contact base material made of an Au alloy, a pure Au layer having a thickness of 0.01 to 0.5 μm formed by coating the contact base material, and a surface of the pure Au layer. And an organic coating layer formed by coating the above. The invention according to claim 2 is the electrical contact material, wherein the pure Au layer is formed by electroplating or displacement plating. Further, as an invention according to claim 3, after forming a pure Au layer on the contact base material, it is immersed in an organic coating solution containing an aliphatic amine or / and a mercaptan to form an organic compound containing the aliphatic amine or / and the mercaptan. A method for producing an electrical contact material, which comprises forming a coating layer.

[0009]

The electrical contact material according to claims 1 and 2 of the present invention comprises:
A pure Au layer having much better corrosion resistance than the Au alloy is formed on the surface of the Au alloy as the contact base material. Since the pure Au layer is soft, the pure Au layer is consumed and drops off at the true contact portion to expose the Au alloy in the initial use as a contact. However, since the pure Au layer firmly adheres to the surface of the Au alloy, it is unlikely that the pure Au layer will fall off other than the true contact portion due to vibration or the like when the contact is used, as in the case of the organic coating layer. As described above, in the electrical contact material of the present invention, the Au alloy is not exposed except in the true contact portion, and the above-mentioned creep phenomenon in which the corrosion generated in the portion other than the true contact portion progresses to the true contact portion can be prevented. The contact base material is entirely Au.
Even if it is an alloy, A
The u alloy may be plated.

By the way, although pure Au is a material excellent in electrical connectivity and corrosion resistance, it has poor wear resistance and a large coefficient of friction with the mating material. Therefore, when pure Au is used as a sliding contact, it causes the coefficient of kinetic friction with the mating material to increase before the pure Au layer is consumed and drops off at the true contact portion. As a measure against this problem, if an organic coating layer is formed on the surface of the pure Au layer, the coefficient of dynamic friction with the mating material can be lowered in the initial stage of use of the contact.

The organic coating layer is consumed and comes off at the true contact portion in the initial use of the contact. At this time, since the organic coating layer has a good adsorptivity for pure Au, pure A
In many cases, the u layer also falls off together with the organic coating layer. When the organic coating layer is formed on the surface of the pure Au layer in this manner, the coefficient of dynamic friction with the mating material is lowered at the initial stage of use of the contact, and the pure Au layer is promoted to drop off at the true contact portion. Therefore, it is possible to prevent the pure Au layer from being exposed at the true contact portion and increasing the dynamic friction coefficient with the mating material.

In the electric contact material according to claim 1 of the present invention, the thickness of the pure Au layer is 0.01 to 0.5 μm for the following reason. First, when the thickness is less than 0.01 μm, there is a problem that pinholes are easily generated in the pure Au layer when the pure Au layer is formed on the Au alloy. On the other hand, 0.
This is because if the thickness exceeds 5 μm, even if the organic coating layer falls off in the initial stage of use of the contact, the pure Au layer is difficult to fall off quickly, and therefore the coefficient of dynamic friction with the mating material increases. . In addition, if the pure Au layer is thick, the cost increases, which is not desirable.

In the method for producing an electric contact material according to claim 3 of the present invention, examples of the aliphatic amine or mercaptan include dodecylamine, aicosylamine, nonylamine, dodecylmercaptan, octadecylmercaptan, aicosylmercaptan, nonylmercaptan. Etc. can be used. The organic coating layer can be formed by immersing the contact base material on which the pure Au layer is formed in a solution in which one or more of these are mixed. In addition, the pure A
The organic coating layer can also be formed by applying or spraying the solution onto the contact base material on which the u layer is formed. Further, a solvent such as toluene, acetone or trichloroethane may be mixed with the above solution and used. The organic coating layer is made of aliphatic amine and / or mercaptan because these are easily adsorbed on the Au material.

[0014]

【Example】

Inventive Examples Au alloy pieces having the composition shown in Table 1 (20 mm × 5 mm thick)
100 mm) was electrolytically degreased under the following conditions. Liquid: NaOH (50g / l) + surfactant (10g /
l) Liquid temperature: 60 ° C DC current: 2 A / dm ² hours: 30 seconds

After washing with water, the surface of the Au alloy piece was activated under the following conditions. Liquid: KCN (100g / l) Liquid temperature: 20 ° C Time: 60 seconds

Next, a pure Au layer having a thickness shown in Table 1 was formed by electroplating or displacement plating. The solutions and current values used in the electroplating method and the solutions used in the displacement plating method are described below. Electroplating solution: potassium gold cyanide (concentration 3g / l) +
KCN (60 g / l) displacement plating solution: potassium gold cyanide (concentration 0.5 g /
l) + Na ₂ Co ₃ (5 g / l) + NaCN (4 g / l)

Then, after washing with water and drying, the organic treating agent shown in Table 1 was immersed in an organic coating solution containing toluene at a concentration of 0.5% for 30 seconds at room temperature and then dried to form an organic coating layer. . In addition, 10 samples each prepared under each condition shown in Table 1 were prepared.

A sliding test and a corrosion resistance test were performed on the sample thus manufactured. The sliding test was performed by sliding the head (diameter 5 mm) of a pure Au rod. The load in the sliding test is 50 g, the sliding distance is 10 mm, and the number of sliding times is 1
It went up to 0000 times. The dynamic friction coefficient was measured during the sliding test. The number of measurement points is one for each sample.

The corrosion resistance test was conducted as follows.
First, the above sample (sample before the sliding test) was subjected to a sulfurization test as an acceleration test under the following conditions. Gas atmosphere: H ₂ S (3 ppm.) Temperature: 30 ° C. Time: 24 hours After the sulfidation test was performed in this way, the contact resistance was measured. There are 10 measurement points for each sample.

Table 3 shows the above test results. Table 3 shows the maximum value of the dynamic friction coefficient when the number of slides is 1 to 10,
Similarly, the maximum value of the dynamic friction coefficient from 11 to 20 times, 21 to 50 times, and the number of sliding times are 100 times and 1000 times.
The dynamic friction coefficient at each time when the number of times reaches 10,000 times is shown. Also, the average and maximum of the measured contact resistance,
The minimum values are shown in Table 3.

Conventional Example and Comparative Example As a conventional example and a comparative example, the samples shown in Table 2 were prepared. In the conventional example, the pure Au layer was not formed on the surface of the Au alloy, and only the organic coating layer was formed. Comparative Example No. 24 has a pure Au layer only and no organic coating layer is formed. No21
Nos. 23 to 23 are the same as the case of the present invention example except that the thickness of the pure Au layer is the value shown in Table 2. Table 4 shows the measured dynamic friction coefficient and contact resistance.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

Conventional Example No. 19 shown in Table 4 has no pure Au layer and no organic coating layer, and the Au alloy is exposed on the contact surface from the beginning of the sliding test.
The coefficient of kinetic friction did not substantially change until 00 times. On the other hand, in Conventional Example No. 20, since the organic coating layer was formed on the Au alloy, the maximum value of the dynamic friction coefficient when the sliding frequency was 1 to 10 times was lower than that in No. 19. It is considered that this is because the organic coating layer was not completely consumed and remained at the time of 10 times. However, even in No. 20, the number of sliding times is 2
When it was 0 times or more, there was substantially no change in the dynamic friction coefficient, which means that the organic coating layer was consumed and dropped at least at the true contact portion with the counterpart material (Au rod), and the Au alloy was exposed.

Comparative Example No 24 having no organic coating layer is pure A
Since the u layer was exposed, the maximum value of the dynamic friction coefficient at the time of 1 to 10 times was as high as 1.2. But 1
The maximum value of the dynamic friction coefficient from 1 to 20 times is 0.4,
It was stable after that. This indicates that the pure Au layer did not fall off and remained at any time from 1 to 10 times. Further, the maximum value of the dynamic friction coefficient at the time of 1 to 10 times was as high as 1.2 because the mating material and the pure Au layer slid.

As shown in Table 3, in most of the examples of the present invention, the maximum value of the dynamic friction coefficient was lower than that of the conventional example No. 19 when the number of sliding times was 1 to 10 times. This indicates that the organic coating layer had not been removed yet at the time of 10 times. However, the number of sliding times is between 21 and 50 times, and 10
The dynamic friction coefficient was stable at 0, 1000, and 10,000 times. This is because the organic coating layer and the pure Au layer fell off and the Au alloy layer was exposed during at least 20 slides. In addition, the maximum value of the dynamic friction coefficient did not become so large during the sliding times of 1 to 20 times because there was substantially no state in which only the organic coating layer fell off and the pure Au layer remained. It appears to be.

On the other hand, in Comparative Examples Nos. 22 and 23, the maximum value at the time when the number of sliding times was 1 to 10 was as low as 0.2, but the maximum value at the time from 11 to 20 times was 1. It was as high as 2. In this, the organic coating layer remained until any one of the times 1 to 10 times, but after that time, pure Au was used.
Is believed to have remained and slid with the mating material. Further, the fact that the coefficient of kinetic friction was still high even after the number of sliding times was 100 or more indicates that the pure Au layer was hard to fall off because of the thick pure Au layer. On the other hand, No21 having a thin pure Au layer had a maximum value of 0.4 at 11 to 20 times, and it is considered that the pure Au layer had already fallen off at this point.

With respect to the contact resistance measured after the sample was subjected to the sulfidation test, as apparent from Tables 3 and 4, the inventive examples showed significantly lower values than the conventional examples. This is because the example of the present invention caused less progress of corrosion (sulfurization) than the conventional example. The reason is that the conventional example No.
It is considered that No. 19 did not have an organic coating layer, and No. 20 had an organic coating layer formed on an Au alloy having poor adhesion and therefore did not sufficiently cover the surface of the Au alloy. On the other hand, in the example of the present invention, the pure Au layer covering the surface of the Au alloy is hard to fall off and has a poor corrosion resistance.
This is probably because the u alloy was not exposed.

Comparative example No. 22, in which the pure Au layer was too thick,
No. 23 is No 24 in which the thickness of the pure Au layer is the same as that of the present invention
The contact resistance value was almost the same as On the other hand, Comparative Example No
No. 21 had a large contact resistance. Pure Au is the cause
This is probably because the layers were too thin and pinholes increased. Therefore, the improvement in corrosion resistance was insufficient.

[0032]

As described above, the electric contact material of the present invention is A
The pure Au layer formed on the surface of the u alloy prevents corrosion of the Au alloy. Furthermore, due to the organic coating layer provided on the surface of the pure Au layer, the pure Au layer and the organic coating layer are quickly removed at the true contact portion at the very early stage of use of the contact, and the wear resistance is excellent. The Au alloy having a low dynamic friction coefficient with is exposed. Further, the pure Au layer is less likely to fall off except the true contact portion of the contact, and the exposed portion of the Au alloy is less than the true contact portion, resulting in an electrical contact material having excellent corrosion resistance. As described above, the electric contact material of the present invention has excellent properties, and improves the reliability of various electric devices.
It makes a significant contribution to the industry.

Claims (3)

[Claims] 1. A contact base material made of an Au alloy, and pure A having a thickness of 0.01 to 0.5 μm formed by coating the contact base material.
An electrical contact material comprising a u layer and an organic coating layer formed by coating the surface of the pure Au layer. 2. The electrical contact material according to claim 1, wherein the pure Au layer is formed by electroplating or displacement plating. 3. A pure Au layer is formed on the contact base material and then immersed in an organic coating solution containing an aliphatic amine or / and a mercaptan to form an organic coating layer made of an aliphatic amine or / and a mercaptan. The method for producing an electric contact material according to claim 1 or 2, characterized in that: