JPH06187867A - Contact material and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a contact material which is readily available at low cost and excellent in corrosion resistance, contact resistance, flexibility, spring characteristic and expansibility and a method of manufacture thereof. CONSTITUTION:A strip nickel clad stainless steel base is entirely or partially plated with one kind selected from rare metals, tin and tin alloys. The contact material is subjected to contact resistance test, salt spray test, sulfur dioxide exposure test, sulfur dioxide-sulfide gas exposure test and bending test, etc. Therefore an anti-corrosion treatment can be omitted after pressing and good results are obtained as to the variety of tests and the material proves to exhibit excellent characteristics especially in the medium current range and the medium voltage range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is excellent in contacts such as connectors and switches, especially in weak, medium current, weak and medium voltage regions, and is excellent in corrosion resistance, contact resistance, bendability, spring characteristics and spreadability. The present invention relates to a contact material and a manufacturing method thereof.

[0002]

Conventionally, copper alloys such as brass, phosphor bronze, beryllium copper, titanium copper, and oxygen-free copper have been widely used as electrical contact materials for connectors, switches and the like. That is, brass is used as a contact material that does not require much spring characteristics because it is lower in price than other copper alloys, and beryllium copper requires a heat hardening treatment and is expensive, Since it has excellent spring characteristics, it is used as a highly reliable contact material. Titanium copper has excellent heat resistance characteristics, and oxygen-free copper has excellent malleability. It is used as a contact material in a field suitable for the characteristics of each of these various copper alloys. In addition, phosphorous copper is often used as a spring contact material as a substitute material for beryllium copper.

However, if the copper alloy material is used as it is as a contact, it is sulphidized or oxidized in the atmosphere to form a film, so that it is used only for a strong current which destroys these films. Therefore, as a weak current contact such as an electronic component, a copper alloy material directly plated with a noble metal such as gold or palladium or tin may be used. However, since mutual diffusion occurs between the copper alloy material and these plating films due to heat generation and aging, increase in contact resistance and poor soldering are likely to occur. Therefore, in general, nickel plating is formed as an intermediate coating on a copper alloy material for the purpose of preventing mutual diffusion, improving contact hardness, and improving wear resistance.

As a method of manufacturing a contact using a nickel-plated copper alloy material, (1) a strip-shaped copper alloy material is entirely nickel-plated, and then a precious metal, tin, tin alloy or the like is wholly plated or partially coated. A method of manufacturing contacts by press forming after plating. (2) A strip-shaped copper alloy material that has been made into a contact shape by pressing is nickel-plated, and then a method such as total plating or partial plating of precious metals, tin, tin alloys, etc. is performed. There is.

In recent years, there has been a demand for lower prices,
Partial plating of contacts is being further promoted. Along with this, in the contacts for high-density mounting, solder plating processing is often used except for the contact portions in order to cope with soldering during assembly. However, in the case of continuous hoop plating of press-formed products as the contact pitch is shortened and the contact surface becomes three-dimensional and the two films are very close to each other, a general liquid level control method causes both films to overlap due to the influence of meniscus. It causes problems such as being lost.

As a method for solving the problem of such press-formed products, processing methods such as resist ink, masking method, tape masking method, belt masking method, drum masking method, brush plating method and jig masking method are adopted. Has been done. However, it is difficult to manage the masking material, masking jig, etc. to maintain the processing accuracy. Further, these methods make it difficult to apply them to small lots and many kinds of products, since the initial cost becomes a large ratio of manufacturing cost. In order to solve the above-mentioned problems of the press-molded product, there is a tendency that the number of contact materials to be press-molded after partial plating in the state of a band material that can be easily masked increases.

Further, as a problem of the contact material for the press-formed product after the strip-shaped plating, there is a case where the copper alloy material is exposed on the fracture surface of the press by the press working after the plating, and the sulfuration or the oxidation reaction occurs from the exposed portion of the material. In addition, depending on the environmental conditions used, the copper alloy may be significantly corroded, causing corrosion products to reach the contact area and contaminate the contact area of precious metals, tin, tin alloys, etc. It is difficult to apply to reliable contact points.

In order to temporarily eliminate such a problem, generally, after press working, a corrosion rust preventive agent for copper, a lubricating oil or the like is applied to prevent corrosion. However, although these coating films have a temporary rust preventive effect, the present condition is that the effect cannot be guaranteed for a long time. Further, in order to dissolve the corrosion rust preventive agent or the lubricating oil, there are many problems such that an organic solvent such as 1.1.1 trichloroethane generally has to be used.

Recently, as a substitute for copper and copper alloy contact materials, nickel or stainless steel has been plated with nickel, and then noble metals or tin or tin alloys have been completely or partially plated on contact materials or stainless materials. Some of the contact materials are directly plated with gold.

[0010]

However, when nickel plating is applied to a stainless steel material, a strongly acidic nickel plating bath containing hydrochloric acid called a wood bath is used. Etching causes pitting corrosion on the surface of stainless steel, and it is difficult to completely cover this pitting corrosion with a general contact nickel plating thickness (1.0 to 5.0 μm). As clearly shown in the test, there is a problem that the plated product is inferior in corrosion resistance to the stainless steel material alone. In addition, a stainless steel material directly plated with gold also has the same problem as nickel plating because a strong acid plating bath of hydrochloric acid is used. recent years,
Since a strong acid plating bath of sulfuric acid was developed, environmental test characteristics such as salt spray were improved, but there was a problem that the corrosion protection of the contact part was not perfect.

The present invention provides a contact material which is excellent in corrosion resistance, contact resistance, bendability, spring characteristics, spreadability and does not require a rust preventive treatment as a post-process, which does not cause such a problem, and a contact material thereof. It is intended to provide a manufacturing method.

[0012]

Means for Solving the Problems As a result of repeated research to solve the above problems and achieve the above objects, the present inventors have clad nickel or nickel-base alloy as a stainless steel material and used it as a material. The present invention has been completed by finding that the object can be achieved by plating a noble metal, tin, or a tin alloy on this (hereinafter referred to as nickel-clad stainless steel material) to form a contact. That is, the first embodiment of the present invention is a nickel-clad stainless steel base material, at least one plating selected from various precious metals, tin and tin alloys formed on the base material as whole plating or partial plating. A contact material having excellent corrosion resistance, contact resistance, bending property, spring property, and spreadability, which is characterized by comprising a layer. A method for producing a contact material, which is excellent in corrosion resistance, contact resistance, ductility, and spring characteristics, in which one kind selected from noble metals, tin and tin alloys is subjected to whole plating or partial plating, and a third embodiment. Is a nickel-clad stainless steel base material that has been press-molded, and one or more selected from various precious metals, tin, and tin alloys is subjected to total plating or partial plating. That corrosion, contact resistance, bending resistance, a method of manufacturing a contact material having excellent spring characteristics.

The nickel-clad stainless steel substrate used may be one produced by a usual method, and a strip-shaped or pressed product is used. The nickel layer preferably has a thickness of 1.0 to 5.0 μm.

The plating of the noble metals, tin and tin alloys is preferably 0.01 to 10 μm in thickness. The tin plating is, for example, a borofluoride gloss bath, and the silver plating is, for example, an alkali silver cyanide plating. The bath and palladium-nickel plating may be carried out by a usual method using, for example, an aluminum chloride palladium-nickel chloride plating bath and gold plating, for example, using an acid hard cobalt gold plating bath of a citrate buffer solution.

[0015]

The contact material according to the present invention is made of stainless steel clad with nickel or a nickel-base alloy, and therefore, pitting corrosion due to etching during the plating treatment is more likely to occur than that of a copper-based material or a stainless steel material nickel-plated. It does not occur and has excellent corrosion resistance. During press working after plating with noble metal, tin, tin alloy, etc., no material is exposed due to press rupture. Therefore, no sulfidation or oxidation reaction occurs from the exposed portion of the material, and the contact portion is not contaminated by corrosion products, so that no contact failure occurs. Further, it is also excellent in bendability, spring characteristics and spreadability.

[0016]

EXAMPLES Next, examples of the present invention will be described. Example 1 A strip-shaped nickel-clad stainless steel substrate (SUS 30
Four materials clad with nickel to a thickness of 3 μm, width 1
5.5 mm, length 50 mm, thickness 0.2 mm) at 50 ° C
After electrolytic degreasing treatment in alkaline cyanide degreasing solution at 6V for 15 seconds, dipping treatment in 10% sulfuric acid at room temperature for 30 seconds for activation treatment, and using acid hard cobalt gold plating bath of citrate buffer solution Gold plating with a thickness of 0.2 μm. Then, the sample was cut into 30 mm, and various tests as described below were performed.

1) Contact resistance: KS Parts Research Laboratory MS8
00 contact resistance meter, open-circuit voltage 50 mV, measuring current DC 10 mA, load 10 g, measuring probe with diameter 1φ and 0.5R tip processed K625 alloy (gold 6
2.5%, 29% silver, 8.5% copper alloy) was measured at 50 locations with the central portion of the sample set at 0.1 mm intervals. The results are shown in Table 1.

2) Corrosion resistance test: (a) Salt spray test:
A 5% saline solution was sprayed at 35 ° C. for 96 hours. (B) Sulfurous acid gas test: The sample was exposed for 240 hours in an atmosphere having a sulfurous acid gas concentration of 25 ppm at 25 ± 2 ° C. and a relative humidity of 75%.
(C) Mixed gas test: The sample was exposed to a mixed gas atmosphere having a sulfur dioxide concentration of 10 ppm and a sulfide gas concentration of 3 ppm at 40 ± 2 ° C. and a relative humidity of 75% for 96 hours. After each test, the sample was ultrasonically washed with pure water, dipped in ethyl alcohol, dried with a dryer, and the corrosion state of the contact portion and the cross-sectional portion was observed with an optical microscope and a scanning electron microscope. The results are shown in Table 2, FIG. 1 (a) and FIG. 2 (a).

3) Bending test: Using a press standard No. 0 tester manufactured by Shikishima Co., a sample was placed horizontally on a simple press mold, and the handle was manually rotated to bend it at 90 degrees,
The bent portion was observed with a scanning electron microscope. The result is shown in Figure 3.
Shown in (a). Example 2 A nickel stainless clad substrate was prepared in the same manner as in Example 1,
0.5μm thickness using neutral cyanide pure gold plating bath
Then, each test was conducted in the same manner as the tests 1) and 2) of Example 1. The results are shown in Tables 1 and 2. Example 3 A nickel-clad stainless steel substrate similar to that of Example 1 was tin-plated with a thickness of 3.0 μm using a borofluoride brightening bath, and the same as Tests 1) and 2) of Example 1. Each test was performed. The results are shown in Tables 1 and 2. Example 4 A nickel-clad stainless steel substrate similar to that in Example 1 was used, and an alkali silver cyanide plating bath was used to obtain a thickness of 2.
Each layer was plated with 0 μm of silver, and each test was conducted in the same manner as in Tests 1) and 2) of Example 1. The results are shown in Tables 1 and 2. Example 5 A nickel-stainless steel clad substrate was prepared in the same manner as in Example 1,
Using an ammine palladium chloride plating bath, a thickness of 0.
Example 1 was performed by using 76 μm palladium plating and 0.05 μm thick gold plating using the same bath as in Example 1.
Each test was carried out in the same manner as the tests 1) and 2). The results are shown in Tables 1 and 2. Example 6 The same nickel-clad stainless steel substrate as in Example 1 was added,
Using ammine palladium nickel plating bath
Each test was performed in the same manner as in Tests 1) and 2) of Example 1 by performing palladium nickel plating with a thickness of 1.0 μm and gold plating with a thickness of 0.05 μm using the same bath as in Example 1. . The results are shown in Tables 1 and 2. Example 7 MX9 which is widely used as a contact material having spring characteristics
6, MX216, C1720, C5210, C7250
Table 3 shows copper gold such as SUS304, nickel clad material of SUS304, and nickel clad material of SUS301.
It was determined by each test shown in. Comparative Example 1 With respect to the nickel-clad stainless steel base material similar to that of Example 1, each test was performed in the same manner as the tests 1) and 2) of the example. The results are shown in Tables 1 and 2. Comparative Example 2 Stainless Steel Material (SUS304, Width 15.5 mm, Length 5
(0 mm, thickness 0.2 mm) was electrolytically degreased in an alkaline cyanide degreasing solution at 50 ° C. for 6 V for 15 seconds, and then immersed in 10% hydrochloric acid for 30 seconds at room temperature for activation for activation. Then, a nickel strike plating base treatment was performed using a hydrochloric acid-acidic wood bath. Then, 3.0 μm thick nickel plating was performed using a sulfamic acid bath, and 3.0 μm thick tin plating was performed using a borofluoride brightening bath. The tests 1) and 2) of Example 1 were performed on this sample, and the obtained results are shown in Tables 1 and 2. Comparative Examples 3 to 5 In the same manner as in Comparative Example 2, the activation treatment, the base treatment and the thickness 3
After performing a nickel strike plating treatment of μm, a silver having a thickness of 2.0 μm was plated using the same type of bath as in Example 3 (Comparative Example 3), and a bath of the same type as in Example 4 was used. A palladium-nickel alloy plating having a thickness of 1.0 μm and a gold plating having a thickness of 0.05 μm (Comparative Example 4), and the same bath as in Example 1 were used to obtain a thickness of 0.2.
A product plated with μm of gold (Comparative Example 5) was obtained, and each test was performed in the same manner as in Tests 1) and 2) of Example 1. The results are shown in Tables 1 and 2. For Comparative Example 5, test 3) was also performed, and the results are shown in FIG. 1 showing the results of tests 1) and 2).
It is shown in Fig. 3 (b) together with Fig. 2 (b) and Fig. 2 (b). Comparative Examples 6 and 7 After base treatment, gold strike plating was performed using a hydrochloric acid-acidic second potassium potassium cyanide bath, and then 0.2 μm thick gold plating was performed using the same bath as in Example 1. (Comparative Example 6) and the activation treatment using 10% sulfuric acid, the base treatment was performed using a sulfuric acid-acidic second potassium gold cyanide bath, and the same bath as in Example 1 was used. A 0.2 μm-thick gold strike-plated product (Comparative Example 7) was obtained, and each test was performed in the same manner as in Tests 1) and 2) of Example 1.
The results are shown in Tables 1 and 2. Comparative Example 8 Each test was performed on the stainless steel material (SUS304) in the same manner as in Tests 1) and 2) of Example 1. The results are shown in Table 1.
And shown in Table 2. Comparative Example 9 Phosphor bronze material (width 15.5 mm, length 50 mm, thickness 0.
2 μm) was subjected to a degreasing treatment in the same manner as in Example 1 and an activation treatment with 10% sulfuric acid, and then a copper strike plating base treatment using an alkali copper cyanide plating bath,
In the same manner as in Comparative Example 2, 3.0 μm thick nickel plating and 3.0 μm thick tin plating were applied. The tests 1) and 2) of Example 1 were performed on this sample. The results are shown in Tables 1 and 2. Comparative Examples 10 to 12 After activation treatment, base treatment and nickel plating with a thickness of 3.0 μm were performed in the same manner as in Comparative Example 9, the same bath as in Example 3 was used and silver with a thickness of 2.0 μm was used. Plated (Comparative Example 10), plated with a 1.0 μm thick palladium-nickel alloy using the same bath as in Example 4 (Comparative Example 11), and similar to Example 1. Gold-plated with a thickness of 0.2 μm using a bath (Comparative Example 1)
2) was obtained, and each test was conducted in the same manner as the tests 1) and 2) of Example 1. The results are shown in Tables 1 and 2. Comparative Example 13 After degreasing treatment, activation treatment with 10% hydrochloric acid, nickel strike plating base treatment, and nickel plating treatment with a thickness of 30 μm were performed in the same manner as in Comparative Example 2, and then Example 1 was performed.
A 0.2 μm-thick gold-plated product was obtained using the same bath as above, and each test was conducted in the same manner as in Tests 1) and 2) of Example 1. The results are shown in Tables 1 and 2, FIG. 1 (c) and FIG. 2 (c).
And shown in FIG. 3 (c). Comparative Example 14 The tests 1) and 2) of Example 1 were performed on the phosphor bronze material. The results are shown in Tables 1 and 2.

[0020]

[Table 1]

[Table 2]

[Table 3] From these results, the contact material obtained by the present invention is extremely excellent in contact resistance characteristics, corrosion resistance, bending characteristics, spring characteristics, etc. as compared with conventional copper and copper alloys or nickel plated materials on stainless steel. It is recognized that it has excellent properties. Therefore, it can be seen that the conventional contact material can be applied to high-reliability parts which are difficult to apply.

Although the present invention has been described with reference to a stainless material in which nickel or a nickel-based alloy is clad, it can be similarly applied to a stainless material having nickel or a nickel-based alloy vapor-deposited on its surface.

[0022]

EFFECTS OF THE INVENTION Since the present invention is a nickel clad stainless steel substrate plated with a noble metal, tin, tin alloy, etc., it is a contact excellent in corrosion resistance, contact resistance, bendability, spring characteristics and spreadability. The material can be obtained easily and inexpensively, and the rust preventive treatment can be omitted altogether after the press working, and a remarkable effect is recognized.

[Brief description of drawings]

FIG. 1 is a photograph showing a metallographic structure by a microscope of an example of a corrosion state of a contact surface after a salt spray test.
(b) is a diagram showing Comparative Example 5, and (c) is a diagram showing Comparative Example 13.

FIG. 2 is a photograph showing a metallographic structure of a corrosion state of a fracture surface of a press after a salt spray test by a microscope, and (a), (b), and (c) are the same as FIG. 1.

FIG. 3 is a photograph showing a metallographic structure by a scanning electron microscope in a state of a bent portion after a bending test, and (a), (b), and (c) are the same as FIG. 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Sai Sai 5-8-8 Tsunashima-higashi, Kohoku-ku, Yokohama-shi, Kanagawa Sannouchi Co., Ltd. (72) Inventor Shogo Inoue 1-9-13 Yokoyamadai, Sagamihara-shi, Kanagawa

Claims (3)

[Claims] 1. A corrosion resistance comprising a nickel-clad stainless steel base material, at least one kind of plating layer selected from noble metals, tin and tin alloys formed as at least partial plating on the base material. A contact material with excellent contact resistance, bendability, spring characteristics, and spreadability. 2. A noble metal, tin or tin alloy selected from noble metals, tin and tin alloys on a band-shaped nickel clad stainless steel substrate.
A method for producing a contact material having excellent corrosion resistance, contact resistance, ductility, and spring characteristics, which is characterized in that at least partial plating is performed on various types. 3. Corrosion resistance, contact resistance, bendability, characterized in that at least partial plating of one kind selected from precious metals, tin and tin alloys is performed on a press-molded nickel clad stainless steel substrate. , A method for producing a contact material having excellent spring characteristics.