JP5184328B2 - Silver coating material for movable contact parts and manufacturing method thereof - Google Patents

Description

  The present invention relates to a silver coating material for movable contact parts and a method for producing the same, and more particularly to a silver coating material for movable contact parts suitable as a disc spring material for connectors, switches, terminals and electronic contact parts, and a method for producing the same.

Conventional push switches and multi-directional switches used in mobile phones and portable terminal devices, as well as remote control switches and composite printers, include phosphor bronze, beryllium copper, and recently copper alloys such as Corson copper alloys, stainless steel A material obtained by applying silver plating to a metal substrate having excellent spring properties such as an iron-based alloy has been used. In this method, after a nickel underlayer is formed on a metal substrate, a material in which silver surface plating is formed is used.
On the other hand, in recent years, due to the spread of e-mail functions of mobile phones, repeated switching operations have increased. By repeating switching in a short period of time, the switching part generates heat, and oxygen in the air permeates the silver plating. It has been found that the nickel is oxidized and the silver is easily peeled off.

In order to prevent this phenomenon, it has been proposed to use, for example, a silver / copper / nickel / stainless steel material in which a copper intermediate layer is provided between the silver layer and the nickel layer (see Patent Documents 1 to 4). The copper intermediate layer is said to have an effect of capturing oxygen that has passed through the silver plating and preventing the oxidation of nickel in the underlayer.
Patent Literature 1 discloses that Ni is plated on a substrate, 0.1 to 0.5 μm of copper is plated thereon, and silver is plated thereon.
In Patent Document 2, a 0.2 to 0.4 μm Ni underlayer is provided on a stainless steel substrate, a 0.2 to 0.6 μm copper plating intermediate layer is provided on the upper layer, and a silver layer is provided on the outermost layer. Is disclosed. The silver plating thickness is preferably 0.5 to 1.0 μm.
Patent Document 3 discloses that the copper plating thickness of the intermediate layer is 0.05 to 2.0 μm.
Patent Document 4 discloses that the total amount of copper contained in the coating layer (underlayer, intermediate layer, outermost layer) is limited.
Further, as disclosed in Patent Document 5, it is disclosed that two types of alloy layers containing copper are formed between the base and the outermost layer instead of the copper intermediate layer.

Japanese Patent No. 3889718 Japanese Patent No. 3772240 JP 2005-133169 A JP 2007-291509 A JP 2007-291510 A

  However, when the electrical contact materials described in Patent Documents 1 to 3 have been studied, copper forming the intermediate layer diffuses in silver or a silver alloy and appears on the outermost layer, which is oxidized to reduce contact resistance. It became clear that it might be high. The cause of this is considered to be that oxygen passing through the intermediate layer cannot be sufficiently trapped and an oxide film is formed on the outermost layer.

  On the other hand, as a recent problem, there is a problem of salt water corrosion resistance. This is because when it is incorporated into a mobile phone as a push switch, it is in a sealed state called a tact sheet and the corrosion resistance from the outside air is relatively maintained, but the corrosion resistance when pressing coiled material and incorporating it into the sheet Has been regarded as a problem. Especially in silver, the problem of discoloration due to sulfidation tends to be addressed, but corrosion resistance due to human sweat and salt contained in press oil is also gaining importance, and conventional products only addressed the problem of sulfidation resistance. The salt water corrosion resistance tends to be overlooked, and it has been found that the contact materials actually formed by the methods described in Patent Documents 1 to 5 have insufficient corrosion resistance. Further, even in a cellular phone processed into a tact sheet shape, there is a problem that sweat permeates into the sheet due to deterioration of the wear of the resin, causing corrosion and causing poor conduction.

  Furthermore, silver deposits adhere to the mold part during pressing, contaminating the mold, and there are problems in workability. This is because silver, which is a relatively soft metal, is formed on the outermost layer, which causes adhesion wear and sliding wear with the mold during pressing and deposits on the mold. For this reason, it is necessary to perform maintenance of the mold every tens of thousands of shots, and there is a large time loss at the time of manufacturing the contact member. In recent years, miniaturization of mobile phones has been rapidly progressing, and accordingly, the press pitch, the bending radius, and the like have been reduced year by year, and plating cracks have occurred in these processes. Starting from this crack, problems such as corrosion progressing to the contact point due to salt water and pollutants in the atmosphere, causing contact failure, etc. have been observed, and these improvements are urgently needed, but patents It is difficult to solve this problem only with the techniques described in Documents 1 to 5.

  Therefore, the present inventors have good corrosion resistance even in an environment where the surface silver layer does not peel off and is affected by sweat or salt even when used in an environment where switching is repeated, Sincerity studies were conducted with the aim of providing a silver coating material for movable contact parts and a method for producing the same. In addition, reduction of silver deposits during pressing and improvement of the pressability and bending workability of the contact member were also investigated, and the arithmetic average roughness Ra of the metal substrate surface and the arithmetic average roughness Ra of the intermediate layer surface were determined. The inventors have found out that it is very important to appropriately control and make the coating thickness of each layer in an appropriate range, and have arrived at the invention.

Therefore, the present invention provides the following solutions.
(1) A base layer made of either nickel, nickel alloy, cobalt, or cobalt alloy is coated on a metal substrate formed of copper or copper alloy, or iron or iron alloy, and copper is coated on the base layer. Alternatively, a silver coating material for movable contact parts on the premise that the intermediate layer made of a copper alloy is coated, and the outermost layer made of silver or a silver alloy is formed on the intermediate layer, on the premise of processing to be at least partially convex. The arithmetic average roughness Ra of the surface of the metal substrate is 0
. A 001～0.2Myuemu, and said at a later stage intermediate layer coating formed thereon
An arithmetic average roughness Ra of the surface of the intermediate layer is 0.001 to 0.1 μm.
(2) The thickness of the underlayer is 0.005 to 0.1 μm,
) Silver coating material for movable contact parts as described.
(3) The thickness of the intermediate layer is 0.01 to 0.2 μm, (1)
Or the silver coating material for movable contact components as described in said (2).
(4) The copper or copper alloy of the intermediate layer is at least one selected from the group consisting of copper, copper-gold alloy, copper-silver alloy, copper-tin alloy, copper-nickel alloy, and copper-indium alloy. The silver coating material for movable contact parts according to any one of (1) to (3), wherein
(5) The movable contact component according to any one of (1) to (4), wherein the outermost layer made of silver or a silver alloy is formed with a thickness of 0.2 to 1.5 μm. Silver coating material.
(6) The outermost layer silver or silver alloy is selected from the group consisting of silver, silver-tin alloy, silver-copper alloy, silver-antimony alloy, silver-selenium alloy, silver-palladium alloy, and silver-indium alloy. The silver coating material for movable contact parts according to any one of (1) to (5), wherein the silver coating material is at least one kind.
(7) wherein (1) A method for producing a variable dynamic contact component for the silver-coated material according to any of - (6), the arithmetic average roughness Ra of the surface of 0.001~0.2μm copper Or copper alloy, or
After coating a base layer made of either nickel or a nickel alloy or cobalt or a cobalt alloy on a metal substrate made of iron or an iron alloy, an intermediate layer made of copper or a copper alloy is coated to coat the intermediate layer. A method for producing a silver coating material for movable contact parts, wherein the arithmetic average roughness Ra of the surface is set to 0.001 to 0.1 μm, and then the outermost layer made of silver or a silver alloy is coated.
(8) One or more of the underlayer, the intermediate layer, and the outermost layer are formed by a plating method. The method for producing a silver coating material for a movable contact part according to (7),
(9) The method for producing a silver coating material for movable contact parts according to (8) above, wherein the plating bath component for coating the intermediate layer contains copper sulfate as a main component.

In the present invention, the arithmetic average roughness Ra of the metal substrate is 0.001 to 0.2 μm, and the arithmetic average roughness Ra of the intermediate layer is 0.001 to 0.1 μm, so that the intermediate layer is a silver layer. By reducing the surface area in contact with the surface layer as much as possible and reducing the number of paths through which the intermediate layer diffuses into the outermost layer of the silver layer, it has the effect of preventing an increase in contact resistance and at the same time promotes moderate diffusion for oxygen scavenging effective. For this reason, oxygen diffused by heat generated during repeated switching such as a push switch that pushes a portion processed into a convex shape can be sufficiently captured, and a contact material with low contact resistance and stable can be obtained.
In addition, by reducing the height difference between the peaks and valleys of the unevenness on the surface of the intermediate layer, it is possible to reduce the portion of the sloped surface of the unevenness where the outermost surface layer formed on the intermediate layer becomes thin, and particularly the salinity. Corrosion resistance under the influence of the environment is improved. As a result, even if it is used in an environment where switching is repeated, the silver layer on the surface does not peel off and the corrosion resistance is good even in an environment affected by sweat, salt, etc. A covering material can be provided. At the same time, since the unevenness on the surface of the outermost layer is reduced, the bending cracking property between the unevennesses is improved, the crack progress during pressing and bending is reduced, and the corrosion resistance is improved.
Further, by reducing the unevenness on the surface of the intermediate layer, it is not necessary to provide the outermost silver layer as thick as the conventional product, so that the outermost silver can be made thinner than the conventional product. For this reason, even if the lower limit of the thickness of the outermost layer is set to 0.2 μm, the quality is hardly deteriorated and the product cost can be suppressed. Furthermore, by reducing the unevenness of the metal substrate surface and the intermediate layer surface, the stress associated with the press process in the feed process and press process during pressing is reduced, the wear is greatly reduced, and the silver generated during pressing is reduced. Since the absolute amount of deposit is reduced, mold wear and maintenance frequency are greatly reduced, so that problems during pressing can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 are cross-sectional views showing an embodiment of the silver coating material for movable contact parts of the present invention. Specifically, FIG. 1 is a schematic diagram, and FIG. 2 is an explanatory diagram of the surface roughness of each layer. 1 and 2, 1 is a metal substrate, 2 is an underlayer, 3 is an intermediate layer, and 4 is an outermost layer. In FIG. 2, the boundary on the surface side of the outermost layer 4 is omitted.

The metal substrate 1 is a material having conductivity, spring characteristics, durability, etc. sufficient for use as a movable contact part, and in the present invention, it is made of copper or copper alloy, iron or iron alloy.
Examples of the copper alloy preferably used as the substrate 1 include bronze, phosphor bronze, brass, titanium copper, copper nickel silicon (Corson type) alloy, and beryllium copper. Examples of iron alloys that are preferably used include stainless steel (SUS) and 42 alloy. The thickness of the substrate 1 is preferably 0.03 to 0.5 mm, and more preferably 0.05 to 0.2 mm, on the premise of processing that is at least partially convex.

  The arithmetic average roughness Ra of the surface of the metal substrate 1 is 0.001 to 0.2 μm, more preferably 0.001 to 0.1 μm. The Ra lower limit value on the surface of the metal substrate is influenced by the roughness of the material rolling roll and is set to be practically 0.001 μm or more. Further, in the Ra upper limit value, as will be described later, the underlayer and the intermediate layer covered by the upper layer may be controlled to have thicknesses of 0.005 to 0.1 μm and 0.01 to 0.2 μm, respectively. Since it is desired, even if the thickness of each layer is within the above range, a limit value that can smooth the unevenness on the surface of the intermediate layer is set. When plating is applied to a substrate having an Ra greater than this upper limit, the height difference due to the unevenness of the substrate surface is further enlarged during formation of the underlayer and the intermediate layer, and the surface of the intermediate layer cannot be sufficiently smoothed. It tends to lead to deterioration of corrosion resistance and increase of contact resistance value. For this reason, the metal substrate adapted in the present invention needs to adjust the arithmetic average roughness Ra of the rolling roll within the above range, considering that Ra is determined by the transfer of the rolling roll.

  On the surface of the substrate 1, nickel (Ni) or Ni alloy having a thickness of 0.005 to 0.1 μm, preferably 0.01 to 0.06 μm, more preferably 0.01 to 0.04 μm, or cobalt (Co ) Or a base layer 2 made of a Co alloy. The lower limit of the thickness of the underlayer 2 is determined from the viewpoint of the adhesion between the substrate 1 and the intermediate layer 3, and the upper limit of the thickness of the underlayer 2 is determined when the electrical contact material is formed from the coating material by pressing or the like. However, it is determined from the viewpoint of preventing the workability from being deteriorated and the occurrence of cracks in the underlayer 2 or the like.

  Ni alloy and Co alloy used for the underlayer 2 include Ni—P (phosphorus), Ni—Sn (tin), Ni—Co, Ni—Co—P, Ni—Cu, and Ni—Cr. (Chromium), Ni—Zn (Zinc), Ni—Fe (Iron), Co—P, Co—Sn, Co—Cu, Co—Cr, Co—Zn, Co—Fe An alloy such as is preferably used. Ni, Ni alloy, Co, and Co alloy are preferable because they have good plating processability, are relatively inexpensive in price, and have a high melting point, so that the barrier function does not deteriorate even in a high temperature environment. Used.

  On the underlayer 2, an intermediate layer 3 made of copper (Cu) or a Cu alloy and having a thickness of 0.01 to 0.2 μm, preferably 0.05 to 0.15 μm is coated. The lower limit of the thickness of the intermediate layer 3 is determined from the viewpoint of preventing oxidation of the components of the underlayer 2, and the effect is insufficient when the thickness is less than 0.01 μm. Further, the upper limit of the thickness of the intermediate layer 3 is that workability is lowered when an electrical contact material is formed from a coating material by press working or the like, and the intermediate layer 3 and the underlayer 2 are not cracked. Determined from the viewpoint of preventing the possibility that the layer 3 diffuses into the outermost layer and raises the contact resistance. When the thickness exceeds 0.2 μm, Cu reaches the outermost layer by repeated switching operation and oxidizes to raise the contact resistance. become.

  Examples of the copper (Cu) or Cu alloy used for the intermediate layer 3 include Cu, Cu—Au (gold), Cu—Ag (silver), Cu—Sn, Cu—Ni, or Cu—In (indium). ) System. In particular, in the Cu alloy system, it becomes difficult to diffuse by alloying, so that it is difficult to increase contact resistance due to oxidation appearing on the outermost layer 4 of the silver or silver alloy layer.

  The arithmetic average roughness Ra of the surface of the intermediate layer 3 is preferably controlled to 0.001 to 0.1 μm, more preferably 0.001 to 0.07 μm. The Ra lower limit value on the surface of the intermediate layer 3 is set because it is practically 0.001 μm or more assuming that the coating forming method is a plating method. Further, the Ra upper limit value on the surface of the intermediate layer 3 is a contact area with the silver or silver alloy layer of the outermost layer 4 that is coated on the intermediate layer 3 without lowering the adhesion between the intermediate layer 3 and the outermost layer 4. Is set for the purpose of reducing as much as possible. When the outermost layer 4 is subjected to silver plating on the intermediate layer 3 having a Ra larger than the upper limit value of the intermediate layer 3, the contact area between the intermediate layer 3 and the outermost layer 4, that is, diffusion due to the height difference due to the irregularities on the surface of the intermediate layer 3 Since the area that affects the degree of progress increases, the components of the intermediate layer 3 are likely to diffuse into the outermost layer 4 due to repeated switching operations and the like, and as a result, the salt water corrosion resistance is deteriorated and the contact resistance value is likely to increase. Become. Further, when Ra on the surface of the intermediate layer 3 is larger than the upper limit value, processing stress is concentrated in the concave portion during pressing or bending, and the crack tends to develop in the underlayer 2 to cause cracking, resulting in deterioration of corrosion resistance. There is a fear.

As a method for controlling the arithmetic average roughness Ra in the intermediate layer 3, it can be adjusted by appropriately selecting the plating current density when forming the coating film of the intermediate layer 3 and the type of additive contained in the plating solution. . For example, in the case of copper plating, the arithmetic average roughness of the surface of the intermediate layer 3 can be controlled within a range of 0.001 to 0.1 μm by applying the copper sulfate plating bath under conditions of 1 to 10 A / dm ^2. . The other plating solutions for forming the intermediate layer 3 can be controlled by the same method.

  On the intermediate layer 3, an outermost layer 4 made of silver (Ag) or a silver alloy is formed. The outermost layer 4 made of silver (Ag) or a silver alloy is a layer provided to improve conductivity as a contact member. Regarding the thickness, in the case of this embodiment, the Ag thickness can be made thinner than the conventional product. This is because the increase in contact resistance and corrosion resistance could not satisfy the required characteristics unless the outermost layer 4 was thick, but in the present invention, the increase in contact resistance and the decrease in corrosion resistance due to diffusion of the intermediate layer are greatly suppressed. Therefore, the effect as a sufficient contact characteristic is expected with 0.2 to 1.5 μm, more preferably 0.5 to 1.0 μm.

Examples of Ag or Ag alloy that can be preferably used as the outermost layer 4 include Ag, Ag—Sn alloy, Ag—Cu alloy, Ag—Sb alloy, Ag—Se alloy, Ag—Pd alloy, and Ag—In alloy. It has good contact characteristics and is preferably used.
When the outermost layer 4 is formed, a method of forming a thickening layer after providing a strike layer on the upper layer of the intermediate layer 3 for improving adhesion is also possible. In this case, the thickness of the outermost layer 4 is such that the total thickness of the strike layer and the thickening layer is within the above range.

  The silver coating material for a movable contact part of the embodiment shown in FIG. 1 is a bottom made of nickel or a nickel alloy, or cobalt or a cobalt alloy, for example, by pre-treating the metal substrate 1 by electrolytic degreasing and pickling. It can form suitably by coat | covering the intermediate | middle layer 3 which consists of copper or a copper alloy, and coat | covers the outermost layer 4 which consists of silver or a silver alloy after coat | covering the base layer 2. FIG.

  The underlayer 2, the intermediate layer 3 and the outermost layer 4 of the silver coating material for movable contact parts can be coated and formed by a plating method, a PVD method or the like, but any one or more layers are formed by a wet plating method. It is desirable to be simple and low cost.

  When a wet plating method is used as a method for forming the intermediate layer 3, a plating bath for forming the copper or copper alloy preferably uses copper sulfate as a main component. This is because the intermediate layer 3 formed by copper sulfate plating diffuses into the outermost layer 4 more than the intermediate layer 3 formed from a conventional copper cyanide bath or copper pyrophosphate bath known as strike plating or base plating bath. It is because the speed to perform can be suppressed. As a result, the corrosion resistance and contact resistance increase can be further suppressed, and a contact material having excellent characteristics can be obtained.

  The silver coating material for movable contact parts of the present invention can be suitably used as a disc spring material for connectors, switches, terminals and electronic contact materials, for example. In particular, it is suitable for a tact switch used in a mobile phone, and can provide a contact material that can sufficiently satisfy characteristics even in keystroke tests of hundreds of thousands to millions of times.

  Next, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.

<Example 1>
After pretreatment of strips of JIS standard C5210 (phosphor bronze) with a thickness of 0.1 mm and a width of 180 mm in the order of degreasing and pickling, an underlayer, an intermediate layer, and an outermost layer are formed in a plating bath having the following composition. The silver coating materials shown in the invention examples and comparative examples having the layer constitution shown in Table 1 were obtained.

(Pretreatment conditions)
[Electrolytic degreasing]
Degreasing liquid: NaOH 60 g / liter Degreasing conditions: Current density 2.5 A / dm ² , temperature 60 ° C., degreasing time 60 seconds [pickling]
Pickling solution: H ₂ SO ₄ 10% by weight Solution pickling conditions: room temperature immersion, immersion time 30 seconds

(Underlayer plating conditions)
[Ni plating]
Plating solution: HCl 120 g / liter, NiCl ₂ 30 g / liter Plating condition: current density 1.5 A / dm ² , temperature 30 ° C.
[Co plating]
Plating solution: HCl 120 g / liter, CoCl ₂ 30 g / liter Plating condition: current density 1.5 A / dm ² , temperature 30 ° C.

(Interlayer plating conditions)
[Cu plating]
Plating solution: CuSO ₄ .5H ₂ O 250 g / liter, H ₂ SO ₄ 50 g / liter, NaCl 0.1 g / liter Plating condition: current density 1 to 10 A / dm ² , temperature 40 ° C.
[Cu-Sn plating]
Plating solution: Na ₂ SnO ₃ 3H ₂ O 100 g / liter, CuCN ₂ 12 g / liter, NaCN 30 g / liter, NaOH 10 g / liter Plating condition: current density 3 A / dm ² , temperature 65 ° C.
[Cu-Ag plating]
Plating solution: AgCN 2 g / liter, Cu metal salt 90 g / liter, KCN 2 g / liter, KCO ₃ 18 g / liter
Plating conditions: current density 0.5 A / dm ² , temperature 50 ° C.

(Outermost layer plating conditions)
[Ag strike plating]
Plating solution: AgCN 5 g / liter, KCN 60 g / liter, K ₂ CO ₃ 30 g / liter Plating condition: current density 2 A / dm ² , temperature 30 ° C.
[Ag plating]
Plating solution: AgCN 50 g / liter, KCN 100 g / liter, K ₂ CO ₃ 30 g / liter Plating condition: current density 3 A / dm ² , temperature 30 ° C.
[Ag-Sn plating]
Plating solution: AgCN 5 g / liter, NaCN 50 g / liter, NaOH 50 g / liter, K ₂ SnO ₃ .3H ₂ O 80 g / liter Plating condition: current density 1 A / dm ² , temperature 30 ° C.
[Ag-Se plating]
Plating solution: AgCN 50 g / liter, KCN 100 g / liter, K ₂ CO ₃ 30 g / liter, K ₂ SeO ₃ 30 g / liter Plating condition: current density 1 A / dm ² , temperature 30 ° C.
[Glossy Ag plating]
Plating solution: AgCN 5 g / liter, KCN 100 g / liter, K ₂ CO ₃ 30 g / liter, NaS ₂ O _{3 3} g / liter Plating condition: current density 1 A / dm ² , temperature 30 ° C.

  Next, the silver coating materials of the examples and comparative examples shown in Table 1 were evaluated for the following evaluation items. The results are shown in Table 2.

(Peel test)
Each silver coating material was cut into 50 mm × 100 mm, and then a peel test after heating at 400 ° C. for 5 to 15 minutes was performed to examine contact resistance measurement and plating adhesion. The peel test was performed based on a tape test method defined in JIS H8504.
(Contact resistance measurement)
After each silver coating material was cut into 50 mm × 50 mm, the contact resistance was measured at the initial stage and after atmospheric heating using a four-terminal method.
Measurement conditions: The resistance value at the time of 10 mA energization was measured 10 times under the conditions of Ag probe R = 2 mm and load 0.1 N, and the average value was calculated.
(Adhesion evaluation)
After the test piece after heating at 400 ° C. for 15 minutes was cut into 10 mm × 30 mm, a cross cut of 2 mm square was performed with a cutter, and then a peeling test was performed using # 631S tape manufactured by Teraoka Seisakusho.
(Corrosion resistance test)
The appearance after 24 hours of the salt spray test was visually observed, and evaluated according to a standard chart of rating number (RN) by the corrosion resistance evaluation method defined in JIS H8502. The rating number is an evaluation of 0 to 10 levels, and a larger number suggests that the corrosion resistance is better.
Salt spray test conditions: NaCl was contained at 5 ± 1% by mass, sprayed for 24 hours under the conditions of a temperature of 35 ± 5 ° C. and a pH of 6.5 to 7.2.
(Pressability alternative test)
Furthermore, for pressability alternative evaluation, the top after the W-bending test was observed, and the presence or absence of a microscope (Keyence) crack was confirmed. After the test piece was cut into 10 mm × 30 mm, evaluation was performed by pressing with a load of 500 kg and a bending radius R = 0.1 mm.

  From Table 2, it can be seen that the product of the present invention is very good in all the items of heat resistance, adhesion, salt water corrosion resistance and pressability. In one comparative example, it can be seen that when Ra after forming the metal substrate and the intermediate layer is large, the corrosion resistance and the contact resistance value are increased, and the pressability is further decreased. Further, it can be seen that when the coating thickness limit is exceeded, problems such as deterioration in corrosion resistance and pressability, and decrease in adhesion occur.

<Example 2>
In a strip made of SUS301, SUS304, SUS403, or SUS430 (all JIS standard stainless steel) having a thickness of 0.05 mm and a width of 200 mm, after performing electrolytic degreasing as a pretreatment, underlayer plating, intermediate layer plating, outermost layer plating A silver coating material having a layer structure shown in Table 3 was obtained. In addition, outermost layer plating performed Ag strike plating 0.1 micrometer, Then, outermost layer Ag plating was implemented to predetermined thickness.

(Pretreatment conditions)
[Electrolytic degreasing]
Degreasing solution: NaOH 60 g / liter Degreasing conditions: 2.5 A / dm ² , temperature 60 ° C., degreasing time 60 seconds

(Underlayer plating conditions)
[Ni plating]
Plating solution: HCl 120 g / liter, NiCl ₂ 30 g / liter Plating condition: current density 1.5 A / dm ² , temperature 30 ° C.

(Interlayer plating conditions)
[Cu plating (1)]
Plating solution: CuSO ₄ .5H ₂ O 250 g / liter, H ₂ SO ₄ 50 g / liter, NaCl 0.1 g / liter Plating condition: current density 1 to 10 A / dm ² , temperature 40 ° C.
[Cu plating (2)]
Plating solution: Cu ₂ P ₂ O ₇ · 3H ₂ O 60 g / liter, K ₄ P ₂ O ₇ 100 g / liter, KNO ₃ 2 g / liter Plating condition: current density 1.0 A / dm ² , temperature 30 ° C.
[Cu plating (3)]
Plating solution: Cu (CN) ₂ 75 g / liter, NaCN 100 g / liter, NaCO ₃ 15 g / liter, NaOH 15 g / liter Plating condition: current density 5 A / dm ² , temperature 60 ° C.

(Outermost layer plating conditions)
[Ag strike plating]
Plating solution: AgCN 5 g / liter, KCN 60 g / liter, K ₂ CO ₃ 30 g / liter Plating condition: current density 2 A / dm ² , temperature 30 ° C.
[Ag plating]
Plating solution: AgCN 50 g / liter, KCN 100 g / liter, K ₂ CO ₃ 30 g / liter Plating condition: current density 3 A / dm ² , temperature 30 ° C.

  Next, each of the silver coating materials of Examples and Comparative Examples shown in Table 3 was cut to 50 mm × 100 mm, and contact resistance measurement after heating at 400 ° C. for 5 to 15 minutes was performed. The conditions for contact resistance measurement were the same as in Example 1. The evaluation results are shown in Table 4.

  As shown in Table 4, in Comparative Examples 9 to 12, it can be seen that the contact resistance increases after atmospheric heating, and the characteristics as the contact material are insufficient. On the other hand, all of Examples 31-34 showed excellent heat resistance, with the contact resistance being stable and almost unchanged from the initial value even after 15 minutes.

  Thus, the silver coating material for movable contact parts of the present invention is (1) extremely stable in heat-resistant adhesion and contact resistance characteristics even under severe conditions of atmospheric heating at a temperature of 400 ° C. for 15 minutes, (2 ) Good salt water corrosion resistance, (3) By forming an intermediate plating that suppresses diffusion to the outermost layer, corrosion resistance and contact resistance characteristics can be stabilized, and can be used as a long-life contact material I understand that.

It is a schematic diagram of the longitudinal cross-section which shows the embodiment of this invention. It is explanatory drawing which shows an example of the longitudinal cross-section which shows the embodiment of this invention.

Explanation of symbols

1 Metal substrate 2 Underlayer 3 Intermediate layer 4 Outermost layer

Claims (9)

An underlayer made of either nickel, nickel alloy, cobalt, or cobalt alloy is coated on a metal substrate formed of copper or copper alloy, or iron or iron alloy, and copper or copper alloy is formed on the underlayer. A silver coating material for movable contact parts on the premise of processing to be at least partially convex, in which an intermediate layer made of is coated, and an outermost layer made of silver or a silver alloy is formed on the intermediate layer. ,
The arithmetic average roughness Ra of the surface of the metal substrate is 0.001 to 0.2 μm, and the arithmetic average roughness Ra of the surface of the intermediate layer at the stage after coating the intermediate layer formed thereon is 0.0
A silver coating material for movable contact parts, characterized by having a thickness of 01 to 0.1 μm. The silver coating material for a movable contact part according to claim 1, wherein the thickness of the underlayer is 0.005 to 0.1 µm. The silver coating material for movable contact parts according to claim 1 or 2, wherein the intermediate layer has a thickness of 0.01 to 0.2 µm. The copper or copper alloy of the intermediate layer is at least one selected from the group consisting of copper, copper-gold alloy, copper-silver alloy, copper-tin alloy, copper-nickel alloy, and copper-indium alloy. The silver covering material for movable contact parts given in any 1 paragraph of Claims 1-3. The outermost layer made of silver or a silver alloy is formed with a thickness of 0.2 to 1.5 µm, The silver for movable contact parts according to any one of claims 1 to 4, Coating material. The outermost layer silver or silver alloy is at least one selected from the group consisting of silver, silver-tin alloy, silver-copper alloy, silver-antimony alloy, silver-selenium alloy, silver-palladium alloy, and silver-indium alloy. The silver coating material for a movable contact part according to any one of claims 1 to 5, wherein the silver coating material is a movable contact part. A method of manufacturing a variable dynamic contact component for the silver-coated material according to any one of claims 1 to 6,
Copper or copper alloy having a surface arithmetic average roughness Ra of 0.001 to 0.2 μm , or iron or
The surface of the intermediate layer is formed by coating a base layer made of either nickel or nickel alloy or cobalt or cobalt alloy on a metal base made of iron alloy, and then coating an intermediate layer made of copper or copper alloy. A method for producing a silver coating material for movable contact parts, wherein the outermost layer made of silver or a silver alloy is coated after the arithmetic average roughness Ra of 0.001 to 0.1 μm. The method for producing a silver coating material for a movable contact part according to claim 7, wherein at least one of the underlayer, the intermediate layer, and the outermost layer is formed by a plating method. The plating bath component when coating the intermediate layer is characterized by comprising copper sulfate as a main component,
The manufacturing method of the silver coating material for movable contact components of Claim 8.

Images