JP2010180425A - Electrical contact and production method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a plated noble-metal film for an electrical contact or a plated Ni film to be used as the underlayer lowers a contact performance or the adhesiveness of the plated film when having a large amount of a brightener deposited on the surface of the plated film, though the films are required to be dense and have superior corrosion resistance. <P>SOLUTION: This production method includes reducing the amount of the brightener contained in the plated noble-metal film of Au and Ag of the electrical contact and the plated Ni film to be used as the underlayer of the films, in the surface of the film, compared to the inner part of the film. Thereby obtained plated film has the surface superior in the contact performance or the adhesiveness of the plated film, though being dense because of containing crystal grains with small grain sizes in the inner part, which constitute the plated film. The plated film containing different amounts of the brightener in the plated film is produced by controlling the current density on the surface of the substrate, for instance, by changing a distance between the anode and a substrate, through tilting the anode or curving the anode to change the shape. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrical contact in which a noble metal film is plated on the surface of a switch, a connector, or the like, and a manufacturing method thereof.

  Conventionally, surface uniformity such as plating has required uniformity of the formed film, which includes precious metal plating such as Au (gold) or Ag (silver) used for electrical contacts such as switches and connectors, and these The same was true for Ni (nickel) plating, which is the base of the plating.

  For example, in Patent Document 1 described below, the current density is made uniform by changing the shape of the electrode, and the alloy composition and coating properties in the plating film are made uniform. Further, in Patent Document 2 below, the electrodes are divided and controlled independently to suppress variations in current density, thereby achieving uniform plating adhesion.

Japanese Patent Laid-Open No. 62-188799 JP 63-293200 A

  By the way, in noble metal plating such as Au or Ag, or Ni base plating, a brightener is added to the plating bath. Conventionally, the plating film is uniformly formed as described above, and the additive is also contained almost uniformly in the entire plating film.

  By the way, if the brightening agent is contained in the entire plating film and the amount of the brightening agent deposited on the plating film surface is large, the contact performance is lowered or the adhesion with the plating layer formed thereon is deteriorated. There was a problem.

  Therefore, for example, there is a method of forming a plating film by multi-layer plating and performing a surface activation treatment each time each plating film is formed in order to prevent a large amount of brightener from being deposited on the surface of each plating film. However, in this method, the manufacturing process is complicated and the manufacturing cost is high, and the productivity is poor.

  On the other hand, when the brightening agent contained in the plating film is small in the entire plating film, the crystal grain size of the plating film increases as a whole, and a dense plating film cannot be obtained, resulting in a problem that the corrosion resistance is lowered.

  Therefore, the present invention solves the above-mentioned conventional problems, and in particular, an object of the present invention is to provide an electrical contact excellent in contact performance or adhesion on a plating surface and a manufacturing method thereof, while being a dense plating film. .

The present invention relates to an electrical contact having a noble metal film plated with Au or Ag.
The amount of brightener contained in the noble metal film is smaller on the film surface than on the inside of the noble metal film, and the particle diameter of the crystal grains constituting the noble metal film is on the inside of the film compared to the film surface. It is characterized by being smaller.
Thereby, it is possible to obtain a dense electrical contact having excellent corrosion resistance and excellent contact performance.

Alternatively, the present invention relates to an electrical contact having a plated Ni film and a noble metal film plated with Au or Ag on the surface of the Ni film.
The amount of brightener contained in the Ni film is smaller on the film surface than on the inside of the Ni film, and the particle diameter of the crystal grains constituting the Ni film is on the inside of the film compared to the film surface. It is characterized by being smaller.

  Thereby, it is possible to obtain a dense electrical contact having excellent corrosion resistance and excellent adhesion between the Ni film and the noble metal film.

Further, the present invention relates to a method for manufacturing an electrical contact having a noble metal film of Au or Ag.
When the noble metal film is plated by electrolytic plating in a plating bath to which a brightener is added, the current when the film surface is plated compared to the current density when the inside of the noble metal film is plated. The density is reduced, and the amount of the brightener contained in the noble metal film is reduced on the film surface as compared with the inside of the film.

Alternatively, the present invention provides a method for producing an electrical contact in which a Ni film and a noble metal film of Au or Ag are laminated and plated.
When the Ni film is formed by electroplating in a plating tank to which a brightening agent has been added, the current when the film surface is plated compared to the current density when the inside of the Ni film is formed by plating. Reducing the density and reducing the amount of brightener contained in the Ni film on the film surface compared to the inside of the film;
Plating the noble metal film on the surface of the Ni film;
It is characterized by having.

  In the present invention, the amount of brightener deposited on the inside and the surface of the plating film can be varied appropriately and simply by changing the current density. By adjusting the current density as described above, the amount of brightener deposited on the surface of the plating film can be reduced as compared with the inside of the film. In addition, since the amount of the brightening agent inside the film can be increased, the grain size of the crystal grains inside the film can be made smaller than that of the film surface, and densification can be achieved.

  In the present invention, it is preferable to change the current density by changing a distance between an anode provided in the plating tank and a region where the electrical contact is provided on the substrate surface which is a cathode.

  Alternatively, in the present invention, a mask plate having an aperture is disposed between the anode provided in the plating tank and the electrical contact formation region provided on the substrate surface as the cathode, and the aperture diameter is changed. It is preferable to change the current density.

Alternatively, in the present invention, a plurality of anodes are arranged in the plating tank, a rectifier is connected to each anode so that the current density can be individually adjusted, and the anode is opposed to a region where the electrical contact is provided on the substrate surface. It is preferable to change the current density by changing the anode.
As described above, the current density can be changed easily and appropriately.

  According to the electrical contact of the present invention, it is possible to obtain a dense electrical contact having excellent corrosion resistance and excellent contact performance or adhesion between plating films.

  Further, according to the method for producing an electrical contact of the present invention, the amount of brightener deposited on the surface of the plating film can be reduced appropriately and easily by adjusting the current density as compared with the inside of the film. In addition, since the amount of the brightening agent inside the film can be increased, the grain size of the crystal grains inside the film can be made smaller than that of the film surface, and densification can be achieved.

The fragmentary sectional view of the electrical contact of a 1st embodiment, The fragmentary sectional view of the electrical contact of 2nd Embodiment, A partial plan view of a substrate with a region for forming electrical contacts; Schematic showing the arrangement (first embodiment) of the anode in the plating tank, Schematic showing the arrangement (second embodiment) of the anode in the plating tank, Schematic which shows arrangement | positioning (3rd Embodiment) in the plating layer which has arrange | positioned the mask board, FIG. 6 is a plan view of the mask plate in FIG. Schematic which shows arrangement | positioning (4th Embodiment) of the anode in a plating tank,

  FIG. 1 is a partial cross-sectional view of the electrical contact of the first embodiment, and FIG. 2 is a partial cross-sectional view of the electrical contact of the second embodiment.

  In FIG. 1 and FIG. 2, the Z direction indicates the height direction (film thickness direction), and shows the plating films laminated from the bottom to the top.

  The electrical contact shown in FIG. 1 includes a noble metal film 33 of Au or Ag. The entire noble metal film 33 is in a crystalline state.

  The noble metal film 33 is formed by a film interior 33a having a large amount of brightener and a film surface 33b having a smaller amount of brightener than the film interior 33a.

If the amount of brightener contained in the plating is large, the crystal grains become finer. Therefore, the film interior 33a is a dense plating film with small crystal grains and is excellent in corrosion resistance. For example, the amount of the brightener contained in the film interior 33a is 0.01 to 1 (mg / cm ³ ).

On the other hand, if the amount of the brightener contained in the plating is small, the crystal grains become coarse, but the contact resistance is stabilized because the brightener that is an impurity such as an organic substance is small. Therefore, the contact resistance on the film surface 33b can be stabilized and the contact performance can be improved. The amount of the brightener contained in the film surface 33b is, for example, 0.0001 to 0.01 (mg / cm ³ ).

  As shown in FIG. 1, the noble metal film 33 has a larger formation range of the film interior 33a with a large amount of the brightener than the film surface 33b with a small amount of the brightener. When formed in this way, the noble metal film 33 is more excellent in corrosion resistance because of a large proportion of the dense film formed. However, since the film surface 33b with a small amount of brightener is formed, the contact resistance of the noble metal film 33 can be stabilized. For example, the film thickness of the film interior 33 a is preferably 50 to 99% of the entire film thickness of the noble metal film 33.

  Further, the film back surface of the noble metal film 33 shown in FIG. 1 is also adjusted so that the amount of the brightener is smaller than that of the film interior 33a and the crystal grain size is larger than that of the film interior 33b, similarly to the film surface 33b. May be. Thereby, both surfaces of the noble metal film 33 can be formed as contact surfaces.

  Note that the brightener contained in the noble metal film 33 shown in FIG. 1 contains, for example, selenium, antimony, or the like.

  The electrical contact of the embodiment shown in FIG. 2 has a configuration in which a noble metal film 33 of Au or Ag is formed on the surface of the plated Ni film 32 by plating.

  In the embodiment shown in FIG. 2, the Ni film 32 is formed of a film interior 32 a having a larger amount of brightener contained in plating and a film surface 32 b having a smaller amount of brightener contained in plating than the film interior 32 a.

When the amount of brightener contained in the plating is large, the Ni film 32 has fine crystal grains. Therefore, the film interior 32a is a dense plating film with small crystal grains and is excellent in corrosion resistance. For example, the amount of the brightener contained in the film interior 32a is 0.01 to 1 (mg / cm ³ ).

On the other hand, if the amount of the brightener contained in the plating is small, the crystal grains are coarsened. However, since the brightener that is an impurity such as an organic substance is small, the film surface 33b with a small amount of brightener can be used as Au or Excellent adhesion to Ag noble metal film 33. The amount of the brightener contained in the film surface 32b is, for example, 0.0001 to 0.01 (mg / cm ³ ).

  As shown in FIG. 2, in the Ni film 32, the formation range of the film interior 32a with a large amount of brightener is larger than the film surface 32b with a small amount of brightener. When formed in this manner, the Ni film 32 is more excellent in corrosion resistance because the Ni film 32 is formed with a dense film. However, since the film surface 32b with a small amount of brightener is formed, the adhesion with the noble metal film 33 of Au or Ag is excellent. For example, the film thickness of the film interior 32 a is preferably 50 to 99% of the entire film thickness of the Ni film 32.

  The change in the amount of brightener and the size of crystal grains contained in the film interiors 32a and 33a of the electrical contacts shown in FIGS. 1 and 2 is continuous or stepwise. For example, in the case of continuous change, the amount of brightener and the size of crystal grains in the film interiors 32a and 33a are substantially constant, and the amount of brightener and crystal grain size on the film surfaces 32b and 33b are continuously changed. The amount of the brightener and the crystal grain size at 32a and 33a are continuously changed, and the amount of the brightener and the crystal grain size at the film surfaces 32b and 33b are substantially constant. From the film interior 32a and 33a to the film surface 32b. , 33b, the amount of brightener and the size of crystal grains can be continuously changed. In the case of step change, in addition to the configuration in which the amount of the brightener and the size of the crystal grains in the film interiors 32a and 33a and the film surfaces 32b and 33b are substantially constant, for example, the gloss in the film interiors 32a and 33a. The amount of the agent and the size of the crystal grains can be changed in multiple stages.

  Further, the noble metal film 33 at the electrical contact shown in FIG. 2 is formed in the same configuration as the film surface 33b shown in FIG. 1, so that the adhesion and contact performance with the Ni film 32 can be more effectively improved. This is preferable. However, as in the case of the film interior 33a of FIG. 1, a dense film with small crystal grains is formed inside the noble metal film 33, thereby effectively improving the corrosion resistance of the noble metal film 33 as well as adhesion and contact performance. It becomes possible to make it.

  The brightener contained in the Ni film 32 in FIG. 2 is, for example, m-benzenesulfonic acid, butynediol, saccharin, or the like.

A method for manufacturing the electrical contact according to the first and second embodiments will be described.
First, a substrate (hoop material) 35 having a formation surface for electrolytic plating of electrical contacts is prepared. For example, a resist layer 36 is applied to the surface of the substrate 35, and a punching pattern is formed on the resist layer 36 in each electrical contact formation region 36 a. The hatched portion shown in FIG. 3 is the region of the resist layer 36 that remains. In FIG. 3, a large number of electrical contact formation regions 36a are arranged. In FIG. 3, the formation region 36a is circular, but the shape of the formation region 36a is variously changed according to the shape of the electrical contact to be manufactured.

  A brightening agent is contained in the plating bath for plating the noble metal film 33 shown in FIG. 1 and the Ni film 32 shown in FIG. 2 by electrolytic plating. In the present embodiment, the brightener contained in the noble metal film 33 shown in FIG. 1 and the Ni film 32 shown in FIG. 2 is changed between the inside of the film and the film surface by changing the current density.

When the noble metal film 33 of the electrical contact shown in FIG. 1 is formed by electroplating, the current density when the film surface 33b is formed as compared with the current density when the inside 33a of the noble metal film 33 is plated. Set to a smaller value. For example, the current density at the time of plating a film inner 33a and 15~100 (A / dm ^2), sets the current density at the time of plating the film surface 33b to 10 (A / dm ²⁾ or less.

  As a result, the amount of the brightener contained in the noble metal film 33 can be increased at the film interior 33a and decreased at the film surface 33b. As described above, since the amount of the brightening agent in the film interior 33a can be increased, the grain size of the crystal grains in the film interior 33a can be made smaller than that of the film surface 33b, and the density can be increased.

Next, a specific method for changing the current density will be described.
In the plating apparatus shown in FIG. 4, a substrate (hoop material) 35 disposed in the plating tank 51 is supported so as to be movable in the direction of the arrow in FIG.

  As shown in FIG. 4, the anodes 53 and 53 disposed in the plating layer 51 are on the fixed side, and the anodes 53 and 53 are disposed to be inclined with respect to the moving direction of the substrate 35.

  In the embodiment of FIG. 4, the substrate 35 is put into the plating bath from the left inlet of the plating tank 51 and discharged from the right outlet.

  A rectifier (not shown) is connected to the anode 53 to control the current. The moving speed of the substrate 35 is not particularly limited, but is preferably in the range of 1 to 10 (m / sec).

  As shown in FIG. 4, when the substrate 53 is moved in the direction of the arrow by disposing the anode 53, the distance between each formation region 36a provided on the substrate 35 and the anode 53 gradually increases. The current density acting on the formation region 36a decreases as the substrate 35 moves.

  Here, the plating bath composition (one example) when the noble metal film 33 shown in FIG. 1 is formed by plating with Ag, for example, is as follows.

Silver cyanide (AgCN) 100 (g / L)
Potassium cyanide (KCN) 100 (g / L)
Potassium carbonate (K ₂ CO ₃ ) 30 (g / L)
Brightener 2 (mg / L)

As the brightener, an organic compound containing antimony (Sb) is used. In addition, an inorganic material such as nickel (Ni) can be suitably used as a brightener. This plating bath contains 80 (g / L) Ag ⁺ ions. It is preferable to manage the plating bath so that the temperature of the solution is 35 to 40 ° C. and the pH is 11 to 13. Moreover, it is preferable to use a silver plate or a platinum plating titanium material as an anode.

  Alternatively, the plating bath composition (one example) when the Ni film 32 shown in FIG. 2 is formed by plating is as follows.

Nickel sulfate (NiSO ₄ ) 184.6 (g / L)
Nickel chloride (NiCl ₂ · 6H ₂ O) 36.6 (g / L)
Boric acid (H ₃ BO ₃ ) 45 (g / L)
Brightener 5 (g / L)

As the brightening agent, m-benzenesulfonic acid is used. As the brightener, organic brighteners such as butynediol and saccharin are preferably used. This plating bath contains 70 (g / L) Ni ²⁺ ions and 20 (g / L) Cl ⁻ ions. It is preferable to manage the plating bath so that the liquid temperature is in the range of 40 to 55 ° C. and the pH is in the range of 3.5 to 4.5. Moreover, it is preferable to use a nickel plate as an anode.

  In the present embodiment, the brightener contained in the Ag film (noble metal film 33) shown in FIG. 1 or the Ni film 32 shown in FIG. 2 can be used without changing the composition of the plating bath by using the plating apparatus shown in FIG. The amount can be increased at the film interiors 32a and 33a and decreased at the film surfaces 32b and 33b.

  In the form shown in FIG. 4, the inclination angle of the anode 53 is substantially constant with respect to the moving direction of the substrate 35, but the inclination angle of the anode 53 can be changed from the middle as shown in FIG.

  In FIG. 5, the inclination angle of the anode 53 with respect to the moving direction of the substrate 35 increases rapidly from the middle of the moving direction of the substrate 35 to the exit.

  In FIG. 5, the amount of the brightener contained in the noble metal film 33 of FIG. 1 and the film interiors 32a, 33a of the Ni film 32 formed in each forming region 36a can be made substantially constant (or the increase rate is very small). The film surfaces 32b and 33b can be reduced rapidly.

  In the embodiment shown in FIGS. 4 and 5, since the anode 53 is inclined with respect to the moving direction of the substrate 35, the noble metal film 33 shown in FIG. 1 and the Ni film shown in FIG. The amount of the brightener contained in 32 tends to change continuously. On the other hand, by arranging the anode 53 stepwise with respect to the moving direction of the substrate 35, the amount of the brightener can be changed stepwise.

  4 and 5 each include two anodes 53 and 53, and a substrate 35 serving as a cathode is interposed between the anodes 53 and 53, whereby electrical contacts are provided on both surfaces of the substrate 35. Plating can be formed. Of course, it is also possible to have only one anode 53 and to form an electrical contact on only one side of the substrate 35 by plating. The same applies to the embodiments shown in FIGS.

  Next, in the embodiment shown in FIG. 6, the anode 53 is arranged in parallel to the substrate 35, but a mask plate 54 having a plurality of openings 55 between the substrate 35 that is a cathode and the anode 53 is provided. It is arranged. For example, as shown in the plan view of FIG. 7, the mask plate 54 is provided with a plurality of apertures 55 having different aperture diameters along the moving direction of the substrate 35.

  As shown in FIG. 6, a mask plate 54 formed so that the aperture diameter of each aperture 55 gradually decreases from the entrance side to the exit side in the movement direction of the substrate 35 is used. 1, the current density with respect to each formation region 36 a of the electrical contacts formed on the surface of the substrate 35 gradually decreases with the movement of the substrate 35, so that each formation region 36 a is plated as shown in FIG. 1. It is possible to adjust the amount of the brightener on the noble metal film 33 or the Ni film 32 shown in FIG.

  In the embodiment shown in FIG. 8, the anode 53 is divided anodes 53 a to 53 f that are divided into a plurality along the moving direction of the substrate 35. The divided anodes 53a to 53f are connected to rectifiers 56a to 56f, respectively, to control the current, and the current density can be individually adjusted in each of the divided anodes 53a to 53f.

  As shown in FIG. 8, when the substrate 35 on the cathode side is moved in the direction of the arrow, the divided anodes 53a to 53f facing the contact electrode formation regions 36a change one after another. For this reason, with the movement of the substrate 35, the current density acting on each formation region 36a can be changed. In the present embodiment, the noble metal film 33 shown in FIG. 1 formed by plating in each formation region 36a is adjusted by adjusting the current density with the anodes facing each other successively in the moving direction of the substrate 35. It is possible to increase the amount of brightener in the film interiors 32a and 33a of the Ni film 32 shown in FIG. 2 and to reduce the amount of brightener on the film surfaces 32b and 33b.

  In the electrical contact manufacturing method shown in FIG. 2, after the Ni film 32 is formed by electroplating, it is moved to another plating tank, and a noble metal film 33 is formed on the surface of the Ni film 32 by electroplating. To do. At this time, it is preferable to form the noble metal film 33 by plating with the same structure as the film surface 33b shown in FIG. 1 because the adhesion and contact performance with the Ni film 32 can be improved more effectively. Therefore, in the plating tank in which the noble metal film 33 is formed by plating, it is preferable to reduce the current density and reduce the amount of the brightener contained in the noble metal film 33, for example, by separating the distance between the substrate and the anode. However, in the noble metal film 33 in FIG. 2, as in the film interior 33a in FIG. 1, in order to form a dense film with a small amount of crystal grains by increasing the amount of brightener, the current density is set at the time of plating inside the film. By increasing the thickness, it is possible to effectively improve the corrosion resistance of the noble metal film 33 as well as the adhesion and contact performance.

  The noble metal film 33 shown in FIG. 1 and the Ni film 32 shown in FIG. 2 can be manufactured by batch plating. In this case, for example, each plating tank for plating each of the film interior 33a and the film surface 33b of the noble metal film 33 shown in FIG. 1 is prepared, and the plating bath composition of each plating tank is made the same. Then, for example, using the configuration shown in FIG. 4, the distance between the substrate and the anode in the plating tank relative to the film interior 33a is set smaller than the distance between the substrate and the anode in the plating tank relative to the film surface 33b.

32 Ni film 33 Noble metal film 32a, 33a Film interior 32b, 33b Film surface 51 Plating tank 53 Anode 53a-53b Divided anode 54 Mask plate 55 Opening 56a-56f Rectifier

Claims (7)

In an electrical contact having a noble metal film plated with Au or Ag,
The amount of brightener contained in the noble metal film is smaller on the film surface than on the inside of the noble metal film, and the particle diameter of the crystal grains constituting the noble metal film is on the inside of the film compared to the film surface. An electrical contact characterized by being reduced in size. In an electrical contact having a plated Ni film and a noble metal film plated with Au or Ag on the surface of the Ni film,
The amount of brightener contained in the Ni film is smaller on the film surface than on the inside of the Ni film, and the particle diameter of the crystal grains constituting the Ni film is on the inside of the film compared to the film surface. An electrical contact characterized by being reduced in size. In a method for manufacturing an electrical contact having a noble metal film of Au or Ag,
When the noble metal film is plated by electrolytic plating in a plating bath to which a brightener is added, the current when the film surface is plated compared to the current density when the inside of the noble metal film is plated. A method for producing an electrical contact, wherein the density is reduced and the amount of brightener contained in the noble metal film is reduced on the film surface as compared with the inside of the film. In a method for manufacturing an electrical contact in which a Ni film and a noble metal film of Au or Ag are laminated and plated,
When the Ni film is formed by electroplating in a plating tank to which a brightening agent has been added, the current when the film surface is plated compared to the current density when the inside of the Ni film is formed by plating. Reducing the density and reducing the amount of brightener contained in the Ni film on the film surface compared to the inside of the film;
Plating the noble metal film on the surface of the Ni film;
A method for producing an electrical contact, comprising:   5. The electrical contact according to claim 3, wherein the current density is changed by changing a distance between an anode provided in the plating tank and a formation region of the electrical contact provided on a substrate surface which is a cathode. Manufacturing method.   A mask plate having an opening is disposed between the anode provided in the plating tank and the electric contact formation area provided on the substrate surface which is a cathode, and the current density is changed by changing the opening diameter. The method of manufacturing an electrical contact according to claim 3 or 4, wherein the electrical contact is changed.   A plurality of anodes are arranged in the plating tank, rectifiers are connected to the respective anodes so that the current density can be adjusted individually, and the anodes facing the electric contact formation regions provided on the substrate surface as the cathodes are changed. The method for manufacturing an electrical contact according to claim 3 or 4, wherein the current density is changed.

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