JPH07173690A - Plating method - Google Patents

Abstract

PURPOSE:To provide a barrel plating method capable of surely forming plating films having a uniform thickness on objects to be plated by suppressing the deposition of plating films on cathode electrodes and catalyst medium. CONSTITUTION:The cathode electrodes and catalyst medium consisting of a metallic material on which the metal to be plated is hardly depositable in a plating stage are used as the cathode electrodes 2 and the catalyst medium 4 in the case of application of specific plating on the objects 3 to be plated by immersing the objects 3 to be plated in a plating liquid 7 and supplying current between the cathode electrodes 2 and anode electrodes 5 while continuously or intermittently conducting the objects 3 to be plated to the cathode electrodes 2. An aluminum or an aluminum alloy is used for the metallic material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating method,
More specifically, the present invention relates to an electrolytic plating method in which an object to be plated such as an electronic component is immersed in a plating solution and a plating film is deposited on the object to be plated while energized.

[0002]

2. Description of the Related Art Barrel plating is one of the plating methods used for plating an object to be plated such as electronic parts. FIG. 3 is a diagram showing an example of this conventional barrel plating method.

In this plating method, at least a part is made of a material such as a wire mesh that allows a plating solution to pass therethrough, and inside a barrel 21 in which a cathode electrode 22 made of copper is arranged,
A large number of objects to be plated 23 such as electronic parts (for example, laminated ceramic capacitors), objects to be plated 23 and cathode electrodes 22
After containing a contact medium 24 (for example, a small sphere made of copper) which conducts electricity, the barrel 21 is placed in a plating solution 27 in a plating tank 26.
The barrel 21 is rotated in the plating solution 27 while being energized between the cathode electrode 22 and the anode electrode 25 arranged in the plating tank 26, and the object to be plated 23 is placed on the cathode electrode 22 and the contact medium 24. And a method of performing plating by contacting with the plating solution 27.

In the above plating method, the object to be plated 23 is small, and it is difficult to contact the object to be plated 23 and the cathode electrode 22 efficiently as it is. With the object to be plated 23
The contact medium 24 for electrically connecting the cathode electrode 22 to the barrel 21
In this way, the contact medium 24 is placed in the barrel 2
By putting it in 1, it becomes possible to surely conduct the portion to be plated of the object to be plated 23 (for example, the external electrode of the multilayer ceramic capacitor) 23a and the cathode electrode 22 through the contact medium 24, and to be plated. It is possible to deposit a plating film having a uniform thickness on a predetermined portion (external electrode) 23a of the object 23.

The object to be plated is not so small,
If sufficient contact can be obtained with the cathode electrode, it is also possible to carry out plating without using a contact medium.

[0006]

However, in the above-described conventional plating method, the cathode electrode 22 and the contact medium 24 made of copper are used, and in the plating step, the surface thereof is plated in the same manner as the object 23 to be plated. A film is deposited. In the case where the current is not concentrated on the cathode electrode 22 and the contact medium 24, a plating film thicker than the plating film formed on the object to be plated 23 is formed on the surface thereof. There is.

Further, in one plating step, the cathode electrode 2
2 and the contact medium 24, even if a thick plated film is not formed, the plated film becomes thicker and the shape of the cathode electrode 22 and the contact medium 24 changes during repeated use, and the plated object 23 and The contact condition of the
There is a problem in that the current distribution in the plating solution 27 becomes non-uniform among lots, leading to variations in the plating thickness of products.

This problem is not limited to the case where the cathode electrode or the contact medium made of copper is used as described above, but is applicable to the case where the cathode electrode or the contact medium made of stainless steel or nickel is used. It is a thing.

Therefore, in order to solve such problems, periodical maintenance and contact medium replacement are carried out, but frequent maintenance is required to process a large number of product lots, and plating is required. There is a problem that the operating rate of the processing equipment deteriorates.

The present invention solves the above-mentioned problems, and suppresses the deposition of the plating film on the cathode electrode or the contact medium, and reliably forms the plating film of uniform thickness on the object to be plated. It is an object of the present invention to provide a plating method capable of

[0011]

In order to achieve the above object, the plating method of the present invention comprises immersing an object to be plated in a plating solution and contacting the object to be plated with a cathode electrode continuously or intermittently. However, in the plating method in which a predetermined plating film is deposited on the object to be plated by applying electricity between the cathode electrode and the anode electrode, the metal to be plated in the plating step is deposited on the surface as the cathode electrode. It is characterized by using a cathode electrode made of a difficult metal material.

[0012] Further, the object to be plated is placed in a barrel having a cathode electrode inside and immersed in a plating solution, and the barrel is energized between the anode electrode and the cathode electrode provided in the plating solution. It is characterized in that a predetermined plating film is deposited on the object to be plated by rotating.

Further, the barrel is provided with a material to be plated and a contact medium for electrically connecting the material to be plated and the cathode electrode, which is made of a metal material in which a metal to be plated in the plating step is less likely to deposit. To do.

Further, the metal material is aluminum or an aluminum alloy.

[0015]

According to the plating method of the present invention, the cathode electrode (and the contact medium for bringing the object to be plated and the cathode electrode into conduction) is made of a metal material in which the metal to be plated is less likely to deposit on the surface. The contact state between the cathode electrode or contact medium and the object to be plated due to the deposition of the plating film on the cathode electrode or contact medium without depending on the shape of the cathode electrode or contact medium or performing frequent maintenance. It is possible to prevent deterioration of the plating solution and non-uniformity of the current distribution in the plating solution between lots, and it is possible to reliably suppress and prevent variations in plating thickness between products.

Further, by using aluminum or an aluminum alloy as the metal material forming the cathode electrode or the contact medium, it is possible to reliably prevent the metal to be plated from depositing on the surface of the cathode electrode or the contact medium. become.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a plating method according to an embodiment of the present invention.

In this embodiment, a plating solution (Sn bath) containing Sn which is a plating metal is used as the plating solution 7, and the external electrodes 3a formed on both ends of the laminated ceramic capacitor 3 which is the object to be plated. The case where Sn plating is performed will be described as an example.

At least a part of the barrel 1 used in this embodiment is made of a material such as a wire mesh that allows a plating solution to pass therethrough, and the cathode electrode made of aluminum is attached to the tip end side of the conductor 2a having an insulation coating. 2 is disposed inside thereof.

Then, after accommodating a large number of monolithic ceramic capacitors (objects to be plated) 3 and small balls of aluminum (contact medium) 4 in the barrel 1, the barrel 1 is placed in a plating solution 7 in a plating tank 6. Immerse, cathode electrode 2 and plating tank 6
The plating solution 7 is energized between the anode electrodes 5 disposed inside.
The barrel 1 was rotated inside. In this way, the external electrode 3a of the monolithic ceramic capacitor 3 was brought into contact with the cathode electrode 2, the contact medium 4 and the plating solution 7 to perform Sn plating on the external electrode 3a. In this example, as the cathode electrode 2 and the contact medium 4 made of aluminum, for example, aluminum having a thin oxide film or an alumite treatment film formed on the surface is used, but the present invention is not limited to this. Absent.

As a result, almost no Sn plating film was deposited on the cathode electrode 2 and the contact medium 4 made of aluminum in the barrel 1. Further, even when the external electrode 3a of the monolithic ceramic capacitor 3 is repeatedly plated, Sn on the cathode electrode 2 and the contact medium 4 is also removed.
The growth of the plated coating was slight.

Therefore, it is possible to suppress the deposition of the Sn plating film on the cathode electrode 2 and the contact medium 4 without depending on the shape of the cathode electrode 2 and the contact medium 4 or to perform frequent maintenance. It is possible to prevent the contact state between the electrode 2 or the contact medium 4 and the monolithic ceramic capacitor 3 from being deteriorated, or to prevent the current distribution in the plating solution 7 from becoming non-uniform between lots, thereby making it possible to disperse the plating thickness between products. Can be reliably suppressed and prevented.

In the above embodiments, the case where the contact medium is used has been described. However, when the object to be plated is not so small and sufficient contact with the cathode electrode can be obtained, the contact medium is used. Instead, it is possible to form a desired plating film on the object to be plated using only the cathode electrode made of aluminum. Also in this case, it is possible to suppress the deposition of the plating film on the cathode electrode and obtain the same effect as in the above-mentioned embodiment.

Next, the cathode electrode (and contact medium) made of aluminum used in the above-mentioned examples plays the role of a current-carrying conductor, and a plating film is deposited on the object to be plated, but the cathode electrode (and contact medium). An experiment that confirms that the plating film hardly deposits will be described.

FIG. 2 is a diagram showing the configuration of the apparatus used in this experiment. In this experiment, a metal container (corresponding to the cathode electrode or the contact medium in the above embodiment) 13 was immersed in an Sn bath 12 in a container 11, and a copper ball was placed on the container 13 so as to be electrically connected to it. 14 (corresponding to the object to be plated in the above example) was placed, and current was applied between the copper sphere 14 and the anode (Sn plate) 15 arranged in the Sn bath 12 for plating. Then, an experiment was performed using a container made of a material different from copper, nickel, stainless steel, and aluminum as the metal container 13, and the thickness of the copper sphere 14 and the Sn plating film deposited on the container 13 was measured. The temperature of the Sn plating bath was 40 ° C. and the plating time was 10 minutes.
The results of the above experiment are shown in Table 1.

[0026]

[Table 1]

As shown in Table 1, when a copper, nickel, or stainless steel container 13 other than aluminum is used, the container 1
3 has a thickness (2.0 ~
Although the Sn plating film of 2.2 μm) was deposited, when the aluminum container 13 was used, the plating film deposited on the container 13 was extremely thin, 0.1 μm. It was confirmed that a plated coating having a thickness of 4.4 μm, which was much thicker than the coating, was formed.

From the above results, in the case of performing the Sn plating, by using the cathode electrode and the contact medium made of aluminum, it is possible to prevent the plating film from being deposited on the cathode electrode and the contact medium itself, and to suppress the plating on the object to be plated. It can be seen that the plated film can be reliably formed.

In this embodiment, the case where aluminum is used as the constituent material of the cathode electrode and the contact medium has been described, but the material in which the plating film is hard to deposit is not limited to this, and the material to be plated is not limited to this. It is possible to select an appropriate material by taking into consideration the type, the type of metal to be plated, the plating conditions, etc., and conducting the above-mentioned experiment in advance to investigate the material in which the plating film is hard to deposit. Become.

In addition, the present invention is not limited to the above-mentioned embodiment in other respects. The kind of metal to be plated, plating conditions such as composition and temperature of plating solution, barrel, cathode electrode and contact medium. Regarding the specific shape of
Various applications and modifications can be made within the scope of the invention.

[0031]

As described above, according to the plating method of the present invention, the cathode electrode (and the contact medium for electrically connecting the object to be plated and the cathode electrode) is made of a metal material on which the metal to be plated is less likely to deposit. Therefore, it is possible to suppress the deposition of the plating film on the cathode electrode or the contact medium without depending on the shape of the cathode electrode or the contact medium or frequently performing maintenance.

Therefore, it is possible to prevent the contact state between the cathode electrode or the contact medium and the object to be plated from being deteriorated, and to prevent the current distribution in the plating solution from becoming uneven between lots.
It is possible to reliably suppress and prevent variations in plating thickness between products.

Further, by using aluminum or aluminum alloy as the metal material constituting the cathode electrode or the contact medium, it is possible to reliably prevent the metal to be plated from depositing on the surface of the cathode electrode or the contact medium. .

Further, according to the present invention, for example, an aluminum mesh belt is used as a current-carrying conductor, and an object to be plated can be placed on the mesh belt to supply power and convey the material simultaneously. It is also possible to automate various processes such as addition to the plating solution, plating treatment, washing of the object to be plated, product packaging and transportation.

[Brief description of drawings]

FIG. 1 is a diagram showing a plating method according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an apparatus used in an experiment for confirming that a plating film is not deposited on a cathode electrode (and a contact medium) made of aluminum.

FIG. 3 is a diagram showing a conventional plating method.

[Explanation of symbols]

1 barrel 2 cathode electrode 3 object to be plated (multilayer ceramic capacitor) 3a external electrode of multilayer ceramic capacitor 4 contact medium 5 anode electrode 6 plating tank 7 plating solution

Claims (4)

[Claims] 1. An object to be plated is immersed in a plating solution, and the object to be plated is energized between the cathode electrode and the anode electrode while continuously or intermittently contacting the object to be plated with the cathode electrode. A plating method for depositing a predetermined plating film, characterized in that a cathode electrode made of a metal material that hardly deposits a metal to be plated in a plating step is used as the cathode electrode. 2. A barrel in which a cathode electrode is disposed, a material to be plated is placed and immersed in a plating solution, and the barrel is energized between the anode electrode and the cathode electrode disposed in the plating solution. The plating method according to claim 1, wherein a predetermined plating film is deposited on the object to be plated by rotating the plate. 3. The barrel, together with the object to be plated, a contact medium, which is made of a metal material in which a metal to be plated in a plating step is less likely to deposit on the surface, is provided to electrically connect the object to be plated and the cathode electrode. The plating method according to claim 2. 4. The plating method according to claim 1, wherein the metal material is aluminum or an aluminum alloy.