JP2003155600A - Plating apparatus for small-sized material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem that electric field is concentrated to an edge of a cathode in electroplating for a small-sized material and a projecting part is formed in the deposited material on the cathode corresponding to the edge of the cathode and the projecting part disturbs the stirring of the material to make good and efficient plating impossible. SOLUTION: The electric field is distributed over the whole by forming a plurality of grooves 11 on the surface of the cathode in contact with the small-sized material to center the electric field also in the vicinity of the grooves 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus for electroplating a small object to be plated such as a small electronic component, and more particularly to an improvement in the cathode structure.

[0002]

2. Description of the Related Art For example, a multilayer ceramic capacitor,
External electrodes formed on the outer surfaces of chip-shaped small electronic components such as cylindrical capacitors, laminated varistors, and laminated inductors are often plated. When performing such plating by electroplating, for example, in Japanese Unexamined Patent Publication No. 5-70999, a plating apparatus 1 as shown in FIG. 6 is used.

Referring to FIG. 6, a plating apparatus 1 includes a plating tank 3 which stores a plating solution 2. A cathode 4 and an anode 5 each made of a conductor are immersed in the plating solution 2.

A plurality of small objects to be plated 6 to be plated (the assembly thereof is schematically indicated by broken lines) are contained in a parts container 7 in the plating solution 2. The object to be plated 6 is a plurality of small electronic components 6a to be plated.
In addition, it includes a plurality of media 6b made of a conductor.

The above-mentioned electrode 4 is arranged so as to form a part of the bottom surface of the above-mentioned component container 7. Therefore, the small electronic component 6 a and the medium 6 b are placed on the cathode 4 in the plating solution 2.

The component container 7 is provided with a vertical shaft 8. The component container 7 rotates about a vertical axis provided by a vertical shaft 8 and thereby stirs the plating solution 2 and also small electronic components 6a in the component container 7.
Also, a stirring action is exerted on the medium 6b so that each of the small electronic components 6a and each of the media 6b contact the cathode 4 evenly.

In such a plating apparatus 1, the cathode 4
Since a current is applied between the anode and the anode 5, if a predetermined voltage is applied between them, a plating film is deposited on an external electrode (not shown) of the small electronic component 6a, and desired electroplating is performed. To be done.

[0008]

When a plating process is performed using the plating apparatus 1 as described above, the surface of the cathode 4 is
It is inevitable that more or less deposits due to plating will form. In particular, small electronic components 6a and media 6b
The more often the situation occurs where the cathode does not contact the cathode 4, the more deposits on the cathode 4.

In the plating apparatus 1, the cathode 4
The surface that contacts the small electronic component 6a and the medium 6b is
It is provided with a smooth flat surface so as not to disturb stirring of the small electronic components 6a and the medium 6b.

However, in the case where the cathode 4 has a smooth flat surface as described above, the cathode 4 can be processed during the plating process.
The electric field tends to concentrate on the edge portion of the cathode 4, and as shown in FIG. 7, the precipitate 9 on the cathode 4 may form a protrusion 10 at the edge portion of the cathode 4.

The above-mentioned projection 10 hinders the stirring of the small electronic components 6a and the medium 6b, and also makes it easier for the deposit 9 to peel off during the plating process.
As a result, the deposit 9 is recognized as a foreign matter and the small electronic component 6a.
It may adhere to the top.

The projection 1 thus formed on the precipitate 9
0 hinders the stirring of the small electronic components 6a and the medium 6b, and when the stirring is disturbed, the situation in which the small electronic components 6a and the media 6b do not contact the cathode 4 is more frequently brought about, and when this situation is brought about, A vicious cycle occurs in which more precipitates 9 are formed and the projections 10 are more likely to grow.

Therefore, an object of the present invention is to provide a plating apparatus for a small object to be plated which can solve the above problems.

[0014]

SUMMARY OF THE INVENTION The present invention comprises a plating tank for storing a plating solution, and a cathode and an anode which are immersed in the plating solution and consist of conductors. A plating device for a small object to be plated, which is configured to deposit a plating film on the small object to be plated by contacting the cathode in the plating solution with the cathode and energizing between the cathode and the anode. In order to solve the above-mentioned technical problem, a concave portion is formed on the surface of the cathode that comes into contact with the small object to be plated.

Whether the recess is provided by a plurality of grooves formed on the surface of the cathode that contacts the small object to be plated or by a plurality of small holes formed on this surface, It may be provided by a chamfer formed on the peripheral portion of the surface.

If the recesses are provided by grooves, the grooves are preferably formed so as to intersect one another.

The apparatus for plating a small object to be plated according to the present invention preferably further comprises a parts container for accommodating a plurality of small objects to be plated in a plating solution, and the cathode is a part of the bottom surface of the parts container. Are arranged to form a.

The component container described above preferably rotates about a vertical axis.

The present invention can be applied to various small objects to be plated, but is particularly advantageously used for plating small electronic parts.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 6 described above is also referred to for explaining one embodiment of the present invention. That is, FIG.
In the plating apparatus 1 shown in FIG. 1, the characteristic configuration of the present invention is the structure of the cathode 4.

FIG. 1 is a plan view of a component container 7 for explaining the first embodiment of the present invention.

The cathode 4a is arranged so as to form a part of the bottom surface of the component container 7. In this embodiment, 4
The individual cathodes 4a are arranged around the shaft 8 at intervals of 90 degrees.

The part of the parts container 7 where the cathode 4a is provided is enlarged and shown in FIG. In FIG.
(A) is a plan view and (b) is a sectional view.

As best shown in FIG. 2, the cathode 4a
A plurality of grooves 11 are formed on the upper surface of the, i.e., the surface that contacts the small electronic component 6a as the object 6 to be plated and the medium 6b (see FIG. 6), and these grooves 11 form the cathode 4a. A recess is provided on the top surface. The width of these grooves 11 is such that the small electronic component 6a to be plated.
Further, the dimensions are made smaller than the respective dimensions of the medium 6b so that the small electronic component 6a and the medium 6b are not fitted into the groove 11.

In the illustrated cathode 4a, three grooves 11 are provided so as to extend in parallel to each other in one cathode 4a, but the number and intervals thereof can be changed as necessary, It can be changed arbitrarily.

As shown in FIG. 1, four cathodes 4a are provided.
The extending direction of the groove 11 formed in each of the
However, the extending direction of the groove 11 can be arbitrarily changed.

Although the cross-sectional shape of the groove 11 is V-shaped as shown in FIG. 2B, it may be another shape such as U-shaped or quadrangular.

FIG. 3 is a view corresponding to FIG. 2A for explaining the second embodiment of the present invention.

A plurality of grooves 11 are formed on the upper surface of the cathode 4b shown in FIG. 3 so as to extend in parallel with each other, and intersect with these grooves 11, for example, in this embodiment, they are orthogonal to each other. Thus, a plurality of grooves 11a are further formed.

FIG. 4 is a diagram corresponding to FIG. 2 for explaining the third embodiment of the present invention.

A plurality of small holes 12 are formed on the upper surface of the cathode 4c shown in FIG. 4, and recesses are provided by these small holes 12. The small hole 12 is made smaller than the dimensions of the small electronic component 6a and the medium 6b to be plated,
The small electronic component 6a and the medium 6b are small holes 12
I will not be stuck in.

The number and distribution of the above-mentioned small holes 12 can be arbitrarily changed as required.

Further, although the illustrated small hole 12 has a circular plane shape as shown in FIG. 4A, it may be replaced with a square plane shape. Further, although the cross-sectional shape of the small hole 12 is V-shaped as shown in FIG. 4B, it may be another shape such as U-shaped or square-shaped.

FIG. 5 is a diagram corresponding to FIG. 2 for explaining the fourth embodiment of the present invention.

The cathode 4d shown in FIG. 5 is particularly shown in FIG. 5 (b).
As well shown in FIG. 1, a chamfered portion 13 is formed on the peripheral portion of the upper surface thereof, and the chamfered portion 13 provides a concave portion. The recess provided by the chamfer 13 is smaller than the dimensions of the small electronic component 6a and the medium 6b to be plated so that the small electronic component 6a and the medium 6b do not fit into the recess provided by the chamfer 13. It

The chamfered portion 13 shown in the drawing has a rounded surface as shown in FIG. 5B, but it may be changed to one having a flat slope.

According to the first to fourth embodiments described above, not only the edge portions of the cathodes 4a to 4d but also the vicinity of the groove 11 and the groove 11 are the portions where the electric field is likely to concentrate during the plating process. And 11a, near the small hole 12, or near the chamfered portion 13, so that the electric field to be concentrated can be dispersed. Therefore, as shown in FIG.
As a result of being generated more only in the edge portion of the
It is possible to make it difficult to cause the phenomenon in which the protrusions are formed, and thus it is possible to make it difficult to cause such a situation that the protrusions 10 hinder the stirring of the small electronic components 6a and the medium 6b.

Further, according to the first to fourth embodiments, the groove 11, the grooves 11 and 11a as the concave portion, and the small hole 1 are provided.
2 or the chamfered portion 13 has a small size such that the plated object 6 such as the small electronic component 6a or the medium 6b does not fit therein.
This is to prevent the slag from fitting into the recess and staying there to hinder stirring.

If the concave portion has a size sufficiently larger than that of the small electronic component or the medium, even if the concave portion is once fitted into the concave portion, it easily comes out, so that it does not stay and hinder stirring.

Next, experimental examples carried out to confirm the effects of the present invention will be described.

In this experimental example, as an example according to the present invention, as shown in FIG. 1, a component container 7 having an inner diameter of 25 cm in which four cathodes 4a are arranged is used in the plating apparatus 1 shown in FIG. I was there.

Further, in this experimental example, two types of cathodes 4a provided in the component container 7 were used, one having a diameter of 20 mm and the other having a diameter of 30 mm.

Regarding the cathode 4a having a diameter of 20 mm described above, three grooves 11 are formed at intervals of 5 mm, and each groove 11 is formed.
Has a width of 0.3 mm and a depth of 0.2 mm.

On the other hand, for the cathode 4a having a diameter of 30 mm, five grooves 11 are formed at intervals of 5 mm and each groove 11 is formed.
Has a width of 0.3 mm and a depth of 0.2 mm.

Also, a small electronic component 6a to be plated
A laminated capacitor having a size of 1.0 mm × 0.5 mm × 0.5 mm was used as the above, and the surfaces of the external electrodes formed on both ends of this laminated capacitor were plated.

On the other hand, as a comparative example, plating was performed under the same conditions as in the case of the example using a cathode having no groove.

Table 1 below shows the maximum thickness of the deposit formed on the cathode for each of the examples and comparative examples.

[0048]

[Table 1]

As can be seen from Table 1, the diameter of the cathode is 20
In both cases of mm and 30 mm,
According to the example, the maximum thickness of the deposited portion is smaller than that of the comparative example. From this, it is assumed that the formation of protrusions in the precipitate was suppressed in the examples.

Table 2 shows the presence / absence of peeling of deposits on the cathode and the plating thickness (average) on the external electrode of the multilayer capacitor for Examples and Comparative Examples in which the diameter of the cathode was 20 mm. It is a thing.

[0051]

[Table 2]

As can be seen from Table 2, first, according to the example, it was possible to prevent peeling of the deposit on the cathode.

Further, when the plating thicknesses were compared, according to the example, it was possible to obtain a thicker plating thickness as compared with the comparative example.

Considering the results of the thickness of the plating film shown in Table 2 and the results of the maximum thickness of deposits on the cathode shown in Table 1 above, according to the example, the deposits on the cathode were examined. The maximum thickness can be made smaller than that of the comparative example, so that it is possible to suppress the formation of protrusions or the like that hinder the stirring of the multilayer capacitor to be plated, and as a result, the multilayer capacitor is more frequently contacted with the cathode and thicker. It is speculated that a plated film was obtained.

Incidentally, in the above-mentioned experimental example, the cathode 4a having a diameter of 20 mm adopted as the example had three parallel grooves 11 as shown in FIGS. 1 and 2, but As shown in FIG. 3, it was confirmed that the maximum thickness of deposits on the cathode 4b can be further reduced to about 2 mm by using the cathode 4b in which three grooves 11 and 11a are formed in the vertical and horizontal directions, respectively. ing.

[0056]

As described above, according to the present invention, the surface of the cathode that contacts the small object to be plated is
Since the concave portion is formed, the portion where the electric field is likely to concentrate during the plating process can be formed not only on the edge portion of the cathode but also in the vicinity of this concave portion. As a result, more is generated only in the edge portion of the cathode, so that it is possible to prevent the phenomenon that protrusions and the like are formed in the precipitate from occurring.

Therefore, it is possible to prevent such a situation that such protrusions hinder the agitation of the small object to be plated, and the efficiency of the plating process can be improved.

Further, it is possible to prevent protrusions or the like from forming on the deposit on the cathode, and it becomes difficult for the deposit to peel off from the cathode due to the anchoring effect of the concave portion on the deposit. Therefore, it is possible to prevent the deposit from being attached as foreign matter to the small object to be plated, and to increase the size of the cathode itself without any problem. This makes it possible to reduce the amount of deposits per unit area of the cathode and also to improve the efficiency of the plating process.

In particular, when the above-mentioned recesses are provided by a plurality of grooves formed on the surface of the cathode that comes into contact with the small object to be plated, it becomes easy to distribute the recesses over the entire surface of the cathode, and the plating treatment is performed. The electric field therein can be more effectively dispersed.

The above-mentioned effects can be more remarkably exhibited when the plurality of grooves are formed so as to intersect with each other.

The present invention relates to a plating apparatus in which a component container for accommodating a plurality of small objects to be plated in a plating solution is provided, and the cathode is arranged so as to form a part of the bottom surface of the component container. Can be applied particularly advantageously. That is, in such a configuration, when the component container rotates about the vertical axis, a stirring action is exerted on the small object to be plated.
This is because, as described above, if it is difficult to form protrusions or the like on the deposit on the cathode, the stirring action can be more smoothly exerted on the small object to be plated.

[Brief description of drawings]

FIG. 1 is a view for explaining a plating apparatus according to a first embodiment of the present invention, which is a component container 7 provided in the plating apparatus.
FIG.

2A and 2B are enlarged views showing a portion of a component container 7 shown in FIG. 1 in which a cathode 4a is arranged, in which FIG. 2A is a plan view and FIG. 2B is a sectional view.

FIG. 3 is a diagram corresponding to FIG. 2A for explaining a cathode 4b according to a second embodiment of the present invention.

FIG. 4 is a view corresponding to FIG. 2 for explaining a cathode 4c according to a third embodiment of the present invention.

FIG. 5 is a diagram corresponding to FIG. 2 for explaining a cathode 4d according to a fourth embodiment of the present invention.

FIG. 6 is a sectional view schematically showing a plating apparatus 1 which is of interest to the present invention.

FIG. 7 is a cross-sectional view showing a part of a component container 7 for explaining the problem to be solved by the present invention.

[Explanation of symbols]

1 Plating equipment 2 plating solution 3 plating tank 4,4a, 4b, 4c, 4d cathode 5 anode 6 Plated object 6a Small electronic components 6b media 7 parts container 8 vertical shafts 11,11a groove 12 small holes 13 Chamfer

Claims (8)

[Claims] 1. A plurality of small objects to be plated, which are provided with a plating tank storing a plating solution and a cathode and an anode which are immersed in the plating solution and are made of a conductor, are the plating solution. In contact with the cathode in, by energizing between the cathode and the anode, configured to deposit a plating film on a small plated object, a plating apparatus for a small plated object, A plating device for a small-sized object to be plated, wherein a recess is formed on a surface of the cathode that comes into contact with the small object to be plated. 2. The plating apparatus for a small object to be plated according to claim 1, wherein the recess is provided by a plurality of grooves formed on the surface of the cathode. 3. The plating apparatus for a small object to be plated according to claim 2, wherein the grooves are formed so as to intersect each other. 4. The plating apparatus for a small object to be plated according to claim 1, wherein the recess is provided by a plurality of small holes formed on the surface of the cathode. 5. The plating apparatus for a small object to be plated according to claim 1, wherein the recess is provided by a chamfer formed on a peripheral portion of the surface of the cathode. 6. The component container for accommodating a plurality of small objects to be plated in the plating solution, wherein the cathode is arranged so as to form a part of a bottom surface of the component container. 6. The plating apparatus for a small object to be plated according to any one of 5 to 5. 7. The plating apparatus for a small object to be plated according to claim 6, wherein the parts container rotates about a vertical axis. 8. The plating apparatus for a small object to be plated according to claim 1, wherein the small object to be plated includes a small electronic component.