JP3265948B2 - Electronic component manufacturing method and barrel plating apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electronic component having an improved step of forming electrodes on the outer surface of the electronic component, and to an improvement in a barrel plating apparatus used in such a manufacturing method.

[0002]

2. Description of the Related Art An example of a conventional method for manufacturing an electronic component will be described with reference to a chip-type multilayer capacitor as an example.

A multilayer capacitor 1 has a sintered body 2 made of a dielectric ceramic such as barium titanate. Internal electrodes 3a to 3e are arranged in the sintered body 2 so as to overlap with each other via a ceramic layer. An external electrode 4 is formed on the end face 2a of the ceramic sintered body 2, and an external electrode 5 is formed on the end face 2b. External electrode 4,
Reference numeral 5 denotes baking layers 4a and 5a formed by applying and baking a conductive paste containing a metal powder such as Ag on the end surfaces 2a and 2b, and Ni formed by electroplating on the baking layers 4a and 5a, respectively. Layers 4b and 5b and N
Sn layers 4c and 5c are also formed on the i-layers 4b and 5b by electroplating.

In manufacturing the multilayer capacitor 1, after preparing a ceramic sintered body 2 on which the internal electrodes 3a to 3e are formed, a conductive paste is applied to both end surfaces 2a and 2b of the sintered body 2 and baked. The baking layers 4a, 5
a is formed. Next, the Ni layers 4b and 5b and the Sn layers 4c and 5c are formed using a barrel plating apparatus.

FIGS. 2 and 3 show the structure of a barrel plating apparatus.
This will be described with reference to FIG. The barrel plating apparatus 6 has a structure in which end faces 8 and 9 are fixed to both ends of the barrel main body 7 so as to close both ends of the cylindrical barrel main body 7. As is clear from FIG. 3, the end faces 8, 9 are provided with the cathode wires 10, 11 respectively.
Is inserted. The barrel main body 7 is configured to be rotationally driven by a driving source (not shown). However, the positions of the cathode rays 10 and 11 are fixed while keeping the positions shown in FIG.

[0006] The cathode wires 10 and 11 are respectively provided with introduction portions 10a and 10a extending inward through the centers of the end face members 8 and 9, respectively.
11a. The bent portions 10b and 11b are formed so as to be bent at the tips of the introduction portions 10a and 11a and extend toward the side surface of the barrel main body 7. Also,
At the distal ends of the bent portions 10b and 11b, distal ends 10c and 11c are provided so as to extend toward the other end face material. In the cathode wires 10 and 11, only the tip portions 10c and 11c are exposed, and in the introduction portions 10a and 11a and the bent portions 10b and 11b, insulating coating (not shown) is applied around the cathode wires. ing.

At the time of barrel plating, the media 13 and the electronic components 14 are charged into the barrel body 7, and the barrel body 7 is immersed in the plating solution 12 and energized using the cathode wires 10, 11 while rotating. The electronic component 1
A plating film is formed on the baking layer 4 (not shown). The medium 13 is made of a conductive material such as a steel ball, and is provided to assist the electrical conduction between the cathode wires 10 and 11 and the electronic component 14. In FIG. 3, the media 13 and the electronic components 14 are illustrated as being scattered in a separated state, but in reality, the media 13 and the electronic components 14 are more densely dispersed than illustrated. Have been.

While rotating the barrel body 7, the cathode wires 10,
The electronic component 14 is agitated in the plating solution 12 by energizing with the use of 11, and the energization is assisted by the medium 13, so that a plating film of a desired film thickness is formed on the baking layer. become.

[0009]

However, the electronic component 14 located at the position shown by the arrow A in FIG. 3, ie, the end face members 8 and 9, and the bent portions 10b and 11 of the cathode wires 10 and 11 are present.
The electronic component 14 positioned between the electronic component 14 and the electronic component 14 is hard to be sufficiently stirred. Therefore, the electronic component 14 existing at the position indicated by the arrow A
Has a problem that plating is more difficult than the electronic component 14 located at the center, and the thickness of the plating film tends to vary. That is, in the electronic component 14 located at the position indicated by the arrow A, there is a problem that the thickness of the plating film is unlikely to be the target thickness.

However, if the plating time is increased and plating is performed while rotating the barrel body 7, a plating film having a desired thickness can be formed even on the electronic component element 14 at the position indicated by the arrow A. is there. However, when the plating time is prolonged, the plating solution 12 easily penetrates into the sintered body through the pores present in the baked layer of the external electrode, and particularly the gap between the internal electrode and the ceramic layer in the sintered body. From the interface of the multilayer capacitor, and the thermal shock resistance of the obtained multilayer capacitor is degraded.

Accordingly, an object of the present invention is to provide a method capable of forming an electrode having a plating film having a thickness with little variation in a relatively short time and producing an electronic component having excellent properties such as thermal shock resistance. Another object of the present invention is to provide a barrel plating apparatus capable of obtaining such an electronic component.

[0012]

According to the present invention, an electronic component and a medium for assisting electrical conduction between the barrel and the electronic component are placed in a barrel of a barrel plating apparatus, and the barrel is placed in a plating solution. Immersion, energizing while rotating, in a method of manufacturing an electronic component having a step of forming an electrode film on the surface of the electronic component by plating, as the barrel plating device, a cylindrical closed both ends by a pair of end face material A barrel body, an introduction portion extending inward from the center of the end face material, a bent portion bent at the tip of the introduction portion so as to extend to the side of the barrel body, and the other end face from the tip of the bent portion A cathode wire having a tip portion extended toward the material side and arranged so as not to rotate with the barrel main body; and inside the end face material, extending from near the center of the end face material to the bent wire tip side of the cathode wire. Provided on so that, and Kirijo
A method for manufacturing an electronic component, comprising: using a rectifier having a shape as described above.

In the method for manufacturing an electronic component according to the present invention, the rectifier is provided so as to extend from the center of the end face material or its vicinity to the tip of the bent portion of the cathode ray.
Even if the electronic component enters the space between the end face material and the bent portion of the cathode ray, the electronic component is smoothly moved to the center of the barrel from the bent portion. Therefore, it is possible to effectively reduce the variation in the plating film thickness of a large number of electronic components put into the barrel.

Further, the barrel plating apparatus of the present invention is a barrel plating apparatus for plating an electronic component immersed in a plating solution inside the barrel plating apparatus, wherein a cylindrical barrel closed at both ends by a pair of end face members. A main body, an introduction portion extending inward from the center of the end face material, a bent portion bent at the tip of the introduction portion so as to extend to the side of the barrel body, and the other end face material side from the tip of the bent portion A cathode ray having a tip portion extended to the inside, and a cathode ray arranged so as not to rotate with the barrel body, and inside the end face material of the barrel,
A barrel plating apparatus, comprising: a rectifier having a conical shape and provided so as to extend from the center of the end face material toward the tip of the bent portion of the cathode wire.

In the barrel plating apparatus of the present invention, the rectifier is attached to the barrel so as to extend from the vicinity of the center of the end face material toward the tip of the bent portion of the cathode wire. The electronic component between the and the bent portion of the cathode ray is smoothly moved to the central region of the barrel. Therefore, when plating a large number of electronic components put in the barrel, it is possible to reduce variations in the thickness of the plating film.

[0016]

FIG. 4 is a perspective view showing the appearance of a barrel plating apparatus according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing the internal structure.

The barrel plating apparatus 21 of the present embodiment has a cylindrical barrel main body 22. Usually, a large number of through holes (not shown) are provided in the side wall of the barrel main body 22 so that a plating solution described later can pass therethrough. In the present embodiment, the barrel main body 22 has a hexagonal cross section.
Although it is configured as a rectangular tube, it may be configured so that the cross-sectional shape is another polygonal shape such as a quadrangle or a pentagon. Further, the barrel main body 22 may have a cylindrical shape. However, in order to enhance the stirring effect of the electronic components inside and reduce the variation in the thickness of the plating film, it is desirable to configure the barrel main body 22 so as to have a prismatic shape rather than a cylindrical shape.

At both end surfaces of the barrel body 22, an end face material 2 is provided.
3 and 24 are fixed, and the inside of the barrel main body 22 is closed to form a barrel 25. The end face members 23 and 24 may be formed integrally with the barrel body 22.

The material constituting the barrel body 22 and the end face members 23 and 24 is not particularly limited, but
It can be made of a suitable rigid material such as metal or synthetic resin. The barrel 25 is configured to be rotatable around its axial direction by a rotation drive source such as a motor (not shown).

On the other hand, as is apparent from FIG.
Through holes 23a and 24a are formed at the centers of the holes 3 and 24, respectively. Cathode wires 26, 27 whose positions are fixed so as not to rotate themselves are inserted into the through holes 23a, 24a. The cathode wires 26, 27 are connected to the through holes 23a,
It has introduction parts 26a and 27a inserted through 24a.
The introduction portions 26a and 27a are connected to a negative potential (not shown) at the outer ends. The introduction sections 26a and 27a
It penetrates through holes 23 a and 24 a and extends linearly into barrel body 22. The leading ends of the introduction portions 26a, 27a are bent, whereby the bent portions 26b, 27
b. The bent portions 26b and 27b are extended so that the distal ends face the side surfaces of the barrel main body 22.

On the other hand, the cathode wires 26 and 27 are bent again at the tips of the bent parts 26b and 27b, and the tips 26c and 27 are bent.
c is configured. The tip portions 26c and 27c are substantially parallel to the introduction portions 26a and 27a, that is, the other end face material 2
4, 23 side.

As is apparent from FIG.
Insulation coatings 28 and 29 are formed around the periphery of each of the introduction portions 26a and 27a and the bent portions 26 so that the tips 26c and 27c are exposed.
b, 27b. The insulating coatings 28 and 29 are formed by attaching an appropriate insulating resin or the like around the cathode wires 26 and 27.

In the barrel 25, the end face members 23,
Rectifiers 30 and 31 are attached to the inner surface of 24.
The rectifier 30 is formed of a material having an appropriate shape retaining property such as a synthetic resin or ceramics. This rectifier 30
As shown in FIGS. 6A and 6B, the triangular pyramid has three vertices on the inner surface of the end face member 23 and the other one is on the inner wall of the barrel body 22. ing.
Accordingly, the surfaces 30a and 30b (see FIG. 6) of the straightening body 30 exposed in the barrel main body 22 are bent toward the central region of the barrel main body 22 from the end face member 23.
(See FIG. 5).

In the barrel 25, an electronic component 33 and a medium 34 are charged and immersed in a plating solution 32 to perform plating. The electronic component 33 is not particularly limited, but may be a chip-type ceramic electronic component such as a multilayer capacitor. The media 34 is introduced to assist in energizing the outer surface of the electronic component 33 when forming a plating film on the outer surface of the electronic component 33. Therefore, in practice, FIG.
, More electronic components 33 and media 34 than those shown in FIG.
The medium 34 functions so as to electrically connect the medium 3 with the medium 3.

Since the medium 34 is provided to assist the energization, it is made of a conductive material such as a steel ball, or at least a material whose surface is made conductive. Further, the shape of the medium 34 is not particularly limited, but in order to sufficiently exhibit the above-described energization assisting action with the rotation of the barrel 25,
A spherical shape is desirable.

When plating using the plating apparatus 21 of the present embodiment, power is supplied while rotating the barrel 25 from the state shown in FIG. In this case, since the electronic component 33 and the medium 34 are sufficiently stirred and mixed in a region between the tips 26c and 27c of the cathode rays 26 and 27, the plating film can be formed with relatively little variation. . On the other hand, as described in the related art section, the cathode ray 2
In the region between the bent portions 26b and 27b of the end portions 6 and 27 and the end face members 23 and 24, stirring of the electronic component 33 is prevented. However, in the present embodiment, since the rectifiers 30 and 31 are provided, the electronic components 33 are placed in the space indicated by the arrow C in FIG.
When the medium or the medium 34 enters, the electronic component 33 and the medium 34 move smoothly along the outer wall of the rectifier 30 as the barrel 25 rotates. That is, the cathode rays 26, 27
Of the barrel body 22, and further toward the center of the barrel body 22. Accordingly, it is possible to uniformly plate all the supplied electronic components 33, and it is possible to suppress a variation in the thickness of the plating film.

The rectifier 30 is preferably configured such that the dimension P in FIG. 5 is larger than the dimension Q in FIG. Here, the dimension P refers to the innermost end of the rectifier 30,
The distance between the end face material 23 and the end face material 23 is shown.
3 shows the distance from the inner surface to the innermost part of the bent portion 26b of the cathode ray 26. When the dimension P is smaller than the dimension Q, in the space between the bent portion 26b and the rectifier 30, stagnation of the electronic component body and the medium 34 may occur, and the operation of the rectifier 30 may be sufficiently performed. May not be exhibited. Therefore, it is preferable that the dimension P be equal to or larger than the dimension Q.

[0028]

However, it is preferable that the rectifier 30 has a triangular pyramid shape as in this embodiment. This is because the electronic component 33 and the medium 34
However, as shown in FIG. 7, which is a schematic cross-sectional view as viewed from the inside of the barrel, there is a bias in the barrel. In this case, when the rectifying body 30 is a triangular pyramid, since the twill wire 30c exists, the electronic component 33 and the medium 34 are more smoothly moved to the center region side of the barrel 22 as the barrel 22 rotates. Will be. That is, stagnation of the electronic component 33 and the medium 34 in the portion where the rectifier 30 is provided can be more effectively suppressed.

[0030]

EXAMPLE Next, the Ni layer and the Sn layer were plated on the baked electrodes of the multilayer capacitor using the barrel plating apparatus described in the above embodiment.

The prepared multilayer capacitor is 1.6 × 0.
100 × 10 ³ pieces having a size of 8 × 0.8 were placed in the barrel. The media used was an iron ball having a diameter of 1.5 mm, and 150 × 10 ³ balls were put into the barrel. In plating, a current of 20 A was applied to each of the Ni layer plating and the Sn layer plating, and the plating was performed by rotating the barrel for 30 minutes each.

For comparison, a conventional barrel plating apparatus shown in FIG. 3 was used as a used barrel plating apparatus.
Except that the plating time was 60 minutes for each of the plating of the Ni layer and the Sn layer,
The i-layer and the Sn layer were plated (Comparative Example).

As described above, the Ni layer and the Sn layer were plated, and the thickness of the plated film in the obtained multilayer capacitor was measured. The results are shown in Table 1 below.

[0034]

[Table 1]

The CV value in Table 1 means that the standard deviation is σ,
When the average value of the thickness of the plating film is x, σ / x × 1
It is a value represented by 00 (%). The measurement results of the thickness of the plating film shown in Table 1 are the measurement results for 50 multilayer capacitors under each condition.

As is apparent from Table 1, the CV value indicating the degree of variation in the thickness of the plating film is significantly reduced in the barrel plating apparatus of the example as compared with the comparative example.

Also, the minimum film thickness value (x−3σ) statistically calculated in one manufacturing lot may be large in the case of the embodiment, even though the average film thickness is small. Understand. From this, even if the time of barrel plating is reduced to half by using the barrel plating apparatus of the example, the function of the plating film, that is, the solder heat resistance by the Ni plating layer and the solderability by the Sn plating layer, It can be seen that it can be secured as in the case of the comparative example.

Further, a thermal shock test was performed on the multilayer capacitors of the example and the comparative example after the barrel plating was performed. The thermal shock test is performed by immersing the laminated capacitor in molten solder at 250 to 450 ° C for 2 seconds, pulling it up,
Thereafter, polishing was performed and observation was made for the presence or absence of cracks. The results are shown in FIG.

In FIG. 8, the solid line X shows the result of the embodiment, and the broken line Y shows the result of the comparative example. As is clear from FIG. 8, in the multilayer capacitor obtained in the example, no crack was generated even when the temperature of the solder was increased to 400 ° C., whereas the multilayer capacitor obtained in the comparative example was obtained. It can be seen that cracks occur at a considerable rate at a temperature of 300 ° C. or higher in the capacitor.

Therefore, when the barrel plating apparatus of the comparative example is used, the quality degradation due to the infiltration of the plating solution greatly varies within a lot, and thermal cracks may occur at a relatively low temperature. In the case of using the barrel plating apparatus of the embodiment, since there is almost no variation in the above-mentioned deterioration in quality among lots, it is considered that the heat resistance of all the multilayer capacitors is maintained at substantially the same level.

[0041]

According to the method for manufacturing an electronic component and the barrel plating apparatus of the present invention, the above-mentioned rectifier is attached to the barrel so as to extend from near the center of the end face material of the barrel to the tip of the bent portion of the cathode wire. When plating is performed while rotating the barrel, the supplied electronic components and media move smoothly from the space between the end face material and the bent portion of the cathode wire to the central region of the barrel. Therefore, in barrel plating, variations in the thickness of the formed plating film can be significantly reduced. In addition, since electronic components are unlikely to stay in areas where plating is difficult, it is possible to significantly reduce the time required for barrel plating, thereby effectively increasing the productivity of electronic components and saving energy. Can be.

In addition, since the plating time can be shortened, the infiltration of the plating solution into the electronic component can be suppressed.
Therefore, it is also possible to provide an electronic component having excellent thermal shock resistance. In particular, in the case of a ceramic laminated electronic component, when plating, a plating solution may enter the sintered body from the interface between the internal electrode and the ceramic layer, and the thermal shock resistance may be reduced. In the production, the plating time can be shortened, so that the present invention can be applied more effectively.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a multilayer capacitor.

FIG. 2 is a perspective view for explaining a conventional barrel plating apparatus.

FIG. 3 is a partially cutaway sectional view of a conventional barrel plating apparatus.

FIG. 4 is a perspective view showing an appearance of a barrel plating apparatus according to one embodiment of the present invention.

5 is a partially cutaway sectional view of the barrel plating apparatus shown in FIG.

FIGS. 6A and 6B are a schematic perspective view and a plan view of the rectifier for explaining the rectifier, respectively.

FIG. 7 is a schematic cross-sectional view seen from the inside of the barrel for explaining the operation of the rectifier.

FIG. 8 is a diagram showing the results of a thermal shock test, showing the relationship between the solder melting temperature and the rate of occurrence of thermal cracks.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Barrel plating apparatus 22 ... Barrel main body 23, 24 ... End face material 25 ... Barrel 26, 27 ... Cathode wire 26a, 27a ... Introducing part 26b, 27b ... Bending part 26c, 27c ... Tip part 30, 31 ... Rectifier 32 ... Plating solution 33 ... Electronic components 34 ... Media

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A 2-102469 (JP, U) JP-A 6-20459 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) C25D 17/20 H01G 4/12 364 H01G 13/00 391

Claims (2)

(57) [Claims] An electronic component and a medium for assisting electrical conduction between the barrel and the electronic component are placed in a barrel of a barrel plating apparatus, the barrel is immersed in a plating solution, and energized while rotating. In a method of manufacturing an electronic component having a step of forming an electrode film on a surface of the electronic component by plating, as the barrel plating apparatus, a cylindrical barrel main body having both ends closed by a pair of end face materials; A leading end extending from the leading end of the leading end toward the other end face material side, and a leading end extending from the leading end of the leading end toward the side surface of the barrel. And a cathode wire disposed so as not to rotate with the barrel body; and a barrel body and / or so as to extend from the vicinity of the center of the end face material to the tip of the bent portion of the cathode wire inside the end face material. It is fixed to an end face member, and is characterized by using those having a rectifying body having the shape of Kirijo method of manufacturing an electronic component. 2. A barrel plating apparatus for immersing and plating an electronic component in a plating solution therein, comprising: a cylindrical barrel main body having both ends closed by a pair of end face members; An introduction portion extended inward, a bent portion bent at the tip of the introduction portion so as to extend to the side surface of the barrel, and a tip portion extended from the tip of the bent portion to the other end material side. A cathode wire disposed so as not to rotate together with the barrel body, and provided inside the end face material of the barrel so as to extend from near the center of the end face material toward the bent wire tip side of the cathode wire , and A barrel plating apparatus, comprising: a rectifier having a conical shape .