JP2001032099A - Production of electronic parts and barrel plating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a process for producing electronic parts having a stage capable of forming plating films having decreased thickness variations by a wet barrel plating process on the metallic films on the outside surfaces of electronic parts. SOLUTION: When the electronic parts formed with the metallic films on the outside surfaces are prepared and the plating films are formed by the barrel plating device on the outside surfaces of the electronic parts, the plating device has a rotary drum 12 and first and second cathodes 13 and 14. These first and second cathodes 13 and 14 have cathode body parts 13a and 14a and plural pieces of electrode fingers 13b and 14b. The electrode fingers 13b and 14b, of which the front ends are formed as exposed parts 13b1 and 14b1 are used. The barrel plating is executed by specifying the length of the exposed parts 13b1 and 14b1 to a range of 0.5 to 1.0L and the width thereof to a range of 5 to 30A when the length from the surface 17 of the feeding material at the time of plating to the bottom end of the exposed parts 13b1 and 14b1 is defined as L and the diameter of an energizing medium 18 as A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electronic component such as a multilayer capacitor, and more particularly, to a method for manufacturing a multilayer capacitor in which an external electrode has a plating film formed on a metal film. The present invention relates to a method for manufacturing an electronic component having an improved step of forming a substrate, and a barrel plating apparatus.

[0002]

2. Description of the Related Art In an electronic component, electrodes for electrically connecting to the outside are formed on the outer surface of an electronic component body such as a ceramic sintered body. For example, in a multilayer capacitor, a plurality of internal electrodes are formed in a ceramic sintered body so as to overlap with each other via a ceramic layer, and both ends of the ceramic sintered body are electrically connected to any one of the internal electrodes. External electrodes are formed on the surface.

The external electrodes can be formed by various methods. Usually, an external electrode is formed on a metal film formed by applying and baking an Ag paste or an Ag-Pd paste.
It has a structure in which a Ni plating film and a Sn plating film are stacked in this order.

That is, a metal film formed by applying and baking a conductive paste such as an Ag paste or an Ag-Pd paste has excellent reliability of electrical connection to an internal electrode and exhibits good conductivity. . However, A
g causes solder erosion during soldering. Therefore, in order to prevent solder erosion, a Ni plating film is formed on the surface of the metal film. Since the Ni plating film has insufficient solderability, a Sn plating film is further formed on the outer surface to enhance the solderability.

In forming a Ni plating film or a Sn plating film on the above-mentioned metal film, a barrel plating apparatus is used in order to increase productivity. A conventional plating method using a barrel plating apparatus will be described with reference to FIG.

[0006] The barrel plating apparatus 51 has a cylindrical rotary drum 52. The rotary drum 52 is configured to be rotatable around its central axis by a rotary drive source. A cathode 53 is provided so as to penetrate the end faces 52a and 52b of the rotating drum 52 facing each other. The cathode 53 is
It is arranged so as not to rotate with the rotating drum 52, that is, is fixedly arranged. The cathode 53 includes a cathode body 53a extending from the end face 52a toward the end face 52b, and a cathode body 53a extending downward from the cathode body 53a.
Electrode fingers 53 dispersedly formed along the length direction of
b. The cathode 53 is covered with an insulating coating layer 54 except for the tip portion of the electrode finger 53b.

At the time of barrel plating, the rotating drum 52
Inside, a steel ball 56 as an energizing medium and an electronic component 57 as an object to be plated are put, and immersed in a plating solution tank (not shown). Thereafter, while rotating the rotating drum 52, current is supplied between the cathode 53 and the anode in a plating bath (not shown). As a result, the exposed portion 53 of the cathode 53
relative to b _1, the metal film formed by applying and baking of conductive paste on the outer surface of the electronic component 57 are in contact, the metal plating solution on the metal film is deposited. Alternatively, the exposed portion 53b ₁ of the electrode finger 53b, a metal film of the electronic component 57 even if it is electrically connected via a steel ball 56, the metal in the plating solution in the same manner to precipitate.

Further, since the rotary drum 52 is rotated, the electronic components 57 being turned is electrically connected repeatedly exposed portion 53b ₁ of the electrode fingers 53, the plating film is formed on the metal film .

[0009]

As described above, when the conventional barrel plating apparatus 51 is used, by rotating the rotary drum 52, the steel balls 56 and the electronic components 57 are agitated. Thus, the metal film of the electronic component 57 are electrically connected repeatedly exposed portion 53b ₁ of the electrode finger 53b, the plating film is formed.

That is, the rotating drum 52 functions to stir the steel balls 56 and the electronic components 57 in the plating tank, and to repeatedly connect the metal film on the outer surface of the electronic components 57 to the electrode fingers 53b. .

However, in the conventional barrel plating apparatus 51, even if the rotation speed and the time of the rotating drum 52 are controlled, the thickness of the formed plating film tends to vary in a large number of the supplied electronic components 57. Met.

Although the cathode 53 is not rotated, while the rotating drum 52 is rotating, some of the electronic components 57 are not rotated.
May adhere to the upper surface of the cathode main body 53a.
Since the cathode main body 53a is covered with the insulating coating layer 54, when the electronic component 57 adheres to the upper surface, a sufficient plating film is no longer formed on the metal film of the attached electronic component 57. Therefore, when the internal electronic components are finally taken out of the rotary drum 52, the electronic components for which the plating film is not sufficiently formed are mixed. Therefore, also from this point, the thickness variation of the plating film has to be very large.

[0013]

SUMMARY OF THE INVENTION An object of the present invention is to stably form a plating film having a small thickness variation by an electric barrel plating device on the surface of a metal film of an electronic component having a plurality of metal films formed on an outer surface. And a barrel plating apparatus.

[0014]

According to a first aspect of the present invention, an external electrode is formed on an outer surface, and the external electrode comprises:
A method for manufacturing an electronic component having a laminated structure of a metal film and a plating film formed by wet barrel plating on the metal film, and a step of preparing an electronic component having a metal film formed on an outer surface thereof, Forming a plating film on the outer surface of the metal film by a barrel plating device, wherein the barrel plating device is disposed so as to extend into the drum from both ends of the rotating drum and both ends of the rotating drum, respectively. And a first cathode and a second cathode which are configured not to rotate as the drum rotates, wherein the first and second cathodes extend from the end of the rotary drum to the inside of the rotary drum. The body, a plurality of electrode fingers extending downward from the lower surface of the cathode body, and an insulating coating layer that exposes the tips of the electrode fingers and covers the remaining part of the electrode fingers and the cathode body. What you have The length of the exposed portion of the electrode finger is defined as L, where L is the length from the surface of the input material when the electronic component and the energizing medium are loaded into the rotating drum to the tip of the exposed portion of the electrode finger. The width of the exposed portion of the electrode finger is 5A or more and 30A or less when the diameter is in the range of 0.5L to 1.0L and the diameter of the energizing medium is A.

According to a second aspect of the present invention, an external electrode is formed on an outer surface, and the external electrode has a laminated structure of a metal film and a plating film formed on the metal film by wet barrel plating. A method of manufacturing an electronic component having an electronic component having a metal film formed on an outer surface thereof, and a step of forming a plating film by a barrel plating apparatus on the outer surface of the metal film, As a barrel plating apparatus, a rotary drum having a cylindrical shape, and first and second cathodes positioned so as to extend inward from both ends of the rotary drum and arranged so as not to rotate with the rotary drum are provided. The first and second cathodes each have a cathode main body and a plurality of electrode fingers extending downward from the cathode main body, and the direction in which the cathode main body extends is 40 to 60 ° with respect to a vertical direction. Make an angle of Characterized by using what is made.

A third invention of the present application is a barrel plating apparatus, wherein a barrel-shaped rotary drum and a rotary drum are positioned so as to extend inward from both ends of the rotary drum, and are arranged so as not to rotate together with the rotary drum. First and second cathodes, wherein the first and second cathodes have a cathode body and a plurality of electrode fingers extending downward from the cathode body, and the cathode body extends. Direction is 40 to vertical direction
It is characterized in that it is configured to form an angle of 60 °.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

(First Embodiment) In the first embodiment, a multilayer capacitor 1 shown in a longitudinal sectional view in FIG. 2 is manufactured as an electronic component. The multilayer capacitor 1 has a ceramic sintered body 2 made of a dielectric ceramic such as a barium titanate-based ceramic. In the ceramic sintered body 2, the internal electrodes 3a to 3f are formed so as to overlap in the thickness direction via a ceramic layer. Internal electrodes 3a, 3c,
3 e is drawn out to the first end face 2 a of the ceramic sintered body 2. The internal electrodes 3b, 3d, 3f are connected to the second end face 2b of the ceramic sintered body 2 on the opposite side to the first end face 2a.
Has been drawn to.

First and second end faces 2 of ceramic sintered body 2
Metal films 4 and 5 are formed by applying and baking a conductive paste so as to cover a and 2b and to reach upper surface 2c, lower surface 2d and both side surfaces of ceramic sintered body 2. Ni plating films 6 and 7 and Sn plating films 8 and 9 are laminated on the metal films 4 and 5. Metal film 4, Ni
The plating film 6 and the Sn plating film 8 constitute a first external electrode 10a, and the metal film 5, the Ni plating film 7 and the Sn plating film 9 constitute a second external electrode 10b.

In this embodiment, first, a structure in which the metal films 4 and 5 are formed on the outer surface of the ceramic sintered body 2 by applying and baking an Ag paste is obtained. The method of obtaining this structure can be performed according to a conventionally known method of manufacturing a multilayer capacitor.

Next, in the present embodiment, Ni plating films 6, 7 and Sn plating films 8, 9 are formed on the outer surfaces of the metal films 4, 5 of the multilayer capacitor 1 on which the metal films 4, 5 are formed. It is formed using an electric barrel plating apparatus.

In the above-mentioned electric barrel plating, FIG.
A barrel plating apparatus shown in (a) and (b) is used. The barrel plating device 11 has a cylindrical rotary drum 12. The rotating drum 12 has a cylindrical shape in the present embodiment, but may have a polygonal cylindrical shape.

The rotary drum 12 is configured to be rotatable around its central axis by a rotary drive source (not shown), for example, a motor. The rotating drum 12 has a pair of end faces 12a and 12b facing each other. In this embodiment, the end surfaces 12a and 12b are configured to extend in the vertical direction.

First and second cathodes 13 and 14 are arranged so as to extend from the outside to the inside of the end faces 12a and 12b, respectively. The cathodes 13 and 14 are fixedly arranged so as not to rotate with the rotating drum 12.

The cathodes 13 and 14 are connected to the end faces 12a and 1
2b, the cathode main bodies 13a and 14a extend inside the rotary drum 12 from the inner surface. Cathode body 13a, 14
“a” has a linear shape, but is inclined so as to be located lower toward the tip. That is, the angle θ between the extending direction of the cathode main bodies 13 and 14 and the vertical direction is smaller than 90 °.

On the other hand, a plurality of electrode fingers 13b and 14b are respectively connected so as to extend downward from the cathode main bodies 13a and 14a. The plurality of electrode fingers 13b are uniformly distributed at a predetermined distance. Similarly, the plurality of electrode fingers 14b are also uniformly dispersed at a predetermined distance.

The plurality of electrode fingers 13b, 14b
Need not necessarily be uniformly distributed. The cathodes 13 and 14 are covered with insulating coating layers 15 and 16 except for the distal end portions of the electrode fingers 13b and 14b.

Materials Constituting the Insulating Coating Layers 15 and 16
Is not particularly limited, and is formed by an appropriate insulating resin.
Can be achieved. Exposing the tip of the electrode fingers 13b and 14b
The portion that is ₁, 14b₁Toss
You.

In this embodiment, during barrel plating, the multilayer capacitor 1A on which the metal films 4 and 5 are formed and the energizing medium 18 are loaded into the rotating drum 12. Hereinafter, in the multilayer capacitor 1 of FIG. 1, the structure before the Ni plating films 6, 7 and the Sn plating films 8, 9 are formed is referred to as a multilayer capacitor 1A.

The current-carrying medium 18 is supplied to ensure electrical connection between the exposed portions 13b ₁ and 14b ₁ of the electrode fingers 13b and 14b and the metal films 4 and 5 of the multilayer capacitor 1A. As the energizing medium 18, a metal ball such as a steel ball can be suitably used. However, the material forming the energizing medium 18 is not limited to this, and a metal material other than steel may be used, and a material in which the surface of an insulating material is coated with a conductive film may be used. Good.
Further, the energizing medium 18 is not limited to a spherical shape, and may have another shape such as a polyhedron.

The feature of the present embodiment is that the surface 1 of the charged object in a state in which the energizing medium 18 and the multilayer capacitor 1A are charged.
7 and the exposed portions 13b ₁ , 14 of the electrode fingers 13b, 14b.
the distance between the lower end of the b ₁ when L, the exposed portion 1
When the length X of 3b, 14b is in the range of 0.5L to 1.0L and the diameter of the energizing medium 18 is A, the width of the exposed portions 13b, 14b is set to 5A or more and 30A or less. Is to be.

In other words, in the above-described state, barrel plating is performed with the energizing medium 18 and the multilayer capacitor 1A being supplied so that the length and width of the electrode finger exposed portions 13b and 14b are within the above-described specific ranges. Will be

In this embodiment, the rotating drum 1 under the above conditions is used.
2 is immersed in a plating solution tank (not shown).
While rotating 2, an electric current is passed between the anode and the cathodes 13 and 14 in a plating solution tank (not shown). As a result, the multilayer capacitor 1A is sufficiently agitated together with the energizing medium 18, and a plating film with small thickness variation is reliably formed on the metal films 4 and 5. This will be described based on specific experimental examples.

A ceramic sintered body 2 having a plurality of internal electrodes 3a to 3f laminated via a ceramic layer and having an outer diameter of 1.6 × 0.8 × 0.8 mm was prepared. Ag paste was applied to the outer surface of the ceramic sintered body 2 and baked to form metal films 4 and 5 having a thickness of about 50 μm.

As described above, a multilayer capacitor 1A having the metal films 4 and 5 formed thereon was prepared. The multilayer capacitor 1A is placed in a rotating drum 12 together with steel balls having a diameter of 1.0 mm as an energizing medium 18.
2 is energized while rotating at a rotational speed of 12 rpm for 50 minutes,
Barrel plating was performed. Thus, a Ni plating film was formed on the metal films 4 and 5.

Next, after cleaning, the plating solution was changed and
Similarly, a Sn plating film was formed. Ni plating film
And when forming the Sn plating film, as shown in Table 1 below.
As shown in FIG.
Surface 17 of the charged material and exposed portion 13b₁, 14
b₁Exposed portion 13 with respect to the distance L from the lower end of
b ₁, 14b₁And the diameter A of the current-carrying medium 18
Exposed portion 13b₁, 14b₁Width ratio and cathode
Variously changing the inclination angle θ of the main body with respect to the vertical direction,
A Ni plating film and a Sn plating film were formed.

[0037]

[Table 1]

Each of the multilayer capacitors 1 obtained under the conditions 1 to 6 was cut, and the average thickness of the plating film was measured. In this case, the average value of the thicknesses of the plating films of the fifty multilayer capacitors was determined and defined as the average plating thickness. Further, a difference R _MAX -R _MIN between the maximum thickness R _MAX of the plating film and the minimum thickness R _MIN of the 50 multilayer capacitors 1 was obtained. The results are shown in Table 2 below and FIG. Note that the thickness of the plating film refers to the sum of the thickness of the Ni plating film and the thickness of the Sn plating film.

[0039]

[Table 2]

As is clear from Table 2 and FIG.
In the multilayer capacitor 1 obtained in (1) to (3), while the thickness variation of the plating film, that is, R _MAX −R _MIN is very large, that is, when plating is performed under the conditions 4 to 6 which fall within the scope of the present invention, the plating film It can be seen that the thickness variation of the sample is significantly reduced.

This is because the exposed portions 13b ₁ and 14b ₁
By setting the length and width within the range of the present invention, the multilayer capacitor 1A and the steel balls are sufficiently stirred, and the metal films 4 and 5 are stably contacted with the exposed portions 13b ₁ and 14b _1. It is considered that the plating films are stably formed on the metal films 4 and 5 of the large number of multilayer capacitors 1 </ b> A that have been supplied.

(Embodiment 2) Under the conditions 4 to 6 of the embodiment 1,
End surface 1 of rotating drum 12 of cathode body portions 13a and 14a
2a and 12b are 5 ° and 10 °, respectively.
And 15 °, but the Ni plating film and the Sn plating were formed on the metal films 4 and 5 of the multilayer capacitor 1A in the same manner as in Example 1 except that the angle θ was variously changed as shown in Table 3. A film was formed. Thus, various multilayer capacitors 1 were obtained.

[0043]

[Table 3]

For comparison, a plated film was formed and a multilayer capacitor was obtained in the same manner as in Example 2 except that the conventional barrel plating apparatus shown in FIG. 5 was used. For each of the multilayer capacitors obtained as described above, the average plating thickness and the thickness variation R _MAX -R _MIN of the plating film were measured in the same manner as in Example 1. The results are shown in Table 4 and FIG.
Shown in

[0045]

[Table 4]

As is clear from Table 4 and FIG. 4, under the conditions 7 to 9 where the inclination angle θ is set to 40 ° or more, compared to the comparative example using the barrel plating apparatus shown in FIG.
It can be seen that the thickness variation of the plating film can be significantly reduced.

Further, it can be seen that in the multilayer capacitor 1 obtained under the conditions 7 to 9, the thickness variation of the plating film is further smaller than that of the multilayer capacitor 1 obtained under the conditions 4 to 6 of the first embodiment.

This is because the multilayer capacitor 1A is placed above the cathode main bodies 13a, 14a because the inclination angle θ between the cathode main bodies 13a, 14b and the end faces 12a, 12b is in the range of 40 to 60 °. It is considered that even if the main body 13a and 14a move, the cathode main bodies 13a and 14a are inclined and therefore fall quickly. That is, the cathode body 13a,
14a is small, the cathode body 13
a and 14a may remain on the laminated capacitor 1A for a certain period of time and may not be sufficiently plated. On the other hand, in the present embodiment, since the inclination angle θ is large, the laminated capacitor 1A is large. This is because 1A falls quickly.

In the first and second embodiments, the multilayer capacitor 1A is prepared as an electronic component, and the plating films are formed on the metal films 4 and 5 of the multilayer capacitor 1A. The method for manufacturing a component can be used for a method for manufacturing a multilayer ceramic electronic component other than the multilayer capacitor, for example, a multilayer varistor or a multilayer thermistor. Further, the present invention can be similarly applied to a method of manufacturing a ceramic electronic component other than the laminated type and an electronic component using a material other than the ceramic. That is, the manufacturing method according to the present invention can be generally applied to the manufacture of an electronic component in which an electrode formed by laminating a plating film on a metal film is formed on the outer surface.

[0050]

According to the method of manufacturing an electronic component according to the first aspect of the present invention, the first and second cathodes are formed of the cathode body and the plurality of electrode fingers extending downward from the lower surface of the cathode body. Have
Since the length and width of the exposed portions of the electrode fingers are in the above-described specific ranges, when the rotating drum is rotated and energized, and the barrel plating is performed, the electronic component and the energized medium are sufficiently stirred, In addition, the metal film on the surface of the electronic component is reliably electrically connected to the cathode, thereby making it possible to stably form a plating film with small thickness variations.

According to the second and third aspects of the present invention, the first,
The second cathode has a cathode main body and a plurality of electrode fingers, and the direction in which the cathode main body extends is 40 degrees with respect to the vertical direction.
When the barrel is plated while rotating the rotating drum, even if the electronic component moves onto the cathode main body, the electronic component is quickly inclined due to the inclination of the cathode main body. Falls into the plating solution below. Therefore, all the electronic components are reliably electroplated because the electronic components are not positioned on the cathode body for a long time. Therefore, it is possible to provide an electronic component with less variation in the thickness of the plating film.

[Brief description of the drawings]

FIGS. 1A and 1B are views showing a barrel plating apparatus used in a first embodiment of the present invention;
(A) is a perspective view, (b) is a longitudinal sectional view for explaining a barrel plating state.

FIG. 2 is a longitudinal sectional view showing the multilayer capacitor manufactured in the first embodiment of the present invention.

FIG. 3 is a view showing thickness variations of plating films formed under various conditions in the first embodiment.

FIG. 4 is a view showing thickness variations of plating films formed under various conditions in the second embodiment.

FIG. 5 is a longitudinal sectional view for explaining a conventional barrel plating apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Multilayer capacitor as an electronic component 2 ... Ceramic sintered body 3a-3f ... Internal electrode 4, 5 ... Metal film 6, 7 ... Ni plating film 8, 9 ... Sn plating film 10a, 10b ... External electrode 11 ... Barrel plating 12 ... rotary drum 12a, 12b ... end surface 13, 14 ... first, second cathode 13a, 14a ... cathode body portion 13b, 14b ... electrode finger 13b _1, 14b ₁ ... exposed portion 15, 16 ... insulating coating layer 18 ... Electrification medium

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // C25D 3/12 C25D 3/30 3/30 H01G 1/14 VF term (Reference) 4K023 AA12 AA17 4K024 AA03 AA07 AB02 BB09 CB02 CB06 DA10 5E001 AB03 AC04 AE02 AE03 AH07 AJ03 5E082 AA01 AB03 BC38 EE04 EE23 EE35 FF05 FG06 FG26 GG10 GG11 GG28 PP09 PP10

Claims (3)

[Claims] 1. A method for manufacturing an electronic component, wherein an external electrode is formed on an outer surface, and the external electrode has a laminated structure of a metal film and a plating film formed on the metal film by wet barrel plating. A step of preparing an electronic component having a metal film formed on an outer surface thereof; anda step of forming a plating film on a outer surface of the metal film with a barrel plating device. A cylindrical rotating drum, and first and second cathodes arranged so as to extend into the drum from both ends of the rotating drum, and configured to not rotate with the rotation of the drum, The first and second cathodes extend from the end of the rotating drum to the inside of the rotating drum, a plurality of electrode fingers extending downward from the lower surface of the cathode body, and exposing the tips of the electrode fingers. , The electrode And an insulating coating layer covering the cathode main body portion, and the exposed portion of the electrode finger from the surface of the charged material when the electronic component and the energizing medium are charged into the rotating drum. When the length to the tip is L, the length of the electrode finger exposed portion is in the range of 0.5 L to 1.0 L, and when the diameter of the energizing medium is A, the electrode finger exposed portion is A width of 5A or more and 30A or less. 2. A method for manufacturing an electronic component, wherein an external electrode is formed on an outer surface, and the external electrode has a laminated structure of a metal film and a plating film formed on the metal film by wet barrel plating. And a step of preparing an electronic component having a metal film formed on an outer surface thereof, and a step of forming a plating film on a outer surface of the metal film by a barrel plating device. A rotary drum, and first and second cathodes positioned so as to extend inward from both ends of the rotary drum and arranged so as not to rotate with the rotary drum. The cathode has a cathode body and a plurality of electrode fingers extending downward from the cathode body, and the direction in which the cathode body extends is 40 degrees with respect to the vertical direction.
A method for producing an electronic component, characterized in that a component configured to form an angle of up to 60 ° is used. 3. A rotary drum comprising: a cylindrical rotary drum; and first and second cathodes positioned so as to extend inward from both ends of the rotary drum, and arranged so as not to rotate with the rotary drum. The first and second cathodes each have a cathode main body and a plurality of electrode fingers extending downward from the cathode main body, and the direction in which the cathode main body extends is 40 degrees with respect to the vertical direction.
A barrel plating apparatus characterized in that the barrel plating apparatus is configured to form an angle of up to 60 °.