JP2003007566A - Laminated electronic components - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a laminated electronic component which can be applied to high-speed mounting by improving capacitance and miniaturizing. A laminate comprising a pair of external electrodes connected to the internal electrode layer is formed on a rectangular parallelepiped electronic component body in which dielectric layers and internal electrode layers are alternately laminated. In the electronic component, the external electrode 9 is formed in an annular shape so as to surround the outer peripheral surface 7 of the electronic component body 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated electronic component, and more particularly to a laminated ceramic capacitor having dielectric layers and internal electrode layers alternately laminated.

[0002]

2. Description of the Related Art With the recent miniaturization of information communication equipment represented by computers and mobile phones, high-density mounting of electronic parts is progressing. For example, a monolithic ceramic capacitor which is one of multi-layer electronic parts. Then, as shown in FIG.
In response to the demand for smaller size and higher capacity, the dielectric layer 61 and the internal electrode layer 63 are thinned to form a highly laminated electronic component body 65 with the number of laminated layers exceeding 200 layers. It is known that the external electrode 67 is provided so as to face the end portion including the end surface of the main body 65.

Regarding the formation position of the external electrode 67,
For example, the one disclosed in Japanese Patent Laid-Open No. 5-55084 is known. In the multilayer electronic component disclosed in this publication, as shown in FIG. 6, the internal electrode layers 71 divided into two groups are alternately laminated with a dielectric layer 73 interposed therebetween to form an electronic component main body 75. The electrode 77 is provided on a single surface perpendicular to the internal electrode layer 71, and since such a multilayer electronic component can be erected on the external circuit board, the mounting density on the external circuit board can be increased. .

In the field of electronic equipment in recent years, high-speed mounting has been rapidly progressing for the purpose of improving productivity. For example, as shown in FIG. 7A, a chip-shaped laminated electronic component can be mounted in any direction. In a parts feeder, align them, and then pick them up with a suction nozzle or the like to set them at a predetermined position on the circuit board, or as shown in FIG. It is called a magazine case), and one method / pitch is pushed up from the bottom of the magazine case with a stick and then sucked up by the suction nozzle pin on the mounting part side and set at a predetermined position on the circuit board. Has been planned.

[0005]

However, in the conventional laminated electronic component as shown in FIG. 5, in order to increase the bonding strength of the external electrode 67 and the moisture resistance, the edge including the end face of the laminated electronic component is increased. Since the external electrode 67 is thickly formed in the portion, the external electrode 67 facing the laminated electronic component
In such a laminated electronic component, it is necessary to reduce the volume of the electronic component main body 65 due to the thickness of the external electrode 67, which reduces the capacitance per unit volume. There was a problem.

Further, in order to maintain insulation between the opposing external electrodes 67, it is necessary to increase the end margin portion on the end face side where the external electrodes 67 are formed, so that the effective area of the internal electrode layer 63 is reduced. There is a problem that the capacitance per unit volume also decreases in this case.

Further, when the multilayer electronic component having the external electrode 67 thickly formed on the end face is mounted on the external circuit board, the uneven heat shrinkage of the solder or the conductive adhesive used as the bonding agent is caused. In addition, there is a problem that a Manhattan phenomenon occurs in which the laminated electronic component stands up and one of the external electrodes 67 is separated from the external circuit board.

Further, when the chip-shaped laminated electronic component is mounted at a high speed by the method as described above, since the external electrode 67 is formed in a rounded shape on the end face of the electronic component main body 65, the mounting machine is used. There is a problem that the stacking type electronic component is obliquely arranged due to the displacement of the suction position, and the mounting yield is reduced, and the mounting speed is reduced when the mounting accuracy is increased.

Further, since the laminated electronic components are highly laminated in order to reduce the size and the capacity, the shape becomes easy to roll,
Moreover, when the external electrode is formed only on one side surface of the electronic component body as in the laminated electronic component disclosed in Japanese Patent Application Laid-Open No. 5-55084, it is mounted on the external circuit board using a high-speed mounting machine. When doing so, it is necessary to previously arrange the external electrode surface of the multilayer electronic component so as to be aligned with the bonding surface of the external circuit board, which causes a problem that the tact of the mounting process is delayed and the mounting cost is increased. there were.

Therefore, it is an object of the present invention to provide a multilayer electronic component which can be applied to high-speed mounting by improving the capacitance and downsizing.

[0011]

A laminated electronic component of the present invention comprises a pair of internal electrode layers connected to a rectangular parallelepiped-shaped electronic component body formed by alternately laminating dielectric layers and internal electrode layers. In the multilayer electronic component formed by forming the external electrode of
The external electrode is formed in an annular shape so as to surround the outer peripheral surface of the electronic component body.

According to this structure, since the external electrodes are not formed on the opposite end faces of the rectangular parallelepiped-shaped electronic component body, the end margin portion on the end face side can be made small, and only the thickness of the external electrodes is required. Since the dimensions of the electronic component body can be increased, for example, in the case of a laminated ceramic capacitor, the effective area of the internal electrode layers is increased, and the capacitance per unit volume can be improved.

Further, since no external electrode is formed on the end face of the electronic component body on the extension line of the internal electrode, no adhesive such as solder or conductive adhesive is attached to the end face of this laminated electronic component, and the external circuit board is not attached. It is possible to prevent the so-called Manhattan phenomenon when mounted on the board, and to improve the mounting yield.

Further, since there is no external electrode and the end surface of the electronic component body on the extension line of the internal electrode is flat, the shape of the laminated electronic component is maintained in a rectangular parallelepiped shape and the dimensional accuracy is improved. It becomes easier to align in the loading section, and it is possible to prevent diagonal disposition and displacement during mounting, and to improve the mounting yield.

Further, since the external electrode is formed in a ring shape so as to surround the outer peripheral surface of the electronic component body, when the external electrode is mounted on the external circuit board by using the high-speed mounting machine, the external electrode is formed of the electronic component body 1. Unlike the case where it is formed only on the side surface, it is not necessary to arrange the external electrode surface to match the bonding surface of the external circuit board in advance, and since it can be loaded in any direction, the tact of the mounting process can be made faster and the mounting cost can be reduced. It can be reduced.

In the above laminated electronic component, it is desirable that the radius of curvature R of the ridge portion of the electronic component body is 80 μm or less. In this way, by reducing the radius of curvature of the ridge of the electronic component body, even if the external electrode is formed to surround the outer peripheral surface, the main surface and side surfaces of the multilayer electronic component become flat surfaces and within the loading section. It is possible to prevent the rolling and the positional deviation, and further improve the mounting accuracy.

In the above laminated electronic component, when the thickness of the external electrode formed on the ridge portion of the electronic component body is t ₁ and the thickness of the flat portion excluding the ridge portion is t ₂ , t ₁ / t ₂ > 0 .5
It is desirable to satisfy the relationship.

By reducing the thickness difference of the external electrodes along the surface shape of the electronic component body, the flatness of the main surface and the side surface of the multilayer electronic component is enhanced, and the mounting accuracy can be further improved.

In the above-mentioned laminated electronic component, it is desirable that the relationship of L / S <2.5 is satisfied, where L is the length of the longest side and S is the length of the shortest side.

Further, in the multilayer electronic component of the present invention, the external electrodes are formed so as to surround the outer peripheral surface of the electronic component main body except the end face of the electronic component main body, so that the external circuit board can be formed on any side surface of the multilayer electronic component. Therefore, the Machtan phenomenon at the time of mounting can be prevented even for a laminated electronic component having a shape in which each side is close to each other and is easily rolled.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The multilayer electronic component of the present invention is applied to, for example, a multilayer ceramic capacitor as shown in FIG.

This laminated electronic component has an outer peripheral surface 7 of both end portions 5 of the rectangular parallelepiped-shaped electronic component body 1 excluding both end faces 3 in the longitudinal direction.
A pair of annular external electrodes 9 are provided so as to be spaced apart from each other. In other words, the outer electrodes 9 are formed by winding the strip-shaped conductor film around both ends 5 of the electronic component body 1. That is, the external electrode 9 is formed by forming an annular conductor film on the side surface of the electronic component body 1 where the main surface of the electronic component body 1 is perpendicular to the internal electrode layer and the side margin is formed. That is, the conductor film is continuously formed on the four surfaces of the electronic component body. The external electrodes 9 may be formed so as to surround the outer peripheral surfaces of both ends of the electronic component body 1 excluding both end faces in the width direction.

Since the external electrodes 9 are not provided on the opposite end surfaces of the electronic component body 1 in this manner, the margin portion on the side of the end face 3 can be made small and the size of the electronic component body 1 by the thickness of the external electrode 9. Since the capacitance can be increased, the capacitance per unit volume of the monolithic ceramic capacitor can be improved. The margin means a peripheral portion of the dielectric layer in which the internal electrode layer is not formed.

As shown in FIG. 2, at least two single surfaces of the electronic component body 1 on which the external electrodes 9 are formed intersect with each other, that is, on the side surfaces perpendicular to the upper and lower surfaces parallel to the internal electrode layers. The formed ridge line portion 11 has a radius of curvature R of 80 μ.
It is preferably m or less. And this radius of curvature R
In order to prevent chipping of the electronic component body 1 and to facilitate handling, it is particularly desirable that the thickness be 50 to 80 μm.

Regarding the thickness of the external electrode 9, the thickness of the ridge line portion 11 is t ₁ and the thickness of the flat surface portion 13 excluding the ridge line portion 11 is t ₂ in the AA ′ sectional view of the multilayer electronic component. At this time, it is desirable to satisfy the relationship of t ₁ / t ₂ ≧ 0.5. This t ₁ / t ₂ is the ridge line portion 11 of the external electrode 9.
The range of 0.5 to 1 is desirable for the reason of increasing the conductivity and the bonding strength and preventing chipping. The thickness t ₁ of the ridge portion 11 means the maximum distance from the ridge portion 11 of the electronic component body to the surface of the external electrode 9.

The electronic component body 1 is formed by alternately laminating dielectric layers 15 and internal electrode layers 17, and insulating layers 19 made of the same material as the dielectric layers 15 are formed on both surfaces in the laminating direction. There is.

In this electronic component body 1, when the longest side formed by the main surface and the side surface is L and the shortest side formed by the main surface and the end surface is S, L / S≤2.5. It is desirable to satisfy L, especially because of its small size and high lamination.
/ S is preferably used in the range of 1.5 to 2.5.

The number of laminated electronic component bodies 1 is at least 2 in order to achieve a compact and high capacity of laminated electronic components.
00 layers or more is desirable.

Further, the thickness of the dielectric layer 15 constituting the laminated electronic component is preferably 5 μm or less for the reason that it is made thin and multi-layered in order to make the laminated electronic component small in size and high in capacity.
The thickness of the dielectric layer 15 is preferably 0.5 to 4 μm because of its high dielectric constant and high insulation.

As shown in FIG. 3, the internal electrode layers 17 constituting the electronic component body 1 face the both surfaces of the dielectric layer 15 and face the first internal electrode layers 17a and the second internal electrode layers 17b.
And are formed alternately.

Further, these internal electrode layers 17a, 17b
The capacitor forming portion 21 is formed on almost the entire surface of the dielectric layer 15, and the end surface of the internal electrode layer 17 is exposed on both side surfaces of the electronic component body 1 on the side edge 22 side in a continuous manner with the capacitor forming portion 21. A pair of drawer portions 23 are formed.

These internal electrode layers 17 are the end margin portions 2 for insulating the external electrodes facing the end face side of the electronic component body, like the conventional monolithic ceramic capacitor.
Since there is almost no need to provide 7, the dielectric layer 1
5 can be widened toward the end face 3 side, and the effective area of the internal electrode layer 17 can be increased.

Then, the electronic component body 1 of the lead-out portion 23
The portion exposed on the side surface 24 of is electrically connected to the external electrode 9.

A plurality of the lead-out portions 23 may be formed, and the plurality of lead-out portions 23 arranged evenly on one side edge 22 of the capacitance forming portion 21 reduces the inductance of the monolithic ceramic capacitor. Desirable for reasons.

Further, in the laminated electronic component of the present invention, since the external electrode 9 is formed in an annular shape so as to surround the outer peripheral surface 3 of the electronic component main body 1, the lead-out portion 23 is formed of the internal electrode layers 17a and 17b. It may be formed only on one side edge.

Further, the width W of the lead-out portion 23, that is, the width of the lead-out portion 23 in the direction of the opposing external electrode 9 is preferably 50 μm or more for the reason that the external electrode 9 can be reliably connected, and the adjacent external electrode It is desirable that the thickness is 100 to 200 μm for the reason that it is possible to maintain the distance to insulate from 9.

Here, the internal electrode layer 17 including the lead-out portion 23
When the areas of a and 17b are A1 and the area of the dielectric layer 15 is A2, the occupied area ratio of the internal electrode layers 17a and 17b is
Because the effective area is increased and the capacitance is improved,
It is desirable to satisfy the relationship of A1 / A2 ≧ 0.8.

As described above, in the monolithic ceramic capacitor, the internal electrode layers 17a and 17 with respect to the area of the dielectric layer 15 are formed.
The larger the area of b is, the higher the capacitance can be. However, the internal electrode layer 17 of the counter electrode adjacent in the thickness direction is formed.
b, 17a, the occupied area ratio is 0.8 to 0.
A range of 9 is desirable.

Further, the thickness of the internal electrode layer 17 is preferably 2 μm or less, and in order to reduce the amount of metal contained in the internal electrode layer 17 and to secure a sufficient effective area, in particular, 1 to 1. It is preferably 5 μm.

As the material of the dielectric layer 15 and the insulating layer 19 in the laminated electronic component of the present invention, a dielectric ceramic such as barium titanate ceramic is used.

Further, the electrode material forming the internal electrode layer 17 is not particularly limited, and Ag, Ag-Pd, N.
A material containing a suitable metal such as i or Cu as a main component is used, and either one formed from a conductor paste or one formed by plating is used.

Similarly, the material forming the external electrode 9 is not particularly limited, and Ag, Ag-Pd, Ni, Cu,
An appropriate metal material such as Sn can be used. The external electrode 5 is formed by applying a conductive paste and then baking it at a high temperature. In addition to a conductive paste prepared by dispersing a metal powder in a thermosetting resin, the external electrode 5 is cured at a relatively low temperature. Can also be formed.

This external electrode paste is shown in FIG.
It is applied to the end of the electronic component body 1 by the method shown in (a), (b), and (c).

First, as shown in FIG. 4A, the electronic component body 1 is loaded on the carrier plate 31 so that the end portions of the electronic component body 1 project.

Next, as shown in FIG. 4B, the carrier plate 31 is placed on the paste tray 33 so that the end surface of each electronic component body 1 abuts on the projection 35 formed on the paste tray 33.

Next, as shown in FIG. 4 (c), the external electrode paste 37 is poured from the left side of the paste tray 33, and the outer peripheral surface 7 of the end portion 5 of the electronic component body 1 excluding the end surface 3 is filled.
The external electrode paste 37 is applied to.

Next, the external electrode paste 37 collected in the paste tray 33 is extracted, and then the carrier plate 31 is removed from the paste tray 33 and the electronic component body 1 is removed.
The external electrode paste 37 formed on the end 5 is dried.

After drying, the external electrode paste 37 is applied to the other end by the same method.

The external electrode paste used at this time needs to have an appropriate viscosity characteristic in order to uniformly apply the external electrode paste to the outer peripheral surface 3 of the electronic component body 1 including the ridge portion 11. In particular, it has thixotropic properties, and, for example, in a shear rate range of 10 to 100 s ^-1 , it is desirable that the viscosity is 100 to 500 Pa · s. The viscosity of the external electrode paste is preferably 200 to 400 Pa · s so as to be in the range of 0.5 to 1 times.

[0050]

Example A monolithic ceramic capacitor, which is one of multi-layer electronic components, was manufactured as follows.

First, 97.5 mol% of BaTiO ₃ and C
Synthetic resin such as polyester or polypropylene is prepared by adding a ceramic slurry having a composition in which 0.5 mol part of Y ₂ O ₃ is added to 100 mol parts of a main component consisting of 2.0 mol% aZrO ₃ and 0.5 mol% MnO. A band-shaped ceramic green sheet having a thickness of about 3 μm was obtained by forming a film by a doctor blade method on the band-shaped carrier film made of, and drying the film. Then, the ceramic green sheet was peeled from the carrier film, and the length was 200 mm.
It was punched into a size of 200 mm in width.

Then, 45% by weight of Ni powder, 5.5% by weight of ethyl cellulose and α-terpineol 94.
55 wt% of vehicle consisting of 5 wt% was kneaded with a three-roll mill to prepare a conductive paste for internal electrode layers.

Next, a conductive paste is printed on one main surface of the ceramic green sheet by using a screen printing device to form an internal electrode pattern having a pair of lead portions formed on opposite side edges of the ceramic green sheet. did.
In this case, the occupied area ratio A1 / A2 of the internal electrode pattern to the ceramic green sheet was 0.8, and the width W of the lead portion was 150 μm mm.

Next, 200 ceramic green sheets having this internal electrode pattern were laminated to obtain a laminated compact.

Then, the appearance of 100 laminated molded bodies thus produced was observed with a binocular microscope to check for cracks, and it was confirmed that no cracks were generated in any of them.

Thereafter, this laminated molded body was placed in the atmosphere at 40
The mixture was heated at a temperature of 0 ° C., the binder was burned, the mixture was baked at 1250 ° C. for 2 hours in a reducing atmosphere, and then reoxidized at 900 ° C. in a nitrogen atmosphere to obtain an electronic component body.

Next, the surface of the electronic component body was polished using a barrel polishing machine. In this case, the radius of curvature of the ridge of the electronic component body was adjusted by changing the barrel polishing time.

Next, an external electrode paste was prepared. The external electrode paste contains 80% by weight of Cu powder and 2% of glass powder.
6% by weight of cellulose as a binder and α-terpineol as a solvent were added to a solid content of 0% by weight, and a small amount of a dispersant was further added to control the viscosity characteristics.

Next, the external electrode paste containing Cu as a main component is applied by the above-described application method, and a pair of external electrode films are annularly separated so as to surround the outer peripheral surface of the electronic component body except the end surface. Formed. That is, the external electrode film was continuously formed on the four surfaces of the electronic component body.

Thereafter, oxygen gas was introduced at 900 ° C. under a nitrogen atmosphere to form external electrodes electrically connected to the internal electrode layers, and the multilayer ceramic capacitor shown in FIGS. 1 and 3 was obtained. At this time, the width of the external electrodes was 200 μm, and the distance between the pair of external electrodes was 1.1 mm.

The monolithic ceramic capacitor has an external dimension
Normal ratio (L / S), radius of curvature R of ridge, thickness of external electrode
Ratio (t₁/ T₂) Was changed and produced. The external dimension ratio
Was adjusted by changing the thickness of the insulator layer. In addition, the external electrode
Thickness ratio t between the ridge and the plane ₁/ T₂Is the external electrode paste
The viscosity was adjusted and controlled by the amount of the solvent and the dispersant therein.

Next, the capacitance of each of the 100 obtained multilayer ceramic capacitors was measured under the conditions of a measurement frequency of 1 kHz, an applied voltage of 1 Vrms, and a temperature of 25 ° C.

Similarly, for each of the obtained 100 laminated ceramic capacitors, solder was used as a bonding agent, and a high-speed mounting machine was used to carry out a mounting test on an external circuit board.

As the external circuit board, a glass epoxy board having a copper foil pad with a diameter of 0.5 mm formed at mounting positions equidistant to a pair of external electrodes formed in the L dimension of the monolithic ceramic capacitor. Using.

Since the amount of positional deviation after mounting varies depending on the shape of the external electrodes and the dimensional accuracy of the multilayer electronic component, the amount of positional deviation after mounting and mounting defects such as the Manhattan phenomenon were evaluated. The displacement amount was obtained by measuring the displacement of the monolithic ceramic capacitor from the center of the copper foil pad having a diameter of 0.5 mm formed on the external circuit board using a measuring microscope and determining the average value thereof.

As a comparative example, the conventional monolithic ceramic capacitor of FIG. 5 in which the external electrodes were formed at the end portions including the opposite end faces of the electronic component body was prepared, and the same characteristic evaluation as that of the monolithic ceramic capacitor of the present invention was made. In addition, a mounting test was conducted, and the results were used as the sample It was described in 10, 11. still,
The external dimensions of the electronic component body that constitutes the comparative example and the monolithic ceramic capacitor of the present invention were the same. The results are shown in Table 1.

[0067]

[Table 1]

As is clear from the results shown in Table 1, the sample No. in which the external electrode was not formed on the end face of the electronic component body was used. 1 to
In No. 9, the displacement during mounting was as small as 89 μm or less, and there was no mounting failure due to the Manhattan phenomenon. Particularly, the sample N in which the radius of curvature of the ridge of the electronic component body is 50 to 80 μm
o. In Nos. 3 to 5, the amount of misalignment was 45 μm or less, which was even smaller. And, the sample No. in which the external dimension ratio (L / S) of the monolithic ceramic capacitor was reduced to 1.5. Also in No. 8, there was no mounting failure due to the Manhattan phenomenon.

On the other hand, sample No. In Nos. 10 and 11, since the external electrodes were formed at the end portion including the end surface of the electronic component body, the amount of misalignment was increased due to the non-uniform adhesion amount of the bonding agent solder and thermal contraction, and the Manhattan phenomenon There were many mounting defects.

[0070]

As described above, in the multilayer electronic component of the present invention, the external electrodes are formed so as to surround the outer peripheral surface of the electronic component body excluding the end faces, so that the dimension in the direction of the opposing external electrodes is reduced. The internal electrode layer formed on almost the entire surface of the dielectric layer can narrow the margin on the end face side connected to the external electrode, increasing the effective area of the internal electrode layer and increasing the capacitance per unit volume. You can

When such a laminated electronic component is mounted on an external circuit board, the laminated electronic component rises due to uneven heating and shrinkage of the bonding agent such as a conductive adhesive,
It is possible to eliminate the Manhattan phenomenon in which one external electrode is separated from the external circuit board.

Furthermore, in such a laminated electronic component,
Since the end face is flat without external electrodes and the laminated electronic component is rectangular, it is easy to align in the loading section in the mounting machine, the laminated electronic component is arranged diagonally, and the suction position on the mounting machine is It is possible to prevent the displacement and improve the mounting yield.

[Brief description of drawings]

FIG. 1 is a perspective view showing a laminated electronic component of the present invention.

FIG. 2 is a cross-sectional view showing the thickness of the ridge line portion of the electronic component body and the external electrode taken along the line AA ′ in FIG.

FIG. 3 is a plan view showing internal electrode layers formed so as to face each other in the multilayer electronic component of the present invention.

FIG. 4 is a schematic view showing a state in which an external electrode paste is applied to the outer peripheral surface of the electronic component body excluding the end surface.

FIG. 5 is a perspective view showing a conventional laminated electronic component in which external electrodes are formed on the ends including both end faces.

FIG. 6 is a perspective view showing a conventional multilayer electronic component having a pair of external electrodes formed on the same side surface.

FIG. 7A is an explanatory view showing a state in which laminated electronic components are continuously extruded from a parts feeder, and FIG. 7B is an explanatory diagram showing a state in which laminated electronic components are continuously extruded from a magazine case. is there.

[Explanation of symbols]

1, 65, 75 ... Electronic component body 7 ... 9, 67, 77 ... External electrodes 11 ... ridge 13 ... Flat surface 15, 63, 73 ... Dielectric layer 17, 61, 71 ... Internal electrode layers

Claims (4)

[Claims] 1. A laminated electronic component, comprising: a rectangular parallelepiped-shaped electronic component main body formed by alternately laminating dielectric layers and internal electrode layers, and forming a pair of external electrodes to which the internal electrode layers are connected. The multilayer electronic component, wherein the external electrode is formed in an annular shape so as to surround the outer peripheral surface of the electronic component main body. 2. The radius of curvature R of the ridge of the electronic component body is 80.
The laminated electronic component according to claim 1, wherein the laminated electronic component has a thickness of not more than μm. 3. The electronic component t ₁ the external electrode thickness formed on the ridge portion of the body, when the thickness of the flat portion excluding the ridge portion was t _2, the relationship of t ₁ / t ₂ ≧ 0.5 The multilayer electronic component according to claim 1 or 2, which is satisfied. 4. When the length of the longest side of the electronic component body is L and the length of the shortest side is S, the relationship of L / S ≦ 2.5 is satisfied. The laminated electronic component according to any one of the above.