JP2000021678A - Multilayer ceramic capacitors - Google Patents

Abstract

(57) [Problem] To provide an external terminal electrode on a pair of end surfaces of a laminate, there is no need to align the end surfaces on which the external terminal electrodes are formed. Provided is a multilayer ceramic capacitor which can be connected to electrodes and has a low inductance and a low impedance in a high frequency range. SOLUTION: The multilayer ceramic capacitor of the present invention comprises:
A substantially square dielectric ceramic layer 2 having a rectangular first internal electrode layer 3 formed thereon and a substantially square dielectric ceramic layer 2 having a rectangular second internal electrode layer 4 formed thereon are respectively laminated. At the same time, the first and second internal electrode layers 3 and 4 respectively extend to diagonal corners of the laminate 1 and a first external terminal electrode 5 is provided on one of a pair of end surfaces of the laminate 1. The other is a multilayer ceramic capacitor in which the second external terminal electrodes 6 are respectively formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a multilayer ceramic capacitor.

[0002]

2. Description of the Related Art Conventionally, as shown in FIGS. 6 and 7, a multilayer ceramic capacitor has a rectangular dielectric ceramic layer 62 having a substantially rectangular first internal electrode layer 63 formed thereon and a substantially rectangular first ceramic electrode layer 62 formed thereon. A first external terminal electrode 65 and a second external terminal electrode 66 are respectively provided on a pair of end faces of a laminated body 61 in which a rectangular dielectric ceramic layer 62 on which two internal electrode layers 64 are formed is laminated.
Had formed.

A first internal electrode layer 63 and a second internal electrode layer 64
7 (shown by dotted lines in FIG. 7) are arranged to face each other with a dielectric ceramic layer 62 interposed therebetween, as shown in FIG. The first internal electrode layer 63 extends, for example, to one end surface side (left end in FIG. 7) of the multilayer body 61 and is connected to the first external terminal electrode 65. Also, the second internal electrode layer 6
4 extends to, for example, the other end face side (the right end in FIG. 7) of the laminate 61 and is connected to the second external terminal electrode 66.

In general, the relationship between the dimension in the long side direction and the dimension in the short side direction of a multilayer ceramic capacitor is 3216 type (3.2 mm × 1.6 mm) or 1005 type (1.0 mm
× 0.5 mm) and so on.

[0005] Such a multilayer ceramic capacitor 60
Then, the internal electrode layer 6 disposed inside the laminate 61
3 and 64 have a rectangular shape extending in the longitudinal direction of the stacked body 61.

In the method of manufacturing such a multilayer ceramic capacitor, a green sheet serving as a dielectric ceramic layer 62 having a conductive film serving as a first internal electrode layer 63 and a conductive film serving as a second internal electrode layer 64 are formed. A green sheet to be the dielectric ceramic layer 62 and a green sheet to be the uppermost dielectric ceramic layer are prepared, and lamination and compression are performed according to the lamination order. Thereafter, the green sheet laminate is cut in accordance with the shape of the laminate 61, and the green sheet and the conductive film are integrally sintered. Thereafter, barrel end polishing is performed on the end face of the fired laminated body to completely expose the first internal electrode layer 63 or the second internal electrode layer 63 from the short side end face.

Then, a conductive film serving as a base thick film conductive film of the first external terminal electrode 65 and the second external terminal electrode 66 is formed on the pair of short side end surfaces of the laminate 61 by dipping or applying a conductive paste. Formed and baked, then
A surface plating layer such as Ni plating or solder plating is formed on the surface of the underlying thick conductor film.

[0008]

However, in the above-described multilayer ceramic capacitor, in the manufacturing process, among the four end faces of the laminate, the end face on which the external terminal electrode must be formed is a pair of short sides. Since this is an end face, the base face thick conductor film of the external terminal electrode should be formed on this face. It was necessary to align.

Further, structurally, the internal electrode layer has a shape elongated from one external terminal electrode side toward the other external terminal electrode film, and a portion facing the other internal electrode layer adjacent in the thickness direction is also elongated. As a result, the mutual inductance component of each internal electrode layer becomes large, so that there is a problem that the inductance and impedance in a high frequency range become large.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to form an external terminal electrode on a pair of end surfaces of a laminate and align the end surfaces on which the external terminal electrode is formed. An object of the present invention is to provide a multilayer ceramic capacitor which eliminates the need for connection between an internal electrode layer and an external terminal electrode, and can improve inductance and impedance in a high frequency range.

[0011]

SUMMARY OF THE INVENTION A multilayer ceramic capacitor according to the present invention has a substantially square dielectric ceramic layer having a first internal electrode layer formed thereon and a substantially square dielectric ceramic layer having a second internal electrode layer formed thereon. And a part of each of the first and second internal electrode layers is extended to a pair of diagonal corners, and the first and second internal electrode layers are formed at one end of the laminate facing each other. 1st external terminal electrode connected to 1 internal electrode layer,
A multilayer ceramic capacitor, wherein a second external terminal electrode connected to the second internal electrode layer is formed at the other end.

[0012]

According to the present invention, the dielectric porcelain layer is substantially square. The shape of the internal electrode layer also becomes a square shape or a substantially rectangular shape close to a square shape according to the shape of the dielectric ceramic layer.

The first and second internal electrode layers extend to a pair of corners located on a diagonal line of the substantially square dielectric ceramic layer, and the corners connect to the external terminal electrodes, respectively. Then, it is formed at an end portion including a pair of opposing end surfaces of a laminated body in which the dielectric ceramic layers are laminated.

As described above, since the internal electrode layers extend from the diagonal corners and the dielectric ceramic layer has a square shape, a pair of external terminal electrodes are covered on the laminate. In forming the attachment, the first and second external terminal electrodes may be formed at the ends so as to include a pair of opposed end surfaces of the laminate, or may be formed to include another pair of opposed end surfaces. Even if it is formed at the end, it can be reliably connected to the internal electrode layer.

In other words, in forming the external terminal electrodes, the conventional alignment step is not required.

Further, since the shape of the internal electrode layer is a square or a rectangle close to a square as compared with the conventional one, the coverage of the internal electrode layer deposited on the dielectric ceramic layer is improved. Therefore, a large-capacity multilayer ceramic capacitor can be easily obtained.

Further, since the size of the internal electrode layers in the long side direction can be reduced, the mutual inductance component of each internal electrode layer, and the inductance and impedance in a high frequency range can be reduced.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a multilayer ceramic capacitor according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is an external perspective view showing a multilayer ceramic capacitor of the present invention, FIG. 2 is a longitudinal sectional view of the multilayer ceramic capacitor of FIG. 1, and FIG. 3 is a relation between internal electrode layers and external terminal electrodes. FIG.

In the figure, 10 is a multilayer ceramic capacitor, 1 is a laminate, 2 is a dielectric ceramic layer, 3 is a first internal electrode layer, 4 is a second internal electrode layer, 5 is a first external terminal electrode, and 6 is a second external terminal electrode.

The laminate 1 includes a plurality of dielectric ceramic layers 2, a first internal electrode layer 3 disposed between the dielectric ceramic layers 2, and a second
The internal electrode layers 4 are alternately stacked.

The dielectric ceramic layer 2 is made of a dielectric material such as barium titanate and strontium titanate, and has a substantially square planar shape. Here, the square shape is a rectangular shape having four sides equal to each other, but the dielectric ceramic layer is subjected to sintering and sintering shrinkage and the like, and a complete square dielectric ceramic layer is realistic. Difficult. Therefore,
An approximate square shape refers to a shape that is as close as possible to a square shape.

The first internal electrode layer 3 and the second internal electrode layer 4
Noble metal material such as Pd or Ag-Pd alloy or N
It is made of a base metal material such as i, and has a substantially rectangular shape on the dielectric ceramic layer 2 and is formed in an island shape.

In FIG. 3, the first internal electrode layer 3 indicated by a solid line is extended from the corner of the substantially square dielectric ceramic layer 2 by the extended conductor film 3a of the first internal electrode layer 3. ing. Also, in FIG. 3, the second internal electrode layer 4 indicated by a dotted line
Are extended from the corners of the substantially square dielectric ceramic layer 2 located diagonally to the corners where the first internal electrode layers 3 extend by the extended conductor film 4 a of the second internal electrode layers 4. ing.
That is, in FIG. 3, the first internal electrode layer 3 extends to the upper left corner on the dielectric ceramic layer 2, and the second internal electrode layer 4 extends to the lower right corner on the dielectric ceramic layer 2. Is out.

First external terminal electrode 5, second external terminal electrode 6
Is formed on an end portion of the laminate 1 including a pair of opposing end surfaces. Here, the external terminal electrodes 5 and 6 are made of an underlying thick conductor film made of Ag or an Ag—Pd alloy, and an N material made of a material that is less likely to cause solder erosion on the surface of the underlying thick conductor film.
Sn or S on the i-plated layer and the Ni-plated layer
It is formed by depositing a plating layer made of a material such as an n-Pb alloy.

More specifically, the first external terminal electrode 5,
The second external terminal electrodes 6 are formed around a pair of end surfaces facing each other of the multilayer body 1 and near the ends of four surfaces (upper surface, lower surface, and both side surfaces of the multilayer body 1) adjacent to the end surfaces. ing.

Thus, the first internal electrode is formed at the diagonally upper corner of the laminated body 1 where the extended conductor film 3a of the first internal electrode layer 3 and the extended conductor film 4a of the second internal electrode layer 4 respectively extend. The layer 3 and the first external terminal electrode 5 are electrically connected to each other, and the second internal electrode layer 4 and the second external terminal electrode 6 are electrically connected to each other.

The multilayer ceramic capacitor 1 having the above structure
In the case of 0, the first internal electrode layer 3 and the second internal electrode layer 4 can be made as close as possible to a square shape as compared with the related art. Therefore, in the planar shape of the dielectric ceramic layer 2,
Since the occupation occupancy rate of the internal electrode layers 3 and 4 (the ratio of the facing area portions of the internal electrode layers 3 and 4) can be increased, a large-capacity multilayer ceramic capacitor can be realized.

At the same time, since the dimension in the long side direction can be shortened in the conventional art, the dimension in the short side direction can be increased, and the resistance components of the internal electrode layers 3 and 4 can be reduced. The mutual inductance component can be reduced, and in particular, the impedance component can be reduced in a high frequency band operation.

In FIG. 3, a first external terminal electrode 5 and a second external terminal electrode 6 are formed on the dielectric ceramic layer 2 constituting the laminated body 1, centering on the left and right end surfaces in the figure. .
However, even with the same laminate 1, as shown in FIG.
The first external terminal electrode 5 'and the second external terminal electrode 6' can be formed around an end face in the vertical direction in the drawing. This also allows the extension conductor film 3a of the first internal electrode layer 3 and the second conductor
The laminated body 1 in which the extended conductor films 4a of the internal electrode layers 4 respectively extend
Of the first internal electrode layer 3 and the first external terminal electrode 5 ′, the second internal electrode layer 4 and the second external terminal electrode 6 ′
Can be connected stably.

Here, the external terminal electrodes 5 and 6 are
Of the four end surfaces adjacent to this end surface, at least the two side surfaces on which the internal electrode layers 3 and 4 extend have external terminal electrodes 5 and 6 (with a width of at least about 100 μm from the end surface). It is important to form 5 ′, 6 ′). This is because the external terminal electrodes 5, 6 (5 ', 6') are formed on either the left or right end face of the laminate 1 as shown in FIGS. Extending conductive film 3 of first internal electrode layer 3 extending from a diagonal corner of body 1
a and the connection between the second internal electrode layer 4 and the extended conductor film 4a are stably connected even if a positional shift occurs in the manufacturing process, and the extended conductor film 3a, the extended conductor film This is to prevent the 4a from being exposed.

The multilayer ceramic capacitor 10 having the above structure
Is formed as follows.

First, three types of ceramic green sheets which are to be the dielectric ceramic layers 2 and include a plurality of element regions are prepared. The ceramic green sheet is formed by a known method, that is,
It can be formed by mixing a predetermined dielectric material, forming a slip, tape-forming the slip material with a doctor blade or the like, and forming a sheet of a predetermined size. The three types of ceramic green sheets are a first green sheet on which an internal electrode layer serving as an uppermost layer (or a lowermost layer, a margin layer) of the laminate 1 is not formed, and a first internal electrode layer 3 on one main surface.
A second green sheet on which a conductive film to be (second internal electrode layer 4) is formed, and a third green on which a conductive film to be second internal electrode layer 4 (first internal electrode layer 3) is formed on one principal surface It is a sheet.

Next, a conductor film to be the first internal electrode layer 3 (second internal electrode layer 4) is formed in each element region of the second green sheet (see FIG. 5). Specifically, the conductive paste is formed by printing and drying a conductive paste containing the above-described material for forming the internal electrode layer.

In FIG. 5, for example, the conductor film 31 formed so as to be aligned on the rightmost side is, for example, the first internal electrode layer 3.
The conductor film 41 formed so as to be aligned on the left side thereof is, for example, the second internal electrode layer 4 and the conductor film to be the extended conductor film 4a.

At the same time, a conductor film to be the second internal electrode layer 4 (first internal electrode layer 3) is formed in each element region of the third green sheet. In this sheet, for example, a conductor film formed so as to be aligned on the rightmost side is a conductor film serving as the second internal electrode layer 4 and the extended conductor film 4a, and a conductor film formed so as to be aligned on the left side thereof The film is a conductor film to be the first internal electrode layer 3 and the extended conductor film 3a.

That is, from the conductor films arranged in a substantially square shape, a conductor film serving as a conductor film extending along one diagonal line of the square element region is formed. The extended conductor film 3a of the first internal electrode layer 3 and the extended conductor film 4a of the second internal electrode layer 4 are common on this green sheet.

Next, in consideration of the order of lamination of the internal electrode layers 3 and 4 of the laminate 1, the above-described second green sheet and third green sheet are laminated, and the first green sheet and the third green sheet are laminated so that the conductive film is not exposed. The sheets are laminated and crimped to integrate. As a result, a large laminated body in an unfired state in which a plurality of element regions are integrated is formed.

Next, the large-sized laminate in an unfired state is cut into each element region, that is, a substantially square shape. Thereby, a laminate in an unfired state is formed.

Next, the unfired laminate is fired at a predetermined atmosphere and temperature to make the conductor film and the ceramic green sheet into an internal electrode layer and a dielectric ceramic layer.
Thereafter, if necessary, polishing is performed to completely expose the extended conductor films 3a, 4a of the internal electrode layers 3, 4 from the fired end faces. Thereby, the laminate 1 having a substantially square planar shape is formed.

Next, external terminal electrodes 5 and 6 are formed on the end including the pair of end surfaces of the laminate 1. At this time, the Ag face is placed near the end face of the laminate 1 and the end of the face adjacent to the end face.
Alternatively, a conductive film to be an underlying thick conductive film is formed by dipping or screen printing a conductive paste made of an Ag—Pd alloy, and a baking process is performed. Then, a Ni plating layer made of a material that is unlikely to be eroded by solder is formed on the surface of the underlying thick film conductor film, and a Sn plating layer is formed on this plating layer.
Alternatively, a plating layer made of a material such as a Sn—Pb alloy is formed.

In the manufacturing method described above, since the planar shape of the laminate 1 is square, the external terminal electrodes 5 and 6 are attached to the ends including the pair of end surfaces, as shown in FIGS. Alternatively, even if they are formed at a pair of end portions, they can be connected to the internal electrode layers 3 and 4 stably. This means that when forming the external terminal electrodes 5 and 6, an aligning operation for aligning predetermined end faces of the laminate 1 is not required, and the external terminal electrodes 5 and 6 may be formed on at least a pair of end faces. Therefore,
In forming the external terminal electrodes 5 and 6, the workability is greatly improved.

In measuring the capacitance characteristics and the like of the multilayer ceramic capacitor, two detection probes of the measuring device are set so as to be in contact with the diagonal portion of the multilayer body 1 on which the external terminal electrodes 5 and 6 are formed. If so, this probe can be always connected to the external terminal electrodes 5 and 6. That is, if the two probes are controlled so as to contact the upper left corner and the lower right in FIG. 3, respectively, the probe in the upper left corner can be brought into contact with the first external terminal electrode 5,
The probe at the lower right corner can be brought into contact with the second external terminal electrode 6. In FIG. 4, the probe at the upper left corner can be brought into contact with the first external terminal electrode 5 ′,
The probe at the lower right corner can be brought into contact with the second external terminal electrode 6 '.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the scope of the present invention.

[0045]

As described above, according to the present invention, since the laminate has no directivity, even if the external terminal electrodes are formed on a pair of end surfaces or on another pair of end surfaces, the internal electrode layer and the external terminal electrodes are formed. Can be connected stably. For this reason,
Alignment work or the like for forming external terminal electrodes is not required.

Further, since the shape of the internal electrode layer can be substantially square, low inductance and low impedance can be reliably achieved, and the application range of the multilayer ceramic capacitor is low inductance or low inductance in a high frequency range. Low impedance is possible.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a multilayer ceramic capacitor according to the present invention.

FIG. 2 is a cross-sectional view of the multilayer ceramic capacitor of the present invention.

FIG. 3 is a schematic diagram showing a relationship between an internal electrode layer and an external terminal electrode of the multilayer ceramic capacitor of the present invention.

FIG. 4 is a schematic diagram showing a relationship between internal electrode layers and external terminal electrodes in another embodiment of the multilayer ceramic capacitor of the present invention.

FIG. 5 is a plan view of a ceramic green sheet in a manufacturing process of the multilayer ceramic capacitor of the present invention.

FIG. 6 is an external perspective view of a conventional multilayer ceramic capacitor.

FIG. 7 is a schematic diagram showing a relationship between internal electrode layers and external terminal electrodes in the multilayer ceramic capacitor of FIG.

[Explanation of symbols]

 10 Multilayer ceramic capacitor 1 Multilayer 2 Dielectric ceramic layer 3 First internal electrode layer 4 Second internal electrode layer 5 · First external terminal electrode 6 ··· Second external terminal electrode

Claims (1)

[Claims] 1. A substantially square dielectric ceramic layer on which a first internal electrode layer is formed and a substantially square dielectric ceramic layer on which a second internal electrode layer is formed.
A first external terminal electrode that extends a part of each of the second internal electrode layers to a pair of diagonally opposite corners and connects to the first internal electrode layer at one of the opposing ends of the laminate; Wherein a second external terminal electrode connected to the second internal electrode layer is formed at the other end.