JP2000195742A - Laminated ceramic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify a process by reducing the number of capacitors mounted on a circuit board for improved mounting density. SOLUTION: The capacitor comprises a laminated body where at least 5 layers of almost rectangular dielectric ceramic layers are laminated, rectangular internal electrode layers 12-15 so provided between dielectric porcelain layers that a part of it is exposed from the end surface of the laminated body, four external electrodes 2-5 formed at each end surface of the laminated body as to be connected to the internal electrode layers 12-15. Here, each of internal electrode layers 12-15 is rotated by 90 deg. in constant direction, in the order of lamination.

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, a multilayer ceramic capacitor is composed of a first dielectric ceramic layer having a substantially rectangular first internal electrode layer and a dielectric ceramic layer having a substantially rectangular second internal electrode layer. In addition, a part of the first internal electrode layer and a part of the second internal electrode layer are laminated so as to extend in different directions from each other, and external electrodes are respectively formed on a pair of end surfaces where the internal electrode layers are exposed.

However, in such a multilayer ceramic capacitor, only one type of capacitance can be obtained between the external electrodes, and when a plurality of types of capacitance are required, a corresponding type of multilayer ceramic capacitor is required. Was.

For this reason, when a large number of capacitors are required as in a hybrid integrated circuit, a plurality of multilayer ceramic capacitors must be mounted on a circuit board. There was a problem of inviting. In addition, it is necessary to mount a plurality of multilayer ceramic capacitors, and there is a problem that the mounting operation is troublesome and complicated.

Therefore, as shown in FIGS. 7 and 8, a four-terminal multilayer ceramic capacitor has been proposed (JP-A-63-146422).

The multilayer ceramic capacitor 70 has a laminated body 71 in which a dielectric ceramic layer 80 on which internal electrode layers 81 to 87 are formed as shown in FIGS. It consisted of external electrodes 72 to 75 formed on the end faces.

The external electrode 72 is connected to a part of the internal electrode layers 81, 83, 85 and 87 shown in FIG. 8, and the external electrode 73 is connected to a part of the internal electrode layer 82 shown in FIG. The electrode 74 is connected to a part of the internal electrode layer 84 shown in FIG.
The external electrode 75 was connected to a part of the internal electrode layer 86 shown in FIG. That is, the internal electrode layers 81, 83, 8
5, 87 were used as reference electrodes and were arranged between every other layer of the dielectric ceramic layer 80. Note that a dielectric ceramic layer 80 serving as a margin layer is required above the internal electrode layer 81, but is omitted in FIG.

In this multilayer ceramic capacitor 70, internal electrode layers 81 and 82 are provided between an external electrode 72 and an external electrode 73 formed on an end face adjacent to the left side of the end face on which the external electrode 72 is formed. , 83 can be obtained.

An external electrode 72 and an external electrode 7 formed on an end face opposite to the end face on which the external electrode 72 is formed are provided.
4 and the second between the internal electrode layers 83, 84 and 85.
Can be obtained.

Also, between the external electrode 72 and the external electrode 75 formed on the end face adjacent to the clockwise end face on which the external electrode 72 is formed, between the internal electrode layers 85, 86, 87. A third capacitance component can be obtained.

For this reason, in this multilayer ceramic capacitor 70, if the electrode areas of the internal electrode layers 82, 84 and 86, which oppose the internal electrode layers 81, 82 and 83, respectively, are different, three capacitors can be used for one capacitor. , Which is one-third that of the case where a hybrid circuit is formed by the above-described two-terminal type multilayer ceramic capacitor.
The number of capacitors may be mounted, and the mounting density is improved.

[0012]

Here, in the above-described multilayer ceramic capacitor 70, the external electrodes 72 connected to the reference internal electrode layers 81, 83, 85, 87 are connected to the four external electrodes of the multilayer body 71. It is necessary to specify, and in order to recognize and distinguish the external electrode 72, it is necessary to form a mark 76 by cutting one corner of the stacked body 71 as shown in FIG.

However, when the size of the multilayer ceramic capacitor is reduced, it is difficult to form the mark 76 with high accuracy, and when the mark 76 is formed, there is a problem that the internal electrode layer is scraped off.

The present invention has been devised in view of the above problems, and has as its object to simplify the process while reducing the number of capacitors mounted on a circuit board to improve the mounting density. It is intended to provide a laminated ceramic capacitor that can be used.

[0015]

According to the present invention, there is provided a multilayer ceramic capacitor comprising at least five or more generally rectangular dielectric ceramic layers stacked on each other, and a dielectric ceramic layer between each of the dielectric ceramic layers. It comprises a substantially rectangular internal electrode layer arranged so that a part thereof is exposed from the end face of the laminate, and four external electrodes formed on each end face of the laminate so as to be connected to the internal electrode layer. In multilayer ceramic capacitors,
The extending end faces of the internal electrode layers are sequentially rotated by 90 ° in a certain direction in the stacking order.

[0016]

In the multilayer ceramic capacitor of the present invention, dielectric ceramic layers having internal electrode layers formed thereon are laminated, and external electrodes connected to the internal electrode layers are formed on four end faces of the laminated body. The end surfaces from which the internal electrode layers extend are sequentially rotated by 90 ° in a certain direction in the stacking order. That is, the end face from which the internal electrode layer extends is an end face that is oriented in one direction around the end face from which the internal electrode layer disposed between adjacent layers extends, for example, perpendicular to the left-hand direction. For example, the first internal electrode layer disposed between the first layers of the dielectric ceramic layer extends from the upper side of the drawing. A second layer adjacent to the first layer on which the first internal electrode layer is formed and a thickness direction of the laminate;
The second internal electrode layer disposed between the layers extends from the left side of the drawing. A third layer disposed between the second layer on which the second internal electrode layer is formed and a third layer adjacent in the thickness direction of the laminate.
The internal electrode layer extends from the lower side of the drawing. The fourth internal electrode layer disposed between the third layer on which the third internal electrode layer is formed and the fourth layer adjacent in the thickness direction of the laminate extends from the right side of the drawing. The fifth internal electrode layer in which the fourth internal electrode layer is disposed between the fourth layer and the fifth layer adjacent in the thickness direction of the stacked body extends as a first internal electrode layer from the upper side of the drawing.

That is, a part of the internal electrode layer extends from, for example, an end face adjacent in a counterclockwise direction and is connected to an external electrode formed on each end face.

According to this multilayer ceramic capacitor,
Three capacitors can be constituted by one capacitor, so that the capacitor is more versatile than the two-terminal capacitor, and the mounting density on the hybrid circuit board can be improved.

That is, the acquired capacitance is a capacitance that can be acquired between external electrodes formed on adjacent end faces, a capacitance that can be acquired between external electrodes formed on a pair of opposed end faces, and a capacitance that can be acquired on another pair of opposed end faces. It is classified into three types of capacitance that can be obtained by external electrodes.

In this case, since the laminated body formed by laminating the dielectric ceramic layers has a substantially rectangular parallelepiped shape, two external electrodes on the adjacent end face, two external electrodes on the long side end face, and the short side side are used. The external electrodes can be specified by visual observation with the two external electrodes on the end face. As a result, a mark for recognition and distinction becomes unnecessary, the process can be simplified, and there is no problem that the internal electrode layer is cut off.

[0021]

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 a perspective view showing the appearance of a multilayer ceramic capacitor according to the present invention, FIG. 2 is a view showing the stacking order of FIG. 1, and FIG. 3 is a view showing a cross section taken along line AA of FIG. Yes,
FIG. 4 is a diagram showing a cross section taken along line BB of FIG.

In the figure, 10 is a multilayer ceramic capacitor, 1 is a laminate, 2 to 5 are external electrodes, and 12 to 15 are internal electrode layers.

The dielectric ceramic layer 11 is made of barium titanate,
It is made of a dielectric material such as strontium titanate, and has a rectangular planar shape.

The internal electrode layers 12 to 15 are made of Pd or Ag.
It is made of a metal material such as a -Pd alloy or a base metal material such as Ni, and has a substantially rectangular shape on the dielectric ceramic layer 11. Further, a part of the internal electrode layers 12 to 15 is configured to be displaced and extended in one circumferential direction for each layer, for example, leftward (in the order of the upper side, the left side, the lower side, the right side...). . Preferably, for stability of characteristics, it is desirable that the internal electrode layers 12 to 15 be a set and the number of all internal electrode layers is a multiple of 4, and the total number of dielectric ceramic layers 11 is all. The number of internal electrode layers is 5, 9,
(4n + 1) layers are formed.

It is important that the inner electrode layers, for example, 12, 13 or 13, 14 have a peripheral portion that does not overlap with each other on the side where the external electrode is not provided. For example, when the length of the long side of the internal electrode layers 12 and 14 is L, the length of the short side is W, the length of the long side of the internal electrode layers 13 and 15 is 1 and the length of the short side is w , L> L, W> w or l <L,
It is assumed that W <w.

The external electrodes 2 to 5 are formed so as to be connected to a part of the internal electrode layers 12 to 15 extended to the end face of the laminate 1, and the internal electrodes 12 to 15 which form a capacitance component are formed. To 15 are selectively connected. Here, the external electrodes 2 to 5 are formed of an underlying thick film conductor film made of Ag or an Ag-Pd alloy, a Ni plating layer made of a material that is unlikely to cause solder erosion on the surface of the underlying thick film conductor film, and a Ni plating layer. A plating layer made of a material such as Sn or a Sn—Pb alloy is formed on the layer.

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

First, a ceramic green sheet which becomes the dielectric ceramic layer 11 and includes a plurality of element regions is prepared. The ceramic green sheet can be formed by a well-known method, that is, by mixing a predetermined dielectric material, forming a slip, tape-forming the slip material with a doctor blade or the like, and forming the slip into a predetermined size.

Next, 4 is added to each element region of the green sheet.
Conductive films to be the types of internal electrode layers 12 to 15 are formed (see FIG. 2). Specifically, the conductive paste is formed by printing and drying a conductive paste containing the above-described material for forming the internal electrode layer.

Next, the above-described green sheets are laminated in consideration of the lamination order of the internal electrode layers 12 to 15 of the laminate 1,
Combine and 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 rectangular shape. Thereby, a laminate in an unfired state is formed.

Next, the unfired laminate is fired in a predetermined atmosphere and at a predetermined temperature to make the conductor films and the ceramic green sheets into the internal electrode layers 12 to 15 and the dielectric ceramic layer 11. Thereafter, if necessary, polishing is performed to completely expose the extended portions of the internal electrode layers 12 to 15 from the fired end surfaces. Thereby, the laminated body 1 is formed.

Next, external electrodes 2 to 5 are formed on the end portions of the laminate 1 including the pair of end surfaces.

At this time, a conductive film to be an underlying thick conductive film is formed on the four side surfaces of the laminated body 1 by a method such as screen printing of a conductive paste made of Ag or an Ag—Pd alloy, and is baked. . Then, a Ni plating layer made of a material that is unlikely to be eroded by solder is formed on the surface of the base thick film conductor film, and Sn or Sn- is formed on the plating layer.
A plating layer made of a material such as a Pb alloy is formed.

In the above manufacturing method, in the multilayer ceramic capacitor 10 having the above-described structure, the acquired capacitance is
A first capacitance component formed between external electrodes (for example, 2, 3 and the like) formed on adjacent end surfaces of the laminate 1, a pair of external electrodes (for example, 3, 5)
And a third capacitance component formed between a pair of external electrodes (for example, 2 and 4) formed on the end face of the long side of the laminate 1. .

For example, the first capacitance component that can be obtained between the external electrodes 2 and 3 is a capacitance component that is mainly proportional to the facing area between the internal electrode layers 12 and 13.

Further, the second electrode which can be obtained between the external electrodes 3 and 5
Is directly between the internal electrode layers 13 and 15 via the internal electrode layer 14 (the capacitance formed in the region of the internal electrode layers 13 and 15 protruding from the longitudinal direction of the internal electrode layer 14). Alternatively, there is a capacitance component formed indirectly (the combined capacitance of the capacitance of the internal electrode layers 13 and 14 and the capacitance of the internal electrode layers 14 and 15).

Further, a third capacitance component which can be obtained between the external electrodes 2 and 4 is directly transferred between the internal electrode layers 12 and 14 via the internal electrode layer 13 (from the width direction of the internal electrode layer 13). There is a capacitance component formed in the protruding regions of the internal electrode layers 12 and 14) or indirectly (combined capacitance of the internal electrode layers 12 and 13 and the capacitance of the internal electrode layers 13 and 14). .

The distinction between these three types of capacitance components is very easy because it is only necessary to confirm the long side and the short side of one of the laminates. There is no need to form marks. Therefore, the process can be simplified, and there is no possibility that the internal electrode layer is accidentally scraped off when forming the mark.

The multilayer ceramic capacitor 10 is
Internal electrode layers, for example, 12 arranged so as to face each other between layers of the dielectric ceramic layer 11 adjacent to each other in the stacking direction of the stack.
13 or 13 and 14 have peripheral portions that do not overlap each other on the side where no external electrode is provided,
This is for keeping the overlapping area of the internal electrode layers 12 to 15 arranged between adjacent layers constant.

FIGS. 5 and 6 are an external perspective view showing another multilayer ceramic capacitor of the present invention and a view showing the structure of an electrode layer.

The planar shape of the laminate 51 is substantially square, and the facing areas of all the internal electrode layers 62 to 65 are equal. Here, the square shape is a rectangular shape having four sides equal to each other, but the dielectric ceramic layer 61 is subjected to a baking process and is accompanied by sintering shrinkage and the like, so that the complete square dielectric ceramic layer 61 is formed.
Is difficult in practice. Therefore, a substantially square shape refers to a shape that is as close as possible to a square shape.

Therefore, external electrodes 52 to 55 can be formed on all four end faces in the same manner, and external electrodes 5 to 55 can be formed.
When forming the layers 2 to 55, an alignment step for selecting three side faces from four side faces is not required, and the term step can be simplified.

Here, a capacitance is formed between the internal electrode layers 62 to 65. Then, all the internal electrode layers 62 to
If the facing areas of the 65 are equal, the acquired capacitances are two types: a capacitance composed of adjacent external electrodes, for example, 52 and 53, and a capacitance composed of opposing external electrodes, for example, 52 and 54. . It is extremely easy to recognize and distinguish these two types, and the positioning during mounting can be simplified.

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.

[0047]

As described above, according to the present invention, one capacitor can constitute a plurality of types of capacitances.
The versatility is improved as compared with the two-terminal type, and the density on the hybrid integrated circuit board can be increased.

Further, it is very easy to recognize and distinguish a plurality of types of capacitors, and it is not necessary to form a mark on the laminate. Thereby, the process can be simplified, the internal electrode layer is not damaged at all, and the device can be reduced in size.

Further, the extension of the internal electrode layer is made to correspond to the extension of the internal electrode layer between the adjacent dielectric ceramic layers.
The regular arrangement of extending to an end face orthogonal to the left rotation or to an end face orthogonal to the right rotation greatly simplifies the lamination process.

[Brief description of the drawings]

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

FIGS. 2A to 2D are plan views of a dielectric layer on which an internal electrode layer constituting a multilayer body of the multilayer ceramic capacitor of the present invention is formed.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is a sectional view taken along line BB of FIG. 1;

FIG. 5 is an external perspective view of another multilayer ceramic capacitor of the present invention.

6 (a) to 6 (d) are plan views of a dielectric layer on which an internal electrode layer constituting the multilayer body of the multilayer ceramic capacitor of FIG. 5 is formed.

FIG. 7 is a perspective view of a conventional multilayer ceramic capacitor.

8 (a) to 8 (g) are plan views of a dielectric layer on which an internal electrode layer constituting the multilayer body of the multilayer ceramic capacitor of FIG. 7 is formed.

[Explanation of symbols]

 10, 50... Multilayer ceramic capacitor 1, 51. ..Internal electrode layers

Claims (1)

[Claims] 1. A laminate comprising at least five or more generally rectangular dielectric ceramic layers laminated, and between each of the dielectric ceramic layers, a part thereof is exposed from an end face of the laminate. A multilayer ceramic capacitor comprising: a substantially rectangular internal electrode layer arranged; and four external electrodes formed on each end surface of the laminate so as to be connected to the internal electrode layer. A multilayer ceramic capacitor wherein the protruding end faces are sequentially rotated by 90 ° in a certain direction in the order of lamination.