JPH0855758A - Multilayer capacitor - Google Patents

Abstract

(57) [Summary] [Structure] In a multilayer capacitor in which a plurality of dielectric layers 11 to 17 and internal electrodes 21 to 27 are alternately stacked,
One of the internal electrode groups 23 and 25 having the same polarity is the end electrode 3
0 is directly connected to the other internal electrode group 21,
A multilayer capacitor 10 in which 22, 24, 26, 27 are connected to each other by a columnar connecting member 35 on one end side of the internal electrodes 21, 22, 24, 26, 27 near the end electrode 30. [Effect] The directions of the currents flowing through the internal electrodes 21 to 27 can be formed so as to cancel each other. As a result, it is possible to provide a multilayer capacitor for high-speed, highly integrated semiconductor chips and modules that is less likely to cause a short circuit and has a large capacitance and a small parasitic inductance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a multilayer capacitor,
More specifically, the present invention relates to a low-inductance multilayer capacitor that can effectively remove switching noise of a logic circuit in a high frequency region.

[0002]

2. Description of the Related Art With the recent increase in capacity, speed and density of electronic circuits, there is a demand for higher capacity and higher frequency of capacitors. A monolithic ceramic capacitor is one of the capacitors that can meet such requirements. Among them, the chip type monolithic ceramic capacitor 40 of the type shown in FIG. 5 is widely used because it can realize a large capacity and can be easily mounted on a package or the like.

Reference numeral 41 in the figure denotes a dielectric. Between the stacked dielectrics 41, an internal electrode 42 formed on substantially the entire surface except the left end and an internal electrode 43 formed on the substantially entire surface excluding the right end. Are formed on every other layer, and these dielectrics 4
1, the internal electrode 42 and the internal electrode 43 form a laminated body 44. Further, an end electrode 45 to which one end of the internal electrode 42 is connected and an end electrode 46 to which one end of the internal electrode 43 is connected are formed at both ends of the laminated body 44.
The chip type monolithic ceramic capacitor 40 is configured to include the laminated body 44 and the end electrodes 45 and 46.

In the chip type monolithic ceramic capacitor 40 thus constructed, the internal electrodes 42 and 43 are formed.
Capacitors are formed on the laminated surfaces facing each other, and the sum of the respective capacitance values becomes the total capacitance value of the chip-type multilayer ceramic capacitor 40, and a large capacitance can be obtained even if it is small.

By the way, in general, a capacitor is ideally a capacitive element, but in reality, it has the dielectric loss of the dielectric material and the resistance and inductance of the electrodes.
It is represented by the equivalent circuit as shown in, and its behavior greatly changes depending on the frequency used. As an example, FIG.
Capacitance C = 1nF, Equivalent series resistance ESR (Equivalent Ser
ies Resistance) = 0.1Ω, impedance of capacitor with equivalent series inductance ESL = 1 nH | Z
It shows the frequency characteristic of |. Here, the solid line represents the actual frequency characteristic, and the dotted line represents the ideal frequency characteristic of a capacitor having no dielectric loss or electrode resistance, that is, the inductance (ωL) component and capacitance component (1 / ωC) of the capacitor.
The frequency characteristics of are shown. As is clear from FIG. 7, the impedance of an actual capacitor begins to shift from around 40 MHz, which indicates that the apparent capacitance is changing. Resonance is generated at 160 MHz, and the inductor behaves as an inductor at frequencies higher than that. A typical application of the capacitor is a bypass capacitor that cuts the noise of the circuit. With the above-mentioned capacitor, the impedance becomes high when the noise frequency becomes 300 MHz or more, so that the noise in the high frequency region can be effectively eliminated. There was a problem that it became difficult to remove.

In order to solve such a problem, it is necessary to increase the self-resonant frequency f _O of the capacitor. In general,
The capacitor's f _O is

[0007]

[Equation 1]

It is represented by Therefore, to increase f _O , E
SL or C must be small. But,
As described above, C tends to increase with the increase in the capacity of the circuit in recent years, and C cannot be reduced, and ESL
It is important to reduce

In the chip type monolithic ceramic capacitor 40, as shown in FIG. 8, in all the internal electrodes 42, 43 sandwiching the dielectric 41, current flows from one end of the end electrode 46 in the same direction, and The electromagnetic fields are not canceled, and the ESL value is approximately the following formula,

[0010]

[Equation 2]

It is represented by As a result, the mutual inductance has a positive and large value, and the ESL value cannot be reduced. For example, assuming that the width a of the end electrode 46 is 0.5 mm, the height c of the capacitor 40 is 0.5 mm, the length d of the capacitor 40 is 1 mm, and μ _{0 is the} magnetic permeability, the ESL is about 1.3.
It becomes a large value of nH.

The switching noise is noise generated by a current (charging / discharging current) flowing through the power supply line of the system due to the switching of the logic circuit, and is proportional to the inductance of the current path. At this time, the capacitor acts as a supply source of charging / discharging current. At present, switching noise in this logic circuit has become a serious problem with the increase in speed of electronic circuits, and in order to suppress the switching noise, it is desired to increase the capacity and the inductance of the capacitor.

In the chip type monolithic ceramic capacitor 40 whose capacity has already been increased, it is important to reduce the ESL of the capacitor itself in order to further suppress switching noise.

In order to reduce the ESL of the capacitor itself, a chip type multilayer capacitor has been proposed in which the internal electrodes are arranged so that the directions of the currents flowing through the vertically adjacent internal electrodes are substantially opposite to each other (special feature). Fairness 4-7076
4 publication). FIG. 9 is a top view of the chip type multilayer capacitor 50. In the figure, 51 and 52 respectively indicate end electrodes, and A in the figure indicates the distance between the end electrodes. The ear piece 53a of the internal electrode 53 formed on the dielectric 54 and the end electrodes 51 and 52 are electrically connected alternately in each stack. FIG. 10 is a schematic diagram showing a series of arrangements of the internal electrodes 53, and the ear piece portions 53a are formed at four different corners of the dielectric 54, respectively. FIG. 11 shows a capacitor 50
FIG. 2 is a view showing the order of orientation of internal electrodes 53 in the inside.
The ear pieces 53a of the stacked internal electrodes 53 are directed to the corners of the other sheet. The internal electrodes 53 stacked in this manner are arranged every other sheet and the end electrodes 51, 5 on the opposite side are arranged.
Since it is connected to 2, the currents flow in opposite directions as indicated by the arrows in the figure, and the magnetic fields cancel each other.
As a result, the parasitic inductance can be reduced.

[0015]

However, in the multilayer capacitor 50 having the above structure, the end electrodes 51 and 52 are formed.
Since the electrodes are formed in the short side direction, the distance A between the end electrodes becomes short, and there is a problem that short-circuiting is highly likely to occur when inexpensive soldering mounting is performed. As shown in FIG. 12, when a multilayer capacitor having a large distance A between the end electrodes is used, the directions of the currents (arrows) are not in the reverse parallel state as shown by the arrows in FIG. 11, and the magnetic fields cancel each other out. Since it is difficult, the parasitic inductance increases. Also,
In order to suppress the direction of the current, a shape of the internal electrode 63 having a groove 65 as shown in FIG. 13 has also been proposed, but in this case, there is a problem that the capacitance value is significantly reduced.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a multilayer capacitor which is less likely to cause a short circuit, has a large capacity, and has a small parasitic inductance. .

[0017]

In order to achieve the above object, a multilayer capacitor according to the present invention is a multilayer capacitor in which a plurality of dielectric layers and internal electrodes are alternately stacked, and one internal electrode having the same polarity. While the group is directly connected to the end electrodes, the other internal electrode group is connected to each other by a columnar connecting member on one end side of the internal electrodes near the end electrodes.

[0018]

If the directions of the currents flowing through the adjacent electrode plates can be made opposite and parallel, the absolute value of the mutual inductance having a negative value becomes substantially equal to the self-inductance, and as a result, the parasitic inductance approaches zero.

In the above-mentioned multilayer capacitor, one end electrode (referred to as a first end electrode) and the internal electrode group connected thereto are connected in the same manner as a normal multilayer chip capacitor. In the internal electrode group, a hollow portion is formed, and another internal electrode group is connected to each other by a columnar connecting member penetrating the hollow portion, and the uppermost portion and the lowermost portion of the other internal electrode group are connected. Will be electrically connected to the other end electrode (referred to as a second end electrode). Therefore, the direction of the current flowing through the internal electrode group that is not directly connected to the second end electrode is that the through hole is formed at one end on the internal electrode near the first end electrode. And 180 the direction of the current flowing through the internal electrode group connected to the first end electrode. It will be reversed. This makes it possible to obtain a multilayer capacitor having a small parasitic inductance.

[0020]

Embodiments of the multilayer capacitor according to the present invention will be described below with reference to the drawings. Here, for simplification, the case where seven layers of internal electrodes are formed will be described. FIG.
Shows a schematic vertical sectional view of a multilayer capacitor 10 according to an embodiment, and FIG. 2 shows an exploded perspective view. 11 in the figure
Reference numerals 17 to 32 denote dielectric plates formed of a high dielectric constant material such as barium titanate.
A plurality of through holes 11a to 16a are formed at predetermined positions of to 16 respectively. The internal electrodes 21, 27 are formed by using a metal paste made of Pb, Pt, Ag, Pd-Ag, or the like, which can be co-fired with the dielectric material, in portions other than the right end portions of the dielectric plates 11 and 17 except for the peripheral predetermined width. Are formed.
Further, internal electrodes 23 and 25 are formed using the metal paste in the portions other than the left end portions of the dielectric plates 13 and 15 except the predetermined width and the portions other than the cutout portions 23a and 25a. In addition, the metal paste is used for the internal electrodes 22, except for the predetermined width around the dielectric plates 12, 14, 16.
24 and 26 are formed respectively. A laminated body is formed by a configuration in which the dielectric plates 11 to 17 and the internal electrodes 21 to 27 are sequentially laminated alternately. An end electrode 30 and an end electrode 31 are formed at the end of the laminated body by using the metal paste that can be co-fired with the dielectric. And every other internal electrode 23 having the same polarity,
25 is connected to the end electrode 30, and the other internal electrodes 22, 24, 26 having the same polarity, and the uppermost internal electrode 21 and the lowermost internal electrode 27 are through holes 11a to 17a.
The internal electrodes 21 and the internal electrodes 2 are connected to each other by the columnar connecting members 35, 36 and 37 filled in a.
It is connected to the end electrode 31 via 7. These columnar connecting members 35 to 37 are formed by using the above-mentioned metal paste which has conductivity and can be co-fired with the dielectric, and is arranged in the vicinity of the end electrodes 30 of the internal electrodes 21 to 27. ing. Since the hollow portions 23a and 25a are formed in the internal electrodes 23 and 25, respectively, as described above, the other internal electrodes 21, ...
・ It is not connected with. These dielectric plates 11 to 1
The multilayer capacitor 10 is configured to include 7, internal electrodes 21 to 27, and end electrodes 30 and 31.

In order to manufacture the laminated capacitor 10 having such a structure, first, a dispersant, an organic binder and a plasticizer are added to a barium titanate powder to which a glass-based sintering aid is added, and the mixture is kneaded. Thickness is about 5 by blade method
A dielectric sheet is obtained by molding into a sheet shape of 0 μm.

Next, the baked size is, for example, 2 mm in length,
After cutting the dielectric sheet into a size having a width of 2 mm, the through holes 11a to 16a shown in FIGS. 1 and 2 are formed, respectively, and further, the two main dielectric sheets are formed on one main surface as shown in FIG. The internal electrode patterns corresponding to the internal electrodes 23 and 25 shown in FIG. 2 are respectively formed by the screen printing method using a metal mask, and are shown on one main surface of five dielectric sheets as shown in FIGS. Internal electrodes 21, 22, 24, 2
Internal electrode patterns corresponding to 6 and 27 are formed by screen printing using a metal mask. At the same time, for example, a Pd—Ag paste is filled as a metal paste into all the through holes 11a to 16a.

After that, the internal electrode pattern is formed on the upper surface 7
The dielectric sheets are laminated one after another as shown in FIGS. 1 and 2, and a dielectric sheet as a protective plate indicated by a dielectric plate 32 in FIG. 1 is laminated.

Next, these laminated dielectric sheets are pressure-bonded and then fired in the atmosphere at 1250 ° C. to obtain a laminated capacitor 1.
Create 0.

FIG. 3A is a schematic diagram showing the direction of the current flowing through the internal electrode 25 in the multilayer capacitor 10 according to the embodiment when the polarity of the internal electrode 25 is +.
FIG. 3B is a schematic diagram showing the direction of the current flowing through the internal electrode 26 when the polarity of the internal electrode 26 is −. Arrows x and y are the directions of the respective currents,
° The direction is reversed.

As is apparent from FIGS. 1 and 3, in the multilayer capacitor 10 according to the embodiment, the currents flowing through the internal electrodes 21 to 26 flow in the directions canceling each other.
Can be made smaller.

Actually, the multilayer capacitor 10 according to the embodiment
When the ESL was examined, it was confirmed that the value was as small as 0.05 nH.

FIG. 4 is a top view of the multilayer capacitor 10 according to the embodiment. Since the end electrodes 30 and 31 can be formed in the longitudinal direction of the capacitor, the risk of short circuit during solder mounting is low, and the size can be sufficiently reduced.

As described above, in the multilayer capacitor 10 according to the embodiment, the method of connecting the end electrodes 30 and the internal electrodes 23 and 25 connected to the end electrodes 30 is the same as that of a normal multilayer chip capacitor. However, the internal electrodes 23 and 25 connected to the end electrodes 30 have hollow portions 23, respectively.
a and 25a are formed, and the hollow portions 23a and 25a are formed.
And the columnar connecting members 35 to penetrate the dielectric plates 11 to 16.
Other internal electrodes 21, 22, 24, 26, 27 by 37
Are connected to each other, of which the internal electrodes 21,
Each of the electrodes 27 is electrically connected to the end electrode 31. Moreover, the hollow portions 23a, 25a are formed at one end portion in the vicinity of the end electrode 30, so that the internal electrodes 22, 2
The direction of the current flowing through the electrodes 4 and 26 is 180 with the direction of the current flowing through the internal electrodes 23 and 25. It will be reversed.

Further, since the internal electrode 21 is formed so as to be adjacent to the internal electrode 22, it is possible to make the directions of the currents of the entire multilayer capacitor in opposite directions and in parallel.
This makes it possible to obtain a multilayer capacitor having a small parasitic inductance.

[0031]

As described above in detail, in the multilayer capacitor according to the present invention, in the multilayer capacitor in which a plurality of dielectrics and internal electrodes are alternately stacked, one internal electrode group having the same polarity is used. While being directly connected to the end electrodes, the other internal electrode group is connected to each other by the columnar connecting member on one end side of these internal electrodes in the vicinity of the end electrodes. Can be formed so that they cancel each other out. As a result, it is possible to provide a multilayer capacitor for high-speed, highly integrated semiconductor chips and modules that is less likely to cause a short circuit and has a large capacitance and a small parasitic inductance.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of a multilayer capacitor according to the present invention.

FIG. 2 is a schematic exploded perspective view of a multilayer capacitor according to an example.

3A and 3B are schematic diagrams showing directions of currents flowing through two adjacent internal electrodes in the multilayer capacitor according to the example.

FIG. 4 is a top view of a multilayer capacitor according to an example.

FIG. 5 is a partial cross-sectional perspective view showing a conventional chip type monolithic ceramic capacitor.

FIG. 6 is an equivalent circuit diagram showing a circuit configuration of a chip type multilayer ceramic capacitor.

FIG. 7 is a graph showing frequency characteristics of impedance | Z | in a conventional chip type multilayer ceramic capacitor.

FIG. 8 is a schematic vertical sectional view of a conventional multilayer capacitor.

FIG. 9 is a top view of a monolithic ceramic capacitor according to a conventional example.

FIG. 10 is an exploded perspective view showing a laminated body portion of the laminated ceramic capacitor.

FIG. 11 is a diagram showing the order in which the internal electrodes of the monolithic ceramic capacitor are oriented.

FIG. 12 is a diagram showing the order in which the internal electrodes are oriented when the distance between the end electrodes of the multilayer ceramic capacitor is widened.

FIG. 13 is a schematic diagram showing a direction of a current flowing through an internal electrode of a laminated ceramic capacitor according to another conventional example.

[Explanation of symbols]

 10 Multilayer Capacitors 11-17, 32 Dielectrics 21-27 Internal Electrodes 30, 31 End Electrodes 35-37 Columnar Connection Members

Claims (1)

[Claims] 1. In a multilayer capacitor in which a plurality of dielectric layers and internal electrodes are alternately stacked, one internal electrode group having the same polarity is directly connected to an end electrode and the other internal electrode group. Is connected to each other by a columnar connecting member on one end side of these internal electrodes near the end electrodes.