U.S. patent application number 12/183863 was filed with the patent office on 2008-12-04 for multi-terminal type laminated capacitor and manufacturing method thereof.
This patent application is currently assigned to TDK Corp.. Invention is credited to Hiroshi OKUYAMA.
Application Number | 20080295310 12/183863 |
Document ID | / |
Family ID | 36970600 |
Filed Date | 2008-12-04 |
United States Patent
Application |
20080295310 |
Kind Code |
A1 |
OKUYAMA; Hiroshi |
December 4, 2008 |
MULTI-TERMINAL TYPE LAMINATED CAPACITOR AND MANUFACTURING METHOD
THEREOF
Abstract
Electrode layers 121 to 128 are superimposed in a ceramic
porcelain 1 with ceramic layers therebetween. The electrode layers
121 to 128 respectively include internal electrodes A1 to A8 and
extraction electrodes B1 to B8. Giving a description on the
electrode layer 121, one end of the extraction electrode B1 is
connected with the internal electrode A1 in the same layer, and the
other end of the same is led onto a side surface of the ceramic
porcelain 1. Further, the extraction electrode B1 is formed to be
thicker than the internal electrode A1 in the same layer.
Inventors: |
OKUYAMA; Hiroshi; (Tokyo,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
TDK Corp.
Tokyo
JP
|
Family ID: |
36970600 |
Appl. No.: |
12/183863 |
Filed: |
July 31, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11354102 |
Feb 15, 2006 |
7430105 |
|
|
12183863 |
|
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Current U.S.
Class: |
29/25.42 |
Current CPC
Class: |
Y10T 29/435 20150115;
H01G 4/232 20130101; H01G 4/30 20130101 |
Class at
Publication: |
29/25.42 |
International
Class: |
H01G 4/12 20060101
H01G004/12 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 10, 2005 |
JP |
2005-067034 |
Claims
1. A manufacturing method of a multi-terminal type laminated
capacitor, comprising: forming an internal electrode layer and a
first extraction electrode layer on an unbaked ceramic sheet;
forming a second extraction electrode layer on the first extraction
electrode layer; and forming a laminated body such that the unbaked
ceramic sheet having the internal electrode layer and the first and
second extraction electrode layers formed thereon is used as a unit
layer in the laminated body.
2. The manufacturing method of a multi-terminal type laminated
capacitor according to claim 1, wherein the second extraction
electrode layer comprises a plurality of layers.
3. The manufacturing method of a multi-terminal type laminated
capacitor according to claim 1, comprising: forming a step
absorption layer made of a ceramic paste on the internal electrode
layer; and then forming a laminated body such that the unbaked
ceramic sheet having the internal electrode layer, the first and
second extraction electrode layers and the step absorption layer
formed thereon is used as a unit layer in the laminated body.
4. The manufacturing method of the multi-terminal type laminated
capacitor according to claim 1, comprising: forming the internal
electrode layer and the first extraction electrode layer as well as
a dummy electrode layer on the unbaked ceramic sheet.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of Ser. No.
11/354,102, filed Feb. 15, 2006, which is based upon and claims
benefit of priority from the prior Japanese Patent Applications No.
2005-067034, filed on Mar. 10, 2005; the entire contents of both of
which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a multi-terminal type
laminated capacitor and a manufacturing method thereof.
[0004] 2. Description of the Related Art
[0005] In an electric supply source of a central processing unit
(CPU) mounted in a digital electronic device, a reduction in
voltage advances while a load current is increased. Therefore,
suppressing a fluctuation in power supply voltage within an
allowable value range with respect to a sudden change in load
current becomes very difficult, and hence a laminated capacitor
called a decoupling capacitor is connected with a power supply.
Further, at the time of a transitional fluctuation in load current,
a current is supplied from this laminated capacitor to a CPU,
thereby suppressing a fluctuation in power supply voltage.
[0006] In recent years, with a further increase in an operating
frequency of a CPU, a load current and its speed are increased.
Therefore, in the laminated capacitor used as the decoupling
capacitor, there is a demand for an increase in equivalent series
resistance (ESR).
[0007] In a multi-terminal type laminated capacitor disclosed in
Japanese Patent Application Laid-open No. 2000-208361, an
extraction electrode for connection with a terminal electrode is
provided to an internal electrode in each layer, and such an
extraction electrode is led onto a side surface of a ceramic
porcelain. The terminal electrode is formed on the side surface of
the ceramic porcelain by plating or the like and joined to the
extraction electrode. The terminal electrode is appressed against
the ceramic porcelain through a joining structure with respect to
the extraction electrode.
[0008] In order to obtain a high ESR in this type of laminated
capacitor, there can be considered a technique which reduces a film
thickness of the internal electrode provided in each layer.
[0009] However, in the technology described in Japanese Patent
Application Laid-open No. 2000-208361, since the film thickness of
the extraction electrode is the same as the film thickness of the
internal electrode, reducing the film thickness of the internal
electrode decreases the film thickness of the extraction electrode.
When the film thickness of the extraction electrode is reduced, a
sufficient joining structure cannot be provided to the terminal
electrode, and hence it is difficult to assure the adhesion of the
terminal electrode with respect to the ceramic porcelain.
[0010] As another means for increasing the ESR, a technique of
reducing the number of layers can be considered. However, when the
number of layers is reduced, the number of extraction electrodes is
also decreased. In the technology described in Japanese Patent
Application Laid-open No. 2000-208361, the film thickness of the
extraction electrode is the same as the film thickness of the
internal electrode. Therefore, when the number of the extraction
electrodes is reduced, a sufficient joining structure cannot be
provided to the terminal electrode, and hence it is difficult to
assure the adhesion of the terminal electrode with respect to the
ceramic porcelain.
SUMMARY OF THE INVENTION
[0011] It is an object of the present invention to provide a
multi-terminal type laminated capacitor and a manufacturing method
thereof which can assure the adhesion of a terminal electrode with
respect to a ceramic porcelain even if the number of layers is
reduced or a film thickness of an internal electrode is reduced in
order to increase an ESR.
[0012] <Multi-Terminal Type Laminated Capacitor>
[0013] To achieve this object, according to the present invention,
there is provided a multi-terminal type laminated capacitor
comprising: a ceramic porcelain; and a plurality of electrode
layers superimposed in the ceramic porcelain with ceramic layers
therebetween.
[0014] Each electrode layer includes an internal electrode and an
extraction electrode. The extraction electrode has one end
connected with the internal electrode in the same layer and the
other end led onto a side surface of the ceramic porcelain, and is
formed to be thicker than the internal electrode in the same
layer.
[0015] As described above, according to the multi-terminal type
laminated capacitor of the present invention comprises the ceramic
porcelain and the plurality of electrode layers superimposed in the
ceramic porcelain with the ceramic layers therebetween. Therefore,
a basic configuration of the multi-terminal type laminated
capacitor can be obtained.
[0016] Each electrode layer includes the internal electrode and the
extraction electrode. One end of the extraction electrode is
connected with the internal electrode in the same layer, and the
other end of the same is led onto the side surface of the ceramic
porcelain. Therefore, the terminal electrode can be formed on the
side surface of the ceramic porcelain, thereby providing the
joining structure with respect to the extraction electrode.
[0017] In the present invention, the extraction electrode is formed
to be thicker than the internal electrode in the same layer.
According to this configuration, even if the number of layers is
reduced or a film thickness of the internal electrode is decreased
in order to increase the ESR, a film thickness which is required
for the joining structure with respect to the terminal electrode
can be assured for the extraction electrode. Therefore, the
sufficient joining structure can be provided to the terminal
electrode, and the adhesion of the terminal electrode with respect
to the ceramic porcelain can be assured. Accordingly, exfoliation
of the terminal electrode due to a thermal shock can be
avoided.
[0018] Preferably, the extraction electrode is formed to be thicker
than the internal electrode in the same layer in the vicinity of
the side surface of the ceramic porcelain.
[0019] In one embodiment, the electrode layer further includes a
dummy electrode, and the dummy electrode is arranged apart from the
internal electrode and the extraction electrode in the same layer,
and has one end led onto the side surface of the ceramic porcelain.
According to this configuration, a joining structure with respect
to the dummy electrode as well as the joining structure with
respect to the extraction electrode can be provided to the terminal
electrode, thereby increasing the adhesion of the terminal
electrode with respect to the ceramic porcelain.
[0020] In at least one of the electrode layers, it is preferable
that the dummy electrode has the same polarity as seen from a
relationship with the internal electrode in the same layer. When
the dummy electrode has the same polarity as seen from the
relationship with the internal electrode in the same layer, a
short-circuit defect between the dummy electrode and the internal
electrode can be avoided.
[0021] In another embodiment, the ceramic porcelain has an inner
layer portion having the electrode layers superimposed with the
ceramic layers therebetween and an outer layer portion positioned
outer as seen from the inner layer portion, the outer layer portion
having a dummy electrode layer. The dummy electrode layer includes
an outer layer dummy electrode, an the outer layer dummy electrode
has one end led onto a side surface of the ceramic porcelain.
According to this configuration, the terminal electrode can be
provided with the joining structure with respect to the extraction
electrode as well as a joining structure with respect to the outer
layer dummy electrode, thereby increasing the adhesion of the
terminal electrode with respect to the ceramic porcelain.
[0022] <Manufacturing Method of Multi-Terminal Type Laminated
Capacitor>
[0023] In a manufacturing method of a multi-terminal type laminated
capacitor according to the present invention, an internal electrode
layer and a first extraction electrode layer are formed on an
unbaked ceramic sheet. Further, a second extraction electrode layer
is formed on the first extraction electrode layer. Furthermore, a
laminated body is formed such that the unbaked ceramic sheet having
the internal electrode layer and the first and second extraction
electrode layers formed thereon is used as a unit layer in the
laminated body.
[0024] As described above, in the manufacturing method of the
multi-terminal type laminated capacitor according to the present
invention, the internal electrode layer and the first extraction
electrode layer are formed on the unbaked ceramic sheet, and the
second extraction electrode layer is formed on the first extraction
electrode layer. Therefore, it is possible to obtain a basic
configuration including the internal electrode and the extraction
electrode which is formed to be thicker than the internal electrode
in the same layer.
[0025] Moreover, the laminated body is formed such that the unbaked
ceramic sheet having the internal electrode layer and the first and
second extraction electrode layers formed thereon is used as a unit
layer in the laminated body. Therefore, the multi-terminal type
laminated capacitor according to the present invention can be
obtained.
[0026] In one embodiment, the second extraction electrode layer is
constituted of a plurality of layers.
[0027] In another embodiment, a step absorption layer made of a
ceramic paste is formed on the internal electrode layer. Then, a
laminated body is formed such that the unbaked ceramic sheet having
the internal electrode layer, the first and second extraction
electrode layers and the step absorption layer formed thereon is
used as a unit layer in the laminated body. According to such a
step absorption layer, a step generated between the internal
electrode layer and the second extraction electrode layer can be
absorbed.
[0028] As described above, according to the present invention, even
if the number of the layers is reduced or a film thickness of the
internal electrode is decreased in order to increase the ESR, it is
possible to provide the multi-terminal type laminated capacitor and
the manufacturing method thereof which can assure the adhesion of
the terminal electrode with respect to the ceramic porcelain.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is an appearance perspective view according to an
embodiment of a multi-terminal type laminated capacitor according
to the present invention;
[0030] FIG. 2 is a pattern diagram showing a cross section taken
along a line 2-2 in FIG. 1;
[0031] FIG. 3 is a pattern diagram showing configurations of
electrode layers;
[0032] FIG. 4 is a view showing a part in the vicinity of the
electrode layers 121 and 122 in an enlarged manner in relation to
the cross section depicted in FIG. 2;
[0033] FIG. 5 is a pattern diagram showing configurations of dummy
electrode layers;
[0034] FIG. 6 is a view showing a step included in an embodiment of
a manufacturing method of a multi-terminal type laminated capacitor
according to the present invention;
[0035] FIG. 7 is a partially enlarged end elevational view taken
along a line 7-7 in FIG. 6;
[0036] FIG. 8 is a view showing a step after the step depicted in
FIGS. 6 and 7;
[0037] FIG. 9 is a view showing a step after the step depicted in
FIG. 8; and
[0038] FIG. 10 is a view showing a step after the step depicted in
FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0039] <Multi-Terminal Type Laminated Capacitor>
[0040] FIG. 1 is an appearance perspective view showing an
embodiment of a multi-terminal type laminated capacitor according
to the present invention, and FIG. 2 is a pattern diagram showing a
cross section taken along a line 2-2 in FIG. 1. As shown in the
drawings, a multi-terminal type laminated capacitor according to
the present invention includes a ceramic porcelain 1 and a
plurality of electrode layers 121 to 128.
[0041] The ceramic porcelain 1 is formed of a dielectric material
or the like mainly containing, e.g., barium titanate. The ceramic
porcelain 1 has a substantially rectangular parallelepiped shape
having a length direction X, a width direction Y and a thickness
direction Z, and terminal electrodes 21 to 24 are provided on one
side surface 101 as seen from the width direction Y. These terminal
electrodes 21 to 24 are arranged on the side surface 101 at
intervals in the length direction X, and the adjacent terminal
electrodes have polarities different from each other. Specifically,
the terminal electrodes 21 and 23 have a negative polarity, and the
terminal electrodes 22 and 24 have a positive polarity.
[0042] Terminal electrodes 25 to 28 are likewise provided on the
other side surface 102 of the ceramic porcelain 1. These terminal
electrodes 25 to 28 are arranged on the side surface 102 at
intervals in the length direction X, and the adjacent terminal
electrodes have polarities different from each other. Specifically,
the terminal electrodes 25 and 27 have a negative polarity, and the
terminal electrodes 26 and 28 have a positive polarity.
[0043] The terminal electrodes 21 to 28 can be constituted of
single-layer or multilayer plating films (212 to 282) and (213 to
283) on underlying films 211 to 281 obtained by applying an
electroconductive paste on the ceramic porcelain 1 and baking this
paste. The underlying films 211 to 281 are constituted to mainly
contain, e.g., Cu or Ag, and the plating films are formed of
multilayer plating films (212 to 282) and (213 to 283) of, e.g.,
Ni/Sn.
[0044] Referring to FIG. 2, the electrode layers 121 to 128 are
superimposed in the ceramic porcelain 1 with ceramic layers held
therebetween. Giving a detailed explanation, the ceramic porcelain
1 consists of an inner layer portion 12, a first outer layer
portion 11 positioned above the inner layer portion 12 and a second
outer layer portion 13 positioned below the inner layer portion 12,
and the electrode layers 121 to 128 are arranged in the inner layer
portion 12 of the ceramic porcelain 1. The electrode layers 121 to
128 are formed of, e.g., Ni.
[0045] FIG. 3 is a pattern diagram showing configurations of the
electrode layers 121 to 128. The electrode layers 121 to 128 will
now be sequentially described hereinafter.
[0046] First, giving a description on the electrode layer 121, the
electrode layer 121 includes an internal electrode Al and an
extraction electrode B1. The internal electrode Al is provided to
face an internal electrode A2 in the electrode layer 122 with a
dielectric layer therebetween, and functions as a capacitance
electrode. The extraction electrode B1 has one end connected with
the internal electrode A1 in the same layer and the other end led
onto one side surface of the ceramic porcelain to be connected with
the terminal electrode 21. Therefore, the internal electrode A1 is
electrically connected with the terminal electrode 21 through the
extraction electrode B1, and hence has the same polarity as that of
the terminal electrode 21, i.e., the negative polarity.
[0047] The electrode layer 121 further includes dummy electrodes
D11 to D13. The dummy electrodes D11 to D13 are respectively
arranged apart from the internal electrode Al and the extraction
electrode B1 in the same layer. Further, each of these dummy
electrodes D11 to D13 is connected with a terminal electrode
selected from the terminal electrodes 21 to 28 in such a manner
that each dummy electrode has the same polarity as seen from a
relationship with the internal electrode A1 in the same layer.
Giving a detailed explanation, the internal electrode A1 has a
negative polarity, and one end of the dummy electrode D11 is led
onto one side surface of the ceramic porcelain to be connected with
the terminal electrode 23 having a negative polarity. One end of
each of the dummy electrodes D12 and D13 is led onto the other side
surface of the ceramic porcelain to be connected with each of the
terminal electrodes 25 and 27 having a negative polarity.
[0048] Giving a description on the electrode layer 122, the
electrode layer 122 includes an internal electrode A2 and an
extraction electrode B2. The internal electrode A2 is provided to
face the internal electrode A1 in the electrode layer 121 and an
internal electrode A3 in the electrode layer 123, and function as a
capacitance electrode. One end of the extraction electrode B2 is
connected with the internal electrode A2 in the same layer, and the
other end of the same is led onto one side surface of the ceramic
porcelain to be connected with the terminal electrode 22.
Therefore, the internal electrode A2 is electrically connected with
the terminal electrode 22 through the extraction electrode B2, and
hence has the same polarity as the terminal electrode 22, i.e., a
positive polarity.
[0049] The electrode layer 122 further includes dummy electrodes
D21 to D23, and the dummy electrodes D21 to D23 are respectively
arranged apart from the internal electrode A2 and the extraction
electrode B2 in the same layer. Further, each of these dummy
electrodes D21 to D23 is connected with a terminal electrode
selected from the terminal electrodes 21 to 28 in such a manner
that each dummy electrode has the same polarity as seen from a
relationship with the internal electrode A2 in the same layer.
Giving a detailed explanation, the internal electrode A2 has a
positive polarity, and one end of the dummy electrode D21 is led
onto one side surface of the ceramic porcelain to be connected with
the terminal electrode 24 having a positive polarity. One end of
each of the dummy electrodes D22 and D23 is led onto the other side
surface of the ceramic porcelain to be connected with each of the
terminal electrodes 26 and 28 having a positive polarity.
[0050] This is also applied to the electrode layers 123 to 128, and
hence the tautological explanation of these layers will be
eliminated as much as possible.
[0051] Giving a description on the electrode layer 123, one end of
an extraction electrode B3 is connected with an internal electrode
A3 in the same layer, and the other end of the same is led onto the
side surface of the ceramic porcelain to be connected with the
terminal electrode 23. Therefore, the internal electrode A3 is
electrically connected with the terminal electrode 23 through the
extraction electrode B3, and hence has the same polarity as the
terminal electrode 23, i.e., a negative polarity. Dummy electrodes
D31 to D33 are respectively connected with the terminal electrodes
21, 25 and 27 having a negative polarity in such a manner that
these dummy electrodes have the same polarity as seen from a
relationship with the internal electrode A3 in the same layer.
[0052] Giving a description on the electrode layer 124, one end of
an extraction electrode B4 is connected with an internal electrode
A4 in the same layer, and the other end of the same is led onto the
side surface of the ceramic porcelain to be connected with the
terminal electrode 24. Therefore, the internal electrode A4 is
electrically connected with the terminal electrode 24 through the
extraction electrode B4, and hence has the same polarity as the
terminal electrode 24, i.e., a positive polarity. Dummy electrodes
D41 to D43 are respectively connected with the terminal electrodes
22, 26 and 28 having a positive polarity in such a manner that
these dummy electrodes have the same polarity as seen from a
relationship with the internal electrode A4 in the same layer.
[0053] Giving a description on the electrode layer 125, one end of
an extraction electrode B5 is connected with an internal electrode
A5 in the same layer, and the other end of the same is led onto the
side surface of the ceramic porcelain to be connected with the
terminal electrode 25. Therefore, the internal electrode A5 is
electrically connected with the terminal electrode 25 through the
extraction electrode B5, and hence has the same polarity as the
terminal electrode 25, i.e., a negative polarity. Dummy electrodes
D51 to D53 are respectively connected with the terminal electrodes
21, 23 and 27 having a negative polarity in such a manner that
these dummy electrodes D51 to D53 have the same polarity as seen
from a relationship with the internal electrode A5 in the same
layer.
[0054] Giving a description on the electrode layer 126, one end of
an extraction electrode B6 is connected with an internal electrode
A6 in the same layer, and the other end of the same is led onto the
side surface of the ceramic porcelain to be connected with the
terminal electrode 26. Therefore, the internal electrode A6 is
electrically connected with the terminal electrode 26 through the
extraction electrode B6, and hence has the same polarity as the
terminal electrode 26, i.e., a positive polarity. Dummy electrodes
D61 to D63 are respectively connected with the terminal electrodes
22, 24 and 28 having a positive polarity in such a manner that
these dummy electrodes have the same polarity in a relationship
with the terminal electrode A6 in the same layer.
[0055] Giving a description on the electrode layer 127, one end of
an extraction electrode B7 is connected with an internal electrode
A7 in the same layer, and the other end of the same is led onto the
side surface of the ceramic porcelain to be connected with the
terminal electrode 27. Therefore, the internal electrode A7 is
electrically connected with the terminal electrode 27 through the
extraction electrode B7, and hence has the same polarity as the
terminal electrode 27, i.e., a negative polarity. Dummy electrodes
D71 to D73 are respectively connected with the terminal electrodes
21, 23 and 25 having a negative polarity in such a manner that
these dummy electrodes have the same polarity in a relationship
with the internal electrode A7 in the same layer.
[0056] Finally, giving a description on the electrode layer 128,
one end of an extraction electrode B8 is connected with an internal
electrode A8 in the same layer, and the other end of the same is
led onto the side surface of the ceramic porcelain to be connected
with the terminal electrode 28. Therefore, the internal electrode
A8 is electrically connected with the terminal electrode 28 through
the extraction electrode B8, and hence has the same polarity as the
terminal electrode 28, i.e., a positive polarity. Dummy electrodes
D81 to D83 are respectively connected with the terminal electrodes
22, 24 and 26 having a positive polarity in such a manner that
these dummy electrodes have the same polarity in a relationship
with the internal electrode A8 in the same layer.
[0057] The basic configuration of each of the electrode layers 121
to 128 is as described above. A detailed configuration of the same
will now be described while taking the electrode layer 121 as an
example.
[0058] FIG. 4 is an enlarged view of a part in the vicinity of the
electrode layers 121 and 122 in relation to the cross section
depicted in FIG. 2. Referring to FIG. 4, the extraction electrode
B1 of the electrode layer 121 is integrally formed with the
internal electrode A1 in the same layer.
[0059] Furthermore, the extraction electrode B1 is formed to be
thicker than the internal electrode A1 in the vicinity of the side
surface 101 of the ceramic porcelain 1. In more detail, a layer
thickness t3 of the extraction electrode B1 is larger than a layer
thickness t1 of the internal electrode A1. The layer thickness t3
of the extraction electrode B1 is a layer thickness as seen from a
part in the vicinity of the side surface 101 of the ceramic
porcelain 1, and the layer thickness t1 of the internal electrode
A1 is a layer thickness of a substantive part which functions as a
capacitance electrode.
[0060] The layer thickness t3 of the extraction electrode B1 is
determined while considering the layer thickness t1 of the internal
electrode A1, a layer thickness t5 of the ceramic layer as seen
from a part between the internal electrodes, and others. A
preferable range of the layer thickness t3 is as follows:
t1<t3<t5 (1)
A more preferable range of the same is as follows:
1.5.times.t1<t3<0.9.times.t5 (2)
Giving numerical examples, when the layer thickness t1 of the
internal electrode A1 is 2 .mu.m and the layer thickness t5 of the
ceramic layer as seen from the part between the internal electrodes
is 6 .mu.m, the layer thickness t3 of the extraction electrode B1
can be set to 4 .mu.m.
[0061] The internal electrodes A2 to A8 and the extraction
electrodes B2 to B8 in the electrode layers 122 to 128 can have the
same configurations in the electrode layer 121.
[0062] Again referring to FIG. 2, a description will be given. The
first outer layer portion 11 of the ceramic porcelain 1 is provided
with dummy electrode layers 111 to 11n. Likewise, the second outer
layer portion 13 is provided with dummy electrode layers 131 to
13n. These dummy electrode layers are formed of, e.g., Ni and
superimposed with the ceramic layers held therebetween. The dummy
electrode layers 111 to 11n in the first outer layer portion 11
will now be described on behalf of the above-described dummy
electrode layers.
[0063] FIG. 5 is a pattern diagram showing configurations of the
dummy electrode layers 111 to 11n. First, the dummy electrode layer
111 will be described. The dummy electrode layer 111 includes outer
layer dummy electrodes E11 to E14, and one end of each of the outer
layer dummy electrode E11 to E14 is led onto the side surface of
the ceramic porcelain to be connected with a terminal electrode
selected from the terminal electrodes 21 to 28. In detail, the
outer layer dummy electrodes E11 and E12 are led onto one side
surface of the ceramic porcelain to be respectively connected with
the terminal electrodes 22 and 24 having the positive polarity, and
the outer layer dummy electrodes E13 and E14 are led onto the other
side surface of the ceramic porcelain to be respectively connected
with the terminal electrodes 26 and 28 having the positive
polarity.
[0064] The dummy electrode layer 112 will now be described. The
dummy electrode layer 112 includes outer layer dummy electrodes E21
to E24, and one end of each of the outer layer dummy electrodes E21
to E24 is led onto the side surface of the ceramic porcelain to be
connected with a terminal electrode selected from the terminal
electrodes 21 to 28. In detail, the outer layer dummy electrodes
E21 and E22 are led onto one side surface of the ceramic porcelain
to be respectively connected with the terminal electrodes 21 and 23
having the negative polarity, and the outer layer dummy electrodes
E23 and E24 are led onto the other side surface of the ceramic
porcelain to be respectively connected with the terminal electrodes
25 and 27 having the negative polarity.
[0065] The dummy electrode layers 113 to 11n can have the same
configuration. For example, of the dummy electrode layers 113 to
11n, a layer having an odd reference number may have the same
configuration as the dummy electrode layer 111, and a layer having
an even reference number may have the same configuration as the
dummy electrode layer 112.
[0066] Furthermore, the dummy electrode layers 131 to 13n in the
second outer layer portion 13 can have the same configurations as
the dummy electrode layers 111 to 11n in the first outer layer
portion 11. For example, the dummy electrode layers 131 to 13n may
have the same configurations as the dummy electrode layers 11n to
111 so that a symmetrical configuration can be assured with the
electrode layers 121 to 128 in the inner layer portion 12 at the
center.
[0067] Moreover, each of the number of the dummy electrode layers
arranged in the first outer layer portion 11 and the number of the
dummy electrode layers arranged in the second outer layer portion
13 can take an arbitrary number.
[0068] As described above with reference to FIGS. 1 and 2, the
multi-terminal type laminated capacitor according to the present
invention includes the ceramic porcelain 1 and the plurality of
electrode layers 121 to 128 superimposed in the ceramic porcelain 1
with the ceramic layers therebetween. Therefore, the basic
configuration of the multi-terminal type laminated capacitor can be
obtained.
[0069] Further, as described above with reference to FIG. 3, the
electrode layers 121 to 128 include the internal electrodes A1 to
A8 and the extraction electrodes B1 to B8. One end of each of these
extraction electrodes B1 to B8 is connected with each of the
internal electrodes A1 to A8 in the same layer, and the other end
of the same is led onto the side surface of the ceramic porcelain
1. Therefore, the terminal electrodes 21 to 28 can be formed on the
side surfaces of the ceramic porcelain 1, thereby providing the
joining structures with respect to the extraction electrodes B1 to
B8.
[0070] In the present invention, each of the extraction electrodes
B1 to B8 is formed to be thicker than each of the internal
electrodes A1 to A8 in the same layer. According to this
configuration, even if the number of layers is reduced or a layer
thickness of each of the internal electrodes A1 to A8 is decreased
in order to increase the ESR, each of the extraction electrodes B1
to B8 can assure a layer thickness which is required for the
joining structure with respect to each of the terminal electrodes
21 to 28. For example, referring to FIG. 4, the layer thickness t3
of the extraction electrode B1 is larger than the layer thickness
t1 of the internal electrode A1. Therefore, even if the layer
thickness t1 of the internal electrode A1 is reduced, the layer
thickness t3 required for the joining structure with respect to the
terminal electrode 21 can be assured for the extraction electrode
B1.
[0071] Therefore, the sufficient joining structure can be provided
to each of the terminal electrodes 21 to 28, thus assuring the
adhesion of the terminal electrodes 21 to 28 with respect to the
ceramic porcelain 1. Accordingly, terminal electrode exfoliation
due to a thermal shock can be avoided.
[0072] Although the illustrated embodiment is provided with the
eight electrode layers 121 to 128, the present invention is not
restricted to such a configuration, and the number of the electrode
layers can take an arbitrary number equal to or above two.
[0073] Further, as described above with reference to FIG. 3, the
electrode layers 121 to 128 include the dummy electrodes D11 to
D83, and one end of each of these dummy electrodes is led onto the
side surface of the ceramic porcelain 1 to be connected with a
selected terminal electrode. For example, one end of each of the
dummy electrodes D31, D51 and D71 is led onto the side surface of
the ceramic porcelain 1 to be connected with the terminal electrode
21. Therefore, the terminal electrode 21 can be provided with the
joining structure with respect to the extraction electrode B1 as
well as the joining structure with respect to the dummy electrodes
D31, D51 and D57, whereby the adhesion of the terminal electrode 21
with respect to the ceramic porcelain 1 can be increased. This is
also applied to the other terminal electrodes 22 to 28.
[0074] Additionally, each of the dummy electrodes D11 to D83 has
the same polarity as seen from the relationship with the internal
electrode in the same layer. For example, the dummy electrodes D11
to D13 have the same polarity, i.e., the negative polarity as seen
from the relationship with the internal electrode A1 (the negative
polarity) in the same layer. Therefore, a short-circuit defect
between the internal electrode A1 and the dummy electrodes D11 to
D13 can be avoided. This is also applied to the other internal
electrodes A2 to A8.
[0075] Although each of the dummy electrodes D11 to D83 is formed
to have the same thickness as each of the internal electrodes A1 to
A8 in the same layer in the illustrated embodiment, each of the
dummy electrodes D11 to D83 may be formed to be thicker than each
of the internal electrodes A1 to A8 in the same layer as different
from the foregoing embodiment. According to this configuration,
even if the number of layers is reduced or a layer thickness of
each of the internal electrodes A1 to A8 is decreased to increase
the ESR, a layer thickness required for the joining structure with
respect to each of the terminal electrodes 21 to 28 can be assured
for each of the dummy electrodes D11 to D83, thereby further
increasing the adhesion of the terminal electrodes 21 to 28 with
respect to the ceramic porcelain 1.
[0076] <Manufacturing Method of Multi-Terminal Type Laminated
Capacitor>
[0077] An embodiment of a manufacturing method of a multi-terminal
type laminated capacitor according to the present invention will
now be described. This embodiment relates to a manufacturing method
of the multi-terminal type laminated capacitor depicted in FIGS. 1
to 5.
[0078] FIG. 6 is a view showing a step included in one embodiment
of a manufacturing method of a multi-terminal type laminated
capacitor according to the present invention, and FIG. 7 is a
partially enlarged end elevational view taken along a line 7-7 in
FIG. 6. The drawings show a region 621 which is provided in one of
electrode layers (e.g., an electrode layer 121) provided to a
multi-terminal type laminated capacitor as a representative
example.
[0079] Referring to FIGS. 6 and 7, an unbaked ceramic sheet (a
ceramic green sheet) 41 is attached on one surface of a support 3.
The unbaked ceramic sheet 41 is formed of a ceramic paste having a
ceramic powder, a solvent, a binder and others mixed therein, and
has a fixed thickness. Further, the support 3 is formed of an
appropriate flexible plastic film.
[0080] Next, as shown in FIGS. 6 and 7, an internal electrode layer
A1a, a first extraction electrode layer B1a and dummy electrode
layers D11a to D13a are formed on the unbaked ceramic sheet 41 in a
predetermined pattern. In the illustrated embodiment, the internal
electrode layer A1a and the first extraction electrode layer B1a
are integrally formed and have a predetermined thickness on the
unbaked ceramic sheet 41. Furthermore, each of the dummy electrode
layers D11a to D13a has the same thickness as the internal
electrode layer A1a and the first extraction electrode layer B1a.
These electrode layers are formed by printing a conductor paste.
The conductor paste can be obtained by mixing a conductor powder, a
solvent, a binder and others. As a printing method, there is a
screen printing method, a gravure printing method, an offset
printing method or the like.
[0081] Incidentally, although not shown, there are regions given to
other electrode layers (e.g., electrode layers 122 to 128) around
the region 621, and internal electrode layers A2a to A8a, first
extraction electrode layers B2a to B8a and dummy electrode layers
D21a to D83a are likewise formed in these regions.
[0082] Subsequently, as shown in FIG. 8, a second extraction
electrode layer B1b is formed on the first extraction electrode
layer B1a. The second extraction electrode layer B1b is formed in
the same shape pattern as the first extraction electrode layer B1a,
and has a predetermined thickness on the first extraction electrode
layer B1a. The second extraction electrode layer B1b is formed by
printing a conductor paste like the internal electrode layer A1a
and the first extraction electrode layer B1a. In the illustrated
embodiment, the second extraction electrode layer B1a constituted
of a single layer. As different from this, the second electrode
layer may be constituted of a plurality of layers, and the second
extraction electrode layer having such a configuration can be
obtained by repeating printing of the conductor paste more than
once.
[0083] Then, as shown in FIG. 9, a step absorption layer 43 is
formed on the internal electrode layer A1a. The step absorption
layer 43 functions to absorb a step generated between the internal
electrode layer A1a and the second extraction electrode layer B1b.
In the illustrated embodiment, the step absorption layer 43 is also
provided in a margin region in which the internal electrode layer
A1a, the first extraction electrode layer B1a and the dummy
electrode layers D11a to D13a are not provided in the region 621 on
the unbaked ceramic sheet 41, and functions to absorb a step
produced between the margin region and the second extraction
electrode layer B1b. It is preferable for a surface of the step
absorption layer 43 to be formed at the same height position as a
surface of the second extraction electrode layer B1b. The step
absorption layer 43 is basically formed of a ceramic paste having
the same configuration as the unbaked ceramic sheet 41.
[0084] Then, as shown in FIG. 10, a laminated body is formed such
that the unbaked ceramic sheet 41 having the internal electrode
layer A1a, the first and second extraction electrode layers B1a and
B1b and the step absorption layer 43 formed thereon is used as each
of unit layers 521 to 528 in the laminated body. In the illustrated
embodiment, the laminated body is formed such that an unbaked
ceramic sheet 42 having an outer layer dummy electrode layer E1a
formed thereon is used as each of outer unit layers 511 to 51n and
531 to 53n in addition to these unit layers 521 to 528. In the
illustrated embodiment, although a technique of superimposing the
outer unit layers 511 to 51n, the unit layers 521 to 528 and the
outer unit layers 531 to 53n on a lamination base 7 is adopted as a
technique of configuring the laminated body, the present invention
is not restricted this technique. For example, it is possible to
adopt a technique of repeating the ceramic green sheet (the unbaked
ceramic sheet) forming step or the electrode layer printing step on
the flexible support for the necessary number of times.
[0085] When a pressure is applied to the thus obtained sheet
laminated body and then cut into a one-chip region, a laminated
green chip is obtained. Furthermore, when steps such as removal of
the binder, baking, formation of a terminal electrode and others
are carried out, the multi-terminal type laminated capacitor shown
in FIGS. 1 to 5 can be obtained.
[0086] In the manufacturing method of the multi-terminal type
laminated capacitor according to the present invention, the
internal electrode layer A1a and the first extraction electrode
layer B1a are formed on the unbaked ceramic sheet 41 as shown in
FIGS. 6 and 7, and then the second extraction electrode layer B1b
is formed on the first extraction electrode layer B1a as shown in
FIG. 8. Therefore, there can be obtained a basic configuration
including the internal electrode and the extraction electrodes each
of which is formed to be thicker than the internal electrode in the
same layer.
[0087] Thereafter, as shown in FIG. 10, the laminated body is
formed with the unbaked ceramic sheet 41 having the internal
electrode layer A1a and the first and second extraction electrode
layers B1a and B1b formed thereon being determined as each of the
unit layers 521 to 528. Therefore, the multi-terminal type
laminated capacitor according to the present invention can be
formed. In detail, the unit layers 521 to 528 constitute the inner
layer portion 12 of the ceramic porcelain 1 shown in FIG. 2, and
the outer unit layers 511 to 51n and 531 to 53n constitute the
outer layer portions 11 and 13 of the ceramic porcelain 1.
[0088] In case of the illustrated embodiment, the step absorption
layer 43 made of the ceramic paste is formed on the internal
electrode layer A1a as shown in FIG. 9. Then, as shown in FIG. 10,
the laminated body is formed with the unbaked ceramic sheet 41
having the internal electrode layer A1a, the first and second
extraction electrode layers B1a and B1b and the step absorption
layer 43 formed thereon being determined as each of the unit layers
521 to 528. According to this step absorption layer 43, a step
generated between the internal electrode layer A1a and the second
extraction electrode layer B1b can be absorbed.
[0089] In the configuration depicted in FIG. 9, although the
surface of the step absorption layer 43 is formed at the same
height position as the surface of the second extraction electrode
layer B1b, the present invention is not restricted to this
configuration. This point will become apparent from the fact that a
step absorbing function can be obtained, for example, even if the
surface of the step absorption layer is placed at a height position
lower than the surface of the second extraction electrode
layer.
* * * * *