U.S. patent application number 16/279189 was filed with the patent office on 2020-02-06 for multilayer ceramic capacitor including adhesive layer between side margin portion and body and method of manufacturing the same.
The applicant listed for this patent is SAMSUNG ELECTRO-MECHANICS CO., LTD.. Invention is credited to Ji Hong JO, Jang Yeol LEE, Yong PARK.
Application Number | 20200043668 16/279189 |
Document ID | / |
Family ID | 68420429 |
Filed Date | 2020-02-06 |
United States Patent
Application |
20200043668 |
Kind Code |
A1 |
PARK; Yong ; et al. |
February 6, 2020 |
MULTILAYER CERAMIC CAPACITOR INCLUDING ADHESIVE LAYER BETWEEN SIDE
MARGIN PORTION AND BODY AND METHOD OF MANUFACTURING THE SAME
Abstract
A multilayer ceramic capacitor includes a ceramic body including
a dielectric layer, a first surface and a second surface opposing
each other, a third surface and a fourth surface connecting the
first surface and the second surface, respectively; internal
electrodes disposed inside the ceramic body and exposed to the
first and second surfaces, and having one ends exposed to the third
surface or the fourth surface; a first side margin portion and a
second side margin portion disposed on sides of the internal
electrodes exposed to the first and second surfaces; and adhesive
layers disposed between the first surface of the ceramic body and
the first side margin portion and between the first surface of the
ceramic body and the second side margin portion, respectively. An
average thickness of each of the first and second side margin
portions is 2 .mu.m or more and 10 .mu.m or less.
Inventors: |
PARK; Yong; (Suwon-si,
KR) ; LEE; Jang Yeol; (Suwon-si, KR) ; JO; Ji
Hong; (Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAMSUNG ELECTRO-MECHANICS CO., LTD. |
Suwon-si |
|
KR |
|
|
Family ID: |
68420429 |
Appl. No.: |
16/279189 |
Filed: |
February 19, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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16169897 |
Oct 24, 2018 |
|
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16279189 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C04B 35/645 20130101;
C04B 35/468 20130101; C04B 2237/704 20130101; C04B 37/005 20130101;
H01G 4/224 20130101; C04B 2235/6582 20130101; C04B 2237/068
20130101; C04B 2237/346 20130101; H01G 4/308 20130101; C04B 37/006
20130101; H01G 4/12 20130101; H01G 4/005 20130101; H01G 4/30
20130101; B32B 18/00 20130101; C04B 2237/80 20130101 |
International
Class: |
H01G 4/30 20060101
H01G004/30; H01G 4/12 20060101 H01G004/12; H01G 4/005 20060101
H01G004/005; C04B 37/00 20060101 C04B037/00; C04B 35/468 20060101
C04B035/468 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 3, 2018 |
KR |
10-2018-0090717 |
Claims
1. A multilayer ceramic capacitor comprising: a ceramic body
including a dielectric layer, a first surface and a second surface
opposing each other, a third surface and a fourth surface
connecting the first surface and the second surface, respectively;
a plurality of internal electrodes disposed inside the ceramic body
and exposed to the first and second surfaces, and having one ends
exposed to the third surface or the fourth surface; a first side
margin portion and a second side margin portion disposed on sides
of the plurality of internal electrodes exposed to the first and
second surfaces, respectively; adhesive layers disposed between the
first surface of the ceramic body and the first side margin portion
and between the second surface of the ceramic body and the second
side margin portion, respectively; a first external electrode
disposed on the third surface of the ceramic body and covering
respective first portions of the first, second, fifth, and sixth
surfaces; and a second external electrode disposed on the fourth
surface of the ceramic body and covering respective second portions
of the first, second, fifth, and sixth surfaces, wherein an average
thickness of each of the first and second side margin portions is 2
.mu.m or more and 10 .mu.m or less, the first side margin portion
and the second side margin portion have a density greater than that
of the adhesive layers, a thickness of each of the dielectric
layers is 0.4 .mu.m or less and a thickness of each of the
plurality of internal electrodes is 0.4 .mu.m or less, and each of
the plurality of internal electrodes is composed of a same material
extending between the adhesive layers respectively disposed on the
first and second surfaces of the ceramic body.
2. The multilayer ceramic capacitor of claim 1, wherein a ratio of
a thickness of the first side margin portion or the second side
margin portion in contact with a side of the internal electrode
disposed in an outermost portion with respect to a thickness of the
first side margin portion or the second side margin portion in
contact with an end of the internal electrode disposed in a center
portion among the plurality of internal electrodes is 1.0 or
less.
3. The multilayer ceramic capacitor of claim 1, wherein a ratio of
a thickness of the first side margin portion or the second side
margin portion in contact with an edge of the ceramic body with
respect to a thickness of the first side margin portion or the
second side margin portion in contact with an end of the internal
electrode disposed in a center portion among the plurality of
internal electrodes is 1.0 or less.
4. (canceled)
5. The multilayer ceramic capacitor of claim 1, wherein an average
thickness of each of the adhesive layers is less than that of each
of the first and second side margin portions.
6. The multilayer ceramic capacitor of claim 1, wherein the
adhesive layers are made of a material different from that used to
make the first and second side margin portions.
7. A method of manufacturing a multilayer ceramic capacitor, the
method comprising: preparing a first ceramic green sheet having a
plurality of first internal electrode patterns formed at
predetermined intervals and a second ceramic green sheet having a
plurality of second internal electrode patterns formed at
predetermined intervals; forming a ceramic green sheet stacked body
by stacking the first ceramic green sheet and the second ceramic
green sheet such that the first internal electrode pattern and the
second internal electrode pattern overlap with other in a stacking
direction of the first and second ceramic green sheets; cutting the
ceramic green sheet stacked body such that sides of the first
internal electrode pattern and the second internal electrode
pattern are exposed in a width direction; forming a first side
margin portion and a second side margin portion by attaching a side
surface ceramic sheet on which an adhesive is applied to the
exposed side surfaces of the sides of the first internal electrode
pattern and the second internal electrode pattern; sintering the
ceramic green stacked body with the first and second side margin
portions to form a ceramic body, the ceramic body having first and
second surfaces on which the first and second side margin portions
are respectively disposed, third and fourth surfaces from which
respective ends of the first and second internal electrode patterns
are alternatively exposed, and fifth and sixth surfaces connected
to the first to the fourth surfaces, respectively; forming a first
external electrode on the third surface of the ceramic body and
covering respective first portions of the first, second, fifth, and
sixth surfaces; and forming a second external electrode disposed on
the fourth surface of the ceramic body and covering respective
second portions of the first, second, fifth, and sixth surfaces,
wherein a thickness of the first and second ceramic green sheets is
0.6 .mu.m or less, and a thickness of the first and second internal
electrode patterns is 0.5 .mu.m or less, the first side margin
portion and the second side margin portion have a density greater
than that of the adhesive layers, after the sintering, a thickness
of an internal electrode made of one of the first and second
internal electrode patterns is 0.4 .mu.m or less, and a thickness
of a dielectric layer made of one of the first and second ceramic
green sheets and being in contact with the internal electrode is
0.4 .mu.m or less, and each internal electrode is composed of a
same material extending between the adhesive layers respectively
disposed on the first and second surfaces of the ceramic body.
8. The method of claim 7, wherein the adhesive is applied onto the
side surface ceramic sheet by using a printing method.
9. The method of claim 7, wherein an average thickness of each of
the first and second side margin portions is 2 .mu.m or more and 10
.mu.m or less.
10. The method of claim 7, wherein a ratio of a thickness of the
first side margin portion or the second side margin portion in
contact with a side of the internal electrode disposed in an
outermost position with respect to a thickness of the first side
margin portion or the second side margin portion in contact with an
end of the internal electrode pattern disposed in a center portion
among the plurality of first and second internal electrode patterns
is 1.0 or less.
11. The method of claim 7, wherein a ratio of a thickness of the
first side margin portion or the second side margin portion in
contact with an edge of the ceramic body with respect to a
thickness of the first side margin portion or the second side
margin portion in contact with an end of the internal electrode
disposed in a center portion among the plurality of first and
second internal electrodes is 1.0 or less.
12. (canceled)
13. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation application of U.S.
patent application Ser. No. 16/169,897 filed on Oct. 24, 2018,
which claims benefit of priority to Korean Patent Application No.
10-2018-0090717 filed on Aug. 3, 2018 in the Korean Intellectual
Property Office, the disclosure of which is incorporated herein by
reference in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates to a multilayer ceramic
capacitor capable of increasing interfacial adhesion between a
ceramic body and a side margin portion to improve reliability, and
a method of manufacturing the same.
BACKGROUND
[0003] In general, electronic elements using a ceramic material
such as a capacitor, an inductor, a piezoelectric element, a
varistor or a thermistor include a ceramic body formed of a ceramic
material, an internal electrode formed inside the body, and an
external electrode provided on the surface of the ceramic body to
be connected to the internal electrode.
[0004] Recently, owing to the miniaturization and
multifunctionalization of electronic products, since there is also
the tendency of miniaturization and high functionality of chip
parts, a multilayer ceramic capacitor is also required to have a
small size and to be a high capacity product.
[0005] In order to realize the small sized and high capacity
multilayer ceramic capacitor, it is necessary to maximize the
electrode effective area (increase the effective volume fraction
necessary for capacity implementation).
[0006] In order to implement the small sized and high capacity
multilayer ceramic capacitor as described above, in manufacturing
the multilayer ceramic capacitor, an internal electrode may be
exposed in the width direction of a body, and thus the internal
electrode width direction area is maximized through the marginless
design. A method of separately attaching a margin portion to a
width direction electrode exposed surface of a chip in an after
manufacturing step of manufacturing the chip and before sintering
the chip is applied.
[0007] However, in the above method, when a side ceramic green
sheet is attached to a side surface of the ceramic body through
thermocompression bonding, a phenomenon occurs in which a side
margin portion is not completely bonded to the side surface of the
ceramic body but is partially separated due to weak adhesion
between the side margin portion and the ceramic body.
[0008] Such a phenomenon of partial separation of the side margin
portion may cause appearance defects and may cause deterioration of
insulation resistance characteristics and moisture resistance
reliability defects.
[0009] In particular, when an excessive thermal compression process
is performed, so as to increase the interfacial adhesion between
the ceramic body and the side margin portion in an ultra-small and
high-capacity product, damage may occur to a dielectric layer
having a reduced thickness and the internal electrode, causing a
problem in which the possibility of deterioration of electrical
characteristics and the occurrence of defects further
increases.
[0010] Therefore, there is a need for research into increasing
interfacial adhesion between the ceramic body and the side margin
portion in ultra-small and high-capacity products.
SUMMARY
[0011] An aspect of the present disclosure may provide a multilayer
ceramic capacitor capable of increasing interfacial adhesion
between a ceramic body and a side margin portion to improve
reliability, and a method of manufacturing the same.
[0012] According to an aspect of the present disclosure, a
multilayer ceramic capacitor may include a ceramic body including a
dielectric layer, a first surface and a second surface opposing
each other, a third surface and a fourth surface connecting the
first surface and the second surface, respectively; a plurality of
internal electrodes disposed inside the ceramic body and exposed to
the first and second surfaces, and having one ends exposed to the
third surface or the fourth surface; a first side margin portion
and a second side margin portion disposed on sides of the plurality
of internal electrodes exposed to the first and second surfaces,
respectively; and adhesive layers disposed between the first
surface of the ceramic body and the first side margin portion and
between the second surface of the ceramic body and the second side
margin portion, respectively. An average thickness of each of the
first and second side margin portions may be 2 .mu.m or more and 10
.mu.m or less.
[0013] According to another aspect of the present disclosure, a
method of manufacturing a multilayer ceramic capacitor may include
preparing a first ceramic green sheet having a plurality of first
internal electrode patterns formed at predetermined intervals and a
second ceramic green sheet having a plurality of second internal
electrode patterns formed at predetermined intervals; forming a
ceramic green sheet stacked body by stacking the first ceramic
green sheet and the second ceramic green sheet such that the first
internal electrode pattern and the second internal electrode
pattern overlap with other in a stacking direction of the first and
second ceramic green sheets; cutting the ceramic green sheet
stacked body such that sides of the first internal electrode
pattern and the second internal electrode pattern are exposed in a
width direction; and forming a first side margin portion and a
second side margin portion by attaching a side surface ceramic
sheet on which an adhesive is applied to the exposed side surfaces
of the sides of the first internal electrode pattern and the second
internal electrode pattern, wherein a thickness of the first and
second ceramic green sheets is 0.6 .mu.m or less, and a thickness
of the first and second internal electrode patterns is 0.5 .mu.m or
less.
BRIEF DESCRIPTION OF DRAWINGS
[0014] The above and other aspects, features, and advantages of the
present disclosure will be more clearly understood from the
following detailed description taken in conjunction with the
accompanying drawings, in which:
[0015] FIG. 1 is a schematic perspective view showing a multilayer
ceramic capacitor according to an exemplary embodiment in the
present disclosure;
[0016] FIG. 2 is a perspective view showing an appearance of a
ceramic body of FIG. 1;
[0017] FIG. 3 is a perspective view showing a ceramic green sheet
stacked body before sintering of the ceramic body of FIG. 2;
[0018] FIG. 4 is a side view seen from a direction A in FIG. 2;
and
[0019] FIGS. 5A to 5F are cross-sectional views and perspective
views schematically showing a method of manufacturing a multilayer
ceramic capacitor according to another exemplary embodiment in the
present disclosure.
DETAILED DESCRIPTION
[0020] Hereinafter, exemplary embodiments in the present disclosure
will now be described in detail with reference to the accompanying
drawings.
[0021] FIG. 1 is a schematic perspective view showing a multilayer
ceramic capacitor 100 according to an exemplary embodiment in the
present disclosure.
[0022] FIG. 2 is a perspective view showing an appearance of a
ceramic body 110 of FIG. 1.
[0023] FIG. 3 is a perspective view showing a ceramic green sheet
stacked body before sintering of the ceramic body 110 of FIG.
2.
[0024] FIG. 4 is a side view seen from a direction A in FIG. 2.
[0025] Referring to FIGS. 1 to 4, a multilayer ceramic capacitor
100 according to an exemplary embodiment in the present disclosure
includes the ceramic body 110, a plurality of internal electrodes
121 and 122 formed inside the ceramic body 110, and external
electrodes 131 and 132 formed on the outer surface of the ceramic
body 110.
[0026] The ceramic body 110 may have a first surface 1 and a second
surface 2 opposing each other and a third surface 3 and a fourth
surface 4 connecting the first surface 1 and the second surface 2,
respectively, and a fifth surface 5 and a sixth surface 6 which are
an upper surface and a lower surface, respectively.
[0027] The first surface 1 and the second surface 2 may face each
other in a width direction W of the ceramic body 110. The third
surface 3 and the fourth surface 4 may be defined as surfaces
opposing each other in a longitudinal direction L of the ceramic
body 110. The fifth surface 5 and the sixth surface 6 may be
defined as surfaces opposing each other in a thickness direction T
of the ceramic body 110.
[0028] The shape of the ceramic body 110 is not particularly
limited, but may be a rectangular parallelepiped shape as
shown.
[0029] The plurality of internal electrodes 121 and 122 formed
inside the ceramic body 110 have one ends exposed to the third
surface 3 or the fourth surface 4 of the ceramic body 110.
[0030] The internal electrodes 121 and 122 may have a pair of the
first internal electrode 121 and the second internal electrode 122
having different polarities.
[0031] One end of the first internal electrode 121 may be exposed
to the third surface 3. One end of the second internal electrode
122 may be exposed to the fourth surface 4.
[0032] The other ends of the first internal electrode 121 and the
second internal electrode 122 are formed at regular intervals from
the third surface 3 or the fourth surface 4.
[0033] The first and second external electrodes 131 and 132 may be
formed on the third and fourth surfaces 3 and 4 of the ceramic body
110 and electrically connected to the internal electrode.
[0034] The multilayer ceramic capacitor 100 according to an
exemplary embodiment in the present disclosure includes the
plurality of internal electrodes 121 and 122 disposed inside the
ceramic body 110, exposed to the first and second surfaces 1 and 2
and having one ends exposed to the third surface 3 or the fourth
surface 4, and a first side margin portion 112 and a second side
margin portion 113 disposed on end portions of the internal
electrodes 121 and 122 exposed to the first and second surfaces 1
and 2.
[0035] The plurality of internal electrodes 121 and 122 are formed
inside the ceramic body 110. Each end of the plurality of internal
electrodes 121 and 122 is exposed to the first surface 1 and the
second surface 2 that are width direction surfaces of the ceramic
body 110. The first side margin portion 112 and the second side
margin portion 113 are disposed on the exposed end portions.
[0036] An average thickness of each of the first side margin
portion 112 and the second side margin portion 113 may be 2 .mu.m
or more and 10 .mu.m or less. The average thickness of a side
margin portion may be measured from an image obtained by scanning a
cross section of the ceramic body 110 in the thickness direction
using a scanning electron microscope (SEM). For example, a
thickness at the predetermined number of points, for example,
thirty points, that are equidistant from each other in the
thickness direction may be measured from the image obtained by
scanning a cross-section of the ceramic body 110 in a
width-thickness (W-T) direction taken along a central portion of
the ceramic body 110 in the length (L) direction using the scanning
electron microscope (SEM), thereby determining the average
thickness of a side margin portion by dividing a sum of thicknesses
measured at the predetermined number of points by the predetermined
number.
[0037] According to an exemplary embodiment in the present
disclosure, the ceramic body 110 includes a stack structure in
which a plurality of dielectric layers 111 are stacked and the
first side margin portion 112 and the second side margin portion
113 disposed in both side surfaces of the stack structure.
[0038] The plurality of dielectric layers 111 may be in a sintered
state such that boundaries between adjacent dielectric layers may
be integrated not to be confirmed.
[0039] The length of the ceramic body 110 corresponds to a distance
from the third surface 3 to the fourth surface 4 of the ceramic
body 110.
[0040] The length of the dielectric layer 111 forms the distance
between the third surface 3 and the fourth surface 4 of the ceramic
body 110.
[0041] According to an exemplary embodiment in the present
disclosure, the length of the ceramic body 110 may be 400 to 1400
.mu.m but is not limited thereto. More specifically, the length of
the ceramic body 110 may be 400 to 800 .mu.m, or 600 to 1400
.mu.m.
[0042] The internal electrodes 121 and 122 may be formed on the
dielectric layer 111 and may be formed inside the ceramic body 110
with a single dielectric layer interposed therebetween by
sintering.
[0043] Referring to FIG. 3, the first internal electrode 121 is
formed on the dielectric layer 111. The first internal electrode
121 is not formed entirely with respect to the longitudinal
direction of the dielectric layer 111. That is, one end of the
first internal electrode 121 may be formed at a predetermined
distance from the fourth surface 4 of the ceramic body 110, and the
other end of the first internal electrode 121 may be formed up to
the third surface 3 and exposed to the third surface 3.
[0044] The end of the first internal electrode 121 exposed to the
third surface 3 of the ceramic body 110 is connected to the first
external electrode 131.
[0045] To the contrary of the first internal electrode 121, one end
of the second internal electrode 122 is formed at a predetermined
distance from the third surface 3 and the other end of the second
internal electrode 122 is exposed to the fourth surface 4 and is
connected to the second external electrode 132.
[0046] The dielectric layer 111 may have the same width as that of
the first internal electrode 121. That is, the first internal
electrode 121 may be formed entirely in the width direction of the
dielectric layer 111. The dielectric layer 111 may have the same
width as that of the second internal electrode 122. That is, the
second internal electrode 122 may be formed entirely in the width
direction of the dielectric layer 111.
[0047] According to an exemplary embodiment in the present
disclosure, the width of the dielectric layer 111 and the widths of
the internal electrodes 121 and 122 may be 100 .mu.m to 900 .mu.m,
but not limited thereto. More specifically, the width of the
dielectric layer 111 and the widths of the internal electrodes 121
and 122 may be 100 .mu.m to 500 .mu.m, or 100 .mu.m to 900
.mu.m.
[0048] As the ceramic body 110 is miniaturized, the thicknesses of
the side margin portions 112 and 113 may affect the electrical
characteristics of the multilayer ceramic capacitor 100. According
to an exemplary embodiment in the present disclosure, the
thicknesses of the side margin portions 112 and 113 are formed to
be 10 .mu.m or less, and the characteristic of the miniaturized
multilayer ceramic capacitor 100 may be improved.
[0049] In an exemplary embodiment in the present disclosure, the
internal electrodes 121 and 122 and the dielectric layer 111 are
simultaneously cut off and formed, and thus the widths of the
internal electrodes 121 and 122 and the width of the dielectric
layer 111 may be the same. This will be described in more detail
later.
[0050] In the present embodiment, the width of the dielectric layer
111 is formed to be the same as the widths of the internal
electrodes 121 and 122, and thus the ends of the internal
electrodes 121 and 122 may be exposed to the first and second
surfaces 1 and 2 in the width direction of the ceramic body
110.
[0051] The first side margin portion 112 and the second side margin
portion 113 may be formed on both side surfaces in the width
direction of the ceramic body 110 where the ends of the internal
electrodes 121 and 122 are exposed.
[0052] The thicknesses of the first side margin portion 112 and the
second side margin portion 113 may be 10 .mu.m or less. The smaller
the thicknesses of the first side margin portion 112 and the second
side margin portion 113, the relatively wider the overlapping area
of the internal electrodes 121 and 122 formed inside the ceramic
body 110.
[0053] The thicknesses of the first side margin portion 112 and the
second side margin portion 113 are not particularly limited as long
as the thicknesses are able to prevent short-circuit of the
internal electrodes 121 and 122 exposed to the side surfaces of the
ceramic body 110. For example, the thicknesses of the first side
margin portion 112 and the second side margin portion 113 may be 2
.mu.m or more.
[0054] If the thicknesses of the first and second side margin
portions 112 and 113 are less than 2 .mu.m, the mechanical strength
against external impact may decrease. If the thicknesses of the
first and second side margin portions 112 and 113 exceed 10 .mu.m,
causing the overlapping area of the internal electrodes 121 and 122
to be relatively reduced, it may be difficult to secure high
capacity of the multilayer ceramic capacitor 110.
[0055] In order to maximize the capacity of a multilayer ceramic
capacitor, a method of making a dielectric layer thinner, a method
of highly stacking the thinned dielectric layer, a method of
improving the coverage of internal electrodes, etc. are
considered.
[0056] Further, a method of improving the overlapping area of
internal electrodes forming the capacity is considered.
[0057] In order to increase the overlapping area of the internal
electrodes, a region of a margin portion in which the internal
electrodes are not formed must be minimized.
[0058] In particular, as the multilayer ceramic capacitor is
miniaturized, the region of the margin portion must be minimized in
order to increase the overlap area of the internal electrodes.
[0059] According to the present embodiment, the internal electrodes
121 and 122 are formed in the entire width direction of the
dielectric layer 111, the thicknesses of the side margin portions
112 and 113 are set to 10 .mu.m or less, and thus the overlapping
area of the internal electrodes 121 and 122 is wide.
[0060] Generally, the thicknesses of the dielectric layer and the
internal electrodes become thinner as the dielectric layer becomes
highly stacked. Therefore, a phenomenon that the internal
electrodes are short-circuited may frequently occur. Also, when the
internal electrodes are formed only in a part of the dielectric
layer, a step difference due to the internal electrodes may be
generated, which may deteriorate the acceleration life and
reliability of the insulation resistance.
[0061] However, according to the present embodiment, even if the
thin internal electrodes and dielectric layer are formed, since the
internal electrodes are entirely formed in the width direction of
the dielectric layer, the overlapping area of the internal
electrodes increases, and thus the capacity of the multilayer
ceramic capacitor may be increased.
[0062] Also, the acceleration life of insulation resistance may be
improved by reducing the step difference due to the internal
electrodes, thereby providing the multilayer ceramic capacitor
having excellent capacity characteristic and excellent
reliability.
[0063] According to an exemplary embodiment in the present
disclosure, an adhesive layer 140 is disposed between the first
side 1 and the second side 2 of the ceramic body 110 and between
the first side margin portion 112 and the second side margin
portion 113.
[0064] A method of forming a first side margin portion and a second
side margin portion according to the related art includes attaching
side ceramic sheets to the side surfaces of a ceramic body having
exposed ends of a first internal electrode pattern and a second
internal electrode pattern and applying heat and pressure.
[0065] In this case, when the adhesion between the side margin
portion and the ceramic body is lowered, there is a problem that
the side ceramic sheets are separated, which may cause problems
such as appearance defects, reduced insulation resistance, and
reduced reliability of moisture resistance.
[0066] In order to prevent the above problems, according to the
related art, the side margin portion is formed by applying high
heat and pressure to enhance the adhesion between the side margin
portion and the ceramic body.
[0067] However, when such high heat and pressure are applied,
damage to the internal electrodes and the dielectric layer having
small thicknesses occurs, which may cause a problem that electric
characteristics such as short circuit deteriorate.
[0068] That is, since the thicknesses of the dielectric layer and
the internal electrodes must be small in the ultra-small and
high-capacity multilayer ceramic capacitor, the method of forming
the side margin portion by applying high heat and pressure
according to the related art as described above may cause
problems.
[0069] According to an exemplary embodiment in the present
disclosure, since the first side margin portion 112 and the second
side margin portion 113 are formed by attaching side ceramic sheets
on which an adhesive is applied to the side surfaces of the ceramic
body 110 having exposed ends of a first internal electrode pattern
and a second internal electrode pattern, even if low heat and
pressure are applied, the adhesion between the side margin portions
112 and 113 and the ceramic body 110 may be enhanced.
[0070] Accordingly, damage to the dielectric layer 111 and the
internal electrodes 121 and 122 may be minimized even in the ultra
small and high capacity multilayer ceramic capacitor 100 to which
the dielectric layer 111 and the internal electrodes 121 and 122
having small thicknesses are applied, thereby improving
reliability.
[0071] According to an exemplary embodiment in the present
disclosure, the ultra small multilayer ceramic capacitor 100
includes the dielectric layer 111 having the thickness of 0.4 .mu.m
or less and the internal electrodes 121 and 122 having the
thickness of 0.4 .mu.m or less.
[0072] As in an exemplary embodiment in the present disclosure,
when the dielectric layer 111 having the thickness of 0.4 .mu.m or
less and the internal electrodes 121 and 122 having the thickness
of 0.4 .mu.m or less are applied, in the case of forming the side
margin portion by applying high heat and pressure as in the related
art, damage may be applied to the dielectric layer 111 and the
internal electrodes 121 and 122, thereby causing deterioration of
electrical characteristics.
[0073] However, in a structure in which the adhesive layer 140 is
disposed between the first side 1 and the second side 2 of the
ceramic body 110 and between the first side margin portion 112 and
the second side margin portion 113 as in an exemplary embodiment in
the present disclosure, damage applied to the dielectric layer 111
having the thickness of 0.4 .mu.m or less and the internal
electrodes 121 and 122 having the thickness of 0.4 .mu.m or less
may be minimized, and thus the reliability may be improved.
[0074] The adhesive layer 140 may include a ceramic slurry
including ceramic powder and a binder. The ceramic powder may be
barium titanate powder, but is not necessarily limited thereto.
[0075] When the adhesive layer 140 includes the ceramic slurry
including the ceramic powder and the binder, since the adhesive
layer 140 is different from the first side margin portion 112 and
the second side margin portion 113 in the composition, a boundary
confirm between the adhesive layer 140 and the side margin may be
possible.
[0076] That is, even when the adhesive layer 140 includes the
ceramic powder, the composition of the adhesive layer 140 is
different from that of the first side margin portion 112 and the
second side margin portion 113, and thus the adhesive layer 140 is
different from the first side margin portion 112 and the second
side margin portion 113 in the density. An average thickness of the
adhesive layer 140 may be less than an average thickness of the
first side margin 112 and an average thickness of the second side
margin portion 113.
[0077] Specifically, the first side margin portion 112 and the
second side margin portion 113 may have a higher density than the
adhesive layer 140.
[0078] Referring to FIG. 4, a ratio of a thickness tc2 of the first
side margin portion 112 or the second side margin portion 113 in
contact with an end of the internal electrode disposed in the
outermost portion with respect to a thickness tc1 of the first side
margin portion 112 or the second side margin portion 113 in contact
with an end of the internal electrode disposed in the center
portion among the plurality of internal electrodes 121 and 122 may
be 1.0 or less.
[0079] A lowest value of the ratio of the thickness tc2 of the
first side margin portion 112 or the second side margin portion 113
in contact with the end of the internal electrode disposed in the
outermost portion with respect to the thickness tc1 of the first
side margin portion 112 or the second side margin portion 113 in
contact with the end of the internal electrode disposed in the
center portion is not particularly limited, but may be preferably
0.9 or more.
[0080] According to an exemplary embodiment in the present
disclosure, since the first or second side margin portion 112 or
113 is formed by attaching the ceramic green sheets to the side
surface of the ceramic body 110 unlike the related art, the
thickness of the first or second side margin portion 112 or 113 for
each position is constant or substantially the same.
[0081] That is, according to the related art, since the side margin
portion is formed by applying or printing a ceramic slurry, the
thickness of the side margin portion for each position has a large
deviation.
[0082] Specifically, according to the related art, the thickness of
the first side margin portion or the second side margin portion in
contact with the end of the internal electrode disposed in the
center portion of the ceramic body 110 is greater than the
thickness of another region.
[0083] For example, according to the related art, a ratio of the
thickness of the first side margin portion or the second side
margin portion in contact with the end of the internal electrode
disposed in the outermost portion with respect to the thickness of
the first side margin portion or the second side margin portion in
contact with the end of the internal electrode disposed in the
center portion is less than 0.9, and the deviation of the ratio is
large.
[0084] In the related art where the thickness of the side margin
portion has a large deviation for each position, since the side
margin portion occupies a large portion in the same-size multilayer
ceramic capacitor, a large size of a capacity forming portion may
not be secured, and thus it is difficult to secure high
capacity.
[0085] Meanwhile, in an exemplary embodiment in the present
disclosure, the average thickness of the first and second side
margin portions 112 and 113 is 2 .mu.m or more and 10 .mu.m or
less, and the ratio of the thickness tc2 of the first side margin
portion 112 or the second side margin portion 113 in contact with
the end of the internal electrode disposed in the outermost portion
with respect to the thickness tc1 of the first side margin portion
112 or the second side margin portion 113 in contact with the end
of the internal electrode disposed in the center portion among the
plurality of internal electrodes 121 and 122 is 0.9 or more and 1.0
or less, the thickness of the side margin portion is small and the
deviation in the thickness is small, and thus the large size of the
capacity forming portion may be secured.
[0086] As a result, the high capacity multilayer ceramic capacitor
may be implemented.
[0087] Meanwhile, referring to FIG. 4, a ratio of a thickness tc3
of the first side margin portion 112 or the second side margin
portion 113 in contact with an edge of the ceramic body 110 with
respect to the thickness tc1 of the first side margin portion 112
or the second side margin portion 113 in contact with the end of
the internal electrode disposed in the center portion among the
plurality of internal electrodes 121 and 122 may be 1.0 or
less.
[0088] A lowest value of the thickness tc3 of the first side margin
portion 112 or the second side margin portion 113 in contact with
the edge of the ceramic body 110 with respect to the thickness tc1
of the first side margin portion 112 or the second side margin
portion 113 in contact with the end of the internal electrode
disposed in the center portion may be preferably 0.9 or more.
[0089] Because of the above characteristic, the large size of the
capacity forming portion may be secured owing to a small thickness
deviation of the side margin portion for each region, and thus the
high capacity multilayer ceramic capacitor may be implemented.
[0090] FIGS. 5A to 5F are cross-sectional views and perspective
views schematically showing a method of manufacturing a multilayer
ceramic capacitor according to another exemplary embodiment in the
present disclosure.
[0091] According to another exemplary embodiment in the present
disclosure, the method of manufacturing the multilayer ceramic
capacitor includes preparing a first ceramic green sheet having a
plurality of first internal electrode patterns formed at
predetermined intervals and a second ceramic green sheet having a
plurality of second internal electrode patterns formed at
predetermined intervals, forming a ceramic green sheet stacked body
by stacking the first ceramic green sheet and the second ceramic
green sheet such that the first internal electrode pattern and the
second internal electrode pattern overlap with other in a stacking
direction of the first and second ceramic green sheets, cutting the
ceramic green sheet stacked body such that sides of the first
internal electrode pattern and the second internal electrode
pattern are exposed in a width direction, and forming a first side
margin portion and a second side margin portion by attaching a side
surface ceramic sheet on which an adhesive is applied to the
exposed side surfaces of the sides of the first internal electrode
pattern and the second internal electrode pattern. A thickness of
the first and second ceramic green sheets is 0.6 .mu.m or less, and
a thickness of the first and second internal electrode patterns is
0.5 .mu.m or less.
[0092] Hereinafter, the method of manufacturing the multilayer
ceramic capacitor according to another exemplary embodiment in the
present disclosure will be described.
[0093] As shown in FIG. 5A, a plurality of stripe shape first
internal electrode patterns 221 are formed on a ceramic green sheet
211 at predetermined intervals. The plurality of stripe shape first
internal electrode patterns 221 may be formed parallel to each
other.
[0094] The ceramic green sheet 211 may be formed of a ceramic paste
including ceramic powder, an organic solvent, and an organic
binder.
[0095] The ceramic powder may use, but not limited to, a barium
titanate (BaTiO.sub.3)-based material, a lead composite
perovskite-based material, a strontium titanate (SrTiO.sub.3)-based
material, or the like as a material having a high dielectric
constant and may use preferably barium titanate (BaTiO.sub.3)
powder. The ceramic green sheet 211 is sintered, and thus becomes
the dielectric layer 111 constituting the ceramic body 110.
[0096] The stripe shape first internal electrode pattern 221 may be
formed by using an internal electrode paste including a conductive
metal. The conductive metal may include, but not limited to, nickel
(Ni), copper (Cu), palladium (Pd), or an alloy thereof.
[0097] The method of forming the stripe shape first internal
electrode pattern 221 on the ceramic green sheet 211 is not
particularly limited, but may be formed through, for example, a
printing method such as a screen printing method or a gravure
printing method.
[0098] Also, although not shown, a plurality of stripe shape second
internal electrode patterns 222 may be formed on another ceramic
green sheet 211 at predetermined intervals.
[0099] Hereinafter, the ceramic green sheet 211 on which the first
internal electrode pattern 221 is formed may be referred to as a
first ceramic green sheet, and the ceramic green sheet 311 on which
the second internal electrode pattern 222 is formed may be referred
to as a second ceramic green sheet.
[0100] Next, as shown in FIG. 5B, the first and second ceramic
green sheets 211 may be alternately stacked such that the stripe
shape first internal electrode patterns 221 and the stripe shape
second internal electrode patterns 222 are alternately stacked.
[0101] Thereafter, the stripe shape first internal electrode
pattern 221 may become the first internal electrode 121 and the
stripe shape second internal electrode pattern 222 may become the
second internal electrode 122.
[0102] According to another exemplary embodiment in the present
disclosure, a thickness td of the first and second ceramic green
sheets 211 is 0.6 .mu.m or less, and a thickness te of the first
and second internal electrode patterns 221 and 222 is 0.5 .mu.m or
less.
[0103] The present disclosure provides a ultra small and high
capacity multilayer ceramic capacitor in which a thickness of the
dielectric layer 111 is 0.4 .mu.m or less, and a thickness of the
internal electrodes 121 and 122 is 0.4 .mu.m or less, and thus the
thickness td of the first and second ceramic green sheets 211 is
0.6 .mu.m or less, and the thickness te of the first and second
internal electrode patterns 221 and 222 is 0.5 .mu.m or less.
[0104] When the ceramic green sheets 211 and the internal electrode
patterns 221 and 222 having small thicknesses are applied, in the
case where a side margin portion is formed according to the related
art, since high heat and pressure are applied, damage may be
applied to the dielectric layer 111 and the internal electrodes 121
and 122, which may cause a problem that the electrical
characteristic deteriorates.
[0105] However, in another exemplary embodiment in the present
disclosure, as described later, the adhesive is applied onto the
side surface ceramic green sheet other than the ceramic green sheet
stacked body and is transferred to side surfaces of the ceramic
green sheet stacked body, the adhesion between a ceramic body and
the side margin portion may be enhanced only owing to low heat and
pressure.
[0106] Accordingly, there is no occurrence of defective appearance
due to separation of the side margin portion, high insulation
resistance, and moisture resistance reliability may be
improved.
[0107] That is, even when the thickness td of the first and second
ceramic green sheets 211 is 0.6 .mu.m or less and the thickness to
of the first and second internal electrode patterns 221 and 222 is
0.5 .mu.m or less, the electrical characteristic may be excellent
and the reliability may be improved.
[0108] FIG. 5C is a cross-sectional view showing a ceramic green
sheet stacked body 220 in which first and second ceramic green
sheets are stacked according to exemplary embodiment in the present
disclosure. FIG. 5D is a cross-sectional view of the ceramic green
sheet stacked body 220 in which first and second ceramic green
sheets are stacked.
[0109] Referring to FIGS. 5C and 5D, the first ceramic green sheet
211 on which the plurality of parallel stripe shape first internal
electrode patterns 221 are printed and the second ceramic green
sheet 211 on which the plurality of parallel stripe shape second
internal electrode patterns 222 are printed are stacked alternately
with each other.
[0110] More specifically, intervals between a central portion of
the stripe shape first internal electrode patterns 221 printed on
the first ceramic green sheet 211 and the stripe shape second
internal electrode patterns 222 printed on the second ceramic green
sheet 211 may be stacked to be overlapped.
[0111] Next, as shown in FIG. 5D, the ceramic green sheet stacked
body 220 may be cut so as to cross the plurality of stripe shape
first internal electrode patterns 221 and the stripe shape second
internal electrode patterns 222. That is, the ceramic green sheet
stacked body 210 may become the stacked body 210 cut along cutting
lines C1-C1 and C2-C2 that are orthogonal to each other.
[0112] More specifically, the stripe shape first internal electrode
patterns 221 and the stripe shape second internal electrode
patterns 222 may be divided into a plurality of internal electrodes
that are cut in a longitudinal direction and have a constant width.
At this time, the stack ceramic green sheets 211 are also cut
together with the internal electrode patterns 221 and 222.
Accordingly, the dielectric layer 111 may be formed to have the
same width as the width of the internal electrodes 221 and 222.
[0113] Also, the ceramic green sheet stacked body 220 may be cut in
accordance with individual ceramic body sizes along the cutting
line C2-C2. That is, before forming a first side margin portion and
a second side margin portion, the plurality of stack bodies 210 may
be formed by cutting a rod shape stack structure into individual
ceramic body sizes along the cutting line C2-C2.
[0114] That is, the rod shape stack structure may be cut by cutting
lines having the same predetermined interval formed between the
central portion of the overlapped first internal electrode 221 and
the second internal electrode 222. Accordingly, one end of each of
the first internal electrode 221 and the second internal electrode
222 may be alternately exposed to the cut surface.
[0115] Thereafter, the first side margin portion and the second
side margin portion may be formed on first and second side surfaces
of the stacked body 210.
[0116] Next, as shown in FIG. 5E, a first side margin portion 212
and a second side margin portions (not shown) may be formed on the
first and second side surfaces of the stacked body 210,
respectively.
[0117] Specifically, a method of forming the first side margin
portion 212 manufactures a side surface ceramic green sheet 212
having an upper portion to which an adhesive 240 is applied and
disposes the side surface ceramic green sheet 212 to which the
adhesive 240 is applied on a punching elastic member 300 formed of
rubber.
[0118] Next, the stacked body 210 is rotated 90 degrees such that
the first surface of the stacked body 210 faces the side surface
ceramic green sheet 212 to which the adhesive 240 is applied, and
then the stacked body 210 is pressed and adhered to the side
surface ceramic green sheet 212 to which the adhesive 240 is
applied.
[0119] In another exemplary embodiment in the present disclosure,
since the adhesive 240 is applied onto the side surface ceramic
green sheet 212, the side surface ceramic green sheet 212 may be
transferred to the side surfaces of the stacked body 210 at low
temperature and low pressure conditions unlike the related art.
[0120] Thus, damage to the stacked body 210 may be minimized, the
electrical characteristics of the multilayer ceramic capacitor may
be prevented from lowering after sintering, and the reliability may
be improved.
[0121] When the stacked body 210 is pressed and adhered to the side
surface ceramic green sheet 212 to which the adhesive 240 is
applied to transfer the side surface ceramic green sheet 212 to the
stacked body 210, owing to the punching elastic material 300 of a
rubber material, the side surface ceramic green sheet 212 may be
formed up to a side edge portion of the stacked body 210, and the
remaining portion may be cut.
[0122] In FIG. 5F, the side surface ceramic green sheet 212 onto
which the adhesive 240 is applied is formed up to the side edge
portion of the stacked body 210.
[0123] Thereafter, the second side margin portion may be formed on
the second side surface of the stacked body 210 by rotating the
stacked body 210.
[0124] Next, the stacked body 210 having the first and second side
margin portions on both sides of the stacked body 210 may be fired
and sintered to form a ceramic body.
[0125] Thereafter, external electrodes may be respectively formed
on a third side surface of the ceramic body where the first
internal electrode is exposed and on a fourth side surface of the
ceramic body where the second internal electrode is exposed.
[0126] According to another exemplary embodiment in the present
disclosure, the thickness of the side surface ceramic green sheet
is small and has a small deviation, and thus the large size of a
capacity forming portion may be secured.
[0127] Specifically, since the average thickness of the first and
second side margin portions 112 and 113 after sintering is 2 .mu.m
or more and 10 .mu.m or less, and the deviation of the thickness of
each of the first and second side margin portions 112 and 113 is
small, the large size of the capacity forming portion may be
secured.
[0128] As a result, the high capacity multilayer ceramic capacitor
may be implemented.
[0129] The description of the same features as those in the
above-described embodiment of the present disclosure will be
omitted here to avoid redundancy.
[0130] Hereinafter, the present disclosure will be described in
more detail with reference to experimental examples. However, the
present disclosure is not intended to limit the scope of the
present disclosure.
Experimental Example
[0131] According to exemplary embodiment in the present disclosure,
there is provided a comparative example in which a side margin
portion is formed only by using a side surface ceramic green sheet,
and an embodiment in which a side margin portion is formed by using
a side surface ceramic green sheet to which an adhesive is
applied.
[0132] A ceramic green sheet stacked body is formed by attaching
the side surface ceramic green sheets of the comparative example
and the embodiment to electrode exposure portions of a green chip
where an internal electrode is exposed in a width direction and has
no margin such that a side margin portion may be formed.
[0133] A multilayer ceramic capacitor green chip of a 0603 size
(Width.times.Length.times.Height: 0.6 mm.times.0.3 mm.times.0.3 mm)
is manufactured by applying certain temperature and pressure under
a condition of minimizing the deformation of the chip and attaching
the side surface ceramic green sheets to both sides of the ceramic
green sheet stacked body.
[0134] In a step of attaching the side surface ceramic green
sheets, low temperature and pressure are applied unlike the related
art. Specifically, the step is performed at 90.degree. C. or less
and under the pressure condition of 0.5 ton or less.
[0135] The completely manufactured multilayer ceramic capacitor
specimens are subjected to plasticizing processing in a nitrogen
atmosphere at a temperature of 400.degree. C. or less, are sintered
under the conditions of a sintering temperature of 1200.degree. C.
or less and a hydrogen concentration of 0.5% H.sub.2 or less, and
then electrical characteristics such as appearance defects,
insulation resistance and moisture resistance characteristics are
comprehensively verified.
[0136] In the comparative example in which the side margin portion
is formed only by using the side surface ceramic green sheet, since
low temperature and pressure are applied when forming the side
margin portion, the appearance defect occurs that the side margin
portion is separated from the body, which causes problems that
insulation resistance deteriorates and moisture resistance
characteristic deteriorates.
[0137] However, in embodiment in which the side margin portion is
formed by using the side surface ceramic green sheet onto which the
adhesive is applied, the adhesion between the ceramic body and the
side margin portion is excellent even when low temperature and
pressure are applied, no separation defect occurs, insulation
resistance is excellent, and moisture resistance characteristic is
enhanced.
[0138] Meanwhile, when the side margin portion is formed by using
the side surface ceramic green sheet onto which an adhesive is not
applied like a multilayer ceramic capacitor in the related art, a
problem occurs that the side margin portion and the ceramic body
are separated from each other, which may cause problems such as
appearance defects, reduced insulation resistance, and reduced
reliability of moisture resistance.
[0139] In order to prevent the above problems, according to the
related art, the side margin portion is formed by applying high
heat and pressure to enhance the adhesion between the side margin
portion and the ceramic body.
[0140] Specifically, according to the related art, even when the
side margin portion is formed by applying high heat and pressure of
110.degree. C. and 1.0 ton, a problem of separation defect occurs.
In the case of applying low heat and pressure of 90.degree. C. and
0.5 ton as in the embodiment of the present disclosure, problems
such as appearance defect, reduced insulation resistance, and
reduced reliability of moisture resistance frequently occur.
[0141] As set forth above, according to an exemplary embodiment in
the present disclosure, internal electrodes are formed entirely in
a width direction of a dielectric layer and exposed to side
surfaces in a width direction of a ceramic body, and then first and
second side margin portions are separately attached, an adhesive is
applied onto a side surface ceramic sheet, other than the ceramic
body, and the first and second side margin portions are formed on
the side surfaces of the ceramic body, and thus the interfacial
adhesion between the ceramic body and the side margin portions may
be increased, thereby reducing the appearance defect.
[0142] Further, the interfacial adhesion between the ceramic body
and the side margin portions may be increased, and thus the
insulation resistance may be high and the moisture resistance
reliability may be improved.
[0143] While exemplary embodiments have been shown and described
above, it will be apparent to those skilled in the art that
modifications and variations could be made without departing from
the scope in the present disclosure as defined by the appended
claims.
* * * * *