U.S. patent application number 14/804389 was filed with the patent office on 2016-01-28 for ceramic electronic component and manufacturing method therefor.
The applicant listed for this patent is Murata Manufacturing Co., Ltd.. Invention is credited to Mitsunori Inoue, Tomohiko Mori.
Application Number | 20160027569 14/804389 |
Document ID | / |
Family ID | 55167265 |
Filed Date | 2016-01-28 |
United States Patent
Application |
20160027569 |
Kind Code |
A1 |
Inoue; Mitsunori ; et
al. |
January 28, 2016 |
CERAMIC ELECTRONIC COMPONENT AND MANUFACTURING METHOD THEREFOR
Abstract
A ceramic electronic component that includes a ceramic element,
and external electrodes on the surface of the ceramic element.
Voids of the ceramic element and voids at the interfaces between
the ceramic element and the external electrodes are filled with a
resin composition. The resin composition is formed by applying, to
the ceramic electronic component, a resin-containing solution that
has the function of etching the surface of the ceramic element to
ionize constituent elements of the ceramic element. The resin
composition includes a resin, and cationic elements among the
constituent elements of the ceramic elements, which are ionized and
deposited from the ceramic element.
Inventors: |
Inoue; Mitsunori;
(Nagaokakyo-shi, JP) ; Mori; Tomohiko;
(Nagaokakyo-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Murata Manufacturing Co., Ltd. |
Nagaokakyo-shi |
|
JP |
|
|
Family ID: |
55167265 |
Appl. No.: |
14/804389 |
Filed: |
July 21, 2015 |
Current U.S.
Class: |
336/192 ;
216/6 |
Current CPC
Class: |
H01F 17/04 20130101;
H01G 4/12 20130101; H01C 7/102 20130101; H01F 17/0013 20130101;
H01F 41/16 20130101; H01F 41/046 20130101; H01G 4/232 20130101;
H01G 4/30 20130101; H01C 7/008 20130101; H01F 27/292 20130101 |
International
Class: |
H01F 27/245 20060101
H01F027/245; H01F 41/04 20060101 H01F041/04; H01F 41/32 20060101
H01F041/32; H01F 27/29 20060101 H01F027/29 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 28, 2014 |
JP |
2014-153091 |
Claims
1. A ceramic electronic component comprising: a ceramic element;
and an electrode on a surface of the ceramic element, wherein voids
of the ceramic element and at an interface between the ceramic
element and the electrode are at least partially filled with a
resin composition comprising a resin and a cationic element that is
a constituent element of the ceramic element.
2. The ceramic electronic component according to claim 1, wherein
the constituent element of the ceramic element includes at least
one of Ba, Ti, Ca, Zr, Fe, Ni, Cu, Zn, Mn, Co, and Si.
3. The ceramic electronic component according to claim 1, wherein
the resin has a thermal decomposition temperature of 240.degree. C.
or higher.
4. The ceramic electronic component according to claim 1, wherein
the resin comprises at least one of an epoxy resin, a polyimide
resin, a silicone resin, a polyamideimide resin, a
polyetheretherketone resin, and a fluorine-containing resin.
5. The ceramic electronic component according to claim 1, wherein
the resin composition contains cross-linked resin components.
6. The ceramic electronic component according to claim 1, further
comprising a plated film on the electrode.
7. A method for manufacturing a ceramic electronic component, the
method comprising: providing, to a surface of a ceramic element, a
resin-containing solution that etches the surface of the ceramic
element so as to ionize constituent elements of the ceramic element
to form a resin composition comprising a resin and a cationic
element that is a constituent element of the ceramic element, the
resin composition at least partially filling voids of the ceramic
element and at an interface between the ceramic element and an
electrode.
8. The method for manufacturing a ceramic electronic component
according to claim 7, wherein a pH of the resin-containing solution
containing the at least one anion is greater than 5 and less than
11.
9. The method for manufacturing a ceramic electronic component
according to claim 7, wherein the method further comprises washing
the ceramic electronic component after applying the
resin-containing solution to the surface of the ceramic
element.
10. The method for manufacturing a ceramic electronic component
according to claim 7, wherein the resin composition is formed after
forming the electrode on the ceramic element.
11. The method for manufacturing a ceramic electronic component
according to claim 7, wherein the electrode is formed on the
ceramic element after forming the resin composition.
12. The method for manufacturing a ceramic electronic component
according to claim 7, wherein the resin composition is formed after
forming the electrode and plating a surface of the electrode.
13. The method for manufacturing a ceramic electronic component
according to claim 7, wherein the resin comprises at least one of
an epoxy resin, a polyimide resin, a silicone resin, a
polyamideimide resin, a polyetheretherketone resin, and a
fluorine-containing resin.
14. The method for manufacturing a ceramic electronic component
according to claim 7, wherein the method further comprises heating
the resin composition so as to cross-link resin components
thereof.
15. The method for manufacturing a ceramic electronic component
according to claim 7, wherein the constituent element of the
ceramic element includes at least one of Ba, Ti, Ca, Zr, Fe, Ni,
Cu, Zn, Mn, Co, and Si.
16. The method for manufacturing a ceramic electronic component
according to claim 7, wherein the resin has a thermal decomposition
temperature of 240.degree. C. or higher.
17. The method for manufacturing a ceramic electronic component
according to claim 7, further comprising forming a plated film on a
surface of the electrode.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a ceramic electronic
component and a method for manufacturing the component, and more
particularly, to a ceramic electronic component such as, for
example, a laminated coil, a multilayer ceramic capacitor, a
thermistor, a varistor, and a multilayer substrate, which includes
a ceramic element and an electrode provided on the ceramic element
surface, and a method for manufacturing the component.
[0003] 2. Description of the Related Art
[0004] Ceramic electronic components may have cracks (voids)
generated in ceramic elements. In addition, gaps (voids) are likely
to be generated at the joint interfaces between the ceramic
elements and heterogeneous materials such as electrodes provided on
the surfaces of the ceramic elements. Characteristic degradation
(insulation degradation) may be caused by ingress of impurities
such as moisture into the ceramic electronic components through the
voids of the ceramic elements or the voids at the interfaces
between the ceramic elements and the electrodes.
[0005] Therefore, as measures against this situation, techniques
have been proposed for coating ceramic element surfaces of ceramic
electronic components with resin, as described in JP 2004-500719
A.
[0006] Coating the ceramic element surfaces of the ceramic
electronic components can reduce the influence of chemical erosion
on the ceramic elements, which is caused by plating solution in the
case of plating or flux in the case of mounting. Further, coating
the ceramic element surfaces can, in the case of plating, suppress
the growth by plating onto the ceramic element surfaces, and reduce
defective conductivity of the electronic component.
[0007] Furthermore, coating the ceramic element surfaces can
prevent ingress of moisture, plating solutions, flux, etc. into the
electronic components, and prevent reliability degradation of the
electronic components, or electrical property degradation due to
deposition by plating onto internal electrodes.
SUMMARY OF THE INVENTION
[0008] However, as in JP2004-500719 A, in the case of coating the
ceramic element surface of the ceramic electronic component with
the resin, the adhesion of the resin on the surface of the ceramic
electronic component, excluding voids of the ceramic element,
increases the size of the ceramic electronic component. Thus, the
ceramic electronic component undergoes a decrease in characteristic
per volume.
[0009] Further, in the case of the resin coating according to the
prior art in Japanese Patent Application Laid-Open No. 2004-500719,
it is not possible to peel the resin (film) by barrel polishing
because of the firm adhesion of the resin to the ceramic element.
Moreover, while the prior art in JP2004-500719 A involves a step of
removing the resin, it is difficult to selectively remove the resin
which adheres to the ceramic element surface while leaving only the
resin which adheres to voids of the ceramic element and at the
interfaces between the ceramic element and electrodes.
[0010] Therefore, an object of the present invention is to provide
a ceramic electronic component and a method for manufacturing the
component, which can prevent characteristic degradation due to
inward ingress of impurities such as moisture, and suppress the
decrease in characteristic per volume.
[0011] The present invention provides a ceramic electronic
component including a ceramic element and an electrode provided on
the ceramic element surface. Voids of the ceramic element and at
the interface between the ceramic element and the electrode are at
least partially filled with a resin composition including a resin
and a cationic element among constituent elements of the ceramic
element.
[0012] Among the constituent elements of the ceramic element, the
cationic element eluted and deposited from the ceramic element is
contained in the resin composition. Furthermore, the constituent
elements of the ceramic element include at least one of Ba, Ti, Ca,
Zr, Fe, Ni, Cu, Zn, Mn, Co, and Si. In addition, a plated film may
be formed on the electrode provided on the ceramic element
surface.
[0013] In the ceramic electronic component according to the present
invention, the resin preferably has a thermal decomposition
temperature of 240.degree. C. or higher. Furthermore, the resin
preferably includes at least one of an epoxy resin, a polyimide
resin, a silicone resin, a polyamideimide resin, a
polyetheretherketone resin, and a fluorine-containing resin. Thus,
the ceramic electronic component has heat resistance improved.
[0014] In addition, in the ceramic electronic component according
to the present invention, the resin composition preferably contains
resin components cross-linked by heating. Thus, the resin
composition can be formed in a short period of time.
[0015] Furthermore, the present invention provides a method for
manufacturing a ceramic electronic component including a ceramic
element, an electrode provided on the ceramic element surface, and
a resin composition that at least partially fills voids of the
ceramic element and at the interface between the ceramic element
and the electrode.
[0016] The method comprises the steps of providing, to the ceramic
element surface, a resin-containing solution that has the function
of etching the ceramic element surface to ionize constituent
elements of the ceramic element to form a resin composition
including a resin and a cationic element among the constituent
elements of the ceramic element, which are ionized and deposited
from the ceramic element, at least partially in the voids of the
ceramic element and at the interface between the ceramic element
and the electrode.
[0017] Methods for providing the resin-containing solution to the
ceramic element surface include methods such as immersion and
application, and preferably with the ceramic element in the
resin-containing solution, the resin-containing solution and the
ceramic element are subjected to agitation, or the voids are
subjected to vacuum/pressure impregnation with the resin-containing
solution. In addition, the resin means a resin that is adjusted to
have a polar group such as a carboxyl group and an amino group, and
able to be, as an organic substance or a composite of organic and
inorganic substances, dissolved or dispersed in an aqueous
solvent.
[0018] The resin-containing solution according to the present
invention has a resin dispersed in an aqueous solvent, and has a
component that etches (dissolves) the ceramic, and a component that
reacts the dissolved ceramic ions with the resin component.
[0019] In the present invention, the resin-containing solution
etches (dissolves) the ceramic element surface to ionize the
constituent elements of the ceramic element. Then, the resin
component dissolved (dispersed) in the resin-containing solution
reacts with cationic elements among the ionized constituent
elements of the ceramic element to neutralize the charge of the
resin component. As a result, the resin component settles out along
with cationic elements among the constituent elements of the
ceramic element.
[0020] Specifically, the anionic resin component stably dispersed
in the aqueous solvent reacts with the cationic elements among the
constituent elements of the ceramic element to settle out through
destabilization at the ceramic element surface.
[0021] The reaction between the ionized constituent elements of the
ceramic element and the resin-containing solution is likely to be
developed at the ceramic element surface, and the reactants are
thus believed to be immobilized to the ceramic element surface. In
contrast, at the electrode formed on the ceramic element surface,
because there is almost no etching reaction developed, fewer
ionized constituent elements of the ceramic element will not
develop any reaction with the resin-containing solution. Therefore,
the resin composition is selectively deposited only on the ceramic
element surface.
[0022] The resin composition formed according to the present
invention passes through a gel state of emulsions aggregated as a
precursor. Therefore, at this stage in the gel state, the reactant
deposited on a part of the ceramic element surface, excluding the
voids of the ceramic element and at the interfaces between the
ceramic element and the electrode, can be easily removed by, for
example, barrel polishing. Accordingly, the resin composition can
be formed partially in the voids of the ceramic element and at the
interface between ceramic element and the electrode in the present
invention.
[0023] According to the present invention, the resin composition is
formed at least partially in the voids of the ceramic element and
at the interfaces between the ceramic element and the electrode.
Therefore, the ceramic electronic component can be obtained which
can prevent characteristic degradation due to inward ingress of
impurities such as moisture. In addition, the invention can be also
adapted to the ceramic electronic component which has voids or
electrodes in complex shapes, because the resin composition is
formed by chemical action.
[0024] Moreover, the ceramic electronic component undergoes almost
no increase in size because the resin composition is formed
partially in the voids of the ceramic element and at the interface
between the ceramic element and the electrode in the ceramic
electronic component according to the present invention. Therefore,
the ceramic electronic component can be obtained which can suppress
the decrease in characteristic per volume.
[0025] The foregoing object, and other objects, features, and
advantages of the invention will become more evident from the
following description of embodiments, which will be provided with
reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a cross-sectional view illustrating an embodiment
of a ceramic electronic component according to the present
invention;
[0027] FIG. 2 is a flowchart showing an embodiment of a method for
manufacturing the ceramic electronic component according to the
present invention;
[0028] FIG. 3 is an enlarged cross-sectional view of an external
electrode;
[0029] FIG. 4 is an enlarged cross-sectional view of an external
electrode of another ceramic electronic component;
[0030] FIG. 5 is an enlarged cross-sectional view of yet another
external electrode of another ceramic electronic component; and
[0031] FIG. 6 is a cross-sectional view illustrating another
embodiment of a ceramic electronic component according to the
present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0032] Embodiments of a ceramic electronic component and a
manufacturing method therefor according to the present invention
will be described.
[0033] A ceramic electronic component according to the present
invention will be described with reference to a laminated coil as
an example.
[0034] FIG. 1 is a cross-sectional view illustrating a laminated
coil 10 that is a ceramic electronic component according to the
present invention.
[0035] The laminated coil 10 includes a substantially cuboid
ceramic element 1, and external electrodes 6a and 6b formed on
right and left ends of the ceramic element 1.
[0036] The ceramic element 1 is a laminated body obtained by
stacking a number of ceramic layers 2 and a number of internal
electrodes 4a, 4b, and 4c in the thickness direction.
[0037] The ceramic layers 2 are composed of a magnetic ceramic
material such as a Cu--Zn ferrite and a Ni--Zn ferrite.
[0038] The internal electrode 4a, for example, formed to have the
shape of J in planar view, has an end extended to the left end
surface of the ceramic element 1, and electrically connected to the
external electrode 6a. The internal electrode 4b, for example,
formed to have the shape of J in planar view, has an end extended
to the right end surface of the ceramic element 1, and electrically
connected to the external electrode 6b. The multiple internal
electrodes 4c are formed to have, for example, the shape of C in
planar view between the respective ceramic layers 2 between the
internal electrodes 4a and 4b. In addition, the internal electrode
4a, the multiple internal electrodes 4c, and the internal electrode
4b are connected in the form of a coil and in series, with
respective through-hole electrodes that penetrate through the
respective ceramic layers 2. Thus, a coil function is achieved
between the external electrodes 6a and 6b. The internal electrodes
4a, 4b, and 4c and the through-hole electrodes are composed of Ag,
Cu, Ni, Pd, or an alloy of the metals, etc.
[0039] The external electrodes 6a and 6b respectively have, on the
surfaces thereof, plated films 7a and 7b formed. The plated films
7a and 7b protect the external electrodes 6a and 6b, and make
solderability of the external electrodes 6a and 6b favorable.
[0040] This laminated coil 10, for example, has voids 1a at the
surface of the ceramic element 1, and has voids 3a and 3b at the
interfaces between the ceramic element 1 and the external
electrodes 6a and 6b. Therefore, the voids 1a of the ceramic
element 1 and the voids 3a and 3b at the interfaces between the
ceramic element 1 and the external electrodes 6a and 6b are each
filled with a resin composition 8. The resin composition 8 includes
a resin, and cationic elements among the constituent elements of
the ceramic element 1.
[0041] The cationic elements among the constituent elements of the
ceramic element 1, which are contained in the resin composition 8,
are deposited by partial elution from the ceramic layers 2 of the
ceramic element 1. More specifically, among the constituent
elements of the ceramic element 1, the cationic elements include
Sr, Sn, Fe, Ni, Cu, Zn, Mn, and Co each eluted and deposited from
the Cu--Zn ferrite, Ni--Zn ferrite, or the like of the ceramic
layers 2.
[0042] The resin included in the resin composition 8 is a
polyvinylidene chloride resin, an acrylic resin, an epoxy resin, a
polyimide resin, a silicone resin, a polyamideimide resin, a
polyetheretherketone resin, a fluorine-containing resin, or the
like. The laminated coil 10 typically undergoes a mounting step
with soldering, and the resin composition 8 thus preferably has
high heat resistance (240.degree. C. or higher). Accordingly, a
resin is preferred which has a thermal decomposition temperature of
240.degree. C. or higher. In this regard, there is a relationship
of: (polyvinylidene chloride resin, acrylic resin)<epoxy
resin<(polyimide resin, polyamideimide resin,
polyetheretherketone resin, silicone resin, fluorine-containing
resin) in terms of heat resistance.
[0043] In the thus configured laminated coil 10, the resin
composition 8 includes the resin and the cationic elements among
the constituent elements of the ceramic element 1, and the resin
composition 8 is formed in the voids 1a of the ceramic element 1 of
the laminated coil 10, and the voids 3a and 3b at the interfaces
between the ceramic element 1 and the external electrodes 6a and
6b. Therefore, characteristic degradation due to ingress of
impurities such as moisture into the laminated coil 10 can be
prevented. In this way, the laminated coil 10 can be obtained which
can make an improvement in reliability. In addition, the invention
can be also adapted to the laminated coil 10 which has voids or
electrodes in complex shapes, because the resin composition 8 is
formed by chemical action.
[0044] Furthermore, in this laminated coil 10, the resin
composition 8 is formed partially in the voids 1a of the ceramic
element 1, and the voids 3a and 3b at the interfaces between the
ceramic element 1 and the external electrodes 6a and 6b, and the
laminated coil 10 thus undergoes almost no increase in size.
Therefore, the laminated coil 10 can be obtained which can suppress
the decrease in characteristic per volume.
[0045] Next, a method for manufacturing the ceramic electronic
component according to the present invention will be described with
reference to the laminated coil 10 as an example. FIG. 2 is a
flowchart showing a method for manufacturing the laminated coil
10.
[0046] In a step S1, an organic binder, a dispersant, a
plasticizer, etc. are added to a magnetic ceramic material such as
Cu--Zn ferrite or Ni--Zn ferrite, thereby preparing slurry for
sheet forming.
[0047] Next, in a step S2, the slurry for sheet forming is formed
into sheets by a doctor blade method to provide rectangular ceramic
green sheets.
[0048] Next, in a step S3, a through-hole electrode paste
containing Ag is applied by a well-known method to form electrode
paste columns which should serve as through-hole electrodes, so as
to penetrate through the ceramic green sheets in the thickness
direction, and an internal electrode paste containing Ag is then
applied by a screen printing method onto the ceramic green sheets
to form electrode paste films which should serve as the internal
electrodes 4a, 4b, and 4c.
[0049] Next, in a step S4, the multiple ceramic green sheets with
the electrode paste films and electrode paste columns formed are
stacked so as to locate the electrode paste films and the electrode
paste columns in predetermined positions, and subjected to pressure
bonding. This laminated ceramic green sheet is cut into a size for
individual ceramic elements 1 to provide a number of unfired
ceramic elements 1.
[0050] Next, in a step S5, the unfired ceramic elements 1 are
subjected to binder removal treatment at 400.degree. C. to
500.degree. C. Thereafter, the unfired ceramic elements 1 are
subjected to firing for 2 hours at a temperature of 900.degree. C.
to 1000.degree. C. to provide sintered ceramic elements 1. The
ceramic green sheets, the electrode paste films, and the electrode
paste columns are subjected to co-firing, and the ceramic green
sheets serve as the ceramic layers 2, the electrode paste films
serve as the internal electrodes 4a, 4b, and 4c, and the electrode
paste columns serves as through-hole electrodes.
[0051] Further, in the subsequent step, there are three types of
manufacturing methods [Method 1] to [Method 3] shown.
[0052] (a) In the Case of [Method 1]
[0053] In the case of the manufacturing method [Method 1], in a
step S6, an external electrode paste (AgPd alloy paste) is applied
to both ends of the sintered ceramic element 1. Thereafter, on the
sintered ceramic elements 1, the external electrode paste is baked
at a temperature of 900.degree. C. to form the external electrodes
6a and 6b electrically connected respectively to the internal
electrodes 4a and 4b.
[0054] Next, in a step S7, to the ceramic elements 1, a
resin-containing solution is provided by an immersion method, or
applied by spin coating. In order to make the resin-containing
solution more likely to enter the voids 1a of the ceramic elements
1 and the voids 3a and 3b at the interfaces between the ceramic
elements 1 and the external electrodes 6a and 6b, it is preferable
to agitate the resin-containing solution and the ceramic elements
1, or vacuum/pressure-impregnate the voids 1a, 3a, and 3b with the
resin-containing solution, with the ceramic element 1 in the
resin-containing solution.
[0055] The resin-containing solution has the function of etching
the surfaces of the ceramic elements 1 to ionize the constituent
elements of the ceramic elements 1, and includes a resin component
dissolved or dispersed in an aqueous solvent. Furthermore, the
resin-containing solution includes a neutralizer for dissolution or
dispersion of the resin component, and if necessary, a surfactant
for reaction with cationic elements among the dissolved constituent
elements of the ceramic elements.
[0056] Therefore, the resin-containing solution etches (dissolves)
the surfaces of the ceramic elements 1 to ionize the constituent
elements of the ceramic elements 1. In regard to the etching
(dissolving) function of the resin-containing solution, the etching
(dissolving) reaction can be developed just with the constituents
of the resin-containing solution without adding any etching
promoting constituent, because the highly ionic metal element is
contained in the case of the laminated coil 10. More specifically,
the etching (dissolving) reaction proceeds when the pH of the
resin-containing solution is set in a pH range (pH<5, pH>11)
in which the highly ionic metal element is present stably as
ions.
[0057] Then, the resin component dissolved (dispersed) in the
resin-containing solution reacts with cationic elements among the
ionized constituent elements of the ceramic elements 1 to
neutralize the charge of the resin component. As a result, the
resin component settles out along with cationic elements among the
constituent elements of the ceramic elements 1, and deposits on the
ceramic element surfaces. Accordingly, in the deposited resin
component, cationic elements are incorporated among the dissolved
and ionized constituent elements of the ceramic elements 1.
[0058] The resin composition 8 formed passes through a gel state of
emulsions aggregated as a precursor. Therefore, at this stage in
the gel state, the reactant deposited on a part of the ceramic
element surface, excluding the voids 1a of the ceramic element 1
and the voids 3a and 3b at the interfaces between the ceramic
element 1 and the external electrodes 6a and 6b, can be easily
removed by, for example, barrel polishing. Accordingly, the resin
composition 8 can be formed partially in the voids 1a of the
ceramic element 1, and the voids 3a and 3b at the interfaces
between the ceramic element 1 and the external electrodes 6a and
6b. Further, thereafter, the ceramic elements 1 may be washed with
a polar solvent such as pure water, if necessary.
[0059] The resin included in the resin-containing solution is a
polyvinylidene chloride resin, an acrylic resin, an epoxy resin, a
polyimide resin, a silicone resin, a polyamideimide resin, a
polyetheretherketone resin, a fluorine-containing resin, or the
like, but basically, it does not matter what kind as long as the
resin is deposited by the present treatment.
[0060] In this way, the resin composition 8 including the cationic
elements among the constituent elements of the ceramic elements 1,
which are ionized and deposited from the ceramic elements 1, and
the resin is formed in the voids 1a of the ceramic elements 1 and
the voids 3a and 3b at the interfaces between the ceramic elements
1 and the external electrodes 6a and 6b. Thereafter, the resin
composition 8 is subjected to heating treatment. The heating
treatment is intended to accelerate a cross-linking reaction
between the resin components in the resin-containing solution
deposited, and the heating condition varies depending on the type
of the resin component. In general, the cross-linking reaction is
likely to proceed under high temperature. However, the excessively
increased temperature increases the decomposition reaction of the
resin component. Accordingly, there is a need to set optimum
temperature and time in accordance with the resin component.
[0061] Next, in a step S8, the plated films 7a and 7b are formed on
the external electrodes 6a and 6b by an electrolytic or electroless
plating method. The plated films 7a and 7b adopt, for example, a
double structure composed of a Ni plated film as a lower layer and
an Sn plated film as an upper layer. FIG. 3 is an enlarged
cross-sectional view of a site with the external electrode 6b
formed by the manufacturing method [Method 1].
[0062] (b) In the Case of [Method 2]
[0063] In the case of the manufacturing method [Method 2], in a
step S9, to the ceramic elements 1, a resin-containing solution is
provided by an immersion method, or applied by spin coating, or
preferably provided or applied by carrying out agitation or
vacuum/pressure impregnation. The resin-containing solution etches
(dissolves) the surfaces of the ceramic elements 1 to ionize the
constituent elements of the ceramic elements 1. Then, the resin
component dissolved (dispersed) in the resin-containing solution
reacts with cationic elements among the ionized constituent
elements of the ceramic elements 1 to neutralize the charge of the
resin component. As a result, the resin component settles out along
with cationic elements among the constituent elements of the
ceramic elements 1, and deposits over substantially the entire
surfaces of the ceramic elements 1. Accordingly, in the deposited
resin component, cationic elements are incorporated among the
dissolved and ionized constituent elements of the ceramic elements
1. It is to be noted that after providing the resin-containing
solution, the ceramic elements 1 may be washed with a polar solvent
such as pure water, if necessary.
[0064] In this way, the resin composition 8 including the cationic
elements among the constituent elements of the ceramic elements 1,
which are ionized and deposited from the ceramic elements 1, and
the resin is formed in the voids 1a of the ceramic elements 1.
Thereafter, the resin composition 8 is subjected to heating
treatment.
[0065] Next, in a step S10, an external electrode paste is applied
to both ends of the ceramic elements 1.
[0066] Thereafter, on the ceramic elements 1, the external
electrodes 6a and 6b electrically connected respectively to the
internal electrodes 4a and 4b are formed at a temperature at which
the resin composition 8 undergoes no thermal decomposition.
[0067] Next, in a step S11, the plated films 7a and 7b are formed
on the external electrodes 6a and 6b by an electrolytic or
electroless plating method. FIG. 4 is an enlarged cross-sectional
view of a site with the external electrode 6b formed by the
manufacturing method [Method 2].
[0068] (c) In the case of [Method 3]
[0069] In the case of the manufacturing method [Method 3], in a
step S12, an external electrode paste is applied to both ends of
the ceramic elements 1. Thereafter, on the ceramic elements 1, the
external electrode paste is baked at a temperature of 900.degree.
C. to form the external electrodes 6a and 6b electrically connected
respectively to the internal electrodes 4a and 4b.
[0070] Next, in a step S13, the plated films 7a and 7b are formed
on the external electrodes 6a and 6b by an electrolytic or
electroless plating method.
[0071] Next, in a step S14, to the ceramic elements 1, a
resin-containing solution is provided by an immersion method, or
applied by spin coating, or preferably provided or applied by
carrying out agitation or vacuum/pressure impregnation. The
resin-containing solution etches (dissolves) the surfaces of the
ceramic elements 1 to ionize the constituent elements of the
ceramic elements 1. Then, the resin component dissolved (dispersed)
in the resin-containing solution reacts with cationic elements
among the ionized constituent elements of the ceramic elements 1 to
neutralize the charge of the resin component. As a result, the
resin component settles out along with cationic elements among the
constituent elements of the ceramic elements 1, and deposits on the
ceramic element surfaces. Accordingly, in the deposited resin
component, cationic elements are incorporated among the dissolved
and ionized constituent elements of the ceramic elements 1. It is
to be noted that after providing the resin-containing solution, the
ceramic elements 1 may be washed with a polar solvent such as pure
water, if necessary.
[0072] In this way, the resin composition 8 including the cationic
elements among the constituent elements of the ceramic elements 1,
which are ionized and deposited from the ceramic elements 1, and
the resin is formed in the voids 1a of the ceramic elements 1 and
the voids 3a and 3b at the interfaces between the ceramic elements
1 and the external electrodes 6a and 6b. Thereafter, the resin
composition 8 is subjected to heating treatment. FIG. 5 is an
enlarged cross-sectional view of a site with the external electrode
6b formed by the manufacturing method [Method 3].
[0073] Next, a ceramic electronic component according to the
present invention will be described with reference to a multilayer
ceramic capacitor as an example other than laminated coils.
[0074] FIG. 6 is a cross-sectional view illustrating a multilayer
ceramic capacitor 30 that is a ceramic electronic component
according to the present invention. The multilayer ceramic
capacitor 30 includes a substantially cuboid ceramic element 21,
and external electrodes 26a and 26b formed on right and left ends
of the ceramic element 21.
[0075] The ceramic element 21 is a laminated body obtained by
stacking, in the thickness direction, a number of ceramic layers 22
and multiple pairs of internal electrodes 24a and 24b opposed to
each other with the ceramic layers 22 interposed therebetween.
[0076] The ceramic layers 22 are composed of a ceramic material of
Pb(Mg,Nb)O.sub.3--PbTiO.sub.3--Pb(Cu,W)--ZnO--MnO.sub.2 as a main
constituent mixed with Li.sub.2O--BaO--B.sub.2O.sub.3--SiO.sub.2 as
an anti-reducing agent, or a ceramic material containing
CaZrO.sub.3--CaTiO.sub.3 as its main constituent.
[0077] The internal electrodes 24a, for example, formed to have a
substantially rectangular shape in planar view, have ends extended
to the left end surface of the ceramic element 21, and electrically
connected to the external electrode 26a. The internal electrodes
24b, for example, formed to have a substantially rectangular shape
in planar view, have ends extended to the right end surface of the
ceramic element 21, and electrically connected to the external
electrode 26b. Thus, a capacitor function is achieved at sites with
the internal electrodes 24a and 24b opposed. The internal
electrodes 24a and 24b are composed of Ag, Cu, Ni, Pd, or an alloy
of the metals, etc.
[0078] The external electrodes 26a and 26b respectively have, on
the surfaces thereof, plated films 27a and 27b formed. The plated
films 27a and 27b protect the external electrodes 26a and 26b, and
make solderability of the external electrodes 26a and 26b
favorable.
[0079] This multilayer ceramic capacitor 30, for example, has voids
21a at the surface of the ceramic element 21, and has voids 23a and
23b at the interfaces between the ceramic element 21 and the
external electrodes 26a and 26b. Therefore, the voids 21a of the
ceramic element 21 and the voids 23a and 23b at the interfaces
between the ceramic element 21 and the external electrodes 26a and
26b are each filled with a resin composition 28, as in the case of
the laminated coil 10. The resin composition 28 includes a resin,
and cationic elements among the constituent elements of the ceramic
element 21.
[0080] The cationic elements among the constituent elements of the
ceramic element 21, which are contained in the resin composition
28, are deposited by partial elution from the ceramic layers 22 of
the ceramic element 21. More specifically, among the constituent
elements of the ceramic element 21, the cationic elements include
Pb, Mg, Nb, Ti, Ba, Li, Zn, Mn, Si, Ca, and Zr each eluted and
deposited from
Pb(Mg,Nb)O.sub.3--PbTiO.sub.3--Pb(Cu,W)--ZnO--MnO.sub.2,
Li.sub.2O--BaO--B.sub.2O.sub.3--SiO.sub.2,
CaZrO.sub.3--CaTiO.sub.3, or the like of the ceramic layers.
EXAMPLES
1. Examples and Comparative Examples
[0081] Respective ceramic electronic components (laminated coils,
multilayer ceramic capacitors) according to examples and
comparative examples were prepared, and subjected to
characterization.
2. Preparation of Examples and Comparative Examples
(a) Examples 1 to 3
[0082] As shown in Table 1, the laminated coil 10 (see FIG. 1)
where the voids 1a of the ceramic element 1 and the voids 3a and 3b
at the interfaces between the ceramic element 1 and the external
electrodes 6a and 6b were filled with the resin composition 8 was
prepared by the manufacturing method [Method 1] according to the
embodiment described previously.
[0083] As the resin-containing solution, a commercially available
latex of a resin component dispersed in an aqueous solvent was used
with an etching promoting constituent and a surfactant added
thereto.
[0084] As the resin-containing solution according to Example 1, an
acrylic resin (Trade Name: Nipol LX814A (from Zeon Corporation)) as
the resin component was used through the adjustment of the pH to
3.0 with the addition of a sulfuric acid as the etching promoting
constituent to the resin. To this resin, 1 vol % of NEWREX
(registered trademark, from NOF Corporation) was added as a
surfactant. The resin-containing solution was adjusted so as to
have a solid content concentration of 10 wt %.
[0085] As the resin-containing solution according to Example 2, a
silicone resin (Trade Name: POLON-MF-56 (from Shin-Etsu Chemical
Co., Ltd.)) as the resin component was used through the adjustment
of the pH to 3.0 with the addition of a sulfuric acid as the
etching promoting constituent to the resin. To this resin, 1 vol %
of NEWREX (registered trademark, from NOF Corporation) was added as
a surfactant. The resin-containing solution was adjusted so as to
have a solid content concentration of 10 wt %.
[0086] As the resin-containing solution according to Example 3, an
epoxy resin (Trade Name: MODEPICS 302 (from Arakawa Chemical
Industries, Ltd.)) as the resin component was used through the
adjustment of the pH to 3.0 with the addition of a sulfuric acid as
the etching promoting constituent to the resin. To this resin, 1
vol % of NEWREX (registered trademark, from NOF Corporation) was
added as a surfactant. The resin-containing solution was adjusted
so as to have a solid content concentration of 10 wt %.
(b) Example 4
[0087] As shown in Table 2, the multilayer ceramic capacitor 30
(see FIG. 6) where the voids 21a of the ceramic element 21 and the
voids 23a and 23b at the interfaces between the ceramic element 21
and the external electrodes 26a and 26b were filled with the resin
composition 28 was prepared by the manufacturing method [Method 1]
according to the embodiment described previously.
[0088] As the resin-containing solution according to Example 4, an
acrylic resin (Trade Name: Nipol LX814A (from Zeon Corporation)) as
the resin component was used through the adjustment of the pH to
3.0 with the addition of a sulfuric acid as the etching promoting
constituent to the resin. To this resin, 1 vol % of NEWREX
(registered trademark, from NOF Corporation) was added as a
surfactant. The resin-containing solution was adjusted so as to
have a solid content concentration of 10 wt %.
(c) Comparative Examples 1 and 2
[0089] As shown in Tables 1 and 2, a laminated coil (Comparative
Example 1) and a multilayer ceramic capacitor (Comparative Example
2) were prepared which were not subjected to the treatment of
forming resin composition as shown in FIG. 2.
3. Characterization and Evaluation Methods in Examples and
Comparative Examples
[0090] The prepared laminated coils according to Examples 1 to 3
and Comparative Example 1 and multilayer ceramic capacitors
according to Example 4 and Comparative Example 2 were subjected to
the evaluation of characteristic changes by the following constant
temperature and humidity test.
[0091] (a) Change in Impedance by Constant Temperature and Humidity
Test
[0092] For each of the laminated coils according to Examples 1 to 3
and Comparative Example 1, twenty samples were examined for the
change in impedance by the constant temperature and humidity test
at a rated current of 2 A for 100 hours at a temperature of
85.degree. C. and a humidity of 85%. In this case, in particular,
the rate of impedance change after the constant temperature and
humidity test was examined with impedance before the constant
temperature and humidity test as a reference. In addition, the
average value for the twenty samples was regarded as the rate of
impedance change.
[0093] (b) Change in Insulation Resistance by Constant Temperature
and Humidity Test
[0094] For each of the multilayer ceramic capacitor according to
Example 4 and Comparative Example 2, the insulation resistance was
measured after leaving twenty samples for 2000 hours in a constant
temperature and humidity bath set at a temperature of 85.degree. C.
and a humidity of 85%. Then, the samples with the insulation
resistance of 10.sup.7.OMEGA. (10 M.OMEGA.) or less were determined
as NG (defectives) to check the incidence of defective insulation
resistance. It is to be noted that the multilayer ceramic
capacitors were not regarded as defectives before the constant
temperature and humidity test, with the insulation resistance in
excess of 10.sup.7.OMEGA. (10 M.OMEGA.).
4. Characterization Result in Examples and Comparative Examples
[0095] Table 1 shows the results of the characterization of
Examples 1 to 3 and Comparative Example 1.
[0096] Table 2 shows the results of the characterization of Example
4 and Comparative Example 2.
TABLE-US-00001 TABLE 1 Rate of Electronic Resin Impedance Component
Composition Resin-Containing Solution pH Change Example 1 Laminated
Coil Yes Acrylic Resin + Sulfuric Acid + Surfactant 3.0 0% 2
Silicone Resin + Sulfuric Acid + Surfactant 3.0 0% 3 Epoxy Resin +
Sulfuric Acid + Surfactant 3.0 0% Comparative 1 Laminated Coil No
-- -- -50% Example
TABLE-US-00002 TABLE 2 Incidence of Defective Electronic Resin
Insulation Component Composition Resin-Containing Solution pH
Resistance Example 4 Multilayer Yes Acrylic Resin + Sulfuric Acid +
Surfactant 3.0 0% Ceramic Capacitor Comparative 2 Multilayer No --
10% Example Ceramic Capacitor
[0097] From the results in Table 1, the change in impedance was
-50% due to generation of migration in the untreated product
(Comparative Example 1), but 0% in the compositions according to
the present examples (Examples 1 to 3).
[0098] Furthermore, from the results in Table 2, the incidence of
defective insulation resistance was 10% in the case of the
untreated product (Comparative Example 2), but 0% in the
composition according to the present example (Example 4).
[0099] It is to be noted that the invention is not to be considered
limited to the previously described embodiments, but can be
modified variously within the scope of the invention.
[0100] The ceramic electronic component according to the invention
is used in a preferred manner, in particular, as parts of portable
devices such as portable communication devices, for example, which
require a reduction in size or a reduction in weight.
* * * * *