U.S. patent application number 16/744569 was filed with the patent office on 2020-05-14 for electronic component.
This patent application is currently assigned to TDK CORPORATION. The applicant listed for this patent is TDK CORPORATION. Invention is credited to Hisashi AIBA, Hiroya NAKAMURA, Kazuto TAKEYA, Kouki YAMADA, Naoyoshi YOSHIDA.
Application Number | 20200154571 16/744569 |
Document ID | / |
Family ID | 65808281 |
Filed Date | 2020-05-14 |
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United States Patent
Application |
20200154571 |
Kind Code |
A1 |
YOSHIDA; Naoyoshi ; et
al. |
May 14, 2020 |
ELECTRONIC COMPONENT
Abstract
An electronic component includes an element body, a thin film
layer disposed to cover a pair of end surfaces and four side
surfaces, a first external electrode and a second external
electrode, and internal conductors, wherein each of the first
external electrode and the second external electrode has first
electrode layers disposed on the thin film layer and electrically
connected to the internal conductors, and second electrode layers
disposed to cover the first electrode layers, and a thermal
conductivity of the second electrode layers is lower than a thermal
conductivity of the first electrode layers.
Inventors: |
YOSHIDA; Naoyoshi; (Tokyo,
JP) ; YAMADA; Kouki; (Tokyo, JP) ; AIBA;
Hisashi; (Tokyo, JP) ; TAKEYA; Kazuto; (Tokyo,
JP) ; NAKAMURA; Hiroya; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TDK CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
TDK CORPORATION
Tokyo
JP
|
Family ID: |
65808281 |
Appl. No.: |
16/744569 |
Filed: |
January 16, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16134733 |
Sep 18, 2018 |
10575404 |
|
|
16744569 |
|
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 1/181 20130101;
H01C 7/041 20130101; H05K 1/0201 20130101; H01G 4/232 20130101;
H01C 7/008 20130101; H01C 7/18 20130101; H01G 4/30 20130101; H01G
4/005 20130101; H01G 4/12 20130101; H01G 2/06 20130101; H01C 1/148
20130101 |
International
Class: |
H05K 1/18 20060101
H05K001/18; H01G 4/232 20060101 H01G004/232; H01C 7/00 20060101
H01C007/00; H01C 7/04 20060101 H01C007/04; H01C 1/148 20060101
H01C001/148; H01C 7/18 20060101 H01C007/18; H01G 4/30 20060101
H01G004/30; H01G 2/06 20060101 H01G002/06; H01G 4/005 20060101
H01G004/005 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 28, 2017 |
JP |
2017-188313 |
Claims
1. An electronic component comprising: an element body formed of a
ceramic; an external electrode disposed on an outer surface of the
element body; and an internal conductor disposed in the element
body, wherein the external electrode has a first electrode layer
electrically connected to the internal conductor, a second
electrode layer disposed to cover the first electrode layer, and a
third electrode layer disposed to cover the second electrode layer,
and a thermal conductivity of the second electrode layer is lower
than a thermal conductivity of the first electrode layer.
2. The electronic component according to claim 1, wherein a thermal
conductivity of the third electrode layer is lower than a thermal
conductivity of the first electrode layer.
3. The electronic component according to claim 1, wherein the first
electrode layer and the second electrode layer contain an identical
metal component.
4. The electronic component according to claim 1, wherein the first
electrode layer and the second electrode layer are formed of
different metal materials, and the second electrode layer contains
Ag.
5. The electronic component according to claim 1, wherein the
second electrode layer contains an identical metal component with
respect to that of the first electrode layer and is formed of a
non-identical metal component with respect to that of the third
component.
6. The electronic component according to claim 1, further
comprising: a thin film layer disposed on the outer surface of the
element body.
7. The electronic component according to claim 6, wherein the thin
film layer is formed of an amorphous glass coat.
8. The electronic component according to claim 6, wherein the thin
film layer contains Al.
9. The electronic component according to claim 6, wherein the thin
film layer is formed along a surface shape of the outer surface of
the element body.
10. The electronic component according to claim 1, wherein the
element body has a pair of end surfaces facing each other and four
side surfaces connecting the pair of end surfaces, the outer
electrode is disposed near each of the pair of end surfaces, and
the first electrode layer has a thickness of a central portion that
is smaller than a thickness of an end portion when viewed from a
facing direction of the pair of end surfaces.
11. The electronic component according to claim 1, wherein the
element body has a pair of end surfaces facing each other and four
side surfaces connecting the pair of end surfaces, the outer
electrode is disposed near each of the pair of end surfaces, and
the second electrode layer has a thickness of a central portion
that is larger than a thickness of an end portion when viewed from
a facing direction of the pair of end surfaces.
12. An electronic device comprising: an electronic component
according to claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation of U.S. application Ser.
No. 16/134,733 filed Sep. 18, 2018, which is based on and claims
priority under 35 U.S.C. 119 from Japanese Patent Application No.
2017-188313 filed on Sep. 28, 2017. The contents of the above
applications are incorporated herein by reference.
TECHNICAL FIELD
[0002] An aspect of the present invention relates to an electronic
component.
BACKGROUND
[0003] An electronic component including an element body having a
pair of end surfaces facing each other and four side surfaces
connecting the pair of end surfaces and formed of a ceramic, and a
first external electrode and a second external electrode
respectively disposed on the side of the pair of end surfaces of
the element body is known (for example, refer to PCT International
Publication No WO 2016/084457).
SUMMARY
[0004] When an electronic component is mounted on a circuit board
or the like, heat (board heat, resistance heat) generated in the
circuit board may be transferred to the element body via the
external electrode. Characteristics of the electronic component may
deteriorate when heat is transferred to the element body
(functional part). Therefore, reliability of the electronic
component may be lowered.
[0005] One aspect of the present invention is to provide an
electronic component capable of curbing deterioration of
reliability.
[0006] An electronic component according to one aspect of the
present invention includes an element body having a pair of end
surfaces which face each other and four side surfaces which connect
the pair of end surfaces and formed of a semiconductor ceramic, a
thin film layer disposed to cover the pair of end surfaces and the
four side surfaces and having an electrical insulation property, a
first external electrode and a second external electrode disposed
on a side of each of the pair of end surfaces, and an internal
conductor disposed in the element body, wherein the thin film layer
is formed along a surface shape of each of the pair of end surfaces
and the four side surfaces, each of the first external electrode
and the second external electrode has a first electrode layer
disposed on the thin film layer and electrically connected to the
internal conductor, and a second electrode layer disposed to cover
the first electrode layer, and a thermal conductivity of the second
electrode layer is lower than a thermal conductivity of the first
electrode layer.
[0007] In the electronic component according to one aspect of the
present invention, the second electrode layer is disposed to cover
the first electrode layer. The thermal conductivity of the second
electrode layer is lower than the thermal conductivity of the first
electrode layer. Therefore, when an electronic component is mounted
on a circuit board or the like, transmission of heat generated in
the circuit board or the like to the element body can be
suppressed. The outer surface of the element body is covered with a
thin film layer. Accordingly, in an electronic component, transfer
of heat generated in a circuit board or the like to the element
body can be suppressed. Therefore, deterioration in characteristics
of electronic components due to heat generated in a circuit board
or the like can be minimized. As a result, deterioration in
reliability of electronic components can be minimized.
[0008] In the electronic component, the thin film layer is formed
along the respective surface shapes of the pair of end surfaces and
the four side faces. An outer surface of the element body may be
concavo-convex. Therefore, a surface area of the thin film layer
can increase and an anchoring effect can be obtained by forming the
thin film layer along the surface shape of the outer surface of the
element body. Therefore, adhesion between the thin film layer and
the first electrode layer and the second electrode layer can be
improved. Therefore, in the electronic component, since bonding
strength between the thin film layer and the first electrode layer
and the second electrode layer can be secured, separation of the
first electrode layer and the second electrode layer therefrom can
be prevented. As a result, in the electronic component, it is
possible to minimize deterioration in reliability.
[0009] In one embodiment, a thickness of the thin film layer
disposed on the four side surfaces may be larger than a thickness
of the thin film layer disposed on the pair of end surfaces. In
this configuration, since the thickness of the thin film layer
disposed on the four side surfaces is large, it is possible to
prevent the heat from being transferred to the element body from
the four side surfaces. Also, since the thickness of the thin film
layer disposed on the end surface is relatively small (thin), an
internal conductor drawn to the end surface is able to break
through the thin film layer and be exposed from the thin film
layer. Therefore, it is possible to ensure electrical connection
between each of the first external electrode and the second
external electrode and the internal conductor.
[0010] In one embodiment, the thin film layer may have a thickness
of 50 nm or more and 300 nm or less.
[0011] According to one aspect of the present invention, it is
possible to curb deterioration of reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a perspective view showing an electronic component
according to one embodiment.
[0013] FIG. 2 is an exploded perspective view of an element
body.
[0014] FIG. 3 is a diagram showing a cross-sectional configuration
of the electronic component.
[0015] FIG. 4 is a diagram showing the cross-sectional
configuration of the electronic component.
[0016] FIG. 5 is an enlarged cross-sectional view showing a surface
of the element body and a thin film layer.
DETAILED DESCRIPTION
[0017] Hereinafter, preferable embodiments of the present invention
will be described in detail with reference to the accompanying
drawings. In the drawings, the same or similar elements are
designated by the same reference numerals, and repeated description
will be omitted.
[0018] As shown in FIG. 1, an NTC thermistor (electronic component)
1 includes an element body 2, and a first external electrode 3 and
a second external electrode 4 disposed on an outer surface of the
element body 2.
[0019] The element body 2 has a rectangular parallelepiped shape.
The rectangular parallelepiped shape includes a rectangular
parallelepiped shape in which a corner portion and a ridge portion
are chamfered, and a rectangular parallelepiped shape in which a
corner portion and a ridge portion are rounded. The element body 2
includes a pair of end surfaces 2a and 2b facing each other, a pair
of main surfaces (side surfaces) 2c and 2d facing each other, and a
pair of side surfaces 2e and 2f facing each other, as outer
surfaces thereof. A facing direction in which the pair of main
surfaces 2c and 2d face each other is a first direction D1. A
facing direction in which the pair of end surfaces 2a and 2b face
each other is a second direction D2. A facing direction in which
the pair of side surfaces 2e and 2f face each other is a third
direction D3. In the embodiment, the first direction D1 is a height
direction of the element body 2. The second direction D2 is a
longitudinal direction of the element body 2 and is orthogonal to
the first direction D1. The third direction D3 is a width direction
of the element body 2 and is orthogonal to the first direction D1
and the second direction D2.
[0020] The pair of end surfaces 2a and 2b extend in the first
direction D1 and perform connection between the pair of main
surfaces 2c and 2d. The pair of end surfaces 2a and 2b also extends
in the third direction D 3 (a short side direction of the pair of
main surfaces 2c and 2d). The pair of side surfaces 2e and 2f
extend in the first direction D1 to connect a space between the
pair of main surfaces 2c and 2d. The pair of side surfaces 2e and
2f also extends in the second direction D2 (a long side direction
of the pair of end surfaces 2a and 2b). In the embodiment, any one
of the pair of main surfaces 2c and 2d is defined as a mounting
surface facing another electronic device when the NTC thermistor 1
is mounted on another electronic device (for example, a circuit
board, an electronic component or the like).
[0021] As shown in FIG. 2, the element body 2 is formed by stacking
a plurality of thermistor layers 7 in a direction in which the pair
of main surfaces 2c and 2d face each other. In the element body 2,
a stacking direction of the plurality of thermistor layers 7
coincides with the first direction D1. Each of the thermistor
layers 7 may be made of, for example, a semiconductor ceramic
containing Mn, Ni and Co metal oxides as main components. The
thermistor layers 7 may contain Fe, Cu, Al, Zr or the like as
auxiliary components for allowing properties thereof to be adjusted
(such as rate of change in resistance) in addition to each of Mn,
Ni and Co metal oxides as main components. The thermistor layers 7
may be formed of Mn and Ni metal oxides or Mn and Co metal oxides
instead of each of Mn, Ni and Co metal oxides. In the actual
element body 2, each of the thermistor layers 7 is integrated to
such an extent that a boundary between the thermistor layers 7
cannot be visually recognized.
[0022] A thin film layer 10 is disposed on an outer surface of the
element body 2. The thin film layer 10 is disposed on the pair of
end surfaces 2a and 2b, the pair of main surfaces 2c and 2d, and
the pair of side surfaces 2e and 2f. That is, the thin film layer
10 is disposed to cover the entire outer surface of the element
body 2. The thin film layer 10 is a glass layer having an
electrical insulation property. Specifically, the thin film layer
10 is an amorphous glass coating layer. The thin film layer 10 is
formed of a glass material such as silica glass and may include Al
and Li. Crystallized glass is not used as the material of the thin
film layer 10.
[0023] A thickness of the thin film layer 10 is 50 nm or more and
300 nm or less. As shown in FIGS. 3 and 4, a thickness T1 of the
thin film layer 10 disposed on the pair of end surfaces 2a and 2b
is smaller than a thickness T2 of the thin film layer 10 disposed
on the pair of main surfaces 2c and 2d and the pair of side
surfaces 2e and 2f (T1<T2). In other words, the thickness T2 of
the thin film layer 10 disposed on the pair of main surfaces 2c and
2d and the pair of side surfaces 2e and 2f is larger than the
thickness T1 of the thin film layer 10 disposed on the pair of end
surfaces 2a and 2b. The thickness T1 is, for example, 50 nm. The
thickness T2 is, for example, 80 nm.
[0024] The thin film layer 10 is formed along each surface shape of
the pair of end surfaces 2a and 2b, the pair of main surfaces 2c
and 2d, and the pair of side surfaces 2e and 2f of the element body
2. The thin film layer 10 reflects the surface shapes of the pair
of end surfaces 2a and 2b, the pair of main surfaces 2c and 2d and
the pair of side surfaces 2e and 2f of the element body 2. That is,
in a cross section shown in FIG. 5, a surface shape of the thin
film layer 10 is the same as the surface shape of each of the pair
of end surfaces 2a and 2b, the pair of main surfaces 2c and 2d, and
the pair of side surfaces 2e and 2f of the element body 2.
[0025] As shown in FIG. 5, for example, when the surface shape of
the main surface 2c has a concavo-convex shape, the thin film layer
10 is formed along irregularities of the main surface 2c (or by
reflecting the irregularities). In other words, the thin film layer
10 is formed on the main surface 2c to have substantially a uniform
thickness with respect to the main surface 2c. The thin film layer
10 is formed by, for example, a sputtering method. The thin film
layer 10 may be formed by CVD, PVD or the like.
[0026] As shown in FIG. 2, the NTC thermistor 1 includes a
plurality of first internal electrodes 5 and a plurality of second
internal electrodes 6 as internal conductors disposed inside the
element body 2. In the embodiment, the number (three in the
embodiment) of the plurality of first internal electrodes 5 is the
same as the number of the plurality of second internal electrodes
6. Each of the plurality of first internal electrodes 5 is exposed
on the end surface 2a. Each of the plurality of second internal
electrodes 6 is exposed on the end surface 2b.
[0027] The first internal electrode 5 and the second internal
electrode 6 are disposed at different positions (layers) in the
first direction D1 of the element body 2. The first internal
electrode 5 and the second internal electrode 6 are alternately
disposed in the element body 2 to face each other with an interval
therebetween in the first direction D1.
[0028] As shown in FIG. 1, the first external electrode 3 is
disposed on the side of one end surface 2a. The first external
electrode 3 is formed on five surfaces of one end surface 2a, the
pair of main surfaces 2c and 2d, and the pair of side surfaces 2e
and 2f. The first internal electrode 5 is directly connected to the
first external electrode 3.
[0029] The first external electrode 3 includes a first electrode
layer 20, a second electrode layer 21, a first plating layer 22,
and a second plating layer 23.
[0030] The first electrode layer 20 is disposed on the thin film
layer 10. The first electrode layer 20 is disposed on one end
surface 2a of the element body 2. The first electrode layer 20 may
be disposed at edge portions of the pair of main surfaces 2c and 2d
and the pair of side surfaces 2e and 2f on the side of the end
surface 2a. The first electrode layer 20 is disposed to cover the
first internal electrode 5 exposed on the end surface 2a (exposed
from the thin film layer 10).
[0031] The first electrode layer 20 is formed by applying a
conductive paste to the surface of the element body 2 (one end
surface 2a in the embodiment) and baking the conductive paste. The
first electrode layer 20 is a sintered metal layer formed by
sintering a metal component (metal powder) contained in the
conductive paste. In the embodiment, the first electrode layer 20
is a sintered metal layer formed of Ag. The first electrode layer
20 may be a sintered metal layer formed of Pd. A powder composed of
Ag or Pd mixed with a glass component, an organic binder, and an
organic solvent is used as the conductive paste.
[0032] The first electrode layer 20 is electrically connected to
the first internal electrode 5. When the first electrode layer 20
is formed by baking the conductive paste, the first internal
electrode 5 exposed on the end surface 2a breaks through the thin
film layer 10. At this time, the conductive paste is sintered while
the first internal electrode 5 exposed from the thin film layer 10
and the conductive paste are in contact with each other.
Accordingly, the first electrode layer 20 is electrically connected
to the first internal electrode 5.
[0033] The second electrode layer 21 is disposed to cover the first
electrode layer 20. The second electrode layer 21 is formed on five
surfaces of one end surface 2a, the pair of main surfaces 2c and
2d, and the pair of side surfaces 2e and 2f. That is, an edge of
the second electrode layer 21 is disposed on the thin film layer
10.
[0034] The second electrode layer 21 is a conductive resin layer. A
thermosetting resin mixed with a conductive material and an organic
solvent or the like is used as the conductive resin. For example, a
metal powder is used as the conductive material. For example, Ag
powder is used as the metal powder. For example, a phenol resin, an
acrylic resin, a silicone resin, an epoxy resin, or a polyimide
resin is used as the thermosetting resin. In the second electrode
layer 21, a thickness of a central portion in the first direction
D1 of the element body 2 may be larger than a thickness on the side
of the pair of main surfaces 2c and 2d and a thickness on the side
of the pair of side surfaces 2e and 2f.
[0035] A thermal conductivity of the second electrode layer 21 is
lower than a thermal conductivity of the first electrode layer 20.
In other words, the thermal conductivity of the first electrode
layer 20 is higher than the thermal conductivity of the second
electrode layer 21. For example, the thermal conductivity of the
first electrode layer 20 is about 10 to 80 times the thermal
conductivity of the second electrode layer 21.
[0036] The first plating layer 22 is disposed to cover the second
electrode layer 21. The first plating layer 22 is formed on five
surfaces of one end surface 2a, the pair of main surfaces 2c and
2d, and the pair of side surfaces 2e and 2f. That is, an edge of
the first plating layer 22 is disposed on the thin film layer 10.
The first plating layer 22 is a Ni plating layer formed by Ni
plating.
[0037] The second plating layer 23 is disposed to cover the first
plating layer 22. The second plating layer 23 is formed on five
surfaces of one end surface 2a, the pair of main surfaces 2c and
2d, and the pair of side surfaces 2e and 2f. That is, an edge of
the second plating layer 23 is disposed on the thin film layer 10.
The second plating layer 23 is a Sn plating layer formed by Sn
plating.
[0038] As shown in FIG. 1, the second external electrode 4 is
disposed on the side of the other end surface 2b. The second
external electrode 4 is formed on five surfaces of one end surface
2b, the pair of main surfaces 2c and 2d, and the pair of side
surfaces 2e and 2f. The second internal electrode 6 is directly
connected to the second external electrode 4.
[0039] The second external electrode 4 includes a first electrode
layer 30, a second electrode layer 31, a first plating layer 32,
and a second plating layer 33.
[0040] The first electrode layer 30 is disposed on one end surface
2b of the element body 2. The first electrode layer 30 is
electrically connected to the second internal electrode 6. The
first electrode layer 30 is formed of the same material as the
first electrode layer 20.
[0041] The second electrode layer 31 is disposed to cover the first
electrode layer 30. The second electrode layer 31 is formed on five
surfaces of one end surface 2b, the pair of main surfaces 2c and
2d, and the pair of side surfaces 2e and 2f. The second electrode
layer 31 is formed of the same material as the second electrode
layer 21.
[0042] The first plating layer 32 is disposed to cover the second
electrode layer 31. The first plating layer 32 is formed on five
surfaces of one end surface 2b, the pair of main surfaces 2c and
2d, and the pair of side surfaces 2e and 2f. The first plating
layer 32 is formed of the same material as the first plating layer
22.
[0043] The second plating layer 33 is disposed to cover the first
plating layer 32. The second plating layer 33 is formed on five
surfaces of one end surface 2b, the pair of main surfaces 2c and
2d, and the pair of side surfaces 2e and 2f. The second plating
layer 33 is formed of the same material as the second plating layer
23.
[0044] As described above, in the NTC thermistor 1 according to the
embodiment, the second electrode layer 21 (the second electrode
layer 31) of the first external electrode 3 (the second external
electrode 4) is disposed to cover the first electrode layer 20 (the
first electrode layer 30). A thermal conductivity of the second
electrode layer 21 (the second electrode layer 31) is lower than a
thermal conductivity of the first electrode layer 20 (the first
electrode layer 30). Therefore, when the NTC thermistor 1 is
mounted on a circuit board or the like, heat generated in the
circuit board or the like can be suppressed from being transferred
to the element body 2. Also, the outer surface of the element body
2 is covered with the thin film layer 10. Thus, in the NTC
thermistor 1, the heat generated in the circuit board or the like
can be suppressed from being transferred to the element body 2.
Accordingly, the NTC thermistor 1 can minimize deterioration of
characteristics due to the heat generated in the circuit board or
the like. As a result, in the NTC thermistor 1, it is possible to
minimize deterioration in reliability. Therefore, the NTC
thermistor 1 can accurately detect an ambient temperature without
being affected by the heat of the circuit board or the like.
[0045] In the NTC thermistor 1 according to the embodiment, the
thin film layer 10 is formed along the respective surface shapes of
the pair of end surfaces 2a and 2b, the pair of main surfaces 2c
and 2d, and the pair of side surfaces 2e and 2f. The outer surface
of the element body 2 may be concavo-convex. Therefore, a surface
area of the thin film layer 10 can increase and an anchoring effect
can be obtained by forming the thin film layer 10 along the surface
shape of the outer surface of the element body 2. Therefore,
adhesion between the thin film layer 10 and the first electrode
layer 20 and the second electrode layer 21 (the first electrode
layer 30 and the second electrode layer 31) can be improved. Thus,
since the NTC thermistor 1 can secure bonding strength between the
thin film layer 10 and the first electrode layer 20 and the second
electrode layer 21 (the first electrode layer 30 and the second
electrode layer 31), separation of the first electrode layer 20 and
the second electrode layer 21 (the first electrode layer 30 and the
second electrode layer 31) can be minimized. As a result, in the
NTC thermistor 1, it is possible to minimize deterioration in
reliability.
[0046] In the NTC thermistor 1 according to the embodiment, the
thickness T2 of the thin film layer 10 disposed on the pair of main
surfaces 2c and 2d and the pair of side surfaces 2e and 2f is
larger than the thickness T1 of the thin film layer 10 disposed on
the pair of end surfaces 2a and 2b. In this configuration, since
the thickness of the thin film layer 10 disposed on the pair of
main surfaces 2c and 2d and the pair of side surfaces 2e and 2f is
large, it is possible to prevent heat from being transferred from
the pair of main surfaces 2c and 2d and the pair of side surfaces
2e and 2f into the element body 2. Further, since the thickness of
the thin film layer 10 disposed on the pair of end surfaces 2a and
2b is relatively small (thin), the first internal electrode 5
withdrawn to the end surfaces 2a and 2b and the second internal
electrode 6 withdrawn to the end surface 2b breaks through the thin
film layer 10 and are exposed from the thin film layer 10.
Therefore, electrical connection between the first external
electrode 3 and the second external electrode 4 and the first
internal electrode 5 and the second internal electrode 6 can be
ensured.
[0047] In the NTC thermistor 1 according to the embodiment, the
thin film layer 10 is formed of amorphous glass. For example, when
the thin film layer 10 is formed of crystallized glass, it is
difficult to form the thin film layer 10 along the surface shape of
the outer surface of the element body 2, and the surface of the
thin film layer 10 may be smooth (flat). In this case, the adhesion
between the thin film layer 10 and the first electrode layer 20 and
the second electrode layer 21 (the first electrode layer 30 and the
second electrode layer 31) cannot be ensured. On the other hand,
when the thin film layer 10 is formed of amorphous glass, it is
possible to form the thin film layer 10 along the surface shape of
the outer surface of the element body 2. Thus, in the NTC
thermistor 1, the surface area of the thin film layer 10 can
increase and an anchoring effect can be obtained. Therefore, in the
NTC thermistor 1, the adhesion between the thin film layer 10 and
the first electrode layer 20 and the second electrode layer 21 (the
first electrode layer 30 and the second electrode layer 31) can be
improved.
[0048] The element body 2 is formed of a semiconductor ceramic.
Therefore, when the first plating layer 22 and the second plating
layer 23 of the first external electrode 3 and the first plating
layer 32 and the second plating layer 33 of the second external
electrode 4 are formed, the plating may extend from the element
body 2 and the plating may be formed at an undesired place on the
element body 2. In the NTC thermistor 1 according to the
embodiment, the thin film layer 10 is formed on the outer surface
of the element body 2. Therefore, formation of a plating layer at
an undesired place on the element body 2 can be avoided.
[0049] Although the embodiment of the present invention have been
described above, the present invention is not necessarily limited
to the above-described embodiment, and various modifications are
possible without departing from the gist thereof.
[0050] In the above-described embodiment, an example in which the
electronic component is the NTC thermistor 1 has been described.
However, the electronic component may be a varistor, a PTC
thermistor or the like. When the electronic component is a
varistor, the semiconductor ceramic contains, for example, ZnO
(zinc oxide) as a main component, and metal elements such as Co,
rare earth metal elements, Group IIIb elements (B, Al, Ga, In), Si,
Cr, Mo, alkali metal elements (K, Rb, Cs), alkaline earth metal
elements (Mg, Ca, Sr, Ba), or the like, and oxides thereof may be
contained as accessory components.
[0051] In the above-described embodiment, an example in which three
first internal electrodes 5 and three second internal electrodes 6
are disposed has been described. However, the number of internal
electrodes (internal conductors) may be appropriately set according
to the design.
[0052] The shapes of the first external electrode 3 and the second
external electrode 4 may be appropriately set according to the
design.
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