U.S. patent application number 09/757959 was filed with the patent office on 2001-05-10 for mounting arrangement for multilayer electronic part.
This patent application is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Sakai, Norio.
Application Number | 20010000986 09/757959 |
Document ID | / |
Family ID | 17035870 |
Filed Date | 2001-05-10 |
United States Patent
Application |
20010000986 |
Kind Code |
A1 |
Sakai, Norio |
May 10, 2001 |
Mounting arrangement for multilayer electronic part
Abstract
A chip capacitor includes a multilayer body composed of a
plurality of stacked sheet layers made of ceramics; capacitor
electrodes and via hole electrodes disposed inside the multilayer
body; and outer electrodes formed on only main surfaces of the
multilayer body such that they are electrically connected to the
capacitor electrodes via the via hole electrodes. Some of the
capacitor electrodes are electrically connected by the via hole
electrodes, and the other capacitor electrodes are electrically
connected by other via hole electrodes.
Inventors: |
Sakai, Norio; (Moriyama-shi,
JP) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
Murata Manufacturing Co.,
Ltd.
|
Family ID: |
17035870 |
Appl. No.: |
09/757959 |
Filed: |
January 10, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09757959 |
Jan 10, 2001 |
|
|
|
09372547 |
Aug 11, 1999 |
|
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Current U.S.
Class: |
361/502 |
Current CPC
Class: |
H01G 4/30 20130101; H03H
7/0115 20130101; Y10T 29/49165 20150115; Y10T 29/49126 20150115;
H01G 4/232 20130101; H01F 41/043 20130101; H03H 2001/0085
20130101 |
Class at
Publication: |
361/502 |
International
Class: |
H01G 009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 25, 1998 |
JP |
10-238827 |
Claims
What is claimed is:
1. A multilayer electronic part, comprising: a multilayer body
including a plurality of stacked ceramic sheet layers, each layer
having spaced apart opposing main surfaces and being stacked in a
direction which is substantially perpendicular to the main surfaces
of the layers, the multilayer body including first and second
opposing main outer surfaces defined by one of the opposing main
surfaces of each outermost stacked ceramic sheet layer; a plurality
of inner electrodes disposed on at least some of the main surfaces
of the ceramic sheet layers; a plurality of connectors disposed
within the multilayer body, the connectors electrically coupling
respective inner electrodes; and a plurality of outer electrodes,
at least one of the outer electrodes disposed on each main outer
surface of the multilayer body, each of the outer electrodes being
electrically connected to at least one of the inner electrodes via
at least one of the connectors.
2. The multilayer electronic part of claim 1, wherein each
connector includes an aperture extending between main surfaces of a
corresponding one of the ceramic sheet layers, the aperture being
substantially filled with a conductive material which provides an
electrical connection from one of the inner electrodes, through the
ceramic sheet layer, to at least one of (i) another inner
electrode; and (ii) one of the outer electrodes.
3. The multilayer electronic part of claim 2, wherein each ceramic
sheet layer, having one of the inner electrodes, includes at least
one connector operable to electrically couple that inner electrode
to at least one of (i) another inner electrode of another ceramic
sheet layer; and (ii) one of the outer electrodes.
4. The multilayer electronic part of claim 3, wherein at least one
of the ceramic sheet layers, having one of the inner electrodes,
includes at least one connector which does not electrically couple
that inner electrode to any other electrode.
5. The multilayer electronic part of claim 4, comprising N ceramic
sheet layers, each being designatable as an n-th ceramic sheet
layer, n=0, 1, 2, 3, . . . N, the n=0 and n=N ceramic sheet layers
being the outermost ceramic sheet layers, wherein substantially all
of the ceramic sheet layers, other than the outermost ceramic sheet
layers, include: one of the inner electrodes disposed on a main
surface thereof; at least one first connector operable to
electrically couple that inner electrode to another inner electrode
of ceramic sheet layer which is at least one of (i) n+2 layers away
therefrom, and (ii) n-2 layers away therefrom; and at least one
second connector which electrically couples electrodes of directly
adjacent ceramic sheet layers together.
6. The multilayer electronic part of claim 5, wherein each of the
outermost ceramic sheet layers include at least one connector
operable to electrically couple the outer electrode thereof to the
inner electrode of a directly adjacent ceramic sheet layer.
7. The multilayer electronic part of claim 6, wherein the ceramic
sheet layers form a capacitor.
8. The multilayer electronic part of claim 3, wherein substantially
all of the ceramic sheet layers, other than the outermost ceramic
sheet layers, include: one of the inner electrodes disposed on a
main surface thereof; at least one first connector operable to
electrically couple that inner electrode to inner electrodes of
directly adjacent ceramic sheet layers.
9. The multilayer electronic part of claim 8, wherein each of the
outermost ceramic sheet layers include at least one connector
operable to electrically couple the outer electrode thereof to the
inner electrode of a directly adjacent ceramic sheet layer.
10. The multilayer electronic part of claim 8, wherein each of the
inner electrodes are in the form of strip lines, each strip line
forming a portion of a coil, the multilayer electronic part forming
an inductor.
11. The multilayer electronic part of claim 1, wherein each of the
ceramic sheet layers is a parallelepiped, end faces thereof
defining respective thicknesses.
12. The multilayer electronic part of claim 11, wherein each
ceramic sheet layer includes at least one end face disposed
substantially perpendicular to and between the spaced apart
opposing main surfaces, said ceramic sheet layers being stacked
such that said end faces form a mounting surface oriented
substantially parallel to the stacking direction.
13. The multilayer electronic part of claim 12, wherein the outer
electrodes are sized and shaped to provide an electrical connection
with a printed circuit board when the mounting surface is oriented
proximate to the printed circuit board.
14. A method of producing a multilayer electronic part, comprising
the steps of: forming a plurality of mother ceramic sheet layers
such that each mother ceramic sheet layer includes spaced apart
opposing main surfaces; forming a plurality of inner electrodes on
the main surfaces of at least some of the mother ceramic sheet
layers; forming a plurality of connectors in the at least some
mother ceramic sheet layers, at least some of the connectors being
electrically coupled to corresponding inner electrodes; forming a
plurality of outer electrodes, at least one outer electrode on one
main surface of each of a first and second one of the mother
ceramic sheet layers; stacking the mother ceramic sheet layers one
atop the other in a direction which is substantially perpendicular
to the main surfaces of the layers such that: (i) the first and
second ceramic sheet layers are outermost layers and define first
and second opposing main outer surfaces of the stack, (ii) the
connectors electrically couple, respective inner electrodes to one
another, and each of the outer electrodes to at least one of the
inner electrodes; press-bonding the plurality of stacked mother
ceramic sheet layers to obtain a mother multilayer body; and
cutting the mother multilayer body into separate multilayer bodies,
each having: a plurality of stacked ceramic sheet layers, a
plurality of inner electrodes, first and second outer electrodes on
opposing main outer surfaces of the multilayer body, and a
plurality of connectors electrically connecting at least some of
the electrodes together.
15. The method of producing the multilayer electronic part of claim
14, further comprising the step of baking the ceramic sheet layer
one of before and after the cutting step.
16. The method of producing the multilayer electronic part of claim
15, wherein the step of forming the connectors includes the steps
of: forming an aperture extending between main surfaces of a
corresponding one of the ceramic sheet layers; and filling the
aperture with a conductive material.
17. The method of producing the multilayer electronic part of claim
16, wherein the step of forming the connectors results in each
ceramic sheet layer, having one of the inner electrodes thereon,
including at least one connector operable to electrically couple
that inner electrode to at least one of (i) another inner electrode
of another ceramic sheet layer, (ii) one of the outer electrodes,
and (iii) no other electrode.
Description
BACKGROUND OF THE INVENTION
1. 1. Field of the Invention
2. The present invention relates to a multilayer electronic part, a
method of producing the multilayer electronic part, and more
particularly, to a multilayer electronic part (and a method of
producing same) in which a plurality of outer electrodes are
disposed on only the main surfaces of a multilayer body, and an end
face of the multilayer body serves as a mounting surface for
mounting the part on a mounting substrate.
3. 2. Description of the Related Art
4. Multilayer electronic parts which utilize chip capacitors and
chip inductors are essential in obtaining miniaturization and
higher performance of electronic devices. There is a demand for
increased density and performance of such devices and, in response
to this demand, a chip capacitor has been proposed in Japanese
Patent Publication No. 57-56217.
5. FIG. 5 is a perspective view of such a chip capacitor 50. Chip
capacitor 50 comprises a multilayer body 52 composed of a plurality
of stacked sheet layers 51 made of ceramics; inner electrodes 53
made of copper or the like inside the multilayer body 52; and outer
electrodes 54 disposed on an end face of the multilayer body 52. In
this case, the inner electrodes 53 are connected to the outer
electrodes 54 by lead electrodes 55 formed at the ends of the inner
electrodes 53. Although not shown, the end face of the multilayer
body 52 where the outer electrodes 54 are disposed serves as a
mounting surface of the chip capacitor 50, and the chip capacitor
50 is mounted on a printed board by connecting the outer electrodes
54 to a pad on the printed board using solder or the like.
6. In multilayer electronic parts employing the above-described
conventional chip capacitor, however, since the outer electrodes
are formed on the end face of the multilayer body, it is necessary,
in producing the chip capacitor, to cut a mother multilayer body
into individual multilayer bodies and to subsequently form outer
electrodes on an end face, which is the cutting face, of the
individual multilayer bodies.
7. As a result, the following problems arise:
8. 1) The production process is complicated and, therefore, the
production cost is high.
9. 2) The cutting surface is not sufficiently flat, and it is
difficult to narrow a resultant space between the outer
electrodes.
10. 3) It is impossible to measure the characteristics of
individual multilayer electronic parts in the assembled state.
SUMMARY OF THE INVENTION
11. To overcome the above described problems, preferred embodiments
of the present invention provide a multilayer electronic part that
allows low production costs and narrowing of the space between
outer electrodes, and a method of producing the multilayer
electronic part.
12. One embodiment of the present invention provides a multilayer
electronic part comprising: a multilayer body composed of a
plurality of stacked sheet layers made of ceramics, said plurality
of stacked sheet layers defining a stacking direction substantially
perpendicular to a main surface of each of said plurality of
stacked sheet layers; a plurality of inner electrodes and
connecting means provided inside said multilayer body; and a
plurality of outer electrodes disposed on only a main surface of
said multilayer body so as to be electrically connected to any of
said inner electrodes via said connecting means, and said
multilayer body further comprising a mounting surface so that said
said multilayer body is mounted at said mounting surface, said
mounting surface being substantially parallel to said stacking
direction.
13. Another embodiment of the present invention provides a method
of producing a multilayer electronic part comprising the steps of:
preparing a plurality of mother sheet layers made of ceramics;
forming inner electrodes and connecting means on any one of said
plurality of mother sheet layers; forming a mother multilayer body
by stacking and press-bonding said plurality of mother sheet
layers; forming an outer electrode on only a main surface of said
mother multilayer body so as to be electrically connected to any
one of said inner electrodes via said connecting means; cutting
said mother multilayer body into a multilayer body having said
inner electrode, said outer electrode, and said connecting means;
and baking said mother multilayer body or said multilayer body.
14. According to the multilayer electronic part of the present
invention, since the outer electrode is disposed on only the main
surface of the base plate, it can be formed such that the mother
multilayer body is not yet cut in the process of producing the
multilayer electronic part.
15. According to the method of producing a multilayer electronic
part of the present invention, since the method includes the step
of forming outer electrodes on the main surface of the mother
multilayer body, it is possible to narrow the space between the
outer electrodes.
16. Further objects, features, and advantages of the present
invention will become apparent from the following description of
the preferred embodiments with reference to the attached
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
17. FIG. 1 is an exploded perspective view of a multilayer
electronic part according to a first embodiment of the present
invention.
18. FIG. 2 is a cross-sectional view showing the multilayer
electronic part of FIG. 1 mounted on a mounting substrate.
19. FIGS. 3A to 3D are cross-sectional views illustrating a method
of producing the multilayer electronic part shown in FIG. 1.
20. FIG. 4 is an exploded perspective view showing a multilayer
electronic part according to a second embodiment of the present
invention.
21. FIG. 5 is a sectional view of a prior art chip capacitor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
22. FIG. 1 is an exploded perspective view showing a multilayer
electronic part according to a first embodiment of the present
invention. A chip capacitor 10 is a multilayer electronic component
and includes a multilayer body 11 composed of a plurality of
stacked sheet layers 12a to 12f made of ceramics. The chip
capacitor also includes capacitor electrodes 13a to 13e serving as
inner electrodes disposed within the multilayer body 11; via hole
electrodes 14 serving as connectors; and outer electrodes 15a and
15b disposed on only the main surfaces 11a and 11b of the
multilayer body 11 such that they are electrically connected to the
capacitor electrodes 13a and 13e via the via hole electrodes
14.
23. In this case, the capacitor electrodes 13a, 13c, and 13e, and
the capacitor electrodes 13b and 13d are electrically connected via
the via hole electrodes 14, respectively.
24. FIG. 2 is a cross-sectional view showing the chip capacitor 10
of FIG. 1 mounted on a mounting substrate. The chip capacitor 10 is
mounted on a printed board 1, which serves as a mounting substrate,
by connecting the outer electrodes 15a and 15b to a wiring pattern
2 on the printed board 1 using, e.g., solder 3. A lengthwise end
face lic of the multilayer body 11 of the chip capacitor 10 is used
as a mounting surface.
25. FIGS. 3A to 3D are cross-sectional views which will be used in
explaining a method of producing the chip capacitor 10 shown in
FIG. 1.
26. First, a plurality of mother sheet layers 21a to 21f made of
ceramics are prepared (FIG. 3A).
27. Next, through holes 22 are formed in the mother sheet layers 21
to 21f by way of, for example, punching, and the capacitor
electrodes 13a to 13e are formed on the mother sheet layers 21b to
21f, respectively, for example by screen-printing conductive paste
thereon. Further, the via hole electrodes 14 are formed by
disposing conductive paste in the through holes 22 (FIG. 3B).
28. After a mother multilayer body 23 is formed by laying the
plurality of mother sheet layers 21a to 21f on top of one another,
conductive paste is screen-printed on only the main surfaces 23a
and 23b of the mother multilayer body 23 such that the outer
electrodes 15a and 15b are formed thereon. In this case, the
capacitor electrodes 13a to 13e on the mother sheet layers 21b to
21f, and the outer electrodes 15a and 15b on the main surfaces 23a
and 23b of the mother multilayer body 23 are connected via the via
hole electrodes 14. Since the mother multilayer body 23 has not yet
been subjected to cutting, the main surfaces 23a and 23b thereof
with outer electrodes 15a and 15b have a high level of flatness
(FIG. 3C).
29. Next, the mother multilayer 11, provided with the capacitor
electrodes 13a to 13e therein and the outer electrodes 15a and 15b
on the main surfaces 23a and 23b thereof, is cut into blocks, each
of which is to become a separate multilayer body 11. Subsequently,
the multilayer body 11, the capacitor electrodes 13a to 13e, the
via hole electrodes 14, and the outer electrodes 15a and 15b are
baked together (FIG. 3D).
30. According to the above-described production method, the chip
capacitor 10 is completed, which has the capacitor electrodes 13a
to 13e inside the multilayer body 11, and the outer electrodes 15a
and 15b formed on only the main surfaces 11a and lib of the
multilayer body 11.
31. FIG. 4 is an exploded perspective view of a multilayer
electronic part according to a second embodiment of the present
invention. A chip inductor 30 is a multilayer electronic component
and includes a multilayer body 31 composed of a plurality of
stacked sheet layers 32a to 32f made of ceramics; inductor
electrodes 33a to 33e serving as inner electrodes disposed inside
the multilayer body 31; via hole electrodes 34 serving as
connectors; and outer electrodes 35a and 35b formed on only the
main surfaces 31a and 31b of the multilayer body 31 such that they
are electrically connected to any of the inductor electrodes 33a
and 33e via the via hole electrodes 34.
32. In this case, the inductor electrodes 33a and 33b, the inductor
electrodes 33b and 33c, the inductor electrodes 33c and 33d, and
the inductor electrodes 33d and 33e are electrically connected,
respectively, by the via hole electrodes 34 formed at one end of
the inductor electrodes 33a and 33e.
33. Although not shown, the chip inductor 30 is mounted on a
printed board (serving as a mounting substrate) by connecting the
outer electrodes 35a and 35b to a wiring pattern on the printed
board (e.g., using solder). A lengthwise end face 31c of the
multilayer body 31 of the chip inductor 30 is used as a mounting
surface, in a manner similar to that of the chip capacitor 10 of
the first embodiment shown in FIG. 1.
34. The chip inductor 30 is produced using a method substantially
similar to the production method of the chip capacitor 10
illustrated in FIGS. 3A to 3D.
35. While a chip capacitor or a chip inductor is used as the
multilayer electronic part in the above embodiments, the present
invention is also applicable to, for example, a chip resistor, a
condenser (capacitor) array part, an inductor array part, or a
resistor array part having a plurality of condensers, a plurality
of inductors, and/or a plurality of resistors formed inside a
multilayer body, and an LCR composite part having a condenser, an
inductor, and a resistor formed inside a multilayer body.
36. While the mother multilayer body is cut into blocks serving as
multilayer bodies before the multilayer body, the inner electrodes,
the connectors, and the outer electrodes are baked together in the
above-described production method, it may alternatively be cut into
10 blocks after being baked together.
37. According to the multilayer electronic part of the present
invention, since outer electrodes are formed on only the main
surfaces of the base plate, they can be formed before the mother
multilayer body is cut in the process of producing the multilayer
electronic part.
38. This makes it possible to simplify the production process and
to reduce the production cost. As a result, it is possible to
achieve a low-cost multilayer electronic part.
39. In accordance with the invention, the characteristics of
individual multilayer electronic parts can be measured when the
parts are combined in an assembly and, therefore, inspection can be
completed in a short time, and the time necessary for the
production process can be reduced.
40. According to the method of producing a multilayer electronic
part of the present invention, the step of forming outer electrodes
on the main surfaces of the mother multilayer body results in a
high level of flatness before cutting and, therefore, it is
possible to narrow any space between the outer electrodes, thereby
reducing the size of the multilayer electronic parts produced
according to the method.
41. Furthermore, since the outer electrodes can be formed
precisely, it is possible to improve the yield of multilayer
electronic parts, and to thereby reduce the costs thereof.
42. While the present invention has been described with reference
to what are presently considered to be the preferred embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments. On the contrary, the invention is intended
to cover various modifications and equivalent arrangements included
within the spirit and scope of the appended claims. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
* * * * *