U.S. patent number 9,271,400 [Application Number 14/016,415] was granted by the patent office on 2016-02-23 for electronic component and manufacturing method therefor.
This patent grant is currently assigned to Murata Manufacturing Co., Ltd.. The grantee listed for this patent is Murata Manufacturing Co., Ltd.. Invention is credited to Mitsuyoshi Hira, Seiji Kai, Takao Mukai, Shintaro Nakatani, Hisashi Yamazaki.
United States Patent |
9,271,400 |
Kai , et al. |
February 23, 2016 |
Electronic component and manufacturing method therefor
Abstract
An electronic component includes a frame-shaped supporting body
including a heat-curable resin and surrounding a functional unit on
one main surface of a substrate and so as to be separated from a
periphery of the substrate on an inner side and in which a lid
member is fixed to the supporting body such that an opening of the
frame-shaped supporting body is sealed. The frame-shaped supporting
body includes a frame-shaped supporting body main body, a first
protrusion that protrudes toward an inside from the supporting body
main body and a second protrusion that protrudes toward an outside
from the supporting body main body at a portion where the
supporting body main body and the first protrusion are continuous
with each other.
Inventors: |
Kai; Seiji (Nagaokakyo,
JP), Nakatani; Shintaro (Nagaokakyo, JP),
Hira; Mitsuyoshi (Nagaokakyo, JP), Mukai; Takao
(Nagaokakyo, JP), Yamazaki; Hisashi (Nagaokakyo,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Murata Manufacturing Co., Ltd. |
Nagaokakyo-shi, Kyoto-fu |
N/A |
JP |
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Assignee: |
Murata Manufacturing Co., Ltd.
(Kyoto, JP)
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Family
ID: |
46929944 |
Appl.
No.: |
14/016,415 |
Filed: |
September 3, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20140003017 A1 |
Jan 2, 2014 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/JP2011/079790 |
Dec 22, 2011 |
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Foreign Application Priority Data
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Mar 28, 2011 [JP] |
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2011-069305 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H03H
9/1071 (20130101); H05K 1/182 (20130101); H03H
3/08 (20130101); H05K 3/3431 (20130101); Y10T
29/49165 (20150115); H05K 2201/0999 (20130101); H05K
2201/10083 (20130101); Y10T 29/49124 (20150115); Y10T
29/49147 (20150115); Y10T 29/49128 (20150115); H05K
2201/2018 (20130101) |
Current International
Class: |
H05K
7/00 (20060101); H05K 1/18 (20060101); H03H
3/08 (20060101); H03H 9/10 (20060101); H05K
3/34 (20060101) |
Field of
Search: |
;361/760,764,783
;174/255,260-262 ;250/704 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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101409537 |
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Apr 2009 |
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CN |
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101889392 |
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Nov 2010 |
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CN |
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101924531 |
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Dec 2010 |
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CN |
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102 53 163 |
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May 2004 |
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DE |
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2002-261582 |
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Sep 2002 |
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JP |
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2002-532934 |
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Oct 2002 |
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JP |
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2006-333130 |
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Dec 2006 |
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JP |
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2007-318058 |
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Dec 2007 |
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JP |
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2008-182292 |
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Aug 2008 |
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JP |
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2009-278016 |
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Nov 2009 |
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JP |
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2010-157956 |
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Jul 2010 |
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JP |
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2010-200198 |
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Sep 2010 |
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JP |
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Other References
Official Communication issued in International Patent Application
No. PCT/JP2011/079790, mailed on Mar. 6, 2012. cited by applicant
.
Official Communication issued in corresponding German Patent
Application No. 11 2011 105 113.1, mailed on May 20, 2014. cited by
applicant.
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Primary Examiner: Semenenko; Yuriy
Attorney, Agent or Firm: Keating & Bennett, LLP
Claims
What is claimed is:
1. An electronic component comprising: a substrate; a functional
unit located on one main surface of the substrate; a frame-shaped
supporting body including a heat-curable resin that is arranged on
the one main surface of the substrate so as to surround the
functional unit and so as to be separated from a periphery of the
substrate on an inner side; and a lid member that is fixed to the
supporting body so as to seal an opening of the supporting body;
wherein the frame-shaped supporting body includes a frame-shaped
supporting body main body, a first protrusion that protrudes toward
an inside from the supporting body main body and a second
protrusion that is provided at a portion in which the supporting
body main body and the first protrusion are continuous with each
other so as to protrude toward an outside from the supporting body
main body, wherein the second protrusion is configured to prevent
occurrence of leak defects.
2. The electronic component according to claim 1, further
comprising a penetrating electrode that is electrically connected
to the functional unit and penetrates through the first protrusion
and the lid member, and an outer terminal that is connected to an
upper portion of the penetrating electrode.
3. The electronic component according to claim 2, wherein the
penetrating electrode includes an under bump metal portion and the
outer terminal includes a bump.
4. The electronic component according to claim 1, wherein the
functional unit located on the substrate includes at least one
interdigital transducer electrode and is a surface acoustic wave
device.
5. The electronic component according to claim 1, wherein the
functional unit is a wafer level chip size packaging surface
acoustic wave device.
6. The electronic component according to claim 1, further
comprising additional functional units located on the one main
surface of the substrate.
7. The electronic component according to claim 1, wherein the
frame-shaped supporting body is rectangular or substantially
rectangular.
8. The electronic component according to claim 1, further
comprising pad electrodes located on the one main surface of the
substrate and covered by the first and second protrusions.
9. The electronic component according to claim 3, wherein the under
bump metal portion includes a Ni layer and an Au layer stacked on
each other, or a single metal layer.
10. The electronic component according to claim 6, wherein the
functional units include a plurality of longitudinally coupled
resonator type surface acoustic wave filters and a plurality of
one-port-type surface acoustic wave resonators.
11. The electronic component according to claim 1, wherein one end
portion of the second protrusion is spaced in a lateral direction
from a position at which an edge of the first protrusion is
continuous with the supporting body main body.
12. The electronic component according to claim 1, wherein a
plurality of the first protrusion is provided inside the supporting
body main body at corner portions of the frame-shaped supporting
body, and a plurality of the second protrusion is provided.
13. The electronic component according to claim 12, wherein the
first protrusions and the second protrusions have a rectangular or
substantially rectangular shape in plan view.
14. The electronic component according to claim 1, wherein the
first protrusion extends from one long edge of the supporting body
main body so as to reach another long edge on an opposite side in a
central region in a length direction of the frame-shaped supporting
body.
15. The electronic component according to claim 1, wherein the
first protrusion is arranged so as to partition a space between two
longitudinal edges of the supporting body main body.
16. The electronic component according to claim 15, further
comprising a transmission filter on a first side of the first
protrusion and a reception filter on a second side of the first
protrusion.
17. An electronic component manufacturing method for manufacturing
the electronic component according to claim 1, the method
comprising: a step of preparing the substrate, on the one main
surface on which the functional unit is formed; a step of providing
the heat-curable resin on the one main surface of the substrate so
as to surround the functional unit on the one main surface of the
substrate and so as to contain the frame-shaped supporting body
main body, which is separated from the periphery of the substrate
on the inner side, and the first and second protrusions; a step of
stacking the lid member to form frame-shaped heat-curable resin on
the one main surface side of the substrate with the heat-curable
resin therebetween; and a step of completing the frame-shaped
supporting body, and joining the frame-shaped supporting body, the
one main surface of the substrate, and the lid member to one
another by curing the heat-curable resin.
18. The electronic component manufacturing method according to
claim 17, further comprising, after the step of completing the
frame-shaped supporting body, a step of forming a through hole that
penetrates through the first protrusion of the frame-shaped
supporting body and the lid member, a step of forming a penetrating
electrode in the through hole, and a step of joining an outer
terminal to an upper end of the penetrating electrode.
19. The electronic component manufacturing method according to
claim 18, wherein an under bump metal portion is formed as the
penetrating electrode and a bump is formed as the outer
terminal.
20. The electronic component manufacturing method according to
claim 17, wherein a surface acoustic wave substrate is prepared on
which a surface acoustic wave element functional unit is formed as
the substrate on which the functional unit is formed.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic component in which a
substrate and a lid member are joined to each other via a
frame-shaped supporting body including a heat-curable resin, and
relates to a manufacturing method therefor.
2. Description of the Related Art
In a surface acoustic wave filter device, for example, a package
structure having a cavity is adopted, in which a surface acoustic
wave filter element faces the cavity. Consequently, in order to
make progress in size reduction of such a device, development of
wafer level chip size packaging (WLCSP) has been progressing. In
WLCSP, the size of the planar shape of a package is the same as
that of a surface acoustic wave element chip.
For example, in Japanese Unexamined Patent Application Publication
No. 2002-532934, an example of this kind of surface acoustic wave
device is disclosed. As illustrated in FIG. 9, a surface acoustic
wave device 1001 described in Japanese Unexamined Patent
Application Publication No. 2002-532934 includes a plate-shaped
surface acoustic wave element 1002. The surface acoustic wave
element 1002 includes a piezoelectric substrate 1003. Functional
units 1004 including interdigital transducer (IDT), electrodes are
formed on the upper surface of the piezoelectric substrate 1003. A
rectangular frame-shaped supporting body 1005 is formed on the
upper surface of the surface acoustic wave element 1002. The
supporting body 1005 is arranged so as to surround the functional
units 1004. A lid member 1006 is fixed to the top of the supporting
body 1005 such that a cavity that the functional units 1004 face is
sealed.
Penetrating electrodes 1007 are formed so as to penetrate through
the frame-shaped supporting body 1005 and the lid member 1006.
Outer terminals 1008 are formed on the upper ends of the
penetrating electrodes 1007.
In the surface acoustic wave device 1001, the outer peripheries of
the supporting body 1005 and the lid member 1006 have the same
dimensions as the outer periphery of the surface acoustic wave
element 1002. Therefore, a reduction in size can be achieved.
On the other hand, in the surface acoustic wave device 1001, the
wider the cavity which the functional units 1004 face becomes, the
greater the number of functional units that can be arranged in the
cavity. If the size of the cavity can be increased, size reduction
of the surface acoustic wave device 1001 can also progress. In
order to increase the area of the planar shape of the cavity, the
width of the frame-shaped supporting body 1005 may be decreased.
However, the frame-shaped supporting body 1005 needs to have a
certain width in order to allow the penetrating electrodes 1007 to
be formed. In this case, the area of the cavity is decreased. In
addition, if the width of the supporting body 1005 is decreased,
the cavity cannot be sufficiently tightly sealed. Accordingly, in
cases such as where there is a change in temperature, there is a
risk of leak defects occurring. Consequently, there has been a
problem in that the environmental resistance has been degraded.
SUMMARY OF THE INVENTION
Preferred embodiments of the present invention provide an
electronic component including a package structure including a
cavity, in which progress can be made in size reduction, is capable
of suppressing or preventing leak defects and is therefore
excellent in terms of environmental resistance.
An electronic component according to a preferred embodiment of the
present invention includes a substrate, a functional unit located
on one main surface of the substrate, a frame-shaped supporting
body including a heat-curable resin that is arranged on the one
main surface of the substrate so as to surround the functional unit
and so as to be separated from the periphery of the substrate on
the inner side, and a lid member that is fixed to the supporting
body so as to seal an opening of the supporting body. In the
electronic component according to a preferred embodiment of the
present invention, the frame-shaped supporting body includes a
frame-shaped supporting body main body, a first protrusion that
protrudes toward the inside from the supporting body main body and
a second protrusion that is provided at a portion in which the
supporting body main body and the first protrusion are continuous
with each other so as to protrude toward the outside from the
supporting body main body.
In a certain specific aspect of the electronic component according
to a preferred embodiment of the present invention, the electronic
component further includes a penetrating electrode that is
electrically connected to the functional unit and is arranged so as
to penetrate through the first protrusion and the lid member, and
further includes an outer terminal that is connected to an upper
portion of the penetrating electrode. In this case, it is possible
to electrically connect the functional unit to the outer terminal
via the penetrating electrode by utilizing the first protrusion.
Therefore, progress can be made in size reduction. In addition, by
selecting the area and shape of the first protrusion provided so as
to be continuous with the frame-shaped supporting body main body,
it is possible to easily provide a penetrating electrode with a
large cross-sectional shape. The penetrating electrode is
preferably an under bump metal portion and the outer terminal is
preferably a bump. In this case, by utilizing the first protrusion,
an under bump metal portion can be provided and the bump can be
joined to the top of the under bump metal portion.
In another specific aspect of the electronic component according to
a preferred embodiment of the present invention, the functional
unit located on the substrate includes at least one IDT electrode
and is a surface acoustic wave device. In this case, with a
preferred embodiment of the present invention, it is possible to
provide a surface acoustic wave device that has a reduced size and
in which it is unlikely that leak defects will occur.
A method of manufacturing an electronic component according to a
preferred embodiment of the present invention includes the
following steps: a step of preparing a substrate on one main
surface of which a functional unit is formed, a step of providing a
heat-curable resin on the one main surface of the substrate so as
to surround the functional unit on the one main surface of the
substrate and so as to contain the frame-shaped supporting body
main body, which is separated from the periphery of the substrate
on the inner side, and the first and second protrusions, a step of
stacking a lid member to form a frame-shaped heat-curable resin on
the one main surface side of the substrate with the heat-curable
resin therebetween, a step of completing the frame-shaped
supporting body, and joining the frame-shaped supporting body, the
one main surface of the substrate, and the lid member to one
another by curing the heat-curable resin.
In a certain specific aspect of the method of manufacturing the
electronic device according to a preferred embodiment of the
present invention, the method further includes, after the step of
completing the frame-shaped supporting body, a step of forming a
through hole so as to penetrate through the first protrusion of the
frame-shaped supporting body and the lid member, a step of forming
a penetrating electrode in the through hole, and a step of joining
an outer terminal to an upper end of the penetrating electrode. In
this case, separate from the frame-shaped supporting body main
body, a penetrating electrode can be formed by utilizing the first
protrusion that the frame-shaped supporting body main body is
provided with. Therefore, even if the thickness of the frame-shaped
supporting body main body has only been thinned, the penetrating
electrode can be easily formed. It is preferable that an under bump
metal portion be formed as the penetrating electrode and a bump be
formed as the outer terminal. In this case, an under bump metal
portion can be formed by utilizing the first protrusion, and
therefore the bump can be easily formed on top of the under bump
metal portion.
In another specific aspect of the method of manufacturing the
electronic component according to a preferred embodiment of the
present invention, a surface acoustic wave substrate is prepared on
which a surface acoustic wave element functional unit is formed as
the substrate on which the functional unit is formed, and thus a
surface acoustic wave device is provided. In this case, with a
preferred embodiment of the present invention, it is possible to
provide a surface acoustic wave device in which progress can be
made in size reduction and in which it is unlikely that leak
defects will occur.
According to an electronic component of various preferred
embodiments of the present invention, at the time of forming the
frame-shaped supporting body composed of a heat-curable resin, even
if the frame-shaped supporting body becomes deformed due to curing
shrinkage, since the second protrusion is provided at a portion at
which the first protrusion is continuous with the supporting body
main body, strain in the portion in which the first protrusion and
the supporting body main body are continuous with each other can be
suppressed or prevented. Consequently, the occurrence of gaps
between the supporting body and the lid member can be suppressed or
prevented and as a result, leak defects can be suppressed or
prevented. Therefore, a compact electronic component can be
provided in which leak defects are unlikely to occur and that is
excellent in terms of environmental resistance.
The above and other elements, features, steps, characteristics and
advantages of the present invention will become more apparent from
the following detailed description of the preferred embodiments
with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A and 1B are a front sectional view of a surface acoustic
wave device, which is an example of an electronic component
according to a preferred embodiment of the present invention and a
bottom view of the structure of a portion that will form a single
surface acoustic wave device prior to being divided from a mother
piezoelectric substrate and from which a lid member has been
removed.
FIG. 2A is a plan view of a surface acoustic wave element used in a
preferred embodiment of the present invention, and FIG. 2B is a
schematic plan view in which electrode structures have been removed
from the structure illustrated in FIG. 1B and illustrates only a
frame-shaped supporting body.
FIGS. 3A to 3E are front sectional views for describing a method of
manufacturing a surface acoustic wave device according to a
preferred embodiment of the present invention.
FIGS. 4A to 4E are front sectional views for describing a method of
manufacturing a surface acoustic wave device according to a
preferred embodiment of the present invention.
FIG. 5 is a plan view illustrating a state in which electrodes of
portions that will form a plurality of surface acoustic wave
elements and frame-shaped supporting bodies have been formed on a
mother wafer prepared using a manufacturing method of a preferred
embodiment of the present invention.
FIG. 6 is a schematic plan view illustrating the directions of
strain at the time of heat curing in a portion in which a
frame-shaped supporting body and a first protrusion are continuous
with each other.
FIG. 7 is a schematic plan view for describing the directions of
strain in a first protrusion, a second protrusion and a
frame-shaped supporting body main body in a portion in which a
frame-shaped supporting body and the first protrusion are
continuous with each other.
FIG. 8 is a schematic plan view illustrating only a frame-shaped
supporting body of a surface acoustic wave device according to a
modification of a preferred embodiment of the present
invention.
FIG. 9 is a front sectional view illustrating an example of a
surface acoustic wave device of the related art.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Hereafter, the present invention will be made clear by describing
specific preferred embodiments of the present invention while
referring to the drawings.
In the following preferred embodiments, a WLCSP type surface
acoustic wave device, which is a non-limiting example of an
electronic component, will be described.
FIG. 1A is a front sectional view illustrating an electronic
component 1 according to a preferred embodiment of the present
invention. The electronic component 1 preferably is a WLCSP type
surface acoustic wave device. The electronic component 1 includes a
substrate 2. The substrate 2 preferably is a surface acoustic wave
element substrate and includes a piezoelectric material. As such a
piezoelectric material, a suitable piezoelectric material such as
LiTaO.sub.3, LiNbO.sub.3, or quartz can be used, for example.
Functional units 3 are located on the lower surface of the
substrate 2. The functional units 3, as will be described below,
include IDT electrodes, reflectors, wiring and pad electrodes.
Structures including metal materials and including such functional
units include multilayer conductive films defined by Ti films and
Al--Cu alloy films in the present preferred embodiment. However,
the metal structures located on the substrate 2 may be made of
other metal materials. That is, a suitable metal material such as
Al, Cu, Ti, Pt, Au, Ag, Ni, Cr, Pd or an alloy containing at least
one of these metals can be used, for example.
As illustrated in FIG. 1A, a frame-shaped supporting body 4 is
joined to the lower surface of the substrate 2. The frame-shaped
supporting body 4 preferably has a rectangular or substantially
rectangular frame-shaped configuration. However, the frame-shaped
supporting body 4 may have a frame-shaped configuration other than
a rectangular or substantially rectangular frame-shaped
configuration. The supporting body 4 is preferably composed of a
cured material of heat-curable resin. In this preferred embodiment,
a polyimide-based resin preferably is used as the heat-curable
resin. However, the supporting body 4 may be formed using another
heat-curable resin, for example.
The supporting body 4, as will be described below, is preferably
arranged so as to surround the functional units 3. In addition, a
lid member 5 is located on the lower end of the supporting body 4
so as to close the opening of the supporting body 4. The lid member
5 preferably has a structure formed by stacking a first layer 5a
including an epoxy-based resin and a second layer 5b including a
polyimide-based resin. However, the lid member 5 may be formed of a
single material layer, for example. Furthermore, the lid member 5
can be formed of a suitable insulating material other than the
above-mentioned resins, for example.
As illustrated in FIG. 1A, pad electrodes 6a and 6b are located on
the lower surface of the substrate 2. Protrusions 4b and 4b, which
will be described below, of the supporting body 4 are arranged so
as to cover the pad electrodes 6a and 6b. In addition, in portions
where the protrusions 4b and 4b of the supporting body 4 are
provided, through holes are provided in the supporting body 4.
These through holes penetrate through not only the supporting body
4 but also through the lid member 5.
Under bump metal portions 7a and 7b are provided as penetrating
electrodes inside the through holes. The under bump metal portions
7a and 7b have structures defined by a Ni layer and an Au layer
being stacked one on top of the other in this preferred embodiment.
The materials that define the under bump metal portions 7a and 7b
are not limited to the above-mentioned metals and suitable
conductive materials similar to the materials that can be used to
define the above-described metal structures can be used. In
addition, the under bump metal portions 7a and 7b may include a
single metal.
The upper ends of the under bump metal portions 7a and 7b are
joined to the pad electrodes 6a and 6b. In addition, the lower ends
of the under bump metal portions 7a and 7b are exposed at the lower
surface of the lid member 5. Bumps 8a and 8b made of a
Sn--Ag--Cu-based solder are arranged on the lower surface of the
under bump metal portions 7a and 7b as outer terminals.
The planar shapes of the functional units 3, the supporting body 4,
the under bump metal portions 7a and 7b and so forth of the
electronic component 1 will be described with reference to FIG. 1B.
The electronic component 1, as illustrated in FIG. 5, which will be
referred to below, is obtained by forming the functional units and
supporting bodies of a plurality of electronic components 1 on a
mother substrate 2A and then dividing the mother substrate 2A.
FIG. 1B is a schematic bottom view of a portion of the mother
substrate 2A that corresponds to a single electronic device 1.
Here, a structure in which the lid member 5 and the bumps 8a and 8b
illustrated in FIG. 1A are not provided is illustrated. In
addition, a feeder line 11 is provided around the outer periphery
of the lower surface of a single substrate 2 in FIG. 1B. The feeder
line 11 is ultimately removed when the mother substrate 2A
illustrated in FIG. 5 is divided. Alternatively, the feeder line 11
is not provided in the finally obtained electronic component 1
illustrated in FIG. 1A.
In addition, the front sectional structure illustrated in FIG. 1A
is a front sectional view of the final electronic component 1
corresponding to the portion along the line A-A of FIG. 1B.
As illustrated in FIG. 1B, the feeder line 11 is provided along the
outer periphery of the substrate 2. The feeder line 11 is
preferably formed of the same metal as that with which the
previously mentioned functional units 3 are formed. It is
preferable that the feeder line 11 be formed of the same electrode
material as the wiring and so forth included in the functional
units 3. Thus, the feeder line 11 can be formed at the same time as
the wiring and so forth.
Within a region surrounded by the feeder line 11, the rectangular
or substantially rectangular frame-shaped supporting body 4 is
provided. The supporting body 4 includes a rectangular or
substantially rectangular frame-shaped supporting body main body
4a. In a region surrounded by the supporting body main body 4a, the
above-mentioned functional units 3 are provided. In the functional
units 3, in order to form a surface acoustic wave filter device, a
plurality of longitudinally coupled resonator type surface acoustic
wave filters 9a and one-port-type surface acoustic wave resonators
9b are provided.
The longitudinally coupled resonator type surface acoustic wave
filters 9a and one-port-type surface acoustic wave resonators 9b
are constructed by forming electrode structures such as IDT
electrodes and reflectors on the substrate 2 in accordance with the
functions thereof. The longitudinally coupled resonator type
surface acoustic wave filters 9a and one-port-type surface acoustic
wave resonators 9b are electrically connected to each other via
wiring electrodes 10 and define functional units 3 as surface
acoustic wave filter devices. In preferred embodiments of the
present invention, the electrode structures of the functional units
3 are not particularly limited.
Pad electrodes 6a to 6g are provided to enable electrical
connection to the outside so as to enable electrical connection to
wiring electrodes 10 of the functional units 3. The pad electrodes
6a to 6g are indicated by broken lines in FIG. 1B. For example, as
with the pad electrodes 6a and 6b, this is because the pad
electrodes 6a and 6b are covered by the first protrusions 4b of the
supporting body 4. In addition, as is clear from the portions where
the pad electrodes 6a and 6b are provided, the under bump metal
portions 7a and 7b are provided in the first protrusions 4b of the
supporting body 4, which cover the pad electrodes 6a and 6b.
The first protrusions 4b of the supporting body 4 are located in
portions where the pad electrodes 6a and 6b are provided as
described above. More specifically, in portions in which the pad
electrodes 6a, 6b, 6c, 6d and 6g, among the pad electrodes 6a to
6g, which are provided at positions along the outer periphery of
the substrate 2, are disposed, the first protrusions 4b are
provided so as to protrude toward the inside from the outer
periphery of the supporting body main body 4a of the supporting
body 4, that is, toward the inside of the opening surrounded by the
supporting body 4. The first protrusions 4b are portions that cover
the pad electrodes 6a to 6d, and 6g and form through holes to
define the under bump metal portions 7a and 7b. Therefore, in this
preferred embodiment, the first protrusions 4b preferably have a
rectangular or substantially rectangular shape in plan view and are
of a certain area.
FIG. 2A is a plan view illustrating a state in which the supporting
body 4, the under bump metal portions 7a and 7b and so forth have
been removed from the structure illustrated in FIG. 1B. That is,
FIG. 2A is a bottom view illustrating a structure in which the
functional units 3, the pad electrodes 6a to 6g and the feeder line
11 located on the substrate 2 are formed. In addition, FIG. 2B is a
plan view illustrating the supporting body 4 and supporting columns
12a and 12b, which include a heat curable resin and located on
portions where the pad electrodes 6e and 6f are provided in FIG.
1B. The supporting columns 12a and 12b are located on portions
where the pad electrodes 6e and 6f are provided and have a
cylindrical or substantially cylindrical shape. In addition,
through holes are provided in the supporting columns 12a and 12b.
Under bump metal portions are provided inside the through
holes.
A method has also been considered in which the first protrusions 4b
are not provided, when forming the portions in which the under bump
metal portions 7a and 7b are formed in the supporting body 4. That
is, if the width of the supporting body 4, that is, the width of
the supporting body main body 4a of the supporting body 4 is made
large, the under bump metal portions can be provided at desired
positions in the supporting body main body 4a. However, in this
structure, the area of the opening surrounded by the supporting
body main body 4a becomes smaller. Therefore, it becomes difficult
to make progress in size reduction.
Consequently, as in this preferred embodiment, usually, the width
of the supporting body main body 4a having a rectangular or
substantially rectangular shape is made small and the first
protrusions 4b are provided inside the supporting body main body
4a. Thus, the area of the portion surrounded by the supporting body
main body 4a can be made large.
However, when the first protrusions 4b are provided, strain, or
deformation is generated when the heat-curable resin of the
supporting body 4 undergoes curing shrinkage. Due to this strain,
there has been a risk of leak defects occurring.
One of the unique features of this preferred embodiment is that
second protrusions 4c are provided in addition to the first
protrusions 4b in order to prevent the occurrence of leak defects.
The second protrusions 4c are provided in portions in which the
first protrusions 4b are provided in the supporting body 4, so as
to extend from the supporting body main body 4a toward the side
opposite to that of the first protrusions 4b, that is, toward the
outside. Thus, the stress, or deformation generated during curing
shrinkage in portions where the supporting body main body 4a and
the first protrusions 4b are continuous with each other is reduced.
Consequently, leak defects can be prevented. This point will be
explained while referring to FIG. 6 and FIG. 7.
FIG. 6 is a schematic view of the structure of a comparative
example in which the first protrusions 4b are continuous with the
supporting body main body 4a and the second protrusions are not
provided. In the case where the supporting body 4 is composed of a
heat-curable resin and is heat cured, curing shrinkage occurs. The
directions of stress at this time are indicated by arrows E in FIG.
6. The first protrusions 4b having a rectangular planar shape are
deformed as the rectangular shape undergoes shrinkage. In addition,
in the band-shaped supporting body main body 4a, curing shrinkage
progresses such that the width thereof becomes smaller. Therefore,
in portions where the supporting body main body 4a and the first
protrusions 4b are continuous with each other, the outer periphery
of the supporting body main body 4a attempts to shift toward the
inside as indicated by the arrow B. Thus, strain and twisting
occurs in the supporting body main body 4a. As a result, a gap is
generated when the lid member 5 is joined to the supporting body 4
and therefore a leak defect occurs.
In contrast, as illustrated in FIG. 7, in a structure in which the
second protrusions 4c are provided, shrinkage progresses in the
directions indicated by the arrows C in the second protrusions 4c
during curing shrinkage. Consequently, in portions in which the
supporting body main body 4a and the first protrusions 4b are
continuous with each other, it is unlikely that deformation of a
kind indicated by the arrows B in FIG. 6 will occur. Consequently,
leak defects can be prevented.
In FIG. 7, in portions in which the first protrusions 4b and the
second protrusions 4c are continuous with each other, the second
protrusions 4c face in a direction toward the outside with respect
to the supporting body main body 4a, and the second protrusions 4c
do not necessarily have to be exactly formed at the positions
illustrated in FIG. 7. For example, one end portion of the second
protrusion 4c, as illustrated by the one dot chain line D, may be
shifted in a lateral direction from a position at which an edge 4b1
of the first protrusion 4b is continuous with the supporting body
main body 4a. Also in such a case, strain is generated in a similar
manner to stress illustrated by arrows C. Therefore, leak defects
can be effectively prevented. Therefore, the second protrusions 4c
may be provided so as to protrude toward the outside from the
supporting body main body 4a in the vicinity of portions in which
the first protrusions 4b are continuous with the supporting body
main body 4a. In addition, so long as the shrinkage strain
indicated by the arrows C can be caused to be generated, the planar
shape of the second protrusions 4c is not limited to a shape such
as a rectangle.
In this preferred embodiment, the width of the frame-shaped
supporting body main body 4a preferably is about 20 .mu.m, for
example. The first protrusions 4b preferably have a square shape of
approximately 116 .mu.m.times.116 .mu.m, for example. In addition,
the protruding length of the second protrusions 4c preferably is
about 30 .mu.m or more, for example. The protruding length is the
length of the second protrusions 4c in the direction in which the
second protrusions 4c protrude from the outer periphery of the
supporting body main body 4a toward the outside. In this preferred
embodiment, the protruding length is the protruding length of the
second protrusions 4c in portions orthogonal to the outer periphery
of the supporting body main body 4a. However, the width of the
supporting body main body 4a, and the dimensions of the first and
second protrusions 4b and 4c are not particularly limited.
Of course, the area and the shape of the second protrusions 4c may
be suitably set in accordance with the rate of curing shrinkage and
the curing temperature of the heat-curable resin forming the
supporting body 4.
Next, a method of manufacturing the electronic component 1 of a
preferred embodiment of the present invention will be described
with reference to FIGS. 3A to 5.
As illustrated in FIG. 3A, first, the mother substrate 2A is
prepared. Next, a plurality of the functional units 3, the pad
electrodes 6a and 6b, and so forth, and, although not illustrated
in FIG. 3B, the feeder line 11 is formed on the mother substrate 2A
by using a thin film fine processing technology.
The feeder line 11 will be described below in detail.
Next, as illustrated in FIG. 3C, a photosensitive epoxy-based resin
is applied so as to cover the entirety of the upper surface of the
mother substrate 2A. Thus, an epoxy-based resin layer 4A is
formed.
Next, as illustrated in FIG. 3D, the epoxy-based resin layer 4A is
patterned using a photolithographic method. Thus, as illustrated in
FIG. 3D, the supporting body 4 is formed. In FIG. 3D, portions in
which the first protrusions 4b of the supporting body 4 are
provided are illustrated, but the supporting body main body 4a, the
second protrusions 4c, and the supporting columns 12a and 12b and
so forth are also formed in the same process. Naturally, at this
stage, the epoxy-based resin has not yet been cured with heat.
FIG. 5 is a plan view of the mother substrate 2A in a state where
the process of FIG. 3D has been completed. The above-mentioned
feeder line 11 will be described with reference to FIG. 5. The
feeder line 11 is formed in a region in which a plurality of
electronic components included in the mother substrate 2A are
formed. In this preferred embodiment, a plurality of electronic
components are formed in a matrix pattern. Therefore, the feeder
line 11 preferably has a lattice-shaped configuration. The feeder
line 11 is removed when a dicing process, which will be described
below, is performed.
In addition, in order to reduce damage caused by a laser process,
which will be described below, the thickness of the pad electrodes
6a to 6g is made to be larger than that of the other metal
structures such as the IDT electrodes and wiring electrodes.
Specifically, it is preferable that the thickness of the Al--Cu
alloy be about 2.3 .mu.m or more, for example.
Next, as illustrated in FIG. 3E, the first and second layers 5a and
5b of the lid member 5 are stacked one on top of the other by
laminating a heat-curable resin using a lamination process. Thus,
the opening surrounded by the supporting body 4 is closed.
At the time of lamination of the lid member 5, it is preferable
that the first layer 5a be in a non-cured state and the second
layer 5b be in a cured state in advance. The second layer 5b is
cured with heat or light, and such that warping of the lid member 5
caused by the cured second layer 5b is suppressed or prevented.
Next, as illustrated in FIG. 3E, after the lamination process has
been performed, the entire body is heated. Thus, the supporting
body 4 and the first layer 5a are cured. As a result, the first
layer 5a and the supporting body 4 are joined together and a cavity
that the functional units 3 of the electronic component 1 face is
formed. At the time of curing, as described above, the second
protrusions 4c have been provided and therefore it is not likely
that deformation will occur in portions where the first protrusions
4b and the supporting body main body 4a are continuous with each
other. Therefore, it is possible to form a cavity that is excellent
in terms of sealability and in which it is unlikely that a leak
defect will occur.
The supporting body 4 and the first layer 5a are preferably cured
in the same heat curing process. Consequently, the heat-curable
resin forming the first layer 5a and the heat-curable resin forming
the supporting body 4 are preferably resins that are cured in the
same temperature range. More preferably, it is preferable that the
first layer 5a and the supporting body 4 be formed of the same
heat-curable resin. Thus, the supporting body 4 and the first layer
5a can be cured by being heated in the same temperature range and
the heating process can be simplified. In addition, when the same
resin is used, the strength of the bond between the first layer 5a
and the supporting body 4 can be effectively increased.
Next, as illustrated in FIG. 4A, through holes are formed so as to
penetrate through the lid member 5 by using for example a laser
process. In FIG. 4A, a state is illustrated in which through holes
are formed so as to penetrate through the lid member 5, and
furthermore the through holes are formed so as to also penetrate
through the supporting body 4 by performing a laser process. Thus,
the pad electrodes 6a and 6b are exposed through the through
holes.
Next, as illustrated in FIG. 4B, the under bump metal portions 7a
and 7b are formed in the through holes. When forming the under bump
metal portions 7a and 7b, in this preferred embodiment, a Ni layer
is formed in the through holes and then an Au layer is formed by
electroplating.
Next, as illustrated in FIG. 4C, the bumps 8a and 8b, which are
composed of solder and mentioned above, are formed on the under
bump metal portions 7a and 7b.
Then, as illustrated in FIG. 4D and FIG. 5, cutting is performed
along division lines F indicated by the broken lines by performing
dicing or the like. As a result, as illustrated in FIG. 4E, the
electronic component 1 can be obtained.
The above-described manufacturing method is just an example of a
method of manufacturing the electronic component 1, and the
electronic component 1 can be manufactured using another
manufacturing method.
As described above, in the electronic component 1 of the present
preferred embodiment, the second protrusions 4c are provided, and
as a result it is unlikely that gaps will occur, which would cause
leak defects, between the supporting body 4 and the lid member 5
and between the supporting body 4 and the substrate 2. The
electronic component 1 of the above-described preferred embodiment
and an electronic component of a comparative example formed in the
same manner except that the second protrusions 4c were omitted from
the structure of the present preferred embodiment were
manufactured. The percentage of leak defects in electronic
components of the preferred embodiment and the comparative example
were measured in a gross leak test. The result of the test for the
comparative example was 1.56%. In contrast, in the example of a
preferred embodiment of the present invention, the percentage of
leak defects was 0.03% and therefore the percentage of leak defects
was able to be lowered by a significant amount.
In the present preferred embodiment, the first protrusions 4b are
provided in order to form the under bump metal portions 7a and 7b,
but may instead be provided in order to simply reinforce the
supporting body main body 4a.
FIG. 8 is a schematic plan view of the frame-shaped supporting body
4 of a surface acoustic wave device according to a modification of
a preferred embodiment of the present invention. FIG. 8 corresponds
to FIG. 2B, which illustrates a preferred embodiment of the present
invention.
This modification is the same as the preferred embodiment of the
present invention shown in FIG. 2B except for the structure of the
frame-shaped supporting body 4. Therefore, in FIG. 8, portions the
same as those in FIG. 2B are denoted by the same reference
symbols.
As illustrated in FIG. 8, in this modification, the first
protrusions 4b are also provided inside the supporting body main
body 4a at corner portions of the frame-shaped supporting body 4.
Furthermore, in addition to the first protrusions 4b, the second
protrusions 4c are provided. Thus, similarly to as in the case of
the preferred embodiment illustrated in FIG. 2B, leak defects are
prevented.
Furthermore, in this modification, a first protrusion 4b extends
from one long edge of the supporting body main body 4a so as to
reach another long edge on the opposite side in the center of the
length direction of the frame-shaped supporting body 4. That is,
the first protrusion 4b is arranged so as to partition the space
between the two long edges of the supporting body main body 4a.
Thus, a transmission filter can be provided on one side of the
first protrusion 4b and a reception filter can be provided on the
other side of the first protrusion 4b functioning as a partition.
Thus, the first protrusion 4b may be arranged so as to function as
a partition that partitions the frame-shaped supporting body 4.
In each of the above-described preferred embodiments, description
has been given of a surface acoustic wave device, but the present
invention is not limited to a surface acoustic wave device and can
generally be applied to any electronic components having a sealed
cavity.
While preferred embodiments of the present invention have been
described above, it is to be understood that variations and
modifications will be apparent to those skilled in the art without
departing from the scope and spirit of the present invention. The
scope of the present invention, therefore, is to be determined
solely by the following claims.
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