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DESCRIPTION JP2014192533

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DESCRIPTION JP2014192533
Abstract: To provide a microphone capable of achieving a reduction in height while protecting a
diaphragm from the external environment. A microphone (1) includes a plate substrate (10)
having a main surface (10a), an acoustic sensor mounted on the main surface (10a), and a circuit
element (30) for processing a signal output from the acoustic sensor. The acoustic sensor
includes a sensor substrate 20. The sensor substrate 20 has a first surface 20 b facing the plate
substrate 10 and a second surface 20 a opposite to the first surface 20 b. The sensor substrate
20 is formed with a hollow portion 28 penetrating from the first surface 20 b to the second
surface 20 a. In the plate substrate 10, a through hole 18 which penetrates the plate substrate
10 in the thickness direction and communicates with the hollow portion 28 is formed. When
viewed in the thickness direction of the plate substrate 10, the through holes 18 overlap the
sensor substrate 20. [Selected figure] Figure 1
マイクロフォン
[0001]
The present invention relates to a microphone, and more particularly to a microphone in which
an acoustic sensor is mounted on a major surface of a base substrate.
[0002]
Microphones are used in various devices such as mobile phones and IC recorders.
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1
For example, in U.S. Pat. No. 7,763,972 (Patent Document 1), an acoustic sensor and a circuit
element are stacked, the acoustic sensor has a thin film functioning as a sensor unit, and the
circuit element corresponds to the thin film Discloses a microphone in which a cavity is formed
at the position where it is located.
[0003]
In recent years, in the microphone, further miniaturization has been required, and in particular, a
reduction in height to reduce the height of the entire microphone is required. If the height of the
acoustic sensor is reduced for the purpose of reducing the height of the microphone described in
U.S. Pat. No. 7,763,972 (Patent Document 1), the distance between the sound hole
communicating with the outside of the microphone and the sensor portion decreases. Therefore,
there is a problem that the foreign substance entering the inside of the microphone via the sound
hole deteriorates the acoustic characteristics of the microphone, or the compressed air flowing
into the inside of the microphone via the sound hole easily damages the sensor unit.
[0004]
To address this problem, U.S. Patent Application Publication No. 2007/0278601 (Patent
Document 2) discloses a configuration for preventing external interference by bending an
acoustic port inside a substrate.
[0005]
U.S. Pat. No. 7,763,972 U.S. Patent Application Publication No. 2007/0278601
[0006]
In the device described in U.S. Patent Application Publication No. 2007/0278601 (Patent
Document 2), the substrate needs a thickness to form an acoustic port with a curved shape
inside.
Therefore, there is a limit in reducing the thickness of the substrate, and there is a problem that
it is difficult to reduce the overall height of the device.
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[0007]
The present invention has been made in view of the above problems, and its main object is to
provide a technology capable of achieving a reduction in the height of a microphone while
protecting a thin film diaphragm from an external environment.
[0008]
A microphone according to the present invention includes a base substrate having a main
surface, an acoustic sensor mounted on the main surface, and a circuit element for processing a
signal output from the acoustic sensor.
The acoustic sensor includes a sensor substrate and a movable electrode.
The sensor substrate has a first surface facing the base substrate and a second surface opposite
to the first surface. The sensor substrate is formed with a hollow portion penetrating from the
first surface to the second surface. The movable electrode covers the cavity from the second
surface side. The base substrate is formed with a through hole which penetrates the base
substrate in the thickness direction and communicates with the hollow portion. When viewed in
the thickness direction of the base substrate, the through holes overlap the sensor substrate.
[0009]
Preferably, the microphone further comprises an adhesive layer. The adhesive layer is interposed
between the main surface and the first surface, and bonds the sensor substrate to the base
substrate. A hollow region not provided with an adhesive layer is formed between the main
surface and the first surface. The through hole communicates with the cavity through the hollow
region.
[0010]
Preferably, a recess in which at least one of the main surface and the first surface is recessed is
formed, and the through hole communicates with the cavity through the recess. The adhesive
cured product obtained by curing the liquid adhesive may be accommodated in a part of the
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inside of the recess.
[0011]
Preferably, the base substrate has a protrusion that protrudes from the main surface, and the
sensor substrate is mounted on the protrusion. The protrusion may protrude from the main
surface along the periphery of the through hole in the main surface.
[0012]
Preferably, the microphone further includes an intervening member penetrating the adhesive
layer and interposed between the main surface and the first surface.
[0013]
Preferably, the through hole is formed along the periphery of the cavity in the first surface.
Preferably, a plurality of through holes are formed in the base substrate.
[0014]
Preferably, the circuit element is laminated to the acoustic sensor.
[0015]
According to the present invention, the diaphragm can be protected from the external
environment, and the height of the microphone can be reduced.
[0016]
FIG. 1 is a cross-sectional view showing an outline of a configuration of a microphone according
to Embodiment 1.
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It is sectional drawing of the microphone of Embodiment 1 which follows the II-II line shown in
FIG.
FIG. 8 is a cross-sectional view showing an outline of a configuration of a microphone according
to Embodiment 2. It is sectional drawing of the microphone of Embodiment 2 which follows the
IV-IV line shown in FIG. FIG. 13 is a cross-sectional view showing an outline of a configuration of
a microphone according to a third embodiment. It is sectional drawing of the microphone of
Embodiment 3 which follows the VI-VI line shown in FIG. FIG. 16 is a cross-sectional view
showing an outline of a configuration of a microphone according to a fourth embodiment. FIG.
18 is a cross-sectional view showing an outline of a configuration of a microphone according to a
fifth embodiment. FIG. 21 is a cross-sectional view showing the outline of the configuration of a
microphone according to a sixth embodiment; FIG. 21 is a cross-sectional view showing the
outline of the configuration of a microphone according to a seventh embodiment; FIG. 21 is a
cross-sectional view showing the outline of the configuration of a microphone according to an
eighth embodiment; FIG. 21 is a cross-sectional view showing the outline of the configuration of
a microphone according to a ninth embodiment; FIG. 21 is a cross-sectional view showing the
outline of the configuration of a microphone according to a tenth embodiment; It is sectional
drawing of the microphone of Embodiment 10 which follows the XIV-XIV line shown in FIG. FIG.
24 is a cross-sectional view showing an outline of a configuration of a microphone according to
an eleventh embodiment. It is sectional drawing of the microphone of Embodiment 11 which
follows the XVI-XVI line shown in FIG. FIG. 24 is a cross-sectional view showing an outline of a
configuration of a microphone according to a twelfth embodiment; FIG. 18 is a cross-sectional
view of the microphone of Embodiment 12 taken along the line XVIII-XVIII shown in FIG. 17. FIG.
35 is a cross-sectional view showing the outline of the configuration of a microphone according
to a thirteenth embodiment; FIG. 24 is a cross-sectional view showing the outline of the
configuration of a microphone according to a fourteenth embodiment; FIG. 51 is a cross-sectional
view showing the outline of the configuration of a microphone according to a fifteenth
embodiment;
[0017]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings. In the drawings, the same or corresponding portions are denoted by the same
reference characters and description thereof will not be repeated.
[0018]
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First Embodiment FIG. 1 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a first embodiment. FIG. 2 is a cross-sectional view of the microphone
1 of the first embodiment, taken along the line II-II shown in FIG. Referring to FIG. 1, microphone
1 is a MEMS microphone manufactured using MEMS (Micro Electro Mechanical System)
technology, and an acoustic sensor (microchip) mounted on plate substrate 10 and plate
substrate 10. And the circuit element 30 stacked on the acoustic sensor.
[0019]
The plate substrate 10 is the base substrate in the first embodiment, and is formed in a flat plate
shape. Plate substrate 10 has a main surface 10a and a connection surface 10b opposite to main
surface 10a. The acoustic sensor and circuit element 30 constituting the microphone 1 are
disposed on the main surface 10 a side of the plate substrate 10.
[0020]
The plate substrate 10 has a conductive layer 12 formed so as to be exposed to the main surface
10 a and an external connection terminal 14 stacked on the connection surface 10 b. When the
microphone 1 is mounted on the mother substrate, the external connection terminal 14 is
electrically connected to the connection terminal on the mother substrate side, whereby power
supply to the microphone 1 and communication of control signals are performed.
[0021]
Plate substrate 10 is formed of a flat multilayer wiring substrate, and in addition to conductive
layer 12 and external connection terminal 14 shown, a conductive layer (not shown) extending in
the surface direction on the surface and the inside of plate substrate 10 and Via electrodes
extending in the thickness direction are formed. The conductive layer 12 is electrically connected
to the external connection terminal 14 via a via electrode formed inside the plate substrate 10.
Here, the plane direction is a direction in which the main surface 10 a and the connection surface
10 b of the plate-shaped plate substrate 10 extend, and is a direction orthogonal to the thickness
direction of the plate substrate 10. In FIG. 1, the vertical direction in the drawing is the thickness
direction of the plate substrate 10, and the horizontal direction in the drawing is the surface
direction.
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[0022]
The plate substrate 10 may be formed of a copper-clad laminate, a glass epoxy substrate, a
ceramic substrate, a plastic substrate, a metal substrate, a carbon nanotube substrate, or a
composite substrate of these, in addition to the multilayer wiring substrate.
[0023]
An acoustic sensor is mounted on the main surface 10 a of the plate substrate 10.
The acoustic sensor mainly includes a sensor substrate 20, a diaphragm 24 and a back plate 25.
[0024]
The sensor substrate 20 is formed of a silicon substrate. The sensor substrate 20 is formed in a
flat plate shape, and has a first surface 20 b and a second surface 20 a. The first surface 20 b and
the second surface 20 a constitute both main surfaces of the sensor substrate 20. The first
surface 20 b is one of the main surfaces of the sensor substrate 20 and is opposed to the main
surface 10 a of the plate substrate 10. The second surface 20 a is the other main surface of the
sensor substrate 20 opposite to the first surface 20 b.
[0025]
An adhesive layer 40 is disposed between the first surface 20 b of the sensor substrate 20 and
the main surface 10 a of the plate substrate 10. Adhesive layer 40 is interposed between main
surface 10 a and first surface 20 b. The first surface 20 b of the sensor substrate 20 is bonded to
the main surface 10 a of the plate substrate 10 using an adhesive layer 40. The sensor substrate
20 is fixed to the main surface 10 a of the plate substrate 10 by the adhesive layer 40, whereby
the acoustic sensor is mounted on the main surface 10 a of the plate substrate 10.
[0026]
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The adhesive layer 40 may be formed by any one or a combination of an adhesive tape, an
adhesive film, a liquid adhesive, and a conductive adhesive. When the adhesive layer 40 is
formed using a liquid adhesive such as a resin, it is desirable to adjust the dropping position and
the dropping amount in consideration of flowing and spreading after applying the liquid
adhesive. Further, the adhesive layer 40 may be formed by forming a metal film on each of the
main surface 10 a of the plate substrate 10 and the first surface 20 b of the sensor substrate 20
and joining them.
[0027]
The sensor substrate 20 has a cavity 28 formed therein. The hollow portion 28 is formed to
reach from the first surface 20 b to the second surface 20 a, and penetrates the sensor substrate
20 in the thickness direction (vertical direction in FIG. 1). The cavity 28 is hollow. The inner
peripheral surface of the hollow portion 28 is formed as a vertical surface extending in the
thickness direction of the sensor substrate 20. The inner circumferential surface of the hollow
portion 28 may be formed as a tapered surface which is inclined with respect to the thickness
direction of the sensor substrate 20, and is formed by a combination of a plurality of tapered
surfaces having different inclination angles with respect to the thickness direction of the sensor
substrate 20. It may be
[0028]
The diaphragm 24 is formed in a thin film shape and has conductivity. Preferably, the diaphragm
24 is formed of a doped poly / crystalline silicon thin film. The diaphragm 24 is attached to the
second surface 20 a of the sensor substrate 20 using an anchor (not shown). The diaphragm 24
is disposed so as to cover the cavity 28 from the second surface 20 a side. The diaphragm 24 has
an edge portion supported by the second surface 20 a of the sensor substrate 20 and a central
portion covering the cavity 28. The central portion of the diaphragm 24 is disposed slightly
floating from the second surface 20a of the sensor substrate 20, and vibrates in response to
acoustic vibration. The diaphragm 24 has a function as a movable electrode of the acoustic
sensor.
[0029]
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The back plate 25 is disposed on the second surface 20 a side of the sensor substrate 20 so as to
face the diaphragm 24, and is fixed to the second surface 20 a of the sensor substrate 20 directly
or through any layer. There is. The back plate 25 has an insulating layer, preferably a fixed film
of silicon nitride / non-doped silicon, and a fixed electrode of a conductive layer, preferably a
poly / crystalline silicon thin film / metal film doped with impurities. ing. The fixed electrode is
provided on the surface of the fixed film on either the side facing the diaphragm 24 or the side
not facing it. The back plate 25 has a lid-like shape that covers the diaphragm 24.
[0030]
An air gap 26 is formed between the back plate 25 and the diaphragm 24. The back plate 25
covers the cavity 28 at a position away from the sensor substrate 20 with respect to the
diaphragm 24. The back plate 25 is perforated with a large number of acoustic holes for avoiding
damping in the air gap 26. These acoustic holes are preferably formed so as to increase the
aperture ratio as long as the back plate can ensure rigidity.
[0031]
The fixed electrode of the back plate 25 faces the diaphragm 24, which is a movable electrode, to
form a capacitor. When a sound wave is incident on the acoustic sensor and the diaphragm 24
vibrates due to the sound pressure, the capacitance between the diaphragm 24 and the fixed
electrode of the back plate 25 changes. In the acoustic sensor according to the present
embodiment, the acoustic vibration (change in sound pressure) sensed by the diaphragm 24
becomes a change in capacitance between the diaphragm 24 and the fixed electrode, and is
output as an electrical signal. . At least a pair of microphone terminals 22 are provided on the
second surface 20 a of the sensor substrate 20. The microphone terminal 22 outputs a detection
signal according to the change in capacitance between the diaphragm 24 and the fixed electrode.
[0032]
The acoustic sensor is not limited to the above-described configuration, and may have another
configuration as long as the diaphragm 24 as the movable electrode and the fixed electrode are
disposed to face each other. For example, the positions of the diaphragm 24 and the back plate
25 in the thickness direction of the sensor substrate 20 may be interchanged with each other.
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The diaphragm 24 may be suspended from the back plate 25 and supported by the back plate
25. In the case of a modification in which the fixed electrode is provided on the sensor substrate
20 or other substrates, the back plate 25 can be omitted.
[0033]
The circuit element 30 is mounted on the second surface 20 a of the sensor substrate 20 and is
stacked on the acoustic sensor. Circuit element 30 may be, for example, an application specific
integrated circuit element (ASIC). The circuit element 30 has a shape in which an angular Cshape is faced down, whereby a hollow space 38 is formed between the circuit element 30 and
the second surface 20 a of the sensor substrate 20. The diaphragm 24 and the back plate 25
provided on the second surface 20 a of the sensor substrate 20 are accommodated in the space
38.
[0034]
A conductive layer 32 is formed on the circuit element 30. The conductive layer 32 is provided
on the surface of the circuit element 30 on the side away from the sensor substrate 20. The
microphone terminal 22 disposed on the second surface 20 a of the sensor substrate 20 and the
conductive layer 32 formed on the circuit element 30 are connected by a bonding wire 62. The
conductive layer 12 formed on the plate substrate 10 and the conductive layer 32 formed on the
circuit element 30 are connected by a bonding wire 64. A detection signal of the acoustic sensor
is output from the microphone terminal 22 and input to the circuit element 30 via the conductive
layer 12. After predetermined signal processing is performed in the circuit element 30, the
detection signal is output from the circuit element 30 and output to the external connection
terminal 14 via the conductive layer 12.
[0035]
The acoustic sensor and the circuit element 30 sequentially stacked on the main surface 10 a of
the plate substrate 10 are entirely covered and protected by a protective layer 50. The protective
layer 50 is formed of an insulating resin. The bonding wires 62 and 64 are disposed inside the
protective layer 50 and protected by the protective layer 50. The plate substrate 10 and the
protective layer 50 form a housing of the microphone 1.
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[0036]
Referring to FIGS. 1 and 2, in plate substrate 10, a through hole 18 is formed to penetrate plate
substrate 10 in the thickness direction. Between the main surface 10 a of the plate substrate 10
and the first surface 20 b of the sensor substrate 20, a hollow region 48 in which the adhesive
layer 40 is not provided is formed. When viewed in the thickness direction of the plate substrate
10 and the sensor substrate 20 (that is, in the vertical direction in FIG. 1 and in the direction
perpendicular to the sheet of FIG. 2), the through holes 18 overlap the sensor substrate 20 and
the hollow region 48 also overlaps with the sensor substrate 20, and the through holes 18 and
the hollow regions 48 overlap with each other. The through hole 18 and the hollow area 48
communicate with each other. The hollow region 48 is formed adjacent to the cavity 28, and the
hollow region 48 is in communication with the cavity 28. The through hole 18 communicates
with the cavity 28 through the hollow region 48.
[0037]
The through hole 18 and the hollow area 48 form an acoustic port for introducing acoustic
vibration to the acoustic sensor. A sound is introduced into the interior of the microphone 1 via
the acoustic port. The microphone 1 has a front chamber, which is a hollow space closer to the
acoustic port with respect to the diaphragm 24, and a back chamber, which is a hollow space
away from the acoustic port with respect to the diaphragm 24. The front chamber and the back
chamber are respectively defined by the diaphragm 24 as a boundary. The cavity 28 has a
function as a front chamber of the microphone 1. The space 38 has a function as a back chamber
of the microphone 1.
[0038]
The acoustic port includes a through hole 18 formed in the plate substrate 10. The acoustic port
also includes a hollow area 48 surrounded by the major surface 10 a of the plate substrate 10,
the first surface 20 b of the sensor substrate 20 and the adhesive layer 40. Since the through
holes 18 extend in the thickness direction of the plate substrate 10 and the hollow regions 48
extend in the surface direction along the main surface 10 a of the plate substrate 10, the
extending direction of the through holes 18 and the hollow regions 48. The directions of
extension of the cross each other. Therefore, the acoustic port constituted by the through hole 18
and the hollow area 48 is formed in a bent shape.
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[0039]
The through holes 18 are round holes having a circular shape that appears in the cross section of
the plate substrate 10 parallel to the main surface 10 a. When viewed in the thickness direction
of the plate substrate 10, the hollow region 48 has an area larger than that of the through hole
18. The entire opening of the through hole 18 in the main surface 10 a of the plate substrate 10
is exposed to the hollow region 48. The projection of the sensor substrate 20 on the main surface
10a along the thickness direction of the plate substrate 10 overlaps all the openings where the
through holes 18 open in the main surface 10a.
[0040]
When the through hole 18 is viewed from the connection surface 10 b side along the extending
direction of the through hole 18, the first surface 20 b of the sensor substrate 20 is visually
recognized in the entire inside of the through hole 18. The acoustic port has a curved shape so
that the cavity 28 formed in the sensor substrate 20 and the diaphragm 24 disposed covering
the cavity 28 can not be seen directly from the connection surface 10 b of the plate substrate 10.
Have.
[0041]
According to the microphone 1 of the first embodiment described above, the acoustic port for
introducing acoustic vibration into the cavity 28 functioning as the front chamber is formed in a
bent shape. Therefore, the diaphragm 24 is disposed at a position not exposed to the external
environment. In this way, it is possible to prevent foreign matter or compressed air from entering
the cavity 28 and reaching the diaphragm 24 via the acoustic port, so damage to the diaphragm
24 can be reduced. Since the arrival of the foreign matter to the diaphragm 24 can be
suppressed, the foreign matter can be suppressed from affecting the vibration of the diaphragm
24. Therefore, the thin film diaphragm 24 can be protected from the external environment.
[0042]
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12
The acoustic port having a bent shape has a through hole 18 penetrating the plate substrate 10,
and a hollow region 48 surrounded by the main surface 10a of the plate substrate 10 and the
first surface 20b of the sensor substrate 20 and the adhesive layer 40. It is formed by Thus, it is
not necessary to form a curved through hole inside the plate substrate 10, and the thickness of
the plate substrate 10 can be reduced. As a result, since the size in the height direction of the
microphone 1 can be reduced, the height of the microphone 1 can be reduced. Since the
processing of the through holes 18 linearly extending in the thickness direction of the plate
substrate 10 is easy, productivity can be greatly improved as compared with the case where the
curved through holes are formed inside the plate substrate 10.
[0043]
The front chamber of the microphone 1 is formed by a cavity 28 formed in the sensor substrate
20. By suppressing damage to the diaphragm 24 due to foreign matter or compressed air
invading through the acoustic port, the diaphragm 24 can be disposed close to the main surface
10 a of the plate substrate 10. Thereby, the thickness of the sensor substrate 20 can be reduced,
and the height reduction of the sensor substrate 20 can be achieved, so that the height reduction
of the microphone 1 can be realized. As a result of reducing the height of the sensor substrate
20, the volume of the front chamber can be reduced, so that the frequency characteristics of the
microphone 1 can be improved particularly in a high frequency range, and the performance of
the microphone 1 can be improved.
[0044]
On the other hand, the back chamber of the microphone 1 is formed by the space 38 between
the sensor substrate 20 and the circuit element 30. The shape and size of the circuit element 30
can be arbitrarily adjusted, and by increasing the dimension in the height direction of the circuit
element 30 having a C-shaped upside, the volume of the space 38 can be increased and the
capacity of the back chamber is increased Can.
[0045]
As a result, the air in the back chamber acts as an air spring to inhibit the vibration of the
diaphragm 24, and the diaphragm 24 can freely vibrate when the sound wave is introduced into
the microphone 1. Therefore, the signal noise ratio (SNR) can be improved to improve the
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sensitivity of the microphone 1. In addition, since the volume of the back chamber can be
increased, it is possible to improve the frequency characteristics of the microphone 1 particularly
in the low frequency range, and to improve the performance of the microphone 1.
[0046]
In terms of the characteristics of the microphone 1, the acoustic port is advantageously larger in
diameter and smaller in length. The acoustic port of the present embodiment includes a hollow
area 48, and the hollow area 48 becomes a part of the path of sound introduced to the
microphone 1. The hollow region 48 is formed by making a cavity corresponding to the
thickness of the adhesive layer 40 between the plate substrate 10 and the sensor substrate 20.
That is, the diameter of the hollow region 48 is determined by the thickness of the adhesive layer
40. Therefore, by making the diameter of the through hole 18 formed in the plate substrate 10
sufficiently large and making the thickness of the adhesive layer 40 sufficiently large, acoustic
performance equal to or better than that of the conventional microphone 1 is sufficiently made.
It can be secured. For example, an adhesive layer 40 having a thickness of 10 μm or more may
be formed.
[0047]
Further, as shown in FIG. 1, the circuit element 30 is stacked on the acoustic sensor. Due to this
stacked structure, the height dimension of the microphone 1 is increased. Therefore, by adopting
the acoustic port of the present embodiment and reducing the thickness of the plate substrate 10
and the sensor substrate 20, the effect of reducing the height of the microphone 1 can be more
remarkably obtained. That is, the acoustic port according to the present embodiment can be
particularly suitably applied to the microphone 1 in which the acoustic sensor and the circuit
element are stacked.
[0048]
Second Embodiment FIG. 3 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a second embodiment. FIG. 4 is a cross-sectional view of the
microphone 1 of the second embodiment, taken along the line IV-IV shown in FIG. The
microphone 1 of the second embodiment is different from that of the first embodiment in the
shape of the acoustic port formed by the through hole 18 and the hollow area 48.
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[0049]
More specifically, in the cross-sectional view shown in FIG. 4, the through hole 18 and the hollow
region 48 in plan view are illustrated. While the through hole 18 of the first embodiment shown
in FIG. 2 has a round hole shape, the through hole 18 of the second embodiment has a slit shape.
The through hole 18 has a shape extending along the outer periphery of the hollow portion 28.
The through hole 18 is formed along the periphery of the cavity 28 in the first surface 20 b of
the sensor substrate 20.
[0050]
The hollow region 48 is formed as a region in which the adhesive layer 40 is not provided in a
region along the periphery of the hollow portion 28 between the main surface 10 a and the first
surface 20 b in accordance with the slit-like through holes 18. . The hollow portion 28 viewed
from the top has a rectangular shape, and the through hole 18 and the hollow area 48 are
formed along one side of the rectangular.
[0051]
According to the microphone 1 of the second embodiment, as shown in FIG. 4, since the through
hole 18 is formed along the periphery of the cavity 28 in the first surface 20b, the plate
substrate 10 parallel to the main surface 10a is formed. The cross-sectional area of the through
hole 18 which appears in the cross section of the cross-section is increased as compared with the
first embodiment. The diameter of the acoustic port can be further increased by forming the
through hole 18 to have a large diameter and forming the hollow region 48 to have a large
diameter in accordance with the through hole 18. Therefore, the microphone 1 having better
acoustic characteristics can be provided. The shape and size of the through hole 18 may be
defined so as to be as large as possible within the range in which the rigidity of the plate
substrate 10 can be secured.
[0052]
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15
Third Embodiment FIG. 5 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a third embodiment. 6 is a cross-sectional view of the microphone 1
of the third embodiment, taken along the line VI-VI shown in FIG. The microphone 1 of the third
embodiment is different from that of the second embodiment in the number of acoustic ports
formed by the through holes 18 and the hollow regions 48.
[0053]
More specifically, in the cross-sectional view shown in FIG. 6, the cavity 28 has a rectangular
shape in top view. The through hole 18 of the second embodiment is formed along one side of a
rectangle, whereas the through hole 18 of the third embodiment is formed along all four sides of
the rectangle. A plurality of slit-like through holes 18 are formed in the plate substrate 10, and
each through hole 18 is formed along the periphery of the cavity 28 in the first surface 20b. The
hollow region 48 is formed along the periphery of the cavity 28 in accordance with the slit-like
through hole 18 as in the second embodiment.
[0054]
According to the microphone 1 of the third embodiment, four slit-like through holes 18
extending along the periphery of the hollow portion 28 are formed, and therefore, penetrations
appear in the cross section of the plate substrate 10 parallel to the main surface 10a. The cross
sectional area of the hole 18 is larger than that of the second embodiment. The diameter of the
acoustic port can be further increased by forming the through hole 18 to have a large diameter
and forming the hollow region 48 to have a large diameter in accordance with the through hole
18. Therefore, the microphone 1 having better acoustic characteristics can be provided. The
number of through holes 18 may be defined as many as possible within the range in which the
rigidity of the plate substrate 10 can be secured.
[0055]
Fourth Embodiment FIG. 7 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a fourth embodiment. The microphone 1 of the fourth embodiment is
different from that of the first embodiment in that a recess 19 in which the main surface 10 a of
the plate substrate 10 is recessed is formed in the plate substrate 10.
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[0056]
The recess 19 is formed adjacent to the through hole 18. The recess 19 is formed such that the
main surface 10 a on the side adjacent to the cavity 28 is recessed toward the connection surface
10 b with respect to the through hole 18. The through hole 18 is in communication with the
cavity 28 through the hollow region 48 and is in communication with the cavity 28 through the
recess 19. The recess 19 and the hollow area 48 communicate with each other. The recess 19
together with the through hole 18 and the hollow area 48 forms an acoustic port for introducing
acoustic vibration to the acoustic sensor. The shape of the through hole 18 may be a round hole
similar to that of the first embodiment, or may be a slit-like hole similar to that of the second
embodiment.
[0057]
According to the microphone 1 of the fourth embodiment, since the recess 19 in which the main
surface 10a of the plate substrate 10 is recessed is formed, the diameter of the acoustic port
communicating the external space of the microphone 1 with the cavity 28 is It is larger than that
of the first embodiment. By enlarging the diameter of the acoustic port, it is possible to provide
the microphone 1 having better acoustic characteristics.
[0058]
Fifth Embodiment FIG. 8 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a fifth embodiment. The microphone 1 of the fifth embodiment is
different from that of the first embodiment in that a recess 29 in which the first surface 20 b of
the sensor substrate 20 is recessed is formed in the sensor substrate 20.
[0059]
The recess 29 is formed on the extension of the through hole 18. The recess 29 is formed such
that a portion corresponding to the projection of the through hole 18 in the first surface 20b of
the sensor substrate 20 is recessed toward the second surface 20a, and the first surface 20b on
the cavity 28 side is recessed with respect to that portion. ing. The recess 29 is in communication
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with the cavity 28. The through hole 18 is in communication with the cavity 28 via the hollow
region 48 and is in communication with the cavity 28 via the recess 29. The recess 29 and the
hollow area 48 communicate with each other. The recess 29 forms an acoustic port together with
the through hole 18 and the hollow area 48. The shape of the through hole 18 may be a round
hole similar to that of the first embodiment, or may be a slit-like hole similar to that of the second
embodiment.
[0060]
According to the microphone 1 of the fifth embodiment, since the concave portion 29 in which
the first surface 20 b of the sensor substrate 20 is recessed is formed, the diameter of the
acoustic port communicating the external space of the microphone 1 and the hollow portion 28
is In comparison with the first embodiment. Therefore, as in the fourth embodiment, the
microphone 1 having better acoustic characteristics can be provided.
[0061]
Sixth Embodiment FIG. 9 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a sixth embodiment. The microphone 1 of the sixth embodiment is
different from that of the fifth embodiment in the shape of the recess 29 formed in the sensor
substrate 20.
[0062]
The bottom of the recess 29 of the fifth embodiment shown in FIG. 8 is formed substantially
parallel to the first surface 20 b of the sensor substrate 20. In the cross-sectional view shown in
FIG. Have. On the other hand, the recess 29 of the sixth embodiment shown in FIG. 9 has an
inner wall surface inclined with respect to the first surface 20 b of the sensor substrate 20 and is
formed in a tapered shape, as shown in FIG. The recess 29 has a substantially triangular crosssectional shape. The recess 29 having a rectangular cross section shown in FIG. 8 can be formed,
for example, using isotropic etching. The recess 29 having a triangular cross section shown in
FIG. 9 can be formed, for example, using anisotropic etching.
[0063]
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18
According to the microphone 1 of the sixth embodiment, as in the fifth embodiment, since the
diameter of the acoustic port is expanded, the microphone 1 having better acoustic
characteristics can be provided. In the example shown in FIG. 9, there is a portion where the
sensor substrate 20 is not processed and the first surface 20 b is not recessed between the
recess 29 and the cavity 28, but the thickness of the adhesive layer 40 is sufficiently secured. If
the diameter of the hollow region 48 is sufficiently large, good acoustic characteristics of the
microphone 1 can be secured.
[0064]
Seventh Embodiment FIG. 10 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a seventh embodiment. The microphone 1 of the seventh
embodiment basically has the same configuration as the microphone 1 of the fourth embodiment
described above, and the plate substrate 10 is provided with a recess 19 in which the main
surface 10 a of the plate substrate 10 is recessed. ing. However, the seventh embodiment is
different from the fourth embodiment in that the recess 19 is formed in the shape shown in FIG.
[0065]
Specifically, in the seventh embodiment, main surface 10a on the side of cavity 28 with respect
to through hole 18 is recessed in recess 19, and main surface 10a on the side away from cavity
28 with respect to through hole 18 is recessed. It is formed. An adhesive cured product 41 is
accommodated in a part of the inside of the recess 19 on the side of the through hole 18 away
from the cavity 28. In the adhesive cured product 41, a part of the liquid adhesive applied to the
main surface 10 a for bonding the acoustic sensor to the plate substrate 10 flows into the inside
of the recess 19 and is cured in the recess 19.
[0066]
In the microphone 1 of the seventh embodiment, in order to mount the acoustic sensor on the
main surface 10 a of the plate substrate 10, a liquid adhesive such as a liquid resin is used. The
sensor substrate 20 is bonded to the plate substrate 10 by a liquid adhesive. In this case, the
recess 19 is used as a reservoir (liquid reservoir) of the liquid adhesive. By forming the recess 19
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19
in the main surface 10 a on the side away from the cavity 28 with respect to the through hole
18, even if the fluid adhesive having flowability flows into the recess 19, the liquid adhesive
Hardens without reaching the through holes 18. As a result, the microphone 1 has the adhesive
cured product 41 accommodated in the recess 19. In this way, the liquid adhesive can be
prevented from blocking the acoustic port, so that predetermined acoustic characteristics of the
microphone 1 can be secured.
[0067]
Eighth Embodiment FIG. 11 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to an eighth embodiment. The microphone 1 of the eighth embodiment
basically has the same configuration as the microphone 1 of the fifth embodiment described
above, and the sensor substrate 20 is provided with a recess 29 in which the first surface 20b of
the sensor substrate 20 is recessed. It is done. However, the eighth embodiment is different from
the fifth embodiment in that the recess 29 is formed in the shape shown in FIG.
[0068]
Specifically, in the eighth embodiment, the first surface 20b of a portion corresponding to the
projection of the through hole 18 in the first surface 20b is recessed in the recess 29, and the
first surface 20b on the cavity 28 side with respect to the projection In addition, the first surface
20b on the side away from the cavity 28 with respect to the projection is formed to be recessed.
The adhesive cured product 41 is accommodated in a part of the inside of the recess 29 on the
side of the through hole 18 away from the cavity 28. In the adhesive cured product 41, a part of
the liquid adhesive applied to the main surface 10 a for bonding the acoustic sensor to the plate
substrate 10 flows into the recess 29 and is cured in the recess 29.
[0069]
In the microphone 1 of the eighth embodiment, as in the seventh embodiment, the sensor
substrate 20 is bonded to the plate substrate 10 by a liquid adhesive. The recess 29 is used as a
reservoir of liquid adhesive. As a result, the liquid adhesive can be prevented from blocking the
acoustic port, so that predetermined acoustic characteristics of the microphone 1 can be secured.
18-04-2019
20
[0070]
Ninth Embodiment FIG. 12 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a ninth embodiment. The microphone 1 of the ninth embodiment
basically has the same configuration as that of the microphone 1 of the sixth embodiment
described above, and the sensor substrate 20 has a recess 29 in which the first surface 20b of
the sensor substrate 20 is recessed. It is done. However, the ninth embodiment is different from
the sixth embodiment in that the recess 29 is formed in the shape shown in FIG.
[0071]
Specifically, in the ninth embodiment, the first surface 20b of the portion corresponding to the
projection of the through hole 18 in the first surface 20b is recessed in the recess 29, and
further, the side away from the cavity 28 with respect to the projection The first surface 20 b is
formed to be recessed. The adhesive cured product 41 is accommodated in a part of the inside of
the recess 29 on the side of the through hole 18 away from the cavity 28.
[0072]
In the microphone 1 of the ninth embodiment, as in the seventh embodiment, the sensor
substrate 20 is bonded to the plate substrate 10 by a liquid adhesive. The recess 29 is used as a
reservoir of liquid adhesive. As a result, the liquid adhesive can be prevented from blocking the
acoustic port, so that predetermined acoustic characteristics of the microphone 1 can be secured.
[0073]
Tenth Embodiment FIG. 13 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a tenth embodiment. 14 is a cross-sectional view of the microphone 1
of the tenth embodiment, taken along line XIV-XIV shown in FIG. The microphone 1 of the tenth
embodiment is different from that of the first embodiment in the shape of the main surface 10 a
side of the plate substrate 10.
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21
[0074]
More specifically, the plate substrate 10 has a projection 16 projecting from the main surface
10a. A plurality of protrusions 16 are formed to surround the hollow portion 28 of the sensor
substrate 20. In the embodiment shown in FIG. 14, four protrusions 16 are formed. The tip of the
projection 16 which is most distant from the main surface 10 a is formed flat. The tips of the
plurality of protrusions 16 are disposed on the same plane parallel to the major surface 10 a of
the plate substrate 10. The sensor substrate 20 of the acoustic sensor is mounted on the
protrusion 16. The first surface 20 b of the sensor substrate 20 is supported by the protrusions
16 in surface contact with the tip surfaces of the plurality of protrusions 16.
[0075]
The main surface 10 a of the plate substrate 10 and the first surface 20 b of the sensor substrate
20 are spaced apart from each other by the height of the protrusion 16. The adhesive layer 40
interposed between the main surface 10 a and the first surface 20 b has the same thickness as
the height of the protrusion 16.
[0076]
When a liquid adhesive is used, the first surface 20 b of the sensor substrate 20 is supported by
the protrusions 16 with an adhesive layer adjacent to the tip surfaces of the plurality of
protrusions 16. The adhesive layer 40 interposed between the main surface 10 a and the first
surface 20 b has a total thickness of the height of the protrusion 16 and the thickness of the
resin remaining on the tip end surface of the protrusion 16. The thickness of the resin remaining
on the tip end face of the protrusion 16 is determined by the viscosity of the liquid adhesive, the
pressure applied to the liquid adhesive during mounting, and the shape of the protrusion 16.
[0077]
According to the microphone 1 of the tenth embodiment, the plate substrate 10 is provided with
the plurality of protrusions 16 protruding from the main surface 10 a, and the sensor substrate
20 is mounted on the protrusions 16. An adhesive layer 40 for bonding the sensor substrate 20
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22
to the plate substrate 10 is disposed between the main surface 10 a of the plate substrate 10 and
the first surface 20 b of the sensor substrate 20. It is possible to freely change the thickness of
the adhesive layer 40 by adjusting the height of the protrusions 16 protruding from the main
surface 10a. The dimension of the hollow region 48 in the thickness direction of the plate
substrate 10 is determined by the thickness of the adhesive layer 40. Therefore, the diameter of
the hollow region 48 can be adjusted in accordance with the dimension of the protrusion 16.
[0078]
As described above, the hollow area 48 constitutes an acoustic port for introducing acoustic
vibration to the acoustic sensor, and the larger the diameter of the acoustic port, the more
advantageous it is in terms of the characteristics of the microphone 1. By forming the
protrusions 16 on the plate substrate 10 and determining the thickness of the adhesive layer 40
by the protrusions 16, the dimension in the height direction of the hollow region 48 can be made
sufficiently large, and the acoustic of a sufficiently large diameter can be obtained. A port can be
formed. Therefore, the acoustic performance of the microphone 1 can be sufficiently secured.
Since the thickness of the adhesive layer 40 can be stabilized throughout and the variation in
thickness of the adhesive layer 40 can be reduced, the variation in acoustic characteristics of the
microphone 1 can be reduced.
[0079]
Eleventh Embodiment FIG. 15 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to an eleventh embodiment. 16 is a cross-sectional view of the
microphone 1 of the eleventh embodiment, taken along line XVI-XVI shown in FIG. The
microphone 1 of the eleventh embodiment is different from that of the first embodiment in that
the microphone 1 further includes an interposing member 46 interposed between the main
surface 10a of the plate substrate and the first surface 20b of the sensor substrate 20. .
[0080]
The interposing member 46 is mounted on the main surface 10 a of the plate substrate 10 and is
disposed so as to protrude relative to the main surface 10 a. A plurality of intervening members
46 are provided so as to surround the hollow portion 28 of the sensor substrate 20. In the
embodiment shown in FIG. 16, four intervening members 46 are arranged. The sensor substrate
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23
20 of the acoustic sensor is mounted on the intervening member 46. The first surface 20 b of the
sensor substrate 20 is supported by the intervening members 46 in contact with the plurality of
intervening members 46 respectively.
[0081]
The main surface 10 a of the plate substrate 10 and the first surface 20 b of the sensor substrate
20 are spaced apart from each other by the dimension of the interposing member 46 in the
height direction. The intervening member 46 is disposed through the adhesive layer 40. The
adhesive layer 40 interposed between the main surface 10 a and the first surface 20 b has the
same thickness as the height of the interposing member 46.
[0082]
According to the microphone 1 of the eleventh embodiment, the plurality of intervening
members 46 are disposed through the adhesive layer 40 between the main surface 10 a of the
plate substrate 10 and the first surface 20 b of the sensor substrate 20. The sensor substrate 20
is mounted on the interposing member 46. By adjusting the dimensions of the interposing
member 46 in the thickness direction of the plate substrate 10, the thickness of the adhesive
layer 40 can be freely changed. The dimension of the hollow region 48 in the thickness direction
of the plate substrate 10 is determined by the thickness of the adhesive layer 40. Therefore, the
diameter of the hollow region 48 can be adjusted in accordance with the size of the interposing
member 46.
[0083]
By determining the thickness of the adhesive layer 40 with the interposing member 46, as in the
tenth embodiment, the dimension in the height direction of the hollow region 48 can be made
sufficiently large, and an acoustic port with a sufficiently large diameter can be formed. it can.
Therefore, the acoustic performance of the microphone 1 can be sufficiently ensured, and
furthermore, variations in acoustic characteristics of the microphone 1 can be reduced.
[0084]
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24
Twelfth Embodiment FIG. 17 is a cross-sectional view showing an outline of a configuration of a
microphone 1 according to a twelfth embodiment. FIG. 18 is a cross-sectional view of the
microphone of the twelfth embodiment, taken along line XVIII-XVIII shown in FIG. In the
microphone 1 of the twelfth embodiment, the plate substrate 10 has, in addition to the
protrusion 16 similar to that of the tenth embodiment, a protrusion 17 which protrudes from the
main surface 10a. The tip end surface of the protrusion 16 and the tip end surface of the
protrusion 17 are disposed on the same plane. The sensor substrate 20 is mounted on the
protrusion 16 and the protrusion 17 and is supported by both the protrusion 16 and the
protrusion 17.
[0085]
The through holes 18 are formed penetrating the plate substrate 10 in the thickness direction,
and are open to the main surface 10 a. The protrusion 17 is provided to project from the main
surface 10a along the periphery of the through hole 18 in the main surface 10a, as shown in FIG.
The through hole 18 shown in FIG. 18 has a round hole shape, and the protrusion 17 has a
portion extending in an arc shape along the outer periphery of the round hole. A part of the outer
periphery of the through hole 18 is surrounded by the protrusion 17. The adhesive layer 40 is
separated from the through hole 18 by the protrusion 17.
[0086]
In the microphone 1 of the twelfth embodiment, in order to mount the acoustic sensor on the
main surface 10a of the plate substrate 10, a liquid adhesive such as a liquid resin is used. The
sensor substrate 20 is bonded to the plate substrate 10 by a liquid adhesive. When the liquid
adhesive is supplied to the main surface 10 a, even if the fluid liquid adhesive moves in the
surface direction along the main surface 10 a, the flow of the liquid adhesive is made by the
protrusions 17. You can stop it. The protrusions 17 function as a barrier to the flow of the liquid
adhesive. Therefore, the liquid adhesive can be prevented from reaching the through hole 18 and
flowing into the through hole 18, and the liquid adhesive can be prevented from blocking the
acoustic port, so that predetermined acoustic characteristics of the microphone 1 can be
prevented. Can be secured.
[0087]
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25
Thirteenth Embodiment FIG. 19 is a cross-sectional view showing an outline of a configuration of
a microphone 1 according to a thirteenth embodiment. In the previous embodiments, the
acoustic sensor was mounted on the flat plate substrate 10, but in the microphone 1 of the
thirteenth embodiment, the plate substrate 10 is formed in a shape in which an angular C
character is laid. There is. The plate substrate 10 having such a shape may be formed by cutting,
or may be formed by attaching a frame to the peripheral portion of the flat multilayer wiring
substrate. The acoustic sensor is mounted on the bottom surface of the plate substrate 10 having
a C-shape.
[0088]
The microphone 1 of the thirteenth embodiment further includes a lid substrate 70. The
laminated structure of the acoustic sensor and the circuit element 30 is accommodated in the
internal space of the package formed by the plate substrate 10 and the lid substrate 70. The
plate substrate 10 and the lid substrate 70 form the housing of the microphone 1 of the
thirteenth embodiment. A hollow space 78 surrounded by the plate substrate 10, the lid
substrate 70, the acoustic sensor and the circuit element 30 is formed inside the housing.
[0089]
Similar to the plate substrate 10 described in the first embodiment, the lid substrate 70 is formed
of a flat multilayer wiring substrate, and the conductive layer 72 exposed on the main surface
facing the acoustic sensor, and the acoustic signal And an external connection terminal 74
laminated on the main surface on the side not facing the sensor. The lid substrate 70 is provided
with a conductive layer (not shown) extending in the surface direction and a via electrode
extending in the thickness direction on the surface and the inside of the lid substrate 70 in
addition to the conductive layer 72 and the external connection terminal 74 shown.
[0090]
When the microphone 1 is mounted on the mother substrate, the external connection terminal
74 is electrically connected to the connection terminal on the mother substrate side, whereby
power supply to the microphone 1 and communication of control signals are performed.
Therefore, unlike the first embodiment, the external connection terminal is not provided on the
18-04-2019
26
plate substrate 10 shown in FIG. The conductive layer 12 is exposed at the C-shaped tip of the
plate substrate 10. The conductive layer 12 and the conductive layer 72 formed on the lid
substrate 70 are disposed at mutually opposing positions. The conductive layer 12 and the
conductive layer 72 are electrically connected with the conductive member 75 interposed. The
conductive member 75 is formed of any one or a combination of a conductive adhesive, a solder,
a conductive double-sided adhesive tape, and a brazing material for welding.
[0091]
The conductive layer 12 formed on the plate substrate 10 and the conductive layer 32 formed on
the circuit element 30 are connected by a bonding wire 64. As compared with the first
embodiment, the wire length of the bonding wire 64 is smaller, which makes it difficult to cut the
bonding wire 64 and facilitates the wire bonding operation.
[0092]
With the above-described configuration, the top port type microphone 1 having the external
connection terminal 74 and provided with the acoustic port at a distance from the lid substrate
70 mounted on the mother substrate is realized. Also in the microphone 1 of the thirteenth
embodiment, as in the first embodiment, the acoustic port for introducing the acoustic vibration
into the cavity 28 is formed in a bent shape. The bent shaped acoustic port is formed by the
through hole 18 and the hollow area 48. As a result, foreign matter or compressed air can be
suppressed from entering the cavity 28 and reaching the diaphragm 24 via the acoustic port, so
damage to the diaphragm 24 can be reduced. In addition, since the thickness of the plate
substrate 10 can be reduced and the dimension in the height direction of the microphone 1 can
be reduced, the height of the microphone 1 can be reduced.
[0093]
In the configuration of the present embodiment shown in FIG. 19, the space 38 and the space 78
can be communicated by providing a gap between the acoustic sensor and the circuit element 30.
In this way, the volume of the back chamber of the microphone 1 can be further increased. In
this case, it is necessary to fill the portions where the conductive members 75 are intermittently
present with an insulating resin to acoustically seal the spaces 38, 78 from the outside.
18-04-2019
27
[0094]
Fourteenth Embodiment FIG. 20 is a cross-sectional view showing an outline of a configuration of
a microphone 1 according to a fourteenth embodiment. In the above embodiments, the acoustic
sensor and the circuit element 30 are laminated to each other to form a laminated structure, but
in the microphone 1 of the fourteenth embodiment, the circuit element 30 is laminated to the
acoustic sensor. Instead, the acoustic sensor and the circuit element 30 are arranged on the base
substrate, and both are mounted on the base substrate.
[0095]
The microphone 1 shown in FIG. 20 includes a package 80. The package 80 forms a housing of
the microphone 1 of the fourteenth embodiment. The package 80 has a hollow box-like shape, in
which a hollow space is formed. Of the internal space of the package 80, the cavity 28 functions
as a front chamber of the microphone 1, and the space 38 opposite to the cavity 28 with respect
to the diaphragm 24 functions as a back chamber of the microphone 1. Similar to the plate
substrate 10 described in the first embodiment, the package 80 is formed of a flat multilayer
wiring board, and has a main surface 80a and a connection surface 80b opposite to the main
surface 80a. doing. Both the acoustic sensor and the circuit element 30 are mounted on the
major surface 80a. The package 80 has a function as a base substrate in the fourteenth
embodiment.
[0096]
The package 80 has a conductive layer 82 formed so as to be exposed to the main surface 80 a
and an external connection terminal 84 stacked on the connection surface 80 b. Package 80 has
a conductive layer (not shown) and an external connection terminal 84, as well as a conductive
layer (not shown) extending in the surface direction on and in the surface of package 80 and a
via electrode extending in the thickness direction. The conductive layer 32 formed on the circuit
element 30 and the conductive layer 82 formed on the package 80 are connected by a bonding
wire 64. The package 80 is formed with a through hole 88 penetrating the package 80 in the
thickness direction. The through hole 88 constitutes a part of the acoustic port.
[0097]
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28
Also in the microphone 1 according to the fourteenth embodiment having the above-described
configuration, as in the first embodiment, the acoustic port for introducing acoustic vibration into
the cavity 28 is formed in a bent shape. The bent shaped acoustic port is formed by the through
hole 88 and the hollow area 48. As a result, foreign matter or compressed air can be suppressed
from entering the cavity 28 and reaching the diaphragm 24 via the acoustic port, so damage to
the diaphragm 24 can be reduced. In addition, by reducing the size in the height direction of the
microphone 1, the volume of the back chamber can be increased, and the performance
improvement of the microphone 1 can be realized.
[0098]
Fifteenth Embodiment FIG. 21 is a cross sectional view showing an outline of a configuration of a
microphone 1 according to a fifteenth embodiment. The microphone 1 of the fifteenth
embodiment is provided with a cover member 90 shaped like an angled C-shape. The cover
member 90 is formed of an insulating material represented by a resin material. The plate
substrate 10 and the cover member 90 are assembled in a hollow box shape, and a hollow space
is formed inside the box. An acoustic sensor and a circuit element 30 are accommodated in an
internal space of a package formed by the plate substrate 10 and the cover member 90. The
plate substrate 10 and the cover member 90 form a housing of the microphone 1 of the fifteenth
embodiment.
[0099]
The cover member 90 has a main surface 90 a facing the plate substrate 10 and an outer surface
90 b opposite to the main surface 90 a. Both the acoustic sensor and the circuit element 30 are
mounted on the main surface 90 a of the cover member 90. Cover member 90 has a function as
a base member in the fifteenth embodiment. Of the box-shaped internal space formed by the
plate substrate 10 and the cover member 90, the cavity 28 functions as the front chamber of the
microphone 1, and the space 38 opposite to the cavity 28 with respect to the diaphragm 24 is
the microphone 1. Act as a back chamber for
[0100]
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29
The conductive layer 92 is exposed at the C-shaped tip of the cover member 90. The conductive
layer 92 and the conductive layer 12 formed on the plate substrate 10 are disposed at mutually
opposing positions. The conductive layer 12 and the conductive layer 92 are electrically
connected with the conductive member 95 interposed. The conductive member 95 is formed of
any one or a combination of a conductive adhesive, solder, a conductive double-sided adhesive
tape, and a brazing material for welding. It is necessary to fill the portion where the conductive
member 95 is intermittently present with an insulating resin to acoustically seal the space 38
from the outside. The conductive layer 32 formed on the circuit element 30 is connected to the
conductive layer 12 formed on the plate substrate 10 and the conductive layer 92 formed on the
cover member 90 by bonding wires 64. In the cover member 90, a through hole 98 which
penetrates the cover member 90 in the thickness direction is formed. The through hole 98
constitutes a part of the acoustic port.
[0101]
With the above-described configuration, the top port type microphone 1 having the external
connection terminal 14 and the acoustic port provided at a distance from the plate substrate 10
mounted on the mother substrate is realized. Also in the microphone 1 of the fifteenth
embodiment, as in the first embodiment, the acoustic port for introducing acoustic vibration into
the cavity 28 is formed in a bent shape. The bent shaped acoustic port is formed by the through
hole 98 and the hollow area 48. As a result, foreign matter or compressed air can be suppressed
from entering the cavity 28 and reaching the diaphragm 24 via the acoustic port, so damage to
the diaphragm 24 can be reduced. In addition, by reducing the size in the height direction of the
microphone 1, the volume of the back chamber can be increased, and the performance
improvement of the microphone 1 can be realized.
[0102]
In the embodiments described above, the projection in which the sensor substrate 20 is copied
on the main surface of the base substrate along the thickness direction of the base substrate is an
opening where the through hole formed in the base substrate is opened in the main surface An
example of overlapping all parts has been described. The projection of the sensor substrate 20
may overlap with a part of the opening. If the through holes overlap a part of the sensor
substrate 20, the above-described effect of suppressing the entry of foreign matter into the
hollow portion 28 can be similarly obtained.
18-04-2019
30
[0103]
Also, in the above embodiments, the example using bonding wires 62 and 64 for the electrical
connection between the acoustic sensor, the circuit element 30, and the substrate on which the
acoustic sensor is mounted has been described. The electrical connection is not limited to wire
bonding, and for example, flat plate-like circuit element 30 and acoustic sensor may be
electrically connected using flip chip bonding, and silicon through electrodes penetrating circuit
element 30 ( The circuit element 30 and the acoustic sensor may be electrically connected using
TSV.
[0104]
In addition, the microphone 1 may further include a conductive electromagnetic shield for
reducing electromagnetic noise. The electromagnetic shield may be disposed on the surface of
the circuit element 30 stacked on the acoustic sensor, the surface opposite to the surface facing
the acoustic sensor. Alternatively, the electromagnetic shield may be disposed on either or both
of the outer surface and the inner surface of the housing of the microphone 1.
[0105]
It should be understood that the embodiment disclosed herein is illustrative and non-restrictive
in every respect. The scope of the present invention is indicated not by the above description but
by the claims, and is intended to include all the modifications within the meaning and scope
equivalent to the claims.
[0106]
Reference Signs List 1 microphone, 10 plate substrate, 10a, 80a, 90a main surface, 10b, 80b
connection surface, 12, 32, 72, 82, 92 conductive layer, 14, 74, 84 external connection terminal,
16, 17 projection, 18, 88, 98 through hole, 19, 29 recess, 20 sensor substrate, 20a second
surface, 20b first surface, 22 microphone terminal, 24 diaphragm, 25 back plate, 26 air gap, 28
cavity, 30 circuit elements, 38 space 40 adhesive layer, 41 adhesive cured product, 46
intervening member, 48 hollow area, 50 protective layer, 62, 64 bonding wire, 70 lid substrate,
75, 95 conductive member, 80 package, 90 cover member.
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