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JP2011015107

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DESCRIPTION JP2011015107
The present invention provides a microphone unit that can reduce stress generated in a
diaphragm and has less sensitivity fluctuation. A microphone unit 1 includes an electroacoustic
conversion unit 12 having a diaphragm 122 displaced by sound pressure to convert a sound
signal into an electric signal, a substrate 11 on which the electroacoustic conversion unit 122 is
mounted, and an external sound Housing at least one sound hole 14a for introducing pressure
and containing the substrate 11 (for example, the top case 14 and the bottom case 15) and the
contact point between the substrate 11 and the housing is reduced And a buffer member 17
disposed between the substrate 11 and the housing and reducing stress generated in the
substrate 11. [Selected figure] Figure 2
マイクロホンユニット
[0001]
The present invention relates to a microphone unit having a function of converting an input
sound into an electrical signal.
[0002]
Conventionally, for example, a microphone unit is applied to a voice input device such as a voice
communication device such as a cellular phone or transceiver, or an information processing
system using a technology for analyzing input voice such as a voice authentication system, or a
recording device. (See, for example, Patent Document 1).
03-05-2019
1
Here, the microphone unit refers to one having a function of converting an input sound into an
electric signal and outputting the electric signal.
[0003]
FIG. 12 is a schematic cross-sectional view showing a configuration example of a conventional
microphone unit. As shown in FIG. 12, the conventional microphone unit 100 includes a
substrate 101, an electroacoustic transducer 102 mounted on the substrate 101 to convert
sound pressure into an electrical signal, and an electroacoustic transducer 102 mounted on the
substrate 101. And a cover member 104 for protecting the electro-acoustic conversion unit 102
and the electric circuit unit 103 mounted on the substrate 101 from dust and the like. A sound
hole (through hole) 104 a is formed in the cover member 104 so that an external sound is guided
to the electroacoustic transducer 102.
[0004]
The electroacoustic transducer 102 is provided with a diaphragm (not shown), and the
microphone unit 100 outputs an electrical signal according to the vibration of the diaphragm
that is vibrated (displaced) by the sound pressure input through the sound hole 104a. It is
supposed to be. When the tension of the diaphragm changes, the sensitivity of the microphone
unit 100 changes. Specifically, when the tension of the diaphragm decreases, the diaphragm is
more likely to vibrate and the sensitivity is improved. On the other hand, when the tension of the
diaphragm becomes large, the diaphragm becomes difficult to vibrate and the sensitivity
decreases.
[0005]
In mass production of microphone units, it is necessary to produce the sensitivity so as to be
within a certain range, and it is inconvenient if the tension of the diaphragm fluctuates at the
time of manufacture of the microphone unit and the sensitivity varies. For this reason, in the
manufacture of the conventional microphone unit 100, it was necessary to manufacture so that
the tension of the diaphragm can be kept within the target range.
03-05-2019
2
[0006]
Although the above-described microphone unit 100 is for a microphone unit having a different
configuration, Patent Document 2 discloses a technique for preventing performance
deterioration due to tension change of the diaphragm. Hereinafter, the configuration disclosed in
Patent Document 2 will be briefly described.
[0007]
FIG. 13 is a schematic cross-sectional view showing the configuration of the (other conventional
example) microphone unit disclosed in Patent Document 2. As shown in FIG. As shown in FIG. 13,
in the conventional microphone unit 200, the diaphragm 201, the diaphragm holder 202 to
which the diaphragm 201 is fixed, and the diaphragm 201 are disposed opposite to each other
with a gap therebetween, And a printed circuit board 205 on which the impedance converter
204 is disposed, and a unit case 206 in which these members are incorporated. Then, in the
microphone unit 200, a conductive biasing member 207 having an elastic force is interposed
between the printed circuit board 205 and an internal component including the diaphragm 201,
the diaphragm holder 202, and the fixed electrode 203.
[0008]
In such a configuration, due to the presence of the biasing member 207, the internal components
inside the unit case 206 can be fixed reliably and in a well-balanced manner, so that it is possible
to prevent performance deterioration due to tension change of the diaphragm 201 .
[0009]
JP, 2008-199353, A JP, 2008-67128, A
[0010]
The present inventors have developed a microphone unit 300 having a configuration as shown in
FIG. 14, for example, for the purpose of efficiently assembling the above-described conventional
microphone unit 100 (see FIG. 12).
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3
FIG. 14 is a schematic cross-sectional view showing a configuration example of a microphone
unit under development by the present inventors.
[0011]
As shown in FIG. 14, in the microphone unit 300 under development by the present inventors, a
substrate 301 on which the electroacoustic transducer 302 and the electric circuit unit 303 are
mounted, a bottom case 304 accommodating the substrate 301, and a bottom case And a top
case 305 mounted on the substrate so as to cover the electroacoustic transducer 302.
A sound hole 305 a is formed in the top case 305 so that an external sound can be guided to the
electroacoustic transducer 302.
[0012]
Since the microphone unit 300 having such a configuration can be aligned with each other
simply by fitting the substrate 301 and the top case 305 to the bottom case 304 in this order,
the assembly operation of the microphone unit 300 is facilitated.
[0013]
However, it has been found that the microphone unit 300 having such a configuration has the
following problems.
That is, for example, when the top case 305 is fitted into the bottom case 304, a force is applied
to the substrate 301 to deform the substrate 301 (stress is generated in the substrate 301), and
the diaphragm (the diagram of FIG. Stress may occur. As a result, the tension of the diaphragm
may be fluctuated and the sensitivity of the microphone unit 300 may be fluctuated.
[0014]
In addition, when the microphone unit 300 is flip-chip mounted on the mounting substrate of the
voice input device, reflow processing may be performed at a high temperature of about 270 °
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4
C., for example. In this case, if the difference in linear expansion coefficient between the substrate
301 and the bottom case 304 is large, stress is generated in the substrate 301 by the heating
and cooling process at the time of reflow. As a result, stress may be generated also in the
diaphragm provided in the electroacoustic transducer 302, and the tension of the diaphragm
may fluctuate to change the sensitivity of the microphone unit 300. In addition, stress may also
be generated on the substrate 301 due to a change in the use environment or the like, and as a
result, stress may also be generated on the diaphragm, and the sensitivity of the microphone unit
300 may change.
[0015]
In addition, the above problems are not shown by patent document 1 or 2, and it is not disclosed
nor suggested about the structure which eliminates such a problem.
[0016]
Therefore, an object of the present invention is to provide a microphone unit that can reduce
stress generated in a diaphragm and has less sensitivity fluctuation.
[0017]
In order to achieve the above object, a microphone unit according to the present invention
includes an electro-acoustic conversion unit having a diaphragm displaced by sound pressure to
convert a sound signal into an electric signal, a substrate on which the electro-acoustic
conversion unit is mounted; A housing having at least one sound hole for introducing an external
sound pressure and arranged between the substrate and the housing so as to reduce the contact
point between the substrate and the housing and the housing in which the substrate is
accommodated And a buffer member for reducing stress generated in the substrate.
[0018]
According to this configuration, since the stress generated on the substrate is reduced by the
buffer member, the stress on the diaphragm caused by the stress generated on the substrate can
be reduced.
That is, according to the present configuration, it is possible to suppress the tension fluctuation
of the diaphragm and to provide the microphone unit with less sensitivity fluctuation.
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[0019]
In the microphone unit of the above configuration, the case is a cover that is formed with the
sound hole and covers an upper surface of the substrate on which the electroacoustic transducer
is disposed to form an internal space in which the electroacoustic transducer is accommodated. It
is good also as having a member and an accommodation crevice and consisting of a box shaped
member which accommodates the substrate and the cover member in the accommodation
crevice with the substrate below and the cover member as the upper side.
[0020]
According to this configuration, it is possible to provide a microphone unit in which the
positional relationship between the substrate and the cover member is aimed at by merely
housing the substrate and the cover member in the box-shaped member.
That is, according to the present configuration, it is possible to provide a microphone unit which
is easy to perform mass production, which has both of the small sensitivity fluctuation and the
good assembly property.
[0021]
In the microphone unit configured as described above, the buffer member may be disposed
between the upper surface of the substrate and the cover member to make the substrate and the
cover member in non-contact with each other.
[0022]
Further, in the microphone unit having the above configuration, the buffer member may be
disposed between the lower surface of the substrate and the bottom surface of the
accommodation recess to reduce the contact point between the substrate and the box-shaped
member. Good.
[0023]
Furthermore, in the microphone unit having the above configuration, the buffer member may be
disposed between the side surface of the substrate and the side surface of the receiving recess to
reduce the contact point between the substrate and the box-shaped member. Good.
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[0024]
In the microphone unit of the above configuration, a first through hole provided below the
diaphragm and a second through hole provided separately from the first through hole are formed
in the substrate, and the cover member is formed. Two sound holes of a first sound hole and a
second sound hole are formed in the groove, a groove is formed in a part of the bottom surface
of the housing recess, and the inside from the first sound hole in the housing A first sound path
passing through a space to the upper surface of the diaphragm, and a second sound hole from
the second acoustic hole to the second through hole, the groove portion, and the first through
hole in order to the lower surface of the diaphragm A sound path may be formed.
[0025]
According to this configuration, the microphone unit (the difference between the sound pressure
applied to the upper surface of the diaphragm and the sound pressure applied to the lower
surface of the vibration plate having the two sound holes) In the dynamic microphone unit), a
configuration with less sensitivity fluctuation can be realized.
[0026]
In the microphone unit of the above configuration, the case has two sound holes of a first sound
hole and a second sound hole, and the case extends from the first sound hole to the upper
surface of the diaphragm in the case. A first sound path and a second sound path extending from
the second sound hole to the lower surface of the diaphragm may be formed.
According to this configuration, the microphone unit (the difference between the sound pressure
applied to the upper surface of the diaphragm and the sound pressure applied to the lower
surface of the vibration plate having the two sound holes) In the dynamic microphone unit), a
configuration with less sensitivity fluctuation can be realized.
[0027]
In the microphone unit configured as described above, the buffer member may be made of resin.
Also, the buffer member may be an adhesive.
03-05-2019
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Then, a silicone-based resin may be selected as the buffer member having these characteristics.
[0028]
In the microphone unit of the above configuration, the substrate may be a film substrate.
According to this configuration, it is possible to provide a thin microphone unit, which has less
sensitivity fluctuation.
[0029]
According to the present invention, it is possible to provide a microphone unit that can reduce
stress generated in the diaphragm and has less sensitivity fluctuation.
That is, according to the present invention, it is possible to manufacture a microphone unit
having desired sensitivity characteristics with high yield, and it is possible to suppress the cost
required for manufacturing the microphone unit.
[0030]
The outline perspective view showing the appearance composition of the microphone unit of a
1st embodiment to which the present invention was applied The sectional view in the AA position
of Drawing 1 The exploded view microphone unit of a 1st embodiment to which the present
invention was applied The schematic plan view showing the composition of the substrate
provided in the microphone unit of the embodiment The schematic sectional view showing the
first modification of the microphone unit of the first embodiment The schematic sectional view
showing the second modification of the microphone unit of the first embodiment A schematic
sectional view showing a third modification of the microphone unit according to the embodiment
A schematic sectional view showing a fourth modification of the microphone unit according to
the first embodiment A schematic showing a configuration of the microphone unit according to
the second embodiment to which the present invention is applied Sectional view A schematic
perspective view showing an appearance configuration of a microphone unit according to a third
embodiment to which the present invention is applied A section at a position B-B in FIG. 10
03-05-2019
8
Schematic cross-sectional view schematic cross-sectional view the inventors showing the
configuration of a microphone unit of a schematic cross-sectional view another conventional
example showing a configuration example of the microphone unit in development showing a
configuration example of a conventional microphone unit
[0031]
Hereinafter, embodiments of a microphone unit to which the present invention is applied will be
described in detail with reference to the drawings.
[0032]
First Embodiment FIG. 1 is a schematic perspective view showing the external configuration of a
microphone unit according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line A-A of FIG.
FIG. 3 is an exploded view of the microphone unit of the first embodiment to which the present
invention is applied, and is shown using a cross section cut at a position A-A in FIG.
FIG. 4 is a schematic plan view showing the configuration of the substrate provided in the
microphone unit of the first embodiment, FIG. 4 (a) shows the upper surface of the substrate, and
FIG. 4 (b) shows the lower surface of the substrate.
The microphone unit of the first embodiment will be described with reference to FIGS. 1 to 4.
[0033]
As shown in FIGS. 1 to 3, the microphone unit 1 according to the first embodiment mainly
includes a substrate 11 on which a micro electro mechanical system (MEMS) chip 12 and an
application specific integrated circuit (ASIC) 13 are mounted, and a substrate A top case 14
disposed to cover 11 and a box-shaped bottom case 15 in which the substrate 11 and the top
case 14 are accommodated are provided.
03-05-2019
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[0034]
The top case 14 is an embodiment of the cover member of the present invention, and the bottom
case 15 is an embodiment of the box-shaped member of the present invention.
And bottom case 15 and top case 14 are combined, and it becomes an embodiment of a case of
the present invention. The MEMS chip 12 is an embodiment of the electroacoustic transducer of
the present invention.
[0035]
The substrate 11 having a substantially rectangular shape in plan view is formed of an insulating
member. Although the material of the substrate 11 is not particularly limited, for example, a glass
epoxy substrate, a polyimide substrate, a silicon substrate, a glass substrate or the like can be
used. However, it is preferable to select the material of the substrate 11 so that the linear
expansion coefficient of the substrate 11 is close to the linear expansion coefficient of the MEMS
chip 12. For example, when the MEMS chip 12 is formed of silicon, it is preferable to select the
material of the substrate so that the linear expansion coefficient of the substrate 11 is about 2.8
ppm / ° C. As described above, by reducing the difference in linear expansion coefficient
between the substrate 11 and the MEMS chip 12, for example, during the reflow process, the
MEMS chip 12 (diaphragm) is derived from the difference in linear expansion coefficient between
the two. The occurrence of stress at 122) can be reduced.
[0036]
Further, in order to make the microphone unit thin, the substrate 11 is preferably a film
substrate having a thickness of, for example, 50 μm or less. In addition, when the substrate 11 is
formed of a film substrate, for example, when a force is applied to the outer peripheral side of the
substrate 11, the outer peripheral side may be mainly deformed (bent) and the deformation on
the central side may be small. . That is, by making the substrate 11 a film substrate, the
advantage that the possibility of generating unnecessary stress in the MEMS chip 12 disposed at
the center side can be reduced is expected, and from such a point of view, the substrate 11 is a
film substrate The merits of
03-05-2019
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[0037]
A wiring pattern (not shown) is formed on the substrate 11. In this wiring pattern, a wiring for
inputting an electric signal obtained by the MEMS chip 12 to the ASIC 13, a wiring for supplying
power to the ASIC 13, and an electric signal obtained after the processing by the ASIC 13 is
performed. Wiring for outputting the signal, wiring for GND connection, and the like are
included.
[0038]
The MEMS chip 12 has a diaphragm that is displaced by sound pressure to convert sound signals
into electrical signals. In the present embodiment, the MEMS chip 12 is made of a silicon chip.
The MEMS chip 12 is a capacitor type microphone having an insulating base substrate 121, a
diaphragm 122, an insulating layer 123, and a fixed electrode 124 as shown in FIG.
[0039]
The base substrate 121 is formed with an opening 121 a having a substantially circular shape in
plan view. The diaphragm 122 provided on the base substrate 121 is a thin film that vibrates
(vibrates in the vertical direction) by receiving a sound pressure, has conductivity, and forms one
end of the electrode. The fixed electrode 124 is disposed to face the diaphragm 122 with the
insulating layer 123 interposed therebetween. Thereby, the diaphragm 122 and the fixed
electrode 124 form a capacitance. A plurality of sound holes are formed in the fixed electrode
124 so that sound waves can pass therethrough, and sound waves coming from the upper side of
the diaphragm 122 reach the diaphragm 122.
[0040]
When sound pressure is applied from the upper surface of the diaphragm 122, the diaphragm
122 vibrates, so the distance between the diaphragm 122 and the fixed electrode 124 changes,
and the capacitance between the diaphragm 122 and the fixed electrode 124 changes. Do.
Therefore, the MEMS chip 12 can convert a sound signal (sound pressure) into an electrical
signal and take it out.
03-05-2019
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[0041]
The configuration of the MEMS chip as the electroacoustic transducer is not limited to the
configuration of this embodiment. For example, in the present embodiment, the diaphragm 122
is lower than the fixed electrode 124, but it is configured such that the opposite relationship to
this (the diaphragm is upper and the fixed electrode is lower) It does not matter.
[0042]
The ASIC 13 is an integrated circuit that amplifies an electrical signal extracted based on a
change in capacitance of the MEMS chip 12. The ASIC 13 may be configured to include a charge
pump circuit and an operational amplifier so that a change in capacitance in the MEMS chip 12
can be accurately obtained. The electrical signal amplified by the ASIC 13 is output to the outside
of the microphone unit 1 through the wiring pattern formed on the substrate 11.
[0043]
In the microphone unit 1 of the first embodiment, the MEMS chip 12 and the ASIC 13 are flip
chip mounted on the substrate 11. However, the present invention is not limited to this
configuration, and the MEMS chip 12 and the ASIC 13 may of course be mounted on the
substrate 11 by wire bonding technology.
[0044]
The top case 14 is disposed to cover the upper surface 11 a on which the MEMS chip 12 and the
ASIC 13 of the substrate 11 are mounted, and forms a substantially rectangular parallelepiped
internal space 20 in which the MEMS chip 12 and the ASIC 13 are accommodated. The top case
14 of the present embodiment is substantially the same size as the substrate 11 in plan view. The
top case 14 is mounted on a buffer member 17 (details will be described later) provided on the
upper surface of the substrate 11 (that is, the top case 14 and the substrate 11 are not in contact
with each other). It arranges so that the upper surface 11a of may be covered.
03-05-2019
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[0045]
The top case 14 is formed with a through hole 14 a having an opening having a substantially
circular shape in plan view on the top surface. The through hole 14 a functions as a sound hole
for introducing an external sound pressure generated outside the microphone unit 1 into the
internal space 20. Hereinafter, the through holes 14a will be referred to as sound holes 14a.
[0046]
Such top case 14 can be formed of, for example, a resin. The microphone unit 1 is mounted on a
mounting substrate (not shown) of the voice input device by, for example, a reflow process. The
reflow process is performed at a high temperature of about 270 ° C., for example. Therefore,
when the microphone unit 1 is mounted by the reflow process, the top case 14 is required to
have heat resistance. In consideration of such a point, the top case 14 is preferably formed of a
heat-resistant resin such as, for example, LCP (Liquid Crystal Polymer; liquid crystal polymer) or
PPS (polyphenylene sulfide).
[0047]
The bottom case 15 has a substantially rectangular parallelepiped housing recess 15a, and the
substrate 11 and the top case 14 are fitted into the housing recess 15a to house the both. When
the accommodation recess 15 a is viewed in plan from above, the size thereof is substantially
equal to the size of the substrate 11 and the top case 14. The substrate 11 accommodated in the
bottom case 15 is disposed such that a buffer member 17 (details will be described later)
provided on the lower surface 11b of the substrate 11 is in contact with the bottom surface 15b
of the accommodation recess 15a. Are disposed in the housing recess 15 a so as not to contact
the bottom case 15.
[0048]
Such bottom case 15 can be formed of, for example, a resin. Similar to the case of the top case 14
described above, the bottom case 15 may be required to have heat resistance, and the bottom
case 15 may be made of, for example, LCP (Liquid Crystal Polymer; liquid crystal polymer) or PPS
(polyphenylene sulfide; polyphenylene). It is preferable to form with resin which has heat
03-05-2019
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resistance, such as sulfide).
[0049]
The bottom case 15 is provided with an electrode terminal (not shown) integrally formed by, for
example, insert molding. The electrode terminals include an electrode terminal for power supply
for supplying electric power to the microphone unit 1, an electrode terminal for output for
outputting an electric signal obtained by the microphone unit 1, and an electrode terminal for
GND connection. Then, it is possible to supply power source power to the substrate 11 from the
outside of the microphone unit 1 and output an electric signal output from the substrate 11 to
the outside of the microphone unit 1 by these electrode terminals. .
[0050]
As shown in FIG. 3, when assembling the microphone unit 1 of the first embodiment, first, the
substrate 11 on which the MEMS chip 12, the ASIC 13 and the like are mounted is dropped
(inserted) into the housing recess 15a of the bottom case 15. Next, the top case 14 is fitted into
the housing recess 15 a of the bottom case 15 so as to cover the substrate 11. Finally, in order to
prevent sound leakage in the microphone unit 1, for example, as shown in FIG. 1, epoxy resin is
provided on the upper side wall of the bottom case 15 so as to cover the gap formed between the
top case 14 and the bottom case 15. And so forth are adhered. As a result, the microphone unit 1
is obtained in which the substrate 11 on which the MEMS chip 12 and the like are mounted is
contained (accommodated) in the housing formed of the top case 14 and the bottom case 15.
[0051]
In the microphone unit 1 of the first embodiment, the bottom case 15 is prepared, and the
microphone unit can be assembled with the positional relationship between the two as desired,
simply by fitting the substrate 11 and the top case 14 into the bottom case 15. For this reason,
the work efficiency at the time of assembling the microphone unit 1 can be improved.
[0052]
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14
By the way, as shown in FIG. 4, on the upper surface 11 a and the lower surface 11 b of the
substrate 11 of the microphone unit 1, the buffer member 17 is provided on the outer peripheral
side of the substrate 11. Although FIG. 4 shows a configuration in which the respective buffer
members 17 provided on the outer peripheral side of the upper surface 11a and the lower
surface 11b are continuously provided on the entire outer periphery as an example, the present
invention is limited to this configuration. It is not the purpose. That is, the buffer members 17
provided on the outer peripheral side of the upper surface 11a and the lower surface 11b of the
substrate 11 do not have to be continuous, and may be intermittently provided at appropriate
positions on the outer peripheral side.
[0053]
In the microphone unit 1, the buffer member 17 is provided for the purpose of reducing the
stress generated on the substrate 11. Here, as a case where stress is generated on the substrate
11, for example, when assembling the microphone unit 1, the case where the top case 14 is
pressed against the substrate 11 or the microphone unit 1 is subjected to reflow processing on
the mounting substrate of the voice input device. And the like. The stress is generated in the
reflow process because, for example, the linear expansion coefficient between the substrate 11
and the bottom case 15 is different.
[0054]
The buffer member 17 is for reducing the stress generated on the substrate 11 as described
above, and is made of a flexible material so that the force applied to the substrate 11 can be
absorbed. More specifically, as the buffer member 17, a material having a rigidity smaller than
that of the substrate 11, the top case 14 and the bottom case 15 is selected, and for example, a
silicone resin can be selected as a preferable material, and others It is also possible to select a
resin of epoxy resin or epoxy resin.
[0055]
As described above, the microphone unit 1 may be mounted on the mounting substrate of the
voice input device, for example, by a reflow process, and the buffer member 17 has heat
resistance so as to withstand the high temperature environment at the time of the reflow process.
It is preferable to select the material. Further, as the buffer member 17, one having a function as
03-05-2019
15
an adhesive may be selected. Furthermore, it is preferable to select the buffer member 17 having
conductivity. Thus, the wiring for the electric circuit in the microphone unit 1 can be easily
configured.
[0056]
For example, when silicone resin is selected as the buffer member 17, the buffer member 17 can
be in the form of a sheet having adhesiveness on both sides. In this case, for example, as shown
in FIG. 4, the buffer member 17 cut into a desired shape is attached in advance to the upper
surface 11 a and the lower surface 11 b of the substrate 11, and the substrate 11 is inserted into
the bottom case 15. The microphone unit 1 can be easily assembled.
[0057]
In addition, the buffer member 17 is not the meaning limited to the sheet-like thing mentioned
above, for example, may be a liquid thing. In this case, the buffer member 17 in the microphone
unit 1 may be obtained by coating. Further, the microphone unit 1 has a configuration in which
the top case 14 and the bottom case 15 are adhered and fixed (the substrate 11 is also fixed) by
the sealing resin 16, and the buffer member 17 may not necessarily have adhesiveness.
[0058]
As described above, in the microphone unit 1 of the first embodiment, the buffer member 17 is
disposed so as to reduce the contact point between the substrate 11 and the housing (composed
of the top case 14 and the bottom case 15). Then, with this configuration, the stress generated in
the substrate 11 can be reduced, and unnecessary stress can be generated in the MEMS chip 12
as much as possible. That is, according to the microphone unit 1 of the first embodiment, it is
possible to suppress the fluctuation of the microphone sensitivity at the time of assembling the
microphone unit 1 or the like.
[0059]
Further, since the buffer member 17 is flexible, it is difficult to form a gap in the portion where
03-05-2019
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the buffer member 17 and each member (the substrate 11, the top case 14, and the bottom case
15) contact. For this reason, although depending on the arrangement of the buffer member 17, it
is expected that the sealing performance is improved by the buffer member 17 to reduce the
acoustic leak. Moreover, it is also possible to set it as the structure which does not provide the
sealing resin 16 in the microphone unit 1 using the sealing performance of the buffer member
17, and can also aim at the improvement of productivity.
[0060]
(Modification of Microphone Unit of First Embodiment) In the microphone unit 1 of the first
embodiment, the buffer member 17 may be disposed to reduce the stress generated in the
substrate 11 in relation to the housing, The configuration is not limited to the configuration
shown in one embodiment, and the configuration can be modified. That is, in order to reduce the
stress generated in the substrate 11, the buffer member 17 may be disposed so as to reduce the
contact point between the substrate 11 and the housing. Hereinafter, this modification will be
described.
[0061]
FIG. 5 is a schematic cross-sectional view showing a first modified example of the microphone
unit of the first embodiment. In the first modification, the buffer member 17 is disposed only
between the substrate 11 and the top case 14, and the substrate 11 and the top case 14 are not
in contact with each other. That is, also in this case, the buffer member 17 is disposed so as to
reduce the contact point between the substrate 11 and the housing, and the stress generated in
the substrate 11 can be reduced by the buffer member 17.
[0062]
FIG. 6 is a schematic cross-sectional view showing a second modification of the microphone unit
of the first embodiment. In the second modification, the buffer member 17 is disposed only
between the lower surface 11 a of the substrate 11 and the bottom surface 15 b of the
accommodation recess 15 a of the bottom case 15. And the buffer member 17 is provided over
the wide area (whole area or substantially whole area) of the lower surface 11 b of the substrate
11. Thereby, the lower surface 11b of the substrate 11 and the bottom case 15 are not in contact
with each other. That is, also in this case, the buffer member 17 is disposed so as to reduce the
03-05-2019
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contact point between the substrate 11 and the housing, and the stress generated in the
substrate 11 can be reduced by the buffer member 17.
[0063]
FIG. 7 is a schematic cross-sectional view showing a third modification of the microphone unit of
the first embodiment. Also in the third modification, as in the second modification, the buffer
member 17 is disposed only between the lower surface 11 a of the substrate 11 and the bottom
surface 15 b of the accommodation recess 15 a of the bottom case 15. However, unlike the
configuration of the second modification, the buffer member 17 provided on the lower surface
11 b side of the substrate 11 is provided only on the outer peripheral side of the substrate 11.
Also in this case, the buffer member 17 is disposed so that the lower surface 11b of the substrate
11 is not in contact with the bottom case 15 and the contact point between the substrate 11 and
the housing is reduced. Can be reduced.
[0064]
In the configuration of the third modification, since the buffer member 17 is provided only on the
outer peripheral side of the substrate 11, a space 23 is formed between the lower surface 11b of
the substrate 11 and the bottom surface 15b of the accommodation recess 15a of the bottom
case 15. Ru. In this case, the space 23 can be used as a back chamber by providing a through
hole (leak hole) penetrating the substrate 11 below the diaphragm 122 of the MEMS chip 12.
Therefore, the volume of the back chamber can be increased, and the microphone sensitivity can
also be improved. In addition, the structure which enlarges the volume of this back chamber is
obtained also by the structure (for example, refer FIG. 2) of 1st Embodiment shown previously.
[0065]
FIG. 8 is a schematic cross-sectional view showing a fourth modification of the microphone unit
of the first embodiment. In the fourth modification, a buffer member 17 is provided between the
side surface 11 c of the substrate 11 and the side surface 15 d of the accommodation recess 15 a
of the bottom case 15. For this reason, the microphone unit of the fourth modification is
provided with a buffer member 17 in contact with the side surface 11c of the substrate 11 in
addition to the upper surface 11a and the lower surface 11b of the substrate 11, and the
substrate 11 has the top case 14 and the bottom case No contact with 15 (ie, the housing).
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[0066]
Also in this case, the buffer member 17 is disposed so as to reduce the contact point between the
substrate 11 and the housing, and the stress generated in the substrate 11 can be reduced by the
buffer member 17. In addition, in the meaning of reducing the stress generated in the substrate
11, it is more preferable to configure so that there is no place where the substrate 11 contacts
the casing as in the present configuration.
[0067]
When the buffer member 17 is disposed between the side surface 11c of the substrate 11 and
the side surface 15d of the accommodation recess 15a of the bottom case 15, the buffer member
17 may be filled with a dispenser or the like.
[0068]
Second Embodiment FIG. 9 is a schematic cross-sectional view showing a configuration of a
microphone unit according to a second embodiment to which the present invention is applied.
In the microphone unit 2 of the second embodiment, the top case 14 is configured not to be
fitted into the bottom case 15 but to cover the bottom case 15 in which the substrate 11 is fitted.
The configuration other than this configuration and the configuration to be changed in
connection with this configuration is the same as that of the microphone unit 1 of the first
embodiment, and the detailed description will be omitted.
[0069]
In the microphone unit 2 of the second embodiment, the substrate 11 does not contact the top
case 14 and does not receive force directly from the top case 14. For this purpose, in the
microphone unit 2, in order to reduce the stress generated on the substrate 11 due to the
relationship with the housing, the buffer member 17 is reduced so as to reduce the contact point
between the substrate 11 and the bottom case 15. It should be arranged. Therefore, the buffer
member 17 is disposed between the lower surface 11 b of the substrate 11 and the bottom
03-05-2019
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surface 15 b of the accommodation recess 15 a of the bottom case 15.
[0070]
In this microphone unit 2, unlike the microphone unit 1 of the first embodiment, the top case 14
does not hold the substrate 11 and fix it. For this reason, in the microphone unit 2, the buffer
member 17 preferably has a function as an adhesive in order to bond the substrate 11 and the
bottom case 15.
[0071]
In the second embodiment, the buffer member 17 disposed between the lower surface 11b of the
substrate 11 and the bottom surface 15b of the accommodation recess 15a of the bottom case
15 is disposed on the outer periphery of the substrate 11. As shown in the second modification
of the embodiment, it may be provided over a wide range of the lower surface 11 b of the
substrate 11. Furthermore, as in the fourth modification of the first embodiment, the buffer
member 17 may be disposed between the side surface 11 c of the substrate 11 and the side
surface 15 d of the accommodation recess 15 a of the bottom case 15.
[0072]
According to the microphone unit 2 of the second embodiment, for example, when the
microphone unit 2 is mounted on the voice input device by the reflow process, the stress
generated on the substrate 11 can be reduced. That is, according to the microphone unit 2 of the
second embodiment, it is possible to suppress the fluctuation of the microphone sensitivity at the
time of mounting the microphone unit 2 or the like.
[0073]
Third Embodiment FIG. 10 is a schematic perspective view showing an appearance configuration
of a microphone unit according to a third embodiment to which the present invention is applied.
FIG. 11 is a cross-sectional view taken along the line B-B in FIG. The microphone unit 3 of the
third embodiment will be described with reference to FIGS. 10 and 11.
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20
[0074]
The microphone units 1 and 2 of the first and second embodiments are configured to vibrate the
diaphragm 122 by the sound pressure input from the upper surface of the diaphragm 122 and to
extract an electrical signal. On the other hand, the microphone unit 3 of the third embodiment
has a configuration (differential microphone unit) for vibrating the diaphragm 122 by the
difference between the sound pressures input from the upper surface and the lower surface of
the diaphragm 122 and extracting an electric signal It has become. The third embodiment is an
embodiment in which the present invention is applied to such a differential microphone unit.
[0075]
Similarly to the first and second embodiments, the microphone unit 3 according to the third
embodiment also largely includes the substrate 11 on which the MEMS chip 12 and the ASIC 13
are mounted, and the top case 14 disposed so as to cover the substrate 11. And a box-shaped
bottom case 15 in which the substrate 11 and the top case 14 are accommodated. The top case
14 and the bottom case 15 constitute a housing.
[0076]
Among these, the configurations of the MEMS chip 12 and the ASIC 13 are substantially the
same as the configurations of the first and second embodiments, and the description thereof will
be omitted.
[0077]
The material used for the substrate 11 and the wiring pattern provided on the substrate 11 are
the same as those of the microphone units 1 and 2 of the first and second embodiments, but the
first through holes 11 d and the second through holes are formed in the substrate 11 11e differs
from the microphone units 1 and 2 of the first and second embodiments in that 11e is formed.
The first through holes 11 d are formed on the lower surface side of the diaphragm 122
provided in the MEMS chip 12, and the second through holes 11 e are formed at predetermined
03-05-2019
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intervals with respect to the first through holes 11 d.
[0078]
The material used for the top case 14 is the same as that of the microphone units 1 and 2 of the
first and second embodiments. However, unlike the configurations of the first and second
embodiments, two sound holes 14a and 14b having a substantially elliptical shape in plan view
are formed. The first sound hole 14 a has an opening on the top surface of the top case 14 and
communicates with the recess space 20 of the top case 14. The second sound hole 14 b
communicates the opening on the top surface of the top case 14 with the opening on the bottom
surface. The top case 14 communicates with the second through hole 11 e formed in the
substrate 11 so that the recess space 20 forms an internal space in which the MEMS chip 12 and
the ASIC 13 are accommodated. Be covered.
[0079]
The material used for the bottom case 15 and the point that the bottom case 15 has a
substantially rectangular parallelepiped housing recess 15a and an electrode terminal are the
same as the microphone units 1 and 2 of the first and second embodiments. However, the bottom
case 15 included in the microphone unit 3 of the third embodiment differs from the
configurations of the first and second embodiments in that the groove 15 c is formed on the
bottom surface 15 b of the housing recess 15 a. The groove 15b communicates with the
diaphragm 122 through the first through hole 11d formed in the substrate 11 accommodated in
the accommodation recess 15a, and communicates with the second sound hole 14b through the
second through hole 11e. It is provided as.
[0080]
The sound generated outside the microphone unit 3 of the third embodiment configured as
described above passes through the first sound hole 14a and the internal space 20 and reaches
the upper surface of the diaphragm 122 (first sound path 21). In addition, it reaches the lower
surface of the diaphragm 122 through the second sound hole 14b, the second through hole 11e,
the groove 15c, and the first through hole 11d (second sound path 22). Then, the diaphragm 122
vibrates according to the sound pressure difference between the sound pressure applied to the
upper surface of the diaphragm 122 and the sound pressure applied to the lower surface, and
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the capacitance between the diaphragm 122 and the fixed electrode 124 changes. An electric
signal based on the sound pressure is extracted.
[0081]
By the way, also in the microphone unit 3 of the third embodiment, similarly to the case of the
first embodiment, the buffer member 17 is disposed between the upper surface 11a of the
substrate 11 and the top case 14 so that the top case 14 does not contact. It is done. Further, the
buffer member 17 is disposed between the lower surface 11 b of the substrate 11 and the
bottom surface 15 b of the accommodation recess 15 a of the bottom case 15 so as not to be in
contact with each other.
[0082]
For this reason, for example, the stress generated on the substrate 11 by the external force
applied at the time of assembling the microphone unit 3 can be reduced. Further, for example,
when the microphone unit 3 is mounted on the voice input device by reflow processing, stress
generated in the substrate 11 due to the difference in linear expansion coefficient between the
substrate 11 and the bottom case 15 can be reduced. And, by reducing the stress generated in
the substrate 11 as described above, the stress generated in the MEMS chip 12 can also be
reduced. That is, according to the configuration of the third embodiment, in the differential
microphone unit, a configuration with less variation in microphone sensitivity can be realized.
[0083]
In the case of the third embodiment as well, the arrangement of the buffer member 17 can be
modified in the same manner as the modification shown in the first embodiment.
[0084]
(Others) The embodiment shown above shows the application example of the present invention,
and the scope of application of the present invention is not limited to the embodiment shown
above.
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That is, various changes may be made to the embodiment described above without departing
from the object of the present invention.
[0085]
For example, in the embodiment described above, the MEMS chip 12 and the ASIC 13 are
configured as separate chips, but the integrated circuit mounted on the ASIC 13 is monolithically
formed on the silicon substrate forming the MEMS chip 12 I don't care.
[0086]
Further, in the embodiment described above, the acoustoelectric conversion unit for converting
sound pressure into an electric signal is configured as the MEMS chip 12 formed using
semiconductor manufacturing technology, but is limited to this configuration It is not the
purpose.
For example, the electroacoustic transducer may be a condenser microphone using an electrec
film or the like.
[0087]
Moreover, in the above embodiment, a so-called condenser type microphone is adopted as the
configuration of the electroacoustic transducer (corresponding to the MEMS chip 12 of the
present embodiment) included in the microphone unit. However, the present invention can also
be applied to a microphone unit adopting a configuration other than a condenser microphone.
For example, the present invention can be applied to a microphone unit in which an
electrodynamic (dynamic), electromagnetic (magnetic), piezoelectric or the like microphone is
adopted.
[0088]
Besides, the shape of the microphone unit is not intended to be limited to the shape of the
present embodiment, and of course can be changed to various shapes.
[0089]
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The microphone unit of the present invention is, for example, a voice communication device such
as a mobile phone or transceiver, or a voice processing system adopting a technology for
analyzing the input voice (voice recognition system, voice recognition system, command
generation system, electronic dictionary, translation Devices, voice input remote controllers, etc.,
or recording devices, amplifier systems (loudspeakers), microphone systems, etc.
[0090]
1, 2, 3 Microphone unit 11 Substrate 11a Upper surface of substrate 11b Lower surface of
substrate 11c Side surface of substrate 11d First through hole 11e Second through hole 12
MEMS chip (electro-acoustic transducer) 14 Top case (cover member, housing Part 15 Bottom
case (box-shaped member, part of the housing) 15a Housing recess 15b Bottom of housing
recess 15c Groove 15d Side of housing recess 14a Sound hole, 1st sound hole 14b 2nd sound
hole 17 Buffer member 20 inside Space 21 1st sound path 22 2nd sound path 122 diaphragm
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