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JP2009260924

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DESCRIPTION JP2009260924
An object of the present invention is to provide a miniaturized microphone. A microphone is
formed with a sound hole (1), a substrate (2) having a substrate electrode (10) on the upper
surface, a main body (5) provided on the upper surface of the substrate (2), and a back space (6)
A converter 3 having a vibrating film 7 provided at the bottom of the space 6 and a converter
electrode 8 provided in a region facing the substrate electrode 10 on the lower surface of the
main body 5, a substrate electrode 10 and a converter electrode 8 And a bump 11 for connecting
the two. The vibration film 7 vibrates by the sound entering from the sound hole 1, and the
sound is converted into a signal in the converter 3. [Selected figure] Figure 3
Microphone and method of manufacturing the same
[0001]
The present invention relates to a microphone and a method of manufacturing the same.
[0002]
For example, in mobile devices such as mobile phones, further miniaturization and weight
reduction are required, and in response to such a request, the microphone mounted inside
thereof is also configured to aim at size reduction and weight reduction. There is.
[0003]
Specifically, a converter for converting sound to an electric signal is mounted on a substrate
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having a sound hole, a substrate electrode of the substrate and a vibrator electrode of the
converter are connected by a bonding wire, and a microphone is a substrate module Are trying to
make them smaller and lighter.
Although the target product is different from the microphone, as a similar prior document, there
is Patent Document 1 relating to the miniaturization of the package.
Japanese Patent Application Laid-Open No. 9-92670
[0004]
The problem in the above conventional example is that the miniaturization of the device becomes
insufficient. That is, in the conventional example, as described above, after the converter is
mounted on the substrate, the substrate electrode of the substrate and the vibrator electrode of
the converter are connected by the bonding wire. A large space for drawing the bonding wire is
required, and as a result, the package can not be miniaturized sufficiently. When the prior art
was applied to the microphone as well, the size could not be sufficiently reduced.
[0005]
An object of the present invention is to provide a miniaturized microphone.
[0006]
In order to achieve this object, in the microphone of the present invention, a sound hole is
formed, a substrate having a substrate electrode on the upper surface, a sound pressure is
converted into an electric signal, and a converter provided on the upper surface of the substrate
A shield cap and a bump, wherein the conversion body is provided with a main body in which a
back space is formed, a vibration membrane which is provided at a bottom of the back space of
the main body and receives the sound pressure, and And a converter electrode provided in a
region opposed to the substrate electrode, wherein the shield cap is in contact with the upper
surface and the side surface of the main body and covers the upper portion of the back space;
The substrate electrode and the converter electrode are connected.
[0007]
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With this configuration, the space in front of the diaphragm can be made thinner than in the
prior art without changing the diameter of the sound hole, so the size of the microphone can be
reduced without reducing the sound collecting ability.
Therefore, by using the microphone of the present invention, it is possible to realize a portable
device which is miniaturized and lightened.
[0008]
Further, if the main body of the converter is made of silicon, it is possible to easily manufacture
the microphone by the semiconductor process.
[0009]
The vibrating membrane may be made of silicon, and the main body and the vibrating membrane
may be integrally formed.
[0010]
The back space may penetrate the body and may extend upward from the vibrating membrane.
[0011]
The microphone may further include a resin body covering a portion of the top surface of the
substrate and at least a portion of the outer surface of the shield cap.
By providing the resin body covering the shield cap, the strength of the microphone against
impact is improved, and therefore, the impact resistance of the portable device can be improved
by using the microphone of the present invention.
[0012]
The resin body may cover the side surface of the shield cap.
[0013]
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You may further provide the amplification element which amplifies the signal produced |
generated by the said conversion body.
[0014]
The substrate may have mounting terminals provided on its lower surface.
[0015]
If the volume of the back space is larger than the volume of the space from the lower surface of
the vibrating membrane to the sound hole, it is preferable because the vibrating membrane easily
vibrates in a wide frequency band while securing the sound collecting capability.
[0016]
The method for manufacturing a microphone according to the present invention prepares a
converter having a main body in which a back space is formed, a vibrating membrane provided
on the bottom of the back space, and a converter electrode provided on the lower surface of the
main body. Step (a): the conversion body is placed on a substrate having a substrate electrode
formed at a position corresponding to the conversion body electrode on the upper surface where
a sound hole is formed, and the conversion body electrode and the substrate electrode are
connected And (c) placing on the substrate a shield cap covering the upper part of the back space
in contact with the upper surface and the side surface of the main body after the step (b).
[0017]
By this method, a small sized microphone can be manufactured.
[0018]
In the step (b), the converter electrode and the substrate electrode may be connected by
ultrasonic thermocompression bonding.
[0019]
Impact resistance can be obtained by further comprising a step (d) of sealing a part of the upper
surface of the substrate and at least a part of the outer surface of the shield cap with a resin after
the step (c). An improved microphone can be manufactured.
[0020]
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The step (a) may include the step (a1) of forming the inverted pyramidal back space by
selectively wet etching the central portion of the silicon plate.
[0021]
In the step (a1), the vibration film may be integrally formed with the main body by stopping the
wet etching before the back space penetrates the main body.
[0022]
As described above, according to the microphone of the present invention, the space in front of
the diaphragm can be made thinner than before without changing the diameter of the sound
hole, so the size of the microphone can be reduced without reducing the sound collecting ability.
be able to.
Therefore, by using the microphone of the present invention, it is possible to realize a portable
device which is miniaturized and lightened.
[0023]
Hereinafter, an embodiment of the present invention will be described with reference to the
attached drawings.
[0024]
FIG. 1 is a plan view showing the upper surface side of the microphone according to the
embodiment of the present invention, FIG. 2 is a plan view showing the lower surface side of the
microphone according to the present embodiment, and FIG. FIG. 3 is a cross-sectional view of the
microphone taken along line III-III in FIG.
[0025]
As shown in FIGS. 1 to 3, the microphone of this embodiment includes a rectangular substrate 2
having a circular sound hole 1, a converter 3 disposed on the substrate 2, and the substrate 2
and the converter 3. An amplification element 4 sealed by a resin body 14 is provided.
[0026]
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5
The converter 3 has a main body 5, a vibrating membrane 7 and a converter electrode 8.
The main body 5 is made of, for example, silicon, and has a square shape as viewed from above
the substrate 2.
The vibrating membrane 7 is connected to the main body.
The converter electrode 8 is provided on the lower surface of the main body 5.
Further, in the main body 5, a back space that spreads like an inverted pyramid from the position
where the vibrating membrane 7 is provided upward is formed.
[0027]
Although not shown, a piezoelectric body is attached to the vibrating membrane 7. The
piezoelectric body converts the sound (sound pressure) into an electric signal by vibrating the
vibrating membrane 7 by the sound entering from the sound hole 1 The converted electric signal
is amplified by the amplification element 4 and then output from the mounting terminal 9 of the
substrate 2 to a control circuit of an electronic device such as a mobile phone.
The piezoelectric body may be provided on either the upper surface or the lower surface of the
vibrating film 7.
Furthermore, an electret may be used instead of the piezoelectric body.
Alternatively, the vibrating membrane 7 may be one of the electrodes, and a capacitor for
converting sound pressure into an electric signal may be provided.
[0028]
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In addition, a substrate electrode 10 is formed at a position facing the converter electrode 8 on
the upper surface of the substrate 2, and the substrate electrode 10 and the converter electrode
8 are electrically connected to each other through the bumps 11. There is.
The substrate electrode 10 and the mounting terminal 9, and the substrate electrode 10 and the
amplification element 4 are appropriately connected by the pattern 12 in the substrate 2.
As a result, when the sound entering from the sound hole 1 is converted into an electric signal by
the diaphragm 7, the electric signal is amplified by the amplification element 4 and then the
mounting terminal 9 of the substrate 2 It is output to the control circuit.
[0029]
The microphone of the present embodiment is provided with a shield cap 13 in close contact
with the upper surface and the side surface of the converter 3 (main body 5) so as to cover the
upper part of the back space 6 formed in the converter 3.
That is, as shown in FIG. 3, the upper surface and the side surface of the main body 5 of the
converter 3 are covered by the metal shield cap 13, whereby the intrusion of external noise
components from the upper surface side of the main body 5 is suppressed. ing.
Furthermore, by covering the upper surface side of the main body of the conversion body 3 with
the shield cap 13 in this manner, the size of the back space 6 is fixed, and thereby the acoustic
characteristics are stabilized.
Further, by the shield cap 13 being in direct contact with the main body 5, the potential of the
main body 5 can be stabilized via the shield cap 13, and a microphone resistant to disturbance
noise can be realized.
Moreover, the rear space can be made smaller by installing the shield cap 13 in direct contact
with the main body 5 as compared with the configuration in which the shield cap is covered on
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the substrate on which the conventional microphone is mounted, and the entire module is
miniaturized Can be
In the description of the present embodiment, the “side surface of the main body 5” means the
outer side surface of the main body 5 and does not mean the surface facing the back space 6
unless otherwise specified.
[0030]
Then, after the shield cap 13 is formed, the upper surface of the substrate 2 and the upper
surface and the side surface of the main body 5 are sealed together with the amplifying element
4 with the resin body 14, whereby the substrate 2 and the converter 3 are integrated and
converted. The body 3 and the amplification element 4 are protected.
[0031]
Now, in the state where the substrate 2 and the conversion body 3 are integrated in this way, the
back space 6 formed in the main body 5 of the conversion body 3 is a portion of the substrate 2
from the lower surface of the diaphragm 7 in contact with the back space 6. The volume is larger
than the front space 15 formed by the sound holes 1 on the lower surface.
[0032]
This is because as the back space 6 is larger, the vibrating membrane 7 is more easily vibrated,
and the frequency band in which the vibration is performed is also wider.
The front space 15 of the vibrating membrane 7 is opened in the back space 6 of the volume Va,
and when sound enters from the front space 15, air in the space is compressed by the piston
effect. As a result, the vibrating membrane 7 vibrates.
[0033]
As shown in FIG. 7, Va (volume of back space 6)> Vb (volume of front space 15 of vibrating
membrane 7).
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Since the front space 15 is mainly intended for the entry of sound, it has a planar size, but the
size in the vertical direction is made as small as possible, thereby reducing the space volume, and
the back space 6 has a vibrating membrane 7. It is preferable to make the space volume as large
as possible so as to facilitate vibration in a wide frequency band.
In the conventional microphone, the relationship of Va (volume of back space) <Vb (volume of
front space 15 of vibrating membrane) was satisfied.
[0034]
In the microphone of this embodiment, as described above, since the substrate 2 having the
sound hole 1 and the conversion body 3 having the main body 5 and the vibrating film 7 are
connected via the bumps 11, compared with the case of using a wire. Thus, the volume of the
front space 15 of the diaphragm 7 can be reduced without narrowing the size of the sound hole
1. Therefore, the size of the microphone can be reduced without degrading the sound collection
function.
[0035]
Furthermore, since the side surface and the upper surface of the shield cap 13 are covered with
the resin body 14, it is difficult to damage not only the impact from the side of the converter 3
but also the impact from above the converter 3 . As described above, since the microphone of the
present embodiment has excellent shock resistance particularly while being downsized and
thinned, it is particularly preferably used for portable communication devices such as mobile
phones that easily cause dropping or the like.
[0036]
Although the resin body 14 may cover the entire side surface of the shield cap 13, the impact
resistance of the microphone is higher than in the case where the resin body 14 is not provided
even if the upper surface and the side surface of the shield cap 13 are covered. Can improve.
[0037]
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FIG.4, FIG.5 and FIG.6 is sectional drawing which shows the manufacturing method of the
microphone of this embodiment.
As shown in FIG. 4, first, the main body 5 made of silicon is wet-etched from above to form the
sound hole 1 penetrating the main body 5 at the central portion. Subsequently, the vibrating film
7 is adhered to the bottom of the sound hole 1. Next, as shown in FIG. 5, with the main body 5 of
the converter 3 placed on the upper surface of the substrate 2, the substrate electrode 10 on the
upper surface of the substrate 2 and the converter electrode 8 of the main body 5 are subjected
to ultrasonic heat Connect by crimping. Next, as shown in FIG. 6, after connecting the substrate
electrode 10 and the converter electrode 8, the main body 5 is covered with the shield cap 13
and sealed with the resin body 14. In this step, the amplification element is also sealed with a
resin body. The shield cap 13 is in close contact with the upper surface and the side surface of
the conversion body 3 (main body 5), and is provided so as to cover the upper portion of the
back space 6. Thus, according to the method of the present embodiment, a microphone can be
manufactured using a semiconductor process.
[0038]
In the present embodiment, the vibrating membrane 7 is formed separately from the converter 3,
but the vibrating membrane 7 and the converter 3 may be integrally formed of silicon. That is, in
the method described above, the back space 6 of the converter 3 is formed by wet-etching the
silicon main body 5 from above, but by stopping this etching in the middle, the vibrating film is
formed on the main body 5 A converter 3 in which 7 are connected in series can be formed.
[0039]
In addition, you may change the position of the constituent material of the microphone of this
embodiment, a member, etc. suitably. For example, the planar shape of the main body 5 may be a
polygon such as a rectangle other than a square, or may be a circle or the like.
[0040]
The substrate electrode 10 and the converter electrode 8 may be connected by a method other
than ultrasonic thermocompression bonding.
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[0041]
-Modification of Microphone-Fig. 8 is a cross-sectional view showing a modification of the
microphone according to the embodiment of the present invention.
[0042]
As shown in the figure, in the microphone shown in FIG. 3, the resin body 14 does not cover the
upper surface of the shield cap 13 but covers only the side surface.
Even in this case, since the resin body 14 improves the strength against the impact applied from
the side of the converter 3, the resin body 14 can be preferably used for communication devices
such as mobile phones.
Further, the microphone according to the present modification can be thinner than the
microphone shown in FIG. 3 because the resin body 14 is not provided on the upper surface of
the shield cap 13.
[0043]
Although the resin body 14 may cover the entire side surface of the shield cap 13, even if a part
of the side surface of the shield cap 13 is covered, the impact resistance of the microphone can
be improved.
[0044]
Alternatively, the resin body 14 may be provided only on the upper surface without being
provided on the side surface of the shield cap 13.
If the resin body 14 covers at least a part of the outer surface (side surface and upper surface) of
the shield cap 13, the strength against impact can be improved.
[0045]
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The microphone of the present invention described above is useful for reducing the size and
weight of a portable device such as a cellular phone that transmits and receives sound.
[0046]
It is a top view showing the upper surface side of the microphone concerning an embodiment of
the present invention.
It is a top view showing the undersurface side of the microphone concerning an embodiment of
the present invention. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2 of a
microphone according to an embodiment of the present invention. It is sectional drawing which
shows the manufacturing method of the microphone which concerns on embodiment of this
invention. It is sectional drawing which shows the manufacturing method of the microphone
which concerns on embodiment of this invention. It is sectional drawing which shows the
manufacturing method of the microphone which concerns on embodiment of this invention. It is
a sectional view of a microphone concerning an embodiment of the present invention. It is a
sectional view showing a modification of a microphone concerning an embodiment of the present
invention.
Explanation of sign
[0047]
DESCRIPTION OF SYMBOLS 1 sound hole 2 board | substrate 3 converter 4 amplifier element 5
main body 6 back space 7 diaphragm 8 converter electrode 9 mounting terminal 10 board
electrode 11 bump 12 pattern 13 shield cap 14 resin body 15 front space
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