JP2008283312A - Pressure transducer device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance reliability of a pressure transducer device and to relax restrictions on a durable environment. <P>SOLUTION: The pressure transducer device comprises a transducer which transduces pressure vibrations into an electric signal, a diaphragm transmitting external pressure vibrations and relaying them to the transducer, and a terminal for taking the electric signal outputted from the transducer out to the outside, and further has a package enclosing the transducer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pressure transducer, and more particularly to its package.

Conventionally, pressure transducers such as a capacitor type, a piezoelectric effect type, and a moving coil type are known. Patent Document 1 discloses a capacitor-type pressure converter. As disclosed in Patent Document 1, a conventional package such as a so-called silicon microphone or electret condenser microphone has a vent hole for propagating sound waves to the diaphragm. This through hole is designed to have a sufficiently high transmittance for audible sound waves.
JP-T-2004-537182

  However, the through holes formed in the package of the pressure conversion device allow moisture and dust to enter the package. In particular, if an attempt is made to increase the transmittance of the through-hole to the audible sound wave, the opening area increases, and moisture and dust easily enter the package. Humidity increases the leakage current between the diaphragm and the electrode plate, thereby degrading the sensitivity characteristics of the pressure transducer. The dust adhering to the diaphragm adversely affects the vibration of the diaphragm. For example, when the dust enters between the diaphragm and the plate, the amplitude of the diaphragm is limited. If the dust is conductive, the characteristics of the signal output from the pressure transducer may be degraded. As described above, the through hole of the package of the pressure conversion device reduces the reliability of the pressure conversion device and restricts the use environment in which the performance is guaranteed (the use environment in which the performance is guaranteed is referred to as the durable environment). It is a factor.

  An object of the present invention is to increase the reliability of a pressure transducer and relax the limitation of the service environment.

(1) A pressure converter for achieving the above object includes a transducer that converts pressure vibration into an electrical signal, a partition that relays external pressure vibration to the transducer, and an electrical signal output from the transducer to the outside. And a package that surrounds the transducer.
According to this pressure conversion device, the package partition wall itself transmits the pressure vibration outside the package and relays it to the transducer, and the transducer outputs the pressure to the electrical signal, and the electrical signal can be taken out from the terminal of the package. In addition, it is not necessary to form a through-hole having a high pressure vibration transmittance in the package. Therefore, by adopting this configuration and eliminating the through hole from the package or reducing the diameter of the through hole, the reliability of the pressure conversion device can be improved and the restriction of the service environment can be relaxed.

(2) In the pressure conversion device for achieving the above object, the transducer is a microphone chip including an electrode plate and a diaphragm forming a counter electrode facing the electrode plate with a gap therebetween. When the diaphragm receives an audible sound wave relayed by the partition wall and vibrates with respect to the electrode plate, the electrical signal corresponding to the audible sound wave is output from the transducer.
According to this pressure transducer, since the package itself transmits audible sound waves and relays to the microphone chip, and the microphone chip outputs an electrical signal corresponding to the audible sound waves relayed by the package, the transmittance of the audible sound waves There is no need to form a high vent in the package. Therefore, by adopting this configuration and eliminating the ventilation hole from the package or reducing the diameter of the ventilation hole, the reliability of the pressure conversion device as a microphone can be improved and the restriction of the service environment can be relaxed.

(3) In the pressure converter for achieving the above object, the package may hermetically surround the transducer.
According to this pressure converter, moisture and dust do not enter the inside of the package.

(4) In the pressure converter for achieving the above object, the package may be provided with a vent having a lower transmission rate of audible sound waves than the partition wall.
According to this pressure conversion device, since the atmospheric pressure can be balanced between the inside and the outside of the package, the manufacturing temperature range such as the solder reflow process and the range of the serviceable temperature during use are expanded.

  (5) In the pressure conversion device for achieving the above object, the package includes a package base part that is joined to an external wiring board and includes the terminal, and a package cover that is joined to the package base part and surrounds the transducer together with the package base part. And the package cover may include a thick part and a thin part that is the partition wall thinner than the thick part.

  The thinner the package is, the higher the pressure vibration transmittance is. However, when the whole is thin, the strength is lowered. Therefore, in this pressure conversion device, the portion for relaying the pressure vibration and the portion for relaying the electrical signal are configured as separate members, thereby increasing the transmittance with respect to the pressure vibration of the package cover that is the portion relaying the pressure vibration. Adopted. That is, the portion where the wiring of the package is formed cannot be made thinner than the other portions and cannot be designed only considering the mechanical characteristics. Are configured as separate members, so that the transmittance of the package cover with respect to the pressure conversion device can be designed to be high. Furthermore, according to this pressure conversion device, the thin portion of the package cover has a higher transmission rate of pressure vibration than the thick portion, and the thick portion of the package cover has higher strength than the thin portion. Therefore, according to this pressure conversion device, the degree of freedom in which the package cover can be designed so that sensitivity and strength are reasonably balanced is increased. Note that the transmittance for a sound wave, which is one of pressure vibrations, is the ratio of the sound pressure inside the package to the sound pressure outside the package.

  (6) In the pressure conversion device for achieving the above object, the package includes a package base that is joined to an external wiring board and includes a terminal, and a package cover that is joined to the package base and surrounds the transducer together with the package base. And an annular region is formed in the annular region of the package cover, and the partition may be a region inside the annular region.

  The thinner the package is, the higher the sound wave transmittance is. However, when the entire package is thin, the strength is lowered. Therefore, in this pressure conversion device, the portion for relaying the pressure vibration and the portion for relaying the electrical signal are configured as separate members, thereby increasing the transmittance with respect to the pressure vibration of the package cover that is the portion relaying the pressure vibration. Adopted. That is, the portion where the wiring of the package is formed cannot be made thinner than the other portions and cannot be designed only considering the mechanical characteristics. Are configured as separate members so that the transmittance of the package cover against pressure vibration can be designed to be high. Further, according to this pressure conversion device, since the annular waveform is formed in the annular region of the package cover, the elastic coefficient with respect to the package base of the package cover is compared with the outer region in the region inside the annular region. Since it becomes large, the transmittance of the sound wave becomes high. That is, since the transmittance of the package cover pressure vibration is higher than when such a ring waveform is not formed on the package cover, the sensitivity can be improved by adopting the configuration of the pressure conversion device.

  (7) In the pressure converter for achieving the above object, the package may include a package base that is bonded to an external wiring board and includes the terminal, and a package cover that is made of a metal material and is the partition wall. Good.

  The thinner the package is, the higher the transmittance of pressure vibration is. However, when the whole package is thin, the strength is lowered. Therefore, in this pressure conversion device, the portion for relaying the pressure vibration and the portion for relaying the electrical signal are configured as separate members, thereby increasing the transmittance with respect to the pressure vibration of the package cover that is the portion relaying the pressure vibration. Adopted. That is, the portion where the wiring of the package is formed cannot be made thinner than the other portions and cannot be designed only considering the mechanical characteristics. Are configured as separate members so that the transmittance of the package cover against pressure vibration can be designed to be high. Further, according to this pressure conversion device, the package cover is made of a metal material, so that it functions as a noise shield. Therefore, according to this pressure converter, the S / N can be increased with a simple structure. The metal material includes a single metal and an alloy.

  (8) In the condenser microphone for achieving the above object, the package may include a package base portion that is bonded to an external wiring board and includes the terminal, and a package cover that is made of plastic and serves as the partition wall.

  The thinner the package is, the higher the transmittance of pressure vibration is. However, when the whole package is thin, the strength is lowered. Therefore, in this pressure conversion device, the portion for relaying the pressure vibration and the portion for relaying the electrical signal are configured as separate members, thereby increasing the transmittance with respect to the pressure vibration of the package cover that is the portion relaying the pressure vibration. Adopted. That is, the portion where the wiring of the package is formed cannot be made thinner than the other portions and cannot be designed only considering the mechanical characteristics. Are configured as separate members so that the transmittance of the package cover against pressure vibration can be designed to be high. Furthermore, according to this pressure converter, since the mass per surface area of the package cover can be reduced, the transmittance of the pressure vibration of the package cover can be increased.

(9) In the pressure converter for achieving the above object, a shield film made of a conductive material may be bonded to at least a part of the package cover.
According to this pressure converter, since the noise shielding effect is obtained by the shielding film made of a conductive material, the S / N can be increased.

(10) In the pressure conversion device for achieving the above object, a breathable member for protecting the package cover may overlap on the surface of the package cover.
According to this pressure conversion device, since the air-permeable member protects the package cover, the strength of the package cover can be reduced and the sound wave transmittance can be increased. That is, by adopting the configuration of this pressure converter, the sensitivity can be improved while maintaining the strength.

(11) In the pressure converter for achieving the above object, the resonance frequency of the package cover may be 3.5 KHz or higher.
When the sound wave frequency becomes higher than the resonance frequency of the package cover, the sound wave transmittance of the package cover decreases. As for the quality of the call sound of a mobile phone or the like, it is sufficient if there is an upper limit of 3.5 kHz. That is, according to this pressure conversion device, since the package cover does not resonate within the range of call sound quality, the conversion efficiency of the sound / electric signal is high.

(12) In the pressure conversion device for achieving the above object, the transducer may include a substrate made of a bulk material, and the electrode plate and the diaphragm may be made of a film deposited on the substrate. .
According to this pressure conversion device, a transducer can be formed by laminating a deposited film on a substrate made of a bulk material. That is, the manufacturing cost of this pressure transducer can be reduced by applying semiconductor process technology. The bulk material is a solid material that is sufficiently thick and large in volume as compared with a deposited film formed by a thin film process and can be handled alone, and is a wafer used to start a thin film process.

Hereinafter, embodiments of the present invention will be described in the following order with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the corresponding component in each figure, and the overlapping description is abbreviate | omitted.
＊＊＊＊＊＊＊＊＊＊＊＊＊
1. First embodiment2. Second embodiment 3. 3. Third embodiment 4. Fourth embodiment 5. Fifth embodiment 6. Sixth embodiment Other Embodiments ***********

1. First Embodiment FIG. 1A is a schematic cross-sectional view showing a condenser microphone 101 as a first embodiment of the present invention, and corresponds to the cut surface 1A shown in FIG. 1B. FIG. 1B is a schematic plan view showing a state where the package cover 3 is removed from the condenser microphone 101.

  A condenser microphone 101 as a pressure conversion device is a so-called silicon microphone in which a microphone chip 2 as a transducer and a driving chip 4 are packaged as a transducer that converts a sound wave, which is vibration of atmospheric pressure, into an electric signal. The package of the condenser microphone 101 includes a package base 6 and a package cover 3.

  The package base 6 is composed of a multilayer wiring board 67 and an annular side wall 60, has a box shape having an opening, and includes a terminal for taking out an electric signal output from the microphone chip 2 to the outside. The side wall 60 is formed integrally with the multilayer wiring board 67 and is made of a ceramic sheet or the like constituting the multilayer wiring board 67. The multilayer wiring board 67 is provided with electrode pads 65 and 68 for electrically connecting the condenser microphone 101 and the external wiring board and joining the condenser microphone 101 to the external wiring board. Electrode pads 65 and 68 as terminals for taking out an electric signal output from the microphone chip 2 to the outside are connected to electrode pads 61, 62 and 63 provided inside the package via through vias 64 and 69. ing. A conductive film 66 that includes the outlines of the microphone chip 2 and the drive chip 4 is formed on the intermediate wiring layer of the package base 6. The conductive film 66 functions as a noise shield for the microphone chip 2 and the drive chip 4.

  The package cover 3 as a partition is a thin plate made of a metal material or plastic. The package cover 3 is joined to the upper end of the side wall 60 of the package base 6 so as to cover the opening of the package base 6 and the microphone chip 2 and the drive chip 4 are hermetically surrounded. An area of the package cover 3 inside the side wall 60 of the package base 6 transmits and relays an audible sound wave that vibrates the diaphragm 22. The material and dimensions of the package cover 3 are designed so as to have a high transmission of audible sound waves, a resonance frequency of 3.5 KHz or higher, and appropriate strength. The reason why the resonance frequency is set to 3.5 KHz or more is that the conversion efficiency of the acoustic / electrical signal is not lowered by resonance in a band necessary for the speech sound quality. When selecting a metal material and a plastic material, generally, the resonance frequency of the package cover 3 can be designed to be less than 3.5 KHz. When plastic is selected as the material for the package cover 3, the audible sound wave transmittance of the package cover 3 is higher than when a metal material is selected. Further, when a metal material is selected as the material of the package cover 3, the strength is increased and the package cover 3 functions as a noise shield. For example, if the material of the rectangular package cover 3 and the package dimensions are designed as follows, the transmittance of the package cover 3 with respect to a sound wave of 1 kHz is 8.3% (−22 dB). Since the thickness of the package base 6 is 0.4 mm on the side wall 60, it does not substantially transmit audible sound waves.

Package cover material: Magnesium alloy Package cover thickness: 0.05mm
Package width (outside dimension): 5.4 mm
Package width (inside dimensions): 4.6 mm
Package length (outer dimensions): 7.4 mm
Package length (inside dimensions): 6.6 mm
Package volume: 4.6 mm ³

  For example, when the material of the rectangular package cover 3 and the dimensions of the package are designed as follows, the transmittance of the package cover 3 with respect to a sound wave of 1 kHz is 13% (−17 dB). Since the thickness of the package base 6 is 0.4 mm on the side wall 60, it does not substantially transmit audible sound waves.

Package cover material: Epoxy resin Package cover thickness: 0.1 mm
Package width (outside dimension): 5.4 mm
Package width (inside dimensions): 4.6 mm
Package length (outer dimensions): 7.4 mm
Package length (inside dimensions): 6.6 mm
Package volume: 4.6 mm ³

  The driving chip 4 is bonded to the package base 6 and is electrically connected to the microphone chip 2 by wires 71 bonded to the electrode pads 25, 26, 27, 44, 45, 46, and the electrode pads 41, 42, 43, They are electrically connected to the package base 6 by wires 72 bonded to 61, 62 and 63. The drive chip 4 includes a stabilized power supply circuit (not shown) for applying a stable bias to either the diaphragm 22 or the electrode plate 21 and an impedance converter (not shown) for reducing the output impedance of the microphone chip 2.

  The microphone chip 2 includes a substrate 24 made of a bulk material such as a silicon wafer bonded to the package base 6, a diaphragm 22 made of a film laminated on the substrate 24, a spacer 23, and an electrode plate 21. . The electrode plate 21 and the diaphragm 22 are made of a conductive film such as polycrystalline silicon doped with phosphorus. The spacer 23 is made of an insulating film such as a silicon oxide film. The components of the microphone chip 2 stacked on the substrate 24 are formed on a wafer such as silicon by using deposition, photolithography, and etching. Therefore, the production of a large number of microphone chips 2 can proceed in parallel.

  Since a gap is formed between the diaphragm 22 and the electrode plate 21 by the spacer 23, the diaphragm 22 forms a counter electrode of the electrode plate 21. Since a large number of air holes (not shown) are formed in the electrode plate 21, sound waves that have passed through the air holes of the electrode plate 21 propagate to the diaphragm 22. The back cavity 28 communicates with the external space of the microphone chip 2 through a vent hole (not shown). The diaphragm 22 vibrates when it receives an audible sound wave relayed by the package cover 3. When the diaphragm 22 is vibrated by receiving an audible sound wave relayed by the package cover 3, the capacitance formed by the electrode plate 21 and the diaphragm 22 changes, and an electric signal corresponding to the audible sound wave received by the diaphragm 22 is a microphone chip. 2 is output.

  In this embodiment, since there is no air hole for taking in sound waves inside the package, sound waves attenuated by being relayed by the package cover 3 reach the microphone chip 2. On the other hand, no wind pressure is applied to the microphone chip 2 because the package has no vent hole. Therefore, the diaphragm 22 is not destroyed by the wind pressure, and the diaphragm 22 and the electrode plate 21 are not joined. Therefore, the diaphragm 22 can be designed to be thinner and more flexible and the sensitivity of the microphone chip 2 can be increased. As a result, it is possible to suppress the sensitivity reduction caused by the sound wave attenuation by the package cover 3 by increasing the sensitivity of the microphone chip 2. As a result, according to the present embodiment, while ensuring the function as a condenser microphone, it is possible to improve the reliability and relax the limitation of the durable environment.

2. Second Embodiment FIGS. 2 and 3 are schematic cross-sectional views showing a condenser microphone 102 as a second embodiment of the present invention, and each correspond to the cut surface 1A of FIG. 1B.

  A vent hole 31 may be formed in the package as shown in FIG. It is desirable that the diameter of the vent hole 31 be as small as possible and that the pipe length be long. That is, even if the vent hole 31 is formed in the package, it is desirable to form the package so that the inside is substantially sealed (for example, liquid-tight). The vent hole 31 can be formed, for example, by forming a groove at the end of the package cover 3 and bonding the package cover 3 and the package base 6 so as to avoid the groove. Moreover, as shown in FIG. 3, a hollow tube such as a hollow quartz fiber may be embedded in the adhesive layer 32 between the package base 6 and the package cover 3, or may be embedded in the package base 6 itself. The material of the package cover 3 is not limited to metal and may be plastic.

  When the vent hole 31 is formed by a groove having a rectangular cross section as shown in FIG. 2, the relationship between the dimension of the vent hole 31 and the transmittance for sound waves of 100 Hz is as follows. The transmittance for sound waves of 100 Hz or higher is further reduced. The package dimensions are the same as in the first embodiment.

(Example 1)
Tube length (L): 0.4mm
Tube width: 0.03mm
Tube depth (H): 0.025 μm
Ventilation rate of vent: -19 dB

  When the vent hole 31 is formed of quartz fiber having a circular pipe cross section as shown in FIG. 3, the relationship between the dimension of the vent hole 31 and the transmittance with respect to a sound wave of 100 Hz is as follows. The transmittance for sound waves of 100 Hz or higher is further reduced. The package dimensions are the same as in the first embodiment.

(Example 2)
Tube length (L): 0.4mm
Diameter (R): 28 μm
Ventilation rate of ventilation hole: -20 dB

(Example 3)
Tube length (L): 0.4mm
Diameter (R): 20 μm
Ventilation rate of ventilation hole: -30dB

  By forming the air holes 31 in the package, the air pressure inside and outside the package is balanced, so that the package can be prevented from being damaged due to a difference in air pressure. For example, by forming the air holes 31 in the package, the temperature of the solder reflow process for joining the package base 6 to the external wiring board can be set high. Since the package cover 3 itself as a partition wall transmits the audible sound wave and relays it to the microphone chip 2, the audible sound wave transmittance of the vent hole 31 may be designed as low as possible. That is, the transmittance of the audible sound wave through the vent hole 31 can be made lower than the transmittance of the package cover 3 itself.

3. Third Embodiment FIG. 4 is a schematic cross-sectional view showing a condenser microphone 103 as a third embodiment of the present invention, and corresponds to the cut surface 1A of FIG. 1B.

  When the package cover 3 is made of plastic, it is desirable to bond a conductive shield film 33 such as metal to either the front or back surface of the package cover 3 as shown in FIG. In this case, the shield film 33 desirably has a shape including at least the outlines of the microphone chip 2, the drive chip 4, and the wires 71 and 72. The shield film 33 is preferably thin and vibrates completely integrally with the package cover 3. Such a shield film 33 can be formed by CVD, electroless plating, powder coating, or the like.

  Since the microphone chip 2 has high impedance, the S / N of the condenser microphone 103 can be remarkably improved by providing such a shield film 33.

4). Fourth Embodiment FIG. 5 is a schematic cross-sectional view showing a condenser microphone 104 as a fourth embodiment of the present invention, and corresponds to the cut surface 1A shown in FIG. 1B.

  From the viewpoint of increasing the transmittance of sound waves, the portion where the sound waves are relayed is preferably as thin and wide as possible, but the strength of the portion decreases as the thickness becomes thinner and wider. Therefore, as shown in FIG. 5, the design freedom of the package cover 3 may be increased by forming a thick portion 36 and a thin portion 37 in the package cover 3. For example, the thickness and thickness of the thick portion 36 are neglected by the sound wave relay function, and the shape and thickness are designed with an emphasis on strength, and the thin portion 37 is secured with sufficient strength to withstand wind pressure and impact while being able to withstand audible sound waves. It is desirable to design the shape and thickness so as to maximize the transmittance. The material of the package cover 3 is not limited to metal and may be plastic.

5. Fifth Embodiment FIG. 6 is a schematic sectional view showing a condenser microphone 105 as a fifth embodiment of the present invention, and corresponds to the cut surface 1A of FIG. 1B.

  As shown in FIG. 6A, a breathable member 34 that transmits sound waves with a high transmittance and obtains an appropriate rigidity may be provided on the surface of the package cover 3. Thereby, since the package cover 3 is protected by the air-permeable member 34, it is possible to prevent an external force from being applied to the thin portion 37 of the package cover 3 and to prevent the thin portion 37 from being damaged. The breathable member 34 only needs to overlap the thin portion 37 of the package cover 3, and does not need to overlap the entire package cover 3. As a material of the air-permeable member 34, for example, a metal plate in which a plurality of small through holes are formed, a porous material, a metal net or the like can be used. The material of the package cover 3 is not limited to metal and may be plastic. Note that a gap 35 is provided between the thin portion 37 that relays the sound wave and the air-permeable member 34 so as not to limit the vibration of the portion of the package cover 3 that relays the sound wave.

  6B, the overall thickness of the package cover 3 is reduced, and the package cover 3 and the air permeability are interposed via a spacer 38 for forming a gap 35 between the package cover 3 and the air permeable member 34. The member 34 may be joined.

6). 6th Embodiment FIG. 7A is typical sectional drawing which shows the condenser microphone 106 as 6th Embodiment of this invention, and respond | corresponds to the cut surface 7A shown to FIG. 7B. FIG. 7B is a schematic plan view showing the condenser microphone 101.

  In order to increase the transmittance of the portion of the package cover 3 that relays the sound wave, it is desirable to form an annular waveform in the annular region 39 of the package cover 3 as shown in FIGS. 7A and 7B. By forming an annular waveform in the annular region 39, an elastic coefficient based on the package base 6 of the relay unit 30 that is an inner region of the annular region 39 is increased, and the transmittance of the relay unit 30 to audible sound waves is increased. Therefore, the sensitivity of the condenser microphone 106 is improved.

Further, by reducing the thickness of the annular region 39 with respect to the thickness of other portions of the package cover 3, the transmittance of the package cover 3 with respect to audible sound waves can be increased while suppressing the area of the thin portion. .
The material of the package cover 3 is not limited to metal and may be plastic.

6). Other Embodiments The technical scope of the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention. For example, you may combine any one of 2nd embodiment which provides a vent hole in a package, and 3rd embodiment to 6th embodiment. Further, the package base 6 may be one in which a lead frame is sealed with resin. Further, as for the positional relationship between the diaphragm 22 and the electrode plate 21 with respect to the substrate 24, any of them may be arranged closer to the substrate 24. When the electrode plate 21 is disposed closer to the substrate 24, the air holes of the electrode plate 21 serve to communicate the gap between the diaphragm 22 and the electrode plate 21 and the back cavity 28. Further, the package cover 3 may have a box shape with a bent periphery. Further, the package cover 3 may constitute only a part of one surface of a substantially rectangular parallelepiped package. That is, for example, a through hole may be formed in a plate-like portion of the package base 6, and the package cover 3 may be joined to the package base 6 so as to close the through hole. Further, the microphone chip 2 and the driving chip 4 may be integrated or may be stacked.

In the above embodiment, a so-called silicon microphone chip is used as the transducer. However, any transducer may be used as long as the transducer converts pressure vibration into an electric signal.
As a first modification, it is possible to use a transducer using an electrostatic capacitor whose output voltage varies when a diaphragm in which static electricity is stored in advance moves due to pressure variation. A transducer using an electrostatic capacitor is likely to be affected by the external environment because charges are stored in the diaphragm in advance. However, the transducer surrounded by the package used in the present invention is not easily affected by the external environment and can increase the sensitivity of the diaphragm, so that the reliability is enhanced while the function is secured, and the limitation of the durable environment is relaxed. I can do it.
As a second modification, a piezoelectric effect type transducer that converts the displacement of the diaphragm into an electric signal by a piezoelectric element can be used. Unlike the capacitor type, the piezoelectric effect type transducer does not require an electrode plate facing the diaphragm, so that in principle the amplitude of the diaphragm can be increased. However, in reality, the diaphragm amplitude cannot be increased in order to prevent destruction due to wind pressure or the like, and the sensitivity of the piezoelectric effect transducer is low. In the package used in the present invention, an external force other than sound waves such as wind pressure is not applied to the diaphragm or is not easily applied. Therefore, the sensitivity can be increased by applying the present invention to a piezoelectric effect type transducer and designing the diaphragm to be flexible.
As a third modification, a moving coil type transducer that includes a coil, a permanent magnet, and a diaphragm, and generates an output voltage when the coil attached to the diaphragm moves in the vicinity of the permanent magnet may be used. In a moving coil type transducer, the sensitivity can be increased by adjusting the density of the coil and the strength of the permanent magnet.
The materials, dimensions, and film forming methods shown in the above embodiment are merely examples, and descriptions of manufacturing methods that are obvious to those skilled in the art are omitted.

(1A) is typical sectional drawing concerning 1st embodiment of this invention. (1B) is a schematic plan view according to the first embodiment of the present invention. The typical sectional view concerning a second embodiment of the present invention. The typical sectional view concerning a second embodiment of the present invention. The typical sectional view concerning a third embodiment of the present invention. Typical sectional drawing concerning 4th embodiment of this invention. (6A) And (6B) is typical sectional drawing concerning 5th embodiment of this invention. (7A) is a schematic sectional view according to a fifth embodiment of the present invention. (7B) is a schematic plan view according to the fifth embodiment of the present invention.

Explanation of symbols

2: microphone chip, 3: package cover, 4: drive chip, 6: package base, 21: electrode plate, 22: diaphragm, 23: spacer, 24: substrate, 25: electrode pad, 28: back cavity, 30: relay Part, 31: vent hole, 32: adhesive layer, 33: shield film, 34: breathable member, 35: gap, 36: thick part, 37: thin part, 38: spacer, 39: annular region, 41: electrode Pad: 60: Side wall, 61, 62, 63: Electrode pad, 64, 69: Through via, 65, 68: Electrode pad, 66: Conductive film, 67: Multilayer wiring board, 71: Wire, 72: Wire, 101: Condenser microphone, 102: Condenser microphone, 103: Condenser microphone, 104: Condenser microphone, 105: Condenser microphone , 106: condenser microphone

Claims (12)

A transducer that converts pressure vibrations into electrical signals;
A partition wall that transmits external pressure vibrations and relays to the transducer;
A terminal for taking out an electrical signal output from the transducer;
And a package surrounding the transducer;
A pressure conversion device comprising: The transducer is
An electrode plate;
A diaphragm forming a counter electrode facing the electrode plate with a gap in between;
A microphone chip comprising:
When the diaphragm vibrates with respect to the electrode plate by receiving an audible sound wave relayed by the partition, the electrical signal corresponding to the audible sound wave is output from the transducer.
The pressure converter according to claim 1. The package hermetically surrounds the transducer;
The pressure converter according to claim 1 or 2. In the package, a vent hole having a lower transmission of audible sound waves than the partition wall is formed.
The pressure converter according to claim 1 or 2. The package is
A package base bonded to an external wiring board and provided with the terminals;
A package cover joined to the package base and surrounding the transducer with the package base;
With
The package cover is
The thick part,
A thin part that is the partition wall thinner than the thick part,
The pressure converter as described in any one of Claims 1-4. The package is
A package base bonded to an external wiring board and provided with the terminals;
A package cover joined to the package base and surrounding the transducer with the package base;
With
An annular waveform is formed in the annular region of the package cover,
The partition is a region inside the annular region,
The pressure converter as described in any one of Claims 1-4. The package is
A package base bonded to an external wiring board and provided with the terminals;
A package cover made of a metal material and serving as the partition wall;
Comprising
The pressure converter as described in any one of Claims 1-4. The package is
A package base bonded to an external wiring board and provided with the terminals;
A package cover made of plastic and serving as the partition;
Comprising
The pressure converter as described in any one of Claims 1-4. A shield film made of a conductive material is bonded to at least a part of the package cover;
The pressure conversion device according to claim 8. A breathable member for protecting the package cover is overlaid on the surface of the package cover.
The pressure converter according to claim 8 or 9. The resonance frequency of the package cover is 3.5 KHz or more.
The pressure converter as described in any one of Claims 5-10. The transducer comprises a substrate of bulk material;
The electrode plate and the diaphragm are made of a film deposited on the substrate.
The pressure conversion device according to claim 2.

Images