JP2006311105A - Acoustical sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic sensor in which desired frequency characteristics can be derived with good repeatability while a miniaturization is attained. <P>SOLUTION: The acoustic sensor includes a shielding case 5 by which sealing is performed to a printed circuit board 2 so that a hydrophone element 1 and an electronic part 3 may be surrounded between printed circuit boards 2 as circuit substrates. The hydrophone element 1 is an electrostatic capacity type hydrophone element with which a backing-plate part 14 is formed in the rear face side of a diaphragm-like vibration cone part 12 through a spacer part 13. In the shielding case 5, a sound hole 51 is formed in the front wall 5a which counters the vibration cone part 12 of the hydrophone element 1, and intersects an overlap region of the hydrophone element 1 of the hydrophone element 1 on the rear surface of the front wall 5a. A channel 52 for ventilation is formed to communicate with a space between the hydrophone element 1 and the printed circuit board 2 and the sound hole 51 between the hydrophone element 1 and the printed circuit board 2, the supporting part 11 of the hydrophone element 1 is adhered to the rear surface of the front wall 5a with resin for sealing except the part superposed with the channel 52 for the ventilation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a small acoustic sensor used for voice input applications such as a mobile phone and a hearing aid.

  Conventionally, a capacitive receiving element having a diaphragm and a back plate, and an electronic component that is disposed on the rear side of the receiving element and that processes a received signal output from the receiving element, An acoustic sensor comprising a circuit board made of a printed circuit board mounted on the opposite surface side of the substrate and a shield case sealed on the circuit board so as to surround the wave receiving element and the electronic component between the circuit board and the circuit board is proposed. (For example, refer to Patent Document 1).

  Here, the shield case in the acoustic sensor disclosed in Patent Document 1 has a sound hole formed in the front wall facing the diaphragm of the wave receiving element, and the wave receiving element and the circuit board on the rear surface of the front wall. A ventilation groove is formed to communicate the space between and the sound hole. In the acoustic sensor disclosed in Patent Document 1, since the ventilation groove described above is formed, air generated due to heat generation of the electronic component disposed in the space between the wave receiving element and the circuit board is formed. It is possible to suppress the frequency characteristics from fluctuating due to expansion and contraction.

Conventionally, as a wave receiving element, for example, a movable substrate comprising a diaphragm-like diaphragm portion formed by processing a silicon substrate or the like by a micromachining technique or the like and continuously formed integrally inside a frame-like support portion. There has been proposed a capacitive receiving element in which a fixed electrode made of a back plate portion is provided on a rear surface side of an electrode via a spacer portion made of an insulating material (see, for example, Patent Document 2).
JP-A-6-339192 (paragraphs [0002]-[0007] and FIG. 5) JP 2003-31820 A (paragraphs [0002]-[0003] and FIG. 1)

  By the way, in order to reduce the size of the acoustic sensor disclosed in the above-mentioned Patent Document 1, a capacitive type formed using a micromachining technique as described in Patent Document 2 as a receiving element. It is conceivable to use a receiving element.

  However, a ventilation path is formed in a portion other than the ventilation groove due to the difference in flatness between the opposing walls of the front wall of the shield case and the support portion of the wave receiving element, and the acoustic resistance is reduced to the ventilation groove. Acquired knowledge that the cut-off frequency in the low-frequency region becomes higher than the design value because it is lower than the acoustic resistance determined by the shape of the sensor, and the cut-off frequency varies from sensor to sensor, making it impossible to obtain the desired frequency characteristics. It was. The above-mentioned Patent Document 1 also discloses an acoustic sensor that adjusts the acoustic resistance after assembly. However, a bolt or tube for adjusting the acoustic resistance at the time of assembly of the acoustic sensor is attached to the circuit board. Since the work to adjust the acoustic resistance after assembly is necessary, the productivity was low.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide an acoustic sensor capable of obtaining a desired frequency characteristic with good reproducibility while achieving downsizing.

  According to the first aspect of the present invention, there is provided a wave receiving element that receives a sound wave and converts the received sound wave into a wave receiving signal that is an electric signal, and a wave receiving element that is disposed on the rear surface side of the wave receiving element and is output from the wave receiving element. An electronic component constituting a signal processing circuit for processing a wave signal is mounted on the circuit board so as to surround the wave receiving element and the electronic component between the circuit board mounted on the surface facing the wave receiving element and the circuit board. The receiving element is provided with a back plate portion through a spacer portion on the rear surface side of the diaphragm-like diaphragm portion formed continuously and integrally inside the frame-shaped support portion. In addition, the shield case has a sound hole formed in the front wall facing the diaphragm portion of the wave receiving element, and overlaps the support portion of the wave receiving element on the rear surface of the front wall. Crossing the area and communicating the sound hole with the space between the receiving element and the circuit board Ventilation groove is formed, the supporting portion of the wave receiving element on the rear surface of the front wall, characterized in that formed by bonding a resin for sealing except for the portion overlapping with the ventilation groove.

  According to the present invention, since the support portion of the wave receiving element is bonded to the rear surface of the front wall of the shield case with the sealing resin except for the portion overlapping the ventilation groove, the front wall of the shield case and the wave receiving element It is possible to prevent a ventilation path from being formed in a portion other than the ventilation groove due to a difference in flatness of the mutually facing surfaces with the support portion, and a ventilation path is formed in a portion other than the ventilation groove. The acoustic resistance increases and the cut-off frequency decreases, and the variation in the acoustic resistance and cut-off frequency for each acoustic sensor is reduced. Therefore, the desired frequency characteristics can be reproduced while miniaturizing. Can get well.

  According to a second aspect of the present invention, in the first aspect of the invention, the shielding case has an inflow prevention convex portion for preventing inflow of resin into the ventilation groove on both sides in the width direction of the ventilation groove on the rear surface of the front wall. It is characterized by being provided.

  According to the present invention, since the resin can be prevented from flowing into the ventilation groove, it is possible to prevent the frequency characteristics from being varied due to the difference in acoustic resistance caused by the difference in the amount of the resin flowing into the ventilation groove. be able to.

  According to a third aspect of the present invention, in the first aspect of the present invention, the shield case is formed with a resin filling concave portion for filling a sealing resin on the rear surface of the front wall continuously with the ventilation groove, and the ventilation groove. A partition wall that divides the internal space of the resin filling concave portion into two resin filling chambers in the longitudinal direction of the ventilation groove on both sides in the width direction is projected from the inner bottom surface of the resin filling concave portion.

  According to the present invention, the effective length of the ventilation groove can be changed between the case where the resin is filled in only one of the two resin filling chambers during assembly and the case where both are filled with the resin, thereby reducing the acoustic resistance. Since the frequency characteristics can be adjusted, the frequency characteristics can be adjusted.

  According to a fourth aspect of the present invention, there is provided a wave receiving element that receives a sound wave and converts the received sound wave into a wave receiving signal that is an electric signal, and a wave receiving element that is disposed on the rear surface side of the wave receiving element and is output from the wave receiving element. An electronic component constituting a signal processing circuit for processing a wave signal is mounted on the circuit board so as to surround the wave receiving element and the electronic component between the circuit board mounted on the surface facing the wave receiving element and the circuit board. The receiving element is provided with a back plate portion through a spacer portion on the rear surface side of the diaphragm-like diaphragm portion formed continuously and integrally inside the frame-shaped support portion. In addition, the shield case has a sound hole formed in the front wall facing the diaphragm portion of the wave receiving element, and overlaps the support portion of the wave receiving element on the rear surface of the front wall. Crossing the area and communicating the sound hole with the space between the receiving element and the circuit board The ventilation pipe is disposed between the rear wall side of the front wall and the support portion, and the ventilation pipe and the support portion of the wave receiving element are bonded to the rear surface of the front wall with a sealing resin. To do.

  According to the present invention, since the support portion of the wave receiving element is bonded to the rear surface of the front wall of the shield case over the entire circumference by the sealing resin, the front wall of the shield case and the support portion of the wave receiving element are Since it is possible to prevent the formation of a ventilation path other than the internal space of the ventilation pipe due to the difference in flatness between the mutually facing surfaces, the ventilation path is formed in a portion other than the ventilation pipe. As a result, the acoustic resistance increases and the cutoff frequency decreases, and the variation in acoustic resistance and cutoff frequency for each acoustic sensor is reduced. Therefore, the desired frequency characteristics can be obtained with good reproducibility while downsizing. be able to. Moreover, the acoustic resistance can be adjusted by appropriately setting the length and the inner diameter of the ventilation pipe.

  According to a fifth aspect of the present invention, in the fourth aspect of the present invention, the shield case is formed with a positioning groove for positioning the ventilation pipe crossing a region overlapping the support portion of the wave receiving element on the rear surface of the front wall. Features.

  According to the present invention, it is possible to prevent the position of the ventilation pipe from being shifted during assembly, and the assemblability is improved.

  In the present invention, there is an effect that a desired frequency characteristic can be obtained with good reproducibility while achieving miniaturization.

(Embodiment 1)
As shown in FIG. 1A and FIG. 2, the acoustic sensor of the present embodiment receives a sound wave and converts the received sound wave into a received signal, which is an electrical signal, A plurality of electronic components 3 constituting a signal processing circuit disposed on the rear surface side of the element 1 (the lower surface side in FIG. 1A) and processing the received signal output from the receiving element 1 are Between the printed circuit board 2 mounted on the opposite surface side (the upper surface side in FIG. 1A) and the printed circuit board 2, and is sealed to the printed circuit board 2 so as to surround the wave receiving element 1 and each electronic component 3. And a metal shielding case 5. Examples of the electronic component 3 include a surface-mounted resistor and a surface-mounted capacitor that constitute a noise removal circuit, and an FET for an amplifier circuit.

  The outer peripheral shape of the wave receiving element 1 and the printed circuit board 2 is rectangular, and the shield case 5 is formed in a rectangular box shape with an open rear surface, and a plurality of sounds for introducing sound waves into the front wall 5a. A hole 51 is formed, and the rear end edge of the peripheral wall 5 b is arranged so as to be substantially flush with the mounting surface of the electronic component 3 on the printed circuit board 2. A space between the rear end edge of the shield case 5 and the outer peripheral edge of the printed circuit board 2 is sealed all around by a sealing portion 7 made of a sealing resin (for example, epoxy resin, silicone resin, etc.). Yes. Each sound hole 51 is formed in a circular shape.

  Further, a synthetic resin molded product in which a conductor pattern (electrical wiring) for electrically connecting the wave receiving element 1 and the printed board 2 is formed in the shield case 5 by using a plating technique and a laser processing technique. A three-dimensional circuit board (MID board) 4 is arranged between the wave receiving element 1 and the printed board 2. Here, an opening 42 for securing a storage space for each electronic component 3 and forming the back chamber 6 on the rear surface side of the wave receiving element 1 is formed at the center of the three-dimensional circuit board 4. The planar shape of the circuit board 4 is a rectangular frame.

  The three-dimensional circuit board 4 is disposed on the surface of the printed board 2 facing the wave receiving element 1, and the conductor pattern of the three-dimensional circuit board 4 is electrically connected to the circuit pattern of the printed board 2, and the three-dimensional circuit board is provided. 4 and the peripheral part of the mutually opposing surface of the printed circuit board 2 are sealed with sealing resin.

  In the present embodiment, the printed circuit board 2 forms a circuit board in which the electronic components 3 constituting the signal processing circuit are mounted on the surface facing the wave receiving element 1. A printed circuit board is formed by forming a recess for forming the back chamber 6 instead of providing the opening 42 in the part and changing the pattern design of the conductor pattern as appropriate to mount the electronic component 3 on the inner bottom surface of the recess. If 2 is not used, the three-dimensional circuit board 4 constitutes a circuit board on which the electronic components constituting the signal processing circuit are mounted on the side facing the wave receiving element 1.

  The wave receiving element 1 is an electrostatic capacity type wave receiving element formed by using a micromachining technique applying a semiconductor manufacturing technique, and is a frame-shaped (in this embodiment, a rectangular frame-shaped) support portion 11. A back plate portion 14 is provided on the rear surface (back surface) side of the diaphragm-shaped diaphragm portion 12 formed integrally and continuously on the inner side via a plurality of spacer portions 13 made of an insulating layer (for example, a silicon dioxide layer). An air layer (air gap) 15 is formed between the plate portion 12 and the back plate portion 14. The back plate portion 14 has a plurality of exhaust holes 14a penetrating in the thickness direction so that air passes through the exhaust holes 14a when the vibration plate portion 12 vibrates. Therefore, when the diaphragm 12 is vibrated by receiving the pressure of the sound wave, it can be prevented from being excessively braked by the air layer 15 between the diaphragm 12 and the back plate 14, and a wide frequency band. It is possible to obtain a flat frequency characteristic and a wide dynamic range. The wave receiving element 1 of the present embodiment includes a silicon wafer after a so-called SOI wafer having an insulating film made of a silicon oxide film in the middle in the thickness direction and a silicon wafer are bonded together with a silicon dioxide layer interposed therebetween. Is formed by using a multilayer structure wafer polished to a predetermined thickness (here, the design thickness of the back plate portion 14), and is formed by a part of the silicon layer on the main surface side of the SOI wafer. 12 is doped with impurities in advance to impart conductivity to the diaphragm 12, and the diaphragm 12 constitutes a movable electrode, and the back plate 14 formed by a part of the silicon wafer Conductivity is imparted to the back plate portion 14 by doping impurities in advance, and the back plate portion 14 constitutes a fixed electrode. Here, the structure of the multilayer structure wafer that is the basis of the wave receiving element 1 is not particularly limited. For example, a silicon wafer on which a silicon dioxide layer is formed and a high-concentration impurity layer that is the basis of the diaphragm 12 are formed. You may use what stuck together the silicon wafer.

  In the above-described wave receiving element 1, a capacitor having the diaphragm 12 and the back plate 14 as electrodes is formed. Therefore, when the diaphragm 12 receives the pressure of sound waves, the diaphragm 12 and the back plate 14. And the capacitance of the capacitor having the diaphragm 12 and the back plate 14 as electrodes changes. Therefore, if a DC bias voltage is applied between the pads (not shown) provided on the diaphragm 12 and the back plate 14, a minute voltage change occurs between the pads in accordance with the pressure of the sound wave. Sound waves can be converted into electrical signals. Here, each pad of the wave receiving element 1 and the conductor pattern of the three-dimensional circuit board 4 are electrically connected via a bump (not shown) made of a metal material (for example, gold). The connection is not limited, and an anisotropic conductive adhesive may be used. Here, a recess 43 having an open upper surface and an inner surface is formed in the peripheral portion of the opening 42 in the three-dimensional circuit board 4, and the pad of the back plate 14 is formed at a portion corresponding to the inner bottom surface of the recess 43. And the conductor pattern are connected, and the pad of the diaphragm 12 and the conductor pattern are connected at the peripheral portion of the recess 43. Therefore, a space between the outer peripheral surface of the wave receiving element 1 and the inner peripheral surface of the peripheral wall 5b of the shield case 5 and the back chamber 6 between the peripheral portion of the three-dimensional circuit board 4 and the peripheral portion of the wave receiving element 1. A gap communicating with is formed. In addition, the wave receiving element 1 laminates a movable electrode made of a conductive material (for example, aluminum) without imparting conductivity to the diaphragm portion 12 and does not impart conductivity to the back plate portion 14. A fixed electrode made of a conductive material (for example, aluminum) may be laminated.

  By the way, the shield case 5 intersects a region overlapping the support portion 11 of the wave receiving element 1 on the rear surface of the front wall 5a, and a space between the wave receiving element 1 and the printed board 2 (that is, the back chamber 6) and a sound hole. An elongated ventilation groove 52 for communicating 51 is formed, and the support portion 11 of the wave receiving element 1 is bonded to the rear surface of the front wall 5a with a sealing resin except for a portion overlapping the ventilation groove 52. . In short, in adhering the shield case 5 and the wave receiving element 1 with a sealing resin in the assembly process, for example, as shown in FIG. 1B, a seal applied to the rear surface of the front wall 5a of the shield case 5 After providing the sealing resin portion 8 made of the resin for use, the shield case 5 and the support portion 11 of the wave receiving element 1 may be bonded via the sealing resin portion 8.

  Therefore, in the acoustic sensor of the present embodiment, the support portion 11 of the wave receiving element 1 is bonded to the rear surface of the front wall 5a of the shield case 5 with a sealing resin except for a portion overlapping the ventilation groove 52. Further, it is possible to prevent a ventilation path from being formed in a portion other than the ventilation groove 52 due to a difference in flatness between the opposing surfaces of the front wall 5a of the shield case 5 and the support portion 11 of the wave receiving element 1. Compared with the case where a ventilation path is formed in a part other than the ventilation groove 52, the acoustic resistance is increased and the cutoff frequency is lowered, and the variation in the acoustic resistance and the cutoff frequency for each acoustic sensor is small. Therefore, a desired frequency characteristic can be obtained with good reproducibility while reducing the size. As a result, it is possible to reduce the cost by improving the manufacturing yield.

(Embodiment 2)
The basic configuration of the acoustic sensor of the present embodiment is substantially the same as that of the first embodiment. As shown in FIG. 3, on the both sides in the width direction of the ventilation groove 52 on the rear surface of the front wall 5 a of the shield case 5, By projecting the inflow prevention convex portion 53 that prevents the sealing resin from flowing into the groove 52, a part of the sealing resin portion 8 is prevented from being formed in the ventilation groove 52. There is a feature in the point. Since other configurations are the same as those of the first embodiment, illustration and description thereof are omitted.

  Thus, in the acoustic sensor of the present embodiment, the sealing resin can be prevented from flowing into the ventilation groove 52, which is caused by the difference in the amount of the sealing resin flowing into the ventilation groove 52. It is possible to prevent the frequency characteristics from varying due to the difference in acoustic resistance.

(Embodiment 3)
The basic configuration of the acoustic sensor of the present embodiment is substantially the same as that of the first embodiment, and as shown in FIGS. 4A and 4B, the rear surface of the front wall 5a of the shield case 5 is filled with a sealing resin. The resin filling recess 54 is formed continuously with the ventilation groove 52 and is filled with resin in the longitudinal direction of the ventilation groove 52 (left and right direction in FIG. 4A) on both sides in the width direction of the ventilation groove 52. The partition wall 54b that divides the internal space of the concave portion 54 for use into two resin filling chambers 54a and 54a is characterized in that it protrudes from the inner bottom surface of the concave portion 54 for resin filling. Since other configurations are the same as those of the first embodiment, illustration and description thereof are omitted.

  Therefore, in the acoustic sensor of the present embodiment, at the time of assembly, as shown in FIG. 4C, only one of the two resin filling chambers 54a and 54a is filled with the sealing resin, and the sealing resin portion 8 is filled. (However, in the resin-filling concave portion 54, the internal space is not partitioned by the partition wall 54b is filled with sealing resin over the entire area), as shown in FIG. Thus, when sealing resin is filled in both of the two resin filling chambers 54 and 54a to form the sealing resin portion 8, the internal space of the resin filling recess 54 is partitioned by the partition wall 54b. Since the effective length of the ventilation groove 52 can be changed and the acoustic resistance can be adjusted, the frequency characteristic can be adjusted. it can. 4 (c) and 4 (d), the effective length of the ventilation groove 52 is longer in FIG. 4 (d), and the acoustic resistance is higher.

(Embodiment 4)
The basic configuration of the acoustic sensor of the present embodiment is substantially the same as that of the first embodiment. Instead of forming the ventilation groove 52 described in the first embodiment on the rear surface of the front wall 52 of the shield case 5, FIG. As shown, the rear surface of the front wall 5a of the shield case 5 intersects the region overlapping the support portion 11 of the wave receiving element 1 and communicates the space between the wave receiving element 1 and the printed circuit board 2 with the sound hole 51. The pipe 9 is arranged on the rear surface of the front wall 5a (that is, the ventilation pipe 9 is arranged between the support portion 11 of the wave receiving element 1 on the rear surface side of the front wall 5a) and on the rear surface of the front wall 5a. The difference is that the ventilation pipe 9 and the support portion 11 of the wave receiving element 1 are bonded by a sealing resin. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  Therefore, in the acoustic sensor of the present embodiment, the support portion 11 of the wave receiving element 1 is bonded to the rear surface of the front wall 5a of the shield case 5 over the entire circumference with a sealing resin. It is possible to prevent a ventilation path other than the internal space of the ventilation pipe 9 from being formed due to the difference in flatness between the opposing surfaces of the front wall 5a and the support portion 11 of the wave receiving element 1. Since the acoustic resistance becomes higher and the cut-off frequency is lower than the case where the ventilation path is formed in a portion other than the vent pipe 9, the variation in the acoustic resistance and the cut-off frequency for each acoustic sensor is reduced. Desired frequency characteristics can be obtained with good reproducibility while achieving miniaturization. Moreover, the acoustic resistance can be adjusted by appropriately setting the length and the inner diameter of the ventilation pipe 9.

(Embodiment 5)
The basic configuration of the acoustic sensor of the present embodiment is substantially the same as that of the fourth embodiment, and the ventilation pipe 9 is positioned on the rear surface of the front wall 5a of the shield case 5 as shown in FIGS. 6 (a) and 6 (b). The only difference is that the positioning groove 56 is formed. Since other configurations are the same as those of the fourth embodiment, illustration and description thereof are omitted.

  Therefore, in the acoustic sensor of the present embodiment, it is possible to prevent the position of the ventilation pipe 9 from being shifted during assembly, and the assemblability is improved.

Embodiment 1 is shown, (a) is a schematic cross-sectional view, (b) is a main part explanatory view of (a). It is a general | schematic disassembled perspective view which shows the same as the above. The state which apply | coated the resin for sealing to the shield case in Embodiment 2 is shown, (a) is a bottom view, (b) is A-A 'sectional drawing of (a). The shield case in Embodiment 3 is shown, (a) is a bottom view, (b) is a BB 'sectional view of (a), (c), (d) is an explanatory view of a filling example of resin for sealing. is there. The state which apply | coated the resin for sealing to the shield case in Embodiment 4 is shown, (a) is a bottom view, (b) is B-B 'sectional drawing of (a). The state which apply | coated the resin for sealing to the shield case in Embodiment 4 is shown, (a) is a bottom view, (b) is B-B 'sectional drawing of (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reception element 2 Printed circuit board 3 Electronic component 4 Three-dimensional circuit board 5 Shield case 5a Front wall 5b Perimeter wall 8 Sealing resin part 11 Support part 12 Vibration board part 13 Spacer part 14 Back board part 14a Exhaust hole 51 Sound hole 52 For ventilation groove

Claims (5)

  A receiving element that receives a sound wave and converts the received sound wave into a received signal that is an electrical signal, and a signal that performs signal processing on the received signal that is disposed on the rear surface side of the receiving element and that is output from the receiving element A circuit board on which an electronic component constituting the processing circuit is mounted on the side facing the wave receiving element, and a shield case sealed on the circuit board so as to surround the wave receiving element and the electronic component between the circuit board and the circuit board The wave receiving element is a capacitance type receiving device in which a back plate portion is provided via a spacer portion on the rear surface side of a diaphragm-like diaphragm portion formed continuously and integrally inside a frame-like support portion. The shield case has a sound hole formed in the front wall facing the diaphragm portion of the wave receiving element, and intersects a region overlapping the support portion of the wave receiving element on the rear surface of the front wall. A ventilation groove is formed to connect the sound hole with the space between the circuit board and the circuit board. And, acoustic sensor support portion of the wave receiving element on the rear surface of the front wall, characterized in that formed by bonding a resin for sealing except for the portion overlapping with the ventilation groove.   The inflow prevention convex part which blocks | prevents the inflow of the resin to a ventilation groove on both sides of the width direction of the ventilation groove in the rear surface of a front wall is protrudingly provided in the shield case. Acoustic sensor.   The shield case has a resin filling recess for filling the sealing resin on the rear surface of the front wall continuously with the ventilation groove, and the resin in the longitudinal direction of the ventilation groove on both sides in the width direction of the ventilation groove. The acoustic sensor according to claim 1, wherein a partition wall that divides the internal space of the filling recess into two resin filling chambers protrudes from the inner bottom surface of the resin filling recess.   A receiving element that receives a sound wave and converts the received sound wave into a received signal that is an electrical signal, and a signal that performs signal processing on the received signal that is disposed on the rear surface side of the receiving element and that is output from the receiving element A circuit board on which an electronic component constituting the processing circuit is mounted on the side facing the wave receiving element, and a shield case sealed on the circuit board so as to surround the wave receiving element and the electronic component between the circuit board and the circuit board The wave receiving element includes an electrostatic plate having a back plate portion provided through a spacer portion made of an insulating material on the rear surface side of the diaphragm-like diaphragm portion formed continuously and integrally inside the frame-shaped support portion. This is a capacitive receiving element. The shield case has a sound hole in the front wall facing the diaphragm part of the receiving element, and intersects the area overlapping the support part of the receiving element on the rear surface of the front wall. The space between the receiving element and the circuit board is connected to the sound hole. The air pipe is disposed between the rear wall side of the front wall and the support portion, and the ventilation pipe and the support portion of the wave receiving element are bonded to the rear surface of the front wall with a sealing resin. Acoustic sensor.   5. The acoustic sensor according to claim 4, wherein the shield case is formed with a positioning groove for positioning the ventilation pipe so as to intersect a region overlapping the support portion of the wave receiving element on the rear surface of the front wall.

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