JP2007060228A - Silicon microphone package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silicon microphone package that has a cavity and a vent hole (leak hole) capable of obtaining an excellent sound receiving characteristic and can be manufactured at a low cost. <P>SOLUTION: The silicon microphone package 1 includes: a printed circuit board 4 on the opening 4a of which a silicon microphone chip is mounted; a casing 5 for surrounding the silicon microphone chip 2 and installed on the printed circuit board 4; and an insulation board 6 placed on the rear side of the casing 5. A groove 5a and an opening 5b which the groove 5a faces are provided to the rear side of the casing 5. The insulation board 6 is provided with a through-hole 6a. By installing the casing 5 onto the printed circuit board 4, a space surrounded by the casing 5 and the printed circuit board 4 becomes a cavity 7 and by installing the insulation board 6 on the rear side of the casing 5, the through-hole 6a, the groove 5a, and the opening 5b become the vent hole 8 for communicatively connecting the cavity 7 to external space. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a silicon microphone package used for, for example, a mobile phone, a hearing aid, an in-vehicle acoustic sensor, a receiving device for an ultrasonic sensor, and the like.

  Conventionally, an electret condenser microphone package using an electret condenser microphone as a condenser microphone has a large number of parts, and it is difficult to reduce the size, weight, and thickness of the whole due to the presence of resin materials, printed boards, and the like. Furthermore, since the diaphragm and diaphragm ring of the capacitor part are bonded together with an adhesive, it is not suitable for an in-vehicle acoustic sensor that requires high reliability.

Accordingly, a silicon microphone package using a silicon microphone chip having good environmental resistance as a condenser microphone has been attracting attention (see, for example, Patent Document 1). In the silicon microphone package of Patent Document 1, a hole is formed in a printed circuit board, and the hole is used as a cavity. That is, a hole is made in the printed circuit board to form a cavity in the printed circuit board itself.
JP-T-2004-537182

  However, in the silicon microphone package described in Patent Document 1 described above, it is difficult to form a hole for forming a cavity in the printed circuit board. In addition, in order to improve the sound receiving characteristics of the silicon microphone package, the cavity is enlarged and the ventilation hole that connects the cavity and the external space (leakage hole for adjusting the external pressure / internal pressure difference between the external space and the cavity) It is desirable to make the vent hole sufficiently narrow with respect to the size of the cavity.

  However, if the holes formed in the printed circuit board are used as cavities as in the silicon microphone package described in Patent Document 1 described above, it is difficult to enlarge the cavities and the size of the cavities is sufficient. Since it is difficult to form a narrow ventilation hole, excellent sound receiving characteristics cannot be obtained.

  The present invention has been made to solve the above-described problems, and provides a silicon microphone package that has a cavity and a vent hole (leak hole) capable of obtaining excellent sound receiving characteristics and can be manufactured at low cost. The purpose is to do.

  To achieve the above object, the present invention provides a printed circuit board having a sound receiving opening in a silicon microphone chip package in which a silicon microphone chip is mounted on a printed circuit board, and the silicon microphone chip is mounted on the opening. A casing installed on the printed circuit board so as to surround the silicon microphone chip so as to form a cavity, and a vent hole installed on the back surface of the casing for communicating the cavity with an external space. And an insulating plate having a through-hole for carrying out, and a groove portion for forming the vent hole and a vent opening portion that faces the groove portion and opens to the external space are provided on the back surface of the casing. The insulating plate covers the groove on the back surface of the casing and the opening for ventilation, and the through hole and the groove are aligned. It is disposed to so that.

  According to the present invention, by installing the casing on the printed circuit board, the space surrounded by the casing and the circuit board becomes a cavity, so that a large cavity can be easily formed. Further, by installing the insulating plate on the inner surface of the casing, the through hole of the insulating plate, the groove portion of the casing, and the opening for ventilation of the casing become a vent hole (leak hole) that communicates the cavity and the external space. A sufficiently narrow ventilation hole can be easily formed with respect to the size of the cavity. Therefore, a cavity and a vent hole for obtaining excellent sound receiving characteristics can be easily formed, and a silicon microphone package capable of exhibiting excellent sound receiving characteristics can be manufactured at low cost.

  A silicon microphone package according to an embodiment of the present invention will be described below with reference to the drawings. 1 shows the configuration of the silicon microphone package, FIG. 2 shows the configuration of the printed circuit board of the silicon microphone package, FIG. 3 shows the configuration of the casing of the silicon microphone package, and FIG. 4 shows the insulating plate of the silicon microphone package. Each configuration is shown. The silicon microphone package 1 is a device that is used in, for example, a mobile phone, a hearing aid, an on-vehicle acoustic sensor, an ultrasonic sensor receiver, and the like, and converts an acoustic signal (sound propagating in the air) into an electrical signal. is there.

  The silicon microphone package 1 includes a silicon microphone chip 2 that detects an acoustic signal as a change in capacitance, a field effect transistor 3 that converts the acoustic signal detected by the silicon microphone chip 2 into an electrical signal, and a silicon microphone chip 2. And a printed circuit board 4 on which the field effect transistor 3 is mounted, a casing 5 for housing the silicon microphone chip 2 and the field effect transistor 3, and an insulating plate 6 installed on the back surface of the casing 5.

  In the silicon microphone package 1, a cavity 7 is formed by a space surrounded by the printed circuit board 4 and the casing, and a vent hole (leak hole) 8 for communicating the cavity 7 with an external space is formed. Yes. These cavities 7 and vent holes 8 are for improving the sound receiving characteristics of acoustic signals. To obtain excellent sound receiving characteristics, the cavities 7 are made larger, and the vent holes 8 are made larger than the cavities 7. It is desirable to make it sufficiently thin. The silicon microphone package 1 is used by being mounted on a mounting substrate 9.

  The silicon microphone chip 2 is manufactured by processing silicon using a semiconductor manufacturing technique, and includes a base portion 21, a vibration film 22, a spacer 23, and a fixed film 24. . A sound receiving hole 2a is formed in the base portion 21, and the vibration film 22 is provided at a position facing the sound receiving hole 2a. The fixed film 24 is provided on the vibration film 22 via the spacer 23, and a gap is provided between the vibration film 22 and the fixed film 24. The base part 21 and the spacer 23 have insulating properties, and the vibration film 22 and the fixed film 24 have conductivity.

  As shown in FIG. 2, the printed circuit board 4 is provided on an insulating substrate 41 having a substantially rectangular flat plate shape, conductive wirings 42 a and 42 b provided on the surface of the substrate 41, and a back surface of the substrate 41. And conductive terminals 43a and 43b. The conductive wirings 42 a and 42 b and the conductive terminals 43 a and 43 b are electrically connected via the through hole 44. The conductive wirings 42 a and 42 b are electrically connected to the silicon microphone chip 2 and the field effect transistor 3, and the conductive terminals 43 a and 43 b are electrically connected to the circuit 91 on the mounting substrate 9. The conductive wiring 42b and the conductive terminal 43b are for ground connection. The printed circuit board 4 has an opening 4a for receiving sound.

  The silicon microphone chip 2 has the sound receiving hole 2a on the printed circuit board 4 side, and the sound receiving hole 2a is aligned with the sound receiving opening 4a of the printed circuit board 4 on the sound receiving opening 4a. And bonded to the printed circuit board 4 by the silicon-based die bonding agent 28, and mounted by wire bonding using the wires 29a and 29b.

  The acoustic signal (sound) passes through the sound receiving space 9a of the mounting board 9, the sound receiving opening 4a of the printed circuit board 4, and the sound receiving hole 2a of the silicon microphone chip 2 in the direction of arrow A in FIG. Then, it is given to the vibration film 22 of the silicon microphone chip 2. When an acoustic signal is given to the diaphragm 22 from the sound receiving hole 2a, the diaphragm 22 vibrates by the acoustic signal, and the capacitances of the diaphragm 22 and the fixed film 24 change, whereby the silicon microphone chip 2 is An acoustic signal is detected.

  The field effect transistor 3 is bonded to the printed circuit board 4 by a conductive adhesive or solder (not shown), and changes in the capacitance of the vibration film 22 and the fixed film 24 of the silicon microphone chip 2, that is, the silicon microphone chip 2. The acoustic signal detected by is converted into an electrical signal and output.

  As shown in FIG. 3, the casing 5 is made of a conductive material, and has a substantially rectangular upper wall 51 and a peripheral side wall 52 continuous from the upper wall 51, and has a substantially rectangular box shape. ing. The peripheral side wall 52 is continuous in the outer peripheral direction of the upper wall 51, and the lower end edge of the peripheral side wall 52 forms the same plane. On the back surface of the upper wall 51 (that is, the back surface of the casing 5), a ventilation groove portion 5a for forming the ventilation hole 8 and a ventilation opening portion 5b that faces the groove portion 5a and opens to the external space are provided. ing.

  The casing 5 surrounds the silicon microphone chip 2 and the field effect transistor 3 and is installed on the printed circuit board 4. By installing the casing 5 on the printed circuit board 4 in this manner, the casing 5 and the printed circuit board 4 shield the region opposite to the sound receiving hole 2a of the silicon microphone chip 2 from the external space. That is, the cavity 7 is formed by the casing 5 and the printed circuit board 4, and the space surrounded by the casing 5 and the printed circuit board 4 becomes the cavity 7.

  The lower end edge of the peripheral side wall 52 of the casing 5 is electrically connected to the conductive wiring 42b for ground connection of the printed circuit board 4 by a conductive adhesive or solder (not shown), whereby the casing 5 shields electromagnetic noise. To play a role. Further, the entire outer periphery of the lower end edge of the peripheral side wall 52 of the casing 5 and the printed circuit board 4 are sealed with the sealing resin 59, whereby the shielding performance of the cavity 7 is enhanced.

  As shown in FIG. 4, the insulating plate 6 is made of an insulating material and has a substantially rectangular flat plate shape. The insulating plate 6 has a through hole 6 a for partitioning the vent hole 8.

  The insulating plate 6 is installed on the back surface of the upper wall 51 of the casing 5 so as to cover the groove portion 5a of the casing 5 and the opening portion 5b for ventilation, and so that the through hole 6a and the groove portion 5a are combined. By installing the insulating plate 6 in the casing 5 in this manner, the cavity 7 and the external space are communicated with each other by the through hole 6a of the insulating plate 6, the groove portion 5a of the casing 5, and the ventilation opening 5b of the casing 5. A leak path (path indicated by arrow B in FIG. 1) is formed. That is, the through hole 6 a of the insulating plate 6, the groove portion 5 a of the casing 5, and the vent opening 5 b of the casing 5 form a vent hole (leak hole) 8 that communicates the cavity 7 with the external space. The insulating plate 6 is fixed to the back surface of the upper wall 51 of the casing 5 with a sealing resin 69.

  In the silicon microphone package 1 configured as described above, the space surrounded by the casing 5 and the circuit board 4 becomes the cavity 7 by installing the casing 5 on the printed circuit board 4. It can be formed easily. Further, by installing the insulating plate 6 on the inner surface of the casing 5, the through hole 6 a of the insulating plate 6, the groove portion 5 a of the casing 5, and the ventilation opening 5 b of the casing 5 communicate the cavity 7 and the external space. Since the air hole (leak hole) 8 is formed, the air hole 8 that is sufficiently thin with respect to the size of the cavity 7 can be easily formed. Accordingly, the cavity 7 and the vent hole 8 for obtaining excellent sound receiving characteristics can be easily formed, and the silicon microphone package 1 capable of exhibiting excellent sound receiving characteristics can be manufactured at low cost.

  In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible. For example, the field effect transistor 3 may be disposed outside the casing 5. In this case, the field effect transistor 3 may be mounted on the printed circuit board 4 or may be mounted on the mounting board 9. The casing 5 and the printed circuit board 4 are replaced with the sealing resin 59 in the step of connecting the casing 5 to the conductive wiring 42b for ground connection of the printed circuit board 4 with a conductive adhesive or solder. Or you may seal with solder. The silicon microphone chip 2 may be flip-chip mounted in place of bonding by the silicon die bond agent 28 and wire bonding mounting by the wires 29a and 29b. The insulating plate 6 may be fixed with an adhesive tape instead of the sealing resin 69.

The side sectional view of the silicon microphone package concerning one embodiment of the present invention. The top view of the printed circuit board of the silicon microphone package. The top view of the casing of the silicon microphone package. The top view of the insulating board of the silicon microphone package.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon microphone package 2 Silicon microphone chip 2a Sound receiving hole 3 Field effect transistor 4 Printed circuit board 4a Sound receiving opening 5 Casing 5a Ventilation groove 5b Ventilation opening 6 Insulating plate 6a Through hole 7 Cavity 8 Ventilation Hole 9 Mounting board 9a Sound receiving space

Claims (1)

In a silicon microphone chip package in which a silicon microphone chip is mounted on a printed circuit board,
A printed circuit board having an opening for receiving sound and having a silicon microphone chip mounted on the opening;
A casing installed on the printed circuit board to surround the silicon microphone chip and form a cavity;
An insulating plate installed on the back surface of the casing and having a through hole for defining a vent hole for communicating the cavity with an external space;
On the back surface of the casing, there are provided a groove portion for forming the ventilation hole, and an opening portion for ventilation that the groove portion faces and opens to the external space,
The silicon microphone package, wherein the insulating plate covers the groove on the back surface of the casing and the opening for ventilation, and is installed so that the through hole and the groove are aligned.

Images