JP2007060285A - 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 including a silicon microphone chip 2, an opening 4a for cavity, and a through-hole 4b; and a casing 5 including a sound receiving opening 5a. The silicon microphone chip 2 is mounted on the cavity opening 4a of the printed circuit board 4, and the casing 5 surrounds the silicon microphone chip 2 and the through-hole 4b and placed on the printed circuit board 4. The space between the printed circuit board 4 and a package board 9 becomes the cavity 7 including the cavity opening 4a by mounting the printed circuit board 4 on a package board 9 and sealing the outer circumference of the printed circuit board 4 by a sealing resin 99 and the through-hole 4b becomes a 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, there is an electret condenser microphone package using an electret condenser microphone as a condenser microphone. This electret condenser microphone package has a large number of parts, and because of the presence of resin materials, printed boards, etc., it is difficult to make the whole small, light, and thin. 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.

  In order to achieve the above object, the invention of claim 1 is a silicon microphone chip package in which a silicon microphone chip is mounted on a circuit board. The silicon microphone chip package has a cavity opening, and the silicon microphone chip is mounted on the opening. A circuit board that is mounted on the board and has an opening to form a cavity by sealing the outer periphery, and has an opening for receiving sound, and is installed so as to surround the silicon microphone chip on the circuit board The circuit board is provided with a through hole for communicating the cavity with the external space, and the through hole and the sound receiving opening of the casing form a leak path of the cavity. is there.

  According to a second aspect of the present invention, in the silicon microphone package according to the first aspect, a conductive wiring connected to a circuit on the mounting substrate is provided on the circuit substrate.

  According to the invention of claim 1, by mounting the circuit board on the mounting board and sealing the outer periphery of the circuit board, the space between the circuit board and the mounting board includes the opening for the cavity of the circuit board. Since it becomes a cavity, a large cavity can be easily formed. Further, since the through hole of the circuit board serves as a vent hole (leak hole) for communicating the cavity and the external space, a sufficiently narrow vent 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.

  According to the invention of claim 2, electrical connection between the circuit board and the circuit on the mounting board can be easily performed.

  A silicon microphone package according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a silicon microphone package. 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, and a casing 5 for housing the silicon microphone chip 2 and the field effect transistor 3.

  The silicon microphone package 1 is used by being mounted on a mounting substrate 9, and a cavity 7 is formed between the printed circuit board 4 and the mounting substrate 9, and an external space outside the cavity 7 and the cavity 7 is a vent hole (leakage). Hole) 8 is communicated. 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 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 so as to overlap 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. The silicon microphone chip 2 detects an acoustic signal based on changes in capacitance of the vibration film 22 and the fixed film 24. The field effect transistor 3 converts the capacitance of the vibration film 22 and the fixed film 24 of the silicon microphone chip 2, that is, converts the acoustic signal detected by the silicon microphone chip 2 into an electrical signal and outputs it.

  The printed circuit board 4 is provided with a circuit (not shown) for electrically connecting the silicon microphone chip 2 and the field effect transistor 3 on the surface of an insulating board 41 having a substantially rectangular flat plate shape. On the back surface, conductive wiring 42 that is electrically connected to the circuit 91 on the mounting substrate 9 is provided. The printed circuit board 4 is provided with a cavity opening 4a for forming the cavity 7 and a through hole 4b for communicating the cavity 7 with the external space.

  The silicon microphone chip 2 has a cavity opening 4 a so that the sound receiving hole 2 a is opposite to the printed circuit board 4 and the sound receiving hole 2 a is aligned with the cavity opening 4 a of the printed circuit board 4. It is placed on top, flip-chip mounted, and electrically connected to the circuit of the printed circuit board 4. Then, the outer periphery of the silicon microphone chip 2 is sealed with a sealing resin 28. The field effect transistor 3 is joined to the printed circuit board 4 by a conductive adhesive or solder (not shown) and is electrically connected to the circuit of the printed circuit board 4.

  The casing 5 is made of a conductive material, 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. 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. The upper wall 51 (that is, the casing 5) is provided with an opening 5a for receiving sound. The casing 5 surrounds the through hole 4 b of the silicon microphone chip 2, the field effect transistor 3, and the printed circuit board 4 so that the sound receiving opening 5 a is aligned with the sound receiving hole 2 a of the silicon microphone chip 2. , Installed on the printed circuit board 4. A lower end edge of the peripheral side wall 52 of the casing 5 is electrically connected to a circuit wiring (not shown) for ground connection of the printed circuit board 4 by a conductive adhesive or solder (not shown). Plays a role in shielding electromagnetic noise. 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 a sealing resin 59.

  The silicon microphone package 1 having such a configuration is mounted on the mounting board 9 so that the conductive wiring 42 of the printed circuit board 4 is electrically connected to the circuit 91 on the mounting board 9. The mounting substrate 9 is sealed with a sealing resin 99. As a result, the printed circuit board 4, the mounting board 9, and the sealing resin 99 shield the region opposite to the sound receiving hole 2 a of the silicon microphone chip 2 from the external space. That is, the cavity 7 is formed by the printed circuit board 4, the mounting board 9, and the sealing resin 91, and the space between the printed circuit board 4 and the mounting board 9 sealed by the sealing resin 99 is the printed circuit board 4. The cavity 7 is formed including the opening 4a for the cavity. Further, a leak path (path indicated by an arrow A in FIG. 1) that connects the cavity 7 and the external space is formed by the through hole 4 b of the printed circuit board 4 and the sound receiving opening 5 a of the casing 5. That is, the through hole 4b of the printed circuit board 4 becomes a vent hole (leak hole) 8 that communicates the cavity 7 and the external space.

  The acoustic signal (sound) passes through the sound receiving opening 5a of the casing 5 and the sound receiving hole 2a of the silicon microphone chip 2 in the direction of arrow B in FIG. Given. When an acoustic signal is given to the vibrating membrane 22, the vibrating membrane 22 vibrates by the acoustic signal and the capacitances of the vibrating membrane 22 and the fixed membrane 24 change, whereby the silicon microphone package 1 detects the acoustic signal. .

  In the silicon microphone package 1 configured as described above, the printed circuit board 4 is mounted on the mounting board 9, and the outer periphery of the printed circuit board 4 is sealed with the sealing resin 99. Since the space between the substrates 9 includes the cavity opening 4a of the printed circuit board 4 and becomes the cavity 7, the large cavity 7 can be easily formed. Further, since the through hole 4b of the printed circuit board 4 becomes a vent hole (leak hole) 8 that communicates the cavity 7 and the external space, the vent hole 8 that is sufficiently narrow with respect to the size of the cavity 7 can be easily formed. be able to. 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, electrical connection between the printed circuit board 4 and the circuit 91 on the mounting board 9 can be easily performed by the conductive wiring 42 provided on the printed circuit board 4.

  FIG. 2 shows another configuration example of the silicon microphone package 1. In the silicon microphone package 1, the field effect transistor 3 is disposed outside the casing 5 and mounted on the mounting substrate 9. The casing 5 has a size smaller than the configuration of FIG. 1 by the amount not containing the field effect transistor 3, and the printed circuit board 4 has the size not mounted by the field effect transistor 3, The dimensions are smaller than the configuration of FIG. The other configuration of the silicon microphone package 1 is the same as the configuration of FIG. In the silicon microphone package 1 configured as described above, the printed circuit board 4 and the casing 5 can be reduced in size.

  In addition, this invention is not restricted to the structure of the said embodiment, A various deformation | transformation is possible. For example, the casing 5 and the printed circuit board 4 are not bonded to the sealing resin 59 in the process of connecting the casing 5 to the circuit wiring for ground connection of the printed circuit board 4 with a conductive adhesive or solder. You may seal with an agent or solder.

The side sectional view of the silicon microphone package concerning one embodiment of the present invention. The side sectional view of another composition 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 Cavity opening 4b Through hole 42 Conductive wiring 5 Casing 5a Sound receiving opening 7 Cavity 8 Vent hole 9 Mounting board 91 Circuit on mounting board 99 Sealing resin

Claims (2)

In a silicon microphone chip package in which a silicon microphone chip is mounted on a circuit board,
A circuit board having an opening for a cavity, mounting a silicon microphone chip on the opening, and mounting on the mounting substrate and sealing the outer periphery to form the cavity including the opening;
A casing that has an opening for receiving sound and is disposed on the circuit board so as to surround the silicon microphone chip;
The circuit board is provided with a through hole for communicating the cavity with an external space,
A silicon microphone package, wherein the through hole and the opening for receiving sound of the casing form a leak path of a cavity. The silicon microphone package according to claim 1, wherein a conductive wiring connected to a circuit on the mounting substrate is provided on the circuit substrate.

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