CN111031462A

CN111031462A - Preposition back sound cavity MEMS MIC

Info

Publication number: CN111031462A
Application number: CN201911100176.3A
Authority: CN
Inventors: 刘志永; 朱法超
Original assignee: Shandong Xingang Electronic Technology Co Ltd
Current assignee: Shandong Xingang Electronic Technology Co Ltd
Priority date: 2019-11-12
Filing date: 2019-11-12
Publication date: 2020-04-17

Abstract

The invention discloses a front rear sound cavity MEMS MIC, which fundamentally solves the common problem of small industry of a front-going MEMS MIC rear sound cavity by adding a cavity plate on a PCB to form an enlarged rear sound cavity communicated with the rear sound cavity under the condition of keeping the appearance structure unchanged, maximizes the utilization rate of an internal space of the MIC and the volume of the rear sound cavity, and thoroughly eliminates the problem that the volume of the rear sound cavity is completely dependent on the size of an MEMS sound pressure sensor chip in the prior art.

Description

Preposition back sound cavity MEMS MIC

Technical Field

The invention relates to the field of MEMS MIC, in particular to a front-mounted back sound cavity MEMS MIC.

Background

The MEMS MIC is a microphone manufactured based on MEMS technology and consists of an MEMS sound pressure sensor chip, an ASIC chip, a front sound cavity, a rear sound cavity and an RF suppression circuit. The MEMS sound pressure sensor is a micro capacitor formed by a silicon diaphragm and a silicon back plate, and can convert sound pressure change into capacitance change, and then an ASIC chip converts the capacitance change into an electric signal to realize sound-electricity conversion. The MEMS chip divides a cavity formed by the MEMS shell into a front sound cavity and a rear sound cavity, and the rear sound cavity of the front sound type MEMS MIC is formed by bonding the MEMS chip and the PCB together through glue. In this way, the volume of the back sound cavity depends on the volume of the back cavity of the MEMS chip, the adjustable range is limited, the MEMS chip cannot be increased infinitely, and the production cost is obviously increased by the overlarge MEMS chip, so that the size of the back sound cavity of the MEMS MIC is limited, the volume of the back sound cavity which is too small limits the performance of the pickup performance of the MEMS chip, and the MEMS MIC with the current structure is difficult to further improve the sensitivity. For the purpose of further improving sensitivity, reducing noise interference, improving sound-electricity conversion efficiency and improving radio reception effect under the condition of unchanged volume of the existing product, a novel MEMS MIC structure is needed to solve the problems.

Disclosure of Invention

The invention aims to overcome the defects of the traditional technology and provide the MEMS MIC with the front-mounted back sound cavity, which can improve the sensitivity, reduce the noise interference, improve the sound-electricity conversion efficiency and achieve the effect of improving the sound reception.

The aim of the invention is achieved by the following technical measures:

preposition back sound chamber MEMS MIC, including sound chamber casing, be equipped with into the sound hole on the sound chamber casing, sound chamber casing is connected with PCB, be equipped with MEMS acoustic pressure sensor chip and ASIC chip in the sound chamber casing, be equipped with back sound chamber, its characterized in that on the MEMS acoustic pressure sensor chip: the MEMS acoustic pressure sensor chip is installed on the cavity plate, constitute the sound transmission cavity between cavity plate and the PCB, be equipped with first sound transmission hole and the second sound transmission hole that communicate the sound transmission cavity on the cavity plate, back sound cavity is through first sound transmission hole and sound transmission cavity intercommunication, be equipped with the cavity ring that communicates sound inlet hole and second sound transmission hole between cavity plate and the sound cavity casing.

Further, the cavity ring is annular or cylindrical with a central through hole. The column shape in the invention refers to a column body with a cross section of square, triangle, other polygons or other regular or irregular shapes on edges.

Furthermore, the PCB is provided with a hollow part forming the sound transmission cavity and/or the cavity plate is provided with an inner concave cavity forming the sound transmission cavity.

Furthermore, the cavity plate is mounted on the PCB, a resonance sound cavity is formed among the sound cavity shell, the PCB and the cavity plate, and the side face, far away from the back sound cavity, of the MEMS sound pressure sensor chip is exposed in the resonance sound cavity.

The resonance sound cavity and the sound transmission cavity are arranged in an isolated mode.

Furthermore, the ASIC chip is installed on the sound cavity shell, the PCB or the cavity plate, and the MEMS sound pressure sensor chip and the ASIC chip are electrically connected with the PCB.

Furthermore, the MEMS sound pressure sensor chip and the ASIC chip are connected with the cavity plate in an adhesive manner.

Further, the cavity plate is made of a metal material or a non-metal material. The cavity plate is made of any one of SPCC, brass C2680, zinc white copper C7521, injection-molded PET, ABS and ceramic.

Due to the adoption of the technical scheme, compared with the prior art, the invention has the advantages that:

The cavity plate design adopted by the invention has simple structure and wide material selection range, different base materials are selected according to different MIC products, metal materials such as SPCC, brass C2680, zinc white copper C7521 and the like can be selected, and non-metal materials can be selected, such as: and (3) injecting non-metal materials with high hardness, such as PET, ABS, ceramics and the like. The cavity plate and the PCB can be bonded by adopting a glue mode, the process is mature, and the yield is high.

The cavity plate added in the MEMS MIC has the advantages of simple structure, easy manufacture, low cost, mature process flow and high yield, can be flexibly matched with different cavity plates aiming at different MIC products, and has wide product popularization range.

The invention is further described with reference to the following figures and detailed description.

Drawings

FIG. 1 is a schematic diagram of the external structure of a front acoustic cavity MEMS MIC of the present invention.

FIG. 2 is a schematic top view of a front-mounted back acoustic cavity MEMS MIC of the present invention.

Fig. 3 is a sectional view of the structure taken along the line a-a in fig. 2.

Fig. 4 is a schematic structural view of the present invention with the sound chamber housing removed.

Fig. 5 is a schematic top view of the present invention with the sound chamber housing removed.

FIG. 6 is an exploded view of a front acoustic cavity MEMS MIC in accordance with the present invention.

FIG. 7 is a schematic diagram of the structure of embodiment 2 of the pre-acoustic back cavity MEMS MIC of the present invention.

Detailed Description

Example 1: as shown in fig. 1 to 6, the front rear sound cavity MEMS MIC includes a sound cavity housing 1, a sound inlet hole 3 is formed in the sound cavity housing 1, the sound cavity housing 1 is connected with a PCB2, a MEMS sound pressure sensor chip 4 and an ASIC chip 5 are arranged in the sound cavity housing 1, a rear sound cavity 41 is formed in the MEMS sound pressure sensor chip 4, a cavity plate 6 is arranged in the sound cavity housing 1, the MEMS sound pressure sensor chip 4 is mounted on the cavity plate 6, a sound transmission cavity 21 is formed between the cavity plate 6 and a PCB2, a first sound transmission hole 61 and a second sound transmission hole 62 which are communicated with the sound transmission cavity 21 are formed in the cavity plate 6, the rear sound cavity 41 is communicated with the sound transmission cavity 21 through the first sound transmission hole 61, and a cavity ring 7 which is communicated with the sound transmission hole 3 and the second sound transmission hole 62 is formed between the cavity plate 6 and the sound cavity housing 1.

The cavity ring 7 is annular or cylindrical with a central through hole 71. In this embodiment, it is cylindrical. The column shape in the invention refers to a column body with a cross section of square, triangle, other polygons or other regular or irregular shapes on edges.

The PCB2 is provided with a hollow portion forming the sound transmission cavity 21.

The cavity plate 6 is mounted on the PCB2, a resonant sound cavity 10 is formed between the sound cavity housing 1 and the PCB2 and the cavity plate 6, and the side surface of the MEMS sound pressure sensor chip 4 away from the rear sound cavity 41 is exposed in the resonant sound cavity 10.

The resonant sound cavity 10 is isolated from the sound transmission cavity 21. With 4 intervals of MEMS acoustic pressure sensor chip between resonance sound chamber 10 and the biography sound chamber 21, both volumes are closer, and the pickup effect is superior to traditional structure far away, and sensitivity is higher, and the product pronunciation is clear, and is natural, easily discerns, and product tone quality promotes and is showing.

As shown in fig. 3 to 5, in the present embodiment, the MEMS acoustic pressure sensor chip 4 and the ASIC chip 5 are both mounted on the cavity plate 6, and the MEMS acoustic pressure sensor chip 4 and the ASIC chip 5 are connected to the cavity plate 6 by gluing. The ASIC chip 5 may also be mounted on the acoustic cavity housing or PCB2, and the MEMS acoustic pressure sensor chip 4 and the ASIC chip 5 are electrically connected to the PCB 2.

The cavity plate 6 is made of a metal material or a non-metal material. The cavity plate 6 is made of any one of SPCC, brass C2680, zinc cupronickel C7521, injection-molded PET, ABS and ceramic.

Example 2: as shown in fig. 7, in the embodiment, the front-end back acoustic cavity MEMS MIC, the acoustic cavity 21 is formed by a hollow portion on the PCB2 and an inner concave cavity on the cavity plate 6. This makes the sound transmission cavity 21 space bigger, and the sound transmission effect is better, and the pickup effect is more excellent, and sensitivity is higher, and the product pronunciation is clear, and is natural, easily discerns, and product tone quality promotes and is showing.

The rest of this example is the same as example 1.

Claims

1. Preposition back sound chamber MEMS MIC, including sound chamber casing, be equipped with into the sound hole on the sound chamber casing, sound chamber casing is connected with PCB, be equipped with MEMS acoustic pressure sensor chip and ASIC chip in the sound chamber casing, be equipped with back sound chamber, its characterized in that on the MEMS acoustic pressure sensor chip: the MEMS acoustic pressure sensor chip is installed on the cavity plate, constitute the sound transmission cavity between cavity plate and the PCB, be equipped with first sound transmission hole and the second sound transmission hole that communicate the sound transmission cavity on the cavity plate, back sound cavity is through first sound transmission hole and sound transmission cavity intercommunication, be equipped with the cavity ring that communicates sound inlet hole and second sound transmission hole between cavity plate and the sound cavity casing.

2. The pre-acoustic back cavity MEMS MIC as claimed in claim 1, wherein:

the cavity ring is annular or cylindrical with a central through hole.

3. The pre-acoustic back cavity MEMS MIC as claimed in claim 1, wherein:

the PCB is provided with a hollowed part forming a sound transmission cavity and/or the cavity plate is provided with an inner concave cavity forming the sound transmission cavity.

4. The pre-acoustic back cavity MEMS MIC as claimed in claim 1, wherein:

the cavity board is arranged on the PCB, a resonance sound cavity is formed among the sound cavity shell, the PCB and the cavity board, and the side face, far away from the back sound cavity, of the MEMS sound pressure sensor chip is exposed in the resonance sound cavity.

5. A front acoustic cavity MEMS MIC as claimed in claim 3, wherein:

6. The pre-acoustic back cavity MEMS MIC as claimed in claim 1, wherein:

the ASIC chip is arranged on the sound cavity shell, the PCB or the cavity plate, and the MEMS sound pressure sensor chip and the ASIC chip are electrically connected with the PCB.

7. The pre-acoustic back cavity MEMS MIC as claimed in claim 1, wherein:

the MEMS sound pressure sensor chip and the ASIC chip are connected with the cavity plate in an adhesive manner.

8. The pre-acoustic back cavity MEMS MIC as claimed in claim 1, wherein:

the cavity plate is made of metal materials or non-metal materials.