CN110856090A

CN110856090A - Novel anti-radio frequency interference micro-electro-mechanical system microphone structure

Info

Publication number: CN110856090A
Application number: CN201911019733.9A
Authority: CN
Inventors: 叶菁华
Original assignee: Yutaixin Microelectronics Technology Shanghai Co Ltd; Zilltek Technology Corp
Current assignee: Yutaixin Microelectronics Technology Shanghai Co Ltd; Zilltek Technology Corp
Priority date: 2019-10-24
Filing date: 2019-10-24
Publication date: 2020-02-28

Abstract

The embodiment of the invention discloses a novel anti-radio frequency interference micro-electro-mechanical system microphone structure, which comprises a PCB substrate, an MEMS chip, a radio frequency filter, an ASIC chip, a shell, an MEMS chip and a power supply, wherein the MEMS chip is packaged on the top surface of the PCB substrate, the bottom of the radio frequency filter is arranged on the top surface of the PCB substrate through a bonding pad and is positioned at one side of the MEMS chip, the ASIC chip is arranged on the top surface of the radio frequency filter, the input end of the ASIC chip is connected with the output end of the MEMS chip, the shell covers the outer sides of the MEMS chip, the radio frequency, the radio frequency filter and the ASIC chip are reasonably distributed, the area and the space on the PCB substrate are utilized to the maximum extent, the occupied space is saved, the structure is simple, the radio frequency filter can easily achieve the filtering effect, the traditional gold wire connection is omitted, the circuit board layout is clear and concise, the manufacturing process is simplified, the subsequent overhaul and updating are convenient, and the cost is reduced.

Description

Novel anti-radio frequency interference micro-electro-mechanical system microphone structure

Technical Field

The invention relates to the field of electronic devices, in particular to a novel radio frequency interference resistant micro-electro-mechanical system microphone structure.

Background

A mems microphone translates into a sound sensor, which acts as a microphone (microphone). It is used to receive sound waves and display a vibration image of the sound, but it is not possible to measure the intensity of the noise. The sensor has a built-in electret condenser microphone that is sensitive to sound. The sound waves vibrate the electret film in the microphone, resulting in a change in capacitance, which generates a minute voltage that changes in response thereto. This voltage is then converted to a voltage of 0-5V, received by the data collector via A/D conversion, and transmitted to the computer.

One drawback of MEMS microphones is Radio Frequency (RF) interference. Sources of radio frequency interference are: cell phones, interphones, and the like; if the radio frequency interference is caused in a special place, for example, X-ray machines, gamma knives, CT machines and other equipment in hospitals can bring strong RF interference.

To prevent this proximity effect, system designers must place the microphone away from the device antenna and isolate its power supply to mitigate radio frequency interference. This often sacrifices the design aesthetics of the product.

In order to combat radio frequency interference, a traditional mems microphone generally employs a method of embedding a resistor and a capacitor on a PCB substrate to achieve radio frequency filtering, and the embedded resistor and capacitor has limited capacity, high manufacturing cost and complex manufacturing.

Disclosure of Invention

The invention aims to provide a novel micro-electromechanical system microphone structure for resisting radio frequency interference, and solves the technical problems.

The technical problem solved by the invention can be realized by adopting the following technical scheme:

a novel anti-RF interference micro-electro-mechanical system microphone structure comprises

A PCB substrate;

the MEMS chip is packaged on the top surface of the PCB substrate;

the bottom of the radio frequency filter is provided with a bonding pad, and the radio frequency filter is arranged on the top surface of the PCB substrate and positioned on one side of the MEMS chip through the bonding pad;

the ASIC chip is arranged on the top surface of the radio frequency filter, and the input end of the ASIC chip is connected with the output end of the MEMS chip;

and the shell is fixed on the top surface of the PCB substrate and covers the MEMS chip, the radio frequency filter and the ASIC chip.

Preferably, the PCB substrate is a double-layer circuit board, and a bonding pad is arranged at the bottom of the PCB substrate.

Preferably, the MEMS chip includes a silicon diaphragm and a silicon back electrode, the silicon diaphragm is parallel to the silicon back electrode, and the silicon diaphragm and the silicon back electrode form a parallel plate capacitor.

Preferably, a sound transmission cavity is arranged between the silicon diaphragm and the PCB substrate.

Preferably, the bottom end of the MEME chip is hermetically sealed and packaged on the top surface of the PCB substrate.

Preferably, the radio frequency filter is packaged on the top surface of the PCB substrate by using a CSP packaging technology, and the bottom end of the radio frequency filter is connected to the circuit on the top surface of the PCB substrate through a pad.

Preferably, the housing is made of metal.

Preferably, the PCB substrate or the housing is provided with a sound hole.

Has the advantages that: the MEMS chip, the radio frequency filter and the ASIC chip on the microphone of the micro electro mechanical system are reasonably distributed, the surface base and the space on the PCB substrate are utilized to the maximum extent, the occupied space is saved, the structure is simple, the radio frequency filter can easily achieve the filtering effect, the traditional gold wire connection is omitted, the circuit board layout is clear and concise, the manufacturing process is simplified, the follow-up overhaul and updating are convenient, and the cost is reduced.

Drawings

FIG. 1 is a schematic cross-sectional view of a MEMS microphone structure according to the present invention.

In the figure: 1-a PCB substrate; 2-a MEMS chip; 3-a radio frequency filter; 4-an ASIC chip; 5-a sound hole; 6-a pad; 7-a first signal line; 8-a second signal line;

21-a silicon diaphragm; 22-silicon back electrode; 23-sound transmission cavity.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.

As shown in FIG. 1, the present invention provides a novel anti-RF-interference MEMS microphone structure, which comprises

The PCB comprises a PCB substrate 1, wherein a sound hole 5 is formed in the PCB substrate 1, and the sound hole 5 is used for transmitting sound; a sound hole 5 may also be provided in the housing 9 to transmit sound to the outside of the headset.

The MEMS chip 2 is packaged on the top surface of the PCB substrate 1 and is positioned at the top end of the sound hole, and the MEMS chip is used for receiving sound and generating a corresponding audio signal according to sound vibration;

the radio frequency filter 3 is arranged on the bottom of the radio frequency filter 3, the radio frequency filter 3 is arranged on the top surface of the PCB substrate through a bonding pad 6, is packaged on the top surface of the PCB substrate 1 and is positioned on one side of the MEMS chip 2, and the radio frequency filter 3 is connected to the output end of an electric signal to filter the radio frequency signal, so that the output tone quality is purer;

the ASIC chip 4 is packaged on the top surface of the radio frequency filter 3, the input end of the ASIC chip 4 is connected with the output end of the MEMS chip 2, and the output end of the ASIC chip 4 is connected with a circuit of the PCB substrate 1; the ASIC chip is an Integrated Circuit (ASIC) chip technology for special applications, and functions to convert and amplify a high-resistance audio electrical signal transmitted from the MEMS chip 2 into a low-resistance electrical signal, which is then transmitted to a radio frequency filter, filtered by an RF anti-noise Circuit, and output an electrical signal matched with a front-end Circuit, thereby completing the acoustic-electrical conversion. And the electric signals are read, so that the voice is identified. The right section of the shell 9 is inverted U-shaped, and the shell 9 is provided with a U-shaped section. The MEMS microphone protection device is fixed on the top surface of the PCB substrate and covers the outer sides of the MEMS chip 2, the radio frequency filter 3 and the ASIC chip 4, and the shell 9 serves as a protection device of the MEMS microphone, so that the MEMS microphone protection device plays a certain role in sealing, moisture protection and external force prevention, and the service life of the internal structure of the MEMS microphone is prolonged.

The invention has the advantages that: the MEMS chip, the radio frequency filter and the ASIC chip on the PCB substrate are reasonably distributed, the surface base and the space on the PCB substrate are utilized to the maximum extent, the occupied space is saved, the structure is simple, the radio frequency filter can easily achieve the filtering effect, the traditional gold thread connection is omitted, the circuit board layout is clear and concise, the manufacturing process is simplified, the subsequent overhaul and the updating are convenient, and the cost is reduced.

In a preferred embodiment of the present invention, the PCB substrate 1 is a double-layer circuit board. The double-sided board is an extension of a single-sided board, and is used when a single-layer wiring cannot meet the requirements of an electronic product. Copper is coated on both sides of the circuit board, so that wires are arranged between the two layers, and the wires can be connected through the through holes to form required network connection. The design of the double-layer PCB enables the circuit arrangement to be more compact, and the space is saved. The bottom of the PCB substrate 1 is provided with a pad which is welded inside the shell.

In a preferred embodiment of the present invention, the MEMS chip 2 includes a silicon diaphragm 21 and a silicon back electrode 22, the silicon diaphragm 21 is parallel to the silicon back electrode 22, and the silicon diaphragm 21 and the silicon back electrode 22 form a parallel plate capacitor. A power line is connected to each of the silicon back electrode 22 and the silicon diaphragm 21, so that a certain voltage is generated between the silicon back electrode 22 and the silicon diaphragm 21. When the silicon diaphragm 21 moves, the distance between the silicon diaphragm 21 and the silicon back electrode 22 changes, and the capacitance changes, so that the sound pressure signal is converted into an electric signal.

As a preferred embodiment of the present invention, a sound transmission cavity 23 is disposed between the silicon diaphragm 21 and the PCB substrate 1, and the sound hole 5 is communicated with the sound transmission cavity 23. The silicon diaphragm 21 is located on the top surface of the sound-transmitting cavity 23, i.e. the sound can immediately vibrate the silicon diaphragm 21 to generate a varying electrical signal after the sound enters the sound-transmitting cavity 23 from the sound hole 5.

The microphone of the micro-electro-mechanical system comprises the following working processes:

external sound enters the sound transmission cavity 23 from the sound hole 5, the silicon diaphragm 21 vibrates under the action of sound pressure, and the distance between the silicon diaphragm 21 and the silicon back electrode 22 is changed, so that the capacitance value is changed, and a sound signal is converted into an electric signal. The electric signal is transmitted to the ASIC chip 4 to convert and amplify the transmitted audio electric signal into a low-resistance electric signal, and then transmitted to the radio frequency filter 3, filtered by the RF anti-noise circuit, and output an electric signal matched with the front-end circuit, thus completing the sound-electricity conversion.

As a preferred embodiment of the present invention, the overall front cross section of the MEME chip 2 is in an inverted "u" shape, and the bottom end of the MEME chip 2 is hermetically sealed on the top surface of the PCB substrate 1, which is advantageous in that sound leakage to other places is avoided, the sensitivity of the silicon diaphragm 21 is higher, and noise is avoided. Dust is prevented from entering the MEMS chip 2 and the radio frequency filter 3.

As a preferred embodiment of the invention, the radio frequency filter 3 is packaged on the top surface of the PCB substrate 1 by adopting CSP packaging technology, the packaging is more precise, and the space of the circuit board and the whole microphone of the micro-electro-mechanical system is saved. The bottom end of the radio frequency filter 3 is connected with a circuit on the top surface of the PCB substrate 1 through a bonding pad 6, and the bonding pad 6 ensures the electrical connection between the radio frequency filter 3 and the circuit on the PCB substrate 1, so that the electric signal is ensured to enter the radio frequency filter 3 and then output after being filtered.

In a preferred embodiment of the invention, the output of the MEMS chip 2 is connected to the input of the ASIC chip 4 via a first signal line 7. The first signal line 7 is used for transmitting the electrical signal output by the MEMS to the ASIC chip 4, so that the subsequent processing of the electrical signal by the ASIC chip 4 is facilitated.

In a preferred embodiment of the present invention, the output terminal of the ASIC chip 4 is connected to the circuit of the PCB substrate 1 through a second signal line 8. The second signal line 8 is used for transmitting the signal processed by the ASIC chip 4 to a circuit of the PCB substrate 1, and the signal of the PCB substrate 1 is converted by the radio frequency filter 3 to remove an interference signal in the signal and finally output a pure and recognizable signal.

As a preferred embodiment of the invention, the shell 9 is made of metal material, so that the protection capability is stronger and the pressure resistance is good.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. A novel anti-radio frequency interference micro-electro-mechanical system microphone structure is characterized by comprising a PCB substrate;

the MEMS chip is packaged on the top surface of the PCB substrate;

2. The novel anti-radio frequency interference micro-electromechanical system microphone structure as claimed in claim 1, wherein the PCB substrate is a double-layer circuit board PCB substrate having pads on the bottom thereof.

3. The MEMS microphone structure of claim 1, wherein the MEMS chip comprises a silicon diaphragm and a silicon back electrode, the silicon diaphragm is parallel to the silicon back electrode, and the silicon diaphragm and the silicon back electrode form a parallel-plate capacitor.

4. The novel anti-radio frequency interference MEMS microphone structure as claimed in claim 3, wherein a sound transmission cavity is formed between the silicon diaphragm and the PCB substrate.

5. The mems microphone structure of claim 1, wherein the mems chip is hermetically sealed at the bottom of the PCB substrate.

6. The novel anti-radio frequency interference micro-electromechanical system microphone structure as claimed in claim 1, wherein the radio frequency filter is packaged on the top surface of the PCB substrate by CSP, and the bottom end of the radio frequency filter is connected to the circuit on the top surface of the PCB substrate through a pad.

7. The mems microphone structure as recited in claim 1, wherein the housing is made of metal.

8. The mems microphone structure as claimed in claim 1, wherein the PCB substrate or the housing has a sound hole.