CN112492489A

CN112492489A - Waterproof MEMS microphone

Info

Publication number: CN112492489A
Application number: CN202011436432.9A
Authority: CN
Inventors: 邓卓
Original assignee: Weifang Goertek Microelectronics Co Ltd
Current assignee: Weifang Goertek Microelectronics Co Ltd
Priority date: 2020-12-07
Filing date: 2020-12-07
Publication date: 2021-03-12
Anticipated expiration: 2040-12-07
Also published as: CN112492489B

Abstract

The invention provides a waterproof MEMS microphone which comprises a packaging structure formed by a metal shell and a PCB, wherein an MEMS chip is arranged on the PCB inside the packaging structure, a sound hole corresponding to the MEMS chip is also arranged on the PCB, and a waterproof structure corresponding to the sound hole is embedded on the PCB outside the packaging structure, wherein the waterproof structure comprises two PI layers and a waterproof membrane, and the waterproof membrane is arranged between the two PI layers. The invention can solve the problem that the performance of the waterproof MEMS microphone is influenced because the waterproof membrane of the existing waterproof MEMS microphone deforms under the action of pressure.

Description

Waterproof MEMS microphone

Technical Field

The invention relates to the technical field of acoustoelectric technology, in particular to a waterproof MEMS microphone.

Background

MEMS (Micro-Electro-Mechanical System) microphones are applied to electronic products such as mobile phones and notebook computers requiring waterproof devices in batches, and in order to adapt to the waterproof devices, a waterproof membrane is disposed in the MEMS microphone structure to form a waterproof MEMS microphone.

The existing waterproof MEMS microphone comprises a packaging structure consisting of a metal shell and a PCB, an ASIC chip and an MEMS chip are arranged on the PCB inside the packaging structure, a metal net is arranged at the position where the MEMS chip is fixed with the PCB, and a waterproof membrane is arranged between the metal net and the PCB.

Although the waterproof membrane can be waterproof, when the microphone works underwater for a long time, the waterproof membrane fails due to overlarge deformation under the action of pressure, and the performance of an MEMS microphone product is further influenced.

In order to solve the above problems, a new waterproof MEMS microphone is needed, and a new waterproof MEMS microphone is needed.

Disclosure of Invention

In view of the above problems, an object of the present invention is to provide a waterproof MEMS microphone, so as to solve the problem that the performance of the waterproof MEMS microphone is affected due to the deformation of the waterproof membrane of the existing waterproof MEMS microphone under the pressure.

The waterproof MEMS microphone comprises a packaging structure formed by a metal shell and a PCB, wherein the PCB inside the packaging structure is provided with an MEMS chip, the PCB is also provided with a sound hole corresponding to the MEMS chip,

a waterproof structure corresponding to the sound hole is embedded on the PCB outside the packaging structure, wherein,

the waterproof structure comprises two PI layers and a waterproof film, wherein the waterproof film is arranged between the two PI layers.

Further, it is preferable that the waterproof structure further comprises an adhesive support layer, wherein,

and two sides of the end part of the waterproof membrane are respectively connected with the two PI layers through the bonding support layer.

Further, it is preferable that the adhesive support layer includes a thermocompression bonding layer and/or a PI support layer.

In addition, preferably, one of the two PI layers is fixedly connected with the side of the PCB where the MEMS chip is disposed through the adhesive support layer.

In addition, the preferable structure is that at least two micropores are arranged on the two PI layers, and the micropores are communicated with the sound holes and the back cavity of the MEMS chip.

Further, it is preferable that the waterproof film has an area greater than 5% of an area of the PCB board.

In addition, the preferable structure is that the vertical distance between the surface of the waterproof membrane and the surface of the PCB board provided with the MEMS chip is more than 50 um;

the vertical distance between the surface of the waterproof film and the PI layer is larger than 50 um.

In addition, it is preferable that a groove for embedding the waterproof structure is provided on the PCB, wherein,

the waterproof structure is fixed in the groove in a sealing mode through a sealant.

In addition, the preferred structure is that an ASIC chip is further disposed inside the package structure, and the ASIC chip and the MEMS chip are both fixedly disposed on the PCB through a hot melt adhesive or an epoxy resin.

In addition, the preferred structure is that the MEMS chip and the ASIC chip, and the ASIC chip and the PCB board are electrically connected by gold wires.

According to the technical scheme, the waterproof MEMS microphone provided by the invention has the advantages that the waterproof structure is embedded on the PCB outside the packaging structure, the waterproof structure comprises the waterproof membrane and two PI layers, and the waterproof membrane is arranged between the two PI layers; simultaneously, the microporous structures are arranged on the two PI layers, so that the two PI layers protect the waterproof membrane from deforming and losing efficacy under the action of pressure, and the acoustic performance of the waterproof MEMS microphone is improved.

Drawings

Other objects and results of the present invention will become more apparent and more readily appreciated as the same becomes better understood by reference to the following specification taken in conjunction with the accompanying drawings. In the drawings:

fig. 1 is a schematic structural diagram of a waterproof MEMS microphone according to an embodiment of the present invention;

FIG. 2 is a schematic view of a waterproof structure according to an embodiment of the present invention;

FIGS. 3-1 and 3-2 are schematic diagrams of PI layer structures according to embodiments of the present invention, respectively;

fig. 4 is a schematic diagram of a PCB board structure according to an embodiment of the present invention.

Wherein the reference numerals include: 1. metal casing, 2, PCB board, 21, sound hole, 3, MEMS chip, 4, SAIC chip, 5, sealed glue, 6, gold thread, 7, gold thread, 8, waterproof construction, 80, first hot pressing bond line, 81, first PI layer, 811, micropore, 82, second hot pressing bond line, 83, first PI supporting layer, 84, third hot pressing bond line, 85, water proof membrane, 86, fourth hot pressing bond line, 87, second PI supporting layer, 88, fifth hot pressing bond line, 89, second PI layer.

The same reference numbers in all figures indicate similar or corresponding features or functions.

Detailed Description

Aiming at solving the problem that the performance of the waterproof MEMS microphone is affected due to the fact that a waterproof membrane of the existing waterproof MEMS microphone deforms under the action of pressure, the invention provides a waterproof MEMS microphone which solves the problem by changing a waterproof structure.

Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In order to illustrate the structure of the waterproof MEMS microphone provided by the present invention, fig. 1 to 4 exemplarily indicate the structure of the waterproof MEMS microphone from different angles. In particular, fig. 1 shows a waterproof MEMS microphone structure according to an embodiment of the invention; FIG. 2 illustrates a waterproof structure according to an embodiment of the present invention; FIGS. 3-1 and 3-2 respectively illustrate PI layer structures in accordance with embodiments of the present invention; fig. 4 shows a PCB board structure according to an embodiment of the invention.

As shown in fig. 1 to 4, the waterproof MEMS microphone provided by the present invention includes a package structure formed by a metal housing 1 and a PCB 2, wherein a MEMS chip 3 is disposed on the PCB 2 inside the package structure, a sound hole 21 corresponding to the MEMS chip 3 is further disposed on the PCB 3, a waterproof structure 8 corresponding to the sound hole 21 is embedded on the PCB 2 outside the package structure, the waterproof structure 8 includes two PI layers and a waterproof film 85, and the waterproof film 85 is disposed between the two PI layers.

The waterproof structure 8 further includes a bonding support layer, and both sides of the end of the waterproof membrane 85 are connected to the two PI layers through the bonding support layer. And one PI layer of the two PI layers is fixedly connected with one surface of the PCB provided with the MEMS chip through an adhesive support layer. That is to say, two layers of PI layer symmetry sets up the both sides at waterproof membrane 85, and waterproof membrane 85 sets up in the middle of two layers of PI layer, is connected through the bonding supporting layer between waterproof membrane 85 and the PI layer, and the bonding supporting layer is used for supporting to connect waterproof membrane and PI layer and is used for connecting PI layer and PCB board 2.

In embodiments of the invention, the adhesive support layer comprises a thermocompression bonding layer and/or a PI support layer. In the embodiment shown in fig. 2, the waterproofing structure 8 comprises, in order from top to bottom: the MEMS chip packaging structure comprises a first hot-pressing bonding layer 80, a first PI layer 81, a second hot-pressing bonding layer 82, a first PI supporting layer 83, a third hot-pressing bonding layer 84, a waterproof film 85, a fourth hot-pressing bonding layer 86, a second PI supporting layer 87, a fifth hot-pressing bonding layer 88 and a second PI layer 89, wherein the first hot-pressing bonding layer 80 is fixedly connected with the side, provided with the MEMS chip 3, of the PCB 2.

The second thermocompression bonding layer 82, the first PI support layer 83, and the third thermocompression bonding layer 84 may be collectively referred to as an adhesive support layer for supporting and connecting the waterproof film 85 and the first PI layer 81. The fourth thermocompression bonding layer 86, the second PI support layer 87, and the fifth thermocompression bonding layer 88 may be collectively referred to as a bonding support layer for supporting and connecting the waterproof film 85 and the second PI layer 89.

In the embodiment shown in fig. 2, the adhesive support layer includes a thermocompression bonding layer and a PI support layer, and in a specific application, the thermocompression bonding layer and the PI support layer in the adhesive support layer may be appropriately reduced or eliminated according to the actual situation, as long as the connection support function for supporting the PI layer and the waterproof membrane is satisfied.

In the embodiment of the invention, the hot-press bonding layer is a HAF layer, and HAF is made of high-performance heat-sensitive phenolic resin or polyurethane.

Wherein, PI is the abbreviation of polyimide, PI material is engineering plastics with excellent mechanical property, has the characteristics of light weight, thin thickness and good bending property, at least more than two micropores are arranged on the PI layer, in the embodiment shown in figure 3-1 and figure 3-2, a plurality of micropores are arranged in the PI layer, the distribution shape of the micropores in the PI layer is shown in figure 3-1 and figure 3-2, in the specific application, the proper micropore distribution can be selected according to the actual situation.

The aperture of each micropore can be set according to actual requirements, generally speaking, the aperture of each micropore is 5-10 micrometers, and the interval between every two adjacent micropores is 1-3 micrometers, so that the supporting strength of the PI layer is guaranteed, the acoustic resistance of the PI layer is extremely low, and the using requirements of the MEMS microphone are met.

In the embodiment shown in fig. 4, a circular sound hole 21 is formed in the PCB, where it should be noted that, an effective sound inlet area of one sound hole is larger than sound inlet areas of a plurality of sound holes with micro-porous structures, and the sound holes with such structures can enhance the acoustic performance of the MEMS microphone and reduce the manufacturing difficulty of the PCB; in the embodiment of the invention, the micro-holes of the PI layer, the sound holes 21 of the PCB and the back cavity of the MEMS chip 3 are communicated.

In the embodiment of the invention, the two PI layers of the waterproof structure 8 are arranged between the waterproof membranes, and the PI layers are provided with the microporous structures, so that the two PI layers protect the waterproof membranes from being deformed and losing effectiveness under the action of pressure, and the acoustic performance of the waterproof MEMS microphone is improved.

In the embodiment of the present invention, in order to achieve good acoustic performance, the area of the waterproof film 85 is greater than 5% of the total area of the PCB, and the vertical distance between the surface of the waterproof film 85 and the side of the PCB 2 on which the MEMS chip 3 is disposed is greater than 50 um; the vertical distance between the surface of the waterproof film 85 and the PI layer 84 is greater than 50u, and the waterproof structure design does not need an additional protection net or protection sheet, so that the height of the whole waterproof structure can be effectively reduced, the size of the MEMS microphone is correspondingly reduced, and the adaptability is developed towards miniaturization.

In the embodiment of the invention, the PCB 2 is provided with a groove, the waterproof structure 8 is embedded on the PCB 2 through the groove, the gap of the groove provided with the waterproof structure 8 is filled with the sealant 5, and the sealing performance and the waterproof performance of the MEM microphone are improved through the sealant 5. By adopting the waterproof structure design of the embodiment of the invention, the size of the product can be reduced, the waterproof membrane 85 can be better protected, and the product performance of the MEMS microphone can be ensured.

In addition, in the embodiment of the present invention, an ASIC chip 4 is further disposed inside the package structure, the MEMS chip 3 and the ASIC chip 4 are both fixed on the PCB 2 by a hot melt adhesive or an epoxy resin, the MEMS chip 3 and the ASIC chip 4 are electrically connected by a gold wire 6, the ASIC chip 4 and the PCB 2 are electrically connected by a gold wire 7, and the metal housing 1 is fixed to the PCB 2 by a solder paste or a glue.

In the embodiment of the present invention, sound acts on the MEMS chip 3 through the micropores of the first PI layer, the micropores of the second PI layer, and the sound hole 21; the MEMS chip 3 converts the received sound signals into analog signals and transmits the analog signals to the ASIC chip 4 through a gold wire 6; the ASIC chip 4 converts the received analog signal into a digital signal, performs signal amplification, calibration and other processing, transmits the processed digital signal to the PCB 2 through the gold wire 7, and simultaneously transmits the digital signal in the PCB 2 to the terminal equipment directly, thereby realizing the transmission of the signal from the waterproof MEMS microphone to the terminal equipment.

According to the waterproof MEMS microphone provided by the invention, the waterproof structure is embedded on the PCB outside the packaging structure, the waterproof structure comprises the waterproof membrane and two PI layers, and the waterproof membrane is arranged between the two PI layers; simultaneously, the microporous structures are arranged on the two PI layers, so that the two PI layers protect the waterproof membrane from deforming and losing efficacy under the action of pressure, and the acoustic performance of the waterproof MEMS microphone is improved.

The waterproof MEMS microphone proposed according to the present invention is described above by way of example with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that various modifications may be made to the waterproof MEMS microphone of the present invention without departing from the scope of the invention. Therefore, the scope of the present invention should be determined by the contents of the appended claims.

Claims

1. A waterproof MEMS microphone comprises a packaging structure formed by a metal shell and a PCB, an MEMS chip is arranged on the PCB inside the packaging structure, and a sound hole corresponding to the MEMS chip is arranged on the PCB,

2. The waterproof MEMS microphone of claim 1,

the waterproof structure further comprises an adhesive support layer, wherein,

3. The waterproof MEMS microphone of claim 2,

the adhesive support layer comprises a thermocompression bonding layer and/or a PI support layer.

4. The waterproof MEMS microphone of claim 3,

one PI layer of the two PI layers is fixedly connected with one surface, provided with the MEMS chip, of the PCB through the bonding support layer.

5. The waterproof MEMS microphone of claim 1,

and at least two micropores are arranged on the two PI layers and are communicated with the sound hole and the back cavity of the MEMS chip.

6. The waterproof MEMS microphone of claim 1,

the area of the waterproof membrane is more than 5% of the area of the PCB.

7. The waterproof MEMS microphone of claim 1,

the vertical distance between the surface of the waterproof membrane and the surface of the PCB provided with the MEMS chip is more than 50 um;

8. The waterproof MEMS microphone of claim 1,

a groove for embedding the waterproof structure is arranged on the PCB, wherein,

9. The waterproof MEMS microphone of claim 1,

an ASIC chip is further arranged inside the packaging structure, and the ASIC chip and the MEMS chip are fixedly arranged on the PCB through hot melt adhesive or epoxy resin.

10. The waterproof MEMS microphone of claim 9,

the MEMS chip and the ASIC chip and the PCB are electrically connected through gold wires.