MEMS microphone

Abstract

A MEMS microphone (100), comprising a housing (10), a substrate (20) covering the housing (10) to form an accommodating space (101), and an ASIC chip (40) and a MEMS chip (30) disposed in the accommodating space (101); the substrate (20) is also provided with a first sound hole (21) extending from an upper surface (201) to a lower surface (202) and not passing through the lower surface, a second sound hole (22) extending from the lower surface (202) to the upper surface (201) and not passing through the upper surface (201), a connecting channel (23) provided between the upper surface (201) and the lower surface (202) of the substrate (20) and placing the first sound hole (21) and the second sound hole (22) in communication, and an air hole (24) extending from the upper surface (201) to the lower surface (202) and not passing through the lower surface (202), the air hole (24) and the second sound hole (22) being disposed to be transversely spaced apart from one another. The MEMS microphone (100) is also provided with an elastic member (50) covering the air hole (24), the elastic member (50) being able to open or close the air hole (24). The MEMS microphone (100) has strong anti-wind capability.

Description

MEMS microphones

[0001]

Technical field

[0002] The present invention relates to the field of electroacoustic conversion, and in particular to a MEMS microphone.

[0003] [Background Technology]

[0004] MEMS (Microelectro Mechanical Systems) MEMS microphones are MEMS microphones manufactured based on MEMS sensor technology. They have improved noise cancellation performance, good RF performance and electromagnetic interference suppression capabilities, and are widely used in various electronic products such as smartphones, wired headphones, tablets and notebooks.

[0005] The MEMS microphone of the related technology includes a shell, a substrate connected to the shell cover to form a receiving space, and an ASIC chip and a MEMS chip placed in the receiving space. The MEMS chip is placed on the substrate, and the diaphragm of the MEMS chip divides the receiving space into a front cavity and a rear cavity. A through hole connected to the front cavity is provided on the substrate. After the atmospheric pressure enters from the through hole, it takes some time for the air pressure in the front cavity and the rear cavity to balance, so it is easy to damage the diaphragm of the MEMS chip. The MEMS microphone has weak anti-blowing ability.

[0006] Therefore, it is necessary to provide a new MEMS microphone to solve the above technical problems.

[0007] [Summary of the invention]

[0008] The object of the present invention is to provide a MEMS microphone with strong anti-blowing capability.

[0009] To achieve the above objectives, the present invention provides a MEMS microphone, comprising a housing, a substrate connected to the housing to form a receiving space, and an ASIC chip and a MEMS chip placed in the receiving space. The MEMS chip is provided with a diaphragm and a backplate spaced apart from the diaphragm. The MEMS chip is placed on the substrate, and the diaphragm divides the receiving space into a front cavity and a rear cavity. The substrate includes an upper surface connected to the MEMS chip and a lower surface opposite the upper surface. The substrate is further provided with a first sound hole extending from the upper surface to the lower surface and not passing through the lower surface, a second sound hole extending from the lower surface to the upper surface and not passing through the upper surface, a connecting channel provided between the upper and lower surfaces of the substrate and connecting the first and second sound holes, and an air vent extending from the upper surface to the lower surface and not passing through the lower surface. The MEMS chip covers the first sound hole, which is connected to the front cavity. The air vent connects the connecting channel and the rear cavity. The air vent is laterally spaced apart from the second sound hole. The MEMS microphone is further provided with an elastic member covering the air vent, and the elastic member can open or close the air vent.

[0010] Preferably, the elastic member is connected to the upper surface of the substrate.

[0011] Preferably, the elastic member includes a fixing portion connected to the upper surface of the substrate and an elastic portion covering the vent hole.

[0012] Preferably, the first sound hole and the second sound hole are arranged laterally spaced apart.

[0013] Preferably, the projection of the second acoustic hole on the upper surface and the air vent are respectively located on two sides of the MEMS chip.

[0014] Preferably, the substrate is a stacked circuit board, which includes a first circuit board connected to the MEMS chip, a second circuit board spaced apart from the first circuit board, and a third circuit board located between the first circuit board and the second circuit board. The third circuit board is a hollow annular structure, the first sound hole and the air hole pass through the first circuit board, and the second sound hole passes through the second circuit board.

[0015] Preferably, the diaphragm is closer to the substrate than the back plate.

[0016] Compared with related technologies, the MEMS microphone of the present invention, by providing air holes and elastic members on the substrate, can open the air holes when needed to balance the air pressure in the front and rear cavities in time, thereby buffering the impact of the air pressure on the MEMS chip diaphragm.

[0017]

Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0019] FIG1 is a cross-sectional view of a MEMS microphone provided by an embodiment of the present invention.

[0020] [Specific implementation method]

[0021] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Referring to Figure 1 , a MEMS microphone 100 includes a housing 10, a substrate 20 that covers the housing 10 to form a receiving space 101, and an ASIC chip 40 and a MEMS chip 30 disposed within the receiving space 101. The MEMS chip 30 is connected to the substrate 20. The MEMS chip 30 includes a diaphragm 31 and a backplate 32 spaced apart from the diaphragm 31. The diaphragm 31 and the backplate 32 form a capacitor structure, and the diaphragm 31 divides the receiving space 101 into a front cavity 11 and a rear cavity 12. In this embodiment, the diaphragm 31 is positioned closer to the substrate than the backplate 32. In other embodiments, the backplate may be positioned closer to the substrate than the diaphragm.

[0023] The substrate 20 includes an upper surface 201 connected to the MEMS chip 30 and a lower surface 202 opposite to the upper surface 201. The substrate 30 is also provided with a first sound hole 21 extending from the upper surface 201 to the lower surface 202 and not passing through the lower surface 202, a second sound hole 22 extending from the lower surface 202 to the upper surface 201 and not passing through the upper surface 201, and a connecting channel 23 provided between the upper surface 201 and the lower surface 202 of the substrate 20 and connecting the first sound hole 21 and the second sound hole 22. The MEMS chip 30 covers the first sound hole 21 and the first sound hole 21 is connected to the front cavity 11. The first sound hole 21 and the second sound hole 22 are laterally spaced apart, that is, the first sound hole 21 and the second sound hole 22 are staggered, which can prevent external dust from falling onto the MEMS chip 30 and can also buffer the impact of external airflow, thereby improving the reliability of the product.

[0024] In this embodiment, the substrate 20 further includes an air vent 24 extending from the upper surface 201 to the lower surface 202 but not passing through the lower surface 202. The air vent 24 connects the connecting channel 23 and the rear cavity 12. The MEMS microphone 100 also includes an elastic member 50 covering the air vent 24. The elastic member 50 can open or close the air vent 24. When external air flows through the second sound hole 22 and the connecting channel 23, the elastic member 50 opens, allowing the connecting channel 23 to connect with the rear cavity 12 through the air vent 24, thereby promptly balancing the air pressure between the front and rear cavities and reducing the impact of external airflow on the MEMS chip 30. Furthermore, the air vent 24 is laterally spaced from the second sound hole 22, i.e., the second sound hole 22 and the air vent 24 are staggered, which reduces direct impact of external airflow on the elastic member 50 and increases the lifespan of the elastic member 50.

[0025] In addition, the elastic part 50 is connected to the upper surface 201 of the substrate 20, and includes a fixed part 51 connected to the upper surface 201 and an elastic part 52 covering the air vent 24, that is, the fixed part 51 is a fixed end, the elastic part 52 is a free end, the elastic part 51 is not fixed to the substrate 20, the fixed part 51 and the elastic part 50 are arranged as one body, and the elastic part 50 can be elastic silicone or metal sheet.

[0026] When external sound enters the connecting channel 23 through the second sound hole 22 and then enters the first sound hole 21, reaching the MEMS chip 30, the MEMS chip 30 converts the sound signal into an electrical signal. The ASIC chip 40 receives the electrical signal from the MEMS chip 30, processes it, and outputs it. In this embodiment, the projection of the second sound hole 22 on the top surface 201 and the air vent 24 are located on either side of the MEMS chip 30. That is, the first sound hole 21 is closer to the second sound hole 22 than the air vent 24. This allows the sound signal to be picked up by the MEMS chip 30 through the first sound hole 21 first, preventing the sound signal from entering the rear cavity 12 directly through the air vent 24, which could affect product reliability.

[0027] Furthermore, the substrate 20 is a laminated circuit board comprising a first circuit board 211 connected to the MEMS chip 30, a second circuit board 212 spaced apart from the first circuit board 211, and a third circuit board 213 located between the first and second circuit boards 211, 212. The third circuit board 213 is a hollow ring-shaped structure, with the first sound hole 22 and the air hole 24 extending through the first circuit board 211, and the second sound hole 22 extending through the second circuit board 212. In other embodiments, a cavity may be directly excavated within the substrate.

[0028] The MEMS microphone 100 of the present invention is provided with an air vent 24 and an elastic member 50 on the substrate 20. The air vent 24 can be opened when needed to balance the air pressure in the front and rear cavities, thereby buffering the impact of the air pressure on the diaphragm 31 of the MEMS chip 30.

[0029] The above description is only an embodiment of the present invention. It should be pointed out that those skilled in the art can make improvements without departing from the creative concept of the present invention, but these improvements all fall within the scope of protection of the present invention.

Claims

1. A MEMS microphone, comprising a housing, a substrate connected to the housing to form a receiving space, and an ASIC chip and a MEMS chip placed in the receiving space, the MEMS chip being provided with a diaphragm and a back plate spaced from the diaphragm, the MEMS chip being placed on the substrate, the diaphragm dividing the receiving space into a front cavity and a rear cavity, the substrate comprising an upper surface connected to the MEMS chip and a lower surface opposite to the upper surface, characterized in that: The substrate is also provided with a first sound hole extending from the upper surface to the lower surface and not passing through the lower surface, a second sound hole extending from the lower surface to the upper surface and not passing through the upper surface, a connecting channel provided between the upper surface and the lower surface of the substrate and connecting the first sound hole and the second sound hole, and an air hole extending from the upper surface to the lower surface and not passing through the lower surface, the MEMS chip covers the first sound hole and the first sound hole is connected to the front cavity, the air hole connects the connecting channel and the rear cavity, the air hole and the second sound hole are arranged laterally spaced apart, and the MEMS microphone is also provided with an elastic member covering the air hole, and the elastic member can open or close the air hole.

2. The MEMS microphone according to claim 1, characterized in that: The elastic member is connected to the upper surface of the substrate.

3. The MEMS microphone according to claim 1, characterized in that: The elastic member includes a fixing portion connected to the upper surface of the substrate and an elastic portion covering the vent hole.

4. The MEMS microphone according to claim 1, characterized in that: The first sound hole and the second sound hole are arranged with a spacing therebetween in a transverse direction.

5. The MEMS microphone according to claim 1, characterized in that: The projection of the second sound hole on the upper surface and the air hole are respectively located on two sides of the MEMS chip.

6. The MEMS microphone according to claim 1, characterized in that: The substrate is a stacked circuit board, which includes a first circuit board connected to the MEMS chip, a second circuit board spaced apart from the first circuit board, and a third circuit board located between the first circuit board and the second circuit board. The third circuit board is a hollow ring structure, the first sound hole and the air hole pass through the first circuit board, and the second sound hole passes through the second circuit board.

7. The MEMS microphone according to claim 1, characterized in that: The diaphragm is closer to the substrate than the back plate.

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