MEMS microphone

Abstract

A MEMS microphone, comprising a base (1), a housing (2) defining an accommodating space with the base (1), a MEMS chip (3) defining a back cavity with the base (1), and an ASIC chip (4) fixed to the base (1). The base (1) is provided with a sound inlet channel (10) communicating the accommodating space with the outside; the MEMS chip (3) is provided with a diaphragm (31) located on a sound inlet path of the sound inlet channel (10); the sound inlet channel (10) comprises a buffer cavity (101) located in the base (1), a first sound inlet hole (102) formed in the base (1) and communicating the buffer cavity (101) with the outside, and a second sound inlet hole (103) formed in the base (1) and communicating the buffer cavity (101) with the back cavity; the second sound inlet hole (103) faces the diaphragm (31); and the second sound inlet hole (103) comprises at least two sub-holes (1031) spaced apart from each other. When external air pressure enters the sound inlet channel (10) from the first sound inlet hole (102), the air pressure will not directly pass through the second sound inlet hole (103) to act on the diaphragm (31), and the sub-holes (1031) can further block airflow, so that the impact of the air pressure on the diaphragm (31) can be effectively buffered, thereby reducing rupture of the diaphragm, and improving the reliability and performance of the MEMS microphone.

Description

MEMS microphones Technical Field

[0001] The utility model belongs to the technical field of acoustic-electrical conversion, and in particular relates to a MEMS microphone. Background Art

[0002] MEMS sensors are the result of the development of MEMS (micro-electromechanical systems) technology. They have a wide range of applications, such as MEMS microphones. Compared with other types of sensor devices, MEMS sensors have the advantages of small size and good frequency response characteristics.

[0003] In related technologies, the MEMS chip of a MEMS microphone is directly aligned with the sound hole, and the atmospheric pressure can directly act on the diaphragm of the MEMS chip through the sound hole, which can easily cause the membrane to break. Technical issues

[0004] The purpose of the utility model is to provide a MEMS microphone that can effectively buffer the impact of air pressure on the diaphragm, reduce the membrane breakage phenomenon, and improve the reliability of the MEMS microphone. Technical Solutions

[0005] The technical solution of the present utility model is as follows: A MEMS microphone is provided, comprising a base, a shell enclosed with the base to form a receiving space, a MEMS chip enclosed with the base to form a back cavity, and an ASIC chip fixed to the base, the base being provided with a sound input channel connecting the receiving space and the outside world, the MEMS chip having a diaphragm located on the sound input path of the sound input channel, the sound input channel comprising a buffer cavity located within the base, a first sound input hole opened in the base and connecting the buffer cavity with the outside world, and a second sound input hole opened in the base and connecting the buffer cavity and the back cavity, the second sound input hole comprising at least two sub-holes spaced apart from each other.

[0006] Furthermore, in the thickness direction of the base body, the orthographic projections of the first sound inlet hole and the second sound inlet hole do not overlap.

[0007] Furthermore, in the thickness direction of the base body, the orthographic projection of the first sound inlet hole is located outside the back cavity.

[0008] Furthermore, in the thickness direction of the base body, the orthographic projection of the first sound inlet hole is located in the back cavity.

[0009] Furthermore, in an orthographic projection in the thickness direction of the substrate, each of the sub-holes surrounds the outer periphery of the first sound inlet hole.

[0010] Furthermore, the sum of the cross-sectional areas of the sub-holes is less than 30% of the cross-sectional area of ​​the first sound inlet hole.

[0011] Furthermore, the base includes a first substrate that is enclosed with the shell to form the receiving space and a second substrate fixed to the side of the first substrate facing away from the shell, the first substrate and the second substrate are spaced apart to form the buffer cavity, the first sound inlet hole is opened in the second substrate, and the second sound inlet hole is opened in the first substrate.

[0012] Furthermore, the base further includes a fixing member fixed between the first substrate and the second substrate, and the first substrate, the second substrate and the fixing member together enclose the buffer cavity.

[0013] Furthermore, the buffer cavity is opposite to the receiving space, and the junction of the shell and the first substrate is opposite to the fixing member. Beneficial effects

[0014] The beneficial effects of the present invention are:

[0015] In the present solution, since the sound inlet channel includes a buffer cavity, a first sound inlet hole and a second sound inlet hole, the second sound inlet hole includes at least two sub-holes spaced apart from each other, and the sub-holes are microholes, when the external air pressure enters the sound inlet channel, it first passes through the first sound inlet hole, then passes through the buffer cavity for buffering, and finally passes through the second sound inlet hole to act on the diaphragm of the MEMS chip. In this process, the air pressure will not directly act on the diaphragm through the second sound inlet hole after entering from the first sound inlet hole, and the second sound inlet hole is set in the form of multiple sub-holes to further buffer the air pressure, which can effectively buffer the impact of the air pressure on the diaphragm, reduce the membrane breakage phenomenon, and improve the reliability and performance of the MEMS microphone. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic cross-sectional view of a MEMS microphone according to a first embodiment of the present invention;

[0017] FIG2 is a schematic cross-sectional view of a MEMS microphone according to a second embodiment of the present invention. Modes for Carrying Out the Invention

[0018] The present invention will be further described below with reference to the accompanying drawings and implementation examples.

[0019] In conjunction with Figures 1-2, a MEMS microphone is provided, including a substrate 1, a shell 2 enclosed with the substrate 1 to form a receiving space, a MEMS chip 3 enclosed with the substrate 1 to form a back cavity, and an ASIC chip 4 fixed to the substrate 1. The substrate 1 is provided with a sound input channel 10 connecting the receiving space and the outside world. The MEMS chip 3 has a diaphragm 31 located on the sound input path of the sound input channel 10. The sound input channel 10 includes a buffer cavity 101 located in the substrate 1, a first sound input hole 102 opened in the substrate 1 and connecting the buffer cavity 101 with the outside world, and a second sound input hole 103 opened in the substrate 1 and connecting the buffer cavity 101 and the back cavity. The second sound input hole 103 faces the diaphragm 31, and the second sound input hole 103 includes at least two sub-holes 1031 spaced apart from each other.

[0020] In this solution, since the sound inlet channel 10 includes a buffer cavity 101, a first sound inlet hole 102 and a second sound inlet hole 103, the second sound inlet hole 103 includes at least two sub-holes 1031 spaced apart from each other, and the sub-holes 1031 are micropores, when the external air pressure enters the sound inlet channel 10, it first passes through the first sound inlet hole 102, then passes through the buffer cavity 101 for buffering, and finally passes through the second sound inlet hole 103 to act on the diaphragm 31 of the MEMS chip 3. In this process, the air pressure will not directly act on the diaphragm 31 through the second sound inlet hole 103 after entering from the first sound inlet hole 102, and the second sound inlet hole 103 is set in the form of multiple sub-holes 1031 to further buffer the air pressure, which can effectively buffer the impact of the air pressure on the diaphragm 31, reduce the membrane rupture phenomenon, and improve the reliability and performance of the MEMS microphone.

[0021] Among them, the MEMS chip 3 also includes a back plate 32 spaced apart from the diaphragm 31. In this solution, a solution is shown in which the back plate 32 is located on the side of the diaphragm 31 away from the substrate 1. It should be understood that in some implementations, the back plate 32 can also be arranged on the side of the diaphragm 31 close to the substrate 1.

[0022] Furthermore, the sum of the cross-sectional areas of the sub-holes 1031 is less than 30% of the cross-sectional area of ​​the first sound inlet 102. In this way, the second sound inlet 103 formed by the sub-holes 1031 has a large air resistance, and the airflow impulse is not easily transmitted through the second sound inlet 103 to the back cavity and further acts on the diaphragm 31, further enhancing the protection of the diaphragm 31. Preferably, the sub-holes 1031 are equal in size and evenly arranged. By forming the second sound inlet 103 with multiple sub-holes 1031, while ensuring the recording performance of the MEMS microphone, the airflow is dispersed into multiple streams when entering the back cavity, further reducing the impact of the air pressure on the diaphragm 31.

[0023] Furthermore, the orthographic projections of the first sound inlet 102 and the second sound inlet 103 do not overlap in the thickness direction of the base 1. Because the first and second sound inlet 102, 103, are staggered, airflow entering through the first sound inlet 102 is blocked by the walls of the buffer cavity 101 before flowing laterally along the buffer cavity 101 toward the second sound inlet 103, further enhancing the buffering effect.

[0024] Furthermore, referring to Figure 1 , the orthographic projection of the first sound inlet hole 102 is located outside the back cavity along the thickness direction of the substrate 1. Thus, the sound inlet channel 10 formed by the first sound inlet hole 102, the buffer cavity 101, and the second sound inlet hole 103 resembles a "Z"-shaped pipe. When air enters, the impact force of the "Z"-shaped pipe is significantly reduced, effectively buffering the impact of air pressure on the diaphragm 31 and ensuring its operational reliability.

[0025] Further, referring to FIG2 , in the thickness direction of the base 1, the orthographic projection of the first sound inlet hole 102 is located in the back cavity. In the orthographic projection in the thickness direction of the base 1, each sub-hole 1031 surrounds the outer periphery of the first sound inlet hole 102. Preferably, each sub-hole 1031 is symmetrically arranged in pairs on both sides of the first sound inlet hole 102, that is, each sub-hole 1031 is an even number and is arranged in a circular array. In this way, the sound inlet channel 10 composed of the first sound inlet hole 102, the buffer cavity 101 and the second sound inlet hole 103 is similar to a "Y"-shaped pipe. When the airflow enters and passes through the "Y"-shaped pipe, it first hits the area enclosed by each sub-hole 1031, and then disperses to flow to each sub-hole 1031. At this time, the impact force of the airflow flowing from each sub-hole 1031 to the back cavity is greatly reduced, thereby effectively buffering the impact force of the air pressure on the diaphragm 31 and ensuring the working reliability of the diaphragm 31. In some embodiments, the sub-holes 1031 may be odd in number and arranged in a circular array.

[0026] Furthermore, the base 1 includes a first substrate 11 that forms a receiving space with the housing 2, and a second substrate 12 that is fixed to the side of the first substrate 11 facing away from the housing 2. The first substrate 11 and the second substrate 12 are separated to form a buffer cavity 101. A first sound inlet hole 102 is defined in the second substrate 12, and a second sound inlet hole 103 is defined in the first substrate 11. The MEMS chip 3 and the ASIC chip 4 are both fixed to the first substrate 11. The MEMS chip 3 and the ASIC chip 4 can be electrically connected via gold wire or via a printed circuit on the first substrate 11. The ASIC chip 4 can be electrically connected to the first substrate 11 via gold wire or directly to the printed circuit on the first substrate 11.

[0027] Furthermore, the base 1 also includes a fixing part 13 fixed between the first substrate 11 and the second substrate 12, and the first substrate 11, the second substrate 12 and the fixing part 13 together enclose a buffer cavity 101. The first substrate 11 and the fixing part 13 can be connected by bonding, and the second substrate 12 and the fixing part 13 can also be connected by bonding, wherein the shape of the buffer cavity 101 can be cubic, cylindrical, etc. The form in which the base 1 is composed of the first substrate 11, the second substrate 12 and the fixing part 13 can make the manufacturing process simpler. In some implementations, the base 1 can also be an integrated structure, and the internal buffer cavity 101 can be formed by removing the internal material of the base 1. In some implementations, in order to further enhance the buffering effect of the buffer cavity 101, the buffer cavity 101 can also be filled with a buffer material, and the buffer material is preferably a soft porous material.

[0028] Furthermore, the buffer cavity 101 is directly opposite to the receiving space, and the junction of the shell 2 and the first substrate 11 is directly opposite to the fixing member 13. In this way, the connection between the shell 2 and the base 1 can be ensured to be reliable, and the base 1 has no cavity in the peripheral area of ​​the shell 2, which increases the structural strength of the base 1 and makes it less prone to damage.

[0029] The above 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 inventive concept of the present invention, but these improvements are all within the scope of protection of the present invention.

Claims

1. A MEMS microphone, comprising a substrate, a shell enclosed with the substrate to form a receiving space, a MEMS chip enclosed with the substrate to form a back cavity, and an ASIC chip fixed to the substrate, wherein the substrate is provided with a sound inlet channel connecting the receiving space and the outside, and the MEMS chip has a diaphragm located on the sound inlet path of the sound inlet channel, characterized in that: The sound inlet channel includes a buffer cavity located in the base, a first sound inlet hole opened in the base and connecting the buffer cavity with the outside, and a second sound inlet hole opened in the base and connecting the buffer cavity and the back cavity, wherein the second sound inlet hole includes at least two sub-holes spaced apart from each other.

2. The MEMS microphone according to claim 1, characterized in that: The sum of the cross-sectional areas of the sub-holes is less than 30% of the cross-sectional area of ​​the first sound inlet hole.

3. The MEMS microphone according to claim 1, characterized in that: In the thickness direction of the substrate, the orthographic projections of the first sound inlet hole and the second sound inlet hole do not overlap.

4. The MEMS microphone according to claim 3, characterized in that: In the thickness direction of the substrate, the orthographic projection of the first sound inlet hole is located outside the back cavity.

5. The MEMS microphone according to claim 3, characterized in that: In the thickness direction of the substrate, the orthographic projection of the first sound inlet hole is located in the back cavity.

6. The MEMS microphone according to claim 5, characterized in that: In the orthographic projection in the thickness direction of the substrate, each of the sub-holes surrounds the outer periphery of the first sound inlet hole.

7. The MEMS microphone according to any one of claims 1 to 6, characterized in that: The base includes a first substrate which is enclosed with the shell to form the receiving space and a second substrate which is fixed to a side of the first substrate away from the shell, the first substrate and the second substrate are spaced apart to form the buffer cavity, the first sound inlet hole is opened in the second substrate, and the second sound inlet hole is opened in the first substrate.

8. The MEMS microphone according to claim 7, characterized in that: The base also includes a fixing member fixed between the first substrate and the second substrate, and the first substrate, the second substrate and the fixing member are jointly enclosed to form the buffer cavity.

9. The MEMS microphone according to claim 8, characterized in that: The buffer cavity is directly opposite to the receiving space, and the connection between the shell and the first substrate is directly opposite to the fixing member.

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