MEMS packaging structure

Abstract

The utility model provides an MEMS packaging structure, which comprises a shell, a circuit board, an MEMS chip and an ASIC (Application Specific Integrated Circuit) chip, the circuit board is covered with the shell to form an accommodating space, the MEMS chip and the ASIC chip are arranged in the accommodating space, the MEMS chip comprises a vibrating diaphragm and a back plate which is separated from the vibrating diaphragm, the MEMS chip is arranged on the circuit board, the circuit board comprises an upper surface and a lower surface which are connected with the MEMS chip, and the upper surface and the lower surface are connected with the MEMS chip. The circuit board is further provided with a first sound hole which extends from the lower surface to the upper surface and does not penetrate through the upper surface, a second sound hole which extends from the upper surface to the lower surface and does not penetrate through the lower surface, and a communication channel which is arranged between the upper surface and the lower surface and communicates the first sound hole and the second sound hole, and the MEMS chip covers the second sound hole. Projections of the first sound hole and the second sound hole in the vibration direction of the vibrating diaphragm are not overlapped, a plurality of protrusion structures are arranged in the communication channel, and the protrusion structures enable the pressure of airflow entering from the first sound hole to be 2-3.5 times of the pressure of airflow flowing out from the second sound hole. The MEMS packaging structure provided by the utility model has a relatively strong anti-blowing capability.

Description

[Technical field]

[0001] The utility model relates to the field of electroacoustic conversion, in particular to a MEMS packaging structure. [Background technology]

[0002] MEMS (Microelectro Mechanical Systems) packaging structure is a packaging structure manufactured based on MEMS sensor technology. It has improved noise elimination performance, good RF performance and electromagnetic interference suppression capabilities. It is widely used in various electronic products such as smart phones, wired headphones, tablets and notebooks.

[0003] The MEMS packaging structure of the related technology includes a shell, a circuit board 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 circuit board, 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 circuit board. After the atmospheric pressure enters from the through hole, the airflow directly acts on the diaphragm of the MEMS chip, which can easily cause the diaphragm to rupture. The MEMS packaging structure has weak anti-blowing ability.

[0004] Therefore, it is necessary to provide a new MEMS packaging structure to solve the above technical problems. [Contents of the utility model]

[0005] The utility model aims to provide a MEMS packaging structure with strong anti-blowing capability.

[0006] In order to achieve the above-mentioned purpose, the utility model provides a MEMS packaging structure, which includes a shell, a circuit board that is covered with the shell to form a receiving space, and a MEMS chip and an ASIC chip placed in the receiving space, the MEMS chip includes a diaphragm and a back plate spaced apart from the diaphragm, the MEMS chip is fixed to the circuit board, the circuit board includes an upper surface connected to the MEMS chip and a lower surface opposite to the upper surface, the circuit board is also provided with a first sound hole extending from the lower surface to the upper surface and not passing through the upper surface, a second sound hole extending from the upper surface to the lower surface and not passing through the lower surface, and a connecting channel provided between the upper surface and the lower surface and connecting the first sound hole and the second sound hole, the MEMS chip covers the second sound hole, the projections of the first sound hole and the second sound hole along the vibration direction of the diaphragm do not overlap each other, and a plurality of convex structures are provided in the connecting channel, and the convex structures make the pressure of the airflow entering from the first sound hole 2-3.5 times the pressure of the airflow flowing out from the second sound hole.

[0007] Preferably, the protruding structure extends from the lower surface and does not contact the upper surface, or the protruding structure extends from the upper surface and does not contact the lower surface.

[0008] Preferably, the circuit board 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 second sound hole passes through the first circuit board, and the first sound hole passes through the second circuit board.

[0009] Preferably, the arrangement of the plurality of protrusion structures is a Tesla valve structure.

[0010] Preferably, the plurality of protruding structures enable the airflow entering from the first sound hole to reach the second sound hole along at least two different paths.

[0011] Preferably, after the airflow enters from the first sound hole and contacts the protruding structure, turbulence is generated to reduce the pressure of the airflow.

[0012] Preferably, the protruding structure is a flat plate structure, and the angle between adjacent protruding structures is 10-170°.

[0013] Preferably, the protruding structure is a flat plate structure, and / or an arc-shaped plate structure, and / or an arc-shaped block structure.

[0014] Preferably, the number of the protrusion structures is 1-1000.

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

[0016] Compared with the related art, the utility model provides a MEMS packaging structure, which includes a shell, a circuit board that covers the shell to form a receiving space, and a MEMS chip and an ASIC chip placed in the receiving space, the MEMS chip includes a diaphragm and a back plate spaced apart from the diaphragm, the MEMS chip is fixed to the circuit board, the circuit board includes an upper surface connected to the MEMS chip and a lower surface opposite to the upper surface, the circuit board is also provided with a first sound hole extending from the lower surface to the upper surface and not passing through the upper surface, a second sound hole extending from the upper surface to the lower surface and not passing through the lower surface, and a connecting channel provided between the upper surface and the lower surface and connecting the first sound hole and the second sound hole, the MEMS chip covers the second sound hole, the projections of the first sound hole and the second sound hole along the vibration direction of the diaphragm do not overlap each other, and a plurality of convex structures are provided in the connecting channel, and the convex structures make the pressure of the airflow entering from the first sound hole 2-3.5 times the pressure of the airflow flowing out from the second sound hole. The MEMS packaging structure of the utility model can effectively reduce the air pressure after the air flow reaches the second sound hole by arranging a plurality of protruding structures in the circuit board, so that the air pressure reaching the diaphragm is reduced by 1 / 2-2 / 3 compared with the air pressure reaching the diaphragm in the prior art, thereby buffering the impact of the air pressure on the diaphragm of the MEMS chip.

Brief Description of the Drawings

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0018] Figure 1 A cross-sectional view of a MEMS packaging structure provided by the first embodiment of the utility model;

[0019] Figure 2 A cross-sectional view of a circuit board in a MEMS packaging structure provided by the first embodiment of the utility model;

[0020] Figure 3 A cross-sectional view of a circuit board in a MEMS packaging structure provided in a second embodiment of the utility model;

[0021] Figure 4 A cross-sectional view of a circuit board in a MEMS packaging structure provided in a third embodiment of the utility model;

[0022] Figure 5 A cross-sectional view of a circuit board in a MEMS packaging structure provided in a fourth embodiment of the utility model;

[0023] Figure 6 This is a cross-sectional view of a circuit board in a MEMS packaging structure provided in the fifth embodiment of the utility model. [Specific implementation method]

[0024] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0025] See also Figure 1 and Figure 2 , Figure 1 This is a cross-sectional view of a MEMS packaging structure 100 provided in the first embodiment of the utility model. The utility model provides a MEMS packaging structure 100, including a shell 1, a circuit board 2 covering the shell 1 to form a receiving space 101, and a MEMS chip 3 and an ASIC chip 4 placed in the receiving space 101, and the MEMS chip 3 is connected to the circuit board 2. The shell 1 is made of metal. The MEMS chip 3 includes a diaphragm 31 and a back plate 32 spaced apart from the diaphragm 31, and the diaphragm 31 and the back plate 32 form a capacitor structure. In this embodiment, the diaphragm 31 is arranged closer to the circuit board 2 than the back plate 32. In other embodiments, the back plate 32 may also be arranged closer to the circuit board 2 than the diaphragm 31.

[0026] Figure 2 For along Figure 1 The cross-sectional view of the circuit board 2 in the thickness direction, please also refer to Figure 1 , Figure 2The circuit board 2 includes an upper surface 201 connected to the MEMS chip 3 and a lower surface 202 opposite to the upper surface 201. The circuit board 2 is also provided with a first sound hole 21 extending from the lower surface 202 to the upper surface 201 and not passing through the upper surface 201, a second sound hole 22 extending from the upper surface 201 to the lower surface 202 and not passing through the lower surface 202, and a connecting channel 23 provided between the upper surface 201 and the lower surface 202 and connecting the first sound hole 21 and the second sound hole 22. The MEMS chip 3 covers the second sound hole 22, and the projections of the first sound hole 21 and the second sound hole 22 along the vibration direction of the diaphragm 31 do not overlap with each other, so that external dust can be prevented from falling on the MEMS chip 3, and the impact of external airflow can be buffered, thereby improving the reliability of the product. A plurality of protrusion structures 24 are disposed in the communication channel 23 . The protrusion structures 24 make the pressure of the airflow entering from the first sound hole 21 2-3.5 times the pressure of the airflow flowing out from the second sound hole 22 .

[0027] The protruding structure 24 extends from the lower surface 202 and does not contact the upper surface 201, or the protruding structure 24 extends from the upper surface 201 and does not contact the lower surface 202. The protruding structure 24 is formed on the circuit board 2 by precision milling or deposition etching process, and the aspect ratio of the protruding structure 24 is 0.1-8.

[0028] The circuit board 2 is a stacked circuit board, which includes a first circuit board 25 connected to the MEMS chip 3, a second circuit board 26 spaced apart from the first circuit board 25, and a third circuit board 27 located between the first circuit board 25 and the second circuit board 26. The third circuit board 27 is a hollow ring structure, the second sound hole 22 passes through the first circuit board 25, and the first sound hole 21 passes through the second circuit board 26. The upper surface 201 is located on the first circuit board 25, the lower surface 202 is located on the second circuit board 26, and the first sound hole 21 and the second sound hole 22 are located at the midline position of the circuit board 2 in the long axis direction.

[0029] The plurality of raised structures 24 allow the airflow entering from the first sound hole 21 to reach the second sound hole 22 along at least two different paths. After the airflow enters from the first sound hole 21 and contacts the raised structure 24, turbulence is generated to reduce the pressure of the airflow, thereby making the pressure reaching the second sound hole 22 smaller, and finally effectively reducing the pressure reaching the diaphragm 31. Specifically, the airflow pressure reaching the diaphragm 31 is reduced by 1 / 2-2 / 3 compared with the airflow pressure reaching the diaphragm in the prior art, thereby ensuring the anti-blowing ability of the diaphragm 31.

[0030] like Figure 2As shown, it is the first embodiment of the utility model, the protrusion structure 24 is a flat plate structure, the angle between adjacent protrusion structures 24 is 10-170°, the number of the protrusion structures 24 is 1-1000. The protrusion structures 24 are symmetrically arranged with the center line of the circuit board 2 as the center.

[0031] like Figure 3 As shown, it is the second embodiment of the utility model, the protruding structure 24a is also a flat structure, the angle between adjacent protruding structures 24a is 10-170°, the protruding structure 24a is divided into two groups, and the two groups of protruding structures 24a are staggered along the length direction of the circuit board 2a.

[0032] like Figure 4 As shown, it is the third embodiment of the utility model, the protruding structure 24b is an arc-shaped plate-like structure, and the number of the protruding structures 24b is 1 to 1000. The protruding structures 24b are symmetrically arranged with the center line of the circuit board 2b as the center.

[0033] like Figure 5 As shown, it is the fourth embodiment of the utility model, the protruding structure 24c is a combination of an arc-shaped plate-like structure and an arc-shaped block-like structure, and the number of the protruding structures 24c is 1-1000. The protruding structures 24c are symmetrically arranged with the center line of the circuit board 2c as the center. In other embodiments, the protruding structure can also be a combination of a flat plate-like structure, an arc-shaped plate-like structure and an arc-shaped block-like structure.

[0034] like Figure 6 As shown, it is the fifth embodiment of the utility model, the arrangement of several protrusion structures 24d is a Tesla valve structure, the protrusion structure 24d is an arc-shaped block structure, specifically, the protrusion structure 24d includes a first protrusion 241d, a second protrusion 242d surrounding the first protrusion 241d, and a third protrusion 243d surrounding the second protrusion 242d, the first protrusion 241d is located in the middle of the circuit board 2d, the second protrusion 242d is in a water drop shape, and the third protrusion 243d extends from the third circuit board 27d to the connecting channel 23d. The protrusion structure 24d is symmetrically arranged with the center line of the circuit board 2d as the center.

[0035] Compared with the related art, the utility model provides a MEMS packaging structure, which includes a shell, a circuit board that covers the shell to form a receiving space, and a MEMS chip and an ASIC chip placed in the receiving space, the MEMS chip includes a diaphragm and a back plate spaced apart from the diaphragm, the MEMS chip is fixed to the circuit board, the circuit board includes an upper surface connected to the MEMS chip and a lower surface opposite to the upper surface, the circuit board is also provided with a first sound hole extending from the lower surface to the upper surface and not passing through the upper surface, a second sound hole extending from the upper surface to the lower surface and not passing through the lower surface, and a connecting channel provided between the upper surface and the lower surface and connecting the first sound hole and the second sound hole, the MEMS chip covers the second sound hole, the projections of the first sound hole and the second sound hole along the vibration direction of the diaphragm do not overlap each other, and a plurality of convex structures are provided in the connecting channel, and the convex structures make the pressure of the airflow entering from the first sound hole 2-3.5 times the pressure of the airflow flowing out from the second sound hole. The MEMS packaging structure of the utility model can effectively reduce the airflow after the airflow reaches the second sound hole by arranging a plurality of protruding structures in the circuit board, so that the airflow pressure reaching the diaphragm is reduced by 1 / 2-2 / 3 compared with the airflow pressure reaching the diaphragm in the prior art, thereby buffering the impact of the air pressure on the diaphragm of the MEMS chip.

[0036] The above is only an implementation method of the present invention. It should be pointed out that a person skilled in the art can make improvements without departing from the inventive concept of the present invention, but these improvements are all within the protection scope of the present invention.

Claims

1. A MEMS packaging structure, comprising a housing, a circuit board that is covered with the housing to form a receiving space, and a MEMS chip and an ASIC chip placed in the receiving space, wherein the MEMS chip comprises a diaphragm and a back plate spaced apart from the diaphragm, the MEMS chip is fixed to the circuit board, and the circuit board comprises an upper surface connected to the MEMS chip and a lower surface opposite to the upper surface, characterized in that: The circuit board is also provided with a first sound hole extending from the lower surface to the upper surface and not passing through the upper surface, a second sound hole extending from the upper surface to the lower surface and not passing through the lower surface, and a connecting channel provided between the upper surface and the lower surface and connecting the first sound hole and the second sound hole, the MEMS chip covers the second sound hole, the projections of the first sound hole and the second sound hole along the vibration direction of the diaphragm do not overlap with each other, and a plurality of protruding structures are provided in the connecting channel, and the protruding structures make the pressure of the airflow entering from the first sound hole 2-3.5 times the pressure of the airflow flowing out from the second sound hole.

2. The MEMS packaging structure according to claim 1, characterized in that: The protruding structure extends from the lower surface and does not contact the upper surface, or the protruding structure extends from the upper surface and does not contact the lower surface.

3. The MEMS packaging structure according to claim 1, characterized in that: The circuit board 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 second sound hole passes through the first circuit board, and the first sound hole passes through the second circuit board.

4. The MEMS packaging structure according to claim 1, characterized in that: The arrangement of the plurality of protruding structures forms a Tesla valve structure.

5. The MEMS packaging structure according to claim 1, characterized in that: The plurality of protruding structures enable the airflow entering from the first sound hole to reach the second sound hole along at least two different paths.

6. The MEMS packaging structure according to claim 1, characterized in that: After the airflow enters from the first sound hole and contacts the protruding structure, turbulence is generated to reduce the pressure of the airflow.

7. The MEMS packaging structure according to claim 6, characterized in that: The protruding structures are flat plate structures, and the angles between adjacent protruding structures are 10-170°.

8. The MEMS packaging structure according to claim 6, characterized in that: The protruding structure is a flat plate structure, and / or an arc-shaped plate structure, and / or an arc-shaped block structure.

9. The MEMS packaging structure according to claim 6, characterized in that: The number of the protruding structures is 1-1000.

10. The MEMS packaging structure according to claim 1, characterized in that: The diaphragm is closer to the circuit board than the back plate.

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