MEMS microphone and electronic device

Abstract

The application discloses a MEMS microphone and an electronic device, wherein the MEMS microphone comprises a substrate provided with a first through hole, a first shell connected with the substrate and jointly enclosing a containing cavity, a second shell located in the containing cavity, and a MEMS microphone. The second shell comprises a top plate and a side plate, the top plate is provided with a second through hole, and a MEMS chip is located on the top plate and covers the second through hole. A waterproof film is arranged on a communication path of the first through hole and the second through hole, and in the thickness direction of the substrate, the projection of the MEMS chip is located in the projection of the waterproof film. The application can make the area of the waterproof film greater than the area of the MEMS chip on the acoustic transmission path of the MEMS microphone, increase the effective sound transmission area of the waterproof film, reduce the influence of acoustic impedance on sound wave transmission while ensuring waterproof performance, and improve the acoustic performance of the MEMS microphone.

Description

Technical Field

[0001] This application relates to the field of microphone technology, and more particularly to a MEMS microphone and electronic device. Background Technology

[0002] A microphone is a sensor that converts sound signals into electrical signals and is widely used in mobile phones, headphones, watches, laptops, and other consumer electronics. MEMS microphones typically introduce sound waves through top or bottom openings. The sound waves enter the cavity through a sound guide hole and act on the diaphragm, thereby achieving sound-to-electrical conversion.

[0003] To achieve waterproofing, existing technologies attach a waterproof membrane inside the MEMS microphone, placing it directly beneath the MEMS chip diaphragm and closer to the acoustic structure. This approach effectively reduces the acoustic cavity volume and improves product consistency. However, due to the limited back cavity size of the MEMS chip, the installation area of ​​the waterproof membrane is constrained by the chip size and packaging structure, making it impossible for the MEMS microphone to effectively balance waterproofing and acoustic performance. Utility Model Content

[0004] This application provides MEMS microphones and electronic devices to improve the acoustic performance of MEMS microphones while meeting the waterproof performance requirements.

[0005] To achieve the above objectives, according to a first aspect of this application, a MEMS microphone is provided, comprising: The substrate has a first through hole that passes through itself; The first housing is fixedly connected to the substrate and together with the substrate, forms an accommodating cavity; The second housing is located within the accommodating cavity. The second housing includes a top plate and a side plate connected to each other. A second through hole is provided on the top plate. The top plate, the side plate, and the base plate together enclose a sound inlet cavity. The first through hole communicates with the sound inlet cavity, and the second through hole communicates with the sound inlet cavity. The MEMS chip is located on the side of the top plate opposite to the substrate and covers the second through hole; A waterproof membrane is fixedly connected to the second housing, and the waterproof membrane is disposed on the communication path between the first through hole and the second through hole, and is spaced apart from the top plate. In the thickness direction of the substrate, the projection of the MEMS chip is located within the projection range of the waterproof membrane.

[0006] Optionally, in the thickness direction of the substrate, the projection of the first through hole may or may not overlap with the projection of the second through hole.

[0007] Optionally, the side plate of the second housing includes a first section and a second section connected together, the inner diameter of the first section is smaller than the inner diameter of the second section, a stepped plate is provided at the connection between the first section and the second section, the first section is farther away from the substrate than the second section, and the waterproof membrane is fixedly connected to the stepped plate.

[0008] Optionally, it also includes a support structure, which includes a first adhesive layer, a support layer and a second adhesive layer connected sequentially along the thickness direction of the substrate. The support structure has a through cavity that passes through the first adhesive layer, the support layer and the second adhesive layer. In the thickness direction of the substrate (1), the projection of the second through hole is located within the projection of the through cavity. The first adhesive layer is fixedly connected to the side of the top plate facing the substrate, and the second adhesive layer is fixedly connected to the waterproof membrane.

[0009] Optionally, it further includes: an ASIC chip, fixed to the side surface of the stepped plate opposite to the substrate, and electrically connected to the MEMS chip.

[0010] Optionally, it further includes: an ASIC chip, fixed on the substrate and electrically connected to the MEMS chip; wherein the ASIC chip is located inside the sound inlet cavity, or the ASIC chip is located outside the sound inlet cavity and inside the accommodating cavity.

[0011] Optionally, the ASIC chip is fixed on the surface of the top plate opposite to the substrate and is electrically connected to the MEMS chip via leads.

[0012] Optionally, the second housing has a plurality of second through holes, the MEMS chip covers all the second through holes, and each of the second through holes is connected to the sound inlet cavity.

[0013] Optionally, the substrate has a plurality of first through holes, each of which is connected to the sound inlet cavity.

[0014] According to a second aspect of this application, an electronic device is provided, comprising the MEMS microphone described in any one of the preceding claims.

[0015] In this application, by setting a second housing, the waterproof membrane is fixed on the communication path between the first and second through holes, and the waterproof membrane is kept spaced from the top plate to prevent it from directly adhering to the second through hole. This design allows the area of ​​the waterproof membrane to be larger than the area of ​​the MEMS chip along the acoustic transmission path, thereby increasing the effective sound transmission area of ​​the waterproof membrane. While ensuring waterproof performance, it reduces the impact of acoustic impedance on sound wave transmission, improving the sensitivity and frequency response consistency of the MEMS microphone, in other words, improving the acoustic performance of the MEMS microphone. Furthermore, by fixing the waterproof membrane to the second housing, the MEMS microphone can still be packaged simply by attaching the second housing to the substrate, simplifying the MEMS microphone packaging process and improving packaging efficiency.

[0016] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0018] Figure 1 This is a schematic diagram of the structure of a MEMS microphone disclosed in an embodiment of this application. Figure 1 ; Figure 2 This is a schematic diagram of the structure of a MEMS microphone disclosed in an embodiment of this application. Figure 2 ; Figure 3 This is a schematic diagram of the structure of a MEMS microphone disclosed in an embodiment of this application. Figure 3 ; Figure 4 This is a schematic diagram of the structure of a MEMS microphone disclosed in an embodiment of this application. Figure 4 ; Figure 5 This is a schematic diagram of the structure of a MEMS microphone disclosed in an embodiment of this application. Figure 5 ; Figure 6 This is a schematic diagram of the structure of a MEMS microphone disclosed in an embodiment of this application. Figure 6 .

[0019] Explanation of reference numerals in the attached figures: 1. Substrate; 11. First through-hole; 2. First housing; 21. Receiving cavity; 3. Second housing; 31. Top plate; 32. Side plate; 33. Sound inlet cavity; 34. Second through hole; 35. First section; 36. Second section; 37. Stepped plate; 4. MEMS chips; 5. Waterproof membrane; 6. Supporting structure; 61. First adhesive layer; 62. Supporting layer; 63. Second adhesive layer; 7. ASIC chip. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0021] As described in the background section, with the diversification of electronic products and the increasing complexity of usage environments, users are constantly raising their requirements for sound pickup quality, signal-to-noise ratio, and dust and water resistance. Especially in mobile terminals, products need to operate stably in humid, dusty, or even short-term water immersion environments, thus placing higher demands on the waterproof design of microphones.

[0022] To improve the waterproof performance of MEMS microphones, some embodiments incorporate a waterproof membrane structure outside the sound guide channel of the terminal product (such as a mobile phone). While this approach enhances the waterproofing of MEMS microphones, the long acoustic channel between the waterproof membrane and the microphone pickup port, coupled with a large front cavity volume and complex acoustic transmission path, leads to additional sound wave losses and phase delays during propagation. Furthermore, the waterproof membrane is prone to deformation during assembly and mounting, resulting in inconsistent frequency response curves and impacting the acoustic consistency and production yield of the product.

[0023] To address the aforementioned issues, in some embodiments, a waterproof membrane is placed at the acoustic aperture of the MEMS microphone to shorten the acoustic channel length and improve frequency response consistency. However, the size of the waterproof membrane in this approach is limited by the back cavity structure of the MEMS chip, resulting in a limited membrane area and making it difficult to use a larger size to disperse sound pressure or improve sound transmission performance. Furthermore, to ensure a high protection rating (such as IP68), the waterproof membrane typically requires a thicker or denser material structure, which leads to a larger acoustic impedance when sound waves pass through the membrane layer, resulting in significant sound energy attenuation and consequently, decreased microphone sensitivity and frequency response distortion. Conversely, reducing the thin film layer or increasing the aperture to improve sound transmission would reduce the protective capability.

[0024] Therefore, in order to improve the acoustic performance of MEMS microphones while meeting the waterproof performance requirements, Embodiment 1 of this application discloses a MEMS microphone.

[0025] Reference Figure 1 This application discloses a MEMS microphone according to Embodiment 1, comprising a substrate 1, a first housing 2, a second housing 3, a MEMS chip 4, and a waterproof membrane 5. The substrate 1 has a first through-hole 11. The first housing 2 is fixedly connected to the substrate 1 and together with the substrate 1 forms an accommodating cavity 21. The second housing 3 is located within the accommodating cavity 21. The second housing 3 includes a top plate 31 and a side plate 32 connected to each other. The top plate 31 has a second through-hole 34. The top plate 31, side plate 32, and substrate 1 together form a sound inlet cavity 33. The first through-hole 11 communicates with the sound inlet cavity 33, and the second through-hole 34 communicates with the sound inlet cavity 33. The MEMS chip 4 is located on the side of the top plate 31 facing away from the substrate 1 and covers the second through-hole 34. The waterproof membrane 5 is located within the sound inlet cavity 33 and is fixedly connected to the second housing 3. The waterproof membrane 5 is disposed on the communication path between the first through-hole 11 and the second through-hole 34, and is spaced from the top plate 31. In the thickness direction of substrate 1, the projection of MEMS chip 4 is located within the projection range of waterproof membrane 5.

[0026] In this embodiment, the first housing 2, the second housing 3, and the substrate 1 together form the rear cavity of the MEMS microphone. The first through-hole 11, the sound inlet cavity 33, the second through-hole 34, and the back cavity of the MEMS chip 4 together form the front cavity of the MEMS microphone. By setting the second housing 3, the waterproof membrane 5 is fixed on the communication path between the first through-hole 11 and the second through-hole 34, and the waterproof membrane 5 is kept at a distance from the top plate 31 to prevent the waterproof membrane 5 from directly adhering to the second through-hole 34. With this design, the area of ​​the waterproof membrane 5 is larger than the area of ​​the MEMS chip 4 in the acoustic transmission path of the MEMS microphone, increasing the effective sound transmission area of ​​the waterproof membrane 5. While ensuring waterproof performance, it reduces the influence of acoustic impedance on sound wave transmission, improves the sensitivity and frequency response consistency of the MEMS microphone, and in other words, improves the acoustic performance of the MEMS microphone.

[0027] In some other embodiments, the projection of the first through-hole 11 overlaps with the projection of the second through-hole 34 in the thickness direction of the substrate 1. In Embodiment 1 of this application, the projections of the first through-hole 11 and the second through-hole 34 do not overlap in the thickness direction of the substrate 1. When external airflow or instantaneous blows act on the waterproof membrane 5, the impact force borne by the membrane layer is transmitted along the acoustic channel. By arranging the first through-hole 11 and the second through-hole 34 without overlap, the impact force is dispersed in the area of ​​action on the membrane layer, which can effectively improve the impact resistance of the MEMS microphone.

[0028] Furthermore, in this embodiment, the side plate 32 of the second housing 3 includes a first segment 35 and a second segment 36 connected together. The inner diameter of the first segment 35 is smaller than the inner diameter of the second segment 36. The connection between the first segment 35 and the second segment 36 has a stepped plate 37. The first segment 35 is farther away from the substrate 1 than the second segment 36. The waterproof membrane 5 is fixedly connected to the stepped plate 37.

[0029] Specifically, in some embodiments, the first housing 2 and the second housing 3 are made of non-metallic materials. In Embodiment 1 of this application, both the first housing 2 and the second housing 3 are made of metallic materials and can be fixedly connected to the substrate 1 by conductive adhesive or solder paste. The fact that both the first housing 2 and the second housing 3 are made of metallic materials allows them to form an electromagnetic shielding cover, effectively improving the radiation resistance of the MEMS microphone.

[0030] In this embodiment, the top plate 31 and side plate 32 of the second housing 3 are integrally formed, and the first section 35, the second section 36, and the stepped plate 37 of the side plate 32 are also integral structures. Specifically, in this embodiment, the top plate 31, the first section 35, and the stepped plate 37 can be formed first by a stamping process. After applying thermosetting adhesive to one side surface of the stepped plate 37 located inside the sound inlet cavity 33, the waterproof membrane 5 is pressed together with the thermosetting adhesive, and finally the stepped plate 37 is stamped to form the second section 36 of the side plate 32.

[0031] Through a stamping process, multiple second housings 3 can be formed simultaneously in a single processing step. The waterproof membrane 5 can be fixed to the stepped plates 37 of the multiple second housings 3 during the formation stage, ensuring the membrane layer is stable and consistently positioned. When assembling the MEMS microphone, the entire assembly can be completed simply by attaching the second housings 3 to the substrate 1, thereby simplifying the MEMS microphone manufacturing process, improving assembly efficiency, and ensuring the reliability and consistency of the MEMS microphone.

[0032] In Embodiment 1 of this application, the MEMS microphone further includes an ASIC chip 7. The ASIC chip 7 is fixed on the substrate 1, located outside the sound inlet cavity 33 and inside the receiving cavity 21. In this embodiment, the substrate 1 is a circuit board, and the ASIC chip 7 is electrically connected to the MEMS chip 4 via leads, and also electrically connected to the substrate 1 via leads.

[0033] Reference Figure 2This application discloses a MEMS microphone in Embodiment 2. Unlike Embodiment 1, the second housing 3 has multiple second through holes 34, and the MEMS chip 4 covers all the second through holes 34. Each second through hole 34 is connected to the sound inlet cavity 33. Compared to Embodiment 1, the aperture of each second through hole 34 in Embodiment 2 is smaller than that in Embodiment 1. By providing multiple smaller aperture second through holes 34, the force of external airflow or impact on the waterproof membrane 5 can be dispersed while ensuring the acoustic channel remains open, resulting in more uniform stress on the membrane layer and thus improving the MEMS microphone's resistance to blows and overall mechanical reliability.

[0034] Similarly, in some other embodiments, a plurality of first through holes 11 may be provided on the substrate 1, each of which is connected to the sound inlet cavity 33. In this embodiment, the diameter of the first through hole 11 is also smaller than that of the first through hole 11 in Embodiment 1.

[0035] Reference Figure 3 This application discloses a MEMS microphone in Embodiment 3. Unlike Embodiment 1, the ASIC chip 7 in Embodiment 3 is packaged within the sound inlet cavity 33. In Embodiment 3, the projection of the ASIC chip 7 is within the projection of the stepped plate 37 along the thickness direction of the substrate 1. With this configuration, the effective volume of the rear cavity in Embodiment 3 is greater than the effective volume of the front cavity. The rear cavity of the MEMS microphone plays a buffering and tuning role acoustically. The larger effective volume of the rear cavity reduces the impact of reflected sound pressure waves on the MEMS chip 4, thereby improving the signal-to-noise ratio of the MEMS microphone. Simultaneously, the ASIC chip 7 is located within the second housing 3, eliminating the need for an additional light-shielding coating to prevent light interference. In Embodiment 3, the ASIC chip 7 can be electrically connected to the substrate 1 via flip-chip packaging, and the MEMS chip 4 is electrically connected to the substrate 1 via leads. The ASIC chip 7 and the MEMS chip 4 are electrically connected through the substrate 1.

[0036] Reference Figure 4 Embodiment 4 of this application discloses a MEMS microphone. Unlike Embodiment 1, the ASIC chip 7 is fixed on the surface of the top plate 31 facing away from the substrate 1. The ASIC chip 7 is electrically connected to the MEMS chip 4 via leads, and the ASIC chip 7 is electrically connected to the substrate 1. In Embodiment 4, by placing both the MEMS chip 4 and the ASIC chip 7 on the top plate 31, more surface space of the substrate 1 can be freed up, allowing the second housing 3 to occupy more surface space of the substrate 1, thereby further increasing the effective area of ​​the waterproof membrane 5.

[0037] Increasing the area of ​​the waterproof membrane 5 can reduce the sound pressure density per unit area, reduce acoustic impedance, and improve sound wave transmittance, thereby enhancing the waterproof performance of the MEMS microphone. Reference Figure 5 Embodiment 5 of this application discloses a MEMS microphone. Unlike Embodiment 4, the ASIC chip 7 is fixed to the side of the stepped plate 37 facing away from the substrate 1. In this embodiment, by arranging the ASIC chip 7 on the stepped plate 37, more surface space of the substrate 1 can be freed up, thereby increasing the projected area of ​​the second housing 3, increasing the effective area of ​​the waterproof membrane 5, and improving the waterproof performance; at the same time, the volume of the rear cavity can be released, thereby enhancing the acoustic buffering effect and improving the signal-to-noise ratio.

[0038] Reference Figure 6 Embodiment Six of this application discloses a MEMS microphone. Unlike Embodiment One, the inner diameters of the first segment 35 and the second segment 36 of the side plate 32 are equal. The MEMS microphone also includes a support structure 6, which includes a first adhesive layer 61, a support layer 62, and a second adhesive layer 63 connected sequentially along the thickness direction of the substrate 1. The support structure 6 has a through cavity that passes through the first adhesive layer 61, the support layer 62, and the second adhesive layer 63. The first adhesive layer 61 is fixedly connected to the side of the top plate 31 facing the substrate 1, and the second adhesive layer 63 is fixedly connected to the waterproof membrane 5.

[0039] Specifically, the second housing 3 can still be formed by stamping to form the top plate 31 and the side plate 32. The waterproof membrane 5 is attached to the top plate 31 of the second housing 3 during the formation process. When assembling the MEMS microphone, the second housing 3 can still be attached to the substrate 1 to complete the overall installation. This simplifies the manufacturing process of the MEMS microphone, improves the packaging efficiency, and ensures the reliability and consistency of the MEMS microphone.

[0040] Embodiment 7 of this application discloses an electronic device that includes a MEMS microphone of any of the above-disclosed features.

[0041] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0042] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0043] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0044] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A MEMS microphone, characterized in that, include: The substrate (1) has a first through hole (11) that passes through itself; The first housing (2) is fixedly connected to the substrate (1) and together with the substrate (1) forms an accommodating cavity (21); The second housing (3) is located inside the accommodating cavity (21). The second housing (3) includes a top plate (31) and a side plate (32) connected to each other. The top plate (31) has a second through hole (34) that passes through it. The top plate (31), the side plate (32) and the base plate (1) together form a sound inlet cavity (33). The first through hole (11) communicates with the sound inlet cavity (33), and the second through hole (34) communicates with the sound inlet cavity (33). The MEMS chip (4) is located on the side of the top plate (31) away from the substrate (1) and covers the second through hole (34); A waterproof membrane (5) is fixedly connected to the second housing (3), and the waterproof membrane (5) is disposed on the communication path of the first through hole (11) and the second through hole (34), and is spaced from the top plate (31). In the thickness direction of the substrate (1), the projection of the MEMS chip (4) is located within the projection of the waterproof membrane (5).

2. The MEMS microphone according to claim 1, characterized in that, In the thickness direction of the substrate (1), the projection of the first through hole (11) may or may not overlap with the projection of the second through hole (34).

3. The MEMS microphone according to claim 1, characterized in that, The side plate (32) of the second housing (3) includes a first section (35) and a second section (36) connected to each other. The inner diameter of the first section (35) is smaller than the inner diameter of the second section (36). The connection between the first section (35) and the second section (36) has a stepped plate (37). The first section (35) is farther away from the substrate (1) than the second section (36). The waterproof membrane (5) is fixedly connected to the stepped plate (37).

4. The MEMS microphone according to claim 1, characterized in that, It also includes a support structure (6), which includes a first adhesive layer (61), a support layer (62), and a second adhesive layer (63) connected sequentially along the thickness direction of the substrate (1). The support structure (6) has a through cavity that passes through the first adhesive layer (61), the support layer (62), and the second adhesive layer (63). In the thickness direction of the substrate (1), the projection of the second through hole (34) is located within the projection of the through cavity. The first adhesive layer (61) is fixedly connected to the top plate (31) on the side facing the substrate (1), and the second adhesive layer (63) is fixedly connected to the waterproof membrane (5).

5. The MEMS microphone according to claim 3, characterized in that, Also includes: An ASIC chip (7) is fixed to the side surface of the stepped plate (37) facing away from the substrate (1) and is electrically connected to the MEMS chip (4).

6. The MEMS microphone according to any one of claims 1 to 4, characterized in that, Also includes: An ASIC chip (7) is fixed on the substrate (1) and electrically connected to the MEMS chip (4); The ASIC chip (7) is located inside the sound inlet cavity (33), or the ASIC chip (7) is located outside the sound inlet cavity (33) and inside the accommodating cavity (21).

7. The MEMS microphone according to claim 1, characterized in that, Also includes: An ASIC chip (7) is fixed on the surface of the top plate (31) away from the substrate (1) and is electrically connected to the MEMS chip (4).

8. The MEMS microphone according to claim 1, characterized in that, The second housing (3) has a plurality of second through holes (34), and the MEMS chip (4) covers all the second through holes (34), and each second through hole (34) is connected to the sound inlet cavity (33).

9. The MEMS microphone according to claim 1, characterized in that, The substrate (1) has a plurality of first through holes (11), each of which is connected to the sound inlet cavity (33).

10. An electronic device, characterized in that, Includes the MEMS microphone as described in any one of claims 1-9.

Images