High signal-to-noise ratio forward sound MEMS microphone

Abstract

The utility model discloses high SNR advances the MEMS microphone of sound, relates to microphone technical field, including first circuit board, second circuit board, electric -acoustic conversion chip, electric signal processing chip and gold wire, first circuit board, first circuit board surface etching forms electrical connection PAD, and first circuit board integrally formed has intercommunication cavity, through the double board structure of first circuit board cooperation second circuit board, will by first sound hole - first cavity - second sound hole - intercommunication cavity - third sound hole sound channel completely integrated in double circuit board inside, forms built -in zigzag channel, need not rely on external additional structure auxiliary sound wave conduction, and the external adaptation difficulty is greatly simplified, simultaneously through second circuit board and first circuit board enclose and form the second cavity that is completely closed, and this second cavity directly wraps electric -acoustic conversion chip and is as the diaphragm exclusive back chamber, can both isolate impurity, and can provide stable pressure environment for diaphragm vibration, guarantee performance stability.

Description

Technical Field

[0001] This utility model relates to the field of microphone technology, and in particular to a high signal-to-noise ratio forward-sound MEMS microphone. Background Technology

[0002] With the rapid development of AI and voice interaction technologies, people have an increasingly urgent need for higher-quality voice interaction. High signal-to-noise ratio (SNR) microphones are becoming a core key to achieving high-quality human-computer voice interaction. As conversational AI continues to develop with the help of advanced algorithms and technologies, its ability to understand natural language input and respond like a human is gradually improving. However, high SNR microphones play an indispensable role in enabling voice assistants to accurately recognize user voice commands and improve overall audio quality in various complex environments.

[0003] In the existing technology, although the back-entry microphone structure has a high signal-to-noise ratio, it has the following structural defects: First, its sound inlet channel structure design is complex, which leads to the need to match a more complex external structure when assembling the whole machine; Second, the MEMS diaphragm is exposed on the back side without a protective structure, making it susceptible to the impact of solder paste and flux splashing during the SMT process.

[0004] To address these issues, the industry has proposed a three-layer stacked board structure for forward-facing microphones. However, this solution suffers from structural redundancy (three layers stacked) and unstable connection structure (interlayer connections relying on solder paste are prone to gaps), resulting in low product yield and high cost.

[0005] Therefore, this invention proposes a high signal-to-noise ratio forward-sound MEMS microphone to solve the above problems. Utility Model Content

[0006] In view of the problems existing in the prior art, this utility model is proposed.

[0007] To solve the above-mentioned technical problems, this utility model provides the following technical solution: a high signal-to-noise ratio forward-sound MEMS microphone, comprising:

[0008] The first circuit board has an electrical connection PAD etched on its surface. The first circuit board has a connecting cavity integrally formed and has a second sound inlet and a third sound inlet. The connecting cavity is connected to the second sound inlet and the third sound inlet, respectively.

[0009] The second circuit board has a first sound inlet hole extending through its top along the thickness direction, and forms an independent first cavity and a second cavity inside. The second cavity is sequentially connected to the first sound inlet hole and the second sound inlet hole. An electroacoustic conversion chip and an electrical signal processing chip are disposed inside the second cavity. The electroacoustic conversion chip and the electrical signal processing chip are arranged at intervals on the first circuit board.

[0010] Gold wires are respectively soldered between the electroacoustic conversion chip and the electrical signal processing chip, and between the electrical signal processing chip and the first circuit board;

[0011] The second circuit board is fixed on the first circuit board. The second circuit board is arranged around the outer periphery of the first cavity and the second cavity, and the second circuit board and the first circuit board form a closed structure to form the first cavity. The first sound inlet hole, the first cavity, the second sound inlet hole, the connecting cavity, and the third sound inlet hole together constitute a sound inlet channel pointing to the MEMS.

[0012] As a preferred embodiment of the high signal-to-noise ratio forward-facing MEMS microphone of this utility model, wherein: the closed structure formed by the second circuit board and the first circuit board is the second cavity, the second cavity encloses the electroacoustic conversion chip, and the second cavity is located on the side of the electroacoustic conversion chip away from the third sound inlet hole.

[0013] As a preferred embodiment of the high signal-to-noise ratio forward-facing MEMS microphone of this utility model, the electroacoustic conversion chip has a MEMS diaphragm, and the sound inlet channel formed by the first sound inlet hole, the first cavity, the second sound inlet hole, the connecting cavity, and the third sound inlet hole points towards the MEMS diaphragm.

[0014] In a preferred embodiment of the high signal-to-noise ratio forward-sound MEMS microphone of this invention, the second cavity encloses an electroacoustic conversion chip and an electrical signal processing chip.

[0015] As a preferred embodiment of the high signal-to-noise ratio forward-sound MEMS microphone of this utility model, the second circuit board is configured as an outer shell and an inner shell disposed on the upper surface of the first circuit board, the outer shell covering the outside of the inner shell, and the first sound inlet hole is opened at the top of the outer shell;

[0016] The first cavity is a closed space formed by the outer shell, the inner shell and the first circuit board. The first cavity is an independent closed space formed by splicing the outer shell and the inner shell. The second cavity is formed by the inner shell and the first circuit board. The top of the first cavity is connected to the first sound inlet hole on the outer shell, and the bottom opening of the first cavity is connected to the second sound inlet hole on the first circuit board.

[0017] In a preferred embodiment of the high signal-to-noise ratio forward-sound MEMS microphone of the present invention, the second circuit board is configured as a first housing and a second housing, the first housing and the second housing are arranged at intervals on the first circuit board, and the first sound inlet is opened at the top of the second housing.

[0018] As a preferred embodiment of the high signal-to-noise ratio forward-facing MEMS microphone of this utility model, wherein: the first housing and the second housing are both independent cover-shaped structures with open bottoms;

[0019] The first cavity is enclosed by the second shell and the first circuit board to form a closed space, and the second cavity is enclosed by the first shell and the first circuit board to form an independent closed space.

[0020] The beneficial effects of this utility model are as follows: By using a dual-board structure of the first circuit board and the second circuit board, the sound inlet channel, consisting of the first sound inlet hole, the first cavity, the second sound inlet hole, the connecting cavity, and the third sound inlet hole, is completely integrated inside the dual circuit boards, forming a built-in zigzag channel. This eliminates the need for external additional structures to assist in sound wave transmission, greatly simplifying the difficulty of external adaptation. At the same time, the second circuit board and the first circuit board enclose a completely sealed second cavity, which directly wraps the electroacoustic conversion chip and serves as a dedicated back cavity for the diaphragm. This not only isolates impurities but also provides a stable pressure environment for diaphragm vibration, ensuring stable performance. Replacing the three-layer stacked board with a dual-board structure of the first circuit board and the second circuit board eliminates redundant intermediate layers, reduces interlayer connection nodes, effectively improves the yield of finished products, and reduces manufacturing costs. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a plan view of the overall structure of the high signal-to-noise ratio forward-moving tone MEMS microphone of Embodiment 1 of this utility model;

[0023] Figure 2 This is a schematic diagram of the AA-direction cross-sectional structure of the high signal-to-noise ratio forward-moving MEMS microphone of Embodiment 1 of this utility model;

[0024] Figure 3 This is a schematic diagram of the BB-direction cross-sectional structure of the high signal-to-noise ratio forward-moving tone MEMS microphone of Embodiment 1 of this utility model;

[0025] Figure 4 This is a schematic diagram of the CC-direction cross-sectional structure of the high signal-to-noise ratio forward-moving MEMS microphone of Embodiment 1 of this utility model;

[0026] Figure 5 This is a plan view of the overall structure of the high signal-to-noise ratio forward-sound MEMS microphone of Embodiment 2 of this utility model;

[0027] Figure 6This is a schematic diagram of the AA-direction cross-sectional structure of the high signal-to-noise ratio forward-moving MEMS microphone of Embodiment 2 of this utility model;

[0028] Figure 7 This is a schematic diagram of the BB-direction cross-sectional structure of the high signal-to-noise ratio forward-moving MEMS microphone in Embodiment 2 of this utility model;

[0029] Figure 8 This is a schematic diagram of the CC-direction cross-sectional structure of the high signal-to-noise ratio forward-sound MEMS microphone of Embodiment 2 of this utility model;

[0030] Figure 9 This is a plan view of the overall structure of the high signal-to-noise ratio forward-moving MEMS microphone of Embodiment 3 of this utility model;

[0031] Figure 10 This is a schematic diagram of the AA-direction cross-sectional structure of the high signal-to-noise ratio forward-moving MEMS microphone of Embodiment 3 of this utility model;

[0032] Figure 11 This is a schematic diagram of the BB-direction cross-sectional structure of the high signal-to-noise ratio forward-sound MEMS microphone of Embodiment 3 of this utility model;

[0033] Figure 12 This is a schematic diagram of the CC-direction cross-sectional structure of the high signal-to-noise ratio forward-sound MEMS microphone of Embodiment 3 of this utility model.

[0034] Explanation of reference numerals in the attached drawings: 001, First circuit board; 002, Electrical connection PAD; 003, Communicating cavity; 004, Second sound inlet; 005, Third sound inlet; 006, Second circuit board; 007, First sound inlet; 008, First cavity; 009, Second cavity; 0010, Electroacoustic conversion chip; 0011, Electrical signal processing chip; 0012, Gold wire; 0013, Outer shell; 0014, Inner shell; 0015, First shell; 0016, Second shell. Detailed Implementation

[0035] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings.

[0036] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0037] Secondly, the term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single embodiment or an embodiment selectively excluded from other embodiments.

[0038] Example 1

[0039] Reference Figures 1-4 As shown, this is the first embodiment of the present invention, which provides a high signal-to-noise ratio forward-sound MEMS microphone, comprising:

[0040] The first circuit board 001 is a rigid circuit board made of FR-4 material. Its surface is etched to form an electrical connection PAD002. The internal cavity 003 is integrally formed by mechanical processing or etching. The first circuit board 001 also has a second sound inlet 004 and a third sound inlet 005. The connecting cavity 003 is connected to the second sound inlet 004 and the third sound inlet 005 respectively. The second sound inlet 004 and the third sound inlet 005 are both arranged through the thickness direction of the first circuit board 001, and their axes are parallel to each other.

[0041] The second circuit board 006 is an FR-4 material circuit board that matches the first circuit board 001. A first sound inlet hole 007 is provided through its top along the thickness direction. Inside, two isolated independent cavities are formed through injection molding or etching. These two isolated independent cavities are a first cavity 008 and a second cavity 009. The second cavity 009 is a closed structure formed by the second circuit board 006 and the first circuit board 001. The second cavity 009 encloses the electroacoustic conversion chip 0010 and the electrical signal processing chip 0011, and is located on the side of the electroacoustic conversion chip 0010 facing away from the third sound inlet hole 005. The first cavity 008 is an independent closed space formed inside the second circuit board 006, its top... The first cavity 008 is connected to the first sound inlet 007, and the bottom opening is connected to the second sound inlet 004; this ensures that sound waves can directly enter the second cavity 009 from the first sound inlet 007. The first cavity 008 is sequentially connected to the first sound inlet 007 and the second sound inlet 004. The second cavity 009 is provided with an electroacoustic conversion chip 0010 and an electrical signal processing chip 0011 fixed to the first circuit board 001. The electroacoustic conversion chip 0010 and the electrical signal processing chip 0011 are fixed to a preset area of ​​the first circuit board 001 by epoxy adhesive bonding process, and the electroacoustic conversion chip 0010 and the electrical signal processing chip 0011 are arranged at intervals on the first circuit board 001 to avoid signal interference during operation.

[0042] Gold wire 0012, which is configured as a gold alloy wire, is soldered to the electroacoustic conversion chip 0010 and the electrical signal processing chip 0011, and between the electrical signal processing chip 0011 and the first circuit board 001;

[0043] The second circuit board 006 is soldered and fixed to the upper surface of the first circuit board 001 using a reflow soldering process. The soldering area is set around the outer periphery of the first cavity 008 and the second cavity 009 to ensure that there is no gap after the two are connected, so that the second cavity 009 forms a completely closed space. The second circuit board 006 and the first circuit board 001 enclose the first cavity 008 to form a closed structure. The first sound inlet 007, the first cavity 008, the second sound inlet 004, the connecting cavity 003, and the third sound inlet 005 together constitute a sound inlet channel pointing to the MEMS. The overall direction of the sound inlet channel is a zigzag shape of "from top to bottom and then turning", ensuring that external sound waves are only transmitted to the MEMS diaphragm along this path and do not directly communicate with the internal space of the second cavity 009.

[0044] There is a gap between the inner wall of the second cavity 009 and the outer wall of the electroacoustic conversion chip 0010. The second cavity 009 encloses the electroacoustic conversion chip 0010 and is located on the side of the electroacoustic conversion chip 0010 away from the third sound inlet 005.

[0045] The electroacoustic conversion chip 0010 has a MEMS diaphragm, which is a circular or square thin film structure. The side of the diaphragm facing the third sound inlet 005 is the sound wave receiving surface. The outlet of the third sound inlet 005 at the end of the sound inlet channel is directly opposite the center area of ​​the MEMS diaphragm. The sound inlet channel formed by the first sound inlet 007, the first cavity 008, the second sound inlet 004, the connecting cavity 003, and the third sound inlet 005 points towards the MEMS diaphragm.

[0046] Furthermore, the second cavity 009 encloses the electroacoustic conversion chip 0010 and the electrical signal processing chip 0011. The electrical signal processing chip 0011 is located on the side of the electroacoustic conversion chip 0010 away from the third sound inlet 005, so as to avoid signal interference when the two are working.

[0047] The structures of the first sound inlet 007, the second sound inlet 004, and the third sound inlet 005 are adapted to the independent setting of the first cavity 008 and the second cavity 009. The aperture of the first sound inlet 007 is slightly larger than that of the second sound inlet 004 and the third sound inlet 005. The inner walls of the first sound inlet 007, the second sound inlet 004, and the third sound inlet 005 are all polished to form a smooth surface, so as to avoid the reflection interference caused by the roughness of the inner wall when the sound wave propagates in the hole, so as to form an independent sound inlet path pointing to the MEMS diaphragm.

[0048] Working principle: When sound waves from the external environment need to be received by the microphone, the sound waves first enter through the first sound inlet 007 at the top of the second circuit board 006. Since the first sound inlet 007 is directly connected to the first cavity 008, the sound waves immediately enter the interior of the first cavity 008. Subsequently, the sound waves are transmitted along the bottom opening of the first cavity 008 to the second sound inlet 004, and then enter the connecting cavity 003 inside the first circuit board 001 through the second sound inlet 004. Since the connecting cavity 003 is also connected to the third sound inlet 005, the sound waves are redirected within the connecting cavity 003 and then act on the MEMS diaphragm of the electroacoustic conversion chip 0010 through the third sound inlet 005. At this time, the MEMS diaphragm vibrates under the pressure of the sound waves, converting the acoustic signal into a corresponding electrical signal. This electrical signal is transmitted to the telecommunications network through the gold wire 0012. The signal processing chip 0011 amplifies and filters the electrical signal, which is then transmitted to the electrical connection PAD002 on the surface of the first circuit board 001 via the gold wire 0012. Finally, the electrical connection PAD002 outputs the processed electrical signal to the external circuit, completing the entire process of "sound-to-electrical conversion-signal processing-signal output". In this process, the second cavity 009 serves as a closed space to enclose the MEMS and is located on the side of the MEMS away from the third sound inlet 005, forming the back cavity required for the vibration of the MEMS diaphragm. This prevents the back of the MEMS diaphragm from directly contacting the external environment and ensures that the sound waves only act on the MEMS diaphragm through the preset sound inlet channel and do not directly communicate with the internal space of the second cavity 009, thus ensuring the stability of the MEMS diaphragm vibration and the purity of the electrical signal.

[0049] This application replaces the existing three-layer stacked board structure with a dual-board structure design of the first circuit board 001 and the second circuit board 006, reducing redundant interlayer connection structures and significantly simplifying the overall structure of the microphone. Simultaneously, the first circuit board 001 and the second circuit board 006 form a closed space through an edge-encircling connection, eliminating the need for complex interlayer soldering and positioning structures, thus reducing structural design difficulty. The second cavity 009, as a completely enclosed structure that encloses the electroacoustic conversion chip 0010, effectively isolates impurities such as solder paste and flux from the external environment, preventing direct contact between impurities and the MEMS diaphragm, which could lead to performance degradation. Compared to the unprotected diaphragm structure of a back-entry microphone, this significantly improves the protection capability of the electroacoustic conversion chip 0010 and reduces performance problems caused by impurity interference. The second cavity 009, as a dedicated back cavity for the MEMS diaphragm, provides a stable pressure environment for the MEMS diaphragm vibration. Furthermore, the independent structure of "first sound inlet 007 - first cavity 008 - second sound inlet 004 - connecting cavity 003 - third sound inlet 005"... The sound inlet channel structure, combined with the smooth inner wall treatment and aperture adaptation design of the first sound inlet hole 007, the second sound inlet hole 004, and the third sound inlet hole 005, reduces reflection interference during sound wave propagation, ensuring that sound waves accurately act on the MEMS diaphragm. This effectively achieves the high signal-to-noise ratio performance of the back-entry microphone, solving the problem of insufficient signal-to-noise ratio in traditional front-entry microphones. In addition, the spaced arrangement of the electroacoustic conversion chip 0010 and the electrical signal processing chip 0011 on the first circuit board 001 avoids signal interference between the two during operation, ensuring the stability of electrical signal processing. The edge-encircling connection structure between the second circuit board 006 and the first circuit board 001 ensures the sealing of the second cavity 009, reducing cavity crosstalk problems caused by poor structural sealing, further improving the product yield. At the same time, the dual-board structure is easier to process and form than the three-layer stacked board, reducing material usage and processing steps, significantly reducing the product manufacturing cost, and comprehensively solving the contradiction between structural complexity, protection capability, signal-to-noise ratio, and cost in existing microphones.

[0050] Example 2

[0051] Reference Figures 5-8The diagram shows the second embodiment of the present invention, which is based on the previous embodiment. The difference is that the second circuit board 006 is configured as an outer shell 0013 and an inner shell 0014. The outer shell 0013 and the inner shell 0014 form a double-layered enclosure structure, with the outer shell 0013 covering the outer shell 0014. Both are disposed on the upper surface of the first circuit board 001, forming a first cavity 008 and a second cavity 009. A first sound inlet 007 is located at the top of the outer shell 0013 and penetrates along the thickness direction of the outer shell 0013. The first cavity 008 is a closed space formed by the outer shell 0013, the inner shell 0014, and the first circuit board 001. The second cavity 009 is formed by the inner shell 0014 and the first circuit board. The two cavities 001 and 009 together form a closed space. The second cavity 009 encloses the electroacoustic conversion chip 0010 and the electrical signal processing chip 0011. A gap is left between the inner wall of the second cavity 009 and the outer wall of the electroacoustic conversion chip 0010, maintaining the position of the electroacoustic conversion chip 0010 away from the third sound inlet hole 005. The first cavity 008 is an independent closed space formed by splicing the outer shell 0013 and the inner shell 0014. Its top is connected to the first sound inlet hole 007 on the outer shell 0013. The bottom opening of the second cavity 009 is connected to the second sound inlet hole 004 on the first circuit board 001, ensuring that sound waves can enter the first cavity 008 and the second cavity 009 from the first sound inlet hole 007. The second cavity 009 is connected to the first sound inlet hole 007 and the second sound inlet hole 004 in sequence.

[0052] Furthermore, the outer shell 0013 and the inner shell 0014 are welded and fixedly connected to form a double-layer cover structure, and are welded and fixed as a whole to the upper surface of the first circuit board 001. The outer shell 0013 and the inner shell 0014 are fixed around the outer periphery of the first cavity 008 and the second cavity 009 to ensure the sealing of the first cavity 008 and the second cavity 009. At the same time, the second sound inlet 004 and the third sound inlet 005 are still retained on the first circuit board 001.

[0053] In this embodiment 2, the second circuit board 006 in embodiment 1 is replaced with a double-layer cover structure consisting of an outer shell 0013 and an inner shell 0014. Firstly, the double-layer cover structure of the outer shell 0013 and inner shell 0014 is easier to process into complex cavity structures compared to the second circuit board 006 composed of an FR-4 circuit board, eliminating the need for internal etching or injection molding processes on the second circuit board 006, thus simplifying the manufacturing process of the first cavity 008 and the second cavity 009 and reducing processing difficulty. Secondly, the double-layer cover structure of the outer shell 0013 and inner shell 0014... The enclosure-type structure provides better sealing and can more reliably isolate external solder paste, flux and other impurities, further enhancing the protection capability of the electroacoustic conversion chip 0010 and reducing performance problems caused by impurity interference. Thirdly, the outer shell 0013 and the inner shell 0014 are fixed by welding or bonding, which is more flexible than the reflow soldering of the first circuit board 001 and the second circuit board 006. This allows for the adaptation to cavity designs of different sizes, and there is no need to strictly match the interlayer positioning of the first circuit board 001 and the second circuit board 006 during assembly, improving packaging compatibility and product yield.

[0054] Example 3

[0055] Reference Figures 9-12 As shown, this is the third embodiment of the present invention. This embodiment is based on the above two embodiments, except that the second circuit board 006 is configured as a first housing 0015 and a second housing 0016. The first housing 0015 and the second housing 0016 are arranged at intervals on the first circuit board 001. The first sound inlet hole 007 is opened at the top of the second housing 0016 and penetrates along the thickness direction of the second housing 0016. The inner wall is polished to reduce sound wave reflection interference.

[0056] Furthermore, both the first housing 0015 and the second housing 0016 are independent cover-like structures with open bottoms. The first housing 0015 and the second housing 0016 are independently fixed to the upper surface of the first circuit board 001 by welding or bonding processes. The fixing areas of the first housing 0015 and the second housing 0016 surround the edge of their respective covers to ensure that there are no gaps in the connection with the circuit board.

[0057] Furthermore, the first cavity 008 is enclosed by the second housing 0016 and the first circuit board 001 to form a closed space, and the second cavity 009 is enclosed by the first housing 0015 and the first circuit board 001 to form an independent closed space. The top of the first cavity 008 is directly connected to the first sound inlet hole 007 on the second housing 0016, and the bottom opening is connected to the second sound inlet hole 004 on the first circuit board 001. The second cavity 009 is used to enclose the electroacoustic conversion chip 0010 and the electrical signal processing chip 0011. A gap is left between the inner wall and the outer wall of the electroacoustic conversion chip 0010, and it maintains the positional feature of being located on the side of the electroacoustic conversion chip 0010 away from the third sound inlet hole 005.

[0058] Compared to the dual-circuit board structure of Embodiment 1 and the inner and outer double-layer nested shell structure of Embodiment 2, the independent spacing design of the first shell 0015 and the second shell 0016 makes the functional division of the first cavity 008 and the second cavity 009 clearer. The size of each shell can be optimized individually according to the chip specifications and sound intake requirements, resulting in stronger adaptability. The independent manufacturing and assembly mode of the first shell 0015 and the second shell 0016 reduces the impact of a single structural defect on the overall product. If the sealing of the first shell 0015 or the second shell 0016 is problematic, only the corresponding shell needs to be replaced, which greatly reduces production and maintenance costs. At the same time, the spacing arrangement reduces vibration conduction and heat transfer between the first cavity 008 and the second cavity 009, avoids the acoustic vibration of the second cavity 009 from interfering with the closed environment of the first cavity 008, further ensures the stability of MEMS diaphragm vibration, improves the purity of electrical signal output, and continues the core advantage of high signal-to-noise ratio.

[0059] Finally, the following points should be noted: First, in the description of this application, it should be noted that, unless otherwise specified and limited, the terms "installation", "connection", and "linkage" should be interpreted broadly, and can be mechanical or electrical connections, or internal connections between two components, or direct connections. "Up", "down", "left", "right", etc. are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may change.

[0060] Secondly: The accompanying drawings of the embodiments disclosed in this utility model only involve the structures involved in the embodiments disclosed in this utility model. Other structures can refer to the general design. In the absence of conflict, the same embodiment and different embodiments of this utility model can be combined with each other.

[0061] Finally: The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A high signal-to-noise ratio forward-sound MEMS microphone, characterized in that, include: A first circuit board (001) has an electrical connection PAD (002) etched on its surface. The first circuit board (001) is integrally formed with a connecting cavity (003). The first circuit board (001) has a second sound inlet (004) and a third sound inlet (005). The connecting cavity (003) is connected to the second sound inlet (004) and the third sound inlet (005) respectively. The second circuit board (006) has a first sound inlet hole (007) extending through its top along the thickness direction, and forms an independent first cavity (008) and a second cavity (009) inside. The second cavity (009) is sequentially connected to the first sound inlet hole (007) and the second sound inlet hole (004). An electroacoustic conversion chip (0010) and an electrical signal processing chip (0011) are disposed inside the second cavity (009). The electroacoustic conversion chip (0010) and the electrical signal processing chip (0011) are arranged at intervals on the first circuit board (001). Gold wires (0012) are respectively soldered between the electroacoustic conversion chip (0010) and the electrical signal processing chip (0011), and between the electrical signal processing chip (0011) and the first circuit board (001); The second circuit board (006) is fixed on the first circuit board (001). The second circuit board (006) is arranged around the outer periphery of the first cavity (008) and the second cavity (009). The second circuit board (006) and the first circuit board (001) enclose each other to form a closed structure to form the first cavity (008). The first sound inlet (007), the first cavity (008), the second sound inlet (004), the connecting cavity (003), and the third sound inlet (005) together constitute a sound inlet channel pointing to the MEMS.

2. The high signal-to-noise ratio forward-sound MEMS microphone as described in claim 1, characterized in that: The closed structure formed by the second circuit board (006) and the first circuit board (001) is the second cavity (009). The second cavity (009) encloses the electroacoustic conversion chip (0010), and the second cavity (009) is located on the side of the electroacoustic conversion chip (0010) away from the third sound inlet (005).

3. The high signal-to-noise ratio forward-sound MEMS microphone as described in claim 2, characterized in that: The electroacoustic conversion chip (0010) has a MEMS diaphragm, and the sound inlet channel formed by the first sound inlet hole (007), the first cavity (008), the second sound inlet hole (004), the connecting cavity (003), and the third sound inlet hole (005) points towards the MEMS diaphragm.

4. The high signal-to-noise ratio forward-sound MEMS microphone as described in claim 3, characterized in that: The second cavity (009) encloses the electroacoustic conversion chip (0010) and the electrical signal processing chip (0011).

5. The high signal-to-noise ratio forward-sound MEMS microphone as described in claim 4, characterized in that: The second circuit board (006) is configured to have an outer shell (0013) and an inner shell (0014) disposed on the upper surface of the first circuit board (001), the outer shell (0013) covering the outside of the inner shell (0014), and the first sound inlet (007) is opened on the top of the outer shell (0013); The first cavity (008) is a closed space formed by the outer shell (0013), the inner shell (0014) and the first circuit board (001). The first cavity (008) is an independent closed space formed by splicing the outer shell (0013) and the inner shell (0014). The second cavity (009) is formed by the inner shell (0014) and the first circuit board (001). The top of the first cavity (008) is connected to the first sound inlet hole (007) on the outer shell (0013), and the bottom opening of the first cavity (008) is connected to the second sound inlet hole (004) on the first circuit board (001).

6. The high signal-to-noise ratio forward-sound MEMS microphone as described in claim 5, characterized in that: The second circuit board (006) is configured as a first housing (0015) and a second housing (0016), the first housing (0015) and the second housing (0016) being arranged at a distance on the first circuit board (001), and the first sound inlet (007) being opened on the top of the second housing (0016).

7. The high signal-to-noise ratio forward-sound MEMS microphone as described in claim 6, characterized in that: Both the first housing (0015) and the second housing (0016) are independent cover-like structures with open bottoms; The first cavity (008) is enclosed by the second shell (0016) and the first circuit board (001) to form a closed space, and the second cavity (009) is enclosed by the first shell (0015) and the first circuit board (001) to form an independent closed space.

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