Dust-proof structure for MEMS devices and MEMS microphone packaging structure

Abstract

The present invention discloses a dustproof structure for a MEMS device and a MEMS microphone packaging structure. The dustproof structure for the MEMS device comprises a mesh membrane and a carrier in a columnar structure. The mesh membrane has a fixed connection area and a sound-transmitting area. The fixed connection area surrounds the sound-transmitting area and is located at the edge of the mesh membrane. The carrier has a through opening, and the opening corresponds to the position of the sound-transmitting area. The carrier has a first end face and a second end face opposite to each other. The first end face is connected to one side of the fixed connection area, and the second end face is configured to form a connection with a substrate of the MEMS device. The outer contour of the carrier at the first end face along the circumference of the columnar structure is larger than the outer contour of the carrier at the second end face along the circumference of the columnar structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of acoustic-electric conversion, and in particular, relates to a dustproof structure for a MEMS device and a MEMS microphone packaging structure. Background Art

[0002] With the rapid development of electroacoustic technology, various electroacoustic products emerge in an endless stream. Microphone, as a transducer device that converts sound signals into electrical signals, is one of the most important devices in electroacoustic products. Nowadays, microphones have been widely used in many different types of electronic products such as mobile phones, tablets, laptops, VR devices, AR devices, and smart wearables. In recent years, the design of microphone packaging structure has become the focus and hot spot of research for technicians in this field.

[0003] The existing microphone packaging structure is usually composed of a housing with a housing cavity, in which components such as chip components (for example, MEMS chips and ASIC chips) are fixed; and a sound pickup hole is also provided on the housing. Therefore, it is found in long-term applications that dust, impurities and other particles and foreign objects from the outside are easily introduced into the microphone's housing cavity through the sound pickup hole. These particles and foreign objects from the outside will cause certain damage to components such as chip components in the housing cavity, and will eventually affect the acoustic performance and service life of the microphone.

[0004] In view of the above technical problems, the current solution is usually to set a corresponding isolation component on the sound pickup hole of the microphone packaging structure to prevent the entry of external particles, foreign objects, etc. The existing isolation component generally includes a carrier and an isolation mesh. When the isolation component is used, the isolation component is installed on the sound pickup hole.

[0005] When the existing isolation component is installed in a MEMS microphone packaging structure, for example, when it is installed on a PCB board in the MEMS microphone packaging structure, the bonding method generally adopted is adhesive bonding. First, the adhesive is applied to the PCB board, and then the isolation component is placed on the PCB board for bonding. When various bonding conditions, such as the amount of adhesive, the location of adhesive distribution, the viscosity of the adhesive, the thickness of the carrier, the placement pressure, etc. are not fully optimized, the adhesive is very likely to overflow, and the overflowed adhesive will flow along the side wall of the carrier to the top of the isolation mesh. The overflowed adhesive is very likely to contaminate and block the isolation mesh, thereby affecting the airflow on the isolation mesh, and further causing the acoustic quality of the microphone to deteriorate. In view of this, it is necessary to provide a new technical solution to solve the above technical problems. Summary of the invention

[0006] An object of the present invention is to provide a dustproof structure for a MEMS device and a MEMS microphone packaging structure.

[0007] According to a first aspect of the present invention, there is provided a dustproof structure for a MEMS device, comprising:

[0008] A mesh membrane, wherein the mesh membrane has a fixed connection area and a sound-transmitting area, wherein the fixed connection area surrounds the sound-transmitting area and is located at an edge of the mesh membrane;

[0009] A carrier in a columnar structure, the carrier having a through opening, the opening corresponding to the position of the sound-transmitting area, the carrier having a first end surface and a second end surface opposite to each other, the first end surface being connected to one side of the fixed connection area, and the second end surface being configured to form a connection with a substrate of a MEMS device;

[0010] An outer contour of the carrier at the first end surface along the circumference of the columnar structure is larger than an outer contour of the carrier at the second end surface along the circumference of the columnar structure.

[0011] Optionally, the carrier is in a conical columnar structure, and the area of ​​the second end surface is smaller than the area of ​​the first end surface.

[0012] Optionally, the carrier includes at least two carrier layers, the first end surface is located on a first carrier layer among the carrier layers, the first carrier layer is connected to one side of the fixed connection area, the other carrier layers are stacked in sequence along the thickness direction of the mesh membrane and distributed on a side of the first carrier layer away from the mesh membrane, and the second end surface is located on the carrier layer farthest from the mesh membrane among the carrier layers;

[0013] At least the outer contour of the carrier layer farthest from the grid membrane along the circumference of the columnar structure is smaller than the outer contour of the first carrier layer along the circumference of the columnar structure.

[0014] Optionally, along the direction from close to the grid membrane to far away from the grid membrane, the outer contour of each carrier layer along the circumference of the columnar structure decreases successively.

[0015] Optionally, the carrier is configured to be pre-fixed on the grid film, and the outer contour and the opening are formed by a photolithography process;

[0016] The first carrier layer and the second carrier layer are formed by two photolithography processes respectively.

[0017] Optionally, the carrier is configured to be formed by a photolithography process;

[0018] A conical photolithography structure having a complementary angle to the carrier is pre-formed on the grid film, the carrier is formed between the conical photolithography structures, and the conical photolithography structure is removed by a photolithography process.

[0019] Optionally, the carrier is configured to be pre-fixed on the grid film, and the outer contour and the opening are formed by a photolithography process.

[0020] Optionally, the material of the carrier is a metal material, and the carrier is configured to be made by a metal electroplating process.

[0021] According to another aspect of the present invention, a MEMS microphone packaging structure is provided, comprising:

[0022] A shell having a receiving cavity, wherein a sound hole is provided on the shell, and the sound hole connects the inside and the outside of the shell;

[0023] A microphone device, wherein the microphone device is fixedly disposed in the housing;

[0024] In the dustproof structure as described above, an adhesive is coated between the second end surface of the carrier and the shell, and the second end surface is bonded and fixed to the shell by a high-temperature bonding and curing process;

[0025] The mesh membrane closes the sound hole; and / or the mesh membrane is spaced between the sound hole and the microphone device.

[0026] Optionally, a side wall of the carrier close to the second end surface is a glue overflow surface, and the adhesive is disposed on the glue overflow surface.

[0027] One technical effect of the present invention is that in the dust-proof structure for MEMS devices provided in an embodiment of the present invention, the carrier has a first end face and a second end face relative to each other. Since the outer contour of the carrier along the circumference of the columnar structure at the first end face is designed to be larger than the outer contour of the carrier along the circumference of the columnar structure at the second end face, when the adhesive overflows, the adhesive will encounter great resistance when climbing upward along the side wall of the carrier, thereby greatly reducing the possibility of the adhesive climbing to the top of the grid membrane, thereby avoiding the situation where the adhesive contaminates the sound-transmitting area of ​​the grid membrane to a large extent, ensuring the airflow in the sound-transmitting area.

[0028] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0030] Figure 1 It is a schematic diagram of a dustproof structure in the prior art;

[0031] Figure 2A schematic diagram of a dustproof structure for a MEMS device provided in an embodiment of the present invention Figure 1 ;

[0032] Figure 3 A schematic diagram of a dustproof structure for a MEMS device provided in an embodiment of the present invention Figure 2 ;

[0033] Figure 4 Schematic diagram of photolithography process Figure 1 ;

[0034] Figure 5 Schematic diagram of photolithography process Figure 2 ;

[0035] Figure 6 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 1 ;

[0036] Figure 7 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 2 ;

[0037] Figure 8 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 3 ;

[0038] Fig. 9 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 4 ;

[0039] Fig.10 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 5 . DETAILED DESCRIPTION

[0040] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0041] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0042] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0043] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0044] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0045] An embodiment of the present invention provides a dustproof structure for a MEMS device, which includes a grid membrane 1 and a carrier 2 with a columnar structure, wherein the grid membrane 1 has a fixed connection area 11 and a sound-transmitting area 12, wherein the fixed connection area 11 surrounds the sound-transmitting area 12, and the fixed connection area 11 is located at the edge of the grid membrane 1; the carrier 2 has a through opening 21, and the opening 21 corresponds to the position of the sound-transmitting area 12; the carrier 2 has a first end face 201 and a second end face 202 opposite to each other, wherein the first end face 201 is connected to one side of the fixed connection area 11, and the second end face 202 is configured to form a connection with a substrate of the MEMS device; the outer contour of the carrier 2 along the circumference of the columnar structure at the first end face 201 is larger than the outer contour of the carrier 2 along the circumference of the columnar structure at the second end face 202.

[0046] Similar dust-proof structures in the prior art, refer to Figure 1 As shown, the outer contour of the carrier 2' along the circumference of the columnar structure is generally set to a uniform structure at all places, for example, the carrier 2' is a cylindrical structure. In this way, when the dustproof structure is bonded to the substrate of the MEMS device using an adhesive, the adhesive will easily crawl along the side wall of the carrier 2' to the top of the grid film 1' after overflowing. In the dustproof structure for MEMS devices provided in the embodiment of the present invention, reference Figure 2 , Figure 3 As shown, the carrier 2 has a first end face 201 and a second end face 202 relative to each other. Since the outer contour of the carrier 2 along the circumference of the columnar structure at the first end face 201 is designed to be larger than the outer contour of the carrier 2 along the circumference of the columnar structure at the second end face 202, when the adhesive overflows, the adhesive will encounter great resistance when climbing upward along the side wall of the carrier 2, thereby greatly reducing the possibility of the adhesive climbing to the top of the grid membrane 1, thereby avoiding the situation where the adhesive contaminates the sound-transmitting area 12 of the grid membrane 1 to a large extent, ensuring the airflow in the sound-transmitting area 12.

[0047] refer to Figure 2 As shown, in one embodiment, the carrier 2 is in a conical columnar structure, and the area of ​​the second end surface 202 is smaller than the area of ​​the first end surface 201 .

[0048] In this embodiment, the cross section of the carrier 2 presents an inverted cone structure, the outer side wall of the carrier 2 is inclined, and the outer contour of the carrier 2 in the circumferential direction tends to gradually increase from the direction away from the mesh membrane 1 to the direction close to the mesh membrane 1, that is, from the second end face 202 to the first end face 201. In this way, when the adhesive overflows from the second end face 202 and climbs upward along the outer side wall of the carrier 2, it is equivalent to crawling on a steep wall, and the crawling resistance will gradually increase, so the adhesive cannot climb to the top of the mesh membrane 1 to a large extent, thereby avoiding the situation where the adhesive contaminates the sound-transmitting area 12 of the mesh membrane 1 to a large extent, and ensuring the airflow of the sound-transmitting area 12.

[0049] refer to Figure 3 As shown, in one embodiment, the carrier 2 includes at least two carrier layers, the first end face 201 is located on the first carrier layer 22 among the carrier layers, the first carrier layer 22 is connected to one side of the fixed connection area 11, and the other carrier layers are stacked in sequence along the thickness direction of the grid membrane 1 on the side of the first carrier layer 22 away from the mesh membrane, and the second end face 202 is located on the carrier layer among the carrier layers that is farthest from the grid membrane 1; at least the outer contour of the carrier layer farthest from the grid membrane 1 along the circumference of the columnar structure is smaller than the outer contour of the first carrier layer 22 along the circumference of the columnar structure.

[0050] In this embodiment, the circumferential outer contour can be designed to decrease layer by layer from the first carrier layer 22 to the carrier layer farthest from the grid membrane 1, forming a structure similar to a step, that is, along the direction from close to the grid membrane 1 to far away from the grid membrane 1, the circumferential outer contour of each carrier layer along the columnar structure decreases in sequence; or the circumferential outer contour of the carrier layer farthest from the grid membrane 1 is designed to be smaller than the circumferential outer contour of the first carrier layer 22, and the circumferential outer contours of the remaining layers are equal to the circumferential outer contour of the first carrier layer 22, which will also form a step structure between the carrier layer farthest from the grid membrane 1 and the carrier layer adjacent thereto. Therefore, when the adhesive overflows from the second end surface 202 and climbs upward along the outer wall of the carrier 2, when it climbs to the step structure, the step surface will block the adhesive from continuing to climb, thereby largely avoiding the situation where the adhesive contaminates the sound-permeable area 12 of the grid membrane 1, ensuring the airflow of the sound-permeable area 12.

[0051] In one embodiment, the carrier 2 is configured to be pre-fixed on the grid film 1, and the outer contour and the opening 21 are formed by a photolithography process; the first carrier layer 22 and the second carrier layer 23 are formed by two photolithography processes respectively.

[0052] The photolithography process is specifically as follows: Figure 4As shown, a sacrificial layer b of organic material, a metal layer c and a carrier layer are sequentially stacked on a bottom plate a, the carrier layer is arranged opposite to a photolithography device, the carrier layer is etched by the photolithography device to obtain the outer contour of the carrier layer and the opening 21, and then the sacrificial layer b is removed and separated from the bottom plate a. Since the first carrier layer 22 and the second carrier layer 23 have different outer contours, they are formed by two photolithography processes respectively, so that the outer contour of the first carrier layer 22 along the circumference of the columnar structure is larger than the outer contour of the second carrier layer 23 along the circumference of the columnar structure.

[0053] A conical photolithography structure having a complementary angle to the carrier 2 is pre-formed on the grid film 1, the carrier 2 is formed between the conical photolithography structures, and the conical photolithography structure is removed by a photolithography process.

[0054] In this embodiment, reference Figure 5 As shown, a sacrificial layer b of organic material, a metal layer c and a conical photolithography structure d having a complementary angle to the carrier 2 are sequentially stacked on a base plate a, and the conical photolithography structure d is etched by a photolithography device to remove the conical photolithography structure d, thereby deforming the carrier layer into an inverted cone. Finally, the sacrificial layer b is removed and detached from the base plate a.

[0055] It should be noted that when the carrier layer is formed by a photolithography process, multiple carrier layers with dustproof structures can be etched simultaneously on one base plate a.

[0056] In one embodiment, the material of the carrier 2 is a metal material, and the carrier 2 is configured to be made by a metal electroplating process, but is not limited to the metal electroplating process, for example, it can also be a chemical deposition process, etc., and the present invention is not limited to this.

[0057] The embodiment of the present invention also provides a MEMS microphone packaging structure, which includes a shell 3 with a accommodating cavity, and a sound hole 4 is provided on the shell 3, and the sound hole 4 connects the inside and outside of the shell 3; the MEMS microphone packaging structure also includes a microphone device and the dustproof structure as described above, and the microphone device is fixedly arranged in the shell 3; an adhesive is coated between the second end face 202 of the carrier 2 and the shell, and the second end face 202 is bonded and fixed to the shell through a high-temperature bonding and curing process; the mesh membrane 1 closes the sound hole; and / or the mesh membrane is spaced between the sound hole and the microphone device. In one embodiment, the side wall of the carrier close to the second end face 202 is a glue overflow surface, and the glue overflow surface has the adhesive.

[0058] The MEMS microphone packaging structure can be applied to various types of electronic products such as mobile phones, laptops, iPads, VR devices, and smart wearable devices, and its application is relatively wide. The MEMS microphone packaging structure provided by the embodiment of the present invention can effectively prevent the internal microphone device and other components from being damaged by external dust, impurities and other particles and foreign matter, and can extend the service life of the microphone, and can also enable the microphone to maintain excellent acoustic performance.

[0059] refer to Figure 6-Figure 10 As shown, the microphone packaging structure of the present invention has a shell 3 structured as follows: it includes a substrate 32 and a packaging cover 31, and the substrate 32 and the packaging cover 31 together enclose the accommodating cavity. The dustproof structure is accommodated in the accommodating cavity of the shell 3. Specifically, the sound hole 4 is opened on the substrate 32, and the microphone device includes a MEMS chip 5 and a signal amplifier 6 connected to each other. Among them, the MEMS chip 5 includes a substrate and a sensing film, and the substrate is a hollow structure. The sensing film is, for example, a piezoelectric element, a capacitor element, a piezoresistive element, etc. The sensing film is arranged at one end of the substrate and covers the hollow structure of the substrate, and the hollow structure forms a back cavity, which is connected to the sound hole 4, and the MEMS chip 5 is mounted on the substrate 32.

[0060] In an optional example of the present invention, Figure 6 As shown, the dustproof structure is located in the housing cavity of the housing 3 and covers the acoustic hole 4. Specifically, the carrier 2 is connected to the substrate 32 and is arranged around the acoustic hole 4. The mesh membrane 1 is arranged opposite to the acoustic hole 4 to prevent external dust, impurities and other particles and foreign matter from entering the housing cavity of the housing 3 through the acoustic hole 4. Figure 3 In the illustrated embodiment, the dustproof structure is entirely located in the back cavity of the MEMS chip 5 , and the external airflow first passes through the filtering effect of the mesh membrane 1 of the dustproof structure before entering the back cavity of the chip 5 .

[0061] In an optional example of the present invention, Figure 7 As shown, the dustproof structure is located in the housing cavity of the housing 3 and covers the acoustic hole 4. Specifically, the carrier 2 is connected to the substrate 32 and is arranged around the acoustic hole 4. The mesh membrane 1 is arranged opposite to the acoustic hole 4 to prevent external dust, impurities and other particles and foreign matter from entering the housing cavity of the housing 3 through the acoustic hole 4. Figure 4 In the embodiment shown, the MEMS chip 5 is connected to the side of the grid membrane 1 of the dustproof structure away from the carrier 2, specifically connected to the side of the fixed connection area 11 away from the carrier 2. The external airflow first passes through the filtering effect of the grid membrane 1 of the dustproof structure before entering the back cavity of the chip 5.

[0062] Of course, the dustproof structure of the present invention may also have other configuration modes:

[0063] For example, Figure 8 As shown, the sound hole 4 is opened on the packaging cover 31, and the dustproof structure cover is arranged at a position on the packaging cover 31 corresponding to the sound hole 4 and is located outside the housing 3. Fig. 9 As shown, the sound hole 4 is opened on the packaging cover 31, and the dustproof structure cover is arranged at a position on the packaging cover 31 corresponding to the sound hole 4 and is located in the accommodating cavity of the housing 3. The position of the dustproof structure corresponds to the sound hole 4, which can prevent external particles and foreign objects from being introduced into the microphone packaging structure through the sound hole 4. For another example, Fig.10 As shown, the sound hole 4 is located on the packaging cover 31, and the dustproof structure is fixedly connected to the substrate 32 at a position corresponding to the sound hole 4. At this time, the dustproof structure can effectively protect the microphone device in the microphone packaging structure.

[0064] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A dustproof structure for a MEMS device, characterized in that: include: Grid The mesh membrane has a fixed connection area and a sound-transmitting area, the fixed connection area surrounds the sound-transmitting area, and the fixed connection area is located at the edge of the mesh membrane; A carrier in a columnar structure, the carrier having a through opening, the opening corresponding to the position of the sound-transmitting area, the carrier having a first end surface and a second end surface opposite to each other, the first end surface being connected to one side of the fixed connection area, and the second end surface being configured to form a connection with a substrate of a MEMS device; The outer contour of the carrier at the first end surface along the circumference of the columnar structure is larger than the outer contour of the carrier at the second end surface along the circumference of the columnar structure, and the carrier is configured to be pre-fixed on the grid film, and the outer contour and the opening are formed by a photolithography process; The carrier is a conical columnar structure, and the area of ​​the second end face is smaller than the area of ​​the first end face; the carrier is configured to be formed by a photolithography process; a plurality of conical photolithography structures having complementary angles to the carrier are pre-formed on the grid film, a plurality of the carriers are formed between the conical photolithography structures, and the plurality of the conical photolithography structures are removed by a photolithography process.

2. The dustproof structure according to claim 1, characterized in that: The material of the carrier is a metal material, and the carrier is configured to be made by a metal electroplating process.

3. A MEMS microphone packaging structure, characterized in that: include: A shell having a receiving cavity, wherein a sound hole is provided on the shell, and the sound hole connects the inside and the outside of the shell; A microphone device, wherein the microphone device is fixedly disposed in the housing; The dustproof structure according to claim 1 or 2, wherein an adhesive is coated between the second end surface of the carrier and the shell, and the second end surface is bonded and fixed to the shell by a high-temperature bonding and curing process; The mesh membrane closes the sound hole; and / or the mesh membrane is spaced between the sound hole and the microphone device.

4. The MEMS microphone packaging structure according to claim 3, characterized in that: The side wall of the carrier close to the second end surface is a glue overflow surface, and the adhesive is disposed on the glue overflow surface.

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