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, wherein the dustproof structure for a MEMS device comprises a mesh membrane and a carrier, 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 the edge of the mesh membrane; the carrier has a through opening, wherein the opening corresponds to the position of the sound-transmitting area, and the carrier comprises at least two carrier layers, wherein a first carrier layer of the carrier layers is connected to one side of the fixed connection area, and other carrier layers are sequentially stacked and distributed on a side of the first carrier layer away from the mesh diaphragm along the thickness direction of the mesh membrane, and each carrier layer has a different thermal expansion coefficient.

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 response to the above technical problems, the solution currently adopted is usually to set a corresponding isolation component on the sound pickup hole of the microphone packaging structure to block the entry of external particles, foreign objects, etc. The existing isolation component generally includes a support part and an isolation mesh. When using the isolation component, the isolation component is installed on the sound pickup hole. However, due to the differences in size, material, structure, etc. between the support part and the isolation mesh of the existing isolation component, a certain internal stress difference is likely to be generated at the connection position between the two; in particular, the support part in the prior art only has a single-layer structure. During hot pressing, due to the different thermal expansion coefficients of the support part and the isolation mesh, the thermal expansion coefficients of the two may even differ greatly, so there will be a large difference in the deformation after heating. The above factors will cause the reticle on the isolation mesh to warp and deform, and the reticle cannot be guaranteed to be in a flat state, which will in turn cause the quality of the product to decline and even affect the airflow at the reticle. Summary of the invention

[0005] An object of the present invention is to provide a dustproof structure for a MEMS device and a MEMS microphone packaging structure.

[0006] According to a first aspect of the present invention, there is provided a dustproof structure for a MEMS device, characterized in that it comprises:

[0007] 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;

[0008] A carrier having a through opening, wherein the opening corresponds to the position of the sound-permeable area, and the carrier comprises at least two carrier layers, wherein a first carrier layer is connected to one side of the fixed connection area, and other carrier layers are sequentially stacked and distributed along the thickness direction of the mesh membrane on a side of the first carrier layer away from the mesh diaphragm, and each carrier layer has a different thermal expansion coefficient.

[0009] Optionally, the thermal expansion coefficient of the grid film is smaller than the thermal expansion coefficient of the first carrier layer, and the thermal expansion coefficients of the carrier layers decrease in sequence along a direction away from the grid film.

[0010] Optionally, the thermal expansion coefficient of the grid film is greater than the thermal expansion coefficient of the first carrier layer, and the thermal expansion coefficients of the carrier layers increase sequentially in a direction away from the grid film.

[0011] Optionally, the mesh membrane is an isolation mesh made of metal as a substrate.

[0012] Optionally, at least one of the carrier layers is made of inorganic non-metallic material or organic material.

[0013] Optionally, the carrier is configured to be pre-fixed on the grid membrane, and the opening is formed by an etching process.

[0014] Optionally, the first carrier layer and at least another carrier layer have different orthographic projection shapes on the grid film, and the first carrier layer and another carrier layer are configured to be formed respectively by two etching processes.

[0015] Optionally, the carrier includes two carrier layers, namely a first carrier layer and a second carrier layer, and the thermal expansion coefficient of the first carrier layer is greater than the thermal expansion coefficient of the second carrier layer;

[0016] Alternatively, the carrier includes three carrier layers, namely a first carrier layer, a second carrier layer and a third carrier layer, the second carrier layer is located between the first carrier layer and the third carrier layer, the thermal expansion coefficient of the first carrier layer is greater than the thermal expansion coefficient of the second carrier layer, and the thermal expansion coefficient of the second carrier layer is greater than the thermal expansion coefficient of the third carrier layer.

[0017] Optionally, the first carrier layer and at least one other carrier layer have different thicknesses.

[0018] According to another aspect of the present invention, a MEMS microphone packaging structure is provided, comprising:

[0019] 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;

[0020] A microphone device, wherein the microphone device is fixedly disposed in the housing;

[0021] In the dustproof structure as described above, the carrier layer of the carrier away from the grid film is fixedly connected to the shell through a high-temperature bonding and curing process;

[0022] The mesh membrane closes the sound hole; and / or the mesh membrane is spaced between the sound hole and the microphone device.

[0023] One technical effect of the present invention is that a dust-proof structure for a MEMS device provided by an embodiment of the present invention, since the carrier includes at least two carrier layers and the thermal expansion coefficients of the carrier layers are different, can effectively alleviate the stress after heating and cooling, prevent the mesh membrane from undergoing large warping deformation, and ensure that the sound-transmitting area of ​​the mesh membrane is basically in a flat state, which is conducive to the smooth flow of air here and will not have an adverse effect on the movement of the airflow.

[0024] 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

[0025] 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.

[0026] Figure 1 A schematic diagram of a dustproof structure for a MEMS device provided in an embodiment of the present invention Figure 1 ;

[0027] Figure 2 A schematic diagram of a dustproof structure for a MEMS device provided in an embodiment of the present invention Figure 2 ;

[0028] Figure 3 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 1 ;

[0029] Figure 4 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 2 ;

[0030] Figure 5A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 3 ;

[0031] Figure 6 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 4 ;

[0032] Figure 7 A schematic diagram of a MEMS microphone packaging structure provided by an embodiment of the present invention Figure 5 . DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] refer to Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a dustproof structure for a MEMS device, which includes a mesh membrane 1 and a carrier 2, wherein the mesh 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 mesh membrane 1; the carrier 2 has a through opening 21, and the opening 21 corresponds to the position of the sound-transmitting area 12, and the carrier 2 includes at least two carrier layers, wherein a first carrier layer 22 of the carrier layers is connected to one side of the fixed connection area 11, and the other carrier layers are sequentially stacked along the thickness direction of the mesh membrane 1 on the side of the first carrier layer 22 away from the mesh diaphragm, and the thermal expansion coefficients of the carrier layers are different.

[0039] When the dustproof structure is installed in the MEMS microphone packaging structure, for example, installed on the PCB board in the MEMS microphone packaging structure, when the carrier 2 has only a single-layer structure, the carrier 2 has only a single thermal expansion coefficient, which is not only very likely to be greatly different from the thermal expansion coefficient of the fixed connection area 11 of the mesh membrane 1, but also likely to be greatly different from the thermal expansion coefficient of the PCB board. In this way, when the dustproof structure is combined with the PCB board through a thermosetting adhesive, there will be a large difference in the deformation between the carrier 2 and the mesh membrane 1, as well as between the carrier 2 and the PCB board. When the temperature drops to room temperature, the carrier 2 and the mesh membrane 1, as well as between the carrier 2 and the PCB board, will constrain each other and generate stress. The stress will prevent the mesh membrane 1 from returning to its original size, thereby causing a large warping deformation of the mesh membrane 1, which makes it impossible to ensure that the mesh membrane is in a flat state. In the dustproof structure for MEMS devices provided in an embodiment of the present invention, since the carrier 2 includes at least two carrier layers, and the thermal expansion coefficients of the carrier layers are different, that is, the carrier layers with different thermal expansion coefficients are transitionally connected in the direction from the grid membrane 1 to the PCB board, this can effectively reduce the stress after heating and cooling, prevent the grid membrane 1 from undergoing large warping deformation, and ensure that the sound-transmitting area 12 of the grid membrane 1 is basically in a flat state, which is conducive to the smooth flow of air here and will not have an adverse effect on the movement of the airflow.

[0040] In one embodiment, the thermal expansion coefficient of the grid film 1 is smaller than the thermal expansion coefficient of the first carrier layer 22 , and the thermal expansion coefficients of the carrier layers decrease in sequence along a direction away from the grid film 1 .

[0041] In this embodiment, the thermal expansion coefficient of the first carrier layer 22 is the largest, and the thermal expansion coefficient of the first carrier layer 22 is not only greater than that of the mesh film 1, but also greater than that of the remaining carrier layers. In addition, the thermal expansion coefficients of the various carrier layers gradually decrease in sequence along the direction away from the mesh film 1. This can effectively alleviate the stress between the carrier 2 and the mesh film 1 and between the carrier 2 and the PCB board after thermal expansion and temperature cooling, thereby basically ensuring that the sound-transmitting area 12 remains flat and avoids warping and deformation of the sound-transmitting area 12.

[0042] In one embodiment, the thermal expansion coefficient of the grid film 1 is greater than the thermal expansion coefficient of the first carrier layer 22 , and the thermal expansion coefficients of the carrier layers increase in sequence along a direction away from the grid film 1 .

[0043] In this embodiment, the thermal expansion coefficient of the first carrier layer 22 is the smallest, and the thermal expansion coefficient of the first carrier layer 22 is not only smaller than that of the mesh film 1, but also smaller than that of the remaining carrier layers. In addition, the thermal expansion coefficients of the carrier layers gradually increase in sequence along the direction away from the mesh film 1. This can effectively alleviate the stress between the carrier 2 and the mesh film 1 and between the carrier 2 and the PCB board after thermal expansion and temperature cooling, thereby basically ensuring that the sound-transmitting area 12 remains flat and avoids warping and deformation of the sound-transmitting area 12.

[0044] After the dustproof structure provided in the embodiment of the present invention is applied to the MEMS microphone packaging structure, since the sound-transmitting area 12 on the mesh membrane 1 is basically in a flat state, it is conducive to the smooth flow of air here and will not have an adverse effect on the movement of the airflow.

[0045] In one embodiment, the mesh membrane 1 is an isolation net made of metal as a substrate. The isolation net can, for example, be a metal screen with a mesh aperture of less than about 10 μm, so that the airflow can pass smoothly, and at the same time, it can effectively block the entry of dust, impurities and other particles from the outside. Moreover, the metal screen has the characteristics of good durability, does not need to be frequently replaced, and has a long service life. Of course, the isolation net can also use mesh cloth with other aperture sizes and other materials, for example, non-woven fabrics can be used. Non-woven fabrics have the characteristics of moisture-proof, breathable, flexible, lightweight, non-combustible, easy to decompose, non-toxic and non-irritating, low price, and recyclable. In addition, the shape of the mesh on the isolation net can be, for example, circular, square, triangular and other shapes. Those skilled in the art can flexibly adjust according to specific needs, and the present invention is not limited to this.

[0046] In one embodiment, at least one carrier layer is made of inorganic non-metallic material or organic material. Using at least one carrier layer of inorganic non-metallic material or organic material has low cost and light weight, which is conducive to installing the dustproof structure in the MEMS microphone packaging structure.

[0047] In one embodiment, the carrier 2 is configured to be pre-fixed on the grid film 1, and the opening 21 is formed by an etching process. The etching process is specifically to place the carrier 2 opposite to the photolithography equipment, to place a mask on the side of the carrier 2 close to the photolithography equipment, to place a through hole on the mask at a position opposite to the opening 21, to allow the photolithography equipment to perform photolithography on the carrier 2, to obtain the carrier 2 with the opening 21, and finally to remove the mask.

[0048] In one embodiment, the first carrier layer 22 and at least another carrier layer have different orthographic projection shapes on the grid film 1 , and the first carrier layer 22 and another carrier layer are configured to be formed respectively by two etching processes.

[0049] For example, along the direction away from the grid membrane 1, the width of the orthographic projection of the carrier layer on the grid membrane 1 becomes wider and wider, so that the stability of the dustproof structure can be enhanced after the dustproof structure is installed in the MEMS microphone packaging structure. For another example, along the direction away from the grid membrane 1, the width of the orthographic projection of the carrier layer on the grid membrane 1 becomes narrower and narrower, which can effectively reduce the weight of the dustproof structure. For another example, a step structure is formed at the connection between each carrier layer. When the dustproof structure is bonded to the MEMS microphone packaging structure by an adhesive, after the adhesive overflows, the step structure can block the adhesive and prevent the adhesive from climbing along the side wall of the carrier 2. Since the orthographic projection shapes of the first carrier layer 22 and at least another carrier layer on the grid membrane 1 are different, they need to be formed separately by two etching processes.

[0050] In one embodiment, the carrier 2 includes two carrier layers, namely a first carrier layer 22 and a second carrier layer 23, and the thermal expansion coefficient of the first carrier layer 22 is greater than the thermal expansion coefficient of the second carrier layer 23; or, the carrier 2 includes three carrier layers, namely a first carrier layer 22, a second carrier layer 23 and a third carrier layer 24, and the second carrier layer 23 is located between the first carrier layer 22 and the third carrier layer 24, and the thermal expansion coefficient of the first carrier layer 22 is greater than the thermal expansion coefficient of the second carrier layer 23, and the thermal expansion coefficient of the second carrier layer 23 is greater than the thermal expansion coefficient of the third carrier layer 24.

[0051] Providing two or three carrier layers can not only effectively alleviate the stress between the carrier 2 and the grid film 1 and between the carrier 2 and the PCB board after thermal expansion and temperature cooling, but also the manufacturing process of the carrier 2 will not be too complicated, which is conducive to cost control.

[0052] In one embodiment, the first carrier layer 22 has a different thickness from at least another carrier layer, for example, the carrier layer of another layer is thinner than the first carrier layer 22, which is beneficial to reduce the weight of the entire dustproof structure.

[0053] An embodiment of the present invention also provides a MEMS microphone packaging structure, which includes a shell 3 with a accommodating cavity, the shell 3 is provided with a sound hole 4, and the sound hole 4 connects the inside and outside of the shell 3; it also includes a microphone device and the dustproof structure as described above, the microphone device is fixedly arranged in the shell 3; the carrier layer of the carrier 2 away from the grid membrane 1 is fixedly connected to the shell 3 by a high-temperature bonding and curing process; the grid membrane 1 closes the sound hole 4; and / or the grid membrane 1 is spaced between the sound hole and the microphone device.

[0054] 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.

[0055] refer to Figure 3-Figure 7 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.

[0056] In an optional example of the present invention, Figure 3 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 .

[0057] In an optional example of the present invention, Figure 4As 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.

[0058] Of course, the dustproof structure of the present invention may also have other configuration modes:

[0059] For example, Figure 5 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. Figure 6 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, Figure 7 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.

[0060] 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, wherein the carrier has a through opening, the opening corresponds to the position of the sound-permeable area, the carrier comprises at least two carrier layers, a first carrier layer of the carrier layers is connected to one side of the fixed connection area, and the other carrier layers are sequentially stacked and distributed on a side of the first carrier layer away from the grid membrane along the thickness direction of the grid membrane, and the thermal expansion coefficients of the carrier layers are different; When the thermal expansion coefficient of the grid membrane is smaller than the thermal expansion coefficient of the first carrier layer, the thermal expansion coefficients of each layer of the carrier layer decrease successively along the direction away from the grid membrane; when the thermal expansion coefficient of the grid membrane is greater than the thermal expansion coefficient of the first carrier layer, the thermal expansion coefficients of each layer of the carrier layer increase successively along the direction away from the grid membrane.

2. The dustproof structure according to claim 1, characterized in that: The mesh membrane is an isolation net made of metal as a base material.

3. The dustproof structure according to claim 1, characterized in that: At least one carrier layer is made of inorganic non-metallic material or organic material.

4. The dustproof structure according to claim 1, characterized in that: The carrier is configured to be pre-fixed on the grid film, and the opening is formed by an etching process.

5. The dustproof structure according to claim 4, characterized in that: The first carrier layer and at least another carrier layer have different orthographic projection shapes on the grid film, and the first carrier layer and another carrier layer are configured to be formed respectively by two etching processes.

6. The dustproof structure according to claim 1, characterized in that: The carrier comprises two carrier layers, namely a first carrier layer and a second carrier layer, wherein the thermal expansion coefficient of the first carrier layer is greater than the thermal expansion coefficient of the second carrier layer; Alternatively, the carrier includes three carrier layers, namely a first carrier layer, a second carrier layer and a third carrier layer, the second carrier layer is located between the first carrier layer and the third carrier layer, the thermal expansion coefficient of the first carrier layer is greater than the thermal expansion coefficient of the second carrier layer, and the thermal expansion coefficient of the second carrier layer is greater than the thermal expansion coefficient of the third carrier layer.

7. The dustproof structure according to claim 1, characterized in that: The first carrier layer has a different thickness than at least one other carrier layer.

8. 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 any one of claims 1 to 7, wherein the carrier layer of the carrier away from the grid film is fixedly connected 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.

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