MEMS sensor

Abstract

The utility model provides an MEMS sensor comprising a packaging structure composed of a PCB and a housing, the PCB in the packaging structure is provided with an ASIC chip and an MEMS chip, the PCB corresponding to the MEMS chip is provided with a sound hole communicated with the outside, the MEMS chip comprises a substrate, a back electrode arranged on the substrate, and a vibrating diaphragm; wherein the back electrode is located above the substrate and corresponds to the sound hole, the vibrating diaphragm is arranged on one side between the substrate and the back electrode, and a sound pressure channel formed between the sound hole and the vibrating diaphragm forms an L shape. According to the utility model, the problem that external foreign matters are easy to enter the vibrating diaphragm of the existing MEMS sensor to cause bad products can be solved.

Description

Technical Field

[0001] The utility model relates to the technical field of sensors, and more specifically, to a MEMS sensor. Background Art

[0002] Traditional MEMS sensors are packaging structures formed by assembling a PCB and a shell, and an ASIC chip and a MEMS chip are arranged on the PCB inside the packaging structure. In the current MEMS chip manufacturing process, the diaphragm of the MEMS chip is located in the middle position, and foreign matter can easily enter the diaphragm inside the MEMS chip, resulting in defective products. Among them, the sources of foreign matter are mainly foreign matter in the process environment, MEMS dicing and expansion. Utility Model Content

[0003] In view of the above problems, the purpose of the present invention is to provide a MEMS sensor to solve the problem that foreign matter can easily enter the diaphragm of the existing MEMS sensor and cause product defects.

[0004] The utility model provides a MEMS sensor, comprising a packaging structure composed of a PCB board and a shell, wherein an ASIC chip and a MEMS chip are arranged on the PCB board inside the packaging structure, and a sound hole connected to the outside is arranged on the PCB board corresponding to the MEMS chip, and the MEMS chip comprises a substrate, a back electrode arranged on the substrate, and a diaphragm; wherein,

[0005] The back pole is located above the substrate and corresponds to the sound hole. The diaphragm is arranged on one side between the substrate and the back pole. The sound pressure channel formed from the sound hole to the diaphragm is in an L shape.

[0006] In addition, a preferred structure is that the sound hole is used to transmit external sound pressure to the diaphragm of the MEMS chip inside the packaging structure.

[0007] In addition, a preferred structure is that chip pads are respectively provided at the bottom of the ASIC chip and the MEMS chip, and an internal pad is provided on the PCB board inside the packaging structure; wherein,

[0008] The ASIC chip, the MEMS chip and the PCB board are connected via corresponding chip pads and the internal pads.

[0009] In addition, a preferred structure is that the chip pad and the internal pad are welded or bonded by soldering or conductive liquid glue.

[0010] In addition, a preferred structure is that a line connecting the ASIC chip and the MEMS chip is pre-buried inside the PCB board.

[0011] In addition, a preferred structure is that a light shielding cover is provided on the ASIC chip, wherein:

[0012] The light shield is used to prevent the ASIC chip from being photosensitized.

[0013] In addition, a preferred structure is that the light shielding cover is a metal shielding cover.

[0014] In addition, a preferred structure is that the housing is fixed to the PCB board by an adhesive, wherein:

[0015] The adhesive is silver paste or solder paste or silica gel or epoxy glue.

[0016] In addition, a preferred structure is that an external pad is provided on a PCB board outside the packaging structure, and the PCB board is electrically connected to an external device via the external pad.

[0017] It can be seen from the above technical solution that the MEMS sensor provided by the utility model, by setting the diaphragm on one side of the substrate, makes the sound pressure channel formed from the sound hole to the diaphragm form an L shape, reduces the entry of foreign matter into the diaphragm in the MEMS chip, thereby improving the product yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other purposes and results of the present invention will become more clear and easy to understand. In the accompanying drawings:

[0019] Figure 1 Schematic diagram of the structure of a MEMS sensor according to an embodiment of the utility model.

[0020] The reference numerals include: 1. housing, 2. PCB board, 3. MEMS chip, 4. ASIC chip, 5. light shielding cover, 6. first pad, 7. second pad, 8. sound hole, 31. diaphragm, 32. substrate, 33. back pole.

[0021] The same reference numerals throughout the drawings indicate similar or corresponding features or functions. DETAILED DESCRIPTION

[0022] In the following description, for the purpose of illustration, in order to provide a comprehensive understanding of one or more embodiments, many specific details are set forth. However, it is apparent that these embodiments may also be implemented without these specific details. In other examples, for ease of describing one or more embodiments, known structures and devices are shown in the form of block diagrams.

[0023] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0024] In view of the aforementioned problem that foreign matter can easily enter the diaphragm of the existing MEMS sensor and cause product defects, the utility model provides a MEMS sensor.

[0025] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] In order to illustrate the structure of the MEMS sensor provided by the utility model, Figure 1 The figure shows a MEMS sensor structure according to an embodiment of the present utility model.

[0027] like Figure 1 As shown, the MEMS sensor provided by the utility model includes a packaging structure composed of a PCB board 2 and a housing 1, wherein an ASIC chip 4 and a MEMS chip 3 are arranged on the PCB board 2 inside the packaging structure, and a sound hole 8 connected to the outside is arranged on the PCB board 2 corresponding to the MEMS chip 3, and the MEMS chip 3 includes a substrate 32, a back electrode 33 arranged on the substrate 32, and a diaphragm 31; wherein the back electrode 33 is located above the substrate 32 and corresponds to the sound hole 8, and the diaphragm 31 is arranged on one side between the substrate 32 and the back electrode 33, and the sound pressure channel formed between the sound hole 8 and the diaphragm 31 forms an L shape. wherein the sound hole 8 is used to transmit the external sound pressure to the diaphragm 31 of the MEMS chip 3 inside the packaging structure.

[0028] Compared with the diaphragm setting position of the conventional MEMS sensor, the MEMS sensor of the present invention sets the diaphragm 31 on one side of the substrate 32, thereby reducing the possibility of foreign matter entering the diaphragm in the MEMS chip and improving the product yield.

[0029] In a traditional MEMS sensor, the ASIC chip 4, the MEMS chip 3 and the PCB board are electrically connected through gold wires; however, the efficiency of this process is very low. In order to solve the problem of low efficiency of this process, in a specific embodiment of the utility model, chip pads are respectively provided at the bottom of the ASIC chip 4 and the MEMS chip 3, and an internal pad is provided on the PCB board 2 inside the packaging structure; wherein the ASIC chip 4, the MEMS chip 3 and the PCB board 2 are connected to the internal pads through corresponding chip pads.

[0030] That is to say, in this embodiment, the chip pad disposed at the bottom of the ASIC chip 4 is the first pad 6, and the chip pad disposed at the bottom of the MEMS chip 3 is the second pad 7. The ASIC chip 4 is connected to the bottom pad of the PCB board 2 via the first pad 6, and the MEMS chip is connected to the bottom pad of the PCB board 2 via the second pad 7, thereby realizing electrical connection between the ASIC chip 4, the MEMS chip 3 and the PCB board. In addition, the chip pads (the first pad 6 and the second pad 7) and the internal pads are welded or bonded by soldering or conductive liquid glue. In specific applications, a suitable electrical connection method can be selected according to actual conditions, and is not limited to a specific method.

[0031] In addition, in the embodiment of the present utility model, in order to realize signal transmission between the ASIC chip 4 , the MEMS chip 3 and the PCB board, a line connecting the ASIC chip 4 and the MEMS chip 3 is pre-buried inside the PCB board 2 .

[0032] In addition, in an embodiment of the present invention, an external pad is provided on the PCB board 2 outside the packaging structure, and the PCB board 2 is electrically connected to an external device via the external pad, thereby realizing signal connection between an external circuit and a MEMS sensor.

[0033] In a specific embodiment of the utility model, a light shielding cover 5 is provided on the ASIC chip 4, wherein the light shielding cover 5 is used to prevent the ASIC chip 4 from being photosensitized. Since the ASIC chip 4 has aluminum pads and various circuits, a sensitization reaction is easily caused under the irradiation of ultraviolet rays, thereby affecting the performance of the ASIC chip 4. In order to prevent the photosensitization of the chip, a light shielding cover 5 with a contoured structure is provided on the ASIC chip 4. The light shielding cover 5 is a metal shielding cover, and can be made of copper or stainless steel. The specific material of the light shielding cover is selected and set according to the actual situation in the specific application.

[0034] In the utility model, the existing COB (Chip-On-Board) is replaced by a light shielding cover, the bare chip is adhered to the PCBBAN with conductive or non-conductive glue, and then wire bonding is performed to achieve its electrical connection, and the chip and bonding wires are encapsulated with glue.

[0035] In addition, in an embodiment of the utility model, the housing 1 is fixed to the PCB board 2 by an adhesive, wherein the adhesive is silver paste or solder paste or silicone or epoxy glue. In specific applications, the specific adhesive is selected according to actual conditions and is not limited to a certain type.

[0036] It can be seen from the above embodiments that the MEMS sensor provided by the utility model, by setting the diaphragm on one side of the substrate, makes the sound pressure channel formed between the sound hole and the diaphragm form an L shape, reduces the entry of foreign matter into the diaphragm in the MEMS chip, and thus improves the product yield. In addition, by setting chip pads at the bottom of the ASIC chip 4 and the MEMS chip 3, respectively, and connecting them with the internal pads set on the PCB board, the signal transmission between the ASIC chip 4, the MEMS chip 3 and the PCB board 2 is realized, thereby solving the bottleneck of the electrical connection process of each component; in addition, the existing COB is further replaced by a light shielding cover, thereby reducing the process turnover process, saving process turnover time and raw material costs.

[0037] The MEMS sensor proposed according to the present invention is described above by way of example with reference to the accompanying drawings. However, those skilled in the art should understand that various improvements can be made to the MEMS sensor proposed by the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the attached claims.

Claims

1. A MEMS sensor, comprising a packaging structure consisting of a PCB board and a housing, wherein: An ASIC chip and a MEMS chip are arranged on the PCB board inside the packaging structure, and a sound hole connected to the outside is arranged on the PCB board corresponding to the MEMS chip, and the MEMS chip includes a substrate, a back electrode arranged on the substrate, and a diaphragm; characterized in that: The back pole is located above the substrate and corresponds to the sound hole. The diaphragm is arranged on one side between the substrate and the back pole. The sound pressure channel formed from the sound hole to the diaphragm is in an L shape.

2. The MEMS sensor according to claim 1, characterized in that: The sound hole is used to transfer external sound pressure to the diaphragm of the MEMS chip inside the packaging structure.

3. The MEMS sensor according to claim 1, wherein: Chip pads are respectively arranged at the bottom of the ASIC chip and the MEMS chip, and internal pads are arranged on the PCB board inside the packaging structure; wherein, The ASIC chip, the MEMS chip and the PCB board are connected via corresponding chip pads and the internal pads.

4. The MEMS sensor according to claim 3, characterized in that: The chip pad is welded or bonded to the internal pad by soldering or conductive liquid glue.

5. The MEMS sensor according to claim 3, characterized in that: A line connecting the ASIC chip and the MEMS chip is pre-buried inside the PCB board.

6. The MEMS sensor according to claim 1, wherein: The ASIC chip is covered with a light shielding cover, wherein: The light shield is used to prevent the ASIC chip from being photosensitized.

7. The MEMS sensor according to claim 6, characterized in that: The light shielding cover is a metal shielding cover.

8. The MEMS sensor according to claim 1, wherein: The housing is fixed to the PCB board by an adhesive, wherein: The adhesive is silver paste or solder paste or silica gel or epoxy glue.

9. The MEMS sensor according to claim 1, wherein: An external solder pad is arranged on the PCB board outside the packaging structure, and the PCB board is electrically connected to an external device through the external solder pad.

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