Vibration sensor packaging structure

Abstract

A vibration sensor packaging structure is disclosed, comprising: a substrate; a packaging shell, fixed to the first surface of the substrate, and forming a first cavity with the substrate; a MEMS chip, fixed to the first surface of the substrate and located in the first cavity, and the MEMS has a second cavity; wherein the substrate is provided with a first air hole and a second air hole penetrating the substrate; one side of the MEMS chip is connected to the outside world via the first cavity and the second air hole, and the other side of the MEMS chip is connected to the outside world via the second cavity and the first air hole. The vibration sensor packaging structure of the present application forms the first air hole and the second air hole penetrating the substrate in the substrate, so that the upper and lower sides of the diaphragm of the MEMS chip can receive sound signals in the air, thereby reducing the noise interference of the sound signal in the air to the vibration sensor and improving the yield and reliability of the device.

Description

Technical Field

[0001] The present invention relates to the technical field of MEMS devices, and in particular to a vibration sensor packaging structure. Background Art

[0002] Vibration is widely present in nature, industry and human life, and different vibrations transmit various signals. To obtain the information carried in vibration, we need to use various vibration sensors, which are widely used in many fields such as energy, chemical industry, medicine, automobile, metallurgy, machinery manufacturing, military industry, scientific research and teaching. For example, the sound signal transmitted by air vibration is read through a microphone; the accelerometer is used to measure the acceleration of the vibrating object; the ultrasonic detector detects and analyzes the vibration signal of mechanical equipment to determine the degree of deterioration of the machine itself and predict its life; the geological disaster early warning device detects the geological vibration caused by seismic waves to warn of earthquakes and other disasters.

[0003] Common sensors in the market include microphone sensors, pressure sensors, and acceleration sensors. Microphone sensors have been extended to bone conduction microphones that convert sound signals through vibration. Traditional bone conduction microphones transmit compressed air to the MEMS diaphragm through the vibration of the mass block. However, the existing vibration microphones are easily affected by the sound signals transmitted in the air, resulting in large noise in the received signals, thereby reducing the yield and reliability of the vibration sensor. Summary of the invention

[0004] In view of the above problems, the object of the present invention is to provide a vibration sensor packaging structure, which reduces the influence of the sound signal on the vibration signal in the signal received by the sensor by changing the air flow path in the vibration sensor, thereby improving the yield and reliability of the vibration sensor.

[0005] According to one aspect of the present invention, there is provided a vibration sensor packaging structure, characterized in that it comprises: a substrate; a packaging shell, fixed to the first surface of the substrate and forming a first cavity between the packaging shell and the substrate; a MEMS chip, fixed to the first surface of the substrate and located in the first cavity, and the MEMS has a second cavity; wherein the substrate is provided with a first air hole and a second air hole penetrating the substrate; one side of the MEMS chip is connected to the outside world via the first cavity and the second air hole, and the other side of the MEMS chip is connected to the outside world via the second cavity and the first air hole.

[0006] Optionally, the cross-sectional shape of the second air hole along the first surface of the substrate is any one of square, circular and polygonal.

[0007] Optionally, the cross-sectional shape of the second air hole along the direction perpendicular to the first surface of the substrate is any one of a trapezoid, a rectangle, an arc, and a polygon.

[0008] Optionally, the second air holes include one or more second air holes, which are located in the substrate on one side or multiple sides of the MEMS chip.

[0009] Optionally, the MEMS chip comprises a supporting structure, and a bottom of the supporting structure is fixed on the surface of the substrate by colloid.

[0010] Optionally, the MEMS chip further includes a diaphragm and a back plate, and the positions of the diaphragm and the back plate are interchangeable.

[0011] Optionally, it further includes: an ASIC chip, and the MEMS chip is electrically connected to the ASIC chip.

[0012] Optionally, it further includes: a sealing ring located on the first surface of the substrate, and the packaging shell is fixed to the substrate via the sealing ring.

[0013] Optionally, the second surface of the substrate includes a first solder pad and a second solder pad.

[0014] Optionally, the first pad surrounds the first air hole and the second air hole.

[0015] The vibration sensor packaging structure provided by the present invention forms a first air hole in the substrate under the second cavity of the MEMS chip, and forms a second air hole in the substrate under the first cavity, so that the time difference between the sound signal reaching the surface of the MEMS chip diaphragm along the second air hole and the time difference between the sound signal reaching the surface of the MEMS chip diaphragm along the first air hole can be basically ignored, so the sounds on the upper and lower surfaces of the MEMS chip diaphragm are offset, and the MEMS chip only receives the vibration signal, so the noise interference of the sound signal on the vibration sensor can be reduced to the greatest extent. Thereby improving the yield and reliability of the vibration sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0017] Figure 1 A structural diagram showing a vibration sensor packaging structure according to an embodiment of the present invention;

[0018] Figure 2a and Figure 2b A schematic diagram of a first surface of a substrate in a vibration sensor packaging structure according to an embodiment of the present invention is shown;

[0019] Figure 3 A schematic diagram of the second surface of the substrate in the vibration sensor packaging structure according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0020] The present invention will be described in more detail below with reference to the accompanying drawings. In each of the accompanying drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the accompanying drawings are not drawn to scale. In addition, some well-known parts may not be shown. For the sake of simplicity, the semiconductor structure obtained after several steps can be described in one figure.

[0021] It should be understood that when describing the structure of a device, when a layer or a region is referred to as being "on" or "over" another layer or another region, it may mean that it is directly on the other layer or another region, or that other layers or regions are included between it and the other layer or another region. Furthermore, if the device is turned over, the layer or a region will be "below" or "beneath" another layer or another region.

[0022] If it is intended to describe a situation where it is directly on another layer or another area, this article will use the expression “directly on…” or “on… and adjacent to…”.

[0023] The specific implementation of the present invention is further described in detail below in conjunction with the drawings and examples.

[0024] Figure 1 A structural diagram showing a vibration sensor packaging structure according to an embodiment of the present invention; Figure 2a and Figure 2b A schematic diagram of a first surface of a substrate in a vibration sensor packaging structure according to an embodiment of the present invention is shown; Figure 3 A schematic diagram of the second surface of the substrate in the vibration sensor packaging structure according to an embodiment of the present invention is shown.

[0025] refer to Figure 1 The vibration sensor packaging structure 100 of the embodiment of the present invention includes: a substrate 3, in which a first air hole 5 penetrating the substrate 3 and a second air hole 4 penetrating the substrate 3 are formed; a packaging shell 1, which is fixed to the first surface of the substrate 3 and forms a first cavity 2 with the substrate 3, and the first air hole 5 and the second air hole 4 are both located in the first cavity 2; a MEMS chip 10, which is arranged in the first cavity 2, and the MEMS chip 10 includes a diaphragm 11, a back plate 12 and a supporting structure, the top of the supporting structure supports the diaphragm 11 and the back plate 12, and the bottom is fixed to the first surface of the substrate 3, and a second cavity 6 is formed between the diaphragm 11 and the back plate 12 at the top of the supporting structure and the substrate 3 at the bottom, and the second cavity 6 is located above the first air hole 5, so that the second cavity 6 is connected to the outside through the first air hole 5, and the first cavity 2 is also connected to the outside through the second air hole 4.

[0026] The vibration sensor packaging structure 100 also includes an ASIC chip 13, which is disposed on the first surface of the substrate 3 in the first cavity 2. The ASIC chip 13 is a dedicated integrated circuit chip and is connected to the MEMS chip 10 through a wire 14. In this specific embodiment, the ASIC chip 13 is fixed to the first surface of the substrate 3. In other specific embodiments, the ASIC chip 13 can also be embedded or integrated inside the substrate 3. The ASIC chip 13 is used to obtain the sensing signal output by the MEMS chip 10 and process it.

[0027] The material of the substrate 3 can be RF-4, BT or ceramic substrate and other commonly used substrate materials. A sealing ring 15 is formed on the first surface of the substrate 3 and surrounds the edge of the first surface of the substrate 3. Figure 2a and Figure 2b The package shell 1 is fixedly connected to the first surface of the substrate 3 through the sealing ring 15 to form a first cavity 2. The second surface of the substrate 3 is formed with a first pad 7 and / or a second pad 9 for providing an electrical connection point, such as Figure 3 The substrate 3 may be a single-layer or multi-layer circuit board, and the first surface of the substrate 3 may also be formed with a circuit structure or an electrical contact portion, such as a solder pad, etc. An electrical connection structure may also be formed inside the substrate 3 to connect the electrical contact portions on the first surface and the second surface of the substrate 3.

[0028] The packaging shell 1 serves as a packaging shell of the vibration sensor packaging structure, which is used to protect the internal electronic components and form a first cavity 2 between the substrate 3. The packaging shell 1 can be made of metal, which is resistant to high temperatures and has a simple production process, and can be mass-produced. In addition, the metal shell packaging shell 1 also has the characteristics of corrosion resistance, electromagnetic shielding, and high mechanical properties, which provide a high degree of protection for the product. In other embodiments, the packaging shell 1 can also be made of other hard materials such as plastic, which is not limited here. The edge of the packaging shell 1 is fixed to the sealing ring 15 on the first surface of the substrate 3 by welding or gluing, so that a first cavity 2 is formed between the packaging shell 1 and the substrate 3.

[0029] The MEMS chip 10 is used as a sensing element for sound signals, and the positions of the diaphragm 11 and the back plate 12 can be interchanged. The bottom of the MEMS chip 10 is fixedly connected to the first surface of the substrate 3 through the colloid 8 .

[0030] refer to Figure 1The first surface of the substrate 3 has a first pore 5 and a second pore 4, wherein the first pore 5 and the second pore 4 both penetrate the substrate 3, and the second pore 4 is located near the first pore 5. Specifically, the first pore 5 is located in the substrate 3 in the second cavity 6 of the MEMS chip 10, and the second pore 4 is located in the substrate 3 outside the MEMS chip 10, so that the second cavity 6 is connected to the outside through the first pore 5, and the first cavity 2 is connected to the outside through the second pore 4. Figure 2a and Figure 2b The schematic top view of the first surface of the substrate 3 is shown, wherein: Figure 2a The MEMS chip 10 and the ASIC chip 13 are also included. In some specific embodiments, the cross-section of the second pore 4 along the direction parallel to the first surface of the substrate 3 can be square, circular, polygonal, etc. In some specific embodiments, the cross-sectional shape of the second pore 4 along the direction perpendicular to the first surface of the substrate 3 is a trapezoidal, rectangular, arc-shaped or polygonal shape. The second pore 4 only needs to penetrate the substrate 3 and connect the first cavity 2 with the external environment. Preferably, the second pore 4 is located near the MEMS chip, and those skilled in the art can reasonably set the shape of the second pore 4. The size of the second pore 4 is adjusted according to the size of the second cavity 6 and / or the first pore 5 of the MEMS chip 10.

[0031] In other embodiments, the second air holes 4 include one or more, which are distributed around the MEMS chip 10 in the substrate 3 on one or more sides outside the MEMS chip 10. The first air holes 5 and the second air holes 4 are connected to the same external environment, so that the air pressure reaching the upper and lower sides of the diaphragm 11 of the MEMS chip 10 is the same, which can minimize interference.

[0032] The MEMS chip 10 includes a second cavity 6 as a back cavity. The pressure sensing layer of the MEMS chip 10 includes a back plate 12 and a diaphragm 11, which are arranged opposite to each other to form a sensing capacitor. When the pressure in the second cavity 6 changes, the pressure sensing layer is deformed, so that the capacitance value changes and a sensing signal is output.

[0033] The support structure of the MEMS chip 10 is fixed to the first surface of the substrate 3 through the colloid 8. When fixing the MEMS chip 10, a certain force is applied to the MEMS chip 10 through the device, so that the bottom of the support structure has a larger contact area with the colloid 8, thereby improving the fixing effect. The colloid is squeezed and overflows to both sides of the bottom of the support structure, overflows to both sides of the support structure, and climbs up a certain height along the outer wall of the MEMS chip 10. Subsequently, the colloid is solidified at a certain temperature and for a certain time, thereby realizing a close connection between the MEMS chip 10 and the substrate 3.

[0034] When the vibration sensor is used, the caller makes a sound, and the sound reaches the vibration sensor through two channels: air and vibration. Among them, the sound signal in the air reaches the second cavity 6 of the MEMS chip 10 through the first air hole 5, so that the capacitance value between the diaphragm 11 and the back plate 12 changes, thereby obtaining a sound signal. The sound signal transmitted by vibration reaches the diaphragm 11 and the back plate 12 of the MEMS chip 10 along the structure of the vibration sensor, so that the capacitance value between the diaphragm 11 and the back plate 12 changes, thereby obtaining a signal. However, in the vibration sensor, the change in capacitance between the diaphragm 11 and the back plate 12 caused by the sound signal in the air causes noise interference in the sound signal obtained by vibration. In this embodiment, a part of the sound signal in the air reaches the second cavity 6 of the MEMS chip 10 along the first air hole 5, pressing the diaphragm 11 to vibrate, and a part reaches the MEMS chip 10 along the second air hole 4 and the first cavity 2, pressing the diaphragm 11 to vibrate from the opposite direction. Due to the same air pressure in two opposite directions acting on the same diaphragm 11, the sound signal in the air is offset. When the sound of the caller is transmitted through the oral bones to the vibration sensor of the earphone close to the bones, the vibration is transmitted to the substrate 3 of the vibration sensor through the earphone shell and then to the MEMS chip 10, causing the diaphragm 11 on the surface of the MEMS chip 10 to vibrate, forming a parallel plate capacitor with the back plate 12 of the MEMS chip 10, and the ASIC chip 13 receives the signal of capacitance change for processing.

[0035] When making a call in a noisy environment, the vibration sensor of the present application can automatically shield the sound signal and only transmit the sound signal transmitted by the bone vibration of the caller when speaking, thereby achieving the highest quality noise reduction.

[0036] In addition, the vibration sensor is not only used for call headsets, but can also be applied to other electronic products that work on the same principle.

[0037] The vibration sensor packaging structure provided by the present invention forms a first air hole and a second air hole penetrating the substrate in the substrate, wherein the first air hole is connected to the second cavity of the MEMS chip, and the second air hole is connected to the first cavity, so that the surface of the MEMS chip facing the first cavity can also receive air and pressure, thereby reducing the noise interference brought to the vibration sensor by the sound signal when only the second cavity of the MEMS chip receives air and pressure, thereby improving the yield and reliability of the vibration sensor.

[0038] The vibration sensor packaging structure provided by the present invention forms a first air hole in the substrate under the second cavity of the MEMS chip, and forms a second air hole in the area of ​​the substrate close to the MEMS chip, so that when the sound signal reaches the surface of the MEMS chip facing the first cavity along the second air hole, the time difference between the time taken for the sound signal to reach the surface of the second cavity of the MEMS chip along the first air hole and the time taken for the sound signal to reach the surface of the second cavity of the MEMS chip along the first air hole is small, and the sound signals are the same, thereby being able to minimize the noise interference of the sound signal on the vibration sensor.

[0039] According to the embodiments of the present invention as described above, these embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and changes can be made based on the above description. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can make good use of the present invention and the modified use based on the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A vibration sensor packaging structure, characterized in that: include: substrate; A packaging shell, fixed to the first surface of the substrate, and forming a first cavity between the packaging shell and the substrate; A MEMS chip is fixed on the first surface of the substrate and is located in the first cavity, and a second cavity is formed between the MEMS chip and the substrate; Wherein, the substrate is provided with a first air hole and a second air hole penetrating through the substrate; The first cavity is connected to the outside through the second air hole, and the second cavity is connected to the outside through the first air hole. The sound signal reaching the MEMS chip diaphragm through the first air hole and the sound signal reaching the MEMS chip diaphragm through the second air hole cancel each other out.

2. The vibration sensor packaging structure according to claim 1, characterized in that: The cross-sectional shape of the first air hole or the second air hole along the first surface of the substrate is any one of square, circular and polygonal.

3. The vibration sensor packaging structure according to claim 1, characterized in that: The cross-sectional shape of the first air hole or the second air hole along the direction perpendicular to the first surface of the substrate is any one of a trapezoid, a rectangle, an arc, and a polygon.

4. The vibration sensor packaging structure according to claim 1, characterized in that: The second air holes include one or more second air holes, which are located in the substrate on one side or multiple sides of the MEMS chip.

5. The vibration sensor packaging structure according to claim 1, characterized in that: The MEMS chip comprises a supporting structure, the bottom of which is fixed on the surface of the substrate through colloid.

6. The vibration sensor packaging structure according to claim 5, characterized in that: The MEMS chip also includes a diaphragm and a back plate, and the positions of the diaphragm and the back plate are interchangeable.

7. The vibration sensor packaging structure according to claim 1, characterized in that: Also includes: ASIC chip, the MEMS chip is electrically connected to the ASIC chip.

8. The vibration sensor packaging structure according to claim 1, characterized in that: Also includes: A sealing ring is located on the first surface of the substrate, and the packaging shell is fixed to the substrate via the sealing ring.

9. The vibration sensor packaging structure according to claim 1, characterized in that: The second surface of the substrate includes a first pad and a second pad.

10. The vibration sensor packaging structure according to claim 9, characterized in that: The first pad surrounds the first air hole and the second air hole.

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