MEMS sensor with good mechanical property

Abstract

The invention discloses an MEMS sensor with good mechanical properties, an MEMS chip and a PCB are stacked and fixed, a built-in cavity is formed in a rigid shell, and the relative position of the PCB and the MEMS chip is cured by pouring glue into the cavity, so that the rigid strength in the horizontal direction is realized; meanwhile, a pre-tightening structure arranged on the rigid cover plate is pressed and limited at the upper part of the MEMS chip, and then the rigid cover plate and the shell are fastened and connected, so that the sensor and the shell form a three-dimensional rigid structure, and the overall rigidity is improved. According to the scheme, the transmission path between the PCB and the external mechanical environment is shortened to the maximum extent, external force can be directly transmitted to the position closest to the MEMS chip, the product has good mechanical transmission performance, signal attenuation can be effectively avoided, and corresponding physical quantities can be sensed and measured more accurately.

Description

Technical Field

[0001] The present invention relates to a sensor, in particular to a MEMS sensor with good mechanical properties, belonging to the technical field of micro-electromechanical systems (MEMS). Background Art

[0002] MEMS sensors are generally used in mobile fields such as household appliances, drones, and communications, and are mainly used in automobiles, communications, and consumer products. They are widely used in these fields due to their good consistency, good stability, small size, low price, and easy integration. Compared with other sensors, such as piezoelectric ceramic sensors, MEMS sensors are smaller in size, lighter in weight, and more adaptable. Their accuracy is measured in nanometers, and their stability and consistency far exceed those of manually assembled piezoelectric ceramic sensors. Especially in applications that require long-term monitoring and permanent installation, their advantages are more significant.

[0003] Since MEMS sensors are in the form of chips, existing MEMS sensors need to be assembled and used in conjunction with PCB circuit boards. On the one hand, the rigidity of PCB circuit boards is relatively weak, which leads to a large attenuation of the external mechanical environment sensed by the MEMS chip after being transmitted through the PCB circuit board, especially in the high-frequency band. On the other hand, the installation method of the two complicates the path of force transmission, greatly enhances the transmission damping, and attenuates the high-frequency signal. A large number of uncontrollable factors cause the MEMS chip (i.e., sensitive element) to obtain a distorted signal, which will produce large errors in energy, frequency band and direction. Therefore, the structure of directly installing the MEMS chip on the PCB circuit board and then fixing it with bolts, snaps or other methods on the PCB board cannot meet applications with higher requirements (mainly referring to: frequency and accuracy). Although this attenuation is acceptable for automobiles, communications and consumer products, for higher-demand scientific research, equipment and industrial field monitoring fields, this signal attenuation will lead to information loss and change, and it is impossible to achieve the required accuracy and it is difficult to capture tiny mechanical signals. Therefore, it is necessary to improve the structure of the MEMS sensor to improve its performance. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a MEMS sensor with good mechanical properties to solve the problems of large force transmission attenuation and low operating frequency in traditional MEMS sensors, so that it can be more widely used in various fields.

[0005] The technical solution of the present invention is: a MEMS sensor with good mechanical properties, including a rigid cover plate (which can be made of stainless steel or titanium alloy material), a rigid shell (which can be made of stainless steel or titanium alloy material), a PCB circuit board and a MEMS chip, wherein the rigid cover plate and the rigid shell are tightly connected, and the characteristics are: the inner bottom of the rigid shell and the PCB circuit board are integrated by positioning pins, and a MEMS chip is fixed on the upper part of the PCB circuit board; a built-in cavity is formed inside the rigid shell, and the PCB circuit board and the MEMS chip stacking assembly are cured by glue injection into the built-in cavity; a pre-tightening structure is provided on the rigid cover plate, and the lower end of the pre-tightening structure is pressed against the upper part of the MEMS chip.

[0006] Furthermore, in the above-mentioned MEMS sensor with good mechanical properties, the rigid cover plate and the rigid shell are connected by means including but not limited to threaded fixing, welding fixing or adhesive fixing.

[0007] Furthermore, in the above-mentioned MEMS sensor with good mechanical properties, the MEMS chip is electrically connected to the PCB circuit board.

[0008] Furthermore, in the above-mentioned MEMS sensor with good mechanical properties, chip pins are arranged on four sides of the lower part of the MEMS chip, and each of the chip pins is fixedly connected to the PCB circuit board through a solder point.

[0009] Furthermore, in the above-mentioned MEMS sensor with good mechanical properties, a sticky patch or a mounting seat is provided at the lower part of the rigid shell, and the sticky patch is a double-sided tape or adhesive.

[0010] Furthermore, in the above-mentioned MEMS sensor with good mechanical properties, a plurality of threaded holes are provided on the mounting seat.

[0011] Furthermore, the above-mentioned MEMS sensor with good mechanical properties, wherein: the pre-tightening structure is a first pre-tightening structure or a second pre-tightening structure, the first pre-tightening structure is integrated with the rigid cover plate, and the first pre-tightening structure includes a cubic pre-tightening structure or a flat pre-tightening structure; the second pre-tightening structure is detachably mounted on the rigid cover plate, and the second pre-tightening structure includes a three-axis pre-tightening structure or a uniaxial pre-tightening structure.

[0012] Furthermore, in the above-mentioned MEMS sensor with good mechanical properties, a positioning countersunk hole is provided at the bottom of the rigid shell, a positioning through hole is provided on the PCB circuit board, and the positioning countersunk hole and the PCB circuit board are aligned and interlaced through the positioning pin.

[0013] Compared with the prior art, after adopting the technical solution of the present invention, the transmission path between the PCB circuit board and the external mechanical environment is shortened to the greatest extent, so that the external force can be directly transmitted to the nearest position of the MEMS chip, effectively avoiding signal attenuation, and more accurately sensing and measuring the corresponding physical quantities; moreover, the rigid cover plate with a pre-tightening structure and the rigid shell fix the MEMS chip up and down, so that the sensor and the shell form a three-dimensional rigid structure, thereby improving the overall rigidity; the remaining built-in cavities in the rigid shell are cured by glue filling to achieve rigid strength in the horizontal direction, so as to reduce the loss of external force transmitted to the MEMS chip in the horizontal direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic structural diagram of the assembly of a three-axis acceleration MEMS sensor (with a cubic pre-tightening structure disposed inside) according to Example 1 of the present invention;

[0015] Figure 2 This is a schematic diagram of the structure of the assembly of a three-axis acceleration MEMS sensor (with a three-axis pre-tightening structure arranged inside and a sticky patch arranged at the bottom) according to Embodiment 2 of the present invention;

[0016] Figure 3 It is a schematic structural diagram of the assembly of a three-axis acceleration MEMS sensor (a three-axis pre-tightening structure is arranged inside, a mounting seat is arranged at the bottom, and a first preset socket rod is arranged inside the rigid shell) according to Embodiment 3 of the present invention;

[0017] Figure 4 This is a schematic structural diagram of the assembly of a single-axis acceleration MEMS sensor (with a flat pre-tightening structure disposed inside) according to Embodiment 4 of the present invention;

[0018] Figure 5 It is a structural schematic diagram of the assembly of a uniaxial acceleration MEMS sensor (a uniaxial pre-tightening structure is arranged inside, a sticky patch is arranged at the bottom, and a second pre-set socket rod is arranged inside the rigid shell) according to Embodiment 5 of the present invention;

[0019] Figure 6 This is a schematic diagram of the structure of the assembly of a uniaxial acceleration MEMS sensor (with a uniaxial pre-tightening structure arranged inside and a mounting seat arranged at the bottom) according to Embodiment 6 of the present invention;

[0020] Figure 7 This is a schematic diagram of the structure in which a PCB circuit board is arranged at the bottom of the rigid housing of the present invention;

[0021] Figure 8 This is a schematic diagram of the structure of the bottom of the rigid shell of the present invention;

[0022] Fig. 9 It is a structural schematic diagram of a comparative example of the present invention.

[0023] Fig.10It is a schematic diagram of a mechanical model of a comparative example of the present invention;

[0024] Fig.11 This is a schematic diagram of the mechanical model of Example 4 of the present invention.

[0025] The meanings of the reference numerals in the figure are as follows: 1-rigid cover plate, 2-rigid shell, 21-three-axis rigid shell, 22-single-axis rigid shell, 3-built-in cavity, 31-three-axis built-in cavity, 32-single-axis built-in cavity, 4-PCB circuit board, 5-MEMS chip, 6-chip pin, 7-solder point, 8-long center column, 9-first pre-tightening plate, 10-short center column, 11-second pre-tightening plate, 12-long flat head bolt, 13-third pre-tightening plate, 14-short flat head bolt, 15-fourth pre-tightening plate, 16-locating pin, 17-sticking, 18-mounting seat, 181-threaded hole, 19-preset socket rod, 191-first pre-set socket rod, 192-second pre-set socket rod, 20-bolt. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below in conjunction with the accompanying drawings to make it easier to understand and grasp. The components involved, such as the PCB circuit board 4, the MEMS chip 5 and the chip pins 6, are all commonly used by ordinary technicians in the field, and there is no special requirement for them in this case.

[0027] Example 1

[0028] See attached Figure 1As shown, in this embodiment 1, a rigid cover plate 1, a three-axis rigid shell 21, a PCB circuit board 4 and a MEMS chip 5 are included. The rigid cover plate 1 and the three-axis rigid shell 21 are fixed by threads to form a sealed connection structure. The inner bottom of the three-axis rigid shell 21 and the PCB circuit board 4 are integrated by positioning pins 16. A MEMS chip 5 is fixed on the upper part of the PCB circuit board 4. Under the premise of ensuring the installation accuracy, the PCB circuit board 4 and the MEMS chip 5 form a stacking assembly. The MEMS chip 5 and the PCB circuit board 4 are electrically connected by metal wires; the four sides of the lower part of the MEMS chip 5 are provided with There are chip pins 6, and each of the chip pins 6 is fixedly connected to the PCB circuit board 4 through a solder point 7. After welding is completed, the lead wires are led out. After the lead wire lead-out position is determined, it is installed into a three-axis rigid shell 21, and the lead wires are passed through the wire openings opened on the three-axis rigid shell 21; a three-axis built-in cavity 31 is formed inside the three-axis rigid shell 21, and the stacked assembly of the PCB circuit board 4 and the MEMS chip 5 is cured by pouring glue into the three-axis built-in cavity 31; a cubic pre-tightening structure is fixed on the rigid cover plate 1, and the upper end of the cubic pre-tightening structure is positioned at the center of the rigid cover plate 1, and the lower end of the cubic pre-tightening structure is pressed on the upper part of the MEMS chip 5.

[0029] Among them, as a three-axis sensor, it is necessary to ensure the installation accuracy of three different axes on the external structure installation surface, in addition to the bottom surface (Z axis), there are two side surfaces (X axis, Y axis), and the MEMS chip 5 and the three-axis rigid shell 21 need to ensure their parallelism and verticality accuracy. Figure 7 and Figure 8 As shown, a positioning countersunk hole b is provided at the bottom of the rigid shell 2, and a positioning through hole a is provided on the PCB circuit board 4 (the positioning through hole a needs to be specifically designed according to the model parameters of the PCB circuit board 4, avoiding the wiring and the pad, and setting two or more positioning through holes a, and making the positioning through holes a as far away from each other as possible to improve the positioning accuracy), the positioning countersunk hole b and the PCB circuit board 4 are aligned and interlaced through the positioning pin 16, thereby ensuring the accuracy during the installation process and the use process, and the positioning pin 16 fixes the horizontal angle of the PCB circuit board 4 and the bottom of the three-axis rigid shell 21, and effectively maintains this positioning accuracy.

[0030] Among them, the cubic pre-tightening structure includes a long central column 8 and a first pre-tightening plate 9, wherein the long central column 8 is arranged at the central part of the rigid cover plate 1 and is integrated with it, and the first pre-tightening plate 9 is a multi-layer buffer plate, and the first pre-tightening plate 9 is fixed to the tail of the long central column 8 and tightly pressed on the MEMS chip 5. When the cubic pre-tightening structure is adopted, after the rigid cover plate 1 is connected and pre-tightened with the three-axis rigid shell 21, the rigid cover plate 1 has a clamping force, that is, a relative pressure is generated between the rigid cover plate 1 and the three-axis rigid shell 21 to ensure the reliability of the connection; after the internal glue filling of the three-axis rigid shell 21, the axial pre-tightening force of the top cover completely acts on the stacking assembly of the PCB circuit board 4 and the MEMS chip 5, and the external load generated by the curing of the glue filling can effectively balance the clamping force of the rigid cover plate 1, and can fully eliminate the gap between the rigid cover plate 1 and the three-axis rigid shell 21 caused by the loose sealing.

[0031] The glue pouring process in this embodiment 1 is as follows: a three-axis acceleration sensor is used, including an X-axis, a Y-axis and a Z-axis. Before the glue pouring and curing, the angles of the X-axis and the Y-axis need to be adjusted to keep them parallel to the X-axis and Y-axis fixed surfaces respectively; the colloid is injected into the three-axis rigid shell 21 through the glue pouring equipment, and the glue pouring colloid uses epoxy resin to encapsulate the PCB circuit board 4 and the MEMS chip 5, and high-strength fiber short filaments are mixed in to improve the gel stiffness. Due to the three-axis pre-tightening structure set in the rigid cover plate 1, the pre-tightening force is continuously provided for the whole composed of the MEMS chip 5, the PCB circuit board 4 and the three-axis rigid shell 21 during the glue pouring until the colloid is completely cured, thereby ensuring the stable transmission of force.

[0032] Example 2

[0033] See attached Figure 2As shown, in this embodiment 2, a rigid cover plate 1, a three-axis rigid shell 21, a PCB circuit board 4 and a MEMS chip 5 are included. The rigid cover plate 1 and the three-axis rigid shell 21 are fixed by threads to form a sealed connection structure. The inner bottom of the three-axis rigid shell 21 and the PCB circuit board 4 are integrated by positioning pins 16. A MEMS chip 5 is fixed on the upper part of the PCB circuit board 4. Under the premise of ensuring the installation accuracy, the PCB circuit board 4 and the MEMS chip 5 form a stacking assembly. The MEMS chip 5 and the PCB circuit board 4 are electrically connected through metal wires; chip pins 6 are provided on the four sides of the lower part of the MEMS chip 5, and each of the chip pins 6 is connected to the PCB through a solder point 7. The circuit board 4 is fixedly connected, and the lead wires are led out after welding. After the lead wire lead-out position is determined, it is installed into the three-axis rigid shell 21, and the lead wires are passed through the wire opening opened on the three-axis rigid shell 21; a three-axis built-in cavity 31 is formed inside the three-axis rigid shell 21, and the stacked assembly of the PCB circuit board 4 and the MEMS chip 5 is cured by pouring glue into the three-axis built-in cavity 31; a three-axis pre-tightening structure is detachably provided on the rigid cover plate 1, and the upper end of the three-axis pre-tightening structure is positioned at the center of the rigid cover plate 1, and the lower end of the three-axis pre-tightening structure is pressed against the upper part of the MEMS chip 5; a sticky patch 17 is provided at the lower part of the three-axis rigid shell 21, and the sticky patch 17 is a double-sided tape or adhesive, which is mainly used for temporary installation, for example: used in vibration tests, for easy disassembly and assembly.

[0034] Among them, as a three-axis sensor, it is necessary to ensure the installation accuracy of three different axes on the external structural installation surface. In addition to the bottom surface (Z axis), there are two side surfaces (X axis, Y axis), and the MEMS chip 5 and the three-axis rigid shell 21 need to ensure their parallelism and verticality accuracy. To this end, a positioning countersunk hole b is provided at the bottom of the rigid shell 2, and a positioning through hole a is provided on the PCB circuit board 4. The positioning through hole a needs to be specifically designed according to the model parameters of the PCB circuit board 4, avoiding the wiring and the pad, and setting two or more positioning through holes a, and making each positioning through hole a as far away from each other as possible, so as to improve the positioning accuracy. The positioning countersunk hole b and the PCB circuit board 4 are aligned and interlaced through the positioning pin 16, so as to ensure the accuracy during the installation process and the use process. The horizontal angle of the PCB circuit board 4 and the bottom of the three-axis rigid shell 21 is fixed by the positioning pin 16, and this positioning accuracy is effectively maintained.

[0035] Among them, the three-axis pre-tightening structure includes a long flat head bolt 12 and a third pre-tightening plate 13. The head of the long flat head bolt 12 is positioned at the upper part of the rigid cover plate 1. The long flat head bolt 12 passes through the rigid cover plate 1 and is threadedly connected to the rigid cover plate 1. The third pre-tightening plate 13 is a multi-layer buffer plate, and the first pre-tightening plate 9 is fixed to the tail of the long flat head bolt 12 and tightly pressed on the MEMS chip 5. This design can achieve adjustable pre-stress, and can adjust the pre-stress for different MEMS chips, different frequencies and different applications to achieve better transmission performance.

[0036] The glue pouring process in this embodiment 2 is as follows: a three-axis acceleration sensor is used, including an X-axis, a Y-axis and a Z-axis. Before the glue pouring and curing, the angles of the X-axis and the Y-axis need to be adjusted to keep them parallel to the X and Y fixed surfaces respectively; the colloid is injected into the three-axis rigid shell 21 through the glue pouring equipment, and the glue pouring colloid uses epoxy resin to encapsulate the PCB circuit board 4 and the MEMS chip 5, and high-strength fiber short filaments are mixed in to improve the gel stiffness. Due to the three-axis pre-tightening structure set in the rigid cover plate 1, the pre-tightening force is continuously provided for the whole composed of the MEMS chip 5, the PCB circuit board 4 and the three-axis rigid shell 21 during the glue pouring until the colloid is completely cured, thereby ensuring the force transmission performance.

[0037] Example 3

[0038] See attached Figure 3As shown, in this embodiment 3, a rigid cover plate 1, a three-axis rigid shell 21, a PCB circuit board 4 and a MEMS chip 5 are included. The rigid cover plate 1 and the three-axis rigid shell 21 are fixed by welding to form a sealed connection structure. The inner bottom of the three-axis rigid shell 21 is integrated with the PCB circuit board 4. A MEMS chip 5 is fixed on the upper part of the PCB circuit board 4. Under the premise of ensuring the installation accuracy, the PCB circuit board 4 and the MEMS chip 5 form a stacked assembly. The MEMS chip 5 and the PCB circuit board 4 are electrically connected through metal wires; chip pins 6 are provided on the four sides of the lower part of the MEMS chip 5, and each of the chip pins 6 is fixedly connected to the PCB circuit board 4 through a solder point 7, and the welding After the lead-out is completed and the lead-out position is determined, it is installed into the three-axis rigid shell 21, and the lead-out is passed through the wire port opened on the three-axis rigid shell 21; a three-axis built-in cavity 31 is formed inside the three-axis rigid shell 21, and the PCB circuit board 4 and the MEMS chip 5 stacked assembly are cured by pouring glue into the three-axis built-in cavity 31; a three-axis pre-tightening structure is detachably provided on the rigid cover plate 1, and the upper end of the three-axis pre-tightening structure is positioned at the center of the rigid cover plate 1, and the lower end of the three-axis pre-tightening structure is pressed against the upper part of the MEMS chip 5; a mounting seat 18 is provided at the lower part of the three-axis rigid shell 21, and a plurality of threaded holes 181 are opened on the mounting seat 18, and threaded installation is mainly used for long-term installation, such as: use in household appliances, drones or communication equipment.

[0039] Among them, the interior of the three-axis rigid shell 21 is provided with several first preset socket rods 181 to enhance the tensile strength of the potting colloid, prevent cracking and improve the overall stability of the three-axis sensor packaging structure. As a three-axis sensor, it is necessary to ensure the installation accuracy of three different axes on the external structural mounting surface. In addition to the bottom surface (Z axis), there are two side surfaces (X axis, Y axis), and the MEMS chip 5 and the three-axis rigid shell 21 need to ensure their parallelism and verticality accuracy. To this end, a positioning countersunk hole b is provided at the bottom of the rigid shell 2, and a positioning through hole a is provided on the PCB circuit board 4. The positioning through hole a needs to be specifically designed according to the model parameters of the PCB circuit board 4, avoiding the wiring and the pad, and setting two or more positioning through holes a, and making each positioning through hole a as far away from each other as possible, so as to improve the positioning accuracy. The positioning countersunk hole b and the PCB circuit board 4 are aligned and interlaced through the positioning pin 16, thereby ensuring the accuracy during the installation process and the use process. The horizontal angle of the PCB circuit board 4 and the bottom of the three-axis rigid shell 21 is fixed by the positioning pin 16, and this positioning accuracy is effectively maintained.

[0040] In this embodiment, the three-axis pre-tightening structure includes a long flat head bolt 12 and a third pre-tightening plate 13. The head of the long flat head bolt 12 is positioned at the upper part of the rigid cover plate 1. The long flat head bolt 12 passes through the rigid cover plate 1 and is threadedly connected to the rigid cover plate 1. The third pre-tightening plate 13 is a multi-layer buffer plate, and the first pre-tightening plate 9 is fixed to the tail of the long flat head bolt 12 and tightly pressed on the MEMS chip 5. This design can achieve adjustable pre-stress, and can adjust the pre-stress for different MEMS chips, different frequencies and different applications to achieve better transmission performance.

[0041] The glue pouring process of this embodiment 3 is as follows: a three-axis acceleration sensor is used, including an X-axis, a Y-axis and a Z-axis. Before the glue pouring and curing, the angles of the X-axis and the Y-axis need to be adjusted to keep them parallel to the X-axis and Y-axis fixed surfaces respectively; the colloid is injected into the three-axis rigid shell 21 at least twice through the glue pouring equipment, so as to preferentially cure the PCB circuit board 4 and the three-axis rigid shell 21 to prevent the PCB circuit board 4 from positional displacement. The glue pouring colloid uses epoxy resin to encapsulate the PCB circuit board 4 and the MEMS chip 5, and high-strength fiber short filaments are mixed in to improve the gel stiffness. The tensile stress inside the colloid is transmitted and dispersed through several first preset socket rods 181 set inside the three-axis rigid shell 21, thereby improving the glue pouring curing rate. Since the three-axis pre-tightening structure set on the rigid cover plate 1 continuously provides pre-tightening force for the whole composed of the MEMS chip 5, the PCB circuit board 4 and the three-axis rigid shell 21 during the glue pouring until the colloid is completely cured, the force transmission performance can be guaranteed.

[0042] Example 4

[0043] See attached Figure 4 As shown, in this embodiment 5, a rigid cover plate 1, a uniaxial rigid shell 22, a PCB circuit board 4 and a MEMS chip 5 are included. The rigid cover plate 1 and the uniaxial rigid shell 22 are fixed by welding to form a sealed connection structure. The inner bottom of the uniaxial rigid shell 22 and the PCB circuit board 4 are integrated. A MEMS chip 5 is fixed on the upper part of the PCB circuit board 4. The PCB circuit board 4 and the MEMS chip 5 form a stacked assembly. The MEMS chip 5 and the PCB circuit board 4 are electrically connected through a metal wire. Chip pins 6 are provided on the four sides of the lower part of the MEMS chip 5, and each of the chip pins 6 is fixedly connected to the PCB circuit board 4 through a solder point 7; a uniaxial built-in cavity 32 is formed inside the uniaxial rigid shell 22, and the PCB circuit board 4 and the MEMS chip 5 stacking assembly are cured by pouring glue into the uniaxial built-in cavity 32; a flat pre-tightening structure is fixed on the rigid cover plate 1, and the upper end of the flat pre-tightening structure is positioned at the center of the rigid cover plate 1, and the lower end of the flat pre-tightening structure is pressed against the upper part of the MEMS chip 5.

[0044] The flat pre-tightening structure includes a short central column 10 and a second pre-tightening sheet 11. The short central column 10 is arranged at the central part of the rigid cover plate 1 and is integrated with the rigid cover plate 1. The second pre-tightening sheet 11 is a single-layer buffer sheet, and the second pre-tightening sheet 11 is fixed to the tail of the short central column 10 and tightly pressed on the MEMS chip 5. When the flat pre-tightening structure is adopted, after the rigid cover plate 1 is connected and pre-tightened with the uniaxial rigid shell 22, the rigid cover plate 1 has a clamping force, that is, a relative pressure is generated between the rigid cover plate 1 and the uniaxial rigid shell 22 to ensure the connection reliability.

[0045] The glue potting process in this embodiment 4 is as follows: a uniaxial acceleration sensor is used, and the colloid is injected into the uniaxial rigid shell 22 through a potting glue device. The glue potting colloid uses epoxy resin to encapsulate the PCB circuit board 4 and the MEMS chip 5, and high-strength fiber short filaments are mixed in to improve the gel stiffness. Due to the three-axis pre-tightening structure set in the rigid cover plate 1, a pre-tightening force is continuously provided for the whole composed of the MEMS chip 5, the PCB circuit board 4 and the uniaxial rigid shell 22 during the glue potting until the colloid is completely cured, thereby ensuring the force transmission performance.

[0046] Example 5

[0047] See attached Figure 5 As shown, in this embodiment 5, a rigid cover plate 1, a uniaxial rigid shell 22, a PCB circuit board 4 and a MEMS chip 5 are included. The rigid cover plate 1 and the uniaxial rigid shell 22 are fixed by welding to form a sealed connection structure. The inner bottom of the uniaxial rigid shell 22 and the PCB circuit board 4 are integrated. A MEMS chip 5 is fixed on the upper part of the PCB circuit board 4. The PCB circuit board 4 and the MEMS chip 5 form a stacked assembly. The MEMS chip 5 and the PCB circuit board 4 are electrically connected through metal wires. Chip pins 6 are provided on the four sides of the lower part of the MEMS chip 5. Each of the chip pins 6 are fixedly connected to the PCB circuit board 4 through solder points 7 respectively; a uniaxial built-in cavity 32 is formed inside the uniaxial rigid shell 22, and the PCB circuit board 4 and the MEMS chip 5 stacking assembly are cured by pouring glue into the uniaxial built-in cavity 32; a uniaxial pre-tightening structure is detachably provided on the rigid cover plate 1, the upper end of the uniaxial pre-tightening structure is positioned at the center of the rigid cover plate 1, and the lower end of the uniaxial pre-tightening structure is pressed against the upper part of the MEMS chip 5; a sticky patch 17 is provided at the lower part of the uniaxial rigid shell 22, and the sticky patch 17 is a double-sided tape or adhesive, which is mainly used for temporary installation, for example: used in vibration tests, for easy disassembly and assembly.

[0048] Among them, several second preset socket rods 182 are arranged inside the uniaxial rigid shell 22 to enhance the tensile strength of the potting colloid, prevent cracking and improve the overall stability of the uniaxial sensor packaging structure. The uniaxial pre-tightening structure includes a short flat head bolt 14 and a fourth pre-tightening plate 15. The head of the short flat head bolt 14 is positioned on the upper part of the rigid cover plate 1. The short flat head bolt 14 passes through the rigid cover plate 1 and is threadedly connected to the rigid cover plate 1. The fourth pre-tightening plate 15 is a single-layer buffer plate, and the fourth pre-tightening plate 15 is fixed to the tail of the short flat head bolt 14 and tightly pressed on the MEMS chip 5. This design can realize adjustable prestress, and can adjust the prestress for different MEMS chips, different frequencies and different applications to achieve better transmission performance.

[0049] The glue potting process in this embodiment 5 is as follows: a uniaxial acceleration sensor is used, and the colloid is injected into the uniaxial rigid shell 22 through a potting glue device. The glue potting colloid uses epoxy resin to encapsulate the PCB circuit board 4 and the MEMS chip 5, and high-strength fiber short filaments are mixed in to improve the gel stiffness. The tensile stress inside the colloid is transmitted and dispersed through several second preset socket rods 182 arranged inside the uniaxial rigid shell 22, thereby improving the curing rate of the glue potting. Due to the three-axis pre-tightening structure arranged on the rigid cover plate 1, a pre-tightening force is continuously provided for the whole composed of the MEMS chip 5, the PCB circuit board 4 and the uniaxial rigid shell 22 during the glue potting until the colloid is completely cured, thereby ensuring the force transmission performance.

[0050] Example 6

[0051] See attached Figure 6As shown, in this embodiment 6, a rigid cover plate 1, a uniaxial rigid shell 22, a PCB circuit board 4 and a MEMS chip 5 are included. The rigid cover plate 1 and the uniaxial rigid shell 22 are fixed by gluing to form a sealed connection structure. The inner bottom of the uniaxial rigid shell 22 is integrated with the PCB circuit board 4. A MEMS chip 5 is fixed on the upper part of the PCB circuit board 4. The PCB circuit board 4 and the MEMS chip 5 form a stacked assembly. The MEMS chip 5 and the PCB circuit board 4 are electrically connected through metal wires. Chip pins 6 are provided on the four sides of the lower part of the MEMS chip 5, and each of the chip pins 6 is respectively connected by welding. The tin point 7 is fixedly connected to the PCB circuit board 4; a uniaxial built-in cavity 32 is formed inside the rigid shell 2, and the PCB circuit board 4 and the MEMS chip 5 stacked assembly are cured by pouring glue into the uniaxial built-in cavity 32; a uniaxial pre-tightening structure is detachably provided on the rigid cover plate 1, and the upper end of the uniaxial pre-tightening structure is positioned at the center of the rigid cover plate 1, and the lower end of the uniaxial pre-tightening structure is pressed against the upper part of the MEMS chip 5; a mounting seat 18 is provided at the lower part of the uniaxial rigid shell 22, and a plurality of threaded holes 181 are opened on the mounting seat 18, and threaded installation is mainly used for long-term installation, such as: use in household appliances, drones or communication equipment.

[0052] Among them, the uniaxial pre-tightening structure includes a short flat head bolt 14 and a fourth pre-tightening plate 15, the head of the short flat head bolt 14 is positioned at the upper part of the rigid cover plate 1, the short flat head bolt 14 passes through the rigid cover plate 1 and is threadedly connected to the rigid cover plate 1, the fourth pre-tightening plate 15 is a single-layer buffer plate, and the fourth pre-tightening plate 15 is fixed to the tail of the short flat head bolt 14 and tightly pressed on the MEMS chip 5. This design can realize adjustable pre-stress, and can adjust the pre-stress for different MEMS chips, different frequencies and different applications to achieve better transmission performance.

[0053] The glue potting process in this embodiment 6 is as follows: a uniaxial acceleration sensor is used, and the colloid is injected into the uniaxial rigid shell 22 through a glue potting device. The glue potting colloid uses epoxy resin to encapsulate the PCB circuit board 4 and the MEMS chip 5, and high-strength fiber short filaments are mixed in to improve the gel stiffness. Due to the three-axis pre-tightening structure set in the rigid cover plate 1, a pre-tightening force is continuously provided for the whole composed of the MEMS chip 5, the PCB circuit board 4 and the uniaxial rigid shell 22 during the glue potting until the colloid is completely cured, thereby ensuring the force transmission performance.

[0054] Comparative Example

[0055] like Fig. 9As shown, an existing MEMS chip 5 is selected and directly installed on a PCB circuit board 4. The PCB circuit board 4 is installed on a structural attachment by means of bolts 20 (or snaps), so that the distance between the MEMS chip 5 and the PCB circuit board 4 and the structural attachments on which it is installed is kept as short as possible (to meet the needs of consumer products or other application scenarios with low requirements, and to reduce transmission losses). The distances between the bolts 20 on both sides and the MEMS chip are L1 and L2, respectively, to indicate that it has different transmission characteristics in different directions.

[0056] Effect verification

[0057] The mechanical models of Example 4 and the comparative example were established respectively, and mechanical analysis was performed on the two, wherein:

[0058] like Fig.10 As shown, a mechanical model of the comparative example is provided, K is the elastic coefficient, D is the damping coefficient, where D ph K is the damping coefficient in the thickness direction of the PCB circuit board 4; ph D is the elastic coefficient of the PCB circuit board 4 in the thickness direction; L1V and D L2V are the damping coefficients generated by the length of the transmission path from the mounting structure of the PCB circuit board 4 to the MEMS chip 5 in different transmission paths; K L1V and K L2V They are elastic coefficients generated by the length of the transmission path from the mounting structure of the PCB circuit board 4 to the MEMS chip 5 in different transmission paths.

[0059] like Fig.11 As shown, the mechanical model of Example 4 is provided, K is the elastic coefficient, D is the damping coefficient, wherein D' ph is the damping coefficient in the thickness direction of the PCB circuit board 4; K` ph is the elastic coefficient in the thickness direction of the PCB circuit board 4.

[0060] Compared with the above mechanical transmission characteristics, it can be seen that in the comparative example, the PCB circuit board 4 is a thin plate structure, D ph Much smaller than D L1V and D L2V , K ph Much larger than K L1V and K L2V. Therefore, the attenuation caused by L1 and L2 will play a major role, and its resonant frequency will be much lower than the resonant frequency in the thickness direction of the PCB. Moreover, when the distances between L1 and L2 are different, multiple different resonant frequencies and damping characteristics will cause corresponding distortions in the dynamic force transmitted from the structural attachment (i.e., the installation bottom), which will not only cause signal attenuation, but even cause adverse deformation in frequency and phase, thus causing signal distortion; on the contrary, in Example 4, the force transmission path is greatly simplified and shortened, the damping coefficient and elastic coefficient are both converted into single parameters, and through the rigid shell 1 and the overall glue curing, the overall stiffness is further enhanced compared to the single-layer PCB circuit board 5 of the comparative example, so D` ph Much smaller than D ph , and K` ph will be much larger than K ph , maintain good transmission performance and avoid signal distortion. ‌

[0061] Among the technical solutions of the present invention, the packaging structure that comprehensively improves the assembly rigidity of the MEMS chip 5 and the PCB circuit board 4 is the technical key of this case. Figure 1 and Figure 2 The focus is on the related components and specific structure of the three-axis acceleration sensor after glue filling. Figure 3 and Figure 4 What is shown is the relevant parts and specific structure of the uniaxial acceleration sensor after glue filling. The overall thickness of the uniaxial acceleration sensor is thinner than that of the triaxial acceleration sensor, which solves the problem that MEMS needs good mechanical transmission in the fields of scientific research, equipment and industrial field monitoring, so that it can obtain better adaptability and low cost, and can expand the scope of use of MEMS sensors in these fields (it can also be applied to multi-axis sensors such as six-axis and nine-axis). For components such as PCB circuit board 4, MEMS chip 5 and chip pin 6, ordinary technicians in this field can make conventional settings according to the existing technology, and this case has no special requirements for its model selection and combined use.

[0062] In this way, using the technical solution of the present invention, different types of MEMS sensors need to use different types of MEMS chips 5, such as: MEMS acceleration chip, MEMS pressure chip, MEMS temperature chip, MEMS humidity chip, MEMS angular velocity chip, etc., and use chip etching technology to realize the perception of various physical quantities through a specific installation structure, convert the physical quantities into electrical signals, and provide them to various applications through output signals for measuring and detecting various physical quantities.

[0063] From the above description, it can be found that compared with the prior art, after adopting the technical solution of the present invention, the transmission path between the PCB circuit board and the external mechanical environment is shortened to the greatest extent, the force transmission path is simplified, and the external force can be directly transmitted to the nearest position of the MEMS chip, effectively avoiding signal attenuation, and more accurately sensing and measuring the corresponding physical quantities; moreover, the rigid cover plate with a pre-tightening structure and the rigid shell fix the MEMS chip up and down, so that the sensor and the shell form a three-dimensional rigid structure, thereby improving the overall rigidity; the remaining built-in cavities in the rigid shell are cured by glue filling to achieve rigid strength in the horizontal direction, so as to reduce the loss of external force transmitted to the MEMS chip in the horizontal direction.

[0064] The technical scheme, working process and implementation effect of the present invention are described in detail above. It should be noted that what is described is only a typical example of the present invention. In addition, the present invention may also have many other specific implementation methods. Any technical scheme formed by equivalent replacement or equivalent transformation falls within the scope of protection required by the present invention.

Claims

1. A MEMS sensor with good mechanical properties, comprising a rigid cover plate (1), a rigid shell (2), a PCB circuit board (4) and a MEMS chip (5), wherein the rigid cover plate (1) and the rigid shell (2) are tightly connected, and characterized in that: The inner bottom of the rigid shell (2) and the PCB circuit board (4) are integrated by positioning pins (16), and the MEMS chip (5) is fixedly arranged on the upper part of the PCB circuit board (4); a built-in cavity (3) is formed inside the rigid shell (2), and the stacked assembly of the PCB circuit board (4) and the MEMS chip (5) is solidified by injecting glue into the built-in cavity (3); a pre-tightening structure is provided on the inner side of the rigid cover plate (1), and the lower end of the pre-tightening structure is pressed against the upper part of the MEMS chip (5).

2. A MEMS sensor with good mechanical properties according to claim 1, characterized in that: The rigid cover plate (1) and the rigid shell (2) are connected by means including but not limited to threaded fixing, welding fixing or adhesive fixing.

3. A MEMS sensor with good mechanical properties according to claim 1, characterized in that: The MEMS chip (5) is electrically connected to the PCB circuit board (4).

4. A MEMS sensor with good mechanical properties according to claim 1 or 3, characterized in that: Chip pins (6) are provided at four sides of the lower part of the MEMS chip (5), and each of the chip pins (6) is fixedly connected to the PCB circuit board (4) via a solder point (7).

5. A MEMS sensor with good mechanical properties according to claim 1, characterized in that: The lower part of the rigid shell (2) is provided with an adhesive patch (17) or a mounting seat (18), and the adhesive patch (17) is a double-sided adhesive tape or adhesive.

6. A MEMS sensor with good mechanical properties according to claim 5, characterized in that: The mounting seat (18) is provided with a threaded hole (181).

7. A MEMS sensor with good mechanical properties according to claim 1, characterized in that: The pre-tightening structure is a first pre-tightening structure or a second pre-tightening structure, the first pre-tightening structure is integrally arranged with the rigid cover plate (1), and the first pre-tightening structure comprises a cubic pre-tightening structure or a flat pre-tightening structure; the second pre-tightening structure is detachably mounted on the rigid cover plate (1), and the second pre-tightening structure comprises a triaxial pre-tightening structure or a uniaxial pre-tightening structure.

8. A MEMS sensor with good mechanical properties according to claim 7, characterized in that: A positioning countersunk hole (b) is provided at the bottom of the rigid shell (2), a positioning through hole (a) is provided on the PCB circuit board (4), and the positioning countersunk hole (b) and the PCB circuit board (4) are aligned and interlaced through the positioning pin (16).

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