High-impact-resistant MEMS overload sensor module

Abstract

The invention provides a high-impact-resistant MEMS overload sensor module. The impact resistance of an overload sensor is improved from the two aspects of structural design and packaging. The MEMS acceleration sensor comprises a stainless steel assembly tube shell, a PCB and an MEMS acceleration sensor. The MEMS acceleration sensor and related components thereof are welded on the PCB, the PCB is fixed in the module assembly tube shell through screws, and the module cover assembly plate is sealed after the module assembly tube shell is filled with pouring sealant; after the module assembling tube shell is assembled with the PCB, the pouring sealant filled in the module assembling tube shell can improve the impact resistance through pouring protection; the MEMS sensor is composed of an MEMS single-axis comb tooth capacitance type single-axis acceleration sensor structure and an ASIC (Application Specific Integrated Circuit) chip; the substrate and the MEMS sensitive structure are connected through anchor point supports and TSVs, the anchor points are discrete small-area anchor points, and compared with a traditional single fulcrum, the stress is lower.

Description

Technical Field

[0001] The invention belongs to the field of MEMS acceleration sensors, and in particular relates to a high-impact resistant MEMS overload sensor module. Background Art

[0002] MEMS overload sensors are currently widely used in aerospace, industrial automation, and other industrial fields. With the development of technology, higher requirements are put forward for the high impact resistance of MEMS overload sensors, such as: the impact acceleration requirement of vehicle-mounted equipment is greater than 5000g, the components in the missile-borne reconnaissance system are subjected to a short-term high overload of 10000g within 2-3ms, the 105mm smoothbore gun used in tanks, the maximum impact acceleration of the shell is about 10000g, and the maximum impact amplitude of the shell during the electromagnetic gun firing process is more than 40000g. In this article, g represents the acceleration of gravity. In order to ensure the normal function of the overload sensor under special working conditions, it is necessary to improve the high impact capability.

[0003] Under high impact, overload sensors are subject to failure modes such as adhesion failure, fracture, delamination, and air leakage. The most common failure is the fracture of the beam or mass block unit or the damage of the bonding, which causes the acceleration signal to jump and the system to make no judgment, causing immeasurable fatal damage. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a high-impact resistant MEMS overload sensor module, so as to improve the impact resistance of the overload sensor in view of the above-mentioned overload sensor failure mode.

[0005] The present invention provides a high-impact resistant uniaxial comb-tooth capacitive uniaxial overload sensor module, comprising an assembled tube shell, a PCB board and a MEMS acceleration sensor; The MEMS acceleration sensor is welded on the PCB board; The assembly tube shell is a hollow shell with an opening; The PCB board is fixed in the assembled tube shell, and potting glue is filled between the assembled tube shell and the PCB board.

[0006] The effect of the above settings is that the potting protection after assembly can improve the impact resistance and achieve normal function under high acceleration impact.

[0007] Furthermore, the MEMS acceleration sensor includes a packaging cover, a packaging shell, and a MEMS uniaxial comb-tooth capacitive uniaxial acceleration sensor structure and an application-specific integrated circuit chip (ASIC chip) disposed in the packaging shell; The MEMS uniaxial comb-teeth capacitive uniaxial acceleration sensor structure comprises a MEMS sensitive unit and a cap and a substrate for mounting the MEMS sensitive unit.

[0008] Furthermore, the MEMS sensitive structure includes a mass block, an elastic beam, fixed comb teeth and movable comb teeth; The fixed comb teeth are fixedly connected to the substrate via anchor points; The gaps between the fixed comb teeth match the gaps between the movable comb teeth, so that the movable comb teeth and the fixed comb teeth are staggered and have movable gaps of equal distance; The movable comb teeth are fixedly connected to the mass block, and the mass block is connected to the fixed comb teeth via an elastic beam; Driven by electrostatic force, the mass block connected to the elastic beam moves mechanically, causing the capacitance between the movable comb teeth and the fixed comb teeth to change, which is converted into an electrical signal output through the ASIC chip, thereby obtaining an acceleration change.

[0009] Furthermore, the fixed comb teeth include a central axis fixedly connected to the substrate via an anchor point and comb teeth extending vertically along both sides of the central axis; The movable comb teeth include side shafts arranged on both sides of the fixed comb teeth and comb teeth extending perpendicularly along the side shafts in the direction of the fixed comb teeth; the comb teeth of the movable comb teeth are staggered with the comb teeth of the fixed comb teeth and an equal distance of movable gaps are left; The ends of the side shafts are respectively connected to the mass blocks, and one end of the side shafts on both sides is connected to the same mass block and the same elastic beam.

[0010] Furthermore, the PCB board is connected with a module lead wire; the module lead wire penetrates the assembly tube shell.

[0011] Furthermore, an assembly cover plate is packaged at the opening of the assembly tube shell.

[0012] The above settings produce the following effects: the assembled cover plate can prevent the potting glue from leaking out and improve the sealing performance of the product.

[0013] Furthermore, the substrate and the MEMS sensitive structure are connected via anchor point support and TSV, and the anchor points are discrete small-area anchor points.

[0014] The above setting produces the effect of: lower stress compared with the traditional single fulcrum.

[0015] Furthermore, the cap, MEMS sensitive unit and substrate are all made of silicon.

[0016] Furthermore, the cap is connected to the MEMS sensitive structure via silicon-silicon bonding.

[0017] Furthermore, the MEMS sensitive structure also includes a double-stage stopper structure arranged at the edge of the MEMS single-axis comb-tooth capacitive single-axis acceleration sensor structure, which is used to limit the displacement of the movable comb teeth in two directions within the plane.

[0018] The above setting produces the following effect: In the MEMS sensitive structure, the displacement of the mechanical structure of the acceleration sensor in two directions in the plane is limited by the design of the double-stage stop structure in the plane.

[0019] Further, the bipolar stop structure comprises a first stop comb tooth arranged on the middle shaft and a second stop comb tooth arranged on the side shaft; The first stop comb teeth and the second stop comb teeth are arranged alternately and leave movable gaps.

[0020] Furthermore, the spacing between the first stop comb teeth and the second stop comb teeth on both sides of the central axis is not equal.

[0021] The above settings produce the following effects: two-stage stops to prevent the structure from being damaged under high impact.

[0022] Furthermore, a metal stop layer is provided on the cap to limit the displacement of the mechanical structure in the vertical direction, and to limit the displacement of the mass block under high impact to a safe range of the material.

[0023] The above settings have the effect of preventing the mechanical structure from being damaged by excessive impact.

[0024] Furthermore, the assembly tube shell is made of stainless steel; The material of the metal stopper layer is gold; the potting glue is silicone rubber; The MEMS package shell is made of ceramic material, and the MEMS package cover is made of metal material. The ASIC chip and the MEMS sensitive structure are both glued to the MEMS packaging tube shell, and the two are connected by metal wire bonding.

[0025] The beneficial effects achieved by the present invention are: The MEMS overload sensor module provided by the present invention has a dispersed small unit anchor point design of its MEMS sensitive structure that can reduce stress compared to a single anchor point structure. The double-stage stop structure arranged in the XY plane and the stop structure in the Z vertical direction can avoid high-impact failure within a certain limit. The potting protection after assembly can improve the impact resistance and realize normal function under high acceleration impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is an overall schematic diagram of the high-impact resistant MEMS overload sensor module of the present invention; Figure 2This is a schematic diagram of the internal assembly of the high-impact resistant MEMS overload sensor module of the present invention; Figure 3 The overall schematic diagram of the MEMS overload sensor module that is resistant to high impact; Figure 4 A schematic diagram of the sensitive structure of a MEMS overload sensor module that is resistant to high impact; Figure 5 A partial view of the sensitive structure stop unit of a MEMS overload sensor module that is resistant to high impact.

[0027] In the figure: 1. Assemble the tube shell; 2. Assemble the cover plate; 3. Module lead wires; 4. PCB board; 5. MEMS acceleration sensor; 6. Related electronic components; 7. MEMS packaging cover plate; 8. MEMS packaging tube shell; 9. ASIC circuit chip; 10. MEMS sensitive structure; 11. Metal wire; 12. Mass block; 13. Elastic beam; 14. In-plane (XY axis) stop unit; 15. Movable comb teeth; 16. Fixed comb teeth; 17. Anchor point; 18. Substrate; 19. Vertical direction (Z axis) stop unit; 20. Metal stop layer. DETAILED DESCRIPTION

[0028] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The present invention will be further described below in conjunction with the embodiments. Embodiment 1:

[0029] like Figure 1 As shown, this embodiment provides a MEMS overload sensor module, specifically a high-impact resistant single-axis comb-tooth capacitive single-axis overload sensor module, including an assembled tube shell 1, a PCB board 4 and a MEMS acceleration sensor 5; The MEMS acceleration sensor 5 is welded on the PCB board 4; The assembly tube shell 1 is a hollow shell with an opening; The PCB board 4 is fixed in the assembly tube shell 1 , and potting glue is filled between the assembly tube shell 1 and the PCB board 4 .

[0030] Implementation principle: The potting protection after assembly can improve the impact resistance and achieve normal function under high acceleration impact. Embodiment 2:

[0031] Figure 1This is an embodiment of the high-impact resistant MEMS overload sensor module of the present invention. Other shapes can be customized according to actual conditions. The assembly tube shell 1 and the assembly cover plate 2 are customized with stainless steel materials with a thickness of about 1 mm. The module lead wire 3 is a multi-core shielded wire. The stainless steel tube shell is mainly used to protect the PCB and the components thereon.

[0032] Figure 2 This is an internal assembly example of the high-impact resistant MEMS overload sensor module described in the present invention. The MEMS acceleration sensor 5 and its related electronic components 6 are mounted on the PCB board 4 through the SMT patch process. The PCB board 4 is fixed to the assembly tube shell 1 by screws and then filled with potting glue for sealing. The potting glue used in this embodiment is silicone rubber, and polyurethane potting glue, silicone rubber-epoxy resin-electronic potting glue, etc. can also be used. Then the assembly cover plate 2 is sealed and assembled with glue.

[0033] Figure 3 In the embodiment of the high-impact MEMS acceleration resistant packaging of the present invention, the MEMS packaging shell 8 is made of ceramic material, the MEMS packaging cover 7 is made of metal material, the ASIC circuit chip 9 and the MEMS sensitive structure 10 are glued to the MEMS packaging shell 8, and the two are bonded and connected by a metal wire 11. The metal wire 11 in the embodiment is gold Au, and other metal materials can be used according to actual conditions.

[0034] like Figure 4-5 As shown, specifically, the fixed comb teeth 16 include a central axis fixedly connected to the substrate through an anchor point 17 and comb teeth extending vertically along both sides of the central axis; The movable comb teeth 15 include side shafts arranged on both sides of the fixed comb teeth 16 and comb teeth extending vertically along the side shafts toward the fixed comb teeth 16; the comb teeth of the movable comb teeth 15 and the comb teeth of the fixed comb teeth 16 are staggered and have movable gaps of equal distance; The ends of the side shafts are respectively connected to the mass block 12 and one end of the side shafts on both sides are connected to the same mass block 12 and the same elastic beam 13 .

[0035] The MEMS sensitive structure 10 also includes a double-stage stop structure arranged at the edge of the MEMS single-axis comb-tooth capacitive single-axis acceleration sensor structure, namely an in-plane (XY axis) stop unit 14 and a vertical direction (Z axis) stop unit 19, which are used to limit the displacement of the movable comb teeth 15 in two directions in the plane.

[0036] The bipolar stop structure comprises a first stop comb tooth arranged on the middle shaft and a second stop comb tooth arranged on the side shaft; The first stop comb teeth and the second stop comb teeth are arranged alternately and leave movable gaps.

[0037] Preferably, the spacing between the first stop comb teeth and the second stop comb teeth on both sides is not equal. The two-stage stop prevents the structure from being damaged under high impact. Figure 4 As shown, the MEMS sensitive structure 10 is made of silicon material, and the fixed comb tooth unit 16 is connected to the substrate through discrete anchor points. Driven by electrostatic force, the mass block 12 connected to the folded elastic beam 13 mechanically moves, so that the capacitance between the movable comb teeth 15 and the fixed comb teeth 16 changes, which is converted into an electrical signal output through the ASIC circuit chip 9, thereby obtaining an acceleration change.

[0038] The anchor points 17 are discrete small areas, which can release stress to a certain extent compared with a single large area anchor point, and is beneficial to improving the performance of the acceleration sensor.

[0039] The in-plane (XY axis) stopper unit 14 and movable comb teeth 15 are also made of silicon material (common material for MEMS structures), and the illustration is only for distinction and ease of observation.

[0040] Figure 5 The in-plane (XY axis) stop unit 18 comb tooth spacing d2>d1 shown in the left figure, that is, the second stop comb teeth below are thinner than the second stop comb teeth above, which can achieve double-stage stopping. The double-cascade stopping has stronger resistance to high-frequency impact. The vertical direction (Z axis) stop unit 19 shown in the right figure has a metal stop layer 20 (the metal used in the embodiment is Au) on the silicon cap, that is, the vertical direction (Z axis) stop unit 19 can protect the mechanical structure from damage caused by the impact in the Z direction. It can be seen from the figure that the fixed comb teeth 16 are arranged on the substrate 18, and the metal stop layer 20 is arranged above it. The sputtered metal stop layer 20 can also use other suitable metal materials or flexible materials, that is, it stops in the vertical direction to limit excessive movement of the structure to prevent damage and functional failure.

[0041] The stop structure design in three directions can improve the impact resistance of the MEMS acceleration sensor, which is beneficial to the normal operation of the overload sensor in harsh environments.

[0042] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features, and in the description of the present invention, "plurality" means two or more, unless otherwise clearly and specifically defined.

[0043] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0045] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0046] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A high-impact resistant MEMS overload sensor module, It is characterized in that Including assembling tube shell, PCB board and MEMS acceleration sensor; The MEMS acceleration sensor is welded on the PCB board; The assembly tube shell is a hollow shell with an opening; The PCB board is fixed in the assembled tube shell, and potting glue is filled between the assembled tube shell and the PCB board.

2. The high-shock resistant MEMS overload sensor module according to claim 1, It is characterized in that The MEMS acceleration sensor comprises a packaging cover, a packaging shell, and a MEMS uniaxial comb-tooth capacitive uniaxial acceleration sensor structure and an ASIC chip arranged in the packaging shell; The MEMS uniaxial comb-tooth capacitive uniaxial acceleration sensor structure includes a MEMS sensitive unit and a cap and a substrate for mounting the MEMS sensitive unit; The MEMS sensitive structure includes a mass block, an elastic beam, fixed comb teeth and movable comb teeth; The fixed comb teeth are fixedly connected to the substrate via anchor points; The gaps between the fixed comb teeth match the gaps between the movable comb teeth, so that the movable comb teeth and the fixed comb teeth are staggered and have movable gaps of equal distance; The movable comb teeth are fixedly connected to the mass block, and the mass block is connected to the fixed comb teeth via an elastic beam; Driven by electrostatic force, the mass block connected to the elastic beam moves mechanically, causing the capacitance between the movable comb teeth and the fixed comb teeth to change, which is converted into an electrical signal output through the ASIC chip, thereby obtaining an acceleration change.

3. The high-shock resistant MEMS overload sensor module according to claim 2, It is characterized in that The fixed comb teeth include a central axis fixedly connected to the substrate through an anchor point and comb teeth extending along both sides of the central axis; The movable comb teeth include side shafts arranged on both sides of the fixed comb teeth and comb teeth extending along the side shafts in the direction of the fixed comb teeth; the comb teeth of the movable comb teeth are staggered with the comb teeth of the fixed comb teeth and an equal distance of movable gaps are left; The ends of the side shafts are respectively connected to the mass blocks, and one end of the side shafts on both sides is connected to the same mass block and the same elastic beam.

4. The high-shock resistant MEMS overload sensor module according to claim 2, It is characterized in that The PCB board is connected with a module lead-out wire; the module lead-out wire penetrates the assembly tube shell.

5. The high-shock resistant MEMS overload sensor module according to claim 2, It is characterized in that An assembly cover plate is packaged at the opening of the assembly tube shell.

6. The high-shock resistant MEMS overload sensor module according to claim 2, It is characterized in that The substrate and the MEMS sensitive structure are connected via anchor point support and TSV, and the anchor points are discrete small-area anchor points.

7. The high-shock resistant MEMS overload sensor module according to claim 2, It is characterized in that The cap, MEMS sensitive unit and substrate are all made of silicon.

8. The high-shock resistant MEMS overload sensor module according to claim 2, It is characterized in that The cap is connected to the MEMS sensitive structure through silicon-silicon bonding.

9. The high-shock resistant MEMS overload sensor module according to claim 2, It is characterized in that The MEMS sensitive structure also includes a double-stage stopper structure arranged at the edge of the MEMS single-axis comb-tooth capacitive single-axis acceleration sensor structure, which is used to limit the displacement of the movable comb teeth in two directions within the plane.

10. The high-shock resistant MEMS overload sensor module according to claim 2, It is characterized in that The assembly tube shell is made of stainless steel; The material of the metal stopper layer is gold; the potting glue is silicone rubber; The packaging tube shell is made of ceramic material, and the packaging cover is made of metal material. The ASIC chip and the MEMS sensitive structure are both glued to the packaging tube shell, and the two are connected by metal wire bonding.

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