Low-Q-value piezoelectric accelerometer and preparation method thereof

Abstract

The invention discloses a low-Q-value piezoelectric accelerometer and a preparation method, and the low-Q-value piezoelectric accelerometer comprises a base which is of a hollow structure with the upper end and the lower end being open; the movement assembly comprises a cantilever assembly and a mass block connected to the cantilever assembly; an upper air damping layer is formed in the area where the upper clamping plate layer and the motion assembly coincide in the projection direction; the lower clamping plate layer is connected with the bottom of the base in a bonding mode, a gap exists between the lower clamping plate layer and the mass block, and a lower air damping layer is formed in the overlapped area of the lower clamping plate layer and the mass block in the projection direction. According to the low-Q-value piezoelectric accelerometer provided by the embodiment of the invention, the air damping layers are respectively formed above and below the motion assembly, so that the total damping value of the system is increased, the purpose of reducing the Q value is achieved, the low-Q-value piezoelectric accelerometer is obtained, and the increase of the response bandwidth of the accelerometer is realized.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, and in particular to a low-Q piezoelectric accelerometer and its fabrication method. Background Technology

[0002] For vibration sensors, a wider bandwidth results in richer and more realistic data acquisition. For example, bone conduction vibration sensors in TWS earphones require a bandwidth of over 4kHz. However, existing piezoelectric vibration sensors have relatively narrow bandwidths, failing to meet these requirements. Vesper's existing piezoelectric accelerometer solution has a ±3dB bandwidth of only about 1.4kHz, far from meeting the needs of the target application scenario. (See also...) Figure 1 The figure shows a reference curve of the accelerometer's response bandwidth versus frequency. Increasing the intermediate receiving frequency can increase the bandwidth, but this will lead to a performance degradation; while increasing the system damping can achieve the same result, which has virtually no impact on the signal-to-noise ratio (SNR).

[0003] Since the Q value is closely related to the system damping, the applicant proposes a low-Q piezoelectric accelerometer and its fabrication method to increase the bandwidth requirement of the accelerometer. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a low-Q piezoelectric accelerometer and its preparation method that overcome or at least partially solve the above problems.

[0005] Other features and advantages of the invention will become apparent from the following detailed description, or may be learned in part by practice of the invention.

[0006] According to a first aspect of the present invention, a low-Q piezoelectric accelerometer is provided, the low-Q piezoelectric accelerometer comprising:

[0007] The base is a hollow structure with openings at both the top and bottom;

[0008] A motion component includes a cantilever assembly and a mass block connected to the cantilever assembly; the cantilever assembly includes a fixed end and a free end, the fixed end of the cantilever assembly is connected to the base, the free end of the cantilever assembly extends inward to the base along the X-axis or Y-axis, and the mass block is connected to the bottom of the free end of the cantilever assembly; the mass block can move along the Z-axis with the free end of the cantilever assembly as a support point.

[0009] An upper clamping layer is connected to the upper end of the base and covers the motion component directly above it. There is a gap between the upper clamping layer and the motion component, and the area where the upper clamping layer and the motion component overlap in the projection direction forms an upper air damping layer.

[0010] The lower clamping layer is connected to the bottom of the base by bonding, and there is a gap between the lower clamping layer and the mass block. The area where the lower clamping layer and the mass block overlap in the projection direction forms a lower air damping layer.

[0011] In some embodiments of the present invention, the cantilever assembly includes a piezoelectric composite layer, a cantilever beam, and an oxide layer that are fixedly connected from top to bottom.

[0012] In some embodiments of the present invention, the upper clamping layer fully or partially covers the area directly above the mass block.

[0013] In some embodiments of the present invention, the upper and lower ends of the mass block are both planar.

[0014] In some embodiments of the present invention, a connecting block is provided at the connection between the mass block and the free end of the cantilever assembly, and the connecting block is generated by etching to thin the upper end of the mass block.

[0015] In some embodiments of the present invention, at least two end faces of the upper clamping layer are connected to the base.

[0016] In some embodiments of the present invention, the upper clamping plate layer is at the same height as the cantilever assembly.

[0017] In some embodiments of the present invention, the upper clamping layer is bonded to the top of the base.

[0018] In some embodiments of the present invention, a reinforcing layer is provided at the upper end of the upper clamping layer.

[0019] According to a second aspect of the present invention, a method for fabricating a low-Q piezoelectric accelerometer is provided, the method comprising:

[0020] Based on the target Q value, the total damping value is determined, which is the sum of the upper air damping value of the upper air damping layer and the lower air damping value of the lower air damping layer.

[0021] The base, cantilever assembly, mass block, and lower clamping plate layer are connected in sequence.

[0022] Obtain the bottom area of ​​the mass block and the first height data of the lower air damping layer, and obtain the lower air damping value based on the first height data and the bottom area of ​​the mass block;

[0023] The upper air damping value is obtained based on the total damping value and the lower air damping value.

[0024] The effective area of ​​the top of the motion component and the second height data of the upper air damping layer are determined based on the upper air damping value. The effective area of ​​the top of the motion component is characterized as the area of ​​the region where the upper clamping plate layer and the mass block coincide in the projection direction. The second height data is characterized as the setting height of the gap between the upper clamping plate layer and the mass block.

[0025] The upper clamping layer is set according to the determined overlapping area and the set height of the gap to obtain the low Q value piezoelectric accelerometer.

[0026] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0027] The low-Q piezoelectric accelerometer described in this embodiment of the invention increases the total damping value of the system by forming air damping layers above and below the moving component, thereby achieving the goal of reducing the Q value and thus obtaining the low-Q piezoelectric accelerometer, thereby increasing the response bandwidth of the accelerometer.

[0028] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a reference curve showing the response bandwidth versus frequency of the accelerometer.

[0031] Figure 2 This is a schematic diagram of the structure of a low-Q piezoelectric accelerometer provided in an embodiment of the present invention;

[0032] Figure 3 This is a schematic diagram of a three-sided fixed-support structure for a low-Q piezoelectric accelerometer.

[0033] Figure 4 A schematic diagram of a low-Q piezoelectric accelerometer with fixed supports on both sides;

[0034] Figure 5 This is a schematic diagram showing the upper sandwich layer covering the portion directly above the mass block when both sides are fixed.

[0035] Figure 6 This is a schematic diagram showing the upper sandwich layer covering the portion directly above the mass block when the three sides are fixed.

[0036] Figure 7 A schematic diagram of a structure in which the upper clamping layer and the cantilever assembly are set at the same height when the two sides are fixed;

[0037] Figure 8 A schematic diagram of a structure in which the upper clamping layer and the cantilever assembly are set at the same height when the three sides are fixed;

[0038] Figure 9 A schematic diagram of a structure with connecting blocks when the structure is fixed on both sides;

[0039] Figure 10 A schematic diagram of a structure with connecting blocks for three-sided fixed support;

[0040] Figure 11 This is a schematic diagram of a structure with a reinforcement layer.

[0041] Figure 12 A schematic diagram of a low-Q piezoelectric accelerometer with biaxial sensing.

[0042] Figure 13 A schematic diagram of a low-Q piezoelectric accelerometer for quadcopter detection;

[0043] Figure 14 This is a schematic flowchart illustrating a method for preparing a low-Q piezoelectric accelerometer according to an embodiment of the present invention.

[0044] Explanation of reference numerals in the attached figures:

[0045] 1. Upper clamping plate layer; 2. Mass block; 3. Cantilever assembly; 4. Cantilever beam; 5. Piezoelectric composite layer; 6. Oxide layer; 7. Lower clamping plate layer; 8. Base; 9. Solder pad; 10. Dielectric layer; 11. Upper air damping layer; 12. Lower air damping layer; 13. Connecting block; 14. Reinforcing layer. Detailed Implementation

[0046] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings.

[0047] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0048] In the context of this disclosure, when a layer / component is referred to as being "above" another layer / component, that layer / component may be directly above the other layer / component, or there may be an intermediate layer / component between them. Additionally, if a layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component may be "below" the other layer / component. In the context of this disclosure, similar or identical components may be denoted by the same or similar reference numerals.

[0049] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to specific implementation methods. It should be understood that the embodiments of this disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0050] The low-Q piezoelectric accelerometer described in this embodiment of the invention is applied to electronic devices, including consumer products, home products, vehicle-mounted products, wearable products, financial terminal products, communication products, and intelligent detection products.

[0051] The electronic device can have the function of vibration signal acquisition. It can be applied to various communication systems or protocols, such as: Global System for Mobile Communication (GSM), Code Division Multiple Access (CDMA) system, Wideband Code Division Multiple Access (WCDMA), General Packet Radio Service (GPRS), Long Term Evolution (LTE), etc.

[0052] For example, in this embodiment of the invention, the electronic device may be a TWS earphone. Taking the TWS earphone as an example, since the Q value (Quality Factor) is negatively correlated with the response bandwidth of the accelerometer in the TWS earphone, this embodiment of the invention increases the response bandwidth of the accelerometer by reducing the Q value. Simultaneously, based on... Where k is the stiffness of the system, f c f is the center frequency. l f is the lower cutoff frequency. u If the upper cutoff frequency is the highest, then the greater the damping, the lower the Q value. For low-frequency vibrations in air, the damping comes from material loss and air friction loss. However, material loss has a relatively small impact on damping. This invention proposes a low-Q piezoelectric accelerometer by increasing air damping to reduce the Q value.

[0053] Specifically Figure 2 This is a schematic diagram of the structure of a low-Q piezoelectric accelerometer provided in an embodiment of the present invention. Figure 3 A side sectional view of the low-Q piezoelectric accelerometer is shown below. Figure 2-3 As shown, the low-Q piezoelectric accelerometer includes:

[0054] The base 8 is a hollow structure with openings at both the top and bottom, which is used to provide a receiving space and physical support function;

[0055] The motion component includes a cantilever assembly 3 and a mass block 2 connected to the cantilever assembly 3; the cantilever assembly 3 includes a fixed end and a free end, the fixed end of the cantilever assembly 3 is connected to the base 8, the free end of the cantilever assembly 3 extends inward to the base 8 along the X-axis or Y-axis, and the mass block 2 is connected to the bottom of the free end of the cantilever assembly 3; the mass block 2 can move along the Z-axis by using the free end of the cantilever assembly 3 as a support point.

[0056] The upper clamping layer 1 is connected to the upper end of the base 8 and covers the motion component directly above it. There is a gap between the upper clamping layer 1 and the motion component, and the area where the upper clamping layer 1 and the motion component overlap in the projection direction forms an upper air damping layer 11.

[0057] The lower clamping plate layer 7 is connected to the bottom of the base 8 by bonding, and there is a gap between the lower clamping plate layer 7 and the mass block 2. The area where the lower clamping plate layer 7 and the mass block 2 overlap in the projection direction (in this embodiment, the Z-axis direction, the same below) forms the lower air damping layer 12.

[0058] This invention first determines the required target Q value, and based on the target Q value, determines the total damping value γ.gas , In the formula, m is the equivalent mass of the system, and ω is the natural angular frequency of the system. The target Q value can be selected according to actual needs, and there are no restrictions on this in the embodiments of the present invention.

[0059] The total damping value γ gas The sum of the upper air damping value γ1 of the upper air damping layer 11 and the lower air damping value γ2 of the lower air damping layer 12, γ gas =γ1 + γ2;

[0060] Among them, based on the calculation principle of conventional air damping (compression film damping), the upper air damping value of the upper air damping layer 11 is... The lower air damping value of the lower air damping layer 12 In the formula, μ is the equivalent viscosity of air, A1 is the effective area of ​​the top of the moving component, d1 is the height of the gap between the moving component and the upper clamping layer 1 (i.e., the second height data), A2 is the bottom area of ​​the mass block 2, and d2 is the height of the gap between the mass block 2 and the lower clamping layer 7 (i.e., the first height data).

[0061] After the lower clamping layer 7 is bonded, the positions of the base 8, cantilever assembly 3, mass block 2, and lower clamping layer 7 are relatively fixed, which has no substantial impact on the total damping value calculated subsequently. Therefore, in this embodiment of the invention, the required upper air damping value is determined by determining the target Q value and the lower air damping value. After connecting the base 8, cantilever assembly 3, mass block 2, and lower clamping layer 7 in sequence, the spatial positional relationship between the upper clamping layer 1 and the mass block 2 is determined to obtain the upper air damping value.

[0062] Specifically, in this embodiment of the invention, the bottom area of ​​the mass block 2 and the first height data of the lower air damping layer 12 are obtained; the lower air damping value is obtained based on the first height data and the bottom area of ​​the mass block 2; the upper air damping value is obtained based on the total damping value and the lower air damping value; the effective top area of ​​the motion component and the second height data of the upper air damping layer 11 are determined based on the upper air damping value; the effective top area of ​​the motion component is characterized as the area of ​​the region where the upper clamping layer 1 and the mass block 2 overlap in the projection direction; the second height data is characterized as the setting height of the gap between the upper clamping layer 1 and the mass block 2; the upper clamping layer 1 is set according to the determined overlapping area and the setting height of the gap to obtain the low Q value piezoelectric accelerometer.

[0063] In this embodiment of the invention, the cantilever assembly 3 includes a piezoelectric composite layer 5, a cantilever beam 4, and an oxide layer 6, which are fixedly connected from top to bottom. The piezoelectric composite layer 5 is a piezoelectric stress detection structure, and its material can be AlN / Mo / AlScN / Mo, or SiO2 / AlN / Mo / AlScN / Mo, etc., and it has a pressure detection function. The cantilever beam 4 is made of the same material as the base 8, which is silicon, providing a supporting function. The oxide layer 6 can be made of silicon oxide, etc., providing a protective function.

[0064] In this embodiment of the invention, the upper clamping layer 1 can be bonded to the top of the base 8. At this time, the area where the upper clamping layer 1 and the cantilever assembly 3 overlap in the projection direction forms the upper air damping layer 11. When the upper clamping layer 1 and the lower clamping layer 7 are bonded, a dielectric layer 10 is provided at the connection between the upper clamping layer 1 and the lower clamping layer 7 and the base 8 to realize wafer-level packaging.

[0065] In this embodiment of the invention, at least two end faces of the upper clamping layer 1 are connected to the base 8 to ensure that the upper clamping layer 1 has sufficiently stable support, wherein, combined with Figure 4 As shown, the upper clamping layer 1 can be perpendicular to the extension direction of the cantilever beam 4 (if it is the X-axis direction), wherein two opposing end faces (in the Y-axis direction) are connected to the base 8 to achieve two-sided fixed support; in order to further improve the stability of the connection of the upper clamping layer 1, combined with Figure 3 As shown, two opposing end faces of the upper clamping plate layer 1 and the end face away from the fixed end of the cantilever beam 4 are respectively connected to the base 8 to achieve three-sided fixed support.

[0066] In this embodiment of the invention, the area where the upper clamping plate layer 1 and the mass block 2 overlap in the projection direction is determined based on the effective area of ​​the top of the motion component. Then, depending on actual needs, the upper clamping plate layer 1 may fully or partially cover the area directly above the mass block 2. Figure 3 and Figure 4 As shown, the upper clamping layer 1 completely covers the area directly above the mass block 2. Figure 5 The diagram shows the upper clamping plate layer 1 covering the portion directly above the mass block 2 when the plate is fixed on both sides. Figure 6 The diagram shows the upper clamping plate layer 1 fully covering the top of the mass block 2 when it is fixed on three sides. Depending on the actual application scenario, a suitable method can be selected, and the embodiments of the present invention do not limit this.

[0067] It should be noted that, since both the upper air damping layer 11 and the lower air damping layer 12 are pressure film dampers, in this embodiment of the invention, the upper and lower ends of the mass block 2 are both planar, so as to obtain a stable damping effect and facilitate the acquisition of an accurate target Q value.

[0068] In this embodiment of the invention, the upper clamping plate layer 1 is at the same height as the cantilever assembly 3, and the upper clamping plate layer 1 covers directly above the mass block 2. That is, the area where the upper clamping plate layer 1 and the mass block 2 overlap in the projection direction forms an upper air damping layer 11. By setting the upper clamping plate layer 1 and the cantilever assembly 3 at the same height, the overall thickness of the low-Q piezoelectric accelerometer can be effectively reduced. (See reference...) Figure 7 The diagram shown is a structural schematic of the upper clamping plate layer 1 and the cantilever assembly 3 being set at the same height when both sides are fixed. (See reference...) Figure 8 The diagram shows a structural schematic of the upper clamping plate layer 1 and the cantilever assembly 3 being set at the same height when the upper clamping plate layer 1 and the cantilever assembly 3 are fixed on three sides.

[0069] In this embodiment of the invention, a connecting block 13 is provided at the connection between the mass block 2 and the free end of the cantilever assembly 3. The connecting block 13 is formed by etching the upper end of the mass block 2 to reduce its thickness. This reduces the overall thickness of the low-Q piezoelectric accelerometer while increasing the second height data corresponding to the upper air damping layer 11, thus improving the flexibility and applicability of the product design. (See also...) Figure 9 The diagram shown is a structural schematic of a connecting block 13 installed when the device is fixed on both sides. (See attached diagram.) Figure 10 The diagram shown is a structural schematic of a connecting block 13 when the device is fixed on three sides.

[0070] Of course, it should be noted that in this embodiment of the invention, due to the limitation of the material's ductility, the overall thickness of the low-Q piezoelectric accelerometer is considered, and the second height data corresponding to the upper air damping layer 11 is 1um to 20um, and the height of the connecting block 13 is 0.5 to 20um. In other embodiments of the invention, the second height data and the height of the connecting block 13 can also be set to other values ​​according to actual application requirements, and this embodiment of the invention does not limit this.

[0071] To improve the structural stability of the upper sandwich layer 1, refer to Figure 11 As shown, in this embodiment of the invention, a reinforcing layer 14 is provided at the upper end of the upper clamping plate layer 1. The reinforcing layer 14 may be polycrystalline silicon, an organic layer, etc. The reinforcing layer 14 may partially or fully cover the upper clamping plate layer 1 to provide protective support function.

[0072] In this embodiment of the invention, the motion component is further provided with a pad 9, which is used to electrically connect with other active devices in the electronic device, such as a PCB circuit board.

[0073] In this embodiment of the invention, the motion component may be a single set, or two sets of motion components symmetrically distributed to achieve two-axis detection, or four sets of motion components symmetrically distributed to achieve two-axis detection; see reference Figure 12 The diagram shows a schematic of a biaxially oriented low-Q piezoelectric accelerometer. The two sets of motion components are respectively connected to the base 8, facing inwards. The upper clamping layer 1 is located directly above the mass block 2 and is connected to the base 8. (See reference...) Figure 13 The diagram shows a low-Q piezoelectric accelerometer with quadriaxial detection. The four sets of motion components are respectively connected to the base 8 and arranged inwards. The upper clamping plate layer 1 is located directly above the mass block 2 and is connected to the base 8.

[0074] Furthermore, in order to increase the release rate of the mass block 2, when the motion component is a multi-axis detection, the motion component can also be provided with through holes to facilitate the increase of airflow.

[0075] Accordingly, depending on the process, when the motion component is for multi-axis detection, after the connecting block 13 is etched out, the area of ​​the mass block 2 corresponding to the upper clamping layer 1 can be towards the inside of the base 8 (facing inwards), or away from the inside of the base 8 (facing outwards), such as... Figure 12 The area in the middle corresponds to the mass block 2 and the upper clamping layer 1, and is located on the inner side away from the base 8. The arrangement can be made according to actual application requirements, and there are no restrictions on this in this embodiment of the invention.

[0076] The low-Q piezoelectric accelerometer described in this embodiment of the invention has the following advantages compared to the prior art:

[0077] 1. By forming air damping layers above and below the moving components, the total damping value of the system is increased, thereby achieving the goal of reducing the Q value and obtaining the low Q value piezoelectric accelerometer, thus increasing the response bandwidth of the accelerometer;

[0078] 2. The setting of the upper clamping layer 1 is determined according to the target Q value. Based on the connection method between the upper clamping layer 1 and the base 8, a connection method with two or more ends can be selected, and the upper clamping layer 1 can fully or partially cover the motion component, so as to be applicable to the needs of different application scenarios and improve the applicability of the product.

[0079] 3. The mass block 2 is thinned by etching, which reduces the overall thickness of the product. At the same time, the stepped back cavity structure also reduces the maximum lateral displacement of the mass block 2 during lateral movement, increases the damping of lateral displacement, increases reliability, and reduces the Q value.

[0080] 4. A reinforcing layer 14 is provided on the upper plywood layer 1, which greatly improves the stability of the structure, increases its impact resistance, and avoids the risk of fracture of the upper plywood layer 1.

[0081] Based on the above embodiments, this invention provides an embodiment of a method for preparing a low-Q piezoelectric accelerometer, which is similar to... Figure 2 Corresponding to the embodiments shown, see the following: Figure 14 As shown, the method for preparing the low-Q piezoelectric accelerometer includes the following steps:

[0082] S1. Based on the target Q value, determine the total damping value, which is the sum of the upper air damping value of the upper air damping layer 11 and the lower air damping value of the lower air damping layer 12.

[0083] S2. Connect the base 8, cantilever assembly 3, mass block 2 and lower clamping plate layer 7 in sequence;

[0084] S3. Obtain the bottom area of ​​the mass block 2 and the first height data of the lower air damping layer 12, and obtain the lower air damping value based on the first height data and the bottom area of ​​the mass block 2.

[0085] S4. Obtain the upper air damping value based on the total damping value and the lower air damping value;

[0086] S5. Determine the effective area of ​​the top of the motion component and the second height data of the upper air damping layer 11 based on the upper air damping value, wherein the effective area of ​​the top of the motion component is characterized as the area of ​​the region where the upper clamping plate layer 1 and the mass block 2 overlap in the projection direction, and the second height data is characterized as the setting height of the gap between the upper clamping plate layer 1 and the mass block 2.

[0087] S6. The upper clamping layer 1 is set according to the determined overlapping area and the set height of the gap to obtain the low Q value piezoelectric accelerometer.

[0088] The method for preparing the low-Q piezoelectric accelerometer described in this embodiment has the same functional components and beneficial effects as the low-Q piezoelectric accelerometer described in the above embodiments. For details, please refer to the embodiments of the low-Q piezoelectric accelerometer described above. The embodiments of this invention will not be repeated here.

[0089] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0090] Similarly, it should be understood that, in order to streamline this disclosure and aid in understanding one or more of the various inventive aspects, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0091] It should be noted that the above embodiments are illustrative of the invention and not restrictive of the invention, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims.

Claims

1. A low Q-value piezoelectric accelerometer characterized by, The low-Q piezoelectric accelerometer comprises: a base, which is a hollow structure with open upper and lower ends; a moving assembly, which comprises a cantilever assembly and a mass block connected to the cantilever assembly; the cantilever assembly comprises a fixed end and a free end, the fixed end of the cantilever assembly is connected to the base, the free end of the cantilever assembly extends to the inside of the base along the X-axis direction or the Y-axis direction, and the bottom of the free end of the cantilever assembly is connected to the mass block; the mass block can move along the Z-axis direction with the free end of the cantilever assembly as a support point; an upper clamping plate layer, which is connected to the upper end of the base and covers the moving assembly directly above; there is a gap between the upper clamping plate layer and the moving assembly, and the area where the upper clamping plate layer and the moving assembly coincide in the projection direction forms an upper air damping layer; a lower clamping plate layer, which is connected to the bottom of the base by bonding, and there is a gap between the lower clamping plate layer and the mass block; the area where the lower clamping plate layer and the mass block coincide in the projection direction forms a lower air damping layer.

2. The low Q-value piezoelectric accelerometer of claim 1, wherein: The cantilever assembly comprises a piezoelectric composite layer, a cantilever beam and an oxide layer fixedly connected in sequence from top to bottom.

3. The low Q-value piezoelectric accelerometer of claim 1, wherein: The upper clamping plate layer fully covers or partially covers the moving assembly directly above.

4. The low Q-value piezoelectric accelerometer of claim 1, wherein: The upper end and the lower end of the mass block are both flat.

5. The low Q-value piezoelectric accelerometer of claim 1, wherein: A connecting block is arranged at the connection between the mass block and the free end of the cantilever assembly, and the connecting block is generated by thinning the upper end of the mass block through etching.

6. The low Q-value piezoelectric accelerometer of claim 1, wherein: At least two end faces of the upper clamping plate layer are connected to the base.

7. The low Q-value piezoelectric accelerometer of claim 1, wherein: The upper clamping plate layer and the cantilever assembly have the same setting height.

8. The low Q-value piezoelectric accelerometer of claim 1, wherein: The upper clamping plate layer is connected to the top of the base by bonding.

9. The low Q-value piezoelectric accelerometer of claim 1, wherein: The upper end of the upper clamping plate layer is provided with a reinforcing layer.

10. A method for manufacturing a low Q-value piezoelectric accelerometer, applied to the low Q-value piezoelectric accelerometer according to any one of claims 1 to 9, characterized by, The preparation method of the low-Q piezoelectric accelerometer comprises: determining a total damping value based on a target Q value, wherein the total damping value is the sum of an upper air damping value of an upper air damping layer and a lower air damping value of a lower air damping layer; connecting the base, the cantilever assembly, the mass block and the lower clamping plate layer in sequence; obtaining the bottom area of the mass block and the first height data of the lower air damping layer, and obtaining the lower air damping value according to the first height data and the bottom area of the mass block; obtaining the upper air damping value according to the total damping value and the lower air damping value; determining the top effective area of the moving assembly and the second height data of the upper air damping layer according to the upper air damping value, wherein the top effective area of the moving assembly represents the area of the region where the upper clamping plate layer and the mass block coincide in the projection direction, and the second height data represents the setting height of the gap between the upper clamping plate layer and the mass block; setting the upper clamping plate layer according to the determined area of the coinciding region and the setting height of the gap to obtain the low-Q piezoelectric accelerometer.

Images