Piezoelectric sensor

Abstract

The utility model provides a piezoelectric sensor. The piezoelectric sensor comprises a substrate assembly, a mass block and a plurality of piezoelectric structures. The substrate assembly comprises a substrate piece and a cavity, and the cavity is formed in the substrate piece. The mass block is fixedly installed on the substrate piece and contained in the cavity. The plurality of piezoelectric structures are installed on one side, back to the mass block, of the substrate piece at intervals and are symmetrically distributed. According to the piezoelectric sensor provided by the invention, the substrate layer is adopted to replace a separately-arranged cantilever beam in the related technology, the mass block is installed on the substrate layer, and the two substrate blocks can jointly support the same substrate layer under the cooperation of the two substrate blocks, so that the bearing capacity of the substrate layer can be effectively improved. After the bearing capacity of the substrate layer is improved, by increasing the mass of the mass block, the signal-to-noise ratio of the piezoelectric sensor can be improved, and the bandwidth can be effectively expanded. After the mass of the mass block is improved, the substrate layer can avoid increasing the width or thickness of the cantilever beam, and can effectively prevent the substrate layer from being broken due to overweight mass of the mass block.

Description

Technical Field

[0001] The present application belongs to the technical field of piezoelectric devices, and more specifically, to a piezoelectric sensor. Background Art

[0002] Piezoelectric sensors are devices that perform electromechanical conversion based on the piezoelectric effect of piezoelectric materials. They can be used directly to measure force or force-related pressure, displacement, vibration acceleration, etc. Traditional piezoelectric sensors are made of quartz crystals of different cuts or various piezoelectric ceramics such as lead zirconate titanate (PZT). They have the advantages of high sensitivity, stable performance, good frequency response, and reliable operation. However, with the development of micro-electromechanical systems (MEMS) technology, new requirements have been put forward for the size, integrated manufacturing compatibility, manufacturing cost, and environmental friendliness of piezoelectric sensors.

[0003] In the related technical field, due to the low space utilization rate of piezoelectric sensors, their signal-to-noise ratio is low and the bandwidth is narrow. Utility Model Content

[0004] The purpose of the embodiments of the present application is to provide a piezoelectric sensor to solve the technical problems existing in the prior art, such as low space utilization leading to low signal-to-noise ratio and narrow bandwidth.

[0005] To achieve the above purpose, the technical solution adopted in this application is: to provide a piezoelectric sensor, including:

[0006] A substrate assembly, the substrate assembly comprising a substrate member and a cavity, wherein the cavity is opened in the substrate member;

[0007] A mass block, the mass block is fixedly mounted on the substrate and accommodated in the cavity;

[0008] A plurality of piezoelectric structures are installed at intervals on a side of the substrate member facing away from the mass block and are symmetrically distributed.

[0009] Optionally, the substrate member includes a substrate layer and two substrate blocks, the two substrate blocks are arranged on one side of the substrate layer and are respectively located at two ends of the substrate layer; wherein the substrate layer and the two substrate blocks enclose to form the cavity.

[0010] Optionally, the substrate assembly further includes two first insulating layers and a second insulating layer, wherein the first insulating layer is fixedly installed between the substrate layer and the substrate block, and the second insulating layer is fixedly installed between the substrate layer and the mass block.

[0011] Optionally, the distance between one of the substrate blocks and the mass block is equal to the distance between the other substrate block and the mass block.

[0012] Optionally, the distance between one of the substrate blocks and the mass block is greater than the distance between the other substrate block and the mass block.

[0013] Optionally, the substrate layer is provided with two through holes, which are symmetrically distributed along the mass block; one of the through holes is located at one end of the plurality of piezoelectric structures, and the other through hole is located at the other end of the plurality of piezoelectric structures.

[0014] Optionally, the piezoelectric sensor further includes a first packaging component, the first packaging component includes a first packaging layer and two first bonding layers, the two first bonding layers are fixedly installed between the substrate layer and the first packaging layer, and are spaced apart.

[0015] Optionally, the piezoelectric sensor further includes a second packaging component, the second packaging component includes a second packaging layer and two second bonding layers, and the second bonding layer is fixedly installed between the substrate block and the second packaging layer.

[0016] Optionally, one end of the mass block facing the second packaging layer has a plurality of protrusions.

[0017] Optionally, the piezoelectric sensor further includes a pad, and the pad is fixedly mounted on the surface of the substrate layer.

[0018] The beneficial effects of the piezoelectric sensor provided by the present application are:

[0019] The piezoelectric sensor provided by the present application adopts a substrate layer to replace the cantilever beam separated in the related art, and adopts a substrate layer to install a mass block. With the cooperation of two substrate blocks, the two substrate blocks can jointly support the same substrate layer, which can effectively improve the bearing capacity of the substrate layer. After improving the bearing capacity of the substrate layer, by increasing the mass of the mass block, the signal-to-noise ratio of the piezoelectric sensor can be effectively improved, and the bandwidth can also be effectively expanded. After improving the mass of the mass block, the substrate layer can avoid increasing the width or thickness of the cantilever beam, and can effectively prevent the substrate layer from breaking due to the excessive mass of the mass block. In addition, the two substrate blocks can be enclosed with the substrate layer to form a cavity, which is convenient for installing the mass block and helps to improve the convenience of use. The cavity is used to facilitate the vibration of the mass block, and can provide space for the vibration of the mass block, which helps to further improve the convenience of use. In addition, the symmetrical arrangement of multiple piezoelectric structures can ensure the consistency of the signal, and it is convenient to connect multiple piezoelectric structures in series or in parallel, which helps to further improve the convenience of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 A front view of the piezoelectric sensor provided in Example 1 of the present application;

[0022] Figure 2 A partial top view of the piezoelectric sensor provided in Example 1 of the present application;

[0023] Figure 3 This is a front view of the piezoelectric sensor provided in Example 2 of the present application.

[0024] Among them, the reference numerals in the figure are:

[0025] 100, substrate assembly; 110, substrate member; 111, substrate layer; 112, substrate block; 113, through hole; 120, cavity; 130, first insulating layer; 140, second insulating layer;

[0026] 200, mass block; 210, protrusion;

[0027] 300, piezoelectric structure;

[0028] 400, first packaging component; 410, first packaging layer; 420, first bonding layer;

[0029] 500, second packaging component; 510, second packaging layer; 520, second bonding layer;

[0030] 600. Solder pad. DETAILED DESCRIPTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0032] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0033] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0034] 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0035] Based on this, the present invention provides a piezoelectric sensor, which can effectively improve space utilization, thereby improving the signal-to-noise ratio and effectively expanding the bandwidth.

[0036] Embodiment 1

[0037] like Figure 1 As shown, an embodiment of the present application provides a piezoelectric sensor, including a substrate assembly 100, a mass block 200 and a plurality of piezoelectric structures 300. The substrate assembly 100 includes a substrate member 110 and a cavity 120, and the cavity 120 is opened in the substrate member 110. The mass block 200 is fixedly mounted on the substrate member 110 and accommodated in the cavity 120. A plurality of piezoelectric structures 300 are installed at intervals on the side of the substrate member 110 facing away from the mass block 200, and are symmetrically distributed. The substrate member 110 includes a substrate layer 111 and two substrate blocks 112, and the two substrate blocks 112 are arranged on one side of the substrate layer 111, and are respectively located at both ends of the substrate layer 111. Among them, the substrate layer 111 and the two substrate blocks 112 enclose a cavity 120.

[0038] It should be noted that in this embodiment, the number of piezoelectric structures 300 is set to four as an example. Of course, in other embodiments, according to actual application requirements, the number of piezoelectric structures 300 can also be set to other numbers, which is not limited here.

[0039] Specifically, in this embodiment, a piezoelectric sensor is used to detect vibration acceleration as an example for explanation. When the piezoelectric sensor is fixed on the object to be measured, when the piezoelectric sensor receives external vibration, the external exciting force will drive the mass block 200 to have forced vibration along the thickness direction, that is, forced vibration is generated in the acceleration direction. The substrate member 110 is strained and generates stress under the action of the mass block 200, and an electric charge is generated on the surface of the piezoelectric structure 300 through the positive piezoelectric effect to detect the vibration acceleration of the object to be measured. It should be noted here that the thickness direction refers to the bidirectional direction of the shortest connection line between the two side surfaces of the substrate layer 111, specifically Figure 1 The X-axis direction is shown in .

[0040] More specifically, the following formula is derived:

[0041]

[0042] Where f0 is the no-load resonant frequency; SNR is the signal-to-noise ratio; d 31 is the piezoelectric strain constant perpendicular to the polarization direction and stress direction; ε r is the relative dielectric constant; ε0 is the vacuum dielectric constant; tan δ is the tangent value of the dielectric loss angle; and m is the mass. Therefore, in order to obtain a higher signal-to-noise ratio, the present application improves the signal-to-noise ratio by increasing the mass of the mass block 200.

[0043] In the related art, the mass block 200 is usually mounted on the cantilever beam of the substrate. Since the cantilever beam is usually set as a slender structure and is set separately, the weight of the mass block 200 is increased, and the cantilever beam of the substrate is prone to breakage due to insufficient rigidity. Increasing the width or thickness of the cantilever beam will increase the rigidity of the cantilever beam, thereby reducing the deformation of the piezoelectric structure 300, and ultimately causing the sensitivity of the piezoelectric sensor to decrease.

[0044] The piezoelectric sensor provided in the embodiment of the present application adopts a substrate layer 111 to replace the cantilever beam separately arranged in the related art, and adopts the substrate layer 111 to install the mass block 200. With the cooperation of the two substrate blocks 112, the two substrate blocks 112 can jointly support the same substrate layer 111, which can effectively improve the bearing capacity of the substrate layer 111. After improving the bearing capacity of the substrate layer 111, by increasing the mass of the mass block 200, the signal-to-noise ratio of the piezoelectric sensor can be effectively improved, and the bandwidth can also be effectively expanded. After improving the mass of the mass block 200, the substrate layer 111 can be used to avoid increasing the width or thickness of the cantilever beam, and can effectively prevent the substrate layer 111 from breaking due to the excessive mass of the mass block 200. In addition, the two substrate blocks 112 can be enclosed with the substrate layer 111 to form a cavity 120, which is convenient for installing the mass block 200 and helps to improve the convenience of use. The cavity 120 is used to facilitate the vibration of the mass block 200, and can provide space for the vibration of the mass block 200, which helps to further improve the convenience of use. In addition, the symmetrical arrangement of the multiple piezoelectric structures 300 can ensure signal consistency and facilitate the series or parallel connection of the multiple piezoelectric structures 300, which helps to further improve the convenience of use.

[0045] It should be noted that in this embodiment, the substrate layer 111 and the substrate block 112 are both made of silicon material. Of course, in other embodiments, according to actual application requirements, the substrate layer 111 and the substrate block 112 can also be made of glass or other materials, which is not limited here.

[0046] It should also be noted that in this embodiment, the first insulating layer 130 and the second insulating layer 140 are both made of silicon oxide material. Of course, in other embodiments, according to actual application requirements, the first insulating layer 130 and the second insulating layer 140 can also be made of other materials, which is not limited here.

[0047] Optionally, the piezoelectric structure 300 is configured to be aluminum nitride (AlN), aluminum scandium nitride (AlScN), lead zirconate titanate (PZT), zinc oxide (ZnO), or the like.

[0048] In one embodiment of the present application, see Figure 1 The substrate assembly 100 further includes two first insulating layers 130 and a second insulating layer 140 . The first insulating layer 130 is fixedly installed between the substrate layer 111 and the substrate block 112 , and the second insulating layer 140 is fixedly installed between the substrate layer 111 and the mass block 200 .

[0049] In this configuration, the first insulating layer 130 and the second insulating layer 140 are isolation layers used for insulation and deep silicon etching stops.

[0050] Optionally, the first insulating layer 130 and the second insulating layer 140 are silicon oxide.

[0051] In one embodiment of the present application, please refer to Figure 1 , wherein the distance between one substrate block 112 and the mass block 200 is equal to the distance between the other substrate block 112 and the mass block 200 .

[0052] In this configuration, since the distance between one substrate block 112 and the mass block 200 is equal to the distance between the other substrate block 112 and the mass block 200, the mass block 200, the plurality of piezoelectric structures 300, the substrate layer 111, the two substrate blocks 112, the two first insulating layers 130 and the second insulating layer 140 can form a symmetrical structure, which can effectively improve the anti-shock characteristics of the sensor, increase reliability and structural stability. In addition, the detection of biaxial vibration acceleration can also be realized.

[0053] In one embodiment of the present application, see Figure 1 and Figure 2 The substrate layer 111 is provided with two through holes 113, which are symmetrically distributed along the mass block 200. One of the through holes 113 is located at one end of the plurality of piezoelectric structures 300, and the other through hole 113 is located at the other end of the plurality of piezoelectric structures 300.

[0054] In this configuration, by opening two through holes 113 on the substrate layer 111 , the mass block 200 is facilitated to vibrate. Furthermore, after the mass block 200 vibrates, the substrate layer 111 is facilitated to transmit the vibration of the mass block 200 to the plurality of piezoelectric structures 300 .

[0055] In one embodiment of the present application, see Figure 1 The piezoelectric sensor further includes a first packaging component 400, which includes a first packaging layer 410 and two first bonding layers 420. The two first bonding layers 420 are fixedly installed between the substrate layer 111 and the first packaging layer 410 and are arranged at intervals. The piezoelectric sensor further includes a second packaging component 500, which includes a second packaging layer 510 and two second bonding layers 520. The second bonding layer 520 is fixedly installed between the substrate block 112 and the second packaging layer 510.

[0056] In this configuration, two first bonding layers 420 are used to bond the first packaging layer 410 to the substrate layer 111, and the first packaging layer 410 is prevented from contacting the plurality of piezoelectric structures 300, thereby preventing the first packaging layer 410 from affecting the piezoelectric effect of the plurality of piezoelectric structures 300. The first packaging layer 410 is used to package the substrate layer 111 from the side of the substrate layer 111 facing away from the substrate block 112, thereby effectively protecting the plurality of piezoelectric structures 300 and the substrate layer 111, thereby preventing the external environment from causing impact on the plurality of piezoelectric structures 300 and the substrate layer 111, thereby preventing the plurality of piezoelectric structures 300 and the substrate layer 111 from being damaged. The two second bonding layers 520 are used to bond the second packaging layer 510 to the substrate block 112, and the second packaging layer 510 is prevented from contacting the mass block 200, thereby preventing the second packaging layer 510 from interfering with the movement of the mass block 200. By using the second packaging layer 510, the substrate block 112 can be packaged from the side facing away from the substrate layer 111, which can effectively protect the substrate layer 111 and the mass block 200, prevent the external environment from causing impact on the mass block 200 and the substrate layer 111, and further prevent the mass block 200 and the substrate layer 111 from being damaged.

[0057] Optionally, the first bonding layer 420 and the second bonding layer 520 are configured to be a gold-tin alloy, an aluminum-germanium alloy, an organic substance, etc.

[0058] In one embodiment of the present application, see Figure 1 The mass block 200 has a plurality of protrusions 210 at one end facing the second packaging layer 510 .

[0059] It should be noted that in this embodiment, the number of protrusions 210 is set to three as an example. Of course, in other embodiments, according to actual application requirements, the number of protrusions 210 can also be set to two, four, five... other numbers, which are not limited here.

[0060] It should also be noted that in this embodiment, the cross-sectional shape of the protrusion 210 is set to a triangle as an example for description. Of course, in other embodiments, according to actual application requirements, the cross-sectional shape of the protrusion 210 can also be set to other shapes such as arcs and polygons, which are not limited here.

[0061] In this way, the use of multiple protrusions 210 can prevent the mass block 200 from directly contacting the second packaging layer 510, thereby preventing the mass block 200 from adhering to the second packaging layer 510 under the action of external impact force. In addition, the cross-section of the multiple protrusions 210 is set to be triangular, so the contact area between the protrusions 210 and the second packaging layer 510 can be reduced, thereby preventing the protrusions 210 from adhering to the second packaging layer 510.

[0062] In one embodiment of the present application, see Figure 1 The piezoelectric sensor also includes a pad 600 , which is fixedly mounted on the surface of the substrate layer 111 .

[0063] Such arrangement and the use of the solder pad 600 facilitate signal extraction, thus helping to improve ease of use.

[0064] Embodiment 2

[0065] This embodiment is basically the same as the first embodiment, and the difference is only that: Figure 3 As shown, the distance between one substrate block 112 and the proof mass 200 is greater than the distance between the other substrate block 112 and the proof mass 200 .

[0066] In such a configuration, since the distance between one substrate block 112 and the mass block 200 is greater than the distance between the other substrate block 112 and the mass block 200, the mass block 200, the multiple piezoelectric structures 300, the substrate layer 111, the two substrate blocks 112, the two first insulating layers 130 and the second insulating layer 140 can form an asymmetric structure. The sensor has two adjacent resonance peaks that restrict each other, thereby preventing an excessively high first-order resonance peak, and thus being able to expand the bandwidth.

[0067] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A piezoelectric sensor, characterized in that: include: A substrate assembly (100), the substrate assembly (100) comprising a substrate member (110) and a cavity (120), the cavity (120) being opened in the substrate member (110); A mass block (200), the mass block (200) being fixedly mounted on the substrate member (110) and accommodated in the cavity (120); A plurality of piezoelectric structures (300) are installed at intervals on a side of the substrate (110) facing away from the mass block (200) and are symmetrically distributed.

2. The piezoelectric sensor according to claim 1, wherein: The substrate member (110) comprises a substrate layer (111) and two substrate blocks (112), wherein the two substrate blocks (112) are arranged on one side of the substrate layer (111) and are respectively located at two ends of the substrate layer (111); wherein the substrate layer (111) and the two substrate blocks (112) enclose to form the cavity (120).

3. The piezoelectric sensor according to claim 2, characterized in that: The substrate assembly (100) further comprises two first insulating layers (130) and a second insulating layer (140), wherein the first insulating layer (130) is fixedly installed between the substrate layer (111) and the substrate block (112), and the second insulating layer (140) is fixedly installed between the substrate layer (111) and the mass block (200).

4. The piezoelectric sensor according to claim 2, wherein: The distance between one of the substrate blocks (112) and the mass block (200) is equal to the distance between the other substrate block (112) and the mass block (200).

5. The piezoelectric sensor according to claim 2, wherein: The distance between one of the substrate blocks (112) and the mass block (200) is greater than the distance between the other substrate block (112) and the mass block (200).

6. The piezoelectric sensor according to claim 2, wherein: The substrate layer (111) is provided with two through holes (113), and the two through holes (113) are symmetrically distributed along the mass block (200); one of the through holes (113) is located at one end of the plurality of piezoelectric structures (300), and the other through hole (113) is located at the other end of the plurality of piezoelectric structures (300).

7. The piezoelectric sensor according to any one of claims 2 to 6, characterized in that: The piezoelectric sensor further comprises a first packaging component (400), wherein the first packaging component (400) comprises a first packaging layer (410) and two first bonding layers (420), wherein the two first bonding layers (420) are fixedly installed between the substrate layer (111) and the first packaging layer (410) and are arranged at intervals.

8. The piezoelectric sensor according to any one of claims 2 to 6, characterized in that: The piezoelectric sensor further comprises a second packaging component (500), wherein the second packaging component (500) comprises a second packaging layer (510) and two second bonding layers (520), wherein the second bonding layer (520) is fixedly installed between the substrate block (112) and the second packaging layer (510).

9. The piezoelectric sensor according to claim 8, characterized in that: One end of the mass block (200) facing the second packaging layer (510) has a plurality of protrusions (210).

10. The piezoelectric sensor according to any one of claims 2 to 6, characterized in that: The piezoelectric sensor further comprises a pad (600), and the pad (600) is fixedly mounted on the surface of the substrate layer (111).

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