Pressure sensor, electronic device, and encapsulation method

Abstract

The present application relates to the technical field of sensing, and discloses a pressure sensor, comprising a substrate and a resonant unit, wherein a mounting surface is provided on the substrate, and a cavity is formed inside the substrate. The resonant unit is arranged on the side of the cavity close to the mounting surface, and a gap is formed between the side wall of the resonant unit and the inner wall of the cavity. A sealing gasket is provided on the mounting surface, and the gap is located within the outer contour of the projection of the sealing gasket on the mounting surface. A pressing plate is provided on the side of the sealing gasket facing away from the mounting surface, a pressing head is provided on the side of the pressing plate facing the sealing gasket, and the pressing head extends into the interior of the sealing gasket and is in contact with the resonant unit. The mounting surface is further provided with a conductive element and an encapsulation material. The encapsulation material encapsulates the pressing plate, the sealing gasket, and the conductive element. The pressure sensor provided in the present application comprises an encapsulation structure, which can encapsulate important components in the pressure sensor, and can ensure operational stability of the pressure sensor. The present application further discloses an electronic device and an encapsulation method.

Description

Pressure sensors, electronic devices and packaging methods

[0001] This application claims priority to Chinese Patent Application No. 202510339036.0, filed on March 20, 2025, entitled "Pressure Sensor, Electronic Device and Packaging Method", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of sensing technology, and in particular to a pressure sensor, electronic device, and packaging method. Background Technology

[0003] A pressure sensor is a sensor that can sense and measure pressure and convert it into an electrical signal output. It is widely used in many fields such as railway transportation, intelligent buildings, aerospace, and medical health. MEMS (micro-electro-mechanical system) resonant pressure sensors, with their advantages of small size, high accuracy, good stability, and easy integration, have gradually replaced traditional pressure sensors and have become one of the most widely used and fastest-growing sensors in the world today.

[0004] MEMS resonant pressure sensors measure pressure based on the characteristic that the resonant frequency of a resonant element changes with external pressure. The resonant element can take various forms, such as beams, tuning forks, and diaphragms of various shapes. Furthermore, various excitation and pickup devices can be used to convert frequency changes into easily detectable and processed electrical signals. MEMS resonant pressure sensors offer advantages such as small size, low power consumption, and strong anti-interference capabilities. However, due to the gap between the substrate and the resonant element within the MEMS resonant pressure sensor, traditional packaging techniques can easily affect the sensor's operational stability. Summary of the Invention

[0005] This application provides a pressure sensor, electronic device, and packaging method that can package important components within a MEMS resonant pressure sensor and ensure the operational stability of the MEMS resonant pressure sensor.

[0006] In a first aspect, this application provides a pressure sensor, including a substrate and a resonant unit. The substrate has a mounting surface and a groove inside. The resonant unit is disposed on the side of the groove near the mounting surface, and a gap exists between the sidewall of the resonant unit and the inner wall of the groove. A sealing gasket is provided on the mounting surface, surrounding the resonant unit, with the gap located within the outer contour of the gasket's projection onto the mounting surface. A pressure plate is provided on the side of the sealing gasket facing away from the mounting surface, covering the sealing gasket. A pressure head is provided on the side of the pressure plate facing the sealing gasket, extending into the interior of the sealing gasket and contacting the resonant unit. A conductive element and encapsulating material are also provided on the mounting surface. The conductive element is electrically connected to the resonant unit to transmit the electrical signal output by the resonant unit. The encapsulating material covers the pressure plate, the sealing gasket, and the conductive element.

[0007] When a pressure sensor is working, its resonant element vibrates. When external pressure is applied to the encapsulation material, the material undergoes elastic deformation, transmitting the pressure to the pressure plate. The pressure plate also undergoes elastic deformation under pressure, causing the pressure head to move closer to the resonant element, thus applying pressure to the resonant element. The resonant element's vibration frequency changes after being subjected to pressure. By detecting the change in vibration frequency, the external pressure value experienced by the pressure sensor can be calculated.

[0008] This application utilizes an encapsulation material to encapsulate critical components in a pressure sensor, such as the resonant unit and conductive elements. Simultaneously, by incorporating a sealing gasket and a pressure plate, a cavity is formed between the gasket and the pressure plate, and the resonant unit is placed within this cavity. This isolates the resonant unit from the encapsulation material, preventing interference from the encapsulation material and improving the stability of the pressure sensor. Furthermore, by positioning the gap within the outer contour of the sealing gasket's projection on the mounting surface, liquid encapsulation material is prevented from flowing into the gap between the resonant unit and the inner wall of the tank. This prevents pressure sensor malfunction caused by liquid encapsulation material flowing into the gap, further enhancing the stability of the pressure sensor.

[0009] In some implementations of this application, a cofferdam is also provided on the mounting surface, the cofferdam surrounds the outside of the sealing gasket and the pressure plate, and the encapsulation material wraps around the cofferdam.

[0010] This application utilizes a dike surrounding the sealing gasket and pressure plate to provide rigid structural support for the encapsulation material, thereby protecting the sealing gasket, pressure plate, and resonant unit. Furthermore, the dike facilitates the shaping of the encapsulation material. Specifically, by using a dike, the flow of the encapsulation material is restricted, thus fixing its shape and giving the pressure sensor a flat encapsulation surface, enabling high uniformity during mass production. Additionally, using the dike to fix the shape of the encapsulation material ensures a regular shape of the contact surface between the external pressure and the pressure sensor, which facilitates the calculation of the contact area, thus aiding in the conversion between pressure and intensity in future operations.

[0011] In some implementations of this application, the size of the cofferdam is greater than or equal to the distance between the side of the tablet facing away from the mounting surface and the mounting surface, along a direction perpendicular to the mounting surface. When the liquid encapsulation material is coated, the cofferdam will gather some of the encapsulation material on the top of the tablet (i.e., the side of the tablet facing away from the mounting surface), thereby also encapsulating and protecting the top of the tablet.

[0012] This application does not limit the shape of the pressure head. In some implementations, the area of ​​the cross-sectional area of ​​the pressure head parallel to the mounting surface gradually decreases from the side away from the resonant element to the side closer to the resonant element. In this case, the side of the pressure head facing the resonant element can be either a plane or a curved surface. By gradually decreasing the area of ​​the cross-sectional area of ​​the pressure head parallel to the mounting surface from the side away from the resonant element to the side closer to the resonant element, the contact area between the pressure head and the resonant element can be reduced, the pressure on the resonant element can be increased, and thus the sensitivity of the pressure sensor can be improved.

[0013] In other implementations, the area of ​​the cross-section of the pressure head parallel to the mounting surface remains constant from the side furthest from the resonant element to the side closest to the resonant element. In this case, the side of the pressure head facing the resonant element can be either a plane or a curved surface. For example, the pressure head can be a cuboid. By setting the pressure head as a cuboid, it becomes easier to process, thereby reducing processing difficulty and saving manufacturing costs.

[0014] In some implementations of this application, the ratio of the contact area between the pressure head and the resonant unit to the surface area of ​​the resonant unit facing the pressure head is 20%-100%. Preferably, the ratio of the contact area between the pressure head and the resonant unit to the surface area of ​​the resonant unit facing the pressure head is 30%.

[0015] In some implementations of this application, the tablet is made of a polymer material or a polymer.

[0016] In some implementations of this application, the sealing gasket is made of an elastic polymer, such as rubber, silicone, or flexible resin.

[0017] In some implementations of this application, the encapsulation material is preferably silicone, but it can also be other elastic materials, such as resin.

[0018] In some implementations of this application, the substrate includes a substrate silicon layer, an oxide layer, and a first device silicon layer stacked sequentially along a direction perpendicular to the mounting surface, with the mounting surface located on the first device silicon layer; the resonant unit includes a second device silicon layer and a piezoelectric layer stacked sequentially along a direction perpendicular to the mounting surface, with a plurality of interdigitated electrodes provided on the piezoelectric layer, the second device silicon layer located in the trench, and at least one connection point between the second device silicon layer and the first device silicon layer.

[0019] In some implementations of this application, the conductive element includes an electrode and a jumper wire, with the electrode electrically connected to the resonant unit and the jumper wire connected to the electrode.

[0020] In some implementations of this application, the substrate has multiple grooves inside, and each groove has a resonant unit on the side near the mounting surface. Exemplarily, the resonant units are arranged in an array. There is a gap between the sidewall of each resonant unit and the inner wall of the corresponding groove, and a sealing gasket surrounds the outside of each resonant unit. Each gap is located within the outer contour of the projection of the corresponding sealing gasket on the mounting surface.

[0021] The pressure sensor provided in this application can have its resonant units packaged independently or packaged together in a single process. Specifically, when the spacing between the resonant units is large, each resonant unit can be packaged independently. When the spacing between the resonant units is small, each resonant unit can be packaged together in a single process.

[0022] When each resonant unit is individually packaged, the number of pressure plates is equal to the number of sealing gaskets, and their positions correspond one-to-one. Each pressure plate covers the side of its corresponding sealing gasket facing away from the mounting surface. Each pressure plate has a pressure head on the side facing the sealing gasket, which extends into the interior of its corresponding sealing gasket and contacts the resonant unit inside the gasket. Furthermore, the pressure sensor also includes multiple containment dams, the number of which is equal to the number of sealing gaskets, and their positions correspond one-to-one. Each containment dam surrounds the exterior of its corresponding sealing gasket and pressure plate, and the encapsulation material covers each pressure plate, each sealing gasket, and each containment dam.

[0023] When encapsulating each resonant unit in a single process, a single pressure plate is used. The pressure plate covers the side of each sealing gasket facing away from the mounting surface. Multiple pressure heads are located on the side of the pressure plate facing the sealing gasket, with the number of pressure heads equal to the number of sealing gaskets and their positions corresponding one-to-one. Each pressure head extends into the interior of its corresponding sealing gasket and contacts the resonant unit within that gasket. Furthermore, the pressure sensor also includes a surrounding dam that surrounds the exterior of each sealing gasket and each pressure plate. Encapsulation material covers the pressure plate, the surrounding dam, and each sealing gasket.

[0024] Secondly, this application provides an electronic device, including a body and a pressure sensor as described in the first aspect, the pressure sensor being disposed on the body.

[0025] Thirdly, this application provides a packaging method for packaging a pressure sensor. The pressure sensor includes a substrate and a resonant unit. The substrate has a mounting surface, and a groove is provided inside the substrate. The resonant unit is located on the side of the groove near the mounting surface. A gap exists between the sidewall of the resonant unit and the inner wall of the groove. A conductive element electrically connected to the resonant unit is also provided on the mounting surface. The packaging method provided in this application includes:

[0026] Place a sealing gasket on the mounting surface, so that the sealing gasket surrounds the outside of the resonant unit and the gap is within the outer contour of the projection of the sealing gasket on the mounting surface.

[0027] Place a pressure plate with a pressure head on the side of the sealing gasket away from the mounting surface, so that the pressure head extends into the interior of the sealing gasket and contacts the resonant unit;

[0028] An encapsulation material is applied to the outside of the pressure plate, gasket, and conductive element to encapsulate them.

[0029] In some implementations of this application, before coating the encapsulation material, a dike is provided on the mounting surface such that the dike surrounds the outside of the sealing gasket and the pressure plate. Attached Figure Description

[0030] Figure 1 shows a schematic diagram of a pressure sensor without a packaging structure;

[0031] Figure 2 shows a schematic diagram of the structure of the pressure sensor in some embodiments of this application;

[0032] Figure 3 shows a schematic diagram of the structure of the pressure sensor in some other embodiments of this application;

[0033] Figure 4 shows a schematic diagram of the pressure sensor in Embodiment 1 of this application;

[0034] Figure 5 shows the relationship between the pressure exerted on the resonant unit and the resonant frequency offset of the resonant unit in Embodiment 1 of this application.

[0035] Figure 6 shows a schematic diagram of the pressure sensor in Embodiment 2 of this application;

[0036] Figure 7 shows a schematic diagram of the pressure sensor in Embodiment 3 of this application;

[0037] Figure 8 shows a schematic diagram of the pressure sensor with multiple resonant units provided in this application.

[0038] Figure 9 shows a schematic diagram of the structure of the pressure sensor with multiple resonant units provided in this application. Detailed Implementation

[0039] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0040] This application provides a pressure sensor that can be applied in various fields such as railway transportation, smart buildings, aerospace, healthcare, and robotic sensing. For example, the pressure sensor provided in this application can be used in wearable devices for tension-based blood pressure detection or digital TCM pulse diagnosis, and can also be integrated into wearable devices, robotic haptic devices, etc. The following description uses a MEMS resonant pressure sensor as an example to illustrate this application.

[0041] Figure 1 shows a schematic diagram of the pressure sensor 100a without encapsulation. Referring to Figure 1, the pressure sensor 100a includes a substrate 1a and a resonant unit 2a. The substrate 1a has a mounting surface 11a and a groove 12a inside. The resonant unit 2a is located on the side of the groove 12a closest to the mounting surface 11a, and a gap 3a exists between the sidewall of the resonant unit 2a and the inner wall of the groove 12a. The resonant unit 2a has at least one connection point with the substrate 1a, and the resonant unit 2a is capable of vibrating. A conductive element 6a is also provided on the mounting surface 11a, and the conductive element 6a is electrically connected to the resonant unit 2a to transmit the electrical signal output by the resonant unit 2a.

[0042] The pressure sensor 100a shown in Figure 1 works on the principle of measuring pressure based on the characteristic that the resonant frequency of the resonant unit 2a changes with external pressure. Specifically, when the pressure sensor 100a is working, the resonant unit 2a vibrates. When external pressure is applied to the resonant unit 2a, the vibration frequency of the resonant unit 2a changes. By detecting the change in vibration frequency, the external pressure value experienced by the pressure sensor 100a can be calculated.

[0043] However, in practical applications, critical components of the pressure sensor 100a (such as the resonant unit 2a and the conductive element 6a) are easily damaged. To address the aforementioned problem of the pressure sensor 100a being easily damaged, three alternative implementation methods are provided below, but each also introduces some issues.

[0044] The first optional implementation method uses an adhesive dispensing method. Specifically, adhesive is dispensed onto the mounting surface, encapsulating the resonant unit 2a and the conductive element 6a. Once the adhesive solidifies, it forms an encapsulation structure to protect the resonant unit 2a and the conductive element 6a. However, because the pressure sensor 100a shown in Figure 1 has a gap 3a, the liquid adhesive can easily flow into the gap 3a during dispensing. This can affect the vibration of the resonant unit 2a, causing the pressure sensor 100a to malfunction and affecting its stability.

[0045] In a second alternative implementation, a vacuum encapsulation layer is bonded to the resonant unit 2a, and then the vacuum encapsulation layer is thinned using wet thinning or mechanical thinning methods. The vacuum encapsulation layer is then etched on the front side to protect critical components on the pressure sensor 100a. However, this encapsulation method is complex and costly, and the encapsulation structure is made of relatively rigid borosilicate glass or silicon. Therefore, the encapsulation structure cannot transmit external pressure and is only suitable for non-contact pressure sensors, not contact pressure sensors.

[0046] The third alternative implementation method utilizes low-pressure chemical vapor deposition to achieve vacuum encapsulation based on polycrystalline silicon materials. However, this encapsulation process is highly sensitive to process parameters such as temperature and gas flow rate, is complex, and the encapsulation material is relatively rigid and cannot transmit external pressure. Therefore, this implementation method also leads to increased costs and is only applicable to non-contact pressure sensors.

[0047] In summary, the packaging methods provided in the first, second, and third optional embodiments described above introduce problems such as poor stability of the pressure sensor, high cost, and inapplicability to contact pressure sensors.

[0048] To address the aforementioned issues, this application provides a pressure sensor 100 with an encapsulation structure that encapsulates important components within the pressure sensor 100. This structure is simple, low-cost, does not affect the stability of the pressure sensor 100, and is applicable to contact-type pressure sensors.

[0049] Referring to Figure 2, this application provides a pressure sensor 100, including a substrate 1 and a resonant unit 2. The substrate 1 has a mounting surface 11, and a groove 12 is provided inside the substrate 1. The resonant unit 2 is disposed on the side of the groove 12 near the mounting surface 11, and a gap 3 is provided between the sidewall of the resonant unit 2 and the inner wall of the groove 12. This application does not limit the number of gaps 3. Exemplarily, a gap 3 may be provided only on one side of the resonant unit 2, or gaps 3 may be provided around all four sides of the resonant unit 2. The resonant unit 2 has at least one connection point with the substrate 1, and the resonant unit 2 is capable of vibrating relative to the substrate 1.

[0050] A sealing gasket 41 is provided on the mounting surface 11, and the sealing gasket 41 surrounds the outside of the resonant unit 2. This application does not specifically limit the shape and material of the sealing gasket 41. Exemplarily, the sealing gasket 41 can be annular or a rectangular frame. The material of the sealing gasket 41 is selected to achieve a water seal. Specifically, the sealing gasket 41 can be made of an elastic polymer, such as rubber, silicone, or flexible resin. The gap 3 is located within the outer contour of the projection of the sealing gasket 41 onto the mounting surface 11. Exemplarily, in some embodiments, the gap 3 is covered by the sealing gasket 41, as shown in FIG2. In other embodiments, the gap 3 is located within the surrounding area of ​​the inner ring of the sealing gasket 42, as shown in FIG3.

[0051] Referring to Figure 2, a pressure plate 5 is provided on the side of the sealing gasket 41 facing away from the mounting surface 11, and the pressure plate 5 covers the sealing gasket 41. A pressure head 51 is provided on the side of the pressure plate 5 facing the sealing gasket 41, and the pressure head 51 extends into the interior of the sealing gasket 41 and contacts the resonant unit 2. The pressure plate 5 is made of a relatively flexible material. Under the action of external force, the pressure plate 5 can undergo elastic deformation.

[0052] A conductive element 6 is also provided on the mounting surface 11. The resonant unit 2 is electrically connected to an external circuit through the conductive element 6 to transmit the electrical signal output by the resonant unit 2. Exemplarily, the conductive element 6 may include an electrode 61 and a jumper 62, with the electrode 61 electrically connected to the resonant unit 2 and the jumper 62 connected to the electrode 61.

[0053] Referring to Figure 2, an encapsulation material 7 is also provided on the mounting surface 11. The encapsulation material 7 wraps around the pressure plate 5, the sealing gasket 41, and the conductive element 6. The encapsulation material 7 is liquid before being applied to the pressure sensor 100. When encapsulating the pressure sensor 100, the sealing gasket 41 is first placed on the mounting surface 11, surrounding the resonant unit 2, and covering the gap 3 or surrounding the gap 3. Subsequently, the pressure plate 5 with a pressure head 51 is placed on the sealing gasket 41, covering the side of the sealing gasket 41 away from the resonant unit 2, and the pressure head 51 is in contact with the resonant unit 2. Finally, the liquid encapsulation material 7 is applied to the outside of the pressure plate 5, the sealing gasket 41, and the conductive element 6, thus encapsulating the pressure plate 5, the sealing gasket 41, and the conductive element 6. After the liquid encapsulation material 7 solidifies, an encapsulation structure is formed to encapsulate the pressure sensor 100.

[0054] Furthermore, the encapsulation material 7 is made of a relatively viscous elastic material, which prevents the encapsulation material 7 from seeping into the cavity 9 formed by the sealing gasket 41 and the pressure plate 5 from between the bottom of the sealing gasket 41 and the mounting surface 11, or from between the top of the sealing gasket 41 and the pressure plate 5. For example, the encapsulation material 7 can be silicone or a resin-based material.

[0055] Furthermore, the sealing gasket 41 is adhered to the mounting surface 11 using adhesive, and the pressure plate 5 is adhered to the sealing gasket 41 using adhesive. By using adhesive for bonding, the gaps between the bottom of the sealing gasket 41 and the mounting surface 11, and between the top of the sealing gasket 41 and the pressure plate 5, can be eliminated, thereby further preventing the encapsulation material 7 from seeping into the cavity 9 formed by the sealing gasket 41 and the pressure plate 5.

[0056] Furthermore, the tablet 5 and the pressure head 51 can be an integral structure, both made of polymer materials, such as PMMA (polymethyl methacrylate), PDMS (polydimethylsiloxane), or silicone. The thickness of the tablet 5 can be 20µm-1mm. Preferably, the thickness of the tablet 5 is 100µm-1mm. When it is necessary to make a tablet 5 with a pressure head 51, the material solution of the tablet 5 and the pressure head 51 can be uniformly poured into the photomask. After the material solution solidifies, the tablet 5 with the pressure head 51 can be removed.

[0057] The pressure sensor 100 provided in this application can achieve electrical excitation and detection using the inverse piezoelectric effect and the piezoelectric effect, respectively. When the pressure sensor 100 is working, the resonant unit 2 vibrates. When external pressure is applied to the encapsulation material 7 (as shown by pressure F in Figure 2), the encapsulation material 7 undergoes elastic deformation under the action of external pressure, thereby transmitting the pressure to the pressure plate 5. The pressure plate 5 also undergoes elastic deformation under pressure, causing the pressure head 51 to move towards the side closer to the resonant unit 2 to apply pressure to the resonant unit 2. Exemplarily, the pressure head 51 contacts the central region of the resonant unit 2. The resonant unit 2 bends after being subjected to pressure, and its resonant frequency changes accordingly. By detecting the change in resonant frequency, the external pressure value experienced by the pressure sensor can be calculated.

[0058] The pressure sensor 100 provided in this application has a simple structure and manufacturing process, low cost, and its packaging structure is suitable for contact-type pressure sensors. By using the packaging material 7, important components such as the resonant unit 2 and the conductive element 6 in the pressure sensor 100 can be encapsulated. Simultaneously, by using a sealing gasket 41 and a pressure plate 5, the sealing gasket 41 and the pressure plate 5 form a cavity 9, and the resonant unit 2 is placed within this cavity 9. This isolates the resonant unit 2 from the packaging material 7, preventing the packaging material 7 from interfering with the vibration of the resonant unit 2 and improving the stability of the pressure sensor 100. Furthermore, by placing the gap 3 within the outer contour of the projection of the sealing gasket 41 on the mounting surface 11, i.e., by covering the gap 3 with the sealing gasket 41, or by placing the gap 3 within the enclosing range of the inner ring of the sealing gasket 41, it is possible to prevent the liquid encapsulation material 7 from flowing into the gap 3 between the resonant unit 2 and the inner wall of the tank 12. This can prevent the pressure sensor 100 from malfunctioning due to the liquid encapsulation material 7 flowing into the gap 3, and further improve the stability of the pressure sensor 100.

[0059] This application does not limit the specific structure of the substrate 1. In some embodiments, the substrate 1 includes a substrate silicon layer 14, an oxide layer 15 and a first device silicon layer 16 sequentially stacked along a direction perpendicular to the mounting surface 11, with the mounting surface 11 located on the first device silicon layer 16.

[0060] This application does not limit the specific structure of the resonant unit 2. In some embodiments, the resonant unit 2 includes a second device silicon layer 21 and a piezoelectric layer 22 stacked sequentially along a direction perpendicular to the mounting surface 11. The piezoelectric layer 22 is provided with a plurality of interdigitated electrodes 23, and the second device silicon layer 21 and the first device silicon layer 16 have at least one connection point.

[0061] In some implementations of this application, referring to FIG2, a cofferdam 8 is further provided on the mounting surface 11, surrounding the sealing gasket 41 and the pressure plate 5, and the encapsulation material 7 covers the cofferdam 8. The electrode 61 and jumper 62 can be disposed either outside or inside the cofferdam 8. Along the direction perpendicular to the mounting surface 11, the dimension of the cofferdam 8 (as shown by dimension H1 in FIG2) is greater than or equal to the distance between the side of the pressure plate 5 facing away from the mounting surface 11 and the mounting surface 11 (as shown by dimension H2 in FIG2). The cofferdam 8 is made of a relatively rigid material. Exemplarily, the cofferdam 8 can be made of metal, polyurethane, resin, or silicone.

[0062] When the pressure sensor 100 is coated, liquid encapsulation material 7 is applied to the top of the dam 8. Subsequently, the encapsulation material 7 flows into the interior of the dam 8 through the opening above the dam 8 to encapsulate the sealing gasket 41, the pressure plate 5, and the resonant unit 2.

[0063] Preferably, the size of the cofferdam 8 (as shown by size H1 in Figure 2) is larger than the distance between the side of the pressure plate 5 facing away from the mounting surface 11 and the mounting surface 11 (as shown by size H2 in Figure 2). When the liquid encapsulation material 7 is coated, the cofferdam 8 will gather some of the encapsulation material 7 on the top of the pressure plate 5 (i.e., the side of the pressure plate 5 facing away from the mounting surface 11), thereby also encapsulating and protecting the top of the pressure plate 5.

[0064] This application utilizes a dike 8 surrounding the sealing gasket 41 and the pressure plate 5 to provide rigid structural support for the encapsulation material 7, thereby protecting the sealing gasket 41, the pressure plate 5, and the resonant unit 2. Furthermore, the dike 8 facilitates the shaping of the encapsulation material 7. Specifically, by using the dike 8, the flow of the encapsulation material 7 is restricted, thus fixing its shape and giving the pressure sensor 100 a flat encapsulation surface, enabling high uniformity during mass production. Additionally, using the dike 8 to fix the shape of the encapsulation material 7 ensures a regular shape of the contact surface 71 between the external pressure and the pressure sensor 100, which facilitates the calculation of the contact surface area 71, thus aiding in the conversion between pressure and stress in future operations.

[0065] This application does not limit the shape of the pressure head 51. In some implementations, the area of ​​the cross-section of the pressure head 51 parallel to the mounting surface 11 gradually decreases from the side away from the resonant unit 2 to the side closer to the resonant unit 2. In other implementations, the area of ​​the cross-section of the pressure head 51 parallel to the mounting surface 11 remains constant from the side away from the resonant unit 2 to the side closer to the resonant unit 2. This application also does not limit the shape of the pressure surface 511 of the pressure head 51 (i.e., the side of the pressure head 51 facing the resonant unit 2). In some implementations, the pressure surface 511 of the pressure head 51 can be a plane. In some implementations, the pressure surface 511 of the pressure head 51 can be a curved surface convex towards the resonant unit 2.

[0066] To enable those skilled in the art to better understand the structure of the pressure head 51, the structure of the pressure head 51 is described below through three embodiments.

[0067] Example 1

[0068] Referring to Figure 4, the area of ​​the cross-section of the pressure head 51 parallel to the mounting surface 11 gradually decreases from the side away from the resonant unit 2 to the side closer to the resonant unit 2 (as shown in the X direction in Figure 4), and the pressure surface 511 of the pressure head 51 is planar. Exemplarily, in this embodiment, the shape of the cross-section of the pressure head 51 perpendicular to the mounting surface 11 can be trapezoidal.

[0069] By employing the technical solution described in this embodiment, the area of ​​the pressure surface 511 can be reduced, thereby reducing the contact area between the pressure head 51 and the resonant unit 2, and increasing the pressure experienced by the resonant unit 2. Figure 5 shows the relationship between the pressure experienced by the resonant unit 2 and the resonant frequency shift of the resonant unit 2. As can be seen from Figure 5, the greater the pressure experienced by the resonant unit 2, the greater the resonant frequency shift of the resonant unit 2, and the higher the sensitivity of the pressure sensor 100. Therefore, this embodiment can improve the sensitivity of the pressure sensor 100 by reducing the contact area between the pressure head 51 and the resonant unit 2.

[0070] Example 2

[0071] Referring to Figure 6, the area of ​​the cross-section of the pressure head 51 parallel to the mounting surface 11 gradually decreases from the side away from the resonant unit 2 to the side closer to the resonant unit 2 (as shown in the X direction in Figure 6), and the pressure surface 511 of the pressure head 51 is a spherical surface protruding towards the resonant unit 2. Exemplarily, in this embodiment, the shape of the cross-section of the pressure head 51 perpendicular to the mounting surface 11 can be semi-circular.

[0072] By adopting the technical solution described in this embodiment, by setting the pressure surface 511 of the pressure head 51 to a spherical surface protruding towards the resonant unit 2, the contact area between the pressure head 51 and the resonant unit 2 can be further reduced, thereby further increasing the pressure on the resonant unit 2 and improving the sensitivity of the pressure sensor 100.

[0073] Example 3

[0074] Referring to Figure 7, the area of ​​the cross-section of the pressure head 51 parallel to the mounting surface 11 remains constant from the side away from the resonant unit 2 to the side closer to the resonant unit 2 (as shown in the X direction in Figure 7), and the pressure surface 511 of the pressure head 51 is planar. Exemplarily, in this embodiment, the shape of the cross-section of the pressure head 51 perpendicular to the mounting surface 11 can be rectangular, that is, the shape of the pressure head 51 can be a cuboid. By setting the pressure head 51 as a cuboid, it can be made easier to process, thereby reducing processing difficulty and saving manufacturing costs.

[0075] The above embodiments are a further detailed description of the pressure head 51, and it should not be assumed that the shape of the pressure head 51 is limited to these descriptions. All equivalent implementations or modifications that do not depart from the scope of this application should be included within the scope of this application.

[0076] In this application, the contact area between the pressure head 51 and the resonant unit 2 can be adjusted according to the specific design of the resonant unit 2 to optimize the sensitivity of the pressure sensor 100. Specifically, the ratio of the contact area between the pressure head 51 and the resonant unit 2 to the surface area of ​​the resonant unit 2 facing the pressure head 51 can be 20%-100%. Preferably, the ratio of the contact area between the pressure head 51 and the resonant unit 2 to the surface area of ​​the resonant unit 2 facing the pressure head 51 can be 30%. The applicant has discovered that when the ratio of the contact area between the pressure head 51 and the resonant unit 2 to the surface area of ​​the resonant unit 2 facing the pressure head 51 is 30%, the pressure sensor 100 will have high sensitivity, and the resonant unit 2 will not be damaged due to excessive pressure applied by the pressure head 51.

[0077] In some implementations of this application, referring to FIG8, a plurality of grooves 12 are provided on the base 1, and a resonant unit 2 is provided on the side of each groove 12 near the mounting surface 11. Exemplarily, the resonant units 2 are arranged in an array. There is a gap 3 between the sidewall of each resonant unit 2 and the inner wall of the corresponding groove 12, and a sealing gasket 41 surrounds the outside of each resonant unit 2. Each gap 3 is located within the outer contour of the projection of the corresponding sealing gasket 41 on the mounting surface 11.

[0078] The pressure sensor provided in this application can have each resonant unit 2 individually packaged, or it can have all resonant units 2 packaged together in one go. Specifically, when the spacing between each resonant unit 2 is large, the technical solution shown in Figure 8 can be used to package each resonant unit 2 individually. When the spacing between each resonant unit 2 is small, the technical solution shown in Figure 9 can be used to package each resonant unit 2 together in one go.

[0079] When each resonant unit 2 is individually packaged, referring to Figure 8, the number of pressure plates 5 is equal to the number of sealing gaskets 41 and their positions correspond one-to-one. Each pressure plate 5 covers the side of its corresponding sealing gasket 41 facing away from the mounting surface 11. Each pressure plate 5 has a pressure head 51 on the side facing the sealing gasket 41, which extends into the interior of its corresponding sealing gasket 41 and contacts the resonant unit 2 inside the sealing gasket 41. Furthermore, the pressure sensor also includes multiple dams 8, the number of which is equal to the number of sealing gaskets 41 and their positions correspond one-to-one. Each dam 8 surrounds the exterior of its corresponding sealing gasket 41 and pressure plate 5, and the encapsulation material 7 wraps around each pressure plate 5, each sealing gasket 41, and each dam 8.

[0080] When encapsulating each resonant unit 2 in one go, referring to Figure 9, there is one pressure plate 5. The pressure plate 5 covers the side of each sealing gasket 41 facing away from the mounting surface 11. Multiple pressure heads 51 are provided on the side of the pressure plate 5 facing the sealing gasket 41. The number of pressure heads 51 is equal to the number of sealing gaskets 41, and their positions correspond one-to-one. Each pressure head 51 extends into the interior of its corresponding sealing gasket 41 and contacts the resonant unit 2 inside that sealing gasket 41. Furthermore, the pressure sensor also includes a dam 8, which surrounds the exterior of each sealing gasket 41 and each pressure plate 5. The encapsulation material 7 wraps around the pressure plate 5, the dam 8, and each sealing gasket 41.

[0081] Secondly, this application provides an electronic device, including a main body and any of the pressure sensors 100 described in the foregoing embodiments in conjunction with Figures 2 to 9, wherein the pressure sensor 100 is disposed on the main body. The electronic device provided by this application can be applied to multiple fields such as railway transportation, intelligent buildings, aerospace, and healthcare. For example, the electronic device provided by this application can be a tension-based blood pressure detector or a digital traditional Chinese medicine pulse diagnosis device, or it can be a wearable device or a robotic haptic device.

[0082] Thirdly, this application provides a packaging method for packaging a pressure sensor. The pressure sensor includes a substrate 1 and a resonant unit 2. The substrate 1 has a mounting surface 11, and a groove 12 is provided inside the substrate 1. The resonant unit 2 is disposed on the side of the groove 12 near the mounting surface 11. A gap 3 exists between the sidewall of the resonant unit 2 and the inner wall of the groove 12. A conductive element 6 electrically connected to the resonant unit 2 is also provided on the mounting surface 11. The packaging method provided by this application includes:

[0083] Step S1: Place a sealing gasket 41 on the mounting surface 11, so that the sealing gasket 41 surrounds the outside of the resonant unit 2, and the gap 3 is located within the outer contour of the projection of the sealing gasket 41 on the mounting surface 11.

[0084] Step S2: Place a pressure plate 5 with a pressure head 51 on the side of the sealing gasket 41 facing away from the mounting surface 11, so that the pressure head 51 extends into the interior of the sealing gasket 41 and comes into contact with the resonant unit 2.

[0085] Step S3: Apply encapsulation material 7 to the outside of the pressure plate 5, sealing gasket 41 and conductive element 6 so that the encapsulation material 7 covers the pressure plate 5, sealing gasket 41 and conductive element 6.

[0086] In some implementations of this application, before coating the encapsulation material 7, a dike 8 is provided on the mounting surface 11, such that the dike 8 surrounds the outside of the sealing gasket 41 and the pressure plate 5.

[0087] The specific embodiments described above illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Although the description of this application is presented in conjunction with some embodiments, this does not mean that the features of this application are limited to this embodiment. On the contrary, the purpose of describing the application in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of this application. This application may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of this application, some specific details have been omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0088] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0089] In the embodiments of this application, "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0090] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" should be interpreted broadly. For example, "connection" can be a detachable connection or a non-detachable connection; it can be a direct connection or an indirect connection through an intermediate medium.

[0091] In the description of this application, it should be noted that the terms "upper", "lower", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0092] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "set," "install," "connect," and "fit" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0093] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A pressure sensor, characterized in that, include: A base (1) is provided with a mounting surface (11) and a groove (12) is provided inside the base (1); A resonant unit (2) is disposed on the side of the groove (12) near the mounting surface (11), and there is a gap (3) between the side wall of the resonant unit (2) and the inner wall of the groove (12). Sealing gaskets (41, 42) are disposed on the mounting surface (11), the sealing gaskets (41, 42) surround the outside of the resonant unit (2), and the gap (3) is located within the outer contour of the projection of the sealing gaskets (41, 42) on the mounting surface (11); A pressure plate (5) covers the side of the sealing gasket (41, 42) away from the mounting surface (11). The side of the pressure plate (5) facing the sealing gasket (41, 42) is provided with a pressure head (51). The pressure head (51) extends into the interior of the sealing gasket (41, 42) and contacts the resonant unit (2). A conductive element (6) is disposed on the mounting surface (11), and the conductive element (6) is electrically connected to the resonant unit (2); An encapsulation material (7) is disposed on the mounting surface (11), and the encapsulation material (7) wraps around the outside of the pressure plate (5), the sealing gaskets (41, 42) and the conductive element (6).

2. The pressure sensor according to claim 1, characterized in that, A dam (8) is also provided on the mounting surface (11), the dam (8) surrounds the outside of the sealing gaskets (41, 42) and the pressure plate (5), and the encapsulation material (7) wraps the dam (8); along the direction perpendicular to the mounting surface (11), the size of the dam (8) is greater than or equal to the distance between the side of the pressure plate (5) facing away from the mounting surface (11) and the mounting surface (11).

3. The pressure sensor according to claim 1, characterized in that, The area of ​​the cross section of the pressure head (51) parallel to the mounting surface (11) gradually decreases or remains unchanged from the side away from the resonant unit (2) to the side closer to the resonant unit (2).

4. The pressure sensor according to claim 1, characterized in that, The side of the pressure head (51) facing the resonant unit (2) is a plane; or, the side of the pressure head (51) facing the resonant unit (2) is a curved surface.

5. The pressure sensor according to claim 1, characterized in that, The ratio of the contact area between the pressure head (51) and the resonant unit (2) to the surface area of ​​the resonant unit (2) facing the pressure head (51) is 20%-100%.

6. The pressure sensor according to claim 1, characterized in that, The tablet (5) is made of polymeric material or polymer.

7. The pressure sensor according to claim 1, characterized in that, The sealing gaskets (41, 42) are made of elastic polymers.

8. The pressure sensor according to claim 1, characterized in that, The encapsulation material (7) is silicone or resin.

9. The pressure sensor according to claim 1, characterized in that, The substrate (1) includes a substrate silicon layer (14), an oxide layer (15), and a first device silicon layer (16) stacked sequentially along a direction perpendicular to the mounting surface (11), and the mounting surface (11) is located on the first device silicon layer (16); the resonant unit (2) includes a second device silicon layer (21) and a piezoelectric layer (22) stacked sequentially along a direction perpendicular to the mounting surface (11), the piezoelectric layer (22) is provided with a plurality of interdigitated electrodes (23), and there is at least one connection point between the second device silicon layer (21) and the first device silicon layer (16).

10. The pressure sensor according to claim 1, characterized in that, The conductive element (6) includes an electrode (61) and a jumper (62). The electrode (61) is electrically connected to the resonant unit (2), and the jumper (62) is connected to the electrode (61).

11. The pressure sensor according to any one of claims 1 to 10, characterized in that, The base (1) has a plurality of grooves (12) inside. Each groove (12) has a resonant unit (2) on the side near the mounting surface (11). Each resonant unit (2) has a gap (3) between its sidewall and the inner wall of the corresponding groove (12). Each resonant unit (2) is surrounded by a sealing gasket (41, 42). Each gap (3) is located within the outer contour of the projection of the corresponding sealing gasket (41, 42) on the mounting surface (11).

12. The pressure sensor according to claim 11, characterized in that, The number of pressure plates (5) is equal to the number of sealing gaskets (41, 42) and their positions correspond one-to-one. Each pressure plate (5) covers the side of the sealing gasket (41, 42) opposite to the mounting surface (11) of the corresponding sealing gasket. Each pressure plate (5) has a pressure head (51) on the side facing the sealing gasket (41, 42). The pressure head (51) extends into the interior of the corresponding sealing gasket (41, 42) and contacts the resonant unit (2) inside the sealing gasket (41, 42).

13. The pressure sensor according to claim 12, characterized in that, It also includes multiple cofferdams (8), the number of which is equal to the number of sealing gaskets (41, 42) and their positions correspond one-to-one. Each cofferdam (8) surrounds the exterior of the corresponding sealing gasket (41, 42) and the pressure plate (5). The encapsulation material (7) wraps around each pressure plate (5), each sealing gasket (41, 42) and each cofferdam (8).

14. The pressure sensor according to claim 11, characterized in that, The number of pressure plates (5) is one. The pressure plate (5) covers the side of each of the sealing gaskets (41, 42) away from the mounting surface (11). The side of the pressure plate (5) facing the sealing gaskets (41, 42) is provided with a plurality of pressure heads (51). The number of pressure heads (51) is equal to that of the sealing gaskets (41, 42) and their positions correspond one-to-one. Each pressure head (51) extends into the interior of the corresponding sealing gasket (41, 42) and contacts the resonant unit (2) inside the sealing gasket (41, 42).

15. The pressure sensor according to claim 14, characterized in that, It also includes a dike (8) surrounding the exterior of each of the sealing gaskets (41, 42) and each of the pressure plates (5), and the encapsulation material (7) wraps around the pressure plates (5), the dike (8) and each of the sealing gaskets (41, 42).

16. An electronic device, characterized in that, It includes a main body and a pressure sensor as described in any one of claims 1 to 15, wherein the pressure sensor is disposed on the main body.

17. A packaging method, characterized in that, For encapsulating a pressure sensor, the pressure sensor includes a substrate (1) and a resonant unit (2). The substrate (1) has a mounting surface (11), and the interior of the substrate (1) has a groove (12). The resonant unit (2) is located on the side of the groove (12) near the mounting surface (11). A gap (3) exists between the sidewall of the resonant unit (2) and the inner wall of the groove (12). The mounting surface (11) also has a conductive element (6) electrically connected to the resonant unit (2). The encapsulation method includes: Place sealing gaskets (41, 42) on the mounting surface (11) such that the sealing gaskets (41, 42) surround the outside of the resonant unit (2) and the gap (3) is located within the outer contour of the projection of the sealing gaskets (41, 42) on the mounting surface (11); A pressure plate (5) with a pressure head (51) is placed on the side of the sealing gasket (41, 42) away from the mounting surface (11), so that the pressure head (51) extends into the interior of the sealing gasket (41, 42) and contacts the resonant unit (2); An encapsulation material (7) is coated on the outside of the pressure plate (5), the sealing gaskets (41, 42) and the conductive element (6) so that the encapsulation material (7) wraps the pressure plate (5), the sealing gaskets (41, 42) and the conductive element (6).

18. The packaging method according to claim 17, characterized in that, Before coating the encapsulation material (7), the method further includes: setting a dam (8) on the mounting surface (11) such that the dam (8) surrounds the outside of the sealing gaskets (41, 42) and the pressure plate (5).

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