A pressure sensor core package structure

Abstract

This utility model discloses a pressure sensor core packaging structure, comprising a base, a patch assembly, a filling structure, a strain gauge, and a pressure plate. The base has a receiving cavity, an opening, and an oil filling hole. The opening communicates with the receiving cavity, and the oil inlet end of the oil filling hole is positioned close to the opening. The patch assembly and the filling structure are both housed within the receiving cavity. After the patch assembly is placed at the bottom of the receiving cavity, the filling structure fills the receiving cavity. The strain gauge and the pressure plate are sequentially fixed to the opening of the base, with the strain gauge located between the base and the pressure plate. The strain gauge and / or the pressure plate are sealed to the base. A gap exists between the strain gauge and the filling structure, and this gap is configured to be filled with oil through the oil filling hole, which is then sealed after being filled with oil. A detection port is provided on the pressure plate. This patent employs a unique core packaging structure, improving the application flexibility of oil-filled packaged pressure sensor products.

Description

Technical Field

[0001] This utility model relates to the field of chip packaging, and in particular to a pressure sensor core packaging structure. Background Technology

[0002] For pressure measurement in harsh environments, oil-filled encapsulation is often used to ensure long-term reliability. This means that the pressure sensor chip is protected by oil and a stainless steel sheet. The chip does not directly contact the measured medium, but rather senses pressure changes indirectly through the stainless steel sheet.

[0003] Commercially available oil-filled pressure sensors involve attaching the sensor chip to the metal substrate of the sensor base (i.e., the bottom of the TO tube socket), then electrically connecting the sensor chip and the metal pins of the TO tube socket via wire bonding, followed by soldering and oil filling. This method is difficult to automate, resulting in low production efficiency and product yield. Furthermore, this method makes it difficult to integrate the IC chip or even application circuitry into the oil-filled cavity, leading to low integration levels. Subsequent addition of external circuitry for compensation and calibration further increases costs and contradicts the trend towards miniaturization and integration.

[0004] With the increasing demand for intelligent social development, pressure sensors are finding wider and wider applications and are in greater demand. The demand for oil-filled pressure sensors is also growing, but their high cost limits their application development.

[0005] Therefore, considering the aforementioned technical problems, it is necessary to propose a new technical solution. Summary of the Invention

[0006] To address at least one of the technical problems existing in the prior art, this utility model adopts a unique core packaging structure, improving the application flexibility of oil-filled pressure sensor products. It allows for sealing and matching with various interfaces by replacing sealing heads of different shapes or sizes. By combining a mature, highly automated packaging method with traditional oil-filled packaging, automated mass production can be achieved, improving production efficiency and yield, and reducing production and operating costs. The specific technical solution is as follows: This utility model provides a pressure sensor core packaging structure, which includes a base, a patch assembly, a filling structure, a strain gauge, and an upper pressure component; The base has a receiving cavity, an opening, and an oil filling hole. The opening is connected to the receiving cavity. The oil inlet end of the oil filling hole is positioned close to the opening. The patch assembly and the filling structure are both housed in the receiving cavity. After the patch assembly is housed at the bottom of the receiving cavity, the filling structure fills the receiving cavity. The strain gauge and the upper pressure member are fixed sequentially on the opening of the base. The strain gauge is located between the base and the upper pressure member. The strain gauge and / or the upper pressure member are sealed to the base. There is a gap between the strain gauge and the filling structure. The gap is configured to be filled with oil through the oil filling hole. The oil filling hole is configured to be sealed after filling the gap with oil. The upper pressure component has an inspection port.

[0007] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, the patch assembly includes a circuit board and a pressure sensor, with the pressure sensor and the circuit board integrated in a packaged sheet assembled in a receiving cavity; or the pressure sensor's packaged sheet is mounted or soldered onto the circuit board, and the patch assembly is housed entirely in a receiving cavity.

[0008] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, the circuit board also integrates one or more of the following: a temperature sensor, a humidity sensor, an acceleration sensor, and application circuit components.

[0009] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, the upper pressure component is a pressure ring, a pressure cap, a threaded cap, or an insert-type seal. A pressure ring or pressure cap is provided on the opening of the base; or The threaded cap is used to seal the opening in the base; or Insert-type seals are installed on the opening of the base.

[0010] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, a gap groove is also provided on the base. The gap groove is located at one end of the accommodating cavity near the opening. The gap groove is configured to allow a gap between the strain gauge and the filling structure. The oil inlet end of the oil filling hole is located on the bottom wall or side wall of the gap groove.

[0011] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, a pin is also fixedly provided on the base. One end of the pin extends into the accommodating cavity and is electrically connected to the circuit board, while the other end of the pin extends out of the accommodating cavity.

[0012] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, a connection port is provided on the surface of the base, and a connector or wire is mounted or soldered on the circuit board. The connector or wire passes through the connection port and extends out of the receiving cavity.

[0013] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, the base is an integral base; The base includes a base body and a mounting body, wherein a pin is provided through the mounting body, and the mounting body is integrally connected to the base body; and / or The base is a steel ring.

[0014] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, the base is a split base; The base includes a base body and a mounting body. A guide pin is provided through the mounting body, and the mounting body is sealed and installed on the base body.

[0015] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, a stop ring is also provided at the end of the base body away from the opening. The outer diameter of the mounting body is larger than the inner diameter of the stop ring. The mounting body is installed into the receiving cavity from the opening, and the mounting body abuts against and seals against the stop ring.

[0016] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, an annular groove is provided on the surface of the base or the surface of the upper pressure component, and an annular sealing ring is placed inside the annular groove.

[0017] As a preferred embodiment of the pressure sensor core packaging structure described in this utility model, a gap groove is also provided on the base, and the gap groove is located at one end of the accommodating cavity near the opening, and the gap groove is located between the filling structure and the strain gauge.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects: Employing a unique core packaging structure enhances the application flexibility of oil-filled pressure sensors, allowing for seamless sealing with various interfaces by replacing sealing heads of different shapes or sizes. Combining industry-leading, highly automated packaging methods with traditional oil-filled packaging improves production efficiency and yield, while reducing production and operating costs. Internal components are manufactured using mature processes, enabling automated mass production, further lowering the cost of oil-filled pressure sensors and expanding their application scenarios.

[0019] This patent introduces surface mount components, which are inexpensive and can be mass-produced automatically, greatly reducing costs and improving labor efficiency. Surface mount modules increase integration, allowing multiple sensors and external circuits to be integrated onto a single circuit board. This enables the sensor core to measure not only pressure but also other physical quantities such as temperature. Furthermore, no additional external circuitry is required, reducing costs and size, aligning with the trend towards miniaturization.

[0020] The surface mount assembly includes a circuit board and components. The circuit board carries the components, which can support not only pressure sensors, but also other sensors or other circuit elements, forming a complete system and improving integration.

[0021] A strain gauge is a sensitive diaphragm that comes into direct contact with the medium being tested through a detection port. The pressure of the medium causes the strain gauge to deform, thereby measuring the pressure value of the medium being tested.

[0022] The upper pressure component and the base together clamp the strain gauge in the middle and are welded into a whole, serving to fix the sensitive membrane strain gauge. The weld of the upper pressure component, strain gauge, and base is a ring weld seal, which is leak-free. The gland or pressure ring is used to tightly clamp the strain gauge together with the base to form a whole. Threaded caps or insert seals also serve to install, fix, and seal. The core with threaded caps or insert seals can be directly installed and used without the need for a separate outer shell.

[0023] The filling structure within the accommodating cavity occupies space, effectively reducing the amount of oil injected. In the example, after the upper pressure component is set or the sealing welding is completed, the oil filling operation is performed. Oil is injected through the oil filling hole, and after filling, the oil filling hole is sealed by welding.

[0024] When the base is a steel ring, the surface mount assembly is attached to the bottom of the inner cavity of the steel ring using, for example, sealant. Because the steel ring is open at both ends, the pads on the back of the circuit board in the surface mount module are exposed, allowing for circuit routing operations such as wire bonding, connectors, or wires to be made on the exposed back of the circuit board. The use of connectors or wires reduces the need for pins and eliminates the need for a pin sintering step, thus significantly reducing costs.

[0025] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] To more clearly illustrate the technical solution of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is an exploded structural diagram of one embodiment of the pressure sensor core packaging structure described in this utility model; Figure 2 This is a three-dimensional structural diagram of one embodiment of the pressure sensor core packaging structure described in this utility model; Figure 3This is an exploded structural diagram of another embodiment of the pressure sensor core packaging structure described in this utility model; Figure 4 This is a three-dimensional structural diagram of another embodiment of the pressure sensor core packaging structure described in this utility model; Figure 5 This is an exploded structural diagram of another embodiment of the pressure sensor core packaging structure described in this utility model; Figure 6 This is an exploded structural diagram of another embodiment of the pressure sensor core packaging structure described in this utility model; Figure 7 This is a three-dimensional structural diagram of another embodiment of the pressure sensor core packaging structure described in this utility model; Figure 8 This is a three-dimensional structural schematic diagram of another embodiment of the pressure sensor core packaging structure described in this utility model; Figure 9 This is a three-dimensional structural diagram of another embodiment of the pressure sensor core packaging structure described in this utility model; Figure 10 This is a three-dimensional structural schematic diagram of one embodiment of the integrated base described in this utility model; Figure 11 This is a three-dimensional structural schematic diagram of another embodiment of the integrated base described in this utility model; Figure 12 This is an exploded structural diagram of one embodiment of the split base described in this utility model; Figure 13 This is an exploded structural diagram of another embodiment of the split base described in this utility model; Figure 14 This is an exploded structural diagram of another embodiment of the split base described in this utility model; Figure 15 This is an exploded structural diagram of another embodiment of the split base described in this utility model.

[0028] Among them, 1-base, 2-patch assembly, 3-filling structure, 4-strain gauge, 5-upper pressure member, 101-base body, 102-mount body, 11-accommodating cavity, 12-opening, 13-oil filling hole, 14-lead pin, 15-connection port, 16-annular groove, 17-annular sealing ring, 18-gap groove, 19-stop ring, 21-circuit board, 211-connector, 22-pressure sensor, 51-detection port, 52-pressure ring, 53-pressure cap, 54-threaded cap, 55-insertion seal. Detailed Implementation

[0029] The embodiments of this utility model are described in detail below, providing a comprehensive overview and complete description of their technical solutions. It is clear that the described embodiments are merely a portion, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model.

[0030] Please see Figures 1-13 ,like Figure 1-13 As shown, this utility model provides a pressure sensor core packaging structure, including a base 1, a patch assembly 2, a filling structure 3, a strain gauge 4, and an upper pressure component 5; The base 1 has a receiving cavity 11, an opening 12, and an oil filling hole 13. The opening 12 is connected to the receiving cavity 11. The oil inlet end of the oil filling hole 13 is close to the opening 12. The patch assembly 2 and the filling structure 3 are both housed in the receiving cavity 11. After the patch assembly 2 is housed at the bottom of the receiving cavity 11, the filling structure 3 fills the receiving cavity 11. The strain gauge 4 and the upper pressure member 5 are fixed on the opening 12 of the base 1 in sequence. The strain gauge 4 is located between the base 1 and the upper pressure member 5. The strain gauge 4 and / or the upper pressure member 5 are sealed to the base. There is a gap between the strain gauge 4 and the filling structure 3. The gap is configured to be filled with oil through the oil filling hole 13. The oil filling hole 13 is configured to be sealed after filling the gap with oil. The upper pressure component 5 has a detection port 51.

[0031] This patent introduces surface mount components, which are inexpensive and can be mass-produced automatically, greatly reducing costs and improving labor efficiency. Surface mount modules increase integration, allowing multiple sensors and external circuits to be integrated onto a single circuit board. This enables the sensor core to measure not only pressure but also other physical quantities such as temperature. Furthermore, no additional external circuitry is required, reducing costs and size, aligning with the trend towards miniaturization.

[0032] In the example, strain gauge 4 is a sensitive diaphragm. The strain gauge is in direct contact with the medium being tested through the detection port. The pressure of the medium being tested causes the strain gauge to deform, thereby measuring the pressure value of the medium being tested.

[0033] In a preferred embodiment, such as Figure 1 , Figure 3 and Figure 5-6 As shown, the patch assembly 2 includes a circuit board 21 and a pressure sensor 22. The pressure sensor 22 and the circuit board 21 are integrated into a package and assembled in a receiving cavity; or the package of the pressure sensor 22 is mounted or soldered onto the circuit board 21. In this example, the pressure sensor 22 is a pressure sensor package, which is mounted on the circuit board 21, and then the entire patch assembly is housed in the receiving cavity.

[0034] Further preferably, the circuit board 21 also integrates one or more of the following: a temperature sensor, a humidity sensor, an acceleration sensor, and application circuit components. Of course, this patent is not limited to this, and other sensors may also be used. The patch assembly includes a circuit board and components. The circuit board carries the components, which can not only carry pressure sensors, but also other sensors or other circuit elements, forming a complete system and improving the integration level.

[0035] In a preferred embodiment, the upper pressure member 5 includes, but is not limited to, a pressure ring 52, a pressure cap 53, a threaded cap 54, or an insert seal 55, etc., to seal and / or fix the strain gauge. One example is... Figure 1-5 As shown, the upper pressure member 5 is a pressure ring 52 or a pressure cap 53, which is disposed on the opening 12 of the base 1 to clamp the strain gauge 4 and form the core as a whole. One example is... Figure 7-8 As shown, the upper pressure member 5 is a threaded cap 54, which is sealed to the opening 12 of the base 1. In this example, the threaded cap 54 is welded to the opening 12 of the base 1. In this example, the threaded cap 54 has a threaded head on the side away from the base, which can be screwed onto other components. One example is... Figure 9 As shown, the upper pressure member 5 is an insert-type seal 55, which is sealed and installed on the opening 12 of the base 1. In the example, the insert-type seal 55 is welded to the opening 12 of the base 1. In the example, a plug-in fixing structure is provided on the side of the insert-type seal 55 away from the base, which can be plugged into other components. The upper pressure member and the base together clamp the strain gauge in the middle and are welded into a whole, which serves to fix the sensitive membrane strain gauge. The welding of the upper pressure member, strain gauge and base is a ring weld seal, which is leak-free. The gland or pressure ring is used to tightly clamp the strain gauge together with the base to form a whole. The threaded cap or insert-type seal can also serve to install, fix and seal. The core of the threaded cap or insert-type seal can be directly installed and used without assembling the outer shell.

[0036] Preferred examples, such as Figure 1 , Figure 3 and Figure 5-6 As shown, a gap groove 18 is also provided on the base 1. The gap groove 18 is located at the end of the accommodating cavity near the opening 12, and is located between the strain gauge 4 and the filling structure 3. In this example, the oil filling hole 13 is provided at the bottom of the gap groove 18. The gap groove facilitates the setting of the oil filling hole and also allows for direct observation of the filling status of the filling structure, avoiding excessive filling of the filling structure that may compress the strain gauge or occupy the gap space.

[0037] In preferred examples, such as Figure 1 , Figure 3 , Figure 5-6 and Figure 10-13 As shown, the oil inlet end of the oil filling hole is located inside the base, and the oil filling end is located on the surface of the base. The oil filling hole 13 is configured to allow oil to be filled into the receiving cavity 11, and the oil filling hole is then welded and sealed after being filled with oil. The filling structure inside the receiving cavity occupies the space of the receiving cavity, effectively reducing the amount of oil injected. In this example, after the upper pressure component is sealed and welded, an oil filling operation is performed. Oil is injected from the oil filling hole, and after filling, the oil filling hole is sealed and welded. In this example, the oil filling end of the oil filling hole is located at the bottom of the base. In this example, the oil filling hole 13 is located at the bottom of the gap groove 18.

[0038] Preferred, such as Figure 1-4 and Figure 6-13 As shown, a pin 14 is also fixedly installed on the base 1. One end of the pin 14 extends into the receiving cavity and is configured to be electrically connected to the circuit board. The other end of the pin 14 extends out of the receiving cavity.

[0039] In a preferred embodiment, the base 1 is a one-piece base. One example is... Figure 10-11 As shown, the base 1 includes a base body 101 and a mounting body 102. The mounting body 102 is located at the end of the base body 101 away from the opening. The pin 14 is disposed on the mounting body 102, and the mounting body 102 is integrally connected to the base body 101. In this example, the base body 101 is cylindrical with openings at both ends. One example is... Figure 5 As shown, the base 1 is a base body 101 with at least two openings, integrally connected. The base body 101 also has a connection port 15. A connector 211 or wire is provided on the circuit board 21, extending through the connection port 15 to the outside of the receiving cavity. Preferably, the openings and connection ports 15 are positioned opposite each other at both ends of the base 1, and the sensor or component is positioned opposite to the connector 211 or wire on both sides of the circuit board 21. In this example, the base 1 is a steel ring. When the base is a steel ring, the surface mount assembly is attached to the bottom of the inner cavity of the steel ring using, for example, sealant. Because the steel ring has openings at both ends, the pads on the back of the circuit board in the surface mount module are exposed, allowing for circuit lead-out work, such as wire bonding, connector mounting, or wire placement, on the exposed back of the circuit board. The use of connectors or wires reduces the need for pins and eliminates a pin sintering step, thus significantly reducing costs.

[0040] In a preferred embodiment, such as Figure 12-13 As shown, the base 1 is a split base, comprising a base body 101 and a mounting body 102. A pin 14 is disposed on the mounting body 102. A connection port 15 is also provided on the base body 101, and the mounting body 102 is sealed and mounted on the connection port 15. Preferably, the opening and the connection port 15 are positioned opposite each other at both ends of the base 1. In this example, the mounting body 102 is sealed and welded to the base body 101.

[0041] In a preferred embodiment, an annular groove 16 is formed on the surface of the base 1 or the surface of the upper pressure member 5, and an annular sealing ring 17 is placed inside the annular groove. Figure 1-5 , Figure 10 and Figure 12 As shown, the annular groove 16 is formed on the surface of the base 1. Figure 6-9 The annular groove 16 can also be formed on the surface of the upper pressure member 5. For example, on the threaded head of a threaded cap or on the insertion fixing structure of the insert seal 55. Of course, the annular groove 16 can be provided at the end of the upper pressure member 5 near the base, or at the end of the upper pressure member away from the base.

[0042] In a preferred embodiment, such as Figure 14-15 As shown, when the base 1 is a split base, a stop ring 19 is also provided at the end of the base body 101 away from the opening 12. The outer diameter of the mounting body 102 is larger than the inner diameter of the stop ring. The pin 14 is provided on the mounting body 102. The mounting body 102 is installed into the receiving cavity 11 through the opening 12, and the mounting body 102 abuts against and seals against the stop ring 19. By using the method of mounting body 1 abutting against and sealing against the stop ring, the mounting body and the base body do not need to be welded, the installation is more secure, and there will be no loosening or detachment.

[0043] It should be noted that, unless otherwise specified, the features in the above embodiments or embodiments described herein can be combined with each other arbitrarily.

[0044] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0045] Although embodiments of the present invention have been shown and described above, it is understood that these embodiments are exemplary, and it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the present invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A pressure sensor core packaging structure, characterized in that, It includes a base (1), a patch assembly (2), a filling structure (3), a strain gauge (4), and an upper pressure component (5); The base (1) has a receiving cavity (11), an opening (12) and an oil filling hole (13). The opening (12) is connected to the receiving cavity (11). The oil inlet end of the oil filling hole (13) is set close to the opening (12). The patch assembly (2) and the filling structure (3) are both housed in the receiving cavity (11). After the patch assembly (2) is housed at the bottom of the receiving cavity (11), the filling structure (3) fills the receiving cavity (11). The strain gauge (4) and the upper pressure member (5) are fixed in sequence on the opening (12) of the base (1). The strain gauge (4) is located between the base (1) and the upper pressure member (5). The strain gauge (4) and / or the upper pressure member (5) are sealed to the base. There is a gap between the strain gauge (4) and the filling structure (3). The gap is configured to be filled with oil through the oil filling hole (13). The oil filling hole (13) is configured to be sealed after filling the gap with oil. The upper pressure component (5) has an inspection port (51).

2. The pressure sensor core packaging structure according to claim 1, characterized in that, The surface mount assembly (2) includes a circuit board (21) and a pressure sensor (22), wherein the pressure sensor (22) and the circuit board (21) are integrally packaged in a receiving cavity; or The package of the pressure sensor (22) is mounted or soldered onto the circuit board (21), and the entire package is housed in the cavity.

3. The pressure sensor core packaging structure according to claim 2, characterized in that, The circuit board (21) also integrates one or more of the following: temperature sensor, humidity sensor, acceleration sensor and application circuit components.

4. The pressure sensor core packaging structure according to claim 1, characterized in that, The upper pressure element (5) is a pressure ring (52), a pressure cap (53), a threaded cap (54), or an insert seal (55); A pressure ring (52) or a pressure cap (53) is disposed on the opening (12) of the base (1); or The threaded cap (54) is sealed to the opening (12) of the base (1); or An insert seal (55) is installed on the opening (12) of the base (1).

5. The pressure sensor core packaging structure according to claim 1, characterized in that, A gap groove (18) is also provided on the base (1). The gap groove (18) is located at one end of the accommodating cavity near the opening (12). The gap groove (18) is configured to allow a gap between the strain gauge (4) and the filling structure (3). The oil inlet of the oil filling hole (13) is located on the bottom wall or side wall of the cavitation groove (18).

6. The pressure sensor core packaging structure according to claim 1, characterized in that, A pin (14) is also fixedly installed on the base (1). One end of the pin (14) extends into the cavity and is electrically connected to the circuit board, while the other end of the pin (14) extends out of the cavity.

7. The pressure sensor core packaging structure according to claim 2, characterized in that, The base (1) has a connection port (15) on its surface. A connector (211) or wire is mounted or soldered on the circuit board (21). The connector (211) or wire extends out of the accommodating cavity through the connection port (15).

8. The pressure sensor core packaging structure according to claim 1, characterized in that, The base (1) is an integral base; The base (1) includes a base body (101) and a mounting body (102), wherein a pin (14) is provided through the mounting body (102), and the mounting body (102) is integrally connected to the base body (101); and / or The base (1) is a steel ring.

9. The pressure sensor core packaging structure according to claim 8, characterized in that, The base (1) is a split base; The mounting body (102) is sealed and mounted on the base body (101); and / or A stop ring (19) is provided at the end of the base body (101) away from the opening (12). The outer diameter of the mounting body (102) is larger than the inner diameter of the stop ring. The mounting body (102) is installed into the receiving cavity (11) from the opening (12). The mounting body (102) abuts against and seals against the stop ring (19).

10. The pressure sensor core packaging structure according to claim 1, characterized in that, An annular groove (16) is provided on the surface of the base (1) or the surface of the upper pressure member (5), and an annular sealing ring (17) is placed in the annular groove; and / or A gap groove (18) is also provided on the base (1). The gap groove (18) is located at one end of the accommodating cavity near the opening (12). The gap groove (18) is located between the filling structure (3) and the strain gauge (4).

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