Capacitive thin film pressure sensor

Abstract

The application discloses a capacitive thin film pressure sensor and belongs to the technical field of sensors.The capacitive thin film pressure sensor comprises a diaphragm assembly, the diaphragm assembly comprises a strain film, a first ring-shaped part and a second ring-shaped part, the strain film is embedded between the first ring-shaped part and the second ring-shaped part in a flat manner, and the outer edge of the strain film is located in the projection area of the first ring-shaped part and the second ring-shaped part.The diaphragm assembly is formed by pressing the strain film by the two ring-shaped parts, the strain film is connected with the shell through the ceramic ring-shaped part, and the signal of the strain film is led out, so that the strain film is isolated from the metal shell and other metal components, the condition that the strain film is directly embedded into the shell to introduce noise and parasitic capacitance is avoided, the sealing property of a vacuum pressure detection cavity is improved, and the measurement precision of the sensor is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensors, in particular to a capacitive thin film pressure sensor. BACKGROUND

[0002] The capacitive thin film pressure sensor forms a variable electrode by an alloy pressure strain diaphragm and forms a vacuum sensing chamber of the sensor and a capacitance structure with a conductive coating on a ceramic substrate, and realizes the transmission of pressure change by the corresponding change of capacitance value caused by the pressure change on both sides of the alloy pressure strain diaphragm.

[0003] In order to make the alloy pressure strain diaphragm parallel to the electrode of the ceramic substrate and firmly installed in the sensor structure, the common method is to use metal welding means, such as laser welding, parallel brazing, etc. to weld the alloy strain diaphragm and the metal shell of the sensor together, which is convenient for signal lead-out at the end of the alloy strain diaphragm, but the capacitor as a sensitive device is connected with the metal shell, and the metal shell is usually connected with the test equipment, which easily introduces external signal noise, thereby affecting the test accuracy of the sensor.

[0004] The inner wall of the vacuum sensing chamber in the sensor is usually a metal material with the same thermal expansion coefficient as the alloy strain diaphragm, or a large-area metal coating is sprayed on the insulating pressure-resistant material, which is beneficial to the stability of air pressure and thermal balance, but also introduces a series of parasitic capacitances, which also affects the test performance of the sensor. The present application provides a new solution to the above problems. SUMMARY

[0005] In order to overcome at least one of the above-mentioned shortcomings, the present application provides a capacitive thin film pressure sensor. The purpose of the present application can be achieved by adopting the following technical scheme:

[0006] A capacitive thin film pressure sensor, comprising a diaphragm assembly, the diaphragm assembly comprising a strain diaphragm, a first ring-shaped member and a second ring-shaped member, the strain diaphragm being flatly embedded between the first ring-shaped member and the second ring-shaped member, and the outer edge of the strain diaphragm being located in the projection area of the first ring-shaped member and the second ring-shaped member.

[0007] In an implementable manner, the diaphragm assembly is formed by sintering the strain diaphragm, the first ring-shaped member and the second ring-shaped member, and the first ring-shaped member and the second ring-shaped member each comprise a ceramic material.

[0008] In an implementable manner, the outer diameter of the strain diaphragm is smaller than the outer diameter of the first ring-shaped member, and the outer diameter of the strain diaphragm is greater than the inner diameter of the first ring-shaped member.

[0009] The outer diameter of the strain film is smaller than the outer diameter of the second ring-shaped member, and the outer diameter of the strain film is greater than the inner diameter of the second ring-shaped member.

[0010] In an implementation, the capacitive thin film pressure sensor further comprises a housing, and the diaphragm assembly is arranged in an inner cavity of the housing.

[0011] In an implementation, the first ring-shaped member is provided with a first conductive hole, and the first conductive hole is located in a projected edge area of the strain film.

[0012] In an implementation, the capacitive thin film pressure sensor further comprises a fixed electrode, the fixed electrode comprises a ceramic substrate, the ceramic substrate is provided with a conductive coating on a first surface facing the diaphragm assembly, the ceramic substrate is provided with a circuit board on a second surface facing away from the diaphragm assembly, and the ceramic substrate is provided with a second conductive hole communicating with the first conductive hole.

[0013] In an implementation, the capacitive thin film pressure sensor further comprises a conductive member, the conductive member is arranged through the first conductive hole and the second conductive hole, a first end of the conductive member is electrically connected with the strain film, and a second end of the conductive member is electrically connected with the circuit board.

[0014] In an implementation, the conductive member is connected with the fixed electrode, and the conductive member is connected with the diaphragm assembly.

[0015] In an implementation, a length of the conductive member is adjustable, or a connection position of the conductive member with the fixed electrode and / or the diaphragm assembly is adjustable, so as to adjust a height difference between the fixed electrode and the strain film.

[0016] In an implementation, the ceramic substrate is provided with a third conductive hole, the third conductive hole is located in a projected edge area of the conductive coating, the third conductive hole is filled with a conductive material, a first end of the conductive material is electrically connected with the conductive coating, and a second end of the conductive material is electrically connected with the circuit board.

[0017] In an implementation, the circuit board comprises:

[0018] a capacitance conversion module for converting a capacitance signal into a voltage signal;

[0019] a wireless transmission module electrically connected with the capacitance conversion module, the wireless transmission module is connected with an antenna, and the wireless transmission module is configured to receive the voltage signal and wirelessly transmit the voltage signal to a terminal.

[0020] The beneficial technical effect of the present application: according to the present disclosure, the capacitive thin film pressure sensor comprises a diaphragm assembly formed by two annular pieces of strain film, the strain film is connected with the shell through the ceramic annular piece, and the signal of the strain film is led out, the strain film is isolated from the metal shell and other metal parts, the condition that the strain film is directly embedded in the shell to introduce noise and parasitic capacitance is avoided, the sealing property of the vacuum pressure detection cavity is improved, and the measurement accuracy of the sensor is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] In the drawings, the following is given by way of example and without limitation:

[0022] Figure 1 A structural schematic view of the first annular piece and the diaphragm assembly at one angle is shown;

[0023] Figure 2 A structural schematic view of the fixed electrode at one angle is shown;

[0024] Figure 3 A structural schematic view of the fixed electrode at another angle is shown;

[0025] Figure 4 A structural schematic view of the diaphragm assembly at one angle is shown;

[0026] Figure 5 A structural cross-sectional view of the capacitive thin film pressure sensor is shown.

[0027] In the drawings:

[0028] 1, diaphragm assembly; 2, fixed electrode; 3, conductive piece; 4, support frame; 5, spring; 6, shell; 7, pressure chamber to be measured; 8, reference pressure chamber;

[0029] 11, strain film; 12, first annular piece; 13, second annular piece;

[0030] 21, ceramic substrate; 22, conductive coating; 23, circuit board; 24, antenna;

[0031] 121, first conductive hole; 211, second conductive hole; 221, third conductive hole; 231, wireless transmission module; 232, capacitance conversion module. DETAILED DESCRIPTION

[0032] In the following detailed disclosure, the drawings are referred to, and these embodiments are fully described to make the technical solution of the present application more clear and explicit to those skilled in the art, the following described embodiments are not limited thereto, and the present application is further described in detail below in combination with the embodiments and drawings.

[0033] In this invention, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise explicitly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0034] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," 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 invention and simplifying the description, and do not indicate or imply that the device or unit 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 invention.

[0035] This invention provides a capacitive thin-film pressure sensor, such as... Figures 1-5 As shown, the capacitive thin-film pressure sensor includes a diaphragm assembly 1, which includes a strain film 11, a first annular member 12, and a second annular member 13. The strain film 11 is flatly embedded between the first annular member 12 and the second annular member 13, and the outer edge of the strain film 11 is located within the projection area of ​​the first annular member 12 and the second annular member 13.

[0036] The capacitive thin-film pressure sensor includes a diaphragm assembly 1 formed by pressing two annular members together with strain films 11. The strain films 11 are connected to the housing through ceramic annular members, and the signal of the strain films 11 is extracted. The strain films 11 are isolated from the metal housing and other metal components, avoiding the situation where the strain films 11 are directly embedded in the housing and introduce noise and parasitic capacitance. At the same time, the sealing performance of the vacuum pressure detection chamber is improved, which greatly improves the measurement accuracy of the sensor.

[0037] The first annular member 12 and the second annular member 13 can have the same shape and size. The cross-sectional shape of the first annular member 12 and the second annular member 13 is approximately a ring-shaped columnar structure. The annular columnar body can be provided with a groove for accommodating the strain film 11.

[0038] The first annular member 12 and the second annular member 13 may have different shapes and sizes, such as... Figure 5 As shown, the first annular member 12 includes an annular column and an outwardly extending annular flange. The annular flange extends toward the second annular member 13 and abuts against the second annular member 13. The strain film 11 is located inside the annular flange and between the first annular member 12 and the second annular member 13.

[0039] In an embodiment, the diaphragm assembly 1 is sintered by a strain film 11, a first ring 12 and a second ring 13, and the first ring 12 and the second ring 13 each comprise a ceramic material.

[0040] The first ring 12 and the second ring 13 are sintered by low-temperature sintering to form ceramic rings, and the ceramic rings have smooth surfaces. The metal strain film 11 is clamped between the two ceramic rings and is solidified by high-temperature sintering at a sintering temperature of 800-1100°C. The sintering forms a diaphragm assembly 1 with a ceramic structure on the outside and a strain film 11 in the middle. The strain film 11 is completely isolated from the shell and other metal components by the ceramic structure. The diaphragm assembly 1 serves as a variable electrode of a capacitive thin-film pressure sensor.

[0041] The sintering time gradually increases with the size of the ceramic ring. The specific sintering temperature and sintering time can be set according to the specific size of the ceramic ring, and the strain film 11 can be clamped to form a whole after solidification after sintering.

[0042] In this embodiment, the inner diameter of the ceramic ring is 5 cm, the outer diameter is 8 cm, and the diameter of the strain film 11 is 7 cm. The sintering temperature is 1000-1100°C, and the sintering time is about 2 hours.

[0043] In an embodiment, as shown in Figure 2 The outer diameter of the strain film 11 is smaller than the outer diameter of the first ring 12, and the outer diameter of the strain film 11 is larger than the inner diameter of the first ring 12. The outer diameter of the strain film 11 is smaller than the outer diameter of the second ring 13, and the outer diameter of the strain film 11 is larger than the inner diameter of the second ring 13.

[0044] The outer edge of the strain film 11 is located completely between the first ring 12 and the second ring 13 in the circumferential direction, so that the strain film 11 in the middle of the sintered and solidified diaphragm assembly 1 remains flat, ensuring the accuracy of the sensor.

[0045] In an embodiment, as shown in Figure 5 The capacitive thin-film pressure sensor further comprises a shell 6, and the diaphragm assembly 1 is arranged in the inner cavity of the shell 6.

[0046] As shown in Figure 5 The capacitive thin-film pressure sensor further comprises a shell 6, and the shell 6 generally comprises a metal material. The strain film 11 in the middle of the diaphragm assembly 1 faces the direction of the air inlet. The fixed electrode 2 is located on the side of the diaphragm assembly 1 away from the air inlet, and the strain film 11 is parallel to the fixed electrode 2.

[0047] The diaphragm assembly 1 is rigidly connected to the housing 6, and the outer diameters of the first annular member 12 and the second annular member 13 are adapted to the inner diameter of the housing 6.

[0048] The diaphragm assembly 1 can be fixed to the inner wall of the housing 6 by setting a sealing ring. The sealing ring can be made of metal or rubber material, which improves the stability of the connection between the diaphragm assembly 1 and the housing 6, and at the same time improves the sealing performance of the reference pressure chamber 8.

[0049] Among them, such as Figure 5 As shown, a support frame 4 can also be provided inside the outer casing 6, which is used to support the diaphragm assembly 1.

[0050] Among them, such as Figure 1 As shown, the capacitive thin-film pressure sensor also includes a spring 5, which is disposed inside the housing 6. The first end of the spring 5 abuts against the inner wall of the housing 6, and the second end abuts against the fixed electrode 2, that is, against the ceramic substrate 21. It is used to apply elastic force to the fixed electrode 2 to ensure the stability of the position of the fixed electrode 2, that is, to ensure the stability of the position between the fixed electrode 2 and the strain film 11, and to ensure the detection accuracy and stability.

[0051] The capacitive thin-film pressure sensor includes an air inlet pipe, a strain diaphragm 11, and a fixed electrode 2. The side of the diaphragm assembly 1 facing away from the air inlet pipe is a reference pressure chamber 8, and the side of the diaphragm assembly 1 facing away from the fixed electrode 2 is a pressure chamber to be measured 7. The strain diaphragm 11 is located between the pressure chamber to be measured 7 and the reference pressure chamber 8.

[0052] It is understandable that the air inlet pipe is connected to the pressure chamber 7 to be measured, one side of the strain diaphragm 11 is the pressure chamber 7 to be measured, and the other side of the strain diaphragm 11 is the reference pressure chamber 8. The two chambers are relatively independent, and there is a pressure difference between the two chambers. The pressure fluctuation of the pressure chamber 7 to be measured causes the strain diaphragm 11 to deform. The deformation is proportional to the pressure difference, which changes the distance between the strain diaphragm 11 and the fixed electrode 2 to measure the process pressure.

[0053] In one possible implementation, such as Figure 2 and Figure 3 As shown, the first annular member 12 has a first conductive hole, which is located within the edge projection area of ​​the strain film 11.

[0054] The first annular member 12 is located on the side of the strain film 11 away from the air inlet, that is, the side of the strain film 11 facing the fixed electrode 2. The first conductive hole is located on the side of the strain film 11 away from the air inlet. The first conductive hole is provided with a conductive layer, which is used to lead out the signal of the strain film 11 and at the same time improve the sealing of the vacuum pressure detection chamber.

[0055] The first conductive hole has two open ends, the first open end of the first conductive hole is connected with the strain film 11, and the second open end of the first conductive hole faces the fixed electrode 2.

[0056] In an embodiment, as shown in Figure 4 and Figure 5 The capacitive thin film pressure sensor further comprises a fixed electrode 2, the fixed electrode 2 comprises a ceramic substrate 21, the ceramic substrate 21 is provided with a conductive coating 22 on the first surface thereof facing the diaphragm assembly 1, the ceramic substrate 21 is provided with a circuit board 23 on the second surface thereof facing away from the diaphragm assembly 1, and the ceramic substrate 21 is provided with a second conductive hole 211 communicating with the first conductive hole.

[0057] The fixed electrode 2 comprises a cylindrical ceramic substrate 21, the ceramic substrate 21 is electroplated with a conductive coating 22 on the first surface thereof facing the strain diaphragm, and the ceramic substrate 21 is provided with a second conductive hole 211 in the uncoated region thereof.

[0058] In an embodiment, as shown in Figure 5 The capacitive thin film pressure sensor further comprises a conductive member 3, the conductive member 3 is arranged in the first conductive hole and the second conductive hole 211, the first end of the conductive member 3 is electrically connected with the strain film 11, and the second end of the conductive member 3 is electrically connected with the circuit board 23.

[0059] The second conductive hole 211 is also provided with a conductive layer, the first conductive hole and the second conductive hole 211 are aligned and communicate with each other, the first conductive hole and the second conductive hole 211 have substantially the same size and are coaxially arranged, and the conductive member 3 is arranged in the first conductive hole and the second conductive hole 211 to transmit the signal of the strain film 11 to the circuit board 23.

[0060] In an embodiment, as shown in Figure 3 The conductive member 3 is connected with the fixed electrode 2 and the diaphragm assembly 1.

[0061] The length of the conductive member 3 is adjustable to adjust the height difference between the fixed electrode 2 and the strain film 11.

[0062] The connection position of the conductive member 3 with the fixed electrode 2 and / or the diaphragm assembly 1 is adjustable to adjust the height difference between the fixed electrode 2 and the strain film 11.

[0063] It can be understood that the distance between the variable electrode and the fixed electrode 2 can be adjusted by changing the length of the conductive member 3, or replacing the conductive member 3 with different lengths, or changing the connection position of the fixed electrode 21 with the conductive member 3, or changing the connection position of the diaphragm assembly 1 with the conductive member 3, so that the range of the capacitive thin film pressure sensor can be flexibly adjusted.

[0064] The conductive member 3 can be an elongated conductive metal cylinder bar with the same diameter as the first and second conductive holes 211, and the first and second conductive holes 211 are connected by the metal bar, so that the signal of the variable electrode can be led out to the circuit board 23 on the fixed electrode 2.

[0065] In an embodiment, as shown in Figure 4 and Figure 3 The third conductive hole 221 is provided on the ceramic substrate 21 and located in the edge projection area of the conductive coating 22, and the third conductive hole 221 is filled with conductive material, the first end of the conductive material is electrically connected with the conductive coating 22, and the second end of the conductive material is electrically connected with the circuit board 23.

[0066] The third conductive hole 221 is provided on the conductive coating 22 area of the ceramic substrate 21, and the third conductive hole 221 is filled with conductive material, and the signal of the fixed electrode 2 can be led out to the circuit board 23 on the fixed electrode 2 through the conductive material.

[0067] In traditional semiconductor vacuum equipment and special process production equipment, usually one device needs to control multiple capacitive thin film pressure sensors at the same time. The common method is to use cables to collect signals of each sensor in a wired manner, and to collect data on the central processor of the equipment, which has great limitations.

[0068] In an embodiment, as shown in Figure 4 and ​ The circuit board 23 includes a capacitance conversion module 232 and a wireless transmission module 231, the capacitance conversion module 232 is used to convert the capacitance signal into a voltage signal, the wireless transmission module 231 is electrically connected with the capacitance conversion module 232, the wireless transmission module 231 is connected with an antenna, which is used to receive the voltage signal and wirelessly transmit the voltage signal to a terminal.

[0069] The second surface of the fixed electrode 2 away from the diaphragm assembly 1 can be sprayed or electroplated with a conductive coating 22 to construct an antenna and a wire structure required for connecting the second and third conductive holes 211 and 221 in a specified area.

[0070] The second surface of the fixed electrode 2 can be fixed with the circuit board 23 by vacuum insulation glue, and the electrical connection of the circuit board 23 with the antenna, the second and third conductive holes 211 and 221 can also be realized by vacuum conductive glue and jumper gold wires.

[0071] The power supply of the capacitive thin film pressure sensor can be an external power supply or a fixed capacity power supply such as a lithium battery.

[0072] The circuit board 23 can realize signal conversion through the capacitor conversion module 232. The capacitor thin film pressure sensor utilizes the material characteristics of the strain thin film 11 to convert pressure into changes in the capacitance value. When the pressure changes, the thin film produces a slight deformation, and the capacitance value changes. The capacitor conversion module 232 converts the changed capacitance value into a voltage signal output.

[0073] The circuit board 23 can realize wireless transmission function through the wireless transmission module 231. The receiving end of the wireless transmission module 231 is used to receive the voltage signal transmitted by the capacitor conversion module 232, and the voltage signal is transmitted through the antenna to the terminal through the transmitting end, realizing wireless measurement of the capacitor thin film pressure sensor. The data information of multiple sensors can be collected remotely at the same time, and the signal conversion and reading of multiple capacitor thin film pressure sensors can be selectively processed in a wireless manner.

[0074] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "a specific embodiment", and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0075] The above is only the preferred embodiment of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0076] In view of the above detailed description, these and other changes can be made to these embodiments. The present written description includes the best mode of the embodiments disclosed, and the patent scope obtained by the present application is defined by the claims. The claims are not limited by the disclosure, and the protection scope of the present application is not limited thereto. Any skilled person in the art can make equivalent replacements or changes to the technical solutions and concepts of the present application within the scope disclosed by the present application, and they are within the protection scope of the present application.

Claims

1. A capacitive thin-film pressure sensor, characterized in that, The diaphragm assembly (1) includes a strain film (11), a first annular member (12) and a second annular member (13). The strain film (11) is flatly embedded between the first annular member (12) and the second annular member (13), and the outer edge of the strain film (11) is located within the projection area of ​​the first annular member (12) and the second annular member (13). The diaphragm assembly (1) is formed by sintering a strain film (11), a first annular member (12), and a second annular member (13). Both the first annular member (12) and the second annular member (13) are made of ceramic material. The capacitive thin film pressure sensor also includes a housing (6), and the diaphragm assembly (1) is disposed in the inner cavity of the housing (6). The ceramic rings formed by the first ring (12) and the second ring (13) by low-temperature sintering have smooth surfaces, and the strain film (11) of the metal is sandwiched between the two ceramic rings and solidified by high-temperature sintering. The first annular member (12) has a first conductive hole (121) located in the edge projection area of ​​the strain film (11). The first conductive hole (121) has a conductive layer inside, which is used to lead out the signal of the strain film (11) for wireless transmission. The capacitive thin-film pressure sensor also includes a fixed electrode (2), which includes a ceramic substrate (21). The first side of the ceramic substrate (21) facing the diaphragm assembly (1) is provided with a conductive coating (22), and the second side of the ceramic substrate (21) away from the diaphragm assembly (1) is provided with a circuit board (23). A second conductive hole (211) communicating with the first conductive hole (121) is opened on the ceramic substrate (21). The capacitive thin-film pressure sensor also includes a conductive element (3), which passes through the first conductive hole (121) and the second conductive hole (211). The first end of the conductive element (3) is electrically connected to the strain film (11), and the second end of the conductive element (3) is electrically connected to the circuit board (23). The conductive element (3) is connected to the fixed electrode (2), and the conductive element (3) is connected to the diaphragm assembly (1); The length of the conductive element (3) is adjustable, or the connection position of the conductive element (3) with the fixed electrode (2) and / or the diaphragm assembly (1) is adjustable, for adjusting the height difference between the fixed electrode (2) and the strain film (11).

2. The capacitive thin-film pressure sensor according to claim 1, characterized in that, The outer diameter of the strain film (11) is smaller than the outer diameter of the first annular member (12), and the outer diameter of the strain film (11) is larger than the inner diameter of the first annular member (12); The outer diameter of the strain film (11) is smaller than the outer diameter of the second annular member (13), and the outer diameter of the strain film (11) is larger than the inner diameter of the second annular member (13).

3. The capacitive thin-film pressure sensor according to claim 1, characterized in that, A third conductive hole (221) is provided on the ceramic substrate (21). The third conductive hole (221) is located in the edge projection area of ​​the conductive coating (22). The third conductive hole (221) is filled with conductive material. The first end of the conductive material is electrically connected to the conductive coating (22), and the second end of the conductive material is electrically connected to the circuit board (23).

4. The capacitive thin-film pressure sensor according to claim 1, characterized in that, The circuit board (23) includes: A capacitance conversion module (232) is used to convert a capacitance signal into a voltage signal; A wireless transmission module (231) is electrically connected to the capacitor conversion module (232). The wireless transmission module (231) is connected to an antenna for receiving the voltage signal and wirelessly transmitting the voltage signal to the terminal.

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