A gauge pressure type silicon piezoresistive pressure sensor

Abstract

This utility model provides a gauge pressure type silicon piezoresistive pressure sensor. A differential pressure sensor chip is mounted in the inner cavity of a housing via a chip mounting base. A gas channel is formed on each of the opposite side panels of the chip mounting base, and a sealing ring is provided at the external port of each gas channel. The differential pressure sensor chip is sealed and isolated from the measured medium through these two sealing rings. No glue is used for mounting and sealing the differential pressure sensor chip, which effectively improves the sensor's service life. The two sealing rings are symmetrically arranged in annular grooves on the outer wall of the chip mounting base. During use, both sealing rings are simultaneously compressed by the housing, but in opposite directions, effectively preventing the sealing rings from falling off. This also improves the mounting firmness of the chip mounting base, enhances structural stability, and further extends the sensor's service life.

Description

Technical Field

[0001] This utility model relates to the field of sensor technology, specifically to a gauge pressure type silicon piezoresistive pressure sensor. Background Technology

[0002] A silicon piezoresistive pressure sensor (or differential pressure sensor) is a sensor made using the piezoresistive effect of single-crystal silicon. Four equal-value semiconductor resistors are diffused in a specific direction on a silicon diaphragm and connected to form a Wheatstone bridge, serving as the sensing element of a force-to-electrical converter. When the diaphragm is subjected to external pressure, the bridge becomes unbalanced. If an excitation power supply (constant current and constant voltage) is applied to the bridge, an output voltage proportional to the measured pressure can be obtained, thus achieving the purpose of pressure measurement. Based on the direction in which the silicon diaphragm senses pressure, they can be divided into absolute pressure type and gauge pressure type. In an absolute pressure type sensor, the silicon diaphragm senses pressure on one side, while the other side is a vacuum environment. Two pressure acquisition terminals are set up; during use, the pressure at each terminal is measured separately, and then the pressure difference is calculated. In a gauge pressure type sensor, the diaphragm senses pressure on both sides, and the pressure at both acquisition terminals is directly measured from both sides of the silicon diaphragm to directly obtain the pressure difference.

[0003] In existing technologies, the sealing between the sensor and the measured medium is usually achieved through adhesive bonding. For example, the patent solution with publication number CN218765760U describes our existing single-mode differential pressure sensor packaging structure. The pressure sensor chip is connected to other electrical components on the circuit board via pads and wiring to form a working circuit. The lower housing with an air nozzle is fixed to the lower surface of the circuit board with sealant. The sealant is used to seal the joints between the upper and lower housings with air nozzles and the circuit board, preventing liquids, gases, and solids from entering their cavities and protecting the internal working circuit. In a micro differential pressure sensor with a dual-air nozzle structure disclosed in patent document CN222188637U, after the MEMS chip and ASIC chip are glued to preset positions, the two chips are connected to the internal pins of the frame body using gold wire bonding. Adhesive is applied to the preset positions, and a bottom cover is attached. The dual air nozzles are connected to the frame body, epoxy adhesive is applied to the connection points, the product is sealed, and then baked for curing. The single-mode differential pressure sensor disclosed in patent document CN215726513U also achieves a sealing effect through sealant.

[0004] However, some drawbacks have been found in practical use: during the dispensing process, uneven dispensing, excessive or insufficient dispensing can occur due to the properties of the adhesive itself or the dispensing method, leading to poor sealing or contamination of other components; regardless of the type of adhesive, curing takes time, resulting in excessively long production cycles and increased time costs; during product use, especially in harsh environments, such as measuring the exhaust gas pressure difference between the front and rear channels of a car engine exhaust particulate filter—high-temperature environments with a high probability of encountering acids, alkalis, and organic solvents—the adhesive itself may change shape over time, causing seal failure and affecting product lifespan. Utility Model Content

[0005] To address the issue of shortened lifespan in harsh environments caused by existing glue-sealed sensor structures, this invention provides a gauge pressure type silicon piezoresistive pressure sensor. By improving the sensor structure, the lifespan of the sensor can be effectively extended.

[0006] The structure of this utility model is as follows: a gauge pressure type silicon piezoresistive pressure sensor, which includes: a housing, an air nozzle and a differential pressure sensor chip, characterized in that it further includes: a chip mounting base and a sealing ring;

[0007] The chip mounting base has an internal cavity for placing the chip; the size and shape of the cavity are adapted to the differential pressure sensor chip; on the opposite side walls of the chip mounting base, a gas channel is formed to connect the inside and outside of the cavity; the port position of each gas channel inside the cavity corresponds to the position of the pressure sensing surface of the differential pressure sensor chip; on the outer wall of the chip mounting base, an annular groove is formed with the port of each gas channel outside the cavity as the center; a sealing ring is provided in each annular groove, and the sealing ring is fitted around the outer circumference of the gas channel, with two sealing rings symmetrically arranged;

[0008] An installation cavity is formed inside the housing, and the chip mounting socket is disposed in the installation cavity;

[0009] Two air nozzles are disposed on the housing, and the air passages inside the air nozzles are connected to the gas passages of the chip mounting base.

[0010] Its further features are:

[0011] The pressure sensing surfaces of the differential pressure sensor chip are respectively arranged on opposite sides of the chip, and the two pressure sensing surfaces are parallel to each other; the two gas channels are located on the same axis, and the gas channels are perpendicular to the pressure sensing surfaces of the chip; the two sealing rings are arranged coaxially.

[0012] The chip mounting base is integrally formed and wraps around the outer periphery of the differential pressure sensor chip;

[0013] It also includes: a printed circuit board, wherein the mounting cavity inside the housing is a stepped cavity, comprising: a first cavity and a second cavity whose dimensions gradually increase from the inside to the outside;

[0014] The chip mounting base is disposed in the first cavity, and the printed circuit board is disposed in the second cavity;

[0015] It also includes: a cover plate; the mounting cavity further includes a third cavity, the third cavity being opened on one side of the second cavity communicating with the outside of the cavity, and having a larger size than the second cavity; the cover plate is disposed in the third cavity;

[0016] The outer shell and the air nozzle are integrally formed.

[0017] This utility model provides a gauge pressure type silicon piezoresistive pressure sensor. A differential pressure sensor chip is mounted in the inner cavity of a housing via a chip mounting base. A gas channel is formed on each of the opposite side panels of the chip mounting base, and a sealing ring is provided at the external port of each gas channel. The differential pressure sensor chip is sealed and isolated from the measured medium through these two sealing rings. No glue is used for mounting and sealing the differential pressure sensor chip, which effectively improves the sensor's service life. The two sealing rings are symmetrically arranged in annular grooves on the outer wall of the chip mounting base. During use, both sealing rings are simultaneously compressed by the housing, but in opposite directions, effectively preventing the sealing rings from falling off. This also improves the mounting firmness of the chip mounting base, enhances structural stability, and further extends the sensor's service life. Attached Figure Description

[0018] Figure 1 This is a three-dimensional structural schematic diagram of the pressure sensor of the gauge type silicon piezoresistive pressure sensor of this application;

[0019] Figure 2 This is a schematic diagram of the exploded structure of an embodiment of the pressure sensor;

[0020] Figure 3 A cross-sectional structural schematic diagram of an embodiment of the pressure sensor;

[0021] Figure 4 This is a cross-sectional structural diagram of the chip mounting base. Detailed Implementation

[0022] like Figures 1-4 As shown, the utility model of this application includes a gauge pressure type silicon piezoresistive pressure sensor, which includes: a housing 1, an air nozzle 2, a differential pressure sensor chip 3, a printed circuit board 4, a cover plate 5, a chip mounting base 6, and a sealing ring 7.

[0023] The chip mounting base 6 has an internal cavity 63 for housing the differential pressure sensor chip 3. The size and shape of the cavity 63 are adapted to the differential pressure sensor chip 3. On the opposite side walls of the chip mounting base 6, a gas channel 62 is opened to connect the inside and outside of the cavity 63. The port position of each gas channel 62 inside the cavity 63 corresponds to the position of the pressure sensing surface of the differential pressure sensor chip 3. On the outer wall of the chip mounting base 6, an annular groove 61 is opened with the port of each gas channel 62 outside the cavity 63 as the center. A sealing ring 7 is set in each annular groove 61, and the sealing ring 7 is fitted around the outer circumference of the gas channel 62. The two sealing rings 7 are symmetrically arranged.

[0024] Two air nozzles 2 are mounted on the outer casing 1. In this embodiment, the outer casing and the air nozzles are integrally formed. The air passages 21 inside the air nozzles 2 are connected to the gas passages 62 of the chip mounting base 6. The pressure sensing surfaces of the differential pressure sensor chip 3 are respectively located on opposite sides of the chip, and the two pressure sensing surfaces are parallel to each other; the two gas passages 62 are located on the same axis and are perpendicular to the two pressure sensing surfaces respectively; the two sealing rings 7 are coaxially arranged. By designing the two gas passages 62 as coaxial, when the measured medium enters from the two air nozzles respectively, it is guided by the air passages 21 inside the air nozzles and the gas passages 62 in the chip mounting base 6, and blown vertically onto the two pressure sensing surfaces of the differential pressure sensor chip 3, directly measuring the pressure at the two pressure acquisition ends, obtaining the pressure difference value, and realizing pressure detection. The specific structure and detection circuit of the differential pressure sensor chip 3 can be implemented based on existing technology. Figure 1 The external interface terminal 9 in the middle is connected to the printed circuit board to provide an external data interface for the pressure sensor. The specific implementation method is based on existing technology.

[0025] In this application, a sealing ring 7 seals the gas channel 62 and the outer casing 1, ensuring that the gas medium entering from the gas nozzle can only be guided through the gas channel 62 to the pressure sensing surface. The differential pressure sensor chip 3 is located inside the chip mounting base 6, with only the two pressure sensing surfaces on both sides in contact with the measured medium. This prevents the sensor chip itself from being damaged by harmful substances such as acids, alkalis, and organic solvents in the measured medium, effectively extending its service life. Furthermore, because the pressure sensing surfaces on both sides of the differential pressure sensor chip 3 receive pressure from the measured medium in opposite directions, and because the two gas channels 62 are located on the same axis, accurate pressure measurement can be achieved. The pressures from both sides can cancel each other out without damaging the sensor structure, ensuring that the pressure sensor of this application can be used for high-range testing.

[0026] like Figure 4As shown, the differential pressure sensor chip 3 is connected to the printed circuit board 4 via metal terminals 8; the metal terminals 8 are connected to the differential pressure sensor chip 3 inside the accommodating cavity 63 and the external circuit via through holes 64 on the chip mounting base 6. The specific connection method is based on existing technology.

[0027] In a practical implementation, the chip mounting base 6 can be designed with an opening at the top of the accommodating cavity 63. In conjunction with the top cover structure, after the differential pressure sensor chip 3 is placed inside the accommodating cavity, it is then connected as a single unit through welding or other methods. In this embodiment, to improve the sealing performance of the chip mounting base 6 and reduce processing steps, the structure of the chip mounting base 6 is designed as a single-piece molding structure. Specifically, the chip mounting base 6 can be wrapped around the outer periphery of the differential pressure sensor chip 3 using existing injection molding technology.

[0028] like Figure 2 As shown, an installation cavity is formed inside the housing 1. The installation cavity inside the housing 1 is a stepped cavity, which includes a first cavity 11, a second cavity 12, and a third cavity 13, whose dimensions gradually increase from the inside to the outside. The size and shape of the smallest first cavity 11 are adapted to the chip mounting base 6. The chip mounting base 6 is located at the innermost side of the first cavity 11. The printed circuit board 4 is located in the second cavity 12. The printed circuit board 4 is soldered to the housing 1 and the metal terminal 8 by means of soldering or other methods in the prior art.

[0029] The third cavity 13 is located on the outermost side of the mounting cavity and connects to the outside of the cavity. The third cavity 13 is larger than the second cavity 12. The cover plate 5 is disposed in the third cavity 13. In this embodiment, the cover plate 5 and the outer shell 1 are made of PPS plastic and are connected using existing technologies such as ultrasonic welding.

[0030] After using the technical solution of this utility model, the sealing of the differential pressure sensor chip 3 is achieved by the chip mounting base 6 with a fully enclosed shape and two sealing rings 7, which can achieve a good sealing effect and effectively seal and isolate the sensor chip from the measured medium. Compared with the existing structure based on glue sealing, this structure effectively avoids the problem of rapid failure caused by the use of glue in the harsh environment of high temperature and dirt. There is no need to set up a glue dispensing process during product processing, which can effectively save time and processing costs.

Claims

1. A gauge pressure type silicon piezoresistive pressure sensor, comprising: The housing, the air nozzle, and the differential pressure sensor chip are characterized in that they further include: a chip mounting base and a sealing ring; The chip mounting base has an internal cavity for placing the chip; the size and shape of the cavity are adapted to the differential pressure sensor chip; on the opposite side walls of the chip mounting base, a gas channel is formed to connect the inside and outside of the cavity; the port position of each gas channel inside the cavity corresponds to the position of the pressure sensing surface of the differential pressure sensor chip; on the outer wall of the chip mounting base, an annular groove is formed with the port of each gas channel outside the cavity as the center; a sealing ring is provided in each annular groove, and the sealing ring is fitted around the outer circumference of the gas channel, with two sealing rings symmetrically arranged; An installation cavity is formed inside the housing, and the chip mounting socket is disposed in the installation cavity; Two air nozzles are disposed on the housing, and the air passages inside the air nozzles are connected to the gas passages of the chip mounting base.

2. The pressure sensor of the gauge type silicon piezoresistive pressure sensor according to claim 1, characterized in that: The pressure sensing surfaces of the differential pressure sensor chip are respectively arranged on opposite sides of the chip, and the two pressure sensing surfaces are parallel to each other; the two gas channels are located on the same axis, and the gas channels are perpendicular to the pressure sensing surfaces of the chip; the two sealing rings are arranged coaxially.

3. The gauge pressure type silicon piezoresistive pressure sensor according to claim 1, characterized in that: The chip mounting base is integrally formed and wraps around the outer periphery of the differential pressure sensor chip.

4. The gauge pressure type silicon piezoresistive pressure sensor according to claim 1, characterized in that: It also includes: a printed circuit board; the mounting cavity inside the housing is a stepped cavity, including: a first cavity and a second cavity whose dimensions gradually increase from the inside to the outside; the chip mounting base is disposed in the first cavity, and the printed circuit board is disposed in the second cavity.

5. The gauge-type silicon piezoresistive pressure sensor according to claim 4, characterized in that: It also includes: a cover plate, and the mounting cavity further includes a third cavity, which is opened on one side of the second cavity communicating with the outside of the cavity, and is larger in size than the second cavity; the cover plate is disposed in the third cavity.

6. The gauge pressure type silicon piezoresistive pressure sensor according to claim 1, characterized in that: The outer shell and the air nozzle are integrally formed.

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