MEMS gas pressure sensor

Abstract

According to the MEMS gas pressure sensor provided by the invention, an independent through hole does not need to be specially formed in a shell of the sensor to serve as a gas inlet hole, the breathable steel based on a porous structure serves as a gas inlet structure of the sensor, and external to-be-detected gas or atmospheric pressure is introduced through the tiny exhaust holes in the breathable steel cylinder body; according to the sensor, the ventilation steel is arranged into the air inlet structures in different shapes, the installation cavity is formed by the ventilation structure and the shell, and the sensor chip is installed in the installation cavity, so that the external shell structure of the whole sensor is not provided with larger through holes, and the overall structural strength is improved; meanwhile, external dust and liquid can be prevented from entering the sensor.

Description

Technical Field

[0001] The utility model relates to the technical field of gas pressure sensors, in particular to a MEMS gas pressure sensor. Background Art

[0002] A MEMS (Micro-Electro-Mechanical Systems) gas pressure sensor is a miniature device that senses gas pressure signals and converts them into a usable output electrical signal. The sensor's sensitive element and signal processing circuitry are typically integrated on a single chip. The sensitive element converts the external pressure signal into an electrical signal, which is then amplified, filtered, and processed by a signal processing unit to output an electrical signal related to the input pressure. For example, patent publication number CN215639890U describes a pressure sensor currently in use by our company. The sensor comprises a substrate 110, a cover plate 120, and a pressure-sensitive chip 130. The substrate 110 is provided with an air inlet 111 extending through its thickness. The cover plate 120, which is mounted on the substrate 110, also has an air outlet 121 extending through its thickness. A cavity 140 is formed between the cover plate 120 and the substrate 110, housing the pressure-sensitive chip 130. The pressure-sensitive chip 130 corresponds to the air inlet 111 and utilizes a MEMS pressure-sensitive chip. The gas to be measured is introduced into the pressure-sensitive chip 130 through the inlet 111, while atmospheric pressure is introduced into the pressure-sensitive chip 130 through the outlet 121. The pressure difference between the two is reflected in the deformation of the diaphragm of the pressure-sensitive chip 130, generating an electrical signal. The electrical signal is connected to the peripheral circuit board through the sensor pins for processing and output, thus achieving real-time pressure measurement within the electronic device.

[0003] However, in actual use, it was found that if the air holes were too small, they would become clogged after prolonged use, causing the sensor to lose functionality. If the air holes were too large, tiny foreign objects could enter the sensor through the air holes in the cover, reducing sensor test accuracy and performance. Furthermore, the sensor holes could allow external liquids to enter the sensor chamber, corroding the sensor and causing it to fail. Furthermore, the holes in the cover and housing also weakened their structural strength, increasing the possibility of sensor damage. Summary of the Invention

[0004] In order to solve the problem in the prior art that holes are punched in the gas pressure sensor housing and cover, which causes the holes to be easily blocked and external foreign matter to enter after long-term use, thereby reducing the performance and service life of the gas pressure sensor, the utility model provides a MEMS gas pressure sensor, which can improve the protection capability and structural strength, ensure the stable performance of the sensor, and extend the service life of the sensor.

[0005] The structure of the utility model is as follows: a MEMS gas pressure sensor, which includes: a sensor chip, a housing and a mounting cavity;

[0006] It is characterized in that it further comprises: an air intake structure;

[0007] The air intake structure is made of breathable steel, which has a porous structure and is evenly distributed with tiny exhaust holes in all directions.

[0008] The air intake structure and the housing are installed together, and the installation cavity is formed between the two. The sensor is arranged at the bottom of the installation cavity, and the air intake structure is arranged above the sensor.

[0009] It is further characterized by:

[0010] The thickness of the permeable part of the permeable steel in the air intake structure is less than 2mm, and the effective permeable area is greater than 3mm²;

[0011] The diameter of the air-permeable steel micropores in the air intake structure is greater than 25 μm;

[0012] The housing comprises: a flat substrate; the air intake structure is provided as a U-shaped housing; the air intake structure is sealed and fixed above the substrate by fixing glue; the air intake structure and the substrate form a mounting cavity, and the sensor chip is provided in the mounting cavity and fixed on the substrate;

[0013] The shell includes: a U-shaped base, a concave stepped mounting cavity is arranged inside the base, the sensor chip is mounted at the bottom of the stepped cavity, and a stepped mounting groove is arranged at the U-shaped opening of the base; the air intake structure is arranged as a cover-like structure, the size of the air intake structure is adapted to the mounting groove, and the air intake structure is sealed and mounted in the mounting groove by fixing glue.

[0014] The present application provides a MEMS gas pressure sensor, which does not require a dedicated independent through hole as an air inlet hole on the sensor housing, but uses a porous structure of breathable steel as the air inlet structure of the sensor, and introduces the external gas to be measured or the atmospheric pressure through the tiny exhaust holes inside the breathable steel cylinder; the breathable steel is set to an air inlet structure of different shapes, and the air inlet structure and the shell jointly form an installation cavity, and the sensor chip is installed in the installation cavity. In this way, since there are no large through holes on the external shell structure of the entire sensor, the overall structural strength is improved, and external dust and liquid can also be prevented from entering the interior of the sensor; at the same time, since the technical solution of the present application is based on breathable steel as the air inlet structure, the steel body of the breathable steel is evenly distributed with tiny exhaust holes in all directions. Even if some of the small holes will be blocked during long-term use, compared with the structure of an independent air inlet hole in the prior art, the air inlet structure area is larger and will not be completely blocked, so the service life can be effectively extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of a gas pressure sensor according to embodiment 1;

[0016] Figure 2 This is a schematic diagram of the structure of a gas pressure sensor according to embodiment 2. DETAILED DESCRIPTION

[0017] The utility model includes a MEMS gas pressure sensor, which includes: a sensor chip, a housing and a mounting cavity. The sensor chip is implemented based on a MEMS pressure sensitive chip.

[0018] To enhance the overall structural strength of the sensor, this application avoids the use of large, independent air intakes. Instead, the air-permeable steel is designed with various air intake shapes. This porous structure, made from fine-grained spherical stainless steel powder sintered at high temperatures, is uniformly distributed throughout the interior with tiny vents. This provides excellent air permeability while also possessing high strength, hardness, and corrosion resistance.

[0019] Specifically, to ensure sufficient air intake for the gas pressure sensor, the permeable steel pores in the air intake structure of this application have a diameter greater than 25 μm and an effective air permeability area greater than 3 mm². To reduce the overall weight of the sensor and maintain consistent air pressure inside and outside the gas pressure sensor, the permeable steel portion of the air intake structure is less than 2 mm thick.

[0020] In the present application, the air intake structure and the shell are installed together, and a mounting cavity is formed between the two. The sensor is arranged at the bottom of the mounting cavity, and the air intake structure is arranged above the sensor.

[0021] like Figure 1In the illustrated embodiment 1, the housing comprises a flat PCB substrate 3; an air intake structure 2 configured as a U-shaped housing; the air intake structure 2 is sealed and fixed to the substrate 1 with adhesive 4; a mounting cavity 5 is formed between the air intake structure 2 and the substrate 1, and the sensor chip 1 is positioned within the mounting cavity 5 and fixed to the substrate 1. Chip 1 is connected to substrate 3 via leads, transmitting data to the substrate 3. Substrate 3 is electrically connected to external circuitry. Electrical signals from chip 1 are transmitted via leads to the substrate, where they are then connected to an external circuit board for processing and output.

[0022] In the specific production of Example 1, a PCB is used as a chip carrier, and the chip 1 is mounted on the PCB using a fixing glue. After the chip 1 is bonded with gold wire, a shell-shaped air intake structure 2 made of breathable steel is used to cover the chip and the pads. The air intake structure 2 and the PCB are fixed with a fixing glue.

[0023] like Figure 2 In the second embodiment shown, the housing comprises a U-shaped base 6 with a recessed, stepped mounting cavity 8 defined within it. The sensor chip 1 is mounted at the bottom of the stepped cavity 8, and a stepped mounting groove is defined within the U-shaped opening of the base 6. The air intake structure 2 is configured as a cover-like structure, sized to fit the mounting groove and sealed within it with adhesive. Chip 1 is electrically connected to chip pins 7 via leads, which in turn connect to a peripheral circuit board. Electrical signals from chip 1 are processed and output by the chip pins 7, which are then routed to the peripheral circuit board.

[0024] In the specific production of Example 2, the base 6 is made of plastic, and the pins 7 are injection molded into the housing. A flat cover plate made of breathable steel serves as the air intake structure 2. The chip 1 is mounted inside the base 6 using adhesive. After the chip 1 and the pins 7 are bonded with gold wire, the breathable steel air intake structure 2 is installed in the opening above the base 6. This air intake structure 2 does not have a dedicated pressure hole. The cover plate-shaped air intake structure 2 and the base 6 are fixed with adhesive.

[0025] Figure 1 and Figure 2 In the embodiment shown, only one air intake structure is provided. Figure 1 and Figure 2 The gas pressure sensor shown is placed in an environment where gas pressure needs to be detected. The ambient gas enters the sensor based on the air intake structure 1 at the top. After the inside and outside are kept consistent, the gas pressure causes the diaphragm of the pressure sensitive chip to deform and generate an electrical signal, thereby realizing real-time measurement of the ambient gas pressure.

[0026] With the technical solution of this utility model, the air intake structure is based on breathable steel. Through small holes distributed throughout the material, ventilation is achieved both inside and outside, preventing foreign matter from entering the interior. Furthermore, because the small holes are evenly distributed throughout the air intake structure, even if some of the small holes become blocked during long-term use, the gas pressure sensor can still function properly, effectively extending the sensor's service life. Furthermore, because neither the housing nor the air intake structure has dedicated, independent through-holes, the material structure is not damaged, effectively improving the structural strength of the housing. Breathable steel itself is also highly strong and corrosion-resistant. Using breathable steel to manufacture the housing increases the overall strength and corrosion resistance of the sensor.

Claims

1. A MEMS gas pressure sensor, comprising: sensor chip, housing and mounting cavity; It is characterized in that it further comprises: an air intake structure; The air intake structure is made of breathable steel, which has a porous structure and is evenly distributed with tiny exhaust holes in all directions. The air intake structure and the housing are installed together, and the installation cavity is formed between the two. The sensor is arranged at the bottom of the installation cavity, and the air intake structure is arranged above the sensor.

2. The MEMS gas pressure sensor according to claim 1, wherein: The thickness of the permeable part of the permeable steel in the air intake structure is less than 2 mm, and the effective permeable area is greater than 3 mm².

3. The MEMS gas pressure sensor according to claim 1, wherein: The diameter of the air-permeable steel micropores in the air intake structure is greater than 25 μm.

4. The MEMS gas pressure sensor according to claim 1, wherein: The shell includes: a flat substrate; the air intake structure is configured as a U-shaped shell; the air intake structure is sealed and fixed above the substrate by fixing glue; the installation cavity is formed between the air intake structure and the substrate, and the sensor chip is arranged in the installation cavity and fixed on the substrate.

5. The MEMS gas pressure sensor according to claim 1, wherein: The shell includes: a U-shaped base, a concave stepped mounting cavity is arranged inside the base, the sensor chip is mounted at the bottom of the stepped cavity, and a stepped mounting groove is arranged at the U-shaped opening of the base; the air intake structure is arranged as a cover-like structure, the size of the air intake structure is adapted to the mounting groove, and the air intake structure is sealed and mounted in the mounting groove by fixing glue.

Images