Low range oil filled pressure sensor

Abstract

The application provides a low-range oil-filled pressure sensor and belongs to the technical field of pressure sensors, aiming to solve the problem of stress transmission and large detection error caused by viscous glue fixing of a pressure core of an existing sensor. The low-range oil-filled pressure sensor comprises a base, a ceramic seat, a pressure chip and a diaphragm, the top of the base is provided with a sink, the inside of the base is provided with a pin extending into the sink, and the pin extends out of the bottom of the base; the ceramic seat is located in the sink and is fixedly connected with the base, the middle of the ceramic seat is provided with a pressure cavity, and the ceramic seat is also provided with a through hole corresponding to the pin; the pressure chip is located in the pressure cavity, and the pressure chip and the pin are connected through a bonding wire, so that the pressure chip is pulled up and kept in a suspended state in the pressure cavity. The low-range oil-filled pressure sensor suspends and fixes the pressure core through the bonding wire, blocks stress transmission, and improves the measurement accuracy and stability.

Description

Technical Field

[0001] This invention belongs to the field of pressure sensor technology, specifically relating to a low-range oil-filled pressure sensor. Background Technology

[0002] The pressure sensor comprises an isolation diaphragm, an oil-filled chamber, a sensing element, and an information conditioning circuit. The oil-filled chamber is located between the isolation diaphragm and the sensing element. During operation, the pressure to be measured acts on the isolation diaphragm, and the liquid in the oil-filled chamber evenly transmits the pressure to the sensing element. The diaphragm on the sensing element experiences a micro-displacement proportional to the pressure, causing a change in piezoresistive resistance. A bridge circuit converts this resistance change into a voltage difference, achieving the initial conversion from pressure to an electrical signal. The electrical signal is then amplified and compensated by the signal conditioning circuit before being converted into a digital signal.

[0003] The sensitive chip in a pressure sensor is a force-sensitive device, which is extremely sensitive to external stress, especially for low-range pressure sensors. During packaging, the sensitive chip is usually fixed to the base using adhesive. The stress from the adhesive and the base during this process is transmitted to the sensitive chip, causing signal drift and resulting in a larger error in the final detected pressure value. Summary of the Invention

[0004] This invention provides a low-range oil-filled pressure sensor, which aims to solve the technical problem that in existing pressure sensors, the sensitive chip is fixed by adhesive, and the stress of the adhesive and the base is transmitted to the sensitive chip, causing signal drift and resulting in large detection value errors.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a low-range oil-filled pressure sensor, comprising:

[0006] The base has a groove at the top and a pin inside that extends into the groove and protrudes from the bottom of the base.

[0007] A ceramic seat is located in the sink and fixedly connected to the base. The ceramic seat has a pressure chamber in the middle and a through hole corresponding to the pin.

[0008] A pressure chip is located inside the pressure chamber. The pressure chip is connected to the pin via a bonding wire, so that the pressure chip can be pulled up and kept suspended in the pressure chamber.

[0009] A diaphragm is fixedly connected to the top of the base, and a sealed cavity is formed between the diaphragm and the pressure chip, the sealed cavity being filled with a pressure transmission medium.

[0010] In one possible implementation, the number of bonding wires is greater than or equal to 5, and the diameter of the bonding wires is 50±0.5μm.

[0011] In one possible implementation, the top of the pin is provided with a solder pad, the diameter of which is smaller than the diameter of the through hole;

[0012] The base has a cavity for the pins to extend out, and the base also includes a glass sintered column fixed in the cavity.

[0013] In one possible implementation, the ceramic base has a connecting channel through which the bonding wire passes, the connecting channel opening upward and connecting the pressure chamber and the through hole, and the tip of the pin is below the connecting channel.

[0014] In one possible implementation, the sidewall of the through hole is provided with a positioning groove corresponding to the connection channel. The positioning groove is V-shaped and is used to limit the position of the bonding wire.

[0015] In one possible implementation, the base further includes a pressure ring pressed around the top of the diaphragm.

[0016] In one possible implementation, the base is further provided with an air chamber located below the pressure chamber, and the pressure chip is located directly above the air chamber;

[0017] The base is provided with an air hole communicating with the air chamber, and the bottom of the base is provided with a vent pipe communicating with the air hole.

[0018] In one possible implementation, the diaphragm has multiple corrugations to form alternating peaks and troughs from the center of the diaphragm outwards, with the peaks gradually increasing from the center of the diaphragm outwards and the troughs gradually increasing from the center of the diaphragm outwards.

[0019] In one possible implementation, the width of the multiple turns of the ripples gradually decreases from the center of the diaphragm outwards.

[0020] In one possible implementation, the top surface of the base has a cavity surface located on the outer periphery of the settling tank, and a mounting surface that abuts the outer periphery of the cavity surface. The cavity surface gradually slopes downward along a direction close to the axis of the base and corresponds to multiple turns of the corrugations. The mounting surface is in contact with the lower surface of the diaphragm.

[0021] Compared with existing technologies, this embodiment suspends the pressure chip using bonding wires, eliminating rigid contact between the pressure chip and the base. Electrical connection and mechanical fixation are achieved solely through the flexible bonding wires. The elastic deformation of the bonding wires absorbs most external stress, completely blocking stress transmission from the base to the pressure chip and avoiding stress drift errors. The pressure chip in this structure responds only to the measured pressure, significantly improving the sensor's measurement accuracy and long-term stability. Suspending the pressure chip with bonding wires avoids the impact of adhesive aging on sensor reliability, making it suitable for harsh conditions such as high temperature, high vacuum, and strong corrosion. After pressure is transmitted from the diaphragm to the pressure transmission medium, it acts uniformly and unimpeded on the sensitive surface of the pressure chip, eliminating the buffering and isolation effect of adhesives. Simultaneously, because the pressure chip is suspended, the flow resistance of the pressure transmission medium is lower, and the pressure transmission hysteresis time is shorter, enabling rapid response to dynamic changes in the measured pressure, making it suitable for dynamic pressure measurement scenarios. Suspended mounting only requires the positioning of the pressure chip and the welding of the bonding wires through bonding equipment. It involves fewer process steps, easier parameter control, and can effectively improve the yield rate of mass production. Attached Figure Description

[0022] Figure 1 A top view of the low-range oil-filled pressure sensor provided in an embodiment of the present invention;

[0023] Figure 2 For along Figure 1 Schematic diagram of the cross-sectional structure along line AA;

[0024] Figure 3 For along Figure 1 Schematic diagram of the cross-sectional structure of the middle BB line;

[0025] Figure 4 An exploded structural diagram of a low-range oil-filled pressure sensor provided in an embodiment of the present invention;

[0026] Figure 5 This is a three-dimensional structural diagram of the base used in an embodiment of the present invention;

[0027] Figure 6 This is a schematic diagram of the cross-sectional structure of the diaphragm used in an embodiment of the present invention;

[0028] Figure 7 This is a schematic diagram of the distribution structure of the pressure chip and pins used in an embodiment of the present invention;

[0029] Figure 8 This is a schematic diagram of the distribution structure of the pressure chip and pins used in another embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures:

[0031] 10-Base; 11-Sink; 12-Pin; 13-Welding plate; 131-Guide hole; 14-Glass sintering column; 15-Pressure ring; 16-Gas chamber; 17-Vent pipe; 18-Cavity surface; 19-Mounting surface; 110-Limiting step.

[0032] 20-Ceramic base; 21-Pressure chamber; 22-Through hole; 23-Connecting channel; 24-Positioning groove;

[0033] 30 - Pressure chip; 31 - Bonding wire;

[0034] 40 - membrane; 41 - crest; 42 - trough;

[0035] 50 - Sealing component. Detailed Implementation

[0036] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0037] Please refer to the following: Figures 1 to 8 The low-range oil-filled pressure sensor provided by this invention will now be described. The low-range oil-filled pressure sensor includes a base 10, a ceramic seat 20, a pressure chip 30, and a diaphragm 40. The base 10 has a recess 11 at its top, and a pin 12 extending into the recess 11 and protruding from the bottom of the base 10. The recess 11 is adapted to the shape of the ceramic seat 20. After the ceramic seat 20 is installed in the recess 11, it can be bonded and fixed to the inner wall of the recess 11 with adhesive, improving the installation stability of the ceramic seat 20 and preventing the pressure chip 30 from shaking and affecting the accuracy of the pressure measurement. The pin 12 is fixed to the base 10, with its top extending into the recess 11 for connection with the pressure chip 30 via a bonding wire 31, and its bottom protruding from the base 10 for connection with external devices to transmit electrical signals.

[0038] The ceramic seat 20 is located within the recess 11 and fixedly connected to the base 10. A pressure chamber 21 is located in the center of the ceramic seat 20, and through holes 22 corresponding to the pins 12 are also provided on the ceramic seat 20. Ceramic material itself has excellent insulation properties. Compared to metal materials, the ceramic seat 20 can effectively isolate the internal circuit components of the sensor, avoiding problems such as signal short circuits, leakage, or electromagnetic interference, ensuring the accuracy of pressure signal conversion. Simultaneously, the dielectric constant of ceramic is stable and will not affect the electric field distribution between the pressure sensor's plates. Ceramic has extremely strong chemical stability and is resistant to corrosion from acids, alkalis, salt solutions, and other corrosive media. In contact pressure measurement, the ceramic seat 20 can directly contact the measured medium, protecting the internal metal circuitry and pressure chip 30 from corrosion, and meeting hygiene standards in the food and medical fields. The structural design of the ceramic seat 20 matches the recess 11 on the base 10, achieving internal sealing of the sensor through sealing rings, welding, or screws, preventing external moisture and dust from entering, and improving the sensor's protection level. In addition, ceramics have high mechanical strength and a small coefficient of thermal expansion, and are not easily deformed in high and low temperature environments. They can provide stable structural support for sensors and reduce the impact of temperature changes on measurement accuracy.

[0039] The pressure chip 30 is located within the pressure chamber 21. The pressure chip 30 is connected to the pin 12 via bonding wires 31, allowing the pressure chip 30 to be lifted and suspended within the pressure chamber 21. The core sensitive area of ​​the pressure chip 30 is the strain region, which is responsible for converting pressure deformation into an electrical signal. Therefore, the pads are designed in the non-sensitive area at the edge of the chip, evenly distributed around the perimeter of the pressure chip 30, maintaining a sufficient safe distance from the sensitive area. Multiple bonding wires 31 are soldered to corresponding pads on the pressure chip 30, with the other end of each bonding wire 31 connected to a pin 12. The structural strength of the bonding wires 31 after installation ensures the suspension of the pressure chip 30.

[0040] A diaphragm 40 is fixedly connected to the top of the base 10, forming a sealed cavity between the diaphragm 40 and the pressure chip 30. This sealed cavity is filled with a pressure transmission medium. The pressure transmission medium can be silicone oil, fluorinated oil, etc. The sensitive area of ​​the pressure chip 30 is tiny and extremely sensitive to pressure distribution, making direct contact with the measured medium impossible. Here, the diaphragm 40 is the sensitive component that directly contacts the measured medium, and it undergoes elastic deformation under pressure. The pressure transmission medium has high stability and is virtually incompressible. Therefore, the concentrated pressure on the diaphragm 40 is converted into uniform hydraulic pressure, which acts on the sensitive area of ​​the pressure chip 30, causing deformation of the sensitive area and accurately converting it into an electrical signal.

[0041] When silicone oil is used as the pressure transmission medium, it enables lossless transmission of minute deformations on the diaphragm 40 to the pressure chip 30, improving the accuracy of pressure detection. Furthermore, the silicone oil covering the top of the pressure chip 30 provides isolation, preventing damage from impurities. Simultaneously, the good thermal conductivity of silicone oil allows it to transfer the heat generated during chip operation to the diaphragm 40 and the base 10, preventing temperature drift errors caused by overheating.

[0042] It should be noted that the shape of the pressure chamber 21 is adapted to the shape of the pressure chip 30, so that after the pressure chip 30 is installed in the pressure chamber 21, the side wall of the pressure chamber 21 can fix and limit the pressure chip 30, avoiding large errors in the measurement value caused by shaking during use.

[0043] In traditional packaging, the pressure chip 30 is typically bonded to the base 10 using adhesive. However, the curing shrinkage and coefficient of thermal expansion of the adhesive do not match those of the pressure chip 30 and the base 10, resulting in residual stress. Simultaneously, the stress from temperature changes in the base 10 is also transmitted to the pressure chip 30 through the adhesive, causing non-pressure deformation of the sensitive elements on the pressure chip 30 and introducing measurement errors.

[0044] Furthermore, adhesives are prone to hardening and cracking when exposed to high temperatures and corrosive environments during use. Volatile organic compounds in the adhesive can contaminate the surface of the pressure chip 30 or the pressure transmission medium, affecting signal conversion efficiency. The poor thermal conductivity of the adhesive hinders heat dissipation during chip operation, leading to increased chip temperature drift.

[0045] During the bonding process, it is necessary to consider the curing time and coating amount of the adhesive. Improper operation may also lead to problems such as misalignment of the bonded parts and air bubbles in the adhesive layer.

[0046] The low-range oil-filled pressure sensor provided in this embodiment, compared with the prior art, suspends the pressure chip 30 by bonding wire 31, allowing the pressure chip 30 to be in no rigid contact with the base 10. Electrical connection and mechanical fixation are achieved solely through the flexible bonding wire 31. The elastic deformation of the bonding wire 31 absorbs most of the external stress, completely blocking stress transmission from the base 10 to the pressure chip 30 and avoiding stress drift errors. The pressure chip 30 in this structure responds only to the measured pressure, significantly improving the sensor's measurement accuracy and long-term stability. The suspension and fixation of the pressure chip 30 by the bonding wire 31 avoids the impact of adhesive aging on sensor reliability, making it suitable for harsh working conditions such as high temperature, high vacuum, and strong corrosion. After the pressure is transmitted from the diaphragm 40 to the pressure transmission medium, it can act uniformly and without obstruction on the sensitive surface of the pressure chip 30, eliminating the buffering and isolation effect of adhesive. Simultaneously, because the pressure chip 30 is suspended, the flow resistance of the pressure transmission medium is lower, and the pressure transmission hysteresis time is shorter, enabling rapid response to dynamic changes in the measured pressure, making it suitable for dynamic pressure measurement scenarios. Suspended mounting only requires positioning of the pressure chip 30 and welding of the bonding wire 31 through bonding equipment, with fewer process steps and easier parameter control, which can effectively improve the yield of mass production.

[0047] The oil-filled pressure sensor of this application also includes an oil injection channel that runs through the base 10 and the ceramic seat 20. The oil injection channel is used to introduce a pressure transmission medium into the sealed cavity. After oil injection, it can be sealed by the sealing member 50.

[0048] In some embodiments, the specific number and size of the aforementioned pins 12 and bonding wires 31 can be defined as follows: Figures 2 to 4 , Figures 7 to 8 The structure shown. See also Figures 2 to 4 , Figures 7 to 8 The number of bonding wires 31 is greater than or equal to 5, and the diameter of bonding wires 31 is 50±0.5μm.

[0049] Since the pressure chip 30 is suspended and requires no adhesive for fixation, it relies entirely on the mechanical support provided by the bonding wire 31. Conventional bonding wires 31 have a diameter of 20–30 μm, which is only sufficient for electrical conductivity. In this embodiment, the bonding wire 31 has significantly improved tensile and bending strength, effectively supporting the weight of the pressure chip 30 itself.

[0050] Meanwhile, when the number of bonding wires 31 is even, multiple bonding wires 31 can be symmetrically distributed and connected to the pads on the pressure chip 30, which can disperse the pressure chip 30 and external stress to each bonding point, avoid single or a few bonding wires 31 from breaking due to stress concentration, and prevent the chip from tilting, shifting or even falling off.

[0051] It is easy to understand that when the number of bonding wires 31 is odd, the number of bonding wires 31 on both sides of the pressure chip 30 can be different. Since the pressure sensor of this application is mainly used for measuring static pressure and not for measuring pressure in a vibration environment, the asymmetrical installation position of the bonding wires 31 will not affect the installation stability and measurement accuracy of the pressure chip 30.

[0052] According to the formula for conductor resistance:

[0053] R = ρ × L ÷ S

[0054] Where ρ is the resistivity of the material, L is the length of the bonding wire 31, and S is the cross-sectional area of ​​the bonding wire 31.

[0055] With a fixed length of bonding wire 31, a larger diameter results in a larger cross-sectional area and lower resistance. For pressure sensors requiring high current transmission, a large-diameter bonding wire 31 reduces Joule heat loss during current flow, preventing localized high temperatures from causing bonding point oxidation and failure. For high-precision pressure chip 30, low contact resistance reduces noise interference during signal transmission, improves the signal-to-noise ratio, and ensures measurement accuracy.

[0056] In addition to meeting the basic four-wire requirements for power (V+, V-) and signal (S+, S-), five or more bonding wires 31 can be used for temperature compensation (such as connecting the chip's built-in temperature sensing resistor), grounding protection, or backup paths to adapt to complex signal processing needs.

[0057] When the suspended chip experiences pressure changes or temperature cycling, it undergoes minute displacements or deformations, causing the bonding wire 31 to bend and stretch repeatedly. The bonding wire 31, with a diameter of 50±0.5μm, has a higher fatigue resistance threshold, reducing metal fatigue cracks caused by repeated deformation. The symmetrical arrangement of multiple bonding wires 31 reduces the deformation amplitude of a single wire 31, further improving overall fatigue resistance and ensuring the connection reliability of the sensor during long-term operation.

[0058] The suspended packaged sensor needs to be filled with a pressure transmission medium in a vacuum environment. During the filling process, the flow of the liquid medium will impact the bonding wire 31. The large-diameter bonding wire 31 is more rigid and is not easily bent by the impact of the medium; the support structure of multiple bonding wires 31 can also limit the movement of the chip and prevent the bonding wire 31 from contacting and short-circuiting with other conductive parts.

[0059] Meanwhile, the bending curvature of the large-diameter bonding wire 31 is more stable, and it will not shrink or stretch excessively due to medium flow or temperature changes, thus ensuring the electrical insulation spacing.

[0060] Optionally, the bonding wire 31 can be made of gold wire.

[0061] In some embodiments, a specific mounting method for the aforementioned pin 12 can be as follows: Figures 2 to 4 , Figures 7 to 8 The structure shown. See also Figures 2 to 4 , Figures 7 to 8 The top of pin 12 is provided with a solder pad 13, the diameter of which is smaller than the diameter of the through hole 22;

[0062] The base 10 has a cavity for the pins 12 to extend out, and the base 10 also includes a glass sintered column 14 fixed in the cavity.

[0063] Although the diameter of the solder pad 13 is smaller than that of the through hole 22, it is larger than that of the pin 12. The distance between the solder pad 13 and the inner wall of the through hole 22 facilitates the installation of the bonding wire 31, leaving sufficient operating space.

[0064] The larger diameter of the solder pad 13 provides a larger contact area with the bonding wire 31 and allows for the adhesion of more solder. This results in a more stable connection, effectively dispersing bonding stress and preventing the bond from detaching or breaking due to insufficient contact points, thus significantly improving the mechanical stability of the electrical connection.

[0065] The solder pad 13 at the top of pin 12 has a larger diameter, which facilitates visual identification, reduces the difficulty of equipment alignment, reduces bonding failures caused by positioning deviations, and improves the efficiency and yield of mass production.

[0066] When mounting the pins 12 onto the base 10, the number and mounting positions of the pins 12 need to be determined first. Holes are drilled in the base 10, and the interior is processed to form a cavity. The pins 12 are passed through the cavity, and the lengths of the top and bottom ends of the pins 12 extending out of the cavity are adjusted. Glass powder (borosilicate glass or aluminosilicate glass) is filled into the gap between the pins 12 and the cavity. The assembled pins 12 and base 10 are placed in a sintering furnace and heated until the glass powder softens and melts into a uniform liquid glass phase. After solidification, a glass sintered column 14 is formed.

[0067] The pin 12 and base 10 are connected by glass sintering. The cured glass has high hardness and a dense structure, which can firmly encapsulate the pin 12 and prevent it from shifting or loosening. Glass is an excellent insulator, which can effectively isolate the conductive pin 12 and base 10, avoid short circuits, and ensure stable transmission of electrical signals. There are no gaps or cracks at the connection between the glass and base 10, and the sealing level is high, which can prevent external moisture and gas from entering the sensor and prevent leakage of the internal pressure transmission medium.

[0068] As an improved embodiment of the solder pad 13, the solder pad 13 is also provided with a guide hole 131. The top end of the axis of the guide hole 131 is inclined towards the bonding wire 31, or the axis of the guide hole 131 is parallel to the vertical direction. Since the bonding wire 31 and the solder pad 13 are connected by solder, if the solder pad 13 does not have a guide hole 131, the contact surface between the bonding wire 31 and the solder pad 13 is flat. After the bonding wire 31 is fixed to the solder pad 13, it extends inclined upward towards the pressure chip 30, which will form a bending point at the connection with the solder pad 13, which can easily cause the bonding wire 31 to bend and break. By providing a guide hole 131, the end of the bonding wire 31 extends into the guide hole 131, and the connection and fixation between the bonding wire 31 and the solder pad 13 is achieved by filling the guide hole 131 with solder. The guide hole 131 ensures that the connection section between the bonding wire 31 and the welding pad 13 has a downward component, thereby preventing the bonding wire 31 from being pulled off due to the weight of the pressure chip 30 during the suspension of the pressure chip 30, thus improving reliability.

[0069] In some embodiments, an improved implementation of the ceramic base 20 described above can employ, as follows: Figures 2 to 4 , Figures 7 to 8 The structure shown. See also Figures 2 to 4 , Figures 7 to 8 The ceramic base 20 is provided with a connecting channel 23 through which the bonding wire 31 passes. The connecting channel 23 opens upward and connects the pressure chamber 21 and the through hole 22. The top of the pin 12 is lower than the connecting channel 23.

[0070] The pressure chamber 21 on the ceramic base 20 is located in the center, and multiple through holes 22 are evenly distributed on the outer periphery of the pressure chamber 21. The bonding wire 31 needs to connect the pads on the chip and the pads 13 on the pins 12. If the bonding wire 31 is directly attached to the top surface of the ceramic base 20, it is easy for the position to be misaligned. After the misalignment, the tension of the bonding wire 31 on the pressure chip 30 will no longer be uniform, which can easily affect the installation stability of the pressure chip 30.

[0071] By setting up connection channels 23, each bonding wire 31 can correspond to one connection channel 23. The sidewall of the connection channel 23 can guide the bonding wire 31, limit the routing trajectory of each bonding wire 31, and prevent the bonding wire 31 from deviating, which could cause instability of the pressure chip 30 or short circuit.

[0072] Meanwhile, the connecting channel 23 can also serve as a support point for the bonding wire 31, helping process engineers to precisely control the arc height of the bonding wire 31 and keep it within the optimal range. When filling the pressure transmission medium, the connecting channel 23 can provide a buffering effect, preventing the bonding wire 31 from being subjected to excessive impact and deforming.

[0073] To protect the bonding wire 31, the sidewalls of the connecting channel 23 are polished or chamfered, and a protective layer is also provided on the inner side of the connecting channel 23 to reduce wear on the bonding wire 31.

[0074] It should be noted that the extension direction of the connecting channel 23 should coincide with the projection of the extension direction of the bonding wire 31 inside it, thereby ensuring that the bonding wire 31 is less bent. In addition, the end of the connecting channel 23 can also be provided with rounded corners to avoid sharp points from wearing down the bonding wire 31 and causing it to break.

[0075] Correspondingly, the pads on the pressure chip 30 are oblong, and the length direction of the oblong pads is parallel to the extension direction of the corresponding connection channel 23.

[0076] In some embodiments, an improved implementation of the ceramic base 20 described above can employ, as follows: Figure 7 The structure shown. See also Figure 7 The side wall of the through hole 22 is provided with a positioning groove 24 corresponding to the connecting channel 23. The positioning groove 24 is V-shaped and is used to limit the bonding wire 31.

[0077] The positioning groove 24 is recessed into the connecting channel 23 in a V-shape, and the corresponding corners are all chamfered.

[0078] Since pin 12 is lower than the connection channel 23, the bonding wire 31 extends downward after passing through the connection channel 23 and connects with pin 12. The portion of the bonding wire 31 extending out between the connection channel 23 and pin 12 abuts against the edge of the intersection of the connection channel 23 and the through hole 22. By providing a V-shaped positioning groove 24 on the inner wall of the through hole 22, the bonding wire 31 can be secured at the bottom of the positioning groove 24. Through the guiding effect of the side wall of the positioning groove 24, if the bonding wire 31 shifts towards the two side walls of the positioning groove 24, it will still slide down along the side wall of the positioning groove 24 to the bottom of the positioning groove 24, thereby achieving automatic adjustment of the position of the bonding wire 31.

[0079] This structure can precisely limit the bonding wire 31, avoiding uneven force on the pressure chip 30 and short circuits caused by wire deviation. At the same time, it works with the connection channel 23 to further standardize the trajectory of the bonding wire 31, improving installation stability and electrical connection reliability.

[0080] In some embodiments, a specific implementation of the base 10 described above may adopt the following approach: Figures 1 to 4 The structure shown. See also Figures 1 to 4 The base 10 also includes a pressure ring 15 pressed around the top of the diaphragm 40. Both the diaphragm 40 and the pressure ring 15 are fixed to the base 10 by laser welding to ensure that a sealed cavity is formed between the diaphragm 40 and the pressure chip 30, so as to avoid leakage of the pressure transmission medium and thus avoid deviation of the pressure measurement value.

[0081] The pressure ring 15 applies pressure evenly to the outer periphery of the diaphragm 40, which can ensure that the edge of the diaphragm 40 is in close contact with the base 10, improve the sealing performance, prevent leakage of the pressure transmission medium, and effectively prevent the diaphragm 40 from warping.

[0082] As an improved embodiment, a seal can also be installed between the pressure ring 15 and the diaphragm 40, and the seal can be compressed by the pre-tightening force to achieve a high airtightness seal.

[0083] Furthermore, the pressure ring 15 can also be connected to the base 10 via a threaded connection. Compared to welding, this connection method facilitates the disassembly of the pressure ring 15, enabling flexible replacement of the diaphragm 40 and reducing maintenance costs. With the diaphragm 40 easily replaceable, different materials or thicknesses of diaphragms 40 can be used to meet different pressure measurement requirements, resulting in greater adaptability.

[0084] In some embodiments, a specific implementation of the base 10 described above may adopt the following approach: Figures 2 to 4 The structure shown. See also Figures 2 to 4 The base 10 also has an air chamber 16 located below the pressure chamber 21, and the pressure chip 30 is located directly above the air chamber 16.

[0085] The base 10 is provided with an air hole that communicates with the air chamber 16, and the bottom of the base 10 is provided with a vent pipe 17 that communicates with the air hole.

[0086] It should be noted that the vent tube 17 and the vent can also be fixed by glass sintering to improve the airtightness of the air chamber 16.

[0087] After the pressure chip 30 is installed in the pressure chamber 21, it cooperates with the pressure chamber 21 to separate the upper and lower spaces of the pressure chip 30: that is, the top of the pressure chip 30 and the diaphragm 40 form an independent cavity (i.e., a sealed cavity), and the bottom of the pressure chip 30 and the air chamber 16 form another independent cavity. The sealed cavity is filled with silicone oil, and the air chamber 16 is connected to the outside through the vent pipe 17.

[0088] The vent tube 17 connects the lower surface of the pressure chip 30 to the outside atmosphere. At this time, the upper surface of the chip bears the measured pressure transmitted through the silicone oil, and the lower surface bears the atmospheric pressure. The pressure difference between the two is the gauge pressure value output by the sensor.

[0089] Without the vent tube 17, a sealed cavity would form on the lower surface of the chip. Temperature changes would cause the gas inside the cavity to expand and contract, generating additional parasitic pressure and severely interfering with measurement accuracy.

[0090] During the factory calibration phase, the vent tube 17 can be connected to a vacuum device to evacuate and seal the reference cavity on the lower surface of the chip. To facilitate connection to the vacuum device, a docking cavity can also be provided in the lower part of the base 10, with the pin 12 and the vent tube 17 located inside the docking cavity. The docking cavity is provided with a limiting step 110, which can correspond to the connector in the vacuum device to achieve quick connection.

[0091] To further prevent silicone oil from leaking from the vent pipe 17, a breathable and waterproof aluminum sheet can be installed at the end of the vent pipe 17 that extends into the air chamber 16, allowing gas to pass through but preventing dust and moisture from entering the interior.

[0092] To facilitate the installation of the pressure chip 30, the shape of the air cavity 16 can be different from that of the pressure cavity 21. For example, the pressure cavity 21 can be rectangular, while the air cavity 16 can be hexagonal. Ensure that the top surface of the air cavity 16 has a portion protruding from the inner wall of the pressure cavity 21 to form a limiting part. When installing the pressure chip 30, it can be placed on the limiting part first, fixed, and then the bonding wire 31 can be installed.

[0093] In some embodiments, a specific implementation of the diaphragm 40 may employ, as follows: Figures 1 to 3 and Figure 6 The structure shown. See also Figures 1 to 3 and Figure 6 The diaphragm 40 has multiple corrugations to form alternating peaks 41 and troughs 42 from the center of the diaphragm 40 outwards. The peaks 41 rise gradually from the center of the diaphragm 40 outwards, and the troughs 42 rise gradually from the center of the diaphragm 40 outwards.

[0094] It is known that the diaphragm 40 will deform when subjected to static pressure, and the deformation is transmitted to the pressure transmission medium, so that the pressure transmission medium can uniformly apply pressure to the sensitive area on the pressure chip 30 to complete the output of electrical signals.

[0095] The diaphragm 40 is essentially an elastic sensing element that converts the measured pressure into displacement or strain through its own elastic deformation. Compared to a flat diaphragm 40, a planar diaphragm 40, under pressure, concentrates stress at its edges, with lower stress in the central region, and its deformation easily enters the nonlinear stage. The corrugated diaphragm 40, through the corrugations on its surface, alters the stress distribution, allowing the stress to be evenly distributed across the corrugated structure.

[0096] In this embodiment, the diaphragm 40 can significantly improve the elastic deformation capability of the diaphragm 40, accurately sense minute changes in low-range pressure, and avoid detection blind spots caused by excessive rigidity of the diaphragm 40.

[0097] The crests 41 and troughs 42 are distributed alternately along the radial direction of the diaphragm 40, forming raised and recessed portions on the diaphragm 40 respectively. When the diaphragm 40 is compressed, the position of the crest 41 or trough 42 will undergo rapid elastic deformation without overcoming the overall rigidity of the planar diaphragm 40. Therefore, it can accurately sense extremely low pressure and has higher sensitivity.

[0098] Since the outer periphery of the diaphragm 40 is fixed to the base 10, applying pressure to the edge of the diaphragm 40 requires overcoming a portion of the force exerted by the base 10 supporting the bottom of the diaphragm 40. In this embodiment, the peaks 41 and troughs 42 gradually increase from the center outwards, meaning the sensitivity is higher the further away from the center of the diaphragm 40, resulting in more uniform deformation of the diaphragm 40 under pressure. The pressure is applied to the pressure chip 30 without deviation through the pressure transmission medium, reducing measurement errors caused by localized stress concentration.

[0099] Specifically, the corrugations on the diaphragm 40 are evenly distributed, and within a large stress range, the deformation and pressure maintain a good linear relationship, which can improve measurement accuracy without the need for complex circuit compensation.

[0100] When the pressure exceeds the rated value of the pressure sensor, the corrugations on the diaphragm 40 will flatten and deform, buffering the overload pressure through the elastic deformation of the corrugations.

[0101] In some embodiments, an improved implementation of the above-described corrugations may employ, as follows: Figures 1 to 3 and Figure 6 The structure shown. See also Figures 1 to 3 and Figure 6 The width of the multi-ring ripples gradually decreases from the center of the diaphragm 40 outwards.

[0102] The aforementioned feature that the higher the position of the peaks 41 and troughs 42 is away from the center of the diaphragm 40, combined with the fact that the corrugation width gradually decreases in the direction away from the center of the diaphragm 40, ensures that the deformation response rate of each area on the diaphragm 40 is nearly uniform, and also ensures the rigidity of the diaphragm 40 at each position. This ensures that sufficient deformation occurs under pressure, while also extending the service life of the diaphragm 40 and avoiding cracking of the diaphragm 40 caused by stress concentration.

[0103] In some embodiments, a specific implementation of the base 10 described above may adopt the following approach: Figures 2 to 5 The structure shown. See also Figures 2 to 5 The top surface of the base 10 has a cavity surface 18 located on the outer periphery of the sink 11, and a mounting surface 19 that abuts the outer periphery of the cavity surface 18. The cavity surface 18 gradually slopes downward along the direction close to the axis of the base 10 and corresponds to multiple corrugations. The mounting surface 19 is in contact with the lower surface of the diaphragm 40.

[0104] The inclined cavity surface 18 corresponds to the corrugations on the diaphragm 40. When the diaphragm 40 undergoes elastic deformation under pressure, the inclined cavity surface 18 provides ample space for the corrugations to deform, preventing rigid interference or compression between the cavity surface 18 and the corrugations, and ensuring that the diaphragm 40 deforms uniformly according to a preset pattern. Simultaneously, the inclined cavity surface 18 creates a uniform filling space between the pressure transmission medium and the pressure chip 30, without dead zones or local depressions, ensuring that the pressure transmitted by the diaphragm 40 is uniformly applied to the sensitive surface of the pressure chip 30 through the medium, avoiding pressure imbalance caused by uneven medium distribution, and reducing measurement errors.

[0105] The flat design of the mounting surface 19 reduces the positioning difficulty during diaphragm 40 assembly, achieving a tight fit between the diaphragm 40 and the base 10 without complex adjustments. The precise correspondence between the cavity surface 18 and the corrugations provides a clear positioning benchmark for the installation of the diaphragm 40, preventing misalignment between the corrugations and the cavity surface 18 caused by diaphragm 40 assembly deviation. This makes the installation position of the diaphragm 40 easier to control during sensor assembly, enhances process repeatability, effectively reduces product performance differences caused by manual assembly deviations, and improves the yield and product consistency of mass production.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A low-range oil-filled pressure sensor, characterized in that, include: The base has a groove at the top and a pin inside that extends into the groove and protrudes from the bottom of the base. A ceramic seat is located in the sink and fixedly connected to the base. The ceramic seat has a pressure chamber in the middle and a through hole corresponding to the pin. A pressure chip is located inside the pressure chamber. The pressure chip is connected to the pin via a bonding wire, so that the pressure chip can be pulled up and kept suspended in the pressure chamber. A diaphragm is fixedly connected to the top of the base, and a sealed cavity is formed between the diaphragm and the pressure chip, the sealed cavity being filled with a pressure transmission medium; The diaphragm has multiple corrugations to form alternating peaks and troughs from the center of the diaphragm outwards. The peaks rise gradually from the center of the diaphragm outwards, and the troughs rise gradually from the center of the diaphragm outwards. The width of the multiple ripples gradually decreases from the center of the diaphragm outwards. The top surface of the base has a cavity surface located on the outer periphery of the settling tank, and a mounting surface that abuts against the outer periphery of the cavity surface. The cavity surface gradually slopes downward along a direction close to the axis of the base and corresponds to multiple turns of the corrugations. The mounting surface is in contact with the lower surface of the diaphragm. The ceramic base is provided with a connecting channel for the bonding wire to pass through. The connecting channel opens upward and connects the pressure chamber and the through hole. The top of the pin is lower than the connecting channel. The sidewall of the through hole is provided with a positioning groove corresponding to the connection channel. The positioning groove is V-shaped and is used to limit the position of the bonding wire.

2. The low-range oil-filled pressure sensor as described in claim 1, characterized in that, The number of bonding wires is greater than or equal to 5, and the diameter of the bonding wires is 50±0.5μm.

3. The low-range oil-filled pressure sensor as described in claim 1, characterized in that, The pin has a solder pad at its top, and the diameter of the solder pad is smaller than the diameter of the through hole; The base has a cavity for the pins to extend out, and the base also includes a glass sintered column fixed in the cavity.

4. The low-range oil-filled pressure sensor as described in claim 1, characterized in that, The base also includes a pressure ring pressed around the top of the diaphragm.

5. The low-range oil-filled pressure sensor as described in claim 1, characterized in that, The base also has an air chamber located below the pressure chamber, and the pressure chip is located directly above the air chamber; The base is provided with an air hole communicating with the air chamber, and the bottom of the base is provided with a vent pipe communicating with the air hole.

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