Pressure sensor

Abstract

A pressure sensor comprises a first circuit and a second circuit, the first circuit comprises a power supply, a step-down element and a first filter capacitor, a first end of the step-down element is electrically connected with the power supply, a second end of the step-down element is connected with a first end of the first filter capacitor at a first node, and a second end of the first filter capacitor is grounded. The first end of the second circuit is provided with a first power port, the first node is connected with the first power port, the voltage of the power supply is directly and greatly divided and reduced through the voltage reduction element, so that the voltage is close to the application value of the second circuit and the third circuit, and meanwhile, the first filter capacitor is used for filtering. Electromagnetic interference on the pressure sensor or interference of a circuit can be reduced, measurement results of the pressure sensor are small in fluctuation, data are stable, and the height fixing function of the unmanned aerial vehicle can be achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of micro-electromechanical systems, in particular to a pressure sensor. Background Art

[0002] Pressure sensors are used on drones to calculate the drone's altitude by measuring pressure, allowing the drone to hover at a fixed height in the air.

[0003] However, when the drone is turned on, due to electromagnetic interference or interference from the line itself, the measurement results of the pressure sensor fluctuate greatly and the data is unstable, causing the drone to be unable to achieve the height-fixing function.

[0004] It should be noted that the information of the utility model in the above background technology section is only used to enhance the understanding of the background of the utility model, and therefore may include information that does not constitute prior art known to ordinary technicians in this field. Utility Model Content

[0005] The purpose of the utility model is to overcome the problems of large fluctuations in measurement results and unstable data of a pressure sensor, and to provide a pressure sensor.

[0006] According to one aspect of the present utility model, a pressure sensor is provided, which includes a first circuit, a second circuit and a third circuit. The first circuit includes a power supply, a voltage-dropping element and a filter capacitor. The filter capacitor includes a first filter capacitor. The first end of the voltage-dropping element is electrically connected to the power supply, the second end of the voltage-dropping element is electrically connected to the first end of the first filter capacitor at a first node, and the second end of the first filter capacitor is grounded; the first end of the second circuit is provided with a first power port, a first ground port, a first communication port and a second communication port. The first power port is electrically connected to the first node, the first ground port is grounded, and the first communication port and the second communication port are used to achieve communication. The second end of the second circuit is provided with a second power port, a second ground port, a first signal input port and a second signal input port; the third circuit is electrically connected to the second power port, the second ground port, the first signal input port and the second signal input port. The third circuit includes a bridge capacitor. The bridge capacitor includes two detection capacitors and two reference capacitors. The capacitance of the reference capacitor remains unchanged, and the detection capacitor is used to detect changes in pressure.

[0007] In one embodiment of the present invention, the third circuit includes a Wheatstone bridge, two detection capacitors are arranged on two opposite bridge arms of the Wheatstone bridge, two reference capacitors are arranged on the other two opposite bridge arms of the Wheatstone bridge, the power node of the Wheatstone bridge is electrically connected to the second power port, the ground node of the Wheatstone bridge is electrically connected to the second ground port, the first signal input port is electrically connected to the first signal output node of the Wheatstone bridge, and the second signal input port is electrically connected to the second signal output node of the Wheatstone bridge.

[0008] In one embodiment of the present invention, the filter capacitor also includes a second filter capacitor, the first end of the second filter capacitor is electrically connected to a second node between the first node and the power port, the second end of the second filter capacitor is grounded, and the second filter capacitor is different in size from the first filter capacitor.

[0009] In one embodiment of the present invention, the first filter capacitor is disposed close to the first power port and the first ground port.

[0010] In one embodiment of the present invention, the voltage-reducing element includes a diode or a resistor.

[0011] In one embodiment of the present invention, the resistance of the voltage-dropping element is 1-20 kΩ, and the capacitance of the filter capacitor is 2.2-30 uF.

[0012] In one embodiment of the present invention, the pressure sensor includes a circuit board, a first chip and a second chip. The first chip is bonded to the circuit board, and the second chip is formed on a side of the first chip away from the circuit board by silicon-silicon bonding.

[0013] In one embodiment of the present invention, the first chip includes a substrate, and the second circuit is arranged on the substrate; the second chip includes a first insulating layer, a first electrode, a supporting portion, a second electrode, a first conductive bonding point and a second conductive bonding point, the first insulating layer is arranged on one side of the substrate; the first electrode is arranged on the side of the first insulating layer away from the substrate; the supporting portion is arranged on the side of the first electrode away from the substrate; the second electrode is arranged on the side of the supporting portion away from the substrate; the first conductive bonding point electrically connects the first electrode and the second circuit; the second conductive bonding point electrically connects the second electrode and the second circuit.

[0014] In one embodiment of the present invention, a plurality of release holes are provided on the second electrode plate, and the release holes are located at the periphery of the support portion.

[0015] In one embodiment of the present invention, the pressure sensor further includes a composite protective layer, which blocks the release hole to form a vacuum cavity.

[0016] In one embodiment of the present invention, the composite protective layer covers a side of the second electrode plate away from the substrate.

[0017] In one embodiment of the present invention, the material of the composite protective layer includes at least one of silicon oxide and silicon nitride.

[0018] In one embodiment of the present invention, the pressure sensor further includes a housing, a welding portion is provided on the periphery of the circuit board, and the housing and the welding portion are welded together.

[0019] In one embodiment of the present invention, the circuit board has a first solder resist layer and a second solder resist layer, the first solder resist layer is provided with a first input pin, a second input pin, a third input pin, a fourth input pin and a fifth input pin, the first input pin inputs a power signal, the second input pin and the third input pin input a ground signal, the fourth input pin inputs a first communication signal, and the fifth input pin inputs a second communication signal, the second solder resist layer includes a first output pin, a second output pin, a third output pin and a fourth output pin, the first output pin is electrically connected to the first power port, the second output pin is electrically connected to the first ground port, the third output pin is electrically connected to the first communication port, and the fourth output pin is electrically connected to the second communication port.

[0020] The pressure sensor of the present invention includes a first circuit and a second circuit. The first circuit includes a power supply, a voltage-dropping element and a first filter capacitor. The first end of the voltage-dropping element is electrically connected to the power supply, the second end of the voltage-dropping element is electrically connected to the first end of the first filter capacitor at a first node, the second end of the first filter capacitor is grounded, the first end of the second circuit is provided with a first power port, and the first node is electrically connected to the first power port. The voltage of the power supply is directly and significantly divided and reduced by the voltage-dropping element, so that the voltage is close to the application value of the second circuit and the third circuit. At the same time, the first filter capacitor is used for filtering processing, which can reduce the pressure sensor from being affected by electromagnetic interference or interference of the line itself. The measurement result of the pressure sensor has small fluctuation and stable data, which can realize the altitude determination function of the drone.

[0021] It should be understood that the above general description and the following detailed description are merely exemplary and explanatory and are not restrictive of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present invention, and together with the specification, are used to explain the principles of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0023] Figure 1 When the filter capacitor includes a first filter capacitor, a circuit schematic diagram of a pressure sensor according to an embodiment of the present utility model is provided.

[0024] Figure 2 When the filter capacitor includes a first filter capacitor and a second filter capacitor, a circuit principle diagram of a pressure sensor involved in an embodiment of the present utility model.

[0025] Figure 3 Schematic diagram of a first solder resist layer according to an embodiment of the present invention.

[0026] Figure 4 It is a plan view of the first layout layer involved in an embodiment of the present utility model.

[0027] Figure 5 It is a plan view of the second layout layer involved in an embodiment of the present utility model.

[0028] Figure 6 2 is a plan view of the second solder resist layer according to an embodiment of the present invention.

[0029] Figure 7 The diagram is a plan view of a pressure sensor according to an embodiment of the present invention when a combination of a small-resistance voltage-dropping element and a large-capacitance filter capacitor is used.

[0030] Figure 8 A schematic plan view of a pressure sensor according to an embodiment of the present invention, wherein a large-resistance voltage-dropping element and a small-capacitance filter capacitor are combined.

[0031] Figure 9 It is a cross-sectional schematic diagram of the pressure sensor according to an embodiment of the present invention when the first chip and the second chip are respectively fixed to the circuit board by adhesive.

[0032] Figure 10 This is a cross-sectional schematic diagram of the pressure sensor according to an embodiment of the present invention when the first chip and the second chip are fixed by adhesive.

[0033] Figure 11 A schematic cross-sectional view of the pressure sensor according to an embodiment of the present invention is shown when a first chip is bonded to a circuit board and a second chip is formed on a side of the first chip away from the circuit board by silicon-silicon bonding.

[0034] Figure 12 Another cross-sectional schematic diagram of the pressure sensor involved in an embodiment of the present invention is when the first chip is bonded to the circuit board and the second chip is formed on the side of the first chip away from the circuit board by silicon-silicon bonding.

[0035] Description of reference numerals:

[0036] 10. First circuit, 101. Power supply, 102. Voltage-dropping element, 103. Filter capacitor, 1031. First filter capacitor, 1032. Second filter capacitor, 20. Second circuit, 201. First power port, 202. First ground port, 203. First communication port, 204. Second communication port, 205. Second power port, 206. Second ground port, 207. First signal input port, 208. Second signal input port, 30. Third circuit, 301. Detection capacitor, 302. Reference capacitor, 40. Circuit board, 401. First solder resist layer, 4011. First input pin, 4012. Second input pin, 4013. Third input pin, 4014. Fourth input pin, 4015. Fifth input pin, 4016. Capacitor pad, 4017. Resistor pad, 402. Second solder resist layer Layer, 4021, first output pin, 4022, second output pin, 4023, third output pin, 4024, fourth output pin, 403, first layout layer, 4031, first conductive portion, 4032, second conductive portion, 4033, third conductive portion, 4034, first ground portion, 404, second layout layer, 4041, fourth conductive portion, 4042, fifth conductive portion, 4043, sixth conductive portion, 4044, second ground portion, 405, welding portion, 50, first chip, 501, substrate, 60, second chip, 601, first insulating layer, 602, first electrode plate, 603, supporting portion, 604, second electrode plate, 6041, release hole, 605, first conductive bonding point, 606, second conductive bonding point, 607, composite protective layer, 608, pad, 609, vacuum chamber, 70, casing DETAILED DESCRIPTION

[0037] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent identical or similar structures, and thus their detailed description will be omitted. Furthermore, the drawings are merely schematic illustrations of the present invention and are not necessarily drawn to scale.

[0038] Although relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used herein for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It will be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via the other structure.

[0039] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0040] Pressure sensors are used on drones to calculate the drone's altitude by measuring pressure, allowing the drone to hover at a fixed altitude in the air. However, there are the following problems: 1) When the drone is turned on, due to electromagnetic interference or interference from the circuit itself, the pressure sensor's pressure measurement results fluctuate greatly and the data is unstable, making it impossible for the drone to achieve the fixed altitude function; 2) The end customer's microcontroller unit (MCU) has limited functions and does not support noise improvement; at the same time, the substrate space for assembling the pressure sensor is compact, making it impossible to design an optimized circuit to improve the impact of noise; 3) The pressure sensor is small in size and has a narrow internal space, which increases the difficulty of improving its performance.

[0041] Based on this, the embodiment of the present invention provides a pressure sensor. Figures 1 to 12As shown, the pressure sensor includes a first circuit 10, a second circuit 20 and a third circuit 30. The first circuit 10 includes a power supply 101, a voltage-dropping element 102 and a first filter capacitor 1031. The first end of the voltage-dropping element 102 is electrically connected to the power supply 101, the second end of the voltage-dropping element 102 is electrically connected to the first end of the first filter capacitor 1031 at a first node P1, and the second end of the first filter capacitor 1031 is grounded. The first end of the second circuit 20 is provided with a first power port 201, a first ground port 202, a first communication port 203 and a second communication port 204. The first power port 201 is electrically connected to the first node P1, and the first ground port 202 is electrically connected to the first communication port 203 and the second communication port 204. The ground port 202 is grounded, the first communication port 203 and the second communication port 204 are used to achieve communication, and the second end of the second circuit 20 is provided with a second power port 205, a second ground port 206, a first signal input port 207 and a second signal input port 208; the third circuit 30 is electrically connected to the second power port 205, the second ground port 206, the first signal input port 207 and the second signal input port 208, and the third circuit 30 includes a bridge capacitor, and the bridge capacitor includes two detection capacitors 301 and two reference capacitors 302. The capacitance of the reference capacitor 302 remains unchanged, and the detection capacitor 301 is used to detect changes in pressure.

[0042] The pressure sensor includes a first circuit 10 and a second circuit 20. The first circuit 10 includes a power supply 101, a voltage-dropping element 102 and a first filter capacitor 1031. The first end of the voltage-dropping element 102 is electrically connected to the power supply 101, and the second end of the voltage-dropping element 102 is electrically connected to the first end of the first filter capacitor 1031 at a first node P1. The second end of the first filter capacitor 1031 is grounded. The first end of the second circuit 20 is provided with a first power port 201, and the first node P1 is electrically connected to the first power port 201. The voltage of the power supply 101 is directly divided and reduced by the voltage-dropping element 102, so that the voltage is close to the application value of the second circuit 20 and the third circuit 30. At the same time, the first filter capacitor 1031 is used for filtering, which can reduce the pressure sensor from electromagnetic interference or interference from the line itself. The measurement results of the pressure sensor have small fluctuations and stable data, which can realize the altitude determination function of the drone.

[0043] The pressure sensor according to the embodiment of the present invention will be described in detail below with reference to specific embodiments.

[0044] like Figure 1 As shown, the pressure sensor may include a first circuit 10, a second circuit 20 and a third circuit 30. The first circuit 10 includes a power supply 101, a voltage-drop element 102 and a first filter capacitor 1031. The first end of the voltage-drop element 102 is electrically connected to the power supply 101, the second end of the voltage-drop element 102 is electrically connected to the first end of the first filter capacitor 1031 at a first node P1, and the second end of the first filter capacitor 1031 is grounded.

[0045] The first end of the second circuit 20 is provided with a first power port 201, a first ground port 202, a first communication port 203, and a second communication port 204. The first power port 201 is electrically connected to the first node P1, the first ground port 202 is grounded, and the first communication port 203 and the second communication port 204 are used for communication. The second end of the second circuit 20 is provided with a second power port 205, a second ground port 206, a first signal input port 207, and a second signal input port 208. The first filter capacitor 1031 is positioned close to the first power port 201 and the first ground port 202 to minimize the inductance and resistance of the power supply 101 path, thereby improving the filtering effect of the first circuit 10. At the same time, the first filter capacitor 1031 has a small capacitance value, a highest resonant frequency, and a small decoupling radius. Therefore, to achieve the filtering effect, it is necessary to be within the range of the effective decoupling radius.

[0046] The third circuit 30 includes a Wheatstone bridge and bridge capacitors. The bridge capacitors include two detection capacitors 301 and two reference capacitors 302. The reference capacitors 302 have a constant capacitance, and the detection capacitors 301 are used to detect changes in pressure. The two detection capacitors 301 are disposed on two opposing arms of the Wheatstone bridge, and the two reference capacitors 302 are disposed on two other opposing arms of the Wheatstone bridge. The power node P2 of the Wheatstone bridge is electrically connected to the second power port 205, the ground node P4 of the Wheatstone bridge is electrically connected to the second ground port 206, the first signal input port 207 is electrically connected to the first signal output node P3 of the Wheatstone bridge, and the second signal input port 208 is electrically connected to the second signal output node P5 of the Wheatstone bridge.

[0047] When there is no pressure, the Wheatstone bridge is in equilibrium and the output voltage is zero. When the external air pressure changes, it causes one of the plates of the detection capacitor 301 to vibrate, which can reduce the distance between the two plates of the reference capacitor 302, causing the capacitance of the detection capacitor 301 to change, thereby causing the Wheatstone bridge to become unbalanced and generating an output voltage proportional to the pressure. This converts the pressure signal into an electrical signal, which is transmitted to the second circuit 20 via the first signal input port 207 and the second signal input port 208. It can be understood that the third circuit 30 has a high sensitivity because the change in the detection capacitor 301 is directly related to the change in the distance and overlapping area between its two plates. This enables the third circuit 30 to detect very small pressure changes.

[0048] The reference capacitor 302 can provide a stable reference: the reference capacitor 302 provides a known capacitance value in the third circuit 30. The capacitance of the two reference capacitors 302 remains unchanged, so the capacitance change of the detection capacitor 301 can be obtained, which helps to ensure the measurement accuracy and stability of the pressure sensor. When the pressure change causes the capacitance of the detection capacitor 301 to change, the stability of the reference capacitor 302 helps to improve the accuracy of the measurement of the entire system. The reference capacitor 302 can provide temperature compensation: the capacitance value will be affected by temperature changes. The reference capacitor 302 can be used in a temperature compensation circuit to reduce the impact of temperature changes on the output of the pressure sensor, thereby improving the performance and reliability of the pressure sensor at different temperatures.

[0049] It should be noted that the voltage-dropping element 102 includes a diode or a resistor. When a diode is used as the voltage-dropping element 102, the diode directly divides the voltage of the power supply 101. At the same time, the diode has a voltage stabilization function, and the subsequent change in the resistance value of the first circuit 10 will not cause the voltage divided by the diode to change, making the voltage output by the diode more stable.

[0050] like Figure 2 As shown, the pressure sensor may further include a second filter capacitor 1032, wherein a first end of the second filter capacitor 1032 is electrically connected to a second node P6 between the first node P1 and the power supply 101 port, and a second end of the second filter capacitor 1032 is grounded. The second filter capacitor 1032 is different in size from the first filter capacitor 1031, and the capacitance of the first filter capacitor 1031 may be greater than the capacitance of the second filter capacitor 1032. A dual filter capacitor 103 may be connected in parallel to achieve a better filtering effect of the first circuit 10, with the larger first capacitor performing low-frequency filtering and the smaller second filter capacitor 1032 performing high-frequency filtering. The specifications of the first filter capacitor 1031 and the second filter capacitor 1032 generally differ by two orders of magnitude.

[0051] like Figures 3 to 6As shown, the pressure sensor includes a circuit board 40, the circuit board 40 has a first solder resist layer 401 and a second solder resist layer 402, the first solder resist layer 401 is provided with a first input pin 4011, a second input pin 4012, a third input pin 4013, a fourth input pin 4014 and a fifth input pin 4015, the first input pin 4011 inputs the power supply 101 signal, the second input pin 4012 and the third input pin 4013 input the ground signal, the fourth input pin 4014 inputs the first communication signal, and the fifth input pin 4015 inputs the second communication signal, the second solder resist layer 402 includes a first output pin 4021, a second output pin 4022, a third output pin 4023 and a fourth output pin 4024, the first output pin 4021 is electrically connected to the first power port 201, the second output pin 4022 is electrically connected to the first ground port 202, the third output pin 4023 is electrically connected to the first communication port 203, and the fourth output pin 4024 is electrically connected to the second communication port 204. The circuit board 40 and the second circuit 20 can be electrically connected through the above structure.

[0052] The circuit board 40 further includes a first layout layer 403 and a second layout layer 404. The first layout layer 403 includes a first conductive portion 4031, a second conductive portion 4032, a third conductive portion 4033, and a first ground portion 4034. The second layout layer 404 includes a fourth conductive portion 4041, a fifth conductive portion 4042, a sixth conductive portion 4043, and a second ground portion 4044. The first conductive portion 4031 is electrically connected to the first input pin 4011, the first ground portion 4034 is electrically connected to the second input pin 4012 and the third input pin 4013, the second conductive portion 4032 is electrically connected to the fourth input pin 4014, and the third ground portion 4044 is electrically connected to the fourth input pin 4014. The conductive portion 4033 is electrically connected to the fifth input pin 4015, the first conductive portion 4031 is electrically connected to the fourth conductive portion 4041, the second conductive portion 4032 is electrically connected to the fifth conductive portion 4042, the third conductive portion 4033 is electrically connected to the sixth conductive portion 4043, the first ground portion 4034 is electrically connected to the second ground portion 4044, the fourth conductive portion 4041 is electrically connected to the first output pin 4021, the second ground portion 4044 is electrically connected to the second output pin 4022, the fifth conductive portion 4042 is electrically connected to the third output pin 4023, and the sixth conductive portion 4043 is electrically connected to the fourth output pin 4024. The first layout layer 403, the second layout layer 404, the first solder resist layer 401, and the second solder resist layer 402 can be interconnected.

[0053] like Figure 7 and Figure 8As shown, two capacitor pads 4016 and two resistor pads 4017 are provided on the first solder resist layer 401 of the circuit board 40. One plate of the filter capacitor 103 can be welded to the two capacitor pads 4016 respectively. The voltage-reducing element 102 can be a resistor or a diode. The two electrodes of the resistor can be welded to the resistor pads 4017. Figure 7 As shown, in the first circuit 10, a combination of a small resistance voltage dropper 102 and a large capacitance filter capacitor 103 can be used to achieve filtering, which can greatly improve the performance of the pressure sensor. The specification of the large capacitance filter capacitor 103 reaches tens of μF. The size of the filter capacitor 103 of this specification is 1*0.5mm, which occupies a large space and causes the size of the pressure sensor to be larger. Figure 8 As shown, in order to reduce the size of the pressure sensor and meet the performance requirements as much as possible, the first circuit 10 adopts a combination of a large-resistance voltage-dropping element 102 and a small-capacitance filter capacitor 103. The voltage of the power supply 101 is directly divided and reduced by a large amount through the large-resistance voltage-dropping element 102, so that the voltage is close to the subsequent circuit application. At the same time, a small-capacitance filter capacitor 103 is used for filtering. However, the filtering ability of the small-capacitance filter capacitor 103 is weak and the performance is reduced. The specification of the filter capacitor 103 is generally several uF, and the size of the filter capacitor 103 is 0.6*0.3mm, which can greatly reduce the size of the pressure sensor and reduce the process difficulty.

[0054] It is recommended that the resistance value of the resistor be 1-20kΩ, and the capacitance value of the filter capacitor 103 be 2.2-30uF. Three combinations of filter capacitors 103 and resistors are provided within the above range for selection. The first specification: the capacitance value of the filter capacitor 103 is 22uF, its package size is 0402, and the resistor is 1kΩ, its package size is 01005; the second specification: the capacitance value of the filter capacitor 103 is 4.7uF, its package size is 0402, the resistor is 15kΩ, and its package size is 01005; the third specification: the capacitance value of the filter capacitor 103 is 2.2uF, its package size is 0201, the resistor is 15kΩ, and its package size is 01005. In this embodiment, the third specification is preferred, which can greatly reduce the specifications of the pressure sensor.

[0055] like Figure 9 As shown, the pressure sensor further includes a first chip 50 and a second chip 60, which are fixed to the circuit board 40 by adhesives, resulting in a larger plane area of ​​the pressure sensor. Figure 10 As shown, the first chip 50 and the second chip 60 are fixed by adhesive, resulting in a larger overall thickness of the pressure sensor. Figure 9 and Figure 10In the embodiment, the third circuit 30 and the second circuit 20 also use a wire bonding (WB) process to achieve electrical signal interconnection, and the cost of gold wire is high.

[0056] In order to further realize the miniaturization and thinness of the pressure sensor, the third circuit 30 is manufactured on the side of the second circuit 20 away from the circuit board 40 by using a complementary metal oxide semiconductor (CMOS) process. Figure 11 As shown, the first chip 50 is bonded to the circuit board 40, and the second chip 60 is formed on the side of the first chip 50 facing away from the circuit board 40 via silicon-silicon bonding. Using the first chip 50 as the substrate for the second chip 60 reduces the thickness of the second chip 60, achieving a lightweight and thin pressure sensor. The pressure sensor also includes a housing 70. A soldering portion 405 is provided on the periphery of the circuit board 40, and the housing 70 and the soldering portion 405 are soldered together.

[0057] like Figure 12 As shown, the first chip 50 includes a substrate 501, and the second circuit 20 is disposed on the substrate 501. The second chip 60 includes a first insulating layer 601 and a third circuit 30. The first insulating layer 601 is disposed on one side of the substrate 501, and the third circuit 30 is disposed on a side of the first insulating layer 601 away from the substrate 501. The first insulating layer 601 can isolate the second circuit 20 and the third circuit 30, serving both as protection for the second circuit 20 and as a substrate 501 for the third circuit 30.

[0058] like Figure 12 As shown, the third circuit 30 includes a first plate 602, a support portion 603, a second plate 604, a first conductive bonding point 605, and a second conductive bonding point 606. The first plate 602 is disposed on the side of the first insulating layer 601 away from the substrate 501, and the support portion 603 is disposed on the side of the first plate 602 away from the substrate 501. The second plate 604 is disposed on the side of the support portion 603 away from the substrate 501. The support portion 603 is primarily composed of the remaining portion of the silicon oxide sacrificial layer and serves to support the first plate 602 and the second substrate. The first conductive bonding point 605 electrically connects the first plate 602 to the second circuit 20, and the second conductive bonding point 606 electrically connects the second plate 604 to the second circuit 20.

[0059] The above structure can be used to form two detection capacitors 301 and two reference capacitors 302, and the two detection capacitors 301 and the two reference capacitors 302 are electrically connected to the second circuit 20. A plurality of release holes 6041 are provided on the second electrode 604. The release holes 6041 are located on the periphery of the support portion 603. The release holes 6041 are used to remove the portion of the silicon oxide sacrificial layer other than the support portion 603. The pressure sensor also includes a composite protective layer 607. The composite protective layer 607 covers the side of the second electrode 604 away from the substrate 501 and can protect the third circuit 30. At the same time, the composite protective layer 607 blocks the release holes 6041 to form a vacuum chamber 609. The vacuum chamber 609 is the gap between the first electrode 602 and the second electrode 604. When the first electrode 602 and the second electrode 604 form the detection capacitor 301, the movement of the second electrode 604 can change the size of the gap, thereby changing the capacitance of the detection capacitor 301. The material of the composite protective layer 607 includes at least one of silicon oxide or silicon nitride. The third circuit 30 is provided on the periphery of the circuit board 40 and may further include a soldering pad 608 . The soldering pad 608 may be interconnected with other circuits through a wire bonding process.

[0060] The present invention also provides a method for manufacturing a pressure sensor. The method may include:

[0061] Step S10, fixing the integrated chip consisting of the first chip 50 and the second chip 60 on the circuit board 40 through a die bonding process;

[0062] Step S20, interconnecting the integrated chip and the circuit board 40 through a wire bonding process;

[0063] Step S30 , soldering the filter capacitor 103 and the voltage-reducing element 102 onto the circuit board 40 through a surface mounted technology (SMT) process;

[0064] Step S40, inspecting the pressure sensor through an automated optical inspection (AOI) process;

[0065] In step S50 , the housing 70 is soldered to the soldering portion 405 of the circuit board 40 by a solder paste scribing process.

[0066] This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the present invention and include common knowledge or customary techniques in the art not disclosed herein. The description and embodiments are to be considered as exemplary only; the true scope and spirit of the present invention are indicated by the claims.

[0067] It should be understood that the present invention is not limited to the precise structure described above and shown in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A pressure sensor, characterized in that: include: A first circuit includes a power supply, a voltage-dropping element, and a filter capacitor, wherein the filter capacitor includes a first filter capacitor, a first end of the voltage-dropping element is electrically connected to the power supply, a second end of the voltage-dropping element is electrically connected to a first end of the first filter capacitor at a first node, and a second end of the first filter capacitor is grounded; a second circuit, wherein a first end of the second circuit is provided with a first power port, a first ground port, a first communication port, and a second communication port, the first power port is electrically connected to the first node, the first ground port is grounded, the first communication port and the second communication port are used to achieve communication, and a second end of the second circuit is provided with a second power port, a second ground port, a first signal input port, and a second signal input port; The third circuit is electrically connected to the second power port, the second ground port, the first signal input port and the second signal input port. The third circuit includes a bridge capacitor, and the bridge capacitor includes two detection capacitors and two reference capacitors. The capacitance of the reference capacitor is unchanged, and the detection capacitor is used to detect changes in pressure.

2. The pressure sensor according to claim 1, wherein The third circuit includes a Wheatstone bridge, the two detection capacitors are arranged on two opposite bridge arms of the Wheatstone bridge, the two reference capacitors are arranged on the other two opposite bridge arms of the Wheatstone bridge, the power node of the Wheatstone bridge is electrically connected to the second power port, the ground node of the Wheatstone bridge is electrically connected to the second ground port, the first signal input port is electrically connected to the first signal output node of the Wheatstone bridge, and the second signal input port is electrically connected to the second signal output node of the Wheatstone bridge.

3. The pressure sensor according to claim 1 or 2, characterized in that The filter capacitor also includes a second filter capacitor, a first end of the second filter capacitor is electrically connected to a second node between the first node and the power port, a second end of the second filter capacitor is grounded, and the second filter capacitor is different in size from the first filter capacitor.

4. The pressure sensor according to claim 1 or 2, characterized in that: The first filter capacitor is disposed close to the first power port and the first ground port.

5. The pressure sensor according to claim 1 or 2, characterized in that: The voltage-dropping element includes a diode or a resistor.

6. The pressure sensor according to claim 1 or 2, characterized in that: The resistance of the voltage-dropping element is 1-20 kΩ, and the capacitance of the filter capacitor is 2.2-30 uF.

7. The pressure sensor according to claim 1, wherein The pressure sensor includes a circuit board, a first chip and a second chip. The first chip is bonded to the circuit board, and the second chip is formed on a side of the first chip away from the circuit board by silicon-silicon bonding.

8. The pressure sensor according to claim 7, characterized in that The first chip includes a substrate, and the second circuit is arranged on the substrate; the second chip includes a first insulating layer, a first electrode, a supporting portion, a second electrode, a first conductive bonding point and a second conductive bonding point, the first insulating layer is arranged on one side of the substrate; the first electrode is arranged on the side of the first insulating layer away from the substrate; the supporting portion is arranged on the side of the first electrode away from the substrate; the second electrode is arranged on the side of the supporting portion away from the substrate; the first conductive bonding point electrically connects the first electrode and the second circuit; the second conductive bonding point electrically connects the second electrode and the second circuit.

9. The pressure sensor according to claim 8, characterized in that The second electrode plate is provided with a plurality of release holes, and the release holes are located at the periphery of the support portion.

10. The pressure sensor according to claim 9, characterized in that The pressure sensor further includes a composite protective layer, which blocks the release hole to form a vacuum cavity.

11. The pressure sensor according to claim 10, characterized in that The composite protective layer covers a side of the second electrode plate away from the substrate.

12. The pressure sensor according to claim 10 or 11, characterized in that: The composite protective layer is made of at least one of silicon oxide and silicon nitride.

13. The pressure sensor according to claim 7, wherein: The pressure sensor further includes a housing, a welding portion is provided on the periphery of the circuit board, and the housing and the welding portion are welded together.

14. The pressure sensor according to claim 7, wherein The circuit board has a first solder resist layer and a second solder resist layer, the first solder resist layer is provided with a first input pin, a second input pin, a third input pin, a fourth input pin and a fifth input pin, the first input pin inputs a power signal, the second input pin and the third input pin input a ground signal, the fourth input pin inputs a first communication signal, and the fifth input pin inputs a second communication signal, the second solder resist layer includes a first output pin, a second output pin, a third output pin and a fourth output pin, the first output pin is electrically connected to the first power port, the second output pin is electrically connected to the first ground port, the third output pin is electrically connected to the first communication port, and the fourth output pin is electrically connected to the second communication port.

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