Capacitive pressure sensor and manufacturing method thereof

Abstract

The invention provides a capacitive pressure sensor and a manufacturing method thereof. The sensor comprises an upper polar plate, a pressure sensing layer and a lower polar plate, the upper polar plate comprises an upper polar plate electrode; the lower polar plate comprises a lower polar plate electrode; the pressure sensing layer is located between the upper pole plate and the lower pole plate, the pressure sensing layer comprises a first pressure sensing electrode and a second pressure sensing electrode, and the first pressure sensing electrode and the second pressure sensing electrode are located on the front face and the back face of the pressure sensing layer respectively; the first voltage sensing electrode and the upper pole plate electrode are oppositely arranged to form a first capacitor, and the second voltage sensing electrode and the lower pole plate electrode are oppositely arranged to form a second capacitor. Differential capacitors, namely a first capacitor and a second capacitor, are adopted. When external pressure acts on the pressure sensing layer, the capacitance values of the two capacitors change at the same time, but the change directions are opposite. By means of the design, the sensitivity of the sensor is improved, and part of errors caused by temperature changes or other non-pressure factors can be offset.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a capacitive pressure sensor and a manufacturing method thereof. Background Art

[0002] Capacitive pressure sensors measure pressure based on changes in capacitance. When the pressure applied to the sensor changes, the structure of the sensor will deform slightly, resulting in a change in the capacitance value, thereby achieving pressure measurement. Capacitive pressure sensors usually use a metal film or a gold-plated film as an electrode of the capacitor. When the electrode plate deforms due to pressure, the capacitance formed between the electrode plate and the fixed electrode changes. Through the measurement circuit, an electrical signal with a certain relationship with the voltage can be output, thereby achieving pressure measurement. Traditional pressure sensors cannot effectively offset errors caused by non-pressure factors such as temperature changes and electromagnetic interference during the measurement process, thereby reducing the accuracy of the measurement results. Summary of the invention

[0003] The present invention provides a capacitive pressure sensor and a manufacturing method thereof, which are used to solve the defect of low measurement accuracy of pressure sensors in the prior art. The technical solution proposed by the present invention is as follows: In a first aspect, the present invention provides a capacitive pressure sensor, comprising: an upper electrode plate, a pressure-sensitive layer and a lower electrode plate; The upper plate includes an upper plate electrode, and the lower plate includes a lower plate electrode; The pressure-sensitive layer is located between the upper electrode plate and the lower electrode plate, and the pressure-sensitive layer includes a first pressure-sensitive electrode and a second pressure-sensitive electrode, and the first pressure-sensitive electrode and the second pressure-sensitive electrode are located on the front side and the back side of the pressure-sensitive layer respectively; The first pressure-sensitive electrode and the upper plate electrode are arranged opposite to each other to form a first capacitor, and the second pressure-sensitive electrode and the lower plate electrode are arranged opposite to each other to form a second capacitor.

[0004] Optionally, the upper electrode plate is provided with a thinning region in a peripheral region of the upper electrode plate electrode, and the lower electrode plate is provided with a thinning region in a peripheral region of the lower electrode plate electrode.

[0005] Optionally, the upper electrode plate is provided with an upper electrode lead-out terminal, and the upper electrode lead-out terminal is connected to the upper electrode plate electrode; The lower electrode plate is provided with a lower electrode lead-out terminal, and the lower electrode lead-out terminal is connected to the lower electrode plate electrode; The pressure-sensitive layer is provided with a first lead-out end facing the upper electrode lead-out end, and the first lead-out end is connected to the first pressure-sensitive electrode; The pressure-sensitive layer is provided with a second lead-out end facing the lower electrode lead-out end; the second lead-out end is connected to the second pressure-sensitive electrode.

[0006] Optionally, the upper electrode plate, the pressure-sensitive layer and the lower electrode plate are correspondingly provided with direct bonding areas.

[0007] Optionally, the upper electrode plate, the pressure-sensitive layer and the lower electrode plate are correspondingly provided with gold-gold bonding areas.

[0008] Optionally, overflow grooves are provided on the edges of the upper electrode plate and the lower electrode plate.

[0009] Optionally, the upper electrode plate, the pressure-sensitive layer and the substrate of the lower electrode plate are made of the same material.

[0010] Optionally, the substrates of the upper electrode plate, the pressure-sensitive layer and the lower electrode plate are made of quartz crystal, glass or high-resistance silicon wafer.

[0011] In a second aspect, the present invention provides a method for manufacturing a capacitive pressure sensor as described in the first aspect, comprising: forming an upper plate electrode on the upper plate; forming a lower plate electrode on the lower plate; Forming a first pressure-sensitive electrode and a second pressure-sensitive electrode on the front and back surfaces of the pressure-sensitive layer respectively; The upper plate, the pressure-sensitive layer and the lower plate are connected so that the first pressure-sensitive electrode and the upper plate electrode are arranged opposite to each other to form a first capacitor, and the second pressure-sensitive electrode and the lower plate electrode are arranged opposite to each other to form a second capacitor.

[0012] Optionally, the method further comprises: The upper plate is thinned in the peripheral area of ​​the upper electrode to form a thinned area, and the lower plate is thinned in the peripheral area of ​​the lower plate electrode to form a thinned area.

[0013] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows: The capacitive pressure sensor provided by the present invention adopts a differential capacitor design, namely a first capacitor and a second capacitor. When external pressure acts on the pressure-sensitive layer, the capacitance values ​​of the two capacitors will change at the same time, but the directions of change are opposite. This design not only improves the sensitivity of the sensor, but also helps to offset some errors caused by temperature changes or other non-pressure factors. The capacitive pressure sensor works based on the capacitance principle and has high measurement accuracy. Since the change in capacitance is inversely proportional to the distance between the electrodes, even a small pressure change will cause a significant change in the capacitance value. This high sensitivity enables the sensor to accurately measure pressure. The capacitive pressure sensor has a fast dynamic response speed. When the external pressure changes, the pressure-sensitive layer will deform rapidly, resulting in a change in the capacitance value. This fast response speed enables the sensor to quickly capture pressure changes and output corresponding signals.

[0014] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0015] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a schematic structural diagram of the upper electrode plate and the corresponding surface of the pressure-sensitive layer provided by the present invention.

[0018] Figure 2 It is a schematic diagram of the pressure-sensitive layer structure provided by the present invention.

[0019] Figure 3 It is a schematic diagram of the reverse structure of the upper electrode plate provided by the present invention.

[0020] Figure 4 It is a schematic diagram of the structure of the lower electrode plate provided by the present invention.

[0021] Reference numerals: 1. Upper plate; 2. Pressure-sensitive layer; 3. Lower plate; 4. Upper plate electrode; 5. Lower plate electrode; 6. Pressure-sensitive electrode; 7. Thinning area; 8. Upper electrode lead-out terminal; 9. Lower electrode lead-out terminal; 10. First lead-out terminal; 11. Second lead-out terminal; 12. Direct bonding area; 13. Gold-gold bonding area; 14. Overflow groove; 15. Front and back electrode conductive through hole. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Combine the following Figure 1-Figure 4A capacitive pressure sensor of the present invention is described.

[0024] Reference Figure 1 As shown, the capacitive pressure sensor adopts a three-layer structure design, and outputs the pressure difference change by monitoring the capacitance difference between the upper and lower plates and the middle pressure-sensitive layer 2. The sensor includes: an upper plate 1, a pressure-sensitive layer 2 and a lower plate 3. The upper plate 1 includes an upper plate electrode 4, and the lower plate 3 includes a lower plate electrode 5.

[0025] The pressure-sensitive layer 2 is located between the upper electrode plate 1 and the lower electrode plate 3. Figure 2 As shown, the pressure-sensitive layer 2 includes two pressure-sensitive electrodes 6, namely a first pressure-sensitive electrode and a second pressure-sensitive electrode, which are respectively located on the front and back sides of the pressure-sensitive layer 2. The first pressure-sensitive electrode is arranged opposite to the upper plate electrode 4 to form a first capacitor, and the second pressure-sensitive electrode is arranged opposite to the lower plate electrode 5 to form a second capacitor.

[0026] The upper plate 1 is an important component of the capacitive pressure sensor, and the upper plate 1 includes an upper plate electrode 4. The upper plate electrode 4 is a plate of a capacitor, and together with the first pressure-sensitive electrode in the pressure-sensitive layer 2, forms a first capacitor.

[0027] The pressure-sensitive layer 2 is made of a material with excellent piezoresistive properties. When external pressure acts on the pressure-sensitive layer 2, it will deform. This deformation will cause the distance between the first pressure-sensitive electrode and the upper plate electrode 4 to change, and the distance between the second pressure-sensitive electrode and the lower plate electrode 5 will also change accordingly. This change in distance will directly lead to a change in capacitance, thereby achieving pressure measurement.

[0028] The lower plate 3 is another important component of the capacitive pressure sensor, including a lower plate electrode 5. This lower plate electrode 5 and the second pressure-sensitive electrode in the pressure-sensitive layer 2 together constitute a second capacitor. Like the upper plate 1, the design and material selection of the lower plate 3 also need to take into account conductivity and mechanical stability. At the same time, in order to ensure the accuracy of the measurement, the lower plate 3 also needs to maintain a certain gap with the pressure-sensitive layer 2 to avoid abnormal changes in the capacitance value caused by direct contact.

[0029] The capacitive pressure sensor provided by the present invention adopts a differential capacitor design, namely a first capacitor and a second capacitor. When external pressure acts on the pressure-sensitive layer 2, the capacitance values ​​of the two capacitors will change at the same time, but the directions of change are opposite. This design not only improves the sensitivity of the sensor, but also helps to offset some errors caused by temperature changes or other non-pressure factors. The capacitive pressure sensor works based on the capacitance principle and has high measurement accuracy. Since the change in capacitance is inversely proportional to the distance between the electrodes, even a small pressure change will cause a significant change in the capacitance value. This high sensitivity enables the sensor to achieve accurate measurement of pressure. The capacitive pressure sensor has a fast dynamic response speed. When the external pressure changes, the pressure-sensitive layer 2 will deform rapidly, resulting in a change in the capacitance value. This fast response speed enables the sensor to quickly capture pressure changes and output corresponding signals.

[0030] In an optional embodiment, the upper plate 1 is provided with a thinning region 7 in a peripheral region of the upper plate electrode 4 , and the lower plate 3 is provided with a thinning region 7 in a peripheral region of the lower plate electrode 5 .

[0031] The upper plate electrode 4 can be located at the center or near the center of the upper plate 1 to form a capacitor with the first pressure-sensitive electrode of the pressure-sensitive layer 2. One or more thinning areas 7 are designed around the outer periphery of the upper plate electrode 4. These thinning areas 7 are achieved by reducing the thickness of the upper plate 1 in this area, which can be achieved by machining, chemical etching, or laser cutting. The shape and size of the thinning area 7 can be adjusted according to specific design requirements, such as being designed as a ring or other shape that can evenly distribute stress.

[0032] The lower plate electrode 5 is also located at the center or near the center of the lower plate 3, and forms a capacitor with the second pressure-sensitive electrode of the pressure-sensitive layer 2. Similar to the upper plate 1, the lower plate 3 is also provided with a thinning area 7 at the periphery of its electrode. These thinning areas 7 reduce the overall stress concentration by reducing the thickness of the lower plate 3 in this area. For example, the area can be thinned by a thinning process such as grinding and polishing to adjust the initial gap of the capacitor and improve the sensitivity of the sensor.

[0033] The present invention helps to optimize the stress distribution in the upper plate 1 and the lower plate 3 by setting the thinning area 7. Under the action of pressure, the thinning area 7 can be deformed more easily, thereby absorbing and dispersing stress, reducing stress concentration and the generation of residual stress. This helps to improve the stability and durability of the sensor, especially when experiencing extreme conditions such as temperature changes and pressure fluctuations. By optimizing the stress distribution, the thinning area 7 can also improve the sensitivity of the sensor. When external pressure acts on the pressure-sensitive layer 2, the thinning area 7 can more easily respond to and transmit pressure changes, resulting in a significant change in the capacitance value. This enables the sensor to measure small pressure changes more accurately, improving the resolution and accuracy of the measurement. When the temperature changes, the thinning area 7 helps to reduce the thermal stress caused by the mismatch of the thermal expansion coefficient of the material. Due to the presence of the thinning area 7, the upper plate 1 and the lower plate 3 can expand and contract more evenly when the temperature changes, thereby reducing the residual stress caused by thermal stress. This helps to maintain the measurement accuracy and stability of the sensor over the full temperature range.

[0034] In an alternative embodiment, referring to Figure 3 As shown, the upper electrode plate 1 is provided with an upper electrode lead-out terminal 8, the lower electrode plate 3 is provided with a lower electrode lead-out terminal 9, the pressure-sensitive layer 2 is provided with a first lead-out terminal 10 facing the upper electrode lead-out terminal 8, and the pressure-sensitive layer 2 is provided with a second lead-out terminal 11 facing the lower electrode lead-out terminal 9.

[0035] The upper electrode lead-out terminal 8 is arranged on the surface or edge of the upper plate 1. This lead-out terminal can be a conductive metal sheet or pin, which is used to export the charge signal of the upper plate electrode 4 to an external circuit. The upper electrode lead-out terminal 8 is electrically connected to the upper plate electrode 4 through an internal conductive structure (such as a metal wire or a film) to ensure that the charge signal can be smoothly transmitted. The lower plate 3 serves as another plate of the capacitor, and a lower electrode lead-out terminal 9 is also arranged on its surface or edge. The function of this lead-out terminal is similar to that of the upper electrode lead-out terminal 8, and is used to export the charge signal of the lower plate electrode 5 to an external circuit. The lower electrode lead-out terminal 9 is also electrically connected to the lower plate electrode 5 through an internal conductive structure.

[0036] The pressure-sensitive layer 2 is located between the upper plate 1 and the lower plate 3 and is a key component of the sensor for sensing pressure changes. In order to export the capacitance change signal on the pressure-sensitive layer 2 to the external circuit, a first lead-out terminal 10 is provided on the front side (the side facing the upper plate 1) of the pressure-sensitive layer 2, and a second lead-out terminal 11 is provided on the back side (the side facing the lower plate 3). The first lead-out terminal 10 and the second lead-out terminal 11 can be electrically connected to the first pressure-sensitive electrode and the second pressure-sensitive electrode through the conductive structure (such as metal film or conductive ink) inside the pressure-sensitive layer 2.

[0037] The present invention provides an upper electrode lead-out terminal 8, a lower electrode lead-out terminal 9, a first lead-out terminal 10 and a second lead-out terminal 11, so that the sensor can conveniently export the capacitance change signal on the upper electrode plate 1, the lower electrode plate 3 and the pressure-sensitive layer 2 to an external circuit for processing and analysis. This makes the output signal of the sensor more stable and reliable, and improves the accuracy and precision of the measurement. Those skilled in the art can select the appropriate lead-out terminal position and quantity according to specific application requirements to meet different circuit connection and signal transmission requirements. The standardized design of the lead-out terminal makes the sensor easier to integrate and package with other electronic components. This helps to reduce the production cost of the sensor, improve production efficiency, and make it more suitable for various electronic devices and systems. Through a reasonable lead-out terminal layout and signal transmission path design, the sensor can more effectively resist the influence of external electromagnetic interference and noise. This helps to ensure that the sensor can still maintain stable measurement performance in a complex environment. The setting of the lead-out terminal also makes it more convenient to repair or replace the sensor. When the sensor fails or needs to be upgraded, the technician can replace or repair the lead-out terminal and its related components through a simple plug-in operation without disassembling or redesigning the entire sensor.

[0038] In an alternative embodiment, referring to Figure 3 and Figure 4 As shown, the upper electrode plate 1 , the pressure-sensitive layer 2 and the lower electrode plate 3 are correspondingly provided with direct bonding areas 12 .

[0039] The above-mentioned direct bonding area 12 refers to a tightly bonded area formed by a specific process means (such as direct bonding technology) between the upper plate 1, the pressure-sensitive layer 2 and the lower plate 3. These areas ensure stable connection and charge transfer between the layers of the sensor. The direct bonding area 12 of the upper plate 1 is located on its lower surface or edge and is used for direct bonding with the pressure-sensitive layer 2. This area is specially treated to ensure good bonding and charge transfer with the pressure-sensitive layer 2.

[0040] The direct bonding area 12 of the pressure-sensitive layer 2 is located on its upper and lower surfaces, and is directly bonded to the upper electrode plate 1 and the lower electrode plate 3. These areas have appropriate thickness and conductivity to ensure that charges can be smoothly transferred between the upper electrode plate 1, the pressure-sensitive layer 2 and the lower electrode plate 3.

[0041] The direct bonding area 12 of the lower electrode plate 3 is located on its upper surface or edge, and is used for direct bonding with the pressure-sensitive layer 2. Similar to the upper electrode plate 1, this area is also specially processed to ensure close bonding and charge transfer with the pressure-sensitive layer 2.

[0042] The direct bonding area 12 of the present invention directly connects the layers together through a specific process without the use of auxiliary materials such as glue or glass paste. The direct bonding area 12 has a higher connection strength and can withstand greater mechanical stress and thermal stress. Since the use of auxiliary materials is avoided, the thermal stress problem caused by material differences is reduced, and the stability and detection accuracy of the sensor are further improved. Moreover, the direct bonding area 12 ensures the close bonding between the layers of the sensor and reduces the performance degradation caused by looseness or delamination. This structure enables the sensor to maintain stable measurement performance during long-term use. The direct bonding area 12 enhances the connection strength between the layers of the sensor and improves the impact and vibration resistance of the sensor. This enables the sensor to maintain stable measurement performance in harsh environments (such as high temperature, high pressure, strong vibration, etc.). The direct bonding area 12 provides a channel for the transfer of charge between the upper plate 1, the pressure-sensitive layer 2 and the lower plate 3, reducing the loss during the charge transfer process. This helps to improve the sensitivity and response speed of the sensor, enabling it to measure pressure changes more accurately. Direct bonding technology simplifies the manufacturing process of the sensor and reduces errors and failures introduced by process steps such as welding or pasting. This helps reduce production costs, improves production efficiency, and makes the sensor easier to mass produce. If the sensor fails or needs repair, the direct bonding area 12 makes it easier to separate and re-bond the layers. This helps reduce maintenance costs and improves the maintainability and service life of the sensor.

[0043] In an alternative embodiment, referring to Figure 3 and Figure 4 As shown, the upper electrode plate 1 , the pressure-sensitive layer 2 and the lower electrode plate 3 are correspondingly provided with gold-gold bonding areas 13 .

[0044] The above-mentioned gold-gold bonding area 13 refers to a tightly connected area formed by the mutual diffusion and bonding of metal (gold) between the upper electrode plate 1, the pressure-sensitive layer 2 and the lower electrode plate 3. These areas ensure the stable connection and high conductivity between the layers of the sensor, and are the key to the stable performance of the sensor. During the manufacturing process, it is necessary to deposit a layer of gold or other highly conductive metal at the corresponding positions of the upper electrode plate 1, the pressure-sensitive layer 2 and the lower electrode plate 3. Then, these metal layers are contacted and tightly bonded to each other through specific process means (such as hot pressing bonding, ultrasonic bonding, etc.) to form a gold-gold bonding area 13. The gold-gold bonding area 13 has excellent conductivity and stability, which can ensure that the sensor maintains stable measurement performance during long-term use. In addition, the gold-gold bonding area 13 also has good corrosion resistance and oxidation resistance, which can resist the influence of harsh environment and extend the service life of the sensor.

[0045] When the upper electrode plate 1 is bonded to the pressure-sensitive layer 2, the direct bonding area 12 is aligned, the gold-gold bonding area 13 is aligned, and direct bonding completes electrical conduction and structural fixed connection. When the lower electrode plate 3 is bonded to the upper electrode plate 1 and the pressure-sensitive layer 2 assembly, the direct bonding area 12 is aligned, the gold-gold bonding area 13 is aligned, and direct bonding completes electrical conduction and structural fixed connection.

[0046] The present invention ensures close connection and high conductivity between the layers of the sensor by setting the gold-gold bonding area 13, and reduces the loss and interference in the charge transfer process. This helps to improve the sensitivity and response speed of the sensor, so that it can measure pressure changes more accurately. The gold-gold bonding area 13 has excellent stability and reliability, and can withstand various mechanical stresses and thermal stresses during long-term use. This enables the sensor to maintain stable measurement performance in harsh environments, improving the reliability and service life of the sensor. The gold-gold bonding technology simplifies the manufacturing process of the sensor and reduces errors and faults introduced by process steps such as welding or pasting. This helps to reduce production costs, improve production efficiency, and make the sensor easier to mass produce. The gold-gold bonding area 13 also enhances the connection strength between the layers of the sensor and improves the impact and vibration resistance of the sensor. This enables the sensor to maintain stable measurement performance in harsh environments (such as high temperature, high pressure, strong vibration, etc.).

[0047] In an alternative embodiment, referring to Figure 1 and Figure 4 As shown, the edges of the upper plate 1 and the lower plate 3 are both provided with overflow grooves 14. The overflow grooves 14 refer to grooves or channels provided at the edges of the upper plate 1 and the lower plate 3, which are used to accommodate excess materials that may be generated during the gold-gold bonding process to ensure the bonding quality. They are also used to accommodate and discharge excess liquid or gas that may accumulate at the edges of the plates. These grooves have appropriate width and depth to ensure that excess materials can be effectively collected and discharged without interfering with the normal operation of the sensor.

[0048] The overflow groove 14 is arranged at the edge of the upper plate 1 and the lower plate 3 and is evenly distributed along the periphery of the plate. This layout helps to ensure that any excess material accumulated on the edge of the plate can be discharged in time during the operation of the sensor, thereby avoiding adverse effects on the measurement performance of the sensor. When the sensor is in operation, some gas may penetrate to the edge of the plate. The overflow groove 14 can accommodate these excess materials and prevent them from entering the sensitive area of ​​the sensor. Through appropriate discharge channels or mechanisms, the overflow groove 14 can discharge the accumulated excess material to the outside of the sensor, thereby keeping the inside of the sensor clean and dry. The presence of the overflow groove 14 helps to prevent the excess material from interfering with the sensitive area of ​​the sensor, thereby ensuring that the sensor can accurately measure pressure changes. This helps to improve the measurement accuracy and stability of the sensor, so that it can perform well in various application scenarios. By discharging the accumulated excess material in time, the overflow groove 14 can reduce the risk of failure caused by the accumulation of liquid or gas inside the sensor. This helps to extend the service life of the sensor and improve its reliability and durability.

[0049] In an optional embodiment, the substrates of the upper electrode plate 1, the pressure-sensitive layer 2 and the lower electrode plate 3 are made of the same material. The substrate material needs to be a non-conductive material with high mechanical strength and good thermal stability to ensure that the sensor can maintain stable performance under various working conditions.

[0050] By setting the same base material, performance fluctuations caused by material differences are avoided. This consistency not only helps to improve the measurement accuracy, stability and response speed of the sensor, but also reduces the failure rate of the sensor during long-term use. Since the materials between the layers are the same, the combination between them is tighter and more reliable, and can more effectively resist the influence of various mechanical stresses and thermal stresses. More importantly, the use of the same base material completely overcomes the defect of traditional pressure sensors that residual stress exists due to mismatched thermal expansion coefficients, which in turn affects the detection accuracy over the full temperature range. When the temperature changes, since the thermal expansion coefficients of the layers are consistent, they can expand or contract synchronously, thereby significantly reducing the generation of residual stress. This improvement greatly improves the detection accuracy of the sensor, enabling it to maintain excellent performance under various temperature and pressure conditions.

[0051] When the sensor fails or needs repair, using the same substrate material can make repair and replacement easier and more convenient. Using the same substrate material can simplify the manufacturing process and reduce production costs. Since there is no need to prepare different equipment and process parameters for different materials, a lot of time and resources can be saved. The same substrate material allows the sensor to better adapt to various working environments and conditions. Whether in high temperature, high pressure, strong magnetic field or corrosive environment, the sensor can maintain stable performance to meet various application requirements.

[0052] In an optional embodiment, the substrates of the upper electrode plate 1 , the pressure-sensitive layer 2 and the lower electrode plate 3 are made of quartz crystal, glass or high-resistance silicon wafer.

[0053] Quartz crystal is a crystalline material with piezoelectric effect. When subjected to external force, polarization will occur inside it and opposite charges will be generated on the surface. In capacitive pressure sensors, quartz crystal is used as the base material to sense pressure changes through its piezoelectric effect and convert them into electrical signals. The piezoelectric effect of quartz crystal makes the sensor extremely sensitive to pressure changes and can accurately measure tiny pressure fluctuations. Quartz crystal has good chemical inertness and physical stability, and can maintain stable performance in various harsh environments.

[0054] Glass is an inorganic non-metallic material with good heat resistance and chemical stability. In capacitive pressure sensors, glass is used as the substrate material to maintain stable performance in high temperature environments and is suitable for some special application scenarios. High-resistance silicon wafers have good mechanical strength. Silicon wafers have mature processing technology, and precise microchannel structures can be obtained through processes such as wet etching to meet the sensor's requirements for microchannel size and shape. High-resistance silicon wafers can remain stable under high threshold acceleration loads, meeting the requirements of application environments such as microfluidic inertial switches. Silicon wafers can be integrated with other semiconductor devices and circuits to achieve miniaturization and intelligence of sensors.

[0055] Those skilled in the art can select specific materials according to actual needs. For example, quartz crystals can be used for applications that require high sensitivity and frequency stability. Glass can be used for applications that require transparency and low cost, but additional protection measures may be required in high temperature or high pressure environments. High-resistance silicon wafers can be used for applications that require precise processing and high integration.

[0056] In an optional embodiment, the upper electrode plate 1 is provided with a conductive through hole 15 for connecting the positive and negative electrodes. The upper electrode plate 1 itself has a positive electrode and a negative electrode, and a metal electrode is also provided on the side wall of the conductive through hole. By means of this conductive through hole, an electrical connection between the positive and negative electrodes of the upper electrode plate 1 can be achieved. The upper electrode plate is made of a non-conductive material, and its surface is covered with an insulating layer to isolate the electrodes. Through holes connected to the electrodes are formed at locations where the electrodes need to be connected. These through holes allow current to flow freely between the positive and negative electrodes. These through holes can be designed to be circular, square or other shapes, depending on the design and application requirements of the sensor.

[0057] The present invention allows current to flow freely between the positive and negative electrodes through the design of the through-holes for conducting the positive and negative electrodes, thereby improving the current transmission efficiency. This helps to reduce the power consumption of the sensor and improve its response speed. By directly connecting the electrode to the upper plate and using the through-holes for current transmission, the structural stability of the sensor can be enhanced. This design helps to reduce the problem of sensor failure caused by loose or falling electrodes. The design of the through-holes for conducting the positive and negative electrodes simplifies the manufacturing process of the sensor. Traditional manufacturing processes may require complex welding or connection steps to ensure the connection between the electrode and the upper plate. However, by designing the through-holes, the electrode can be directly connected to the upper plate, thereby reducing the steps and costs in the manufacturing process. Since the current is transmitted more smoothly between the positive and negative electrodes, the measurement accuracy of the sensor will also be improved. This helps to ensure that the sensor can provide accurate and reliable measurement results under various working conditions.

[0058] The following is a description of a method for manufacturing a capacitive pressure sensor provided by the present invention. The method for manufacturing the capacitive pressure sensor described below and the capacitive pressure sensor described above can refer to each other.

[0059] The present invention provides a method for manufacturing a capacitive pressure sensor, comprising: S101, forming an upper plate electrode 4 on the upper plate 1. Select a suitable substrate material (such as quartz crystal, glass or high-resistance silicon wafer) as the substrate of the upper plate 1. Form the upper plate electrode 4 on the substrate by film deposition, evaporation or other appropriate methods. The electrode material can be a metal, such as silver, copper, aluminum, gold, etc., and the specific selection depends on the required conductivity and stability.

[0060] S102, forming a lower plate electrode 5 on the lower plate 3. Similarly, a suitable substrate material is selected as the substrate of the lower plate 3. The lower plate electrode 5 is formed on the substrate in a similar manner to the formation of the upper plate electrode 4.

[0061] S103, forming a first pressure-sensitive electrode and a second pressure-sensitive electrode on the front and back surfaces of the pressure-sensitive layer 2, respectively. Select a material with appropriate elasticity and conductivity as the pressure-sensitive layer 2. The material of the pressure-sensitive layer 2 should be able to respond to pressure changes and produce corresponding deformation. Form a first pressure-sensitive electrode and a second pressure-sensitive electrode on the front and back surfaces of the pressure-sensitive layer 2, respectively. These electrodes are arranged opposite to the upper plate electrode 4 and the lower plate electrode 5 to form a capacitor structure.

[0062] S104, connect the upper plate 1, the pressure-sensitive layer 2 and the lower plate 3 so that the first pressure-sensitive electrode and the upper plate electrode 4 are arranged relative to each other to form a first capacitor, and the second pressure-sensitive electrode and the lower plate electrode 5 are arranged relative to each other to form a second capacitor. Specifically, the upper plate 1, the pressure-sensitive layer 2 and the lower plate 3 are precisely aligned in a predetermined order and position. Use direct bonding, welding or other appropriate connection methods to connect the layers together. Ensure that the first pressure-sensitive electrode and the upper plate electrode 4 are arranged relative to each other to form a first capacitor, and the second pressure-sensitive electrode and the lower plate electrode 5 are arranged relative to each other to form a second capacitor. Perform necessary cleaning, testing and calibration on the connected sensor to ensure that its performance and stability meet the design requirements. As needed, accessories such as protective shells and connectors can be installed on the sensor for easy use and maintenance.

[0063] The capacitive pressure sensor of the present invention reflects the change of pressure by measuring the change of capacitance value. Since there is a good linear relationship between the change of capacitance value and pressure, high-precision measurement can be achieved. The pressure-sensing layer 2 is very sensitive to pressure changes, and even a small pressure change can cause a significant change in the capacitance value. This makes the sensor highly sensitive and can detect small pressure fluctuations. Due to the use of connection methods such as direct bonding, the thermal stress problem caused by the mismatch between the auxiliary materials and the pressure-sensing layer 2 and the electrode layer materials in traditional sensors is avoided. This improves the stability and reliability of the sensor, enabling it to work for a long time in various harsh environments.

[0064] Optionally, the method further comprises: S105 , thinning the upper electrode plate 1 in the peripheral area of ​​the upper electrode to form a thinned area 7 , and thinning the lower electrode plate in the peripheral area of ​​the lower electrode plate to form a thinned area 7 .

[0065] First, make sure that the upper electrode plate 1 and the lower electrode plate 3 have been manufactured according to the design requirements and that the electrodes have been correctly installed. Prepare thinning tools, such as high-speed angle grinders, sandpaper, erasers, cleaning fluid, etc. Use a high-speed angle grinder with sandpaper to thin the peripheral area of ​​the upper electrode plate 1. Pay attention to controlling the strength and speed of thinning to avoid damaging the electrode or causing unnecessary deformation. After thinning to the required thickness, wipe it clean with cleaning fluid to ensure that there is no residue on the surface. Also use a high-speed angle grinder with sandpaper to thin the peripheral area of ​​the lower electrode plate 3. As with the upper electrode plate 1, pay attention to controlling the strength and speed of thinning and keep the surface clean. Perform a quality inspection on the thinned upper electrode plate 1 and the lower electrode plate 3 to ensure that the thickness and shape of the thinning area 7 meet the design requirements. Check whether the electrode is intact and whether the connection between the thinning area 7 and the electrode is firm.

[0066] By forming the thinning area 7 through a thinning process, the stress distribution inside the sensor can be optimized. Under pressure, the thinning area 7 can disperse and withstand stress more effectively, thereby improving the stability and durability of the sensor. The presence of the thinning area 7 makes it easier for the sensor to deform when under pressure, thereby improving the sensitivity of the sensor. This means that the sensor can more accurately sense small pressure changes and respond accordingly. Due to the presence of the thinning area 7, the sensor can better adapt to thermal expansion and contraction when the temperature changes. This helps to reduce the thermal stress caused by temperature changes and further improves the stability and reliability of the sensor. By precisely controlling the strength and speed of thinning, precise control of the thickness and shape of the thinning area 7 can be achieved. This helps to improve the manufacturing accuracy and consistency of the sensor.

[0067] The substrate of the upper plate 1, the pressure-sensitive layer 2 and the lower plate 3 is a quartz substrate. The method also includes: using laser technology to accurately punch the required small holes on the upper plate 1, which are usually used for subsequent electrode connection or pressure sensing. Laser drilling has the characteristics of high precision and high efficiency, and can ensure that the size, position and shape of the holes meet the design requirements. Taking quartz as an example, the substrate of the upper plate 1 is cleaned with an appropriate cleaning agent (such as anhydrous ethanol, deionized water, etc.) to remove dirt, grease and other impurities on the surface. The cleaning process requires strict control of temperature and time to ensure that the quartz substrate is not damaged or its performance is not affected. On the cleaned quartz substrate, a layer of gold film is prepared by sputtering coating technology to form a gold-gold bonding area 13. Sputtering coating has excellent adhesion and uniformity, which can ensure a firm connection between the gold film and the quartz substrate. The gold-gold bonding area 13 is used for electrode connection or sensor packaging to ensure the stability and reliability of the sensor.

[0068] Laser technology is also used to accurately punch the required small holes on the pressure-sensitive layer 2. These holes are used for connection or sensing between the pressure-sensitive layer 2 and the upper and lower plates. The quartz substrate is cleaned to remove dirt and impurities on the surface to ensure that the performance of the pressure-sensitive layer 2 is not affected. A layer of gold film is prepared on the cleaned quartz substrate to form a gold-gold bonding area 13 to ensure a firm connection between the pressure-sensitive layer 2 and the upper and lower plates.

[0069] The lower plate 3 is cleaned thoroughly to remove dirt, grease and other impurities on the surface. This helps to ensure the quality and adhesion of the subsequent sputtering coating. A layer of gold film is prepared on the cleaned lower plate 3 to form the gold-gold bonding area 13. Similar to the upper plate 1 and the pressure-sensitive layer 2, this step ensures a strong connection and stability between the various parts of the sensor.

[0070] The present invention uses high-precision laser drilling technology to ensure that the size, position and shape of the hole meet the design requirements, thereby improving the accuracy and reliability of the sensor. Sputtering coating technology has excellent adhesion and uniformity, ensuring the quality and stability of the gold-gold bonding area 13. Through a strict cleaning process, the dirt and impurities on the surface of the upper electrode plate 1, the pressure-sensitive layer 2 and the lower electrode plate 3 are removed, thereby improving the performance and stability of the sensor. The preparation of the gold-gold bonding area 13 ensures a firm connection between the various parts of the sensor, avoiding performance degradation or failure due to poor connection. The entire process has high controllability and repeatability, and can ensure the consistency and reliability of each sensor. This helps to achieve large-scale production and application, and reduce production costs and cycles.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A capacitive pressure sensor, characterized in that: include: Upper plate, pressure-sensitive layer and lower plate; The upper plate includes an upper plate electrode, and the lower plate includes a lower plate electrode; The pressure-sensitive layer is located between the upper electrode plate and the lower electrode plate, and the pressure-sensitive layer includes a first pressure-sensitive electrode and a second pressure-sensitive electrode, and the first pressure-sensitive electrode and the second pressure-sensitive electrode are located on the front side and the back side of the pressure-sensitive layer respectively; The first pressure-sensitive electrode and the upper plate electrode are arranged opposite to each other to form a first capacitor, and the second pressure-sensitive electrode and the lower plate electrode are arranged opposite to each other to form a second capacitor.

2. The capacitive pressure sensor according to claim 1, characterized in that: The upper electrode plate is provided with a thinning area in the peripheral area of ​​the upper electrode plate electrode, and the lower electrode plate is provided with a thinning area in the peripheral area of ​​the lower electrode plate electrode.

3. The capacitive pressure sensor according to claim 1, characterized in that: The upper electrode plate is provided with an upper electrode lead-out terminal, and the upper electrode lead-out terminal is connected to the upper electrode plate electrode; The lower electrode plate is provided with a lower electrode lead-out terminal, and the lower electrode lead-out terminal is connected to the lower electrode plate electrode; The pressure-sensitive layer is provided with a first lead-out end facing the upper electrode lead-out end, and the first lead-out end is connected to the first pressure-sensitive electrode; The pressure-sensitive layer is provided with a second lead-out end facing the lower electrode lead-out end; the second lead-out end is connected to the second pressure-sensitive electrode.

4. The capacitive pressure sensor according to claim 1, characterized in that: The upper electrode plate, the pressure-sensitive layer and the lower electrode plate are correspondingly provided with direct bonding areas.

5. The capacitive pressure sensor according to claim 1, characterized in that: The upper electrode plate, the pressure-sensitive layer and the lower electrode plate are correspondingly provided with gold-gold bonding areas.

6. The capacitive pressure sensor according to claim 1, characterized in that: Overflow grooves are arranged at the edges of the upper electrode plate and the lower electrode plate.

7. The capacitive pressure sensor according to claim 1, characterized in that: The upper electrode plate, the pressure-sensitive layer and the substrate of the lower electrode plate are made of the same material.

8. The capacitive pressure sensor according to claim 1, characterized in that: The substrates of the upper electrode plate, the pressure-sensitive layer and the lower electrode plate are made of quartz crystal, glass or high-resistance silicon wafer.

9. A method for manufacturing a capacitive pressure sensor according to any one of claims 1 to 8, characterized in that: include: forming an upper plate electrode on the upper plate; forming a lower plate electrode on the lower plate; Forming a first pressure-sensitive electrode and a second pressure-sensitive electrode on the front and back surfaces of the pressure-sensitive layer respectively; The upper plate, the pressure-sensitive layer and the lower plate are connected so that the first pressure-sensitive electrode and the upper plate electrode are arranged opposite to each other to form a first capacitor, and the second pressure-sensitive electrode and the lower plate electrode are arranged opposite to each other to form a second capacitor.

10. The method for manufacturing a capacitive pressure sensor according to claim 9, characterized in that: The method further comprises: The upper plate is thinned in the peripheral area of ​​the upper electrode to form a thinned area, and the lower plate is thinned in the peripheral area of ​​the lower plate electrode to form a thinned area.

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