An integrated temperature and pressure dual-mode sensor and a method of manufacturing the same

Abstract

The application provides an integrated temperature and pressure dual-mode sensor and a preparation method thereof. The integrated temperature and pressure dual-mode sensor comprises a piezoelectric chip, an NTC chip and a flexible packaging structure. The flexible packaging structure comprises separated first and second packaging layers. The first and second packaging layers sandwich the piezoelectric chip and the NTC chip from two sides, respectively. The first packaging electrode layer of the first packaging layer is electrically connected with one electrode layer of the piezoelectric chip and one electrode layer of the NTC chip to form a common connection point. The second packaging electrode layer of the second packaging layer comprises k electrodes which are electrically isolated from each other, k = the number of the piezoelectric chip + the number of the NTC chip. The k electrodes are electrically connected with the other electrode layer of the piezoelectric chip and the other electrode layer of the NTC chip, respectively. The piezoelectric chip and the NTC chip are integrated by the flexible packaging structure, so that the temperature and the pressure can be monitored simultaneously. The integrated temperature and pressure dual-mode sensor has the advantages of small thickness and good flexibility, and the application range is greatly expanded.

Description

Technical Field

[0001] This invention relates to the field of sensors, specifically to an integrated temperature and pressure dual-mode sensor and its fabrication method. Background Technology

[0002] Pressure sensors have wide applications in automotive electronics, aerospace, and industrial manufacturing. They monitor stress and vibration to obtain the operating status of machinery and equipment, enabling structural health monitoring and non-destructive assessment, which is crucial for ensuring safe and efficient equipment operation. In these applications, ambient temperature often fluctuates. Because the physical parameters of materials, such as resistivity and piezoelectric constant, change with temperature, the output signal of pressure sensors exhibits temperature drift. To ensure that pressure sensors maintain stable, consistent, and high-precision measurement performance under varying temperature conditions, real-time temperature compensation is necessary.

[0003] Current temperature compensation methods mainly include: 1. Establishing a temperature error model and using an additional algorithm based on the thermal error model established by temperature calibration to correct the pressure sensor output signal. This algorithm is complex and difficult to calibrate the sensor output signal accurately in real time. 2. The built-in circuit method, which places the pressure sensor in a bridge circuit to achieve temperature self-compensation.

[0004] Since monitoring both temperature and pressure is equally important in high-temperature and high-pressure operating environments such as aircraft engines, designing a dual-mode sensor that can simultaneously measure temperature and pressure is an effective solution.

[0005] Currently, the main focus of research on temperature and pressure dual-mode sensors is on decoupling different sensing mechanisms to provide a simple, easy-to-operate, and efficient monitoring solution.

[0006] Jincheng Wang, Rui Chen, and others published an article in Small entitled "Integrating In-Plane Thermoelectricity and Out-Plane Piezoresistivity for Fully Decoupled Temperature-Pressure Sensing," which utilizes the thermoelectric effect of graphene films on polyimide to achieve temperature sensing, and a microcone array made of a piezoresistive composite material composed of carbon nanotubes, graphite powder, and polydimethylsiloxane (CNT / GP / PDMS) to achieve pressure sensing. Their array-type temperature and pressure sensing layout is complex, and the vertical stacking method increases the overall thickness of the sensor.

[0007] Hailong Yu, Zhenqing Hu, and others published "Flexible temperature-pressure dual sensor based on 3D spiral thermoelectric Bi2Te3 films" in Nature Communications. This method realizes temperature and pressure sensing based on the thermoelectric and piezoresistive effects of Bi2Te3 thin films. The method involves steps such as using magnetron sputtering to deposit Bi2Te3 thin films and using femtosecond lasers to pattern the thin films. The manufacturing process is complex and costly.

[0008] Of the two methods for fabricating dual-mode flexible temperature and pressure sensors mentioned above, the first method uses two different materials to sense pressure and temperature respectively, and the fabrication and processing technologies for the two sensitive materials are different, increasing the complexity of the manufacturing process. The second method uses the same material for both temperature and pressure sensing, requiring complex functional materials and complex structural designs to reduce crosstalk between the temperature and pressure signals. Therefore, it is necessary to propose a simpler, more effective, stable, and reliable design method for an integrated temperature and pressure sensor. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide an integrated temperature and pressure dual-mode sensor and its fabrication method. By using a flexible packaging structure to encapsulate an NTC chip and a piezoelectric chip together, the resulting flexible integrated temperature and pressure dual-mode sensor can simultaneously detect temperature and pressure, combining the advantages of small thickness and high flexibility, thus greatly expanding its application range.

[0010] To achieve the above-mentioned objectives, in a first aspect, the present invention provides an integrated temperature and pressure dual-mode sensor, comprising a piezoelectric chip, an NTC chip, and a flexible packaging structure; the flexible packaging structure includes a separate first packaging layer and a second packaging layer, which respectively enclose the piezoelectric chip and the NTC chip from both sides, such that a first packaging electrode layer of the first packaging layer is electrically connected to one electrode layer of the piezoelectric chip and one electrode layer of the NTC chip to form a common connection point; the second packaging electrode layer of the second packaging layer includes k electrically isolated electrodes, where k = the number of piezoelectric chips + the number of NTC chips, and the k electrodes are respectively electrically connected to another electrode layer of the piezoelectric chip and another electrode layer of the NTC chip.

[0011] Preferably, in the same dimension, the size of the flexible packaging structure is p times the size of either the piezoelectric chip or the NTC chip, where p ≥ 2.

[0012] Preferably, the number of piezoelectric chips is n, where n≥2.

[0013] Preferably, n=4, and the four piezoelectric chips are evenly distributed around the NTC chip as the center.

[0014] Preferably, the piezoelectric chip includes two electrode layers and a piezoelectric ceramic layer sandwiched therebetween, and the NTC chip includes two electrode layers and an NTC thermistor ceramic layer sandwiched therebetween. The piezoelectric ceramic layer and the NTC thermistor ceramic layer have the same thickness, which is 50μm-200μm.

[0015] Preferably, the first insulating layer of the first encapsulation layer covers the first encapsulation electrode layer, and the first electrode layer of the piezoelectric chip and the first electrode layer of the NTC chip are directly electrically connected to the first encapsulation electrode layer. The second encapsulation layer further includes a ground layer, which is disposed on the same layer as the second encapsulation electrode layer and electrically isolated therefrom. The second insulating layer and the third insulating layer of the second encapsulation layer respectively wrap around the second encapsulation electrode layer and the ground layer from both sides. The second insulating layer has m soldering windows, m = k + 1, so that a portion of the k electrodes is exposed at each of the k soldering windows, allowing the second electrode layer of the piezoelectric chip and the second electrode layer of the NTC chip to be electrically connected to the k electrodes respectively. A portion of the ground layer is exposed at the last soldering window, allowing the first encapsulation electrode layer to be electrically connected to the ground layer.

[0016] Preferably, the tails of the k electrodes and the ground layer are located at the edge of the second encapsulation layer, and the metal layer of each tail is exposed.

[0017] Preferably, the tails are arranged in parallel side by side.

[0018] In a second aspect, the present invention provides a method for fabricating an integrated temperature and pressure dual-mode sensor, used to fabricate the integrated temperature and pressure dual-mode sensor described in any of the technical solutions of the first aspect, comprising the following steps: (1) depositing a second electrode layer of a piezoelectric chip on one side of a piezoelectric ceramic with a thickness greater than 200 μm, and depositing a second electrode layer of an NTC chip on one side of an NTC thermistor ceramic with a thickness greater than 200 μm; (2) thinning the piezoelectric ceramic and the NTC thermistor ceramic to 50 μm-200 μm respectively; (3) sputtering a first electrode layer of a piezoelectric chip on the other side of the thinned piezoelectric ceramic to obtain a piezoelectric ceramic wafer; sputtering a first electrode layer of an NTC chip on the other side of the thinned NTC thermistor ceramic to obtain an NTC thermistor ceramic wafer. (4) The piezoelectric ceramic wafer is cut into multiple piezoelectric chips of preset specifications, and the NTC thermistor ceramic wafer is cut into multiple NTC chips of preset specifications; (5) The two packaging layers of the flexible packaging structure are sandwiched from both sides of the NTC chip and at least one of the piezoelectric chips, so that the first electrode layer of the NTC chip and the first electrode layer of the piezoelectric chip are electrically connected to the first packaging electrode layer of the first packaging layer to form a common connection point, and the second packaging electrode layer of the second packaging layer is electrically connected to the other electrode layer of the piezoelectric chip and the other electrode layer of the NTC chip through k mutually electrically isolated electrodes, respectively, to form an integrated temperature and pressure dual-mode flexible sensor, k = the number of piezoelectric chips + the number of NTC chips.

[0019] Preferably, step (5) employs a surface mount soldering (SMT) packaging method. First, a first solder is applied to the soldering area of ​​each of the k electrodes. Then, a total of k piezoelectric chips and NTC chips are placed on the first solder at k locations, so that the second electrode layers of the k piezoelectric chips and NTC chips are surface mount soldered to the k electrodes. Next, a second solder is applied to the surface of the first electrode layers of the piezoelectric chips and NTC chips. Finally, the first encapsulation electrode layer of the first encapsulation layer is pressed onto the second solder at each location and surface mount soldered to the first electrode layer.

[0020] Preferably, a ground layer is provided on the same layer as the second encapsulation electrode layer, such that the second insulating layer and the third insulating layer of the second encapsulation layer respectively wrap around the second encapsulation electrode layer and the ground layer from both sides. m soldering windows, m = k + 1, are opened on the second insulating layer so that a portion of each of the k electrodes is exposed at each of the k soldering windows, allowing the second electrode layer of the piezoelectric chip and the second electrode layer of the NTC chip to be electrically connected to the k electrodes respectively. A portion of the ground layer is exposed at the last soldering window, allowing the first encapsulation electrode layer to be electrically connected to the ground layer. The first solder is applied at each of the soldering windows.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] This invention utilizes a flexible packaging structure to encapsulate an NTC chip and at least one piezoelectric chip together to fabricate the desired flexible integrated temperature and pressure dual-mode sensor. The fabrication process is simple and ingenious, the required materials are commonly used and readily available, and the cost-effectiveness is extremely high. The dual-mode sensor fabricated by this invention can simultaneously detect temperature and pressure. The sensitivity of the pressure sensor at different temperatures is pre-calibrated by measurement, resulting in a set of pressure-output voltage curves at different temperatures. In subsequent use, the voltage measured by the pressure sensor and the temperature measured by the temperature sensor can be mapped to the pressure to be measured; this pressure is the temperature-compensated measurement value, thus easily and quickly solving the temperature compensation problem of the pressure sensor. Furthermore, this dual-mode sensor also possesses the advantages of small thickness and good flexibility, greatly expanding its application range. Other technical effects brought about by the additional features will be further illustrated in the corresponding embodiments. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the structure of an embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, wherein (a) is an assembly view and (b) is a layered view;

[0025] Figure 2 This is a process flow diagram of an embodiment of the method of the present invention, wherein (a)-(f) represent six process steps arranged in chronological order.

[0026] In the figure, 1 is a flexible packaging structure; 2 is an NTC chip; 3 is a piezoelectric chip; 4 is a first insulating layer; 5 is a first packaging electrode layer; 6 is a second insulating layer; 7 is a welding window; 8 is a second packaging electrode layer; 9 is a third insulating layer; 10 is a grinding wheel; 11 is a piezoelectric ceramic layer and an NTC thermistor ceramic layer; 12 is a second electrode layer; 13 is a first electrode layer; 14 is a cutting blade; 15 is a first solder; and 16 is a second solder. Detailed Implementation

[0027] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0028] like Figure 1 Figures (a) and (b), Figure 2 As shown in Figures (a) and (b), an embodiment of the integrated temperature and pressure dual-mode sensor of the present invention includes a piezoelectric chip 3, an NTC chip 2, and a flexible packaging structure 1. The flexible packaging structure 1 includes a separate first packaging layer and a second packaging layer, which respectively enclose the piezoelectric chip 3 and the NTC chip 2 from both sides, such that the first packaging electrode layer 5 of the first packaging layer is electrically connected to one electrode layer of the piezoelectric chip 3 and one electrode layer of the NTC chip 2 to form a common connection point for grounding. The second packaging electrode layer 8 of the second packaging layer includes k electrically isolated electrodes, where k = the number of piezoelectric chips 3 + the number of NTC chips 2, and the k electrodes are respectively electrically connected to another electrode layer of the piezoelectric chip 3 and another electrode layer of the NTC chip 2.

[0029] In this embodiment, the piezoelectric chip 3 and the NTC chip 2 are sandwiched between the first encapsulation layer and the second encapsulation layer, such as... Figure 2 As shown in Figures (a) and (b), the lower surfaces of both the piezoelectric chip 3 and the NTC chip 2 are second electrode layers 12, and their upper surfaces are first electrode layers 13. The first encapsulation electrode layer 5 of the first encapsulation layer, the first electrode layer 13 of the piezoelectric chip 3, and the first electrode layer 13 of the NTC chip 2 are electrically connected together to form a common connection point, which is ultimately grounded, equivalent to a negative electrode. Since the sensor includes more than one piezoelectric chip 3 and NTC chip 2, k electrodes equal to the number of sensors k must be electrically connected to each sensor. The dual-mode sensor formed by this integrated encapsulation can simultaneously measure both temperature and pressure parameters. The fabrication process is simple and ingenious, the required materials are commonly used and readily available, and the cost-effectiveness is extremely high. The resulting dual-mode sensor can simultaneously detect temperature and pressure. The sensitivity of the pressure sensor at different temperatures is pre-calibrated through measurement, resulting in a set of pressure-output voltage curves at various temperatures. In subsequent use, the voltage measured by the pressure sensor and the temperature measured by the temperature sensor can be mapped to the pressure to be measured; this pressure is the temperature-compensated measurement value, thus quickly and easily solving the temperature compensation problem of the pressure sensor. Furthermore, the flexible packaging structure allows the parts connected to the external circuitry to be bent or folded during use, significantly reducing the required space and enabling flexible application in various narrow spaces and bending environments, greatly expanding its application range.

[0030] In this embodiment, the flexible packaging structure 1 can be an FPC (Flexible Printed Circuit) board. The first packaging electrode layer 5 and the second packaging electrode layer 8 on the FPC board are generally made of copper with gold plating. The first packaging electrode layer 5 and the first electrode layer 13 are bonded together using reflow soldering or laser soldering. The contact areas of the two electrode layers can be equal, meaning that their electrodes completely cover each other. Alternatively, the contact areas can be unequal. For example, the area of ​​the first packaging electrode layer 5 can be 80% of the area of ​​the first electrode layer 13. In this case, the shape of the first packaging electrode layer 5 can be designed as a long, thin strip with a width narrower than the first electrode layer 13 and a length much greater than the first electrode layer 13. This satisfies electrical performance requirements and saves metal usage in the width direction of the first electrode layer 13. The thickness of the packaging electrode layers (including the first packaging electrode layer 5 and the second packaging electrode layer 8) can be controlled between 10μm and 40μm.

[0031] In one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, the size of the flexible packaging structure 1 is p times the size of either the piezoelectric chip 3 or the NTC chip 2, where p ≥ 2, in the same dimensional dimension. In this embodiment, the value of p is preferably 10 or higher. Figure 1 As shown in Figures (a) and (b), the area of ​​the piezoelectric chip 3 and the NTC chip 2 is much smaller than the area of ​​the flexible packaging structure 1, only a small square as indicated by the arrow in the figure. The piezoelectric chip 3 and the NTC chip 2 are made of plastic ceramic, which has poor flexibility. Through electrical connection with the large-sized flexible packaging structure 1, the metal electrodes of the piezoelectric chip 3 and the NTC chip 2 can be flexibly extended a long distance. The external circuit for temperature and pressure measurement and control does not need to be directly connected to the piezoelectric chip 3 and the NTC chip 2, but only needs to be connected to the packaging electrode layer of the flexible packaging structure 1. This greatly increases the flexibility of the integrated temperature and pressure dual-mode sensor in this embodiment. During use, the part connected to the external circuit can be bent or folded, greatly reducing the size of the space required. It can be flexibly applied to various narrow spaces and spaces that need to be bent, greatly expanding the application range.

[0032] In one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, the number of piezoelectric chips 3 is n, where n ≥ 2. In this embodiment, as... Figure 1 Figures (a) and (b), Figure 2 As shown in Figures (d), (e), and (f), preferably n=4, the four piezoelectric chips 3 are evenly distributed around the NTC chip 2, enabling multi-point pressure detection and greatly improving the spatial resolution of the pressure sensor. The temperature sensor uses single-point detection, ensuring the accuracy of temperature measurement while reducing the complexity of layout and wiring.

[0033] In one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, such as Figure 2 As shown in Figures (a) and (b), the piezoelectric chip 3 includes two electrode layers and a piezoelectric ceramic layer 11 sandwiched between them, and the NTC chip 2 includes two electrode layers and an NTC thermistor ceramic layer 11 sandwiched between them. The piezoelectric ceramic layer 11 and the NTC thermistor ceramic layer 11 have the same thickness, both ranging from 50μm to 200μm. In this embodiment, the NTC (Negative Temperature Coefficient) thermistor ceramic layer is made of metal oxide semiconductor, and its resistance decreases as temperature increases. Compared to other types of temperature sensors, it has the advantages of high sensitivity, high measurement accuracy, and low cost. It can be used not only as a measuring element, such as a thermometer or temperature sensing device in an air conditioner, but also as a control element, such as a thermal switch in a kettle or a current limiter in a power supply device. It is widely used in household appliances, automotive electronics, medical and health instruments and equipment, etc. The flexible NTC chip 2 can be bent mechanically without damage, adapting to temperature measurement in various narrow spaces. Furthermore, the response time and sensitivity of the small-sized flexible NTC thermistor will also be improved. In this embodiment, the piezoelectric ceramic material includes any one of PZT, BaTiO3, AlN, and PMN-PT; the NTC thermistor ceramic has NTC characteristics. In this embodiment, the thickness of the piezoelectric ceramic layer 11 and the NTC thermistor ceramic layer 11 is greatly reduced compared to the traditional thickness (greater than 300μm). The thickness of the piezoelectric ceramic layer 11 and the NTC thermistor ceramic layer 11 directly affects the overall thickness of the piezoelectric chip 3 and the NTC chip 2 after packaging. The reduced thickness of the piezoelectric chip 3 and the NTC chip 2 has the following advantages: (1) ultra-thin design, easy to adhere to the test object, sensitive response, low power consumption, suitable for narrow spaces, and opening up new application scenarios; (2) fast response time; (3) elasticity and easy welding; (4) thin film coating, excellent insulation and heat resistance; (5) sensitive to the environment; (6) controllable structural parameters; (7) high stability.

[0034] like Figure 1As shown in Figures (a) and (b), in one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, the first insulating layer 4 of the first encapsulation layer covers the first encapsulation electrode layer 5, and the first electrode layer 13 of the piezoelectric chip 3 and the first electrode layer 13 of the NTC chip 2 are directly electrically connected to the first encapsulation electrode layer 5, respectively; the second encapsulation layer also includes a ground layer, which is disposed on the same layer as the second encapsulation electrode layer 8 and electrically isolated therefrom, and the second insulating layer 6 and the third insulating layer 9 of the second encapsulation layer respectively wrap around the second encapsulation electrode layer 8 and the ground layer from both sides, respectively. m welding windows 7, m = k + 1, are opened on the second insulating layer 6 so that a portion of the k electrodes are exposed at each of the k welding windows 7, allowing the second electrode layer 12 of the piezoelectric chip 3 and the second electrode layer 12 of the NTC chip 2 to be electrically connected to the k electrodes, respectively. A portion of the ground layer is exposed at the last welding window 7, allowing the first encapsulation electrode layer 5 to be electrically connected to the ground layer. In this embodiment, there are three main additional technical features. First, a ground layer is disposed on the same layer as the second encapsulation electrode layer 8. Specifically… Figure 1 In Figure (b), the L-shaped electrode at the upper right corner of the third insulating layer 9 is the grounding layer. The grounding layer is electrically connected to the first encapsulation electrode layer 5 and ultimately to the ground wire of the external circuit. The grounding layer effectively moves the position of the first encapsulation electrode layer 5 from the lower surface of the first insulating layer 4 to the upper surface of the third insulating layer 9, aligning it with the longitudinal position of the second encapsulation electrode layer 8. This concentrates all electrodes connected to the external circuit on one edge of the third insulating layer 9, facilitating more efficient subsequent connection to the external circuit. Secondly, as... Figure 1 As shown in Figure (b), insulation is achieved by two insulating layers, namely the second insulating layer 6 and the third insulating layer 9, sandwiched between the second encapsulation electrode layer 8 and the ground layer from both sides. Specifically, the upper surface of the second encapsulation electrode layer 8 and the ground layer is covered by the second insulating layer 6, and the lower surface of the second encapsulation electrode layer 8 and the ground layer is covered by the third insulating layer 9. This ensures that the second encapsulation electrode layer 8 and the ground layer maintain electrical isolation from any other metal medium, such as the first encapsulation electrode layer 5, thus guaranteeing the encapsulation effect. Thirdly, m welding windows 7 are opened at corresponding positions on the second insulating layer 6 to expose the metal electrode layer covered below the insulating layer for welding; that is, the welding window 7 must correspond to the metal electrode layer. For example, as... Figure 1As shown in Figure (b), the number of piezoelectric chips 3 is n = 4, and there is one NTC chip 2. Therefore, k = 4 + 1 = 5, and m = k + 1 = 6, meaning 6 welding windows 7 are required. One welding window is used to weld the second electrode layer 12 of the NTC chip 2 to one electrode of the second packaging electrode layer 8. Four welding windows 7 are used to weld the second electrode layers 12 of the four piezoelectric chips 3 to the other four electrodes of the second packaging electrode layer 8, respectively. The last welding window 7 is used to weld the first packaging electrode layer 5 to the ground layer. The size of the welding windows 7 is comparable to the area of ​​the piezoelectric chips 3 and NTC chips 2, facilitating alignment and welding. It should be noted that the area of ​​the welding windows 7 does not need to be exactly equal to the area of ​​the piezoelectric chips 3 or NTC chips 2; they can be equal or slightly smaller, but not larger, otherwise there will be insulation risks. By opening very small windows only at the welding positions and keeping the non-welding positions completely insulated, electrical insulation performance is guaranteed.

[0035] In this embodiment, as Figure 1 As shown in Figure (b), the six welding windows 7 are located on the second insulating layer 6, as indicated by the white squares in the figure. It is important to note that the five gray squares above the five white squares on the left represent five sensor chips: four piezoelectric chips 3 and one NTC chip 2. These five sensor chips are not on the second insulating layer 6 but are suspended, representing the exploded view effect. Each of the five welding windows 7 corresponds one-to-one with a sensor chip; during welding, the sensor chip must be placed in its corresponding welding window 7. The rightmost white square is the welding window 7 used for welding the grounding layer.

[0036] In one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, the tails of the k electrodes and the ground layer are located at the edge of the second encapsulation layer, and the metal layer of each tail is exposed. In this embodiment, as... Figure 1 As shown in Figures (a) and (b), together with the grounding layer, there are a total of 6 electrodes extending to the right edge of the third insulating layer 9. The tails of the 6 electrodes are exposed in the metal layer, which facilitates connection to the external circuit by welding wires.

[0037] In one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, the tail sections are arranged in parallel side by side. In this embodiment, as... Figure 1 As shown in Figures (a) and (b), compared to the previous embodiment, the tails of the six electrodes are arranged in parallel on the right edge of the third insulating layer 9, and the spacing between each electrode can be equal, which facilitates connection to the external circuit by connecting the FPC adapter board or the corresponding socket, making it plug-and-play, convenient to use, and greatly improving the connection efficiency of the external circuit.

[0038] like Figure 2As shown in Figures (a)-(f), one embodiment of the fabrication method of the integrated temperature and pressure dual-mode sensor of the present invention includes the following steps: (1) depositing a second electrode layer 12 of piezoelectric chip 3 on one side of piezoelectric ceramic 11 with a thickness greater than 200 μm, and depositing a second electrode layer 12 of NTC chip 2 on one side of NTC thermistor ceramic 11 with a thickness greater than 200 μm, as shown in Figures (a)-(f), which includes the following steps: (1) ... piezoelectric chip 3 on one side of piezoelectric ceramic 11 with a thickness greater than 200 μm, as shown in Figures (a Figure 2 As shown in Figure (a); it should be explained here that since the fabrication processes of piezoelectric ceramic wafers and NTC thermistor ceramic wafers are the same, Figure 2 Figure (a) illustrates the preparation process of both simultaneously. For simplicity, the same reference numeral 11 is used to represent the piezoelectric ceramic and the NTC thermistor ceramic, the same reference numeral 12 is used to represent the second electrode layer of both, and the same reference numeral 13 is used to represent the first electrode layer of both; (2) The piezoelectric ceramic 11 and the NTC thermistor ceramic 11 are thinned to 50μm-200μm respectively by the grinding wheel 10, as shown in Figure (a). Figure 2 As shown in Figure (a); (3) the first electrode layer 13 of the piezoelectric chip is sputtered on the other side of the thinned piezoelectric ceramic to obtain a piezoelectric ceramic wafer; the first electrode layer 13 of the NTC chip is sputtered on the other side of the thinned NTC thermistor ceramic 11 to obtain an NTC thermistor ceramic wafer, as shown in Figure (a); Figure 2 As shown in Figure (b); (4) the piezoelectric ceramic wafer is cut into multiple piezoelectric chips 3 of preset specifications by the cutting blade 14, and the NTC thermistor ceramic wafer is cut into multiple NTC chips 2 of preset specifications, as shown in Figure (b); Figure 2 As shown in Figure (c); (5) the two encapsulation layers of the flexible encapsulation structure 1 are sandwiched from both sides of the NTC chip 2 and at least one of the piezoelectric chips 3, so that the first electrode layer 13 of the NTC chip 2 and the first electrode layer 13 of the piezoelectric chip 3 are electrically connected to the first encapsulation electrode layer 5 of the first encapsulation layer to form a common connection point for grounding. The second encapsulation electrode layer 8 of the second encapsulation layer is electrically connected to the other electrode layer of the piezoelectric chip 3 and the other electrode layer of the NTC chip 2 through k mutually electrically isolated electrodes, and the encapsulation forms an integrated temperature and pressure dual-mode flexible sensor, k = the number of piezoelectric chips + the number of NTC chips.

[0039] In this embodiment, the grinding surface of the grinding wheel 10 completely covers the surfaces of the piezoelectric ceramic 11 and the NTC thermistor ceramic 11 for mechanical polishing to achieve a thinning effect. The thickness, speed, and uniformity of the thinning can be controlled by customizing parameters such as the rotational speed of the grinding wheel 10, axial feed step size, cycle, and number of feeds. After thinning to 50μm-200μm, the thinner integrated temperature and pressure dual-mode sensor can be applied in narrower spaces, expanding its application range.

[0040] In this embodiment, as Figure 2 As shown in Figure (f), the areas of NTC chip 2 and piezoelectric chip 3 are much smaller than the area of ​​flexible packaging structure 1, only the size shown by the small square in the figure. The material of NTC chip 2 and piezoelectric chip 3 is plastic ceramic, which has poor flexibility. Through electrical connection with the large-sized flexible packaging structure 1, the metal electrodes of NTC chip 2 and piezoelectric chip 3 can be flexibly extended a long distance. For external circuits, they do not need to be directly connected to NTC chip 2 and piezoelectric chip 3, but only need to be connected to the packaging electrode layer of flexible packaging structure 1. This greatly increases the flexibility of the integrated temperature and pressure dual-mode sensor in this embodiment. During use, the part connected to the external circuit can be bent or folded, greatly reducing the size of the space required. It can be flexibly applied to various narrow spaces and spaces that need to be bent, greatly expanding the application range.

[0041] In this embodiment, the piezoelectric chip 3 and the NTC chip 2 are sandwiched between the first encapsulation layer and the second encapsulation layer, such as... Figure 2 As shown in Figures (a) and (b), the lower surfaces of both the piezoelectric chip 3 and the NTC chip 2 are second electrode layers 12, and their upper surfaces are first electrode layers 13. The first encapsulation electrode layer 5 of the first encapsulation layer, the first electrode layer 13 of the piezoelectric chip 3, and the first electrode layer 13 of the NTC chip 2 are electrically connected together to form a common connection point, which is ultimately grounded, equivalent to a negative electrode. Since the sensor includes more than one piezoelectric chip 3 and NTC chip 2, k electrodes equal to the number of sensors k must be electrically connected to each sensor. The dual-mode sensor formed by this integrated encapsulation can simultaneously measure both temperature and pressure parameters. Furthermore, the encapsulation structure is flexible; the part connected to the external circuit can be bent or folded during use, greatly reducing the required space size. It can be flexibly applied to various narrow spaces and spaces requiring bending, significantly expanding its application range.

[0042] In one embodiment of the preparation method of the present invention, step (5) adopts a surface mount soldering packaging method. First, a first solder 15 is applied to the soldering area (i.e., soldering window 7) of each of the k electrodes using a solder paste printer. Then, a total of k piezoelectric chips 3 and NTC chips 2 are placed on the first solder 15 at the k positions, so that the second electrode layer 12 of each of the k piezoelectric chips 3 and NTC chips 2 is surface mount soldered to the k electrodes. Next, a second solder 16 is applied to the surface of the first electrode layer 13 of the piezoelectric chip 3 and NTC chip 2. Finally, the first encapsulation electrode layer 5 of the first encapsulation layer is pressed onto the second solder 16 at each location and surface mount soldered to the first electrode layer 13. Preferably, a ground layer is provided on the same layer as the second encapsulation electrode layer 8, so that the second insulating layer 6 and the third insulating layer 9 of the second encapsulation layer respectively wrap around the second encapsulation electrode layer 8 and the ground layer from both sides. m soldering windows 7, m = k + 1, are opened on the second insulating layer so that a portion of the k electrodes are exposed at each of the k soldering windows 7, so that the second electrode layer 12 of the piezoelectric chip 3 and the second electrode layer 12 of the NTC chip 2 can be electrically connected to the k electrodes respectively. A portion of the ground layer is exposed at the last soldering window 7, so that the first encapsulation electrode layer 5 can be electrically connected to the ground layer. The first solder 15 is applied at each of the soldering windows 7.

[0043] In this embodiment, Figure 2 Taking Figures (d)-(f) as an example, the entire surface mount soldering process mainly consists of the following five steps: First, the first solder 15 is simultaneously applied to the positions of the six soldering windows 7 using a solder paste printer; Second, the lower surfaces of the four piezoelectric chips 3, the lower surface of the one NTC chip 2, and... Figure 1 In Figures (a) and (b), the end of the first packaging electrode layer 5 is placed onto the corresponding first solder 15. In the third step, the second electrode layers 12 on the lower surfaces of the four piezoelectric chips 3, the second electrode layer 12 on the lower surface of the one NTC chip 2, and the first packaging electrode layer 5 are simultaneously soldered to the corresponding electrodes and ground layer of the second packaging electrode layer 8 using a surface mount soldering machine. In the fourth step, the second solder 16 is simultaneously applied to the upper surfaces of the four piezoelectric chips 3 and the one NTC chip 2 using a solder paste printer. In the fifth step, the first electrode layers 13 on the upper surfaces of the four piezoelectric chips 3 and the one NTC chip 2 are simultaneously soldered to the first packaging electrode layer 5 using a surface mount soldering machine. Therefore, the actual soldering process includes two solder application steps, one placement of the workpiece, and two surface mount soldering steps, all of which can be completed automatically by the equipment, making it very fast and efficient, with good consistency and stability in soldering quality.

[0044] Other technical details of the present invention can be found in the applicant's previously filed invention patent CN118824656A, "An NTC Thermistor and Its Preparation Method".

[0045] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention. The above preferred features can be used in any combination without conflict.

Claims

1. An integrated temperature and pressure dual-mode sensor, characterized in that, The device includes a piezoelectric chip, an NTC chip, and a flexible packaging structure. The flexible packaging structure includes a separate first packaging layer and a second packaging layer, which respectively enclose the piezoelectric chip and the NTC chip from both sides. The first packaging electrode layer of the first packaging layer is electrically connected to one electrode layer of the piezoelectric chip and one electrode layer of the NTC chip to form a common connection point. The second packaging electrode layer of the second packaging layer includes k electrically isolated electrodes, where k = the number of piezoelectric chips + the number of NTC chips. The k electrodes are electrically connected to another electrode layer of the piezoelectric chip and another electrode layer of the NTC chip. The first insulating layer of the first encapsulation layer covers the first encapsulation electrode layer. The first electrode layer of the piezoelectric chip and the first electrode layer of the NTC chip are directly electrically connected to the first encapsulation electrode layer. The second encapsulation layer also includes a ground layer. The ground layer is disposed on the same layer as the second encapsulation electrode layer and electrically isolated from it. The second insulating layer and the third insulating layer of the second encapsulation layer respectively wrap around the second encapsulation electrode layer and the ground layer from both sides. The second insulating layer has m soldering windows, m=k+1, so that a portion of the k electrodes are exposed at each of the k soldering windows, allowing the second electrode layer of the piezoelectric chip and the second electrode layer of the NTC chip to be electrically connected to the k electrodes respectively. A portion of the ground layer is exposed at the last soldering window, allowing the first encapsulation electrode layer to be electrically connected to the ground layer. The piezoelectric chip is an inorganic piezoelectric ceramic chip, and the NTC chip is an inorganic NTC thermistor ceramic chip; the piezoelectric chip and the NTC chip are sandwiched between the first packaging layer and the second packaging layer, located in the same plane, forming a coplanar integrated structure.

2. The integrated temperature and pressure dual-mode sensor according to claim 1, characterized in that, In the same dimension, the size of the flexible packaging structure is p times the size of either the piezoelectric chip or the NTC chip, where p ≥ 2.

3. The integrated temperature and pressure dual-mode sensor according to claim 1, characterized in that, The number of piezoelectric chips is n, where n≥2.

4. The integrated temperature and pressure dual-mode sensor according to claim 1, characterized in that, The piezoelectric chip includes two electrode layers and a piezoelectric ceramic layer sandwiched between them. The NTC chip includes two electrode layers and an NTC thermistor ceramic layer sandwiched between them. The piezoelectric ceramic layer and the NTC thermistor ceramic layer have the same thickness, which is 50μm-200μm.

5. The integrated temperature and pressure dual-mode sensor according to claim 1, characterized in that, The tails of the k electrodes and the ground layer are located at the edge of the second encapsulation layer, and the metal layer of each tail is exposed.

6. The integrated temperature and pressure dual-mode sensor according to claim 5, characterized in that, The tails of each tail are arranged in parallel side by side.

7. A method for fabricating an integrated temperature and pressure dual-mode sensor according to any one of claims 1-6, characterized in that, Includes the following steps: (1) A second electrode layer of a piezoelectric chip is deposited on one side of a piezoelectric ceramic with a thickness greater than 200 μm, and a second electrode layer of an NTC chip is deposited on one side of an NTC thermistor ceramic with a thickness greater than 200 μm. (2) The piezoelectric ceramic and NTC thermistor ceramic are thinned to 50μm-200μm respectively; (3) Sputter the first electrode layer of the piezoelectric chip onto the other side of the thinned piezoelectric ceramic to obtain a piezoelectric ceramic wafer; Sputter the first electrode layer of the NTC chip onto the other side of the thinned NTC thermistor ceramic to obtain an NTC thermistor ceramic wafer; (4) The piezoelectric ceramic wafer is cut into multiple piezoelectric chips of preset specifications, and the NTC thermistor ceramic wafer is cut into multiple NTC chips of preset specifications; (5) The two packaging layers of the flexible packaging structure are sandwiched from both sides of the NTC chip and at least one of the piezoelectric chips, so that the first electrode layer of the NTC chip and the first electrode layer of the piezoelectric chip are electrically connected to the first packaging electrode layer of the first packaging layer to form a common connection point. The second packaging electrode layer of the second packaging layer is electrically connected to the other electrode layer of the piezoelectric chip and the other electrode layer of the NTC chip through k mutually electrically isolated electrodes, respectively, to form an integrated temperature and pressure dual-mode flexible sensor, where k = the number of piezoelectric chips + the number of NTC chips.

8. The method for fabricating the integrated temperature and pressure dual-mode sensor according to claim 7, characterized in that, In step (5), a surface mount soldering (SMT) packaging method is adopted. First, a first solder is applied to the area to be soldered on each of the k electrodes. Then, a total of k piezoelectric chips and NTC chips are placed on the first solder at k positions, so that the second electrode layers of the k piezoelectric chips and NTC chips are surface mount soldered to the k electrodes. Next, a second solder is applied to the surface of the first electrode layers of the piezoelectric chips and NTC chips. Finally, the first encapsulation electrode layer of the first encapsulation layer is pressed onto the second solder at each location and surface mount soldered to the first electrode layer.

9. The method for fabricating the integrated temperature and pressure dual-mode sensor according to claim 8, characterized in that, A ground layer is disposed on the same layer as the second encapsulation electrode layer, such that the second insulating layer and the third insulating layer of the second encapsulation layer respectively wrap around the second encapsulation electrode layer and the ground layer from both sides. m soldering windows are opened on the second insulating layer, m=k+1, so that a portion of the k electrodes are exposed at each of the k soldering windows, so that the second electrode layer of the piezoelectric chip and the second electrode layer of the NTC chip can be electrically connected to the k electrodes respectively. A portion of the ground layer is exposed at the last soldering window, so that the first encapsulation electrode layer can be electrically connected to the ground layer. The first solder is applied at each of the soldering windows.

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