Integrated temperature and pressure dual-mode sensor and preparation method thereof

Abstract

The invention 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 a first packaging layer and a second packaging layer which are separated from each other, and the first packaging layer and the second packaging layer respectively clamp the piezoelectric chip and the NTC chip from two sides of the piezoelectric chip and the NTC chip, so that a first packaging electrode layer of the first packaging layer is respectively electrically connected with one electrode layer of the piezoelectric chip and one electrode layer of the NTC chip to form a common connection point; a second packaging electrode layer of the second packaging layer comprises k electrodes which are electrically isolated from one another, k is equal to the sum of the number of the piezoelectric chips and the number of the NTC chips, and the k electrodes are electrically connected with the other electrode layer of the piezoelectric chips and the other electrode layer of the NTC chips respectively. The piezoelectric chip and the NTC chip are integrated through the flexible packaging structure, the temperature and the pressure can be monitored at the same time, the flexible packaging structure has the advantages of being small in thickness and good in flexibility, and the application range is greatly expanded.

Description

Technical Field

[0001] The present invention relates to the field of sensors, and in particular to an integrated temperature and pressure dual-mode sensor and a preparation method thereof. Background Art

[0002] Pressure sensors are widely used in automotive electronics, aerospace, and industrial production. They can monitor stress, vibration, and other information to obtain the operating status of machinery and equipment, thereby enabling health monitoring and non-destructive evaluation of equipment structures, which is essential for ensuring safe operation of equipment and improving equipment operating efficiency. In these application scenarios, the ambient temperature often fluctuates. Since the physical parameters of the material, such as resistivity and piezoelectric constant, change with temperature, the output signal of the pressure sensor has temperature drift. In order to enable the pressure sensor to maintain performance stability, consistency, and high-precision measurement under temperature-changing environmental conditions, real-time temperature compensation is required.

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

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

[0005] At present, the main focus of temperature & pressure dual-mode sensors is to decouple different sensing mechanisms and provide a monitoring solution that is simple in structure, easy to operate and efficient.

[0006] Jincheng Wang, Rui Chen and others published an article titled "Integrating In-Plane Thermoelectricity and Out-Plane Piezoresistivity for Fully Decoupled Temperature-Pressure Sensing" in Small. They realized temperature sensing based on the thermoelectric effect of graphene film on polyimide, and pressure sensing by using a micro-cone array made of a piezoresistive composite material composed of carbon nanotubes, graphite powder and polydimethylsiloxane (CNT / GP / PDMS). The layout and wiring of the array temperature and pressure sensor are 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, realizing temperature and pressure sensing based on the thermoelectric and piezoresistive effects of Bi2Te3 films. This method involves steps such as using magnetron sputtering to deposit Bi2Te3 films and using femtosecond lasers to pattern the films. The manufacturing process is complex and costly.

[0008] In the above two methods for preparing temperature and pressure dual-mode flexible sensors, the first method uses two different materials to sense pressure and temperature respectively. The preparation and processing techniques of the two sensitive materials are different, which increases the complexity of the manufacturing process; the second method uses the same material for temperature and pressure sensing at the same time, which requires complex functional materials and complex structural design to reduce the crosstalk between the temperature and pressure signals. Therefore, it is necessary to propose a design method for a simpler, more effective, stable and reliable temperature and pressure integrated sensor. Summary of the invention

[0009] In view of the defects in the prior art, the purpose of the present invention is to provide an integrated temperature and pressure dual-mode sensor and a preparation method thereof. The NTC chip and the piezoelectric chip are packaged together using a flexible packaging structure. The resulting flexible integrated temperature and pressure dual-mode sensor can detect temperature and pressure at the same time, has the advantages of small thickness and good flexibility, and its application range is greatly expanded.

[0010] To achieve the above-mentioned purpose of the invention, 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 comprises a separate first packaging layer and a second packaging layer, the first packaging layer and the second packaging layer respectively sandwich the piezoelectric chip and the NTC chip from both sides thereof, so that the first packaging electrode layer of the first packaging layer is respectively 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 comprises k electrodes electrically isolated from each other, k=the number of the piezoelectric chips+the number of the 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, and p≥2.

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

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

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

[0015] Preferably, the first insulating layer of the first packaging layer covers the first packaging 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 packaging electrode layer respectively; the second packaging layer also includes a grounding layer, and the grounding layer is arranged on the same layer as the second packaging electrode layer and is electrically isolated, and the second insulating layer and the third insulating layer of the second packaging layer respectively wrap the second packaging electrode layer and the grounding layer from both sides thereof, and m welding windows are opened on the second insulating layer, m=k+1, so that a part of the k electrodes are respectively exposed at k welding windows, so that the second electrode layer of the piezoelectric chip and the second electrode layer of the NTC chip are electrically connected to the k electrodes respectively, and a part of the grounding layer is exposed at the last welding window, so that the first packaging electrode layer is electrically connected to the grounding layer.

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

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

[0018] In a second aspect, the present invention provides a method for preparing an integrated temperature and pressure dual-mode sensor, which is used to prepare the integrated temperature and pressure dual-mode sensor described in any technical solution of the first aspect, comprising the following steps: (1) plating a second electrode layer of a piezoelectric chip on one side of a piezoelectric ceramic thicker than 200 μm, and plating a second electrode layer of an NTC chip on one side of an NTC thermistor ceramic thicker 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 the piezoelectric chip on the other side of the thinned piezoelectric ceramic to obtain a piezoelectric ceramic wafer; and sputtering a first electrode layer of the NTC chip on the other side of the thinned NTC thermistor ceramic to obtain an NTC thermistor ceramic wafer. ; (4) cutting the piezoelectric ceramic wafer into a plurality of piezoelectric chips of preset specifications, and cutting the NTC thermistor ceramic wafer into a plurality of NTC chips of preset specifications; (5) sandwiching two packaging layers of a flexible packaging structure 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 electrodes that are electrically isolated from each other, to form an integrated temperature and pressure dual-mode flexible sensor, where k = the number of the piezoelectric chips + the number of the NTC chips.

[0019] Preferably, in the step (5), a patch welding packaging method is adopted. First, a first solder is applied to the area to be welded of each of the k electrodes, and 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 patch welded to the k electrodes respectively. Then, a second solder is applied to the surface of the first electrode layer of the piezoelectric chip and the NTC chip respectively, and finally, the first packaging electrode layer of the first packaging layer is pressed onto the second solder at each location and patch welded to the first electrode layer.

[0020] Preferably, a grounding layer is arranged on the same layer as the second packaging electrode layer, so that the second insulating layer and the third insulating layer of the second packaging layer respectively wrap the second packaging electrode layer and the grounding layer from both sides thereof, and m welding windows are opened on the second insulating layer, m=k+1, so that a part of the k electrodes are respectively exposed at k welding windows, so that the second electrode layer of the piezoelectric chip and the second electrode layer of the NTC chip are respectively electrically connected to the k electrodes, and a part of the grounding layer is exposed at the last welding window, so that the first packaging electrode layer is electrically connected to the grounding layer; and the first solder is applied at each welding window.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention uses a flexible packaging structure to package an NTC chip and at least one piezoelectric chip together to obtain the required flexible integrated temperature and pressure dual-mode sensor. The preparation process is simple and ingenious, the materials required for preparation are commonly used and easy to obtain, and the cost performance is extremely high. The dual-mode sensor prepared by the present invention can detect temperature and pressure at the same time. The sensitivity of the pressure sensor at different temperatures is calibrated in advance by measurement to obtain 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 used to correspond to the pressure to be measured. This pressure is the measured value after temperature compensation, which solves the temperature compensation problem of the pressure sensor very simply and quickly. In addition, the dual-mode sensor also has the advantages of small thickness and good flexibility, and the scope of application is greatly expanded. Other technical effects brought about by the additional features will be further described in the corresponding embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0024] Figure 1 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 diagram and (b) is a layered diagram;

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

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

[0027] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0028] like Figure 1 Figure (a) and Figure (b) Figure 2 As shown in (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 separated first packaging layer and a second packaging layer, the first packaging layer and the second packaging layer respectively sandwich the piezoelectric chip 3 and the NTC chip 2 from both sides, so that the first packaging electrode layer 5 of the first packaging layer is respectively 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 electrodes electrically isolated from each other, k=the number of the piezoelectric chips 3+the number of the 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 packaging layer and the second packaging layer. Figure 2 As shown in (a) and (b), the lower surfaces of the piezoelectric chip 3 and the NTC chip 2 are both the second electrode layer 12, and the upper surfaces are both the first electrode layer 13. The first packaging electrode layer 5 of the first packaging 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, there must be k electrodes equal to the number k of sensors electrically connected to each sensor. The dual-mode sensor formed by such an integrated package can simultaneously measure the dual parameters of temperature and pressure. The preparation process is simple and ingenious, the materials required for preparation are commonly used and easily available, and the cost performance is extremely high. The dual-mode sensor can detect temperature and pressure at the same time. The sensitivity of the pressure sensor at different temperatures is calibrated in advance by measurement, and a set of pressure-output voltage curves at different temperatures are obtained. In subsequent use, the voltage measured by the pressure sensor and the temperature measured by the temperature sensor can be used to correspond to the pressure to be measured. This pressure is the measured value after temperature compensation, which solves the temperature compensation problem of the pressure sensor very simply and quickly. The packaging structure is flexible, and the part connected to the external circuit can be bent or folded during use, which greatly compresses the size of the space required, and can be flexibly applied to various narrow spaces and spaces that need to be bent, etc., greatly expanding the scope of application.

[0030] In this embodiment, the flexible packaging structure 1 can use an FPC (Flexible Printed Circuit) board, and the material of the first packaging electrode layer 5 and the second packaging electrode layer 8 on the FPC board is generally copper with gold plating on the surface. The first packaging electrode layer 5 and the first electrode layer 13 are bonded and welded, and welding methods such as reflow soldering or laser welding can be used. The contact areas of the two electrode layers can be equal, that is, the electrodes of the two completely cover each other. The contact areas of the two can also be unequal, such as the area of ​​the first packaging electrode layer 5 accounts for 80% of the area of ​​the first electrode layer 13. In this way, the shape of the first packaging electrode layer 5 can be designed to be narrower than the first electrode layer 13, and the length is much larger than the first electrode layer 13. The slender strip type can meet the electrical performance requirements and save the metal consumption in the width direction of the first electrode layer 13. The thickness of the packaging electrode layer (including the first packaging electrode layer 5 and the second packaging electrode layer 8) can be controlled to be 10μm-40μm.

[0031] In one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, in the same dimension, 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 this embodiment, the value of p is preferably greater than 10, such as 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, and is only a small square indicated by the tail end of the arrow in the figure. The material of the piezoelectric chip 3 and the NTC chip 2 itself is plastic ceramic, which has poor flexibility. Through the 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 for a long distance. The external circuit used 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. In this way, the flexibility of the integrated temperature and pressure dual-mode sensor of this embodiment is greatly increased. During use, the part connected to the external circuit can be bent or folded and deformed, which greatly compresses the size of the space required to be occupied, and can be flexibly applied to various narrow spaces and spaces that need to be bent, etc., and the scope of application is greatly expanded.

[0032] In one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, the number of the piezoelectric chips 3 is n, where n≥2. Figure 1 Figure (a) and Figure (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 with the NTC chip 2 as the center, and can detect multi-point pressure, so that the spatial resolution of the pressure sensor is greatly improved. The temperature sensor adopts single-point detection to ensure the accuracy of temperature measurement and reduce the complexity of layout and wiring.

[0033] In one embodiment of the integrated temperature and pressure dual-mode sensor of the present invention, Figure 2 As shown in (a) and (b), the piezoelectric chip 3 includes two electrode layers and a piezoelectric ceramic layer 11 sandwiched therebetween, and the NTC chip 2 includes two electrode layers and an NTC thermistor layer 11 sandwiched therebetween, and the piezoelectric ceramic layer 11 and the NTC thermistor layer 11 have the same thickness, both of which are 50μm-200μm. In this embodiment, the NTC (Negative Temperature Coefficient) thermistor layer is made of a metal oxide semiconductor, and its resistance decreases with increasing temperature. Compared with other types of temperature sensors, it has the advantages of high sensitivity, high measurement accuracy and low cost. It can not only be used as a measuring element, such as a temperature sensing device in a thermometer and an air conditioner, but also as a control element, such as a thermal switch in a kettle, a current limiter in a power supply device, etc., and is widely used in household appliances, automotive electronics, medical and health instruments and equipment and other fields. The flexible NTC chip 2 can be bent mechanically without loss, and is suitable for temperature measurement in various narrow spaces. In addition, the response time and sensitivity of small-size flexible NTC thermistors 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 has been greatly reduced compared with the traditional thickness (greater than 300 μm). 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. After the thickness of the piezoelectric chip 3 and the NTC chip 2 is reduced, they have the following advantages: (1) ultra-thin design, easy to fit the object to be measured, sensitive response, low power consumption, suitable for narrow space, and open 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 (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 packaging layer covers the first packaging 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 packaging electrode layer 5 respectively; the second packaging layer also includes a grounding layer, and the grounding layer is arranged on the same layer as the second packaging electrode layer 8 and is electrically isolated, and the second insulating layer 6 and the third insulating layer 9 of the second packaging layer respectively wrap the second packaging electrode layer 8 and the grounding layer from both sides thereof, and m welding windows 7 are provided on the second insulating layer 6, m=k+1, so that a part of the k electrodes is exposed at k welding windows 7, respectively, so that the second electrode layer 12 of the piezoelectric chip 3 and the second electrode layer 12 of the NTC chip 2 are electrically connected to the k electrodes respectively, and a part of the grounding layer is exposed at the last welding window 7, so that the first packaging electrode layer 5 is electrically connected to the grounding layer. In this embodiment, there are mainly three additional technical features. First, a grounding layer is provided on the same layer as the second packaging 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, which is electrically connected to the first package electrode layer 5 and finally connected to the ground wire of the external circuit. The setting of the grounding layer is equivalent to moving the position of the first package electrode layer 5 from the lower surface of the first insulating layer 4 to the upper surface of the third insulating layer 9, which is the same as the longitudinal position of the second package electrode layer 8, and all electrodes connected to the external circuit are concentrated on one side edge of the third insulating layer 9, which is convenient for subsequent more efficient connection with the external circuit. Second, as Figure 1 As shown in Figure (b), two insulating layers, namely the second insulating layer 6 and the third insulating layer 9, are used to insulate the second package electrode layer 8 and the ground layer from both sides. Specifically, the upper surface of the second package electrode layer 8 and the ground layer is covered with the second insulating layer 6, and the lower surface of the second package electrode layer 8 and the ground layer is covered with the third insulating layer 9. In this way, the second package electrode layer 8 and the ground layer can be electrically isolated from any other metal medium, such as the first package electrode layer 5, to ensure the packaging effect. Third, m welding windows 7 are opened at the corresponding position of the second insulating layer 6 to expose the metal electrode layer covered under the insulating layer for welding, that is, the welding window 7 must correspond to the metal electrode layer. For example, if Figure 1As shown in Figure (b), the number of piezoelectric chips 3 is n=4, and there is 1 NTC chip 2, then k=4+1=5, m=k+1=6, that is, 6 welding windows 7 need to be opened, of which 1 welding window is used to weld the second electrode layer 12 of the NTC chip 2 to 1 electrode of the second package electrode layer 8, 4 welding windows 7 are used to weld the second electrode layer 12 of the 4 piezoelectric chips 3 to the other 4 electrodes of the second package electrode layer 8, and the last welding window 7 is used to weld the first package electrode layer 5 to the ground layer. The size of the welding window 7 is equivalent to the area of ​​the piezoelectric chip 3 and the NTC chip 2, which is convenient for matching welding. It should be pointed out that the area of ​​the welding window 7 does not need to be completely equal to the area of ​​the piezoelectric chip 3 or the NTC chip 2. It can be equal or slightly smaller, but not larger, otherwise there will be insulation risks. Only a window with a very small area is opened at the welding position, and the non-welding position is completely insulated to ensure electrical insulation performance.

[0035] In this embodiment, Figure 1 As shown in Figure (b), 6 welding windows 7 are located on the second insulating layer 6, and the white squares in the figure are welding windows 7. It should be noted that the 5 gray squares above the 5 white squares on the left side of the figure represent 5 sensor chips, which are 4 piezoelectric chips 3 and 1 NTC chip 2. These 5 sensor chips are not on the second insulating layer 6, but are suspended in the air, which is the effect of the exploded view. The 5 welding windows 7 correspond to the 5 sensor chips one by one. When welding, the sensor chips need to be placed at the corresponding welding windows 7. The rightmost white square is the welding window 7 for welding the ground 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 packaging layer, and the metal layer of each tail is exposed. Figure 1 As shown in Figures (a) and (b), together with the ground layer, there are a total of 6 electrodes extending to the right edge of the third insulating layer 9, and the tails of the 6 electrodes are all exposed to the metal layer, which is convenient for connection with an external circuit through welding wires.

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

[0038] like Figure 2As shown in Figures (a) to (f) of the present invention, an embodiment of the method for preparing an integrated temperature and pressure dual-mode sensor of the present invention comprises the following steps: (1) plating a second electrode layer 12 of a piezoelectric chip 3 on one side of a piezoelectric ceramic 11 having a thickness greater than 200 μm, and plating a second electrode layer 12 of an NTC chip 2 on one side of an NTC thermistor ceramic 11 having a thickness greater than 200 μm, as shown in Figures (a) to (f) of the present invention. Figure 2 As shown in Figure (a) in the figure; it needs to be explained here that since the preparation process of piezoelectric ceramic wafers and NTC thermistor ceramic wafers is the same, Figure 2 Figure (a) in the figure can illustrate the preparation process of both. 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 the two, and the same reference numeral 13 is used to represent the first electrode layer of the two; (2) the piezoelectric ceramic 11 and the NTC thermistor ceramic 11 are thinned to 50μm-200μm respectively by a grinding wheel 10, as shown in FIG. Figure 2 As shown in (a) of FIG. 1 ; (3) sputtering a first electrode layer 13 of a piezoelectric chip on the other side of the thinned piezoelectric ceramic to obtain a piezoelectric ceramic wafer; sputtering a first electrode layer 13 of an NTC chip on the other side of the thinned NTC thermistor ceramic 11 to obtain an NTC thermistor ceramic wafer, as shown in FIG. Figure 2 (4) The piezoelectric ceramic wafer is cut into a plurality of piezoelectric chips 3 of preset specifications by a cutting blade 14, and the NTC thermistor ceramic wafer is cut into a plurality of NTC chips 2 of preset specifications, such as Figure 2 As shown in Figure (c) in the figure; (5) The two packaging layers of the flexible packaging 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 packaging electrode layer 5 of the first packaging layer to form a common connection point for grounding, and the second packaging electrode layer 8 of the second packaging 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 electrodes that are electrically isolated from each other, and the packaging forms an integrated temperature and pressure dual-mode flexible sensor, k = the number of the piezoelectric chips + the number of the NTC chips.

[0039] In this embodiment, the surface of the piezoelectric ceramic 11 and the NTC thermistor ceramic 11 is completely covered by the grinding plane of the grinding wheel 10 to perform mechanical polishing to achieve a thinning effect. The thickness, speed, uniformity and other indicators of thinning can be controlled by personalizing the rotation speed, axial feed step length, cycle and feed number of the grinding wheel 10. After thinning to 50μm-200μm, the thinner integrated temperature and pressure dual-mode sensor can be applied to a narrower space, broadening its application range.

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

[0041] In this embodiment, the piezoelectric chip 3 and the NTC chip 2 are sandwiched between the first packaging layer and the second packaging layer. Figure 2 As shown in (a) and (b), the lower surfaces of the piezoelectric chip 3 and the NTC chip 2 are both the second electrode layer 12, and the upper surfaces are both the first electrode layer 13. The first packaging electrode layer 5 of the first packaging 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 and is equivalent to a negative electrode. Since the sensor includes more than one piezoelectric chip 3 and NTC chip 2, there must be k electrodes equal to the number k of sensors electrically connected to each sensor. The dual-mode sensor formed by such an integrated package can simultaneously measure the dual parameters of temperature and pressure, and the packaging structure is flexible. During use, the part connected to the external circuit can be bent or folded and deformed, which greatly compresses the size of the space required to be occupied, and can be flexibly applied to various narrow spaces and spaces that need to be bent, etc., greatly expanding the scope of application.

[0042] In one embodiment of the preparation method of the present invention, the step (5) adopts a packaging method of patch welding, and firstly, the first solder 15 is applied to the welding area of ​​each of the k electrodes, i.e., the welding window 7, by a solder paste printer, and then the piezoelectric chips 3 and NTC chips 2, a total of k in number, are placed on the first solder 15 at k positions, respectively, so that the second electrode layers 12 of the k piezoelectric chips 3 and NTC chips 2 are patch welded to the k electrodes, and then the second solder 16 is applied to the surface of the first electrode layer 13 of the piezoelectric chip 3 and the NTC chip 2, respectively, and finally the first packaging electrode layer 5 of the first packaging layer is pressed on the second solder 16 at each location to be patch welded to the first electrode layer 13. Preferably, a grounding layer is arranged on the same layer as the second packaging electrode layer 8, so that the second insulating layer 6 and the third insulating layer 9 of the second packaging layer respectively wrap the second packaging electrode layer 8 and the grounding layer from both sides thereof, and m welding windows 7 are opened on the second insulating layer, m=k+1, so that a part of the k electrodes are respectively exposed at k welding 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 are respectively electrically connected to the k electrodes, and a part of the grounding layer is exposed at the last welding window 7, so that the first packaging electrode layer 5 is electrically connected to the grounding layer; and the first solder 15 is applied at each welding window 7.

[0043] In this embodiment, Figure 2 As shown in Figures (d) to (f) of FIG. 1 , the entire patch welding process is mainly divided into the following five steps: the first step is to simultaneously apply the first solder 15 at the positions of the six welding windows 7 by a solder paste printer; the second step is to sequentially solder the lower surfaces of the four piezoelectric chips 3, the lower surface of the one NTC chip 2, and the Figure 1 The end of the first package electrode layer 5 shown in (a) and (b) is placed on the first solder 15 at the corresponding position; the third step is to use a patch welding machine to weld the second electrode layer 12 on the lower surface of the four piezoelectric chips 3, the second electrode layer 12 on the lower surface of the one NTC chip 2, and the first package electrode layer 5 to the corresponding electrodes of the second package electrode layer 8 and the ground layer at one time; the fourth step is to use a solder paste printer to simultaneously apply the second solder 16 on the upper surface of the four piezoelectric chips 3 and the upper surface of the one NTC chip 2; the fifth step is to use a patch welding machine to weld the first electrode layer 13 on the upper surface of the four piezoelectric chips 3, the first electrode layer 13 on the upper surface of the one NTC chip 2, and the first package electrode layer 5 at one time. It can be seen that the actual welding process includes two spot welding, one positioning and placement of the object to be welded, and two patch weldings, and all of which can be completed automatically by the equipment, which is very fast and efficient, and the consistency and stability of the welding quality are good.

[0044] For other technical details of the present invention, please refer to the invention patent CN118824656A previously applied by the applicant, namely, an NTC thermistor and a preparation method thereof.

[0045] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. An integrated temperature and pressure dual-mode sensor, characterized in that: It comprises a piezoelectric chip, an NTC chip and a flexible packaging structure; the flexible packaging structure comprises a separated first packaging layer and a second packaging layer, the first packaging layer and the second packaging layer respectively sandwich the piezoelectric chip and the NTC chip from both sides thereof, so that a first packaging electrode layer of the first packaging layer is respectively electrically connected to an electrode layer of the piezoelectric chip and an 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 electrically isolated from each other, k=the number of the piezoelectric chips+the number of the NTC chips, the k electrodes are respectively electrically connected to another electrode layer of the piezoelectric chip and another electrode layer of the NTC chip.

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 the 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 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, both of which are 50 μm-200 μm.

5. The integrated temperature and pressure dual-mode sensor according to claim 1, characterized in that: The first insulating layer of the first packaging layer covers the first packaging 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 packaging electrode layer respectively; the second packaging layer also includes a grounding layer, and the grounding layer is arranged on the same layer as the second packaging electrode layer and is electrically isolated. The second insulating layer and the third insulating layer of the second packaging layer respectively wrap the second packaging electrode layer and the grounding layer from both sides thereof, and m welding windows are opened on the second insulating layer, where m=k+1, so that a part of the k electrodes are respectively exposed at k welding windows, so that the second electrode layer of the piezoelectric chip and the second electrode layer of the NTC chip are electrically connected to the k electrodes respectively, and a part of the grounding layer is exposed at the last welding window, so that the first packaging electrode layer is electrically connected to the grounding layer.

6. The integrated temperature and pressure dual-mode sensor according to claim 5, characterized in that: The tails of the k electrodes and the ground layer are respectively located at the edge of the second packaging layer, and the metal layers of the tails are exposed.

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

8. A method for preparing an integrated temperature and pressure dual-mode sensor, characterized in that: The steps include: (1) Plating a second electrode layer of a piezoelectric chip on one side of a piezoelectric ceramic thicker than 200 μm, and plating a second electrode layer of an NTC chip on one side of an NTC thermistor ceramic thicker 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) cutting the piezoelectric ceramic wafer into a plurality of piezoelectric chips of preset specifications, and cutting the NTC thermistor ceramic wafer into a plurality of NTC chips of preset specifications; (5) 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 electrodes that are electrically isolated from each other, to form an integrated temperature and pressure dual-mode flexible sensor, where k = the number of the piezoelectric chips + the number of the NTC chips.

9. The method for preparing the integrated temperature and pressure dual-mode sensor according to claim 8, characterized in that: In the step (5), a packaging method of patch welding is adopted. First, the first solder is applied to the area to be welded of each of the k electrodes, and then the piezoelectric chips and NTC chips, a total of k in number, are placed on the first solder at k positions, so that the second electrode layers of the k piezoelectric chips and NTC chips are patch welded to the k electrodes, and then the second solder is applied to the surface of the first electrode layer of the piezoelectric chip and the NTC chip, and finally the first packaging electrode layer of the first packaging layer is pressed onto the second solder at each location and patch welded to the first electrode layer.

10. The method for preparing the integrated temperature and pressure dual-mode sensor according to claim 9, characterized in that: A grounding layer is arranged on the same layer as the second packaging electrode layer, so that the second insulating layer and the third insulating layer of the second packaging layer respectively wrap the second packaging electrode layer and the grounding layer from both sides thereof, and m welding windows are opened on the second insulating layer, where m=k+1, so that a part of the k electrodes are respectively exposed at k welding windows, so that the second electrode layer of the piezoelectric chip and the second electrode layer of the NTC chip are respectively electrically connected to the k electrodes, and a part of the grounding layer is exposed at the last welding window, so that the first packaging electrode layer is electrically connected to the grounding layer; and the first solder is applied at each welding window.

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