Ink for ink-jet printing, flexible high-temperature-resistant electronic system and preparation method thereof

Abstract

The invention provides ink for ink-jet printing, a flexible high-temperature-resistant electronic system and a preparation method of the flexible high-temperature-resistant electronic system. The material for preparing the ink is selected from at least one of ammonium molybdate, ammonium tungstate, ammonium niobate, niobium oxalate and tantalum ethoxide; a solvent for preparing the ink is a mixed solvent of at least three of water, propylene glycol, ethanol, ethylene glycol and isopropanol; the viscosity of the ink is less than 20 CPS, and the particle size of the solution is less than 1 [mu] m. According to the preparation method, an extreme temperature resistant circuit is directly printed on the surface of the flexible substrate through ink-jet printing and thermal annealing, precise manufacturing of a flexible electronic system with extreme temperature resistance, super-strong interface bonding energy and high light transmittance is achieved, and stress mismatch and microcrack formation of the electronic system in a high-temperature environment can be remarkably inhibited.

Description

Technical Field

[0001] The present invention belongs to the technical fields of additive manufacturing and electronic circuit systems, and particularly relates to an ink for inkjet printing, a flexible high-temperature-resistant electronic system, and a preparation method thereof. Background Art

[0002] With the rapid development of electronic technology, the demand for flexible and high-performance electronic materials has gradually increased. The working performance of traditional electronic components is limited in high-temperature environments. Especially in aerospace, automotive electronics, and other high-temperature applications, the development of flexible high-temperature-resistant electronic systems has become increasingly important. In the prior art, most methods cannot take into account good flexibility, high-temperature resistance, and the performance of circuits. Therefore, a new circuit preparation method is urgently needed. There is an increasing demand for electronic circuits and systems that can operate reliably at high temperatures without performance degradation or failure to support the normal operation of electronic devices under extreme environmental conditions, such as space exploration, clean energy, and turbine engine monitoring. The intrinsic carrier concentration of traditional semiconductors approaches the limit at high temperatures, restricting their potential applications in harsher environments, such as the nuclear industry. In addition, these devices are usually rigid, and there are few strategies to endow them with mechanical flexibility.

[0003] When designing and manufacturing flexible electronic modules (such as amplifiers, filters, and wave generators) and integrated systems for high-temperature applications, several key challenges still remain. The possibility of realizing flexible high-temperature electronic devices is restricted by the inherent characteristics of most existing flexible materials, including poor stability and reduced conductivity at high temperatures. For example, as a widely used circuit material, copper may degrade or even lose its function at temperatures exceeding 200 °C because it is prone to oxidation. Flexible substrates, such as polyimide films and organic fibers, may be continuously damaged when the temperature reaches 300 °C. In addition, the strong interfacial strength between the flexible material and the substrate at room temperature may decrease at high temperatures, mainly due to the mismatch of the thermal expansion coefficients and the influence of thermal stress between the functional material and the flexible substrate. This will cause the material to peel off or fall off the substrate surface in extreme environments. Therefore, there is a scarcity of flexible electronic modules, front-end electronic devices, and integrated systems that can operate reliably under extreme temperature conditions. Summary of the Invention

[0004] To solve the problems existing in the prior art, the purpose of the present invention is to provide an ink for inkjet printing, a flexible high-temperature-resistant electronic system, and a preparation method thereof. This method can in-situ form a conformal circuit on the substrate surface by inkjet printing combined with thermal annealing, realizing the precision manufacturing of electronic components such as extreme temperature-resistant electronic systems and in-situ monitoring flexible systems.

[0005] The present invention is achieved through the following technical solutions:

[0006] An ink for inkjet printing, the materials for making the ink are selected from at least one of ammonium molybdate, ammonium tungstate, ammonium niobate, niobium oxalate, and tantalum ethoxide; the solvent for making the ink is a mixed solvent of at least three of water, propylene glycol, ethanol, ethylene glycol, and isopropyl alcohol; the viscosity of the ink is less than 20 CPS, and the solution particles are less than 1 μm.

[0007] Optionally, the volume ratio of each component in the three mixed solvents is 3:2:1.

[0008] Optionally, the volume of the mixed solution for making the ink is 10 mL, and the addition amount of the material for making the ink is 60 mg.

[0009] A method for preparing a flexible high-temperature resistant electronic system using the ink for inkjet printing of the present invention, comprising the following steps:

[0010] Substrate surface treatment, circuit design, printing process parameter regulation, high-temperature resistant circuit printing, post-treatment of circuit high-temperature annealing and sintering, welding layer printing, integration and assembly of electronic component stack structures, and circuit packaging;

[0011] The printing process parameters are: printing speed 20 mm / s, printing height 10 mm, substrate temperature 30 °C, and carrier gas flow rate 80 sccm.

[0012] Optionally, the post-treatment of circuit high-temperature annealing and sintering includes: according to the curing and sintering temperatures of different materials, selecting a suitable post-treatment method to perform solvent evaporation and sintering curing on the printed precursor pattern;

[0013] After printing, the printed precursor pattern is dried at 150 °C for 10 min for solvent evaporation. Then, the precursor on the substrate is transferred to a quartz furnace for thermal annealing; the temperature of the furnace chamber is 700 - 1000 °C, held for 30 min, and then naturally cooled to room temperature.

[0014] Optionally, the substrate surface treatment includes:

[0015] Using argon plasma to clean the substrate surface to remove impurities and obtain a uniform surface; using ultraviolet / ozone plasma to treat the substrate surface to generate hydrophilic functional groups and adjust the substrate surface energy.

[0016] Optionally, the substrate is selected from one of mica, polyimide, and ceramic.

[0017] Optionally, the ink is also filtered through a nylon filter with a pore size of 0.22 μm.

[0018] Optionally, the conductive materials used in the welding layer include high-temperature resistant conductive pastes such as silver paste, silver glue, and silver-palladium paste;

[0019] The sample was annealed at 80 °C for 60 min to completely dry the conductive adhesive.

[0020] A flexible high-temperature resistant electronic system, characterized in that it is prepared by using the method for preparing a flexible high-temperature resistant electronic system according to any one of the claims of the present invention.

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

[0022] Different from traditional industrial methods, through customized inkjet printing and thermal annealing processes, temperature-resistant circuits with different shapes and thicknesses are deposited on flexible substrates, which play a key role in signal acquisition (i.e., strain and temperature), data transmission, and component connection. Due to the strong bonding between the flexible circuit, electronic components, and substrate, the developed electronic modules, including signal amplifiers, filters, and signal generators, can operate at temperatures exceeding 400 °C (maximum 650 °C). By adjusting the temperature, the output signals of these modules are highly adjustable within a wide range. It is verified that flexible electronic modules and highly integrated systems operating under extreme temperature conditions can operate stably and can be used for long-term and reliable electronic signal processing. Description of the Drawings

[0023] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation to the present invention. In the drawings:

[0024] Figure 1 A circuit picture under an optical microscope of the inkjet-printed flexible high-temperature electronic system prepared in Example 1;

[0025] Figure 2 A scanning electron microscope-energy dispersive spectroscopy picture of the inkjet-printed flexible high-temperature electronic system prepared in Example 1;

[0026] Figure 3 An atomic force microscope test picture of the inkjet-printed flexible high-temperature electronic system prepared in Example 1;

[0027] Figure 4 A light transmittance picture of the inkjet-printed flexible high-temperature electronic system prepared in Example 1;

[0028] Figure 5 A principle picture of the molybdenum amplification circuit prepared in Example 1;

[0029] Figure 6 A signal-to-noise ratio comparison picture of the molybdenum amplification circuit and the copper amplification circuit prepared in Example 1;

[0030] Figure 7 A test curve of the molybdenum amplification circuit prepared in Example 1 continuously tested at 300 °C for 100 h;

[0031] Figure 8 The physical diagram and block diagram of the molybdenum amplification circuit prepared for Example 1 attached to the engine condition monitoring system;

[0032] Figure 9 The comparative test curve of the molybdenum amplification circuit prepared for Example 1 and other commercial sensors for engine condition monitoring;

[0033] Figure 10 The time-domain and frequency-domain diagrams of the molybdenum amplification circuit prepared for Example 1 for monitoring the normal and abnormal states of the engine;

[0034] Figure 11 The low-pass filtering performance picture of the high-temperature filtering circuit prepared for Example 2;

[0035] Figure 12 The comparative test curve of the mechanical resistance performance of the high-temperature filtering circuit prepared for Example 2 at different annealing temperatures;

[0036] Figure 13 The optimized stable mechanical resistance performance test curve of the high-temperature filtering circuit prepared for Example 2;

[0037] Figure 14 The test curve of the high-temperature filtering circuit prepared for Example 2 from room temperature to 900 degrees Celsius;

[0038] Figure 15 The long-term stable test curve of the high-temperature signal generation circuit system prepared for Example 3 at room temperature and 400 °C;

[0039] Figure 16 The test curve of the nano-level high-precision preparation and resistivity of the high-temperature signal generation circuit prepared for Example 3;

[0040] Figure 17 The physical diagram of the high-temperature resistant circuit diagram obtained in Comparative Example 1. Detailed implementation manners

[0041] The technical solutions of the present invention will be further described below in conjunction with the embodiments, but are not limited thereto. Any modifications or equivalent replacements of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0042] The preparation principle of the present invention is as follows:

[0043] An inkjet printing and thermal annealing strategy is used to in-situ grow ultra-thin and high-quality high-temperature resistant circuit patterns on a flexible mica substrate, serving as signal recorders, electrodes, and modulators. Different from traditional electronic systems, the proposed flexible electronic system needs to operate at high temperatures, which requires high stability and robustness of the structure under mechanical bending and high-temperature environments. The mica surface is treated with ultraviolet / ozone plasma to generate hydrophilic functional groups such as hydroxyl and carboxyl groups. In addition, the in-situ decomposition of the precursor and the growth of crystals further enhance the adhesion of the high-temperature resistant thin film to the substrate, forming a strong interface. This is verified through cyclic peel tests. The strain and thermal stress distributions of the high-temperature resistant thin film and the substrate at different temperatures are simulated to study the performance of the device under high temperatures. The results show that there is no obvious thermal mismatch between the thin film and the substrate at high temperatures, confirming the high stability of the system under high-temperature bending conditions.

[0044] A method for preparing a flexible high-temperature resistant electronic system with high resolution and light transmittance based on inkjet printing and its applications according to the present invention include the following processes:

[0045] Step 1: Selection of ink materials

[0046] In the initial stage of preparing the circuit, the ink materials are mainly used to provide electrical conductivity, including various high-temperature resistant metal precursor salts. Commonly used metal precursor salts include ammonium molybdate, ammonium tungstate, ammonium niobate, tantalum ethoxide, and niobium oxalate, etc. These materials have good extreme temperature resistance and can maintain their electrical conductivity and chemical stability in high-temperature environments.

[0047] Step 2: Preparation of inkjet printing ink

[0048] Dissolve 60 mg of the selected precursor material in a specific mixed solution with a volume of 10 mL. Selecting the appropriate solvent and adjusting the solubility are key factors to ensure the final ink performance. The ink should have appropriate viscosity and surface tension (the viscosity of the ink is less than 20 CPS, and the solution particles are less than 1 μm) to ensure smooth flow and formation of precise patterns during inkjet printing.

[0049] Step 3: Treatment of the substrate surface

[0050] Before inkjet printing the ink, it is crucial to treat the substrate surface. First, clean the substrate surface with argon plasma for about 60 seconds to remove possible dirt and impurities, making the substrate surface reach a uniform state. Subsequently, perform ultraviolet / ozone plasma treatment for about 8 minutes to generate hydrophilic functional groups such as hydroxyl and carboxyl groups on the substrate surface to adjust the surface energy of the substrate. This series of surface treatment steps not only improve the adhesion of the ink but also provide a good foundation for subsequent printing.

[0051] Step 4: Circuit Design

[0052] Create a three-dimensional digital model using patterning design software and perform conformal circuit design based on the dimensions of the actual substrate. Optimize the layout and structure of the circuit to ensure its effectiveness and reliability in practical applications, and evaluate potential electrical performance indicators to minimize the deviation between design and engineering implementation as much as possible.

[0053] Step 5: Optimization of Ink Performance

[0054] To ensure the fluidity of the ink in the nozzle and avoid nozzle clogging, filtration of the ink is necessary. Filter the ink using a nylon filter with a pore size of 0.22 μm to remove any large particulate matter that may be present. This step helps to significantly improve the stability and reliability of inkjet printing, ensuring a smooth printing process and improving the quality of the final circuit.

[0055] Step 6: Regulation of Printing Process Parameters

[0056] Before inkjet printing, conduct pre-printing experiments to adjust the inkjet process parameters, such as nozzle speed, ink supply, printing temperature, etc., and determine the printing size for each parameter combination. Thus, determine the optimal parameter combination within the process window to ensure the formation of the expected printing result in actual production. For example, the printing process parameters selected in the present invention are: printing speed 20 mm / s, printing height 10 mm, substrate temperature 30 °C, carrier gas flow rate 80 sccm.

[0057] Step 7: Printing of High-Temperature-Resistant Circuits

[0058] According to the designed circuit pattern size, perform inkjet printing of the ink for specific ink and substrate conditions. At this time, during the printing process, closely monitor the operating state of the nozzle and the ejection of the ink to ensure that every detail meets the design requirements, thereby obtaining a circuit pattern with stable performance.

[0059] Step 8: Post-Treatment of High-Temperature Annealing of Circuits

[0060] After the circuit pattern is printed, it needs to be subjected to high-temperature annealing sintering. During this process, select an appropriate curing temperature and treatment plan according to the characteristics of the materials used to effectively promote the curing of the precursor and enhance the conductivity and mechanical strength of the circuit. This step is crucial for forming a stable circuit structure and directly affects the working performance of the entire electronic system. For example, after printing, the printed precursor pattern is dried at 150 °C for 10 min for solvent evaporation. Then, the precursor on the substrate is transferred to a quartz furnace for thermal annealing; the temperature of the furnace chamber is 700 - 1000 °C, held for 30 min, and then naturally cooled to room temperature.

[0061] Step 9: Printing of the Soldering Layer

[0062] Based on the circuit layout rules and design, a conductive material resistant to extreme temperatures is screen-printed to precise locations. The curing temperature of the solder layer must be compatible with the properties of the preceding circuit to ensure good bonding and stability between the various layers, ultimately improving the overall performance of the electronic component.

[0063] Step 10: Integrated assembly of electronic component stacking structure

[0064] After printing the circuit and solder layers, the electronic components are stacked and integrated. During this process, the high-temperature-resistant electronic components are precisely placed manually under a microscope to ensure that each component's position and arrangement conform to the design requirements. Subsequently, the soldering process is completed using a 285°C hot plate, firmly bonding the components and ensuring the integrity of the overall structure.

[0065] Step 11: Packaging the Circuit

[0066] High-temperature resistant insulating materials are selected and printed on a large area of the circuit surface to protect the internal components of the circuit from the influence of the external environment, while improving the overall performance and service life of the system.

[0067] Experiments have demonstrated that temperature-resistant circuits of varying shapes and thicknesses can be deposited on flexible mica substrates through an inkjet printing and thermal annealing process, playing a key role in signal acquisition (i.e., strain and temperature), data transmission, and component connection. Due to the strong bonding between the high-temperature-resistant circuits, electronic components, and substrate, the developed electronic modules, including amplifiers, low-pass filters, and signal generators, can operate at temperatures up to 650°C. By adjusting the temperature, the output signals of these modules are highly adjustable over a wide range. Therefore, the design of flexible electronic modules and highly integrated systems operating under extreme temperature conditions has been verified, which can be used for stable and reliable electrical signal processing, and has great potential for the future development of flexible electronic systems for high-temperature applications.

[0068] Embodiment 1:

[0069] This embodiment provides a method for preparing a flexible high-temperature resistant amplifying circuit electronic system and its application in preparing target-sized patterns. The specific implementation steps are as follows:

[0070] Step 1, inkjet printing ink preparation:

[0071] 60 mg of ammonium molybdate was added to a 10 mL mixed solution containing water, propylene glycol, and ethanol in a volume ratio of 3:2:1 to form a printable precursor ink. The ink needs to be filtered during the preparation process to avoid nozzle clogging, and a nylon filter was used for pretreatment to ensure the uniformity and stability of the ink.

[0072] Step 2, Substrate surface treatment:

[0073] A flexible mica substrate with a thickness of 20 μm was selected and surface-treated before printing. The substrate was treated using the ultraviolet ozone treatment method for 8 minutes to enhance the hydrophilicity of the substrate and ensure that the ink can effectively adhere to the substrate surface.

[0074] Step 3, Circuit design:

[0075] A three-dimensional laser scanner was used to scan the curved glass substrate, and a patterned design software was used to construct a three-dimensional digital model. The circuit was designed by magnifying according to the actual size of the substrate to ensure the perfect match between the circuit pattern and the target application.

[0076] Step 4, Ink performance optimization:

[0077] Before the printing operation, the ink was filtered again through a 0.22 μm filter to ensure that the viscosity and other properties of the ink meet the best printing requirements, preventing nozzle clogging and other adverse phenomena during the printing process.

[0078] Step 5, Printing process parameter regulation:

[0079] The parameters of the inkjet printer were adjusted. Through pre-printing experiments, the process window was determined, and the printing size under each parameter combination was optimized. The printing speed was 20 mm / s, the printing height was 10 mm, the substrate temperature was 30 °C, and the carrier gas flow rate was 80 sccm to ensure printing accuracy and repeatability. The edges of the printed pattern are relatively clear and neat. As Figure 1 shown, the circuit picture under the optical microscope of the inkjet-printed flexible high-temperature electronic system shows that the circuit has a high resolution. By adjusting the number of printed layers, the light transmittance of the circuit can be adjusted, Figure 4 showing that the circuit has good light transmittance in different wavelength light ranges.

[0080] Step 6, High-temperature circuit printing:

[0081] According to the previously designed circuit pattern, inkjet printing of the ink was carried out to ensure that the printed precursor pattern meets the design circuit pattern standard.

[0082] Step 7, Post-treatment of high-temperature annealing and sintering of the circuit:

[0083] After printing is completed, the printed precursor is dried at 150°C for 10 minutes to evaporate the solvent. Subsequently, the printed mica substrate is transferred to a quartz furnace for thermal annealing. The furnace temperature is raised to 870°C within 60 minutes, maintained for 30 minutes, and then naturally cooled to room temperature to achieve high-temperature sintering of the circuit. Figure 3 As shown, the atomic force microscope test results of the inkjet printed flexible high-temperature electronic system show that its thickness can reach 7.3nm. Figure 2 The successful synthesis and uniform distribution of high-temperature resistant electronic materials were demonstrated, and the circuit was mainly composed of molybdenum elements.

[0084] Step 8, welding layer printing:

[0085] Based on circuit layout rules and pattern design, we select conductive materials suitable for extreme temperatures and accurately print them in the designated locations using a screen printing process. Based on the different curing temperatures of the solder layers, we perform appropriate post-annealing treatment to ensure solder strength and conductivity.

[0086] Step 9: Electronic component stacking structure integration and assembly:

[0087] A microscope is used to manually place high-temperature resistant electronic components, and a 285°C hot plate is used for soldering to achieve effective integration of electronic components and ensure circuit stability and reliability.

[0088] Step 10, circuit packaging:

[0089] Use high temperature resistant insulating materials for large area printing on circuits.

[0090] Step 11, high temperature engine performance test:

[0091] Attach the high-temperature resistant circuit to the engine model to monitor its normal and abnormal working conditions in real time.

[0092] This embodiment prepares a signal amplification circuit system that can operate at 400°C and above. The system architecture diagram is as follows: Figure 5 As shown, it is confirmed that the performance of the amplifier with molybdenum is improved by 13 times compared with the traditional copper circuit ( Figure 6 ). Passed 100h continuous high temperature test, Figure 7 The test results show that the output voltage of the molybdenum amplifier has high signal integrity over a wide temperature range up to 400°C. Therefore, the flexible amplification system can be applied to monitor the operating status of the engine. It can successfully distinguish between normal operation and engine abnormalities with high signal detection resolution, showing great potential in recording and identification. On this basis, this system is used in high-temperature engine monitoring applications. The system is set up as follows Figure 8As shown. The results prove that, compared with traditional and commercial copper and molybdenum electrode sensors, etc., the signal-to-noise ratio of the flexible high-temperature resistant amplifier circuit electronic system reaches the highest ( Figure 9 ), and at the same time, it can accurately monitor the normal and abnormal working states of the engine, such as Figure 10 shown.

[0093] Example 2:

[0094] This example provides a preparation method of a flexible high-temperature resistant filter circuit electronic system and its application in preparing target-size patterns. The specific implementation steps are as follows:

[0095] Step 1, preparation of inkjet printing ink:

[0096] Prepare 60 mg of ammonium tungstate and dissolve it in a 10 mL mixed solution containing water, ethylene glycol, and isopropyl alcohol with a volume ratio of 3:2:1. The selection of this mixed solution can improve the fluidity and printing stability of the ink and ensure the uniformity of droplets during the inkjet printing process. To ensure the smooth use of the nozzle, the ink is filtered using a nylon filter with a pore size of 0.22 μm to prevent nozzle blockage caused by particle precipitation or contamination.

[0097] Step 2, surface treatment of the substrate:

[0098] The three-dimensional substrate selects a flexible mica substrate with a thickness of 20 μm. Before printing, the flexible mica substrate is treated with ultraviolet ozone for 8 min to enhance its hydrophilicity, providing good adhesion for the subsequent printing process and helping to improve the resolution of the circuit pattern.

[0099] Step 3, circuit design:

[0100] Use a three-dimensional laser scanner to scan the curved glass substrate into, and use patterning design software to construct a three-dimensional digital model to obtain its surface feature data in real time. Based on the obtained data, use patterning design software to construct a three-dimensional digital model, and then design the signal amplification circuit.

[0101] Step 4, regulation of printing process parameters:

[0102] Adjust the inkjet process to conduct pre-printing experiments, adjust each process parameter, and make multiple adjustments to the printing speed of 20 mm / s, printing height of 10 mm, substrate temperature of 30 °C, and carrier gas flow rate of 80 sccm to clarify the best process window and the printed size under each parameter combination.

[0103] Step 5, printing of high-temperature resistant circuits:

[0104] Select appropriate parameters according to the designed circuit pattern size for inkjet printing of the ink, ensuring that the viscosity, fluidity, and spraying speed of the ink are all in the best state during the printing process.

[0105] Step 6, Post-treatment of Circuit High-temperature Annealing Sintering:

[0106] After printing, the preliminary drying method of the printed precursor pattern is to evaporate the solvent at 150 °C for 10 minutes, and then transfer the printed precursor to a quartz furnace for heat annealing treatment. During the heat annealing process, the furnace temperature is raised to 920 °C within 60 minutes and maintained for 30 minutes, and finally cooled naturally to room temperature to ensure the density and stability of the circuit pattern. The peel strength test of the flexible high-temperature resistant amplifier circuit electronic system is carried out, Figure 12 proving that at different post-treatment temperatures of no treatment, 500 °C and 900 °C, the bonding ability at 900 °C is the strongest and the performance is the best. Figure 13 It shows that after treatment at 900 °C, the number of glass times reaches 100 times and the resistance value does not change, proving that there is a very strong binding energy between the material and the substrate.

[0107] Step 7, Welding Layer Printing:

[0108] According to the circuit layout rules and patterning design, a silver paste, a conductive material resistant to extreme temperatures, is selected and printed at a specific position using the screen printing process, and then treated at a curing temperature of 80 °C for 1 h for subsequent annealing treatment to ensure a firm bond between the welding layer and the substrate.

[0109] Step 8, Integrated Assembly of Electronic Component Stack Structure:

[0110] The high-temperature resistant electronic components are manually placed under a microscope to ensure the accuracy of positioning. A hot plate at 285 °C is used for welding to achieve electrical connection between components and ensure the integrity and functionality of the circuit.

[0111] Step 9, Circuit Encapsulation:

[0112] The high-temperature resistant insulating material polyimide is printed on the circuit in a large area using the piezoelectric spraying method to protect the circuit from the external environment and improve its reliability.

[0113] The flexible high-temperature resistant filter circuit electronic system fabricated through the above steps is tested in environments of 25 °C and 650 °C, and the results show that low-pass filtering can be effectively achieved at high temperatures ( Figure 11 ). The results show that the stability of the output signal and the voltage amplitude can both be effectively regulated by the fabricated flexible high-temperature resistant filter circuit. By adjusting the environmental temperature, linear controllable modulation of the passband of the high-temperature encryption system can be achieved, thus successfully completing the extraction, separation, and identification of mixed frequency signals. Figure 14 It shows that the high-temperature resistance performance of this material reaches 900 °C, and different samples have excellent repeatability and consistency.

[0114] Example 3:

[0115] This embodiment provides a preparation method of a flexible high-temperature resistant signal generation circuit system and its application in preparing a target-size pattern. The specific implementation steps are as follows:

[0116] Step 1, preparation of inkjet printing ink:

[0117] 60 mg of ammonium molybdate / ammonium niobate mixture is added to a 10 mL mixed solution containing propylene glycol, ethanol and isopropanol, and the volume ratio is 3:2:1. Stir well to form a uniform printing ink. Considering the fluidity and printing performance of the ink, a nylon filter with a pore size of 0.22 μm is used for filtration to prevent nozzle clogging, thereby ensuring the smooth progress of the inkjet printing process.

[0118] Step 2, surface treatment of the substrate:

[0119] In this embodiment, flexible mica with a thickness of 20 μm is selected as the substrate. The hydrophilicity of the substrate is crucial for good printing results. Before printing, the mica substrate is treated by ultraviolet ozone treatment technology for 8 minutes to enhance its hydrophilicity, thereby improving the ink wettability and ensuring the clarity and accuracy of the circuit pattern.

[0120] Step 3, circuit design:

[0121] Use a three-dimensional laser scanner to scan the curved glass substrate, use patterning design software to construct a three-dimensional digital model, and design a signal amplification circuit according to the substrate size.

[0122] Step 4, regulation of printing process parameters:

[0123] Adjust the inkjet process to conduct pre-printing experiments, adjust each process parameter, and clarify the process window and the printed size under each parameter combination.

[0124] Step 5, printing of high-temperature resistant circuits:

[0125] Ensure the uniformity of ink flow and precise control of the printing speed, and select appropriate parameters according to the designed circuit pattern size for inkjet printing of the ink.

[0126] Step 6, post-treatment of high-temperature annealing and sintering of the circuit:

[0127] After printing, the printed precursor pattern is dried at 150 °C for 10 min for solvent evaporation. Then, the precursor on the mica is transferred to a quartz furnace for thermal annealing. The temperature of the furnace chamber is raised to 950 °C and maintained for 30 min, and then naturally cooled to room temperature.

[0128] Step 7, printing of the welding layer:

[0129] According to the circuit layout rules and patterning design, a high-temperature resistant conductive silver paste is selected and printed at specific positions using the screen printing process. Subsequently, annealing is carried out in an air atmosphere at 80 °C for 1 h to cure the welding layer.

[0130] Step 8, integrated assembly of the electronic component stack structure:

[0131] The high-temperature resistant electronic components are manually placed under a microscope and soldered using a 285 °C hot plate.

[0132] Step 9, circuit encapsulation:

[0133] A high-temperature resistant insulating material, polyimide, is used for large-area printing on the circuit.

[0134] Figure 15 The test results show that the high-temperature resistant signal generation circuit system can stably generate a sine wave signal without distortion at 400 °C. On this basis, Figure 16 The high-precision preparation at the nanoscale and resistivity test of the high-temperature signal generation circuit are carried out, and the results prove that the system can stably generate a specific waveform signal.

[0135] Comparative Example 1:

[0136] Step 1, preparation of the inkjet printing ink:

[0137] 60 mg of ammonium molybdate is added to a 10 mL mixed solution containing water, propylene glycol, and ethanol with volume ratios of 2:1:1 respectively to form a printable precursor ink.

[0138] Step 2, surface treatment of the substrate:

[0139] A flexible mica substrate with a thickness of 20 μm is selected and surface-treated before printing. The substrate is treated using the ultraviolet ozone treatment method for 8 minutes.

[0140] Step 3, circuit design:

[0141] A three-dimensional laser scanner is used to scan the curved glass substrate, and a three-dimensional digital model is constructed using patterning design software.

[0142] Step 4, ink performance optimization:

[0143] Before the printing operation, the ink is filtered again through a 0.22 μm filter to prevent nozzle clogging and other adverse phenomena during printing.

[0144] Step 5, adjustment of printing process parameters:

[0145] Adjust the parameters of the inkjet printer and optimize the printing size under various parameter combinations. The printing speed is 20 mm / s, the printing height is 10 mm, the substrate temperature is 30 °C, and the carrier gas flow rate is 80 sccm.

[0146] Step 6, high-temperature circuit printing:

[0147] Perform inkjet printing according to the previously designed circuit pattern.

[0148] Step 7, post-treatment of high-temperature annealing of the circuit:

[0149] After printing, dry the printed precursor at 150 °C for 10 minutes to evaporate the solvent. Subsequently, transfer the printed mica substrate to a quartz furnace for thermal annealing. The furnace temperature rises to 870 °C within 60 minutes, maintains for 30 minutes, and then cools naturally to room temperature to achieve high-temperature sintering of the circuit.

[0150] The physical object of the high-temperature resistant circuit diagram obtained in Comparative Example 1 is as Figure 17 shown. During the printing process, there are adverse effects such as satellite ink droplets. The results show that the resolution of the printed circuit is poor and errors such as short circuits occur.

[0151] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. An ink for inkjet printing, characterized in that, The materials for making the ink are selected from at least one of ammonium molybdate, ammonium tungstate, ammonium niobate, niobium oxalate, and tantalum ethoxide; The solvent for making the ink is a mixed solvent of at least three of water, propylene glycol, ethanol, ethylene glycol, and isopropyl alcohol; The viscosity of the ink is less than 20 CPS, and the solution particles are less than 1 μm.

2. The ink for inkjet printing according to claim 1, wherein, The volume ratio of each component in the three-component mixed solvent is 3:2:

1.

3. The ink for inkjet printing according to claim 1 or 2, characterized in that, The volume of the mixed solution for making the ink is 10 mL, and the addition amount of the materials for making the ink is 60 mg.

4. A method for preparing a flexible high-temperature resistant electronic system using the ink for inkjet printing according to claim 1 or 2, characterized in that, It includes the following steps: Substrate surface treatment, circuit design, printing process parameter regulation, high-temperature resistant circuit printing, post-treatment of high-temperature annealing and sintering of the circuit, welding layer printing, integrated assembly of the electronic component stack structure, and circuit packaging; The printing process parameters are: printing speed 20 mm / s, printing height 10 mm, substrate temperature 30 °C, and carrier gas flow rate 80 sccm.

5. The method for preparing a flexible high-temperature resistant electronic system according to claim 4, wherein The post-treatment of high-temperature annealing and sintering of the circuit includes: according to the curing and sintering temperatures of different materials, selecting a suitable post-treatment method to perform solvent evaporation and sintering curing on the printed precursor pattern; After printing, the printed precursor pattern is dried at 150 °C for 10 min for solvent evaporation. Then, the precursor on the substrate is transferred to a quartz furnace for thermal annealing; the temperature of the furnace chamber is 700 - 1000 °C, maintained for 30 min, and then naturally cooled to room temperature.

6. The method for preparing a flexible high-temperature resistant electronic system according to claim 4, characterized in that: The substrate surface treatment includes: Using argon plasma to clean the substrate surface to remove impurities and obtain a uniform surface; using ultraviolet / ozone plasma to treat the substrate surface to generate hydrophilic functional groups and adjust the substrate surface energy.

7. The method for preparing a flexible high-temperature resistant electronic system according to claim 4, characterized in that: The substrate is selected from one of mica, polyimide, and ceramic.

8. The method for preparing a flexible high-temperature resistant electronic system according to claim 4, characterized in that, The ink is also filtered with a nylon filter with a pore size of 0.22 μm.

9. The method for preparing a flexible high-temperature resistant electronic system according to claim 4, characterized in that, The conductive materials used in the welding layer include high-temperature resistant conductive pastes such as silver paste, silver glue, and silver-palladium paste; The sample is annealed at 80 °C for 60 min to completely dry the conductive glue.

10. A flexible high temperature resistant electronic system, characterized in that: It is prepared by using the method for preparing a flexible high-temperature resistant electronic system according to any one of claims 4 - 9.

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