Thermistor and manufacturing method

Abstract

The invention provides a thermosensitive resistor and a manufacturing method. The thermosensitive resistor comprises a substrate, electrodes and a protective layer, the matrix is prepared from a nano-scale ceramic powder and high-molecular polymer composite material, the nano-scale ceramic powder is uniformly dispersed in a high-molecular polymer, and the high-molecular polymer is polyimide; the electrode is made of an alloy material composed of silver, palladium and rare earth elements, and the electrode is deposited on the surface of the base body through the physical vapor deposition technology. The protective layer wraps the surfaces of the base body and the electrodes, the protective layer is composed of a multi-layer composite material, and the multi-layer composite material comprises an inner layer, a middle layer and an outer layer. Compared with a traditional product, the size is greatly reduced, the development requirement for miniaturization of electronic equipment is met, meanwhile, the layering failure problem caused by thermal expansion under large-current impact is effectively prevented, and the stability of product performance is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermistors, in particular to a thermistor and a manufacturing method. BACKGROUND

[0002] With the development of electronic technology, electronic devices are rapidly advancing towards miniaturization and thinness at an unprecedented speed. From smartphones to wearable devices, from tablets to micro sensors, each subfield has put forward extremely strict requirements for the size and integration of electronic components. In this industry background, the miniaturization of thermistors, as an indispensable key component in electronic circuits, has become imminent. Thermistors play an important role in temperature sensing and over-temperature protection in circuits, and their stability and size directly affect the efficiency and reliability of the entire electronic device.

[0003] However, the current thermistors have exposed a series of problems in actual use: Traditional plug-in thermistors are usually installed by inserting the pins into the circuit board. Structurally, it is generally composed of a thermistor body, pins and a protective packaging shell. The thermistor body is the core component, responsible for sensing temperature changes and changing its resistance value; the pins are used to connect the resistor body with the circuit on the circuit board to realize the transmission of electrical signals; the packaging shell protects the thermistor body from external environmental interference.

[0004] However, due to its large overall volume, it has obvious disadvantages in size. For example, the diameter of the common round plug-in thermistor is usually several millimeters to tens of millimeters, and the pin length is also relatively long. This large volume makes it difficult to adapt to the compact internal space layout of modern electronic devices. In today's pursuit of ultra-thin electronic devices, the space on the internal circuit board is indeed valuable, and the placement of each component needs careful planning. The traditional plug-in thermistor often occupies too much space, making it difficult to layout the circuit board, and even unable to install, thus failing to meet the urgent needs of electronic device miniaturization.

[0005] In order to adapt to the development trend of electronic device miniaturization, miniaturized surface mount thermistors have emerged. Surface mount thermistors have undergone major structural improvements. They are usually installed using surface mount technology (SMT) and are directly soldered to the surface of the circuit board. Its structure mainly includes a thermistor chip, electrodes and a packaging layer. The thermistor chip is the core part of temperature sensing, the electrodes are used to connect the chip with the circuit board, and the packaging layer protects the chip and electrodes.

[0006] This structure achieves a significant reduction in size to some extent, better adapting to the compact internal space of modern electronic devices. However, under high current surges, miniaturized surface-mount thermistors are prone to thermal delamination failure. From a structural perspective, traditional surface-mount thermistors experience stress due to differences in their coefficients of thermal expansion when high currents pass through them. For example, the sensing material and electrode material in the thermistor chip have different coefficients of thermal expansion. When a high current passes through, the chip heats up rapidly, and the different degrees of thermal expansion cause relative displacement between the materials, leading to delamination. This delamination damages the internal structure of the thermistor, resulting in performance degradation or even complete failure. In practical applications, once a thermistor fails, it may be unable to detect temperature changes in a timely manner, thus failing to provide effective over-temperature protection for electronic devices and posing serious safety hazards.

[0007] In summary, traditional through-hole thermistors, due to their large size, are difficult to fit into the compact internal space layout of modern electronic devices and cannot meet the miniaturization requirements. While miniaturized surface-mount products achieve a certain degree of size reduction, they are prone to thermal delamination failure under high current surges. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of the existing technology. The present invention proposes a thermistor and a manufacturing method thereof.

[0009] To address the issue that traditional through-hole thermistors, due to their large size, are difficult to fit into the compact internal space of modern electronic devices and cannot meet miniaturization requirements, and while miniaturized surface-mount products achieve some size reduction, they are prone to thermal delamination failure under high current surges, the technical solution adopted in this invention is: A thermistor includes: a substrate, electrodes, and a protective layer; The matrix is ​​made of a composite material of nano-sized ceramic powder and polymer, wherein the nano-sized ceramic powder is uniformly dispersed in the polymer, and the polymer is polyimide. The electrode is made of an alloy material composed of silver, palladium and rare earth elements, and the electrode is deposited on the surface of the substrate by physical vapor deposition technology. The protective layer is wrapped around the substrate and electrode surface, and the protective layer is composed of a multilayer composite material, which includes an inner layer, a middle layer and an outer layer.

[0010] Preferably, the particle size range of the nano-sized ceramic powder is 10-100 nm, and the thickness of the matrix is ​​0.1-0.5 mm; The electrode contains 60%–80% silver, 15%–30% palladium, and 1%–5% rare earth elements, and the electrode layer thickness is 0.01–0.05 mm. The inner layer is a hydrophobic nano-coating, the middle layer is a buffer material, and the outer layer is a wear-resistant ceramic coating. The total thickness of the protective layer is 0.05 to 0.2 mm.

[0011] Preferably, the nano-sized ceramic powder is alumina or silicon nitride, and the buffer material is silicone rubber.

[0012] Preferably, the hydrophobic nano-coating is a fluorinated polyethylene nano-coating, and the wear-resistant ceramic coating is an alumina ceramic coating.

[0013] Preferably, the method for manufacturing the thermistor includes the following steps: S1. Preparation of the matrix: Nano-sized ceramic powder and polymer are mixed in proportion, dispersant and solvent are added, and the mixture is stirred evenly in a high-speed mixer to form a slurry; the slurry is made into a thin sheet by a casting process, and then sintered at a high temperature of 1100-1300℃ for 6-24 hours to obtain the matrix; S2. Electrode deposition: The prepared substrate is placed in a physical vapor deposition apparatus. Under vacuum, alloy atoms are deposited on both sides or one side of the substrate surface by heating the alloy target to form an electrode layer. The deposition rate and deposition time are controlled during the deposition process to ensure that the thickness of the electrode layer is uniform. S3. Preparation of the protective layer: First, a hydrophobic nano-coating is deposited on the electrode surface using chemical vapor deposition technology at a deposition temperature of 100-200℃ and a deposition time of 0.5-1 hour; then, the substrate with the hydrophobic nano-coating is immersed in a silicone rubber solution for 1-2 hours, followed by drying and curing at room temperature to form a buffer layer; finally, a wear-resistant ceramic coating is sprayed onto the surface of the buffer layer using plasma spraying technology at a spraying power of 20-50kW and a spraying distance of 50-100mm to form an outer protective layer.

[0014] Preferably, in the matrix preparation step, the dispersant is polyethylene glycol and the solvent is N-methylpyrrolidone.

[0015] Preferably, in the substrate preparation step, the casting speed of the casting process is 0.5 to 2 m / min.

[0016] Preferably, in the electrode deposition step, the alloy target is an alloy target composed of silver, palladium, and a small amount of rare earth elements, with a silver content of 60%–80%, a palladium content of 15%–30%, and a rare earth element content of 1%–5%, and the vacuum degree of the physical vapor deposition equipment is 1×10⁻³–1×10⁻5 Pa.

[0017] Preferably, in the preparation step of the protective layer, the reaction gas of the chemical vapor deposition technique is a mixture of carbon tetrafluoride and hydrogen, and the volume ratio of carbon tetrafluoride to hydrogen in the mixture is 1:2-1:5.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention uses nano-scale ceramic powder and polymer composite material to make the matrix. The thickness of the matrix is ​​precisely controlled to 0.1-0.5 mm through a casting process. Compared with traditional products, the volume is greatly reduced, which meets the development needs of miniaturization of electronic devices.

[0019] The nanoscale ceramic powder in this invention possesses high thermal conductivity, enabling rapid heat dissipation and reducing heat accumulation within the matrix. The polymers, such as polyimide or polyphenylene sulfide, exhibit excellent high-temperature resistance, withstanding the high temperatures generated by high-current impacts without performance degradation. Simultaneously, the uniform matrix structure prepared by the casting process avoids thermal expansion differences caused by uneven material distribution, effectively preventing delamination failure due to thermal expansion under high-current impacts and ensuring product performance stability. Attached Figure Description

[0020] The disclosure of this invention is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this invention. In the drawings, the same reference numerals are used to refer to the same parts. Wherein: Figure 1 This is a schematic diagram of the overall structure of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the overall structure of the present invention. Figure 2 ; Figure 3 This is a schematic block diagram illustrating the overall components of the present invention; Figure 4 This is a schematic block diagram of the matrix composition materials of the present invention; Figure 5 This is a schematic block diagram of the electrode composition materials of the present invention; Figure 6 This is a schematic block diagram of the protective layer composition materials of the present invention; Figure 7 This is a schematic block diagram illustrating the manufacturing method steps of the present invention. Detailed Implementation

[0021] It is readily understood that, based on the technical solution of this invention, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of the invention. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative examples of the technical solution of this invention and should not be considered as the entirety of the invention or as limitations or restrictions on the technical solution of this invention.

[0022] Specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0023] Please see Figure 1 - Figure 6 This embodiment proposes a thermistor, which mainly consists of three parts: a substrate, an electrode, and a protective layer.

[0024] The matrix is ​​made of a composite material of nano-sized ceramic powder and polymer. The nano-sized ceramic powder is selected from materials such as alumina and silicon nitride, which possess high thermal conductivity and good electrical properties. Its particle size is strictly controlled within the range of 10-100 nm to ensure uniform dispersion of the powder within the polymer. The polymer is selected from polyimide or polyphenylene sulfide, both of which exhibit excellent high-temperature resistance and chemical corrosion resistance. The matrix is ​​prepared using a special casting process, with its thickness precisely controlled between 0.1 and 0.5 mm. This achieves miniaturization while ensuring sufficient mechanical strength and thermal stability to withstand the heat generated during high-current impacts, preventing delamination failure due to thermal expansion.

[0025] The electrodes utilize a novel alloy material composed of silver, palladium, and trace amounts of rare earth elements (such as lanthanum and cerium). The silver content is 60%–80% to ensure low electrical resistance; the palladium content is 15%–30% to improve oxidation resistance; and the rare earth element content is 1%–5% to refine the grain size and enhance adhesion and mechanical properties. The electrodes are deposited on both sides or one side of the substrate surface using physical vapor deposition (PVD) technology, forming a uniform electrode layer with a thickness of 0.01–0.05 mm. The two electrodes are insulated from each other by the substrate. PVD technology enables high-precision deposition at low temperatures, avoiding thermal damage to the substrate while ensuring good adhesion between the electrode and the substrate.

[0026] The protective layer is composed of multiple layers of composite materials, consisting of a hydrophobic nano-coating, a buffer material layer, and a wear-resistant ceramic coating from the inside out. The inner hydrophobic nano-coating uses fluorinated polyethylene nano-coating, which possesses excellent hydrophobicity and chemical stability, effectively preventing the intrusion of moisture and oil, and avoiding resistance drift caused by environmental factors. The middle buffer material layer uses silicone rubber, which has good elasticity and energy absorption properties, absorbing vibration energy, reducing the impact of vibration on the internal structure of the thermistor, and improving the product's vibration resistance. The outer wear-resistant ceramic coating uses alumina ceramic coating, which has high hardness, high wear resistance, and good corrosion resistance, improving the thermistor's wear resistance and scratch resistance, and extending the product's service life. The total thickness of the protective layer is controlled between 0.05 and 0.2 mm to minimize the impact on the overall dimensions of the product while ensuring protective performance.

[0027] Please see Figure 7 The method for manufacturing the thermistor of the present invention includes the following detailed steps: Matrix preparation: First, accurately weigh the nano-sized ceramic powder and polymer at a specific ratio, then add appropriate amounts of dispersant (such as polyethylene glycol) and solvent (such as N-methylpyrrolidone). In a high-speed mixer, stir and mix thoroughly at 1000-2000 rpm to form a homogeneous slurry. Strict control of time and temperature is necessary during stirring to ensure the slurry's performance stability.

[0028] Next, the slurry is cast into thin sheets using a casting process. During casting, the casting speed is controlled at 0.5–2 m / min, and the doctor blade gap is precisely adjusted to ensure uniform sheet thickness. The cast sheets are then allowed to dry naturally in a dry environment or dried using a low-temperature drying device.

[0029] Finally, the dried sheets are placed in a high-temperature sintering furnace for sintering. The sintering temperature is controlled at 1100-1300℃, and the sintering time is 6-24 hours. During the sintering process, the heating and cooling rates must be precisely controlled to avoid cracking or deformation of the sheets due to excessively rapid temperature changes, thereby obtaining a matrix with excellent performance.

[0030] Electrode deposition: The prepared substrate is placed in a physical vapor deposition (PVD) apparatus, and the apparatus is evacuated to a vacuum level of 1×10⁻³ -1×10⁻⁻. 5 Pa, to create a favorable sedimentation environment.

[0031] An alloy target composed of silver, palladium, and a small amount of rare earth elements is heated, causing the alloy atoms to evaporate and deposit on the substrate surface at high temperature. During the deposition process, the deposition rate (0.1-0.5 nm / s) and deposition time are precisely controlled to ensure a uniform electrode layer thickness of 0.01–0.05 mm. Simultaneously, a rotating substrate method is used to ensure that the electrode material can be uniformly deposited to cover both sides or one side of the substrate surface.

[0032] Protective layer preparation: First, a hydrophobic nanocoating is deposited on the electrode surface using chemical vapor deposition (CVD). The substrate with the electrode is placed in a CVD apparatus, and a reactive gas (a mixture of carbon tetrafluoride and hydrogen, with a volume ratio of carbon tetrafluoride to hydrogen of 1:2-1:5) is introduced. Under the conditions of deposition temperature of 100-200℃ and deposition time of 0.5-1 hour, a uniform fluorinated polyethylene nanocoating is formed.

[0033] The substrate with the hydrophobic nano-coating is then immersed in a silicone rubber solution for 1-2 hours, allowing the silicone rubber to adhere evenly to the surface of the hydrophobic nano-coating and form a buffer layer. The substrate is then removed from the solution and dried and cured at room temperature to allow the silicone rubber to fully cross-link, improving the performance of the buffer layer.

[0034] Finally, a wear-resistant ceramic coating is applied to the surface of the buffer layer using plasma spraying technology. The spraying power of the plasma spraying equipment is adjusted to 20-50kW, and the spraying distance to 50-100mm, to spray alumina ceramic powder onto the surface of the buffer layer, forming an outer protective layer. During the spraying process, the spraying angle and speed must be controlled to ensure a uniform and dense ceramic coating.

[0035] Please continue reading. Figure 1 - Figure 7 The beneficial effects of this invention are: Miniaturization: Traditional plug-in thermistors are bulky and difficult to fit into the compact internal space of modern electronic devices. This invention uses a matrix made of nano-scale ceramic powder and polymer composite material, and precisely controls the matrix thickness to 0.1–0.5 mm through a casting process. Compared to traditional products, this significantly reduces the size, meeting the miniaturization needs of electronic devices.

[0036] Performance Stability Guarantee: During miniaturization, thermal delamination failure under high-current impact is a common problem. In this invention, the nano-scale ceramic powder has high thermal conductivity, enabling rapid heat dissipation and reducing heat accumulation within the matrix. The polymers, such as polyimide or polyphenylene sulfide, possess excellent high-temperature resistance, withstanding the high temperatures generated by high-current impacts without performance degradation. Simultaneously, the uniform matrix structure prepared by the casting process avoids thermal expansion differences caused by uneven material distribution, effectively preventing delamination failure due to thermal expansion under high-current impacts and ensuring product performance stability. For example, in simulated high-current impact tests, the thermistor of this invention exhibits minimal resistance change and stable performance after prolonged high-current flow, while traditional miniaturized surface-mount products show significant resistance drift or even failure.

[0037] Process Simplification and Optimization: Although the manufacturing method of this invention involves multiple steps such as substrate preparation, electrode deposition, and protective layer preparation, these processes are relatively mature and easy to control. Casting can precisely control the thickness and uniformity of the substrate, reducing the difficulty and cost of subsequent processing; physical vapor deposition (PVD) technology can achieve high-precision electrode deposition at low temperatures, avoiding thermal damage to the substrate at high temperatures, while ensuring good adhesion between the electrode and the substrate, reducing the defect rate due to poor adhesion; chemical vapor deposition (CVD) and plasma spraying technologies can precisely control the thickness and performance of the protective layer, improving product quality and reliability.

[0038] Cost control: By optimizing material formulations and process parameters, raw material waste is reduced. For example, in the matrix preparation process, precise control of the ratio of nanoscale ceramic powder to polymer, as well as the amount of dispersant and solvent, avoids excessive material use. Simultaneously, standardized process flow and equipment selection help improve production efficiency and reduce equipment debugging and maintenance costs. Furthermore, the manufacturing method of this invention reduces the defect rate during production, further lowering production costs. Compared with existing technologies, effective cost control is achieved while ensuring product quality.

[0039] Adaptability to Humid and Hot Environments: In humid and hot environments, moisture and oil can easily penetrate the interior of the thermistor, causing resistance drift or even failure. In this invention, the inner hydrophobic nano-coating of the protective layer is made of fluorinated polyethylene nano-coating, which possesses excellent hydrophobicity and chemical stability. In humid and hot environments, the fluorinated polyethylene nano-coating effectively prevents the intrusion of moisture and oil, keeping the interior of the thermistor dry and clean, thus avoiding resistance drift caused by environmental factors. For example, in long-term testing in a simulated high-temperature and high-humidity environment, the resistance of the thermistor of this invention shows minimal change and remains stable, while existing products exhibit significant resistance changes under the same conditions.

[0040] Vibration Environment Adaptability: In a vibration environment, the internal structure of components may loosen or be damaged due to vibration, affecting their reliability. In this invention, the intermediate buffer material of the protective layer is silicone rubber, which has good elasticity and energy absorption properties. When the thermistor is subjected to vibration, the silicone rubber can absorb the vibration energy, reducing the impact of vibration on the internal structure, thereby protecting the integrity of the electrodes and the substrate and improving the product's vibration resistance. For example, in vibration simulation tests, the thermistor of this invention maintained its internal structure intact and its performance did not significantly decline after prolonged vibration, while existing products exhibited problems such as electrode loosening and substrate cracking.

[0041] Wear Resistance and Scratch Resistance: Thermistors may be subjected to friction and scratches during use, affecting their appearance and performance. In this invention, the outer wear-resistant ceramic coating of the protective layer is made of alumina ceramic, which possesses high hardness, high wear resistance, and good corrosion resistance. The alumina ceramic coating effectively resists friction and scratches, protecting the thermistor's surface from damage and extending the product's lifespan. For example, in wear resistance tests, the thermistor of this invention remained smooth after repeated friction, and its performance was unaffected, while existing products showed obvious scratches and performance degradation.

[0042] Example 1: Smartphone Temperature Monitoring Application Background: When smartphones run high-performance applications (such as games and video rendering), the processor temperature may soar to over 80°C. Traditional thermistors are difficult to meet the requirements for precise temperature control due to their large size or unstable performance.

[0043] Applications and Testing: Installation location: The thermistor of this invention (substrate thickness 0.3mm, electrode layer thickness 0.03mm) is mounted on the surface of the smartphone processor and directly soldered onto the circuit board using SMT process.

[0044] Performance testing: High-temperature test: Temperature was continuously monitored under full processor load (10W). The results showed that the thermistor's resistance value responded linearly to temperature changes, with an error range of ≤±0.5℃, which is 30% more accurate than traditional surface mount resistors.

[0045] High-current surge test: Simulating a transient current surge (5A, lasting 10ms), the thermistor substrate temperature rose by only 5°C, with no delamination or performance degradation observed. Traditional surface mount resistors, under the same conditions, experienced a resistance drift of up to 15%.

[0046] Long-term stability test: After 1000 hours of continuous operation at 60℃ / 90%RH, the resistance value changes by <1%, and the hydrophobic nano-coating (fluorinated polyethylene) effectively blocks moisture intrusion.

[0047] Results: Through precise temperature control, the phone processor temperature is reduced by 8°C compared to using traditional resistors, game frame rate stability is improved by 20%, and the user's touch temperature is reduced by 5°C.

[0048] Test data comparison: Example 2: Overheat Protection of New Energy Vehicle Battery Packs Background: In fast charging or high-temperature environments, the local temperature of electric vehicle battery packs may exceed 60°C, requiring a rapid response (response time <1s) to prevent thermal runaway.

[0049] Applications and Testing: Installation location: The thermistor of this invention (0.2mm substrate thickness, 0.1mm total protective layer thickness) is mounted on the surface of each cell in the battery module and connected to the BMS via a flexible circuit board (FPC).

[0050] Performance testing: Response speed test: Simulating local overheating of the battery cell (from 25℃ to 60℃), the change in the thermistor resistance value triggered the BMS alarm in only 0.8s, which is 0.5s faster than the traditional NTC resistor.

[0051] Vibration test: After 4 hours of continuous vibration at a frequency of 10-2000Hz and an acceleration of 5g, the silicone rubber buffer layer absorbs more than 90% of the vibration energy, and the resistance value changes by <0.3%.

[0052] Abrasion resistance test: During the battery pack assembly process, after the resistor surface was rubbed 10 times (load 5N), the alumina ceramic coating showed no scratches and the resistance value did not change.

[0053] Results: In a real-world test on a certain vehicle model, the incidence of battery pack thermal runaway events was reduced by 70%, and the BMS false alarm rate dropped to below 0.1%.

[0054] Test data comparison: Example 3: Vibration Resistance Applications of Industrial Control Equipment Background: Industrial robot controllers need to operate stably for a long time in environments with vibration (acceleration of 10g) and oil contamination. Traditional resistors are prone to loosening or corrosion failure due to vibration.

[0055] Applications and Testing: Installation position: The thermistor of the present invention (substrate thickness 0.5mm, wear-resistant ceramic coating thickness 50μm) is installed on the surface of the heat sink of the controller power module and fixed by spring clamps.

[0056] Performance testing: Vibration test: After continuous vibration for 100 hours on a triaxial vibration table (frequency 5-500Hz, acceleration 10g), the bonding force between the resistor and the substrate remained >5N, and no detachment occurred.

[0057] Oil stain test: After immersing the resistor in industrial lubricating oil (temperature 80℃) for 72 hours, the contact angle of the hydrophobic coating surface is >120° and the resistance value changes by <0.5%.

[0058] High-temperature life test: After working at 125℃ for 2000 hours, the resistance drift is <2%, which meets the industrial standard (AEC-Q200).

[0059] Results: The controller failure rate was reduced from an average of 5 times per year to 1 time, and maintenance costs were reduced by 60%.

[0060] Test data comparison: Example 4: Extreme Environment Resistance Applications of Aerospace Electronic Equipment Background: Avionics equipment needs to operate stably in a temperature range of -55℃ to 125℃ and in a strong radiation environment. Traditional resistors are prone to failure due to thermal expansion mismatch or radiation damage.

[0061] Applications and Testing: Installation location: The resistor of this invention (the base material is silicon nitride / polyimide composite material) is used in the satellite power management module and is connected to the circuit board by gold wire bonding.

[0062] Performance testing: Temperature cycling test: After 1000 cycles between -55℃ and 125℃, the resistance value changed by <0.3%, and the substrate did not crack (the thermal stress distribution was optimized by the casting process).

[0063] Radiation test: After irradiation with a total dose of 50 kRad of gamma rays, the resistance value changed by <0.1%, which is better than the military-grade standard (MIL-STD-883).

[0064] Results: The satellite has not experienced any power failures due to thermistor failure during its three years of operation in orbit, and its lifespan is expected to be extended to 15 years.

[0065] Test data comparison: The above embodiments demonstrate that the present invention, through its nanocomposite matrix, novel alloy electrodes, and multi-layer protective layer design, significantly outperforms traditional technologies in terms of miniaturization, vibration resistance, and environmental resistance, making it suitable for high-reliability applications. Test data quantitatively verifies its effectiveness in resolving the contradictions between "miniaturization and performance stability," "process complexity and cost," and "environmental adaptability and reliability."

[0066] The technical scope of this invention is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this invention, and all such modifications and variations should fall within the protection scope of this invention.

Claims

1. A thermistor, characterized in that, include: Substrate, electrodes, and protective layer; The matrix is ​​made of a composite material of nano-sized ceramic powder and polymer, wherein the nano-sized ceramic powder is uniformly dispersed in the polymer, and the polymer is polyimide. The electrode is made of an alloy material composed of silver, palladium and rare earth elements, and the electrode is deposited on the surface of the substrate by physical vapor deposition technology. The protective layer is wrapped around the substrate and electrode surface, and the protective layer is composed of a multilayer composite material, which includes an inner layer, a middle layer and an outer layer.

2. The thermistor according to claim 1, characterized in that: The particle size range of the nano-sized ceramic powder is 10-100 nm, and the thickness of the matrix is ​​0.1-0.5 mm; The electrode contains 60%–80% silver, 15%–30% palladium, and 1%–5% rare earth elements, and the electrode layer thickness is 0.01–0.05 mm. The inner layer is a hydrophobic nano-coating, the middle layer is a buffer material, and the outer layer is a wear-resistant ceramic coating. The total thickness of the protective layer is 0.05 to 0.2 mm.

3. The thermistor according to claim 2, characterized in that, The nano-scale ceramic powder is alumina or silicon nitride, and the buffer material is silicone rubber.

4. The thermistor according to claim 2, characterized in that, The hydrophobic nano-coating is a fluorinated polyethylene nano-coating, and the wear-resistant ceramic coating is an alumina ceramic coating.

5. The method for manufacturing the thermistor according to claim 1, characterized in that, Includes the following steps: S1. Preparation of the matrix: Nano-sized ceramic powder and polymer are mixed in proportion, dispersant and solvent are added, and the mixture is stirred evenly in a high-speed mixer to form a slurry; the slurry is made into a thin sheet by a casting process, and then sintered at a high temperature of 1100-1300℃ for 6-24 hours to obtain the matrix; S2. Electrode deposition: The prepared substrate is placed in a physical vapor deposition apparatus. Under vacuum, alloy atoms are deposited on both sides or one side of the substrate surface by heating the alloy target to form an electrode layer. The deposition rate and deposition time are controlled during the deposition process to ensure that the thickness of the electrode layer is uniform. S3. Preparation of the protective layer: First, a hydrophobic nano-coating is deposited on the electrode surface using chemical vapor deposition technology at a deposition temperature of 100-200℃ and a deposition time of 0.5-1 hour; then, the substrate with the hydrophobic nano-coating is immersed in a silicone rubber solution for 1-2 hours, followed by drying and curing at room temperature to form a buffer layer; finally, a wear-resistant ceramic coating is sprayed onto the surface of the buffer layer using plasma spraying technology at a spraying power of 20-50kW and a spraying distance of 50-100mm to form an outer protective layer.

6. The method for manufacturing a thermistor according to claim 5, characterized in that, In the preparation step of the matrix, the dispersant is polyethylene glycol and the solvent is N-methylpyrrolidone.

7. The method for manufacturing a thermistor according to claim 5, characterized in that, In the substrate preparation step, the casting speed of the casting process is 0.5 to 2 m / min.

8. The method for manufacturing a thermistor according to claim 5, characterized in that, In the electrode deposition step, the alloy target is an alloy target composed of silver, palladium, and a small amount of rare earth elements, with a silver content of 60%–80%, a palladium content of 15%–30%, and a rare earth element content of 1%–5%. The vacuum degree of the physical vapor deposition equipment is 1×10⁻³–1×10⁻ 5 Pa.

9. The method for manufacturing a thermistor according to claim 5, characterized in that, In the preparation step of the protective layer, the reaction gas of the chemical vapor deposition technology is a mixture of carbon tetrafluoride and hydrogen, and the volume ratio of carbon tetrafluoride to hydrogen in the mixture is 1:2-1:5.

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