High-current power type thermosensitive chip and preparation method thereof

Abstract

The invention discloses a high-current power type thermosensitive chip and a preparation method thereof. The current bearing capacity of the chip is remarkably improved on the premise that the product size is not increased, and the technical scheme is as follows: the thermosensitive chip is made of a composite material, and the composite material comprises a main material and a composite additive; the main material comprises the following components in percentage by weight: 30 to 70 percent of manganous-manganic oxide (MnO), 10 to 30 percent of zinc oxide (ZnO), 8 to 20 percent of copper oxide (CuO) and 1 to 10 percent of cobaltosic oxide (CoO); the composite additive accounts for 1-10% of the weight of the main material; the invention has the following beneficial effects: a multi-layer annular structure design is adopted to form a collaborative heat dissipation mechanism, which is beneficial to simultaneous dissipation of heat in the up and down directions, and avoids the'hot bottleneck 'effect of heat accumulation in the central area of a solid structure; the technical bottleneck that a traditional power type thermistor depends on increasing the size and improving the current capacity is effectively solved, the outstanding industrial application value is achieved, and meanwhile the thermal stability and durability are improved.

Description

Technical Field

[0001] This invention belongs to the field of electronic component fabrication technology, and more specifically, it relates to a high-current power thermistor chip and its fabrication method. Background Technology

[0002] Negative temperature coefficient (NTC) thermistors are important electronic components widely used in surge current suppression, temperature measurement, and control. Power-type NTC thermistors are particularly suitable for absorbing surge currents during circuit startup, protecting electronic equipment from overcurrent surges. The current carrying capacity of traditional power-type NTC thermistors is closely related to their size, typically requiring increased chip size to improve current capacity. For example, a thermistor chip with a rated current of 10A requires a diameter of approximately 30mm, while a chip with a rated current of 12A requires a diameter of 20mm, with a resistance of approximately 0.7Ω.

[0003] This "space-for-performance" design approach has obvious limitations: First, the increased chip size leads to increased raw material consumption and higher manufacturing costs; second, larger components occupy more circuit board space, which contradicts the trend of miniaturization and high-density integration in modern electronic products; third, simply increasing the size has limited efficiency in improving current capacity and may lead to a decrease in thermal response speed.

[0004] Existing technologies attempt to increase current capacity by adjusting material formulations; for example: The invention patent with patent number 201210008641.2 discloses a method for manufacturing a power-type negative temperature coefficient thermistor. The patent proposes to form a material with high resistivity and high B value by adjusting the proportions of cobalt tetroxide, manganese dioxide, nickel oxide and aluminum oxide in the thermistor ceramic powder, i.e., the molar ratios are 30-60%, 40-70%, 10-30%, and 5-20%, respectively. Patent No. 202310006754.7 discloses a high-capacity power-type thermistor material and its preparation method. This patent uses Mn3O4, NiO, CuO, and Co3O4 as the matrix, and adds Al2O3, Nb2O5, Fe2O3, and SiC as additives. While this method improves the material properties to some extent, it fails to fundamentally resolve the contradiction between small volume and large current.

[0005] Patent No. 200910013606.8 discloses a high-capacity power thermistor and its fabrication method. This patent proposes a ring structure design, optimizing the ratio of outer diameter D to inner diameter d (d / D≥0.3) to increase current capacity by 20% and reduce temperature rise by 20-30℃. While this design improves performance by increasing heat dissipation area and optimizing current paths, it still doesn't solve the problem of significantly increasing chip current carrying capacity without increasing chip size. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a high-current power thermistor chip and its fabrication method; effectively solving the problem of significantly improving the chip's current carrying capacity without increasing product size. The technical solution is as follows: The thermal chip is made of composite material. By pre-determining the main material ratio and adding composite additives, and designing the structure as a multi-layer ring structure, the current carrying capacity is significantly improved without changing the product volume.

[0007] The composite material comprises a main material and composite additives; the weight percentages of each component in the main material are: manganese tetroxide (Mn3O4): 30–70%, zinc oxide (ZnO): 10–30%, copper oxide (CuO): 8–20%, and cobalt tetroxide (Co3O4): 1–10%; the properties and functions of each component are as follows: Manganese tetroxide (Mn3O4): As a main crystal phase forming agent, it provides the basic spinel structural framework and ensures the basic NTC properties of the material; Zinc oxide (ZnO): can effectively adjust the lattice constant, improve sintering activity, and reduce sintering temperature; Copper oxide (CuO): As a sintering aid, it promotes the densification process and increases the density of the material; Cobalt tetroxide (Co3O4) can effectively adjust the B value and resistivity of materials, and improve the stability of electrical properties.

[0008] The composite additive accounts for 1-10% of the weight of the main material; the weight percentage of each component in the composite additive is as follows: alumina (Al2O3): 10-25%, niobium pentoxide (Nb2O5): 10-20%, ferric oxide (Fe2O3): 20-35%, silicon carbide (SiC): 20-40%; the properties and functions of each component in the composite additive are as follows: Alumina (Al2O3): As a grain growth inhibitor, it refines grains, increases the number of grain boundaries, and optimizes electrical resistance characteristics; Niobium pentoxide (Nb₂O₅): As an acceptor dopant, it adjusts the grain boundary barrier height and improves nonlinear electrical properties; Ferric oxide (Fe2O3): As a donor dopant, it forms a compensating doping effect with Nb2O5, stabilizing the temperature resistance characteristics of the material and greatly reducing the sensitivity of the chip's electrical performance to changes in the external environment and aging under long-term operating conditions. Silicon carbide (SiC): As a highly thermally conductive phase, it acts as a heat conduction channel, effectively preventing thermal runaway, improving the thermal conductivity of the chip, accelerating heat dissipation, and reducing the operating temperature.

[0009] The composite additive, through the synergistic effect of doping of each component, simultaneously optimizes the electrical performance and thermal management capability of the thermistor chip.

[0010] The thermistor chip adopts a multi-layer ring structure, including an outer ring wall, an inner ring wall, and internal electrodes connecting the outer and inner ring walls. The internal structure of the thermistor chip contains at least three thermistor layers and multiple electrode layers disposed within the thermistor layers, forming a parallel conductive path. The current path enters from one electrode layer, passes through the multiple parallel internal electrode layers, and exits from the other electrode layer, effectively shunting the current. The ratio of its outer diameter D to its inner diameter d, d / D, is set to 0.20–0.25. The multi-layer ring structure increases the heat dissipation area, optimizes the current distribution path, and effectively reduces the overall resistance. At the same time, it effectively reduces the operating temperature, enabling the thermistor chip to withstand a larger current within the same volume.

[0011] The upper part of the multi-layer ring structure of the thermistor chip is set as the upper cover layer, the middle part of the multi-layer ring structure of the thermistor chip is set as the thermistor layer, and the lower part of the multi-layer ring structure of the thermistor chip is set as the lower cover layer. The upper cover layer, the thermistor layer and the lower cover layer form a stacked structure.

[0012] The aforementioned multi-layered ring structure forms a synergistic heat dissipation mechanism. Firstly, it enhances axial heat dissipation; the multi-layered ring structure itself provides the thermistor chip with a larger surface area in the axial direction (thickness), facilitating simultaneous heat dissipation in both the upward and downward directions. Secondly, it provides an excellent radial heat dissipation path; the multi-layered ring structure allows heat to dissipate simultaneously from both the inner and outer walls; the heat generated during the thermistor chip's operation can reach the surface radially, avoiding the "thermal bottleneck" effect of heat accumulation in the central region of a solid structure. Thirdly, it forms a three-dimensional heat dissipation network; the combination of the vertical axial structure and the horizontal radial structure constitutes a three-dimensional heat dissipation network, effectively improving the heat dissipation efficiency of the thermistor chip.

[0013] The electrode layer uses a silver-palladium alloy electrode with a silver-palladium weight ratio of 90:10 to 70:30 and an electrode thickness of 10 to 30 μm, which ensures both conductivity and improves the electrode's oxidation resistance.

[0014] The fabrication steps of the high-current power thermistor chip include: Casting: Green ceramic tapes are prepared using a casting process to ensure uniform thickness and consistent microstructure. Segmented sintering: Precisely controlled sintering curves prevent defects caused by excessively rapid heating and ensure that the material is fully densified; Atmosphere-controlled sintering: A controlled atmosphere is introduced during the critical sintering stage to regulate the valence state distribution of metal ions in the material.

[0015] The beneficial effects of this invention are as follows: It employs a multi-layered ring structure design, forming a synergistic heat dissipation mechanism. First, axial heat dissipation is enhanced, facilitating simultaneous heat dissipation in both upward and downward directions. Second, it effectively increases the radial heat dissipation path, allowing heat to dissipate simultaneously from both the inner and outer walls, avoiding the "thermal bottleneck" effect of heat accumulation in the central area of ​​a solid structure. Third, it constitutes a three-dimensional heat dissipation network structure, effectively solving the technical bottleneck of traditional power-type thermistors that rely on increasing volume to improve current capacity, possessing outstanding industrial application value, while also improving thermal stability and durability.

[0016] This invention achieves a significant increase in current carrying capacity without changing the product volume by pre-determining the main material ratio, adding composite additives, and designing the structure as a multi-layered ring structure. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the thermistor chip of the present invention; Figure 2 This is a schematic diagram of the exploded structure of the thermistor chip of the present invention; in the figure: 101. Top cover layer; 102. Thermistor layer; 103. Bottom cover layer; 104. Electrode layer. Detailed Implementation

[0018] Combined with appendix Figure 1 , Figure 2 The present invention is further described in detail with reference to the embodiments, so that the public can better understand the implementation method of the present invention. The specific implementation method of the present invention is as follows: The high-current power thermistor chip is made of composite material, which includes a main material and composite additives; the weight percentage of each component in the main material is as follows: manganese tetroxide (Mn3O4): 30-70%, zinc oxide (ZnO): 10-30%, copper oxide (CuO): 8-20%, and cobalt tetroxide (Co3O4): 1-10%. The properties and functions of each component are as follows: Manganese tetroxide (Mn3O4): as the main crystal phase forming agent, it provides the basic spinel structure framework and ensures the basic NTC characteristics of the material; Zinc oxide (ZnO): it can effectively adjust the lattice constant, improve sintering activity, and reduce sintering temperature; Copper oxide (CuO): as a sintering aid, it promotes the densification process and increases the material density; Cobalt tetroxide (Co3O4): it can effectively adjust the B value and resistivity of the material and improve the stability of electrical properties.

[0019] The composite additive accounts for 1-10% of the weight of the main material; the weight percentage of each component in the composite additive is as follows: alumina Al2O3: 10-25%, niobium pentoxide Nb2O5: 10-20%, ferric oxide Fe2O3: 20-35%, silicon carbide SiC: 20-40%; The method for preparing the composite doping of the thermal chip composite material, i.e., the thermal chip mixed powder, includes the following steps: Step 1: Compound formulation. According to the weight percentage of each component in the main material, namely, manganese tetroxide (Mn3O4): 30-70%, zinc oxide (ZnO): 10-30%, copper oxide (CuO): 8-20%, and cobalt tetroxide (Co3O4): 1-10%, first select two main material components and mix them to prepare a pre-formulated mixture; then add a composite additive accounting for 1-10% of the weight of the main material to the pre-formulated mixture, and then add the remaining two main material components to obtain the compound formulation. Step 2: Composite grinding. Add the composite ingredients to a ball mill jar pre-loaded with a certain number of zirconia balls, then add a preset weight of grinding media, and then perform ball milling. The ratio of material to grinding balls is 1:1 to 1.5, and the ratio of material to grinding media is 1:3 to 5. The ball milling media is a mixture of ethanol and water, with a water to ethanol ratio of 1 to 1.5:0.5 to 1. The ball milling speed is 20 to 30 Hz / min, and the ball milling time is 18 to 30 hours to obtain the thermal chip mixed powder.

[0020] The synergistic effects of the doping components in the composite additive are as follows: Alumina (Al₂O₃): acts as a grain growth inhibitor, refining grains, increasing the number of grain boundaries, and optimizing resistance characteristics; Niobium pentoxide (Nb₂O₅): acts as an acceptor dopant, adjusting the grain boundary barrier height and improving nonlinear electrical characteristics; Ferric oxide (Fe₂O₃): acts as a donor dopant, forming a compensating doping effect with Nb₂O₅, stabilizing the material's resistance-temperature characteristics; Silicon carbide (SiC): acts as a high thermal conductivity phase, improving the material's thermal conductivity, accelerating heat dissipation, and reducing the operating temperature. The electrical performance and thermal management capabilities of the thermistor chip are significantly improved.

[0021] The thermistor chip adopts a multi-layer ring structure, including an outer ring wall, an inner ring wall, and internal electrodes connecting the outer and inner ring walls. The internal structure of the thermistor chip contains at least three thermistor layers 102 and multiple electrode layers 104 disposed inside the thermistor layers 102, forming a parallel conductive path. The current path enters from one electrode layer 104, passes through the multiple parallel internal electrode layers 104, and exits from the other electrode layer 104, effectively shunting the current. The ratio d / D of the outer diameter D of the thermistor layer 102 to the inner diameter d of the thermistor layer 102 is set to 0.20~0.25. The multi-layer ring structure increases the heat dissipation area, optimizes the current distribution path, and effectively reduces the overall resistance. At the same time, it effectively reduces the operating temperature, enabling the thermistor chip to withstand a larger current in the same volume.

[0022] The upper part of the multi-layer ring structure of the thermistor chip is set as an upper cover layer 101, the middle part of the multi-layer ring structure of the thermistor chip is set as a thermistor layer 102, and the lower part of the multi-layer ring structure of the thermistor chip is set as a lower cover layer 103. The upper cover layer 101, the thermistor layer 102 and the lower cover layer 103 form a stacked structure.

[0023] The aforementioned multi-layered ring structure forms a synergistic heat dissipation mechanism. Firstly, it enhances axial heat dissipation; the multi-layered ring structure itself provides the thermistor chip with a larger surface area in the axial direction (thickness), facilitating simultaneous heat dissipation in both the upward and downward directions. Secondly, it provides an excellent radial heat dissipation path; the multi-layered ring structure allows heat to dissipate simultaneously from both the inner and outer walls; the heat generated during the thermistor chip's operation can reach the surface radially, avoiding the "thermal bottleneck" effect of heat accumulation in the central region of a solid structure. Thirdly, it forms a three-dimensional heat dissipation network; the combination of the vertical axial structure and the horizontal radial structure constitutes a three-dimensional heat dissipation network, effectively improving the heat dissipation efficiency of the thermistor chip.

[0024] The electrode layer 104 is a silver-palladium alloy electrode with a silver-palladium weight ratio of 90:10 to 70:30 and an electrode thickness of 10 to 30 μm, which ensures both conductivity and improves the electrode's oxidation resistance.

[0025] The method for fabricating the high-current power thermistor chip includes two processes: the preparation of thermistor chip mixed powder and the fabrication of thermistor chip. The thermistor chip fabrication steps include: Step 1: Casting and forming. The mixed powder obtained by the composite doping method is mixed with binder, plasticizer and solvent in a weight ratio of 100:15:5:40 to prepare casting slurry, and cast to form a green ceramic tape with a thickness of 0.3 to 0.8 mm. The adhesive is polyvinyl butyral, the plasticizer is dibutyl phthalate, and the solvent is a mixture of anhydrous ethanol and toluene in a volume ratio of 1:1. Step 2: Printing electrodes. Print the internal electrode pattern on the green ceramic tape using screen printing with a screen mesh count of 200-300. Step 3: Lamination and pressing. The printed raw ceramic sheets are laminated, including the upper cover layer 101, the heat-sensitive layer 102 in the middle and the lower cover layer 103, and isostatically pressed at a temperature of 60-80℃ and a pressure of 20-30MPa. Step 4: Sintering treatment. A segmented sintering process is adopted. First, the heating rate is 0.5-1℃ / min when the temperature rises from room temperature to 500℃. Second, the heating rate is 1-2℃ / min when the temperature rises from 500℃ to 800℃. Third, a nitrogen-oxygen mixture is introduced at 800-1100℃, with an oxygen volume fraction of 2-5%, to control the valence state and distribution of metal ions in the material. The temperature is held for 120-210 min and then cooled in the furnace. Step 5: Electrode layer 104 preparation. Silver-palladium alloy electrodes are printed on both ends of the sintered thermistor chip, and sintered at 800-850℃ for 20-30 minutes to obtain the thermistor chip. Example 1

[0026] 1. Raw material preparation: The weight percentage of each component of the main material is 55% Mn3O4, 20% ZnO, 15% CuO, and 5% Co3O4; the composite additive accounts for 5% of the weight of the main material, and the weight percentage of each component of the composite additive is 15% Al2O3, 15% Nb2O5, 30% Fe2O3, and 40% SiC; the raw material for the thermal chip is obtained. 2. Composite grinding: The thermistor chip raw material is added to a ball mill jar with zirconia balls, and then grinding media is added. The ball milling is then carried out. The ratio of material to grinding balls is 1:1, and the ratio of material to grinding media is 1:4. The ball milling media is a mixture of ethanol and water, with a water to ethanol ratio of 1:0.5. The ball milling speed is 25 Hz / min, and the ball milling time is 20 hours to obtain the thermistor chip mixed powder.

[0027] 3. Casting molding: The thermal chip powder is mixed with a mixed solvent prepared by polyvinyl butyral, dibutyl phthalate and ethanol-toluene in a weight ratio of 100:15:5:40 to prepare a casting slurry, which is then cast to form a green ceramic tape with a thickness of 0.5 mm. 4. Printing electrodes: Print silver-palladium alloy electrode patterns on the green ceramic tape. The ratio of silver to palladium alloy is 80:20, and the screen mesh is 250 mesh. 5. Lamination and pressing: Lay 8 layers of printed raw ceramic sheets, 2 upper cover layers, 4 heat-sensitive layers, and 2 lower cover layers, and press them into shape by isostatic pressing at 70℃ and 25MPa. 6. Sintering treatment: Segmented heating and continuous sintering are adopted. When heating from room temperature to 500℃, the heating rate is 0.8℃ / min. When heating from 500℃ to 800℃, the heating rate is 1.5℃ / min. When heating from 800℃ to 1080℃, the temperature is held for 180 minutes and then cooled with the furnace. 7. End electrode preparation: Electrode layers are printed on both ends of the sintered chip, and the chip is sintered at 820°C for 25 minutes to obtain a thermistor chip.

[0028] 8. Performance testing: The obtained thermistor chip has a diameter of 20mm and a thickness of 4mm. Actual test results show that the steady-state current capacity reaches 18A, the resistance is 0.55Ω, the B value is 3200K in the 25–85℃ range, and the temperature rise is only 42℃. Example 2

[0029] The basic process is the same as in Example 1, except that: 1. Raw material preparation: The weight percentages of the main material components are Mn3O4 70%, ZnO 12%, CuO 12%, and Co3O4 3%; the composite additive accounts for 3% of the weight of the main material, and the weight percentages of the composite additive components are Al2O3 25%, Nb2O5 20%, Fe2O3 35%, and SiC 20%. 2. Sintering treatment: At 800-1080℃, a nitrogen-oxygen mixture is introduced, with an oxygen volume fraction of 3%, to control the valence distribution of manganese ions in the material. 3. Performance Testing: The obtained thermistor chip has a diameter of 20mm and a thickness of 4mm. Actual test results show that the steady-state current capacity reaches 16A, the resistance is 0.62Ω, the B value is 2950K in the 25–85℃ range, and the temperature rise is 45℃; the standard deviation of the resistance is less than 2%. Example 3

[0030] The basic process is the same as in Example 1, except that: 1. Raw material preparation: The weight percentage of each component of the main material is 30% Mn3O4, 30% ZnO, 20% CuO, and 10% Co3O4; the composite additive accounts for 10% of the weight of the main material, and the weight percentage of each component of the composite additive is 10% Al2O3, 15% Nb2O5, 35% Fe2O3, and 40% SiC.

[0031] 2. Printing electrodes: Print silver-palladium alloy electrode patterns on the green ceramic tape, with a silver-palladium alloy ratio of 70:30. 3. Sintering treatment, with the peak sintering temperature increased to 1100℃; 4. Performance Testing: The obtained thermistor chip has a diameter of 20mm and a thickness of 4mm. Actual test results show that the steady-state current capacity reaches 20A, the resistance is 0.48Ω, the B value is 3500K in the 25–85℃ range, and the temperature rise is 38℃. This demonstrates high current capacity and low resistance, making it suitable for demanding applications.

[0032] The performance test results of the embodiments are compared with those of the prior art as follows: Performance parameters Example 1 Example 2 Example 3 Existing technology (solid structure chip) Dimensions (diameter × thickness, mm) 20×4 20×4 20×4 20×4 Steady-state current capacity (A) 18 16 20 12 Resistance value (Ω, 25℃) 0.55 0.62 0.48 0.70 B value (25 / 85℃, K) 3200 2950 3500 2800 Temperature rise (°C, 15A current) 42 45 38 65 Current boost ratio 50% 33% 67% ～ By comparing the performance data of the embodiments with those of the prior art, it can be directly concluded that: the present invention, through reasonable main material ratio and composite doping strategy of composite additives, and by designing the structure of the thermistor chip as a multi-layer ring structure, has successfully achieved a significant increase in the current capacity of the thermistor chip without changing the size of the thermistor chip. Compared with the traditional solid chip structure product, at a current of 15A, the temperature rise of the multi-layer ring structure of the present invention is reduced from 65°C to 38-45°C, which shows that the multi-layer ring structure of the present invention can better release and disperse thermal stress, greatly improve thermal stability, and increase the current capacity by 33%-67%, while maintaining good resistance characteristics and thermal stability. Moreover, the B value is increased by 25% in the range of 25-85°C, changes with temperature more quickly, is more suitable for high-precision temperature measurement or compensation, has stronger ability to suppress surge current, and enhances the durability and reliability of the product.

[0033] The technical solution of this invention overcomes the technical bottleneck of existing power-type NTC thermistors, provides key technical support for the miniaturization and high power density development of electronic devices, and has important industrial promotion and application value.

Claims

1. A high-current power thermistor chip, characterized in that: The high-current power type thermistor chip is made of composite material, which includes a main material and composite additives; the weight percentage and performance of each component in the main material are as follows: Manganese tetroxide (Mn3O4): 30-70%, as the main crystal phase forming agent, provides the basic spinel structure framework and ensures the basic NTC properties of the material; Zinc oxide (ZnO): 10-30%, can effectively adjust the lattice constant, improve sintering activity, and reduce sintering temperature; Copper oxide (CuO): 8-20%, used as a sintering aid to promote densification and increase material density; Cobalt tetroxide (Co3O4): 1-10%, can effectively adjust the B value and resistivity of materials and improve the stability of electrical properties; The composite additive accounts for 1-10% of the weight of the main material; the weight percentage of each component in the composite additive and the synergistic effect of doping are as follows: Alumina (Al2O3): 10-25%, as a grain growth inhibitor, refines grains, increases the number of grain boundaries, and optimizes electrical resistance characteristics; Niobium pentoxide (Nb₂O₅): 10-20%, used as acceptor doping to adjust the grain boundary barrier height and improve nonlinear electrical properties; Ferric oxide (Fe2O3): 20-35%, as a donor dopant, forms a compensating doping effect with Nb2O5, stabilizing the temperature resistance characteristics of the material, and greatly reducing the sensitivity of the chip's electrical performance to changes in the external environment and aging under long-term operating conditions. Silicon carbide (SiC): 20-40%, as a high thermal conductivity phase, acts as a heat conduction channel, effectively preventing thermal runaway, improving the thermal conductivity of the material, accelerating heat dissipation, and reducing the operating temperature.

2. The high-current power thermistor chip according to claim 1, characterized in that, The thermistor chip adopts a multi-layer ring structure, including an outer ring wall, an inner ring wall, and internal electrodes connecting the outer ring wall and the inner ring wall. The interior of the thermistor chip contains at least three thermistor layers (102) and multiple electrode layers (104) disposed inside the thermistor layers (102), forming a parallel conductive path. The current path enters from one electrode layer (104), passes through the multiple parallel internal electrode layers (104), and flows out from the other electrode layer (104), effectively shunting the current. The ratio d / D of the outer diameter D of the thermistor layer (102) to the inner diameter d of the thermistor layer (102) is set to 0.20~0.

25. The multi-layer ring structure increases the heat dissipation area, optimizes the current distribution path, and effectively reduces the overall resistance. At the same time, it effectively reduces the operating temperature, enabling the thermistor chip to withstand a larger current in the same volume.

3. The high-current power thermistor chip according to claim 1, characterized in that, The upper part of the multi-layer ring structure of the thermal chip is set as an upper cover layer (101), the middle part of the multi-layer ring structure of the thermal chip is set as a thermal layer (102), and the lower part of the multi-layer ring structure of the thermal chip is set as a lower cover layer (103). The upper cover layer (101), the thermal layer (102) and the lower cover layer (103) form a stacked structure. The aforementioned multi-layered ring structure forms a synergistic heat dissipation mechanism. First, axial heat dissipation is enhanced, as the multi-layered ring structure itself provides the thermistor chip with a larger surface area in the axial direction (thickness), which is beneficial for heat dissipation in both the upward and downward directions. Second, the radial heat dissipation path is excellent, as the multi-layered ring structure allows heat to be dissipated from both the inner and outer walls simultaneously. The heat generated by the thermistor chip during operation can reach the surface radially, avoiding the "thermal bottleneck" effect of heat accumulation in the central area of ​​a solid structure. Third, a three-dimensional heat dissipation network is formed, that is, the combination of the vertical axial structure and the horizontal radial structure constitutes a three-dimensional heat dissipation network, which effectively improves the heat dissipation efficiency of the thermistor chip.

4. The high-current power thermistor chip according to claim 1, characterized in that, The electrode layer (104) is made of silver-palladium alloy, with a silver-palladium weight ratio of 90:10 to 70:30 and an electrode thickness of 10 to 30 μm, which ensures both conductivity and improves the electrode's oxidation resistance.

5. The method for fabricating a high-current power thermistor chip according to any one of claims 1 to 4, characterized in that, The preparation method includes two processes: preparation of thermistor chip mixed powder and preparation of thermistor chip. The preparation of thermistor chip mixed powder is the composite doping of thermistor chip composite material, and its steps include: Step 1: Compound formulation. According to the weight percentage of each component in the main material, namely, manganese tetroxide (Mn3O4): 30-70%, zinc oxide (ZnO): 10-30%, copper oxide (CuO): 8-20%, and cobalt tetroxide (Co3O4): 1-10%, first select two main material components and mix them to prepare a pre-formulated mixture; then add a composite additive accounting for 1-10% of the weight of the main material to the pre-formulated mixture, and then add the remaining two main material components to obtain the compound formulation. Step 2: Composite grinding. The composite ingredients are added to a ball mill jar pre-loaded with a certain number of zirconia balls, and then a preset weight of grinding media is added. The ball milling is then carried out. The ratio of material to grinding balls is 1:1 to 1.5, and the ratio of material to grinding media is 1:3 to 5. The ball milling media is a mixture of ethanol and water, and the ratio of water to ethanol is 1 to 1.5:0.5 to 1. The ball milling speed is 20 to 30 Hz / min, and the ball milling time is 18 to 30 hours to obtain the thermal chip mixed powder. The method for fabricating the high-current power thermistor chip includes the following steps: Step 1: Casting and forming. The mixed powder obtained by the composite doping method is mixed with binder, plasticizer and solvent in a weight ratio of 100:15:5:40 to prepare casting slurry, and cast to form a green ceramic tape with a thickness of 0.3 to 0.8 mm. The adhesive is polyvinyl butyral, the plasticizer is dibutyl phthalate, and the solvent is a mixture of anhydrous ethanol and toluene in a volume ratio of 1:

1. Step 2: Printing electrodes. Print the internal electrode pattern on the green ceramic tape using screen printing with a screen mesh count of 200-300. Step 3: Lamination and pressing. The printed raw ceramic pieces are laminated, including the upper cover layer (101), the heat-sensitive layer (102) in the middle and the lower cover layer (103), and isostatically pressed at a temperature of 60-80℃ and a pressure of 20-30MPa. Step 4: Sintering treatment. A segmented sintering process is adopted. First, the heating rate is 0.5-1℃ / min when the temperature rises from room temperature to 500℃. Second, the heating rate is 1-2℃ / min when the temperature rises from 500℃ to 800℃. Third, a nitrogen-oxygen mixture is introduced at 800-1100℃, with an oxygen volume fraction of 2-5%, to control the valence state and distribution of metal ions in the material. The temperature is held for 120-210 min and then cooled in the furnace. Step 5: Electrode layer (104) preparation. Silver-palladium alloy electrodes are printed on both ends of the sintered thermistor chip, and sintered at 800-850℃ for 20-30 minutes to obtain the thermistor chip.

6. The method for fabricating a high-current power thermistor chip according to claim 4, characterized in that, Step 1: Raw material preparation. The weight percentages of the main material components are Mn3O4 55%, ZnO 20%, CuO 15%, and Co3O4 5%. The composite additive accounts for 5% of the weight of the main material, and the weight percentages of the composite additive components are Al2O3 15%, Nb2O5 15%, Fe2O3 30%, and SiC 40%. The thermistor chip raw material is thus obtained. Step 2: Composite grinding. The thermistor chip raw material is added to a ball mill jar with zirconia balls, and then grinding media is added. Then, ball milling is carried out. The ratio of material to grinding balls is 1:1, the ratio of material to grinding media is 1:4, the ball milling media is a mixture of ethanol and water, the ratio of water to ethanol is 1:0.5, the ball milling speed is 25 Hz / min, and the ball milling time is 20 hours to obtain the thermistor chip mixed powder. Step 3: Casting and molding. The thermal chip powder is mixed with a mixed solvent prepared by polyvinyl butyral, dibutyl phthalate and ethanol-toluene in a weight ratio of 100:15:5:40 to prepare a casting slurry, which is then cast to form a green ceramic tape with a thickness of 0.5 mm. Step 4: Printing electrodes. Print silver-palladium alloy electrode patterns on the green ceramic tape. The ratio of silver to palladium alloy is 80:20, and the screen mesh is 250 mesh. Step 5: Lamination and pressing. The 8 printed raw ceramic sheets are laminated, including 2 upper cover layers, 4 heat-sensitive layers, and 2 lower cover layers, and isostatically pressed at 70℃ and 25MPa. Step 6: Sintering treatment. Segmented heating and continuous sintering are adopted. When heating from room temperature to 500℃, the heating rate is 0.8℃ / min. When heating from 500 to 800℃, the heating rate is 1.5℃ / min. When heating from 800 to 1080℃, the temperature is held for 180 minutes and then cooled with the furnace. Step 7: End electrode preparation. Electrode layers are printed on both ends of the sintered chip, and the chip is sintered at 820°C for 25 minutes to obtain a thermistor chip. Step 8: Performance testing. The dimensions of the fabricated thermistor chip are: diameter 20mm and thickness 4mm. The actual test results show that the steady-state current capacity reaches 18A, the resistance value is 0.55Ω, the B value is 3200K in the 25~85℃ range, and the temperature rise is only 42℃.

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