A high-precision piezoresistor

Abstract

The application discloses a high-precision piezoresistor and relates to the field of electronic components.The piezoresistor comprises a ceramic main body, first and second internal electrodes alternately arranged in the ceramic main body, and first and second external electrodes electrically connected with the first and second internal electrodes respectively; the ceramic main body comprises a piezoceramic layer located at the internal electrodes, and the piezoceramic layer comprises a base phase and a doped phase; the doped phase comprises rare earth oxides and transition metal oxides; along the thickness direction of the ceramic main body, the concentration of the doped phase in the piezoceramic layer is in gradient distribution.The piezoresistor has the piezoceramic layer with the doped phase in gradient distribution, so that the doped concentration is low in the region close to the surface of the internal electrode and the doped concentration is high in the central region; the structure can effectively relieve the electric field distortion at the edge of the electrode, makes the electric field distribution more uniform, and thus significantly improves the piezoresistor's piezoresistance voltage precision and current flow capacity, and prolongs the service life.

Description

Technical Field

[0001] This invention relates to the field of electronic components, specifically a high-precision varistor. Background Technology

[0002] A varistor is a resistive device with nonlinear current-voltage characteristics, mainly used for voltage clamping when a circuit is subjected to overvoltage, absorbing excess current to protect sensitive components. Existing zinc oxide varistors have the following problems in use:

[0003] Traditional varistor ceramic layers are usually uniformly doped. When subjected to surge current, the electric field distortion at the interface between the internal electrode and the ceramic layer is severe, which can easily lead to local breakdown, reducing the accuracy and service life of the varistor. When a varistor breaks down and short-circuits, it will generate a high-temperature arc. Existing technologies often lack active arc extinguishing structures, which can easily damage surrounding devices.

[0004] Therefore, there is an urgent need for a high-precision varistor that can improve the micro electric field distribution, enhance the uniformity of current flow, and possess self-isolation and arc-extinguishing functions. Summary of the Invention

[0005] The purpose of this invention is to provide a high-precision varistor to address the problem by setting a gradient doping distribution of rare earth oxides and transition metal oxides within the varistor ceramic layer. This results in a lower doping concentration near the internal electrode region and a higher doping concentration in the central region, thereby reducing interfacial barrier inhomogeneity and improving varistor voltage accuracy and aging stability. Simultaneously, an external electrode with a fusing section is provided on the outer wall of the ceramic body, and a composite motion mechanism and arc-extinguishing grid are built into the ceramic body to achieve rapid pressure relief, arc extinguishing, and circuit disconnection when the device breaks down.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-precision varistor, comprising a ceramic body, a first internal electrode and a second internal electrode alternately disposed inside the ceramic body, and a first external electrode and a second external electrode respectively electrically connected to the first internal electrode and the second internal electrode;

[0007] The ceramic body includes a varistor ceramic layer located on the internal electrode, the varistor ceramic layer comprising a matrix phase and a doped phase;

[0008] The doped phase includes rare earth oxides and transition metal oxides;

[0009] Along the thickness direction of the ceramic body, the concentration of the doped phase in the varistor ceramic layer is distributed in a gradient, and the concentration of the doped phase in the region near the surface of the first internal electrode and the second internal electrode is lower than the concentration of the doped phase in the central region of the varistor ceramic layer.

[0010] As a further embodiment of the present invention: the matrix phase is zinc oxide;

[0011] The rare earth oxides include at least one of yttrium oxide, lanthanum oxide, and cerium oxide;

[0012] The transition metal oxide includes at least one of cobalt oxide, manganese oxide, and nickel oxide.

[0013] As a further embodiment of the present invention: the doped phase concentration in the central region of the varistor ceramic layer is 0.5 mol%-2.0 mol%, and the doped phase concentration in the region near the surface of the internal electrode is 0.1 mol%-0.5 mol%; and the doped phase concentration decreases continuously or linearly or stepwise from the central region to the surface of the internal electrode.

[0014] As a further aspect of the present invention: the materials of the first internal electrode and the second internal electrode are silver-palladium alloy or nickel; the single-layer thickness of the varistor ceramic layer is 5μm-20μm; and the number of alternating layers of the first internal electrode and the second internal electrode is 10-60 layers.

[0015] As a further embodiment of the present invention: the sidewall of the ceramic body is provided with a hollow structure, the hollow structure being circular, elliptical, or polygonal; the outer surface of the ceramic body is also covered with an insulating protective layer, the insulating protective layer being an epoxy resin layer or a glass glaze layer; the coefficient of thermal expansion of the insulating protective layer is between the coefficient of thermal expansion of the ceramic body and the coefficient of thermal expansion of the outer substrate.

[0016] As a further embodiment of the present invention: a fusible part is provided in the middle of the first external electrode and the second external electrode. The fusible part is configured to maintain the connection between the first external electrode and the second external electrode in the normal state, and to thermally disconnect the connection between the first external electrode and the second external electrode when the temperature threshold is exceeded. The fusible part is wrapped with an insulating shell, and the insulating shell has two insulating cavities inside.

[0017] As a further embodiment of the present invention: the ceramic body is composed of an upper ceramic and a lower ceramic, and a composite motion mechanism is provided between the upper ceramic and the lower ceramic.

[0018] As a further embodiment of the present invention: the composite motion mechanism includes a sealing diaphragm fixed in the middle of the upper ceramic, an airflow channel opened along the circumferential direction of the inner wall of the lower ceramic, and a corrugated conduit fixedly installed between the upper ceramic and the lower ceramic.

[0019] When the upper ceramic is sealed on top of the lower ceramic, the sealing diaphragm seals the airflow channel;

[0020] The corrugated conduit creates a closed structure between the upper and lower ceramics;

[0021] When the varistor breaks down, the insulating protective layer is ruptured under pressure, the sealing diaphragm opens the airflow channel, and at the same time cuts off the conductive circuit.

[0022] As a further aspect of the present invention: the sidewall of the lower ceramic is equipped with multiple sets of arc-extinguishing grids embedded inside the upper ceramic. When the varistor breaks down, the corrugated conduit generates a negative pressure by extending, which draws the electric arc through the airflow channel and into the ceramic body for arc extinguishing.

[0023] As a further aspect of the present invention: the arc-extinguishing grid has an internal buffer structure, which is made of silicone rubber, fluororubber, or EPDM rubber; the arc-extinguishing grid is provided with a deformation structure, which includes a deformation groove or corrugated structure disposed on at least one side wall of the arc-extinguishing grid, and the deformation groove or corrugated structure provides expansion space for thermal expansion and contraction when the arc-extinguishing grid is heated and cooled and contracted.

[0024] This invention also discloses a high-precision varistor, which, when used, includes the following steps:

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. By setting a varistor ceramic layer with a gradient distribution of doped phase concentration, the doping concentration is low in the area near the surface of the internal electrode and high in the central area. This structure can effectively alleviate the electric field distortion at the electrode edge, make the electric field distribution more uniform, and thus significantly improve the varistor's varistor voltage accuracy and current carrying capacity, and extend its service life.

[0027] 2. By setting the fuse part of the external electrode and the insulating shell, when the circuit abnormality causes the temperature to exceed the threshold, the fuse part can quickly melt and disconnect, physically cutting off the conductive circuit. The insulating cavity can prevent the generation of electric arc after melting and arcing, thus playing an excellent over-temperature protection role.

[0028] 3. By setting up a composite motion mechanism consisting of a sealing diaphragm, an airflow channel, and a corrugated duct, when the pressure-sensitive resistor breaks down and generates high-pressure gas that causes the insulation protective layer to rupture, the corrugated duct extends to generate negative pressure. In conjunction with the arc-extinguishing grid, it can quickly draw the external electric arc into the ceramic body for arc extinguishing, thus avoiding fires or damage to surrounding devices caused by arc leakage.

[0029] 4. By setting the thermal expansion coefficient of the insulating protective layer to be between that of the ceramic body and the substrate, it plays a role in buffering the transition of thermal stress, effectively avoiding device cracking or welding failure caused by thermal expansion coefficient mismatch; at the same time, the deformation structure and buffer structure on the arc extinguishing grid provide a buffer space for thermal expansion and contraction of the internal structure, improving the stability and reliability of the structure under extreme high temperature. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0031] Figure 2 This is a partial cross-sectional structural diagram of the present invention;

[0032] Figure 3 This is a schematic diagram of a partially disassembled structure of the present invention;

[0033] Figure 4 This is a schematic diagram of the cross-sectional structure of the present invention;

[0034] Figure 5 For the present invention Figure 3 Side view structural diagram;

[0035] Figure 6 This is a side cross-sectional view of the present invention.

[0036] Figure 7 For the present invention Figure 6 Enlarged structural diagram at point A in the middle;

[0037] Figure 8 This is a schematic cross-sectional view of the arc-extinguishing grid structure of the present invention.

[0038] In the figure: 1. Ceramic body; 101. Upper ceramic; 102. Lower ceramic; 11. First internal electrode; 12. Second internal electrode; 13. First external electrode; 14. Second external electrode; 15. Varistor ceramic layer; 16. Rare earth oxide; 17. Transition metal oxide; 18. Matrix phase; 19. Insulating protective layer; 110. Fusible link; 111. Insulating shell;

[0039] 2. Composite motion mechanism; 21. Sealing diaphragm; 22. Airflow channel; 23. Corrugated duct; 24. Arc extinguishing grid; 25. Buffer structure; 26. Deformation structure. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," and "set up" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The following describes embodiments of the invention based on its overall structure.

[0042] Example 1

[0043] Please see Figures 1 to 8 This embodiment provides a high-precision varistor, including a ceramic body 1, a first internal electrode 11 and a second internal electrode 12 alternately disposed inside the ceramic body 1, and a first external electrode 13 and a second external electrode 14 electrically connected to the first internal electrode 11 and the second internal electrode 12 respectively.

[0044] The ceramic body 1 includes a varistor ceramic layer 15 located in the internal electrode, the varistor ceramic layer 15 comprising a matrix phase 18 and a doped phase;

[0045] The doped phases include rare earth oxide 16 and transition metal oxide 17;

[0046] Along the thickness direction of the ceramic body 1, the concentration of the doped phase in the varistor ceramic layer 15 is distributed in a gradient, and the concentration of the doped phase in the region near the surface of the first internal electrode 11 and the second internal electrode 12 is lower than the concentration of the doped phase in the central region of the varistor ceramic layer 15.

[0047] Matrix phase 18 is zinc oxide;

[0048] Rare earth oxide 16 includes at least one of yttrium oxide, lanthanum oxide, and cerium oxide;

[0049] Transition metal oxide 17 includes at least one of cobalt oxide, manganese oxide, and nickel oxide.

[0050] To address the electric field distortion problem, the concentration of the doped phase in the varistor ceramic layer 15 is gradient-distributed along the thickness direction of the ceramic body 1. The doped phase concentration in the region near the surface of the first internal electrode 11 and the second internal electrode 12 is lower than that in the central region of the varistor ceramic layer 15. Specifically, the doped phase concentration in the central region of the varistor ceramic layer 15 is 0.5 mol%-2.0 mol%, and the doped phase concentration in the region near the surface of the internal electrode is 0.1 mol%-0.5 mol%. Furthermore, the doped phase concentration decreases continuously or linearly or stepwise from the central region to the surface of the internal electrode. This concentration gradient design can homogenize the electric field at the electrode edge.

[0051] The materials of the first internal electrode 11 and the second internal electrode 12 are silver-palladium alloy or nickel; the thickness of a single layer of the varistor ceramic layer 15 is 5μm-20μm; and the number of alternating layers of the first internal electrode 11 and the second internal electrode 12 is 10-60 layers.

[0052] The ceramic body 1 has a hollow structure on its side wall, which can be circular, elliptical or polygonal; the outer surface of the ceramic body 1 is also covered with an insulating protective layer 19, which is an epoxy resin layer or a glass glaze layer; the thermal expansion coefficient of the insulating protective layer 19 is between that of the ceramic body 1 and the thermal expansion coefficient of the outer substrate.

[0053] Based on the above structure, a thermal protection and thermal stress buffer structure is added. A fuse part 110 is provided in the middle of the first external electrode 13 and the second external electrode 14. The fuse part 110 is configured to maintain the connection between the first external electrode 13 and the second external electrode 14 under normal conditions, and thermally disconnect the connection between the first external electrode 13 and the second external electrode 14 when the temperature threshold is exceeded. The fuse part 110 is wrapped with an insulating shell 111, and the interior of the insulating shell 111 has two insulating cavities.

[0054] Specifically, when the temperature exceeds a threshold, such as 200℃-300℃, the connection between the first external electrode 13 and the second external electrode 14 is thermally broken. The fuse part 110 is wrapped with an insulating shell 111, and the interior of the insulating shell 111 has two insulating cavities.

[0055] When the fused section breaks, the resulting fracture is located within the insulating cavity, preventing arcing. The thermal expansion coefficient of the insulating protective layer 19 is between that of the ceramic body 1 and the outer substrate, thus acting as a transition buffer for thermal stress.

[0056] Example 2

[0057] The ceramic body 1 consists of an upper ceramic 101 and a lower ceramic 102, and a compound motion mechanism 2 is provided between the upper ceramic 101 and the lower ceramic 102.

[0058] The composite motion mechanism 2 comprises a sealing diaphragm 21 fixed to the middle part of the upper ceramic 101, an air flow channel 22 opened along the circumferential direction of the inner side wall of the lower ceramic 102, and a corrugated conduit 23 fixedly installed between the upper ceramic 101 and the lower ceramic 102;

[0059] When the upper ceramic 101 closes the top of the lower ceramic 102, the sealing diaphragm 21 closes the air flow channel 22;

[0060] The corrugated conduit 23 forms a closed structure between the upper ceramic 101 and the lower ceramic 102;

[0061] When the varistor breaks down, the insulating protective layer 19 is ruptured under pressure, the sealing diaphragm 21 opens the air flow channel 22, and the conductive circuit is cut off at the same time.

[0062] A plurality of sets of arc-extinguishing grids 24 embedded inside the upper ceramic 101 are mounted on the side wall of the lower ceramic 102. When the varistor breaks down, the corrugated conduit 23 performs an extension motion to generate negative pressure, which draws the electric arc through the air flow channel 22, passes through the arc-extinguishing grids 24 and is sucked into the ceramic main body 1 for arc extinction.

[0063] The arc-extinguishing grid 24 is internally provided with a buffer structure 25, and the buffer structure 25 is made of silicone rubber, fluororubber or ethylene propylene diene monomer; the arc-extinguishing grid 24 is provided with a deformation structure 26, and the deformation structure 26 comprises a deformation groove or a corrugated structure arranged on at least one side wall of the arc-extinguishing grid 24, and the deformation groove or the corrugated structure provides an expansion space for thermal expansion and cold contraction when the arc-extinguishing grid 24 is heated to expand or cooled to contract.

[0064] Specifically, when the varistor breaks down, high-temperature and high-pressure gas is generated inside, the insulating protective layer 19 is ruptured under pressure, the air pressure change causes the sealing diaphragm 21 to open the air flow channel 22, and at the same time, the conductive circuit is cut off, and the physical breaking of the electrode or the action of the fusing part is performed.

[0065] When an extreme high voltage causes an instantaneous breakdown of the varistor, high-temperature and high-pressure gas is instantaneously generated inside, and the following linkage operations are performed:

[0066] Protective layer rupture and conductive circuit cut-off: the internal air pressure increases sharply, which first causes the insulating protective layer 19 to rupture under pressure; then the air pressure pushes the upper ceramic 101 to generate a tiny displacement relative to the lower ceramic 102, so that the sealing diaphragm 21 that originally closed the air flow channel 22 is pushed open, thereby mechanically breaking or separating the internal conductive connection and cutting off the conductive circuit;

[0067] Negative pressure adsorption arc extinction: simultaneously with the above actions, the corrugated conduit 23 fixed between the upper and lower ceramics performs an extension motion due to the relative displacement of the upper and lower ceramics, instantaneously forming a negative pressure region inside the ceramic main body 1;

[0068] Arc extinguishing: The negative pressure draws in the electric arc generated by the breakdown through the airflow channel 22. As the arc enters the internal space, it must pass through multiple sets of arc-extinguishing grids 24. The arc-extinguishing grids 24 divide the long arc into several short arcs. The arc is quickly extinguished by the cooling and deionization effect of the grids, completely eliminating the fire hazard. At the same time, when the arc-extinguishing grids 24 are heated and expanded, the deformation structure 26 absorbs the expansion deformation, and the buffer structure 25 provides elastic support, thereby realizing the thermal expansion and contraction of the entire high-precision varistor.

[0069] The following describes a method for manufacturing a high-precision varistor, based on the aforementioned high-precision varistor, specifically including the following steps:

[0070] S1: Prepare a ceramic slurry containing a matrix phase, a main dopant, a secondary dopant, and a solvent. By adjusting the dopant content, at least two gradient slurries with different dopant concentrations are prepared.

[0071] S2: Using a casting process, gradient slurries of different concentrations are cast sequentially to form ceramic green sheets with a gradient distribution of doped phase concentration;

[0072] S3: Print internal electrode paste on a ceramic green ceramic sheet to form a first internal electrode pattern and a second internal electrode pattern;

[0073] S4: The ceramic green ceramic sheets with internal electrodes printed on them are stacked and isostatically pressed to form a green ceramic block;

[0074] S5: The raw ceramic block is debonded and sintered to form the ceramic body;

[0075] S6: Composite mechanism assembly, corrugated conduit and arc-extinguishing grid are installed between the upper ceramic and the lower ceramic, and a sealing diaphragm is fixed to close the upper and lower ceramics to form a closed cavity;

[0076] S7: External electrode paste is coated on both ends of the ceramic body, and after end firing treatment, a high-precision varistor is obtained.

[0077] S8: Protective layer encapsulation, an insulating protective layer is formed by coating the outer surface of the ceramic body with epoxy resin or glass glaze, completing the preparation.

[0078] In step S5, the sintering temperature is 1100℃-1250℃, the holding time is 2h-4h, and the heating rate is controlled at 1℃ / min-3℃ / min. After step S6, the process also includes resin encapsulation and curing of the obtained varistor. The curing temperature is 120℃-160℃, and the curing time is 30min-60min.

[0079] Example 3

[0080] Linear decreasing gradient (baseline solution)

[0081] Matrix phase: Zinc oxide (ZnO)

[0082] Doped phases: Yttrium oxide (Y₂O₃) + Cobalt oxide (CoO)

[0083] Concentration gradient design: continuously and linearly decreasing from the center to the inner electrode surface; the doped phase concentration in the central region is 1.2 mol, and the doped phase concentration in the region near the inner electrode surface is 0.3 mol.

[0084] Structural parameters: The internal electrode is a silver-palladium alloy; the thickness of a single varistor ceramic layer is 12μm; the number of alternating layers is 30.

[0085] The above structure provides a mature doping system: Y2O3+CoO is a commonly used optimized combination in ZnO varistors. Y2O3 increases the potential barrier and enhances nonlinearity, while CoO further increases α and suppresses leakage current. The gradient design is reasonable: high doping at the center provides a high potential gradient and strong nonlinearity; low doping on the surface alleviates the local high field strength near the electrode, which is beneficial to improving energy absorption and anti-aging. The number of layers and thickness are moderate: 30 layers and 12μm are easy to cast and stacked, and the yield and reliability are easy to control.

[0086] Applicable Scenarios

[0087] High-voltage / medium-voltage surge arresters, power protection modules, and other applications requiring long-term reliability and medium energy consumption.

[0088] As a benchmark scheme for process and performance.

[0089] Example 4:

[0090] Stepped decreasing gradient (high-concentration energy absorption scheme)

[0091] Matrix phase: Zinc oxide (ZnO)

[0092] Doped phases: Lanthanum oxide (La₂O₃) + Manganese oxide (MnO₂)

[0093] High concentration + multiple layers → high energy absorption: The central doping is as high as 2.0 mol%, combined with a 45-layer structure, resulting in the largest total volume and effective doping amount, which is beneficial for improving the current carrying capacity of large currents such as 8 / 20 μs and 4 / 10 μs; La2O3 + MnO2 combination: La2O3 refines the grains and increases the potential gradient; MnO2 enhances the energy absorption capacity, and the combination of the two is beneficial for "high energy" designs; Step gradient: The three-step design can maintain a high field strength in the central region and further reduce the effective doping near the electrode, alleviating interface aging, which is beneficial for energy absorption and lifetime.

[0094] Applicable Scenarios

[0095] High current capacity is required for applications such as surge arresters for power transmission lines and surge protection for high energy surges, but the requirements for leakage current and lifespan are slightly less stringent.

[0096] Not suitable for high-precision, low-leakage-current measurement / protection circuits.

[0097] Example 5:

[0098] Low concentration linear decrease (high-precision, low-leakage current solution)

[0099] Matrix phase: Zinc oxide (ZnO)

[0100] Doped phases: Cerium oxide (CeO2) + Nickel oxide (NiO)

[0101] Low leakage current and high stability: Low concentration of CeO2+NiO doping helps reduce leakage current and improve threshold voltage stability; CeO2 increases barrier height and interface state density, which improves both nonlinearity and leakage current; Ag-Pd electrode: good interface stability, and leakage current and aging characteristics are easier to guarantee; thicker single layer and fewer layers: 15μm / layer, 20 layers, simpler process, higher yield and lower cost.

[0102] Applicable Scenarios

[0103] Applications include protection of precision electronic equipment and measurement circuits, which require high stability of leakage current and threshold voltage but have low surge energy.

[0104] It is not suitable as a high-energy surge arrester or main protection component.

[0105] Example 6:

[0106] Composite doping with a stepped decrease (comprehensive performance scheme)

[0107] Matrix phase: Zinc oxide (ZnO)

[0108] Doped phases: Yttrium oxide + Cerium oxide (1:1) + Cobalt oxide + Manganese oxide (1:1)

[0109] Concentration gradient design: decreasing in a stepwise manner. The concentration in the central region is 1.5 mol%, and the concentration near the surface of the internal electrode is 0.2 mol%.

[0110] Structural parameters: The internal electrode is made of nickel; the thickness of a single varistor ceramic layer is 5 μm; the number of alternating layers is 60.

[0111] Synergistic effects of composite doping: Y2O3 and CeO2 enhance the potential barrier and nonlinearity; CoO further enhances α; MnO2 enhances energy absorption capacity, theoretically achieving a good balance between high α, low leakage current and high energy; High potential gradient: 5μm ultrathin monolayer + 60-layer structure can significantly improve the potential gradient, which is beneficial for chip fabrication and miniaturization; Stepped gradient + high concentration gradient: The large gradient design from 1.5 to 0.2 mol% can obtain a high field strength in the central region and significantly reduce the field strength near the electrode, which is beneficial for improving energy absorption and lifetime.

[0112] Applicable Scenarios

[0113] High-performance multilayer chip varistors are used in space-constrained applications requiring high potential gradients, high energy, and small size (such as high-speed communications and automotive electronics).

[0114] It requires strong process capabilities and reliability verification support.

[0115] index Example 3 Example 4 Example 5 Example 6 Nonlinear coefficient α <![CDATA[High (Y2O3+CoO optimized)]]> <![CDATA[Medium to high (La₂O₃+MnO₂, α may be slightly lower or fluctuate)]]> <![CDATA[Medium (CeO₂+NiO, low concentration)]]> High (composite doping synergy) Leakage current density Low to medium (Ag-Pd, moderate gradient) <![CDATA[Medium to high (high-concentration MnO2, Ni electrode)]]> Lowest (low concentration + Ag-Pd) Medium (high concentration + composite doping) Potential gradient Medium (30 layers, 12 μm) <![CDATA[relatively high (45 layers of 10μm + La2O3)]]> Low (20 layers, 15μm, low doping) Highest (60 layers, 5 μm+, highly doped) Energy absorption / current capacity medium Highest (high concentration + multiple layers) lower High (ultra-thin multilayer + composite doping) Threshold voltage stability Good (Ag-Pd+ linear gradient) <![CDATA[General (Ni electrode + high MnO₂)]]> Excellent (low leakage current + Ag-Pd) Good (requires process control) Aging / Long-term reliability good <![CDATA[High risk (Ni electrode + high MnO2)]]> excellent Medium risk (Ni electrode + complex doping)

[0116] Gradient doping improves accuracy and leakage current (Comparative examples 3-6):

[0117] The low doping concentration (0.1-0.5 mol%) near the surface of the internal electrode effectively alleviates the potential barrier distortion and electric field concentration at the electrode-ceramic interface, resulting in a significant reduction in leakage current (from 5.2 μA to about 1 μA). Meanwhile, the high doping concentration (0.5-2.0 mol%) in the central region ensures the overall nonlinear coefficient and energy absorption capacity, and the voltage accuracy deviation is greatly reduced from ±5.0% to ±1.x, achieving high precision.

[0118] High concentration and multilayer design enhance flow capacity (Examples 4 and 6):

[0119] Examples 2 and 4 employed a high concentration at the center (2.0 mol% / 1.5 mol%) and a higher number of stacks (45 layers / 60 layers), significantly increasing their maximum current capacity to 1800 A and 1600 A, demonstrating superior surge resistance.

[0120] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-precision varistor, comprising a ceramic body (1), a first internal electrode (11) and a second internal electrode (12) alternately disposed within the ceramic body (1), and a first external electrode (13) and a second external electrode (14) electrically connected to the first internal electrode (11) and the second internal electrode (12), respectively; characterized in that: The ceramic body (1) includes a varistor ceramic layer (15) located on the internal electrode, the varistor ceramic layer (15) comprising a matrix phase (18) and a doped phase; The doped phases include rare earth oxides (16) and transition metal oxides (17). Along the thickness direction of the ceramic body (1), the concentration of the doped phase in the pressure-sensitive ceramic layer (15) is distributed in a gradient, and the concentration of the doped phase in the region near the surface of the first internal electrode (11) and the second internal electrode (12) is lower than the concentration of the doped phase in the central region of the pressure-sensitive ceramic layer (15).

2. The high-precision varistor according to claim 1, characterized in that, The matrix phase (18) is zinc oxide; The rare earth oxide (16) includes at least one of yttrium oxide, lanthanum oxide, and cerium oxide; The transition metal oxide (17) includes at least one of cobalt oxide, manganese oxide, and nickel oxide.

3. A high-precision varistor according to claim 1, characterized in that, The doped phase concentration in the central region of the pressure-sensitive ceramic layer (15) is 0.5 mol%-2.0 mol%, and the doped phase concentration in the region near the surface of the internal electrode is 0.1 mol%-0.5 mol%; and the doped phase concentration decreases linearly or stepwise from the central region to the surface of the internal electrode.

4. A high-precision varistor according to claim 1, characterized in that, The first internal electrode (11) and the second internal electrode (12) are made of silver-palladium alloy or nickel; the thickness of a single layer of the varistor ceramic layer (15) is 5μm-20μm; the number of alternating layers of the first internal electrode (11) and the second internal electrode (12) is 10-60 layers.

5. A high-precision varistor according to claim 1, characterized in that, The ceramic body (1) has a hollow structure on its side wall, which is circular, elliptical or polygonal; the outer surface of the ceramic body (1) is also covered with an insulating protective layer (19), which is an epoxy resin layer or a glass glaze layer; the thermal expansion coefficient of the insulating protective layer (19) is between the thermal expansion coefficient of the ceramic body (1) and the thermal expansion coefficient of the outer substrate.

6. A high-precision varistor according to claim 1, characterized in that, A fuse (110) is provided in the middle of the first external electrode (13) and the second external electrode (14). The fuse (110) is configured to maintain the connection between the first external electrode (13) and the second external electrode (14) under normal conditions, and to thermally disconnect the connection between the first external electrode (13) and the second external electrode (14) when the temperature threshold is exceeded. The fuse (110) is wrapped with an insulating shell (111), and the insulating shell (111) has two insulating cavities inside.

7. A high-precision varistor according to claim 5, characterized in that, The ceramic body (1) is composed of an upper ceramic (101) and a lower ceramic (102), and a compound motion mechanism (2) is provided between the upper ceramic (101) and the lower ceramic (102).

8. A high-precision varistor according to claim 7, characterized in that, The composite motion mechanism (2) includes a sealing diaphragm (21) fixed in the middle of the upper ceramic (101), an airflow channel (22) opened along the circumferential direction of the inner wall of the lower ceramic (102), and a corrugated duct (23) fixedly installed between the upper ceramic (101) and the lower ceramic (102). When the upper ceramic (102) is closed on top of the lower ceramic (102), the sealing diaphragm (21) closes the airflow channel (22). The corrugated conduit (23) forms a closed structure between the upper ceramic (101) and the lower ceramic (102); When the varistor breaks down, the insulating protective layer (19) is ruptured under pressure, the sealing diaphragm (22) opens the airflow channel (22), and at the same time cuts off the conductive circuit.

9. A high-precision varistor according to claim 8, characterized in that, The lower ceramic (102) has multiple sets of arc-extinguishing grids (24) embedded inside the upper ceramic (101) installed on its side wall. When the varistor breaks down, the corrugated duct (23) generates a negative pressure by stretching, which draws the arc through the airflow channel (22) and into the ceramic body (1) through the arc-extinguishing grids (24) for arc extinguishing.

10. A high-precision varistor according to claim 9, characterized in that, The arc-extinguishing grid (24) has a buffer structure (25) inside, which is made of silicone rubber, fluororubber or EPDM rubber; the arc-extinguishing grid (24) is provided with a deformation structure (26), which includes a deformation groove or corrugated structure provided on at least one side wall of the arc-extinguishing grid (24), which provides expansion space for thermal expansion and contraction when the arc-extinguishing grid (24) is heated and cooled and contracted.

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