Chip-type pressure-sensitive resistor, its manufacturing method, and applications

Abstract

This application belongs to the field of resistor technology, and particularly relates to a chip-type piezoresistor, its manufacturing method, and applications. The manufacturing method of the chip-type piezoresistor includes preparing an additive containing Bi2O3, Sb2O3, MnO2, Cr2O3, Co2O3, H3BO3, Zn3(PO4)2·4H2O, Nb2O5, AgNO3, and Al(NO3)3·9H2O with a molar ratio of (1.0~2.0):(1.0~2.0):(0.4~0.8):(0.4~0.8):(0.4~0.8):(1.0~2.0):(0.8~1.6):(0.2~0.8):(0.01~0.05):(0.02~0.08), and mixing it with the main crystal phase material, solvent, and auxiliary agent to manufacture a chip-type piezoresistor. By reducing the sintering temperature and adjusting the mixing ratio of the additive and the main crystal phase material, resistors with low, medium, and high potential gradients can be manufactured respectively, which is simple and efficient.

Description

Technical Field

[0001] This application claims the priority of a Chinese patent application filed with the China National Intellectual Property Administration on July 1, 2022, with the application number 202210767580.1, and all of its contents are incorporated herein by reference. This application belongs to the technical field of resistors, and particularly relates to a chip-type pressure-sensitive resistor, a manufacturing method thereof, and applications.

Background Art

[0002] Modern electronic finished devices tend to be miniaturized, thinner, and multifunctional. The integration density of their internal circuits and the mounting density of electronic components have been greatly improved. As the most basic part of electronic devices, the need for miniaturization of electronic components is becoming increasingly strong. The conventional plug-in type ZnO pressure-sensitive resistor has defects such as large size (the smallest in the market is φ5mm) and small flux, and its application is greatly limited. With the improvement of materials and process technologies, chip-type pressure-sensitive resistors have attracted more and more attention from the market due to their miniaturization and excellent surge voltage protection ability. They have begun to replace conventional plug-in pressure-sensitive resistors in some application fields, and are more widely applied especially in fields such as security, communication power, network communication, and LED lighting. The magnitude of the peak current parameter of a chip-type pressure-sensitive resistor determines the strength of the product's surge resistance ability. The larger the parameter, the stronger the product's surge resistance ability, indicating that the protection effect is excellent. This parameter is mainly related to ceramic materials, product size (structural design), and production process. With the need for the miniaturization trend, the flux density of ceramic materials can be greatly improved, and the surge protection performance of products can be further improved to meet market needs.

[0003] The current chip-type piezoresistor is generally divided into DC applications (low voltage 5 - 30V, medium voltage 30V - 85V) and AC applications (high voltage 110V - 320V) according to different application fields. Based on different voltage ranges, it is necessary to adopt different types of formulations in the manufacturing technology. Since multiple types of formulations are operated on the production line, for both powder manufacturing and slurry manufacturing, it is necessary to strictly clean the jigs and equipment, or prepare and classify multiple pieces of equipment for use to prevent cross-contamination between multiple materials. Such operating rules lead to problems such as low production efficiency, complex processes, and cumbersome on-site management. Currently, the chip-type piezoresistors produced on a large scale mainly adopt ZnO - Bi-based ceramic materials that match Pd10 / Ag90 or Pd20 / Ag80 internal electrode slurries, and their sintering temperatures all need to be at temperatures above 900°C. This sintering temperature is still too high for pure silver slurries and cannot be fully and effectively adapted. For example, the internal electrodes need to be printed to a thickness of 10μm or more, and there is a problem that the sintering temperature adjustment space is narrow to prevent burning of the lead-out ends and internal electrodes. Therefore, when trying to fully adapt to pure silver internal electrode slurries, it is necessary to further lower the sintering temperature of the ceramic material system to below 900°C.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The object of this application is to provide a chip-type piezoresistor, its manufacturing method, and an electronic device, and to solve to a certain extent the problems that chip-type piezoresistors in different voltage ranges need to be manufactured with different types of formulations, resulting in low production efficiency and high sintering temperature.

Means for Solving the Problems

[0005] To achieve the above object, this application adopts the following technical solutions.

[0006] According to a first aspect, this application provides a manufacturing method of a chip-type piezoresistor, The step of preparing an additive containing Bi2O3, Sb2O3, MnO2, Cr2O3, Co2O3, H3BO3, Zn3(PO4)2·4H2O, Nb2O5, AgNO3 and Al(NO3)3·9H2O with a molar ratio of (1.0~2.0):(1.0~2.0):(0.4~0.8):(0.4~0.8):(0.4~0.8):(1.0~2.0):(0.8~1.6):(0.2~0.8):(0.01~0.05):(0.02~0.08); The step of mixing and grinding the additive with a main crystal phase material, a solvent and an auxiliary agent to obtain a ceramic material; The step of manufacturing a chip-type pressure-sensitive resistor with the ceramic material, are included.

[0007] According to a second aspect, the present application provides a chip-type pressure-sensitive resistor, the chip-type pressure-sensitive resistor includes a main crystal phase material and an additive, and the additive includes Bi2O3, Sb2O3, MnO2, Cr2O3, Co2O3, H3BO3, Zn3(PO4)2·4H2O, Nb2O5, AgNO3 and Al(NO3)3·9H2O with a molar ratio of (1.0~2.0):(1.0~2.0):(0.4~0.8):(0.4~0.8):(0.4~0.8):(1.0~2.0):(0.8~1.6):(0.2~0.8):(0.01~0.05):(0.02~0.08).

[0008] According to a third aspect, the present application provides an electronic device, the electronic device includes a chip-type pressure-sensitive resistor manufactured by the above method, or includes the above chip-type pressure-sensitive resistor.

Advantages of the Invention

[0009] The method for manufacturing the chip-type pressure-sensitive resistor according to the first aspect of the present application has a simple manufacturing process, low energy consumption, low cost, and is applicable to industrial mass production and application. The ceramic material used in the manufactured chip-type pressure-sensitive resistor contains additives with a unique composition. Here, Bi2O3 is the main component of the high-resistance grain boundary skeleton structure that constitutes the pressure-sensitive resistor, and is the basis for making the pressure-sensitive resistor have nonlinearity. Sb2O3 is the main additive component for producing antimony zinc spinel phase, and spinel is located at the intersection of the crystal grains of the main crystal phase material such as ZnO, which promotes the growth of the main crystal phase and makes it grow uniformly, improving the breakdown voltage and square wave resistance of the element, and improving the stability of the operation of the element under large current shock and long-term electric field. If too much Sb2O3 is added, it will increase the leakage current and reduce the product's flux capacity and surge overvoltage absorption ability. Cr2O3, like Sb2O3, is involved in the formation of spinel, and can generate channels similar to Sb2O3, contributing to the improvement of component stability, while excessive doping will increase the potential gradient, increase leakage current, and deteriorate the pressure ratio. Components such as MnO2 and Co2O3 play a very important role in reducing the nonlinearity and leakage current of chip-type pressure-sensitive resistors, while also contributing to improving the resistance and stability to square waves, lightning currents, and high current shocks, but excessive doping will increase the pressure ratio of resistor chips. Components such as H3BO3 and Zn3(PO4)2·4H2O have low melting points, and the low eutectic compounds formed from the two have a significant melting auxiliary effect, which can promote grain growth and reduce the sintering temperature. In addition, the glass oxide formed by them is easy to form a dense glass phase with Bi2O3, Sb2O3, and interstitial Zn ions during the sintering process, reducing the grain boundary defect concentration and improving the long-term stability of chip resistors in an electric field environment. Nb2O5 segregates at the grain boundaries, forming spinel phases such as Zn3Nb2O8 with the main crystal phase material, which acts to prevent grain growth, and the spinel phase increases the interface state density of the grain boundaries, which increases the barrier height of the grain boundaries and improves the nonlinearity of the product. However, if the amount added is too high, it inhibits grain growth, which increases the number of grain boundary defects, increases the leakage current, and reduces the nonlinear coefficient.The monovalent silver ions of AgNO3 can lower and clamp the Fermi level, belong to the grain boundary stabilizer, suppress the movement of interlattice ions, suppress the diffusion of oxygen atoms, mitigate the degradation of the piezoresistor, and extend the service life of the component. However, if the addition amount is too large, the leakage current increases, the piezovoltage decreases, and the comprehensive performance deteriorates. Al(NO3)3·9H2O has an Al. 3+ (53.5 pm) has a small ionic radius and is easy to enter the crystal lattice, improves the carrier concentration of the main crystal phase grains, reduces the resistance of the grains, shifts the V-I characteristic curve of the piezoresistor to the high current region, reduces the limiting voltage ratio, and improves the resistance to lightning current and high current impact effects. However, if it is doped excessively, the leakage current increases and the piezovoltage rises.

[0010] The chip-type piezoresistor according to the second aspect of the present application plays a decisive role in forming an excellent non-linear structure of the piezoresistor, improving the impact current resistance, and improving the long-term operation stability, etc., due to the synergistic effect between the main crystal phase material and the additives with special formulations. In addition, low melting point components such as Bi2O3, H3BO3, and Zn3(PO4)2·4H2O in the additives can form eutectics and play a melting assistance effect, which is advantageous for reducing the sintering temperature to less than 900 °C, ensuring that the piezoresistor still has good electrical performance and long-term use stability at a low sintering temperature. Under the condition of lowering the sintering temperature, by adjusting the doping amount of each component of the additive in the ceramic material or the mixing ratio of the additive and the main crystal phase material, the application needs of piezoresistors with low, medium, and high voltage gradients can be satisfied respectively, with flexible application and wide adaptability.

[0011] The electronic device according to the third aspect of the present application includes the above chip-type piezoresistor. Since the chip-type piezoresistor has characteristics such as non-linearity, high flux, adjustable voltage gradient, and low-temperature sinterability due to the synergistic effect between the main crystal phase material and the additives with special formulations, the stability of the electronic device is improved.

Brief Description of the Drawings

[0012] To more clearly explain the technical solutions in the embodiments of this application, the drawings that need to be used in the following description of the embodiments or the prior art will be briefly introduced. Needless to say, the drawings in the following description are only some embodiments of this application, and those skilled in the art can also obtain other drawings based on these drawings without creative efforts.

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0013] To more clearly illustrate the technical problems to be solved, the technical solutions and the beneficial effects of this application, the following will further describe this application in detail with reference to the embodiments. It should be understood that the specific embodiments described here are only for explaining this application and do not limit this application.

[0014] In this application, the term "and / or" describes the relationship of related objects, and there may be three types of relationships. For example, A and / or B may indicate that A exists alone, A and B exist simultaneously, or B exists alone. Here, A and B may be singular or plural. The character " / " generally indicates that the related objects before and after are in an "or" relationship.

[0015] In this application, "at least one" means one or more, and "a plurality" means two or more. Expressions such as "at least one of the following items" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both represent a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c. Here, a, b, and c may each be single or plural.

[0016] Note that in various embodiments of this application, the magnitude of the number of each process does not mean the order of execution. Some or all steps may be executed in parallel or in sequence, and the execution order of each process should be determined by its function and internal logic, and does not limit the implementation process of the embodiments of this application in any way.

[0017] The terms used in the embodiments of this application are only for explaining specific embodiments and are not intended to limit this application. The singular forms "one" and "the" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0018] The weights of the related components mentioned in the specification of the embodiments of this application may indicate not only the specific content of each component but also the proportional relationship of the weights between the components. Therefore, as long as it is proportionally enlarged or reduced according to the content of the related components in the specification of the embodiments of this application, it falls within the scope described in the specification of the embodiments of this application. Specifically, the mass in the specification of the embodiments of this application may be mass units well-known in the chemical industry field such as μg, mg, g, kg, etc.

[0019] The terms "first" and "second" are merely for the purpose of explanation and are not for distinguishing substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of the specified technical features. For example, without departing from the scope of the embodiments of the present application, the first ○○ may be called the second ○○, and similarly, the second ○○ may be called the first ○○. Therefore, the features of "first" and "second" can explicitly or implicitly include one or more features.

[0020] The first aspect of the embodiments of the present application provides a method for manufacturing a chip-type piezoresistor, including the following steps.

[0021] In S10, an additive containing Bi2O3, Sb2O3, MnO2, Cr2O3, Co2O3, H3BO3, Zn3(PO4)2·4H2O, Nb2O5, AgNO3, and Al(NO3)3·9H2O with a molar ratio of (1.0~2.0):(1.0~2.0):(0.4~0.8):(0.4~0.8):(0.4~0.8):(1.0~2.0):(0.8~1.6):(0.2~0.8):(0.01~0.05):(0.02~0.08) is prepared.

[0022] In S20, the additive is mixed with the main crystal phase material, solvent, and auxiliary agent and subjected to a mixed grinding process to obtain a ceramic material.

[0023] In S30, a chip-type piezoresistor is manufactured using the ceramic material.

[0024] According to the manufacturing method of the chip type pressure sensitive resistor of the embodiment 1 of the present invention, additives including Bi2O3, Sb2O3, MnO2, Cr2O3, Co2O3, H3BO3, Zn3(PO4)2·4H2O, Nb2O5, AgNO3 and Al(NO3)3·9H2O are prepared with a molar ratio of (1.0-2.0):(1.0-2.0):(0.4-0.8):(0.4-0.8):(0.4-0.8):(1.0-2.0):(0.8-1.6):(0.2-0.8):(0.01-0.05):(0.02-0.08), and then the additives are mixed with the main crystalline phase material, the solvent and the auxiliary agent and polished to obtain a ceramic material, which is then manufactured into a chip type pressure sensitive resistor. The method for manufacturing the chip-type pressure-sensitive resistor of the embodiment of the present application has a simple manufacturing process, low energy consumption, low cost, and is applicable to industrial mass production and application. The ceramic material used in the manufactured chip-type pressure-sensitive resistor contains additives with a unique composition. Here, Bi2O3 is the main component of the high-resistance grain boundary skeleton structure that constitutes the pressure-sensitive resistor, and is the basis for making the pressure-sensitive resistor have nonlinearity. Sb2O3 is the main additive component for producing antimony zinc spinel phase, and spinel is located at the intersection of the grains of the main crystal phase material such as ZnO, which promotes the growth of the main crystal phase and makes it grow uniformly, improving the breakdown voltage and square wave resistance of the element, and improving the stability of the operation of the element under large current shock and long-term electric field. If too much Sb2O3 is added, it will increase the leakage current and reduce the product's flux capacity and surge overvoltage absorption ability. Cr2O3, like Sb2O3, is involved in the formation of spinel, and can generate channels similar to Sb2O3, contributing to improving the stability of the components, while excessive doping will increase the potential gradient, increase the leakage current, and worsen the pressure ratio. Components such as MnO2 and Co2O3 play a very important role in reducing the nonlinearity and leakage current of chip-type pressure-sensitive resistors, while also contributing to improving the resistance and stability to square waves, lightning currents, and high current shocks, but excessive doping will increase the pressure ratio of resistor chips. Components such as H3BO3 and Zn3(PO4)2·4H2O have low melting points, and the low eutectic compounds formed from the two have significant melting auxiliary effects, which can promote grain growth and reduce the sintering temperature.In addition, the glass oxide formed thereby is likely to form a dense glass phase with Bi2O3, Sb2O3 and interstitial Zn ions during the firing process, reduce the grain boundary defect concentration, and improve the long-term stability of the chip resistance in the electric field environment. Nb2O5 segregates at the grain boundaries, forms a spinel phase such as the main crystal phase material and Zn3Nb2O8, and plays a role in preventing grain growth. At the same time, the spinel phase increases the interface energy level density of the grain boundaries, so the barrier height of the grain boundaries can be increased, and the non-linearity of the product can be improved. However, if the addition amount is too high, grain growth will be inhibited, resulting in an increase in grain boundary defects, an increase in leakage current, and a decrease in the non-linear coefficient. The monovalent silver ions of AgNO3 can lower and clamp the Fermi level, belong to the grain boundary stabilizer, suppress the movement of interstitial ions, suppress the diffusion of oxygen atoms, alleviate the deterioration of the pressure-sensitive resistance, and extend the service life of the component. However, if the addition amount is too large, the leakage current will increase, the pressure-sensitive voltage will decrease, and the overall performance will be inferior. Al(NO3)3·9H2O is Al. 3+(53.5 pm) has a small ionic radius, is easy to enter the crystal lattice, improves the carrier concentration of the crystal grains of the main crystal phase, reduces the resistance of the crystal grains, shifts the V-I characteristic curve of the piezoresistor to the high-current region, reduces the limiting voltage ratio, and improves the resistance to lightning current and high-current impact. However, if doped excessively, the leakage current increases and the piezovoltage rises. The embodiments of this application manufacture chip-type piezoresistors, and the synergistic effect between the main crystal phase material in the ceramic material and the additives with special formulations plays a decisive role in forming an excellent non-linear structure of the piezoresistor, improving the impact current resistance, and improving the long-term operation stability. On the other hand, the low-melting-point components in the additives can form eutectics and play the role of fluxing agents, which is beneficial for reducing the sintering temperature below 900 °C, ensuring that the piezoresistor still has good electrical performance and long-term use stability at a low sintering temperature. Furthermore, by adjusting the doping amount of each component of the additive in the ceramic material or the mixing ratio of the additive and the main crystal phase material under the condition of lowering the sintering temperature, the application needs of piezoresistors with low, medium, and high voltage gradients can be satisfied respectively, realizing the manufacture of different types of ceramic materials and chip-type piezoresistors with low, medium, and high voltages simultaneously, solving the problem that it is necessary to prepare ceramic materials with different formulations for different potential gradient components in the prior art, greatly simplifying the production process, and improving the production efficiency.

[0025] In some embodiments, in the above step S10, the step of preparing the additive is to weigh Bi2O3, Sb2O3, MnO2, Cr2O3, Co2O3, H3BO3, Zn3(PO4)2·4H2O, Nb2O5, AgNO3, and Al(NO3)3·9H2O with a molar ratio of (1.0~2.0):(1.0~2.0):(0.4~0.8):(0.4~0.8):(0.4~0.8):(1.0~2.0):(0.8~1.6):(0.2~0.8):(0.01~0.05):(0.02~0.08), then put the additive powder and 80~120% of the total powder mass of water, preferably deionized water, into a planetary ball mill for mixing and grinding. When the particle size reaches the predetermined requirement, discharge it into a special tray and dry it to obtain the additive.

[0026] In some embodiments, the D50 particle size of the additive is 0.8 μm or less, and the D95 particle size is 2 μm or less. An additive with such a particle size is advantageous for the manufacturing process of the chip-type piezoresistor and ensures the nonlinear structure, low temperature, low pressure, and other characteristics of the manufactured chip-type piezoresistor. If the particle size is too small, it contributes to the subsequent sintering process, but because it is too small, the potential gradient of the manufactured piezoresistor becomes high, which is disadvantageous for the manufacture of low-temperature and low-pressure chip-type piezoresistors. If the particle size is too large, it is disadvantageous for sintering, not suitable for the conventional tape casting process, and affects the manufacturing efficiency of the chip-type piezoresistor. In some specific embodiments, the D50 particle size of the additive is 0.7 μm or less, and the D95 particle size is 1.5 μm or less.

[0027] In some embodiments, in the above step S20, a main crystal phase material is selected from zinc oxide to manufacture a ZnO chip-type piezoresistor. The main crystal phase material consists of a divalent element (Zn) and oxygen (O), which is a hexavalent element. From the perspective of the material, the zinc oxide piezoresistor is a "II-VI group oxide semiconductor". Due to the synergistic effect between the main crystal phase material and the additive with a specific formulation, the manufactured chip-type piezoresistor has characteristics such as a large flux capacity, a low limiting voltage, a fast response speed, no freewheeling, symmetric volt-ampere characteristics (i.e., product non-polarity), and a low voltage temperature coefficient.

[0028] In some embodiments, the main crystal phase material has a D50 particle size of 0.8 μm or less and a D95 particle size of 2 μm or less. If the particle size is too small, it contributes to the subsequent sintering process, but because it is too small, the potential gradient of the manufactured piezoresistor becomes high, which is disadvantageous for the manufacture of low-temperature and low-pressure chip-type piezoresistors. If the particle size is too large, it is disadvantageous for sintering, not suitable for the conventional tape casting process, and affects the manufacturing efficiency of the chip-type piezoresistor.

[0029] This application has conducted research through examples and found that the lower the content of the main crystal phase material, the higher the content of the additive, and the higher the potential gradient of the ceramic material.

[0030] In some embodiments, the step of performing the mixed grinding process includes: after mixing and grinding an additive having a mass ratio of (90-94):(6-10) with the main crystal phase material, performing a mixed grinding process with a solvent and an auxiliary agent to obtain a ceramic material having a potential of 300 V / mm to 500 V / mm, that is, a ceramic material with a low potential gradient.

[0031] In some other embodiments, the step of performing the mixed grinding process includes: after mixing and grinding an additive having a mass ratio of (86-90):(10-14) with the main crystal phase material, performing a mixed grinding process with a solvent and an auxiliary agent to obtain a ceramic material having a potential of 500 V / mm to 1000 V / mm, that is, obtaining a ceramic material with a medium potential gradient.

[0032] In some other embodiments, the step of performing the mixed grinding process includes: after mixing and grinding an additive having a mass ratio of (81-86):(14-19) with the main crystal phase material, performing a mixed grinding process with a solvent and an auxiliary agent to obtain a ceramic material having a potential of 1000 V / mm to 2000 V / mm, that is, obtaining a ceramic material with a high potential gradient.

[0033] The embodiments of the present application prepare a ceramic material with a low potential gradient, a ceramic material with a medium potential gradient, and a ceramic material with a high potential gradient respectively by adjusting the mixing ratio of the additive and the main crystal phase material in the ceramic material, meet the application requirements of low-pressure, medium-pressure, and high-pressure potential gradients respectively, and simultaneously realize the production of different types of ceramic materials and chip-type piezoresistors with low pressure, medium pressure, and high pressure, solving the problem that it is necessary to manufacture ceramic materials with different formulations for different potential gradient components in the prior art, greatly simplifying the production process and improving the production efficiency.

[0034] In some embodiments, the auxiliary agent includes a dispersant, an adhesive, and a thickener, and the auxiliary agent adjusts the material properties of the ceramic material to improve the stability of the manufactured chip-type piezoresistor.

[0035] In some embodiments, the dispersant is selected from acrylate-based ones. This type of dispersant has many active groups and binds to the main crystal phase materials such as zinc oxide and each component in the additives, dispersing each component uniformly and stably in the solution, and improving the dispersion stability and uniformity of the ceramic material. In some specific embodiments, the acrylate-based dispersants include Disperbyk-182 and Disperbyk-184 of BYK Japan Co., Ltd., and DOPA-22 of Kyoeisha Chemical Co., Ltd.

[0036] In some embodiments, the adhesive is selected from polymethyl methacrylate (PMMA)-based ones. This type of material has a relatively high viscosity and is advantageous for the binding stability of each raw material component in the high-ceramic material. In some specific embodiments, the PMMA-based adhesives include A-21 and B-44 of Rohm and Haas.

[0037] In some embodiments, the thickener is selected from at least one of dioctyl phthalate (DOP), dibutyl phthalate (DBP), and dioctyl adipate (DOA). These thickeners can improve the system viscosity, maintain the system in a uniform and stable suspension or emulsion state, or form a gel, which is advantageous for manufacturing a molded body with a ceramic material later and improving the manufacturing efficiency of the chip-type piezoresistor.

[0038] In some embodiments, the solvent includes toluene or a mixed solvent of propyl acetate and an alcohol-based solvent. The combined use of toluene or propyl acetate and an alcohol-based solvent is advantageous for improving the dissolution and dispersion stability of the additives, main crystal phase materials, and auxiliaries in the solvent and improving the stability of the ceramic material. In some specific embodiments, the solvent is selected from a mixed solvent of toluene and absolute ethanol or a mixed solvent of propyl acetate and isobutanol.

[0039] In some embodiments, in the ceramic material, the mass percentage content of the dispersant is 1% - 2%, the mass percentage content of the adhesive is 7 - 12%, the mass percentage content of the thickener is 2 - 5%, and the mass percentage content of the solvent is 50% - 80%. In the ceramic material of the embodiments of the present application, the addition amount of the solvent component is between 50% and 80% of the powder weight, which is mainly to ensure that the viscosity of the prepared slurry is within an appropriate range and is suitable for normal casting. The addition amount is affected by the type and molecular weight of the selected adhesive. The usage amount of the dispersant component is 1% - 2% of the powder weight, aiming to enhance the dispersion effect of the powder. The usage amount of the adhesive component is between 7% and 10% of the powder weight, which is determined according to the molecular weight and type of the adhesive itself. Combined with the usage amount of the solvent, it ensures an appropriate slurry viscosity for normal casting. The usage amount of the plasticizer is between 2% and 5%, aiming to reduce the intermolecular force of the adhesive, increase plasticity, and facilitate subsequent process processing. In the ceramic material of the embodiments of the present application, the addition amounts of these auxiliaries and solvents are aimed at ensuring the processability in the production of the previous step. If the addition amount is inappropriate, for example, the viscosity is inappropriate, the casting effect is poor, which will affect the subsequent product manufacturing. If the selection and addition of the dispersant are inappropriate, it will affect the dispersion effect of the powder and the consistency of the subsequent product performance. If the usage amounts of the adhesive and the plasticizer are inappropriate, appearance defects such as sheet adhesion and burrs will occur in the subsequent cut processed products.

[0040] In some embodiments, the step of mixing the additive with the main crystal phase material, the solvent and the auxiliary and performing a mixing and grinding treatment includes: after mixing the additive with the main crystal phase material, adding the solvent and the dispersant, and performing ball milling for 6 - 12 hours by a planetary ball mill under the condition that the ball mill frequency is 25 - 30 HZ, and then further adding the adhesive and the thickener, and performing ball milling for 6 - 12 hours by a planetary ball mill under the condition that the ball mill frequency is 25 - 30 HZ to obtain the ceramic material. The grinding of each component in the ceramic material is uniform, the dispersion is stable, which is advantageous for the subsequent manufacture of the chip type piezoresistor.

[0041] In some embodiments, in the above step S30, the step of manufacturing the chip-type piezoresistor with a ceramic material includes forming the ceramic material into a shaped body film based on a predetermined structure, then printing internal electrodes, and sequentially performing a lamination process, a warm pressing process, a cutting process, a slurry discharging process, a sintering process, a terminal electrode process, and a plating process to manufacture the chip-type piezoresistor.

[0042] In some embodiments, the temperature of the sintering process is 850 °C or higher and 900 °C or lower. Among the additives of the ceramic material in the embodiments of the present application, low melting point components such as Bi2O3, H3BO3, and Zn3(PO4)2·4H2O can form eutectics, exhibit a melting assisting effect, are advantageous for reducing the sintering temperature of the ceramic material, lower the sintering temperature below 900 °C, and ensure that the piezoresistor has good electrical performance and long-term use stability at a low sintering temperature.

[0043] In some embodiments, the silver content in the silver slurry used in the terminal electrode process is 60% to 70%, and the sintering temperature of silver is 600 °C to 800 °C. In some specific embodiments, the internal electrode layer slurry is a pure silver slurry. Preferably, the silver content of the pure silver slurry is 85% to 92%, the printing thickness is 5 to 10 μm, and the sintering temperature is between 850 °C and 900 °C.

[0044] A second aspect of the embodiments of the present application provides a chip-type piezoresistor, which includes a main crystal phase material and an additive. The additive includes Bi2O3, Sb2O3, MnO2, Cr2O3, Co2O3, H3BO3, Zn3(PO4)2·4H2O, Nb2O5, AgNO3, and Al(NO3)3·9H2O with a molar ratio of (1.0 to 2.0):(1.0 to 2.0):(0.4 to 0.8):(0.4 to 0.8):(0.4 to 0.8):(1.0 to 2.0):(0.8 to 1.6):(0.2 to 0.8):(0.01 to 0.05):(0.02 to 0.08).

[0045] The chip-type piezoresistor according to the second aspect of the embodiment of the present application includes a main crystal phase material and an additive. The additive includes Bi2O3, Sb2O3, MnO2, Cr2O3, Co2O3, H3BO3, Zn3(PO4)2·4H2O, Nb2O5, AgNO3, and Al(NO3)3·9H2O with a molar ratio of (1.0~2.0):(1.0~2.0):(0.4~0.8):(0.4~0.8):(0.4~0.8):(1.0~2.0):(0.8~1.6):(0.2~0.8):(0.01~0.05):(0.02~0.08). Due to the synergistic effect between the main crystal phase material and the specially formulated additive, it plays a decisive role in forming an excellent non-linear structure of the piezoresistance, improving the impact current resistance, and enhancing the long-term operation stability. In addition, low melting point components such as Bi2O3, H3BO3, and Zn3(PO4)2·4H2O in the additive can form a eutectic and play a melting assistance effect, which is beneficial for reducing the sintering temperature to less than 900°C, ensuring that the piezoresistor still has good electrical performance and long-term use stability at a low sintering temperature. Under the condition of lowering the sintering temperature, by adjusting the doping amount of each component of the additive in the ceramic material or the mixing ratio of the additive and the main crystal phase material, the application needs of piezoresistors with low, medium, and high voltage gradients can be satisfied respectively, with flexible application and wide adaptability.

[0046] The chip-type piezoresistor according to the embodiment of the present application can be manufactured by the method of the above embodiment.

[0047] In some embodiments, the main crystal phase material is selected from zinc oxide.

[0048] In some embodiments, the main crystal phase material has a particle size D50 of 0.8 μm or less and a particle size D95 of 2 μm or less.

[0049] In some embodiments, the additive has a particle size D50 of 0.8 μm or less and a particle size D95 of 2 μm or less.

[0050] In some embodiments, the mass ratio of the main crystal phase material to the additive is (81~94):(6~19).

[0051] In some specific embodiments, when the mass ratio of the main crystal phase material to the additive is (90 - 94):(6 - 10), the potential of the chip-type piezoresistor is 300 V / mm to 500 V / mm.

[0052] In some specific embodiments, when the mass ratio of the main crystal phase material to the additive is (86 - 90):(10 - 14), the potential of the chip-type piezoresistor is 500 V / mm to 1000 V / mm.

[0053] In some specific embodiments, when the mass ratio of the main crystal phase material to the additive is (81 - 86):(14 - 19), the potential of the chip-type piezoresistor is 1000 V / mm to 2000 V / mm.

[0054] The technical effects of the above embodiments of the present application are described in the foregoing, and the description is omitted here.

[0055] In some specific embodiments, when the main crystal phase material is zinc oxide and the mass ratio of zinc oxide to the additive is 92:8, the flux density of the chip-type piezoresistor is 59 A / mm 2It is very high. Since the time of the applied rush current is short, when a large current is applied to the ZnO varistor, it is absorbed by the varistors of cells with different pulse capabilities within a short time, and the generated heat raises the temperature of the product. Since the heat generated in such a short time cannot be effectively and quickly diffused to other parts of the varistor, the varistors of different cells rapidly increase in temperature in a short time, and the temperature gradient between two different cells generates thermal stress at the grain boundaries between them. When the thermal stress between different parts inside the resistor exceeds the critical value, it bursts and fails. There are several factors that affect the degree of temperature diffusion and the difference in the temperature gradient between two adjacent cells, such as the uniformity in the microstructure, the thermal conductivity, specific heat constant, and specific gravity of the ceramic material. The microstructure of the varistor, from a microscopic perspective, consists of zinc oxide crystal grains, grain boundary layers, and spinel three phases. Since the electrical resistance of the zinc oxide crystal grains is (1 - 10) Ω·cm and the electrical resistivity of the grain boundary layer is (10^12 - 10^13) Ω·cm, the voltage applied to the varistor is basically applied to the grain boundary layer. The heat generation characteristics of the grain boundary layer depend on the heat dissipation characteristics such as the heat capacity and thermal conductivity of the zinc oxide crystal grains in contact with it. Therefore, the flux capacity of the high-energy varistor is generally determined by the heat capacity of the zinc oxide crystal grains. Needless to say, in the chip-type varistor, the larger the ZnO crystal grains, that is, the higher the ZnO content, the larger the flux capacity of the high-energy varistor. By reducing the content of the additive, the grain boundary layer becomes thinner, contributing to the growth of the zinc oxide crystal grains. Moreover, since both the thermal conductivity and heat capacity of the zinc oxide crystal grains are higher than those of the grain boundary layer material, reducing the content of the additive within a certain range contributes to the improvement of the flux passing ability of the product.

[0056] The third aspect of the embodiment of the present application provides an electronic device, which includes a chip-type varistor manufactured by the above method, or includes the above chip-type varistor.

[0057] The electronic device according to the third aspect of the embodiment of the present application includes the above chip-type piezoresistor. The chip-type piezoresistor has characteristics such as non-linearity, high flux, adjustable voltage gradient, and low-temperature sinterability due to the synergistic effect of the main crystal phase material and a special compounding additive, thereby improving the stability of the electronic device.

[0058] To clarify the details and operations of the above embodiments of the present application for those skilled in the art to understand and to highlight the progressiveness of the chip-type piezoresistor and its manufacturing method according to the embodiments of the present application, the following technical solutions will be described by multiple embodiments.

[0059] [Example 1] Manufacture a chip-type piezoresistor in the following steps.

[0060] 1) Weigh the additive so that the chemical composition and mixing ratio (mole percentage) are Bi2O3:Sb2O3:MnO2:Cr2O3:Co2O3:H3BO3:Zn3(PO4)2·4H2O:Nb2O5:AgNO3:Al(NO3)3·9H2O = 1.2:1.0:0.5:0.5:1.0:1.2:1.0:0.1:0.02:0.03. Add ionic water of 90% of the total mass of the additive powder, put it into a planetary ball mill and mix and grind for 16 h. When the particle size meets the requirements of a predetermined D50≤0.8 μm and D95≤2 μm, discharge it into a dedicated tray and perform a drying treatment in an oven at a temperature of 150°C ± 10°C to obtain an additive for subsequent compounding.

[0061] 2) With a material mixing ratio of 92 wt% ZnO + 8 wt% additive, weigh and grind the corresponding mass of the additive, mix the additive after the grinding treatment with the corresponding mass of zinc oxide powder, and add the corresponding mass of solvent (propyl acetate of 50% of the total powder mass and isobutanol of 15% of the total powder mass). After adding an acrylate-based dispersant (1.5% of the total powder mass), perform ball milling and mixing in a planetary ball mill under the conditions of 30 Hz and 8 h.

[0062] 3) After the ball milling mixing was completed, 12% of the total powder mass of polymethyl methacrylate-based adhesive and 5% of the total powder mass of dioctyl phthalate thickener were continuously added to the slurry, and mixing and dispersion were carried out again in a planetary ball mill under the conditions of 30 Hz and 8 h to obtain a ceramic material.

[0063] 4) After discharging the ceramic material, it was cast onto a PET film to form a molded body film with a thickness of 40 μm. Based on the structure design of size 4532, a dielectric layer thickness of 0.14 mm, and six internal electrodes, the processes of lamination, hot water pressing, cutting, slurry discharging, sintering, terminal electrode manufacturing, and plating were sequentially completed, and finally, a chip-type pressure-sensitive resistor corresponding to the needs was obtained. Here, the internal electrodes were printed with pure silver slurry with a silver content of 90%, and the printing thickness was 7 - 9 μm. The highest sintering temperature was 870 °C, and it was kept warm for 2 h. The terminal electrode silver slurry was manufactured with a terminal slurry with a silver content of 65%, silver sintering was carried out at the highest temperature of 750 °C, the conductive terminals were fabricated, and a chip-type pressure-sensitive resistor was obtained.

[0064] [Example 2] A chip-type pressure-sensitive resistor is manufactured in the following steps.

[0065] 1) The preparation and composition of the additives were the same as in Example 1 and were used as they were.

[0066] 2) With a material mixing ratio of 88 wt% ZnO + 12 wt% additives, the corresponding mass of additives was weighed and pulverized. After the pulverization treatment, the additives and the corresponding mass of zinc oxide powder were mixed, and the corresponding mass of solvent (propyl acetate at 50% of the total powder mass and isobutanol at 15% of the total powder mass) was added. After adding an acrylate-based dispersant (1.5% of the total powder mass), ball milling mixing was carried out in a planetary ball mill under the conditions of 30 Hz and 8 h.

[0067] 3) After the ball milling mixing was completed, 12% of the total powder mass of polymethyl methacrylate-based adhesive and 5% of the total powder mass of dioctyl phthalate thickener were continuously added to the slurry, and mixing and dispersion were carried out again in a planetary ball mill under the conditions of 30 Hz and 8 h to obtain a ceramic material.

[0068] 4) After discharging the ceramic material, it was cast onto a formed body film with a thickness of 40 μm on a PET film. Based on the 4532 size, a dielectric layer thickness of 0.14 mm, and the structural design of six internal electrodes, the processes of lamination, hot water pressing, cutting, slurry discharging, sintering, terminal electrode manufacturing, and plating were sequentially completed, and finally a chip-type pressure-sensitive resistor corresponding to the needs was obtained. Here, the internal electrodes were printed with a pure silver slurry having a silver content of 90%, and the printing thickness was 7 - 9 μm. The maximum sintering temperature was 870 °C, and it was kept warm for 2 h. The terminal electrode silver slurry was manufactured with a terminal slurry having a silver content of 65%, and silver sintering was performed at a maximum temperature of 750 °C to complete the production of conductive terminals and obtain a chip-type pressure-sensitive resistor.

[0069] [Example 3] Manufacture a chip-type pressure-sensitive resistor in the following steps.

[0070] 1) The preparation and composition of the additive were the same as in Example 1 and were used as they were.

[0071] 2) With a material mixing ratio of 84 wt% ZnO + 16 wt% additive, weigh and crush the corresponding mass of the additive. After the crushing treatment, mix the additive with the corresponding mass of zinc oxide powder, and add the corresponding mass of solvent (propyl acetate at 50% of the total powder mass and isobutanol at 15% of the total powder mass). After adding an acrylic acid ester-based dispersant (1.5% of the total powder mass), perform ball milling and mixing under the conditions of 30 Hz and 8 h with a planetary ball mill.

[0072] 3) After the ball milling and mixing are completed, continue to add a polymethyl methacrylate-based adhesive at 12% of the total powder mass and a dioctyl phthalate thickener at 5% of the total powder mass to the slurry, and perform mixing and dispersion again under the conditions of 30 Hz and 8 h with a planetary ball mill to obtain a ceramic material.

[0073] 4) After discharging the ceramic material, it was cast onto a formed body film with a thickness of 40 μm on a PET film. Based on the 4532 size, a dielectric layer thickness of 0.14 mm, and the structural design of six internal electrodes, the processes of lamination, hot water pressing, cutting, slurry discharging, sintering, terminal electrode manufacturing, and plating were sequentially completed, and finally a chip-type pressure-sensitive resistor corresponding to the needs was obtained. Here, the internal electrodes were printed with a pure silver slurry having a silver content of 90%, and the printing thickness was 7 - 9 μm. The highest sintering temperature was 870 °C, and it was kept warm for 2 h. The terminal electrode silver slurry was manufactured with a terminal slurry having a silver content of 65%, silver sintering was performed at the highest temperature of 750 °C, the conductive terminals were fabricated, and a chip-type pressure-sensitive resistor was obtained.

[0074] [Example 4] Manufacture a chip-type pressure-sensitive resistor. In Step 1, it is different from Example 1 in that Bi2O3:Sb2O3:MnO2:Cr2O3:Co2O3:H3BO3:Zn3(PO4)2·4H2O:Nb2O5:AgNO3:Al(NO3)3·9H2O = 1.5:0.9:0.5:0.5:1.0:1.6:1.5:0.1:0.02:0.03.

[0075] Furthermore, in order to verify the progressiveness of the examples of the present application, the following tests were respectively carried out on the electrochemical performance such as the pressure-sensitive voltage, leakage current, non-linear coefficient, peak current, potential gradient, and flux density, and the morphology of the chip-type pressure-sensitive resistors manufactured in the examples.

[0076] 1. The test method for the pressure-sensitive voltage is that the nominal value of the pressure-sensitive voltage is V1mA, and this parameter is one of the parameters at the conversion point between the pre-breakdown region and the breakdown region in the zinc oxide pressure-sensitive resistor volt-ampere curve. Generally, it is the voltage value across the product when a direct current of 1 mA flows.

[0077] 2. The test method for the leakage current is the current value passing through the product at 75% of the pressure-sensitive voltage V1mA.

[0078] 3. The measurement method for the non-linear coefficient is to calculate the non-linear coefficient α by the formula α = 1 / (logV1mA / V0.1mA).

[0079] 4. The peak current test method measures whether the product can withstand the peak value of the 8 / 20 μS pulse current for a specified number of times.

[0080] 5. The method for measuring the potential gradient voltage calculates the value obtained by dividing the pressure-sensitive voltage value by the dielectric layer thickness.

[0081] 6. The test method for the flux density refers to the national standard "GJB 1782A-2015".

[0082] The results of the above tests are shown in Table 1 below.

[0083]

Table 1

[0084] As can be seen from the above test results, all the chip-type pressure-sensitive resistors manufactured in the examples of this application have a high flux density, a low pressure-sensitive voltage, a low leakage current, a high non-linear coefficient, and the potential gradient can be flexibly adjusted by the mixing ratio of the zinc oxide main crystal phase material and the additive. By adjusting the mixing ratio of the zinc oxide main crystal phase material and the additive, low-potential chip-type pressure-sensitive resistors, medium-potential chip-type pressure-sensitive resistors, and high-potential chip-type pressure-sensitive resistors can be manufactured respectively. In the low-voltage, medium-voltage, and high-voltage ranges, the small leakage current indicates that the power consumption of the product is small, which improves the application performance of the component, improves the flexibility of the application of the chip-type pressure-sensitive resistor, and simplifies the manufacturing process. Also, the high non-linear coefficient indicates that the pressure-sensitive characteristics of the product are obvious, and the peak current indicates that the surge protection ability of the product is strong.

[0085] 7. Using a scanning electron microscope, the morphology of the chip-type pressure-sensitive resistor manufactured in the examples was observed respectively, and the measurement results are shown in FIGS. 2 to 4. Here, FIG. 2 is a SEM microscopic morphology diagram of the chip-type pressure-sensitive resistor of Example 1, FIG. 3 is a SEM microscopic morphology diagram of the chip-type pressure-sensitive resistor of Example 2, and FIG. 4 is a SEM microscopic morphology diagram of the chip-type pressure-sensitive resistor of Example 3. As can be seen from the morphology diagrams, the chip-type pressure-sensitive resistor manufactured in the examples of this application has a uniform particle distribution, a flat surface, and improved stability of the chip-type pressure-sensitive resistor.

[0086] The above are only preferred embodiments of this application and do not limit this application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should all be included within the protection scope of this application.

Claims

1. A method for manufacturing a chip-type piezoresistor, comprising: The Bi with a molar ratio of (1.0 to 2.0):(1.0 to 2.0):(0.4 to 0.8):(0.4 to 0.8):(0.4 to 0.8):(1.0 to 2.0):(0.8 to 1.6):(0.2 to 0.8):(0.01 to 0.05):(0.02 to 0.08) ２ O ３ , Sb ２ O ３ , MnO ２ , Cr ２ O ３ , Co ２ O ３ , H ３ BO ３ , Zn ３ (PO ４ ) ２ ·4H ２ O, Nb ２ O ５ , AgNO ３ and Al(NO ３ ) ３ ·9H ２ O to prepare an additive containing mixing and polishing the additive with a primary crystal phase material, a solvent, and an auxiliary agent to obtain a ceramic material; and manufacturing a chip-type piezoresistor using the ceramic material. A method for manufacturing a chip-type piezoresistor.

2. The primary crystal phase material is selected from zinc oxide, and / or the primary crystal phase material has a particle size D50 of 0.8 μm or less and a particle size D95 of 2 μm or less, and / or the additive has a particle size D50 of 0.8 μm or less and a particle size D95 of 2 μm or less. The method for manufacturing a chip-type piezoresistor according to Claim 1.

3. The step of mixing and polishing comprises: mixing the additive having a mass ratio of (90-94):(6-10) with the primary crystal phase material, polishing, then mixing and polishing with the solvent and the auxiliary agent to obtain a ceramic material having a potential of 300 V / mm to 500 V / mm, or mixing the additive having a mass ratio of (86-90):(10-14) with the primary crystal phase material, polishing, then mixing and polishing with the solvent and the auxiliary agent to obtain a ceramic material having a potential of 500 V / mm to 1000 V / mm, or mixing the additive having a mass ratio of (81-86):(14-19) with the primary crystal phase material, polishing, then mixing and polishing with the solvent and the auxiliary agent to obtain a ceramic material having a potential of 1000 V / mm to 2000 V / mm. The method for manufacturing a chip-type piezoresistor according to Claim 1.

4. The auxiliary agent includes a dispersant, an adhesive, and a thickener, and / or the solvent includes a mixed solvent of toluene or propyl acetate and an alcohol-based solvent. The method for manufacturing a chip-type piezoresistor according to Claim 3.

5. In the ceramic material, the mass percentage content of the dispersant is 1% to 2%, the mass percentage content of the adhesive is 7 to 12%, the mass percentage content of the thickener is 2 to 5%, and the mass percentage content of the solvent is 50% to 80%, and / or the dispersant is selected from acrylate-based, and / or the adhesive is selected from polymethyl methacrylate-based, and / or the thickener is selected from at least one of dioctyl phthalate, dibutyl phthalate, and dioctyl adipate, and / or The solvent is selected from a mixed solvent of toluene and absolute ethanol, or a mixed solvent of propyl acetate and isobutanol. The method for manufacturing a chip-type pressure-sensitive resistor according to claim 4.

6. The step of performing the mixed grinding process is as follows: After mixing the additive and the main crystal phase material, the solvent and the dispersant are added, and ball milling is performed for 6 to 12 hours using a planetary ball mill under the condition that the ball mill frequency is 25 to 30 Hz. Then, the adhesive and the thickener are added, and ball milling is performed for 6 to 12 hours using a planetary ball mill under the condition that the ball mill frequency is 25 to 30 Hz to obtain the ceramic material. The method for manufacturing a chip-type pressure-sensitive resistor according to claim 4 or 5.

7. The step of manufacturing a chip-type pressure-sensitive resistor with the ceramic material is as follows: Based on a predetermined structure, the ceramic material is formed into a shaped body film, then an internal electrode is printed, and a lamination process, a warm water pressing process, a cutting process, a slurry discharging process, a sintering process, a terminal electrode process, and a plating process are sequentially performed to manufacture a chip-type pressure-sensitive resistor. The method for manufacturing a chip-type pressure-sensitive resistor according to claim 6.

8. The temperature of the sintering process is 850 °C or higher and 900 °C or lower, and / or The silver content in the silver slurry used in the terminal electrode process is 60 to 70%, and the sintering temperature of silver is 600 to 800 °C. The method for manufacturing a chip-type pressure-sensitive resistor according to claim 7.

9. The chip-type pressure-sensitive resistor, The chip-type pressure-sensitive resistor includes a main crystal phase material and an additive. The additive is Bi with a molar ratio of (1.0 to 2.0):(1.0 to 2.0):(0.4 to 0.8):(0.4 to 0.8):(0.4 to 0.8):(1.0 to 2.0):(0.8 to 1.6):(0.2 to 0.8):(0.01 to 0.05):(0.02 to 0.08). ２ O ３ , Sb ２ O ３ , MnO ２ , Cr ２ O ３ , Co ２ O ３ , H ３ BO ３ , Zn ３ (PO ４ ) ２ ·4H ２ O, Nb ２ O ５ , AgNO ３ and Al(NO ３ ) ３ ·9H ２ O and contains Chip-type pressure-sensitive resistor.

10. An electronic device, The electronic device includes a chip-type pressure-sensitive resistor manufactured by the method for manufacturing a chip-type pressure-sensitive resistor according to any one of claims 1 to 5, or a chip-type pressure-sensitive resistor according to claim 9. Electronic device.

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