NTC thermistor and preparation method thereof

Abstract

The present application relates to the technical field of thermistor, particularly to a NTC thermistor and a preparation method thereof, comprising an insulating substrate, a plurality of NTC modules which are isolated from each other and arranged side by side on the insulating substrate in the same direction, a first conductive film unit arranged on the insulating substrate and located at one side of the NTC unit, a second conductive film unit arranged on the insulating substrate and located at the other side of the NTC unit, a plurality of fuse film layers, and a protective layer covering the NTC modules and the fuse film layers, wherein the plurality of fuse film layers are respectively arranged between the NTC modules and the first conductive film unit and between the NTC modules and the second conductive film unit, and the melting points of the fuse film layers are all lower than those of the first and second conductive film units; by using the fuse film layers with lower melting points to connect the branches of the NTC modules, the present application realizes hierarchical protection of faults, when high temperature is generated due to overvoltage or overcurrent, the fuse film layers are preferentially fused to isolate the single or partial fault NTC modules, thereby avoiding complete failure of the NTC thermistor and providing reliability.

Description

Technical Field

[0001] This invention relates to the field of thermistor technology, and in particular to an NTC thermistor and its preparation method. Background Technology

[0002] Existing NTC thermistors generally adopt an integrated structure of "electrode-NTC ceramic functional body-electrode", such as multilayer SMD type, single-layer SMD type and single-layer chip type. Their NTC ceramic functional body is a single unit, with the electrodes on both sides directly covering its surface, and no special breakdown protection structure is set. It relies solely on the voltage resistance of the ceramic itself to resist instantaneous overvoltage and overcurrent impacts. In practical applications, abnormal operating conditions such as instantaneous high voltage and surge current can easily cause the NTC ceramic functional body to break down, burn out or even explode, causing the entire NTC thermistor to completely fail and lose its core function. The complete failure of the NTC thermistor will also cause the entire module or system to malfunction or even be scrapped, increasing maintenance and replacement costs and potentially causing safety hazards.

[0003] To address the aforementioned shortcomings, there is an urgent need for an NTC thermistor that can provide breakdown protection during instantaneous overvoltage and overcurrent events to prevent the failure of the entire device. Summary of the Invention

[0004] This invention provides an NTC thermistor and its preparation method that can achieve breakdown protection under instantaneous overvoltage and overcurrent to avoid overall failure, thereby solving the problem that the NTC ceramic functional body in existing products is prone to breakdown, burnout or even explosion under abnormal operating conditions such as instantaneous high voltage and surge current, causing the entire NTC thermistor to fail completely.

[0005] An NTC thermistor, comprising:

[0006] Insulating substrate; An NTC unit includes multiple NTC modules, which are isolated from each other and arranged side by side on the insulating substrate in the same direction. The first conductive film unit is disposed on the insulating substrate and located on one side of the NTC unit; The second conductive film unit is disposed on the insulating substrate and located on the other side of the NTC unit; Multiple fuse layers are respectively disposed between each NTC module and the first conductive film unit, and between each NTC module and the second conductive film unit, to form a parallel circuit; A protective layer covers the NTC unit and the plurality of fuse layers; The melting point of the fusible film layer is lower than that of the first conductive film unit and the second conductive film unit.

[0007] Optionally, both the first conductive film unit and the second conductive film unit include at least one underlay layer and at least one solder layer, and the underlay layer and the solder layer are stacked alternately.

[0008] Optionally, the underlayer is a nickel layer and the solder layer is a silver layer.

[0009] Optionally, the fusible film layer is an aluminum layer.

[0010] Optionally, the first conductive film unit is a first conductive film layer extending along the arrangement direction of the NTC modules, and each NTC module is connected to the first conductive film layer through a fuse layer; the second conductive film unit is a second conductive film layer extending along the arrangement direction of the NTC modules, and each NTC module is connected to the second conductive film layer through a fuse layer.

[0011] Optionally, the first conductive film unit includes a plurality of first conductive film modules arranged side by side along the arrangement direction of the NTC module, two adjacent first conductive film modules are connected by the fusible film layer, and each first conductive film module is correspondingly disposed on one side of an NTC module and connected to the NTC module through a fusible film layer.

[0012] Optionally, the second conductive film unit includes a plurality of second conductive film modules arranged side by side along the arrangement direction of the NTC module, adjacent two second conductive film modules are connected by the fusible film layer, and each second conductive film module is correspondingly arranged on the other side of the NTC module and connected to the NTC module through the fusible film layer.

[0013] Optionally, the protective layer is one of a glass encapsulation layer and a resin encapsulation layer; the insulating substrate is a ceramic substrate.

[0014] To address the problems existing in the prior art, the present invention also provides a method for preparing an NTC thermistor, which includes the following steps: The powder of the mixture is prepared according to the NTC formula, and then formed into a ceramic block with NTC properties through grinding, drying, sieving, pressing and sintering. A ceramic block with NTC properties is sputtered onto an insulating substrate to form multiple NTC modules that are isolated from each other and arranged in the same direction on the insulating substrate. A conductive film is sputtered on an insulating substrate to form a first conductive film unit and a second conductive film unit on both sides of the NTC module, respectively. A fusion-breaking metal film is sputtered between each NTC module and the first conductive film unit, and between each NTC module and the second conductive film unit, to form multiple fusion-breaking film layers. The NTC module and the fuse layer are encapsulated with glass or resin.

[0015] Optionally, the following steps are also included: Multiple conductive films are sputtered on both sides of the NTC module to form multiple first conductive film modules arranged side by side along the NTC module's arrangement direction on one side of the NTC module, and multiple second conductive film modules arranged side by side along the NTC module's arrangement direction on the other side of the NTC module. A fusion-breaking metal film is sputtered between two adjacent first conductive film modules and between two adjacent second conductive film modules. Alternatively, a single conductive film extending along the arrangement direction of the NTC module can be sputtered onto both sides of the NTC module to form a first conductive film layer and a second conductive film layer.

[0016] The beneficial effects of the NTC thermistor provided in this invention are as follows: By setting up multiple mutually isolated NTC modules and using a fusible film layer to connect each NTC module with the first conductive film unit and the second conductive film unit on both sides to form a parallel circuit, the traditional "electrode-NTC ceramic-electrode" structural design of NTC thermistors is broken. By using a fusible film layer with a lower melting point for branch connection, the basic structural support for fault graded protection is realized. When encountering instantaneous overvoltage or overcurrent, the high temperature generated by high voltage or high current will preferentially cause the fusible film layer with a lower melting point to melt, thereby isolating a single or partial faulty NTC module, thus avoiding the complete failure of the entire NTC thermistor and ensuring the reliability of the whole system. Attached Figure Description

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a schematic diagram of the structure of the NTC thermistor in an embodiment of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the structure of the NTC thermistor in an embodiment of the present invention. Figure 2 ; Figure 3 This is a flowchart of the method for preparing the NTC thermistor in this embodiment of the invention. Figure 1 ; Figure 4 This is the semi-finished structure of the NTC thermistor in the embodiments of the present invention. Figure 1 ; Figure 5 This is the semi-finished structure of the NTC thermistor in the embodiments of the present invention. Figure 2 ; Figure 6 This is the semi-finished structure of the NTC thermistor in the embodiments of the present invention. Figure 3 ; Figure 7 This is a flowchart of the method for preparing the NTC thermistor in this embodiment of the invention. Figure 2 ; Figure 8 This is a flowchart of the method for preparing the NTC thermistor in this embodiment of the invention. Figure 3 .

[0018] The labels for the attached figures are as follows: 1. Insulating substrate; 2. NTC module; 5. Fuse film layer; 6. Protective layer; 31. First conductive film layer; 32. Second conductive film layer; 33. First connecting conductive film; 41. First conductive film module; 42. Second conductive film module; 43. Second connecting conductive film. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] like Figure 1 and Figure 2 As shown, the present invention provides a specific embodiment of an NTC thermistor.

[0021] An NTC thermistor, reference Figure 1 and Figure 2 The NTC thermistor includes an insulating substrate 1, an NTC unit, a first conductive film unit, a second conductive film unit, multiple fusible film layers 5, and a protective layer 6. The NTC unit includes multiple NTC modules 2, which are isolated from each other and arranged side by side on the insulating substrate 1 in the same direction. The first conductive film unit is disposed on the insulating substrate 1 and located on one side of the NTC unit. The second conductive film unit is disposed on the insulating substrate 1 and located on the other side of the NTC unit. The multiple fusible film layers 5 are respectively disposed between each NTC module 2 and the first conductive film unit, and between each NTC module 2 and the second conductive film unit to form a parallel circuit. The protective layer 6 covers the NTC unit and the multiple fusible film layers 5 for encapsulation and protection. The melting point of the fusible film layer 5 is lower than that of the first conductive film unit and the second conductive film unit.

[0022] Specifically, refer to Figure 1 and Figure 2The insulating substrate 1 serves as the carrier substrate for the NTC thermistor, supporting other functional structures and providing electrical insulation between functional layers to prevent leakage and short circuits, ensuring the electrical safety of the device. The NTC unit consists of multiple NTC modules 2, which are used to realize the negative temperature coefficient thermistor function, sensing temperature changes and correspondingly changing their own resistance. They are the core of the device's temperature measurement and control functions. The multiple NTC modules 2 are mutually insulated and arranged side by side along the same direction on the surface of the insulating substrate 1. Each NTC module 2 is an independent thermistor unit and can realize the thermistor function independently. The first conductive film unit is disposed on the insulating substrate 1 and located on one side of the NTC unit. As one of the electrical access terminals, it is used to conduct current and introduce the current from the external circuit into the NTC module 2. The second conductive film unit is disposed on the insulating substrate 1 and located on the other side of the NTC unit, corresponding to the first conductive film unit. As another electrical access terminal, it is used to conduct current and conduct the current from the NTC module 2 to the external circuit, thus forming a complete conductive loop with the first conductive film unit.

[0023] Further, refer to Figure 1 and Figure 2 Each NTC module 2 is connected to the first conductive film unit with a corresponding fuse layer 5, and each NTC module 2 is also connected to the second conductive film unit with a corresponding fuse layer 5. Through the above connection method, multiple NTC modules 2 form a parallel circuit with the first conductive film unit and the second conductive film unit through the fuse layer 5. The fuse layer 5 is used to realize fault protection. Since the melting point of the fuse layer 5 is lower than that of the first conductive film unit and the second conductive film unit, when a fault occurs, the high temperature generated by overvoltage and overcurrent will preferentially cause the corresponding fuse layer 5 to melt, thereby realizing rapid isolation of the faulty NTC module 2, avoiding the expansion of the fault, and protecting the first conductive film unit and the second conductive film unit from damage. This ensures that the non-faulty NTC module 2 can normally conduct current through the first conductive film unit, the second conductive film unit and its corresponding fuse layer 5, ensuring that the device only experiences functional degradation rather than complete failure. The protective layer 6 completely covers the outside of the NTC unit and all the fuse layers 5, and is used to encapsulate and protect the internal functional structure, isolate external moisture, dust, mechanical stress and other interference, prevent damage to the internal structure, and improve the device's environmental adaptability and service life.

[0024] In this embodiment, by setting up multiple mutually isolated NTC modules 2 and using a fusible film layer 5 to connect each NTC module 2 with the first conductive film unit and the second conductive film unit on both sides to form a parallel circuit, the traditional "electrode-NTC ceramic-electrode" structural design of NTC thermistors is broken. By using a fusible film layer 5 with a lower melting point for branch connection, the basic structural support for fault grade protection is realized. When encountering instantaneous overvoltage or overcurrent, the high temperature generated by high voltage or high current will preferentially cause the fusible film layer 5 with a lower melting point to melt, thereby isolating a single or partial faulty NTC module 2, thus avoiding the complete failure of the entire NTC thermistor and ensuring the reliability of the whole system.

[0025] In one embodiment, both the first conductive film unit and the second conductive film unit adopt a multilayer composite structure, each including at least one underlayer and at least one solder layer. The underlayer and solder layers are alternately stacked to form a multilayer superimposed conductive film structure. The underlayer is used to enhance the bonding force between the first and second conductive film units and the insulating substrate 1, prevent the film layer from falling off, and ensure structural stability. The core function of the solder layer is to improve the soldering compatibility of the conductive film unit, facilitate the soldering connection between the device and the external circuit, and at the same time help improve the conductivity. The multilayer alternating stacked structure can improve the bonding strength between the first and second conductive film units and the insulating substrate 1, while improving the overall conductivity and solderability, and ensuring the stability of current conduction.

[0026] This embodiment sets the first conductive film unit and the second conductive film unit as a multi-layer structure with alternating underlayer and solder layers. Compared with a single-layer conductive film, this can significantly improve the overall performance of the conductive film unit: the underlayer can enhance the bonding force between the conductive film and the insulating substrate 1, avoiding the problem of film peeling off during use; the solder layer can improve the soldering compatibility of the conductive film unit, facilitating the soldering connection between the device and the external circuit; the multi-layer alternating stacked structure can also reduce the conductive resistance, improve the current conduction efficiency, and enhance the mechanical stability and aging resistance of the conductive film unit.

[0027] In one embodiment, the bottom layer is a nickel layer, the welding layer is a silver layer, and the fusing film layer 5 is an aluminum layer. The nickel layer contacts the insulating substrate 1, utilizing the high adhesion of nickel to form a firm bond with the insulating substrate 1, preventing the first and second conductive film units from falling off and ensuring structural reliability. The silver layer is located on the outside, and its core function is to utilize the excellent conductivity of silver to reduce conductive loss and improve current conduction efficiency. At the same time, the good welding performance of silver facilitates the welding of the device to external circuits, and the good oxidation resistance of silver can extend the service life of the first and second conductive film units. Utilizing the low melting point of aluminum, it is used as the fusing film layer 5, which can preferentially melt at high temperatures, cutting off the connection between the faulty NTC module 2 and the first and second conductive film units in a timely manner, isolating the faulty module, and preventing the fault from spreading to the entire NTC thermistor.

[0028] This invention provides two design schemes for the first conductive film unit and the second conductive film unit, based on different sensitivity requirements and resistance stability requirements.

[0029] Option 1 refer to Figure 1 The first conductive film unit is a first conductive film layer 31 extending along the arrangement direction of the NTC module 2, and each NTC module 2 is connected to the first conductive film layer 31 through a fusible film layer 5; the second conductive film unit is a second conductive film layer 41 extending along the arrangement direction of the NTC module 2, and each NTC module 2 is connected to the second conductive film layer 41 through a fusible film layer 5.

[0030] Specifically, the first conductive film unit is designed as a single continuous conductive film layer, namely the first conductive film layer 31. Its function is to concentrate the current conduction and evenly distribute the external current to each NTC module 2. At the same time, it serves as an electrical access terminal to facilitate connection with external circuits. Each NTC module 2 is connected to the first conductive film layer 31 through an independent fuse film layer 5, providing independent fault protection for each NTC module 2. The second conductive film unit is also designed as a single continuous conductive film layer, namely the second conductive film layer 41. Its function is to collect the current of each NTC module 2 and conduct it to the external circuit, forming a complete conductive loop with the first conductive film layer 31. Each NTC module 2 is connected to the second conductive film layer 41 through an independent fuse film layer 5, further ensuring the independent protection of each NTC module 2. The above structure forms a complete parallel circuit, ensuring normal operation and fault protection of the devices.

[0031] This solution sets the first and second conductive film units as a single conductive film layer extending along the arrangement direction of the NTC module 2. The structure is simple and easy to manufacture, which can reduce the complexity of the process and the production cost. Each NTC module 2 is connected to the first and second conductive film units through an independent fusible film layer 5, realizing independent protection for a single NTC module 2. When a certain NTC module 2 fails, the corresponding fusible film layer 5 melts, isolating only that single NTC module 2, while the other NTC modules 2 can still work normally. The resistance change is small, and the overall functional stability of the device is high, making it suitable for scenarios with high requirements for resistance stability.

[0032] Option 2 refer to Figure 2 The first conductive film unit includes multiple first conductive film modules 32 arranged side by side along the arrangement direction of the NTC module 2. Adjacent first conductive film modules 32 are connected by a fusible film layer 5, and each first conductive film module 32 is correspondingly disposed on one side of an NTC module 2 and connected to the NTC module 2 through a fusible film layer 5. The second conductive film unit includes multiple second conductive film modules 42 arranged side by side along the arrangement direction of the NTC module 2. Adjacent second conductive film modules 42 are connected by a fusible film layer 5, and each second conductive film module 42 is correspondingly disposed on the other side of an NTC module 2 and connected to the NTC module 2 through a fusible film layer 5.

[0033] Specifically, each first conductive film module 32 and each second conductive film module 42 are configured one-to-one with an NTC module 2 and are respectively disposed on both sides of the corresponding NTC module 2 for conducting current to their corresponding NTC module 2, realizing segmented current conduction. Adjacent first conductive film modules 32 are connected by a fusible film layer 5. The fusible film layer 5 is used for graded protection. When an overvoltage or overcurrent occurs in a certain segment, it can be fused first to isolate the NTC module 2 group in that segment. Each first conductive film module 32 is disposed on one side of an NTC module 2 and is connected to the corresponding NTC module 2 through a fusible film layer 5. The core function of the fusible film layer 5 is to realize the conduction between a single NTC module 2 and the corresponding conductive film module, and at the same time, to fuse first when the NTC module 2 fails, forming a graded conductive structure that takes into account both single module protection and segmented protection, thereby improving the device's fault resistance capability.

[0034] Furthermore, the core function of each second conductive film module 42 is to export the current of the corresponding NTC module 2, realizing segmented current export, and forming a segmented conductive circuit in conjunction with the first conductive film module 32. Adjacent second conductive film modules 42 are connected by a fusible film layer 5. The core function of this fusible film layer 5 is to cooperate with the graded protection of the first conductive film unit to achieve bidirectional graded fusing. When a certain segment fails, the fusible film layer 5 at the corresponding position of the first conductive film unit fuses together to ensure complete isolation of the faulty segment. Each second conductive film module 42 is correspondingly set on the other side of an NTC module 2 and connected to the corresponding NTC module 2 through a fusible film layer 5. The core function of this fusible film layer 5 is to realize the conduction between a single NTC module 2 and the corresponding second conductive film module 42, and to fuse when the NTC module 2 fails. In conjunction with the graded structure of the first conductive film unit, a complete graded fusing circuit is formed, improving the reliability and effectiveness of graded protection.

[0035] A first connecting conductive film 33 is provided between the first conductive film module 32 at the front end and the first conductive film module 32 at the rear end, and a second connecting conductive film 43 is provided between the second conductive film module 42 at the front end and the second conductive film module 42 at the rear end. Its function is to form a complete current collection loop, ensuring that all first conductive film modules 32 can achieve current collection through the first connecting conductive film 33, and all second conductive film modules 42 can achieve current collection through the second connecting conductive film 43. This avoids problems such as poor current conduction and local current accumulation caused by segmented design. Simultaneously, it improves the overall structural integrity and enhances the stability of current conduction, ensuring that the NTC module 2 in the non-faulty section can conduct current normally through the connecting conductive film, further guaranteeing the reliability of the graded protection function and avoiding potential circuit breakage hazards caused by the segmented structure. Combined with the graded structure of the first conductive film unit, it forms a complete graded fusing circuit, improving the reliability and effectiveness of graded protection.

[0036] Compared to Scheme 1, this scheme has more fuse layers 5, meaning more fuse points and higher fuse sensitivity. When encountering instantaneous overvoltage or overcurrent, it can preferentially fuse the fuse layers 5 between adjacent first conductive film modules 32, segmenting and isolating the faulty NTC module 2 groups to prevent the fault from spreading rapidly. At the same time, the graded fuse design can achieve step-by-step protection according to the degree of fault, which is suitable for scenarios with high protection sensitivity requirements and improves the device's fault resistance.

[0037] In one embodiment, the protective layer 6 is either a glass encapsulation layer or a resin encapsulation layer; the insulating substrate 1 is a ceramic substrate; its core function is to achieve all-round encapsulation protection, isolate external moisture, dust, mechanical stress and other interference, prevent damage to the internal NTC unit and fuse layer 5, and at the same time improve the insulation performance of the device to ensure long-term stable operation of the device; the protective layer 6 completely covers the NTC unit and all fuse layers 5 to ensure comprehensive protection; the insulating substrate 1 is a ceramic substrate, and its core function is to serve as the bearing substrate of the entire device, supporting all functional structures, while utilizing the excellent insulation properties of ceramics to achieve electrical insulation between functional layers, avoid leakage and short circuits, and ensure the electrical safety of the device; and the ceramic substrate has good thermal conductivity, which can quickly conduct the heat generated during the operation of the NTC module 2, avoid local overheating, and further improve the working stability and service life of the device.

[0038] like Figures 2 to 8 As shown, the present invention also provides a specific embodiment of a method for preparing an NTC thermistor.

[0039] A method for fabricating an NTC thermistor, referenced Figures 2 to 6 The preparation method includes the following steps: S1. The powder of the mixture is prepared according to the NTC formula, and then formed into a ceramic block with NTC characteristics by grinding, drying, sieving, pressing and sintering. S2. Sputter a ceramic block with NTC characteristics onto an insulating substrate to form multiple NTC modules that are isolated from each other and arranged in the same direction on the insulating substrate. S3. Sputter a conductive film on an insulating substrate to form a first conductive film unit and a second conductive film unit on both sides of the NTC module, respectively. S4. Sputter a fusion-breaking metal film between each NTC module and the first conductive film unit, and between each NTC module and the second conductive film unit, to form multiple fusion-breaking film layers. S5. The NTC module and the fuse layer are encapsulated with glass or resin.

[0040] The first step is to prepare the NTC ceramic block: According to the preset NTC performance formula, the powder of the mixture is prepared. The powder is then processed by grinding, drying, sieving, pressing and molding, and high-temperature sintering to obtain a ceramic block with NTC characteristics. The ceramic block serves as the target material for subsequent sputtering of the NTC module, providing the material basis for the thermosensitive characteristics of the NTC module and ensuring that the NTC module can realize the functions of temperature sensing and resistance change.

[0041] The second step is to prepare the NTC module: The ceramic block with NTC properties is used as the target material and sputtered onto the insulating substrate to form an NTC thin film. Then, the NTC thin film is processed by masking or etching to divide it into multiple isolated NTC modules arranged in the same direction. The function of the NTC module is to act as an independent thermistor unit to realize the negative temperature coefficient thermistor function. The multiple isolated structures provide a basis for fault classification protection.

[0042] The third step is to prepare the first conductive film unit and the second conductive film unit: using a sputtering process, a conductive thin film is sputtered on an insulating substrate to form the first conductive film unit and the second conductive film unit on both sides of the NTC module. The function of the first conductive film unit is to introduce external current, and the function of the second conductive film unit is to discharge the current of the NTC module. The two work together to form a complete conductive circuit to ensure normal current conduction; ensure that the conductive film unit corresponds to the position of the NTC module to meet the electrical conduction requirements.

[0043] The fourth step is to prepare the fusible film layer: using a sputtering process, fusible metal films are sputtered between each NTC module and the first conductive film unit, and between each NTC module and the second conductive film unit, to form multiple independent fusible film layers. The function of the fusible film layer is to achieve fault protection. During normal operation, it conducts current, and during a fault, it prioritizes fusing and isolating the faulty module, ensuring that the fusible film layer achieves reliable electrical connection between the NTC module and the first conductive film unit, and between the NTC module and the second conductive film unit.

[0044] Step 5, encapsulation: Using glass or resin materials, the NTC module and all fusible film layers on the insulating substrate are encapsulated to form a protective layer. The function of the protective layer is to protect the internal functional structure and isolate external interference. After encapsulation, the NTC thermistor is obtained.

[0045] Among them, DC sputtering or RF sputtering can be selected according to the different material properties used in different NTC formulations.

[0046] This preparation method is based on mature sputtering, sintering, and encapsulation processes, making it easy to scale up production and reducing production difficulty and costs. The process involves grinding, drying, sieving, pressing, and sintering to prepare a ceramic block with NTC properties, ensuring uniform and stable performance and providing a high-quality target material for the subsequent sputtering of NTC modules. Sputtering the NTC ceramic block onto an insulating substrate to form an NTC module allows for precise control of the module's thickness and dimensions, ensuring stable thermosensitive performance. The use of sputtering technology to prepare conductive film units and fusible films ensures the bonding strength and conductivity reliability of each film layer. Finally, glass or resin encapsulation effectively protects the internal functional structure, improving the device's environmental adaptability and lifespan.

[0047] In one embodiment, reference Figure 7 and Figure 8 The preparation method also includes the following steps: S31. Sputter multiple conductive films on both sides of the NTC module to form multiple first conductive film modules arranged side by side along the arrangement direction of the NTC module on one side of the NTC module, and multiple second conductive film modules arranged side by side along the arrangement direction of the NTC module on the other side of the NTC module, and sputter fused metal films between two adjacent first conductive film modules and between two adjacent second conductive film modules.

[0048] This step is used to fabricate the NTC thermistor in Scheme 2 above. Multiple independent conductive films are sputtered on both sides of the NTC module. Through masking or etching processes, multiple first conductive film modules are formed on one side of the NTC module, arranged side by side along the NTC module's orientation. The function of the first conductive film modules is to conduct current in segments, providing current access to the corresponding NTC modules. On the other side of the NTC module, multiple second conductive film modules are formed, arranged side by side along the NTC module's orientation. The function of the second conductive film modules is to conduct current in segments, forming segmented conductive loops in conjunction with the first conductive film modules. A fusing metal film is sputtered between two adjacent first conductive film modules and between two adjacent second conductive film modules. The function of this fusing metal film is to achieve graded fusing protection, prioritizing fusing and isolating the faulty segment in case of a fault, thus completing the fabrication of the graded fusing structure.

[0049] S32. Sputter a solid conductive film extending along the arrangement direction of the NTC module on both sides of the NTC module to form a first conductive film layer and a second conductive film layer.

[0050] This step is used to fabricate the NTC thermistor in Scheme 1 above. A whole conductive film extending along the arrangement direction of the NTC module is sputtered on both sides of the NTC module to form a first conductive film layer and a second conductive film layer. The function of the first conductive film layer is to concentrate the current and distribute it to each NTC module. The function of the second conductive film layer is to concentrate and collect the current of each NTC module and lead it out, thus completing the preparation of the branch isolation structure and ensuring that each NTC module can be protected independently.

[0051] This embodiment utilizes two different fusing structures to adapt to various application requirements, enhancing the flexibility and adaptability of the fabrication method. The first embodiment can fabricate a graded fusing structure by sputtering multiple conductive film modules and fusing layers between them, achieving graded protection and meeting the needs of scenarios requiring high protection sensitivity. The second embodiment can fabricate a branch isolation structure by sputtering a single conductive film layer, simplifying the process steps, reducing production difficulty, and meeting the needs of scenarios requiring high resistance stability. Both embodiments are based on sputtering technology, are compatible with existing fabrication steps, require no additional complex equipment, and can be flexibly selected according to actual product needs, balancing production efficiency and product performance, further expanding the applicability of the fabrication method.

[0052] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. An NTC thermistor, characterized in that, include: Insulating substrate; An NTC unit includes multiple NTC modules, which are isolated from each other and arranged side by side on the insulating substrate in the same direction. The first conductive film unit is disposed on the insulating substrate and located on one side of the NTC unit; The second conductive film unit is disposed on the insulating substrate and located on the other side of the NTC unit; Multiple fuse layers are respectively disposed between each NTC module and the first conductive film unit, and between each NTC module and the second conductive film unit, to form a parallel circuit; A protective layer covers the NTC unit and the plurality of fuse layers; The melting point of the fusible film layer is lower than that of the first conductive film unit and the second conductive film unit.

2. The NTC thermistor according to claim 1, characterized in that, Both the first conductive film unit and the second conductive film unit include at least one underlay layer and at least one solder layer, and the underlay layer and the solder layer are stacked alternately.

3. The NTC thermistor according to claim 2, characterized in that, The underlayer is a nickel layer, and the welding layer is a silver layer.

4. The NTC thermistor according to any one of claims 1-3, characterized in that, The fusible film layer is an aluminum layer.

5. The NTC thermistor according to any one of claims 1-3, characterized in that, The first conductive film unit is a first conductive film layer extending along the arrangement direction of the NTC modules, and each NTC module is connected to the first conductive film layer through a fuse layer; the second conductive film unit is a second conductive film layer extending along the arrangement direction of the NTC modules, and each NTC module is connected to the second conductive film layer through a fuse layer.

6. The NTC thermistor according to any one of claims 1-3, characterized in that, The first conductive film unit includes a plurality of first conductive film modules arranged side by side along the arrangement direction of the NTC module. Adjacent first conductive film modules are connected by the fusible film layer, and each first conductive film module is correspondingly disposed on one side of an NTC module and connected to the NTC module through a fusible film layer.

7. The NTC thermistor according to any one of claims 1-3, characterized in that, The second conductive film unit includes a plurality of second conductive film modules arranged side by side along the arrangement direction of the NTC module. Adjacent second conductive film modules are connected by the fusible film layer, and each second conductive film module is correspondingly arranged on the other side of the NTC module and connected to the NTC module through the fusible film layer.

8. The NTC thermistor according to claim 1, characterized in that, The protective layer is either a glass encapsulation layer or a resin encapsulation layer; the insulating substrate is a ceramic substrate.

9. A method for preparing an NTC thermistor, characterized in that, Includes the following steps: The powder of the mixture is prepared according to the NTC formula, and then formed into a ceramic block with NTC properties through grinding, drying, sieving, pressing and sintering. A ceramic block with NTC properties is sputtered onto an insulating substrate to form multiple NTC modules that are isolated from each other and arranged in the same direction on the insulating substrate. A conductive film is sputtered on an insulating substrate to form a first conductive film unit and a second conductive film unit on both sides of the NTC module, respectively. A fusion-breaking metal film is sputtered between each NTC module and the first conductive film unit, and between each NTC module and the second conductive film unit, to form multiple fusion-breaking film layers. The NTC module and the fuse layer are encapsulated with glass or resin.

10. The NTC thermistor according to claim 9, characterized in that, It also includes the following steps: Multiple conductive films are sputtered on both sides of the NTC module to form multiple first conductive film modules arranged side by side along the NTC module's arrangement direction on one side of the NTC module, and multiple second conductive film modules arranged side by side along the NTC module's arrangement direction on the other side of the NTC module. A fusion-breaking metal film is sputtered between two adjacent first conductive film modules and between two adjacent second conductive film modules. Alternatively, a single conductive film extending along the arrangement direction of the NTC module can be sputtered onto both sides of the NTC module to form a first conductive film layer and a second conductive film layer.

Images