Production method and production line of ceramic base glass-sealed NTC thermistor

Abstract

The application discloses a production method and a production line of a ceramic base glass-sealed NTC thermistor, and the method comprises the following steps: placing multiple groups of Dumet wire leads at equal intervals on a wire arranging jig; installing a ceramic base; coating conductive paste; embedding a chip to form a wire-chip preform; after drying, loading into a sintering tool, sleeving a glass sealing tube, and cooperating with a positioning groove to perform radial guidance and coaxial positioning; after high-temperature sintering, the glass and the ceramic base are fused and mutually fused; and finally, pickling and drying to obtain a finished product. The production line is provided with a wire arranging device, a ceramic base assembling device, a coating device, a chip assembling device, a drying device, a glass sealing tube assembling device, a sintering device and a pickling and drying device. Through the cooperative action of the wire arranging jig and the sintering tool, the ceramic base and the glass-sealed NTC thermistor are precisely and efficiently combined, the consistency of product production is effectively improved, and the demand for large-scale mass production is met.

Description

Technical Field

[0001] This invention belongs to the field of thermistor manufacturing technology, and relates to the preparation of NTC thermistors, specifically to a method and production line for producing a ceramic-base glass-sealed NTC thermistor. Background Technology

[0002] Traditional single-ended glass-encapsulated NTC thermistors typically involve soldering an NTC thermistor chip to two Dumme wires, encasing it in a glass tube, and then melting the glass tube at high temperature to encapsulate the chip and the base of the leads, creating a glass-encapsulated NTC thermistor with radial leads. This product has low structural strength at the lead-glass interface, making it susceptible to micro-cracks or even breakage from vibration, tension, and other external forces, leading to airtightness failure. If moisture intrusion occurs and silver paste is used for the electrodes, it can easily cause silver ion migration, resulting in signal drift or failure. Furthermore, the small size and thin, flexible leads make the glass encapsulation the only feasible clamping point during subsequent sensor fabrication or assembly. However, the glass encapsulation itself is brittle and easily damaged by external impacts or improper clamping force.

[0003] To address the aforementioned issues, existing technologies attempt to add a ceramic base to the bottom of the glass package to improve structural strength and insulation performance, as well as provide a clamping reference for subsequent production. However, this only addresses the product structure level and lacks a supporting streamlined production process. Furthermore, the addition of a ceramic base places higher demands on assembly precision and sintering positioning. Traditional assembly methods rely heavily on manual or semi-automatic assembly, which suffers from difficulties in positioning and poor airtightness between the ceramic and glass. This makes it difficult to achieve precise alignment between the ceramic base and the leads and chips, easily leading to defects such as ceramic base misalignment and poor glass-ceramic coaxiality, making it difficult to meet the high yield and high consistency requirements of mass production. More importantly, existing processes cannot fully fuse the glass and ceramic base, resulting in low bonding strength. Therefore, to meet the requirements, there is an urgent need for a production process that can adapt to glass-encapsulated NTC thermistors and ceramic bases. Summary of the Invention

[0004] To address the aforementioned problems, the main objective of this invention is to design a production method and production line for ceramic-based glass-sealed NTC thermistors. This solves the problems of poor product consistency and inability to achieve precise alignment between the ceramic base and leads / chips using traditional manual or semi-automatic methods, as well as the problem of low bonding strength caused by insufficient melting of the glass and ceramic base.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for manufacturing a ceramic-base glass-sealed NTC thermistor, wherein the ceramic base used in this method has a porous structure, the pores of which are filled with molten glass, and the distance between the two lead vias of the ceramic base is less than the thickness of the NTC thermistor chip; specifically, the manufacturing method includes the following steps: S1. Place multiple sets of Dumex wires at equal intervals on the wiring fixture, with two Dumex wires in each set. S2. Spread one end of each set of Dumex wires open and install the ceramic base. The two Dumex wires are aligned and extend out of the ceramic base. S3. The tip of the Dumex wire extending from the ceramic base is coated with conductive paste; S4. Open up the head of each group of Dumex leads again, and insert an NTC thermistor chip between the two Dumex leads to form a lead-chip preform. S5. The lead-chip preform enters the heating equipment along with the wiring fixture to dry the conductive paste and form a semi-finished product. S6. Transfer the semi-finished product in the cabling fixture to the sintering fixture, perform radial positioning of the Dumex wire and the ceramic base, and put a glass encapsulation tube on the outside of each NTC thermistor chip. S7. The sintering fixture is fed into the sintering furnace. High-temperature sintering melts the glass encapsulation tube, wraps the lead wire-chip, and fills the pores of the ceramic base. After cooling, a molten and integrated product is formed and then annealed. S8. After annealing the fused and integrated product, pickle the Dumex wire lead, wash with pure water, and then dry to obtain the finished product.

[0006] To complement the above production method, the wiring fixture is described in detail. As a further description of the invention, in step S1, the wiring fixture is a long strip structure, its width being less than the length of the Dumex wire lead, and multiple sets of equally spaced double-line slots for placing the Dumex wire leads are formed along its length. Furthermore, the double-line slots are configured with equal width, and two parallel Dumex wires are placed in each double-line slot.

[0007] As a further description of the present invention, in step S2, one end of each group of Dumex wires is opened up, and the distance between the two Dumex wires after opening up is consistent with the distance between the wire through holes of the ceramic base, and they are inserted into the wire through holes of the ceramic base accordingly; in step S4, the ends of each group of Dumex wires are opened up again, and the distance between the two Dumex wires after opening up is consistent with the thickness of the NTC thermistor chip, and the opened Dumex wires are released after the NTC thermistor chip is inserted.

[0008] As a further description of the present invention, in step S6, the lead-chip semi-finished product on the cable fixture is transferred to a high-temperature sintering fixture, where a positioning groove is used to assemble and limit the glass encapsulation tube. Furthermore, the sintering fixture is made of graphite and includes a positioning groove adapted to the outer contour of the ceramic base. The inner wall of the positioning groove has a stepped structure to support the ceramic base. The glass encapsulation tube is then embedded in the positioning groove, positioned outside the NTC thermistor chip. The positioning groove provides radial guidance for the glass encapsulation tube, ensuring that the ceramic base and the glass encapsulation tube are coaxial.

[0009] As a further description of the present invention, in step S7, the sintering furnace is set as a nitrogen furnace, which heats up to 650 ℃~800 ℃ at a heating rate of 80~100 ℃ / min, holds at that temperature for 3~5 min, so that the glass encapsulation tube and the ceramic base can be fused together at high temperature; the furnace is then cooled down to 550 ℃ at a cooling rate of 60~80 ℃ / min, and then naturally cooled to room temperature.

[0010] As a further description of the present invention, in step S8, the molten and integrated product enters a nitrogen-protected annealing furnace, is heated to 400 ℃~500 ℃ at a heating rate of 15~20 ℃ / min, held at that temperature for 30~60 min, and then cooled to room temperature in the furnace at a rate of 30~60 ℃ / min to eliminate mechanical stress.

[0011] A production line for a ceramic-base glass-sealed NTC thermistor includes: The wire feeding device is used to simultaneously feed and cut two Dummie wires and place them into the double wire groove of the wire laying fixture. The ceramic base assembly device is used to open the heads of the two Dumex wires in each set of double wire slots, grasp the ceramic base to align the wire through holes with the Dumex wires, and install them. A coating device for coating conductive paste onto the tip of the Dumex wire extending from the ceramic base; The chip assembly device is used to open up the head of each set of Dummes leads again, pick up the NTC thermistor chip and place it between two Dummes leads. Drying device for drying the conductive paste coated on the Dumex wire leads; A glass encapsulation tube assembly device is used to mount a glass encapsulation tube on the outside of an NTC thermistor chip, with the glass encapsulation tube fitting against the upper surface of a ceramic base. The sintering apparatus is used to melt the glass encapsulation tube at high temperature, wrap the lead-chip and fill the pores of the ceramic base to form a molten and integrated product and then anneal it. The pickling and drying equipment is used to pickle the Dumex wire leads of the molten and integrated product, and then clean and dry them to obtain the finished product.

[0012] As a further description of the present invention, the ceramic base assembly device and the chip assembly device include a spreading mechanism, a visual positioning system and a gripper; the spreading mechanism is used to spread the Dumex wire head to a preset distance, and the gripper, in conjunction with the visual positioning system, is used for alignment and assembly during the assembly process.

[0013] As a further description of the present invention, the glass encapsulation tube assembly device includes a vision positioning system and a robot arm; the robot arm, in conjunction with the vision positioning system, is used to transfer the semi-finished product of the wiring fixture into the sintering fixture, and to grasp the glass encapsulation tube and embed it into the positioning groove of the sintering fixture, thereby realizing the assembly of the glass encapsulation tube.

[0014] Compared with the prior art, the technical advantages of the present invention are as follows: This invention provides a method and production line for manufacturing ceramic-base glass-encapsulated NTC thermistors, including an automated production method and an automated production line. By introducing a wiring fixture and sintering tooling, high-precision production is achieved throughout the entire process, from laying out the Dummell wire leads, assembling the ceramic base and NTC thermistor chip, to assembling the glass encapsulation tube. The double-groove structure of the wiring fixture ensures the parallelism of the Dummell wire leads; the stepped structure and positioning grooves of the sintering tooling provide support for the ceramic base, assembly of the glass encapsulation tube, and radial guidance. Combined with high-temperature sintering in a sintering furnace, the glass encapsulation tube melts and encapsulates the leads-chip, filling the pores of the ceramic base to form a fused, integrated product, significantly improving the product's structural strength, insulation, moisture resistance, and long-term reliability.

[0015] The production line for ceramic-base glass-sealed NTC thermistors of this invention is configured sequentially with a wire feeding device, a ceramic base assembly device, a coating device, a chip assembly device, a drying device, a glass encapsulation tube assembly device, a sintering device, and an acid washing and drying device. It not only realizes the large-scale and stable production of ceramic-base glass-sealed NTC thermistors, but also significantly reduces the quality fluctuations caused by human intervention, ensuring the stability and consistency of the product in harsh environments such as high temperature and humidity. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the production method of the present invention; Figure 2 This is a structural view of the ceramic base used in this invention; Figure 3 This is a structural view of the cabling fixture used in this invention; Figure 4 This is a structural view of the cable tray of the present invention for placing the Dumex wire lead; Figure 5 This is a structural view of the sintering fixture of the present invention; Figure 6 This is a structural view of the sintering fixture of the present invention in conjunction with the lead-chip preform and the glass encapsulation tube; Figure 7 This is a layout diagram of the various devices in the production line of the present invention. Figure 8 This is a structural view of the opening mechanism of the present invention in conjunction with the Dumex wire; Figure 9 This is a schematic diagram illustrating the performance data of the product prepared according to the present invention.

[0017] In the diagram, A. ceramic base, A1. lead wire through hole, A2. fused groove, A3. mesh pattern, B. NTC thermistor chip, C. Dummex wire, D. glass encapsulation tube; 1. Cable routing fixture, 2. Double cable groove, 3. Sintering fixture, 31. Support platform, 32. Positioning groove, 33. Step structure, 4. Spreading mechanism, 41. U-shaped plate, 42. Adsorption hole, 43. Air pipe, 44. V-shaped groove. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings: In one embodiment of the present invention, a method for producing a ceramic-base glass-sealed NTC thermistor is disclosed. The ceramic base A used in this method has a porous structure, with its pores filled by molten glass. Furthermore, the distance between the two lead through-holes A1 of the ceramic base A is less than the thickness of the NTC thermistor chip B (the thickness of a conventional chip is 0.35-0.45 mm). Figure 2 As shown, the upper surface of the ceramic base A includes a molten groove A2 and an annular mesh pattern A3. The mesh pattern A3 forms a porous ceramic base A, which, after sintering, allows the glass to be seamlessly connected to the ceramic base A.

[0019] Specifically, such as Figure 1 As shown, the method includes the following steps: S1. Place multiple sets of Dumex wires at equal intervals on the wiring fixture, with two Dumex wires in each set. S2. Spread one end of each set of Dumex wires open and install the ceramic base. The two Dumex wires are aligned and extend out of the ceramic base. S3. The tip of the Dumex wire extending from the ceramic base is coated with conductive paste; S4. Open up the head of each group of Dumex leads again, and insert an NTC thermistor chip between the two Dumex leads to form a lead-chip preform. S5. The lead-chip preform enters the heating equipment along with the wiring fixture to dry the conductive paste and form a semi-finished product. S6. Transfer the semi-finished product in the cabling fixture to the sintering fixture, perform radial positioning of the Dumex wire and the ceramic base, and put a glass encapsulation tube on the outside of each NTC thermistor chip. S7. The sintering fixture is fed into the sintering furnace. High-temperature sintering melts the glass encapsulation tube, wraps the lead wire-chip, and fills the pores of the ceramic base. After cooling, a molten and integrated product is formed and then annealed. S8. After annealing the fused and integrated product, pickle the Dumex wire lead, wash with pure water, and then dry to obtain the finished product.

[0020] In this embodiment, in step S1, the above-mentioned cable tray 1 is a long strip structure, the width of which is less than the length of the Dumex wire C, and 60 sets of equally spaced double wire grooves 2 are formed along its length to place the Dumex wire. The spacing between adjacent double wire grooves 2 is set to 4-10 mm. Figure 3 As shown. In use, two Dumex wires C are placed into a double-wire slot 2, with their heads extending beyond the slot body. This provides the necessary conditions for the subsequent unfolding of the Dumex wires C, the assembly of the ceramic base A, and the insertion of the NTC thermistor chip B, as follows. Figure 4 As shown. Specifically, the double-slot 2 is designed with a uniform width of 0.75~0.85 mm to precisely position the Dumesh wire lead C, accommodating Dumesh wire leads C with a diameter of 0.3~0.35 mm. The tension of the Dumesh wire lead C is controlled at 0.5±0.1 N. After being placed in the double-slot 2, the parallelism error is ≤0.02 mm, ensuring that the lead wire is free from stretching, twisting, and crossing, laying the foundation for subsequent processes.

[0021] In this embodiment, in step S2, one end of each set of Dumex wires C is spread open, and the distance between the heads of the two Dumex wires C after spreading is consistent with the distance between the lead through holes A1 of the ceramic base A, and they are inserted into the lead through holes A1 of the ceramic base A accordingly. Specifically, in this embodiment, the Dumex wires C are spread open and supplied to the ceramic base A through a vibratory feeder direct vibration orientation device. The spread Dumex wires C are then aligned with the lead through holes A1 for installation. It should be noted that after the ceramic base A is installed, the spread Dumex wires C are released, and the Dumex wires C recover inward due to their own toughness; and the thickness of the conventionally sized NTC thermistor chip B is greater than the distance between the lead through holes A1. Therefore, when inserting the NTC thermistor chip B, the Dumex wires C need to be spread open again.

[0022] In this embodiment, in step S3, conductive paste is selected according to the actual use environment of the product; conductive silver paste is applied under normal working conditions of 250 ℃ and below, and conductive gold paste is applied under high-temperature working conditions of 350 ℃ and above. The coating area is 0.5 mm, the thickness is 5±1 μm, and the amount of paste applied at a single point is 0.005±0.001 mL. There is no overflow or missed coating, which ensures the conductivity and stability of the electrode under the corresponding temperature conditions.

[0023] In this embodiment, in step S4, one end of each set of Dumex wires C is spread open again. After spreading, the distance between the heads of the two Dumex wires C is consistent with the thickness of the NTC thermistor chip B. This, combined with the vibratory feeder, enables the directional feeding of the NTC thermistor chip B. The NTC thermistor chip B is then vertically inserted between the two Dumex wires C. After insertion, the Dumex wires C are released and clamped onto the electrode surfaces on both sides of the NTC thermistor chip B for initial positioning.

[0024] In this embodiment, in step S5, the heating device is a high-frequency induction heating device. The entire row of 60 products is heated and dried synchronously with the cable fixture 1. The drying temperature is 220±5 ℃, the heating time is 5 s, and the temperature uniformity error is ≤3 ℃, so as to achieve firm curing of conductive paste and fixation of NTC thermistor chip B.

[0025] In this embodiment, in step S6, the sintering fixture 3 is a 60-position glass-ceramic sintering high-temperature resistant sintering fixture made of graphite material, which has the characteristics of high temperature resistance, good thermal conductivity, and strong thermal shock resistance in a nitrogen protective atmosphere. Figure 5 As shown, the bottom of the sintering fixture 3 is provided with a support platform 31 to support the bottom of the Dumex wire C and define the relative position of the ceramic base A and the NTC thermistor chip B. The top of the sintering fixture 3 has a positioning groove 32 that matches the outer contour of the ceramic base A. The clearance between the positioning groove 32 and the glass encapsulation tube D is 0.02~0.05 mm, forming a clearance fit, which can provide radial guidance for the glass encapsulation tube D, keeping it coaxial with the ceramic base A. The inner wall of the positioning groove 32 has a stepped structure 33 to support the lower end face of the ceramic base A. Figure 6 As shown, during assembly, the bottom of the Dumex lead C stands upright on the support platform 31, the ceramic base A is placed in the positioning groove 32 and supported by the stepped structure 33, and then the glass encapsulation tube D is inserted. The positioning groove 32 limits its radial movement to ensure that the glass encapsulation tube D is not tilted or loose, thus ensuring the bonding accuracy of subsequent high-temperature sintering.

[0026] In this embodiment, in step S7, the sintering fixture 3 containing the glass encapsulation tube D and the semi-finished product is fed into a continuous nitrogen-protected sintering furnace. The sintering furnace heats the temperature to 650°C-800°C at a rate of 80-100°C / min and holds it for 3-5 minutes, allowing the glass encapsulation tube D and the ceramic base A to fuse together at a high temperature. The temperature is then reduced to 550°C at a rate of 60-80°C / min, and then allowed to cool naturally to room temperature. During the sintering process, the high thermal conductivity of graphite material ensures uniform heat absorption, guaranteeing that the ceramic base A and the glass encapsulation tube D are coaxial and without misalignment. The molten glass encapsulates the lead-chip and forms a fused-to-metal structure with the ceramic base A. This fused-to-metal bonding method significantly improves the structural strength of the glass-lead junction, achieving vibration and tensile strength resistance, and fundamentally preventing encapsulation failure. Furthermore, the fused and integrated product enters a nitrogen-protected annealing furnace, where it is heated to 400℃~500℃ at a heating rate of 15~20℃ / min, held at that temperature for 30~60 min, and then cooled to room temperature in the furnace at a rate of 30~60℃ / min to eliminate mechanical stress, ensure that the glass encapsulation is free of internal stress, and avoid glass cracking due to thermal stress during later use.

[0027] In this embodiment, in step S8, the Dumel wire lead C is immersed in an acid pickling solution at a temperature of 25±2 ℃ for 5~10 min to remove the sintered borate coating and trace oxide layer remaining on the Dumel wire lead C. After rinsing with three levels of pure water, it is dried in a hot air drying oven at 40~60 ℃ for 30 min, with a pure water resistivity of 18.2 MΩ·cm. This ensures that the product is free of residue and corrosion, guaranteeing the conductivity of the Dumel wire lead C.

[0028] After the above process, a ceramic-base glass-sealed NTC thermistor is obtained. Further, the product undergoes a full-appearance inspection using a fully automated 4K ultra-high-definition visual inspection system with an accuracy of ±0.005 mm, eliminating defective products and ensuring the integrity of the product's appearance and structure. The resistance value is then measured in a high-precision constant-temperature oil bath at 25±0.01 ℃ with an accuracy of ±0.1%, ensuring the consistency of the product's resistance value. Defective products include, but are not limited to: NTC thermistor chip misalignment angle >45°, NTC thermistor chip defects, chipping or cracks, impurities, bubbles, or cracks in the glass encapsulation tube, chipped or broken ceramic base, and cracked or poorly sealed glass-ceramic fusion interface.

[0029] In this embodiment, the specific production process also includes, according to actual needs, applying polyimide solution at the contact point between the ceramic base A and the Dumex wire C, with a coating amount of 0.01±0.002 mL and a coating area of ​​1.5±0.2 mm; or, fitting an insulating sleeve over the outside of the Dumex wire C and applying polyimide solution at the contact point between the insulating sleeve and the ceramic base, followed by curing in a vacuum oven. After curing, the adhesion of the insulating sleeve is ≥0.1 N, with no peeling or displacement. The use of polyimide solution and insulating sleeve enhances the product's moisture-proof and water-resistant properties, improving product safety standards. After re-inspection, the product completes the warehousing process.

[0030] In another embodiment of the present invention, a production line for a ceramic-base glass-sealed NTC thermistor is disclosed, such as... Figure 7 As shown, it includes a wire feeding device, a ceramic base assembly device, a coating device, a chip assembly device, a drying device, a glass encapsulation tube assembly device, a sintering device, and an acid pickling and drying device. Specifically: The wire feeding device adopts a dual-wire synchronous feeding method, which is used to simultaneously feed and cut two Dumme wires and place them into the dual-wire groove of the wire laying fixture.

[0031] The ceramic base assembly device includes a spreading mechanism, a vision positioning system, and grippers. These grippers are used to spread the heads of the two Dumex wires in each set of double-grooved slots, grasp the ceramic base of the vibratory feeder's direct vibration orientation device, align the wire through-holes with the Dumex wires, and install them. Specifically, in this embodiment, the spreading mechanism spreads the Dumex wire heads to a preset distance, and the grippers, in conjunction with the vision positioning system, achieve alignment and installation during the assembly process. Figure 8 As shown, the opening mechanism 4 is a U-shaped symmetrical vacuum adsorption structure, including a U-shaped plate 41 and adsorption holes 42 symmetrically arranged on both inner sides of the U-shaped plate 41. The adsorption holes 42 are connected to the air pump through an air pipe 43, and a V-shaped groove 44 is opened at the position of the adsorption hole 42 to accommodate the Dumex wire C. The width of the U-shaped plate 41 is adapted to the width of the double wire groove 2. It is placed outside the two Dumex wires C. After air is introduced, the adsorption holes 42 generate a bidirectional adsorption force to open the Dumex wire C. After the air is cut off, there is no external force, and the Dumex wire C returns to its original position only by its own elasticity. It achieves vacuum adsorption only by the air supply and cut-off, without any other mechanical structure, thus avoiding damage to the Dumex wires. The gripper can achieve 360° angle adjustment, and its gripping surface includes a flexible gripping part made of anti-static soft rubber material. The gripping force is 0.2±0.05 N. It works with the vision positioning system to complete the orientation gripping, angle adjustment and assembly of the ceramic base. The positioning accuracy of the visual positioning system is ±0.01 mm, ensuring that the lead wire through hole of the ceramic base is precisely aligned with the two Dumex wires after they are spread out.

[0032] The coating device is used to coat the Dumex wire tip that extends out of the ceramic base with conductive paste. The conductive paste includes, but is not limited to, silver paste and gold paste, and the specific type can be selected according to the actual application scenario of the product.

[0033] The chip assembly device includes a spreading mechanism, a vision positioning system, and grippers, used to spread the heads of each set of Dumme wires again, placing the NTC thermistor chip between two Dumme wires. Specifically, in this embodiment, the spreading mechanism spreads the heads of the Dumme wires again to a preset distance, and the grippers, in conjunction with the vision positioning system, complete the orientation gripping, angle adjustment, and precise installation of the NTC thermistor chip. Its spreading mechanism and grippers are consistent with the structural configuration of the ceramic base assembly device described above.

[0034] The drying device is configured as a high-frequency induction heating device, used to dry the conductive paste coated on the Dumex wire leads.

[0035] The glass encapsulation tube assembly device includes a vision positioning system and a robotic arm, combined with a high-temperature sintering fixture, for mounting glass encapsulation tubes onto the outside of NTC thermistor chips. The glass encapsulation tubes are attached to a ceramic base. Specifically, the robotic arm, in conjunction with the vision positioning system, picks up the semi-finished product from the cable fixture and transfers it into the positioning groove of the sintering fixture. The robot is then limited by a stepped structure, and finally picks up the glass encapsulation tube and embeds it into the positioning groove of the sintering fixture, thus achieving the guided mounting of the glass encapsulation tube.

[0036] The sintering apparatus, including a continuous nitrogen-protected sintering furnace and a nitrogen-protected annealing furnace, is used to melt the glass encapsulation tube at high temperature, wrap the lead-chip and fill the pores of the ceramic base to form a molten and integrated product and then anneal it.

[0037] The pickling and drying device includes a pickling tank, a cleaning tank, and a drying tank. It is used to pickle the Dumex wire leads of the molten and integrated product, and then clean and dry them to obtain the finished product. Specifically, the ceramic base is held by a clamp, the Dumex wire leads are exposed and immersed in the pickling solution of the pickling tank, and after pickling, they are placed in the cleaning tank for three-stage pure water cleaning, and then dried in the drying tank to obtain the finished product.

[0038] Based on the above embodiments, by adding a ceramic base to a conventional single-ended glass-sealed thermistor and combining it with fully automated production, the structural strength of the junction between the glass package and the Dummell wire leads can be significantly enhanced. This thermistor possesses excellent vibration resistance, tensile strength, temperature shock resistance, and insulation and moisture-proof properties, and is suitable for automated packaging. This significantly improves the reliability and lifespan of the product and temperature sensors manufactured using it as a core component. Furthermore, the addition of the ceramic base provides a clamping reference for subsequent sensor fabrication or assembly processes, facilitating automated operation and preventing product failures caused by clamping the glass package.

[0039] To verify the performance of the products prepared by the above-described production method and production line of the present invention, the following reliability verification was conducted, and the results are shown below: 1. Temperature shock test: Temperature -55℃~250℃, holding time 30 min, switching time ≤10 s, 100 shock cycles; after the test, the sample has no appearance defects such as cracks or peeling, and the resistance change rate is ≤±2.0%; 2. Lead wire tensile test: With the resistor terminals fixed, the two radially parallel leads are separated to 180° and a tensile force of ≥5 N is applied for 10 s. The leads should not be loose or broken, and the sample should be free of cracks or other defects. The resistance change rate should be ≤±2.0%. 3. Steady-state damp heat test: temperature 40±2 ℃, humidity 93±2% RH, for 1000 h; resistance change rate after test ≤±2.0%; 4. Vibration test: Frequency range 10~500 Hz, amplitude 0.75 mm or acceleration 98 m / s². 2 The test was conducted vertically for 2 hours, with a recovery time of 2 hours, for a total of 1000 hours; the resistance change rate after the test was ≤ ±2.0%. 5. Collision test: Acceleration 250 m / s² 2 The pulse duration was 6 ms, the direction was upright, the number of collisions was 4000, and the recovery time was 2 h; the resistance change rate after the test was ≤ ±2.0%. 6. High-temperature aging test: temperature 250 ℃, time 1000 h; resistance change rate after test ≤ ±2.0%.

[0040] After the above tests, all samples showed no visible damage (under a 20x optical microscope), and their electrical performance met the above specifications.

[0041] like Figure 9 As shown, products that meet the resistance change rate requirement of ≤±2.0% after lead wire tensile testing are selected, and the resistance value of the product after tensile testing is used as the resistance value before testing for steady-state damp heat testing. The data shows that the resistance change rate |(R2-R1) / R1|≤2.0% indicates that the product can prevent silver ion migration caused by moisture penetration under harsh environments, demonstrating excellent anti-permeability and insulation retention capabilities.

[0042] The above content discloses the manufacturing process of the ceramic base glass-sealed NTC thermistor of the present invention. Compared with the prior art, the present invention has the following advantages: 1. This invention, by first installing the ceramic base and then assembling the NTC thermistor chip, combined with the radial limiting and coaxial guiding effect of the sintering fixture, enables the glass encapsulation tube and the ceramic base to form a stable molten and interwoven bond after high-temperature sintering. This significantly enhances the structural strength of the glass-lead joint, effectively resists external forces such as vibration and tension, avoids the generation of microcracks, prevents moisture intrusion and silver ion migration, and significantly improves the long-term reliability of the product in humid environments. 2. This invention adopts a double-groove structure of a wiring fixture to achieve equidistant and equal-height arrangement of Dumex wires. Through a vision positioning system and tooling fixture, it achieves precise alignment of processes such as ceramic base installation, NTC thermistor chip insertion, and glass encapsulation tube assembly, solving problems such as low positioning accuracy, ceramic base misalignment, and poor glass-ceramic coaxiality in traditional processes, thereby improving product consistency and pass rate. 3. This invention connects the processes of wire laying, assembly, slurry coating, sintering, and post-processing in an orderly manner, realizing multi-station synchronous and precise operation, greatly improving production efficiency, reducing human operation errors, and enabling the product to have good mass production capability and cost advantages, which can meet the needs of high-end applications for large-volume, high-reliability products.

[0043] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the direction and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A method for producing a ceramic-base glass-sealed NTC thermistor, characterized in that, The ceramic base used in this manufacturing method has a porous structure, with its pores filled by molten glass, and the distance between the two lead vias of the ceramic base is less than the thickness of the NTC thermistor chip; specifically, the manufacturing method includes the following steps: S1. Place multiple sets of Dumex wires at equal intervals on the wiring fixture, with two Dumex wires in each set. S2. Spread one end of each set of Dumex wires open and install the ceramic base. The two Dumex wires are aligned and extend out of the ceramic base. S3. The tip of the Dumex wire extending from the ceramic base is coated with conductive paste; S4. Open up the head of each group of Dumex leads again, and insert an NTC thermistor chip between the two Dumex leads to form a lead-chip preform. S5. The lead-chip preform enters the heating equipment along with the wiring fixture to dry the conductive paste and form a semi-finished product. S6. Transfer the semi-finished product in the cabling fixture to the sintering fixture, perform radial positioning of the Dumex wire and the ceramic base, and put a glass encapsulation tube on the outside of each NTC thermistor chip. S7. The sintering fixture is fed into the sintering furnace. High-temperature sintering melts the glass encapsulation tube, wraps the lead wire-chip, and fills the pores of the ceramic base. After cooling, a molten and integrated product is formed and then annealed. S8. After annealing the fused and integrated product, pickle the Dumex wire lead, and then dry it after washing with pure water to obtain the finished product.

2. The method for producing a ceramic-base glass-sealed NTC thermistor according to claim 1, characterized in that: In step S1, the wiring fixture is a long strip structure with a width smaller than the length of the Dumex wire lead, and multiple sets of equally spaced double wire grooves are opened along its length direction for placing the Dumex wire lead.

3. The method for producing a ceramic-base glass-sealed NTC thermistor according to claim 2, characterized in that: The double slots are configured with equal width, and two parallel Dumex wires are placed in each double slot.

4. The method for producing a ceramic-base glass-sealed NTC thermistor according to claim 1, characterized in that: In step S2, one end of each set of Dumex wires is opened up. After opening, the distance between the ends of the two Dumex wires is consistent with the distance between the wire through holes of the ceramic base, and they are inserted into the wire through holes of the ceramic base accordingly. In step S4, the heads of each set of Dumex wires are opened again. After opening, the distance between the heads of the two Dumex wires is consistent with the thickness of the NTC thermistor chip. After inserting the NTC thermistor chip, the opened Dumex wires are released.

5. The method for producing a ceramic-base glass-sealed NTC thermistor according to claim 1, characterized in that: In step S6, the sintering fixture is made of graphite and includes a positioning groove that matches the outer contour of the ceramic base. The inner wall of the positioning groove is provided with a stepped structure to support the ceramic base. A glass encapsulation tube is embedded in the positioning groove. The glass encapsulation tube is fitted outside the NTC thermistor chip. The positioning groove provides radial guidance for the glass encapsulation tube, making the ceramic base and the glass encapsulation tube coaxial.

6. The method for producing a ceramic-base glass-sealed NTC thermistor according to claim 1, characterized in that: In step S7, the sintering furnace is set as a nitrogen furnace, which heats up to 650 ℃~800 ℃ at a heating rate of 80~100 ℃ / min and holds for 3~5 min to allow the glass encapsulation tube and the ceramic base to melt and fuse at high temperature; the furnace is then cooled down to 550 ℃ at a cooling rate of 60~80 ℃ / min and then naturally cooled to room temperature.

7. The method for producing a ceramic-base glass-sealed NTC thermistor according to claim 1, characterized in that: In step S8, the molten and integrated product enters a nitrogen-protected annealing furnace, where it is heated to 400℃~500℃ at a heating rate of 15~20℃ / min, held at that temperature for 30~60 min, and then cooled to room temperature in the furnace at a rate of 30~60℃ / min to eliminate mechanical stress.

8. A production line for a ceramic-base glass-sealed NTC thermistor, characterized in that, include: The wire feeding device is used to simultaneously feed and cut two Dummie wires and place them into the double wire groove of the wire laying fixture. The ceramic base assembly device is used to open the heads of the two Dumex wires in each set of double wire slots, grasp the ceramic base to align the wire through holes with the Dumex wires, and install them. A coating device for coating conductive paste onto the tip of the Dumex wire extending from the ceramic base; The chip assembly device is used to open up the head of each set of Dummes leads again, pick up the NTC thermistor chip and place it between two Dummes leads. Drying device for drying the conductive paste coated on the Dumex wire leads; A glass encapsulation tube assembly device is used to mount a glass encapsulation tube on the outside of an NTC thermistor chip, with the glass encapsulation tube fitting against the upper surface of a ceramic base. The sintering apparatus is used to melt the glass encapsulation tube at high temperature, wrap the lead-chip and fill the pores of the ceramic base to form a molten and integrated product and then anneal it. The pickling and drying equipment is used to pickle the Dumex wire leads of the molten and integrated product, and then clean and dry them to obtain the finished product.

9. The production line for a ceramic-base glass-sealed NTC thermistor according to claim 8, characterized in that: The ceramic base assembly device and the chip assembly device include a spreading mechanism, a visual positioning system, and grippers; the spreading mechanism is used to spread the Dumex wire head to a preset distance, and the grippers, in conjunction with the visual positioning system, are used for alignment and assembly during the assembly process.

10. A production line for a ceramic-base glass-sealed NTC thermistor according to claim 8, characterized in that: The glass encapsulation tube assembly device includes a vision positioning system and a robot arm; the robot arm, in conjunction with the vision positioning system, is used to transfer the semi-finished product of the wiring fixture into the sintering fixture, and to grasp the glass encapsulation tube and embed it into the positioning groove of the sintering fixture, thereby realizing the assembly of the glass encapsulation tube.

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