A high-density, high-adhesion gold electrode paste for NTC thermistors, its preparation method and application

Abstract

This invention relates to the field of electronic information materials technology, providing a high-density, high-adhesion gold electrode paste for NTC thermistors, its preparation method, and its applications. The NTC thermistor gold electrode paste provided by this invention comprises the following components by weight percentage: 72-90% gold powder, 2-7% composite inorganic binder phase, 0-2% functional additives, and the balance being an organic carrier. This invention preferably uses spherical gold powder with a particle size of 1-2 μm as the conductive phase, combined with a glass powder-oxide-non-oxide composite inorganic binder phase, and simultaneously adds functional additives for performance enhancement. Through the synergistic effect of the components, the density and adhesion strength of the NTC thermistor gold electrode are effectively improved, its environmental stability is enhanced, the resistance drift rate is reduced, and the service reliability of the NTC thermistor is significantly improved. Furthermore, the preparation method provided by this invention is simple to operate, uses readily available raw materials, and balances product performance and production efficiency, making it suitable for industrial mass production.

Description

Technical Field

[0001] This invention relates to the field of electronic information materials technology, and in particular to a high-density, high-adhesion NTC thermistor gold electrode paste, its preparation method, and its application. Background Technology

[0002] NTC thermistors, due to their negative temperature coefficient, are widely used in temperature measurement, temperature control, and circuit protection. Their overall core performance is determined by the quality of the electrodes and the quality of the interface between the ceramic substrate and the electrodes. Gold electrodes, due to their excellent conductivity, chemical stability, and oxidation resistance, are the preferred electrode material for high-end NTC thermistors.

[0003] Currently, many publicly available technical solutions focus on the research and development and production of gold electrode pastes for NTC thermistors. However, these solutions generally use conventional gold electrode paste formulations, which involve simple control of the gold powder and glass powder binder phase. They do not perform fine-tuning for the particle size, morphology, and organic residues of the gold powder, nor do they design a dedicated inorganic binder phase system. Some technical solutions involve the control of powder particle size in the gold electrode paste, but they do not adapt to a dedicated compound binder phase system and functional additives, or the compound formulation used has poor compatibility with the gold powder. The prepared gold electrodes still have technical defects such as insufficient density, weak bonding with the ceramic matrix, high resistance drift rate under high temperature aging and thermal shock conditions, and poor long-term stability, making it difficult to meet the application requirements of high-precision and high-reliability electronic components.

[0004] In summary, to address the aforementioned shortcomings of existing technologies, further precise control of gold powder particle size, design of a suitable inorganic binder phase system, and supplementation with appropriate additives to prepare gold electrode paste are effective solutions for preparing high-performance NTC thermistor gold electrodes. Summary of the Invention

[0005] In view of this, the present invention provides a high-density, high-adhesion gold electrode paste for NTC thermistors, its preparation method, and its application. The gold electrode prepared using the gold electrode paste of the present invention has high density, strong adhesion to the NTC ceramic substrate, low resistance drift, and good long-term stability, thus meeting the application requirements of high-precision, high-reliability electronic components.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: An NTC thermistor gold electrode paste comprises the following components by weight percentage: 72-90% gold powder, 2-7% compounded inorganic binder phase, 0-2% functional additives, and the balance being an organic carrier. The gold powder is D. 50 Spherical gold powder with a particle size of 1~2μm has an organic residue rate of <0.5%; The components of the composite inorganic binder phase include glass powder, oxide additives and non-oxide additives; The functional additives include one or more of organotitanium reagents and organosilicon reagents.

[0007] Preferably, the glass powder is a ZnO-Bi2O3-B2O3-SiO2-Al2O3 series glass powder; the raw materials for preparing the ZnO-Bi2O3-B2O3-SiO2-Al2O3 series glass powder are ZnO, Bi2O3, H3BO3, SiO2 and Al2O3; the mass of H3BO3 is based on B2O3, and the mass ratio of ZnO, Bi2O3, B2O3, SiO2 and Al2O3 is 12~17:5~10:16~22:35~44:8~14; The glass powder D 50 The particle size is 1.5~5μm.

[0008] Preferably, the oxide additive includes one or more of zirconium oxide, nickel oxide, and copper oxide; the non-oxide additive includes one or more of silicon nitride, boron nitride, and silicon carbide; and the mass ratio of glass powder, oxide additive, and non-oxide additive in the composite inorganic binder phase is 60~80:10~20:10~20.

[0009] Preferably, the organotitanium reagent includes one or more of tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, and di(triethanolamine) titanate; the organosilicon reagent includes one or more of tetraethyl orthosilicate, methyltrimethoxysilane, and silane coupling agents.

[0010] Preferably, the organic carrier comprises the following components by weight percentage: 8-18 wt% binder, 2-5 wt% dispersant, and the balance being an organic solvent; the binder comprises one or more of nitrocellulose, ethylcellulose, and polyvinyl butyral; the dispersant comprises one or more of BYK2025, polyamide wax, and oleic acid; and the organic solvent comprises one or more of terpineol, butyl carbitol acetate, ethylene glycol monobutyl ether, and dibutyl phthalate.

[0011] This invention also provides a method for preparing the NTC thermistor gold electrode paste described above, comprising the following steps: Gold powder, compounded inorganic binder phase, functional additives and part of organic carrier are mixed to obtain a premixed slurry; The premixed slurry and the remaining organic carrier are rolled and dispersed to obtain the NTC thermistor gold electrode slurry.

[0012] Preferably, the mixing is carried out under stirring conditions, wherein the stirring speed is 800~2500 r / min and the time is 10~30 min; The rolling and dispersion process is repeated ≥20 times, and the slurry fineness is ≤10μm.

[0013] The present invention also provides the application of the NTC thermistor gold electrode paste described in the above-described scheme or the NTC thermistor gold electrode paste prepared by the preparation method described in the above-described scheme in NTC thermistors.

[0014] The present invention also provides an NTC thermistor gold electrode, which is formed from an NTC thermistor gold electrode paste; the NTC thermistor gold electrode paste is the NTC thermistor gold electrode paste described in the above scheme or the NTC thermistor gold electrode paste prepared by the preparation method described in the above scheme.

[0015] This invention also provides a method for preparing the gold electrode of the NTC thermistor described above, comprising the following steps: The NTC thermistor gold electrode paste is printed on the surface of an NTC ceramic substrate, then dried and sintered to obtain the NTC thermistor gold electrode.

[0016] This invention provides a gold electrode paste for NTC thermistors, comprising the following components by weight percentage: 72-90% gold powder, 2-7% compounded inorganic binder phase, 0-2% functional additives, and the balance being an organic carrier; wherein the gold powder is D... 50The invention uses spherical gold powder with a particle size of 1-2 μm and an organic residue rate of <0.5%. The components of the composite inorganic binder phase include glass powder, oxide additives, and non-oxide additives. The functional additives include one or more of organotitanium and organosilicon reagents. This invention selects spherical gold powder with a particle size of 1-2 μm as the conductive phase, which can improve the density of the gold electrode, enhance its long-term stability, and reduce the resistance drift rate. The composite inorganic binder phase used in this invention is composed of glass powder, oxide additives, and non-oxide additives. The oxide additives optimize sintering fluidity, strengthen the solid-state bonding between the gold powder and the glass phase, improve the interfacial compatibility between the binder phase and the ceramic substrate, and reduce sintering interfacial stress. The non-oxide additives inhibit abnormal changes in gold powder grain size, reduce internal stress during electrode sintering, improve electrode surface quality, enhance interfacial bonding strength, and optimize electrode wear resistance and thermal shock resistance. This invention, by adding organotitanium reagents, can fill the internal pores of the electrode, significantly improve the density of the gold electrode, reduce sintering defects, and optimize the high-temperature aging stability of the electrode; adding organosilicon reagents can strengthen the interfacial bonding between the gold electrode and the NTC ceramic substrate, and improve the electrode adhesion strength. The results of the examples show that the gold electrode prepared by this invention has a shear strength of 34.98~38.50 gf, a high-temperature aging resistance drift rate of only 0.28%~0.36%, and a resistance change rate of only 0.055%~0.085% after 100 cycles of thermal shock at -55℃ and 140℃.

[0017] In summary, the NTC thermistor prepared using the gold electrode paste of the present invention has high gold electrode density, strong bonding ability with the substrate, and low resistance drift rate, which greatly improves the service reliability of the NTC thermistor and is suitable for high-end electronic components.

[0018] This invention also provides the NTC thermistor gold electrode paste and its preparation method described above. The gold electrode paste is obtained through premixing and rolling dispersion, and then the gold electrode is obtained through printing and sintering. The preparation method provided by this invention is simple to operate, uses readily available raw materials, requires no complex equipment, balances product performance and production efficiency, and is suitable for industrial mass production. Attached Figure Description

[0019] Figure 1 SEM image of the gold electrode prepared in Example 1; Figure 2 SEM image of the gold electrode prepared in Example 2; Figure 3 SEM image of the gold electrode prepared in Example 3; Figure 4 SEM image of the gold electrode prepared in Example 4; Figure 5 SEM image of the gold electrode prepared in Example 5; Figure 6 This is a SEM image of the cross-sectional structure of the gold electrode and the substrate in Example 5; Figure 7 SEM image of the gold electrode prepared in Comparative Example 1; Figure 8 SEM image of the gold electrode prepared in Comparative Example 2. Detailed Implementation

[0020] This invention provides an NTC thermistor gold electrode paste, comprising the following components by weight percentage: 72-90% gold powder, 2-7% compounded inorganic binder phase, 0-2% functional additives, and the balance being an organic carrier; The gold powder is D. 50 Spherical gold powder with a particle size of 1~2μm has an organic residue rate of <0.5%; The components of the composite inorganic binder phase include glass powder, oxide additives and non-oxide additives; The functional additives include one or more of organotitanium reagents and organosilicon reagents.

[0021] Unless otherwise specified, all raw materials / components used in this invention are commercially available.

[0022] The NTC thermistor gold electrode paste provided by this invention comprises 72-90% gold powder by weight percentage, specifically 75%, 80%, 83%, 86%, or 90%; the gold powder is preferably D. 50 Spherical gold powder with a particle size of 1~2μm and an organic residue rate of <0.5%; in the embodiments of the present invention, the D of the spherical gold powder 50 Specifically, the particle size can be 1.13, 1.5, or 1.86 μm; in this invention, the gold powder is prepared according to the method in ZL 202410642305.6, and the gold powder with different particle sizes can be obtained by adjusting the amount of surfactant.

[0023] The NTC thermistor gold electrode paste provided by this invention, by weight percentage, comprises a composite inorganic binder phase of 2-7%, specifically 3%, 5%, or 6%. The composite inorganic binder phase comprises glass powder, oxide additives, and non-oxide additives. The glass powder is preferably a ZnO-Bi2O3-B2O3-SiO2-Al2O3 system glass powder. The raw materials for preparing the ZnO-Bi2O3-B2O3-SiO2-Al2O3 system glass powder are preferably ZnO, Bi2O3, H3BO3, SiO2, and Al2O3, wherein H3BO3 is the initial raw material for B2O3. The mass of H3BO3 is based on B2O3. The mass ratio of ZnO, Bi2O3, B2O3, SiO2, and Al2O3 is 12~17:5~10:16~22:35~44:8~14, specifically 15:10:19:42:14. In a specific embodiment of the present invention, the glass powder preparation method preferably includes: mixing ZnO, Bi2O3, H3BO3, SiO2, and Al2O3 and sequentially melting, water quenching, ball milling, sieving, and drying to obtain the glass powder; the melting temperature is preferably 1200℃, and the melting time is preferably 2 hours; the present invention does not have special requirements for the specific conditions of water quenching, ball milling, sieving, and drying, and those well known to those skilled in the art can be used.

[0024] In this invention, the D of the glass powder 50 The particle size is preferably 1.5~5μm, specifically 2, 2.5 or 4μm.

[0025] In this invention, the oxide additive preferably includes one or more of zirconium oxide, nickel oxide, and copper oxide; the non-oxide additive preferably includes one or more of silicon nitride, boron nitride, and silicon carbide; the mass ratio of glass powder, oxide additive, and non-oxide additive in the composite inorganic binder phase is preferably 60~80:10~20:10~20, specifically 70:15:15.

[0026] The NTC thermistor gold electrode paste provided by the present invention comprises 0-2% functional additives by weight percentage, preferably greater than 0 and less than or equal to 2%, specifically 0.1%, 0.5%, 1%, 1.5% or 2%; the functional additives preferably include one or more of organotitanium reagents and organosilicon reagents; the organotitanium reagents preferably include one or more of tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, and di(triethanolamine) diisopropyl titanate; the organosilicon reagents preferably include one or more of tetraethyl orthosilicate, methyltrimethoxysilane, and silane coupling agents.

[0027] This invention preferably uses spherical gold powder with a particle size of 1~2μm as the conductive phase, combined with a glass powder-oxide-nonoxide composite inorganic binder phase as support, and supplemented with special organic functional additives for performance enhancement, to achieve hierarchical adaptation, complementarity and mutual promotion of gold powder, inorganic binder phase and organic additives. Among them, gold powder provides excellent conductivity and a good foundation for forming, the composite binder phase optimizes sintering fluidity, interfacial compatibility and grain structure, and functional additives enhance pore filling and interfacial bonding. From the conductive substrate, solid phase skeleton and interfacial reinforcement, the density and adhesion of the electrode are upgraded simultaneously from multiple dimensions, while improving the environmental stability of the gold electrode and reducing its resistivity drift rate.

[0028] The NTC thermistor gold electrode paste provided by this invention comprises, by weight percentage, the balance being an organic carrier. In this invention, with the total mass of binder, dispersant, and organic solvent being 100%, the organic carrier comprises the following components by weight percentage: binder 8-18 wt%, specifically 10%, 13%, 15%, or 16%; dispersant 2-5 wt%, specifically 3% or 4%; and the balance being organic solvent. The binder preferably comprises one or more of nitrocellulose, ethylcellulose, and polyvinyl butyral. The preferred dispersant comprises one or more of BYK2025, polyamide wax, and oleic acid. The organic solvent preferably comprises one or more of terpineol, butyl carbitol acetate, ethylene glycol monobutyl ether, and dibutyl phthalate. In a specific embodiment of this invention, the organic solvent is preferably a mixed solvent of terpineol and butyl carbitol acetate, wherein the mass ratio of terpineol to butyl carbitol acetate in the mixed solvent is 7:3.

[0029] This invention also provides a method for preparing the NTC thermistor gold electrode paste described above, comprising the following steps: Gold powder, compounded inorganic binder phase, functional additives and part of organic carrier are mixed to obtain a premixed slurry; The premixed slurry and the remaining organic carrier are rolled and dispersed to obtain the NTC thermistor gold electrode slurry.

[0030] This invention mixes gold powder, a compounded inorganic binder phase, functional additives, and a portion of an organic carrier to obtain a premixed slurry. In this invention, the gold powder and the compounded inorganic binder phase are preferably dried before mixing. The drying temperature is preferably 70-90℃, specifically 80℃, and the drying time is preferably 1-2 hours, specifically 1.5 hours. The organic carrier accounts for 30-70% of the total organic carrier mass, specifically 40%. The mixing is preferably carried out under stirring conditions. The stirring speed is preferably 800-2500 r / min, specifically 1200 r / min, and the stirring time is preferably 10-30 minutes, specifically 20 minutes. In a specific embodiment of this invention, when the weight percentage of the functional additive is 0, the addition of the functional additive can be omitted.

[0031] After obtaining the premixed slurry, the present invention further disperses the premixed slurry and the remaining organic carrier by rolling to obtain the NTC thermistor gold electrode slurry. In the present invention, the rolling dispersion is preferably carried out using a three-roll mill; the number of rolling dispersions is preferably ≥20 times, specifically 30 times; and the fineness of the slurry obtained by rolling dispersion is preferably ≤10μm.

[0032] The present invention also provides the application of the gold electrode paste for NTC thermistors described above in NTC thermistors.

[0033] The present invention also provides an NTC thermistor gold electrode, which is formed from an NTC thermistor gold electrode paste; the NTC thermistor gold electrode paste is the NTC thermistor gold electrode paste described in the above scheme or the NTC thermistor gold electrode paste prepared by the preparation method described in the above scheme.

[0034] This invention also provides a method for preparing the gold electrode of the NTC thermistor described above, comprising the following steps: The NTC thermistor gold electrode paste is printed on the surface of an NTC ceramic substrate, then dried and sintered to obtain the NTC thermistor gold electrode.

[0035] In this invention, the drying temperature is preferably 110~150℃, specifically 120℃, the drying time is preferably 10~20min, specifically 15min, the sintering is preferably tunnel furnace sintering, the peak temperature of sintering is preferably 830~900℃, specifically 850℃, and the sintering time at the peak temperature is preferably 10~20min, specifically 15min.

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments thereof.

[0037] In the following examples, the gold powder was prepared using the preparation method described in ZL202410642305.6. By changing the amount of surfactant, spherical gold powder with different particle sizes was prepared.

[0038] The specific preparation method of gold powder is as follows: S1. Weigh 40g of chloroauric acid solution (concentration of 50wt% based on gold) into a beaker, dilute it with 900mL of water-n-propanol mixed solvent with a volume ratio of 1:1, place it in a 40℃ constant temperature water bath and stir at a stirring speed of 250rpm until homogeneous. Then adjust the pH value of the solution to 4.0 by adding concentrated ammonia dropwise to obtain the gold source solution. S2. Weigh 3.2g of surfactant polyvinylpyrrolidone and dissolve it in 50mL of n-propanol solvent. Then add the obtained surfactant solution to the reaction gold source solution obtained in step S1 to obtain a pre-reaction solution. S3. Weigh 70g of reducing agent ascorbic acid and add it to 50mL of deionized water. Stir and dissolve the solution in a 60℃ constant temperature water bath. After cooling, the reducing agent solution is obtained. Then, it is added to the pre-reaction solution at a dropping rate of 1.6mL / s and reacted for 1h. After the reaction is completed, the resulting golden yellow turbid liquid is aged for 15min. Then, it is washed twice by centrifugation with deionized water to obtain a gold-containing precipitate. S4. Measure 33 mL of 30% hydrogen peroxide solution, pour it into a beaker, add deionized water to prepare 200 mL of hydrogen peroxide treatment solution, disperse the gold-containing precipitate obtained in step S3 in the treatment solution, place it in an ultrasonic cleaner for ultrasonic treatment, remove the beaker after boiling, wait for the beaker temperature to drop and the solution to become clear and transparent, remove the supernatant, wash three times with deionized water and ethanol respectively by centrifugation, and then dry in a 70℃ forced-air drying oven to obtain D. 50 Spherical gold powder with a particle size of 1.13 μm.

[0039] Prepared according to the above method, the mass of the surfactant was changed to 2.5g, yielding D. 50 Gold powder with a particle size of 1.5 μm; by changing the mass of the surfactant to 2.0 g, D was obtained. 50 Spherical gold powder with a particle size of 1.86 μm; by changing the mass of the surfactant to 5.0 g, D was obtained. 50 Spherical gold powder with a particle size of 0.6 μm; by changing the mass of the surfactant to 1.4 g, D was obtained. 50 Spherical gold powder with a particle size of 2.7 μm. The organic residue rate of the above gold powder is less than 0.5%.

[0040] Example 1 By weight percentage, the gold electrode paste for NTC thermistors consists of the following components: 83 wt% gold powder, 3 wt% compounded inorganic binder phase, and 14 wt% organic carrier. Wherein, the D of the gold powder50 The particle size is 1.13 μm; The composite inorganic binder phase is composed of glass powder, oxide, and non-oxide in a mass ratio of 70:15:15. The glass powder is a ZnO-Bi2O3-B2O3-SiO2-Al2O3 system glass powder, which is prepared by mixing ZnO, Bi2O3, H3BO3, SiO2, and Al2O3 (the mass of H3BO3 is calculated as B2O3, and the mass ratio of ZnO, Bi2O3, B2O3, SiO2, and Al2O3 is 15:10:19:42:14), placing it in a furnace, melting it at 1200℃ for 2 hours, and then rapidly water quenching it to obtain microcrystalline glass. The microcrystalline glass is then ball-milled, sieved, and dried to obtain ZnO-Bi2O3-B2O3-SiO2-Al2O3 glass powder with a softening point of 610℃ and an average particle size of 2.5μm. The oxide is zirconium oxide, and the non-oxide is silicon nitride.

[0041] The organic carrier is composed of a binder, an organic solvent, and a dispersant, with the binder comprising 13 wt%, the dispersant 4 wt%, and the organic solvent 83 wt% by weight. The binder is ethyl cellulose, the organic solvent is a mixture of terpineol and butyl carbitol acetate (the mass ratio of terpineol to butyl carbitol acetate is 7:3), and the dispersant is BYK2025. The specific preparation process is as follows: 13 g of ethyl cellulose is weighed into a mixture of 83 g of terpineol and butyl carbitol acetate (58.1 g and 24.9 g, respectively), stirred and dissolved at 90 °C, and after cooling, 4 g of BYK2025 is added and stirred until homogeneous to obtain the organic carrier.

[0042] The preparation methods of gold conductor paste and gold electrode are as follows: S1. Gold powder, compounded inorganic binder phase and organic carrier accounting for 40% of the total organic carrier mass are mixed in a homogenizer to obtain a premixed slurry; wherein the mixing speed is 1200 r / min and the mixing time is 20 min; S2. The premixed slurry and the remaining 60% of the organic carrier are rolled in a three-roll mill to obtain the NTC thermistor gold electrode slurry; the rolling is performed 30 times, and the fineness of the slurry is controlled to be ≤ 10μm. S3. The gold electrode paste is printed on the surface of an NTC ceramic substrate, and then dried and sintered to obtain an NTC thermistor gold electrode; wherein the drying temperature is 120°C, the drying time is 15 min, the peak sintering temperature in the tunnel furnace is 850°C, and the sintering time at the peak temperature is 15 min.

[0043] Example 2 All other conditions are the same as in Example 1, except that the D of the gold powder used is changed. 50 The particle size is 1.5 μm.

[0044] Example 3 All other conditions are the same as in Example 1, except that the D of the gold powder used is changed. 50 The particle size is 1.86 μm.

[0045] Example 4 Other conditions were the same as in Example 1, except that the composition of the gold electrode paste was changed to: 83 wt% gold powder, 2.5 wt% compounded inorganic binder phase, 1 wt% tetrabutyl titanate, and 13.5 wt% organic carrier; and the D of the gold powder used was... 50 The particle size is 1.5 μm. Tetrabutyl titanate is added in step S1 during the preparation of the gold electrode paste.

[0046] Example 5 Other conditions were the same as in Example 1, except that the composition of the gold electrode paste was changed to: 83 wt% gold powder, 2.5 wt% compounded inorganic binder, 1 wt% KH550 silane coupling agent, and 13.5 wt% organic carrier; and the D of the gold powder used was... 50 The particle size is 1.5 μm. KH550 silane coupling agent is added in step S1 during the preparation of the gold electrode slurry.

[0047] Comparative Example 1 All other conditions are the same as in Example 1, except that the D of the gold powder used is changed. 50 The particle size is 0.6 μm.

[0048] Comparative Example 2 All other conditions are the same as in Example 1, except that the D of the gold powder used is changed. 50 The particle size is 2.7 μm.

[0049] Comparative Example 3 Other conditions are the same as in Example 1, except that the compound binder phase is replaced with a single binder phase, that is, ZnO-Bi2O3-B2O3-SiO2-Al2O3 glass powder is used as the binder phase, without adding oxides and non-oxides; and the D of the gold powder used is... 50 The particle size is 1.5 μm.

[0050] Performance testing 1. Morphological test The surface morphology or cross-sectional structure of the gold electrodes in Examples 1-5 and Comparative Examples 1-2 were observed using scanning electron microscopy. Figures 1-5 SEM images of the gold electrodes prepared in Examples 1-5 are shown. Figure 6 This is a SEM image of the cross-sectional structure of the gold electrode and the substrate in Example 5; Figures 7-8 SEM images of the gold electrodes prepared in Comparative Examples 1-2.

[0051] 2. Shear strength, high-temperature aging performance and thermal shock performance tests The gold electrodes prepared in Examples 1-5 and Comparative Examples 1-3 were tested for shear strength, high-temperature aging performance, and thermal shock performance. The specific test methods are as follows: 1) Shear strength: A micro-force push-pull tester was used, with a testing speed of 4 mm / min. Each sample was tested 30 times, and the average value was taken. 2) High-temperature aging performance: The sample was placed in a constant temperature chamber at 180℃ for 100h and the resistance value before and after aging was tested. The resistance change rate ΔR / R0 was calculated (ΔR = resistance value after aging - resistance value before aging, R0 is the resistance value before aging). 3) Thermal shock performance: The sample was placed in a thermal shock chamber at -55℃ to 140℃ for 100 cycles, with each high and low temperature cycle lasting 30 minutes. The resistance value before and after the shock was tested, and the resistance change rate ΔR / R0 was calculated.

[0052] The performance test results are shown in the table below.

[0053] Table 1 Performance parameters of the gold electrodes in Examples 1-5 and Comparative Examples 1-3

[0054] Test Result Analysis: Comparing Examples 1-3, it can be seen that when the gold powder particle size is controlled within the range of 1-2 μm, the performance of the gold electrode changes systematically with the particle size: as the particle size increases from 1.13 μm to 1.86 μm, the shear strength increases slightly, the rate of change of thermal shock resistance gradually decreases, and the high-temperature aging drift rate increases slightly but remains at an excellent level overall; Examples 1-3 all exhibit good compactness (see Examples 1-3). Figures 1-3 This fully confirms the rationality of the 1~2μm particle size range, but Example 2 (D) 50 =1.5μm) is relatively denser and has more regular grains, making it the optimal implementation method. In contrast, in Comparative Example 1 (0.60μm) and Comparative Example 2 (2.70μm), the electrode performance deteriorated significantly and the film density decreased markedly after the gold powder particle size exceeded the optimal range (see Comparative Example 1). Figures 7-8 The shear strength decreased and the resistance drift rate far exceeded that of the embodiment, which could not meet the requirements of high-end NTC thermistors, proving the necessity of limiting the particle size of gold powder in this invention.

[0055] Under the same gold powder particle size, the electrode using the composite inorganic binder phase has better performance than the electrode using the single ZnO-Bi2O3-B2O3-SiO2-Al2O3 glass powder binder phase (Comparative Example 3). Examples 1 to 5 all showed good performance, while the shear strength of Comparative Example 3 decreased significantly and the resistivity drift increased significantly. The above results further verify that the composite inorganic binder phase can effectively optimize the sintering effect and strengthen the interfacial bonding, and has significant performance advantages compared with the traditional single binder phase.

[0056] By adding functional additives based on the optimal gold powder particle size and the composite inorganic binder phase, the electrode performance is significantly improved: Example 4 shows the addition of an organic titanium reagent, which can effectively fill the internal pores of the electrode (see...). Figure 4 The sintering defects were optimized, and the high-temperature aging and thermal shock performance was the best in the entire group, significantly enhancing the long-term stability of the electrode. In Example 5, a silane coupling agent was added, which significantly enhanced the interfacial bonding between the electrode and the NTC ceramic matrix (see Example 5). Figures 5-6 The shear strength is increased to 38.50 gf, which takes into account both super strong adhesion and excellent stability, further highlighting the scientific nature of the formulation of this invention, and perfectly matching the core development goals of high density, high adhesion and high stability.

[0057] In summary, this invention controls the gold powder particle size to 1~2μm, and combines it with a glass powder-oxide-non-oxide composite inorganic binder phase, supplemented by functional additives to achieve multi-level synergistic effects. This comprehensively improves the density, adhesion, and stability of the gold electrode, fundamentally solving the common industry problems of insufficient gold electrode density, low adhesion, high resistance drift rate, and poor long-term service stability in existing NTC thermistors. The resulting gold electrode exhibits excellent and balanced mechanical properties and environmental tolerance, meeting the requirements for long-term reliable operation of high-end NTC thermistors. Furthermore, the preparation process is simple and suitable for industrial mass production, showing broad prospects for industrial applications.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A gold electrode paste for an NTC thermistor, characterized in that, It includes the following components by weight percentage: 72-90% gold powder, 2-7% compounded inorganic binder phase, 0-2% functional additives, and the balance being an organic carrier; The gold powder is D. 50 Spherical gold powder with a particle size of 1~2μm has an organic residue rate of <0.5%; The components of the composite inorganic binder phase include glass powder, oxide additives and non-oxide additives; The functional additives include one or more of organotitanium reagents and organosilicon reagents.

2. The NTC thermistor gold electrode paste according to claim 1, characterized in that, The glass powder is a ZnO-Bi2O3-B2O3-SiO2-Al2O3 series glass powder; the raw materials for preparing the ZnO-Bi2O3-B2O3-SiO2-Al2O3 series glass powder are ZnO, Bi2O3, H3BO3, SiO2 and Al2O3; the mass of H3BO3 is based on B2O3, and the mass ratio of ZnO, Bi2O3, B2O3, SiO2 and Al2O3 is 12~17:5~10:16~22:35~44:8~14; The glass powder D 50 The particle size is 1.5~5μm.

3. The NTC thermistor gold electrode paste according to claim 1, characterized in that, The oxide additives include one or more of zirconium oxide, nickel oxide, and copper oxide; the non-oxide additives include one or more of silicon nitride, boron nitride, and silicon carbide; the mass ratio of glass powder, oxide additives, and non-oxide additives in the composite inorganic binder phase is 60~80:10~20:10~20.

4. The NTC thermistor gold electrode paste according to claim 1, characterized in that, The organotitanium reagents include one or more of tetrabutyl titanate, tetraisopropyl titanate, tetraethyl titanate, and di(triethanolamine) titanate diisopropyl; the organosilicon reagents include one or more of tetraethyl orthosilicate, methyltrimethoxysilane, and silane coupling agents.

5. The NTC thermistor gold electrode paste according to claim 1, characterized in that, The organic carrier comprises the following components by weight percentage: 8-18 wt% binder, 2-5 wt% dispersant, and the balance being an organic solvent; the binder comprises one or more of nitrocellulose, ethylcellulose, and polyvinyl butyral; the dispersant comprises one or more of BYK2025, polyamide wax, and oleic acid; and the organic solvent comprises one or more of terpineol, butyl carbitol acetate, ethylene glycol monobutyl ether, and dibutyl phthalate.

6. The method for preparing the NTC thermistor gold electrode paste according to any one of claims 1 to 5, characterized in that, Includes the following steps: Gold powder, compounded inorganic binder phase, functional additives and part of organic carrier are mixed to obtain a premixed slurry; The premixed slurry and the remaining organic carrier are rolled and dispersed to obtain the NTC thermistor gold electrode slurry.

7. The preparation method according to claim 6, characterized in that, The mixing is carried out under stirring conditions, with a stirring speed of 800~2500 r / min and a stirring time of 10~30 min; The rolling and dispersion process is repeated ≥20 times, and the slurry fineness is ≤10μm.

8. The application of the NTC thermistor gold electrode paste according to any one of claims 1 to 5 or the NTC thermistor gold electrode paste prepared by the preparation method according to any one of claims 6 to 7 in NTC thermistors.

9. A gold electrode for an NTC thermistor, characterized in that, It is formed from NTC thermistor gold electrode paste; the NTC thermistor gold electrode paste is the NTC thermistor gold electrode paste according to any one of claims 1 to 5 or the NTC thermistor gold electrode paste prepared by the preparation method according to any one of claims 6 to 7.

10. The method for preparing the gold electrode of the NTC thermistor according to claim 9, characterized in that, Includes the following steps: The NTC thermistor gold electrode paste is printed on the surface of an NTC ceramic substrate, then dried and sintered to obtain the NTC thermistor gold electrode.

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