Beryllium oxide ceramic pyrotechnic resistor conductor silver paste, preparation method and application thereof

Abstract

The present application relates to electronic paste and special ceramic electronic component material technical field, put forward the conductor silver paste for beryllium oxide ceramic initiating explosive resistor and preparation method and application, the conductor silver paste includes 75%-85% silver powder, 3%-7% glass powder, 0.5%-2% composite modified additive and the balance of organic carrier according to mass percent; Composite modified additive is composed of rare earth metal oxide and silicon-based precursor; Rare earth metal oxide includes one or more of lanthanum oxide, cerium oxide, neodymium oxide; The silicon-based precursor is methyl phenyl polysiloxane precursor, the conductor silver paste solves the technical problem that the silver layer is easy to fall off after the silver paste for conventional alumina is plated with nickel, tin lead process on the beryllium oxide ceramic matrix, and at the same time, complete compatibility with the existing silk screen printing, sintering process is maintained.

Description

Technical Field

[0001] This invention relates to the field of electronic pastes and special ceramic electronic component materials, and more specifically, to conductor silver paste for beryllium oxide ceramic pyrotechnic resistors, its preparation method, and its application. Background Technology

[0002] Beryllium oxide ceramics are special inorganic non-metallic functional materials prepared using beryllium oxide as the main raw material. They feature high thermal conductivity, low dielectric constant, and good high-temperature stability. Their room temperature thermal conductivity can reach 240–300 W / (m·K), approximately 10 times that of conventional alumina ceramics, and their thermal conductivity level is close to that of metallic aluminum. Simultaneously, they possess high mechanical strength and excellent insulation properties.

[0003] Pyrotechnic resistors generate a large amount of Joule heat in a very short time during ignition, requiring the substrate material to quickly dissipate this heat and prevent localized heat accumulation that could lead to unreliable ignition. Beryllium oxide ceramics, with their excellent thermal conductivity and mechanical strength, effectively dissipate the operating heat of the device and ensure structural stability under extreme conditions, making them an ideal choice for the substrate material of pyrotechnic resistors.

[0004] Conductive silver paste is a paste system prepared by mixing silver powder, glass powder, and organic carrier through a slurry and rolling process. Currently, most resistors in the field of electronic components use alumina ceramic as the matrix. Commercially available conductive silver pastes are formulated specifically for the surface energy, thermal expansion coefficient, and interfacial reaction characteristics of alumina ceramic, and the relevant formulation systems and production processes are very mature.

[0005] Because the production scale of beryllium oxide ceramic pyrotechnic resistors is relatively small, current production typically uses silver paste specifically designed for alumina ceramics for electrode fabrication. However, beryllium oxide ceramics have a strongly covalent hexagonal wurtzite structure and are chemically inert, exhibiting significantly different physicochemical properties compared to alumina ceramics. Conventional alumina silver paste glass phase systems are designed for the lattice characteristics of alumina, resulting in insufficient wettability and interfacial reactivity on the beryllium oxide ceramic surface. This fails to form sufficiently strong interfacial bonds, leading to microscopic gaps and weak bonding areas between the silver layer and the substrate.

[0006] In subsequent nickel and tin-lead electroplating processes, the acidic electrolyte gradually seeps into the interface region along microscopic gaps, further eroding the already fragile bonding interface, ultimately causing the silver layer and plating to detach from the beryllium oxide ceramic substrate. This problem seriously affects the installation reliability and operational safety of pyrotechnic resistors and is one of the key technical bottlenecks restricting the large-scale application of beryllium oxide ceramic pyrotechnic resistors. Summary of the Invention

[0007] In view of this, the present invention provides a conductor silver paste for beryllium oxide ceramic pyrotechnic resistors, a preparation method and application. This conductor silver paste solves the technical problem that the silver layer of conventional alumina silver paste is easy to fall off after electroplating nickel and tin-lead processes on beryllium oxide ceramic substrates, while maintaining full compatibility with existing screen printing and sintering processes.

[0008] The technical solution of this invention is as follows: In a first aspect, the present invention provides a conductor silver paste for beryllium oxide ceramic pyrotechnic resistors, wherein the conductor silver paste comprises, by mass percentage, 75%-85% silver powder, 3%-7% glass powder, 0.5%-2% composite modifying additives and the balance being an organic carrier. The composite modified additive is composed of rare earth metal oxides and silicon-based precursors. The rare earth metal oxides include one or more of lanthanum oxide, cerium oxide, and neodymium oxide; The silicon-based precursor is a methylphenyl polysiloxane precursor; The mass ratio of the rare earth metal oxide to the silicon-based precursor is 1:(0.5-2).

[0009] Furthermore, the rare earth metal oxide is a nanoparticle with a particle size of less than 100 nm.

[0010] Furthermore, the molecular formula of the methylphenyl polysiloxane precursor is: Molecular weight 500-2000, viscosity 50-800 cSt.

[0011] Furthermore, the silver powder is spherical silver powder with a purity of not less than 99.9% and a particle size of 0.5-1.5μm.

[0012] Furthermore, the glass powder is a borosilicate calcium system glass powder, which includes, by mass percentage, 35%-40% silicon dioxide, 35%-40% calcium oxide, 10%-20% aluminum oxide, 5%-10% barium oxide and 0.5%-2% lithium oxide.

[0013] Furthermore, the conductor silver paste comprises, by mass percentage, 78%-82% silver powder, 4%-6% glass powder, 0.8%-1.5% composite modifying additives, and the balance being an organic carrier. Secondly, based on the same inventive concept, the present invention provides a method for preparing the conductor silver paste for beryllium oxide ceramic pyrotechnic resistors as described in any one of the first aspects, comprising the following steps: The silver powder, the glass powder, and the composite modifier are added to the organic carrier and stirred at room temperature for 8-15 minutes for initial mixing. Then, the mixture is stirred in a planetary gravity mixer to obtain a mixed slurry. The mixed slurry is ground through a rolling process to obtain a ground slurry; The grinding slurry is filtered to remove impurities and degassed under vacuum to obtain the conductor silver paste.

[0014] Furthermore, the rolling process is repeated 2-4 times until the fineness of the grinding slurry is no greater than 10μm.

[0015] Furthermore, the mixing in the planetary gravity mixer specifically involves: first mixing at 1500-2000 rpm for 200-300 seconds, and then mixing at 300-500 rpm for 300-400 seconds to obtain the mixed slurry.

[0016] Thirdly, based on the same inventive concept, the present invention provides the application of the conductor silver paste for beryllium oxide ceramic pyrotechnic resistors described in the first aspect or the conductor silver paste for beryllium oxide ceramic pyrotechnic resistors prepared by the preparation method described in the second aspect in the preparation of electrodes for beryllium oxide ceramic pyrotechnic resistors.

[0017] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. This invention employs a composite additive system synergistically modified with rare earth metal oxides and silicon-based precursors. The rare earth oxide nanoparticles can form stable chemical bonds with the lattice oxygen on the surface of beryllium oxide ceramics, enhancing the physicochemical bonding between the silver layer and the substrate. During sintering, the silicon-based precursor forms a dense interface modification layer, effectively filling microscopic gaps and blocking electrolyte penetration channels. Under the synergistic effect of both, the adhesion of the silver electrode after electroplating remains stable at no less than 70N, an improvement of over 150% compared to conventional commercial alumina silver paste, completely eliminating the problem of silver layer / plating layer peeling off after electroplating.

[0018] 2. The silver paste of this invention follows the traditional silver paste production process, without requiring modification to existing printing and sintering equipment and process parameters, and can be directly applied to mass production, demonstrating strong engineering feasibility.

[0019] 3. After electroplating with nickel and tin-lead, the silver layer and plating layer do not peel off or flake, significantly improving the installation reliability and welding strength of beryllium oxide ceramic pyrotechnic resistors.

[0020] 4. The conductor silver paste of the present invention can be directly applied to the mass production of beryllium oxide ceramic pyrotechnic resistor electrodes through screen printing process. After drying and sintering, a dense silver electrode is formed, which can withstand subsequent nickel and tin-lead electroplating processes and meet the reliability requirements of the entire process of pyrotechnic resistors. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a SEM image of the silver electrode of the product obtained in Example 1 of the present invention; Figure 2 This is a process route diagram for the testing section of this invention; Figure 3 This is a bar chart showing the silver layer adhesion test results of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0025] To address the problems existing in the prior art, according to one aspect of the present disclosure, a conductor silver paste for beryllium oxide ceramic pyrotechnic resistors is provided, which comprises, by mass percentage, 75%-85% silver powder, 3%-7% glass powder, 0.5%-2% composite modifying additives and the balance being an organic carrier. The composite modifier is composed of rare earth metal oxides and silicon-based precursors; Rare earth metal oxides include one or more of lanthanum oxide, cerium oxide, and neodymium oxide; The silicon-based precursor is a methylphenyl polysiloxane precursor; The mass ratio of rare earth metal oxides to silicon-based precursors is 1:(0.5-2).

[0026] In some examples, the composite modifier can be selected from any value between 0.5% and 2% by mass percentage.

[0027] For example, the composite modifiers are, by weight percentage, including but not limited to 0.5%, 0.6%, 0.7%, 0.9%, 1%, 1.2%, 1.5%, 1.8% and 2.0%.

[0028] It should be noted that the sum of the mass percentages of all components in the conductor silver paste is 100%.

[0029] In some examples, rare earth metal oxides are nanoparticles with a particle size of less than 100 nm, which can form stable chemical bonds with the lattice oxygen on the surface of beryllium oxide ceramics, anchoring the interface structure and further enhancing the interfacial bonding force.

[0030] In some examples, the molecular formula of the methylphenyl polysiloxane precursor is Molecular weight 500-2000, viscosity 50-800 cSt.

[0031] It should be noted that the methylphenyl polysiloxane precursor is commercially available, with CAS number 63148-52-7.

[0032] In some examples, the silver powder is spherical silver powder with a purity of not less than 99.9% and a particle size of 0.5-1.5μm, ensuring a dense and uniform conductive network.

[0033] In some examples, the glass powder is a borosilicate calcium system glass powder, which by mass percentage comprises 35%-40% silicon dioxide, 35%-40% calcium oxide, 10%-20% aluminum oxide, 5%-10% barium oxide and 0.5%-2% lithium oxide. This glass powder system is matched with the sintering temperature and coefficient of thermal expansion.

[0034] In some examples, the conductor silver paste comprises, by mass percentage, 78%-82% silver powder, 4%-6% glass powder, 0.8%-1.5% composite modifiers, and the balance being an organic carrier.

[0035] It should be noted that the organic carrier is composed of a film-forming resin and an organic solvent. The film-forming resin is selected from one or more of ethyl cellulose and acrylic resin, and the organic solvent is selected from one or more of terpineol, diethylene glycol butyl ether, diethylene glycol butyl ether acetate, and tributyl citrate. The viscosity of the organic carrier is 10-60 Pa·s (25℃).

[0036] It should also be noted that the surface of beryllium oxide ceramics is dominated by Be-O bonds, and the surface hydroxyl density is extremely low (approximately 0.5-1 hydroxyl groups / nm). 2 This is far lower than the 4-5 per nm of alumina ceramics. 2 This results in additives in conventional glass powder systems being unable to form effective chemical anchoring with the substrate surface, relying only on physical wetting, and naturally resulting in low interfacial bonding strength.

[0037] In this invention, rare earth ions (La) 3+ Ce 3+ / Ce 4+ 、Nd 3+The oxygen atoms possess empty 4f orbitals and exhibit a strong affinity for oxygen. During sintering at temperatures above 500℃, nano-rare earth oxides undergo a solid-state reaction with the lattice oxygen on the surface of beryllium oxide ceramics, forming rare earth beryllate transition phases, such as La₂Be₂O₅. This transition phase is chemically compatible with both the beryllium oxide matrix and the silver glass phase, acting as a chemical anchor. Nanoparticles with a particle size of less than 100 nm possess a larger specific surface area and higher surface activity, enabling the initiation of the aforementioned solid-state reaction at lower temperatures.

[0038] During sintering at 300-600℃, the methylphenyl polysiloxane precursor undergoes thermal decomposition, resulting in the orderly removal of phenyl and methyl side chains and the gradual cross-linking and solidification of the Si-O backbone. This leads to the in-situ formation of a dense SiO2-based inorganic modified layer at the silver-ceramic interface. This modified layer fills the micropores formed by the shrinkage of the silver powder during sintering and forms chemical bonds with the rare-earth beryllium salt transition phase, constructing a complete interfacial bonding network. Methylphenyl polysiloxane was chosen instead of pure methyl or pure phenyl polysiloxane because phenyl provides higher thermal stability, while methyl ensures appropriate fluidity. The ratio of these two components determines the rheological behavior of the precursor during the sintering heating stage and the final film quality. The molecular weight limit of 500-2000 and viscosity of 50-800 cSt ensures uniform dispersion of the precursor in the organic carrier and prevents premature cross-linking during printing and drying.

[0039] According to another aspect of the embodiments of this application, a method for preparing conductor silver paste for beryllium oxide ceramic pyrotechnic resistors is also provided, comprising the following steps: Silver powder, glass powder and composite modifiers are added to an organic carrier and stirred at room temperature for 8-15 minutes for initial mixing. Then, the mixture is stirred in a planetary gravity mixer to obtain a slurry. The mixed slurry is ground through a rolling process to obtain a ground slurry; The grinding slurry is filtered to remove impurities and degassed under vacuum to obtain conductive silver paste.

[0040] It should be noted that the silver powder, glass powder, rare earth metal oxides, methylphenyl polysiloxane precursors, organic carriers, and other raw materials used in this invention are all commercially available industrial-grade products. Their preparation or synthesis methods have been disclosed in the prior art, and the products obtained by different preparation or synthesis methods can all be applied to the technical solution of this invention. The different preparation or synthesis methods will not affect the technical effect of this invention. Those skilled in the art can refer to the prior art to select a suitable method or purchase commercially available finished products for use without any creative effort. No limitation is made here.

[0041] In some examples, the rolling process is repeated 2-4 times until the fineness of the grinding slurry is no greater than 10 μm.

[0042] In some examples, the mixing process in a planetary gravity mixer involves first mixing at 1500-2000 rpm for 200-300 seconds, and then mixing at 300-500 rpm for 300-400 seconds to obtain a mixed slurry.

[0043] According to another aspect of the embodiments of this application, the application of the conductor silver paste for beryllium oxide ceramic pyrotechnic resistors as described in any one of the first aspects or the conductor silver paste for beryllium oxide ceramic pyrotechnic resistors prepared by the preparation method described in any one of the second aspects in the preparation of electrodes for beryllium oxide ceramic pyrotechnic resistors is also provided.

[0044] In some examples, the above application specifically involves printing conductive silver paste onto a beryllium oxide ceramic substrate using a screen printing process, drying and sintering it to form a silver electrode, and then forming a composite electrode layer through nickel plating and tin-lead plating processes.

[0045] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed according to national standards. If no corresponding national standard exists, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed. Example 1

[0046] This embodiment 1 provides a conductor silver paste for beryllium oxide ceramic pyrotechnic resistors and its preparation method. The mass percentages of each component are as follows: 80% spherical silver powder with a particle size of 1.0 μm and a purity of 99.9%; The borosilicate calcium system glass powder consists of 38% SiO2, 38% CaO, 15% Al2O3, 8% BaO, and 1% Li2O, and comprises 5% glass powder. A 1% composite modifier consisting of 0.4% lanthanum oxide, 0.6% methylphenyl polysiloxane precursor, and 1% by mass ratio of 1:1.5; The organic carrier consists of 59.5% terpineol, 20% diethylene glycol butyl ether, 10% diethylene glycol butyl ether acetate, 10% ethyl cellulose, and 0.5% lecithin.

[0047] The molecular formula of the methylphenyl polysiloxane precursor is: Number average molecular weight 1000, viscosity 500 cSt.

[0048] The preparation method is as follows: Weigh each component according to the above formula, add silver powder, glass powder and composite modified additive to the organic carrier, stir at room temperature for 10 min; place in a planetary gravity mixer and stir at 1600 rpm for 240 s, then stir at 300 rpm for 300 s; grind to a fineness of no more than 10 μm using a three-roll mill; filter to remove impurities and degas under vacuum to obtain conductor silver paste.

[0049] SEM image of the conductor silver paste silver electrode prepared in Example 1 is shown below. Figure 1 As shown. Example 2

[0050] This embodiment 2 provides a conductor silver paste for beryllium oxide ceramic pyrotechnic resistors and its preparation method. The mass percentages of each component are as follows: 78% of the silver powder is spherical with a particle size of 1.0 μm and a purity of 99.9%. The borosilicate calcium system glass powder, consisting of 38% SiO2, 38% CaO, 15% Al2O3, 8% BaO, and 1% Li2O, comprises 6% glass powder. A composite modifier consisting of 0.5% cerium oxide, 1.0% methylphenyl polysiloxane precursor, and 1.5% by mass ratio of 1:2; The organic carrier consists of 69.5% terpineol, 20% diethylene glycol butyl ether, 10% ethyl cellulose, and 0.5% lecithin, and is 14.5% organic.

[0051] The molecular formula of the methylphenyl polysiloxane precursor is: Number average molecular weight 500, viscosity 50 cSt.

[0052] The preparation method is as follows: Weigh each component according to the above formula, add silver powder, glass powder and composite modifier to the organic carrier, stir at room temperature for 8 minutes; place in a planetary gravity mixer and stir at 1500 rpm for 200 seconds, then stir at 400 rpm for 350 seconds; grind to a fineness of no more than 10 μm using a three-roll mill; filter to remove impurities and degas under vacuum to obtain conductor silver paste. Example 3

[0053] This embodiment 3 provides a conductor silver paste for beryllium oxide ceramic pyrotechnic resistors and its preparation method. The mass percentages of each component are as follows: 82% of the silver powder is spherical with a particle size of 1.0 μm and a purity of 99.9%. The borosilicate calcium system glass powder, consisting of 38% SiO2, 36% CaO, 15% Al2O3, 8% BaO, and 1% Li2O, comprises 4% glass powder. A composite modifier consisting of 0.8% neodymium oxide (0.3%), methylphenyl polysiloxane precursor (0.5%), and a mass ratio of 1:1.67; The organic carrier consists of 59.5% terpineol, 20% diethylene glycol butyl ether, 10% tributyl citrate, 10% ethyl cellulose, and 0.5% lecithin, totaling 13.2%.

[0054] The molecular formula of the methylphenyl polysiloxane precursor is: Number average molecular weight 2000, viscosity 800 cSt.

[0055] The preparation method is as follows: Weigh each component according to the above formula, add silver powder, glass powder and composite modifier to the organic carrier, stir at room temperature for 15 minutes; place in a planetary gravity mixer and stir at 2000 rpm for 300 seconds, then stir at 500 rpm for 400 seconds; grind to a fineness of no more than 10 μm using a three-roll mill; filter to remove impurities and degas under vacuum to obtain conductor silver paste.

[0056] Comparative Example 1 Comparative Example 1 provides a commercially available conventional silver paste for alumina ceramics. According to the product specifications, its main components include 74%-75% silver powder, no more than 3% glass powder, and no more than 22% organic carrier. The remaining component information is based on the actual composition of commercially available products. It is directly used for electrode preparation on beryllium oxide ceramic substrates as a blank control.

[0057] Comparative Example 2 Comparative Example 2 provides a conductive silver paste and its preparation method. The preparation method is the same as that in Example 1, except that rare earth metal oxides are used alone to verify the effect of not adding methylphenyl polysiloxane precursor on the technical effect of the present invention. The mass percentage of each component of the conductive silver paste is as follows: 80% spherical silver powder, 5% glass powder, 1% lanthanum oxide, and 14% organic carrier.

[0058] Comparative Example 3 Comparative Example 3 provides a conductive silver paste and its preparation method. The preparation method is the same as that in Example 1, except that a methylphenyl polysiloxane precursor is used alone to verify the effect of not adding rare earth metal oxides on the technical effect of the present invention. The mass percentage of each component of the conductive silver paste is as follows: 80% spherical silver powder, 5% glass powder, 1% methylphenyl polysiloxane precursor, and 14% organic carrier.

[0059] Comparative Example 4 Comparative Example 4 provides a conductive silver paste and its preparation method. The preparation method is the same as that in Example 1, except that the mass ratio of rare earth metal oxide to methylphenyl polysiloxane precursor is 1:3, in order to verify the impact of the mass ratio exceeding the limit of the present invention on the technical effect of the present invention. The mass percentage of each component of the conductive silver paste is as follows: 80% spherical silver powder, 5% glass powder, 1% composite modifier consisting of 0.25% lanthanum oxide and 0.75% methylphenyl polysiloxane precursor, and 14% organic carrier.

[0060] To better understand the present invention, the following performance evaluation tests were performed on the embodiments and comparative examples.

[0061] The adhesion of the silver layer was tested according to the adhesion test requirements (vertical tensile test) in GB / T 17473-2025 "Test Methods for Performance of Electronic Pastes - Conductor Paste Test".

[0062] This experiment tested the adhesion of the silver plating layer. The test substrate was a 6.3mm × 6.3mm × 1mm beryllium oxide ceramic sheet. A 2mm × 2mm electrode pattern was printed in the center of the substrate. After drying at 150℃ for 15 minutes, it was sintered according to the following procedure: peak temperature 850℃, holding time 10 minutes; heating rate: no more than 80℃ / min for 100-300℃, no more than 70℃ / min for 300-500℃, and no more than 60℃ / min for 500-850℃; cooling rate: no more than 60℃ / min for 850-700℃, and no more than 100℃ / min for 700-100℃. After sintering, a silver electrode was fabricated, and nickel and tin-lead metal layers were electroplated onto the silver electrode. Adhesion testing was conducted according to standard requirements at a pull speed of 10mm / min. The process flow diagram is shown below. Figure 2 As shown.

[0063] The test results are shown in Table 1: Table 1. Silver layer adhesion test results Example 1 77.3 Example 2 73.8 Example 3 75.5 Comparative Example 1 Electrode detachment occurred on some products after electroplating, with a maximum pull-out force of 26.8. Comparative Example 2 Electrode detachment occurred on some products after electroplating, with a maximum pull-out force of 42.5. Comparative Example 3 Electrode detachment occurred on some products after electroplating, with a maximum pull-out force of 34.0. Comparative Example 4 56.3 Please refer to Figure 3 And Table 1, by Figure 3 As shown in Table 1, the silver pastes in all embodiments of the present invention exhibit stable adhesion of no less than 70 N after electroplating, which is more than 150% higher than that of conventional commercial silver pastes for alumina, with no silver layer peeling or flaking. Comparative Example 2, which uses only rare earth metal oxides, or Comparative Example 3, which uses only silicon-based precursors, showed significantly lower adhesion than the embodiments of the present invention, indicating that both must be used synergistically to achieve optimal results. When rare earth oxides are used alone, although the rare earth beryllium salt transition phase formed by the solid-phase reaction can provide chemical anchoring points, the micropores generated by sintering shrinkage still exist, allowing the electrolyte to still penetrate along the pores. When silicon-based precursors are used alone, although the SiO2-based modified layer can fill the pores, it lacks chemical bonding with the beryllium oxide ceramic surface, belonging to physical intercalation, resulting in limited improvement in interfacial bonding strength. When both are used synergistically, the rare earth beryllium salt transition phase provides chemical anchoring points, and the SiO2-based modified layer densely fills around these anchoring points, forming a dual interfacial bonding mechanism of chemical bonding and physical filling, thus significantly improving adhesion compared to either method used alone.

[0064] When the mass ratio of rare earth metal oxide to silicon-based precursor exceeds the range required by this invention, the adhesion also decreases significantly, indicating that the ratio of the two has a key impact on the interface modification effect. If there is too much rare earth oxide, the rare earth beryllium salt transition phase is enriched in the interface region after sintering, but the SiO2-based modified layer is insufficient to fill the pores, and channels still exist at the interface. When the mass ratio is higher than 1:2, that is, there is too much silicon-based precursor and the SiO2-based modified layer is too thick. During the sintering cooling stage, residual stress is generated due to the mismatch between the thermal expansion coefficients of the silver layer and the ceramic, which leads to interface cracking and decreased adhesion. The data of Comparative Example 4 confirms this point.

[0065] Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible subranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the range referred to.

[0066] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A conductor silver paste for beryllium oxide ceramic pyrotechnic resistors, characterized in that, The conductor silver paste comprises, by mass percentage, 75%-85% silver powder, 3%-7% glass powder, 0.5%-2% composite modifying additives, and the balance being an organic carrier. The composite modified additive is composed of rare earth metal oxides and silicon-based precursors. The rare earth metal oxides include one or more of lanthanum oxide, cerium oxide, and neodymium oxide; The silicon-based precursor is a methylphenyl polysiloxane precursor; The mass ratio of the rare earth metal oxide to the silicon-based precursor is 1:(0.5-2).

2. The conductor silver paste according to claim 1, characterized in that, The rare earth metal oxide is a nanoparticle with a particle size of less than 100 nm.

3. The conductor silver paste according to claim 1, characterized in that, The molecular formula of the methylphenyl polysiloxane precursor is [Si(CH3)2O]x[Si(CH3)(C6H5)O]y, with a molecular weight of 500-2000 and a viscosity of 50-800 cSt.

4. The conductor silver paste according to claim 1, characterized in that, The silver powder is spherical silver powder with a purity of not less than 99.9% and a particle size of 0.5-1.5μm.

5. The conductor silver paste according to claim 1, characterized in that, The glass powder is a borosilicate calcium system glass powder, which includes 35%-40% silicon dioxide, 35%-40% calcium oxide, 10%-20% aluminum oxide, 5%-10% barium oxide and 0.5%-2% lithium oxide by mass percentage.

6. The conductor silver paste according to claim 1, characterized in that, The conductor silver paste comprises, by mass percentage, 78%-82% silver powder, 4%-6% glass powder, 0.8%-1.5% composite modifying additives, and the balance being an organic carrier.

7. A method for preparing a conductor silver paste for beryllium oxide ceramic pyrotechnic resistors according to any one of claims 1-6, characterized in that, Includes the following steps: The silver powder, the glass powder, and the composite modifier are added to the organic carrier and stirred at room temperature for 8-15 minutes for initial mixing. Then, the mixture is stirred in a planetary gravity mixer to obtain a mixed slurry. The mixed slurry is ground through a rolling process to obtain a ground slurry; The grinding slurry is filtered to remove impurities and degassed under vacuum to obtain the conductor silver paste.

8. The method according to claim 7, characterized in that, The rolling process is repeated 2-4 times until the fineness of the grinding slurry is no greater than 10μm.

9. The method according to claim 7, characterized in that, The mixing process in the planetary gravity mixer involves first mixing at 1500-2000 rpm for 200-300 seconds, and then mixing at 300-500 rpm for 300-400 seconds to obtain the mixed slurry.

10. The use of the conductor silver paste for beryllium oxide ceramic pyrotechnic resistors according to any one of claims 1-6 in the preparation of electrodes for beryllium oxide ceramic pyrotechnic resistors.

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