Low-temperature soldering silver paste for high-speed dispensing system and preparation method thereof

Abstract

The application relates to the field of welding materials, in particular to a low-temperature welding silver paste for a high-speed dispensing system and a preparation method thereof. The low-temperature welding silver paste for the high-speed dispensing system is prepared from raw materials including spherical conductive silver powder with an average particle size of 0.5-1.2 microns, ester alcohol carriers and a functional composition. The low-temperature welding silver paste for the high-speed dispensing system prepared through the application can not only maintain the low-temperature welding application effect, but also has the conductive and heat-conductive performance and mechanical strength, can adapt to the high-speed dispensing process, has good flow uniformity, greatly improves the welding quality, ensures excellent waterproof, moisture resistance and corrosion resistance and other performances, fully solves the performance contradiction problem of the existing low-temperature welding materials, maintains excellent comprehensive performance, and meets the increasingly high performance requirement of the welding materials in the existing application field.

Description

Technical Field

[0001] This application relates to the field of welding materials, and more specifically to a low-temperature welding silver paste for high-speed dispensing systems and its preparation method. Background Technology

[0002] With the rapid development of the electronics industry, electronic components are constantly evolving towards miniaturization, high density, and high power, placing higher demands on interconnection technologies. Traditional high-temperature soldering techniques, such as tin-lead soldering, typically operate at temperatures above 200°C, which not only easily leads to thermal damage to thermistor components but also fails to meet the delicate requirements of high-density packaging. Simultaneously, with the industrial application of third-generation wide-bandgap semiconductor devices such as silicon carbide (SiC), their high power density and high-temperature operating characteristics place even more stringent demands on packaging interconnection technologies. Traditional solders are prone to fatigue failure at high temperatures, becoming a key bottleneck restricting the performance release of SiC devices.

[0003] In recent years, low-temperature silver sintering technology has gradually become an effective solution for addressing the connection problems of high-power devices. This technology utilizes the densification of silver nanoparticles at low temperatures (<250℃) to form a conductive layer, possessing the triple advantages of excellent conductivity, heat dissipation, and mechanical strength. However, existing silver sintering technologies typically require specific temperature and pressure conditions, resulting in a complex process flow that is difficult to adapt to the high-efficiency production requirements of high-speed dispensing systems. Furthermore, existing silver sintering pastes are prone to uneven flowability, high porosity after curing, and unstable conductivity during dispensing, failing to meet the stringent welding quality requirements of high-speed dispensing systems. In addition, the silver nanoparticles in existing silver sintering technologies tend to agglomerate at high temperatures, leading to discontinuous conductive pathways and affecting the long-term reliability of the welded joints.

[0004] In high-speed dispensing systems, soldering silver paste needs to possess good flowability, rapid curing characteristics, high electrical and thermal conductivity, and excellent mechanical strength. While existing silver solder pastes offer good flowability, they require high-temperature soldering, which doesn't match the low-temperature requirements of high-speed dispensing systems. Low-temperature conductive silver pastes, although curable at low temperatures, primarily offer conductivity suitable for electronic component connections, not soldering, and their mechanical strength is insufficient. While low-temperature silver sintering technology offers performance advantages, its complex process contradicts the high efficiency of high-speed dispensing systems, hindering large-scale application. Summary of the Invention

[0005] In summary, existing technologies suffer from several technical problems, including excessively high welding temperatures, difficulty in meeting the welding requirements of thermistor components, difficulty in balancing the electrical and thermal conductivity and mechanical strength of low-temperature welding materials, and uneven flowability of welding materials during high-speed dispensing, leading to unstable welding quality. These problems severely restrict the application and development of soldering silver paste in the manufacturing of high-power electronic devices. There is an urgent need to develop a low-temperature soldering silver paste suitable for high-speed dispensing systems to overcome these technical bottlenecks. This application proposes a low-temperature soldering silver paste specifically for high-speed dispensing systems and its preparation method to solve the aforementioned technical problems and meet the higher performance requirements of existing application fields.

[0006] A low-temperature soldering silver paste for high-speed dispensing systems comprises at least spherical conductive silver powder with an average D50 particle size of 0.5~1.2μm, an ester alcohol carrier, and a functional composition.

[0007] Preferably, the mass ratio of the spherical conductive silver powder, the ester alcohol carrier, and the functional composition is (70~80):(15~25):(4~8).

[0008] More preferably, the mass ratio of the spherical conductive silver powder, the ester alcohol carrier, and the functional composition is (70~75):(17~21):(5.5~7).

[0009] More preferably, the average D50 particle size of the spherical conductive silver powder is 0.6~0.9μm.

[0010] Preferably, the ester alcohol carrier is at least one selected from 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, dodecyl alcohol ester, butyl carbitol, and terpineol.

[0011] More preferably, the ester alcohol support is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate or terpineol.

[0012] More preferably, the ester alcohol carrier is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0013] Preferably, the functional composition is a combination of zirconium acetylacetonate and perfluoropolyether propyltriethoxysilane.

[0014] Preferably, the mass ratio of zirconium acetylacetonate to perfluoropolyether propyltriethoxysilane is (3~4):(0.6~1).

[0015] Preferably, the mass ratio of zirconium acetylacetonate to perfluoropolyether propyltriethoxysilane is (3.2~3.5):(0.6~0.8).

[0016] The functional composition incorporated in this application not only achieves low-temperature, high-efficiency welding but also constructs an inherent, long-lasting protective mechanism for the silver paste, ensuring its excellent overall performance. During the low-temperature sintering process of the silver paste, the active zirconium not only catalyzes and promotes the diffusion of silver atoms and the formation of sintering necks at lower temperatures, improving densification and mechanical strength, but also subsequently transforms into a stable metal oxide, firmly anchoring at the silver grain boundaries, thereby significantly passivating the silver surface and inhibiting the initiation of electrochemical corrosion.

[0017] On the other hand, the synergy between low surface energy perfluoropolyether segments and hydrolyzable siloxanes forms a continuous, dense, and extremely stable hydrophobic and oleophobic protective film on the outside and within the pores of the sintered silver conductive network framework through cross-linking. This physicochemical barrier effectively isolates the silver conductive pathway from external moisture, oxygen, and various corrosive media, fundamentally improving the environmental reliability of the connection points.

[0018] Preferably, the low-temperature soldering silver paste for high-speed dispensing systems further includes functional additives, thixotropic agents, dispersants, coupling agents, defoamers, stabilizers, and leveling agents in its raw materials.

[0019] Preferably, the mass ratio of the spherical conductive silver powder, functional additives, and coupling agent is (70~80):(3~8):(0.5~1.5).

[0020] More preferably, the mass ratio of the spherical conductive silver powder, functional additives and coupling agent is (70~75):(4~6):(0.7~1.2).

[0021] Preferably, the functional additive is a combination of copper 2-ethylhexanoate and silver neodecanoate.

[0022] Preferably, the mass ratio of copper 2-ethylhexanoate to silver neodecanoate is (2.5~3.5):(1~1.2).

[0023] Preferably, the thixotropic agent is at least one selected from fumed silica, hydrogenated castor oil, organobentonite, and polyamide wax.

[0024] More preferably, the thixotropic agent is fumed silica or organobentonite.

[0025] More preferably, the thixotropic agent is fumed silica with an average particle size of 15-50 nm.

[0026] Preferably, the dispersant is at least one selected from block copolymers, polyurethanes, and polysiloxanes.

[0027] More preferably, the dispersant is a block copolymer or polyurethane.

[0028] More preferably, the dispersant is a block copolymer.

[0029] Preferably, the coupling agent is at least one selected from γ-glycidoxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, methacryloyloxypropyltrimethoxysilane, and mercaptopropyltrimethoxysilane.

[0030] More preferably, the coupling agent is γ-glycidoxypropyltrimethoxysilane or mercaptopropyltrimethoxysilane.

[0031] Preferably, the defoamer is at least one of silicone defoamers.

[0032] Preferably, the stabilizer is 2-phenylbenzimidazole-5-sulfonic acid.

[0033] Preferably, the leveling agent is at least one of polyacrylate, fluorocarbon polymer and acetate.

[0034] Preferably, the leveling agent is a polyacrylate or a fluorocarbon polymer.

[0035] More preferably, the leveling agent is polyacrylate.

[0036] More preferably, the low-temperature soldering silver paste for high-speed dispensing systems comprises, by weight, the following raw materials: 70-80 parts of spherical conductive silver powder, 15-25 parts of ester alcohol carrier, 4-8 parts of compound functional composition, 3-8 parts of functional additives, 0.5-2 parts of thixotropic agent, 0.3-1.5 parts of dispersant, 0.5-1.5 parts of coupling agent, 0.1-0.5 parts of defoamer, 0.2-0.6 parts of stabilizer, and 0.2-0.7 parts of leveling agent.

[0037] A method for preparing low-temperature soldering silver paste for high-speed dispensing systems includes the following steps: S1: In the main tank of a planetary mixer, add the ester alcohol carrier, the functional composition, the functional additive, the defoamer, the dispersant, the coupling agent, the stabilizer, and the coupling agent in sequence, and start the mixer to stir until all liquid and solution components are mixed evenly; S2: Add spherical conductive silver powder in three batches, reducing the rotation frequency, and stirring briefly after each addition until the silver powder is initially wetted before adding the next batch. After all the silver powder has been added, increase the mixer speed and stir and mix under a vacuum of -0.095 MPa to form a uniform paste; S3: Adjust the mixer speed to a low rotation frequency, slowly and evenly add the thixotropic agent. After all the agent has been added, continue stirring under a vacuum of -0.095 MPa. Finally, degas the final paste under a low rotation frequency and a vacuum of -0.098 MPa. After degassing, filter the paste using a 400-500 mesh stainless steel screen to obtain the final product.

[0038] More preferably, the preparation method of low-temperature soldering silver paste for high-speed dispensing systems specifically includes the following steps: S1: In the main tank of a planetary mixer, add the ester alcohol carrier, the functional composition, the functional additive, the defoamer, the dispersant, the coupling agent, the stabilizer, and the coupling agent in sequence. Start the mixer and stir for 10-15 minutes at a revolution frequency of 15-20 Hz and a rotation frequency of 10-15 Hz until all liquid and solution components are uniformly mixed; S2: Add spherical conductive silver powder in three batches, reducing the revolution frequency to 5-8 Hz. After each addition, stir briefly until the silver powder is initially wetted before adding the next batch. After all the silver powder has been added, increase the mixer speed to a revolution frequency of 25-30 Hz and a rotation frequency of 20-25 Hz, and stir and mix for 60-65 minutes under a vacuum of -0.095 MPa to form a uniform paste; S3: Adjust the mixer speed to a revolution frequency of 8-10 Hz. Add the thixotropic agent slowly and evenly at a frequency of 4-5 Hz. After all the agent has been added, restore the stirring speed and continue stirring for 30-35 minutes under a vacuum of -0.095 MPa. Finally, degas the final paste at a slow speed of 4-5 Hz under a vacuum of -0.098 MPa for 10-15 minutes. After degassing, filter the paste using a 400-500 mesh stainless steel screen to obtain the final product.

[0039] The beneficial effects of this application are:

[0040] 1. The low-temperature welding silver paste for high-speed dispensing systems finally obtained in this application not only maintains the effect of low-temperature welding applications, but also takes into account the electrical and thermal conductivity as well as mechanical strength. It can also adapt to the high-speed dispensing process, maintain good flow uniformity, and significantly improve welding quality while ensuring excellent waterproof, moisture-proof, and corrosion-resistant properties. It fully solves the performance contradiction problem of existing low-temperature welding materials, maintains excellent comprehensive performance, and meets the increasingly high performance requirements of welding materials in current application fields.

[0041] 2. The functional composition incorporated in this application, while achieving low-temperature, high-efficiency welding, also constructs an inherent, long-lasting protective mechanism for the silver paste, which is a prerequisite for ensuring its excellent overall performance. During the low-temperature sintering process of the silver paste, the active zirconium not only catalyzes and promotes the diffusion of silver atoms and the formation of sintering necks at lower temperatures, improving densification and mechanical strength, but also subsequently transforms into a stable metal oxide, firmly anchoring at the silver grain boundaries, thereby significantly passivating the silver surface and inhibiting the initiation of electrochemical corrosion.

[0042] 3. The soldering silver paste prepared in this application enables rapid sintering in low-temperature environments below 200℃, effectively avoiding damage to heat-sensitive components. At the same time, its excellent shear thinning characteristics and high thixotropic index ensure that there is no stringing or splashing during high-speed dispensing, and the lines are uniform and consistent. Moreover, the connection points formed after sintering exhibit excellent comprehensive performance, fully meeting the stringent requirements of high power density devices for electrical connection and heat dissipation capabilities. It can also effectively resist salt spray corrosion, demonstrating superior long-term environmental reliability and service life. It is particularly suitable for high-reliability microelectronic packaging in harsh conditions such as automotive electronics and outdoor equipment. Attached Figure Description

[0043] Figure 1 This is a photograph of the low-temperature soldering silver paste prepared for a high-speed dispensing system according to this embodiment. Detailed Implementation

[0044] Example 1

[0045] A low-temperature soldering silver paste for high-speed dispensing systems, comprising, by weight, the following raw materials: 75 parts spherical conductive silver powder, 20 parts ester alcohol carrier, 6.5 parts compounding functional composition, 5.5 parts functional additives, 1.2 parts thixotropic agent, 0.8 parts dispersant, 0.8 parts coupling agent, 0.3 parts defoamer, 0.4 parts stabilizer, and 0.6 parts leveling agent.

[0046] The average D50 particle size of the spherical conductive silver powder is 0.8 μm.

[0047] The ester alcohol carrier is 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

[0048] The functional composition is a composition of zirconium acetylacetonate and perfluoropolyether propyltriethoxysilane in a mass ratio of 3.3:0.7.

[0049] The functional additive is a combination of copper 2-ethylhexanoate and silver neodecanoate in a mass ratio of 3:1.

[0050] The thixotropic agent is fumed silica with an average particle size of 20 nm; the dispersant is block copolymer BYK-180; the coupling agent is γ-glycidyl etheroxypropyltrimethoxysilane; the defoamer is TEGO 810; the stabilizer is 2-phenylbenzimidazole-5-sulfonic acid; and the leveling agent is polyacrylate BYK-358N.

[0051] A method for preparing low-temperature soldering silver paste for high-speed dispensing systems includes the following steps: S1: In the main tank of a planetary mixer, add the ester alcohol carrier, the functional composition, the functional additive, the defoamer, the dispersant, the coupling agent, the stabilizer, and the coupling agent in sequence. Start the mixer and stir for 12 minutes at a revolution frequency of 20 Hz and a rotation frequency of 15 Hz until all liquid and solution components are uniformly mixed; S2: Add spherical conductive silver powder in three batches, reducing the revolution frequency to 6 Hz. After each addition, stir briefly until the silver powder is initially wetted before adding the next batch. After all the silver powder has been added, increase the mixer speed to a revolution frequency of 30 Hz and a rotation frequency of 25 Hz, and stir and mix for 65 minutes under a vacuum of -0.095 MPa to form a uniform paste; S3: Adjust the mixer speed to a revolution frequency of 10 Hz, slowly and uniformly add the thixotropic agent. After all the agent has been added, restore the speed and stir under a vacuum of -0.095 MPa. Under MPa conditions, continue stirring for 35 min. Finally, degas the final paste at a slow speed of 5 Hz under a vacuum of -0.098 MPa for 12 min. After degassing, filter the paste using a 500-mesh stainless steel sieve to obtain the final product.

[0052] The actual product of the low-temperature soldering silver paste for high-speed dispensing systems prepared in this embodiment is shown below. Figure 1 As shown.

[0053] Example 2

[0054] This embodiment differs from Embodiment 1 only in the following way: A low-temperature soldering silver paste for a high-speed dispensing system, by weight, comprises: 70 parts of spherical conductive silver powder, 20 parts of ester alcohol carrier, 5.5 parts of compound functional composition, 5.5 parts of functional additives, 1.2 parts of thixotropic agent, 0.8 parts of dispersant, 0.8 parts of coupling agent, 0.3 parts of defoamer, 0.4 parts of stabilizer, and 0.6 parts of leveling agent.

[0055] The remaining implementation methods are the same.

[0056] Example 3

[0057] This embodiment differs from Embodiment 1 only in the following aspects: A low-temperature soldering silver paste for a high-speed dispensing system, by weight, comprises: 80 parts of spherical conductive silver powder, 20 parts of ester alcohol carrier, 6.5 parts of compound functional composition, 3.5 parts of functional additives, 1.2 parts of thixotropic agent, 0.8 parts of dispersant, 0.8 parts of coupling agent, 0.3 parts of defoamer, 0.4 parts of stabilizer, and 0.6 parts of leveling agent.

[0058] The remaining implementation methods are the same.

[0059] Comparative Example 1

[0060] This comparative example differs from Example 1 only in the following aspects: A low-temperature soldering silver paste for a high-speed dispensing system, by weight, comprises: 80 parts of spherical conductive silver powder, 20 parts of ester alcohol carrier, 6.5 parts of compound functional composition, 1.5 parts of functional additives, 1.2 parts of thixotropic agent, 0.8 parts of dispersant, 0.8 parts of coupling agent, 0.3 parts of defoamer, 0.4 parts of stabilizer, and 0.6 parts of leveling agent.

[0061] The remaining implementation methods are the same.

[0062] Comparative Example 2

[0063] This comparative example differs from Example 1 only in the following aspects: A low-temperature soldering silver paste for a high-speed dispensing system, by weight, comprises: 80 parts of spherical conductive silver powder, 20 parts of ester alcohol carrier, 2.5 parts of functional compound, 6.5 parts of polymerization aid, 1.2 parts of thixotropic agent, 0.8 parts of dispersant, 0.8 parts of coupling agent, 0.3 parts of defoamer, 0.4 parts of stabilizer, and 0.6 parts of leveling agent.

[0064] The remaining implementation methods are the same.

[0065] Comparative Example 3

[0066] This comparative example differs from Example 1 only in the following way: the functional composition is a combination of zirconium acetylacetonate and perfluoropolyetherpropyltriethoxysilane in a mass ratio of 3.8:0.2.

[0067] The remaining implementation methods are the same.

[0068] Comparative Example 4

[0069] This comparative example differs from Example 1 only in the following way: the functional composition is a combination of zirconium acetylacetonate and perfluoropolyetherpropyltriethoxysilane in a mass ratio of 2:1.5.

[0070] The remaining implementation methods are the same.

[0071] Comparative Example 5

[0072] This comparative example differs from Example 1 only in the following way: the functional additive is a combination of copper 2-ethylhexanoate and silver neocaprate in a mass ratio of 6:1.

[0073] The remaining implementation methods are the same.

[0074] Comparative Example 6

[0075] This comparative example differs from Example 1 only in the following way: the functional additive is a combination of copper 2-ethylhexanoate and silver neocaprate in a mass ratio of 1:1.2.

[0076] The remaining implementation methods are the same.

[0077] Performance testing

[0078] 1. Rheological properties: The test referenced ASTM D4287, and the thixotropic index at the final high and low shear speeds was recorded in Table 1.

[0079] 2. Conductivity: The conductivity of the silver paste prepared in the examples and comparative examples was tested using a conductivity tester. The average value of 10 tests was recorded in Table 1.

[0080] 3. Resistance to damp heat aging: The test references JESD22-A101D. The change rate of volume resistivity of the silver paste line is taken, and the result is the average of 10 tests, which is recorded in Table 1.

[0081] 4. Shear strength of welded joint: The test reference is JIS Z3198-7, and the result is the average of 10 tests.

[0082] 5. Salt spray corrosion resistance: The test is conducted in accordance with ASTM B117. The sample is placed in a salt spray chamber at 35°C with continuous spraying of 5% sodium chloride solution for 168 hours. After the test, the surface corrosion is observed, and the resistance before and after the test is measured to obtain the resistance change rate. The result is the average of 10 tests.

[0083] Table 1 Performance Test Results

[0084] Example Rheological properties Electrical conductivity (μΩ·cm) Resistance to damp heat - Change rate of volume resistivity (%) Solder joint shear strength (MPa) Salt spray resistance - volume resistivity change rate (%) Example 1 8 4.02 3.69 31.2 6.87 Example 2 8 4.14 3.84 30.5 7.01 Example 3 8 4.08 3.81 31.4 6.79 Comparative Example 1 6 4.89 5.14 26.5 9.67 Comparative Example 2 6 4.74 5.58 28.2 10.14 Comparative Example 3 7 4.65 4.69 29.4 8.81 Comparative Example 4 7 4.54 4.44 28.8 8.07 Comparative Example 5 6 4.39 4.21 30.1 7.97 Comparative Example 6 7 4.36 4.41 28.7 7.89

[0085] Based on the performance test results of the final embodiments and comparative examples, the embodiments, by adopting the corresponding technical solution defined in this application, incorporate a functional composition that, while achieving low-temperature, high-efficiency welding, constructs an inherent long-term protective mechanism for the silver paste, ensuring its excellent overall performance. During the low-temperature sintering process of the silver paste, the active zirconium not only catalyzes and promotes the diffusion of silver atoms and the formation of sintering necks at lower temperatures, improving densification and mechanical strength, but also subsequently transforms into a stable metal oxide, firmly anchoring at the silver grain boundaries, thereby significantly passivating the silver surface and inhibiting the initiation of electrochemical corrosion. Furthermore, the functional additives construct a high-performance organic carrier network for the silver paste during high-speed dispensing and low-temperature welding, achieving a good balance between fluidity and final mechanical strength. In contrast, the comparative examples, employing different technical solutions than those defined in this application, exhibited significantly reduced effects, resulting in a marked decrease in the final overall performance.

Claims

1. A low-temperature soldering silver paste for high-speed dispensing systems, characterized in that: The raw materials include at least spherical conductive silver powder with an average D50 particle size of 0.5~1.2μm, ester alcohol carrier, and a functional composition. The mass ratio of the spherical conductive silver powder, the ester alcohol carrier, and the functional composition is (70~80):(15~25):(4~8); The functional composition is a combination of zirconium acetylacetonate and perfluoropolyetherpropyltriethoxysilane in a mass ratio of (3~4):(0.6~1).

2. The low-temperature soldering silver paste for high-speed dispensing systems according to claim 1, characterized in that: The ester alcohol carrier is at least one selected from 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, dodecyl alcohol ester, butyl carbitol, and terpineol.

3. The low-temperature soldering silver paste for high-speed dispensing systems according to claim 2, characterized in that: The average D50 particle size of the spherical conductive silver powder is 0.6~0.9μm.

4. The low-temperature soldering silver paste for high-speed dispensing systems according to claim 3, characterized in that: The low-temperature soldering silver paste used in high-speed dispensing systems also includes functional additives, thixotropic agents, dispersants, coupling agents, defoamers, stabilizers, and leveling agents in its raw materials.

5. The low-temperature soldering silver paste for high-speed dispensing systems according to claim 4, characterized in that: The mass ratio of the spherical conductive silver powder, functional additives, and coupling agent is (70~80):(3~8):(0.5~1.5).

6. The low-temperature soldering silver paste for a high-speed dispensing system according to claim 5, characterized in that: The functional additive is a combination of copper 2-ethylhexanoate and silver neodecanoate, with a mass ratio of (2.5~3.5):(1~1.2).

7. The low-temperature soldering silver paste for a high-speed dispensing system according to claim 6, characterized in that: The thixotropic agent is at least one of fumed silica, hydrogenated castor oil, organobentonite, and polyamide wax.

8. The low-temperature soldering silver paste for a high-speed dispensing system according to claim 7, characterized in that: The dispersant is at least one of block copolymers, polyurethanes, and polysiloxanes.

9. The low-temperature soldering silver paste for a high-speed dispensing system according to claim 8, characterized in that: The low-temperature soldering silver paste for high-speed dispensing systems comprises, by weight, the following raw materials: 70-80 parts of spherical conductive silver powder, 15-25 parts of ester alcohol carrier, 4-8 parts of compound functional composition, 3-8 parts of functional additives, 0.5-2 parts of thixotropic agent, 0.3-1.5 parts of dispersant, 0.5-1.5 parts of coupling agent, 0.1-0.5 parts of defoamer, 0.2-0.6 parts of stabilizer, and 0.2-0.7 parts of leveling agent.

10. A method for preparing low-temperature soldering silver paste for a high-speed dispensing system according to any one of claims 4 to 9, characterized in that: Includes the following steps: S1: In the main tank of the planetary mixer, add the ester alcohol carrier, compound functional composition, functional additives, defoamer, dispersant, coupling agent, stabilizer and coupling agent in sequence, and start the mixer to stir until all liquid and solution components are mixed evenly; S2: Add spherical conductive silver powder in three batches, reduce to the revolution frequency, stir briefly after each addition until the silver powder is initially wetted, and then add the next batch. After the silver powder is added, increase the mixer speed and stir and mix under a vacuum of -0.095MPa to form a uniform paste; S3: Adjust the mixer speed to a low revolution frequency, slowly and evenly add the thixotropic agent. After all the agent has been added, continue stirring under a vacuum of -0.095MPa. Finally, degas the final paste under a low revolution frequency and a vacuum of -0.098MPa. After degassing, filter the paste using a 400~500 mesh stainless steel screen to obtain the final product.

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