A highly thixotropic conductive silver paste and its preparation method

Abstract

The present invention relates to the technical field of conductive silver paste, and discloses a highly thixotropic conductive silver paste and a preparation method thereof. The conductive silver paste prepared by the present invention uses spherical silver powder and modified flaky silver powder as the conductive phase, glass powder as the inorganic binder phase, and at the same time adds an organic carrier and mixes and stirs them; the modified flaky silver powder has better conductivity than the flaky silver powder, and has better and more stable dispersibility in the matrix; modified polyurea and hydroxy acrylic resin are introduced into the organic carrier, and by using their synergistic effect, the thixotropy and adhesion of the silver paste are improved. Therefore, the conductive silver paste of the present invention has good application prospects in the fields of electronic products, solar cells, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive silver pastes, and particularly relates to a highly thixotropic conductive silver paste and a preparation method thereof. Background Art

[0002] Conductive silver paste is an electronic functional material integrating polymer materials, powders, and glass, with rheological properties. It is an important material for hybrid integrated circuits, sensitive components, displays, antennas, electromagnetic shielding, and various electronic discrete devices, and has good application prospects in fields such as solar cells, printed circuit boards, touch screens, sensors, and new energy vehicle manufacturing. Conductive silver paste has excellent electrical conductivity and chemical stability and is widely used in the electronics industry. The electrical conductivity, low-resistance performance, thixotropy, etc. of conductive silver paste have a very important impact on the synthesis of materials and will directly affect the comprehensive performance of products.

[0003] The thixotropy of conductive silver paste has a great impact on the yield of circuit printing. For example, viscosity, adhesiveness, adhesion, leveling property, film-forming property, volatility of solvents, etc. will all affect the printing performance of the circuit, resulting in the phenomenon that the conductive circuit falls off from the substrate, rendering the conductive circuit scrapped. Therefore, the thixotropy of conductive silver paste needs to be improved. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a highly thixotropic conductive silver paste and a preparation method thereof.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] A highly thixotropic conductive silver paste, comprising raw materials in the following mass percentages: 75 - 85% composite silver powder, 2 - 4% glass powder, 10 - 25% organic carrier;

[0007] The composite silver powder is composed of spherical silver powder and modified flaky silver powder mixed in a mass ratio of 7 - 9:1 - 3;

[0008] Further, the modified flaky silver powder is prepared by the following steps:

[0009] Step A1: Stir flaky silver powder and 4-mercaptobenzoic acid in absolute ethanol for 10 min, then perform ultrasonic treatment for 30 min, place in a water bath at 40 - 60 °C and react for 3 - 7 h, centrifuge, wash, dry, and grind to obtain carboxylated silver powder;

[0010] Step A2: Stir 2,5-dihydroxyterephthalic acid and nickel nitrate hexahydrate in a mixed solution of N,N-dimethylformamide, deionized water, and ethanol with a volume ratio of 1:1:1 for 30 min, then slowly add a 0.4 mol / L sodium hydroxide solution and stir for 20 min. Next, add carboxylated silver powder and stir for 30 - 50 min. Finally, transfer the mixture to an autoclave and react at 110 - 130 °C for 6 - 8 h. Centrifuge, wash, and dry to obtain modified flaky silver powder;

[0011] Furthermore, in step A1, the dosage ratio of flaky silver powder, 4-mercaptobenzoic acid, and absolute ethanol is 10 g: 0.1 - 0.4 g: 100 mL;

[0012] Furthermore, in step A2, the dosage ratio of 2,5-dihydroxyterephthalic acid, nickel nitrate hexahydrate, the mixed solution, sodium hydroxide solution, and carboxylated silver powder is 0.5 - 1.5 g: 0.6 - 1.8 g: 150 mL: 10 mL: 1 - 3 g.

[0013] The organic carrier comprises raw materials with the following mass percentages: 55 - 65% pine oil, 25 - 35% dibutyl phthalate, 1 - 2% hydroxyacrylic resin, 2 - 5% modified polyurea, and 2 - 4% methyl cellulose;

[0014] The modified polyurea is prepared by the following steps:

[0015] Step B1: Mix p-phenylenediamine and dimethylacetamide and stir evenly. Add diphenylmethane diisocyanate in three portions within 1 h, then raise the temperature to 65 - 75 °C and stir for 3 - 5 h to obtain a polyurea prepolymer;

[0016] Step B2: Raise the temperature of the above polyurea prepolymer to 80 - 90 °C, then add 2,2-dimethylolpropionic acid and dibutyltin dilaurate, and stir under nitrogen for 2.5 - 3.5 h to obtain a polyurea compound;

[0017] Step B3: Add dopamine hydrochloride to the above polyurea compound, and under nitrogen, raise the temperature to 160 - 180 °C for reflux reaction for 2 - 6 h, then raise the temperature to 200 °C and continue to react for 1 - 2 h to obtain modified polyurea;

[0018] Furthermore, in step B1, the dosage ratio of p-phenylenediamine, dimethylacetamide, and diphenylmethane diisocyanate is 0.01 - 0.02 mol: 200 mL: 0.015 - 0.04 mol;

[0019] Furthermore, in step B2, the mass ratio of the polyurea prepolymer, 2,2-dimethylolpropionic acid, and dibutyltin dilaurate is 3 - 8: 0.5 - 2: 0.0001 - 0.0002;

[0020] Further, the mass ratio of dopamine hydrochloride in step B3 to 2,2-dimethylolpropionic acid in step B2 is 0.7 - 2.83:0.5 - 2.

[0021] A preparation method of a highly thixotropic conductive silver paste includes the following steps:

[0022] Step S1: Weigh the raw materials by mass percentage. Add pine oil, dibutyl phthalate, hydroxy acrylic resin, and methyl cellulose into a blender. Under the conditions of 30 - 40 °C and 200 - 400 rpm / min, stir for 1 - 2 h, then add modified polyurea and continue to stir for 40 - 60 min to obtain an organic carrier.

[0023] Step S2: Weigh the raw materials by mass percentage. Mix and stir glass powder and composite silver powder evenly in a blender, then add the organic carrier and stir for 10 - 30 min. Subsequently, pour the obtained slurry into a three-roll grinder and grind it to a fineness of 7 - 10 μm to obtain the highly thixotropic conductive silver paste.

[0024] The beneficial effects of the present invention:

[0025] The conductive silver paste prepared by the present invention uses spherical silver powder and modified flaky silver powder as the conductive phase, and glass powder as the non-bonding phase, and is mixed and stirred with an organic carrier. The modified flaky silver powder has better conductivity compared with flaky silver powder, and has better and more stable dispersibility in the matrix. The organic carrier introduces modified polyurea and hydroxy acrylic resin, and uses their synergistic effect to improve the thixotropy and adhesion of the silver paste. Therefore, the conductive silver paste of the present invention has good application prospects in the fields of electronic products, solar cells, etc.

[0026] In the modified flaky silver powder, first, the reaction between the mercapto group in 4-mercaptobenzoic acid and silver powder is used to prepare carboxylated silver powder; then, the carboxyl group on the surface of the carboxylated silver powder is used to participate in the synthesis of Ni-MOF (Ni-MOF is a nickel-based metal-organic framework) to obtain the modified flaky silver powder. The modified flaky silver powder and spherical silver powder act synergistically as the conductivity in the conductive silver paste, providing excellent conductive performance for the silver paste. Among them, the modified flaky silver powder is prepared by an in-situ synthesis method, and a MOF is coated on the surface of the flaky silver powder. The MOF coating layer can form a protective film on the surface of the silver powder to prevent the aggregation and precipitation between silver powder particles, thereby ensuring the uniform dispersion of silver powder in the conductive silver paste and significantly improving the dispersibility and stability of silver powder. After the conductive silver paste is sintered, continuous conductive networks are formed between silver powder particles, and the MOF coating layer helps to reduce the pores in the sintered film layer and increase the conductive paths between silver powder particles, thereby reducing the sheet resistance of the film layer and improving the comprehensive performance of the silver paste. In addition, the nickel element contained in the MOF layer can also reduce the sintering temperature of the conductive silver paste, enabling the conductive paste to be cured at a lower temperature and being suitable for application scenarios that require low-temperature curing.

[0027] In the modified polyurea, first, the -NH2 group in p-phenylenediamine reacts with the -NCO group in diphenylmethane diisocyanate to obtain a polyurea prepolymer; then, under the action of a catalyst, the terminal isocyanate group in the polyurea prepolymer reacts with the hydroxyl group in 2,2-dimethylolpropionic acid to obtain a polyurea compound; finally, the amino group in dopamine hydrochloride reacts with the carboxyl group in the polyurea compound to obtain the modified polyurea. The addition of the modified polyurea can cooperate with the hydroxyl acrylic resin to improve the thixotropy of the silver paste; this is because the modified polyurea contains a large number of polar groups, such as: urea groups, amide groups, hydroxyl groups, and urethane groups. The presence of these groups can cause strong hydrogen bond interactions between the molecules of the modified polyurea, and the hydrogen bond interactions can form a network structure in the matrix. This structure is destroyed under the action of shear force, resulting in a decrease in the viscosity of the slurry. After the shear force is removed, the hydrogen bonds are re-formed, and the viscosity of the slurry is restored, thereby enabling the matrix to have good thixotropic properties; the urethane group contained in the modified polyurea also exhibits good moisture resistance, improving the moisture resistance of the modified polyurea and effectively reducing the decrease in adhesion caused by poor moisture resistance of the polyurea. In addition, the catechol structure contained in the modified polyurea also improves the adhesion of the conductive silver paste, making the conductive silver paste have excellent adhesion after printing. Specific embodiments

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0029] Example 1: The modified flaky silver powder is prepared by the following steps:

[0030] Step A1: Stir 10 g of flaky silver powder and 0.1 g of 4-mercaptobenzoic acid in 100 mL of absolute ethanol for 10 min, then perform ultrasonic treatment for 30 min, react in a 40 °C water bath for 3 h, centrifuge, wash, dry, and grind to obtain carboxylated silver powder;

[0031] Step A2: Stir 0.5 g of 2,5-dihydroxyterephthalic acid and 0.6 g of nickel nitrate hexahydrate in 150 mL of a mixed solution of N,N-dimethylformamide, deionized water, and ethanol with a volume ratio of 1:1:1 for 30 min, then slowly add 10 mL of 0.4 mol / L sodium hydroxide solution and stir for 20 min, then add 1 g of carboxylated silver powder and stir for 30 min, and finally transfer it to an autoclave and react at 110 °C for 6 h, centrifuge, wash, and dry to obtain the modified flaky silver powder.

[0032] The modified polyurea is prepared by the following steps:

[0033] Step B1: Mix 0.01 mol of p-phenylenediamine and 200 mL of dimethylacetamide and stir evenly. Add 0.015 mol of diphenylmethane diisocyanate in three portions within 1 h, then raise the temperature to 65 °C and stir for reaction for 3 h to obtain a polyurea prepolymer.

[0034] Step B2: Raise the temperature of the above 3 g of polyurea prepolymer to 80 °C, then add 0.5 g of 2,2-bis(hydroxymethyl)propionic acid and 0.0001 g of dibutyltin dilaurate, and stir for reaction for 2.5 h under nitrogen atmosphere to obtain a polyurea compound.

[0035] Step B3: Add 0.7 g of dopamine hydrochloride to the above polyurea compound, and under nitrogen atmosphere, raise the temperature to 160 °C and reflux for reaction for 2 h, then raise the temperature to 200 °C and continue the reaction for 1 h to obtain a modified polyurea.

[0036] Example 2: The modified flaky silver powder is prepared by the following steps:

[0037] Step A1: Mix 10 g of flaky silver powder and 0.25 g of 4-mercaptobenzoic acid in 100 mL of absolute ethanol, stir for 10 min, then perform ultrasonic treatment for 30 min, place in a water bath at 50 °C for reaction for 5 h, centrifuge, wash, dry, and grind to obtain carboxylated silver powder.

[0038] Step A2: Mix 1 g of 2,5-dihydroxyterephthalic acid and 1.2 g of nickel nitrate hexahydrate in 150 mL of a mixed solution of N,N-dimethylformamide, deionized water, and ethanol with a volume ratio of 1:1:1, stir for 30 min, then slowly add 10 mL of 0.4 mol / L sodium hydroxide solution and stir for 20 min, then add 2 g of carboxylated silver powder and stir for 40 min, and finally transfer to an autoclave and react at 120 °C for 7 h, centrifuge, wash, and dry to obtain the modified flaky silver powder.

[0039] The modified polyurea is prepared by the following steps:

[0040] Step B1: Mix 0.015 mol of p-phenylenediamine and 200 mL of dimethylacetamide and stir evenly. Add 0.025 mol of diphenylmethane diisocyanate in three portions within 1 h, then raise the temperature to 70 °C and stir for reaction for 4 h to obtain a polyurea prepolymer.

[0041] Step B2: Raise the temperature of the above 5 g of polyurea prepolymer to 85 °C, then add 1 g of 2,2-bis(hydroxymethyl)propionic acid and 0.00015 g of dibutyltin dilaurate, and stir for reaction for 3 h under nitrogen atmosphere to obtain a polyurea compound.

[0042] Step B3: Add 1.5 g of dopamine hydrochloride to the above polyurea compound, and under nitrogen atmosphere, heat up to 170 °C and reflux for 4 h, then heat up to 200 °C and continue to react for 1.5 h to obtain the modified polyurea.

[0043] Example 3: The modified flaky silver powder is prepared by the following steps:

[0044] Step A1: Stir 10 g of flaky silver powder and 0.4 g of 4-mercaptobenzoic acid in 100 mL of absolute ethanol for 10 min, then perform ultrasonic treatment for 30 min, place in a water bath at 60 °C and react for 7 h, centrifuge, wash, dry, and grind to obtain carboxylated silver powder;

[0045] Step A2: Stir 1.5 g of 2,5-dihydroxyterephthalic acid and 1.8 g of nickel nitrate hexahydrate in 150 mL of a mixed solution of N,N-dimethylformamide, deionized water, and ethanol with a volume ratio of 1:1:1 for 30 min, then slowly add 10 mL of 0.4 mol / L sodium hydroxide solution and stir for 20 min, then add 3 g of carboxylated silver powder and stir for 50 min, finally transfer to an autoclave and react at 130 °C for 8 h, centrifuge, wash, and dry to obtain the modified flaky silver powder.

[0046] The modified polyurea is prepared by the following steps:

[0047] Step B1: Mix 0.02 mol of p-phenylenediamine and 200 mL of dimethylacetamide and stir evenly. Add 0.04 mol of diphenylmethane diisocyanate in three portions within 1 h, then heat up to 75 °C and stir and react for 5 h to obtain the polyurea prepolymer;

[0048] Step B2: Heat the above 8 g of polyurea prepolymer to 90 °C, then add 2 g of 2,2-dimethylolpropionic acid and 0.0002 g of dibutyltin dilaurate, and stir and react under nitrogen atmosphere for 3.5 h to obtain the polyurea compound;

[0049] Step B3: Add 2.83 g of dopamine hydrochloride to the above polyurea compound, and under nitrogen atmosphere, heat up to 180 °C and reflux for 6 h, then heat up to 200 °C and continue to react for 2 h to obtain the modified polyurea.

[0050] Example 4: A preparation method of a highly thixotropic conductive silver paste includes the following steps:

[0051] Step S1: Weigh the raw materials by mass percentage. Add 65% pine oil, 25% dibutyl phthalate, 1% hydroxyacrylic resin, and 2% methyl cellulose to a blender, and stir at 30 °C and 200 rpm for 1 h, then add 2% of the modified polyurea prepared in Example 1 and continue to stir for 40 min to obtain the organic carrier;

[0052] Step S2: Mix spherical silver powder and the modified flaky silver powder prepared in Example 1 at a mass ratio of 7:3 to obtain composite silver powder; then weigh the raw materials by mass percentage, mix 2% glass powder and 75% composite silver powder in a blender and stir evenly, then add 23% organic carrier and stir for 10 min. Subsequently, pour the obtained slurry into a three-roll grinder and grind it to a fineness of 7 μm to obtain a highly thixotropic conductive silver paste.

[0053] Example 5: A method for preparing a highly thixotropic conductive silver paste includes the following steps:

[0054] Step S1: Weigh the raw materials by mass percentage, add 60% pine oil, 32% dibutyl phthalate, 1.5% hydroxy acrylic resin and 3% methyl cellulose into a blender, and stir at 35°C and 300 rpm / min for 1.5 h. Then add 3.5% of the modified polyurea prepared in Example 2 and continue to stir for 50 min to obtain an organic carrier.

[0055] Step S2: Mix spherical silver powder and the modified flaky silver powder prepared in Example 2 at a mass ratio of 8:2 to obtain composite silver powder; then weigh the raw materials by mass percentage, mix 3% glass powder and 80% composite silver powder in a blender and stir evenly, then add 17% organic carrier and stir for 20 min. Subsequently, pour the obtained slurry into a three-roll grinder and grind it to a fineness of 8 μm to obtain a highly thixotropic conductive silver paste.

[0056] Example 6: A method for preparing a highly thixotropic conductive silver paste includes the following steps:

[0057] Step S1: Weigh the raw materials by mass percentage, add 59% pine oil, 30% dibutyl phthalate, 2% hydroxy acrylic resin and 4% methyl cellulose into a blender, and stir at 40°C and 400 rpm / min for 2 h. Then add 5% of the modified polyurea prepared in Example 3 and continue to stir for 60 min to obtain an organic carrier.

[0058] Step S2: Mix spherical silver powder and the modified flaky silver powder prepared in Example 3 at a mass ratio of 9:1 to obtain composite silver powder; then weigh the raw materials by mass percentage, mix 4% glass powder and 85% composite silver powder in a blender and stir evenly, then add 11% organic carrier and stir for 30 min. Subsequently, pour the obtained slurry into a three-roll grinder and grind it to a fineness of 10 μm to obtain a highly thixotropic conductive silver paste.

[0059] Comparative Example 1: This comparative example is a conductive silver paste. The difference from Example 5 is that flaky silver powder is used instead of the modified flaky silver powder prepared in Example 2, and the rest are the same.

[0060] Comparative Example 2: This comparative example is a conductive silver paste. The difference from Example 5 is that commercially available polyurea is used instead of the modified polyurea prepared in Example 2, and the rest are the same.

[0061] Performance test: Conduct performance tests on the conductive silver pastes prepared in Examples 4 - 6 and Comparative Examples 1 - 2:

[0062] Thixotropy: Use a BROOKFIELD rotational viscometer (No. 14 rotor) to measure the viscosities at rotor speeds of 5 r / min and 50 r / min, and calculate the thixotropy index It according to the following formula: It = η5 / η50, where It is the thixotropy index; η5 is the viscosity measured at a rotor speed of 5 r / min; η50 is the viscosity measured at a rotor speed of 50 r / min;

[0063] Sheet resistance: Use an 800 - mesh polyester screen to screen fine conductive lines on the ITO / PET film of a semi - automatic screen printing machine with the conductive silver pastes prepared in Examples 4 - 6 and Comparative Examples 1 - 2. Among them, the fine conductive lines screened are five serpentine lines, and the line width / line pitch are 50 μm / 50 μm, 60 μm / 60 μm, 70 μm / 70 μm, 80 μm / 80 μm, 100 μm / 100 μm in sequence, and the thickness is 2 μm - 6 μm; after baking at 130 °C for 60 minutes, observe under a microscope. The surfaces of the conductive lines with a line width / line pitch of 50 μm and above are flat, and the edges are clear and smooth. Then use a digital multimeter to measure the resistance value of the printed wire, and then calculate the sheet resistance;

[0064] Adhesion: Use the cross - cut test (ITO / PT film) specified by the national standard, 3M 600 tape, pull vertically, ASTM standard; the above test results are shown in Table 1:

[0065] Table 1: Performance test results

[0066]

[0067] It can be seen from Table 1 that after the thixotropy, sheet resistance, and adhesion tests of the conductive silver paste prepared by the present invention, the thixotropy index is between 5.76 - 5.91, the sheet resistance is between 26 mΩ / sq / 10 μm - 29 mΩ / sq / 10 μm, and the adhesion grade is uniformly 5B, indicating that the conductive silver paste has excellent conductivity and adhesion, and also has high thixotropy.

[0068] The above content is only an example and illustration of the concept of the present invention. Those skilled in the art of the present technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the scope defined by the concept of the invention, they should all belong to the protection scope of the present invention.

Claims

1. A highly thixotropic conductive silver paste, characterized in that, It comprises raw materials with the following mass percentages: 75 - 85% of composite silver powder, 2 - 4% of glass powder, and 10 - 25% of organic carrier; The composite silver powder is formed by mixing spherical silver powder and modified flaky silver powder in a mass ratio of 7 - 9:1 - 3; The organic carrier comprises raw materials with the following mass percentages: 55 - 65% of pine oil, 25 - 35% of dibutyl phthalate, 1 - 2% of hydroxy acrylic resin, 2 - 5% of modified polyurea, and 2 - 4% of methyl cellulose; The modified flaky silver powder is prepared by the following steps: Step A1: Stir flaky silver powder and 4 - mercaptobenzoic acid in absolute ethanol for 10 min, then perform ultrasonic treatment for 30 min, place it in a water bath at 40 - 60 °C and react for 3 - 7 h, centrifuge, wash, dry, and grind to obtain carboxylated silver powder; Step A2: Stir 2,5 - dihydroxyterephthalic acid and nickel nitrate hexahydrate in a mixed solution of N,N - dimethylformamide, deionized water, and ethanol with a volume ratio of 1:1:1 for 30 min, then slowly add 0.4 mol / L sodium hydroxide solution and stir for 20 min, then add carboxylated silver powder and stir for 30 - 50 min, finally transfer it to an autoclave and react at 110 - 130 °C for 6 - 8 h, centrifuge, wash, and dry to obtain modified flaky silver powder; The modified polyurea is prepared by the following steps: Step B1: Mix p - phenylenediamine and dimethylacetamide and stir evenly, add diphenylmethane diisocyanate in three portions within 1 h, then raise the temperature to 65 - 75 °C and stir and react for 3 - 5 h to obtain a polyurea prepolymer; Step B2: Raise the temperature of the above polyurea prepolymer to 80 - 90 °C, then add 2,2 - dimethylolpropionic acid and dibutyltin dilaurate, and stir and react for 2.5 - 3.5 h under nitrogen conditions to obtain a polyurea compound; Step B3: Add dopamine hydrochloride to the above polyurea compound, and under nitrogen conditions, raise the temperature to 160 - 180 °C and reflux and react for 2 - 6 h, then raise the temperature to 200 °C and continue to react for 1 - 2 h to obtain modified polyurea.

2. The highly thixotropic conductive silver paste according to claim 1, wherein In step A1, the dosage ratio of flaky silver powder, 4 - mercaptobenzoic acid, and absolute ethanol is 10 g:0.1 - 0.4 g:100 mL.

3. A highly thixotropic conductive silver paste according to claim 1, wherein In step A2, the dosage ratio of 2,5 - dihydroxyterephthalic acid, nickel nitrate hexahydrate, the mixed solution, sodium hydroxide solution, and carboxylated silver powder is 0.5 - 1.5 g:0.6 - 1.8 g:150 mL:10 mL:1 - 3 g.

4. A highly thixotropic conductive silver paste according to claim 1, characterized in that, In step B1, the dosage ratio of p - phenylenediamine, dimethylacetamide, and diphenylmethane diisocyanate is 0.01 - 0.02 mol:200 mL:0.015 - 0.04 mol.

5. A highly thixotropic conductive silver paste according to claim 1, characterized in that, In step B2, the mass ratio of the polyurea prepolymer, 2,2 - dimethylolpropionic acid, and dibutyltin dilaurate is 3 - 8:0.5 - 2:0.0001 - 0.0002.

6. The highly thixotropic conductive silver paste according to claim 1, wherein In step B3, the mass ratio of dopamine hydrochloride and 2,2 - dimethylolpropionic acid in step B2 is 0.7 - 2.83:0.5 - 2.

7. A method for preparing the highly thixotropic conductive silver paste according to any one of claims 1-6, characterized in that, It includes the following steps: Step S1: Weigh the raw materials by mass percentage. Add pine oil, dibutyl phthalate, hydroxy acrylic resin and methyl cellulose into a blender. Stir for 1 - 2 h at 30 - 40 °C and 200 - 400 rpm / min, then add modified polyurea and continue to stir for 40 - 60 min to obtain the organic carrier. Step S2: Weigh the raw materials by mass percentage. Mix and stir glass powder and composite silver powder evenly in a blender, then add the organic carrier and stir for 10 - 30 min. Subsequently, pour the obtained slurry into a three-roll grinder and grind it to a fineness of 7 - 10 μm to obtain the high thixotropic conductive silver paste.

Images