High-temperature-resistant and high-humidity-resistant low-temperature halogen-free conductive silver paste, and preparation method therefor

Abstract

A high-temperature-resistant and high-humidity-resistant low-temperature halogen-free conductive silver paste, and a preparation method therefor, relating to the field of conductive pastes. The preparation method comprises the following steps: weighing a polymer resin and a solvent, stirring in a dissolving kettle until the mixture is transparent, and using a screen for filtering to remove impurities, thereby obtaining a carrier; putting metal silver powder, the carrier, a thixotropic agent, an adhesion promoter, a hardening agent, and a dispersing agent into a high-speed disperser for high-speed dispersion to obtain a uniform paste; and grinding and dispersing the paste in a three-roller mill, and adjusting the distance between rollers to adjust the fineness and viscosity of the silver paste, thereby obtaining the high-temperature-resistant and high-humidity-resistant low-temperature halogen-free conductive silver paste. Compared with the prior art, the prepared silver paste has advantages such as meeting the environmental protection requirements for silver paste, whilst ensuring resistance, hardness, bending performance and the like.

Description

A high temperature and high humidity resistant low temperature halogen-free conductive silver paste and its preparation method Technical Field

[0001] The present invention relates to the field of conductive paste, in particular to a low-temperature halogen-free conductive silver paste that is resistant to high temperature and high humidity and a preparation method thereof. Background Art

[0002] With the rapid development of electronic products, people's lives have been qualitatively improved, and the manufacturing of the microelectronics industry has become a fine, three-dimensional processing and molding. In the manufacture of devices such as TFT-LCD, Touch Panel, and LED, these microelectronic devices are required to be resistant to high temperature and high humidity in certain special application environments, and have a small resistance change rate (i.e., good stability). Therefore, the preparation of functional pastes for printed circuits that meet performance requirements plays a vital role.

[0003] With the introduction of the ROHS and REACH directives for electronic products, the use of halogen-containing slurries that pose a pollution hazard has been restricted, and replacing halogen-containing slurries with halogen-free slurries will become a development trend.

[0004] At present, most of the silver pastes used by domestic customers who use low-temperature pastes are still halogen silver paste products, and a small number use low-temperature halogen-free silver paste and other products. However, some low-temperature halogen-free silver paste and other products have the following problems: Although low-temperature halogen-free silver paste products have low resistance, good hardness and bendability, they have low thixotropy and are not easy to flow, making them difficult to use. In addition, their resistance to high temperature and high humidity and poor adhesion limit their use.

[0005] Chinese patent application CN103165219A discloses a halogen-free silver paste for large keyboards and a preparation method thereof. The halogen-free silver paste includes the following components and contents (by weight): 48% to 53% metallic silver powder; 7.5% to 9.5% polymer resin; 0.5% to 1.0% curing agent; 0.2% to 0.6% adhesion promoter; 0.1% to 0.5% hardener; 0.5% to 0.8% thickener; and 35% to 43% solvent. The components are mixed, dissolved, ground, and filtered to obtain a halogen-free silver paste for large keyboards. However, due to the selection of additives and the combination of silver powder types, the paste prepared by this patent has some deficiencies in high temperature and high humidity performance.

[0006] Summary of the Invention

[0007] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a low-temperature halogen-free conductive silver paste and its preparation method that not only meets the technical requirements of low-temperature silver paste products such as resistance, hardness and bendability, but also has high temperature and humidity resistance, excellent adhesion and thixotropy.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] A low-temperature, high-humidity resistant, halogen-free conductive silver paste comprising the following components in parts by weight:

[0010] Furthermore, the metallic silver powder is selected from flaky silver powders of different particle sizes, wherein three flaky silver powders of different particle sizes are selected: the particle size of flaky silver powder a is 5.0-8.0 μm, and the tap density is 2.7-3.1 g / mL; the average particle size of flaky silver powder b is 3.0-4.0 μm, and the tap density is 2.0-3.0 g / mL; the average particle size of flaky silver powder c is 1.0-2.0 μm, and the tap density is 0.8-1.5 g / mL.

[0011] Furthermore, the polymer resin is polyurethane resin.

[0012] Furthermore, the solvent includes at least one of terpineol, divalent acid ester, isophorone or propylene glycol methyl ether acetate.

[0013] Furthermore, the thixotropic agent includes at least one of organic bentonite, polyurea, fumed silica, and hydrogenated castor oil.

[0014] Furthermore, the dispersant includes at least one of polyethylene glycol, oleyl amino oleate, and polyethylene wax.

[0015] Furthermore, the adhesion promoter is polyurea, and the hardener is polyethylene wax.

[0016] A method for preparing a low-temperature, high-humidity resistant, low-temperature, halogen-free conductive silver paste comprises the following steps:

[0017] S1: Take a polymer resin and a solvent in a dissolving kettle and stir until transparent, then filter with a mesh to remove impurities to obtain a carrier;

[0018] S2: Place the metallic silver powder, the carrier prepared in step S1, the thixotropic agent, the adhesion promoter, the hardening agent, and the dispersant in a high-speed disperser for high-speed dispersion to obtain a uniform slurry;

[0019] S3: Grind and disperse the slurry obtained in step S2 in a three-roll mill, adjust the distance between the rollers, and adjust the fineness and viscosity of the silver paste to prepare a low-temperature, high-humidity resistant, low-temperature halogen-free conductive silver paste.

[0020] Furthermore, in step S1, the mesh size of the sieve is 250-300 meshes.

[0021] Furthermore, in step S3, the fineness of the silver paste is controlled to be 0-15 μm, and the viscosity is controlled to be 9-31 Pa·S.

[0022] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0023] Compared with the prior art, the present invention adopts halogen-free raw materials, meets the environmental protection requirements of silver paste while ensuring resistance, hardness, bendability and other aspects, and produces a low-temperature halogen-free conductive silver paste that is resistant to high temperature and high humidity, and has particularly good adhesion and thixotropy. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] The following examples are implemented based on the above technical solutions of the present invention, and provide detailed implementation methods and specific operating processes, but the protection scope of the present invention is not limited to the following examples.

[0026] The following are more detailed implementation cases, which further illustrate the technical solutions of the present invention and the technical effects that can be obtained.

[0027] In the following examples, unless otherwise specified, raw materials, reagents or processing techniques are all conventional commercially available products or conventional processing techniques in the art.

[0028] Example 1

[0029] This embodiment provides a low-temperature, high-humidity resistant, low-temperature, halogen-free conductive silver paste and a preparation method thereof:

[0030] In this embodiment, the raw materials are as follows:

[0031] Flake metal silver powder a20kg, flake metal silver powder b20kg, flake metal silver powder c10kg, polyurethane resin 9.5kg, solvent 36.5kg, thixotropic agent 2kg, adhesion promoter 0.5kg, hardener 0.5kg, dispersant 1kg, wherein the metallic silver powder used is flake silver powder (all purchased from Zhejiang Changfeng Precious Metal Powder Co., Ltd.), flake silver powder a particle size of 5.5μm, and tap density of 2.8g / mL; flake silver powder b particle size of 3.5μm, and tap density of 2.3g / mL; flake silver powder c particle size of 1.3μm, and tap density of 1.0g / mL, the polymer resin used is acrylic polyurethane resin, the organic solvent used is divalent ester, the thixotropic agent used is organic bentonite, the adhesion promoter used is polyurea, the hardener used is polyethylene wax, and the dispersant used is polyethylene glycol, and the used agents are all purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0032] The preparation process is as follows:

[0033] (1) Weighing the polyurethane resin and the dibasic acid ester according to the above mass, stirring in a dissolving kettle until transparent, and filtering through a 250-300 mesh sieve to remove impurities to obtain a carrier;

[0034] (2) Weighing the metallic silver powder, the carrier obtained in step (1), organic bentonite, polyurea, polyethylene wax and polyethylene glycol according to the above mass, placing them in a high-speed disperser for high-speed dispersion (3000 r / min, 5 min) to obtain a uniform slurry;

[0035] (3) The slurry obtained in step (2) is ground and dispersed in a three-roll mill. The mill speed sequence is adjusted to make the dispersion more uniform. The spacing between the rollers is adjusted to make the fineness of the silver paste reach 12 μm. The viscosity is adjusted to 15 Pa·s by fine-tuning the solvent to prepare a light-colored, UV-resistant, low-temperature, high-temperature, and high-humidity-resistant titanium-containing conductive paste.

[0036] Example 2

[0037] This embodiment provides a low-temperature, high-humidity resistant, low-temperature, halogen-free conductive silver paste and a preparation method thereof:

[0038] In this embodiment, the raw materials are as follows:

[0039] 20kg of flaky metal silver powder a, 20kg of flaky metal silver powder b, 10kg of flaky metal silver powder c, 9.5kg of polyurethane resin, 37.5kg of solvent, 1.2kg of thixotropic agent, 0.4kg of adhesion promoter, 0.4kg of hardener, and 1kg of dispersant, wherein the metal silver powder used is flaky silver powder (all purchased from Zhejiang Changfeng Precious Metal Powder Co., Ltd.), the particle size of flaky silver powder a is 5.5μm, and the tap density is 2.8g / mL; the particle size of flaky silver powder b is 3.5μm, and the tap density is 2.3g / mL; the particle size of flaky silver powder c is 1.0μm, and the tap density is 0.8g / mL, the polymer resin used is acrylic polyurethane resin, the organic solvent used is divalent acid ester, the thixotropic agent used is organic bentonite, the adhesion promoter used is polyurea, the hardener used is polyethylene wax, and the dispersant used is polyethylene glycol;

[0040] The preparation process is as follows:

[0041] (1) Weighing the polyurethane resin and the dibasic acid ester according to the above mass, stirring in a dissolving kettle until transparent, and filtering through a 250-300 mesh sieve to remove impurities to obtain a carrier;

[0042] (2) weighing the metallic silver powder, the carrier obtained in step (1), organic bentonite, polyurea, polyethylene wax and polyethylene glycol according to the above mass and placing them in a high-speed disperser for high-speed dispersion to obtain a uniform slurry;

[0043] (3) The slurry obtained in step (2) is ground and dispersed in a three-roll mill. The mill speed sequence is adjusted to make the dispersion more uniform. The spacing between the rollers is adjusted to make the fineness of the silver paste reach 10 μm. The viscosity is adjusted to 11 Pa·s by fine-tuning the solvent to prepare a light-colored, UV-resistant, low-temperature, high-temperature, and high-humidity-resistant titanium-containing conductive paste.

[0044] Example 3

[0045] This embodiment provides a low-temperature, high-humidity resistant, low-temperature, halogen-free conductive silver paste and a preparation method thereof:

[0046] In this embodiment, the raw materials are as follows:

[0047] 20kg of flaky metal silver powder a, 20kg of flaky metal silver powder b, 10kg of flaky metal silver powder c, 9kg of polyurethane resin, 38.8kg of solvent, 0.8kg of thixotropic agent, 0.2kg of adhesion promoter, 0.2kg of hardener, and 1kg of dispersant, wherein the metal silver powder used is flaky silver powder (all purchased from Zhejiang Changfeng Precious Metal Powder Co., Ltd.), the particle size of flaky silver powder a is 5.5μm, and the tap density is 2.8g / mL; the particle size of flaky silver powder b is 3.5μm, and the tap density is 2.3g / mL; the particle size of flaky silver powder c is 1.0μm, and the tap density is 0.8g / mL, the polymer resin used is acrylic polyurethane resin, the organic solvent used is divalent acid ester, the thixotropic agent used is organic bentonite, the adhesion promoter used is polyurea, the hardener used is polyethylene wax, and the dispersant used is polyethylene glycol;

[0048] The preparation process is as follows:

[0049] (1) Weighing the polyurethane resin and the dibasic acid ester according to the above mass, stirring in a dissolving kettle until transparent, and filtering through a 250-300 mesh sieve to remove impurities to obtain a carrier;

[0050] (2) weighing the metallic silver powder, the carrier obtained in step (1), organic bentonite, polyurea, polyethylene wax and polyethylene glycol according to the above mass and placing them in a high-speed disperser for high-speed dispersion to obtain a uniform slurry;

[0051] (3) The slurry obtained in step (2) is ground and dispersed in a three-roll mill. The mill speed sequence is adjusted to make the dispersion more uniform. The spacing between the rollers is adjusted to make the fineness of the silver paste reach 10 μm. The viscosity is adjusted to 10 Pa·s by fine-tuning the solvent to prepare a light-colored, UV-resistant, low-temperature, high-temperature, and high-humidity-resistant titanium-containing conductive paste.

[0052] Example 4

[0053] This embodiment provides a low-temperature, high-humidity resistant, low-temperature, halogen-free conductive silver paste and a preparation method thereof:

[0054] The following components and qualities were used:

[0055] 20kg of flaky silver powder a, 20kg of flaky silver powder b, 10kg of flaky silver powder c, 9.5kg of polyurethane resin, 35.5kg of solvent, 3kg of thixotropic agent, 0.5kg of adhesion promoter, 0.5kg of hardener, and 1kg of dispersant. The silver powder used is flaky silver powder, with a particle size of 5.5μm and a tap density of 2.8g / mL for flaky silver powder a; a particle size of 3.5μm and a tap density of 2.3g / mL for flaky silver powder b; and a particle size of 1.0μm and a tap density of 0.8g / mL for flaky silver powder c. The polymer resin used is acrylic polyurethane resin, the organic solvent used is a divalent acid ester, the thixotropic agent used is organic bentonite, the adhesion promoter is polyurea, the hardener is polyethylene wax, and the dispersant is polyethylene glycol. The preparation process is as follows:

[0056] (1) Weighing the polyurethane resin and the dibasic acid ester according to the above mass, stirring in a dissolving kettle until transparent, and filtering through a 250-300 mesh sieve to remove impurities to obtain a carrier;

[0057] (2) weighing the metallic silver powder, the carrier obtained in step (1), organic bentonite, polyurea, polyethylene wax and polyethylene glycol according to the above mass and placing them in a high-speed disperser for high-speed dispersion to obtain a uniform slurry;

[0058] (3) The slurry obtained in step (2) is ground and dispersed in a three-roll mill. The mill speed sequence is adjusted to make the dispersion more uniform. The spacing between the rollers is adjusted to make the fineness of the silver paste reach 11 μm. The viscosity is adjusted to 14 Pa·s by fine-tuning the solvent to prepare a light-colored, UV-resistant, low-temperature, high-temperature, and high-humidity-resistant titanium-containing conductive paste.

[0059] Comparative Example 1

[0060] This comparative example provides a low-temperature, high-humidity resistant, low-temperature, halogen-free conductive silver paste and a preparation method thereof (without adding a thixotropic agent):

[0061] The following components and qualities were used:

[0062] 20kg of flaky metal silver powder a, 8kg of flaky metal silver powder b, 20kg of flaky metal silver powder c, 9.5kg of polyurethane resin, 38.5kg of solvent, 0.5kg of adhesion promoter, 0.5kg of hardener, and 1kg of dispersant. Among them, the metal silver powder used is flaky silver powder (all purchased from Zhejiang Changfeng Precious Metal Powder Co., Ltd.), the particle size of flaky silver powder a is 5.5μm, and the tap density is 2.8g / mL; the particle size of flaky silver powder b is 3.5μm, and the tap density is 2.3g / mL; the particle size of flaky silver powder c is 1.3μm, and the tap density is 1.0g / mL, the polymer resin used is acrylic polyurethane resin, the organic solvent used is divalent acid ester, the adhesion promoter used is polyurea, the hardener used is polyethylene wax, and the dispersant used is polyethylene glycol.

[0063] The preparation process is as follows:

[0064] (1) Weighing the polyurethane resin and the dibasic acid ester according to the above mass, stirring in a dissolving kettle until transparent, and filtering through a 250-300 mesh sieve to remove impurities to obtain a carrier;

[0065] (2) weighing the metallic silver powder, the carrier obtained in step (1), organic bentonite, polyurea, polyethylene wax and polyethylene glycol according to the above mass and placing them in a high-speed disperser for high-speed dispersion to obtain a uniform slurry;

[0066] (3) The slurry obtained in step (2) is ground and dispersed in a three-roll mill. The mill speed sequence is adjusted to make the dispersion more uniform. The spacing between the rollers is adjusted to make the fineness of the silver paste reach 11 μm. The viscosity is adjusted to 10 Pa·s by fine-tuning the solvent to prepare a light-colored, UV-resistant, low-temperature, high-temperature, and high-humidity-resistant titanium-containing conductive paste.

[0067] The performance tests were performed on the slurries prepared in Examples 1-4 and Comparative Example 1:

[0068] 1. Fineness

[0069] Test method:

[0070] a. First, select a scraper fineness meter with different ranges based on the type of coating. When the fineness is 15μm or less, a scraper fineness meter with a range of 0-25μm should be used (Examples 1-3 and Comparative Examples 1-2); when the fineness is 15μm-30μm, a scraper fineness meter with a range of 0-50μm should be used; when the fineness is above 30μm, a scraper fineness meter with a range of 0-100μm should be selected.

[0071] b. Before using, clean and dry the scraper fineness gauge with alcohol and use a soft cloth to clean it;

[0072] c. Use a small paint knife to fully stir the sample, and then drip 2-3 drops of the sample prepared in Examples 1-3 and Comparative Examples 1-2 into the deepest part of the groove of the scraper fineness meter, so that the groove can be filled with a little excess.

[0073] d. Hold the scraper with both hands and place it horizontally on the upper end of the polished plate (at the edge of the sample), making the scraper contact the surface of the polished plate vertically. Scrape from top to bottom at a constant speed within 3 seconds, so that the sample fills the grooves and no excess paint is left on the plate.

[0074] e. After the scraper is pulled, immediately (make the viewing angle 20° to 30° with the groove plane) observe the evenly exposed particles in the groove and record the readings (accurate to the minimum scale value). If individual particles are exposed on other scale lines, the readings shall not exceed three particles within the range of the adjacent scale lines.

[0075] 2. Viscosity

[0076] Test method:

[0077] a. Take 20g of the sample prepared in Example 1-3 and Comparative Example 1-2 and place it in a ground-mouth sample bottle;

[0078] b. Open the constant temperature circulating water tank to circulate the water in the tank, and use a thermometer to test to confirm that the water temperature reaches 25+1℃;

[0079] c. Place the sample bottle in a constant temperature water bath and let it stand for 48 hours;

[0080] d. Open the valve between the water tank and the viscometer test room water tank to circulate the water;

[0081] e. Use alcohol cotton to clean the viscometer test tank and rotor respectively and air dry;

[0082] f. Take the sample bottle out of the constant temperature water tank, adjust the viscometer level, put the sample into the test tank, fix the rotor, and rotate at 10r / min;

[0083] g. Turn on the viscometer power, wait for the digital display to stabilize, reset it, and set the parameters;

[0084] h. Start the rotor motor, and after 60 seconds, press the stop button, read the data, and make a record;

[0085] i. Turn off the power of the viscometer and close the circulating water.

[0086] 3. Resistors

[0087] Test method:

[0088] Set the multimeter to the ohm range, then touch the two probes to the two ends of the silver paste circuit and record the resistance value.

[0089] 4. Hardness

[0090] Test method:

[0091] Fix the silver paste screen-printed on PET on a horizontal surface. Hold a sharpened Zhonghua brand high-grade drawing pencil lead at a 45° angle to the paint film surface and push it forward approximately 1 cm at a speed of 1 cm / s (without breaking the pencil). Make five scratches with each pencil of each hardness level. If two or more scratches damage the paint film, switch to a harder pencil and continue scratching until you find a pencil that does not scratch the paint film. The hardness of this pencil represents the pencil hardness of the measured paint film.

[0092] Among them, the hardness grades of Zhonghua brand high-grade drawing pencils are 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, and H, among which 9H is the hardest and H is the softest.

[0093] 5. Anti-bending

[0094] Test method:

[0095] a. After 2g~3g of the slurry prepared in Examples and Comparative Examples were applied to the PET material, the slurry was laid flat, bent 180° on the front, and a 1kg weight was pressed on the bend for 60s;

[0096] b. Bend the fold 180° in the opposite direction and press a 1kg weight on the bend for 60s.

[0097] c. Lay flat and press a 1kg weight against the bend for 30 seconds.

[0098] d. After bending continuously 5 times, measure the resistance and calculate the resistance change rate.

[0099] 6. Resistant to high temperature and humidity

[0100] Test method:

[0101] A PET film (25 cm x 15 cm) coated with 2 g to 3 g of the slurry was placed in a constant temperature and humidity tester at 85°C and 85% RH. After 15 hours, it was cooled to room temperature and taken out to observe whether there was watermark on the surface of the film.

[0102] 7. Adhesion

[0103] Test method:

[0104] a. Score a grid (7cm×7cm) on a PET film (25cm×15cm) coated with 2g~3g of slurry. The grid knife must penetrate the paint film to the substrate.

[0105] b. Clean the sample surface to ensure the cleanliness of the test environment;

[0106] c. Apply the tape to the center of the coating sample, ensuring full contact with the coating, and then pull it off quickly and continuously;

[0107] d. Evaluate adhesion based on the degree of paint film shedding. (As the degree of paint film shedding increases, the order is 5B, 4B, 3B, 2B, 1B, 0B)

[0108] Among them, when the grid knife is cut, the cut should be made until the base material is seen, and it should not be cut only on the paint. After the grid knife is finished cutting, it is necessary to use tape to test whether it will fall off. The tape is attached to the grid position, and pressed down with your fingers to stick the tape tightly, and then the tape is torn off with an instantaneous force.

[0109] The experimental data and results are shown in Table 1

[0110] Table 1 Performance test results of conductive silver paste produced in Examples 1-3 and Comparative Examples 1-2

[0111] In summary: the high temperature and high humidity performance of the conductive silver paste of the present invention shows a downward trend as the thixotropic agent continues to decrease. Compared with the comparative example, when the high temperature and high humidity agent is 0.8-2%, the high temperature and high humidity performance is the best, but as the thixotropic agent decreases to 0% (Comparative Example 1), its high temperature and high humidity performance is extremely poor, and the rate of change after bending 10 times increases. When the amount of thixotropic agent is increased to 3%, its high temperature and high humidity performance remains basically unchanged, but it will cause a certain amount of increase in resistance, increase viscosity, and increase the change in resistance after bending 10 times. Therefore, when the thixotropic agent is within the content of 0.8% to 2%, the resistance and other properties are optimal.

[0112] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A low-temperature, high-humidity resistant, halogen-free conductive silver paste, characterized in that: The conductive paste comprises the following components in parts by weight:

2. The high temperature and high humidity resistant low temperature halogen-free conductive silver paste according to claim 1, characterized in that: The metallic silver powder is selected from flaky silver powders with different particle sizes, wherein the particle sizes of the flaky silver powders with different particle sizes are respectively: 5.0-8.0 μm, 3.0-4.0 μm, and 1.0-2.0 μm.

3. The high temperature and high humidity resistant low temperature halogen-free conductive silver paste according to claim 1, characterized in that: The polymer resin is polyurethane resin.

4. The high temperature and high humidity resistant low temperature halogen-free conductive silver paste according to claim 1, characterized in that: The solvent includes at least one of terpineol, dibasic acid ester, isophorone or propylene glycol methyl ether acetate.

5. The high temperature and high humidity resistant low temperature halogen-free conductive silver paste according to claim 1, characterized in that: The thixotropic agent includes at least one of organic bentonite, polyurea, fumed silica and hydrogenated castor oil.

6. The high temperature and high humidity resistant low temperature halogen-free conductive silver paste according to claim 1, characterized in that: The dispersant includes at least one of polyethylene glycol, oleyl amino oleate, and polyethylene wax.

7. The high temperature and high humidity resistant low temperature halogen-free conductive silver paste according to claim 1, characterized in that: The adhesion promoter is polyurea, and the hardener is polyethylene wax.

8. A method for preparing a high temperature and high humidity resistant low temperature halogen-free conductive silver paste as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Take a polymer resin and a solvent in a dissolving kettle, stir until transparent, and filter with a sieve to remove impurities to obtain a carrier; S2: Take the metallic silver powder, the carrier prepared in step S1, the thixotropic agent, the adhesion promoter, the hardener and the The powder is placed in a high-speed disperser for high-speed dispersion to obtain a uniform slurry; S3: Grind and disperse the slurry obtained in step S2 in a three-roll mill, adjust the distance between the rollers, adjust the fineness and viscosity of the silver paste, and prepare a low-temperature halogen-free conductive silver paste that is resistant to high temperature and high humidity.

9. The method for preparing the high temperature and high humidity resistant low temperature halogen-free conductive silver paste according to claim 8, characterized in that: In step S1, the mesh size of the sieve is 250-300 meshes.

10. The method for preparing the high temperature and high humidity resistant low temperature halogen-free conductive silver paste according to claim 8, characterized in that: In step S3, the fineness of the silver paste is controlled to be 0-15 μm, and the viscosity is 9-31 Pa·S.

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