Modified conductive silver paste and preparation method thereof

Abstract

The invention provides modified conductive silver paste and a preparation method thereof. The preparation method of the modified conductive silver paste comprises the following steps: S1, uniformly mixing silver powder, resin, a solvent and a curing agent to obtain primary paste; and S2, a rheological additive and a coalescing agent are added into the primary paste and evenly mixed, the modified conductive silver paste is obtained, the mass of the rheological additive accounts for 1%-7% of the mass of the modified conductive silver paste, and the mass of the coalescing agent accounts for 0.05%-5% of the mass of the modified conductive silver paste. According to the preparation method of the modified conductive silver paste provided by the embodiment of the invention, the rheological property of the paste is greatly improved by adding a proper amount of the rheological additive and the coalescing agent, and the paste is easier to level especially in a wet film state.

Description

Technical Field

[0001] The invention relates to the technical field of conductive paste, and in particular to a modified conductive silver paste and a preparation method thereof. Background Art

[0002] With the development of microelectronics technology, the requirements for electronic components are getting higher and higher. The surface flatness of the graphics produced by traditional silver paste through screen printing is poor and the undulations are obvious. It cannot be used in application scenarios with high conductivity and good fluidity, such as 5G mobile phone terminal antennas. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a modified conductive silver paste and a preparation method thereof, which can improve the leveling property of the silver paste.

[0004] The method for preparing the modified conductive silver paste according to the first embodiment of the present invention comprises the following steps:

[0005] S1. Evenly mix the silver powder, resin, solvent and curing agent to obtain a preliminary slurry;

[0006] S2, adding a rheological additive and a film-forming additive to the preliminary slurry, and uniformly mixing to obtain the modified conductive silver paste,

[0007] The mass of the rheological additive accounts for 1% to 7% of the mass of the modified conductive silver paste, and the mass of the film-forming additive accounts for 0.05% to 5% of the mass of the modified conductive silver paste.

[0008] In some embodiments, in step S1,

[0009] The silver powder includes a particle size of D 50 Silver powder with a particle size of 200 nm and a particle size of D 50 The silver powder is 300nm and the particle size is D 50 It is 500nm silver powder.

[0010] In some embodiments, the step S1 further includes adding a dispersant.

[0011] Wherein, the particle size is D 50 The silver powder is 200 nm, the particle size is D 50 The silver powder is 300nm, the particle size is D 50 The mass ratio of 500nm silver powder, resin, solvent, curing agent and dispersant is (5-35): (10-40): (30-70): (0.1-3): (5-15): (0.1-2): (0.1-0.5).

[0012] Preferably, in step S1,

[0013] The resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, alicyclic epoxy resin or resorcinol epoxy resin;

[0014] The solvent includes one or more of dipropylene glycol dimethyl ether, propylene glycol diacetate, propylene glycol butyl ether, ethylene glycol butyl ether, propylene glycol propyl ether, ethylene glycol tert-butyl ether, isophorone, ethylene glycol, propylene glycol, propylene glycol methyl ether, ethyl acetate, butyl acetate, xylene, terpineol, ethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl ether acetate, dodecanol ester, dibutyl phthalate, triacetin, dioctyl phthalate, dioctyl adipate, isopropyl alcohol, n-butanol or cyclopentanone;

[0015] The curing agent includes one or more of boron trifluoride ethylamine complex, diphenyl dimethyl sulfone, diaminophenyl sulfone, 4,4-diaminodiphenyl sulfone, heptadecyl imidazole, dicyandiamide, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, adipic acid dihydrazide, methyl isobutyl ketimine, polyetheramine D-230, polyamide 650 or bisphenol A cyanate;

[0016] The dispersant includes one or more of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, hexadecyltrimethylammonium chloride, octadecylamine acetate, oleic acid, stearic acid or palmitic acid.

[0017] In some implementation modes, step S2 specifically includes:

[0018] Adding a rheological additive and a film-forming additive to the preliminary slurry, uniformly mixing to obtain a first mixed slurry, grinding the first mixed slurry to obtain a second mixed slurry, sieving the second mixed slurry to obtain the modified conductive silver paste,

[0019] The mass of the rheological additive accounts for 1% to 7% of the mass of the modified conductive silver paste, and the mass of the film-forming additive accounts for 0.05% to 5% of the mass of the modified conductive silver paste.

[0020] Preferably, in step S2,

[0021] The rheological additive includes one or more of ethyl cellulose, hydroxyethyl cellulose, hydroxypropylene cellulose, polyamide wax, silicone-modified polyurethane acrylate, silicone-modified bentonite, castor oil derivatives, silicone polyether copolymers, silicone wax rheological additives, acrylic acid alkali swelling thickeners, acrylate copolymers or carbomer.

[0022] Preferably, in step S2,

[0023] The film-forming aid includes one or more of alcohol ester, polyethylene glycol, acrylate, polyurethane, polyvinyl alcohol and polyvinyl pyrrolidone.

[0024] In some embodiments, in step S2, grinding the first mixed slurry to obtain the second mixed slurry specifically includes:

[0025] The first mixed slurry is ground until the fineness is 0-2.5 μm to obtain a second mixed slurry.

[0026] In some embodiments, in step S2, screening the second mixed slurry specifically includes:

[0027] The second mixed slurry is sieved through a 400-500 mesh screen.

[0028] The modified conductive silver paste according to the second embodiment of the present invention is prepared by the preparation method of the modified conductive silver paste of any embodiment of the first embodiment.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] The preparation method of the modified conductive silver paste of the embodiment of the present invention greatly improves the rheological properties of the paste by adding appropriate amounts of rheological additives and film-forming additives, especially making it easier to level in a wet film state.

[0031] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0033] Figure 1 is a flow chart of a method for preparing a modified conductive silver paste according to an embodiment of the present invention;

[0034] Figure 2 This is a 50 μm-scale SEM cross-sectional image of the modified conductive silver paste of an embodiment of the present invention after curing;

[0035] Figure 3 This is a 100 μm-scale SEM cross-sectional image of the modified conductive silver paste of an embodiment of the present invention after curing. DETAILED DESCRIPTION

[0036] In the description of this embodiment, it should be understood that the terms "length", "width", "height", "up", "down", "left", "right", "vertical", "horizontal", "bottom", "inside" and "outside" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0037] As a specific embodiment of the present invention, refer to Figure 1 As shown, the method for preparing the modified conductive silver paste according to the first aspect of the present invention may include the following steps:

[0038] S1. Evenly mix the silver powder, resin, solvent and curing agent to obtain a preliminary slurry;

[0039] S2, add rheological additive and film-forming additive to the preliminary slurry, mix evenly, and obtain modified conductive silver paste.

[0040] The mass of the rheological additive accounts for 1% to 7% of the mass of the modified conductive silver paste, and the mass of the film-forming additive accounts for 0.05% to 5% of the mass of the modified conductive silver paste.

[0041] Specifically, the preparation method of the modified conductive silver paste of the embodiment of the present invention is to first uniformly mix silver powder, resin, solvent and curing agent to obtain a preliminary slurry, and then add a rheological additive and a film-forming additive to the slurry. The surface of the modified conductive silver paste finally obtained can achieve high leveling properties.

[0042] Preferably, the mass of the rheological additive accounts for 1% to 7% of the mass of the modified conductive silver paste, which can be determined depending on the performance of the paste itself. Too little addition will affect the leveling of the paste, and too much addition will affect the resistivity of the entire silver paste. For example, if the original resistivity is large, excessive addition will make the overall resistivity of the silver paste too large. Even if the leveling improves, excessive resistivity will affect the signal transmission effect.

[0043] Preferably, the mass of the film-forming aid accounts for 0.05% to 5% of the mass of the modified conductive silver paste, which can be determined depending on the performance of the paste itself. Adding too little will not achieve the leveling effect during the curing process, and adding too much will affect the overall electrical properties of the paste, thereby affecting the final signal transmission effect.

[0044] That is to say, the preparation method of the modified conductive silver paste of the embodiment of the present invention greatly improves the rheological properties of the paste by adding an appropriate amount of rheological additives and film-forming additives, especially making it easier to level in the wet film state. As an example, when printing a large-area graphic, the paste is printed onto the substrate through the screen. During the lifting process of the screen, the paste will be lifted up and then disconnected, making the surface flatness of the entire graphic poor. The modified conductive silver paste obtained by the preparation method of the present invention will make the entire printed pattern surface itself smoother after the subsequent self-leveling and curing process, which effectively ensures that the printed pattern will eventually present a good effect.

[0045] In some embodiments, in step S1,

[0046] The silver powder includes particles with a diameter of D 50 Silver powder with a particle size of 200 nm and a particle size of D 50 The silver powder is 300nm and the particle size is D 50 It is 500nm silver powder.

[0047] Specifically, the three types of silver powders are selected and combined in a spherical shape, and the stacking density is high after printing. During the film forming process, the silver powders of different particle sizes cooperate with each other to better fill the gaps in the film layer and reduce the porosity. The silver powders with smaller particle sizes can fill the tiny depressions between the silver powders with larger particle sizes, making the surface of the film layer smoother and flatter.

[0048] In some embodiments, step S1 further includes adding a dispersant.

[0049] The particle size is D 50 Silver powder with a particle size of 200 nm and a particle size of D 50 The silver powder is 300nm, the particle size is D 50 The mass ratio of 500nm silver powder, resin, curing agent, solvent and dispersant is (5-35): (10-40): (30-70): (0.1-3): (0.1-2): (5-15): (0.1-0.5).

[0050] Specifically, when the mass fraction of silver powder with D50 of 200nm is 5-35 parts, the small-particle silver powder of 200nm plays a key filling role in the silver paste system. It can be filled into the gaps formed by 300nm and 500nm silver powders to increase the packing density of the silver powder. 10-40 parts by mass of 300nm silver powder is an important component for building a conductive network. Its particle size is moderate, which can not only form a larger conductive skeleton with 500nm silver powder, but also provide a basis for attachment and connection of 200nm silver powder. 30-70 parts by mass of 500nm silver powder is the main builder of the conductive network of silver paste. Due to its larger particle size, the transmission distance of electrons between 500nm silver powder particles is relatively short, which can provide higher conductivity.

[0051] The main function of the resin in the silver paste is to bond the silver powder particles and form a continuous film layer. In the range of 0.1-3 parts by mass, the resin can firmly bond the silver powder together, so that the silver paste forms a stable conductive film on the substrate.

[0052] The main function of the solvent is to evenly disperse the silver powder, resin, curing agent and dispersant in the silver paste system. In the range of 5-15 parts by mass, the solvent can provide sufficient fluidity to make the silver paste have a suitable viscosity and facilitate construction operations.

[0053] The role of the curing agent in the silver paste is to chemically react with the resin and other components to transform the silver paste from liquid to solid and form a stable conductive film layer. In the range of 0.1-2 parts by mass, the curing agent can provide sufficient active groups to react with the functional groups in the resin and promote the curing process.

[0054] The main function of the dispersant is to prevent the silver powder from agglomerating in the silver paste system and ensure that the silver powder is evenly dispersed. In the range of 0.1-0.5 parts by mass, the dispersant can be adsorbed on the surface of the silver powder particles to form a protective film, reducing the surface attraction between the silver powder particles.

[0055] Preferably, in step S1,

[0056] The resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, alicyclic epoxy resin or resorcinol epoxy resin;

[0057] The solvent includes one or more of dipropylene glycol dimethyl ether, propylene glycol diacetate, propylene glycol butyl ether, ethylene glycol butyl ether, propylene glycol propyl ether, ethylene glycol tert-butyl ether, isophorone, ethylene glycol, propylene glycol, propylene glycol methyl ether, ethyl acetate, butyl acetate, xylene, terpineol, ethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl ether acetate, dodecanol ester, dibutyl phthalate, triacetin, dioctyl phthalate, dioctyl adipate, isopropyl alcohol, n-butanol or cyclopentanone;

[0058] The curing agent includes one or more of boron trifluoride ethylamine complex, diphenyl dimethyl sulfone, diaminophenyl sulfone, 4,4-diaminodiphenyl sulfone, heptadecyl imidazole, dicyandiamide, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, adipic acid dihydrazide, methyl isobutyl ketimine, polyetheramine D-230, polyamide 650 or bisphenol A cyanate;

[0059] The dispersant includes one or more of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, hexadecyl trimethyl ammonium chloride, octadecylamine acetate, oleic acid, stearic acid or palmitic acid. Specifically, BYK111, BYK2009, BYK-220SN or BYK-1162 can be used as the wetting dispersant.

[0060] In some implementations, step S2 specifically includes:

[0061] Adding a rheological additive and a film-forming additive to the preliminary slurry, uniformly mixing to obtain a first mixed slurry, grinding the first mixed slurry to obtain a second mixed slurry, sieving the second mixed slurry to obtain the modified conductive silver paste,

[0062] The mass of the rheological additive accounts for 1% to 7% of the mass of the modified conductive silver paste, and the mass of the film-forming additive accounts for 0.05% to 5% of the mass of the modified conductive silver paste.

[0063] That is to say, after adding the rheological additive and the film-forming additive to the preliminary slurry and mixing them evenly, the slurry needs to be ground and sieved so that the quality of the obtained modified conductive silver paste is better, that is, the rheological properties are better.

[0064] Preferably, in step S2,

[0065] The rheological additive may include one or more of ethyl cellulose, hydroxyethyl cellulose, hydroxypropylene cellulose, polyamide wax, silicone-modified polyurethane acrylate, silicone-modified bentonite, castor oil derivatives, silicone polyether copolymers, silicone wax rheological additives, acrylic acid alkali swellable thickeners, acrylate copolymers or carbomer.

[0066] Specifically, the use of the above substances as rheological additives can effectively improve the leveling performance and wire drawing performance of the silver paste itself.

[0067] Preferably, in step S2,

[0068] The film-forming aid may include one or more of alcohol ester, polyethylene glycol, acrylate, polyurethane, polyvinyl alcohol and polyvinyl pyrrolidone.

[0069] Specifically, the above substances are selected as film-forming aids. On the one hand, the film-forming properties of the silver paste can be improved, so that the paste forms a uniform, continuous, and defect-free conductive film; on the other hand, the surface tension between the silver powder particles can be reduced, so that the silver powder can be spread better, thereby helping to form a smooth film. In other words, the film-forming aids of the above substances can adjust the surface tension, prevent shrinkage and orange peel, and improve electrical properties.

[0070] In some embodiments, in step S2, grinding the first mixed slurry to obtain the second mixed slurry specifically includes:

[0071] The first mixed slurry is ground until the fineness is 0-2.5 μm to obtain a second mixed slurry.

[0072] Thus, the second mixed slurry obtained after grinding to a predetermined fineness range of 0 to 2.5 μm reduces the size of its material particles, so that the leveling property of the slurry is further improved.

[0073] In some embodiments, in step S2, screening the second mixed slurry specifically includes:

[0074] The second mixed slurry is sieved through a 400-500 mesh screen.

[0075] That is to say, by screening the ground second mixed slurry through a 400-500 mesh screen, impurities with larger particle sizes or particles with substandard fineness in the slurry can be screened out, thereby maximizing the leveling properties of the slurry.

[0076] As an example, the internal structure of the conductive silver paste prepared by the preparation method of the modified conductive silver paste of the embodiment of the present invention is as follows: Figure 2 and Figure 3 As shown, from the SEM cross-section test picture of the cured conductive silver paste, it can be seen that the silver particles are evenly distributed after curing to form a continuous and dense conductive network; the paste has no tiny pores and no air bubbles larger than 1 micron; the surface of the conductive silver paste is smooth and continuous, without obvious ups and downs or depressions.

[0077] The modified conductive silver paste according to the second embodiment of the present invention is prepared by the preparation method of the modified conductive silver paste of any embodiment of the first embodiment.

[0078] The modified conductive silver paste and the preparation method thereof of the present application are further described below with specific examples.

[0079] Example 1

[0080] Preparation of preliminary slurry: Select 9 parts by mass of silver powder with a D50 of 200 nm, 15 parts by mass of silver powder with a D50 of 300 nm, 60 parts by mass of silver powder with a D50 of 500 nm, 2 parts by mass of epoxy resin, 1.5 parts by mass of boron trifluoride ethylamine complex, 12.2 parts by mass of dipropylene glycol dimethyl ether and 0.3 parts by mass of polyvinyl alcohol, and mix them evenly to obtain a preliminary slurry.

[0081] Preparation of modified conductive silver paste: Add ethyl cellulose and alcohol ester twelve to the preliminary slurry, mix evenly, grind to a fineness of 1 μm, and pass through a 400-mesh sieve to obtain a modified conductive silver paste, wherein ethyl cellulose accounts for 4% of the mass of the modified conductive silver paste, and alcohol ester twelve accounts for 0.3% of the mass of the modified conductive silver paste.

[0082] Example 2

[0083] Preparation of preliminary slurry: Select 9 parts by mass of silver powder with a D50 of 200 nm, 15 parts by mass of silver powder with a D50 of 300 nm, 60 parts by mass of silver powder with a D50 of 500 nm, 2 parts by mass of epoxy resin, 1.5 parts by mass of boron trifluoride ethylamine complex, 12.2 parts by mass of dipropylene glycol dimethyl ether and 0.3 parts by mass of polyvinyl alcohol, and mix them evenly to obtain a preliminary slurry.

[0084] Preparation of modified conductive silver paste: Add hydroxyethyl cellulose and polyethylene glycol to the preliminary slurry, mix evenly, grind to a fineness of 1 μm, and pass through a 400-mesh screen to obtain a modified conductive silver paste, wherein hydroxyethyl cellulose accounts for 3% of the mass of the modified conductive silver paste, and polyethylene glycol accounts for 0.5% of the mass of the modified conductive silver paste.

[0085] Example 3

[0086] Preparation of preliminary slurry: Select 9 parts by mass of silver powder with a D50 of 200 nm, 15 parts by mass of silver powder with a D50 of 300 nm, 60 parts by mass of silver powder with a D50 of 500 nm, 2 parts by mass of epoxy resin, 1.5 parts by mass of boron trifluoride ethylamine complex, 12.2 parts by mass of dipropylene glycol dimethyl ether and 0.3 parts by mass of polyvinyl alcohol, and mix them evenly to obtain a preliminary slurry.

[0087] Preparation of modified conductive silver paste: Add hydroxypropylene cellulose and polyvinyl pyrrolidone to the preliminary slurry, mix evenly, grind to a fineness of 1 μm, and pass through a 400-mesh screen to obtain a modified conductive silver paste, wherein hydroxypropylene cellulose accounts for 4% of the mass of the modified conductive silver paste, and polyvinyl pyrrolidone accounts for 0.5% of the mass of the modified conductive silver paste.

[0088] Comparative Example 1

[0089] Preparation of conductive silver paste: Select 9 parts by mass of silver powder with a D50 of 200 nm, 15 parts by mass of silver powder with a D50 of 300 nm, 60 parts by mass of silver powder with a D50 of 500 nm, 2 parts by mass of epoxy resin, 1.5 parts by mass of boron trifluoride ethylamine complex, 12.2 parts by mass of dipropylene glycol dimethyl ether and 0.3 parts by mass of polyvinyl alcohol, and mix them evenly to obtain a conductive silver paste.

[0090] Comparative Example 2

[0091] Preparation of preliminary slurry: Select 9 parts by mass of silver powder with a D50 of 200 nm, 15 parts by mass of silver powder with a D50 of 300 nm, 60 parts by mass of silver powder with a D50 of 500 nm, 2 parts by mass of epoxy resin, 1.5 parts by mass of boron trifluoride ethylamine complex, 12.2 parts by mass of dipropylene glycol dimethyl ether and 0.3 parts by mass of polyvinyl alcohol, and mix them evenly to obtain a preliminary slurry.

[0092] Preparation of conductive silver paste: Ethyl cellulose is added to the preliminary slurry, mixed evenly, ground to a fineness of 1 μm, and passed through a 400-mesh screen to obtain a conductive silver paste, wherein the ethyl cellulose accounts for 4% of the mass of the conductive silver paste.

[0093] Comparative Example 3

[0094] Preparation of preliminary slurry: Select 9 parts by mass of silver powder with a D50 of 200 nm, 15 parts by mass of silver powder with a D50 of 300 nm, 60 parts by mass of silver powder with a D50 of 500 nm, 2 parts by mass of epoxy resin, 1.5 parts by mass of boron trifluoride ethylamine complex, 12.2 parts by mass of dipropylene glycol dimethyl ether and 0.3 parts by mass of polyvinyl alcohol, and mix them evenly to obtain a preliminary slurry.

[0095] Preparation of conductive silver paste: Add alcohol ester 12 to the preliminary paste, mix evenly, grind to a fineness of 1 μm, and pass through a 400-mesh screen to obtain a conductive silver paste, wherein the alcohol ester 12 accounts for 0.3% of the mass of the conductive silver paste.

[0096] Table 1 is a performance test evaluation table of the modified conductive silver paste of each embodiment and the conductive silver paste of each comparative example

[0097]

[0098] The conductive silver paste prepared in each embodiment and comparative example was screen printed and dried and cured at 90 degrees Celsius to obtain the resistivity and flatness test data shown in Table 1.

[0099] Referring to Table 1, by comparing Example 1 and Comparative Example 1, it can be seen that by adding ethyl cellulose rheological additive and alcohol ester twelve film-forming additive, the self-leveling performance of the slurry is greatly increased without affecting the electrical properties of the silver paste, the flatness of the material is improved, and the volume resistivity of the material is almost unaffected.

[0100] From the comparison between Example 2 and Comparative Example 1, it can be seen that the addition of hydroxyethyl cellulose rheological additive and polyethylene glycol film-forming additive can improve the flatness to a certain extent, but the conductivity of the silicone leveling additive is poor, which will affect the volume resistivity.

[0101] It can be seen from the comparison between Example 3 and Comparative Example 1 that the addition of hydroxypropylene cellulose rheological additive and PVP film-forming additive can improve the flatness to a certain extent, but will lead to a significant increase in the volume resistivity.

[0102] In Comparative Example 2, only the rheological additive was added without the participation of the film-forming additive, and the flatness was significantly improved.

[0103] In Comparative Example 3, only the film-forming aid was added, and the line width widened after the slurry was printed, and the flatness was not significantly improved.

[0104] In summary, the modified conductive silver paste prepared by the preparation method of the present invention can achieve high leveling on the surface of the silver paste in a wet film state after printing by adding a rheological additive and a film-forming additive, and achieve submicron-level flatness after curing. In addition, the modified conductive silver paste of the present invention has high flatness and high density after curing, and can be cured at a low temperature of 90°C.

[0105] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A method for preparing a modified conductive silver paste, characterized in that: The steps include: S1. Evenly mix the silver powder, resin, solvent and curing agent to obtain a preliminary slurry; S2, adding a rheological additive and a film-forming additive to the preliminary slurry, and uniformly mixing to obtain the modified conductive silver paste, The mass of the rheological additive accounts for 1% to 7% of the mass of the modified conductive silver paste, and the mass of the film-forming additive accounts for 0.05% to 5% of the mass of the modified conductive silver paste.

2. The method for preparing the modified conductive silver paste according to claim 1, characterized in that: In the step S1, The silver powder includes a particle size of D 50 Silver powder with a particle size of 200 nm and a particle size of D 50 The silver powder is 300nm and the particle size is D 50 It is 500nm silver powder.

3. The method for preparing the modified conductive silver paste according to claim 2, characterized in that: The step S1 further includes adding a dispersant. Wherein, the particle size is D 50 The silver powder is 200 nm, the particle size is D 50 The silver powder is 300nm, the particle size is D 50 The mass ratio of 500nm silver powder, resin, solvent, curing agent and dispersant is (5-35): (10-40): (30-70): (0.1-3): (5-15): (0.1-2): (0.1-0.5).

4. The method for preparing the modified conductive silver paste according to claim 3, characterized in that: In the step S1, The resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin, alicyclic epoxy resin or resorcinol epoxy resin; The solvent includes one or more of dipropylene glycol dimethyl ether, propylene glycol diacetate, propylene glycol butyl ether, ethylene glycol butyl ether, propylene glycol propyl ether, ethylene glycol tert-butyl ether, isophorone, ethylene glycol, propylene glycol, propylene glycol methyl ether, ethyl acetate, butyl acetate, xylene, terpineol, ethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl ether acetate, dodecanol ester, dibutyl phthalate, triacetin, dioctyl phthalate, dioctyl adipate, isopropyl alcohol, n-butanol or cyclopentanone; The curing agent includes one or more of boron trifluoride ethylamine complex, diphenyl dimethyl sulfone, diaminophenyl sulfone, 4,4-diaminodiphenyl sulfone, heptadecyl imidazole, dicyandiamide, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, adipic acid dihydrazide, methyl isobutyl ketimine, polyetheramine D-230, polyamide 650 or bisphenol A cyanate; The dispersant includes one or more of polyvinyl pyrrolidone, polyvinyl alcohol, polyethylene glycol, hexadecyltrimethylammonium chloride, octadecylamine acetate, oleic acid, stearic acid or palmitic acid.

5. The method for preparing the modified conductive silver paste according to claim 1, characterized in that: The step S2 specifically includes: Adding a rheological additive and a film-forming additive to the preliminary slurry, uniformly mixing to obtain a first mixed slurry, grinding the first mixed slurry to obtain a second mixed slurry, sieving the second mixed slurry to obtain the modified conductive silver paste, The mass of the rheological additive accounts for 1% to 7% of the mass of the modified conductive silver paste, and the mass of the film-forming additive accounts for 0.05% to 5% of the mass of the modified conductive silver paste.

6. The method for preparing the modified conductive silver paste according to claim 1, characterized in that: In the step S2, The rheological additive includes one or more of ethyl cellulose, hydroxyethyl cellulose, hydroxypropylene cellulose, polyamide wax, silicone-modified polyurethane acrylate, silicone-modified bentonite, castor oil derivatives, silicone polyether copolymers, silicone wax rheological additives, acrylic acid alkali swelling thickeners, acrylate copolymers or carbomer.

7. The method for preparing the modified conductive silver paste according to claim 1, characterized in that: In the step S2, The film-forming aid includes one or more of alcohol ester, polyethylene glycol, acrylate, polyurethane, polyvinyl alcohol and polyvinyl pyrrolidone.

8. The method for preparing the modified conductive silver paste according to claim 5, characterized in that: In the step S2, grinding the first mixed slurry to obtain the second mixed slurry specifically includes: The first mixed slurry is ground until the fineness is 0-2.5 μm to obtain a second mixed slurry.

9. The method for preparing the modified conductive silver paste according to claim 5, characterized in that: In the step S2, the screening of the second mixed slurry specifically includes: The second mixed slurry is sieved through a 400-500 mesh screen.

10. A modified conductive silver paste, characterized in that: The modified conductive silver paste is prepared by the preparation method of any one of claims 1 to 9.

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