CN111303808B

CN111303808B - Conductive adhesive with high dispersion stability and high conductivity and preparation method thereof

Info

Publication number: CN111303808B
Application number: CN202010138557.7A
Authority: CN
Inventors: 方斌; 吴丰富; 张震; 杨向民
Original assignee: Xiamen Yinfang New Material Technology Co ltd; East China University of Science and Technology
Current assignee: Xiamen Yinfang New Material Technology Co ltd; East China University of Science and Technology
Priority date: 2020-03-03
Filing date: 2020-03-03
Publication date: 2021-06-18
Anticipated expiration: 2040-03-03
Also published as: CN111303808A

Abstract

The invention discloses a conductive adhesive with high dispersion stability and high conductivity, which is prepared from a resin dispersion stabilizer 1, a resin dispersion stabilizer 2 and conductive metal powder, wherein the mass ratio of the resin dispersion stabilizer 1 to the resin dispersion stabilizer 2 is 1 (1-2), and the conductive metal powder accounts for 45-80% of the total mass of the resin dispersion stabilizer 1, the resin dispersion stabilizer 2 and the conductive metal powder. The preparation method is simple and efficient, has controllable conditions, and is easy to realize industrial production. The conductive adhesive with high dispersion stability and high conductivity is obtained by copolymerization and crosslinking by using metal powder stabilized by a resin dispersion stabilizer as a conductive material and the resin dispersion stabilizer as a dispersant and a resin material, and has a huge application prospect in the field of printed circuits.

Description

Conductive adhesive with high dispersion stability and high conductivity and preparation method thereof

Technical Field

The invention belongs to the technical field of conductive adhesive preparation, and particularly relates to a conductive adhesive with high dispersion stability and high conductivity and a preparation method thereof.

Background

A printed Circuit board (pcb) in an electronic device is manufactured through a series of complicated processing steps such as photolithography, development, etching, and the like, and the processing steps are complicated, high in energy consumption, and serious in pollutant discharge. Printed circuit technology is the additive manufacturing technology that utilizes printing technology to make electronic devices or circuits. Compared with the traditional integrated circuit processing method, the printed circuit technology can realize large-area and batch manufacturing, has low cost and environmental protection, and can meet special requirements of digitalization, individualization and the like, thereby meeting new booming development opportunities.

With the wide application of ink-jet printing, screen printing, dispensing and other printed circuit technologies in the preparation of circuits and electrodes, conductive adhesives become key materials for realizing efficient and low-cost preparation of optoelectronic devices. The conductive adhesive is generally prepared by mechanically blending conductive metal powder, high polymer resin and other additives. Wherein, a large amount of surface active agents such as gelatin powder, polyvinylpyrrolidone (PVP), sodium dodecyl sulfate and the like are required to be added when the conductive metal powder is prepared. The Journal of Alloys and Compounds in the netherlands (Journal of Alloys and Compounds, 494, page 84 of 2010) reports that silver powder is prepared by a chemical reduction method by using silver nitrate and lauric acid as a precursor and a surfactant respectively, wherein the dosage of the surfactant is about 20% of the silver nitrate, and the removal is difficult. If the removal is incomplete, the conductivity of the conductive adhesive is seriously affected. If the silver powder is completely removed, the silver powder is easy to settle and agglomerate in the conductive adhesive, so that the reliability of the printed circuit is greatly reduced, and the actual application requirements cannot be met. Therefore, developing a conductive adhesive with high dispersion stability and high conductivity is a hot research point in the scientific research and industrial fields.

Disclosure of Invention

The invention aims to provide a conductive adhesive with high dispersion stability and high conductivity, so as to overcome the defects of complicated preparation process, poor stability and low conductivity of the conventional conductive adhesive.

The second purpose of the invention is to provide a preparation method of the conductive adhesive with high dispersion stability and high conductivity.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

the invention provides a conductive adhesive with high dispersion stability and high conductivity, which is prepared from a resin dispersion stabilizer 1, a resin dispersion stabilizer 2 and conductive metal powder, wherein the mass ratio of the resin dispersion stabilizer 1 to the resin dispersion stabilizer 2 is 1 (1-2), and the conductive metal powder accounts for 45-80% of the total mass of the resin dispersion stabilizer 1, the resin dispersion stabilizer 2 and the conductive metal powder;

the preparation method of the resin dispersion stabilizer 1 includes the steps of: initiating copolymerization of a monomer A and a monomer B in a molar ratio of (1-16): 1 in a mixed solvent by an initiator to obtain the resin dispersion stabilizer 1; the monomer A is N-vinyl pyrrolidone, and the monomer B is acrylic acid; the mass of the initiator is 4.0-8.0% of the total mass of the monomer A and the monomer B; the initiator is azobisisobutyronitrile;

the preparation method of the resin dispersion stabilizer 2 includes the steps of: initiating copolymerization of a monomer A and a monomer B in a molar ratio of (1-16): 1 in a mixed solvent by an initiator to obtain the resin dispersion stabilizer 2; the monomer A is N-vinyl pyrrolidone, and the monomer B is glycidyl methacrylate; the mass of the initiator is 4.0-8.0% of the total mass of the monomer A and the monomer B; the initiator is azobisisobutyronitrile.

The preparation method of the conductive metal powder comprises the following steps:

step one, preparing a metal salt solution: adding metal salt into deionized water, wherein the molar concentration of the metal salt solution is 0.28-10 mol/L, and dropwise adding 25-28% concentrated ammonia water until a clear and transparent solution is obtained;

step two, preparation of a reducing agent solution: dissolving a resin dispersion stabilizer 1 or a resin dispersion stabilizer 2 and a reducing agent in deionized water, and uniformly mixing at the temperature of 5-25 ℃;

thirdly, mixing and reacting the metal salt solution and the reducing agent solution: slowly dripping the metal salt solution prepared in the first step into the reducing agent solution prepared in the second step, or slowly dripping the reducing agent solution prepared in the second step into the metal salt solution prepared in the first step, wherein the dripping speed is 0.02-1.5 mL/min; and after the dropwise addition is finished, continuously reacting for 10-60 min at the temperature of 5-40 ℃ to obtain the conductive metal powder.

The metal salt in the first step is selected from one of silver nitrate, silver carbonate, silver sulfate, silver oxalate, copper nitrate and copper chloride.

The preferred molar concentration of the metal salt solution in the first step is 1.67 mol/L.

The reducing agent in the second step is selected from one of 1, 4-dihydrophthalazine-5-alcohol, ascorbic acid, hydrazine hydrate and ethylene glycol.

In the second step, the mass ratio of the resin dispersion stabilizer 1 or the resin dispersion stabilizer 2 to the reducing agent is (0.001-1): 1.

The average particle size range of the conductive metal powder is 0.26-2.722 μm, and the conductive metal powder has the advantages of high specific surface area, high sphericity, narrow particle size distribution and good dispersion stability.

The mixed solvent is a mixed solution of absolute ethyl alcohol, isopropanol and deionized water, wherein the absolute ethyl alcohol, the isopropanol and the deionized water are 85 +/-3%, 5 +/-1% and 10 +/-2% of the total mass of the solvent respectively, and the mass of the mixed solvent is 1.3-1.6 times of the sum of the mass of the monomer A and the mass of the monomer B.

The copolymerization is carried out in N₂Carrying out pre-reaction for 5-60 min at 65 ℃ under the protection of atmosphere; and then reacting for 1-4 h at 75 ℃ and 80 ℃.

The conductive metal powder is one of conductive metal silver powder or conductive metal copper powder.

The second aspect of the present invention provides a method for preparing the conductive adhesive with high dispersion stability and high conductivity, comprising the steps of:

uniformly mixing a resin dispersion stabilizer 1 and a resin dispersion stabilizer 2 with conductive metal powder in a mass ratio of 1 (1-2) after drying, wherein the conductive metal powder accounts for 45-80% of the total mass of the resin dispersion stabilizer 1, the resin dispersion stabilizer 2 and the conductive metal powder, and performing high-temperature treatment to obtain the conductive adhesive with high dispersion stability and high conductivity.

The drying temperature is 90-120 ℃, and the drying time is 0.5-12 h.

The high-temperature treatment is carried out at the temperature of 80-180 ℃ for 1-3 h.

Due to the adoption of the technical scheme, the invention has the following advantages and beneficial effects:

the preparation method of the conductive adhesive with high dispersion stability and high conductivity provided by the invention is characterized in that the conductive metal powder is prepared by taking the synthetic resin dispersion stabilizer as a surfactant, one end of the resin dispersion stabilizer is polyvinylpyrrolidone, and the polyvinylpyrrolidone can well disperse and stabilize the metal powder; the other end is acrylic acid or glycidyl methacrylate, and the conductive adhesive can be directly obtained through a crosslinking reaction. Therefore, the metal powder can be stably dispersed in the conductive adhesive, the surfactant does not need to be removed, and the conductivity of the conductive adhesive can be improved while the preparation steps are simplified.

According to the preparation method of the conductive adhesive with high dispersion stability and high conductivity, provided by the invention, the average particle size range of conductive metal powder prepared by taking the resin dispersion stabilizer as the surfactant is 0.26-2.722 microns, and the conductive metal powder has the advantages of high specific surface area, high sphericity and narrow particle size distribution. The preparation method is simple and efficient, has controllable conditions, and is easy to realize industrial production. The conductive adhesive with high dispersion stability and high conductivity is obtained by copolymerization and crosslinking by using metal powder stabilized by a resin dispersion stabilizer as a conductive material and the resin dispersion stabilizer as a resin material, and has a huge application prospect in the field of printed circuits.

The invention takes the synthetic resin dispersion stabilizer as the surfactant to prepare the conductive metal powder, the dispersion stabilizer not only can well disperse and stabilize the conductive metal powder, but also can directly obtain the conductive adhesive through crosslinking reaction, and a feasible scheme is provided for efficiently preparing the conductive adhesive with good dispersion stability and high conductivity.

Drawings

FIG. 1 is a nuclear magnetic resonance carbon spectrum of resin dispersion stabilizer 1-1 prepared in example 1.

Fig. 2 is a SEM schematic view of the first conductive silver powder prepared in example 1.

Fig. 3 is a SEM schematic of the first conductive metal copper powder prepared in example 2.

FIG. 4 is a nuclear magnetic resonance carbon spectrum of resin dispersion stabilizer 2-1 prepared in example 3.

Fig. 5 is a SEM schematic view of the second conductive silver powder prepared in example 3.

Fig. 6 is a SEM schematic view of the third conductive silver powder prepared in example 4.

Detailed Description

In order to more clearly illustrate the invention, the invention is further described below in connection with preferred embodiments. It is to be understood by persons skilled in the art that the following detailed description is illustrative and not restrictive, and is not to be taken as limiting the scope of the invention.

The average particle diameter described in this application is defined as follows: when the prepared metal powder is spherical, the diameter of the sphere is obtained; when non-spherical, the diameter is the average of the major and minor axes of the metal powder.

Example 1

The method for producing the resin dispersion stabilizer 1 includes the steps of: 3.6g of acrylic acid and 11.1g of N-vinyl pyrrolidone are mixed uniformly in a three-neck flask; then, in N₂Under the protection of atmosphere, a mixed solution of 18.81g of absolute ethyl alcohol, 0.99g of isopropanol, 2.20g of deionized water and 0.60g of azobisisobutyronitrile is added. Reaction system is N₂Under the protection of atmosphere, heating to 65 ℃, and pre-reacting for 0.5 h; subsequently, the temperature was raised to 75 ℃ and 80 ℃ in this order, and the reaction was carried out for 3 hours each to obtain 1-1 as a resin dispersion stabilizer. FIG. 1 is a nuclear magnetic resonance carbon spectrum of resin dispersion stabilizer 1-1 prepared in example 1.

The preparation method of the conductive silver powder comprises the following steps:

step one, preparing a metal salt solution: dissolving 3.4g of silver nitrate into 10mL of deionized water, and dropwise adding 5mL of 25-28% concentrated ammonia water to obtain a clear and transparent solution;

step two, preparation of a reducing agent solution: dissolving 0.034g of resin dispersion stabilizer 1-1 and 2g of 1, 4-dihydrophthalazine-5-ol in 40mL of deionized water, and placing the solution in a 10 ℃ constant temperature water bath to be stirred and mixed uniformly;

thirdly, mixing and reacting the metal salt solution and the reducing agent solution: the metal salt solution prepared in the first step was slowly dropped into the reducing agent solution prepared in the second step using a peristaltic pump at a dropping rate of 0.0625 mL/min. And after the dropwise addition of the metal salt solution is finished, continuously reacting for 30min at the temperature of 10 ℃ to obtain an orange suspension, filtering, and washing with absolute ethyl alcohol and deionized water to obtain the first conductive silver powder. Fig. 2 is a SEM schematic view of the first conductive silver powder prepared in example 1.

The particle size of the first conductive silver powder prepared in this example is shown in table 1:

TABLE 1 particle size of first conductive silver powder

Sample (I)	D10/μm	D50/μm	D90/μm
				Silver powder	1.767	2.722	3.735

Example 2

The preparation method of the conductive metal copper powder comprises the following steps:

step one, preparing a metal salt solution: dissolving 5.4g of copper chloride in 24mL of deionized water, and dropwise adding 11.5mL of 25-28% concentrated ammonia water to obtain a clear and transparent solution;

step two, preparation of a reducing agent solution: 0.68g of resin dispersion stabilizer 1-1 (prepared in example 1) and 3g of 1, 4-dihydrophthalazin-5-ol were dissolved in 80mL of deionized water, and the solution was stirred and mixed uniformly in a constant temperature water bath at 20 ℃;

thirdly, mixing and reacting the metal salt solution and the reducing agent solution: and slowly dropwise adding the metal salt solution prepared in the first step into the reducing agent solution prepared in the second step by using a peristaltic pump, wherein the dropwise adding speed is 0.036 mL/min. And after the dropwise addition of the metal salt solution is finished, continuously reacting for 30min at the temperature of 20 ℃ to obtain a suspension, filtering, and washing with absolute ethyl alcohol and deionized water to obtain the first conductive metal copper powder. Fig. 3 is a SEM schematic of the first conductive metal copper powder prepared in example 2.

The particle size of the first conductive metal copper powder prepared in this example is shown in table 2:

TABLE 2 first conductive Metal copper powder particle size

Sample (I)	D10/μm	D50/μm	D90/μm
				Copper powder	0.937	1.149	1.371

Example 3

The preparation method of the resin dispersion stabilizer 2 includes the steps of: 1.78g of glycidyl methacrylate and 11.1g of N-vinyl pyrrolidone are mixed uniformly in a three-neck flask; then, in N₂Under the protection of an atmosphere, a mixed solution of 16.52g of absolute ethyl alcohol, 0.87g of isopropyl alcohol, 1.93g of deionized water and 0.52g of azobisisobutyronitrile is added. Reaction system is N₂Under the protection of atmosphere, heating to 65 ℃, and pre-reacting for 0.5 h; then, the temperature is raised to 75 ℃ and 80 ℃ in sequence, and the reaction is carried out for 3h respectively to prepare the resin dispersion stabilizer 2-1. FIG. 4 is a nuclear magnetic resonance carbon spectrum of resin dispersion stabilizer 2-1 prepared in example 3.

step one, preparing a metal salt solution: dissolving 6.8g of silver nitrate into 24mL of deionized water, and dropwise adding 11.5mL of 25-28% concentrated ammonia water to obtain a clear and transparent solution;

step two, preparation of a reducing agent solution: dissolving 1.02g of resin dispersion stabilizer 2-1 and 3.0g of 1, 4-dihydrophthalazine-5-alcohol in 80mL of deionized water, and placing the solution in a constant-temperature water bath at 20 ℃ to be stirred and mixed uniformly;

thirdly, mixing and reacting the metal salt solution and the reducing agent solution: and slowly dripping the reducing agent solution prepared in the second step into the metal salt solution prepared in the first step by using a peristaltic pump, wherein the dripping speed is 0.066mL/min, continuously reacting for 30min at the temperature of 20 ℃ after finishing dripping to obtain a suspension, filtering, and washing by using absolute ethyl alcohol and deionized water to obtain the second conductive metal silver powder. Fig. 5 is a SEM schematic view of the second conductive silver powder prepared in example 3.

The particle diameters of the second conductive silver powders prepared in this example are shown in table 3:

TABLE 3 particle size of the second conductive silver powder

Sample (I)	D10/μm	D50/μm	D90/μm
				Silver powder	0.947	1.025	1.145

Example 4

step one, preparing a metal salt solution: dissolving 10.2g of silver nitrate into 24mL of deionized water, and dropwise adding 11.5mL of 25-28% concentrated ammonia water to obtain a clear and transparent solution;

step two, preparation of a reducing agent solution: dissolving 1.02g of resin dispersion stabilizer 2-1 (prepared in example 3) and 3.0g of 1, 4-dihydrophthalazin-5-ol in 80mL of deionized water, and placing the solution in a constant-temperature water bath at 20 ℃ to be uniformly stirred and mixed;

thirdly, mixing and reacting the metal salt solution and the reducing agent solution: and slowly dripping the metal salt solution prepared in the first step into the reducing agent solution prepared in the second step by using a peristaltic pump, wherein the dripping speed is 0.05mL/min, continuously reacting for 30min at the temperature of 20 ℃ after finishing dripping to obtain a suspension, filtering, and washing by using absolute ethyl alcohol and deionized water to obtain the third conductive metal silver powder. Fig. 6 is a SEM schematic view of the third conductive silver powder prepared in example 4.

The particle size of the third conductive silver powder prepared in this example is shown in table 4:

TABLE 4 third conductive silver powder particle size

Sample (I)	D10/μm	D50/μm	D90/μm
				Silver powder	1.062	1.361	1.816

Example 5

The preparation method of the conductive adhesive with high dispersion stability and high conductivity comprises the following steps:

isolation of the binary copolymer: 5g of the resin dispersion stabilizer 1-1 prepared in example 1 and 5g of the resin dispersion stabilizer 2-1 prepared in example 3 were weighed, respectively, and vacuum-dried at a temperature of 110 ℃ for 2 hours to remove the solvent, thereby obtaining a solid resin.

Preparing the conductive adhesive: 1g of the above-mentioned dried resin dispersion stabilizer 1-1, 1g of the above-mentioned dried resin dispersion stabilizer 2-1 and 3g of the third conductive silver powder prepared in example 4 were weighed, respectively, uniformly mixed by mechanical stirring, and then heat-treated at a temperature of 150 ℃ for 3 hours to prepare a conductive paste having high dispersion stability and high conductivity. The properties are shown in table 5:

TABLE 5 conductive paste Performance parameters and Dispersion stability of silver powder in conductive paste

Example 6

isolation of the binary copolymer: 5g of the resin dispersion stabilizer 1-1 prepared in example 1 and 5g of the resin dispersion stabilizer 2-1 prepared in example 3 were weighed, respectively, and vacuum-dried at a temperature of 110 ℃ for 3 hours to remove the solvent, thereby obtaining a solid resin.

Preparing the conductive adhesive: 1g of the dried resin dispersion stabilizer 1-1, 2g of the dried resin dispersion stabilizer 2-1, and 3.7g of the first conductive metal copper powder prepared in example 2 were weighed, mixed uniformly by mechanical stirring, and then heat-treated at 150 ℃ for 3 hours to prepare a conductive paste having high dispersion stability and high conductivity. The properties are shown in Table 6:

TABLE 6 conductive paste Performance parameters and Dispersion stability of copper powder in conductive pastes

Example 7

isolation of the binary copolymer: 5g of the resin dispersion stabilizer 1-1 prepared in example 1 and 5g of the resin dispersion stabilizer 2-1 prepared in example 3 were weighed, respectively, and vacuum-dried at a temperature of 110 ℃ for 2 hours to remove the solvent, thereby obtaining solid resins.

Preparing the conductive adhesive: 1g of the above-mentioned dried resin dispersion stabilizer 1-1, 1.5g of the above-mentioned dried resin dispersion stabilizer 2-1 and 4.7g of the third conductive silver powder prepared in example 4 were weighed, respectively, uniformly mixed by mechanical stirring, and then heat-treated at a temperature of 150 ℃ for 3 hours to prepare a conductive paste having high dispersion stability and high conductivity. The properties are shown in Table 7:

TABLE 7 conductive paste Performance parameters and Dispersion stability of silver powder in conductive paste

Example 8

isolation of the binary copolymer: 5g of the resin dispersion stabilizer 1-1 prepared in example 1 and 5g of the resin dispersion stabilizer 2-1 prepared in example 3 were weighed, respectively, and vacuum-dried at 90 ℃ for 3 hours to remove the solvent, thereby obtaining a solid resin.

Preparing the conductive adhesive: 2g of the above-mentioned dried resin dispersion stabilizer 1-1, 3g of the above-mentioned dried resin dispersion stabilizer 2-1 and 6g of the third conductive silver powder prepared in example 4 were weighed, respectively, uniformly mixed by mechanical stirring, and then heat-treated at a temperature of 150 ℃ for 3 hours to prepare a conductive paste having high dispersion stability and high conductivity. The properties are shown in Table 8:

TABLE 8 conductive paste Performance parameters and Dispersion stability of silver powder in conductive paste

Example 9

Preparing the conductive adhesive: 3g of the above-mentioned dried resin dispersion stabilizer 1-1, 6g of the above-mentioned dried resin dispersion stabilizer 2-1 and 8g of the third conductive silver powder prepared in example 4 were weighed, respectively, uniformly mixed by mechanical stirring, and then heat-treated at a temperature of 150 ℃ for 3 hours to prepare a conductive paste having high dispersion stability and high conductivity. The properties are shown in Table 9:

TABLE 9 conductive paste Performance parameters and Dispersion stability of silver powder in conductive paste

Example 10

The method for producing the resin dispersion stabilizer 1 includes the steps of: 0.90g of acrylic acid and 11.1g N-vinyl pyrrolidone are mixed uniformly in a three-neck flask; then, in N₂Under the protection of atmosphere, a mixed solution of 15.39g of absolute ethyl alcohol, 0.90g of isopropanol, 1.80g of deionized water and 0.48g of azobisisobutyronitrile is added. Reaction system is N₂Under the protection of atmosphere, heating to 65 ℃, and pre-reacting for 0.5 h; then, the temperature is raised to 75 ℃ and 80 ℃ in sequence, and the reaction is carried out for 2h respectively to prepare the resin dispersion stabilizer 1-2.

Example 11

The preparation method of the resin dispersion stabilizer 2 includes the steps of: 0.89g of glycidyl methacrylate and 11.1g N-vinyl pyrrolidone are mixed uniformly in a three-neck flask; then, in N₂Under the protection of atmosphere, 15.41g of absolute ethyl alcohol is addedA mixed solution of 0.81g of isopropyl alcohol, 1.86g of deionized water and 0.48g of azobisisobutyronitrile. Reaction system is N₂Under the protection of atmosphere, heating to 65 ℃, and pre-reacting for 0.5 h; then, the temperature is raised to 75 ℃ and 80 ℃ in sequence, and the reaction is carried out for 3h respectively to prepare the resin dispersion stabilizer 2-2.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. A conductive adhesive with high dispersion stability and high conductivity is characterized by being prepared from a resin dispersion stabilizer 1, a resin dispersion stabilizer 2 and conductive metal powder, wherein the mass ratio of the resin dispersion stabilizer 1 to the resin dispersion stabilizer 2 is 1 (1-2), and the conductive metal powder accounts for 45-80% of the total mass of the resin dispersion stabilizer 1, the resin dispersion stabilizer 2 and the conductive metal powder;

the preparation method of the resin dispersion stabilizer 1 includes the steps of: initiating copolymerization of a monomer A and a monomer B in a molar ratio of (1-16): 1 in a mixed solvent by an initiator to obtain the resin dispersion stabilizer 1;

the monomer A is N-vinyl pyrrolidone, the monomer B is acrylic acid, the mass of the initiator is 4.0-8.0% of the total mass of the monomer A and the monomer B, and the initiator is azobisisobutyronitrile;

the preparation method of the resin dispersion stabilizer 2 includes the steps of: initiating copolymerization of a monomer A and a monomer B in a molar ratio of (1-16): 1 in a mixed solvent by an initiator to obtain the resin dispersion stabilizer 2;

the monomer A is N-vinyl pyrrolidone, the monomer B is glycidyl methacrylate, the mass of the initiator is 4.0-8.0% of the total mass of the monomer A and the monomer B, and the initiator is azobisisobutyronitrile;

thirdly, mixing and reacting the metal salt solution and the reducing agent solution: slowly dripping the metal salt solution prepared in the first step into the reducing agent solution prepared in the second step, or slowly dripping the reducing agent solution prepared in the second step into the metal salt solution prepared in the first step, wherein the dripping speed is 0.02 mL/min-1.5 mL/min; after the dropwise addition, the reaction is continued for 10 to 60 minutes at the temperature of 5 to 40 ℃ to obtain the target product.

2. The conductive paste as claimed in claim 1, wherein the metal salt in the first step is selected from the group consisting of: one of silver nitrate, silver carbonate, silver sulfate, silver oxalate, copper nitrate or copper chloride;

the molar concentration of the metal salt solution in the first step is 1.67 mol/L.

3. The conductive paste as claimed in claim 1, wherein the reducing agent in the second step is selected from the group consisting of: 1, 4-dihydrophthalazin-5-ol, ascorbic acid, hydrazine hydrate or ethylene glycol.

4. The conductive adhesive according to claim 1, wherein the mass ratio of the resin dispersion stabilizer 1 or the resin dispersion stabilizer 2 to the reducing agent in the second step is (0.001-1): 1;

the average particle size range of the conductive metal powder is 0.26-2.722 mu m.

5. The conductive adhesive according to claim 1, wherein the mixed solvent is a mixed solution of absolute ethyl alcohol, isopropyl alcohol and deionized water, wherein the absolute ethyl alcohol, the isopropyl alcohol and the deionized water are respectively 85 ± 3%, 5 ± 1% and 10 ± 2% of the total mass of the solvent, and the mass of the mixed solvent is 1.3-1.6 times of the sum of the masses of the monomer A and the monomer B.

6. The conductive adhesive of claim 1, wherein the copolymerization is at N₂The preparation is carried out under the protection of atmosphere, and pre-reaction is carried out for 5min to 60min at 65 ℃; then the reaction is carried out for 1 to 4 hours at the temperature of 75 ℃ and 80 ℃.

7. The conductive paste as claimed in claim 1, wherein the conductive metal powder is one of a conductive metal silver powder and a conductive metal copper powder.

8. A method for preparing the conductive adhesive according to any one of claims 1 to 7, comprising the steps of:

uniformly mixing a resin dispersion stabilizer 1 and a resin dispersion stabilizer 2 which are dried in a mass ratio of 1 (1-2) with conductive metal powder, wherein the conductive metal powder accounts for 45-80% of the total mass of the resin dispersion stabilizer 1, the resin dispersion stabilizer 2 and the conductive metal powder, and performing high-temperature treatment to obtain a target object.

9. The preparation method according to claim 8, wherein the drying temperature is 90-120 ℃ and the drying time is 0.5-12 h; the temperature of the high-temperature treatment is 80-180 ℃, and the time is 1-3 h.