Micro-nano composite conductive paste and preparation method thereof

Abstract

The invention relates to a micro-nano composite conductive paste and a preparation method thereof, and relates to the technical field of electronic materials, the micro-nano composite conductive paste is prepared from the following raw materials by weight: 65-85 parts of a conductive filler, 10-15 parts of a composite solvent, 2-4 parts of an auxiliary agent, and 3-5 parts of an organic carrier; the conductive filler is formed by mixing micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets and GNP (at) PDA-Ag core-shell type nanoparticles according to the mass ratio of (2 to 3): (1 to 2): (2 to 3): (0.1 to 0.3): (0.8 to 1.2). The conductive paste is higher in cost performance, better in conductivity and more excellent in stability and adhesion performance.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic materials, and in particular to a micro-nano composite conductive paste and a preparation method thereof. Background Art

[0002] With the rapid development of electronic information technology, conductive paste, as a key material in the manufacture of electronic components, has a direct impact on important indicators such as the conductivity, reliability, and service life of electronic devices. As electronic devices move towards miniaturization and integration, higher requirements are placed on the conductivity, adhesion, and stability of conductive pastes. Traditional single-metal conductive pastes, such as pure silver or pure copper, have limitations in their applications. While pure silver paste offers excellent conductivity and chemical stability, its high cost limits its large-scale application. Pure copper paste, on the other hand, is relatively inexpensive, but copper easily oxidizes in air, resulting in decreased conductivity and impacting the long-term stability of electronic devices. In order to reduce costs and improve the performance of conductive pastes, researchers have tried to prepare conductive pastes by compounding silver and copper. However, in existing silver-copper composite conductive pastes, the particle size distribution of metal particles is not reasonable, and they are often single micron- or nano-sized particles, which makes it difficult for the conductivity and stability of the paste to reach the ideal state. The contact resistance between micron-sized particles is large, and nano-sized particles are prone to agglomeration, affecting the uniformity and fluidity of the paste. In addition, the preparation methods of conductive pastes on the market also have the problems of complex process, high energy consumption, environmental pollution, insufficient compatibility and wettability between organic carriers and conductive powders, and easy delamination and cracking during the curing or sintering process.

[0003] To address the above-mentioned issues, a Chinese invention patent application with publication number CN116189960A discloses a silver-copper composite conductive paste capable of low-temperature sintering, its preparation method, and application, comprising the following components in weight percentage: 20-80% micron copper particles; 10-60% nano-silver flakes; 1-20% nano-silver particles; and 1-10% organic carrier. The silver-copper composite conductive paste capable of low-temperature sintering provided by the invention utilizes silver and copper of various sizes and morphologies, using large-sized silver flakes and micron copper particles as a skeleton and small-sized nano-silver particles as fillers, thereby reducing gaps and improving performance. The silver-copper composite conductive paste capable of low-temperature sintering of the invention utilizes a large number of micron copper particles, which improves the thermal and electrical conductivity of the paste while effectively reducing costs. However, its adhesion and stability still need to be further improved.

[0004] It can be seen that the development of a micro-nano composite conductive paste and its preparation method with higher cost performance, better conductivity, better stability and adhesion performance, simple and environmentally friendly preparation process meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the conductive paste field. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a micro-nano composite conductive paste and a preparation method thereof with higher cost performance, better conductivity, better stability and adhesion performance, and simple and environmentally friendly preparation process.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is a micro-nano composite conductive paste, which is made of the following raw materials in parts by weight: 65-85 parts of conductive filler, 10-15 parts of composite solvent, 2-4 parts of additive, and 3-5 parts of organic carrier; the conductive filler is a mixture of micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of (2-3):(1-2):(2-3):(0.1-0.3):(0.8-1.2).

[0007] Preferably, the average particle size of the micron-sized silver powder is 5-10 μm, and the shape is spherical.

[0008] Preferably, the nano-scale silver powder has an average particle size of 40-100 nm and a spherical shape.

[0009] Preferably, the micron-sized copper powder has an average particle size of 2-5 μm and is in the shape of a flake.

[0010] Preferably, the graphene nanosheets have a diameter of 5-10 μm and a thickness of 3-10 nm, and are provided by Shanghai Jiyi Biotechnology Co., Ltd.

[0011] Preferably, there is no special requirement for the source of the GNP@PDA-Ag core-shell nanoparticles. In one embodiment of the present invention, the GNP@PDA-Ag core-shell nanoparticles are prepared according to the method of Example 1 of the Chinese invention patent with authorization publication number CN113121886B.

[0012] Preferably, the composite solvent is a mixture of propylene glycol methyl ether, terpineol, ethanolamine, and polyvinyl pyrrolidone in a mass ratio of (30-40): (40-50): (5-10): (2-5).

[0013] Preferably, the polyvinyl pyrrolidone is polyvinyl pyrrolidone K-30 with a molecular weight of 40,000.

[0014] Preferably, the auxiliary agent is a mixture of a coupling agent and a dispersant in a mass ratio of 1:(0.8-1.2).

[0015] Preferably, the coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

[0016] Preferably, the dispersant is BASF dispersant Dispex®AA4040.

[0017] Preferably, the organic carrier comprises the following components in parts by weight: 5-8 parts of ethyl cellulose, 1-3 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1-3 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, 0.8-1.2 parts of polyethylene glycol diacrylate, 1-2 parts of hydrogenated rosin pentaerythritol ester, 0.8-1.2 parts of meso-tetramethyl-meso-tetra-p-aminophenylcalix[4]pyrrole, and 0.05-0.08 parts of initiator.

[0018] Preferably, the viscosity of the ethyl cellulose is 80-120 mPa.s; and the weight average molecular weight of the polyethylene glycol diacrylate is 10,000.

[0019] Preferably, there is no special requirement for the source of the Meso tetramethyl meso tetra-p-aminophenyl calix [4] pyrrole. In one embodiment of the present invention, the preparation method of the Meso tetramethyl meso tetra-p-aminophenyl calix [4] pyrrole is described in: Guo Yong, Shao Shijun, He Lijun, et al. Synthesis and Characterization of Meso Tetramethyl meso tetra-p-aminophenyl calix [4] pyrrole [J]. Chemical Reagents, 2002 (6): 344-345.

[0020] Preferably, the initiator is azobisisobutyronitrile.

[0021] Another object of the present invention is to provide a method for preparing the micro-nano composite conductive slurry, comprising the following steps: plasma-treating the conductive filler and mixing it with other raw materials; stirring the mixture in an inert gas atmosphere at 60-70°C in a planetary mixer at a speed of 1500-1800 r / min for 3-5 hours to obtain a uniform micro-nano composite conductive slurry.

[0022] Preferably, the inert gas is any one of nitrogen, helium, neon and argon.

[0023] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The preparation method of the micro-nano composite conductive paste disclosed in the present invention is simple and easy to operate, convenient to operate and control, high in preparation efficiency and finished product qualification rate, low in dependence on equipment, easy to be mass-produced industrially, and has high promotion and application value.

[0024] (2) The micro-nano composite conductive paste disclosed in the present invention is made of the following raw materials in parts by weight: 65-85 parts of conductive filler, 10-15 parts of composite solvent, 2-4 parts of auxiliary agent, and 3-5 parts of organic carrier; the conductive filler is a mixture of micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of (2-3):(1-2):(2-3):(0.1-0.3):(0.8-1.2). Through the interaction between the raw materials, the conductive paste is more cost-effective, has better conductivity, and has better stability and adhesion properties than traditional products.

[0025] (3) The micro-nano composite conductive paste disclosed in the present invention comprises a conductive filler composed of micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of (2-3):(1-2):(2-3):(0.1-0.3):(0.8-1.2); the micron-sized silver powder and the micron-sized copper powder form a skeleton support, the nano-sized silver powder fills the gaps between the micron-sized particles, and the graphene nanosheets and the GNP@PDA-Ag core-shell particles construct a nano-scale conductive bridge, forming a three-level network of "macroscopic skeleton-mesoscopic filling-nanobridge". The interaction of these components can effectively improve the conductivity and density of the paste. This micro-nano composite structural design fully utilizes the advantages of filler components with different particle sizes and overcomes the shortcomings of particles with a single particle size. The micron-sized silver powder has an average particle size of 5-10 μm and a spherical shape; the nano-sized silver powder has an average particle size of 40-100 nm and a spherical shape; the micron-sized copper powder has an average particle size of 2-5 μm and a flake shape; and the graphene nanosheets have a diameter of 5-10 μm and a thickness of 3-10 nm. This particle size combination enables the filler components to form a densely packed structure in the slurry, reducing voids and contact resistance, thereby improving the slurry's conductivity. Furthermore, the optimal particle size distribution ensures the slurry's fluidity and workability. The introduction of graphene nanosheets and GNP@PDA-Ag core-shell particles overcomes the limitations of traditional metal composite systems, constructing a "metal-two-dimensional material" heterojunction. This utilizes the high carrier mobility of graphene and the low resistivity of silver and copper to create a synergistic conductive effect. Through the synergistic transmission of graphene's delocalized π electrons and silver and copper's free electrons, a composite conductive mode of "ballistic transport-ohmic conduction" is achieved, significantly improving electron mobility. This composite design of inorganic nanomaterials and metal powders is a first in the field of conductive pastes.

[0026] (4) The micro-nano composite conductive paste disclosed in the present invention comprises a composite solvent comprising propylene glycol methyl ether, terpineol, ethanolamine, and polyvinyl pyrrolidone in a mass ratio of (30-40):(40-50):(5-10):(2-5). The composite solvent employs a water-based solvent + oil-based solvent composite technology, and uses organic solvents with different surface tensions. The organic solvents contain a large number of active functional groups, which can enhance the bonding between the high molecular weight polymer in the organic carrier and the conductive filler, and between the conductive silver paste and the cell substrate. The oil-based solvent can lubricate the silver powder and reduce friction between the powders, thereby increasing the arrangement and stacking density of the conductive filler in the silver grid lines after curing. Furthermore, the oil-based solvent can also weaken the friction between the conductive paste and the screen during printing, thereby improving and enhancing the fine gridding and high-speed printing properties of the conductive paste. Aqueous solvents can improve the compatibility and wettability of conductive fillers with the resin in the organic carrier, and give the conductive paste lower viscosity and better fluidity, so that the conductive paste has excellent printability and long-term use, and has excellent printing of extremely fine linearity.

[0027] (5) The micro-nano composite conductive paste disclosed in the present invention, the organic carrier includes the following components in parts by weight: 5-8 parts of ethyl cellulose, 1-3 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1-3 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, 0.8-1.2 parts of polyethylene glycol diacrylate, 1-2 parts of hydrogenated rosin pentaerythritol ester, 0.8-1.2 parts of meso-tetramethyl-meso-tetra-p-aminophenyl cup[4]pyrrole, and 0.05-0.08 parts of initiator. Through the interaction and synergy of the various components, an interpenetrating polymer network is formed during the curing process. Compounding additives further enhance the compatibility and wettability between the organic vehicle and the conductive filler, preventing collapse or significant flow of the conductive paste during low-temperature sintering and curing. This addresses the challenges of traditional conductive pastes, such as poor control of sub-grid width during narrow-aperture screen printing, prone to printing and cosmetic defects during mass production, weak electrical performance, low production capacity, and low main grid adhesion. The macrocyclic structure of cuppyrrole combined with its zwitterionic properties creates a three-in-one filler interface control system: "recognition-anchoring-dispersion." This solves the problem of coordinated dispersion of multi-scale fillers and significantly improves dispersion uniformity. By rationally controlling the ratios of the various components, the paste exhibits excellent rheological properties, conductivity, and stability. DETAILED DESCRIPTION

[0028] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are merely examples, and those skilled in the art may conceive of other obvious variations.

[0029] Example 1 A micro-nano composite conductive paste is prepared from the following raw materials, measured in parts by weight: 65 parts of a conductive filler, 10 parts of a composite solvent, 2 parts of an additive, and 3 parts of an organic carrier; the conductive filler is prepared by mixing micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of 2:1:2:0.1:0.8.

[0030] The average particle size of the micron-sized silver powder is 5 μm and the shape is spherical; the average particle size of the nano-sized silver powder is 40 nm and the shape is spherical; the average particle size of the micron-sized copper powder is 2 μm and the shape is flaky; the graphene nanosheets have a diameter of 5-10 μm and a thickness of 3-10 nm, and are provided by Shanghai Jiyi Biotechnology Co., Ltd.; the GNP@PDA-Ag core-shell nanoparticles are made according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN113121886B.

[0031] The composite solvent is a mixture of propylene glycol methyl ether, terpineol, ethanolamine, and polyvinyl pyrrolidone in a mass ratio of 30:40:5:2; the polyvinyl pyrrolidone is polyvinyl pyrrolidone K-30 with a molecular weight of 40,000; the auxiliary agent is a mixture of a coupling agent and a dispersant in a mass ratio of 1:0.8; the coupling agent is a silane coupling agent KH550; and the dispersant is BASF dispersant Dispex®AA4040.

[0032] The organic carrier includes the following components in parts by weight: 5 parts of ethyl cellulose, 1 part of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1 part of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, 0.8 parts of polyethylene glycol diacrylate, 1 part of hydrogenated rosin pentaerythritol ester, 0.8 parts of meso-tetramethyl-meso-tetra-p-aminophenylcalix[4]pyrrole, and 0.05 parts of initiator.

[0033] The viscosity of the ethyl cellulose is 80-120 mPa.s; the weight average molecular weight of the polyethylene glycol diacrylate is 10,000; the preparation method of the Meso tetramethyl meso tetra-p-aminophenyl calix [4] pyrrole can be found in: Guo Yong, Shao Shijun, He Lijun, et al. Synthesis and characterization of Meso tetramethyl meso tetra-p-aminophenyl calix [4] pyrrole [J]. Chemical Reagents, 2002 (6): 344-345; the initiator is azobisisobutyronitrile.

[0034] A preparation method of the micro-nano composite conductive paste comprises the following steps: plasma-treating a conductive filler and then mixing it with other raw materials; stirring the mixture in an inert gas atmosphere at 60° C. at a speed of 1500 r / min for 3 hours in a planetary mixer to obtain a uniform micro-nano composite conductive paste; the inert gas is nitrogen.

[0035] Example 2 A micro-nano composite conductive paste is prepared from the following raw materials, measured in parts by weight: 70 parts of a conductive filler, 12 parts of a composite solvent, 2.5 parts of an additive, and 3.5 parts of an organic carrier; the conductive filler is prepared by mixing micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of 2.2:1.3:2.2:0.15:0.9.

[0036] The average particle size of the micron-sized silver powder is 6 μm and the shape is spherical; the average particle size of the nano-sized silver powder is 60 nm and the shape is spherical; the average particle size of the micron-sized copper powder is 3 μm and the shape is flaky; the graphene nanosheets have a diameter of 5-10 μm and a thickness of 3-10 nm, and are provided by Shanghai Jiyi Biotechnology Co., Ltd.; the GNP@PDA-Ag core-shell nanoparticles are made according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN113121886B.

[0037] The composite solvent is a mixture of propylene glycol methyl ether, terpineol, ethanolamine, and polyvinyl pyrrolidone in a mass ratio of 33:42:6:3; the polyvinyl pyrrolidone is polyvinyl pyrrolidone K-30 with a molecular weight of 40,000; the auxiliary agent is a mixture of a coupling agent and a dispersant in a mass ratio of 1:0.9; the coupling agent is a silane coupling agent KH560; and the dispersant is BASF's dispersant Dispex®AA4040.

[0038] The organic vehicle comprises the following components in parts by weight: 6 parts of ethyl cellulose, 1.5 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1.5 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, 0.9 parts of polyethylene glycol diacrylate, 0.9 parts of hydrocortisone ...0.9 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 0.9 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 0.9 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1 1.2 parts of pentaerythritol ester, 0.9 parts of Meso-tetramethyl-meso-tetra-p-aminophenyl cup[4]pyrrole, and 0.06 parts of initiator; the viscosity of the ethyl cellulose is 80-120 mPa.s; the weight average molecular weight of the polyethylene glycol diacrylate is 10,000; the preparation method of the Meso-tetramethyl-meso-tetra-p-aminophenyl cup[4]pyrrole, see: Guo Yong, Shao Shijun, He Lijun, et al. Synthesis and characterization of Meso-tetramethyl-meso-tetra-p-aminophenyl cup[4]pyrrole [J]. Chemical Reagents, 2002(6): 344345; the initiator is azobisisobutyronitrile.

[0039] A method for preparing the micro-nano composite conductive paste comprises the following steps: subjecting a conductive filler to plasma treatment and then mixing it with other raw materials; stirring the mixture in an inert gas atmosphere at 63°C and a speed of 1600 r / min for 3.5 hours in a planetary mixer to obtain a uniform micro-nano composite conductive paste; the inert gas is helium.

[0040] Example 3 A micro-nano composite conductive paste is prepared from the following raw materials, measured in parts by weight: 75 parts of a conductive filler, 13 parts of a composite solvent, 3 parts of an additive, and 4 parts of an organic carrier; the conductive filler is prepared by mixing micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of 2.5:1.5:2.5:0.2:1.

[0041] The average particle size of the micron-scale silver powder is 7 μm and the shape is spherical; the average particle size of the nano-scale silver powder is 70 nm and the shape is spherical; the average particle size of the micron-scale copper powder is 3.5 μm and the shape is flake; the diameter of the graphene nanosheet is 5-10 μm and the thickness is 3-10 nm, and it is provided by Shanghai Jiyi Biotechnology Co., Ltd.; the GNP@PDA-Ag core-shell nanoparticles are obtained according to the Chinese invention patent with the authorization announcement number CN113121886B. The composite solvent is prepared by the method of Example 1; the composite solvent is a mixture of propylene glycol methyl ether, terpineol, ethanolamine, and polyvinyl pyrrolidone in a mass ratio of 35:45:7.5:3.5; the polyvinyl pyrrolidone is polyvinyl pyrrolidone K-30 with a molecular weight of 40,000; the auxiliary agent is a coupling agent and a dispersant mixed in a mass ratio of 1:1; the coupling agent is a silane coupling agent KH570; and the dispersant is BASF dispersant Dispex®AA4040.

[0042] The organic carrier comprises the following components in parts by weight: 6.5 parts of ethyl cellulose, 2 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, 1 part of polyethylene glycol diacrylate, 1.5 parts of hydrogenated rosin pentaerythritol ester, 1 part of Meso-tetramethyl-meso-tetra-p-aminophenyl cup [4] pyrrole, and 0.065 parts of initiator; the viscosity of the ethyl cellulose is 80-120 mPa.s; the weight average molecular weight of the polyethylene glycol diacrylate is 10,000; the preparation method of the Meso-tetramethyl-meso-tetra-p-aminophenyl cup [4] pyrrole, see: Guo Yong, Shao Shijun, He Lijun, et al. Meso Synthesis and characterization of tetramethyl meso tetra-p-aminophenyl cup[4]pyrrole[J]. Chemical Reagents, 2002(6):344345; the initiator is azobisisobutyronitrile.

[0043] A preparation method of the micro-nano composite conductive paste comprises the following steps: plasma-treating a conductive filler and then mixing it with other raw materials; stirring the mixture in an inert gas atmosphere at 65°C at a speed of 1650 r / min for 4 hours to obtain a uniform micro-nano composite conductive paste; the inert gas is neon.

[0044] Example 4 A micro-nano composite conductive paste is prepared from the following raw materials, measured in parts by weight: 80 parts of a conductive filler, 14 parts of a composite solvent, 3.5 parts of an additive, and 4.5 parts of an organic vehicle; the conductive filler is prepared by mixing micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of 2.8:1.8:2.8:0.25:1.1.

[0045] The average particle size of the micron-sized silver powder is 9 μm and the shape is spherical; the average particle size of the nano-sized silver powder is 90 nm and the shape is spherical; the average particle size of the micron-sized copper powder is 4 μm and the shape is flaky; the graphene nanosheets have a diameter of 5-10 μm and a thickness of 3-10 nm and are provided by Shanghai Jiyi Biotechnology Co., Ltd.; the GNP@PDA-Ag core-shell nanoparticles are prepared according to the method of Example 1 of the Chinese invention patent with authorization announcement number CN113121886B; the composite solvent is propylene glycol. Methyl ether, terpineol, ethanolamine, and polyvinyl pyrrolidone are mixed in a mass ratio of 38:48:9:4.5; the polyvinyl pyrrolidone is polyvinyl pyrrolidone K-30 with a molecular weight of 40,000; the auxiliary agent is a coupling agent and a dispersant mixed in a mass ratio of 1:1.1; the coupling agent is a silane coupling agent KH550, a silane coupling agent KH560, and a silane coupling agent KH570 mixed in a mass ratio of 1:2:1; the dispersant is BASF dispersant Dispex®AA4040.

[0046] The organic vehicle includes the following components in parts by weight: 7.5 parts of ethyl cellulose, 2.5 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2.5 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, and 1.1 parts of polyethylene glycol diacrylate. , 1.9 parts of hydrogenated rosin pentaerythritol ester, 1.1 parts of Meso-tetramethyl-meso-tetra-p-aminophenyl cup [4] pyrrole, and 0.075 parts of initiator; the viscosity of the ethyl cellulose is 80-120 mPa.s; the weight-average molecular weight of the polyethylene glycol diacrylate is 10,000; the preparation method of the Meso-tetramethyl-meso-tetra-p-aminophenyl cup [4] pyrrole, see: Guo Yong, Shao Shijun, He Lijun, et al. Synthesis and characterization of Meso-tetramethyl-meso-tetra-p-aminophenyl cup [4] pyrrole [J]. Chemical Reagents, 2002 (6): 344-345; the initiator is azobisisobutyronitrile.

[0047] A method for preparing the micro-nano composite conductive paste comprises the following steps: subjecting a conductive filler to plasma treatment and then mixing it with other raw materials; stirring the mixture in an inert gas atmosphere at 68° C. at a speed of 1750 r / min for 4.5 hours to obtain a uniform micro-nano composite conductive paste; the inert gas is argon.

[0048] Example 5 A micro-nano composite conductive paste is prepared from the following raw materials, measured in parts by weight: 85 parts of a conductive filler, 15 parts of a composite solvent, 4 parts of an additive, and 5 parts of an organic carrier; the conductive filler is prepared by mixing micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of 3:2:3:0.3:1.2.

[0049] The average particle size of the micron-scale silver powder is 10 μm and the shape is spherical; the average particle size of the nano-scale silver powder is 100 nm and the shape is spherical; the average particle size of the micron-scale copper powder is 5 μm and the shape is flake; the diameter of the graphene nanosheet is 5-10 μm and the thickness is 3-10 nm, and it is provided by Shanghai Jiyi Biotechnology Co., Ltd.; the GNP@PDA-Ag core-shell nanoparticles are obtained according to the Chinese invention patent with the authorization announcement number CN113121886B. The composite solvent is prepared by the method of Example 1; the composite solvent is a mixture of propylene glycol methyl ether, terpineol, ethanolamine, and polyvinyl pyrrolidone in a mass ratio of 40:50:10:5; the polyvinyl pyrrolidone is polyvinyl pyrrolidone K-30 with a molecular weight of 40,000; the auxiliary agent is a coupling agent and a dispersant mixed in a mass ratio of 1:1.2; the coupling agent is a silane coupling agent KH550; and the dispersant is BASF dispersant Dispex®AA4040.

[0050] The organic carrier comprises the following components in parts by weight: 8 parts of ethyl cellulose, 3 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, 1.2 parts of polyethylene glycol diacrylate, 2 parts of hydrogenated rosin pentaerythritol ester, 1.2 parts of Meso-tetramethyl-meso-tetra-p-aminophenyl cup [4] pyrrole, and 0.08 parts of initiator; the viscosity of the ethyl cellulose is 80-120 mPa.s; the weight average molecular weight of the polyethylene glycol diacrylate is 10,000; the preparation method of the Meso-tetramethyl-meso-tetra-p-aminophenyl cup [4] pyrrole, see: Guo Yong, Shao Shijun, He Lijun, et al. Synthesis and characterization of tetra-p-aminophenylcalix[4]pyrrole[J]. Chemical Reagents, 2002(6):344-345; the initiator is azobisisobutyronitrile.

[0051] A preparation method of the micro-nano composite conductive paste comprises the following steps: plasma-treating a conductive filler and then mixing it with other raw materials; stirring the mixture in an inert gas atmosphere at 70°C at a speed of 1800 r / min for 5 hours to obtain a uniform micro-nano composite conductive paste; the inert gas is argon.

[0052] Comparative Example 1 A micro-nano composite conductive paste and a preparation method thereof are basically the same as those in Example 1, except that an equal amount of micron-sized copper powder is used instead of GNP@PDA-Ag core-shell nanoparticles; and Meso-tetramethyl-meso-tetra-p-aminophenyl cup[4]pyrrole and ethanolamine are not added.

[0053] Comparative Example 2 A micro-nano composite conductive paste and a preparation method thereof are basically the same as those in Example 1, except that an equal amount of nano-scale silver powder is used instead of graphene nanosheets, and 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt and polyvinyl pyrrolidone are not added.

[0054] In order to further illustrate the beneficial technical effects of the micro-nano composite conductive pastes involved in various embodiments of the present invention, relevant performance tests were conducted on the micro-nano composite conductive pastes involved in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1. The test method is as follows: (1) Conductivity: Each conductive paste was pad printed on a PC substrate to form a conductive circuit with a thickness of 15 μm. The circuit was pre-cured at 150°C for 30 min and then sintered at 200°C for 2 h. After cooling to room temperature, the square resistance of the conductive paste after sintering was measured using a four-probe method. (2) Adhesion: Refer to GB / T 9286-1998 "Scratch test for paint and varnish films". Use a scratch tester to perform a scratch test on the sintered conductive film with a grid spacing of 1mm. Then use 3M tape to stick and quickly tear off the tape. Observe the peeling of the paint film and then rate the adhesion.

[0055] (3) Stability: The sintered conductive paste is made into a sheet sample and placed in a constant temperature and humidity chamber. It is stored for 1000 hours at a temperature of 85°C and a humidity of 85%. After cooling to room temperature, the square resistance is tested again according to the conductivity test method (1). The rate of change of the square resistance is calculated. The smaller the value, the better the stability.

[0056] Table 1 Performance test results of micro-nano composite conductive paste project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Square resistance (mΩ / □) 1.2 0.8 0.6 0.5 0.3 1.8 2.5 Adhesion grade (grade) 0 0 0 0 0 1 1 stability(%) 1.5 1.3 0.8 0.5 0.1 3.4 2.7 As can be seen from Table 1, the micro-nano composite conductive paste involved in the embodiment of the present invention has better conductivity, more excellent adhesion and stability than the comparative example product; the combined use of GNP@PDA-Ag core-shell nanoparticles, Meso-tetramethyl-meso-tetra-aminophenyl cup [4] pyrrole, ethanolamine, graphene nanosheets, 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt and polyvinyl pyrrolidone is beneficial to improving the above properties.

[0057] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A micro-nano composite conductive paste, characterized in that: The invention is prepared from the following raw materials in parts by weight: 65-85 parts of conductive filler, 10-15 parts of composite solvent, 2-4 parts of auxiliary agent, and 3-5 parts of organic carrier; the conductive filler is prepared by mixing micron-sized silver powder, nano-sized silver powder, micron-sized copper powder, graphene nanosheets, and GNP@PDA-Ag core-shell nanoparticles in a mass ratio of (2-3):(1-2):(2-3):(0.1-0.3):(0.8-1.2).

2. The micro-nano composite conductive paste according to claim 1, characterized in that: The average particle size of the micron-scale silver powder is 5-10 μm, and the shape is spherical; the average particle size of the nano-scale silver powder is 40-100 nm, and the shape is spherical.

3. The micro-nano composite conductive paste according to claim 1, characterized in that: The average particle size of the micron-sized copper powder is 2-5 μm, and the shape is flake-shaped; the diameter of the graphene nanosheet is 5-10 μm, and the thickness is 3-10 nm.

4. The micro-nano composite conductive paste according to claim 1, characterized in that: The composite solvent is prepared by mixing propylene glycol methyl ether, terpineol, ethanolamine and polyvinyl pyrrolidone in a mass ratio of (30-40): (40-50): (5-10): (2-5).

5. The micro-nano composite conductive paste according to claim 4, characterized in that: The polyvinyl pyrrolidone is polyvinyl pyrrolidone K-30, and has a molecular weight of 40,000.

6. The micro-nano composite conductive paste according to claim 1, characterized in that: The auxiliary agent is a mixture of a coupling agent and a dispersant in a mass ratio of 1:(0.8-1.2); the coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570; and the dispersant is BASF dispersant Dispex®AA4040.

7. The micro-nano composite conductive paste according to claim 1, characterized in that: The organic carrier includes the following components in parts by weight: 5-8 parts of ethyl cellulose, 1-3 parts of 1,3-bis(oxiranylmethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 1-3 parts of 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, 0.8-1.2 parts of polyethylene glycol diacrylate, 1-2 parts of hydrogenated rosin pentaerythritol ester, 0.8-1.2 parts of meso-tetramethyl-meso-tetra-p-aminophenylcalix[4]pyrrole, and 0.05-0.08 parts of an initiator.

8. The micro-nano composite conductive paste according to claim 7, characterized in that: The viscosity of the ethyl cellulose is 80-120 mPa.s; the weight average molecular weight of the polyethylene glycol diacrylate is 10,000; and the initiator is azobisisobutyronitrile.

9. A method for preparing the micro-nano composite conductive paste according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: subjecting the conductive filler to plasma treatment and then mixing it with other raw materials; stirring the mixture in an inert gas atmosphere at 60-70° C. and a speed of 1500-1800 r / min for 3-5 hours in a planetary mixer to obtain a uniform micro-nano composite conductive slurry.

10. The method for preparing the micro-nano composite conductive paste according to claim 9, characterized in that: The inert gas is any one of nitrogen, helium, neon and argon.