Conductive paste, and preparation method therefor and use thereof

Abstract

Provided are a conductive paste, and a preparation method therefor and the use thereof. The conductive paste comprises an organic binder, a conductive agent, an additive and a solvent. The organic binder comprises a first binder, and the first binder contains nitrogen. The weight ratio of the organic binder, the conductive agent, the additive, and the solvent is (3-10):(40-95):(0.1-3):(10-45), and the mass content of nitrogen in the conductive paste is 5,000 mg / kg or less.

Description

Conductive paste, preparation method and application thereof

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 2024113438395, filed on September 25, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of conductive materials, in particular to a conductive paste, a preparation method and application thereof. BACKGROUND

[0004] The conductive paste generally includes an organic binder, a conductive agent, a functional additive, a solvent, etc. The organic binder contains a thermoplastic resin and a thermosetting resin. The thermoplastic resin has good mechanical properties and toughness, and the thermosetting resin has good heat resistance and strength. Users can select and modify the resin according to the final performance needs, so that it is widely used in electronic components, integrated circuits, 5G and new energy fields.

[0005] Most of the existing conductive pastes use thermoplastic materials, which have poor adhesion to the substrate, are prone to fission at high temperatures, and are prone to "degeneration" during storage of the paste. SUMMARY

[0006] Embodiments of the present disclosure aim to at least solve one of the technical problems in the related art to some extent.

[0007] Therefore, one purpose of the embodiments of the present disclosure is to provide a conductive paste. By selecting an organic binder containing nitrogen elements and controlling the content of the organic binder and the additive and the content of nitrogen elements in the conductive paste, the storage stability of the conductive paste can be improved, and the adhesion of the conductive paste to the substrate after curing and the conductive stability can also be improved.

[0008] Another purpose of the embodiments of the present disclosure is to provide a preparation method of a conductive paste.

[0009] Still another purpose of the embodiments of the present disclosure relates to the application of the conductive paste.

[0010] To achieve the above purpose, a first aspect of the embodiments of the present disclosure provides a conductive paste, which includes an organic binder, a conductive agent, an additive and a solvent. The organic binder includes a first binder, and the first binder contains nitrogen elements. The weight ratio of the organic binder, the conductive agent, the additive and the solvent is (3-10):(40-95):(0.1-3):(10-45), and the mass content of nitrogen elements in the conductive paste is below 5000 mg / kg.

[0011] In some embodiments, the mass content of nitrogen element in the conductive paste is below 1000 mg / kg.

[0012] In some embodiments, the first binder comprises at least one of nitrogen-containing polyolefin, nitrogen-containing polyester, nitrogen-containing polyvinyl acetate, nitrogen-containing acrylic resin, nitrogen-containing silicone resin, nitrogen-containing epoxy resin, and nitrogen-containing fluorine-containing resin.

[0013] In some other embodiments, the organic binder further comprises a second binder, the second binder being free of nitrogen element, the second binder comprising a copolymer or a modified product of at least one structural unit of polyolefin, polyester, polyvinyl acetate, acrylic resin, silicone resin, epoxy resin, and fluorine-containing resin.

[0014] In some embodiments, the additive comprises at least one of N,N-dimethylethanolamine, 2,4,6-tris(dimethylaminomethyl)phenol, benzyl dimethyl amine, o-hydroxybenzyl dimethyl amine, N-(2-hydroxyphenyl)-N',N'-dimethylurea, N-(2-hydroxy-4-nitrophenyl)-N',N'-dimethylurea, N-(5-chloro-2-hydroxyphenyl)-N',N'-dimethylurea, N-(4-chlorophenyl)-N',N'-dimethylurea, N-(4-chloro-2-hydroxyphenyl)-N',N'-dimethylurea, 2,4,6-tris(dimethylaminomethyl)phenol, and tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate.

[0015] In some embodiments, the conductive agent comprises at least one of silver, copper, and aluminum.

[0016] In some embodiments, the conductive agent comprises at least one of flaky silver, nanosphere silver, and microsphere silver.

[0017] In some embodiments, the conductive agent consists of flaky silver, nanosphere silver, and microsphere silver, and the weight ratio of the flaky silver, the nanosphere silver, and the microsphere silver is (25-50):(5-15):(10-30).

[0018] In some embodiments, the particle size D3 of the flaky silver is 1.0-10.0 μm, and the particle size D90 of the flaky silver is 5-20 μm.

[0019] In some embodiments, the particle size D3 of the nanosphere silver is 5-50 nm, and the particle size D90 of the nanosphere silver is 500-1000 nm.

[0020] In some embodiments, the particle size D3 of the microspherical silver is 1.0-10.0 μm, and the particle size D90 of the microspherical silver is 5-10 μm.

[0021] In some embodiments, the solvent comprises at least one of an ester solvent, an ether solvent, and an acid ester solvent.

[0022] In some embodiments, the curing temperature of the conductive paste is 150-180℃.

[0023] In some embodiments, the volume resistivity of the conductive paste at 150-180℃ is 0.5*10 -5 -7.5*10 -5 Ω.cm.

[0024] A second aspect of the embodiments of the present disclosure provides a preparation method of a conductive paste, comprising:

[0025] Mixing the organic binder, the conductive agent, the additive, and the solvent to obtain the conductive paste.

[0026] A third aspect of the embodiments of the present disclosure relates to the application of the conductive paste as described above in the embodiments of the present disclosure in the fields of electrode components, capacitors, integrated circuits, 5G technology, and new energy sources, etc.

[0027] The technical solution can bring the following beneficial effects:

[0028] The conductive paste described in the embodiments of the present disclosure can bring at least the following beneficial effects:

[0029] 1. The use of the organic binder containing nitrogen elements can effectively improve the thermal stability and electrical conductivity stability of the paste during use, and ensure the adhesion of the conductive paste to the substrate during use.

[0030] 2. The use of the flaky silver, nanoscale spherical silver, and microspherical silver with specific particle sizes in the conductive paste can help to form a continuous conductive layer during the curing process of the conductive paste, and improve the electrical conductivity.

[0031] 3. By controlling the content of nitrogen elements in the conductive paste, the storage stability of the conductive paste can be improved.

[0032] Additional aspects and advantages of the embodiments of the present disclosure will be in part apparent and in part pointed out hereinafter in the description of the embodiments of the present disclosure. DETAILED DESCRIPTION

[0033] The embodiments of the present disclosure are described in detail below, and the examples of the embodiments are exemplary and are intended to explain the embodiments of the present disclosure, and cannot be understood as a limitation of the present disclosure.

[0034] In the embodiments of the present disclosure, unless otherwise specified, the disclosure of a numerical range includes all values within the range and the disclosure of further subdivided ranges, including the endpoints and subranges given for these ranges. For example, the particle size D3 of the flaky silver is 1.0-10.0 μm, which can be understood as that the particle size D3 of the flaky silver includes but is not limited to 1.0 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc.

[0035] In the embodiments of the present disclosure, the "particle size D3" refers to the particle size value corresponding to the cumulative distribution percentage of 3% from small to large in the particle size distribution.

[0036] In the embodiments of the present disclosure, the "particle size D90" refers to the particle size value corresponding to the cumulative distribution percentage of 90% from small to large in the particle size distribution.

[0037] In the embodiments of the present disclosure, the raw materials, equipment, etc. involved, unless otherwise specified, are raw materials, equipment that can be self-made by commercial channels or known methods; the methods involved, unless otherwise specified, are conventional methods.

[0038] The inventors found that most of the existing conductive pastes use thermoplastic materials, and the adhesion with the substrate after curing is poor, high temperature is prone to fission, and the phenomenon of "deterioration" is prone to occur during storage of the paste.

[0039] Based on the above findings, the inventors found that when the organic binder and the additive in the conductive paste meet the specific dosage requirement, the use of N-containing material for the organic binder can react with the hydroxyl groups on the surface of the substrate and the powder, and the lone pair of electrons contained therein is conducive to complexing with the powder, so that the resin (i.e. the organic binder) in the conductive paste can be infiltrated and spread on the surface of the substrate and the conductive agent such as silver powder, thereby improving the wetting ability of the resin to the substrate and the conductive agent such as silver powder. Moreover, there are groups that can react with the resin, which can "tightly bind" the polymer to the interface, so that the resin and the conductive agent such as silver powder are well adhered together. The modulus of the "interface" formed therebetween is between the inorganic reinforcing material and the resin, and when external force is encountered, the internal stress can be uniformly transmitted, preventing cracks caused by external force, and improving the adhesion of the conductive paste to the substrate. At the same time, the use of N-containing material can improve the temperature resistance and conductivity of the conductive paste, but a high content of N element in the conductive paste will deteriorate the storage performance of the conductive paste.

[0040] Therefore, the inventors tried to select nitrogen-containing organic binders and additives and control the content of nitrogen element in the conductive paste in order to overcome the defects of poor adhesion of the existing conductive paste to the substrate, poor storage performance and poor conductivity stability.

[0041] In addition, the inventors have also found that different conductive agents have different abilities to improve the conductive performance. For example, the use of different shapes and particle sizes of silver in combination can help to improve the formation of a continuous conductive layer during the curing process of the conductive paste and improve the electrical conductivity.

[0042] The conductive paste, the preparation method of the conductive paste, and the application of the conductive paste according to the embodiments of the present disclosure are described in detail below.

[0043] <Conductive paste>

[0044] The conductive paste according to the embodiments of the present disclosure comprises an organic binder, a conductive agent, an additive, and a solvent. The organic binder comprises a first binder containing nitrogen elements. The weight ratio of the organic binder, the conductive agent, the additive, and the solvent is (3-10):(40-95):(0.1-3):(10-45), and the mass content of nitrogen elements in the conductive paste is below 5000 mg / kg.

[0045] As a non-limiting enumeration, the mass content of nitrogen elements in the conductive paste includes but is not limited to 10 mg / kg, 50 mg / kg, 100 mg / kg, 500 mg / kg, 1000 mg / kg, 1500 mg / kg, 2000 mg / kg, 2500 mg / kg, 3000 mg / kg, 3500 mg / kg, 4000 mg / kg, 4500 mg / kg, or 5000 mg / kg, etc.

[0046] In the embodiments of the present disclosure, the use of the organic binder containing nitrogen elements and the control of the content of the organic binder and the additive and the content of nitrogen elements in the conductive paste within the above range can improve the storage stability of the conductive paste, effectively improve the thermal stability and electrical stability of the paste during use, and improve the adhesion of the conductive paste to the substrate after curing. The specific mechanism is that:

[0047] When the organic binder and the additive in the conductive paste meet the specific dosage requirement, the organic binder using the N-containing material can react with the hydroxyl group on the surface of the substrate and the powder, and the lone pair of electrons contained therein is conducive to complexing with the powder, so that the resin (i.e., the organic binder) in the conductive paste can be infiltrated and spread on the surface of the substrate and the conductive agent, thereby improving the wetting ability of the resin to the substrate and the conductive agent. Moreover, there are groups that can react with the resin, which can "tightly bind" the polymer to the interface, so that the resin and the conductive agent are better adhered together. The modulus of the "interface" formed thereby is between the inorganic reinforcing material and the resin, and when external force is encountered, the internal stress can be uniformly transmitted, preventing cracks caused by external force and improving the adhesion of the conductive paste to the substrate. Meanwhile, the inventor has proved through experiments that, when the content of nitrogen element in the conductive paste is controlled to be less than or equal to 5000 mg / kg, the storage performance of the conductive paste can be improved, and specific experimental data of the comparative examples are shown below.

[0048] In some embodiments, the first binder includes, but is not limited to, at least one of a nitrogen-containing polyolefin, a nitrogen-containing polyester, a nitrogen-containing polyvinyl acetate, a nitrogen-containing acrylic resin, a nitrogen-containing silicone resin, a nitrogen-containing epoxy resin, a nitrogen-containing fluorine-containing resin, etc., such as at least one of a fluorine-containing amide copolymer, a nitrogen-containing olefin copolymer, a nitrogen-containing silicone epoxy resin, etc.

[0049] In some embodiments, the first binder includes, but is not limited to, at least one of a commercially available nitrogen-containing silicone-modified epoxy resin EPSI-3201, a commercially available nitrogen-containing amino-modified acrylic resin RV-3146, a commercially available amino-modified epoxy resin RV-3136, a commercially available nitrogen-containing modified epoxy resin S-510, etc.

[0050] In other embodiments, under the premise that the content of the organic binder in the conductive paste meets the requirement, in order to adjust the content of the nitrogen element in the conductive paste, the mass content of the nitrogen element in the conductive paste is less than or equal to 5000 mg / kg, and in addition to the first binder containing the nitrogen element, the organic binder can also contain a second binder not containing the nitrogen element.

[0051] It should be noted that in the embodiments of the present disclosure, when the organic binder contains both the first binder containing the nitrogen element and the second binder not containing the nitrogen element, under the premise that the content of the organic binder in the conductive paste meets the requirement and the mass content of the nitrogen element in the conductive paste is less than or equal to 5000 mg / kg, the mass ratio of the first binder to the second binder is not limited, but the higher the mass ratio of the first binder in the organic binder, the better the performance of the conductive paste.

[0052] In some embodiments, the second binder described above includes, but is not limited to, at least one of polyolefin, polyester, polyvinyl acetate, acrylic resin, silicone resin, epoxy resin, fluorine-containing resin, etc., such as commercially available conventional nitrogen-free epoxy resin GY 250, etc.

[0053] In the embodiments of the present disclosure, the organic binder has two functions: on the one hand, it can provide dispersion for the conductive agent such as silver powder, preventing the agglomeration of the conductive agent such as silver powder; on the other hand, it can provide adhesion to the substrate, preventing the slurry from falling off the substrate.

[0054] In some embodiments, the additive described above includes a first additive containing nitrogen element. Exemplarily, the first additive includes, but is not limited to, at least one of N,N-dimethylethanolamine, 2,4,6-tris(dimethylaminomethyl)phenol, benzyl dimethylamine, o-hydroxybenzyl dimethylamine, N-(2-hydroxyphenyl)-N',N'-dimethylurea, N-(2-hydroxy-4-nitrophenyl)-N',N'-dimethylurea, N-(5-chloro-2-hydroxyphenyl)-N',N'-dimethylurea, N-(4-chlorophenyl)-N',N'-dimethylurea, N-(4-chloro-2-hydroxyphenyl)-N',N'-dimethylurea, 2,4,6-tris(dimethylaminomethyl)phenol, tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate, etc.

[0055] In other embodiments, in order to adjust the content of nitrogen element in the conductive slurry, the mass content of nitrogen element in the conductive slurry is less than 5000 mg / kg, under the premise that the content of the additive in the conductive slurry meets the requirements, the additive can contain a second additive containing no nitrogen element in addition to the first additive containing nitrogen element described above.

[0056] It should be noted that in the embodiments of the present disclosure, when the additive contains both the first additive containing nitrogen element described above and the second additive containing no nitrogen element, under the premise that the content of the additive in the conductive slurry meets the requirements and the mass content of nitrogen element in the conductive slurry is less than 5000 mg / kg, the mass ratio of the first additive and the second additive is not limited, but the higher the mass ratio of the first additive in the additive, the better the performance of the conductive slurry.

[0057] In the embodiments of the present disclosure, the additive can improve the adhesion of the slurry to the substrate, reduce the initial volume resistivity of the product, and improve the temperature resistance of the product.

[0058] In some embodiments, the mass content of nitrogen in the conductive paste described above is below 1000 mg / kg. At this time, the N element content in the conductive paste has great advantages in the above range - good storage stability, thermal stability, electrical stability, moderate paste adhesion, reasonable interface impedance, and can improve the conductivity of the paste in subsequent applications.

[0059] In the embodiments of the present disclosure, the weight ratio of the four of the organic binder, the conductive agent, the additive, and the solvent is (3-10):(40-95):(0.1-3):(10-45), which can improve the conductivity and adhesion; exceeding the above range, the storage performance and temperature resistance decrease. For example, when the content of the organic binder is too high and the content of the conductive agent is too low, the volume resistivity of the paste increases and the conductivity decreases, and at the same time, the temperature resistance of the organic material deteriorates, and further decomposition may occur, reducing the high-temperature life of the product during use, thereby limiting the use range of the product; when the content of the organic binder is too low and the content of the conductive agent is too high, the adhesion of the paste decreases, and too little organic binder cannot connect too much conductive agent, which causes the product to easily settle during storage and the conductive agent to easily "separate out" on the surface of the product during use, reducing the bonding force of the paste and the substrate; when the content of the additive is too high, the additive is essentially an organic phase, is not conductive, does not participate in the reaction, and cannot be combined with the conductive agent and the organic binder, and too much additive will separate out on the surface of the product to form an insulating film layer after the paste is solidified, increasing the volume resistivity of the paste.

[0060] In the embodiments of the present disclosure, the conductive agent includes at least one of silver, copper, aluminum, and the like.

[0061] In some embodiments, the conductive agent includes at least one of flaky silver (also referred to as flaky silver), nanosphere silver, and microsphere silver.

[0062] In some embodiments, the conductive agent is composed of flaky silver, nanosphere silver, and microsphere silver, and the weight ratio of the three of flaky silver, nanosphere silver, and microsphere silver is (25-50):(5-15):(10-30), including but not limited to 25:10:10, 25:10:30, 25:10:20, 50:10:10, 50:10:30, 50:10:20, 37.5:10:10, 37.5:10:30, 37.5:10:20, 25:5:20, 25:15:20, 50:5:20, or 50:15:20, and the like.

[0063] In some embodiments, the particle size D3 of the flaky silver is 1.0-10.0 μm, including but not limited to 1.0 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, and the like.

[0064] In some embodiments, the flaky silver has a particle size D3 of 1.0-5.0 pm.

[0065] In some embodiments, the flaky silver has a particle size D3 of 1.0-5.0 pm.

[0066] In some embodiments, the flaky silver has a particle size D90 greater than 5 pm, including but not limited to 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, 10 pm, 12.5 pm, 15 pm, 17.5 pm, or 20 pm, etc.

[0067] In some embodiments, the flaky silver has a particle size D90 of 5-20 pm.

[0068] In some embodiments, the flaky silver has a particle size D90 of 5-10 pm.

[0069] In some embodiments, the nanosphere silver has a particle size D3 of 5-50 nm, including but not limited to 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or 50 nm, etc.

[0070] In some embodiments, the nanosphere silver has a particle size D3 of 5-20 nm.

[0071] In some embodiments, the nanosphere silver has a particle size D90 greater than 500 nm, including but not limited to 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1200 nm, 1500 nm, 2000 nm, or 2500 nm, etc.

[0072] In some embodiments, the nanosphere silver has a particle size D90 of 500-1000 nm.

[0073] In some embodiments, the microsphere silver has a particle size D3 of 1.0-10.0 pm, including but not limited to 1.0 pm, 2 pm, 3 pm, 4 pm, 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, or 10 pm, etc.

[0074] In some embodiments, the microsphere silver has a particle size D3 of 1.0-3.0 pm.

[0075] In some embodiments, the microsphere silver has a particle size D90 greater than 5 pm, including but not limited to 5 pm, 6 pm, 7 pm, 8 pm, 9 pm, 10 pm, 12.5 pm, 15 pm, 17.5 pm, or 20 pm, etc.

[0076] In some embodiments, the microsphere silver has a particle size D90 of 5-10 pm.

[0077] In the embodiments of the present disclosure, the use of the above-mentioned flaky silver of a specific particle size, nanosphere silver and microsphere silver is conducive to improving the formation of a continuous conductive layer during the curing process of the conductive paste and improving the electrical conductivity.

[0078] In some embodiments, the solvent includes, but is not limited to, at least one of an ester solvent, an ether solvent, an acid ester solvent, and the like. For example, at least one of diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, dimethyl adipate, butyl acetate, and the like.

[0079] The conductive paste of the embodiments of the present disclosure has good low-temperature curing performance, and the curing temperature is 150 -180℃, including but not limited to 150℃, 160℃, 170℃ or 180℃, etc.

[0080] In some embodiments, the volume resistivity of the conductive paste is 0.5*10 -5 -7.5*10 -5 Ω·cm, including but not limited to 0.5*10 -5 Ω·cm, 3.0*10 -5 Ω·cm, 5.0*10 -5 Ω·cm, 5.5*10 -5 Ω·cm, 6.5*10 -5 Ω·cm, or 7.5*10 -5 Ω·cm, etc.

[0081] <Method for preparing a conductive paste>

[0082] The method for preparing the conductive paste of the embodiments of the present disclosure includes:

[0083] Mixing the organic binder, the conductive agent, the additive and the solvent to obtain the conductive paste.

[0084] In some embodiments, the method for preparing the conductive paste includes:

[0085] The organic binder, the conductive agent, the additive and the solvent are added to a double-planetary mixer, and stirred at a temperature of 25℃ for 3-6h to form the conductive paste.

[0086] <Applications of the conductive paste>

[0087] The conductive paste of the embodiments of the present disclosure can be widely applied to electrode components, capacitors, integrated circuits, 5G technology and new energy fields, etc.

[0088] Some features of the present technology are further illustrated in the following non-limiting examples.

[0089] I. Examples and Comparative Examples

[0090] The testing method of nitrogen element in each of the following examples and comparative examples is ion chromatography.

[0091] The raw material sources and nitrogen element contents involved in each of the following examples and comparative examples are shown in Table 1.

[0092] Table 1 Raw material sources and nitrogen element contents

[0093] Example 1

[0094] (conductive paste)

[0095] The conductive paste of the present example is composed of the following components in parts by weight: organic binder 8 parts, flaky silver 50 parts, nanosphere silver 5 parts, microsphere silver 10 parts, additive 0.5 part, solvent 32 parts. Among them, the organic binder is a mixture of commercially available nitrogen-containing organosilicon modified epoxy resin EPSI-3201 and conventional epoxy resin GY 250 without nitrogen in a mass ratio of 1:6; the flaky silver has a particle size D3 of 1.0 μm and a particle size D90 of 10.0 μm; the nanosphere silver has a particle size D3 of 20 nm and a particle size D90 of 900 nm; the microsphere silver has a particle size D3 of 2.0 μm and a particle size D90 of 6.0 μm; the additive is N-(2-hydroxyphenyl)-N',N'-dimethylurea; and the solvent is diethylene glycol ethyl ether acetate.

[0096] (preparation method of conductive paste)

[0097] The formula amount of organic binder, flaky silver, nanosphere silver, microsphere silver, solvent and additive are sequentially added into a double planetary mixer, stirred for 4 h at a temperature control of 25°C, and uniformly stirred to form a silver paste.

[0098] It is tested that the mass content of nitrogen element in the conductive paste of the present example is 830 mg / kg.

[0099] Example 2

[0100] (conductive paste)

[0101] The conductive paste of the present example is composed of the following components in parts by weight: organic binder 3 parts, flaky silver 30 parts, nanosphere silver 5 parts, microsphere silver 30 parts, additive 0.25 part, solvent 32 parts. Among them, the organic binder is commercially available nitrogen-containing amino-modified acrylic resin RV-3146; the flaky silver has a particle size D3 of 3.0 μm and a particle size D90 of 5.0 μm; the nanosphere silver has a particle size D3 of 20 nm and a particle size D90 of 900 nm; the microsphere silver has a particle size D3 of 3.0 μm and a particle size D90 of 10.0 μm; the additive is N-(2-hydroxyphenyl)-N',N'-dimethylurea; and the solvent is diethylene glycol butyl ether acetate.

[0102] Preparation method of conductive paste

[0103] The formula amount of organic binder, flaky silver, nanosphere silver, microsphere silver, solvent and additive were sequentially added into a double planetary mixer, and stirred for 4h at 25℃, to form a silver paste.

[0104] It was tested that the mass content of nitrogen element in the conductive paste of the embodiment was 592mg / kg.

[0105] Example 3

[0106] Conductive paste

[0107] The conductive paste of the embodiment was composed of the following components by weight: organic binder 5 parts, flaky silver 50 parts, nanosphere silver 5 parts, microsphere silver 10 parts, additive 0.6 parts, and solvent 30 parts. The organic binder was a mixture of commercially available amino-modified epoxy resin RV-3136 and conventional epoxy resin GY 250 at a mass ratio of 1:0.27; the flaky silver had a particle size D3 of 3.0μm and a particle size D90 of 5.0μm; the nanosphere silver had a particle size D3 of 5nm and a particle size D90 of 500nm; the microsphere silver had a particle size D3 of 3.0μm and a particle size D90 of 10.0μm; the additive was o-hydroxybenzyl dimethylamine; and the solvent was ethylene glycol monobutyl ether.

[0108] Preparation method of conductive paste

[0109] The formula amount of organic binder, flaky silver, nanosphere silver, microsphere silver, solvent and additive were sequentially added into a double planetary mixer, and stirred for 4h at 25℃, to form a silver paste.

[0110] It was tested that the mass content of nitrogen element in the conductive paste of the embodiment was 730mg / kg.

[0111] Example 4

[0112] The conductive paste of the embodiment was composed of the following components by weight: organic binder 3 parts, flaky silver 50 parts, nanosphere silver 5 parts, microsphere silver 10 parts, additive 0.5 parts, and solvent 30 parts. The organic binder was a mixture of commercially available nitrogen-containing modified epoxy resin S-510 and conventional epoxy resin GY 250 without nitrogen at a mass ratio of 1:1.17; the flaky silver had a particle size D3 of 3.0μm and a particle size D90 of 5.0μm; the nanosphere silver had a particle size D3 of 5nm and a particle size D90 of 500nm; the microsphere silver had a particle size D3 of 3.0μm and a particle size D90 of 10.0μm; the additive was 2,4,6-tris(dimethylaminomethyl)phenol; and the solvent was ethylene glycol monobutyl ether.

[0113] Preparation method of conductive paste

[0114] The formula amount of organic binder, flaky silver, nanosphere silver, microsphere silver, solvent and additive were added into a double planetary mixer in turn, and stirred for 4h at 25℃, to form a silver paste.

[0115] It was tested that the mass content of nitrogen element in the conductive paste of the embodiment was 1000mg / kg.

[0116] Example 5

[0117] The embodiment was basically the same as Example 1, except that:

[0118] In the conductive paste, the organic binder was a commercially available nitrogen-containing organosilicon modified epoxy resin EPSI-3201.

[0119] It was tested that the mass content of nitrogen element in the conductive paste of the embodiment was 4580mg / kg.

[0120] Example 6

[0121] The embodiment was basically the same as Example 1, except that:

[0122] In the conductive paste, 10 parts of the organic binder was a mixture of a commercially available nitrogen-containing organosilicon modified epoxy resin EPSI-3201 and a conventional epoxy resin GY 250 without nitrogen in a mass ratio of 1:0.13.

[0123] It was tested that the mass content of nitrogen element in the conductive paste of the embodiment was 5000mg / kg.

[0124] Example 7

[0125] The embodiment was basically the same as Example 1, except that:

[0126] In the conductive paste, “50 parts of flaky silver, 5 parts of nanosphere silver, 10 parts of microsphere silver” were replaced by: 65 parts of flaky silver.

[0127] Example 8

[0128] The embodiment was basically the same as Example 1, except that:

[0129] In the conductive paste, “50 parts of flaky silver, 5 parts of nanosphere silver, 10 parts of microsphere silver” were replaced by: 21 parts of nanosphere silver, 44 parts of microsphere silver.

[0130] Example 9

[0131] The embodiment was basically the same as Example 1, except that:

[0132] In the conductive paste, the "50 parts of flaky silver, 5 parts of nanosphere silver, and 10 parts of microsphere silver" are replaced by 65 parts of copper powder having a particle size of 5 microns.

[0133] Example 10

[0134] This example is basically the same as Example 1, except that:

[0135] In the conductive paste, the 9 parts of organic binder is a mixture of commercially available nitrogen-containing silicone-modified epoxy resin EPSI-3201 and commercially available nitrogen-containing modified epoxy resin S-510 at a mass ratio of 1:0.69.

[0136] It is tested that the mass content of nitrogen element in the conductive paste of this example is 3800 mg / kg.

[0137] Comparative Example 1

[0138] The conductive paste of this comparative example is composed of the following components in parts by weight: 5 parts of organic binder, 50 parts of flaky silver, 5 parts of nanosphere silver, 10 parts of microsphere silver, 0.3 parts of additive, and 30 parts of solvent. The organic binder is commercially available conventional epoxy resin GY 250 without nitrogen; the flaky silver has a particle size D3 of 3.0 μm and a particle size D90 of 5.0 μm; the nanosphere silver has a particle size D3 of 5 nm and a particle size D90 of 500 nm; the microsphere silver has a particle size D3 of 3.0 μm and a particle size D90 of 10.0 μm; the additive is o-hydroxybenzyl dimethylamine, and the mass content of nitrogen element is 276 mg / kg; and the solvent is ethylene glycol monobutyl ether.

[0139] (Preparation method of conductive paste)

[0140] The formula amount of organic binder, flaky silver, nanosphere silver, microsphere silver, solvent, and additive are sequentially added into a double planetary mixer, and stirred for 4 h at a temperature control of 25°C to form a silver paste.

[0141] It is tested that the mass content of nitrogen element in the conductive paste of this comparative example is 276 mg / kg.

[0142] Comparative Example 2

[0143] The conductive paste of the present embodiment is composed of the following components by weight: organic binder 10.8 parts, flaky silver 45 parts, nanosphere silver 5 parts, microsphere silver 10 parts, additive 0.5 parts, solvent 32 parts. Among them, the organic binder is commercially available nitrogen-containing organic silicon modified epoxy resin EPSI-3201; the flaky silver has a particle size D3 of 1.0 μm and a particle size D90 of 10.0 μm; the nanosphere silver has a particle size D3 of 20 nm and a particle size D90 of 900 nm; the microsphere silver has a particle size D3 of 2.0 μm and a particle size D90 of 6.0 μm; the additive is N-(2-hydroxyphenyl)-N',N'-dimethylurea; and the solvent is diethylene glycol ethyl ether acetate.

[0144] It is tested that the mass content of nitrogen element in the conductive paste of the present comparative example is 6000 mg / kg.

[0145] II. Performance test

[0146] 1. Performance test method

[0147] (1) Adhesion test: the crosshatch method is adopted. In some embodiments, five samples are prepared by coating each of the conductive pastes of the examples or comparative examples on a glass slide in a 30 mm x 30 mm rectangular film, drying at 180°C for 20 min, and using a crosshatch knife to draw 10 x 10 (100) 1 mm x 1 mm small grids on the surface of the test sample, with each line reaching the bottom layer of the coating film; the debris in the test area is brushed clean with a brush, the tested small network is firmly adhered with 3M 600# adhesive tape (i.e. 3M TM Scotch TM 600 transparent film adhesive tape), and the adhesive tape is rubbed with a rubber to increase the contact area and force between the adhesive tape and the tested area, one end of the adhesive tape is held with the hand, and the adhesive tape is quickly pulled off in the vertical direction (90 degrees).

[0148] (2) Resistivity test: the four-probe test method is adopted. In some embodiments, after the conductive paste of each example or comparative example is coated on a glass slide, the glass slide is placed in a 150°C oven for baking for 60±2 min to form a thin film with a thickness of 20±2 μm, and the resistivity mode in the RTS-9 double electric four-probe test system is selected for resistivity determination.

[0149] (3) Viscosity test: the rotary viscometer method is adopted. In some embodiments, the appropriate rotor and rotation speed are selected according to the viscosity and viscosity range of the paste to be tested, the rotor groove scale part is aligned with the liquid surface, the test key is pressed, and the data is read and recorded.

[0150] 2. Performance evaluation method

[0151] Storage stability: the viscosity of the conductive paste of the same example or the comparative example was tested by the above viscosity test method in fresh state and after being placed for 1 month, 2 months, 3 months, 4 months, 5 months and 6 months. If the difference between the viscosity of the conductive paste after being placed for different time and the viscosity of the conductive paste in fresh state is within 20%, it is considered that the storage stability of the conductive paste is good; otherwise, it is considered that the storage stability is poor.

[0152] The evaluation method of adhesion is that the adhesion of the paste is considered to meet the requirements when the adhesion by the crosshatch method is greater than or equal to 5B.

[0153] Electrical performance: the initial volume resistivity of the conductive paste of the same example or the comparative example was tested by the above resistivity test method in fresh state and after being placed for 6 months. If the difference between the volume resistivity after being placed for 6 months and the initial volume resistivity is within 20%, it is considered that the electrical performance of the conductive paste is good; otherwise, it is considered that the electrical performance is poor.

[0154] 3. Performance test results

[0155] The storage stability test results of the paste are shown in Table 2, and the curing performance test results are shown in Table 3.

[0156] Table 2 Storage stability

[0157] As can be seen from Table 2, the conductive paste of each example of the present disclosure has a lower curing temperature than the comparative examples. At the same time, according to the data in Table 2, it is found that the difference between the viscosity of the conductive paste of each example of the present disclosure after being placed for different time and the viscosity in fresh state is within 20%, which proves that the storage stability of the conductive paste of each example of the present disclosure is better. The difference between the viscosity of the conductive paste of each comparative example after being placed for different time and the viscosity in fresh state is greater than 20%, which proves that the storage stability of the conductive paste of the comparative examples is poor.

[0158] Table 3 Curing performance test results

[0159] As can be seen from Table 3, the adhesion between the conductive paste of each example of the present disclosure and the glass slide is better than that of the comparative examples; at the same time, according to the data in Table 3, it is found that the difference between the volume resistivity of the conductive paste of each example of the present disclosure after being placed for 6 months and the initial volume resistivity is within 20%, while the difference between the volume resistivity of the conductive paste of each comparative example after being placed for 6 months and the initial volume resistivity is greater than 20%, which shows that the electrical performance and high temperature resistance of the conductive paste of each example of the present disclosure are obviously superior to those of the comparative examples.

[0160] In this disclosure, the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that the particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the disclosure. Illustrative expressions of such terms do not necessarily refer to the same embodiment or example in this specification. Moreover, such terms do not necessarily refer to the same embodiment or example. The particular features, structures, materials, or characteristics can be combined in any suitable manner in one or more embodiments or examples. In addition, different embodiments or examples described in this specification and features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction, if necessary.

[0161] In addition, the terms "first", "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the disclosure, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise specifically limited.

[0162] Although the embodiments of the disclosure have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the disclosure, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the disclosure.

[0163] All embodiments of the disclosure can be executed independently or in combination with other embodiments, and are considered to be within the scope of protection required by the disclosure.

Claims

1. An electrically conductive paste, characterized by, The organic binder includes a first binder containing a nitrogen element, and the first binder includes at least one of a nitrogen-containing polyolefin, a nitrogen-containing polyester, a nitrogen-containing polyvinyl acetate, a nitrogen-containing acrylic resin, a nitrogen-containing silicone resin, a nitrogen-containing epoxy resin, and a nitrogen-containing fluorine-containing resin. The weight ratio of the four of the organic binder, the conductive agent, the additive, and the solvent is (3-10):(40-95):(0.1-3):(10-45), and the mass content of the nitrogen element in the conductive paste is below 5000 mg / kg.

2. The electroconductive paste according to claim 1, characterized by The mass content of the nitrogen element in the conductive paste is below 1000 mg / kg.

3. The electroconductive paste according to claim 1 or 2, characterized by, The first binder includes at least one of a nitrogen-containing polyolefin, a nitrogen-containing polyester, a nitrogen-containing polyvinyl acetate, a nitrogen-containing acrylic resin, a nitrogen-containing silicone resin, a nitrogen-containing epoxy resin, and a nitrogen-containing fluorine-containing resin; and / or, The additive includes at least one of N,N-dimethylethanolamine, 2,4,6-tris(dimethylaminomethyl)phenol, benzyl dimethylamine, o-hydroxybenzyl dimethylamine, N-(2-hydroxyphenyl)-N',N'-dimethylurea, N-(2-hydroxy-4-nitrophenyl)-N',N'-dimethylurea, N-(5-chloro-2-hydroxyphenyl)-N',N'-dimethylurea, N-(4-chlorophenyl)-N',N'-dimethylurea, N-(4-chloro-2-hydroxyphenyl)-N',N'-dimethylurea, 2,4,6-tris(dimethylaminomethyl)phenol, and tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate.

4. The electroconductive paste according to any one of claims 1 to 3, characterized in that, The organic binder further includes a second binder not containing a nitrogen element, and the second binder includes a copolymer or a modified product of at least one structural unit of a polyolefin, a polyester, a polyvinyl acetate, an acrylic resin, a silicone resin, an epoxy resin, and a fluorine-containing resin.

5. The electroconductive paste according to any one of claims 1 to 4, characterized in that, The conductive agent includes at least one of silver, copper, and aluminum. The solvent includes at least one of an ester-based solvent, an ether-based solvent, and an acid ester-based solvent.

6. The conductive paste according to any one of claims 1 to 5, wherein, The conductive agent includes at least one of flaky silver, nanosphere silver, and microsphere silver, and when the conductive agent contains flaky silver, nanosphere silver, and microsphere silver at the same time, the weight ratio of the three of the flaky silver, the nanosphere silver, and the microsphere silver is (25-50):(5-15):(10-30).

7. The electroconductive paste according to claim 6, wherein The particle size D3 of the flaky silver is 1.0-10.0 μm, and the particle size D90 of the flaky silver is 5-20 μm. The particle size D3 of the nanosphere silver is 5-50 nm, and the particle size D90 of the nanosphere silver is 500-1000 nm. The particle size D3 of the microsphere silver is 1.0-10.0 μm, and the particle size D90 of the microsphere silver is 5-10 μm.

8. The conductive paste according to any one of claims 1 to 7, wherein, The curing temperature of the conductive paste is 150-180℃. and / or the electrically conductive paste 150-180 °C has a volume resistivity of 0.5*10 -5 -7.5*10 -5 Ω.cm.

9. A method of preparing the electroconductive paste as claimed in any one of claims 1 to 8, characterized by, The method includes: The organic binder, the conductive agent, the additive, and the solvent are mixed uniformly to obtain the conductive paste.

10. The conductive paste according to any one of claims 1 to 8 for use in the fields of electrode components, capacitors, integrated circuits, 5G technology, and new energy.

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