A composite copper paste for low-temperature sintering, its preparation method and application

Abstract

This invention belongs to the field of electronic packaging and discloses a low-temperature sintering composite copper paste, its preparation method, and its applications. It addresses the technical problems of existing composite copper pastes, such as high sintering temperature, complex preparation process, poor oxidation resistance, non-dense sintering, and poor conductivity. This invention uses a hydrothermal method to synthesize surface-modified, oxidation-resistant copper nanowires in situ, and then combines them with copper nanoparticles, copper nanosheets, and other components to prepare a low-temperature sintering composite copper paste. This composite copper paste can be directly sintered at low temperatures in air without relying on inert gas or reducing atmosphere protection, significantly reducing process costs. Simultaneously, its sintered body exhibits excellent conductivity, effectively broadening the application range of this conductive copper paste.

Description

Technical Field

[0001] This invention belongs to the field of electronic packaging, and in particular relates to a low-temperature sintering composite copper paste. Background Technology

[0002] The rapid and continuous development of microelectronic packaging, photovoltaic devices, and precision circuit board technologies is driving electronic devices towards miniaturization, thinning, low power consumption, and high integration. This trend places more stringent demands on the comprehensive performance of core conductive materials—conductive pastes—especially in terms of sintering temperature, conductivity, environmental adaptability, and manufacturing costs. Traditionally, silver paste is widely used as a conductive material in electronic packaging due to its mature sintering process and excellent conductivity. However, the high cost of silver and its inherent electromigration defects significantly limit its economic viability and long-term reliability in large-scale industrial applications. In contrast, copper-based conductive pastes, with their superior conductivity, significant cost advantages, and lack of electromigration risk, are considered a key material for replacing silver paste and achieving cost reduction and efficiency improvement in electronic packaging, and have become a core research direction in the field of conductive pastes.

[0003] Traditional sintered copper pastes typically require densification sintering at temperatures between 600°C and 900°C to achieve the desired high conductivity. However, this temperature range is far higher than the 300°C upper limit required for chip packaging processes. To overcome this limitation, existing technologies have explored introducing copper nanoparticles or copper nanowires into copper-based pastes to effectively improve the density of the sintered layer, ultimately optimizing its density and conductivity. However, copper nanowires tend to form a loose, porous structure, resulting in insufficient density of the sintered body; while copper nanoparticles can achieve dense packing, they require high-temperature sintering and have high grain boundary resistance. Patent application CN119418979A discloses a nano-copper metal material for low-temperature sintered conductive pastes containing copper nanoparticles and copper nanowires. Although the binary composite system of copper nanoparticles and copper nanowires can partially synergize performance, the continuity of the conductive network and the pore filling efficiency are still limited by the uniformity of the morphology. Patent CN104505137A discloses a conductive copper paste that, after being screen-printed, needs to be sintered in a nitrogen / hydrogen mixed reducing atmosphere. In addition to relying on reducing gases, it also requires high-temperature heat treatment, which leads to complex processes and increased costs.

[0004] Therefore, developing a composite copper paste with excellent antioxidant properties, excellent electrical conductivity, low-temperature air sintering capability, and adaptability to multiple scenarios, as well as its preparation technology, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] To address the aforementioned problems of high sintering temperature, complex preparation process, poor oxidation resistance, non-dense sintering, and poor conductivity, this invention provides a composite copper paste for low-temperature sintering, its preparation method, and its application.

[0006] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0007] A composite copper paste for low-temperature sintering comprises antioxidant copper nanowires, copper nanoparticles, copper nanosheets, and solvent I; wherein the antioxidant copper nanowires account for 3%-33% of the total mass of the antioxidant copper nanowires, copper nanoparticles, and copper nanosheets, the copper nanoparticles account for 66.5%-91.5% of the total mass of the antioxidant copper nanowires, copper nanoparticles, and copper nanosheets, and the remainder is copper nanosheets.

[0008] More preferably, the antioxidant copper nanowires account for 3%-16% of the total mass of the antioxidant copper nanowires, copper nanoparticles and copper nanosheets, the copper nanoparticles account for 82.5%-91.5% of the total mass of the antioxidant copper nanowires, copper nanoparticles and copper nanosheets, and the remainder is copper nanosheets.

[0009] This invention utilizes antioxidant copper nanowires combined with copper nanoparticles and copper nanosheets to prepare low-temperature sintering copper paste. The copper nanowires form an interpenetrating initial framework structure within the composite copper paste, providing preferential contact sites for low-temperature sintering. The aspect ratio advantage of copper nanowires allows for multi-point contact between wires and particles, wires and wires, and wires and surfaces before sintering. Compared to particle-particle contact, this contact method has a larger contact area, forming a continuous sintering neck. This expands localized wire-to-wire, wire-to-particle, and particle-to-particle connections into a globally interconnected three-dimensional network structure, thereby significantly improving the electrical conductivity of the sintered body.

[0010] The copper nanosheets described above have a diameter range of 1-5 μm and a thickness range of 10-30 nm; solvent I is at least one of ethylene glycol, polyethylene glycol and dimethylformamide.

[0011] The particle size range of the aforementioned copper nanoparticles is 80-100 nm. The average diameter of the antioxidant copper nanowires is 50-80 nm, and the length is 10-50 μm.

[0012] Furthermore, the preparation method of the above-mentioned antioxidant copper nanowires is as follows: A copper source, a reducing agent, and a capping agent are dissolved in solvent II, and a hydrothermal reaction is carried out to obtain antioxidant copper nanowires. The copper source is any one of copper chloride dihydrate, copper nitrate trihydrate, and copper sulfate pentahydrate; the capping agent is at least one of oleic acid, oleylamine, hexadecylamine, and octadecylamine; the reducing agent is glucose or ascorbic acid; and solvent II is at least one of deionized water, methanol, ethanol, and propanol.

[0013] The mass ratio of copper source, reducing agent, and capping agent is (0.5-9.5):(0.52-12.8):(6-72). For example, the mass ratios are (0.5-9.5):(0.52-6):(6-72), (0.5-9.5):(6-12.8):(6-72), (0.5-1):(0.52-12.8):(6-72), (1-9.5):(0.52-12.8):(6-72), and (1:(1-1.2):(7-12), as long as they fall within the above ranges. The hydrothermal reaction temperature is 100-180℃, and the time is 3-10 h.

[0014] The method for preparing the composite copper paste for low-temperature sintering of the present invention comprises the following steps: mixing antioxidant copper nanowires, copper nanoparticles, copper nanosheets and solvent I, and then degassing.

[0015] The above-mentioned low-temperature sintering composite copper paste is applied in electronic packaging materials. The application steps are as follows: the low-temperature sintering composite copper paste is applied to a substrate, heated to 180-350℃ at a heating rate of 5-30℃ / min, at a pressure of 1-5 MPa, and held for 5-30 min to obtain the final product. More preferably, the temperature is increased to 220-350℃ at a heating rate of 5-30℃ / min, at a pressure of 1-5 MPa, and held for 10-30 min to obtain the final product.

[0016] The beneficial effects of this invention are:

[0017] (1) The antioxidant copper nanowires prepared in this invention are combined with copper nanoparticles, copper nanosheets and other components to prepare low-temperature sintering copper paste. The copper nanowires form an interpenetrating initial skeleton structure in the composite copper paste, providing preferential contact sites for low-temperature sintering. The aspect ratio advantage of copper nanowires allows them to form multi-point contacts between lines and particles, lines and lines, and lines and surfaces before sintering. Compared with particle-particle contacts, this contact method has a larger contact area, forming a continuous sintering neck, which expands the local line-to-line, line-to-particle, and line-to-surface connections into a three-dimensional network structure with global interconnection, thereby significantly improving the conductivity of the sintered body.

[0018] (2) The present invention is simple to synthesize, low in cost, and the prepared copper nanowires have strong antioxidant properties and stable dimensions, which is conducive to large-scale preparation. The low-temperature sintering composite copper paste prepared is simple to process and low in equipment cost, making it a suitable preparation method for promotion.

[0019] (3) The low-temperature sintering composite copper paste prepared by the present invention has excellent conductivity and is a new type of high-performance electronic sealing material. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a scanning electron microscope image of the copper nanowires prepared in Example 1 of the present invention.

[0022] Figure 2 The X-ray diffraction (XRD) spectra of the copper nanowires prepared in Example 1 of this invention before and after oxidation.

[0023] Figure 3 This is a schematic diagram of the low-temperature sintering composite copper paste sintering in Embodiment 1 of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1

[0026] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0027] (1) First, weigh 0.36 g of copper chloride dihydrate, 0.46 g of glucose, 80 μL of oleic acid, and 5 mL of oleylamine, dissolve them in 8 mL of ethanol and 20 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 120℃ for 6 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 60 nm, and the average length is 35 μm (e.g., ...). Figure 1 (As shown). The prepared antioxidant copper nanowires were placed in air for 5 months, and their XRD patterns were tested. No copper oxidation peaks were detected (as shown). Figure 2 (As shown in the figure). The results show that the prepared copper nanowires have excellent antioxidant properties.

[0028] (2) Weigh 0.5 g of the antioxidant copper nanowires prepared in step (1), 5.4 g of copper nanoparticles (average particle size of 80 nm), and 0.1 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0029] The low-temperature sintered composite copper paste obtained in this embodiment was placed in a heating furnace and heated to 220°C at a heating rate of 5°C / min under ambient atmosphere, with a pressure of 2 MPa, and held for 30 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 3.89 μΩ·cm.

[0030] Figure 3 This is a schematic diagram of the low-temperature sintering composite copper paste sintering according to Embodiment 1 of the present invention. Under low-temperature sintering conditions of 220℃ and pressure of 2 MPa, the copper nanowires inside the composite copper paste interlock to form an initial conductive framework that runs through the entire structure. Copper nanoparticles fill the gaps between the nanowires, significantly increasing the interfacial contact sites required for low-temperature sintering. The copper nanosheets introduced into the system can further widen the interfacial contact area, promote the formation of continuous sintering necks, and transform the isolated line-to-line, line-to-particle, and particle-to-particle connections that exist locally into a fully interconnected three-dimensional network, ultimately significantly improving the conductivity of the sintered copper matrix.

[0031] Example 2

[0032] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0033] (1) First, weigh 0.36 g of copper chloride dihydrate, 0.46 g of glucose, 80 μL of oleic acid, and 5 mL of oleylamine, dissolve them in 8 mL of ethanol and 20 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 120℃ for 6 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 60 nm, and the average length is 35 μm.

[0034] (2) Weigh 0.5 g of the antioxidant copper nanowires prepared in step (1), 5.49 g of copper nanoparticles (average particle size of 80 nm), and 0.01 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0035] The low-temperature sintered composite copper paste obtained in this embodiment was placed in a heating furnace and heated to 220°C at a heating rate of 5°C / min under ambient atmosphere, with a pressure of 2 MPa, and held for 30 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 4.08 μΩ·cm.

[0036] Example 3

[0037] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0038] (1) First, weigh 0.45 g of copper chloride dihydrate, 0.5 g of glucose, 100 μL of oleic acid, and 4 mL of oleylamine, dissolve them in 8 mL of ethanol and 20 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 100℃ for 10 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 80 nm, and the average length is 42 μm.

[0039] (2) Weigh 1 g of the antioxidant copper nanowires prepared in step (1), 4.95 g of copper nanoparticles (average particle size of 100 nm), and 0.05 g of copper nanosheets (average sheet diameter of 1 μm and sheet thickness of 10 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0040] The low-temperature sintered composite copper paste obtained in this embodiment was placed in a heating furnace and heated to 240°C at a heating rate of 5°C / min under ambient atmosphere, with a pressure of 2 MPa, and held for 30 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 4.35 μΩ·cm.

[0041] Example 4

[0042] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0043] (1) First, weigh 0.36 g of copper chloride dihydrate, 0.46 g of glucose, 80 μL of oleic acid, and 5 mL of oleylamine, dissolve them in 8 mL of ethanol and 20 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 120℃ for 6 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 60 nm, and the average length is 35 μm.

[0044] (2) Weigh 0.2 g of the antioxidant copper nanowires prepared in step (1), 5.3 g of copper nanoparticles (average particle size of 80 nm), and 0.5 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0045] The low-temperature sintered composite copper paste obtained in this embodiment was placed in a heating furnace and heated to 240°C at a heating rate of 5°C / min under ambient atmosphere, with a pressure of 2 MPa, and held for 30 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 5.4 μΩ·cm.

[0046] Example 5

[0047] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0048] (1) First, weigh 0.36 g of copper chloride dihydrate, 0.46 g of glucose, 80 μL of oleic acid, and 5 mL of oleylamine, dissolve them in 8 mL of ethanol and 20 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 120℃ for 6 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 60 nm, and the average length is 35 μm.

[0049] (2) Weigh 0.2 g of the antioxidant copper nanowires prepared in step (1), 5.3 g of copper nanoparticles (average particle size of 80 nm), and 0.5 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0050] The low-temperature sintered composite copper paste obtained in this embodiment was placed in a heating furnace and heated to 300°C at a heating rate of 5°C / min under ambient atmosphere, with a pressure of 1 MPa, and held for 20 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 4.51 μΩ·cm.

[0051] Example 6

[0052] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0053] (1) First, weigh 0.36 g of copper chloride dihydrate, 0.46 g of glucose, 80 μL of oleic acid, and 5 mL of oleylamine, dissolve them in 8 mL of ethanol and 20 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 120℃ for 6 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 60 nm, and the average length is 35 μm.

[0054] (2) Weigh 0.5 g of the antioxidant copper nanowires prepared in step (1), 5.4 g of copper nanoparticles (average particle size of 80 nm), and 0.1 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0055] The low-temperature sintered composite copper paste obtained in this embodiment was placed in a heating furnace and heated to 250°C at a heating rate of 30°C / min under ambient atmosphere, with a pressure of 5 MPa, and held for 10 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 5.12 μΩ·cm.

[0056] Example 7

[0057] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0058] (1) First, weigh 0.36 g of copper chloride dihydrate, 0.46 g of glucose, 80 μL of oleic acid, and 5 mL of oleylamine, dissolve them in 8 mL of ethanol and 20 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 120℃ for 6 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 60 nm, and the average length is 35 μm.

[0059] (2) Weigh 0.5 g of the antioxidant copper nanowires prepared in step (1), 5.4 g of copper nanoparticles (average particle size of 80 nm), and 0.1 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0060] The low-temperature sintered composite copper paste obtained in this embodiment was placed in a heating furnace and heated to 350°C at a heating rate of 10°C / min under ambient atmosphere, with a pressure of 2 MPa, and held for 30 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 4.16 μΩ·cm.

[0061] Example 8

[0062] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0063] (1) First, weigh 3.6 g of copper chloride dihydrate, 4.85 g of glucose, 400 μL of oleic acid, and 26.87 mL of oleylamine and dissolve them in 80 mL of ethanol and 100 mL of deionized water. Stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 100 °C for 10 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 50 nm and the average length is 10 μm.

[0064] (2) Weigh 0.2 g of the antioxidant copper nanowires prepared in step (1), 5.3 g of copper nanoparticles (average particle size of 80 nm), and 0.5 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0065] Example 9

[0066] The preparation method of the composite copper paste for low-temperature sintering in this embodiment includes the following steps:

[0067] (1) First, weigh 0.36 g of copper chloride dihydrate, 0.46 g of glucose, 80 μL of oleic acid, and 5 mL of oleylamine, dissolve them in 8 mL of ethanol and 10 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 180℃ for 3 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 80 nm, and the average length is 20 μm.

[0068] (2) Weigh 0.2 g of the antioxidant copper nanowires prepared in step (1), 5.3 g of copper nanoparticles (average particle size of 80 nm), and 0.5 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0069] Comparative Example 1

[0070] The preparation method of the composite copper paste for low-temperature sintering in this comparative example includes the following steps:

[0071] (1) First, weigh 0.36 g of copper chloride dihydrate, 0.46 g of glucose, 80 μL of oleic acid, and 5 mL of oleylamine, dissolve them in 8 mL of ethanol and 20 mL of deionized water, and stir magnetically for 30 min to form a homogeneous emulsion. Pour the emulsion into a hydrothermal reactor and heat at 120℃ for 6 hours. After cooling, antioxidant copper nanowires are obtained. The average diameter of the prepared antioxidant copper nanowires is 60 nm, and the average length is 35 μm.

[0072] (2) Weigh 0.25 g of the antioxidant copper nanowires prepared in step (1) and 5.75 g of copper nanoparticles (average particle size of 100 nm) and disperse them in 2.8 mL of ethylene glycol and 0.2 mL of polyethylene glycol. Mix and degas to form a composite copper paste for low-temperature sintering.

[0073] The low-temperature sintered composite copper paste obtained in this comparative example was placed in a heating furnace and heated to 220℃ at a heating rate of 10℃ / min under ambient atmosphere, with a pressure of 2 MPa, and held for 30 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 10.56 μΩ·cm.

[0074] Comparative Example 2

[0075] The preparation method of copper paste for low-temperature sintering in this comparative example includes the following steps:

[0076] Weigh 6 g of copper nanoparticles (average particle size of 80 nm) and disperse them in 3 mL of ethylene glycol. Mix and degas to form a copper paste for low-temperature sintering.

[0077] The low-temperature sintered copper slurry obtained in this comparative example was placed in a heating furnace and heated to 220°C at a heating rate of 5°C / min under ambient atmosphere, with a pressure of 2 MPa, and held for 30 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 9.8 μΩ·cm.

[0078] Comparative Example 3

[0079] The preparation method of the composite copper paste for low-temperature sintering in this comparative example includes the following steps:

[0080] Weigh 5.5 g of copper nanoparticles (average particle size of 80 nm) and 0.5 g of copper nanosheets (average sheet diameter of 5 μm and sheet thickness of 30 nm), disperse them in 5.6 mL of ethylene glycol and 0.4 mL of polyethylene glycol, mix and degas to form a composite copper paste for low-temperature sintering.

[0081] The low-temperature sintered copper slurry obtained in this comparative example was placed in a heating furnace and heated to 220°C at a heating rate of 5°C / min under ambient atmosphere, with a pressure of 2 MPa, and held for 30 min. The sintered copper block was then subjected to performance testing. The results showed that the resistivity was 8.67 μΩ·cm.

[0082] The properties of the materials prepared in the above application examples are shown in Table 1.

[0083] Table 1

[0084]

[0085] As shown in Table 1, compared with single copper nanoparticle, copper nanowire, and copper nanosheet systems, or copper pastes composed of only two components, copper pastes prepared by synergistically combining three copper-based nanofillers in a specific ratio exhibit superior electrical conductivity. Although sintering process parameters can regulate the electrical conductivity of the sintered body to some extent, a comprehensive performance comparison shows that the three-component composite copper paste has significant performance advantages in low-temperature sintering systems.

[0086] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A composite copper paste for low-temperature sintering, characterized in that, It includes antioxidant copper nanowires, copper nanoparticles, copper nanosheets and solvent I; wherein, antioxidant copper nanowires account for 3%-33% of the total mass of antioxidant copper nanowires, copper nanoparticles and copper nanosheets, and copper nanoparticles account for 66.5%-91.5% of the total mass of antioxidant copper nanowires, copper nanoparticles and copper nanosheets.

2. The composite copper paste for low-temperature sintering according to claim 1, characterized in that, The copper nanosheets have a diameter range of 1-5 μm and a thickness range of 10-30 nm; solvent I is at least one of ethylene glycol, polyethylene glycol and dimethylformamide.

3. The composite copper paste for low-temperature sintering according to claim 1, characterized in that, The copper nanoparticles have a particle size range of 80-100 nm.

4. The composite copper paste for low-temperature sintering according to claim 1, characterized in that, The antioxidant copper nanowires have an average diameter of 50-80 nm and a length of 10-50 μm.

5. The composite copper paste for low-temperature sintering according to claim 4, characterized in that, The method for preparing the antioxidant copper nanowires is as follows: copper source, reducing agent and capping agent are dissolved in solvent II, and the antioxidant copper nanowires are obtained by hydrothermal reaction.

6. The composite copper paste for low-temperature sintering according to claim 5, characterized in that, The copper source is any one of copper chloride dihydrate, copper nitrate trihydrate, and copper sulfate pentahydrate; the capping agent is at least one of oleic acid, oleylamine, hexadecylamine, and octadecylamine; the reducing agent is glucose or ascorbic acid; and solvent II is at least one of deionized water, methanol, ethanol, and propanol.

7. The composite copper paste for low-temperature sintering according to claim 5, characterized in that, The mass ratio of copper source, reducing agent and capping agent is (0.5-9.5):(0.52-12.8):(6-72); the hydrothermal reaction temperature is 100-180℃ and the time is 3-10h.

8. The method for preparing the composite copper paste for low-temperature sintering according to claim 1, characterized in that, The steps are as follows: Antioxidant copper nanowires, copper nanoparticles, copper nanosheets and solvent I are mixed and degassed.

9. The application of the low-temperature sintering composite copper paste as described in claim 1 in electronic packaging materials.

10. The application according to claim 9, characterized in that, The application steps are as follows: apply low-temperature sintering composite copper paste to the substrate, heat it to 180-350℃ at a heating rate of 5-30℃ / min, apply a pressure of 1-5 MPa, and hold for 5-30 min to obtain the final product.

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