High-temperature and high-humidity resistant nano-copper and its preparation method

Abstract

The present invention discloses a high-temperature and high-humidity resistant nano-copper and a preparation method thereof. The high-temperature and high-humidity resistant nano-copper is a nano-copper whose surface is modified with a formate-copper ion complex and an alkyl hydrophobic layer. Its preparation is based on the oxidation inhibition effect of formic acid, by laser direct writing synchronously inducing the photothermal reduction of nano-copper oxide, and forming a coordination passivation layer on the surface of the sintered nano-copper, while introducing long-chain organic amines to significantly improve the hydrophobicity of the nano-copper, thereby forming a more stable hydrophobic anti-oxidation layer on the surface of the nano-copper. In addition, the high-temperature and high-humidity resistant nano-copper prepared by the present invention has excellent electrical conductivity and can form good adhesion with flexible / rigid substrates. Compared with the prior art, the process of the present invention is simple, and effective anti-oxidation / hydrophobic surface treatment is performed based on laser patterning direct writing. While significantly improving processing efficiency, it realizes the one-step integration of multiple properties of high-temperature and high-humidity resistant nano-copper.

Description

Technical Field

[0001] The invention relates to surface treatment of nano copper, and in particular to high-temperature and high-humidity resistant nano copper and a preparation method thereof. Background Art

[0002] Nanocopper, a copper material with unique physical and chemical properties at the nanoscale, has attracted widespread attention in recent years for its outstanding performance in catalysis (high-efficiency catalysts and carriers), electronics (microelectromechanical devices, conductive inks, printed circuit boards, etc.), antimicrobial applications (healthcare, food packaging, water treatment, etc.), energy (solar energy / lithium-ion batteries, thermal interface materials), and environmental remediation (heavy metal pollution purification). Compared to macroscale copper, nanocopper exhibits a higher specific surface area, stronger surface activity, and excellent electromechanical properties.

[0003] However, nanocopper is highly susceptible to failure in long-term high-temperature environments. Compared to bulk copper, its thermal stability deteriorates significantly due to its small particle size and large surface area. Furthermore, nanocopper is prone to corrosion in high-humidity environments, which in turn affects its conductivity and appearance. Furthermore, further increases in humidity accelerate the oxidation of the nanocopper surface, ultimately leading to the formation of copper oxides.

[0004] In order to improve the oxidation resistance and durability of nano copper in high temperature and high humidity environments, a variety of antioxidant and anti-corrosion surface treatment methods have been developed:

[0005] (1) Surface coating: By coating the surface of nano-copper with a layer of stable substances (such as metals such as gold, silver, and nickel, or non-metals such as silicon dioxide, carbon layer, and polymer), oxygen and moisture can be effectively blocked from direct contact with the nano-copper, thereby preventing its oxidation and aggregation.

[0006] (2) Surface passivation: Stable coordination functional groups are introduced on the surface of nano-copper by chemical or physical methods to form a dense compound film and increase its surface energy, thereby improving its stability under high temperature and high humidity.

[0007] (3) Surface modification: forming a self-assembled film on the surface of nano-copper by chemical bonding or other means (such as using thiol compounds) to effectively improve the surface properties of nano-copper, form a stable protective layer, and enhance its high temperature and high humidity antioxidant properties.

[0008] (4) Surface modification and composite materials: Nano-copper is composited and embedded with other materials (such as ceramics, organic polymers, etc.) to prevent direct exposure to high-temperature and humid environments under the effect of physical isolation, and at the same time, the overall performance of nano-copper is enhanced by taking advantage of the characteristics of the composite material.

[0009] Among the above treatment methods, method (1) has a better antioxidant effect, but it is more expensive and the process is more complicated. Although the nano-copper obtained by methods (2) to (4) has a certain antioxidant effect, it will still undergo irreversible oxidation failure when exposed to high temperature and high humidity for a long time.

[0010] In the prior art, the corresponding method (1) is taken as an example of "a method for preparing nano-carbon coated copper powder" with patent number CN201910232685.5, and the steps include: preparing polyacrylonitrile solution: adding polyacrylonitrile powder to a solvent, stirring it at 60℃~80℃ to obtain a polyacrylonitrile solution; coating carbon-rich material: taking copper powder with a particle size of 0.1μm~10μm, first pickling the copper powder with dilute sulfuric acid with a mass concentration of 2%~8%, and then repeatedly washing the pickled copper powder with distilled water until The process is as follows: the copper powder after acid washing and water washing is placed in a vacuum drying oven, kept at 40°C to 80°C for 2 to 3 hours, and dried to obtain clean copper powder; the clean copper powder is weighed and added to a polyacrylonitrile solution, and electromagnetically stirred to obtain a mixture; the carbon-rich material is pre-oxidized by placing the mixture in a stainless steel reactor for pre-oxidation treatment; the carbon-rich material is pyrolyzed to prepare nanocarbon-coated copper powder; the stainless steel reactor is evacuated to a vacuum degree of 1×10 -1 mpa~1×10 -3 mpa, then fill a stainless steel reactor with inert gas for carbonization treatment, causing the carbon atoms in the polyacrylonitrile to be pyrolyzed into a two-dimensional carbon network structure that is evenly coated on the surface of the copper powder. Finally, after cooling to room temperature, the nanocarbon-coated copper powder is obtained. Although the method of the present invention is simple and easy to implement, and the resulting antioxidant copper powder has good conductivity, the process is cumbersome and requires to be carried out in an inert gas, which makes the reaction conditions relatively harsh.

[0011] In the prior art, corresponding to method (1), taking "Anti-oxidation super-hydrophobic copper film and its preparation method" with patent number CN202111250495.X as an example, the anti-oxidation super-hydrophobic copper film is a graphitized carbon layer wrapped around the copper nanoclusters, and the formed copper@carbon core-shell structure is uniformly deposited on the substrate to form a copper-carbon film, and the surface morphology of the copper-carbon film is nano-peak-shaped. The anti-oxidation super-hydrophobic copper film is prepared by chemical vapor deposition, which includes the following steps: substrate cleaning, placing the cut substrate into an ultrasonic cleaning machine for ultrasonic cleaning; substrate etching, placing the substrate into an etching solution, and etching the substrate surface; precursor preparation, respectively weighing an organic metal precursor and a liquid organic precursor for standby use, wherein the organic metal precursor is Cu(I) or Cu(II) organic metal copper; the liquid organic precursor is a hydrocarbon with a decomposition temperature lower than that of the organic metal precursor; charging, placing the etched substrate into the reaction zone of a tube furnace, respectively loading the precursors into a raw material tank, closing the raw material tank valve and connecting the raw material tank to the tube furnace; introducing hydrogen, introducing hydrogen into the tube furnace to replace the air in the tube furnace, and increasing the pressure in the tube furnace. Reach 1000~9000Pa;Argon gas is passed into, argon gas is passed into head tank, argon gas is completely filled with head tank, air is isolated, and the pressure in head tank is made to be identical with the pressure in tube furnace;Reaction zone heating, tube furnace is heated, the reaction zone in tube furnace is in reaction temperature, and described reaction temperature is 400~600 DEG C;Head tank heating, head tank is heated, organometallic precursor and liquid organic precursor are all gasified;Deposit, open head tank valve, precursor is passed into reaction zone by argon gas and is deposited, and the product after deposition will be deposited on the surface of substrate;Insulation, after deposition is completed, argon gas and head tank valve are quickly closed, the hydrogen concentration in control tube furnace reaction zone is controlled, the temperature of tube furnace reaction zone is dropped to room temperature, obtain described anti-oxidation super-hydrophobic copper film.Although the method is easy to control, and repeatability is good, reaction needs high pressure environment and inert gas protection, thus inevitably can significantly increase cost.

[0012] In the prior art, the corresponding method (1) is described in Patent No. CN201710343566.8, "A New Anti-Oxidation Nano-Copper Solder Paste, Its Preparation Method, and Application." This method uses a magnetron sputtering process to uniformly coat the surface of nano-copper powder with a metal film (gold or silver), then uses the traditional nano-copper solder paste formula and adds an appropriate amount of molding aids to prepare a new type of anti-oxidation and anti-cracking nano-copper solder paste. This invention prevents oxidation of nano-copper by coating it with an inert metal gold / silver layer, enabling long-term trouble-free service in high-temperature and high-humidity environments. However, this significantly increases material costs, limiting large-scale applications.

[0013] In the prior art, the corresponding method (2) is taken as an example of the "surface treatment method of copper-containing materials" with patent number CN201710751393.3. A surface treatment method of copper-containing materials is provided, which adopts a simple method to modify or adsorb formate on the surface of the copper material, enhance the antioxidant ability of the copper material, and make it have better conductivity. The copper-containing material is mixed with a polar solvent, stabilizers and additives are added, and then sealed and pressurized for reaction, and then liquid-solid separation, washing, and drying are performed to complete the antioxidant surface treatment of the copper material. Among them, formate is used to treat the copper surface. The redox potential of formate is lower than that of copper, and the oxidation kinetics of formate are slow, which can effectively prevent the chemical or electrochemical corrosion of copper. It is applicable to all zero-valent or partially oxidized copper-containing materials. The copper-containing material treated by this invention has stronger antioxidant ability, salt and alkali corrosion resistance and higher conductivity than before treatment, and can be used for copper-based conductive slurry, etc. However, the operation process is relatively cumbersome, the reaction time is long, and a closed reaction condition of pressurization and heating is required, which is not suitable for efficient treatment under room temperature environment. In addition, it is difficult to prevent the copper-based conductive paste prepared by this method from being oxidized during long-term storage.

[0014] In the prior art, the corresponding method (2) is taken as an example of the “Preparation Method of Antioxidant Copper-Based Conductive Ink” with patent number CN201710752246.8. The surface treatment of the copper material is as follows: 250-3000 mesh copper powder is mixed with a polar solvent (at least one of amide solvents, alcohol solvents, ester solvents, ether solvents, and water), a formate stabilizer is added and mixed, and then a sealed reaction is carried out in a pressure-resistant container at 120-180° C. for 0.01-100 hours, followed by liquid-solid separation, washing, and drying. The antioxidant copper-based conductive ink is prepared by compounding the treated copper powder with other media of the conductive paste according to the mass percentage of 10%-74.5% antioxidant copper powder, 0-20% conductive particles, 20%-50% organic solvent, 5%-30% binder, and 0.5%-20% additive, and stirring evenly to obtain the conductive paste. The antioxidant copper-based conductive ink is printed and cured. The antioxidant copper-based conductive ink prepared by this invention has good stability, excellent conductivity and dispersibility, but it also has disadvantages such as relatively harsh reaction conditions and poor long-term storage of the antioxidant copper-based conductive ink.

[0015] In the prior art, the corresponding method (3) is described in the patent number CN202110912124.7, “Anti-oxidation copper film / copper wire and its preparation method and application”. Anti-oxidation copper powder, alcohol solvent, amine solvent, resin, and additive are ground and mixed, and degassed to obtain an anti-oxidation copper slurry. The anti-oxidation copper slurry is applied to a substrate, dried and pre-cured under an inert atmosphere to obtain a copper film precursor 1 / copper wire precursor 1. The copper film precursor 1 / copper wire precursor 1 is cured under an inert atmosphere to obtain a copper film precursor 2 / copper wire precursor 2. The copper film precursor 2 / copper wire precursor 2 is placed in a compound containing a thiol group or a disulfide bond to obtain an anti-oxidation copper film / copper wire. Although the copper film / copper wire obtained by this invention has excellent oxidation resistance, an inert atmosphere is required to obtain high conductivity, and the preparation conditions are relatively harsh.

[0016] In the prior art, corresponding to method (2) and method (3), taking the patent number CN202010578213.8 "Anti-oxidation copper material and its preparation method" as an example, the anti-oxidation copper material is a copper material whose surface is modified with formate and thiol, and the thiol is adsorbed on the surface of the copper material modified by the formate. The preparation method of the above-mentioned anti-oxidation copper material comprises the following steps: adding a formate solution with a concentration of 1 to 15 mol / L and a solvent to a first container and stirring evenly to obtain a mixed solution, then placing the copper material in the first container containing the above-mentioned mixed solution, reacting at a temperature of 80 to 180 ° C for 0.5 to 24 hours, pouring out the supernatant, and adding a 1.0×10 -4 ~1.0×10 -1 The copper material is reacted in a 100 mol / L thiol for 0.5 to 30 minutes, followed by liquid-solid separation, washing, and drying to obtain the antioxidant copper material. In the present invention, the copper material modification process only requires a common open container environment and a short time to significantly improve the antioxidant capacity of the copper material, offering advantages such as simple preparation and low cost. However, obtaining the pre-processed raw materials involves conditions such as closed high-pressure heating, which to some extent limits efficient preparation.

[0017] In the prior art, the corresponding method (4) is to take the patent number CN202210906888.X "Anti-oxidation copper nanowire transparent electrode and its preparation method and application" as an example, take the copper nanowire stock solution prepared by the liquid phase method, use a non-polar organic solvent to wash and centrifuge, dissolve the obtained copper nanowire in anhydrous ethanol to obtain a copper nanowire dispersion; dilute the copper nanowire dispersion with deionized water and ultrasonically treat it; add an organic acid solution to the obtained solution, and ultrasonically treat it at the same time to remove the coating agent on the surface of the copper nanowire; filter the obtained solution with a filter membrane for purification, and then redissolve the copper nanowire in anhydrous ethanol, and repeat the aforementioned dilution, filtration, and purification. The membrane filtration purification and redissolution process produces a copper nanowire spray liquid for future use. The spray liquid is then sprayed onto a flexible substrate under high pressure to form a film, while a heating platform is used to heat the bottom of the flexible substrate to evaporate the solvent, thereby producing a copper nanowire thin film. The copper nanowire thin film is then immersed in the organic acid solution, rinsed with anhydrous ethanol, and vacuum-dried to initially produce a copper nanowire transparent electrode. The resulting copper nanowire transparent electrode is then treated with argon plasma and then stored in a vacuum chamber to produce a copper nanowire transparent electrode with enhanced conductivity. An aluminum oxide protective layer is deposited on the surface of the resulting copper nanowire transparent electrode using atomic layer deposition technology to produce an oxidation-resistant copper nanowire transparent electrode. In the present invention, the aluminum oxide deposited by atomic layer deposition is dense, has good isolation effect, and strong oxidation resistance. The introduced aluminum oxide shell has a uniform nanometer-level thickness and has little effect on the light transmittance and sheet resistance of the transparent electrode. The argon plasma treatment acts as a welding agent for the copper nanowire conductive network, significantly reducing contact resistance and improving conductivity. However, this method not only involves expensive physical vapor deposition (atomic layer deposition), but also involves abnormal conditions such as argon atmosphere and high-pressure spraying, which is not conducive to large-scale processing.

[0018] In the prior art, the corresponding method (4) is described in the patent number CN201910399914.2, "A method for preparing an anti-oxidation micro-nano copper material". Micro-nano copper powder is prepared using a micro-nano copper preparation device; an organic coating agent is placed in the vacuum chamber of the in-situ coating device, and the organic coating agent in the vacuum chamber is sublimated or vaporized by heating; an inert gas is introduced into the preparation system, and the micro-nano copper powder is introduced into the vacuum chamber of the in-situ coating device along with the inert gas, and the sublimated or vaporized organic coating agent contacts and coats the surface of the micro-nano copper particles. Although the vacuum heating and inert atmosphere in the invention form a good organic coating on the surface of the micro-nano copper ions, greatly improving the anti-oxidation and dispersibility of the micro-nano copper particles and reducing their surface activity, the specific processing environment of the entire process will inevitably cause cost-effectiveness problems and does not meet the actual application requirements.

[0019] Therefore, developing an antioxidant surface treatment method for high-temperature and high-humidity resistant nano-copper with simple preparation, efficient processing, strong compatibility and high cost-effectiveness is the current technical challenge to solve the application of nano-copper in functional fields such as catalysis, electronic and electrical, antibacterial, energy, and environmental remediation. Summary of the Invention

[0020] The purpose of the present invention is to address the deficiencies of the existing technology and provide a high-temperature and high-humidity resistant nano-copper and a preparation method thereof. The nano-copper is prepared by laser direct writing modification / reduction sintering, and the method is simple, efficient and has excellent effects.

[0021] The technical solutions adopted in the present invention are as follows:

[0022] A high-temperature and high-humidity resistant nano-copper, which is a nano-copper with a formate-copper ion complex and an alkyl hydrophobic layer modified on its surface;

[0023] The preparation method mainly comprises the following steps:

[0024] An alcohol solvent, an organic dispersant, an organic auxiliary agent 1, an organic auxiliary agent 2, a long-chain organic amine, and an appropriate amount of formic acid are mixed and heated and stirred to obtain a functional precursor solution; an appropriate amount of nano-copper oxide is added to the functional precursor solution and fully ultrasonically dispersed to obtain a functional nano-copper oxide ink; the functional nano-copper oxide ink is coated on a pretreated substrate and heated and dried to obtain a functional nano-copper oxide film; the functional nano-copper oxide film is subjected to laser direct writing modification / reduction sintering to obtain high-temperature and high-humidity resistant nano-copper.

[0025] The alcohol solvent is selected from one or more of monohydric alcohol, dihydric alcohol and polyhydric alcohol; the organic dispersant is selected from one or more of polyacrylamide organic polymer, polyethylene oxide organic polymer, cetyltrimethylammonium bromide, tannin and lignin, but not limited thereto; the organic auxiliary agent 1 is an organic amide, which is selected from one or more of formamide, acetamide, propionamide, butanamide, valeramide, acetylmethylamine, acetylethylamine, propionylethylamine, isopropylamide, lactamide, butyrylmethylamine, isobutylamide, methylacetamide, acetylvinylamine, N,N-dimethylformamide, N,N-dimethylacetamide and N-ethylacetamide, but not limited thereto; the organic auxiliary agent 2 is an organic alcoholamine, which is selected from one or more of ethanolamine, diethanolamine, triethanolamine, methylethanolamine, dimethylethanolamine, isopropanolamine, ethylpropanolamine, isobutanolamine, hexanolamine, cyclohexanolamine, N-methylethanolamine, N,N-dimethylethanolamine The long-chain organic amine is selected from one or more of dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosylamine, behenylamine, dodecylbenzylamine, hexadecylbenzylamine, eicosylbenzylamine, dodecyldimethylamine, dodecyltrimethylamine, tetradecyldimethylamine, hexadecyldimethylamine, octadecylmethylamine, octadecyldimethylamine, octadecylethylamine, octadecyldiethylamine, octadecylaniline, eicosyldimethylamine, behenyltrimethylamine, N-methyloctadecylamine, N,N-dimethyldodecylamine, N,N-dimethylhexadecylamine, N,N-dimethyloctadecylamine, N-ethyldodecylamine, N-butyldodecylamine, diethylenetriamine, and oleylamine, but is not limited thereto; the heating and stirring temperature is 50-70° C., the rotation speed is 600-1500 rpm, and the time is 2-20 h.

[0026] The nano copper oxide is selected from one or more of copper oxide nanoparticles, copper oxide nanowires, copper oxide nanosheets, copper oxide nanorods, and copper oxide nanoshuttles, but is not limited thereto; the real-time temperature of the ultrasonic dispersion is 50-60° C., the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 0.1-2 h; the functional nano copper oxide ink comprises 34.8-45.1 wt% of nano copper oxide, 38.6-43.5 wt% of an alcohol solvent, 5.9-8.5 wt% of an organic dispersant, 0.0-2.5 wt% of an organic additive 1, 0.0-5.2 wt% of an organic additive 2, 4.5-5.0 wt% of a long-chain organic amine, and 3.4-4.0 wt% of formic acid.

[0027] The coating method is selected from one or more of spin coating, spraying, scraping, brushing, dripping, and screen printing, but is not limited thereto; the pretreatment is oxygen plasma surface treatment, and the treatment time is 60s to 150s; the substrate includes a flexible substrate and a rigid substrate, and the flexible substrate is selected from one or more of polyimide (PI), polyethylene terephthalate (PET), polyvinyl alcohol (PVA), and polyethylene naphthalate (PEN), but is not limited thereto; the rigid substrate is selected from one or more of polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSF), liquid crystal polymer (LCP), glass, silicon wafer, and ceramic, but is not limited thereto; the heating and drying temperature is 50 to 80°C, and the time is 2 to 12 hours.

[0028] The laser is a continuous green light with a wavelength of 532nm; the power of the laser direct writing modification / reduction sintering is 100-300mW, the speed is 20-200mm / s, and the scanning period is 20-40μm; the laser direct writing modification / reduction sintering is based on the oxidation inhibition effect of formic acid, and synchronously induces the photothermal reduction of nano-copper oxide through laser direct writing, and forms a coordination passivation layer on the surface of the sintered nano-copper, while introducing long-chain organic amines to significantly improve the hydrophobic properties of the nano-copper, thereby forming a more stable hydrophobic anti-oxidation layer on the surface of the nano-copper.

[0029] The present invention's laser direct writing modification / reduction sintering based on laser processing mainly includes three aspects: First, the instantaneous temperature field created by high-energy laser irradiation can promote a partial redox reaction between formic acid and nano-copper oxide, causing the reduced zero-valent copper surface to rearrange to a Cu(110) crystal plane; then, the copper ions in the reaction product continue to coordinate and complex with the formate radicals obtained by decomposition to form a passivation protective film on the nano-copper surface, which can effectively improve the thermal stability of the nano-copper in a high-temperature environment. Second, after the aforementioned coordination passivation layer is formed, the hydrophilic amino groups contained in the introduced long-chain organic amine will interact with the oxide layer and exposed copper atoms on the nano-copper surface through chemical bonding, thereby stably adsorbing on the nano-copper surface; then, the hydrophobic long carbon chains in the long-chain organic amine molecules will be arranged in a directional manner, facing outward, while the hydrophilic amino groups are fixed to the nano-copper surface. This directional arrangement of molecules changes the physicochemical properties of the nano-copper surface, making it exhibit strong hydrophobicity (high-humidity corrosion resistance). Third, under the action of laser photothermal radiation, the reducing solvent, dispersant, and organic additive in the functional nano-copper oxide film are decomposed into aldehyde and carboxyl groups, fully reducing the divalent copper ions to zero-valent copper. At the same time, the molten nano-copper adheres to each other under the surface plasmon resonance effect and fuses and agglomerates as the specific surface area decreases. Finally, under the action of laser patterned scanning, it repeatedly melts and solidifies to form a uniform and continuous conductive matrix. The synergistic effect of the above three aspects is the key to significantly improving the oxidation resistance and stability of nano-copper in high temperature and high humidity environments.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] (1) Functional nano copper oxide ink is simple to prepare, low in cost, easy to store for a long time, not subject to oxidation risk, and suitable for various coating processes such as printing, coating, and printing.

[0032] (2) Laser direct writing modification can induce the coordination passivation of formic acid on the surface of nanocopper and the hydrophobic adsorption of long-chain organic amines on the surface of nanocopper. Compared with the case where there is no formate and long-chain organic amine and the case where there is only formate, it has stronger antioxidant ability and stability in high temperature and high humidity environment.

[0033] (3) Laser reduction sintering can pattern nano-copper oxide after selective photothermal irradiation to generate a nano-copper matrix with excellent conductivity and adhesion.

[0034] (4) Laser direct writing modification / reduction sintering does not rely on tedious process steps such as pre-treatment and post-treatment, as well as the addition of external chemical reagents. It does not require vacuum or inert atmosphere and can be carried out directly in the atmospheric environment. The treatment process is simple and it is an environmentally friendly anti-oxidation surface treatment method.

[0035] (5) Laser direct writing modification / reduction sintering is not limited by the shape and size of nano-copper materials and is suitable for multi-scale nano-copper.

[0036] (6) The laser direct writing modification / reduction sintering process is highly efficient and can significantly shorten the production cycle compared to traditional surface treatment methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is an optical photograph of the prepared functional nano copper oxide ink;

[0038] Figure 2 The optical photograph of the prepared rectangular pattern high temperature and high humidity resistant nano copper electrode and the magnified optical microscope photograph of the interface;

[0039] Figure 3 The relative resistance changes of high temperature resistant nano copper with different formic acid concentrations at 180°C over time;

[0040] Figure 4 The relative resistance changes of high temperature and high humidity resistant nano-copper with different oleylamine concentrations at 180°C over time;

[0041] Figure 5 The relative resistance changes of nano copper (original), high temperature resistant nano copper (FA) and high temperature and high humidity resistant nano copper (FFA) at 180°C over time;

[0042] Figure 6 The relative resistance change of nano copper with high temperature and humidity resistance at 180℃, 190℃, 200℃, 210℃ and 220℃ respectively over time;

[0043] Figure 7 To compare the relative resistance changes of nano-copper, high temperature resistant nano-copper and high temperature and high humidity resistant nano-copper over time at 80℃ and 90%RH;

[0044] Figure 8 Optical microscope photos of control nano-copper, high-temperature resistant nano-copper, and high-temperature and high-humidity resistant nano-copper before and after exposure to 80°C and 90% RH;

[0045] Figure 9 To compare the relative resistance changes of nano-copper, high temperature resistant nano-copper and high temperature and high humidity resistant nano-copper over time during 22 cycles between 25℃, 30%RH and 90%RH;

[0046] Figure 10 To compare the relative resistance changes of nano-copper, high-temperature resistant nano-copper and high-temperature and high-humidity resistant nano-copper over time during 22 cycles between 80% RH, 20℃ and 90℃. DETAILED DESCRIPTION

[0047] The present invention will be described in detail below by way of examples in conjunction with the accompanying drawings. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are therefore only examples and are not intended to limit the scope of protection of the present invention.

[0048] Example 1:

[0049] S1: Weigh 0.65 g of polyvinyl pyrrolidone and 0.297 g of formic acid, mix them in 3.0 mL of ethylene glycol, and heat and stir them uniformly at 60°C and 1000 rpm for 6 h to obtain functional precursor solution 1;

[0050] S2: Weigh 0.377 g of oleylamine and mix it with the functional precursor solution 1. Heat and stir evenly at 55°C and 1000 rpm for 2 h to obtain a functional precursor solution.

[0051] S3: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the functional precursor solution for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55° C., the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 2.5 min to obtain a functional nano copper oxide solution 1.

[0052] S4: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the functional nano copper oxide solution 1 for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55° C., the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 3 min to obtain a functional nano copper oxide ink.

[0053] S5: Mechanically shake the functional nano copper oxide ink for 0.5 min and let it stand for later use;

[0054] S6: Take a flexible polyimide film substrate with a thickness of 50 μm and a size of 30×30 mm, clean the surface impurities with isopropyl alcohol ultrasonically for 5 minutes, and dry it for later use;

[0055] S7: The flexible polyimide film substrate is subjected to oxygen plasma surface treatment for 120 s;

[0056] S8: The flexible polyimide film substrate treated in S7 was vacuum-adsorbed on the spin coating chuck of the spin coater, and 1.0 mL of functional nano copper oxide ink was dropped on the center of the substrate. The substrate was spin-coated at a speed of 1500 rpm for 10 s and 800 rpm for 5 s.

[0057] S9: placing the flexible polyimide film substrate after spin coating the functional nano copper oxide ink in a constant temperature blast drying oven or a vacuum drying oven for heating and drying at a temperature of 50° C. for 3 hours to obtain a functional nano copper oxide film;

[0058] S10: placing the flexible polyimide film substrate covered with the functional nano-copper oxide film on a laser processing platform with a continuous green light of 532 nm wavelength, and adjusting the height of the processing platform for laser focusing;

[0059] S11: Draw a rectangular electrode pattern with a size of 9×3 mm, so that the laser performs patterned direct writing (laser direct writing modification / reduction sintering) along the rectangular electrode pattern filling path with a power of 210 mW, a speed of 40 mm / s, and a line scanning period of 30 μm, converting the black nano-copper oxide at the scanning path into red nano-copper to obtain a high-temperature and high-humidity resistant nano-copper electrode.

[0060] Figure 1 This is an optical photograph of the prepared functional nano-copper oxide ink.

[0061] Figure 2 These are optical photographs of the prepared rectangular patterned high-temperature and high-humidity resistant nano-copper electrode and magnified optical microscope photographs of the interface.

[0062] Example 2:

[0063] S1: Weigh 0.65 g of polyvinyl pyrrolidone, 0.297 g of formic acid, and 0.2 g of isopropanolamine in 3.0 mL of ethylene glycol, and heat and stir uniformly at 60°C and 1000 rpm for 8 h to obtain functional precursor solution 1;

[0064] S2: Weigh 0.39 g of oleylamine and mix it with the functional precursor solution 1. Heat and stir uniformly at 60°C and 1000 rpm for 2 h to obtain the functional precursor solution.

[0065] S3 to S10 are the same as in Example 1;

[0066] S11: Draw a rectangular electrode pattern with a size of 9×3 mm, so that the laser performs patterned direct writing (laser direct writing modification / reduction sintering) along the rectangular electrode pattern filling path at a power of 180 mW, a speed of 60 mm / s, and a line scanning period of 30 μm, converting the black nano-copper oxide at the scanning path into red nano-copper to obtain a high-temperature and high-humidity resistant nano-copper electrode.

[0067] Example 3:

[0068] S1: Weigh 0.65 g of polyvinyl pyrrolidone, 0.297 g of formic acid, and 0.4 g of N,N-dimethylformamide in 3.0 mL of ethylene glycol, and heat and stir uniformly at 60°C and 1000 rpm for 6 h to obtain functional precursor solution 1;

[0069] S2: Weigh 0.39 g of oleylamine and mix it with the functional precursor solution 1. Heat and stir uniformly at 60°C and 1000 rpm for 2 h to obtain a functional precursor solution.

[0070] S3 to S10 are the same as in Example 1;

[0071] S11: Draw a rectangular electrode pattern with a size of 9×3 mm, so that the laser performs patterned direct writing (laser direct writing modification / reduction sintering) along the rectangular electrode pattern filling path with a power of 190 mW, a speed of 60 mm / s, and a line scanning period of 30 μm, converting the black nano-copper oxide at the scanning path into red nano-copper to obtain a high-temperature and high-humidity resistant nano-copper electrode.

[0072] Example 4:

[0073] S1: 0.65 g of polyvinyl pyrrolidone and 0.158 g, 0.226 g, 0.297 g, 0.371 g, and 0.448 g of formic acid were weighed in sequence and mixed in 3.0 mL of ethylene glycol. The mixture was uniformly heated and stirred at 1000 rpm at 60°C for 6 h to obtain five precursor solutions with different formic acid concentrations.

[0074] S2: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the five precursor solutions for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55°C, the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 2.5 min to obtain five nano-copper oxide solutions 1.

[0075] S3: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the five nano-copper oxide solutions 1 for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55°C, the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 3 min to obtain five nano-copper oxide inks with different formic acid concentrations.

[0076] S4: Mechanically shake the nano copper oxide ink for 3 minutes and let it stand for later use;

[0077] S5: Take 5 flexible polyimide film substrates with a thickness of 50 μm and a size of 30×30 mm, clean the surface impurities with isopropyl alcohol ultrasonically for 5 minutes, and dry them for later use;

[0078] S6: The flexible polyimide film substrate is subjected to oxygen plasma surface treatment for 120 s;

[0079] S7: The flexible polyimide film substrate treated in S6 was vacuum-adsorbed on the spin coating chuck of the spin coater in sequence, and 1.0 mL of nano-copper oxide ink with different formic acid concentrations was dripped on the center of the substrate in sequence, and the coating was performed at a speed of 1500 rpm for 10 s and 800 rpm for 5 s;

[0080] S8: placing the flexible polyimide film substrate after spin-coating the nano copper oxide ink in a constant temperature blast drying oven or a vacuum drying oven for heating and drying at a temperature of 50° C. for 3 hours to obtain a nano copper oxide film;

[0081] S9: placing the flexible polyimide film substrate covered with the nano-copper oxide film on a laser processing platform with a continuous green light of 532 nm wavelength in sequence, and adjusting the height of the processing platform for laser focusing;

[0082] S10: Drawing a rectangular electrode pattern with a size of 9×3 mm, so that the laser performs pattern direct writing (laser direct writing passivation / reduction sintering) along the rectangular electrode pattern filling path at a power of 210 mW, a speed of 40 mm / s, and a line scanning period of 30 μm, converting the black nano-copper oxide at the scanning path into red nano-copper to obtain a high-temperature resistant nano-copper electrode;

[0083] S11: Manually apply a thin silver paste to each end of each high-temperature resistant nano-copper electrode to draw out the electrode, and place it in a vacuum drying oven to heat and dry at 60°C for 3 hours;

[0084] S12: Design a voltage divider circuit board according to the resistance value of the high-temperature resistant nano-copper electrode, and connect each high-temperature resistant nano-copper electrode in turn through an alligator clip wire, and connect it to a data acquisition instrument through a DuPont line;

[0085] S13: placing the high-temperature resistant nano-copper electrode in a constant temperature blast drying oven, setting the temperature to 180° C., and recording the partial pressure change in real time using a data acquisition instrument;

[0086] S14: Convert the data results into the relative resistance change of the high-temperature resistant nano-copper electrode through the voltage divider formula.

[0087] Figure 3 The figure shows the change in relative resistance of high-temperature resistant nano-copper with different formic acid concentrations at 180°C over time. It can be seen that when the relative content of formic acid is 91%, its high-temperature resistance after laser direct writing modification is the best (the relative resistance change rate is about 0.38). When the formic acid content decreases, the complex formed by its reaction and coordination with the nano-copper surface is not enough to resist oxygen intrusion, and the high-temperature oxidation resistance is poor. When the formic acid content increases, it will trigger additional reactions at the interface with the nano-copper, affecting the passivation effect and surface properties, and will cause the high-temperature oxidation resistance of the nano-copper to fail in the long run.

[0088] Example 5:

[0089] S1: Weigh 5 times 0.65 g of polyvinyl pyrrolidone and 0.297 g of formic acid, mix them in 3.0 mL of ethylene glycol, and heat and stir them uniformly at 60°C and 1000 rpm for 6 h to obtain functional precursor solution 1;

[0090] S2: Weigh 0.122 g / 0.208 g / 0.297 g / 0.391 g / 0.488 g of oleylamine in sequence and mix them in functional precursor solution 1. Heat and stir evenly at 55°C and 1000 rpm for 4 h to obtain five functional precursor solutions with different oleylamine concentrations.

[0091] S3: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the five functional precursor solutions for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55° C., the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 2.5 min to obtain five functional nano copper oxide solutions 1.

[0092] S4: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the five functional nano copper oxide solutions 1 for full ultrasonic dispersion. The ultrasonic real-time temperature is 55° C., the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 3 min to obtain five functional nano copper oxide inks with different oleylamine concentrations.

[0093] S5 to S7 are the same as S4 to S6 in Example 4;

[0094] S8: The flexible polyimide film substrates were vacuum-adsorbed onto the spin coating chuck of the spin coater, and 1.0 mL of functional nano-copper oxide ink with different oleylamine concentrations was dripped onto the center of the substrates, and the coating was performed at 1500 rpm for 10 s and 800 rpm for 5 s.

[0095] S9: placing the flexible polyimide film substrate after spin coating the functional nano copper oxide ink in a constant temperature blast drying oven or a vacuum drying oven for heating and drying at a temperature of 55° C. for 4 hours to obtain a functional nano copper oxide film;

[0096] S10: placing the flexible polyimide film substrate covered with the functional nano-copper oxide film on a laser processing platform with a continuous green light of 532 nm wavelength in sequence, and adjusting the height of the processing platform for laser focusing;

[0097] S11: Draw a rectangular electrode pattern with a size of 9×3 mm, and perform pattern direct writing (laser direct writing modification / reduction sintering) along the rectangular electrode pattern filling path at a power of 210 mW, a speed of 40 mm / s, and a line scanning period of 30 μm, converting the black nano-copper oxide at the scanning path into red nano-copper to obtain a high temperature and high humidity resistant nano-copper electrode;

[0098] S12: Manually apply a thin silver paste to each end of each high-temperature and high-humidity resistant nano-copper electrode to draw out the electrodes, and place them in a vacuum drying oven for heating and drying at 60°C for 3 hours;

[0099] S13: Design a voltage divider circuit board according to the resistance value of the high-temperature and high-humidity resistant nano-copper electrode, and connect each high-temperature and high-humidity resistant nano-copper electrode in turn through an alligator clip wire, and connect it to a data acquisition instrument through a DuPont line;

[0100] S14: placing the high temperature and high humidity resistant nano copper electrode in a constant temperature blast drying oven, setting the temperature to 180°C, and recording the partial pressure change in real time using a data acquisition instrument;

[0101] S15: The data results are converted into the relative resistance change of the high temperature and high humidity resistant nano-copper electrode through the voltage divider formula.

[0102] Figure 4 The relative resistance change over time at 180°C for high-temperature and high-humidity-resistant nano-copper at different oleylamine concentrations is shown. It can be seen that, based on the optimal formic acid relative content (91%), when the oleylamine relative content reaches 91%, the high-temperature oxidation resistance of the nano-copper is significantly improved after laser direct writing (the relative resistance change rate is approximately 0.04). Furthermore, the overall thermal stability of the nano-copper is enhanced after adding different oleylamine concentrations.

[0103] Example 6:

[0104] S1: Weigh 0.65 g of polyvinyl pyrrolidone and mix it in 3.0 mL of ethylene glycol. Heat and stir evenly at 60°C and 1000 rpm for 2 h to obtain a control precursor solution.

[0105] S2: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the control precursor solution for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55°C, the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 2.5 min to obtain a control nano-copper oxide solution 1.

[0106] S3: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the control nano-copper oxide solution 1 for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55° C., the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 3 min to obtain a control nano-copper oxide ink.

[0107] S4: Mechanically shake the control nano copper oxide ink for 0.5 min and let it stand for later use;

[0108] S5-S6 are the same as S6-S7 in Example 1;

[0109] S7: The flexible polyimide film substrate was vacuum-adsorbed on the spin coating chuck of the spin coater, and 1.0 mL of the control nano-copper oxide ink was dropped on the center of the substrate. The substrate was spin-coated at 1500 rpm for 10 s and 800 rpm for 5 s.

[0110] S8: placing the flexible polyimide film substrate after spin coating the control nano copper oxide ink in a constant temperature blast drying oven or a vacuum drying oven for heating and drying at a temperature of 60° C. for 2 h to obtain a control nano copper oxide film;

[0111] S9: Place the flexible polyimide film substrate covered with the control nano-copper oxide film on a laser processing platform with a continuous green light of 532 nm wavelength, and adjust the height of the processing platform for laser focusing;

[0112] S10: Draw a rectangular electrode pattern with a size of 9×3 mm, so that the laser performs patterned direct writing (laser reduction sintering) along the rectangular electrode pattern filling path at a power of 210 mW, a speed of 40 mm / s, and a line scanning period of 30 μm, converting the black nano-copper oxide at the scanning path into red nano-copper to obtain a control nano-copper electrode.

[0113] S11: Manually apply a thin silver paste to both ends of the control nanocopper electrode to extract the electrode, and place it in a vacuum drying oven for heating and drying at 60°C for 3 hours;

[0114] S12: Design a voltage divider circuit board based on the resistance value of the control nano-copper electrode, connect the control nano-copper electrode via an alligator clip wire, and connect it to a data acquisition instrument via a DuPont wire;

[0115] S13: Weigh 0.65 g of polyvinyl pyrrolidone and 0.297 g of formic acid, mix them in 3.0 mL of ethylene glycol, and uniformly heat and stir at 1000 rpm at 60° C. for 6 h to obtain a formic acid precursor solution;

[0116] S14: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in a formic acid precursor solution for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55° C., the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 2.5 min to obtain a formic acid nano-copper oxide solution 1.

[0117] S15: Weigh 1.5 g of copper oxide nanowires (40 nm) and place them in the formic acid nano-copper oxide solution 1 for thorough ultrasonic dispersion. The ultrasonic real-time temperature is 55° C., the ultrasonic pulse width is 0.1 s, and the ultrasonic time is 3 min to obtain formic acid nano-copper oxide ink.

[0118] S16: Mechanically shake the formic acid nano copper oxide ink for 3 minutes and let it stand for standby use;

[0119] S17-S18 are the same as S6-S7 in Example 1;

[0120] S19: The flexible polyimide film substrate was vacuum-adsorbed on the spin coating chuck of the spin coater, and 1.0 mL of formic acid nano-copper oxide ink was dripped on the center of the substrate in sequence, and the coating was carried out at a speed of 1500 rpm for 10 s and 800 rpm for 5 s;

[0121] S20: placing the flexible polyimide film substrate after spin-coating the formic acid nano-copper oxide ink in a constant temperature blast drying oven or a vacuum drying oven for heating and drying at a temperature of 50° C. for 3 hours to obtain a formic acid nano-copper oxide film;

[0122] S21: placing a flexible polyimide film substrate covered with a formic acid nano-copper oxide film on a laser processing platform with a continuous green light of 532 nm wavelength, and adjusting the height of the processing platform for laser focusing;

[0123] S22: Drawing a rectangular electrode pattern with a size of 9×3 mm, so that the laser performs pattern direct writing (laser direct writing passivation / reduction sintering) along the rectangular electrode pattern filling path at a power of 210 mW, a speed of 40 mm / s, and a line scanning period of 30 μm, converting the black nano-copper oxide at the scanning path into red nano-copper to obtain a high-temperature resistant nano-copper electrode;

[0124] S23: Manually apply a thin silver paste on both ends of the high-temperature resistant nano-copper electrode to lead out the electrode, and place it in a vacuum drying oven for heating and drying at 60°C for 3 hours;

[0125] S24: Design a voltage divider circuit board according to the resistance value of the high-temperature resistant nano-copper electrode, connect the high-temperature resistant nano-copper electrode via an alligator clip wire, and connect it to a data acquisition instrument via a DuPont line;

[0126] S25 to S35 are the same as S1 to S11 in Example 1;

[0127] S36: Manually apply a thin silver paste to both ends of the high-temperature and high-humidity resistant nano-copper electrode to extract the electrode, and place it in a vacuum drying oven for heating and drying at 60°C for 3 hours;

[0128] S37: Design a voltage divider circuit board based on the resistance value of the high-temperature and high-humidity resistant nano-copper electrode, connect the high-temperature and high-humidity resistant nano-copper electrode via alligator clip wires, and connect it to the data acquisition instrument via DuPont wires;

[0129] S38: placing the control nano-copper electrode, the high-temperature resistant nano-copper electrode, and the high-temperature and high-humidity resistant nano-copper electrode in a constant temperature blast drying oven, setting the temperature to 180° C., and recording the partial pressure changes in real time using a data acquisition instrument;

[0130] S39: The data results are converted into relative resistance changes of the control nano-copper electrode, the high-temperature resistant nano-copper electrode and the high-temperature and high-humidity resistant nano-copper electrode through the voltage divider formula.

[0131] Figure 5 The relative resistance changes over time at 180°C for the control nano-copper, high-temperature-resistant nano-copper, and high-temperature-resistant and high-humidity-resistant nano-copper are shown. It can be seen that since the control nano-copper did not undergo coordination passivation modification on its surface after laser treatment, it accelerated its failure in high-temperature environments. The high-temperature-resistant nano-copper has good high-temperature oxidation resistance (relative resistance increases less) due to the laser-induced surface passivation forming a coordination complex protective layer. The high-temperature-resistant and high-humidity-resistant nano-copper also has the best high-temperature resistance due to the simultaneous introduction of oleylamine for surface adsorption during the laser-induced modification process.

[0132] Example 7:

[0133] S1 to S11 are the same as in Example 1;

[0134] S12: Repeat S1 to S11 4 times to finally obtain 5 high temperature and high humidity resistant nano-copper electrodes;

[0135] S13-S14 are the same as S12-S13 in Example 5;

[0136] S15: placing the high temperature and high humidity resistant nano copper electrode in a constant temperature blast drying oven, setting the temperature to 180°C / 190°C / 200°C / 210°C / 220°C in sequence, and recording the partial pressure changes in real time using a data acquisition instrument;

[0137] S16: The data results under different high temperature environments are converted into the relative resistance change of the high temperature and high humidity resistant nano-copper electrode through the voltage division formula.

[0138] Figure 6 The relative resistance of high-temperature, high-humidity-resistant nano-copper changes over time at 180°C, 190°C, 200°C, 210°C, and 220°C, respectively. It can be seen that when the high-temperature environment is 180°C and 190°C, the thermal stability of high-temperature, high-humidity-resistant nano-copper is comparable, with no significant difference. As the temperature continues to rise to 200°C and above, the electrical performance degradation of high-temperature, high-humidity-resistant nano-copper gradually increases. It can be considered that 190°C is the upper temperature limit of high-temperature, high-humidity-resistant nano-copper.

[0139] Example 8:

[0140] S1 to S37 are the same as in Example 6;

[0141] S38: placing the control nano-copper electrode, the high-temperature resistant nano-copper electrode, and the high-temperature and high-humidity resistant nano-copper electrode in an environmental test chamber, setting the temperature to 80° C. and the humidity to 90% RH, and recording the partial pressure changes in real time using a data acquisition instrument;

[0142] S39 is the same as Example 6.

[0143] Figure 7 The relative resistance changes over time for control nanocopper, high-temperature-resistant nanocopper, and high-temperature- and high-humidity-resistant nanocopper at 80°C and 90% RH are shown. It can be seen that the high-temperature-resistant nanocopper exhibits poor resistance to high humidity due to the lack of hydrophobic surface modification with long-chain organic amines. In comparison, the high-temperature- and high-humidity-resistant nanocopper exhibits the best high-humidity resistance, with a relative resistance change rate of approximately 0.45 after 85 hours of continuous high humidity. The inset shows that the hydrophobic angles of the control nanocopper, high-temperature-resistant nanocopper, and high-temperature- and high-humidity-resistant nanocopper surfaces are 30°, 8°, and 130°, respectively.

[0144] Figure 8 These are optical micrographs of the control nanocopper, high-temperature-resistant nanocopper, and high-temperature- and high-humidity-resistant nanocopper before and after exposure to 80°C and 90% RH. As can be seen, the surface of the high-temperature-resistant nanocopper has been covered in a dark green verdigris after continued high-humidity corrosion, while the control nanocopper surface also exhibits some purple-red wet oxidation marks. In contrast, the surface of the high-temperature- and high-humidity-resistant nanocopper showed no significant changes before and after exposure to high humidity.

[0145] Example 9:

[0146] S1 to S37 are the same as in Example 6;

[0147] S38: Place the control nano-copper electrode, the high-temperature resistant nano-copper electrode, and the high-temperature and high-humidity resistant nano-copper electrode in an environmental test chamber, set the temperature to 25°C, and cycle the humidity between 30% RH and 90% RH for 22 cycles (the duration of humidity climbing and falling is 1 hour, and the duration of humidity at 30% RH and 90% RH is 1 hour), and record the partial pressure changes in real time using a data acquisition instrument;

[0148] S39 is the same as Example 6.

[0149] Figure 9 The relative resistance changes over time of nano-copper, high-temperature-resistant nano-copper, and high-temperature and high-humidity-resistant nano-copper were compared during 22 cycles at 25°C, 30% RH, and 90% RH. It can be seen that after eliminating the high-temperature interference (25°C), the high-temperature and high-humidity-resistant nano-copper still has excellent corrosion stability under low-humidity and low-humidity cycles (the relative resistance change rate after 74 hours is approximately 0.05).

[0150] Example 10:

[0151] S1 to S37 are the same as in Example 6;

[0152] S38: placing the control nano-copper electrode, the high-temperature resistant nano-copper electrode, and the high-temperature and high-humidity resistant nano-copper electrode in an environmental test chamber, setting the humidity to 80% RH, and subjecting the temperature to 22 cycles between 20°C and 90°C (the duration of temperature rise and fall is 1 hour, and the duration of temperature at 20°C and 90°C is 1 hour), and recording the partial pressure changes in real time using a data acquisition instrument;

[0153] S39 is the same as Example 6.

[0154] Figure 10 The relative resistance changes over time of nano-copper, high-temperature-resistant nano-copper, and high-temperature and high-humidity-resistant nano-copper were compared during 22 cycles between 80% RH and 20°C and 90°C. It can be seen that after the introduction of temperature cycling in a continuous high-humidity environment, although the high-temperature and high-humidity-resistant nano-copper will respond slightly to temperature changes, it still has good overall thermal stability and corrosion resistance (the relative resistance change rate after 72 hours is about 0.44).

Claims

1. A method for preparing high temperature and high humidity resistant nano copper, characterized in that: The high-temperature and high-humidity resistant nano-copper is a nano-copper with a formate-copper ion complex and an alkyl hydrophobic layer modified on its surface; the preparation method comprises: mixing an alcohol solvent, an organic dispersant, an organic additive 1, an organic additive 2, a long-chain organic amine, and formic acid, and heating and stirring the mixture to obtain a functional precursor solution; adding nano-copper oxide to the functional precursor solution, and fully ultrasonically dispersing the mixture to obtain a functional nano-copper oxide ink, which comprises: 34.8-45.1wt% nano-copper oxide, 38.6-43.5wt% alcohol solvent, 5.9-8.5wt% organic dispersant, 0.0-2.5wt% organic additive 1, 0.0-5.2wt% organic additive 2, 4.5-5.0wt% long-chain organic amine, and 3.4-4.0wt% formic acid; the nano-copper oxide is copper oxide nanowires, the organic additive 1 The invention discloses an organic amide, an organic auxiliary agent 2, and an organic alcohol amine; a functional nano copper oxide ink is coated on a pretreated substrate, heated and dried to obtain a functional nano copper oxide film; the functional nano copper oxide film is subjected to laser direct writing modification / reduction sintering to obtain high temperature and high humidity resistant nano copper, the laser is a continuous green light with a wavelength of 532nm, the power of the laser direct writing modification / reduction sintering is 100-300mW, the speed is 20-200mm / s, and the scanning period is 20-40μm, the laser direct writing modification / reduction sintering is based on the oxidation inhibition effect of formic acid, and the laser direct writing synchronously induces the photothermal reduction of nano copper oxide, and forms a coordination passivation layer on the surface of the sintered nano copper, and at the same time introduces a long-chain organic amine to improve the hydrophobicity of the nano copper, so that a hydrophobic anti-oxidation layer is formed on the surface of the nano copper.

2. The method for preparing high temperature and high humidity resistant nano copper according to claim 1, characterized in that: The alcohol solvent is selected from one or more of monohydric alcohols and polyhydric alcohols.

3. The method for preparing high temperature and high humidity resistant nano copper according to claim 1, wherein: The organic dispersant is selected from one or more of polyacrylamide organic polymers, polyethylene oxide organic polymers, hexadecyltrimethylammonium bromide, tannin, and lignin.

4. The method for preparing high temperature and high humidity resistant nano copper according to claim 1, characterized in that: The long-chain organic amine is selected from the group consisting of dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, eicosylamine, behenylamine, dodecylbenzylamine, hexadecylbenzylamine, eicosylbenzylamine, dodecyldimethylamine, dodecyltrimethylamine, tetradecyldimethylamine, hexadecyldimethylamine, octadecylmethylamine, octadecyldimethylamine, octadecylethylamine, octadecyldiethylamine, octadecylaniline, eicosyldimethylamine, behenyltrimethylamine, N-methyloctadecylamine, One or more of N,N-dimethyldodecylamine, N,N-dimethylhexadecylamine, N,N-dimethyloctadecylamine, N-ethyldodecylamine, N-butyldodecylamine, diethylenetriamine, and oleylamine.

5. The method for preparing high temperature and humidity resistant nano copper according to claim 1, characterized in that: The pretreatment is oxygen plasma surface treatment, and the treatment time is 60s to 150s.

6. The method for preparing high temperature and high humidity resistant nano copper according to claim 1, characterized in that: The substrate is a flexible substrate or a rigid substrate; the flexible substrate is selected from one or more of polyimide (PI), polyethylene terephthalate (PET), polyvinyl alcohol (PVA), and polyethylene naphthalate (PEN); the rigid substrate is selected from one or more of polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polysulfone (PSF), liquid crystal polymer (LCP), glass, silicon wafer, and ceramic.

Images