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CN-122007410-A - Preparation method of nanoscale silver-coated copper powder

CN122007410ACN 122007410 ACN122007410 ACN 122007410ACN-122007410-A

Abstract

The invention relates to the technical field of silver-coated copper powder, in particular to a preparation method of nanoscale silver-coated copper powder. The invention solves the problem of hard agglomeration among particles by constructing a double-layer cladding structure of copper core-silver shell-silicon dioxide shell, realizes excellent oxidation resistance and corrosion resistance superior to common silver-coated copper powder and even pure silver powder, and can still maintain excellent conductivity through precise process control.

Inventors

  • WANG ZEHAO
  • LI QI
  • WANG TIANQI

Assignees

  • 浙江睿霄科技发展有限公司

Dates

Publication Date
20260512
Application Date
20260210

Claims (10)

  1. 1. The preparation method of the nano-scale silver-coated copper powder is characterized by comprising the following steps of: S1, cleaning and modifying copper powder, selecting spherical or particle copper powder with a quantitative D50=500-700 nm under a nitrogen atmosphere, transferring the copper powder into a reaction container, adding rare organic acid, stirring for 15min at normal temperature, centrifugally filtering, alternately washing with deionized water and absolute ethyl alcohol for three times, dispersing the washed copper powder in a mixed solution of absolute ethyl alcohol and deionized water, adding polyvinylpyrrolidone, and mechanically stirring for 45min to form copper powder dispersed materials; S2, continuously micro-flowing and precisely silvering, namely dissolving quantitative polyvinylpyrrolidone and a reducing agent in a water/ethanol mixed solution, mixing to form a solution A, slowly mixing a silver nitrate solution with ammonia water under a light-shielding condition to form a clear solution which is a solution B, homogenizing copper powder dispersion materials to ensure no sedimentation and form a solution C, synchronously injecting the solution A, the solution B and the solution C into a continuous flow micro-reactor by using a precise injection pump at a constant flow rate, keeping constant temperature and stirring at 55 ℃, and collecting silver plating dispersion liquid into a collecting tank in a nitrogen atmosphere after reacting for 45-75 seconds; S3, coating a protective layer, transferring the collected silver plating dispersion liquid into a gap type stirring reaction kettle, adding ammonia water to adjust the pH value, synchronously and slowly dropwise adding an ethanol solution of tetraethoxysilane and an ethanol solution of a silane coupling agent under the condition of mechanical stirring, and reacting for 4.5 hours under the condition of 38 ℃, keeping stirring for 1.5 hours after the reaction is finished, adding aminosilane, heating to 60 ℃, and reacting for 1 hour to obtain composite slurry with a SiO 2 protective layer; S4, after-treatment, carrying out centrifugal filtration on the composite slurry, washing with absolute ethyl alcohol for 4 times after solid-liquid separation to obtain a nano-particle wet cake, dispersing the wet cake in cyclohexane to form suspension, pouring the suspension into a freeze-drying tray, placing the freeze-drying tray into a freeze dryer for freezing until the suspension is completely solidified, and starting a vacuum pump to reduce the temperature to-80 ℃ for sublimation for 36 hours to obtain a nano-silver copper-clad powder finished product.
  2. 2. The method for preparing nano-scale copper-clad silver powder according to claim 1, wherein in the step S1, the organic acid is citric acid or oxalic acid, the concentration is 1.5%, and the volume ratio of the absolute ethyl alcohol to the deionized water is 1:1.
  3. 3. The method of claim 1, wherein in the step S3, the silane coupling agent is KH-550 with a mass concentration of 0.15% (w/v).
  4. 4. The method of preparing nano-scale copper-clad silver powder as set forth in claim 1, wherein in the step S2, the mass of polyvinylpyrrolidone is 66% of the total mass of the copper powder and the target silver layer, and when the silver nitrate solution is mixed with ammonia water, the ammonia water is added dropwise into the silver nitrate solution at a dropping rate of 0.62mL/min.
  5. 5. The method of claim 4, wherein in the step S2, the flow rate ratio of the solution A to the solution B to the solution C is 2:1:1.
  6. 6. The method of claim 1, wherein in the step S3, the pH is adjusted to 10, and the thickness of the SiO 2 protective layer is 2.5-3nm.
  7. 7. The method of preparing nano-scale copper-clad silver powder according to claim 1, wherein in the step S3, the dripping rate of the ethanol solution of the tetraethoxysilane and the ethanol solution of the silane coupling agent is 0.8mL/min, and the mechanical stirring rate is 150rpm.
  8. 8. The method of claim 1, wherein in the step S3, the amount of the aminosilane is 6.2% of the theoretical mass of the SiO 2 protective layer, and the aminosilane is diluted into 10% ethanol solution by absolute ethanol before the addition.
  9. 9. The method of preparing nano-sized copper-clad silver powder according to claim 1, wherein the wet cake is dispersed in cyclohexane in the step S4 with a dispersed solid content of 11%.
  10. 10. A nano-scale silver-coated copper powder, characterized by being prepared by the method for preparing the nano-scale silver-coated copper powder according to any one of claims 1 to 9.

Description

Preparation method of nanoscale silver-coated copper powder Technical Field The invention relates to the technical field of silver-coated copper powder, in particular to a preparation method of nanoscale silver-coated copper powder. Background The silver-coated copper powder is composite metal powder which takes copper powder as a core and uniformly coats a silver layer on the surface, has high conductivity of silver and economical efficiency of copper, and is a high cost performance material for replacing pure silver powder. The silver-based conductive material has excellent conductive performance, low resistivity of 0.015-0.025 ohm/square centimeter, high chemical stability, and capacity of preventing copper oxidation and maintaining long-term conductivity. The silver-coated copper powder has various shapes (such as sphere, particle, flake and dendritic) and controllable particle size (D50 range is 5-25 microns), and is suitable for different process requirements. The nano silver-coated copper powder is a micro-nano functional material, the size of the core copper particles is usually between submicron and tens of microns, and the external silver coating layer is nano-scale in thickness (tens of nanometers to hundreds of nanometers). The precise core-shell structure design has key application in a plurality of fields, namely, in the microelectronics field, the micron-sized overall size of the precise core-shell structure design and the nanometer-sized silver shell cooperate to form an ideal material for preparing high-performance and low-cost conductive paste and ink, and the precise core-shell structure design is used for electrodes of printed circuits, flexible electrons and solar cells; in the field of antibiosis, the nano silver surface can exert high-efficiency and durable antibiosis performance, and simultaneously, the copper core reduces cost, and is commonly used for medical instrument coatings and antibiosis plastics, and in the field of catalysts and 3D printing, the nano silver can also be used for manufacturing special catalysts and conductive composite materials by virtue of high specific surface area, high conductivity and oxidation resistance. At present, china patent with publication number of CN108080651A discloses a preparation method of nano silver-coated copper powder for electronic paste, which comprises the following steps of adding deionized water into a dispersing agent and a reducing agent to form a mixed solution, adjusting the mixed solution to be neutral by adding an alkaline solution, taking copper salt and deionized water to form a copper salt solution, adding a complexing agent to complex the copper salt solution to obtain a copper ammonia solution, dripping the copper ammonia solution into the mixed solution obtained in the step one to obtain a reducing solution, taking silver nitrate and deionized water to form a silver salt solution, adding the complexing agent to complex the silver ammonia solution, dripping the silver ammonia solution into the reducing solution, filtering the obtained solution, collecting filter residues, washing the filter residues with deionized water and absolute ethyl alcohol, and drying to obtain the nano silver-coated copper powder for electronic paste. In the invention, the preparation raw material components and the process steps are simple, the method is easy for large-scale production, harmless, pollution-free, efficient and environment-friendly, the obtained nano silver-coated copper powder has small resistivity and higher oxidation resistance, and the method accords with the electrical property and reduces the cost. However, including the above-mentioned patent technologies, agglomeration of nano-scale silver-coated copper powder is a core challenge in the preparation and application of the nano-scale silver-coated copper powder in the prior art. The nano particles have large specific surface area and high surface energy, and are easy to agglomerate. The agglomeration of the nano silver-coated copper powder can directly cause the problems of uneven coating, difficult dispersion, reduced performance, poor stability of subsequent sizing agent or ink and the like, and seriously affects the dispersibility and the performance of the final product. In order to solve the problems, the invention provides a preparation method of nano-scale silver-coated copper powder. Disclosure of Invention The invention aims to provide a preparation method of nanoscale silver-coated copper powder, which aims to solve the problems in the background technology. In order to solve the technical problems, the invention provides the following technical scheme: the preparation method of the nano-scale silver-coated copper powder comprises the following steps: S1, cleaning and modifying copper powder, selecting spherical or particle copper powder with a quantitative D50=500-700 nm under a nitrogen atmosphere, transferring the copper powder into a reaction container, adding