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CN-122025283-A - Method for regulating and controlling conductivity of silver-coated copper paste, preparation method and application of silver-coated copper paste

CN122025283ACN 122025283 ACN122025283 ACN 122025283ACN-122025283-A

Abstract

The invention belongs to the field of conductive paste, and relates to a method for regulating and controlling the conductivity of silver-coated copper paste, a preparation method of silver-coated copper paste and application thereof; the method comprises the steps of mixing silver-coated copper powder with resin, an organic solvent and an auxiliary agent to prepare corresponding silver-coated copper paste, carrying out screen printing on the silver-coated copper paste on a PET plate, solidifying the silver-coated copper paste to obtain corresponding printed conducting strips, carrying out volume resistivity test on the solidified printed conducting strips, and determining that the number density of surface salient points of the silver-coated copper powder is in inverse proportion to the volume resistivity, thereby determining that the number density of the surface salient points of the silver-coated copper powder is positively correlated to the conductivity, and selecting the silver-coated copper powder with the corresponding number density of salient points according to the volume resistivity requirement of preset silver-coated copper paste. In the method, the silver-coated copper paste preparation method and the application thereof, the preparation and the application of the low-cost conductive material are realized by regulating and controlling the number of the salient points on the surface of the silver-coated copper powder.

Inventors

  • LI MINGGANG
  • PENG YIFAN
  • WANG LIYE
  • FAN YIJING
  • LIU FANGYANG

Assignees

  • 中南大学

Dates

Publication Date
20260512
Application Date
20260407

Claims (10)

  1. 1. The method for regulating and controlling the conductivity of the silver-coated copper paste is characterized by comprising the following steps of: Providing at least three silver-coated copper powders with different surface bump number densities; mixing the silver-coated copper powder with resin, an organic solvent and an auxiliary agent to prepare corresponding silver-coated copper paste, wherein the silver-coated copper paste does not contain nano silver powder; Carrying out screen printing on the silver-coated copper paste on a PET plate, and then solidifying to obtain a corresponding printed conducting strip; the volume resistivity test is carried out on the cured printed conductive strip, and the result shows that the number density of the surface salient points of the silver-coated copper powder is inversely proportional to the volume resistivity, so that the number density of the surface salient points of the silver-coated copper powder is determined to be positively related to the conductivity; And selecting silver-coated copper powder with corresponding surface bump number density according to the volume resistivity requirement of preset silver-coated copper slurry.
  2. 2. The method of claim 1, wherein the silver-coated copper powder is divided into at least three according to the number density of the surface bumps of the silver-coated copper powder: The first silver-coated copper powder has the number density of the surface salient points less than or equal to 0.40/mu m < 2 >; the second silver-coated copper powder is 0.40/mum < 2 > and the number density of the surface convex points is less than or equal to 1.19/mum < 2 >; and the number density of the surface salient points of the third silver coated copper powder is more than 1.19/mum < 2 >.
  3. 3. The method according to claim 2, wherein in the preparation of the silver-coated copper powder, copper powder is provided, deionized water, a silver powder dispersing agent and a silver ion complexing agent are added, a silver nitrate solution is added dropwise, and the number density of the surface bumps of the silver-coated copper powder is controlled by the dropping speed.
  4. 4. The method according to claim 2, wherein the silver-coated copper powder is spherical, the particle diameter D50 is 3.0-6.0 μm, the silver content is 5-40%, and the mass fraction of the silver-coated copper powder in the silver-coated copper paste is 70-90%.
  5. 5. A method according to claim 3, wherein the third silver-coated copper powder is selected as a silver-coated copper paste for use in the preparation of photovoltaic cell grids.
  6. 6. The method of claim 1, wherein the mixing comprises the steps of: (1) Mixing resin and an organic solvent, and pre-stirring to obtain a first mixture; (2) Adding an auxiliary agent into the first mixture, and carrying out secondary pre-stirring to obtain a second mixture; (3) And adding the silver-coated copper powder into the second mixture, and carrying out main stirring to obtain silver-coated copper slurry.
  7. 7. The method of claim 6, wherein the silver-coated copper paste comprises the following components in mass fraction: 70% -90% of silver-coated copper powder; 0.5 to 2.0 percent of resin; 0.5% -2% of ethyl cellulose; 0.2% -1% of fumed silica, and the particle size is 15-30 nm; 0.42 to 1.3 percent of auxiliary agent; 10-15% of organic solvent. The resin is at least one of epoxy resin or organic silicon resin; the auxiliary agent comprises 0.2 to 0.6 percent of BYK-141 defoamer, 0.2 to 0.6 percent of BYK-161 dispersant and 0.02 to 0.1 percent of BYK-306 flatting agent; the organic solvent consists of the following components: 3 to 6 percent of diethylene glycol butyl ether acetate, 1 to 3 percent of tributyl citrate, 1 to 4 percent of terpineol and 1 to 3 percent of dibutyl phthalate.
  8. 8. The method of claim 1, wherein the curing temperature is 80 ℃ to 200 ℃ and the curing time is 5min to 30min, the printing is screen printing, and the width of the printed conductive strips is 0.02mm to 2mm.
  9. 9. The preparation method of the silver-coated copper paste is characterized by comprising the following steps of: determining the volume resistivity required by the target silver-coated copper paste; determining the number density of the salient points on the surface of the target silver-coated copper powder corresponding to the target silver-coated copper slurry by adopting the method of any one of claims 1-8; and mixing the target silver-coated copper powder with resin, an organic solvent and an auxiliary agent to prepare the target silver-coated copper slurry.
  10. 10. Use of the method of claims 1-8 or the method of preparation of silver-coated copper paste of claim 9 in the field of photovoltaic cells, flexible electronics or semiconductor packaging.

Description

Method for regulating and controlling conductivity of silver-coated copper paste, preparation method and application of silver-coated copper paste Technical Field The invention belongs to the field of conductive paste, and relates to a method for regulating and controlling conductivity of silver-coated copper paste, a preparation method of silver-coated copper paste and application of silver-coated copper paste. Background The demand for conductive silver paste in the fields of photovoltaic cells, flexible electronics, semiconductor packaging and the like continues to grow. The conductive silver paste is a core material for realizing conductivity in the device, and the conductivity of the conductive silver paste directly determines the working performance of the device. However, silver powder of the current commercial conductive silver paste accounts for up to 85% to 93%, and silver is used as a noble metal, so that the price is high for a long time, the production cost of related devices is greatly increased, and the large-scale application and sustainable development of related industry are severely restricted. Therefore, development of silver powder substitute materials with high performance and low cost becomes one of industrial research hotspots. Silver-coated copper powder is considered as an ideal substitute material for silver powder in conductive silver paste because of the low cost of copper and the high conductivity and oxidation resistance of a silver coating. Silver coated copper pastes are typically used after curing at temperatures below 200 degrees celsius. How to control the conductivity of the silver-coated copper paste to meet the requirements in different application scenes is a key technical problem in industry. The existing regulation and control means mainly focus on strategies such as a mode of regulating and optimizing a slurry formula (such as regulating a resin and dispersing agent proportion) or a mode of compounding micro-nano silver powder (such as adding 100-300 nm silver powder), in order to improve conductivity, a mode of adding the micro-nano silver powder is generally adopted, and the nano silver powder can fill gaps of the micro-silver coated copper powder, so that the conductivity is improved, but the cost is too high. For example, chinese patent application publication No. CN121182450A discloses a high-performance conductive adhesive doped with conductive nano particles, which comprises, by weight, 50-100 parts of vinyl liquid silicone rubber, 100-400 parts of modified silver-coated copper powder, 1-10 parts of nano silver powder, 1-10 parts of epoxy silane modified prepolymer, 3-30 parts of hydrogen-containing silicone oil, 0.1-5 parts of platinum catalyst and 0.05-1 part of inhibitor. Disclosure of Invention The invention aims to solve the problem that the conductive silver paste in the prior art cannot achieve both conductivity and cost, and save the silver consumption, and provides a method for regulating and controlling the conductivity of the silver-coated copper paste, a preparation method of the silver-coated copper paste and application thereof, wherein the method is low in cost by regulating and controlling the number of salient points on the surface of the silver-coated copper powder. In order to achieve the above object, a first aspect of the present application provides a method for controlling conductivity of silver-coated copper paste, comprising: Providing at least three silver-coated copper powders with different surface bump number densities; mixing the silver-coated copper powder with resin, an organic solvent and an auxiliary agent to prepare corresponding silver-coated copper paste, wherein the silver-coated copper paste does not contain nano silver powder; Carrying out screen printing on the silver-coated copper paste on a PET plate, and then solidifying to obtain a corresponding printed conducting strip; the volume resistivity test is carried out on the cured printed conductive strip, and the result shows that the number density of the surface salient points of the silver-coated copper powder is inversely proportional to the volume resistivity, so that the number density of the surface salient points of the silver-coated copper powder is determined to be positively related to the conductivity; And selecting silver-coated copper powder with corresponding surface bump number density according to the volume resistivity requirement of preset silver-coated copper slurry. In one embodiment, the silver-coated copper powder is divided into at least the following three types according to the number density of the surface bumps of the silver-coated copper powder: The first silver-coated copper powder has the number density of the surface salient points less than or equal to 0.40/mu m < 2 >; the second silver-coated copper powder is 0.40/mum < 2 > and the number density of the surface convex points is less than or equal to 1.19/mum < 2 >; and the number dens