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CN-117505874-B - Flake self-assembled spherical silver powder and preparation method thereof

CN117505874BCN 117505874 BCN117505874 BCN 117505874BCN-117505874-B

Abstract

The invention provides a flaky self-assembled spherical silver powder and a preparation method thereof, belonging to the technical field of conductive fillers, wherein the preparation method comprises the steps of preparing 0.65-1.5 mol/L of sulfate solution and 1.70-2.70 mol/L of silver nitrate solution; the method comprises the steps of adding a sulfate solution with the volume ratio of 2-6:1 into a reaction container, stirring and keeping the temperature at 25-100 ℃, adding a silver nitrate solution with the volume ratio of 45-55%, reacting for 3-7 minutes, simultaneously dropwise adding the rest sulfate solution with the volume ratio of 30-40% and the silver nitrate solution with the volume ratio of 45-55% into the reaction container in a stirring state, continuously stirring, and then sequentially separating, washing and drying to obtain the flaky self-assembled spherical silver powder. The flaky self-assembled spherical silver powder has the advantages of large specific surface area, low tap density and high sphericity, and is suitable for low-temperature sintering slurry.

Inventors

  • MA YAN
  • ZHENG WEI
  • LIU FANG
  • HA MIN
  • WANG JUN
  • MI XIXUE
  • CHEN XUEGANG
  • ZHANG XINHUI
  • MA XIAO

Assignees

  • 宁夏中色新材料有限公司

Dates

Publication Date
20260512
Application Date
20231121

Claims (7)

  1. 1. The preparation method of the flaky self-assembled spherical silver powder is characterized by comprising the following steps of: S1, preparing 0.65-1.5 mol/L of sulfate solution and 1.70-2.70 mol/L of silver nitrate solution; the volume ratio of the sulfate solution to the silver nitrate solution is 2-6:1; In the step S1, the sulfate in the sulfate solution is one or a mixture of more than two of ferrous ammonium sulfate, ferrous sulfate or hydroxylamine sulfate; S2, adding 60-70% by volume of sulfate solution into a reaction container, stirring and keeping the temperature at 25-100 ℃, adding 45-55% by volume of silver nitrate solution, and reacting for 3-7 minutes; Step S3, in a stirring state, simultaneously dropwise adding the rest 30-40% by volume of sulfate solution and 45-55% by volume of silver nitrate solution into a reaction container, continuously stirring, and then sequentially separating, washing and drying to obtain flaky self-assembled spherical silver powder; in the step S3, the dropping speed of the silver nitrate solution is greater than or equal to the dropping speed of the sulfate solution; In the step S3, a conduit is adopted in the dropwise adding mode of the silver nitrate solution, and the conduit extends below the liquid level along the wall of the reaction container; the sulfate solution is added dropwise by using a conduit and maintained above the liquid level along the wall of the reaction vessel.
  2. 2. The preparation method according to claim 1, wherein in the step S1, the volume ratio of the sulfate solution to the silver nitrate solution is 3-4:1.
  3. 3. The method according to claim 2, wherein in the step S2, the temperature is 50 to 75 ℃.
  4. 4. The preparation method according to claim 3, wherein in the step S3, the dropping speed of the silver nitrate solution is 50-80 ml/min; the dropping speed of the sulfate solution is 50-70 ml/min.
  5. 5. The method according to claim 4, wherein in the step S3, the stirring reaction time is 7 to 12 minutes.
  6. 6. A plate-shaped self-assembled spherical silver powder, characterized in that the plate-shaped self-assembled spherical silver powder is prepared by the preparation method according to any one of claims 1 to 5.
  7. 7. The plate-like self-assembled spherical silver powder according to claim 6, wherein the specific surface area of the plate-like self-assembled spherical silver powder is >11m 2 /g, tap density is <1.2g/cm 3 , average particle diameter is 1.88-2.53 μm, apparent density is 0.55-0.64 g/cm 3 , and burn-out value at 530 ℃ is 0.05-0.07%.

Description

Flake self-assembled spherical silver powder and preparation method thereof Technical Field The invention belongs to the technical field of conductive fillers, and particularly relates to flaky self-assembled spherical silver powder and a preparation method thereof. Background Silver powder is widely used as an excellent conductive filler in the fields of energy, microelectronics and the like. Silver powder is used as a main component of the electronic paste, and the morphology, the particle size distribution, the dispersibility, the tap density and the like of the silver powder have important influences on the performance of the silver paste. Silver powder with different technical indexes has different purposes, such as spherical silver powder with high tap density is often used for preparing silver paste with high silver content, and flake silver powder with low apparent density is often used for preparing film paste with low silver content. Compared with flake silver powder, the spherical silver powder has good fluidity in the slurry, and can ensure that the slurry has good printability. The flake silver powder has a larger specific surface area than the spherical silver powder, and can be sintered at a lower temperature to form a dense silver layer. Therefore, how to prepare silver powder with low-temperature sintering characteristics and good fluidity is a technical problem to be solved. Disclosure of Invention One of the purposes of the invention is to provide a preparation method of flaky self-assembled spherical silver powder, which can obtain flaky self-assembled spherical silver powder with large specific surface area, low tap density and high sphericity and is suitable for low-temperature sintering slurry. The second object of the present invention is to provide a plate-like self-assembled spherical silver powder. In order to achieve one of the above purposes, the present invention is implemented by the following technical scheme: A method for preparing flaky self-assembled spherical silver powder, comprising the following steps: s1, preparing a sulfate solution with the volume ratio of 0.65-1.5 mol/L and a silver nitrate solution with the volume ratio of 1.70-2.70 mol/L, wherein the volume ratio of the sulfate solution to the silver nitrate solution is 2-6:1; S2, adding 60-70% by volume of sulfate solution into a reaction container, stirring and keeping the temperature at 25-100 ℃, adding 45-55% by volume of silver nitrate solution, and reacting for 3-7 minutes; and step S3, in a stirring state, simultaneously dropwise adding the rest 30-40% by volume of sulfate solution and 45-55% by volume of silver nitrate solution into a reaction container, continuously stirring, and then sequentially separating, washing and drying to obtain the flaky self-assembled spherical silver powder. The invention adopts two-step reaction, and through the one-step dumping reaction (namely the reaction between the sulfate solution and the silver nitrate solution in the step S2), the monodisperse submicron-level flaky self-assembled spherical silver powder can be rapidly obtained; according to the invention, through the simultaneous dropwise addition mode change of the reaction of the second step (namely the reaction between the sulfate solution and the silver nitrate solution in the step S3), the reaction product between the sulfate solution and the silver nitrate solution in the step S3 is ensured to grow in situ on the surface of the submicron silver powder generated in the step S2 and slowly grow towards the direction of flaky growth, so that the specific surface area of the obtained flaky self-assembled spherical silver powder is ensured to be large, the sintering temperature is low, the phenomenon that the silver atoms generated later in the reaction process only after the one-time dumping reaction are reduced along with the concentration of the silver nitrate is avoided, the reaction power is weakened, and the silver atoms generated later are deposited and grown towards the direction of reducing the surface energy of the silver powder, so that the compact spherical silver powder instead of the flaky self-assembled spherical silver powder is obtained. Further, in the step S1, the volume ratio of the sulfate solution to the silver nitrate solution is 3-4:1. Further, in the step S1, the sulfate in the sulfate solution is one or more of ferrous ammonium sulfate, ferrous sulfate, and hydroxylamine sulfate. Further, in the step S2, the temperature is 50 to 75 ℃. Further, in the step S3, the dropping speed of the silver nitrate solution is greater than or equal to the dropping speed of the sulfate solution. According to the invention, by controlling the dropping speed of the silver nitrate solution and the sulfate solution, the high-concentration silver nitrate is ensured to be dropped faster, so that the Ag + in the base solution can keep a certain concentration, and the submicron flaky self-assembled spherical silver