US 12,427,570 B2
Silver flake powder and production method thereof, and electrically conductive paste
Takuya Kojima, Saitama (JP)
Assigned to DOWA ELECTRONICS MATERIALS CO., LTD., Tokyo (JP)
Appl. No. 18/278,725
Filed by DOWA ELECTRONICS MATERIALS CO., LTD., Tokyo (JP)
PCT Filed Mar. 1, 2022, PCT No. PCT/JP2022/008687
§ 371(c)(1), (2) Date Aug. 24, 2023,
PCT Pub. No. WO2022/190968, PCT Pub. Date Sep. 15, 2022.
Claims priority of application No. 2021-036402 (JP), filed on Mar. 8, 2021; and application No. 2022-027369 (JP), filed on Feb. 25, 2022.
Prior Publication US 2024/0157436 A1, May 16, 2024
Int. Cl. B22F 1/068 (2022.01); B22F 1/05 (2022.01); B22F 9/04 (2006.01); H01B 1/22 (2006.01)
CPC B22F 1/068 (2022.01) [B22F 1/05 (2022.01); B22F 9/04 (2013.01); H01B 1/22 (2013.01); B22F 2009/042 (2013.01); B22F 2009/045 (2013.01); B22F 2301/255 (2013.01); B22F 2304/10 (2013.01)] 3 Claims
OG exemplary drawing
 
1. A flaky silver powder production method, comprising:
flaking by allowing a spherical silver powder to collide with media to flake the spherical silver powder to thereby obtain a flaky silver powder,
wherein the flaking is carried out in a manner that a ratio (V2/V1) of an average volume V2 to an average volume V1 is 1.0 to 1.5, where the average volume V1 is calculated according to the following equation 1 using a mean primary particle diameter (Dsem) in μm of the spherical silver powder as measured by a scanning electron microscope, and the average volume V2 is calculated according to the following equation 2 using a cumulative average major axis (L) in μm of the flaky silver powder, and a cumulative average thickness (T) in μm of the flaky silver powder:
V1=4/3×π×(Dsem/2)3  (Equation 1)
V2=T×π×(L/2)2  (Equation 2)
wherein a ratio [(D90−D10)/D50] of a difference between a cumulative 90th percentile particle diameter (D90) of the flaky silver powder and a cumulative 10th percentile particle diameter (D10) of the flaky silver powder to the cumulative 50th percentile particle diameter (D50) is 1.35 or less, where the cumulative 10th percentile particle diameter (D10) and the cumulative 90th percentile particle diameter (D90) are measured by laser diffraction or laser scattering particle size analysis,
wherein the flaky silver powder has a tapped density of from 0.8 g/mL to 1.9 g/mL, and
wherein a cumulative 50th percentile particle diameter (D50) in μm of the spherical silver powder as measured by laser diffraction or laser scattering particle size analysis is from 1 μm to 2.5 μm.