	US 12,233,484 B2
	Flux and solder paste
Ryuji Ukai, Tokyo (JP); Kazuya Kitazawa, Tokyo (JP); Hiroaki Kawamata, Tokyo (JP); Shinji Kikuchi, Tokyo (JP); and Keisuke Shinozaki, Tokyo (JP)
Assigned to Senju Metal Industry Co., Ltd., Tokyo (JP)
Appl. No. 17/914,495
Filed by Senju Metal Industry Co., Ltd., Tokyo (JP)
PCT Filed Mar. 25, 2021, PCT No. PCT/JP2021/012462 § 371(c)(1), (2) Date Sep. 26, 2022, PCT Pub. No. WO2021/193797, PCT Pub. Date Sep. 30, 2021.
Claims priority of application No. 2020-058267 (JP), filed on Mar. 27, 2020.
Prior Publication US 2023/0122883 A1, Apr. 20, 2023
Int. Cl. B23K 35/362 (2006.01); B23K 35/02 (2006.01); B23K 35/36 (2006.01)

CPC B23K 35/362 (2013.01) [B23K 35/025 (2013.01); B23K 35/3612 (2013.01); B23K 35/3613 (2013.01)]

13 Claims

1. A flux for a solder paste comprising: rosin; an activator; and a solvent,

wherein the solvent includes a monoalkylene glycol-based solvent and a solid solvent that is solid at 20° C.,

wherein a total content of the monoalkylene glycol-based solvent and the solid solvent ranges from 40% by mass to 60% by mass with a total amount of the flux as 100%,

wherein a content of the solid solvent ranges from 5% by mass to 25% by mass with the total amount of the flux as 100%,

wherein a content of the rosin ranges from 38% by mass to 50% by mass with the total amount of the flux as 100%, and

wherein the solid solvent is selected from the group consisting of: 2,5-dimethyl-2,5-hexanediol, dioxane glycol, 2,5-dimethyl-3-hexyne-2,5-diol, 2,3-dimethyl-2,3-butanediol, 2,2′-oxybis(methylene)bis(2-ethyl-1,3-propanediol), 2,2-bis(hydroxymethyl)-1,3-propanediol, 1,1,1-tris(hydroxymethyl) propane, and combinations thereof.