	US 12,454,030 B2
	Solder composition and method for manufacturing flexible circuit board
Sumire Tanaka, Iruma (JP); Yurika Munekawa, Iruma (JP); and Daigo Ichikawa, Iruma (JP)
Assigned to TAMURA CORPORATION, Tokyo (JP)
Filed by TAMURA CORPORATION, Tokyo (JP)
Filed on Sep. 12, 2022, as Appl. No. 17/942,506.
Claims priority of application No. 2021-150920 (JP), filed on Sep. 16, 2021.
Prior Publication US 2023/0100601 A1, Mar. 30, 2023
Int. Cl. B23K 35/362 (2006.01); B23K 35/36 (2006.01); B23K 101/42 (2006.01); H05K 1/02 (2006.01); H05K 1/11 (2006.01); H05K 3/34 (2006.01)

CPC B23K 35/362 (2013.01) [B23K 35/3613 (2013.01); B23K 35/3618 (2013.01); H05K 1/028 (2013.01); H05K 1/118 (2013.01); H05K 3/3463 (2013.01); B23K 2101/42 (2018.08); H05K 2203/0571 (2013.01)]

10 Claims

1. A solder composition comprising:

a flux composition comprising an (A) rosin resin, a (B) activator, a (C) thixotropic agent, and a (D) solvent; and

(E) solder powder, wherein

the (B) component comprises a (B1) dicarboxylic acid having 3 to 8 carbon atoms,

the (C) component comprises at least one selected from the group consisting of a (C1) amide thixotropic agent having a hydroxy group in one molecule and a (C2) glycerol thixotropic agent having a hydroxy group in one molecule, and

the solder composition satisfies a condition represented by Numerical Formula (F1) below provided that a total of contents of the (C1) component and the (C2) component is defined as X and a content of the (B1) component is defined as Y,

X/2≤Y≤5X (F1).