Abstract: Provided is a flux for resin-cored solder that is used in resin-cored solder that is supplied into a through hole formed along a central axis of a soldering iron. The flux includes 60% by mass to 99.9% by mass of a rosin ester to a total mass of the flux, 0.1% by mass to 15% by mass of a covalent halogen compound to the total mass of the flux, and more than 0% by mass to 10% by mass of rosin amine, N,N-diethyloctylamine, or rosin amine and N,N-diethyloctylamine to the total mass of the flux.

Abstract: A method for manufacturing a soldered product by soldering a solder object portion, including: a solder supplying step that causes a cylindrical soldering iron having a through hole to contact with the solder object portion to supply a thread solder piece to the solder object portion from the through hole; a heating step that heats the thread solder piece with the cylindrical soldering iron and causes to melt the thread solder piece at the solder object portion; and a curing step that cures a melting object of the thread solder piece to solder the solder object portion. The thread solder piece is composed of a core containing a flux and a coating member containing a solder alloy that covers the core. The flux has a rosin having an acid value which is substantially as a main component thereof.

Abstract: Provided are flux for resin flux cored solder, flux for flux-coated solder, resin flux cored solder using the flux for resin flux cored solder, flux-coated solder using the flux for flux-coated solder, and a soldering method, which have low residue and are excellent in processability. The flux for resin flux cored solder or flux-coated solder contains a solid solvent in an amount of 70 wt % or more and 99.5 wt % or less, and an activator in an amount of 0.5 wt % or more and 30 wt % or less.

Abstract: Provided are flux for resin flux cored solder, flux for flux-coated solder, resin flux cored solder using the flux for resin flux cored solder, flux-coated solder using the flux for flux-coated solder, and a soldering method, which have low residue and are excellent in processability. The flux for resin flux cored solder or flux-coated solder contains a solid solvent in an amount of 70 wt % or more and 99.5 wt % or less, and an activator in an amount of 0.5 wt % or more and 30 wt % or less.

Abstract: Provided is flux for resin flux cored solder using in a soldering method in which the resin flux cored solder is supplied into a through hole formed along a central axis of a soldering iron. The flux contains volatile rosin in an amount of 70 wt % or more and 98 wt % or less, non-volatile rosin in an amount of 0 wt % or more and 10% or less, and an activator in an amount of 2 wt % or more and 30 wt % or less, the activator including an organic acid in an amount of 0 wt % or more and 15 wt % or less, an organohalogen compound in an amount of 0.5 wt % and 15 wt % or less, an amine in an amount of 0 wt % or more and 5 wt % or less, and an amine hydrohalide salt in an amount of 0 wt % or more and 2.5 wt % or less.