Flux, resin flux cored solder using the flux, and soldering method

A flux for resin flux cored solder, the flux comprising:

• 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 wt % 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 % or more 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,
• wherein the organic acid is at least one compound selected from the group consisting of:
• glutaric acid, adipic acid, pimelic acid, azelaic acid, eicosane diacid, citric acid, glycolic acid, succinic acid, salicylic acid, diglycolic acid, dipicolinic acid, dibutyl aniline diglycolic acid, suberic acid, sebacic acid, thioglycol acid, phthalic acid, isophthalic acid, terephthalic acid, dodecanedioic acid, parahydroxyphenylacetic acid, picolinic acid, phenylsuccinic acid, fumaric acid, maleic acid, malonic acid, lauric acid, benzoic acid, tartaric acid, tris(2-carboxyethyl)isocyanurate, glycine, 1,3-cyclohexanedicarboxylic acid, 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butanoic acid, 4-tert-butyl benzoic acid, 2,3-dihydroxybenzoic acid, 2,4-diethyl glutaric acid, 2-quinolinecarboxylic acid, 3-hydroxybenzoic acid, malic acid, p-anisic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, oleic acid, linoleic acid, linolenic acid, a first dimer acid which is a reactant of oleic acid and linoleic acid, a first trimer acid which is a reactant of oleic acid and linoleic acid, a first hydrogenated dimer acid that is obtained by adding hydrogen to the first dimer acid, a first hydrogenated trimer acid that is obtained by adding hydrogen to the first trimer acid, a second dimer acid which is a reactant of acrylic acid, a second trimer acid which is a reactant of acrylic acid, a second hydrogenated dimer acid that is obtained by adding hydrogen to the second dimer acid, a second hydrogenated trimer acid that is obtained by adding hydrogen to the second trimer acid, a third dimer acid which is a reactant of methacrylic acid, a third trimer acid which is a reactant of methacrylic acid, a third hydrogenated dimer acid that is obtained by adding hydrogen to the third dimer acid, a third hydrogenated trimer acid that is obtained by adding hydrogen to the third trimer acid, a fourth dimer acid which is a reactant of acrylic acid and methacrylic acid, a fourth trimer acid which is a reactant of acrylic acid and methacrylic acid, a fourth hydrogenated dimer acid that is obtained by adding hydrogen to the fourth dimer acid, a fourth hydrogenated trimer acid that is obtained by adding hydrogen to the fourth trimer acid, a fifth dimer acid which is a reactant of oleic acid, a fifth trimer acid which is a reactant of oleic acid, a fifth hydrogenated dimer acid that is obtained by adding hydrogen to the fifth dimer acid, a fifth hydrogenated trimer acid that is obtained by adding hydrogen to the fifth trimer acid, a sixth dimer acid which is a reactant of linoleic acid, a sixth trimer acid which is a reactant of linoleic acid, a sixth hydrogenated dimer acid that is obtained by adding hydrogen to the sixth dimer acid, a sixth hydrogenated trimer acid that is obtained by adding hydrogen to the sixth trimer acid, a seventh dimer acid which is a reactant of linolenic acid, a seventh trimer acid which is a reactant of linolenic acid, a seventh hydrogenated dimer acid that is obtained by adding hydrogen to the seventh dimer acid, a seventh hydrogenated trimer acid that is obtained by adding hydrogen to the seventh trimer acid, an eighth dimer acid which is a reactant of acrylic acid and oleic acid, an eighth trimer acid which is a reactant of acrylic acid and oleic acid, an eighth hydrogenated dimer acid that is obtained by adding hydrogen to the eighth dimer acid, an eighth hydrogenated trimer acid that is obtained by adding hydrogen to the eighth trimer acid, a ninth dimer acid which is a reactant of acrylic acid and linoleic acid, a ninth trimer acid which is a reactant of acrylic acid and linoleic acid, a ninth hydrogenated dimer acid that is obtained by adding hydrogen to the ninth dimer acid, a ninth hydrogenated trimer acid that is obtained by adding hydrogen to the ninth trimer acid, a tenth dimer acid which is a reactant of acrylic acid and linolenic acid, a tenth trimer acid which is a reactant of acrylic acid and linolenic acid, a tenth hydrogenated dimer acid that is obtained by adding hydrogen to the tenth dimer acid, a tenth hydrogenated trimer acid that is obtained by adding hydrogen to the tenth trimer acid, an eleventh dimer acid which is a reactant of methacrylic acid and oleic acid, an eleventh trimer acid which is a reactant of methacrylic acid and oleic acid, an eleventh hydrogenated dimer acid that is obtained by adding hydrogen to the eleventh dimer acid, an eleventh hydrogenated trimer acid that is obtained by adding hydrogen to the eleventh trimer acid, a twelfth dimer acid which is a reactant of methacrylic acid and linoleic acid, a twelfth trimer acid which is a reactant of methacrylic acid and linoleic acid, a twelfth hydrogenated dimer acid that is obtained by adding hydrogen to the twelfth dimer acid, a twelfth hydrogenated trimer acid that is obtained by adding hydrogen to the twelfth trimer acid, a thirteenth dimer acid which is a reactant of methacrylic acid and linolenic acid, a thirteenth trimer acid which is a reactant of methacrylic acid and linolenic acid, a thirteenth hydrogenated dimer acid that is obtained by adding hydrogen to the thirteenth dimer acid, a thirteenth hydrogenated trimer acid that is obtained by adding hydrogen to the thirteenth trimer acid, a fourteenth dimer acid which is a reactant of oleic acid and linolenic acid, a fourteenth trimer acid which is a reactant of oleic acid and linolenic acid, a fourteenth hydrogenated dimer acid that is obtained by adding hydrogen to the fourteenth dimer acid, a fourteenth hydrogenated trimer acid that is obtained by adding hydrogen to the fourteenth trimer acid, a fifteenth dimer acid which is a reactant of linoleic acid and linolenic acid, a fifteenth trimer acid which is a reactant of linoleic acid and linolenic acid, a fifteenth hydrogenated dimer acid that is obtained by adding hydrogen to the fifteenth dimer acid, a fifteenth hydrogenated trimer acid that is obtained by adding hydrogen to the fifteenth trimer acid,
• wherein the organohalogen compound is at least one compound selected from the group consisting of:
• trans-2,3-dibromo-1,4-butenediol, triallyl isocyanurate hexabromide, 1-bromo-2-butanol, 1-bromo-2-propanol, 3-bromo-1-propanol, 3-bromo-1,2-propanediol, 1,4-dibromo-2-butanol, 1,3-dibromo-2-propanol, 2,3-dibromo-1-propanol, 2,3-dibromo-1,4-butanediol, 2,3-dibromo-2-butene-1,4-diol, trans-2,3-dibromo-2-butene-1,4-diol, cis-2,3-dibromo-2-butene-1,4-diol, 2,2-bis(bromomethyl)-1,3-propanediol, tetrabromoethane, tetrabromobutane, 2,2,2-tribromoethanol, choroalkane, chlorinated fatty acid ester, HET acid, HET acid nonhydrate, fluorochemical surfactant, surfactant including a perfluoroalkyl group, and polytetrafluoroethylene,
• wherein when 10 mg of the flux is filled in an aluminum pan and heated from 25 degrees C. to 350 degrees C. at a temperature rising rate of 10 degrees C./min under N2 atmosphere, a weight of the flux after heating is 20% or less of a weight of the flux before heating,
• wherein when the flux is used to form a resin flux cored solder having a composition of Sn-3Ag-0.5Cu, a diameter of 0.8 mm, and containing solder in an amount of 97 wt % and the flux in an amount of 3 wt %, a wet spreading rate calculated according to JIS Z 3197 8.3.1.1 of the resin flux cored solder is 70% or more, and
• wherein the flux exhibits a transmittance of 50% or less in a corrosion test using a copper mirror based on JIS Z 3197.