An object of the present invention is to provide a flux which does not precipitate a crystal and can improve solder wettability.

A flux comprising 0.4 to 10.0 mass % of ditolylguanidine and 1.0 to 10.0 mass % of an organic acid, and not comprising diphenylguanidine as an amine compound.

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.

Compositions and methods for coupling metals to aluminum surfaces are provided. The compositions are prepared as aqueous solutions or suspensions, and can be applied to the aluminum surface using conventional printing techniques. Rheology of the printable composition can be adjusted to provide a gel or a cream. Curing steps, if necessary, are performed at low temperatures that are compatible with plastic/polymer components of mass produced devices, such as aluminum RFID antennae.

A cleaning flux contains as a solvent 60-98% by weight of one or both of an alkylene oxide-resorcinol copolymer and an ethylene oxide-propylene oxide condensation-added alkylene diamine. An addition amount of the alkylene oxide-resorcinol copolymer is within a range of 0-98% by weight and the addition amount of the ethylene oxide-propylene oxide condensation-added alkylene diamine is within the range of 0-98% by weight. The cleaning flux further includes one or both of an organic acid and a halogen compound. The addition amount of the organic acid is within the range of 0-18% by weight and the addition amount of the halogen compound is within the range of 0-4% by weight.

A solder composition contains: flux composition containing (A) rosin-based resin, (B) activator, and (C) solvent; and (D): solder powder with a melting point of 200 to 250 degrees C. The component (A) contains (A1) rosin-based resin with a softening point of 120 degrees C. or more and an acid number of 220 mgKOH/g or more and (A2) rosin-based resin with a softening point of 100 degrees C. or less and an acid number of 20 mgKOH/g or less. The component (C) contains (C1) hexanediol solvent with a melting point of 40 degrees C. or more and a boiling point of 220 degrees C. or less and (C2) solvent with a viscosity of 10 mPa.Math.s or less at 20 degrees C. and a boiling point of 270 degrees C. or more. A content of the component (A1) ranges from 15 to 25 mass % with respect to the flux composition (100 mass %).

Provided is a flux containing not less than 11.0 degrees and not more than 17.0 of a contact angle between the flux and a resist substrate on which the flux has been printed to have 1.0 mm of a diameter and 0.15 mm of a thickness when heating the resist substrate at 150 degrees C. for 30 seconds and cooling the resist substrate to a room temperature. The flux also contains more than zero seconds and not more than 2.0 seconds of a zero-cross time when heating a Cu plate at 150 degrees C. in a thermostat oven for 12 hours, applying the flux onto the baked Cu plate, and dipping the baked Cu plate onto which the flux is applied into a Sn-3.0Ag-0.5Cu alloy at a dipping speed of 15 mm/sec and by 2.0 mm of a dipped depth.

A brazing material for brazing aluminum or an aluminum alloy includes fluoride-based flux, a solidifying agent, and an organic viscosity reducing agent and is solid at 25? C.

A solder alloy substantially consists of tin, silver, indium, bismuth, and antimony. With respect to the total amount of the solder alloy, the content ratio of the silver is 2.8 mass % or more and 4 mass % or less; the content ratio of the indium is 6.2 mass % or more and 9.0 mass % or less; the content ratio of the bismuth is 0.7 mass % or more and 5.0 mass % or less; the content ratio of the antimony is 0.3 mass % or more and 5.0 mass % or less; and the content ratio of the tin is the remaining ratio and the value of A is 4.36 or less wherein A=0.87[In content ratio (mass %)]0.41[Ag content ratio (mass %)]0.82[Sb content ratio (mass %)].

A solder alloy is a tin-silver-copper solder alloy substantially consisting of tin, silver, copper, bismuth, nickel, cobalt, and indium. With respect to the total amount of the solder alloy, the content ratio of the silver is 2 mass % or more and 5 mass % or less; the content ratio of the copper is 0.1 mass % or more and 1 mass % or less; the content ratio of the bismuth is 0.5 mass % or more and 4.8 mass % or less; the content ratio of the nickel is 0.01 mass % or more and 0.15 mass % or less; the content ratio of the cobalt is 0.001 mass % or more and 0.008 mass % or less; the content ratio of the indium is above 6.2 mass % and 10 mass % or less; and the content ratio of the tin is the remaining ratio.

Provided is a flux activator containing a halogen compound represented by formula 1 below:

##STR00001##

where X.sup.1 and X.sup.2 represent different halogen atoms, R.sup.1 and R.sup.2 are each a group represented by any one of formulas OH, OR.sup.3, OC(O)R.sup.4, and OC(O)NHR.sup.5, R.sup.1 and R.sup.2 optionally represent the same group or different groups, R.sup.3, R.sup.4, and R.sup.5 are each an aromatic hydrocarbon group having 1 to 18 carbon atoms or an aliphatic hydrocarbon group having 1 to 18 carbon atoms, and R.sup.3, R.sup.4, and R.sup.5 optionally represent the same group or different groups.