Abstract: A solder powder comprises solder particles having a distribution such that the number of particles having a particle diameter of 20 ?m or less is 30% or less, wherein the oxygen content is 500 ppm or less. A flux for solder paste comprises an organic acid component consisting of an organic acid ester and an ester decomposer catalyst, an organic halogen compound, a reducing agent and a resin component. A solder paste mainly comprises a flux and a solder powder, wherein the water content of the solder paste is 0.5% by weight or less.

Abstract: A solder powder comprises solder particles having a distribution such that the number of particles having a particle diameter of 20 &mgr;m or less is 30% or less, wherein the oxygen content is 500 ppm or less. A flux for solder paste comprises an organic acid component consisting of an organic acid ester and an ester decomposer catalyst, an organic halogen compound, a reducing agent and a resin component. A solder paste mainly comprises a flux and a solder powder, wherein the water content of the solder paste is 0.5% by weight or less.

Abstract: A solder powder comprises solder particles having a distribution such that the number of particles having a particle diameter of 20 &mgr;m or less is 30% or less, wherein the oxygen content is 500 ppm or less. A flux for solder paste comprises an organic acid component consisting of an organic acid ester and an ester decomposer catalyst, an organic halogen compound, a reducing agent and a resin component. A solder paste mainly comprises a flux and a solder powder, wherein the water content of the solder paste is 0.5% by weight or less.

Abstract: A composition comprising metal oxide particles having photo-catalytic activity, a solvent-soluble zirconium compound and a solvent. Preferably, the metal oxide particles having photocatalytic activity are titanium oxide particles; the metal oxide particles have an average particle diameter of about 0.005 to 0.3 &mgr;m; and the amount of the zirconium compound is in the range of about 3-200 parts by weight, as ZrO2, per 100 parts by weight of the metal oxide articles. A composite of a film having a photo-catalytic activity with a base material is made by coating the base material with the above composition to form a film, and curing the film on the base material.

Abstract: To provide a solder paste having excellent storage stability; a method for soldering, which method is highly reliable and suitable for producing fine-pitch mounted wiring boards and a variety of parts; and a joint produced through soldering.