Abstract: There is closed a flux which is designed to be used in a soldering using a lead-free and zinc-free solder containing tin as a major component and not containing lead, the soldering being adapted to be applied to a surface portion which is constituted by a copper-based metal and/or a nickel-based metal (excluding the case where the surface portion is constituted by electroless nickel plating), wherein the flux contains at least one kind of material selected from the group consisting of a copper-based metal, a nickel-based metal, an inorganic salt of copper-based metal and/or a nickel-based metal, an inorganic complex of copper-based metal and/or a nickel-based metal, and an organic complex of copper-based metal and/or a nickel-based metal (a metal complex of an organic compound where atoms of N, O and S in amine (excluding nitrogen-containing hetrocyclic compounds), imine (excluding nitrogen-containing hetrocyclic compounds), oxime, ketone, alkoxy and thioketone are coordinated with a metal).

Abstract: A solder powder is coated with an agent that protects the powder from oxidation. The coating agent is substantially insoluble in a vehicle used to make solder pastes. Thus, pastes made with the coated powders also resist oxidation even when exposed to air. A method for making the coated solder powders is also disclosed and claimed.

Abstract: A soldering device wherein the article to be soldered is moved into contact with molten solder which flows in the direction counter to the direction of movement of said article is characterized by including a nozzle for flowing said molten solder and a flow path of a channel shape provided contiguous thereto for circulating said molten solder flowed out of said nozzle, said flow path having side-wall plates which are vertically adjustable.