Abstract: [PROBLEMS TO BE SOLVED] To provide a low-silver lead-free solder alloy having an excellent wettability and being excellent in heat-fatigue resistance, and a solder-paste soldering material and resin-flux cored soldering material being excellent in fatigue resistance, and a joined product by using the soldering material. [MEANS FOR SOLVING] 0.1 to 1.5% by weight of Cu, 0.01% by weight or more and less than 0.05% by weight of Co, 0.05 to 0.25% by weight of Ag, 0.001 to 0.008% by weight of Ge, and the remainder being Sn. This low silver lead-free solder alloy is blended with a pasty flux or molded in a liner form by using a solid or pasty flux as a core. [SELECTED FIGURE] FIG.

Abstract: Provided is an SnCu lead-free solder alloy which eliminates a drawback that an intermetallic compound excessively precipitates and the precipitate serves as nuclei to form dross to thereby cause soldering defects including a needle-like protrusion to occur, thus to satisfy all of the properties required for practical use. A lead-free solder alloy contains 0.1 to 1.5% by weight of Cu, not less than 0.01 and less than 0.05% by weight of Co, 0.05 to 0.5% by weight of Ag and 0.01 to 0.1% by weight of Sb, the remainder being Sn, or further contains 0.001 to 0.008% by weight of Ge, whereby the formation of dross is prevented, and thus the drawback that soldering defects including a needle-like protrusion occur is eliminated.