A lead-free solder alloy may comprise tin, silver, copper, bismuth, cobalt, and antimony. The alloy may further comprise nickel. The silver may be present in an amount from about 2.0% to 2.8% by weight of the solder. The copper may be present in an amount from about 0.2% to 1.2% by weight of the solder. The bismuth may be present in an amount from about 0.0% to about 5.0% by weight of the solder. In some embodiments, the bismuth may be present in an amount from about 1.5% to 3.2% by weight of the solder. The cobalt may be present in an amount from about 0.001% to about 0.2% by weight of the solder. The antimony may be present in an amount between about 0.0% to about 0.1% by weight of the solder. The balance of the solder is tin.

A lead-free solder alloy may comprise tin, silver, copper, bismuth, cobalt, and antimony. The alloy may further comprise nickel. The silver may be present in an amount from about 2.0% to 2.8% by weight of the solder. The copper may be present in an amount from about 0.2% to 1.2% by weight of the solder. The bismuth may be present in an amount from about 0.0% to about 5.0% by weight of the solder. In some embodiments, the bismuth may be present in an amount from about 1.5% to 3.2% by weight of the solder. The cobalt may be present in an amount from about 0.001% to about 0.2% by weight of the solder. The antimony may be present in an amount between about 0.0% to about 0.1% by weight of the solder. The balance of the solder is tin.

A solder alloy has an alloy composition consisting of, in mass %, Ag: 0 to 4%, Cu: 0.1 to 1.0%, Ni: 0.01 to 0.3%, Sb: 5.1 to 7.5%, Bi: 0.1 to 4.5%, Co: 0.001 to 0.3%, P: 0.001 to 0.2%, and the balance being Sn.

A solder alloy has an alloy composition consisting of, in mass %, Ag: 0 to 4%, Cu: 0.1 to 1.0%, Ni: 0.01 to 0.3%, Sb: 5.1 to 7.5%, Bi: 0.1 to 4.5%, Co: 0.001 to 0.3%, P: 0.001 to 0.2%, and the balance being Sn.

A flux comprising an organic acid; a solvent; and polyoxyethylene behenyl alcohol having an average number of moles of ethylene oxide added of 7 to 40 mol.

A lead-free solder ball is provided which suppresses interfacial peeling in a bonding interface of a solder ball, fusion defects which develop between the solder ball and solder paste, and which can be used both with Ni electrodes plated with Au or the like and Cu electrodes having a water-soluble preflux applied atop Cu. The lead-free solder ball for electrodes of BGAs or CSPs consists of 1.6-2.9 mass % of Ag, 0.7-0.8 mass % of Cu, 0.05-0.08 mass % of Ni, and a remainder of Sn. It has excellent resistance to thermal fatigue and to drop impacts regardless of the type of electrodes of a printed circuit board to which it is bonded, which are Cu electrodes or Ni electrodes having Au plating or Au/Pd plating as surface treatment.

A lead-free solder ball is provided which suppresses interfacial peeling in a bonding interface of a solder ball, fusion defects which develop between the solder ball and solder paste, and which can be used both with Ni electrodes plated with Au or the like and Cu electrodes having a water-soluble preflux applied atop Cu. The lead-free solder ball for electrodes of BGAs or CSPs consists of 1.6-2.9 mass % of Ag, 0.7-0.8 mass % of Cu, 0.05-0.08 mass % of Ni, and a remainder of Sn. It has excellent resistance to thermal fatigue and to drop impacts regardless of the type of electrodes of a printed circuit board to which it is bonded, which are Cu electrodes or Ni electrodes having Au plating or Au/Pd plating as surface treatment.

Provided is a lead-free solder alloy that has excellent tensile strength and ductility, does not deform after heat cycles, and does not crack. The In and Bi content are optimized and the Sb and Ni content are adjusted. As a result, this solder alloy has an alloy composition including, by mass, 1.0 to 7.0% of In, 1.5 to 5.5% of Bi, 1.0 to 4.0% of Ag, 0.01 to 0.2% of Ni, and 0.01 to 0.15% of Sb, with the remainder made up by Sn.

Provided is a lead-free solder alloy that has excellent tensile strength and ductility, does not deform after heat cycles, and does not crack. The In and Bi content are optimized and the Sb and Ni content are adjusted. As a result, this solder alloy has an alloy composition including, by mass, 1.0 to 7.0% of In, 1.5 to 5.5% of Bi, 1.0 to 4.0% of Ag, 0.01 to 0.2% of Ni, and 0.01 to 0.15% of Sb, with the remainder made up by Sn.

Provided are a Sn—Bi—In-based low melting-point joining member used in a Pb-free electroconductive joining method in mounting a semiconductor component, and is usable for low-temperature joining, and a manufacturing method therefor.

A Sn—Bi—In-based low melting-point joining member, including a Sn—Bi—In alloy that has a composition within a range represented by a quadrangle in a Sn—Bi—In ternary phase diagram, a first quadrangle having four vertices including: Point 1 (1, 69, 30), Point 2 (26, 52, 22), Point 3 (40, 10, 50), and Point 4 (1, 25, 74), where Point (x, y, z) is defined as a point of x mass % Sn, y mass % Bi and z mass % In, and that also has a melting point of 60 to 110° C. As well as a method for producing a Sn—Bi—In-based low melting-point joining member, including a plating step of forming a plated laminate on an object to be plated, the plated laminate including a laminated plating layer obtained by performing Sn plating, Bi plating, and In plating respectively such that the laminated plating layer has a composition within the range represented by the first quadrangle.