Abstract: A lead-free solder alloy includes Ag in an amount of 0.3 to 4.0% by mass, Cu in an amount of 0.1 to 2.0% by mass, Fe in an amount of 0.005 to 0.05% by mass, Ni in an amount of 0.01 to 0.5% by mass, Ga in an amount of 0.001 to 0.1% by mass, and Sn as the balance.

Abstract: In a method for manufacturing a solder joint part, at least one of a first metal base material and a second metal base material is an alloy containing Ni in an amount of more than 0 wt % and less than 44 wt % and Cu in an amount of more than 56 wt %, and solder is a solder alloy containing Ga and inevitable impurities or a solder alloy containing Ga as a main component and having a melting point of 30° C. or lower. The method includes applying the solder to a surface of the first metal base material and placing the second metal base material on the applied solder, and heating the first and second metal base materials to a temperature of 90° C. or lower in a specified atmosphere or in a liquid to generate CuGa2 or (Cu, Ni)Ga2 between the first and second metal base materials, thereby joining the first and second metal material.

Abstract: Provided is a solder-metal mesh composite material in which a lead-free solder layer formed of Sn—Cu—Ni-based lead-free solder contains metal mesh having high thermal conductivity, a void occupancy in a cross-section in a thickness direction is 15% or less, and the Sn—Cu—Ni-based lead-free solder contains 0.1 to 2% by weight of Cu, 0.002 to 1% by weight of Ni, and Sn as a remainder or contains 0.1 to 2% by weight of Cu, 0.002 to 1% by weight of Ni, 0.001 to 1% by weight of Ge, and Sn as a remainder.

Abstract: A lead-free solder alloy includes Ag in an amount of 0.3 to 4.0% by mass, Cu in an amount of 0.1 to 2.0% by mass, Fe in an amount of 0.005 to 0.05% by mass, Ni in an amount of 0.01 to 0.5% by mass, Ga in an amount of 0.001 to 0.1% by mass, and Sn as the balance.

Abstract: In a method for manufacturing a solder joint part, at least one of a first metal base material and a second metal base material is an alloy containing Ni in an amount of more than 0 wt % and less than 44 wt % and Cu in an amount of more than 56 wt %, and solder is a solder alloy containing Ga and inevitable impurities or a solder alloy containing Ga as a main component and having a melting point of 30° C. or lower. The method includes applying the solder to a surface of the first metal base material and placing the second metal base material on the applied solder, and heating the first and second metal base materials to a temperature of 90° C. or lower in a specified atmosphere or in a liquid to generate CuGa2 or (Cu, Ni)Ga2 between the first and second metal base materials, thereby joining the first and second metal material.

Abstract: A soldered joint of the present invention is a soldered joint using a lead-free solder alloy of Sn—Cu—Ni—Bi—Ge system, and the lead-free solder alloy is an alloy in which an addition amount of Cu is 0.1 weight % to 2.0 weight %, an addition amount of Ni is 0.05 weight % to 0.5 weight %, an addition amount of Bi is 0.1 weight % to less than 8 weight %, an addition amount of Ge is 0.006 weight % to 0.1 weight %, and a balance is Sn and inevitable impurities. The soldered joint of the present invention includes a bonding portion with an object to be soldered in which Cu3Sn is prevented from being generated.