A solder alloy is used for soldering, and its chemical composition in mass % includes: 2.0 to 4.0% of Ag; 0.6 to 1.2% of Cu; 2.0 to 5.0% of Sb; 1.1 to 3.5% of In; 0 to 0.20% of Ni; 0 to 0.20% of Co; 0 to 0.05% of Ge; and balance of Sn, and impurities.

A solder alloy is used for soldering, and its chemical composition in mass % includes: 2.0 to 4.0% of Ag; 0.6 to 1.2% of Cu; 2.0 to 5.0% of Sb; 1.1 to 3.5% of In; 0 to 0.20% of Ni; 0 to 0.20% of Co; 0 to 0.05% of Ge; and balance of Sn, and impurities.

A solder alloy has an alloy composition consisting of, in mass %, Cu: 0.1% to 2.0%, Ni: 0.01% to 0.4%, P: 0.001% to 0.08%, and Ge: 0.001% to 0.08%, with the balance being Sn. The alloy composition satisfies the following relations (1) to (3): (Cu+5Ni)≤0.945% (relation (1)), (P+Ge)≤0.15% (relation (2)), 2.0≤(Cu+5Ni)/(P+Ge)≤1000 (relation (3)). In the above relations (1) to (3), Cu, Ni, P, and Ge each represents a content (mass %) thereof in the solder alloy.

A SnBiSb series low-temperature lead-free solder and a preparation method thereof, which belongs to the technical field of low-temperature soldering. The lead-free solder includes by weight the following composition: 32.8-56.5% of Bi, 0.7-2.2% of Sb, with the remainder being Sn, wherein the weight percentages of Bi and Sb satisfy a relationship of b=0.006a2−0.672a+19.61+c, wherein the symbol a represents the weight percentage of Bi, the symbol b represents the weight percentage of Sb, and the range of c is −1.85≤c≤1.85. The solder alloy has a peritectic or near peritectic structure with a low melting point, and has an excellent mechanical performance and reliability, and applicable to the field of low-temperature soldering.

A SnBiSb series low-temperature lead-free solder and a preparation method thereof, which belongs to the technical field of low-temperature soldering. The lead-free solder includes by weight the following composition: 32.8-56.5% of Bi, 0.7-2.2% of Sb, with the remainder being Sn, wherein the weight percentages of Bi and Sb satisfy a relationship of b=0.006a2−0.672a+19.61+c, wherein the symbol a represents the weight percentage of Bi, the symbol b represents the weight percentage of Sb, and the range of c is −1.85≤c≤1.85. The solder alloy has a peritectic or near peritectic structure with a low melting point, and has an excellent mechanical performance and reliability, and applicable to the field of low-temperature soldering.

A semiconductor device includes a semiconductor chip having first and second main electrodes disposed on opposite surfaces of a silicon carbide substrate, first and second heat dissipation members disposed so as to sandwich the semiconductor chip, and joining members disposed between the first main electrode and the first heat dissipation member and between the second main electrode and the second heat dissipation member. At least one of the joining members is made of a lead-free solder having an alloy composition that contains 3.2 to 3.8 mass % Ag, 0.6 to 0.8 mass % Cu, 0.01 to 0.2 mass % Ni, x mass % Sb, y mass % Bi, 0.001 to 0.3 mass % Co, 0.001 to 0.2 mass % P, and a balance of Sn, where x and y satisfy relational expressions of x+2y≤11 mass %, x+14y≤42 mass %, and x≥5.1 mass %.

A semiconductor device includes a semiconductor chip having first and second main electrodes disposed on opposite surfaces of a silicon carbide substrate, first and second heat dissipation members disposed so as to sandwich the semiconductor chip, and joining members disposed between the first main electrode and the first heat dissipation member and between the second main electrode and the second heat dissipation member. At least one of the joining members is made of a lead-free solder having an alloy composition that contains 3.2 to 3.8 mass % Ag, 0.6 to 0.8 mass % Cu, 0.01 to 0.2 mass % Ni, x mass % Sb, y mass % Bi, 0.001 to 0.3 mass % Co, 0.001 to 0.2 mass % P, and a balance of Sn, where x and y satisfy relational expressions of x+2y≤11 mass %, x+14y≤42 mass %, and x≥5.1 mass %.

Provided are a solder alloy, a solder paste, a solder ball, a solder preform, and a solder joint, which have a melting temperature within a predetermined range, and high tensile strength and shear strength, suppress generation of voids, and have excellent mountability due to their thin oxide films. The solder alloy has an alloy composition consisting of, by mass %, Ag: 2.5 to 3.7%, Cu: 0.25 to 0.95%, Bi: 3.0 to 3.9%, and In: 0.5 to 2.3%, with the balance being Sn, and the alloy composition satisfies the following relations (1) and (2): 8.1≤Ag+2Cu+Bi+In ≤11.5 (1), and 1.00≤(Bi+In)/Ag≤1.66 (2). Ag, Cu, Bi and In in the relations (1) and (2) each represent the contents (mass %) in the alloy composition.

Provided are a solder alloy, a solder paste, a solder ball, a solder preform, and a solder joint, which have a melting temperature within a predetermined range, and high tensile strength and shear strength, suppress generation of voids, and have excellent mountability due to their thin oxide films. The solder alloy has an alloy composition consisting of, by mass %, Ag: 2.5 to 3.7%, Cu: 0.25 to 0.95%, Bi: 3.0 to 3.9%, and In: 0.5 to 2.3%, with the balance being Sn, and the alloy composition satisfies the following relations (1) and (2): 8.1≤Ag+2Cu+Bi+In ≤11.5 (1), and 1.00≤(Bi+In)/Ag≤1.66 (2). Ag, Cu, Bi and In in the relations (1) and (2) each represent the contents (mass %) in the alloy composition.

Provided is a solder paste which uses a conventional flux, and for which long-term preservation is made possible and an easy preservation method can be realized by suppressing changes in the viscosity of the paste over time. This solder paste is provided with a solder powder, a zirconium oxide powder, and a flux, and changes in the viscosity of the paste over time are suppressed.