Lead-free solder alloy and solder joint part
A lead-free solder alloy consisting essentially of: 32 mass % or more and 40 mass % or less of Bi; 0.1 mass % or more and 1.0 mass % or less of Sb; 0.1 mass % or more and 1.0 mass % or less of Cu; 0.001 mass % or more and 0.1 mass % or less of Ni; and a remainder of Sn with unavoidable impurities. The lead-free solder alloy further contains specific elements in amounts in predetermined ranges.
1. A lead-free solder alloy consisting of:
32 mass % or more and 40 mass % or less of Bi;
0.1 mass % or more and 1.0 mass % or less of Sb;
0.1 mass % or more and 1.0 mass % or less of Cu;
0.001 mass % or more and 0.1 mass % or less of Ni;
optionally one of
0.3 mass % or less of Ag,
at least one selected from Fe and Co, wherein a content of Fe and Co is 0.001 mass % or more and 0.1 mass % or less, and
at least one selected from Ga, Mn, V, P, and Ge, wherein a content of each of Ga, Mn, V, P, and Ge is 0.001 mass % or more and 0.01 mass % or less; and
a remainder of Sn with unavoidable impurities,
wherein a rate of change of max force of the lead-free solder alloy after aging at 150° C. for 100 hours is 100% or more and 184% or less in an impact sheer test with a shear speed at 1000 mm/s.
2. The lead-free solder alloy according to claim 1 wherein Ag is present in an amount of 0.3 mass % or less.
3. The lead-free solder alloy according to claim 1 wherein at least one selected from Fe and Co is present, wherein a content of each of Fe and Co is 0.001 mass % or more and 0.1 mass % or less.
4. The lead-free solder alloy according to claim 1 wherein at least one selected from Ga, Mn, V, P, and Ge is present, wherein a content of each of Ga, Mn, V, P, and Ge is 0.001 mass % or more and 0.01 mass % or less.
5. The lead-free solder alloy according to claim 1 , having 36 mass % or more and 38 mass % or less of Bi.
6. The lead-free solder alloy according to claim 2 , having 36 mass % or more and 38 mass % or less of Bi.
7. The lead-free solder alloy according to claim 3 , having 36 mass % or more and 38 mass % or less of Bi.
8. The lead-free solder alloy according to claim 4 , having 36 mass % or more and 38 mass % or less of Bi.
9. A solder joint part comprising the lead-free solder alloy according to claim 1 .
10. A solder joint part comprising the lead-free solder alloy according to claim 2 .
11. A solder joint part comprising the lead-free solder alloy according to claim 3 .
12. A solder joint part comprising the lead-free solder alloy according to claim 4 .