| 摘要 |
PROBLEM TO BE SOLVED: To suppress the generation of a joining defect of a solder alloy and a solder-joined structure to improve the joining strength. SOLUTION: For a joined structure where a first solder alloy consisting essentially of Sn and contains at least one of Ag and Cu in Sn and a second solder alloy containing both Sn and Cu are melt-joined to form a joining alloy, the composition of each solder alloy is so set as to satisfy the following relation (1): (W1+W2)<=0.6×W3... (1), where the case where W1=0 or W2=0 is included, and W1: the content of Ag with respect to the whole joining alloy, W2: the content of Cu with respect to the whole joining alloy, and W3: the content of Zn with respect to the whole joining alloy.
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