| 摘要 |
PROBLEM TO BE SOLVED: To obtain a solder capable of soldering completely with no flux or with extremely small amount of flux to be used by making the solder composed of a specified weight rate of Na and the balance Sn. SOLUTION: A solder is composed of 0.0001-10 wt.% Na and the balance Sn. Preferably the solder is composed of 0.0001-10 wt.% Na and the balance Sn and other metals, and further, regarding the other metals, the solder comprises a total sum of not less than one kind of Pb, In, Bi, Ge, Sb, Cu, Zn, and Ag of 0.001-50 wt.% Furthermore, preferably, the solder is composed of a Sn alloy constituting a wire-shaped core using metallic Na itself corresponding to 0.0001-10 wt.% to the total weight and contains the balance Sn and the other metals wherein Sn alloy covers around the core, and the core and the surrounding Sn alloy do not form an alloy but are formed into a wire shape. Thereby, there is no need of Pb as an additional metal, so it becomes possible to be free from Pb, and by containing Na, soldering at a far lower temperature becomes available.
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