| 摘要 |
PROBLEM TO BE SOLVED: To safely form a soldering part of high heat resistance and high strength by applying a In-Sn solder of a specific composition not containing lead on a base metal, and by discharging a low melting component of a solder not being alloyed with a base metal to a periphery of a pressurized portion during pressurization under a melting condition. SOLUTION: A solder composed of 2-80 wt.%, preferably 5-60 wt.% In and the balance of Sn, is heated and melted. A solder is dipped in a solder liquid after a flux is applied on a welded face of a base metal such as copper, so as to melt and adhere the solder. Thereby, an alloy layer (a) of higher strength and higher melting point than solder itself is produced on an interface between a solidified solder layer b and a welded face. Then, the welded faces are overlaid, and the overlaid part is pressurized at a pressure of 1-6 kg/cm2 or so at the temperature slightly higher than the melting temperature of the solder, for example, at the temperature of 350-600 deg.C or so. Therefore, the solder layer b of low melting point under the molten condition is discharged to the proximity of the pressurizing portion, and strong jointing is completed while a residue alloy layer (a) is used as a joint.
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