| 摘要 |
PROBLEM TO BE SOLVED: To inhibit the formation of alloy layer with low strength and low melting point at the interface between a land and solder, and to assure satisfactory quality and reliability of solder bonding. SOLUTION: Reflow process includes a heat process to heat and melt soldering paste adhered on PCB3, and a cooling process to cool and solidify the soldering paste in a molten state, which is heated and melted by the heat process, with forced cooling at a cooling speed of 1.5°C/sec or more. Sn-Zn-Bi alloy having Bi content of less than 3% is used as the soldering paste, and a paste combining two or more kinds of solder powder is suitable for the soldering paste. If flow treatment is executed after that, the flow treatment goes through a flow process in which the temperature of a soldered joint of an electric component mounted by the reflow process is 170°C or less. COPYRIGHT: (C)2004,JPO
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