| 摘要 |
PROBLEM TO BE SOLVED: To prevent migration of flux used in a non-cleaning condition, and use the flux residue as an insulating film by containing rosin or/and modified rosin and activator, and also a specific melt flow rate ethylene-vinyl acetate copolymer at a specific melt flow rate. SOLUTION: Ethylene-vinyl acetate copolymer with the melt flow rate of 500 g/10 min or more is contained at 1-50 wt.%. The flux contains 5-30 wt.% fatty acid amid or/and fatty acid bis amid, and the solder paste is obtained by mixing a solvent diluent of the flux and the powder solder. Additionally, soldering is carried out using the flux, and the flux residue after soldering is remained as an insulating film. Furthermore, soldering is carried out using the solder paste, and it is preferable that the flux residue after soldering is remained as an insulating film. Thereby, elements can be built on a circuit substrate at excellent workability and safety, without cleaning/removing the flux residue.
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