| 摘要 |
PROBLEM TO BE SOLVED: To reduce generation of voids during the reflow in a sandwich condition in a soldering case of surface mounting using a formed solder or of joining a heat radiation plate by providing a water soluble flux mainly consisting of an ester of an organic acid and a polyhydric alcohol to realize water cleaning. SOLUTION: A water soluble flux mainly consists of an ester of an organic acid such as capric acid, lauric acid, myristic acid, palmitic acid, linoleic acid, and oleic acid, and a polyhydric alcohol such as butanediol, glycerol, and polyglycerol. A water soluble flux for reflow soldering using this formed solder is of liquid or paste form in which its viscosity can be regulated by adding an activating agent and a solvent. The ester includes a lauric acid polyglycerol ester and an oleic acid polyglycerol ester. The activating agent includes carbonic acid, and/or amine halogenated hydroacid.
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