Ikuo Okamoto

Studies on Flux Action of Metallic Halides for Soldering

In the previous papers on aniline hydrochloride flux action of soldering, it has been shown that molten aniline hydrochloride reacts with copper to give CuCl2 and copper complex, which react with molten solder of Sn-Pb alloy to give metallic copper. Successively, this copper dissolves into the molten solder and a thin Cu-rich layer is formed on the surface of molten solder. The wetting of copper plate by the solder is improved through the reaction and the dissolution of Cu into molten solder.In this report, the flux action of various metallic halides en soldering was studied in relation to the reaction of flux with Sn solder and spreading phenomenon. The flux action of metallic halide may be considered as followsThe electrochemical series of metal in molten salts plays an important role in the reaction of metallic halide with Sn so1der. The effect of metallic halide on wetting is dependent mainly on the electrochemical series of metal, and improvement of spreading by metallic halide may be ascribed to the lowering of interfacial tension between flux and solder.Such a lowering of interfacial tension is caused by the dissolution of metal into molten Sn, while the metal results from the reaction between metallic halide and molten Sn.