軟鑞接の研究(第1報)

Abstract

This report is researched for the microstructure of joints, which are prepared by the soaking of the copper rods in the bath of molten tin, tin-lead alloy of eutectic composition and in tin powder with flux.1) The eutectoid temperature of Cu31Sn8 (δ) is 330°C-380°C It is recognized that δ is not formed at the Cu-Sn interface at the above temperature interval even for 30hr-70hr, but Cu3Sn is formed and contacts with Cu. But at 400°C δ contacts with Cu.2) When Cu-Sn is heated for very short time at 50°C-100°C above the melting point of Sn, Cu3 So and Cu6Sn5 are always formed and Cu3Sn contacts with Cu, Cu6Sn5 contacts with Cu3Sn. Therfore it is thought that these compounds have the important influence on soldering of copper by soft solder and play on important part. Up to now it has been thought that these compounds are not recognized when soldering time is very short.The microstructure of vertical section alone of solder joins have been studied, but the microstructure of the inclined plane of joins have been not observed, therefore these compounds have been passed over, because there very thin.3) The microstructure and microhardness of these compounds by the diffusion are same with those of the Cu31Sn8, Cu3Sn and Cu6Sn5 phase by melting. The Vickers microhardness of Cu31Sn8, Cu3Sn and Cu6Sn5 are about 590, 530 and 460.4) Between copper and solid tin are formed these compands Cu3Sn, Cu6Sn5 by diffusion below melting temperature of tin.5) The free energy of activation calculated from the deposition of tin on copper and brass with flux are 12970cal/g. atom and 12930ca1/g.atom.