Study on microstructure control of copper-tin biphase interface in hot-dip tin-plated electronic copper strip

Abstract

In order to study the effect of reflow process parameters on the copper-tin biphase interface structure of hot dip tinned electronic copper strip, heat treatment of C14415 hot dip tinned electronic copper strip was carried out. Electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM) were used to collect and analyze the microcosmic characteristics of the copper-tin biphase interface of hot dip tin-coated electronic copper strip after reflux. The results show that Cu6Sn5 and Cu3Sn are formed at the Cu–Sn biphase interface during reflow welding, and Cu6Sn5 is first formed at the Cu–Sn biphase interface, and Cu3Sn is gradually formed at the bottom of Cu6Sn5 when the Cu–Sn biphase interface forms a high temperature and stable environment. During the growth of Cu and Sn and its series of compounds, different reflow welding processes have no obvious effect on the distribution of interphase orientation difference. The competitive growth process of the multiphase interface during reflow welding was reconstructed through the distribution state of the multiphase interface under different reflow welding processes. The optimal process parameters of reflow welding were 290°C-heat preservation for 3min-air cooling.

Keywords

• Hot dip tin plating
• Copper strip
• Reflow welding
• Copper-tin biphase interface