Enhancement of solderability of Cu60Zr30Ti10 bulk metallic glass by dealloying in hydrofluoric acid solution

Abstract

To extend the engineering applications of bulk metallic glasses (BMGs), it is necessary to create process to form appropriate BMG/BMG and BMG/crystalline metal joint. In this study, hydrofluoric acid (HF) solution treatment and a laser soldering process were employed to enhance the solderability of Cu60Zr30Ti10 BMG. The surface treatment in HF solution successfully dissolved surface Zr and Ti, resulting in concentration of Cu at the surface. A reflow soldering process using Sn-3.0 mass% Ag-0.5 mass% Cu (SAC) solder on this surface showed obvious dewetting because the thin Cu-rich layer dissolved into the molten solder. Laser soldering with a 0.01 s irradiation time, which produces rapid heating and cooling rates, offered good wettability of SAC solder and Sn-57 mass% Bi (SB) solder. At the interface between the SB solder and the HF-treated BMG foil, an intermetallic compound (IMC) layer was observed by scanning electron microscopy (SEM).