Abstract: The fracture surface and composition of single crystal copper fine bonding wire are inspected by scanning electron microscopy(SEM) and X-ray energy dispersive spectrometer(EDS), and the broken type and its influencing factors in single crystal copper wire drawing are analyzed. The results show that the breaking of fine single crystal copper bonding wire in drawing process is mainly caused by the oxide segregation formed by high-concentration gas elements O and S, the high mass fraction of harmful impurity elements(Al, Ca, Si, etc) and the intermetallic compounds formed thereby, the holes caused by internal defects(micro-pores and impurities, non-uniform microstructures) or local stress concentration in single crystal copper. The surface defects(peeling, burrs, scratches, etc) and micro-oxide impurities have decisive influence to the sudden wire breaking in the drawing process. The phenomenon of hardening of single crystal copper is obviously, the local stress concentration caused by improper tension control and its abrupt change lead to the wire breaking in the drawing process.

Key words: Bonding wire, Drawing, Single crystal copper, Wire breaking