Abstract
Interfacial impedance method was applied to evaluate the interface stability of solder joints. Results showed that the surface treatment on rolled copper strongly influenced the solder joint interface structure. The composition and interfacial impedance between rolled copper and solder were also influenced by the surface treatment of the copper. Especially, a correlation was found between the surface treatment and time dependence of the interfacial impedance value. The admittance spectra of interfacial impedance between as-rolled copper and solder showed strain from the semicircular shape, although the plasma ashed copper or thermally oxidized copper showed no such strain over time. The strain probably represents solder joint instability. The interfacial impedance method can be useful for evaluation of the solid metal interface, not only the interface between the liquid and solid.
