Retardation Effect of Tin Multilayer on Sn-3.0Ag-0.5Cu (SAC305)-Based Solder Joint Interface

Transient liquid phase-like soldering technique has been successfully applied to prepare lead-free solder joints at 230 degrees C. Multiple interlayers of tin thin films in combination with a Sn-3.0Ag-0.5Cu (SAC305) solder paste have been used as filler for joining. Microstructural analysis was carried out by electron microscopy and energy-dispersive spectroscopy. For interlayer containing samples (Cu-Sn-SAC305-Sn-Cu), interfacial intermetallics layers found to be more homogeneous compared to the samples without interlayers (Cu-SAC305-Cu). Quality of the joints has been investigated nondestructively by ultrasonic method. On measuring the electrical resistivity by four-probe method, Cu-Sn-SAC305-Sn-Cu solder joint shows lower electrical resistivity compared to that of the Cu-SAC305-Cu solder joint, wherein nonlinear ultrasonic parameters confirm the superiority of former over later.