Tensile Properties, Strain Rate Sensitivity and Microstructural Analysis of SN100C Solder Alloys

Sn-Cu-Ni-Ge (SN100C^®) is a high-performance Pb-free solder alloy widely used in the electronics manufacturing industry due to its excellent soldering performance and lower cost. SN100C has a huge potential to replace the commonly used Sn-Ag-Cu solders. This work investigates the effect of different strain rates (10-3 to 8×10-1s-1) on tensile performance for bulk SN100C samples at room temperature. The tensile properties, e.g., elastic modulus (E), yield strength (σy) and tensile strength (σT) are determined from the stress-stress curves. The value of σy and σT increases with increasing strain rates and this increase becomes less prominent at higher strain rates. Necking and ductile fracture are observed for all samples with a significant number of dimples, voids and tongues formed. The level of ductility of the samples decreases with increasing strain rates, which is further confirmed by the stress-strain behaviour. The microstructural evolution of the samples is evaluated by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) to reveal the generation of recrystallisation and fracture of the intermetallic compounds (IMCs) at the fracture tips and identify the embedded of IMCs within the sample matrix.