Melting temperature depression of Sn-0.4Co-0.7Cu lead-free solder nanoparticles

Journal article, 2009

Purpose - The purpose of this paper is to study the melting temperature of the nanoparticles of the new developed Sn-0.4Co-0.7Cu (wt%) lead-free solder alloy. Design/methodology/approach - Nanoparticles of Sn-0.4Co-0.7Cu lead-free solder alloy were prepared by the self-developed consumable-electrode direct current arc technique, where ultrasonic vibration was applied during the manufacturing of the particles. X-ray diffraction and field emission scanning electron microscope were employed to analyze the crystal structure and morphology of the nanopartiles, respectively. Differential scanning calorimetry was used to investigate the melting temperature of both the bulk alloy and as-prepared nanoparticles. Findings - The melting temperature of the nanoparticles was approximately 5 degrees C lower compared to that of the bulk alloy. Originality/value - As a novel developed lead-free solder alloy, the Sn-0.4Co0.7Cu (wt%) alloy provides a cost advantage compared to the extensively used Sn-Ag-Cu system. Some limitations still exist, however, mainly due to its relatively higher melting temperature compared to that of eutectic Sn-37Pb solder. In view of this situation, the attempt to lower its melting temperature has recently attracted more attention based on the knowledge that the melting temperature for pure metals is reduced when the particle size is decreased down to a few tens of nanometers.