Search

Abstract: Nanoparticles were prepared with a consumable-electrode direct current arc (CDCA) technique. The results showed that the calorimetric melting onset temperature of the nanoparticles of SnAgCu solder alloy could be as low as 179°C, equivalent to that of the traditionally used SnPb eutectic alloy (183°C). Moreover, the homogenous melting model (HMM) and Gibbs–Thomson equation were employed to theoretically estimate the size-dependent melting temperature of the as-prepared nanoparticles. The structure and morphology of the nanoparticles were analyzed with a high-resolution transmission electron microscopy (HRTEM). The CDCA technique showed promising prospect in manufacturing large amounts of nanoparticles with controlled shape, small size, narrow particle size distribution and nearly oxide-free composition. This undoubtedly puts forward a novel feasible approach to manufacture high quality lead-free solders for electronic products. [Copyright &y& Elsevier]

Abstract: In the present work, effect of adding small amount of Er on the microstructure, physical and mechanical properties of Sn3.8Ag0.7Cu solder has been investigated. The purpose is to understand if the heavy rare earth Er has similar effect as light rare earth Ce or La on improving properties of SnAgCu lead-free solder. The results indicated that adding small amount of Er can evidently improve the wettability, mechanical strength and creep rupture life of the Sn3.8Ag0.7Cu solder alloy. It is pointed out that proper Er content in the Sn3.8Ag0.7Cu solder alloy should be in a range of 0.05–0.25wt%. Moreover, the size of intermetallic compounds (IMC) was measured quantitatively for the Sn3.8Ag0.7Cu solder alloys with various Er contents. It is felt that the increase in mechanical strength may be related to the refining of IMCs of the solder due to the addition of small amount of Er. [Copyright &y& Elsevier]

New under bump metallization (UBM) is required for future microelectronics to minimize reliability concerns with solder interconnects. In this study, electroless FeP film was prepared as UBM. Solderability of electroless NiP, electrodeposite Fe and electroless FeP films with eutectic SnAgCu solder was investigated by static wetting tests and wetting balance measurements. Results revealed that the solderability of NiP film has almost no change with thermal aged for the film in air atmosphere increasing. The contact angles for FeP and Fe films with SnAgCu solder increased and the maximum wetting force decreased with heating time increasing from 0 h, 48 h, 89 h–160 h at 180 °C. But the solderability of FeP film was found to be better than those of NiP and Fe whether the films in base or thermal aged at 180 °C for 89 h. Even after thermal aged in air atmosphere at 180 °C for 160 h, the FeP also performed the smallest contace angle compared with the NiP and the Fe. Oxide layer on the surface of FeP was much easier to be removed by rosin mildly activated flux during reflow process because loose structure. It was proved to be the key for the highly solderability of electroless FeP. Image 1 • Solderability of electroless NiP has almost no change with oxide time increasing from 0 hour to 160 hours at 180 oC in air. • Solderability of electroless FeP and electrodeposite Fe films reduced with the oxide time increasing. • Solderability of FeP was found to be better than those of NiP and Fe whether in base or oxidation at 180 oC for 160 h. • Difference of oxide layer was proved to be the key for highly solderability of electroless FeP. [ABSTRACT FROM AUTHOR]