Gas Atomization of Sn-Pb Solder Alloys; The Influence of Composition on Morphology

摘要

The production of eutectic Sn-Pb alloy type 3 electronic grade solder powder (25 to 45 microns) has traditionally been dominated by spinning disk atomization and, to a lesser extent, ultrasonic atomization. As electronic packaging evolves towards finer pitch sizes powder finer than 25 microns is required. Spinning disk and ultrasonic atomization produce poor yields of powder less than 25 microns, thus there is a renewed interest in gas atomization for producing higher yields of finer powder. The trade-off in higher yields is a reduction in the quality of particle morphology, specifically sphericity. Lead-free electronic solder alloys, which are predominantly tin, appear to be able to be gas atomized to produce powder with acceptable morphologies. Thus, it appears that lead may be the cause of the morphology issue with the traditional eutectic Sn-Pb alloy. This paper will present a study of the morphology of several Sn-Pb alloys as a function of lead content.