THE ROLE OF NICKEL IN SOLDER ALLOYS -PART 1. THE EFFECT OF NI ON THE BEHAVIOUR OF SN-0.7CU IN SOLDERING AND COATING PROCESSES

摘要

Recent real time X-ray imaging of the soldering process using synchrotron radiation has revealed that the addition of Ni to Sn-0.7Cu changes the hypoeutectic microstructure to near eutectic. This is consistent with the previously reported observation that the Ragone fluidity peaks with a Ni addition of around 0.05% and explains why the Sn-0.7Cu-0.05Ni alloy performs so well in wave and selective soldering and in hot air solder levelling. Other observations on wetting and the growth of the interfacial IMC made in synchrotron X-ray imaging will also be reported and related to the performance of the alloy in production assembly processes. This paper provides an overview of how real time synchrotron X-ray imaging techniques were used to establish the effect of Ni on the behavior of Sn-0.7Cu in soldering and coating processes.