Cobar’s SAC4-XM7S solder paste reportedly delivers excellent results in applications requiring extended heating profiles. It remains stable and active during extended heating at elevated temperatures, does not require a nitrogen blanket, and offers a robust printing window. It is available in most common SAC-alloys, including an anti-tombstoning type and several powder classes. Before the introduction of this paste, the supplier claims it was hardly possible that one single paste could provide all the desired properties for lead-free applications without the use of nitrogen blanketing and the use of extended profiles to minimize delta-T. The latter can represent a challenge to the process in applications where the thermal bulk between small and large components presents an added complication to the implementation of Pb-free technology. The only solution is to use an extended heat-profile with a long soak zone. This thermal load on the organic parts of a solder paste require the use of advanced synthetic polymers, in order to survive the higher heat and assure good reflow characteristics, too.
EPP EUROPE 433
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