OSP coatings: the nitrogen solution

For the past several years, tin-lead has been the most commonly used circuit board finish, mainly because of its high solderability. But as the current evolutions in Electronics are pushing toward more and more stringent demands in terms of quality, miniaturization, costs and environmental legislation compliance, the Assembly industry must find an alternative to those circuit board finishes. Among the existing solutions, the organic coatings may be one of the most attractive. However, whereas they bring solutions to the majority of the problems presented by tin-lead, they lead to solderability troubles when processed under air. This paper reports the results of tests aimed at evaluating the performance improvements for several organic coatings when replacing air by nitrogen based atmospheres during the temperature excursions