A comprehensive parallel study on the board level reliability of SAC, SACX and SCN solders

Legislation that mandates the banning of lead (Pb) in electronics due to environmental and health concerns has been actively pursued in many countries during the past fifteen years. Lead-free electronics will be deployed in many products that serve markets where the reliability is a critical requirement. Although a large number of research studies have been performed and are currently under way in the lead- free soldering area, especially on the reliability of SAC lead- free solder joints, data on comparison of SAC solders with other lead-free solders (such as SCN) is still scarce. This paper presents a systematic reliability study of lead- free solder joints with different solder alloys. The printed circuit board test assemblies include two kinds of components (QFN and PBGA), with different terminal metallurgies and five kinds of lead-free solder pastes (SAC305, SAC387, SACC, SACS and SCN). The results and analysis of different reliability tests (accelerated thermal cycling, package shear/pull, bending and drop tests) with five kinds of solders are discussed.