Abstract:

While most electronic equipment used tin-based lead-free solders, some equipment is still produced with tin-lead solder. The use of tin-lead solder for assembly can be an issue when working with area array components. Area array components (BGA/CSP) are often available only with lead free solder balls. As a result, tin-lead assemblers must either reball the lead-free area array components with tin-lead solder spheres or create mixed solder interconnects. For lead-free manufacturers, tin-silver-copper (SAC) solder spheres are frequently used. Due to issues with drop durability, some part manufacturers have reduced the silver content in the solder spheres to improve reliability. In this paper we examine reliability of BGA assemblies with the mixed solder sphere/solder paste combinations subject to harmonic vibration loading. The solder sphere/solder paste combinations include SAC305/SAC305, SAC305/SnPb, SAC105/SAC305, and SnPb/SnPb. The results in this study indicate that both the SAC105/SAC305 and SAC305/SAC305 are more likely to failure sooner that SnPb/SnPb and SAC305/SnPb assemblies under vibration loading.

Keywords : Lead Free Solders, Solder Interconnects, Vibration Durability, Mixed Solder Assemblies

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