Solder Joint Reliability of Sn-Ag-Cu BGA and Sn-Pb Solder Paste

In the transition to lead-free, components suppliers need carry the product of lead-free and lead components. This could cause the extensive logistic problems in manufacturing. Therefore, it is necessary to study the solder joint character of Sn-Ag-Cu BGA and Sn-Pb solder paste. In this study, the results of solder joint shape and reliability evaluations of PBGA (plastic ball grid array) lead-free package assembled to PCBs (printed circuit boards) with eutectic Sn-Pb solder paste was presented. The lead-free package was assembled under various reflow profiles and PCB surface finish. The peak temperature of reflow soldering of 210, 225 and 235 degC with the soak profile was used. The PCB surface finish included HASL (hot air soldering level) and ENIG (electro-less Ni/immersion Au). The different types of solder joints, both as-reflowed and after reliability test were examined using optical microscope, transmission X-Ray. The reliability test of TTC (thermal torsion cycling) and ATC (accelerated thermal cycling) was used. Detailed failure analysis is also presented