Sn-Cu-Ni soldering process optimization using multivariate analysis

One lead free solder candidate, Sn-Ag-Cu305 (Sn96.5/Ag3.0/Cu0.5), has come into widespread use as a replacement for traditional tin-lead solder (Sn63/Pb37). However, the price of silver has increased dramatically in recent years. This has increased manufacturing costs, impacting firm competitiveness. This paper evaluates the performance of the low cost Sn-Cu-Ni solder alloy used for wave soldering. Sample products for several applications are used to assess critical factors in the wave soldering process. A principal component analysis was performed in this paper to integrate multiple quality characteristics, namely assembly yield and solder joint strength, for process development. As a result, a parameter combination of 270 rm C soldering temperature and 8 s dwell time is recommended. A test vehicle with daisy-chain circuitry design is used to investigate the performance of samples prepared by the optimal process. Samples are subject to the thermal cycling test. The performance of the recommended process is therefore verified.