Evaluation on the Manufacturability of Solderable Sn Coatings Obtained by Employing Hot-Dipped Tinning Process

The lack of systematic evaluation on the feasibility of fabricating solderable coatings through a hot-dipped tinning process restricts the increasing applications of this process in the electronics industry. In this paper, the temperature-dependence, wettability, thermal stability, and microstructure of solderable Sn coatings produced by hot-dipped tinning are evaluated synthetically, which aims at developing a cost-efficient and environment-friendly way to fabricate solderable Sn coatings. Experimental results show that a dipping temperature of 280–320°C and dipping time of 4–6 s are appropriate process conditions for C1100 foils. The solderability of C1100 foils is superior to C194 foils. After long-term service (up to 500 h) at elevated temperature, sharp spines caused by SnO2 whiskers appear on the surface of coated C194 foils, which increase the risk of short circuit in use and lower their reliability. The addition of microalloying elements may be a possible solution to restrain SnO2 whiskers.