Abstract

We studied the various characteristics of Sn-In (wt%) Pb-free solders for photovoltaic ribbon application. The solders near the eutectic composition of Sn₄₈In₅₂ (wt%) existed in InSn₄ and In₃Sn alloy phases, and in In crystal phase, but not in Sn crystal phase. In addition, the InSn4 phase (γ-alloy) existed separately from the In₃Sn (β-alloy) and the In phase confirmed by an SEM-EDS-mapping. The melting temperature of the eutectic solder of Sn₄₈In₅₂ (wt%) was 119.2℃, and when the Sn content decreased in reference to the eutectic composition, it slightly increased to 121.4℃, but when the Sn content increased, it remained almost constant at 119.1℃. The peel strength of the ribbon plated with the Sn₄₂In₅₈ (wt%) solder was 38.7 N/㎟, and it tended to increase when the Sn content increased. The peel strength of the eutectic Sn₄₈In₅₂ (wt%) solder was 53.6 N/㎟, and that of the Sn₅₁In₄₉ (wt%) solder was 61.6 N/㎟ that was the highest.

• Keywords: Photovoltaic ribbon, Sn-In Pb-free solders, Low-melting temperature, Peel strength