Indium, chromium and nickel-modified eutectic Sn-0.7 wt% Cu lead-free solder rapidly solidified from molten state

Sn-Cu eutectic modified by minor In, Cr and Ni additions are one of the major alternatives to lead-free solders. The results show that nanostructured solders produced by rapid solidification are dependent on melting properties and the melting temperature. It is found that the In, Cr or Ni addition has the effect of suppressing the formation of eutectic rapidly solidified Sn-0.7Cu alloy. The results indicated that the melting temperatures (Tm) of Sn-0.7Cu are modified to lower temperature by In, Cr and Ni additions. The formation of new intermetallic compounds such as In3Sn, Cu6Sn5, Cu10Sn3, and NiSn are more uniformly distributed inside Sn-rich phase effectively enhancing the hardness and creep resistance of the eutectic Sn-0.7Cu solder joint at room temperature. The results of these tests are consistent with positive effect of the In, Cr and Ni in enhancing the performance of the eutectic Sn-0.7Cu solder as a practical to lead-free solder.