A Novel Electronic Packaging Method to Replace High-Temperature Sn-Pb Solders

Abstract

The In/Ni/Cu/Ni/In multilayer was prepared by an electroplating method to replace high-temperature Sn-Pb solders that are conventionally used but are very harmful to the environment. This study shows all the sandwich couples that formed the (Cu,Ni) 6 (Sn,In) 5 and Cu 2 In 3 Sn phases at the interface. When the solder joint was reflowed at 200°C, a planar layer (Ni,Cu) 3 (Sn,In) 4 formed near the Ni layer. When the reflowing temperature was increased to 300°C, another planar layer Cu 3 (Sn,In) formed near the Cu substrate. The greater part of the intermetallic compounds in this case were the (Cu,Ni) 6 (Sn,In) 5 and Cu 3 (Sn,In) phases. The Cu 3 (Sn,In) phase thickness was increased with increasing aging time. The thicker formation of Cu 3 (Sn,In) phase improved the solder-joint strength. The samples reflowed at 300°C exhibited the best mechanical strength, which was 57.6 kg/cm 2 as reflowed. This In/Ni/Cu/Ni/In multilayer structure is a suitable candidate for high-temperature Pb-free solders.