Low-temperature lead-free SnBiIn solder for electronic packaging

In pursuit of functionality and miniaturization in electronics, 3D integrated packaging requires low-temperature solders. This study explores a novel low-temperature lead-free SnBiIn solder. The solder has an ultimate tensile strength of 43.9 MPa, an elongation after break of 36.5%, and a low melting point of 91.8 °C. It is environmentally friendly with a homogeneous structure. Under controlled conditions of reflow at 150 °C for 5 min, the solder exhibited a solder/Cu(substrate) wetting angle of 32.6° and an average intermetallic compound (IMC) thickness of 2.3 μm—both meeting rigorous electronic industry standards. Furthermore, the Cu/SnBiIn/Cu joint demonstrated a substantial shear strength of 34.4 ± 1 MPa. These results highlight the potential of this lead-free, low-temperature solder for electronic packaging applications.