Abstract: The mechanical behavior of Sn62Pb36Ag2 solder joints was systematically investigated through shear performance tests and fracture morphology analyses over a temperature range from cryogenic (-196 ℃) to ambient (25 ℃). Results demonstrate that the shear strength increases monotonically with decreasing temperature. A distinct ductile-to-brittle transition was observed at approximately -100 ℃. Below this transition temperature, fractures propagated primarily along the intermetallic compound (IMC) layer, exhibiting transgranular cleavage facets and significant brittleness. Conversely, ductile fracture mechanisms characterized by shear bands prevailed above -100 ℃. Microstructural analysis indicates that the enhanced brittleness under cryogenic conditions stems primarily from restricted dislocation mobility and suppressed thermal activation processes. These findings may offer guidance for material selection in aerospace interconnects operating in extreme environments. For applications at temperatures ≤-100 ℃, solder alloys with superior low-temperature ductility (e.g., indium-based solder alloys) are strongly recommended to ensure operational reliability.