Abstract: Soldering experiments of two kinds of devices QFP32 and QFP48 were carried out using diode-laser soldering system and IR reflow soldering method, and the distribution regulations of the tensile strength of QFP micro-joints with Sn-Pb solder and Sn-Ag-Cu lead-free solder were studied by STR-1000 micro-joints tester, and the characteristics of fracture microstructures of micro-joints were also analyzed by SEM. The results indicate that tensile strength of QFP micro-joints soldered with laser soldering system is larger than that with IR reflow soldering method, and tensile strength of QFP48 micro-joints is larger than that of QFP32 micro-joints. Fracture mechanism of micro-joints soldered with laser soldering system is toughness fracture, while fracture mechanism of micro-joints soldered with IR reflow soldering method includes brittle fracture and toughness fracture.