Abstract: To meet the demand for high-reliability vertical interconnection in the miniaturization, high integration, and three-dimensional assembly of electronic devices, research on large-sized solder ball bonding technology for double-sided bump interposer was conducted. Sn63Pb37 solder balls with diameters of 1.2 mm and 2.0 mm were prepared using the remelting method, and the investigation was carried out by combining laser ball placement, thermal shock testing (from −55 ℃ to 125 ℃, 200 cycles), random vibration testing (15 g rms), and finite element analysis. The results show that the prepared solder balls exhibit a dense microstructure with uniformly distributed Pb-rich phases; the shear strength of the solder joints exceeds 25 MPa, and a continuous intermetallic compound layer with a thickness of approximately 0.1 μm is formed at the interface. After thermal shock testing, the 0.76 mm solder ball joints experience failure, whereas the 1.2 mm and 2.0 mm solder joints remain stable. After random vibration testing, all small-sized solder joints experience pad peeling, while the large-sized solder joints maintain structural integrity. As the solder ball diameter increases from 0.76 mm to 2.0 mm, the strain energy density decreases from 0.294 MPa to 0.042 6 MPa, a decrease of 85.5%; the fatigue life increases from 259 cycles to 3 605 cycles, an increase of 13.9 times. Large-sized solder balls can significantly reduce stress concentration and improve thermomechanical reliability.