The failure mechanism of electromigration (EM) for electronic packaging technology has garnered interest. Electromigration-caused voids reduce electronic device dependability. Two-step reflow at 250℃ and 210℃ was employed to create SAC305/SnPb micro-hybrid solder connections. Finite element analysis confirmed electromigration failure. After 768 h at 10A, the anode interface IMC thickness increased by 149.8 %, while the cathode IMC increased less. Polarity accelerates anode IMC growth. Electromigration of Cu from cathode to anode causes structural flaws and 44.6 % shear strength loss to 35.1 MPa. Fractures shift from inside the solder joint to the IMC layer becoming brittle. COMSOL simulation demonstrates greatest current density, temperature, and stress at the current inlet and Cu pad-solder joint junction.