Modern electronics products relentlessly become more complex, higher in density and speed, and thinner and lighter for greater portability. The package of these products is therefore critical. The reliability of the interconnection of electronics packaging has become a critical issue. In this study, the novel testing methods for electronic packaging are introduced and failure mechanisms of electronic packaging are explained. Electronics packaging is subjected to mechanical vibration and thermal cyclic loads which lead to fatigue crack initiation, propagation and the ultimate fracture of the packaging. A small-sized electromagnetic-type bending cycling tester, a micro-mechanical testing machine, and thermal fatigue testing apparatus were specially developed for the reliability assessment of electronics packaging. The long-term reliability of an electronic component under cyclic bending induced high-cycle fatigue was assessed. The high-cycle bending-fatigue test was performed using an electromagnetic-type testing machine. The time to failure was determined by measuring the changes in resistance. Using the micro-mechanical tester, low cycle fatigues were performed and compared with the results of a finite element analysis to investigate the optimal shape of solder bumps in electronic packaging. Fatigue tests on various lead-free solder materials are discussed. To assess the resistance against thermal loads, pseudo-power cycling method is developed. Thermal fatigue tests of lead-containing and lead-free solder joints of electronic packaging were performed using the pseudo-power cycling tester. The results from the thermal fatigue tests are compared with the mechanical fatigue data in terms of the inelastic energy dissipation per cycle. It was found that the mechanical load has a longer fatigue life than the thermal load at the same inelastic energy dissipation per cycle.