Fatigue and Fracture Assessment for Reliability of Electronics Packaging

Modern electronics products move in the direction of complex, high density, high speed and also thinner and lighter for portability. Reliability of interconnection of electronics packaging has become critical issue. Major functions of electronic packaging are briefly discussed 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 final fracture. A small sized electromagnetic type fatigue tester, micro-mechanical testing machine, and thermal fatigue testing apparatus were specially developed for reliability assessment of electronics packaging. Long term reliability of surface mounted component packaging of under vibration induced high cycle fatigue was assessed with testing and finite element analysis. High cycle fatigue test was performed by the electromagnetic type testing machine. The time to failure was determined by measuring the changes in resistance. Using the micro-mechanical tester, isothermal low cycle fatigue of solder joints in packaging are performed and compared with finite element analysis to investigate the optimal shape of solder bumps in electronic packaging. Fatigue tests on various lead-free solder materials are discussed. Thermal fatigue tests of lead-contained and lead-free solder joints of electronic packaging were performed. Thermal fatigue results are compared with the mechanical fatigue data in terms of inelastic energy dissipation per cycle. It was found that mechanical load has longer fatigue life than thermal load at the same inelastic energy dissipation per cycle. Other advanced experimental methods for reliability assessment of microelectronic packaging are briefly discussed.