Experimental techniques for fatigue reliability of BGA solder bumps in electronic packaging

Abstract

Reliability of the solder bump has been studied by accelerated testing with several experimental techniques. A new thermal fatigue test apparatus using thermal conduction was constructed, which could produce temperature gradient effects without any additional design of test specimen and control the temperature of specimen easily. For the simulation of temperature change due to the heat generation of chip, a specimen (chip) was put on a heating plate through which heat flux was conducted. A small-sized electromagnetic type fatigue tester and a micro-mechanical testing machine were developed. High cycle fatigue test was performed by a small-sized electromagnetic type fatigue-tester. The time to failure was determined by measuring the changes in resistance. Using micro-mechanical tester, isothermal fatigue test was performed to investigate the optimum shape of solder bumps. The isothermal low cycle fatigue test of solder bumps was performed with four different shapes and the equivalent plastic strain distributions of four different cases were calculated using finite element method.