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

Reliability of the solder bump has been studied by accelerated testing with several experimental techniques. A new thermal fatigue test apparatus usin g thermal conduction was constructed, which could produce temperature gradi ent effects without any additional design of test specimen and control the temperature of specimen easily. For the simulation of temperature change du e to the heat generation of chip, a specimen (chip) was put on a heating pl ate through which heat flux was conducted. A small-sized electromagnetic ty pe fatigue tester and a micro-mechanical testing machine were developed. Hi gh cycle fatigue test was performed by a small-sized electromagnetic type f atigue-tester. The time to failure was determined by measuring the changes in resistance. Using micro-mechanical tester, isothermal fatigue test was p erformed to investigate the optimum shape of solder bumps. The isothermal l ow cycle fatigue test of solder bumps was performed with four different sha pes and the equivalent plastic strain distributions of four different cases were calculated using finite element method.