BGA VIBRATION FATIGUE TEST

摘要

The objectives of the present study are to experimentally: 1) determine the survivability/durability of the solder joints of ball grid array (BGA) packages when subjected to military vibration environment and 2) evaluate the design parameters impacting on BGA solder joint vibration fatigue damage. A test vehicle (TV), on which various sizes of BGA daisy-chained packages are soldered, is first designed and manufactured. Three design parameters, including printed wiring board (PWB) material, conformal coating, and BGA underfill, are used to construct 12 different types of TV configurations. All TV configurations are then subjected to random vibration tests while continuously monitoring solder joint integrity. Based on the measured results, a destructive physical analysis is then conducted to further verify the failure locations and crack paths of the solder joints. Test results indicate that: 1) the use of conformal coating and underfill would prolong BGA solder joint vibration fatigue life; 2) the use of polyimide versus thermount PWB would result in an insignificant effect on BGA solder joint fatigue life; and 3) the BGA solder joint fatigue life could be increased by one-order-of-magnitude (or more) using either reworkable or non-reworkable underfill in BGA packages versus using no underfill. All these test results are recommended to be used for calibrating BGA vibration fatigue life prediction models, which will be presented in other publications. In addition, it is recommended that a parametric study be conducted which includes variations in PWB solder pad size, stencil thickness, etc., to identify critical design factors impacting on the BGA solder joint fatigue life, and then to seek an optimum design. An example of a 313-pin plastic BGA, 352-pin plastic BGA, and 304-pin ceramic BGA is illustrated in the present study.