Under-filled BGA solder joint vibration fatigue damage

The paper (1) experimentally determines the survivability/durability of the solder joints of ball grid array (BGA) with/without under-filled materials when subjected to military vibration environment and (2) develops a vibration fatigue life prediction model, which is qualitatively calibrated by test. A test vehicle (TV), on which various sizes of BGA daisy-chained packages with/without under-filled materials, e.g., Hysol (non-reworkable) and Hacthane (reworkable) are soldered, is first designed, fabricated and subjected to random vibration tests continuously monitoring the solder joint integrity. Based on the measurement 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) ceramic BGA (CBGA) mounted to the same modules will be more susceptible to failure than, the plastic BGA (PBGA) under the same conditions; (2) the PBGA solder joint fatigue life could be increased by one-order-of-magnitude (or more) using either one of under-filled materials in the packages versus using no underfilled material; (3) the use of under-filled material of Hysol could also improve the life expectancy of the CBGA by more than a factor of ten; and (4) only a slight increase in the life of the CBGA with using the under-filled material of Hacthane.