Shock and thermal cycling synergism effects on reliability of CBGA assemblies

BGAs are now packages of choice especially for higher I/O counts for commercial applications and are also being considered for use in military and aerospace. Thermal cycling characteristics of BGA assemblies have been widely reported. Thermal cycling represents the on-off environmental condition for most electronic products and therefore is a key factor that defines reliability. As a result, much data is available for accelerated thermal cycle conditions, but very limited data is available on vibration and shock representative of aerospace applications. Test vehicles with daisy chain plastic and ceramic BGAs (CBGAs) ranging from 256 to 625 I/O count were subjected to random vibration/shock representative of a spacecraft launch environment. The effect of board rigidity on behavior was also investigated by adding strips to or bonding of board to an aluminum plate. This paper compares accelerated thermal cycles-to-failure data under four temperature ranges before and after thermal random vibration for CBGAs with 361 and 625 I/Os. Stress and strain projections by finite element analysis are also presented.