Thermal fatigue reliability analysis of redistributed flip chip assemblies

The thermo-mechanical reliability of redistributed flip chip assemblies is in particular determined by the plastic deformations of the solder joints and by the stresses in the photo-BCB redistribution layers. Finite element simulations and Coffin Manson based reliability models are used to compare the thermal cycling reliability of redistributed and standard flip chip assemblies. The existence of a photosensitive BCB redistribution layer on the chip influences the thermal fatigue of the flip chip assembly. The largest reliability improvement using redistributed chips is achieved by moving the solder joints from the perimeter to the interior of the die resulting in an area array flip chip.