The development of high scale integration technologies leads to an increase of I/O number and then to larger and larger components. For equivalent dimensions, BGA packages provide more I/O connections capability compared to standard SMT components (J and L leaded packages). Therefore the use of BGA packages seems to be a good alternative to conventional fine pitch technologies. Because of its good dissipation characteristics Ceramic Ball Grid Array package (CBGA) is commonly used, but its thermal expansion mismatch with FR4 substrates and the stiffness of its solder balls induce a critical thermomechanical behavior under thermal cycling. We have performed 2D finite element simulations on CBGA components assembled on FR4 card in order to evaluate the highest stressed regions of the solder joint. The maximum cumulative strain energy has been calculated as a function of the thermal cycling characteristics and of the package size to evaluate the fatigue of the solder joints. Accelerated ageing tests (0°C to 100°C) have been performed on CBGA samples to validate such a global approach. The analysis of the degradation have been performed using direct observation on S.E.M. and also a specific procedure of acoustic imaging allowing the detection of defects located on the inner balls. From the previous FEM simulations results and the experimental data under thermal cycling, we propose a global interpretation, based on general mechanical laws, of the thermomechanical behavior of the CBGA solder joints under thermal cycling. Conclusions about the evolution of the CBGA assemblies criticity with both package size and ball number increase are deduced from this study.