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The ceramic ball grid array (CBGA) packages are typically used for high I/O count area array assemblies. As the package size is large, the distance to neutral point is also high resulting in a large thermal deformation mismatch between the CBGA package and the printed circuit board (PCB). In order to cope with this problem, a special solder joint connection is used. As CBGA assemblies are used for high pin count assemblies, a full 3D thermo-mechanical modelling of an assembly to an FR4 board is not possible anymore. Therefore, a modified micro–macro methodology is proposed where only the critical solder joint is modelled in detail, while the other connections are replaced by equivalent connections. For several CBGA configurations, simulation results are correlated to thermal cycling test results. Finally, a parameter sensitivity study shows that the PCB properties have a significant influence on the solder joint reliability.

Proceedings of the 17th European Symposium on Reliability of Electron Devices, Failure Physics and Analysis. Wuppertal, Germany 3rd-6th October 2006; International audience; Dielectric-based RF MEMS capacitive switches were fabricated and characterized for their response to dielectric charging, thermal storage and cycling and to total dose gamma irradiations. The evolution of the switch electromechanical and RF characteristics (actuation and releasing voltages, insertion losses, isolation) were evaluated as a function of the applied stress (temperature or total ionizing dose). It is indicated that the thermal stress has a relatively minor impact on the switches (the switches remained functional with nearly the same electrical properties). Under our particular test conditions, C(V) and S-parameters measurements show that gamma radiation has low to moderate effects on the components behavior