For the first time, the effects of dielectric film thickness in the dielectric charging process of RF MEMS capacitive switches is presented. Both MEMS switches and MIM capacitors are used to investigate charging phenomena. The contribution of charge injection and dipole orientation has been identified. An empirical law that allows the prediction of stored charge on the film thickness was drawn. Above room temperature, the dependence of thermally stimulated depolarization current on a certain activation energy that is independent of dielectric film thickness allows the inclusion of this behavior in modeling tools.